The entorhinal cortex (EC) is a major gateway between the hippocampus and telencephalic structures, and plays a critical role in memory and navigation. Through the use of various molecular markers and genetic tools, neuron types constituting EC are well studied in rodents, and their layer-dependent distributions, connections, and functions have also been characterized. In primates, however, such cell-type-specific understandings are lagging. To bridge the gap between rodents and primates, here we provide the first cell-type-based global map of EC in macaque monkeys. The laminar organization of the monkey EC was systematically examined and compared with that of the rodent EC by using immunohistochemistry for molecular markers which have been well characterized in the rodent EC: reelin, calbindin, and Purkinje cell protein 4 (PCP4). We further employed retrograde neuron labeling from the nucleus accumbens and amygdala to identify the EC output layer. This cell-type-based approach enabled us to apply the latest laminar definition of rodent EC to monkeys. Based on the similarity of the laminar organization, the monkey EC can be divided into two subdivisions: rostral and caudal EC. These subdivisions likely correspond to the lateral and medial EC in rodents, respectively. In addition, we found an overall absence of a clear laminar arrangement of layer V neurons in the rostral EC, unlike rodents. The cell-type-based architectural map provided in this study will accelerate the application of genetic tools in monkeys for better understanding of the role of EC in memory and navigation. The entorhinal cortex (EC), a major gateway between the hippocampus and telencephalic structures, plays a critical role in memory and navigation. Previous anatomical studies have shown that the connectivity patterns of EC are strikingly different across the layers: superficial layers (layers II and III) provide the main inputs to the hippocampus, whereas deeper layers (layers V and VI) receive outputs from the hippocampus. These patterns are consistent in several species, including rodents and monkeys . In rodeThe EC in various species has been divided into cytoarchitectonically identified subregions of which number has been variable, though often include two main anatomically and functionally defined subdivisions, the lateral and the medial entorhinal cortex , rostral division (Er), lateral rostral division (Elr), lateral caudal division (Elc), intermediate division (Ei), caudal division (Ec), and caudal-limiting division (Ecl) . AlternaOne potential index to clarify the homologous brain regions of LEC and MEC in monkey EC is cell-type-specific molecular markers. In monkeys, the immunoreactivity for RE in layer II has been reported , and thaTwo male macaque monkeys (Macaca mulatta) of 6 years old weighing 9.8 kg and 5 years old weighing 6.7 kg were used in this study . The experimental procedure for monkeys were in accordance with protocols approved by the Animal Welfare and Animal Care Committee of the Primate Research Institute, Kyoto University, and were conducted in line with the Guideline for Care and Use of Non-human Primates established by the Primate Research Institute, Kyoto University.Male adult Long Evans rats of 45–65 weeks weighing 320–390 g and male adult C57BL/6NCrSlc mice of 12–28 weeks weighing 18–33 g were used in this study. The experiments were approved by the Center for Laboratory Animal Research, Tohoku University, and were conducted according to the Guidelines of the National Institutes of Health and the Tohoku University Guidelines for Animal Care and use.Throughout the experiments, the animals were maintained in a cage that was placed inside a safety cabinet. The room temperature (23–26°C) and the light condition (12 h on/off cycle) were controlled. All efforts were made to avoid the animals from suffering.13 gc/ml, 1.5 μl × 3 site/2 track), and 4.8 μl of the AAV2Retro-hSynI-mKO2 was injected into the accessory-basal nucleus of AMG at two rostrocaudally different levels  through a 10 μl Hamilton microsyringe. After the injections, the scalp incision was sutured. The monkey was monitored until the full recovery from the anesthesia.Monkeys were deeply anesthetized with ketamine  and xylazine . During the surgery, the monkey was kept hydrated with a located Ringer’s solution (i.v.). An antibiotic  and an analgesic  were applied at the initial anesthesia. After removal of a portion of the skull, multiple injections of retrograde adeno-associated viral vector (AAV2Retro)  were madRats/mice were deeply anesthetized with ketamine  and xylazine  and were mounted in a stereotaxic flame. The skull was exposed, and a small burr hole was drilled above the injection site. The injection was made by means of a glass micropipette (tip diameter = 20–40 μm) connected to 1 μl Hamilton microsyringe. Coordinates of following injection sites were based on the rat or mouse brain atlas  and calcThree weeks after AAV injection, the monkeys were deeply anesthetized with an overdose of sodium pentobarbital  and perfused transcardially with 0.1M phosphate buffer saline (PBS), followed by 10% formalin dissolved in 0.1M phosphate buffer (PB). The brain was removed from the skull, postfixed in the same fresh fixative overnight at 4°C, and saturated with 30% sucrose in 0.1 M PBS at 4°C. Monkey brains were sectioned in 50 μm coronal planes on a freezing microtome and 10 equally spaced series were collected. Sections were split in the mid-sagittal plane and processed as described below.To visualize the PCP4+ neurons, sections ipsilateral to the injection site were stained with primary antibody, rabbit anti-PCP4  followed by secondary antibodies . To visualize RE+ and CB+ neurons, contralateral sections were stained with primary , MBL #D233-3; 1:1,000, rabbit anti-Calbindin, Abcam #ab11426) and secondary antibodies . For delineation purposes, sections were stained for NeuN with primary  and secondary antibodies .For all immunohistochemical procedures, sections were rinsed 3 × 10 min in PBS followed by 60 min incubation in a blocking solution containing 3% bovine serum albumin (BSA) in PBS with 0.3% Triton X-100 (PBS-Tx). Sections were incubated with the primary antibodies diluted in the blocking solution for 48 h at 4°C, rinsed 3 × 10 min in PBS, and incubated with secondary antibodies diluted in PBS-Tx 24 h at room temperature. Finally, sections were rinsed 3 × 10 min in PBS. To reduce endogenous autofluorescence, monkey sections were immersed in a TrueBlack (Biotium) solution diluted by 70% ethanol for 30 s. The sections were mounted on gelatin-coated slides, and coverslipped using Prolong Diamond Antifade Mountant (Invitrogen #P36961). A series of the adjacent sections were mounted and Nissl-stained with 0.5% Cresyl violet (Acros Organics #AC229630050).3), followed by 4% paraformaldehyde (PFA) in 0.1M PB. The brains were removed from the skulls, postfixed in the same fresh fixative overnight at 4°C, and put in a cryo-protective solution containing 20% glycerol, 2% DMSO diluted in 0.125M PB at 4°C. The brains were sectioned at 40 μm in the horizontal plane on a freezing microtome and six equally spaced series were collected for further processing.One week after Fluoro-Gold injection, rodents were deeply anesthetized with an overdose of sodium pentobarbital  and perfused transcardially with Ringer’s solution .1 In PCP4-stained sections, this results in 12 parameters for each columnar bin: Number of PCP4+ neurons in layers IIa, IIb, III, Va, Vb, VI, and retrogradely labeled (RTG+) neurons in layers IIa, IIb, III, Va, Vb, VI. The same applies to the RE- and CB-stained sections: number of RE+ neurons in layers IIa, IIb, III, Va, Vb, VI, and CB+ neurons in layers IIa, IIb, III, Va, Vb, VI. Based on these parameters, a principal component analysis was conducted in MATLAB (Mathworks) in order to compare the cytoarchitectonic features of the entorhinal subdivisions. The multiple columnar bins which compose each entorhinal subdivision were used as data points, and the 12 parameters for each columnar bin were used as variables. To perform this analysis, all variables were converted to the proportion of the total number of labeled neurons. To compare the soma size of labeled-neurons, optical sections were obtained with a Zeiss Apotome, and the soma size for each labeled neuron was measured in NeuN images using Zen Blue software. Note that the immunofluorescence for NeuN can be observed in the cytoplasm in addition to the nucleus of a neuron.Coverslipped samples were imaged using an automated scanner . PCP4, RE, CB, and retrograde labels were thresholded with Zen Blue software (Zeiss), and the labeled-neurons above the threshold were plotted using illustrator software (Adobe). To compare the distribution patterns of labeled neurons, EC was divided into columnar bins by first dividing layer IV into 200 μm-wide bins, and then, extending the columnar bin throughout all layers. The number of immunohistochemically labeled neuron within each layer in each bin was quantified using image J software.Following previous studies on monkey EC , we cytopost hoc tests to control for multiple comparison. All statistical tests were two-tailed, and thresholds for significance were placed at ∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001. All data are shown as mean ± standard errors.To compare the soma size of labeled-neurons , statistIn previous monkey studies, the entorhinal layers were purely defined by their cytoarchitectonic features . In contLayer I was a cell poor layer beneath the pia which was immunonegative to PCP4. In previous monkey studies, “layer II” was defined as a thin layer of darkly Nissl-stained cells, and “layer III” as the deeper layer separated from “layer II” by a narrow cell-free zone . In addition, despite the mixed distribution of PCP4+ neurons and retrogradely labeled neurons in the rostral EC, retrogradely labeled neurons that showed PCP4+ colabeling were hardly observed . These results indicate that monkey EC layer V is composed of two cell types with distinct molecular identity, soma size, and connectivity, which intermingle in the rostral subdivisions and segregate in different sublayers in the caudal subdivisions.Recent studies in rodents reported that molecularly defined sublayers of entorhinal layer V show distinct connectivity . To examTo examine whether the EC subdivisions can be distinguished based on the above cell-type specific markers, we conducted principal component analyses based on the number of PCP4+ neurons and the NAc-projecting neurons across layers. This resulted in a moderate separation between the caudal EC, that is Ec and Ecl, and the rostral EC, that is Er and Elr, in both subjects . Interesp < 0.001 for layer IIa RE+ cells vs. layer III RE+ cells and layer IIa RE+ cells vs. layer III RE- cells, one-way ANOVA followed by Bonferroni’s multiple comparison test).The distributions of the molecular markers for EC layer II, RE, and CB, were examined in monkey EC, contralateral to the AAV-injection site . SimilarOne prominent feature of CB+ neurons in layer II is that they form periodic clusters, which have been confirmed both in rodent MEC and in human caudal EC . In contPrincipal component analysis based on the number of RE+ and CB+ neurons across layers resulted in a moderate separation between the caudal EC, that is Elc, Ec, and Ecl, and the rostral EC, that is Er and Elr . Ei, howPrincipal component analysis shown in In sections immunostained for PCP4, clear distribution differences of NAc-projecting neurons were observed in layer V between Eir and Eic. In Eic, NAc-projecting neurons were localized in layer Va whereas in Eir, they were also present in layer Vb . In addiIn sections immunostained for CB and RE, differences were mainly observed in the superficial layers especially for the CB-labeling. CB+ neurons tend to cluster in patches in Eir compared to Eic, while the islands of RE+ neurons were more prominent in Eir than in Eic . AlthougOur understanding of the EC has progressed substantially by studies in rodents focusing on the functionally distinct subregions, MEC that processes spatial information and LEC that represents the time and content of episodes . To applIn this study, we focused on cell-type-specific markers and found that Ei can indeed be further divided into rostral and caudal portions on the basis of the distribution of PCP4+ neurons and telencephalon-projecting neurons in layer V. The caudal Ei (Eic) showed similarity to the caudal EC subdivisions, that is, Elc, Ec, and Ecl, showing a clear segregation in the distribution of the two cell types in layers Va and Vb. In contrast, the rostral Ei (Eir) was found to be more similar to the rostral EC subdivisions, that is, Er and Elr, with the two cell types being intermingled in both layers Va and Vb. Although it is unclear whether this cell-type-based border corresponds to the terminal distribution pattern of projections from the presubiculum, we can extrapolate, based on the specific cell marker expression patterns shown here, that the caudal subdivisions including Eic are homologous to rodent MEC, while the rostral subdivisions including Eir are homologous to rodent LEC. In the following sections, we tentatively call the two subdivisions monkey MEC and monkey LEC, respectively.Layer IIa is a thin layer of RE+ stellate cells which project to the dentate gyrus and CA3, whereas layer IIb comprises CB+ pyramidal cells that only show minor hippocampal projections and widespread though sparse telencephalic cortical and subcortical projections. Layer III neurons express PCP4 and project to CA1 and the subiculum. Layer V is composed of layer Va and layer Vb, which mediate the hippocampal information to telencephalic structures. Large PCP4-negative pyramidal cells located in layer Va are the major origin of telencephalic cortical and subcortical projections, whereas small PCP4+ neurons are densely packed in layer Vb and are among the recipients of hippocampal outputs from CA1 and the subiculum.The laminar definition of EC has recently been reconsidered based on the distribution of molecularly defined neurons in rodents . To promThe present data indicate that the laminar organization of monkey EC displays a strong similarity to that of rodent EC with some exceptions. In monkey MEC, the cell-type-based laminar organization was found to be similar to that in rodent MEC: PCP4+ neurons were distributed in layers III and Vb, whereas the neurons projecting to telencephalic structures, as tested with projections to NAc and AMG, were localized in layer Va. Since the soma size of PCP4+ layer Vb neurons is small whereas that of telencephalon-projecting neurons in layer Va is large, the border between layers Va and Vb is also apparent in Nissl-stained sections. The only clear difference between monkey and rodent MEC was the labeling pattern in layer II. The organization of layer II of monkey MEC was rather similar to that of rodent LEC, in that there was a clear segregation between the RE+ layer IIa and the CB+ layer IIb. In addition, CB+ patches were hardly observed in monkey MEC, unlike rodent MEC .In monkey LEC, the cell-type-based laminar differentiation between superficial layers was similar to that in rodent LEC: RE+ and CB+ neurons were found to be confined to layers IIa and IIb, respectively, and the PCP4 expression level of layer III neurons was lower than that in monkey MEC. The RE+ layer IIa neurons were separated by cell-sparse zones to form cellular islands. One exception is the presence of CB+ patches in Er and rostral Ei, which is in line with a previous report . The mosvia neurons in layers II and III (In recent studies, the circuits of entorhinal layer V in rodents were examined, which revealed how the hippocampal information is sent out to telencephalic structures. The main recipients of dorsal hippocampal projections in EC are PCP4+ layer Vb neurons . These l and III . Interes and III . These d and III .In this study, we have shown that monkey entorhinal layer V is also composed of PCP4+ neurons and neurons projecting to telencephalic structures. Although detailed circuit analysis of specific cell types has not yet been carried out in monkey EC, in a previous anterograde tracing study, the intrinsic connections of EC were examined using chemical anterograde tracers . These aIn contrast to MEC, the laminar organization of monkey LEC layer V largely differed from that of rodent LEC, and PCP4+ neurons and telencephalon-projecting neurons did not obey the rodent laminar arrangement but were intermingled in layer V. This raises the possibility that the hippocampal projection may directly innervate the telencephalon-projecting neurons in monkey LEC, and therefore, the monkey LEC mediates the transfer of hippocampal information to telencephalic structures more efficiently than the rodent LEC. It, however, must be noted that despite the mixed distribution, PCP4 and retrograde labeling were hardly colocalized in single neurons in monkey LEC layer V. This points out the other possibility that regardless of the different laminar distribution, LEC layer V neurons are connectionally similar and are embedded within similar circuits, both in rodents and monkeys. To further understand the organization of entorhinal layer V, it is essential to identify the targets of the hippocampal outputs in monkeys. The hippocampal-entorhinal projection has only been examined in detailed in rodents, reporting that the dorsal hippocampal neurons innervate entorhinal layer Vb but not Va . InteresA developmental study in mice reported data suggesting that MEC is derived from the medial pallium similarly to the hippocampus, whereas LEC is derived from a distinct dorsolateral caudal pallial sector . This diThe laminar organization of layer V, as defined by the cell types, is different between the rostral and caudal EC in monkeys. These rostral and caudal portions of EC likely correspond to LEC and MEC in rodents, respectively. In addition, we found that a clear laminar arrangement of layer V neurons, which is evident in rodent LEC, is absent in the rostral EC of monkeys. These observations suggest that LEC in primates may have increased its complexity through evolution, and developed into a uniquely tuned information processing system, serving the efficient transfer of hippocampal output to cortical and subcortical structures. Further investigations are required to fully appreciate the potential relevance of the primate LEC.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The animal study was reviewed and approved by the Animal Welfare and Animal Care Committee of the Primate Research Institute, Kyoto University and the Center for Laboratory Animal Research of Tohoku University.SO and MPW conceived the study design. K-II produced the AAV vectors. KK, ST, AZ, and RY collected the experimental samples in monkeys, both under supervision of MT. TK collected the samples in rodents. RY, TK, and SO analyzed the data. All authors contributed to the discussions that resulted in the current manuscript, which was written by SO and RY, and edited by MPW, K-IT, and MT. All authors approved the final version of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The relations between CRF and SBP revealed the mediation effect of the BFM and the FMI only in boys. Conclusions: Fatness mediated associations between CRF and SBP in boys. Therefore, both CRF and fatness are necessary to maintain positive results of the BP revealed in normal SBP ranges after HIIT.Background: Low cardiorespiratory fitness (CRF), elevated blood pressure (BP), and high fatness are cardiovascular disease risk factors. It remains unknown how fatness affects the influence of CRF on BP. Therefore, the aim was to examine whether the associations between baseline CRF and HIIT-postintervention resting BP were mediated through fatness in adolescents. Material and methods: The sample (n = 64) comprised 28 boys 36 girls aged 16 years. The analysed factors were fitness index- reflecting CRF, body fat mass (BFM), fat mass index (FMI), and body mass index (BMI). Bootstrapped mediation procedures were performed. The mediation analysis was conducted concerning the sex moderation effect. Results: The mediation effect of sex was confirmed; therefore, mediations models were designed separately for boys and girls. The results showed a statistically significant inverse relationship between baseline CRF and post-intervention systolic blood pressure (SBP) in both sexes (boys: B = −0.603,  The worldwide prevalence of obesity, hypertension, and low cardiorespiratory fitness (CRF) are well-documented ,2,3. VerA high level of fatness is a risk factor for elevated blood pressure (BP) in adolescents . ContrarPhysical activity (PA) is an effective way to decrease whole body fat and resting BP and improve CRF ,13,14. TOne of the most effective methods for improving fitness and body composition is high-intensity interval training (HIIT). Evidence from previous studies support a positive influence on body mass index (BMI), waist-to-hip ratio (WHR), and whole BFM ,18,19. TTo date, little is still known about the possible ways HIIT affects BP, especially the role of CRF and BF at the baseline (preintervention) concerning effects in resting BP after the intervention, though single studies have suggested that whole bodyweight could mediate the relationship between CRF and BP ,24,25, oThus, considering the relationship between cardiorespiratory fitness, fatness, and resting blood pressure after the intervention of the high-intensity interval training ,9,10,11,Therefore, the main aim of the work was to examine whether the associations between CRF and postintervention resting BP (both SBP and DBP) were mediated through body fatness in adolescents. Specifically, we put forward four detailed questions: (1) Did the resting BP after HIIT intervention depend on CRF at baseline? (2) Did the CRF associated with fatness affect resting BP after HIIT intervention? (3) Did the effect of CRF on resting BP after intervention disappear after including fatness  into the model—other words: could fatness indices act as a mediator in the relationship between CRF and BP? (4) Did sex moderate such potential associations? Although the main mediator tested in the mediation model was body fat mass (BFM in kilograms), the effectiveness of the fat mass index (FMI) compared to body mass index (BMI) as the mediators were also tested. Based on the procedure proposed by Baron and Kenny , the folThis study was part of the project “Physical activity and nutritional education in preventing civilization diseases—theoretical aspects and practical implications for the secondary school physical education program”. The project was a school-based prospective study carried out in one of the secondary schools in Wroclaw—a city in the southwest of Poland. The project aimed to search the methods supporting standard education in increasing the intensity of exercises to adjust body composition, motor performance, cardiorespiratory fitness, and cardiovascular functions. High-intensity interval training was an intervention program implemented into PE lessons. On the other hand, part of the project was an educational campaign on the proper nutrition of adolescents. A detailed description of the sampling, full number of participants, recruitment approaches, intervention design, and data collection, in addition to several analyses of the effectiveness of HIIT on CRF, body composition, musculoskeletal fitness, including comparisons between experimental and control groups, effects of HIIT in groups with different fat mass level and between normal and hypertensive adolescents, were published elsewhere ,28. The study sample included 73 individuals who took part in the HIIT intervention program. The participants were in three classes, randomly assigned to the experimental group . Regarding aim, the results only experimental group were used in this work. Furthermore, we decided to study the mediation effect of fatness in the relationship between baseline preintervention CRF and postintervention SBP and DBP only in adolescents with no hypertension. Therefore, the results of nine individuals were excluded before starting mediation analysis. In detail, three boys and six girls presented values of SBP or DBP above the threshold of hypertension .The final analysis involves 64 adolescent students—28 boys aged 16.17 ± 0.30 and 36 girls aged 16.11 ± 0.39. The participants were volunteers, and they could quit at any time. The students and their parents or guardians were informed about the objectives and rules of the study. The school principal, parents and study participants gave written informed consent before participation. Measurements were taken before (baseline variables) and after the 10-week intervention (postintervention) in one day from 8:00 a.m. to 1:00 p.m. Participants were asked to excrete, avoid physical activity, avoid excessive drinking of liquids, and keep their typical morning patterns directly before measurements.Body height was measured with an accuracy of 0.1 cm, using anthropometers . Bodyweight and body fat mass (BFM) was measured using an InBody230 body composition analyzer , which was positively validated as a reliable tool. High intraclass correlation coefficients indicated very high reliability for BF% (≥0.98), FM (≥0.98), and FFM (≥0.99), as well as the low standard error of measurement . 2)—was calculated using the following formula:Based on the values of height and weight obtained, the index of relative body mass—BMI (kg/mBased on the body fat mass results—fat mass index (FMI) was calculated from a similar formula such as BMI:In schemes of calculated models, explanations of associations between different variables, and overall interpretations, the term FAT was used to generalize the description of all fatness variables .p = heart rate within 1.5 min after the subject stopped the test.The physical fitness index (FI) that defines cardiovascular fitness (CRF) was determined using the Harvard Step Test. Before each test, a Polar H1 heart rate monitor was fitted to each student. Participants stepped up and down on a 41.3 cm high stool at a pace of 30 cycles  per minute, with a metronome set at 120 bpm. The exercise continued for up to 300 s, less if participants became fatigued. Resting heart rate, changes during exercise, and recovery pulse was measured. Recovery pulse was recorded within 1.5 min of recovery. Heart rate monitors sampled participants pulses at 5-s intervals and were transmitted to a smartwatch . FI was calculated using the following formula [Due to performing the study in school settings , the intensity of the exercises was adjusted to the study subjects who do not participate in any sports type. The established HIIT intensity was safe in order to avoid any side effects such as dizziness or faintness. Moreover, the effort intensity was acceptable for the pupils; therefore, they did not refuse participation. Simultaneously, it was possible to achieve broad positive effects associated with the HIIT intervention .In this work, we used the results of resting blood pressure after a 10-week intervention. Automatic Blood Pressure Monitor—Omron BP710 measured blood pressure parameters. Participants were asked to sit quietly for 10 min before measurements. Readings of resting SBP and DBP were taken three times in 10-min intervals. The mean value of the three measurements was recorded into the database. As aforementioned, the assumption in this work was non-hypertensive blood pressure. The procedure of classifying the adolescents based on the systolic and diastolic blood pressure measurements met the criteria contained in the National High Blood Pressure Education Program (NHBPEP) Working Group published in the 4th Report (IVR) . AccordiP = 133, C95/DBP = 82. Similarly, we adopted girls’ values: C95/SBP = 130, C95/DBP = 81. Proper and adequate percentiles used in this work were calculated for Polish adolescents . We usedThe above description of the HIIT intervention was presented elsewhere . Here, bEvaluation of the intensity of the workout was based on the Tanaka formula:Using the Polar H1 , participants’ heart rate was measured and was established in the range of 75–80% HRmax (145–157 heartbeats/min) to perform the HIIT. p = 0.05. Statistica V. A 13.0 statistical package  was used to calculate descriptive statistics.Descriptive statistics of the measurements: FI, BFM, FMI, BMI and SBP, DBP are presented as means, SDs, and 95% CI and were calculated separately for boys and girls . MediatiBoth sexes—male and female—were in the normal range of body mass index and the level of body fat, suggesting healthy fatness (not overweight nor obesity). Dispersion of all fatness variables suggested very consistent groups. Whereas both groups, boys and girls, received very low results of fitness index locating their cardiorespiratory fitness in the very poor category. The mean value of systolic blood pressure was lower in boys, while girls received a mean value very close to standard 120 bps, while diastolic blood pressure was lower in girls than boys .p = 0.010; girls B = −0.394, p = 0.037), but not significant (though negative) on DBP . These results suggested that lower CRF at the baseline is significantly associated with higher post-intervention systolic blood pressure and not significantly with diastolic blood pressure. One of the study’s objectives was to investigate the effects of the baseline CRF on post-intervention SBP and DBP in adolescents. Calculated total effects, extracted from moderated mediation model, was an indicator of the influence of the CRF on SBP and DBP.. Results calculated for males and females separately confirmed the significant and negative impact of CRF on SBP  and dependent variable (DV) to start mediation analysis, this step is controversial. Shrout and Bolger  proved tAnother study’s objective was to assess the potential moderation role of sex in mediation models. This effect was examined before the main mediation analysis, which allowe the adoption of a proper analytic strategy . The hypothesized model of moderated mediation is presented in p > 0.05); this meant differences in the element of the mediation model between both sexes. Lack of significant interaction (p > 0.05) meant the same effect in both sexes’ elements of the mediation model. Moderation effects were represented by statistically significant interactions between categories of the moderator (sex: boys and girls) and paths of mediation model: 1. direct effect of CRF on BP; 2. indirect effect’s component: CRF on FAT; 3. indirect effect’s component: FAT on BP. Suppose there was a significant interaction  on the dependent variable disappears after including the mediator. Both paths (a and b) related to the mediator are significant. Analysis was conducted separately for each potential mediator . Results are presented in As already mentioned above, the total effect (path c) of baseline CRF on post-intervention SBP was statistically significant, and, conversely, the same effect on DBP was not statistically significant. Therefore, the mediation effect that occurs was determined by the statistical significance of the indirect effect (paths ab) and the insignificance of the direct effect (path c’).p = 0.009), and BFM was positively related to post-intervention SBP . Moreover, after including the mediator, the association between CRF and SBP (direct effect—path c’) was no longer significant (p = 0.076). Therefore, all hypotheses were confirmed—mediation effect was present, and preintervention level of BFM acted as mediator. Conversely, there was no mediation effect of the BFM in the model constructed for postintervention DBP. Baseline CRF and BFM were not associated, as well as there was no significant connection between BFM and DBP. Considering non-significant total effect and direct effect, no relationship between CRF and DBP can be concludedMediation results with BFM as a mediator are shown in In girls, the mediation effect of BFM in the relationship between CRF and SBP was not observed. The statistically significant total effect was still significant after introducing BFM as a mediator. Moreover, both indirect components (paths a and b) were insignificant. Thus, BFM was no mediator in girls, but baseline CRF independently affected post-intervention SBP. In the case of DBP, similarly to boys, the mediation effect of BFM on DBP was not observed. The results of mediation analysis confirmed the aforementioned moderating role of sex in the case of SBP  and lack moderating effect in case of DBP .p = 0.057). Moreover, CRF was significantly and negatively related to FMI  and FMI was significantly and positively associated with SBP . Thus, also, in this case, all hypotheses were confirmed. Mediation effect was indicated, and FMI (similarly to BFM) played the role of a mediator. In the case of postintervention DBP, both total and direct effects of mediation were statistically significant. Both paths of the indirect effect of mediation (a and b) were not significant. Therefore, FMI was no mediator. Moreover, there were no associations between CRF, FMI, and post-intervention DBP.In boys, the initial significant total effect of baseline CRF (negatively associated with postintervention SBP) was no longer significant after including FMI as mediator .p = 0.019 in boys, p = 0.036 in girls). In contrast, both indirect paths (a and b) were insignificant. Therefore, there was no mediation effect. In the case of DBP, there were no mediation effects, both in boys and girls.This study showed a statistically significant inverse relationship between baseline cardiorespiratory fitness and post-intervention systolic blood pressure. The associations between cardiorespiratory fitness and postintervention diastolic blood pressure were not observed (either in boys or girls). After including the third variable, examining the character of the relations between CRF and postintervention SBP revealed the mediation effect of the BFM and FMI in boys but not in girls. Thus, a moderated mediation was observed, which was manifested in the fact that the influence of the baseline CRF on post-intervention SBP in girls was autonomous and independent of fatness. There was no mediation in the case of BMI, either in boys or girls. These findings expand current knowledge about the importance of fatness as a feature mediating negative associations between CRF and BP after the intervention program.The present study, similar to previous ones ,36, showCRF and fatness are considered health predictors and cardiovascular disease risk factors . Very stOn the contrary, the results of this work showed no relationship between BMI and CRF . It is difficult to interpret this result. Probably, it depended on a small number of participants. Considering that there was the effect of CRF and BFM and FMI, it can be concluded that BMI is a less sensitive body fat measurement for mediating procedure than total body fat mass or fat mass index, particularly concerning a small group of individuals. Fatness, particularly a very high level of fatness, is strongly linked to blood pressure. The dependence is positive—the higher the fat level, the higher the blood pressure level. Thus, overweight and obesity are very closely linked to hypertension. Obesity causes functional and structural changes in the microcirculation that impair microvascular functions underlying elevated blood pressure . The expThe main finding in this study is the mediation effect of fatness  in the relationship between CRF and SBP. It is difficult to explain why the mediation effect was not observed in DBP. Moreover, the mediation effect was observed only in males. Thus, it can be concluded that moderated mediation was revealed. This meant that categories of the factor moderating phenomena changed the final results. In this case, sex is a moderator; therefore, the relationship in males is different than in females. The mediation mechanism assumes that the independent variable influences the mediator, and the mediator affects the dependent variable. So, the independent variable’s total effect is divided into indirect effects through a mediator. Based on the mechanism mentioned above, our results suggested that CRF at baseline probably ameliorates the fatness level and fatness and affects blood pressure. Our results are convergent to previous studies with mediation analysis. Inverse associations between CRF and BMI, body fat percentage (BFP) or waist-to-hip ratio (WHR), as well as an inverse relationship between these fatness measurements and blood pressure, with simultaneous lack of influence of the CRF on BP , were observed ,38. The Our mediation analysis gave a new insight into understanding the relationship between fatness, CRF, and SBP. It can be suggested that BFM and FMI are more sensitive measurements than BMI to detect the mediation role of fatness in associations between independent and dependent variables (CRF and SBP in this case). However, the mediation role of fatness was moderated by sex; mediation was observed only in males. The lack of mediation, but the direct association between CRF and SBP, independently of fatness, suggested the necessity of enhancing the importance of aerobic fitness as a health indicator in girls.The strength of this study includes its intervention design. Such a project gave new insight into how high-intensity interval training may affect blood pressure and how this effect depends on the level of fatness—the interaction design allowed to make cause–effect interferences. This study has several limitations. The first is its small number of participants. In addition, participants were homogeneous concerning age. Groups of different ages  should be considered. Another limitation is the lack of other relevant covariates such as lifestyle elements . Findings cannot be extended to the entire population of polish youth as the sample was not nationally representative. Measurement of CRF should include the indirect evaluation of VO2max with an accurate field test.In conclusion, the results of this intervention study showed that baseline cardiorespiratory fitness impacted only post-intervention systolic blood pressure, but there was no significant influence on diastolic blood pressure. Moderation analysis, carried out initially, revealed sex as a factor modifying mediation models. In girls, CRF acted autonomously, without the mediation of fatness, whereas in boys, the influence of the CRF on the SBP was not autonomous, but fatness acted as a complete mediator in the inverse associations between CRF and SBP, after high-intensity interval training in adolescents. Thus, the positive effect of the intervention program  on systolic blood pressure was mainly boys with better baseline cardiorespiratory fitness and relatively low baseline fatness . Therefore, the suggestion that optimal cardiorespiratory fitness and fatness levels were essential to maintain balanced (far from hypertension) post-intervention systolic blood pressure contributes to the comprehension of the relationship between the relationship and the triad of main factors of cardiovascular health. Findings from this work can be considered in preparing interventions focusing on the effects of cardiovascular health in youth. Interventions should be tailored separately for males and females, and effective methods for both cardiovascular functions should be sought. Body fat mass and fat mass index proved to be more accurate measurements and more perfect indicators for the mediating role of fatness than BMI.


The aim was to analyze the morningness/eveningness (M/E) effect on suicidal ideation through sleep and depressive symptoms mediators with school shift  as moderator. In this study, 586 Mexican adolescents, with a mean age of 16.31 ± 0.92, from a public high school in a double-shift school system (298 from the morning shift and 288 from the afternoon shift) participated. Measurements of sleep, morningness/eveningness (circadian preference), depressive symptomology, and suicidal ideation were completed. Adolescents in the afternoon shift reported a later rise time, bedtime, greater time in bed sleep length, and less social jet lag than in the morning shift. Considering the moderated-mediated analysis, circadian preference and suicidal ideation were mediated by both depressive symptoms and school day’s sleep length in the morning shift. In the afternoon shift, no mediation effect was significant. When weekend sleep length was considered in the model, only depressive symptoms had a mediating effect between circadian preference and suicidal ideation in the morning shift; no significant mediating effect was found on the afternoon shift. The results suggest that an afternoon school schedule may act as a protective factor for the adolescent’s mental health and may represent a viable option for future interventions. Studies have reported that having a short sleep duration on school days and poor sleep quality during adolescence may lead to depression ,2. FurthRecent clinical reviews about the relationship between sleep duration, depression, and suicidality in adolescents concluded that sleep deprivation significantly predicted higher levels of depressive symptoms and suicidality . Park etThis issue becomes highly relevant in the adolescent stage for two reasons. On one hand, because sleep duration is shorter during the school week and longer on the weekend, adolescents’ sleep delay is relatively long compared to children’s and adults’, leading to shorter time in bed during the week due to the early start time of school. Few studies have differentiated both school and weekend sleep duration and its relationship with depression and suicidality. On another hand, most of the studies have been carried out in the morning shift, so it would be very interesting to analyze the M/E-sleep-depression-suicidality relationship in the afternoon shift. During the lifespan, first, there is a shift towards eveningness during the age of puberty, and second, a shift back towards morningness, which could be viewed as a biological marker of the end of adolescence. After reaching adolescence, most people gradually become more and more morning-type. The shift to eveningness occurs around the age of 12–13 years and school start times remain scheduled at early morning hours; this misalignment between biological (evening preference) and social (early school start time) factors has been associated with the greater difficulty of evening types to cope with environmental and social demands. Goldin et al.  have sugThe aim of this study is twofold: first to assess the mediating role of sleep and depressive symptoms in the relationship between M/E and suicidal ideation, and second, to assess if the aforementioned mediation model is moderated by morning and afternoon Mexican school shifts.The participants were 586 adolescents at a public high school in Reynosa, Tamaulipas (latitude 26°1′00 and longitude 98°14′00) in northeastern Mexico (252 boys and 334 girls). The overall mean age was 16.31 ± 0.92 (mean ± SD) years, and the age range was 15 to 18 years. There were 298 adolescents from the morning shift (school schedule from 07:00 to 13:20), of whom 139 were boys and 159 girls, and 288 adolescents from the afternoon shift (school schedule of 14:00 to 19:30), of whom 113 were boys and 175 girls.Questions about rising times and bedtimes on weekends and weekdays were adapted from the School Sleep Habits Survey . SeveralSocial jet lag was calculated according to the formula indicated by Wittmann et al.  considerTo obtain mid-sleep, we calculated the middle of time in bed on weekends and weekdays used by Wittmann et al. .n = 178), neither (n = 247), and morning (n = 161) types. Furthermore, the cut-off points separated evening (n = 115), neither (n = 112), and morning (n = 61) types for the afternoon shift and evening (n = 63), neither (n = 135), and morning (n = 100) types for the morning shift. The internal consistency  for this sample was α = 0.62.The Spanish version of the Morningness-Eveningness Scale for Children (MESC) ,15 was uThe Mexican version of Roberts Suicidal Ideation Scale ,17 was uThe Mexican version of the short version of CES-D (CESD-7) was used . It follMexican public high schools follow the same three-year school program scheme as the public secondary school, as described in Arrona-Palacios and Díaz-Morales , but insp2) was used as a measure of effect size according to Cohen [Multiple analysis of covariance  was performed to test school shift and sex effects on sleep variables, M/E, suicidal ideation, and depressive symptoms. Partial eta-squared .All analyses were run using the Statistical Package for the Social Sciences program IBM SPSS Statistics 25.0,  and PROCESS version 3.5 . There was a greater percentage of morning types in the morning shift than in the afternoon shift (57.4 vs. 39.9) and in the afternoon shift, there was a greater percentage of evening types than in the morning shift (22.9 vs. 9.1). In addition, considering school shift and depressive symptoms, no significant differences were found , although the percentage with depressive symptoms of morning shift students was greater than those of the afternoon shift (55.4 vs. 49.7). For suicidal ideation, a significant difference was found , morning shift students reported a greater percentage of suicidal ideation than afternoon shift students (36.2 vs. 24.3).Considering school shift and morningness/eveningness, significant differences were found  on sleep habits. A preliminary analysis indicated that girls woke up somewhat earlier than boys; for the rest of the sleep variables, there were no significant differences . = 4.54, p ˂ 0.01, F = 5.18, p ˂ 0.05, respectively). Post hoc comparison  indicated that the difference in bedtime and rise time between girls and boys was greater in the afternoon shift  than in the morning shift .Considering school shift, on weekdays, students from the morning shift went to bed earlier, woke up earlier, and reported a shorter time in bed than students from the afternoon shift. During the weekend, adolescents from the morning shift went to bed earlier and woke up earlier than those from the afternoon shift. No significant difference was found with time in bed . Also, tp < 0.001) indicated that girls reported more depressive symptoms than boys in the morning shift (10.23 vs. 8.17).A second MANCOVA considered the effects of school shift, sex, and age (covariable) on M/E, Depressive Symptoms, and Suicidal Ideation. The results indicated that girls reported more symptoms of depression than boys . No sex To test the morningness/eveningness effect on suicidal ideation through sleep and depressive symptoms mediators, with school shift as the moderator and sex and age as covariables, we tested three moderated-mediation models, changing the measure of sleep as the mediator  in each of them.p < 0.05), whereas in the afternoon shift, the more morningness, the less school time in bed , t = −1.92, p < 0.05).The first moderated-mediation model (sleep measured as school time in bed) indicated that, regarding school time in bed see , in the p < 0.001), whereas in the afternoon shift, this relationship was weaker , t = −2.18, p < 0.05).Regarding depressive symptoms, in the morning shift, the more school time in bed, the less depressive symptoms , t = −3.57, p < 0.001); this is more apparent than in the afternoon shift , t = 6.83, p < 0.001).Considering suicidal ideation, in the morning shift, the greater the presence of depressive symptoms, the greater the suicidal ideation , t = 9.85, The indirect effect of depressive symptoms by school shift was significant ), indicating that the effect of the M/E on suicidal ideation through depressive symptoms occurs in the morning shift.Finally, the indirect effect of school time in bed and depressive symptoms by school shift was significant ), indicating that the effect of M/E on suicidal ideation through school time in bed and the depressive symptoms occurs in the morning shift.In the second moderated-mediation model, considering the weekend time in bed instead of school time in bed as a mediator see , any of Similar to the previous model, the indirect effect of depressive symptoms by school shift was significant ), indicating that the effect of M/E on suicidal ideation through depressive symptoms occurs in the morning shift.Finally, in the third moderated-mediation model, considering social jet lag instead of school time in bed and weekend time in bed as mediators see , only thPrevious studies have found that depression mediates the relationship between M/E and suicidality. The first aim of the present study was to examine whether this relationship occurs in the afternoon shift, since most previous studies have been conducted in the morning shift, where evening adolescents are less aligned with the morning social clock imposed by the school schedule. The results of the present study confirm such a mediation effect in the morning shift but not in the afternoon shift, suggesting that, during adolescence, the afternoon shift is beneficial for health.The second objective was whether the consideration of weekly sleep time, weekend, or social jet lag, together with depression, was implicated in the mediation between M/S and suicidal ideation. The results indicated that only school time in bed together with depression mediated the relationship between M/E and suicidal ideation in the morning shift. Neither weekend time in bed nor social jet lag were significant mediators.This study has reported for the first time the relevance of the morning and afternoon school shift, as well as school and weekend sleep length, in the morningness-eveningness-depression-suicide relationship. The differences in sleep habits according to school shift were the expected: adolescents from the afternoon shift followed the same trend of getting up late, slept longer, and experienced less social jet lag than adolescents in the morning shift, similar to previous works ,10,22. IThe results indicated that the prevalence of depressive symptoms was similar in adolescents in the morning and the afternoon shift, but suicidal ideation was more prevalent in the morning shift. When considering the mediation analysis, M/E and suicidal ideation were fully mediated by both depressive symptoms and school day’s sleep length in the morning shift. In the afternoon shift, no mediation effect was significant. Furthermore, when weekend sleep length was considered in the mediation model, only depressive symptoms exerted a mediating effect between M/E and suicidal ideation during the morning shift, while there was no significant mediating effect on the afternoon shift.The majority of the studies on the relationship between sleep duration, depressive symptoms, and suicidal ideation have been carried out considering a morning social environment and found that the more sleep-deprived are the adolescents, the more depressive symptoms or suicidal ideations ,6. In ouEffectively, depressive symptoms and sleep length both weekdays and weekends were related to suicidal ideation, but the relative contribution of M/E was different according to the school shift. Thus, greater eveningness was associated with suicidal ideation (direct effect) only in the morning shift, and this relationship was partially mediated by depressive symptoms and school days and weekend sleep length (indirect effects). On the other hand, in the afternoon shift, these relationships were not significant. To the extent of our knowledge, this is the first report considering these complex relationships between M/E-depressive symptoms-suicidal ideation by assessing weekdays and weekend sleep duration in morning and afternoon school shifts.These results add evidence about the negative consequences of misalignment between adolescent internal rhythm and social external cues, such as school timetables, at least in the morning shift. Previous studies conducted with adolescents (mostly in morning shifts) have found that eveningness is a risk factor for health with a higher index of depression  and suiczeitgeber that synchronizes the circadian rhythms of adolescents [zeitgeber [In earlier investigations, the school start time was considered an important social lescents . Howeverlescents ,10,11,22lescents , which ieitgeber . Intereseitgeber ,33,34.One of the hypotheses on the relationships between circadian preference and depressive symptoms is that personality traits, such as neuroticism, could be implicated . Also, sThere has been a general need for schools around the world to implement later school start times. Delaying school start time may help improve mental health, well-being, healthy weight, and academic performance ,37. MoreSeveral limitations in the current study must be acknowledged. First, this was a cross-sectional study and, according to Sobel , mediatiThe main findings suggest that because afternoon shift students may have adjusted or synchronized with the late circadian preference, no direct effect of morningness-eveningness and suicidal ideation was mediated by depressive symptoms and school or weekend sleep length; all this indicates that the afternoon school schedule may act as a protective factor for an adolescent’s mental health and development.


BL/L was a risk factor for the occurrence of SPCs as acute myeloid leukemias ), Hodgkin lymphomas  ) and Kaposi sarcomas ). These results may assist the development of diagnostic and clinical recommendations for BL/L.Burkitt lymphoma/leukemia (BL/L) is an aggressive oncohematological disease. This study evaluated the population-based prognosis and survival on BL/L as well as if BL/L behaved as a risk factor for the development of second primary cancers (SPCs) and if other first tumors behaved as risk factors for the occurrence of BL/L as an SPC. A retrospective cohort using the Surveillance, Epidemiology and End Results (SEER) Program (2008–2016) was performed. Kaplan–Meier, time-dependent covariate Cox regression and Poisson regression models were conducted. Overall, 3094 patients were included . The estimated overall survival was 65.4 months . Significantly more deaths occurred for older patients, black race, disease at an advanced stage, patients without chemotherapy/surgery and patients who underwent radiotherapy. Hodgkin lymphomas  (RR, 7.6 (3.9–15.0;  World Health Organization Classification of Tumors of Haematopoietic and Lymphoid Tissues (WHOc) being the most currently used, with previous publications in 2001 [Burkitt lymphoma (BL) is an aggressive B-cell non-Hodgkin lymphoma (NHL) with an extremely short doubling time that often affects the extranodal sites or manifests as acute leukemia (Burkitt leukemia: BLK) . The dia in 2001 , 2008 [4 in 2001 . The BL  in 2001 . Subsequ in 2001 .Three epidemiological clinical variants of BL exist. Endemic BL (eBL) occurs in equatorial Africa and malaria-endemic regions, being the most common childhood malignancy . Sporadic BL (sBL) occurs worldwide, mainly in children and young adults  and immunodeficiency-associated BL (iBL) is usually related to HIV-positive individuals (6 cases per 1000 AIDS cases) . sBL patCross-sectional and cohort studies are important tools for identifying the distribution of a specific disease in a population to explain possible factors related to its cause and diseases outcomes and to understand the interference of social and clinical factors in the disease risk . PreviouThus, in addition to evaluating the prognosis and survival of BL/L patients, the main aim of this study was to evaluate the primary cancers that behaved as risk factors to the development of BL/L as an SPC as well as the risk of BL/L providing the occurrence of other SPCs in a time period from 2008 to 2016 in the USA using the SEER Program database.n = 3094). For risk factors analyses, patients with any cancer other than BL/L in this same date restriction were also included . Specifically for the incidence calculation, the total population used by SEER*Stat was of 786,813,193 and the displayed rate was cases per 1,000,000.This was an observational, analytical and retrospective cohort study. Data were collected from the SEER Program database  . The incThe variables were extracted as follows: age at diagnosis, Ann Arbor staging, chemotherapy, histology/behavior , origin, primary site, primary cancer by international rules (PIR), race, radiotherapy, record number, sex, site (ICD-O-3/WHO 2008), surgery of primary site, survival (months), vital status and year of diagnosis. The definition of the variables according to the specific document from the SEER Program  is avail® v.20 software . The risk relative (RR) calculation of the bivariate analysis was performed using BioEstat® v.5.3 software . Values of p < 0.05 were considered statistically significant for all analyses and point estimates are shown along with the 95% confidence interval (CI).All statistical analyses were performed using SPSSDescriptive statistical analyses were performed. The Kolmogorov–Smirnov test showed the non-normal distribution of the majority of the continuous variables, which were reported as the median, interquartile ranges  and minimum and maximum values (range). The normally-distributed continuous variables were reported as the mean, standard deviation (SD) and standard error (SE). The categorical variables were reported as their absolute and relative frequency.The Kaplan–Meier method was performed to estimate the survival of the patients. The outcome was the overall survival (OS) (dependent variable), represented through the ‘vital status’ variable. The mean OS survival time (in months) was estimated by the interval between the date of the BL/L diagnosis until the date of the patients’ death (due to this disease or other causes) or right censorship . The statistical comparison of the Kaplan–Meier curves at different moments of the study follow-up was assessed through Breslow , Tarone–Ware and log rank (Mantel–Cox) tests.A time-dependent covariate Cox regression model  was used to investigate the prognostic factors associated with the OS. This model type was selected due to the lack of proportionality observed in the survival curves  from the Kaplan–Meier graphs . The sizThe variable ‘record number’ was chosen for the risk factor analysis. This variable sequentially numbers the tumors of a person, which has its ordered values based on the date of diagnosis and then the sequence number . Only caThe International Agency for Research on Cancer (IARC) defines primary cancer as the one that originates in a primary site or tissue and is not an extension nor a recurrence nor a metastasis . In our n = 148; ‘controls’, n = 334,597) and also if BL/L (as a first primary cancer) behaved as a risk factor for the occurrence of other SPCs . An SPC is defined as a new primary cancer that occurs in a person who has had cancer in the past and it may occur months or years after the original (primary) cancer was diagnosed and treated [We evaluated which first primary cancers acted as risk factors for BL/L occurrence as an SPC . The estimated incidence of the disease was 3.9 cases per 1,000,000 inhabitants  [n = 231; 7.5%) and 45–49 years   . The med.8%) see . AccordiA total of 10 out of 3094 patients were considered as missing by the SEER*Stat software. Thus, a survival analysis was performed with 3084 patients. In the 108 months of follow-up (2008 to 2016), a total of 1177 deaths (38.2%) for any cause occurred. The mean OS was 65.4 months . The time-dependent Cox model regression  showed the following factors associated with a worse prognosis for BL/L: population ageing, black race, disease in stage IV by Ann Arbor staging, no chemotherapy and no surgery on the primary site. No radiotherapy was associated with a good prognosis. Similar results were obtained with the multivariate analysis that additionally showed males associated with a worse OS prognosis when compared with females. In addition, the multivariate analysis showed that two primary sites  behaved as a worse prognosis for BL/L. All values of OS outcome  are shown in p = 0.017); Hodgkin lymphomas (HLs)  ; Kaposi sarcomas ; liver cancers  and trachea, mediastinum and other respiratory tumors . The median time until diagnosis of BL/L as an SPC was of five years .p < 0.001); anus, anal canal and anorectum tumors ; HLs   and Kaposi sarcomas . On the other hand, there was a decrease in the incidence of lung and bronchus cancer as an SPC . The median time until the presentation of other SPCs was of two years .BL/L behaved as a risk factor for the occurrence of the following SPCs: acute myeloid leukemia (AML)  and they usually have an aggressive clinical course and a worse prognosis than BL [The international classification of BL was revised in 2008 and 2016. The cases initially classified as an atypical morphological variant of BL (‘Burkitt-like lymphoma’) in WHOc 2001  were rea than BL . In our Our results showed that a few prognostic factors negatively impacted on the OS of BL/L patients. Aging was one of them. In the past decades, the significant increase in somatic mutations in animal and human cells damaged the genetic material of patients, resulting in a greater mortality from cancers at older ages including BL/L . StudiesBlacks were also associated with a worse prognosis for OS leading to a greater risk of dying from BL/L, which may be explained due to socioeconomic features. Wang et al. (2008) studied elderly patients with NHL and highlighted that African-Americans presented a lower educational level, income and socioeconomic status than Caucasian patients. Consequently, the proportion of patients on chemotherapy was lower among blacks and a poorer socioeconomic status was significantly associated with a higher risk of mortality . HoweverAlmost half of the patients in our study presented stage IV BL. Liu et al. (2019) showed the difficulty in finding BL cases at earlier stages (I and II) . In our The bivariate analysis of the time-dependent covariate Cox regression showed the involvement of certain primary sites at diagnosis by BL/L as being statistically associated with a worse prognosis. The GIT was the second most frequently involved extranodal site as a primary diagnostic site while skin, breasts, the CNS and glands had less than 5% involvement each. sBL has an important abdominal involvement (affecting up to 5% of GIT NHL cases in the North American population) followed by the head and neck, nose, oropharynx and tonsils ,38.Patients not treated with chemotherapy or those who underwent radiotherapy had higher risks of death. Chemotherapy is the standard BL treatment . ProphylNHL comprises of a heterogeneous group of hematological diseases varying according to their biological characteristics. Each NHL subtype may have a different treatment, prognosis, clinical response and survival. Consequently, the risk for developing other cancers may also differ between these subtypes ,17,40. IThere was an overall SPC risk 25% higher in patients who had a first NHL compared with the reference population. However, confounding factors such as age, sex, staging, follow-up time, number of chemotherapy agents and radiotherapy sessions might influence this outcome . In addiWe found that lung and bronchus cancers could decrease the occurrence of BL/L as an SPC as well as BL/L as a first primary cancer in the patient’s life decreased the incidence of these tumors and breast cancer as SPCs. These results should be interpreted with caution especially because our analysis did not consider the confounding factors. However, a recent study that investigated SPCs in breast cancer showed that the standardized incidence ratios in patients with chemotherapy were higher in all malignancies except lymphoma, myeloma and chronic lymphocytic leukemia .Our study has a few limitations. First, we cannot be absolutely sure that all BL/L patients in our study were diagnosed based on WHOc 2008 (or a later version) because this information was not available. With the date cutoff applied in the sample selection (2008–2016), we could infer that the most recent version of the WHOc may have been used. Second, the search date cutoff restricted the risk factor analysis to cancers that occurred after BL/L . Third, the radiotherapy and chemotherapy variables were described according to the SEER*Stat as ‘No/Unknown’. The lack of descriptive information on these variables hampered further analyses. Fourth, information regarding aspects of treatment , disease  and comorbidities  was not available; thus, other analyses including the prognosis of patients according to the type of treatment, evaluation of malignancies in patients with HIV  or the distinction between the epidemiological clinical variants of BL could not be performed. Lastly, although our risk factor analysis presented several characteristics of a case-control study, factor and patient characteristics were not paired.In conclusion, population ageing, black race, advanced staging, no chemotherapy, radiotherapy and no surgery were associated with a worse prognosis in BL/L, significantly decreasing the OS. First primary cancers that behaved as risk factors for the development of BL/L as an SPC were aleukemic, subleukemic and NOS tumors; anus, anal canal and anorectum tumors; HLs ; Kaposi sarcomas; liver cancers and trachea, mediastinum and other respiratory organs cancers. On the other hand, lung and bronchus cancers decreased the incidence. At the same time, BL/L acted as a risk factor for the occurrence of other SPCs such as AML, HL  and Kaposi sarcomas. On the other hand, a decreased incidence was observed for breast cancer and lung/bronchus tumors as SPCs. These results may assist the development of diagnostic and clinical recommendations in this field and guide the conduction of further studies on risk factors for hematological malignancies.


Sexual self-efficacy (SSE) has also been cited as an important factor for healthy and satisfying sex. The purpose of this study was to determine SSE and its related factors among married women of reproductive age.The present study is a cross-sectional, descriptive-analytical study. The research samples were 588 married women of reproductive age. A cluster sampling method is used to select participants. Data collection instruments were the socio-demographic form and the Sexual Self-Efficacy Scale-Female Functioning (SSES-F). Data analysis, Friedman, Multiple Linear Regression was performed through SPSS software version 16.The highest and lowest score was related to body acceptance (77.78) and communication (69.66), respectively. The results showed that age , marital satisfaction , life satisfaction  and the economic-social welfare satisfaction were related to SSE. We've found that Women with a higher Education, Employment, higher income, and Younger husbands had the highest SSE score.The components of age, marital satisfaction, life satisfaction, and economic status affect the SSE of married women of reproductive age. The results of this study can be useful in the design and implementation of sexual health promotion interventions. The SSE is a predictor of sexual function and sexual quality of life Generally, people with low self- efficacy avoid sexual activity and have less sexual satisfaction Since the sexual response and sexual function, is highly influenced by the self-efficacy of a woman, the ability of the women to maintain pleasurable sexual function depends on their self-efficacy and motivation to be willing and able to fulfill sexual activity On the other hand, culturally, women's sexuality is framed as responsive and passive to male sexuality, with men initiating sex and women being the gatekeepers of sexual activity The present study is a cross-sectional, descriptive, and analytical study, which included 588 married women of reproductive age. The study population was selected based on some criteria. They were: women aged 15–49, married women who lived with their husbands, interested in participating, having the ability to read and write, and not using psychiatric drugs. The study population was selected using a Cluster Sampling method. At first, 24 Health Centers under the coverage of Guilan University of Medical Sciences were classified into 4 clusters based on geographic areas: North, South, East, and West. Then, using a random number table, 8 centers were selected by allocating 2 centers in each area.Data were collected using a two questionnaire includes demographics, the standardized tool SSES-F. The demographic questions consisted of items regarding personal- social characteristics , personal- social characteristics of the spouse  were evaluated.Bailes et al. The range of validity index was between 10 (absolutely uncertain) to 100 (quite sure) while the participants had been the ability to perform the sexual activity. If they are unable to perform, a zero score would be calculated. The overall grading of the questionnaire is computed from the mean scores of all aspects in SSES-F. The grading of each dimension is calculated based on the mean scores of the dimension. The highest score is 100 which represents a high SSE level.The independent-samples t-test, Variance Analysis, and Pearson Correlation Coefficiencyis used to determine SSE based on socio-demographic variables of participants. Logistic Regression or Multiple Linear Regression was used to determine related factors to SSE. P-Value was considered with P <0.05.The majority of participants (87%) were under 40 years old, diploma (47.1) and nearly 50% were unemployed (housewives). The majority's income was less than one million (about 50%). Besides, nearly 64% had children and about 15% had a history of infertility. The age of participants' spouses was 35. 72±7.61 .Based on the results, the total score of SSE (Mean score ± Standard Deviation) was 72.8±15 . MaximumIn multiple analysis, multiple linear regression in the method of stepwise was used to determine predictors of SSE. In the initial model, all variables with a P <0.1 level of significance has joined the model. In the final model, 4 variables include age , marital satisfaction , life satisfaction  is SSE predictors. The efficacy score decreased with age. However, there is a significant relationship between marital, life, economic satisfaction with the SSE score .Based on the results, the total score of SSE in the participants was 72.8±15. Body acceptance had the maximum and communication had the minimum scores. A study by Zare et al (2015) that assessed the relationship between SSE and sexual life quality was reported the mean score of SSE 49.61±12.63. These researchers demonstrated that, sexual refusal had the highest mean on the dimensions of SSE which is in line with the present study in terms of the highest mean in the SSE area The SSE score is statistically significant based on all socio-demographic variables. Participants with younger husbands, higher education and employment, and high incomes had great SSE scores. Previous research supports this idea. Often researchers are interested to evaluate women's sexual function, although that is an important one issue, understanding a women's sexual function is much more complex because influenced by women's sexuality. In order to advance the understanding of women's sexuality, a clarifying of some basic sexual concepts, and identifying the factors associated with them is essential and can be used in other areas of sexual research. As a sexual concept, SSE has great potential to help to understand women's sexuality and solves their sexual problems.The highest and lowest scores of SSE were related to body acceptance and communication, respectively. Besides, age, marital satisfaction, life satisfaction, and economic-social welfare, satisfaction are the factors related to SSE. The results of this study can be important for the application to programs such as sexual education. Future study efforts should continue to include each gender and age group.


Objectives: Synthetic MRI can obtain multiple parameters in one scan, including T1 and T2 relaxation time, proton density (PD), brain volume, etc. This study aimed to investigate the parameter values T1 and T2 relaxation time, PD, and volume characteristics of intraventricular hemorrhage (IVH) newborn brain, and the ability of synthetic MRI parameters T1 and T2 relaxation time and PD to diagnose IVH.Materials and methods: The study included 50 premature babies scanned with conventional and synthetic MRI. Premature infants were allocated to the case group (n = 15) and NON IVH (n = 35). The T1, T2, PD values, and brain volume were obtained by synthetic MRI. Then we assessed the impact of IVH on these parameters.Results: In the posterior limbs of the internal capsule (PLIC), genu of the corpus callosum (GCC), central white matter (CWM), frontal white matter (FWM), and cerebellum (each p < 0.05), the T1 and T2 relaxation times of the IVH group were significantly prolonged. There were significant differences also in PD. The brain volume in many parts were also significantly reduced, which was best illustrated in gray matter (GM), cerebrospinal fluid and intracranial volume, and brain parenchymal fraction (BPF) . The differential diagnosis ability of these quantitative values was found to be excellent in PLIC, CWM, and cerebellum .Conclusion: The quantitative parameters of synthetic MRI show well the brain tissue characteristic values and brain volume changes of IVH premature infants. T1 and T2 relaxation times and PD contribute to the diagnosis and evaluation of IVH. Intraventricular hemorrhage (IVH) is a common complication of premature infants and a typical form of intracranial hemorrhage in premature infants. Despite advances in clinical management, the absolute number of cases is still high due to the increase in the survival rate of premature infants and the detection rate of minor diseases . In addiThe long-term neurological outcome of IVH syndrome is still controversial and is still an active area of research. It was believed that IVH did not increase the risk of neurodevelopmental disorders related to preterm birth . Some re1, T2, and proton density (PD). In addition, it can reconstruct multiple image contrasts in one scan, which can save about 13 min of scan time compared with traditional MRI, and it can provide new information. Brain volume segmentation and calculation can also be performed through image post-processing. Synthetic MRI takes less time and obtains more image information. Therefore, this is especially suitable for some acute patients such as stroke. Although this emerging imaging technique has been described in some neurological fields, there has been no report on the use of synthetic MRI in children with IVH.Synthetic MRI is a quantitative imaging technique that can measure inherent relaxometry of TThe objectives of this study were to investigate the trend of local relaxation time and brain volume changes in IVH premature infants, and to study the diagnostic ability of quantitative parameters of synthetic MRI in IVH premature infants.The study included premature babies scanned from January 2020 to March 2021, and for which both conventional MRI and synthetic MRI were performed. The exclusion criteria included congenital malformations, congenital TORCH infection, periventricular leukomalacia, high-grade IVH, and poor image quality. The case group inclusion criteria were premature infants with low-grade IVH. The inclusion criteria of the control group were premature infants, no intracranial hemorrhage, no infectious diseases, no genetic diseases, etc. They had an MRI scan because they failed the hearing screening. Finally, 15 cases in the IVH group and 35 cases in the NON IVH group were included, and we obtained the informed consent of the parents.2/s). SyMRI software was used to calculate T1 and T2 relaxation maps, and T1WI , T1 FLAIR , T2WI , T2 FLAIR , and PD  images were reconstructed and synthesized for diagnostic evaluation. Their parameters were the same and are as follows: slice thickness: 4.0 mm, field of view: 220 × 186 mm. Scan time was 4 min. Then the professional manually outlined the region of interest (ROI) on the T1 image of SyMRI: posterior limbs of the internal capsule (PLIC), genu of the corpus callosum (GCC), parietal white matter (PWM), frontal white matter (FWM), thalamus (TH), central white matter (CWM), occipital white matter (OWM), and cerebellum. The ROI size was controlled within (10 ± 2) mm2. In order to avoid researcher bias, all ROIs were described by the same pediatric neuroradiologist, who had 10 years of experience in neonatal MRI and know nothing about grouping. The average T1 and T2 relaxation values of the selected ROI were automatically provided by the SyMRI software.All infants were sedated with dexmedetomidine hydrochloride injection, 0.75–1 μg/kg. Then the babies were placed on the MRI bed, and the ears were plugged with earplugs to protect hearing and reduce motion artifacts. MR scan was carried out on a 3.0 T MR scanner  in a supine position using a 16-channel head coil, with T1WI , T2WI , and T2 FLAIR  volume, cerebrospinal fluid (CSF) volume, brain parenchymal volume (BPV), and intracranial volume (ICV) of the whole brain on the SyMRI software. The BPV was calculated as the sum of WM, GM, and NoN . ICV was calculated as the sum of BPV and cerebrospinal fluid. The brain parenchymal fraction (BPF) was BPV divided by ICV. Skull stripping, to remove tissue outside the intracranial volume, was automatically performed by an existing module in this software.U-test of continuous and chi-square test of categorical variables. The quantitative values , tissue volume, and tissue score of the two groups in each segmentation area were compared, using the Mann–Whitney U-test or Student t-test.All data were statistically analyzed with SPSS version 21 . The normality of each variable was tested using the Shapiro–Wilk test. To determine the difference in clinical characteristics between the two groups, we used the Mann–Whitney p < 0.05 were considered to represent a statistically significant result. Graphs were prepared with GraphPad Prism version 8 .In addition, the ROC curve and the area under the curve (AUC) were used to evaluate the ability of relaxation time diagnostic. The AUC between 0.7 and 0.8 was considered acceptable, and 0.8–0.9 was considered excellent. p > 0.05) , and 35 cases of brain MRI showed normal . Gestational age (GA) at birth, postmenstrual age (PMA) at scan, birth weight, Apgar score, gender, and delivery method had no statistical significant difference (p < 0.05), the T1 and T2 relaxation times in the IVH group were significantly prolonged. At the same time, the T1 relaxation time in TH was also significantly longer . The significant difference in PD between the two groups was mainly manifested in PLIC , CWM , FWM , and cerebellum .The T1, T2 relaxation times and PD were used to evaluate the differences between the two groups of premature brain development . In the p = 0.071, t = 1.849) and OWM  was longer than the NON IVH group, the difference was not significant. T2 relaxation time had no significant difference in TH , PWM , and OWM . The OWM  showed that the PD value of the case group was lower, compared with the control group.Although the T1 relaxation time of WM . Second, the differences also existed in the NON volume . However, although the myelin volume in the IVH group was lower than the control group, it showed no difference .The brain tissue segmentation results of the two groups are shown in p < 0.001), as shown in We can also observe a similar trend in the BPF indicator. The BPF in the IVH group was significantly lower, compared with the NON IVH group . Acceptable for the T1, T2, and PD measurements in PWM , it was insufficient for T1, T2, and PD measurements in OWM . This was evaluated by the AUC of ROC curves (The ROC curve and AUC were used to assess whether IVH and NON IVH could be distinguished based on local tissue relaxation time alone. The differential diagnosis ability of T1, T2, and PD measurement was found to be excellent in PLIC, CWM, and cerebellum (AUC 0.700–0.837, C curves .Synthetic MRI can quantitatively evaluate the brain development of premature infants with intraventricular hemorrhage. In our research, the relaxation measurement showed that the T1, T2, and PD of preterm infants in the IVH group were prolonged. In addition, this paper proposed a novel method for automatic segmentation and volume estimation of whole brain tissue. Our results showed that the brain GM, CSF, BPV, and ICV of premature infants in the IVH group were significantly lower compared with the NON IVH group. The BPF results showed that, in the IVH group, BPV accounted for a small proportion of ICV, suggesting that the development was lagging behind. Relaxation measurement had a good diagnostic value for IVH premature infants, using ROC curve analysis. The research in this article shows that the quantitative value and brain volume could be obtained by quantitative synthetic MRI, which had certain value for brain development assessment and diagnosis of IVH in premature infants.Our results revealed that the T1 and T2 relaxation times of the IVH group were significantly delayed, especially in the posterior limbs of the internal capsule, genu of the corpus callosum, frontal white matter, and central white matter. It has been reported that measuring T1 and T2 relaxation time is particularly suitable for the study of neonatal brain maturity because they reflected the changes in volumetric water content, compartmentalization, and macromolecular microstructures associated with early brain maturation and myelination , 7. VariGenerally speaking, the order of white matter myelination is bottom–up, back-to-front, and center-to-around . The PLIBrain MRI segmentation and brain volume estimation are of great significance in many neurological applications . Our resICV compared with the control group. Our results showed no significant difference in myelin sheath volume compared with the control group. We speculated that the reason might be that the germinal matrix was the main source of oligodendrocyte progenitor proliferation. Moreover, oligodendrocyte progenitor cells migrated to the white matter, differentiated, and produced cerebral myelin in the third trimester. IVH, however, damaged the germinal matrix, thus, resulting in the loss of myelin-producing cells. The final manifestations were impaired myelin development and neurodevelopment. At the same time, the premature infants in the control group had a smaller corrected gestational age, and only partially myelinated or unmyelinated, so the difference in myelin volume was not significant.The BPF is calculated as the ratio of BPV and ICV. The brain parenchyma of IVH patients occupied a smaller volume in the skull. This indicated that the brain development of children with IVH was lagging behind. In the long run, it will affect children's intellectual development and abnormal behavior, language disorders, etc. . TherefoIn the central nervous system, quantitative biomarkers are increasingly needed to identify early brain injury or other neurological diseases. Synthetic MRI relaxometry of T1, T2, and PD can be used to quantitatively detect the differences in brain microstructure , 23. OurThe following limitations merit consideration. First of all, the sample size included in the case group was small. This requires subsequent collection of more IVH patients to increase the sample size. Second, the manually drawn ROI was subjective. Afterward, it is expected to automatically delineate the ROIs. In addition, studies reported that the artifacts of T2 FLAIR displayed in synthetic MRI were more common, but these artifacts were easy to identify and did not affect the diagnosis . TherefoSynthetic MRI is very sensitive in detecting the changes of brain microstructure in children with IVH. It can quantitatively determine the relaxation time and the changes of brain volume. We observed significant prolongation of local T1, T2, and PD in IVH premature infants. At the same time, the GM volume, total brain volume, and brain parenchymal fraction were also significantly reduced. Quantitative parameters of quantitative synthetic MRI were helpful to distinguish the brain tissue of premature infants with IVH from that of normal premature infants. Synthetic MRI may provide early biomarkers for neurodevelopmental disorders.The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s.The studies involving human participants were reviewed and approved by Ethics Committee of the Third Affiliated Hospital of Zhengzhou University. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.CZ: manuscript editing. MC: statistical analysis. XinZ: study design and work supervising. XiaZ: study concepts, design, and funding. KW: language modification. All authors contributed to the article and approved the submitted version.This research was funded by The National Natural Science Foundation of China, Grant No. 81870983. At the same time, it was also funded by Scientific and technological key project of Henan Province, Grant No. 212102310742.KW was employed by company GE Healthcare. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


However, the SVM model was lower (p < 0.01). We suggest that VLBWI mortality prediction using ML methods would yield the same prediction rate as the traditional statistical LR method and may be suitable for predicting mortality. However, low prediction rates are observed in certain ML methods; hence, further research is needed on these limitations and selecting an appropriate method.Statistical and analytical methods using artificial intelligence approaches such as machine learning (ML) are increasingly being applied to the field of pediatrics, particularly to neonatology. This study compared the representative ML analysis and the logistic regression (LR), which is a traditional statistical analysis method, using them to predict mortality of very low birth weight infants (VLBWI). We included 7472 VLBWI data from a nationwide Korean neonatal network. Eleven predictor variables  were selected based on clinical impact and statistical analysis. We compared the predicted mortality between ML methods—such as artificial neural network (ANN), random forest (RF), and support vector machine (SVM)—and LR with a randomly selected training set (80%) and a test set (20%). The model performances of area under the receiver operating curve  equaled LR 0.841 (0.811–0.872), ANN 0.845 (0.815–0.875), and RF 0.826 (0.795–0.858). The exception was SVM 0.631 (0.578–0.683). No statistically significant differences were observed between the performance of LR, ANN, and RF (i.e.,  For treating critically ill newborns, the clinical situation or severity at the time of hospitalization often affects newborns’ subsequent death or morbidity ,2. ThereNeonatal mortality or criticality assessments typically use general linear models, such as logistic regression (LR) analysis, to compare the influence of each risk factor; these models use prominent, influential factors as elements of assessment tools. However, LR models require statistical assumptions, such as linear relationships between the covariates and the risk of morbidity. Furthermore, limitations of regression, such as overfitting and multicollinearity, exclude the analysis of many explanatory variables. These limitations impede analytical models that select a small set of variables relevant to the clinical model .Recently, ML techniques have emerged as the most popular and flourishing discipline in artificial intelligence (AI) due to the capabilities of high-performance hardware such as graphic processing units and the availability of large datasets. ML techniques have been applied to many medical disciplines, including in the detection of specific clinical findings in medical images, and have achieved excellent performance with high sensitivity and specificity ,9. ExistThis study aims to determine the best model for mortality prediction by comparing the predictive performances of LR, artificial neural network (ANN), random forest (RF), and support vector machine (SVM) models using data from the Korea Neonatal Network (KNN), which is a national-wide registry of newborns weighing less than 1500 g who are admitted to the neonatal intensive care unit (NICU).We conducted the ML analysis of the KNN data . The KNNUsing a standard electronic report form, we collected the data for 10,425 VLBWI born between 1 January 2013 and 31 December 2017 in 67 hospitals participating in the KNN. This study excluded 139 infants born at a GA of ˂23 weeks, 624 infants born at GA of ≥34 weeks , 328 infThe primary outcome of this study was obtaining the mortality prediction of VLBWI in the NICU. We analyzed 20 variables from the KNN registry , hypertension, chorioamnionitis, premature rupture of membranes (PROM), antenatal steroid, and cesarean delivery; maternal social history: education, marital status, and nationality; paternal social history: education, and ethnicity). BW and GA showed a strong positive correlation of 0.73. Owing to the high possibility of multicollinearity between these two factors, the authors retained GA for the analysis  and excluded BW from the analysis . Additiop < 0.10.LR is a powerful model to analyzing multiple explanatory variables simultaneously while reducing the impact of confounding factors . We perfhttp://www.tensorflow.org, accessed on 30 December 2021), an open-source ML library from the Google Barin Team, and an R interface to Keras .ANN is an ML model that consists of three layers containing connected nodes: an input layer, a hidden layer, and an output layer . During RF is an ensemble technique that improves generalization by combining multiple learning models . The ratSVM is an ML model based on a linear delimiter, suitable for binary classification. We extend SVM to handle non-linear problems using the so-called kernel tricks. It implicitly maps the input vectors into a high-dimensional feature space via a non-linear map derived via a kernel function . SVM is We randomly selected 80% of the total cases as the dataset for training mortality prediction by developing four different ML models—LR, ANN, RF, and SVM. We then selected the remaining 20% of cases as the test dataset to predict mortality. The four ML models considered are briefly reviewed below:t-test to examine the differences among continuous variables. A two-tailed p-value of < 0.05 was considered statistically significant. Receiver operating characteristic (ROC) curves were used to plot the trade-off between specificity and sensitivity. The measures for the prediction performance of the ML model were: area under the ROC curve (AUROC), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). All data were cleaned and subsequently analyzed using R software packages .In this study, correlation between neonatal and maternal parameters and the mortality of VLBWI in NICU were analyzed using the Chi-squared test. We used the Student’s A total of 10,425 VLBWI were registered during the study period: 2953 neonates were excluded from this study because of considerations including GA, severe congenital anomalies, or missing values in their data. Thus, the final analysis included 7472 patients with complete records . Among tp = 0.035; others: p < 0.001). The mean GA at birth was 28+4 weeks (28+6 weeks in the living group vs. 25+6 weeks in the dead group), and the mean birth weight was 1071.0 g (1111.1 g in the living group vs. 775.2 g in the dead group). Moreover, 1 min Apgar score, 5 min Apgar score, and body temperature at admission were lower in the dead group than the living group . In addition, the dead group had a higher rate of resuscitation at birth than the living group (5914 (89.9%) in the living group vs. 881 (98.7%) in the dead group). However, there was no statistically significant difference between the two groups in multiple births (p = 0.367) (Patient characteristics are shown in = 0.367) .p < 0.001 in all groups). The maternal DM, hypertension, and antenatal steroids were higher in the living group than in the dead group . However, histologic chorioamnionitis and PROM rates were higher in the dead group than in the living group  (p = 0.008). The rate of “college or above” maternal education was higher in the living group (74.4%) than in the dead group (71.8%)  . Howeverd group) . In addi (71.8%) . No stat (71.8%) . p = 0.858, and p = 0.118, respectively). However, a statistically significant difference was observed between LR and SVM in terms of the AUROC (Reference and p < 0.001). The AUROC indicating the mortality prediction of the SVM model was lower than those of the LR, ANN, and RF models  to predict neonatal mortality in VLBWI. We found no statistically significant differences in the predictive performance of the ANN and RF models upon comparison with the LR, except for SVM, which had lower predictive performance. The ANN and RF models showed a predictive performance similar to LR; however, the sensitivity and specificity of each ML model differed. The RF model had sensitivity and specificity similar to those of LR, and the ANN model had a higher specificity but lower sensitivity than those of the LR model. As a result of comparing the prediction performance of the four models developed in this study, it showed that traditional LR method is close to ANN and RF, much better than SVM. SVM has the advantage of being well-suited for complex classification . HoweverLR is the most common algorithm for prognostic modeling, and it is often compared to AI-based models . HoweverThe ML approach facilitates a more refined approach to predicting the mortality of the preterm infants than that offered by the LR; thus, it can yield unbiased results and exhibit high clinical applicability. The ML approach allows the combination of higher-order non-linear correlation between the predictors, offers the advantage of being a non-parametric approach, and does not use distribution assumptions. The use of cross-validation also minimizes the possibility of overfitting in ML models. Therefore, the clinical application of ML models can help predict VLBWI mortality, and it can help make treatment decisions for this patient population. Although our study does not show results consistent with previous studies suggesting that either traditional LR or ML are superior, it does show that the ANN and RF models, but not SVM, can be as valuable as LR in predicting the mortality of VLBWI. Furthermore, the ANN and RF models showed a similar predictive ability of mortality in VLBWI compared to LR in this study. The LR method used to predict neonatal mortality in this study is considered to show similar predictive ability in ANN, RF, and LR, including the AI-based LR method which was used instead of the traditional LR method.The first strength of this study is that we use a population-based, prospectively collected national cohort database that covered more than 70% of the total VLBWI in Korea and registered multi-center clinical information on VLBWI from the 60–70 participating hospitals in Korea. The second strength of this study is that we confirmed the correlation between two variables, GA and BW, that can independently affect mortality in VLBWI and lead to bias, using the correlation meter to minimize bias. Finally, the third strength of this study is that we removed missing values (without processing) and incomplete cases to reduce the risk of bias due to missing values. Therefore, the risk of bias due to missing values was low.There are some limitations of this study that should be acknowledged. First, we excluded observations with missing values, which may be a disadvantage leading to an underestimating VLBWI mortality in this study. Second, although many variables may affect VLBWI mortality, we selected 11 variables for the analysis, which may lead to a selection bias in this study.This study shows that when ML models are applied to predict VLBWI mortality using maternal and neonatal factors, the ANN and RF models, but not SVM, show a predictive power similar to LR. Moreover, the RF model shows sensitivity, specificity, and accuracy similar to the LR ML model. Therefore, we thought these ML models would be a valuable and alternative strategy to LR when predicting VLBWI mortality. However, there is a low prediction rate depending on the ML method, so further research is needed based on these limitations and selecting an appropriate method.