Background: Despite innovative advances in neonatal medicine, intraventricular hemorrhage (IVH) continues to be a significant complication in neonatal intensive care units globally.Objective: The study aimed to discern the variables heightening the risk of severe IVH (Grade III and IV) in extremely premature infants weighing less than 750 grams. We postulated that a descending hematocrit (Hct) trend during the first week of life could serve as a predictive marker for the development of severe IVH in this vulnerable population.Methods: This retrospective case-control study encompassed infants weighing less than 750 grams at birth, diagnosed with Grade III and/or IV IVH, and born in a tertiary center from 2009 to 2014. A group of 17 infants with severe IVH was compared with 14 gestational age-matched controls. Acid-base status, glucose, fluid goal, urine output, and nutrient  intake during the first four days of life were meticulously evaluated. Statistically significant variables from baseline data were further analyzed via univariable and multivariable logistic regression analyses, ensuring control for potential confounding variables.Results: The univariate logistic regression model delineated odds ratios (ORs) of 0.842 for day 2 average Hct  and 0.16 for urine output on day 3 , with the remaining six variables demonstrating no significant association. In the post-multivariable regression analysis, day 2 Hct was the only significant variable . The receiver operating characteristic (ROC) curve analysis portrayed an area under the curve of 71% for the day 2 Hct variable.Conclusion: The study revealed that a dip in Hct on day 2 of life augments the likelihood of Grade III and IV IVH among extremely premature infants with a birth weight of less than 750 grams. This insight amplifies our understanding of risk factors associated with severe IVH development in extremely preterm infants, potentially aiding in refining preventive strategies and optimizing clinical management and treatment of these affected infants. Intraventricular hemorrhage (IVH), a prevalent complication linked with preterm birth, is of substantial concern due to its potential to engender profound neurodevelopmental deficits and permanent disabilities, such as deafness and blindness, in preterm infants -5. It isIVH typically originates in the periventricular germinal matrix of preterm infants, a region rich in glial and neuronal precursor cells in the developing brain, within the first 48 hours of life ,6. The pHematocrit (Hct), defined as the fraction of blood volume constituted by red blood cells, is often considered a surrogate marker for blood volume. Concordantly, several studies have probed into the direct relationship between Hct and IVH incidence ,19-21. AStudy design and participantsThis investigation adopted a case-control study design, targeting very low birth weight (VLBW) infants diagnosed with Grade III and/or Grade IV IVH between 2009 and 2014 at a tertiary center. The study's subjects were juxtaposed against gestational age-matched control infants. Inclusion criteria for the infants were a birth weight of less than 750 grams and a diagnosis of Grade III and/or Grade IV IVH within the first week of life , and parity were collated. Neonatal data comprising gestational age, gender, birth weight, admission temperature, and Apgar scores at one and five minutes post-delivery were also collected. Rigorous monitoring of the newborn infants facilitated the documentation of data pertaining to acid-base status, glucose levels, fluid goal, urine output, calorie intake, and protein intake during the first four days of hospitalization. The focus on data from the first four DOL stems from the average day of diagnosis for Grade III IVH in our sample being 3.6 DOL. We included infants who were diagnosed with IVH within the first 48 hours of life . Thus, this timeframe allowed us to evaluate how variable differences within this period may influence or predict the grade of IVH (the range of days when head ultrasound was performed extended from day 1 to day 9).Inclusion and exclusion criteriaThe inclusion criteria for the study were categorized into three distinct domains. Primarily, infants with a birth weight of up to 750 grams were considered eligible. Secondly, the timing of diagnosis was crucial; only those diagnosed with IVH within the first 48 hours of life were included. Finally, the study encompassed infants who survived beyond the immediate newborn period.Conversely, certain conditions warranted participant exclusion. Infants diagnosed with IVH from day 3, or more than 48 hours after birth, through to the first week of life were excluded. Additionally, infants exceeding a birth weight of 750 grams were deemed ineligible. Neonates identified with any congenital anomalies were excluded from the study, and any infants not surviving the immediate newborn period were also omitted from the research.Statistical analysisThe analytical plan comprised a comprehensive comparative assessment of clinical variables among case and control cohorts. Categorical data were delineated as proportions, while the distribution of continuous variables was appraised using the Shapiro-Wilk test. We presented parametric data as means and standard deviations (SDs), whereas non-parametric data were expressed as medians and interquartile ranges (IQRs).The chi-square test or Fisher's exact test was utilized for the analysis of categorical variables, while the Student's t-test was applied for parametric variables. Non-parametric variables were examined using the Mann-Whitney U test or the Kruskal-Wallis test. Confidence intervals were set at a 95% significance level, and a p-value threshold of 0.05 was adopted to establish statistical significance.For binary outcome variables, we computed odds ratios (ORs) to express effect estimates. Variables displaying significant correlation with severe IVH in the univariable analysis were advanced to the multivariable analysis phase. A binary logistic regression model was employed to assess the association between the binary outcome variable and the primary independent variable while adjusting for the effects of potential confounders.Given that the diagnosis of IVH was ascertained on day 3, our logistic regression model included only those clinical variables from day 2 that demonstrated statistical significance. This approach facilitated the evaluation of the predictive capabilities of the independent variables based on measurements acquired prior to IVH diagnosis.Subsequently, the Mantel-Haenszel (MH) method was implemented to detect variations in ORs across distinct subgroups of potential confounders. In the event of detecting effect modification, strata-specific ORs were additionally reported. All statistical analyses were carried out using the SAS 9.4 software .Participant profile and baseline characteristicsThroughout the five-year study duration, 17 infants diagnosed with severe IVH and 14 gestational age-matched control infants met the inclusion criteria. Upon evaluating the baseline demographics and clinical characteristics of both mothers and their infants, no statistically significant disparities emerged between the IVH and non-IVH infant groups (Table Mothers delivering IVH infants exhibited a slightly lower mean age compared to those giving birth to non-IVH infants (25.1 vs 28.7 years) and were predominantly of Black ethnicity (76.9% vs 57.1%). It is noteworthy that the vast majority of mothers across both cohorts had received postnatal care (PNC). Regarding therapeutic measures, a substantial proportion of mothers giving birth to IVH infants had been administered magnesium and antenatal steroids. Intriguingly, a higher fraction of non-IVH infants were delivered via cesarean section.In terms of neonatal characteristics, female infants constituted a majority within the non-IVH group (64.3% vs 41.2%). Infants diagnosed with IVH were slightly underweight and exhibited a marginally reduced average gestational age compared to non-IVH infants. Additionally, IVH infants demonstrated compromised Apgar scores at one and five minutes post-delivery.Follow-up characteristics of infantsThe univariate analysis of follow-up characteristics unveiled significant associations between distinct variables at specific stages Table . On day Multivariable predictors of severe IVHOnly significant baseline and follow-up variables were considered for the multivariable binary regression association analysis, employed for predicting severe IVH Table . FollowiPrincipal findingsOur retrospective study explores the relationship between Hct and the occurrence of severe IVH (Grade III and Grade IV). This was done with the purpose of filling the current shortage of information on this clinical variable as a predictor of IVH. Current literature points to an abundance of information detailing the connection between clinical indicators PCO2 and calorie intake as predictors of IVH. Hct, however, is little explored and found through our work to be a more directly connected indicator of potential IVH risk.The present understanding of the role of PCO2 as a predictor stems from findings regarding elevated PCO2 levels being significantly associated with IVH group preterm and low/ELBW infants in comparison to the control groups -25. VasoResults in the context of what is knownMultiple scientific studies have shown the importance of caloric intake within proper neurodevelopment. Caloric deprivation has been found to be a significant risk factor  as work With regards to Hct, our study shows after multivariate analysis that a day 2 Hct level of 35.42 is useful as a predictor for IVH in ELBW babies. In previous literature, low Hct is demonstrated to be a useful predictor for moderate-severe grade IVH ,34. The Advantages of HctHct provides several advantages as a diagnostic tool for IVH in comparison to the current gold standard-cranial ultrasounds. In ELBW babies, IVH occurs much earlier in comparison to VLBW babies. In a study comparing IVH timing between 500-700 g birth weight babies and 700-1500 g birth weight babies, 62% of cases occurred in the first 18 hours of life in the 500-700 gram birth weight babies group in comparison to 13% in the >700 g birth weight babies group . AlthougFrom the standpoint of VLBW infants, it has been found that in <1500 gram birth weight babies, approximately 48% of IVH cases occurred in the first six hours after birth. This occurrence of early-stage IVH has pointed to this initial six-hour window as being valuable in diagnosing and preventing further progression of IVH , pointinBacked up by further literature showing that the cranial ultrasound has zero sensitivity in picking up Grade II IVH (no ventricular dilation) , progresComparison with earlier studiesThere is a range of current literature that explores various other clinical risk factors and, if applicable, their sensitivity and specificity as a predictor of IVH. A study showed factors such as small for gestational age, lower platelet crit levels (PCT), and lower Apgar scores at 5 minutes were all significantly associated with occurrences of IVH in comparison to non-IVH group infants. Upon further multivariate analysis, it was found that low PCT levels were the most predictive indicator of IVH. This was simply one variable in their larger model analyzing the role of platelet-related factors in morbidity and mortality of preterm infants toward common diseases; thus, sensitivity and specificity were not calculated . In geneAdditionally, studies regarding plasma activin A have also suggested the presence of lesser-utilized clinical indicators of IVH. With regards to the detection of early-stage (I and II) IVH in preterm infants, a cutoff level of 0.8 μg/L activin A presented with a 100% specificity and sensitivity rate. This can point to neuroprotective measures being a beneficial intervention when concentration levels of plasma activin A in the infant's blood above that cutoff level are reached . With reBiological reasoning behind the association of HctThe intricate relationship between Hct, blood flow, and viscosity is key to understanding the genesis of IVH, especially in ELBW infants. Hct is known to affect blood viscosity, which, in turn, influences CBF . The immPrediction of IVH using multiple predictorsAnticipating IVH involves considering multiple predictors. Elevated PCO2 levels, indicative of hypercapnia, can predispose infants to IVH by causing vasodilation and a consequential increase in CBF -25. PremStrengths and limitationsThis case-control study offers novel insights into the association between Hct levels and severe IVH risk in extremely premature infants. The robust design, which matches cases and controls by gestational age, augments our understanding of IVH's potential mechanisms, highlighting Hct's potential as an early predictive biomarker. The rigorous use of both univariate and multivariate regression analyses also strengthens our findings.However, inherent limitations of a retrospective case-control study, such as potential selection bias due to the single-center sample, restrict the generalizability of the findings. Additionally, the small sample size may limit statistical power and increase the chance of type II errors. Despite controlling for several confounding variables, unmeasured confounders may present residual confounding, necessitating these findings be confirmed in future prospective studies.Future directionsTo extend this research, larger multi-center studies are necessary for enhanced generalizability. These studies could elucidate further risk factors and underlying biological mechanisms. The integration of artificial intelligence (AI) could refine IVH prediction capabilities, using Hct and other variables to provide personalized risk scores. However, the application of AI tools necessitates rigorous validation and ethical considerations.Moreover, investigating Hct-maintenance interventions could inform preventive strategies to reduce severe IVH incidence, thus improving clinical outcomes for extremely premature infants. Future research should, therefore, aim to explore, develop, and evaluate such interventions. While our study advances the understanding of severe IVH, further research is crucial to fully realize and leverage Hct's potential as a predictive marker.In conclusion, our study demonstrates the significance of decreasing Hct on the second day of life as a strong predictor for the occurrence of severe IVH (Grade III or IV) in extremely premature infants with a birth weight of less than 750 grams. The findings contribute to the growing body of knowledge surrounding the risk factors for IVH, potentially guiding advancements in prevention strategies and patient management. Future research should focus on validating these results in larger multicenter studies and developing advanced predictive models using machine learning to provide real-time, individualized risk assessments. Ultimately, such studies could lead to improved clinical outcomes for this vulnerable patient population.


To review the current literature regarding infection and inflammation of thethoracic aorta and to summarise its aetiologies, pathogenesis and clinicalpresentation. Additionally, the authors sought to compare diagnostic methodsand to analyse the different management options.A comprehensive electronic search using PubMed, MEDLINE, Scopus and GoogleScholar was conducted to find relevant journal articles with key searchterms including: ‘aortitis’, ‘thoracic aortic infection’ and ‘surgicalmanagement of infected thoracic aortic aneurysms’. Prominent publicationsfrom 1995 till present (2021) were analysed to achieve a deeperunderstanding of thoracic aorta infection and inflammation, and theinformation was then collated to form this review.Staphylococcus, Enterococcus andStreptococcus accounting for approximately 60% of theinfections. The authors also noted that StaphylococcusAureus was associated with poorer outcomes. Key diagnostictools include MRI and multi-slice CT imaging, which are useful imagingmodalities in defining the extent of the disease thus allowing for planningsurgical intervention. Surgical intervention itself is extremelymultifaceted and the rarity of the condition means no large-scalecomparative research between all the management options exists. Until morelarge-scale comparative data becomes available to guide treatment, theoptimal approach must be decided on a case-by-case basis, considering thebenefits and drawback of each treatment option.The literature review revealed that infectious causes are more prominent thannon-infectious causes, with Gram positive bacteria such asA high index of suspicion and a comprehensive history is required toeffectively diagnose and manage infection and inflammation of the thoracicaorta. Differentiating between infectious and inflammatory cases is crucialfor management planning, as infectious causes typically require antibioticsand surgical intervention. Over the years, the post treatment results haveshown significant improvement due to earlier diagnosis, advancement insurgical options and increasingly specific microbial therapy. Aortitis is a general term that describes aortic inflammation of any cause. The mostcommon aetiologies of aortitis are non-infectious, particularly large vesselvasculitides such as Takayasu and giant cell arteritis. Infectious causes can beattributed to many pathogens including Staphylococci, Enterococci and Streptococci.If undiagnosed, it can lead to the formation of an aneurysm which may rupture,thereby emphasising the importance of early diagnosis and management in improvingoutcomes. This review aims to present a recent summary of common aetiologies,microbiology, immunology, diagnostic tools and management options for aortitis.1 In the late 1800s, several causes of infected and inflamedaneurysms were established.2 Primary infections of the aorta and infected aorticaneurysms are rare, accounting for approximately 2–3% of all aortic aneurysms. Theseinfections are lethal, often requiring prompt surgical intervention, without whichthe mortality has been reported at 16–44%.3 Infectious and non-infectiousaetiologies have been studied extensively to determine management options and assessoutcomes.Aortitis is due to infection or inflammation, and usually includes the vasavasorum.In the last decade, there have been numerous theories explaining the pathology ofaortic infections and classifying them. Primary infected aneurysms can emerge fromlymphatic spread or direct contact; whereas secondary infected aneurysms occur as aresult of septic embolization typically within the vasa vasorum. Understandingwhether the source of the infection is intravascular or extravascular is crucial inrecognising the infectious agent. Various studies, have classified infections intodifferent types to further understand the pathways and determine managementoptions.3 Very few cases of non-aneurysmal infectious aortitis have beenreported, however, it is difficult to establish a diagnosis as compared to theiraneurysmal counterparts due to the nonspecific clinical manifestations.4 A case reportby Kanemitsu et al. described a patient who presented with fever and abdominal pain,whose CT scan indicated retroperitoneal fibrosis or inflammatory abdominal aortitis.The diagnosis was confirmed using broad range polymerase chain reaction and DNAsequencing, and the authors suggested that this method is useful in rapidlyestablishing a final diagnosis.4 In cases of infectious aortitisattacks in non-aneurysmal aortas, inadequate management can lead to formation of amycotic aneurysm and subsequent rupture.These five types  broadly 1 Regardingnon-infectious causes, inflammation of the aorta can typically occur as a result oflarge cell vasculitides such as giant cell arteritis (GCA) and Takayasu’s arteritis.GCA is more common in elderly women and involves the aorta or its branches in 10–18%of cases.5Other causes include systemic lupus erythematosus, rheumatoid arthritis and HLA-B27associated spondyloarthropathies.5Inflammatory aortic aneurysms account for around 10% of aortic aneurysms and aredifferentiated from atherosclerotic aneurysms by assessing peri-aortic fibrosis andmural thickening. These are non-infectious, with a predominantly unknown aetiologyalthough studies suggest that 50% of cases may be associated with IgG4 relateddisease and are linked to mediastinal or retroperitoneal fibrosis.Salmonella spp. and Staphylococcusaureus.3 Previously, most cases of aortitis were related toinfective endocarditis, in relation to infection by Enterococcus species andStreptococcus pneumonia.5.,pneumococci, as well as Haemophilusinfluenza.1 More recently, they havebeen linked to intravenous drug use and possible intravascularintervention.1Mycotic aneurysms were first described by Osler in the 1800s in the context ofbacterial endocarditis. The term ‘mycotic’ could be misleading, as it alludes toinvolvement of fungal pathogens. However, they have been associated with Group Aβ-haemolytic Salmonella, common in infectiousabdominal aortitis are reported to make up of approximately 35% of all infectedaneurysms.3 A retrospective review by Hsu et al. investigatingcommon microorganisms in infected thoracic aortic aneurysms (ITAA) noted thatthat aortic infections due to nontyphoid Salmonella resulted inpoor clinical outcomes.3 A higher mortality rate was reported here due tosubsequent supra-renal aneurysms, and increased likelihood of rupture due topathogen invasion of the intima.3Gram negative bacilli, mainly 7 Studieshave reported that Th1 cytokines such as IFN-γ aid in the development of earlyatherosclerosis which is a significant risk factor to developing aortitis. Th2cytokines and chemokines appear in later stages. Although there is involvementof several inflammatory mediators, Th1 is the most critical in accumulation ofinflammatory cells in aortic aneurysms.7The immunological processes in aortitis vary based on aetiology, especially whencomparing infectious and non-infectious processes. The presence of inflammatoryinfiltrates in aortic aneurysms increases the likelihood of decay.8. Nonspecific symptoms and results include fever(75%), thoracic and back pain (60%), abdominal pain (20%), leucocytosis,neutrophilia and elevated inflammatory markers.10 Other findingsinclude a palpable pulsatile tender mass and positive blood culture.Additionally, interleukin-6 can serve as a useful marker in diagnosingGCA.10It is vital to establish an early diagnosis with aortitis due to its severeand life-threatening nature. This can be difficult due to the nonspecificsigns and symptoms and differing clinical presentations. It should besuspected in patients over the age of 50, with a history of atherosclerosisor aneurysmal disease if they present with thoracic/back pain, nausea,vomiting and fever 11 Otheraspects of diagnosing aortitis are biopsy, histology andimmunochemistry.5 Differentiating between infectious and non-infectiousaortitis is a key feature of the diagnostic process as the incorrect use ofcorticosteroids or immunosuppressing drugs instead of antimicrobial drugs in thepresence of an infected aneurysm is harmful.12 Imaging plays a crucialrole in this with non-infected aneurysms typically taking on a fusiform shapeand involving longer stretches of the aorta.13 Infected aneurysms tendto be more saccular in nature and imaging may also show oedema, peri-aortic gasand fat-stranding.14 A saccular aneurysm may also indicate a risk or ruptureand so its presence should prompt an accelerated diagnostic work-up to enableimmediate treatment.15 Clinical presentation and blood cultures alone havesignificantly less diagnostic value in comparison to imaging with regard todifferentiating between infected and non-infected aortic aneurysms.16Imaging modalities that are useful in diagnosing aortitis when there is aclinical suspicion are CT angiography (CTA), MR angiography (MRA), ultrasoundscanning (US) and positron emission tomography (PET) scanning.5 Despite this, mildinflammation and wall oedema may be missed. CT is performed with theadministration of iodinated contrast and is particularly helpful in rulingout other pathologies that may have similar presentations to aortitis .5 Limitations of CTinclude its sensitivity, the need of exposure to radiation and iodinatedcontrast which may not be administered to all patients.11Compared to MRI, CT imaging can also show arterial calcifications which maybe caused by long standing aortitis (e.g.Takayasu arteritis) 17.Multidetector CTA offers high resolution and 3D reconstruction which hasmade it the imaging of choice when evaluating mycotic aneurysms.1CT scans can image aortic wall thickening and peri-aortic inflammation, whichare cardinal signs of aortic infection.18 Compared to CT, MRIdoes not expose patients to ionising radiation which is advantageous inyounger age groups (<35 years old). Areas of aortic inflammation maypresent as wall thickening, oedema or enhancement on MRI. Disadvantages ofMRI include the fact that it is not always available and its unsuitabilityfor patients with implanted devices or who are critically unwell.8 Recentstudies have found 3D-black-blood MRI is an effective and radiation-freealternative to cross sectional CT imaging for the diagnosis of thoraciclarge vessel vasculitis, making it a useful modality for investigatingnon-infectious aortitis.20 Both MRI andmulti-slice CT imaging are useful in defining the extent of the disease andfor planning surgical intervention.22MRI provides good resolution images of the aortic wall and lumen with thepossibility of 3D reconstructions and is performed with gadolinium contrast.Non-contrast MR angiography can be used alongside contrast imaging toprovide complementary information about the lumen, or as an alternative whencontrast is unsuitable.23 It isimportant to differentiate lineal diffuse uptake in the wall that ischaracteristic for vasculitis from patchy uptake that is more suggestive ofatherosclerotic disease.24 CT or MRI can then beused in further morphological assessment of the vessel, thus allowing for amore precise localisation of disease in combined imaging.11 Asystematic review on large vessel vasculitis revealed specificities of 98%and sensitivities of 90% for GCA patients. 18-FDG PET performed well inassessing Takayasu arteritis as well with pooled specificities andsensitivities of 84%. Limitations identified by the meta-analysis includethe need to standardise the parameters used to analyse vascularinflammation.25 Other small studiesof 18F-FDG PET in Takayasu arteritis have shown sensitivity ranges of60%–92% and specificities of 88%–100%.28 These have hadinconsistent reference standards, so larger clinical studies should beperformed for a more relevant comparison.A recently emerging technique is combining the use of 18-fluorodeoxyglucose(18F-FDG) PET with CTA or MRA for initial diagnosis of GCA or Takayasuarteritis. 18F-FDG taken up by macrophages and lymphocytes, thus acting as asurrogate marker of increased activity of inflammatory cells.8 As such, it remainsuseful only in situations where aortitis or a mycotic aneurysm cannot beexcluded otherwise.11 Similarly, ultrasound scanning (US) is not acommonly used modality for diagnosing aortitis, but abdominal ortransthoracic US can show circumferential thickening of the aortic wall andcan be useful in identifying and assessing aneurysms in the ascendingthoracic aorta. Transoesophageal echocardiogram is the gold standardinvestigation for excluding infective endocarditis which is commonlyassociated with infectious aortitis. While echocardiography measures thelumen diameter, CT and MRI allow for measuring the external aortic diameterwhich allows for better imaging of aortic wall pathology.5Despite having been the investigation of choice in the past, angiography isinvasive and poses the risk of causing the rupture of the aortic wall whichcan be very fragile when inflamed.Where there is clinical suspicion of aortitis, we recommend early MRI or CTimaging as the most crucial step in the diagnostic pathway. Whilst theclinical picture of the patient and other previously mentioned facets of thediagnostic work-up are important, imaging is the investigation which allowsfor the key differentiation between infectious and non-infectious aortitis.Additionally, early imaging enables the planning of life saving treatment tobe expedited, thereby mitigating risks such as aneurysm rupture.29 If infectiousaortitis is suspected, it should be rapidly diagnosed and requiresbroad-spectrum IV antibiotics covering the most likely pathogens.30 Inthe case of infected thoracic aortic aneurysms, ampicillin orcephalosporins, which combat Salmonella species, should bethe first choice antibiotics when a causative agent is not yet identified bya positive blood culture.31 If the patient istaken straight to theatre , then perioperative tissue samples should also be taken so theinfecting agent can be identified and a more efficacious and narrow spectrumpost-operative antibiotic regimen can be implemented.32One of the initial therapy options for non-infectious aortitis is usingcorticosteroids, generally 0.5–1 mg/kg prednisolone daily for 1–2 years withthe possibility of dose reduction 2–3 months after initiation. Nearly 50%patients can relapse during tapering, requiring additional immunosuppressionwith drugs such as methotrexate.31 The rarity of ITAA andthe clinical variability of the aneurysm means there are no specific guidelinesregarding its treatment and the precise nature of the surgical intervention isdecided on a case-by-case basis.33 There are four maincategories of ITAA and whilst their pathogenesis varies depending on their type,the surgical options similar for all types.34Surgical intervention occurs once the infection or inflammation to the thoracicaorta has progressed to a point where an ITAA has formed. Generally, surgery isadvised when the aneurysm’s diameter exceeds 55 mm or rapid expansion isobserved using short interval CT.35 A comprehensivestatement from the American Heart Association (AHA) regarding the treatmentof infected aortic aneurysms outlines five major benefits of in situ aorticreconstruction over extra-anatomic bypass.36 The five benefitsare:1. Rifampicin-soaked (and other conduits) arereadily available2. Greaterversatility of in situ conduits versus extra-anatomicalones.3. There are fewer long-termcomplications  with an in-situapproach.4. Lower complicationrates in patients with aortic infection secondary toaorto-enteric fistulas.5. Higherlong-term survival rates within situ repair versusextra-anatomic bypass.Open surgical management involves resecting the aneurysm, thoroughlydebriding the infected tissue, and irrigating with saline, to minimise therisk of re-infection. This is followed by aortic reconstruction using insitu graft placement.36 Müller et al. explain that for supra-renal infectedaortic aneurysms (i.e. ITAA), the anatomical difficulty and need torevascularize the intercostal, visceral and renal arteries simultaneouslymeans that an in situ repair is the only option, with extra-anatomicalrepair not being feasible in this setting.37 Whilst extra-anatomicbypass has been performed in the thoracic aorta, the only existing examplesare in the context of complex aortic stenosis and aortic arch atresia in apaediatric setting.39 The five benefits above imply that an in situreconstruction would be preferable even if an extra-anatomic bypass was afeasible alternative. The AHA article states the major disadvantage of insitu reconstruction is that the introduction of the graft, a foreign body,into the infected and potentially purulent vascular tissue may promotere-infection. The necessity of in situ repair in the case of ITAA means thatthe infected tissue cannot be bypassed and so a pedicle omental flap may beused to bring immune tissue from the omentum to the graft site in an effortto reduce post-operative infection rates.40It is noteworthy that extra-anatomic bypass is theoretically not possible inthe context of an ITAA, however, the benefits of in situ reconstruction arestill relevant.S. Aureus,which is the most common pathogen infecting pre-existinganeurysms.42 Rifampicin-bound grafts have also been found to bemore resistant to post-operative infection than Dacron graftsalone.43 Although not directly comparable to treating aorticinfection in humans, recent animal studies have concluded that a novelantibiotic combination of minocycline, chlorhexidine and rifampicin has aneven lower rate of post-operative infection (25%) versus Dacron alone (75%)or poly-tetra-flour-ethylene (87.5%) in resisting polymicrobial graftinfection.44 A similar animal pilot study also concluded thatgrafts bound to these same three antibiotics proved highly effective atreducing graft infection for at least 2 weeks post-operatively which impliesthat the future of antibiotic bound grafts may be this triple approachrather than rifampicin alone.45 However, more studiesand human trials are needed to confirm this.The opinion of the literature varies regarding what the best graft materialis for in situ repair, but there are certainly more popular options. Gupta,Bandyk and Johnson postulated that rifampicin-bonded, gelatin-impregnatedantibiotic Dacron grafts were useful in treating staphylococcal infectionsof the aorta; being especially effective against 46 This is supported byTambe, Sampath and Modak who’s research comparing antibiotics versusantiseptics in medical devices showed that medical devices with silver saltswere better at preventing bacterial growth than those containing rifampicin,especially in the case of antibiotic resistance. They concluded that thedevelopment of bacterial resistance to antiseptics is negligible, whilecertain bacteria developed antibiotic resistance far quicker.47Grafts bound with silver salts have also been shown to be highly effectivewhen used as replacement conduits for the infected thoracic aorta. Batt etal. performed a prospective study where they analysed the use of anInterGard Silver (IGS) collagen and silver acetate–coated polyester graft inreplacing mycotic aortic aneurysms (and in redo operations for infectedgrafts) concluding that secondary infections were less common with the IGSversus the rifampicin-bound graft.48 They conclude from their treatment of 50 patientsfrom 2006 to 2016 that the use of cryopreserved allografts was associatedwith good resistance to re-infection owing to the lack of a need tointroduce a foreign graft material into infected tissue. They also claim a64% survival outcome for their patients and identified key drawbacks ofcryopreserved allografts: early rupture and pseudoaneurysm formation. Theresearchers acted on this by ensuring close early observation for sutureline disruption or aneurysmal changes to the cryopreserved allograft,however, this early limitation remains the main drawback of this graftapproach. McCready et al. also concluded that long-term degeneration ofcryopreserved allografts was rare; suggesting that in the absence of initialcomplications or significant patient comorbidities at the time of operating,they may be a strong candidate for an effective long-term grafttype.49Corvera et al. wrote extensively about the use of cryopreserved allografts inrelation to treating thoracic and thoracoabdominal mycotic aneurysms andtheir work is the largest recorded study of cryopreserved allografts in thethoracic aorta.50 Advantages of this method include its adequacy forcritically ill patients and avoiding: thoracotomy, aortic cross-clamping,extracorporeal circulation and the manipulation of fragile and inflamedaortic tissue.51 It can also be used in staged procedures in orderto delay open repair until the patient is more stable.50 Thedrawback of endovascular repair is the potential increased rate of graftinfection, sepsis, recurrent MAA or fistulation since the stent graft isplaced in an infected area with no previous debridement.51Endovascular repair for mycotic aortic aneurysms (MAA) was firstly describedin 1998, offering a less invasive management method compared to open repair(OR).52 A retrospectiveSwedish nationwide study on mycotic thoracic aortic aneurysms showed thatendovascular repair as the predominant management option in Sweden. Survivalwas 92% at 30 days and 72% at 5 years. It showed comparable frequency ofinfection-related complications to that reported by Hsu et al. for OR: 17%vs 18%.54A European retrospective multicentre study on MAAs has shown 91% survival at30 days, 19% fatal infection-related complications (most during the firstyear post op), 55% survival at 5 years with few serious late infectioncomplications when using endovascular aneurysm repair. Short term mortalityrates for OR range from 20% to 40% with significant short- and long-termmorbidities from the operation.21 Thisstance is shared by Ting et al. who conclude that open surgery with in situaortic reconstruction is associated with favourable outcomes and goodlong-term results.55Stellmes et al. found that endovascular repair to thoracic aortic aneurysmfeasible in an emergency setting but noted the importance of life-longclinical monitoring and follow up. Notably, 1/6 of their cases diedfollowing endovascular repair and 2/6 of their patients had to undergosecond operations where an open repair was performed owing to inadequaciesof the former endovascular approach as a permanent solution.37Due to the lack of RCTs and head-to-head studies on this relatively raretopic there are no clear guidelines on management of ITAAs and furtherstudies with longer follow ups should be performed to clarify this.Ultimately the management choice should be tailored for each case byconsidering factors such as the location of the aneurysm, patientcomorbidities and the infective pathogen. Regardless of the surgicalapproach to ITAA repair, post-operative antibiotics play a crucial role inthe prevention of re-infection. The timespan for how long antibiotics shouldbe taken post-operatively is very varied but Müller et al., recommended aminimum of 3 months and only to discontinue antibiotics when closeexamination rules out any chance of remaining infection; based off their owninstitutional analyses throughout the 1980 and 1990s.56 16 patientswith aortitis were followed up over a median of 3.6 years and eight had ‘Significantaortic events’ including further dissections and new aneurysm formation. Low patientnumbers mean that the findings of this study may not be consistent with the outcomesexperienced by all patients with non-infectious aortitis, however, the scarceliterature means this study adds significantly to a generally lacking knowledgebase. Prognosis in the short to mid-term is highlighted by a similar case seriesevaluating 64 patients with non-infectious aortitis (median follow up of 15.4months) which found a death rate of 9.4%.57 A 2014 study of 156 patientswho were operated on due to inflammatory diseases of the thoracic aorta providesfollow up over a longer time period: they quote a Kaplan–Meier survival rate of 55%at 8 years.58On balance, the scarcity of literature, variability of management and diversity ofpatient factors makes is hard to predict exactly what outcome a patient withnon-infectious aortitis might expect.A 2019 Study evaluated outcomes in patients with non-infectious aortitis followingsurgical repair of thoracic aortic aneurysms and dissections.54 with complications includingsepsis, graft infection, mycotic aneurysm recurrence and aorto-oesophageal fistulaformation. Other studies have quoted similar 5-year survival rates of 71% and 74.9%,respectively.59 Whilst operative management is associated with risks, untreatedinfective aortitis has been shown to be associated with a high risk of aorticrupture with a subsequent high mortality.11 A systematic review into themanagement of mycotic aortic aneurysms concluded that EVAR appears to be associatedwith superior short term survival (without late disadvantages) in comparison toOR.60Of note, the review also concluded that a supra-renal aneurysm location wasassociated with poorer outcomes, suggesting that thoracic mycotic aortic aneurysmshave a worse prognosis in comparison to their abdominal counterparts. Other factorsassociated with poor prognosis include: advanced patient age, non-salmonellainfection/pathogen virulence, non-operative management and the level of infectionprior to operating.62 Overall, the scarcity of literature looking specifically atoutcomes in patients with surgically treated thoracic aortic aneurysms and thevariability of patient and treatment factors means that the complication rates inany one study may not accurately reflect the risk of developing that complicationfor the wider patient population.Regarding the outcomes of infectious aortitis and mycotic aneurysms, the literatureis again lacking and largely focuses on abdominal rather than thoracic aorticpathology. A 2018 paper looking at the outcomes of surgically repaired MycoticAortic Aneurysms showed a 5-year survival rate of 71%Staphylococci, Enterococci andStreptococci and by Gram negative bacteria such asSalmonella. Early diagnosis aids in reducing mortality and ismade by clinical examination, laboratory testing and CT, MRI and ultrasound imaging.Regarding the infected thoracic aorta, management typically consists ofbroad-spectrum antibiotic use and then, provided the patient is a suitable surgicalcandidate, open or endovascular techniques are used to replace the infected andoften aneurysmal aorta. Whilst larger scale research and trials would allow forclearer treatment guidelines to be produced, the complexity of this disease meansthat management on a case-by-case basis is likely to remain the primary approach fortreating patients suffering from infected and inflamed thoracic aortas.Inflammation and infection of the thoracic aorta are rare and dangerous conditionswith a myriad of aetiologies and a reported mortality of 30–50%. Non-infectiouscauses are primarily accredited to large vessel vasculitides, whereas infectiouscauses tend to be because of bacterial infections, namely by Gram positiveThis review has detailed several avenues of thoracic aortitis and the investigativeand management options based on aetiology. Typically, a high index of suspicion anda comprehensive history is required, and, due to the rarity and nonspecific clinicalsymptoms, there is often an ambiguous diagnosis. Differentiating between infectiousand inflammatory cases is crucial for management planning, as infectious causesrequire antibiotics and surgical intervention. Over the years, the post-treatmentresults have shown significant improvement due to early diagnosis, advancement insurgical options and increasingly specific microbial therapy.


Functional abdominal pain disorders (FAPDs) affect up to 25% of children in the United States. These disorders are more recently known as disorders of “brain-gut” interaction. The diagnosis is based on the ROME IV criteria, and requires the absence of an organic condition to explain the symptoms. Although these disorders are not completely understood, several factors have been involved in the pathophysiology including disordered gut motility, visceral hypersensitivity, allergies, anxiety/stress, gastrointestinal infection/inflammation, as well dysbiosis of the gut microbiome. The pharmacologic and non-pharmacologic treatments for FAPDs are directed to modifying these pathophysiologic mechanisms. This review aims to summarize the non-pharmacologic interventions used in the treatment of FAPDs including dietary modifications, manipulation of the gut microbiome  and psychological interventions that addresses the “brain” component of the brain-gut axis . In a survey conducted at a large academic pediatric gastroenterology center, 96% of patients with functional pain disorders reported using at least 1 complementary and alternative medicine treatment to ameliorate symptoms. The paucity of data supporting most of the therapies discussed in this review underscores the need for large randomized controlled trials to assess their efficacy and superiority compared to other treatments. Functional gastrointestinal disorders (FGIDs) are characterized by recurrent abdominal pain in the absence of structural or biochemical abnormalities . The patThe low FODMAP diet has been one of the most well studied interventions in FGID management in adults. The low FODMAP diet aims to minimize the intake of several fermentable carbohydrates, including foods containing galacto-oligosaccharides, lactose, fructose in excess of glucose, and sugar polyols, such as sorbitol and mannitol. Examples of foods high in FODMAPs are: wheat, rye, barley, brussels sprouts, artichoke, asparagus, lentils, legumes, okra, peas, apples, shallots, beet, broccoli, fennel and onion . The lowLactose is a disaccharide comprised of glucose and galactose. Lactose is digested by hydrolysis via lactase-phlorizin hydrolase (LPH) activity in the small intestinal brush border. Symptoms of lactose intolerance  resulting from LPH deficiency often overlap with those seen in IBS . Studiesn = 81) and also found children with FAPD receiving age based doses of soluble fiber (psyllium) for 4 weeks reported reduced IBS symptoms compared to the placebo group  with 1,299 total participants ranging in age from 15 to 78 years old and found soluble fiber improved global symptom scores in patients with IBS while insoluble fiber did not appear to have an effect . Althougbo group . Similarbo group . The mecbo group . The diebo group . Solublebo group . Short cbo group . SCFAs hbo group . SCFAs, bo group .n = 36) entered a prospective double-blind placebo-controlled gluten challenge  and results showed only 14% of children had true NCGS (Non-celiac gluten sensitivity (NCGS) is characterized by intestinal and or extra intestinal symptoms after gluten ingestion that resolve with gluten withdrawal and relapse following a gluten challenge in the absence of celiac disease (CD) or wheat allergy . Intestirue NCGS . This strue NCGS . Currentrue NCGS .n = 28) and without FAP (n = 58) found Bacteroidetes significantly lower in the healthy controls and Firmicutes significantly increased in healthy controls  and VSL#3 significantly increased treatment success and reduced pain intensity in children with abdominal pain related FGIDs, especially IBS  with a total of 641 subjects between the ages of 4–18 years and found a moderate positive effect on pain intensity reduction for L. reuteri at 4 weeks however, beyond that there was no significant reduction in pain frequency at any point in time, no reduction in school absenteeism, and no significant increase in the number of children whose symptoms completely resolved after the intervention . A study by Gholizade et al. published in 2021 demonstrated that a synbiotic composed of fructo-oligosaccharides and seven types of beneficial bacteria effectively decreased the frequency, duration and intensity of FAPD in children .Studies have shown that children with FGIDs have a greater incidence of clinically proven anxiety disorders and depression compared to children without FGIDs . These pn = 24) conducted by Zucker et al. showed that CBT can be effectively utilized in younger children (ages 5–9 years) with a focus on promoting playful and curious approaches to body signals and providing families with decision trees to help describe, label, and interpret the meaning of somatic signals through the use of cartoon characters as metaphors for experience  (CBT focuses on reducing anxiety and stress related to somatic sensations . Viscerassy Gus) . Althougssy Gus) . CBT tarssy Gus) . It is assy Gus) . Parentsssy Gus) . Anotherssy Gus) .HT has been used for treatment of refractory IBS since the 1980s . The aimYoga incorporates aspects of exercise, breath work, concentration, and meditation . Health n = 12,787) but found only one fifth of the reviews were high quality  and the Firmicutes to Bacteriodetes ratio was lower in children who received 540 mg of peppermint oil compared to other groups  . Studiesn = 307) living in Boston found 42% of participants were vitamin D insufficient with 24% of the study population having vitamin D levels in the deficient range (n = 112) found patients who received 6 months of vitamin D supplementation had significant improvement in IBS symptoms and QoL scores compared to the placebo group  of gastric slow waves regulated by the interstitial cells of cajal . Other tThis review highlights non-pharmacologic therapies clinicians may offer as treatment options for pediatric patients with IBS and reviews the relevant literature. It also highlights some common non-pharmacologic therapies patients may inquire about but may not be recommended due to lack of supporting evidence. In general, well conducted pediatric trials for many therapies discussed are lacking and the existing ones are small in sample size making generalizable conclusions difficult. Treatments offered to patients should consider the available evidence, the individual patient circumstances, and resource availability.


Cox2 or Pge2 in the osteoblast lineage cells or knockout Ep4 in sensory nerve blunts bone formation in response to mechanical loading. And sensory denervation also significantly reduces mechanical load-induced bone formation. Moreover, mechanical loading induces CREB phosphorylation in the hypothalamic ARC region to inhibit sympathetic TH expression in the PVN for osteogenesis. Finally, we show that elevated PGE2 is associated with ankle osteoarthritis (AOA) and pain. Together, our data demonstrate that in response to mechanical loading, skeletal interoception occurs in the form of hypothalamic processing of PGE2-driven peripheral signaling to maintain physiologic bone homeostasis, while chronically elevated PGE2 can be sensed as pain during AOA and implication of potential treatment.Bone is a mechanosensitive tissue and undergoes constant remodeling to adapt to the mechanical loading environment. However, it is unclear whether the signals of bone cells in response to mechanical stress are processed and interpreted in the brain. In this study, we found that the hypothalamus of the brain regulates bone remodeling and structure by perceiving bone PGE2 concentration in response to mechanical loading. Bone PGE2 levels are in proportion to their weight bearing. When weight bearing changes in the tail-suspension mice, the PGE2 concentrations in bones change in line with their weight bearing changes. Deletion of  The primary functions of the skeleton of terrestrial animals are to provide mechanical support for locomotion and physical activity, to protect fragile organs and to serve as a metabolic mineral reserve. The mecMechanical loads increase bone formation by stimulating the activity of bone-forming osteoblasts. In contInteroception represents and monitors the organism’s internal state to regulate the complex interactions between the brain and peripheral organs, 30. TheTo date, the PGE2 skeletal interoception in regulating bone remodeling has been mostly studied in the pathophysiological conditions. It is sin vitro microcomputerized tomography (μCT) of bones at different locations within the body harvested at 12 weeks of age revealed that the talus had the highest bone volume fraction (BV/TV), as well as the trabecular thickness (Tb.Th) and cortical thickness (Ct.Th), which are indices of trabecular and cortical structure, respectively, while the skull had the lowest of these three parameters.  was investigated. TS is a ground-based model that creates hypokinesia and hypodynamia at the hind limbs and mimics cephalic fluid-shift aspects of space flight. Extensive studies in rats showed that it induces both cortical and cancellous bone loss in the hind limbs. We thus+ osteoclasts at steady state in the calcaneus and tibia, but not in the talus  by crossing Cox2 floxed (Cox2wt) mice with osteocalcin (Ocn)-Cre mice to eliminate PGE2 secretion by osteoblastic cells as Ocn is a selective marker of osteoblasts. Bone PGE2 concentrations were not changed after loading within 12 h in the Cox2Ocn−/− mice, suggesting that PGE2 was largely secreted by osteoblasts  mice with sensory neuron-specific cre mice (Advilin-Cre) to generate mice with sensory denervation (TrkAAvil−/−). Immunostaining of talus sections showed that most calcitonin gene-related peptide (CGRP)+ sensory nerve fibers were eliminated in the TrkAAvil−/− mice (TrkAwt or TrkAAvil−/− mice (TrkAAvil−/− mice relative to their wild-type (WT) littermates  by crossing EP4 floxed (EP4wt) mice with Advilin-Cre mice. In the EP4wt mice, the bone mass increased significantly after mechanical loading compared to the control group, as shown by μCT analysis. However, this effect was diminished in the EP4Avil−/− mice , the rate-limiting enzyme in the synthesis of catecholamines, in the paraventricular nucleus (PVN) of the hypothalamus. TH expression was significantly lower in the mechanical loading group compared to the control group . As expel−/−mice . Taken tThe ARC is an essential site for the control of energy balance and the autonomic nervous system. The PVN has been identified as the primary hypothalamic site that contributes to the control of sympathetic outflow and energy expenditure. In the + neurons, which are primarily located in the ARC, express neuropeptide Y (NPY) and gamma-aminobutyric acid (GABA) to decrease energy expenditure via the sympathetic nervous system -mCherry) unilaterally into the ARC. The infected AgRP+ neurons express inhibitory designer receptors hM4d, which can be inhibited following injection of the designer ligand clozapine-N-oxide (CNO). Inhibition of AgRP+ neurons on the right side of the brain was associated with significantly lower pCREB expression in the ARC during mechanical loading compared with the control left side of the brain (Agouti-related peptide (AgRP)s system . To testhe brain , F. Impohe brain , H. ThusTh gene expression, we measured Crem (the gene that encodes ICER) mRNA expression in the PVN in mice after mechanical loading through reverse transcription-polymerase chain reaction (RT-PCR). Crem mRNA expression was significantly higher in loaded mice compared to the unloaded control group  is an endogenous repressor of cAMP-responsive element (CRE)-mediated gene transcription. To determine whether mechanical loading increases the expression of ICER in the hypothalamus to regulate ol group . By Westol group . To invepromoter  and founpromoter . Moreove−/− mice . Taken tPOMC, to regulate energy metabolism. We found that mechanical loading induced significant greater levels of p-STAT3 in the PVN in the EP4wt mice  acts as a transcription factor that binds to and regulate the expression of target genes, such as 4wt mice . We nextpromoter , H. In a−/− mice  Therefor+ neurofilaments was markedly higher in AOA mice than in the the sham-surgery group -associated pain. In mice, we excised the calcaneofibular ligament, the anterior talofibular ligament and the lateral ankle capsule , an established mouse model of AOA and ankle pain. Both bone marrow (BV/TV) and trabecular bone parameters were significantly lower in 12-week AOA mice , B. By sry group , and PGEry group , suggestry group , suggest+ sensory nerve fibers in the AOA human samples compared to the normal healthy talus . These specimens were systemically scanned and analyzed by μCT. The images demonstrated the specimens included the serial sagittal sections  and showhy talus . TogetheCox2, and thus elimination of Pge2 expression, in osteoblast lineage cells or knockout of Ep4 in sensory nerve blunts bone formation in response to mechanical loading. And sensory denervation also significantly reduces mechanical loading-induced bone formation. Moreover, mechanical loading induces CREB phosphorylation in the ARC to inhibit sympathetic Th expression in the PVN, thus promoting osteogenesis. Therefore, our data demonstrate that the hypothalamus perceives elevation of bone PGE2 in response to mechanical loading to maintain bone remodeling, structure and homeostasis.Weight-bearing bones undergo constant remodeling or modeling by transforming mechanical signaling into biochemical signals in bone cells. The mecCox2 or sensory Ep4. This suggests that mechanical loading acts along a PGE2-EP4 sensory axis to transmit the change in peripheral status to the hypothalamus to promote a compensatory response. In this manner, proper skeletal interoception is achieved.Bone formation during remodeling under mechanical loading is an energy intensive process consuming glucose, ATP, oxygen and free fatty acids–44. TherNpy promoter to downregulate the expression of hypothalamic NPY -PVN (TH) circuitry acts upstream to regulate TH expression to mediate the mechanical loading interoceptive pathway.THactivity . We prevactivity . Here, wTh expression by ChIP assay. Notably, we found that mechanical loading promotes the elevation of pSTAT3 levels in the PVN, perhaps via the ARC neural circuitry, and that the elevated pSTAT3 in turn binds to the promoter region of Crem, the gene that encodes the inducible cAMP early repressor, ICER, elevating its expression. ICER, in turn, binds to the promoter of Th to suppress its expression, thus suppressing sympathetic tone to promote bone formation. Together, these findings show that hypothalamic regulation of NPY and TH activity in response to mechanical loading coordinates energy metabolism with bone structure remodeling. Thus, the brain is essential for the control of mechanical loading-induced bone formation.We further identified the mechanistic pathway in the PVN that regulates + osteoclasts in the talus from either healthy or AOA mice talus or in talus samples from humans with AOA. Bone remodeling is initiated by osteoclastic bone resorption, which is coupled with osteoblastic bone formation(+ osteocytes in mouse talus than in the calcaneus and tibia. The number of Ctsk+ osteocytes in talus were significantly increased after 7 days of TS or 8 weeks after AOA surgery, and this increase is accompanied by bone loss. Similarly in the human talus, we detected no TRAP+ osteoclasts from either normal human or from patients with AOA. However, CTSK was expressed in both normal and AOA talus, and its levels were significantly higher in the AOA talus and accompanied by significant bone loss compared to the healthy controls. This suggests that in the talus CTSK+ osteocytes likely perform the resorptive function usually mediated by osteoclasts. Indeed, the sympathetic nervous system promotes osteocyte-driven bone loss by secretion of extracellular vesicles containing bone-degrading enzymes for perilacunar bone resorption during lactation (The talus in the ankle bears the highest body weight. Ankle oformation–51. Thisactation . It appeactation . The finIn summary, our results show that the hypothalamus regulates bone remodeling and structure by perceiving elevated bone PGE2 concentrations that occur in response to mechanical loading. The axis of mechanical loading—PGE2-EP4 signaling—ARC—PVN—SNS acts as a skeletal interoceptive ascending pathway to transmit and process peripheral signals to the brain to promote bone remodeling. Our results suggest skeletal interoceptive regulation of osteocyte-mediated resorption for weight-bearing bones, including cortical bone, acts to maintain bone homeostasis upon mechanical loading. If this system acts chronically to excessive levels, such as in disease states, then this may explain the pain associated with such conditions, with implications for potential treatment.


Endoplasmic reticulum (ER) is the largest membrane-bound compartment in all cells and functions as a key regulator in protein biosynthesis, lipid metabolism, and calcium balance. Mammalian endoplasmic reticulum has evolved with an orchestrated protein quality control system to handle defective proteins and ensure endoplasmic reticulum homeostasis. Nevertheless, the accumulation and aggregation of misfolded proteins in the endoplasmic reticulum may occur during pathological conditions. The inability of endoplasmic reticulum quality control system to clear faulty proteins and aggregates from the endoplasmic reticulum results in the development of many human disorders. The efforts to comprehensively understand endoplasmic reticulum quality control network and protein aggregation will benefit the diagnostics and therapeutics of endoplasmic reticulum storage diseases. Herein, we overview recent advances in mammalian endoplasmic reticulum protein quality control system, describe protein phase transition model, and summarize the approaches to monitor protein aggregation. Moreover, we discuss the therapeutic applications of enhancing endoplasmic reticulum protein quality control pathways in endoplasmic reticulum storage diseases. The ER is a single membrane-enclosed organelle within eukaryotic cells and plays crucial roles in diverse cell functions such as protein synthesis, lipid trafficking, calcium homeostasis, redox regulation, and cellular metabolism . AlthougWhen ER protein quality control system is insufficient to clear misfolded proteins during pathological conditions, faulty proteins accumulate progressively and may form large protein aggregates, thereby disrupting ER homeostasis and cellular functions. Both ER stress and UPR dysfunction have been shown to play important roles in the etiology of many cancers and neurodegenerative disorders such as Alzheimer disease and Huntington disease . NotablyIn this work, we outline ER protein quality control system, summarize protein aggregation model and detecting tools, and exemplify the therapeutic targets of ER protein quality control machinery in two different ERSDs.There exists an oxidative environment involving thiol-disulfide pairs in the ER lumen, which is crucial for disulfide formation and proper protein folding . The redThe Ero1-PDI redox cycle is pivotal in ER oxidative protein folding and highly conserved across different species. The glycoprotein Ero1 introduces the formation of de novo disulfide bridge via oxidating the PDI and transferring electrons to molecular oxygen, in which hydrogen peroxide is synthesized as a byproduct. Mammalian Ero1 exists in two different types: Ero1α has a broad expression pattern, while Ero1β is present in secretory cells . The EroMammalian UPR is to sense and transmit ER stress signals to the cytosol and other organelles such as the nucleus. The UPR consists of three different signaling cascades triggered separately by protein kinase RNA-like ER kinase (PERK), activating transcription factor 6 (ATF6), and inositol-requiring protein 1α (IRE1α) . All thein situ, whereas the ATF6 activation is accompanied by its disulfide reduction and cleavage in the Golgi  and hydroxymethylglutaryl reductase degradation protein 1 (Hrd1) is the best-studied translocation channel in mammalian cells . The SelApart from the misfolded proteins, ERAD has the capacity to manage properly folded proteins and thus governs their expression abundance . This kiER-phagy is an orchestrated system to remove ERAD-resistant misfolded proteins and insoluble protein aggregates from the ER via the lysosomal degradation pathway . Beyond Akita proinsulin mutants are disposed from the ER by this macro-ER-phagy  in a neutral pH solution is found to self-assemble into protein crystals in vitro . Overexpin vitro . The ovein vitro . Unlike in vitro . These oin vitro. Since it is difficult to forecast when and where the aggregation of faulty proteins happens in multi-cellular organisms, the in vivo assessment of protein aggregation is extremely challenging. Thus, the spontaneous aggregation of purified recombinant proteins in vitro provides a chance to assess the kinetic process of protein aggregation.There exist limitable approaches to characterize protein aggregates , most ofSize exclusion chromatography (SEC), dynamic light scattering (DLS), analytical ultracentrifugation (AUC), and atomic force microscopy (AFM) have been employed to capture the early aggregation events of soluble protein oligomers . Each dein vitro characterization of protein aggregation may mistakenly recapitulate protein aggregation process in vivo, the overexpression of fluorescently labeled proteins in cell line has been utilized to characterize the dynamic features of protein aggregation in living cells   . The AATin (AAT) . Neverthin (AAT) , therebyAmong over 100 AAT mutations, the Z-AAT is the most severe mutant affecting ∼1 in 1,500 newborns worldwide . The folAlthough functional AAT administration can be used to treat AATD patients with emphysema , this auin vivo process of protein aggregation. The stable overexpression of specific protein in cell lines may facilitate protein aggregation behavior via inducing protein overcrowding and cellular stress, which contributes to the artificial peculiarity of cellular models. In this scenario, it will be reasonable to employ primary cell culture or zebrafish model to investigate the dynamic features of ER protein aggregation in vivo. Moreover, as liquid-liquid phase separation conduces to the formation of membraneless compartments in eukaryotic cells (in vivo, especially in animal disease models. Since the UPR, ERAD, and ER-phagy exist in all mammalian cells, the feasible path to address the above issue is utilizing the animal model with deletion of at least one ER quality control pathway. The aging has been associated with ER stress and UPR impairment (C. elegans (Despite recent advances, there are many open questions to be addressed in the future. The identification of mutant protein aggregates and inclusions in the ER is qualitative without the description of dynamic protein aggregation. Thus, more studies are needed to explore whether the aggregation of misfolded proteins in the ER follows the seeding-nucleation model. The cellular models have been taken to investigate ER protein aggregation by stably overexpressing protein in living cells , but theic cells , it is ipairment . Chronic elegans , while t elegans . As the  elegans . For exa elegans . In thes


Increasing efforts toward the prevention of stress-related mental disorders have created a need for unobtrusive real-life monitoring of stress-related symptoms. Wearable devices have emerged as a possible solution to aid in this process, but their use in real-life stress detection has not been systematically investigated.We aimed to determine the utility of ecological momentary assessments (EMA) and physiological arousal measured through wearable devices in detecting ecologically relevant stress states.Using EMA combined with wearable biosensors for ecological physiological assessments (EPA), we investigated the impact of an ecological stressor  on physiological arousal and affect compared to a control week without examinations in first-year medical and biomedical science students . We first used generalized linear mixed-effects models with maximal fitting approaches to investigate the impact of examination periods on subjective stress exposure, mood, and physiological arousal. We then used machine learning models to investigate whether we could use EMA, wearable biosensors, or the combination of both to classify momentary data  as belonging to examination or control weeks. We tested both individualized models using a leave-one-beep-out approach and group-based models using a leave-one-subject-out approach.During stressful high-stakes examination (versus control) weeks, participants reported increased negative affect and decreased positive affect. Intriguingly, physiological arousal decreased on average during the examination week. Time-resolved analyses revealed peaks in physiological arousal associated with both momentary self-reported stress exposure and self-reported positive affect. Mediation models revealed that the decreased physiological arousal in the examination week was mediated by lower positive affect during the same period. We then used machine learning to show that while individualized EMA outperformed EPA in its ability to classify beeps as originating from examinations or from control weeks , a combination of EMA and EPA yields optimal classification . Finally, when comparing individualized models to group-based models, we found that the individualized models significantly outperformed the group-based models across all 3 inputs .This study underscores the potential of wearable biosensors for stress-related mental health monitoring. However, it emphasizes the necessity of psychological context in interpreting physiological arousal captured by these devices, as arousal can be related to both positive and negative contexts. Moreover, our findings support a personalized approach in which momentary stress is optimally detected when referenced against an individual’s own data. Stress-related mental disorders such as major depression and anxiety disorders have gained increased recognition in the public eye. While a vast body of research exists regarding these disorders, studies have mostly focused on retrospective assessments of afflicted individuals. More recently, an increased interest has emerged in determining what makes some individuals more resilient to developing these disorders than others -4. InvesPrevious studies have used ecological momentary assessments (EMA)  to invesThe emergence of widely accessible wearable biosensors has raised the question of whether these devices can be used for ecological physiological assessments (EPA), either as an add-on or an alternative to EMA, in mental health monitoring. Wearable biosensors offer continuous recording of autonomic physiological markers such as skin conductance (SC) and heart rate (HR). These measures have been extensively validated in laboratory-based studies using controlled stress-induction protocols , showingTo this end, we aimed to investigate the ability of active EMA measures, passive EPA monitoring, and the combination of these 2 methods to detect stress in real life. We investigated a population of first-year medical and biomedical students known to experience increased psychological distress . ParticiWe recruited 84 right-handed, first-year bachelor’s students in the medical or biomedical science majors from Radboud Health Academy spanning 3 academic years . Participants were recruited through flyer distribution, presentations in common lecture halls, and web-based advertisements. A participant withdrew during testing, resulting in a total sample size of 83 participants used in the analysis. The programs were selected due to their structured examination weeks that occur every 5th and 10th week of a semester, allowing us to examine a period with higher stress levels during examination weeks as an ecological prolonged stressor. Right-handed participants were selected as participants were instructed to wear watches on their nondominant hand to reduce motion-related noise, with studies showing better signal from the left wrist than the right . Only paParticipants completed 2 weeks of EMA, one during an examination period  and the other occurring on average 16 days  outside of these periods  versus the control week allowed us to determine individualized patterns of stress reactivity. During these weeks, participants received 6 surveys a day at fixed intervals through SMS text message links. Participants were given a 1-hour window to fill out the surveys (like previous studies ). IndiviEMA surveys consisted of questions regarding subjective stress used for validating our experimental paradigm and mood questions (PA and NA) relating to our subjective outcome measures filled in on a 7-point Likert scale. Questions in the validation set probed four types of stress, as follows: (1) event-related stress assessed the most prominent event that occurred in between EMA beeps; (2) activity-related stress questions probed the activity participants were engaged in upon receiving the beep; (3) social-related stress addressed stress that may arise from the social context participants were present in ; and (4) physical-related stress was used as a control measure to account for environmental and physical demands. Mood outcome questions consisted of 4 items assessing positive mood and 5 items assessing negative mood based on the positive and negative affect schedule (PANAS), as validated in previous work . EMA iteEPA data cleaning was performed using Python  . AdditioAll statistical analyses were conducted in R  using generalized linear mixed effects models and random forest models (lmer and randomforest packages) ,41. Initt tests against the mean subject-level bootstrap error. We tested the generalizability of the random forest models to a population level using a Leave-One-Subject-Out (LOSO) analysis in which models were trained on N-1 participants data set and tested on the removed participant, repeating until each participant had been removed once from the data set. Model predictions using the LOBO were then compared to those of the LOSO method to estimate the generalizability of machine learning models based on the data.One of our goals was to assess the usability of ambulatory, nonintrusive measures to determine whether someone is currently in a stressed state. To this end, random forest models were used to determine the ability to classify whether participants’ beeps were in the stress or control week using the collected EMA mood and ambulatory EPA outcome data. Due to the subjective nature of mood items, participant-centered mood was used in all models. We conceptualized mood and physiology as outcomes of stressed states based on previous findings ,43. IndiAll procedures carried out were approved by the regional medical ethical review board . Written informed consent was obtained from all participants in Dutch following an intake interview where a detailed explanation of the procedures was carried out. Participants were given unique identifiers to maintain anonymity for all data acquired, with encrypted key files maintained by selected study personnel. In order to ensure the anonymity of the wearable data, participants were also provided with a study-specific account for data synchronization instead of personal accounts. Participants who completed all parts of the study were awarded 150 euros (US $158). The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008.P<.001) and current reports of stress  in the examination stress versus control week. Social stress was not significantly different between the 2 weeks. The control items measuring physical stress also did not differ significantly between the weeks, showing that increases in subjective stress were likely due to our experimental manipulation instead of environmental or physical changes , and a decrease in PA  during the stress week (fdrP<.001), and maximum HR . In accordance with our expectations, we also saw an increase in NA , social , and physical stress . The opposite was true for PA for event-related , activity-related , social , and physical stress . The magnitude of SC responses was associated with activity , event  and physical stress . For HR measures, mean  and minimum  HR were negatively associated with social stress. Thus, within-beep fluctuations in subjective stress are associated with expected mood changes and increases in physiological arousal . We found a positive association between NA and activity-related , and mean , minimum , and maximum HR  but not fully , indicating potential additional mechanisms are at play. The effect of week type on the number of SC responses was not mediated by PA.Next, to confirm that the observed average decrease in physiological arousal observed during the stress weeks is due to the decrease in PA, we assessed whether PA statistically mediated the effects of week type on reductions in physiological arousal. We specifically focused on the arousal measures linked to subjective stress and PA: the number of SC responses and their magnitudes. Results indicated that PA significantly mediated the relationship between SC magnitude and week type , Model 2 , and Model 3  all performed above chance. Paired-samples, 2-tailed t tests comparing the within-participant error rates between the LOBO models showed that Model 3  outperformed Model 1 using mood alone , which in turn outperformed Model 2 using EPA alone . While overall the EMA mood models performed better, for some participants, models 1 and 2 had almost equivalent performance.We next examined to what extent prolonged stress  can be classified from individual beeps using machine learning based on affect, physiological arousal, or a combination of both using individualized LOBO models. The mean subject-level error was 33.45% (SD 2.21%) for Model 1 (based on affect), 36.11% (SD 2.72%) for Model 2 (based on physiology), and 29.87% (SD 3.45%) for Model 3 (based on affect and physiology combined). Hence, the combined model outperformed the single-variable models. All models performed significantly above chance on an individual level for all but one subject . Group-lWe next investigated the generalizability of these models from an individualized approach to a population-level one (using group-level classification) through LOSO cross-validation. M1 using affect , M2 using physiology , and M3 using the combination  were again tested against their bootstrapped counterparts.t test showed that only model 1 , and model 3  performed better than chance. Model 2 did not perform above chance .For some individual participants, LOSO models performed significantly above chance level  in classifying week type . Group-lt test with FDR correction. All individualized LOBO models performed better than the group-level LOSO models. LOSO Model 1 (mood) performed significantly worse than the equivalent LOBO model . LOSO Model 2 (physiology) was also significantly worse than the LOBO counterpart . LOSO Model 3 (combination) similarly performed worse than the LOBO model counterpart . In sum, individual models vastly outperformed group-based models.We additionally directly compared the classification errors between the individualized and group models for each participant using a paired-sample This study investigated physiological and psychological responses to ecological stressors in daily life  to determine the usability of passive monitoring technologies for detecting prolonged stress. We used EMA and EPA to track subjective stress, mood, and arousal-related physiology. Our findings confirmed an overall increase in subjective stress during examination weeks. As hypothesized during the stress week, NA increased and PA decreased. Contrary to what was expected, lower SC and HR arousal measures were recorded during the stress week. At a beep-to-beep time scale, increased subjective stress was associated with increased NA, decreased PA, and increased SC responses. Interestingly, PA was also associated with increased SC responses and partially mediated the between-week differences in SC we found. Thus, the observed decreases in physiological arousal measures were  due to a reduction in PA. Using a machine learning approach, we showed that the combination of individual mood and physiology was best able to detect whether individual beeps stemmed from stress or control weeks. We conclude that passive monitoring with wearable biosensors can detect prolonged stress, highlighting the importance of mood measures to dissociate positive and negative arousal.In line with previous work, the stress week resulted in increases in self-reported stress, validating our paradigm . We obseWe subsequently tested the ability of machine learning models to classify individual beeps as stemming from stress or control weeks with physiology, mood, or a combination of both. Physiology models could classify beeps almost as well as mood models (3.85% difference on average). However, and more importantly, combination models showed the highest accuracy. Hence, the addition of mood questions to physiological arousal provides valuable information for prolonged stress detection. This converges with the mixed models and mediation results: accounting for valence through mood is necessary to distinguish stress-induced from PA-induced arousal. Our findings provide a mechanistic explanation for why previous studies using SC trigger-based EMA to detect stress captured positive arousal instead . In addiBesides demonstrating the utility of physiological monitoring, our results highlight the importance of individualized approaches in stress detection. Classification models trained and tested on individuals’ own data (LOBO) performed significantly better than those trained on group data (LOSO). Our individualized approach offers drastic improvements in the classification of stress states in comparison with group approaches . This suWorth noting is that classification accuracy of our machine learning models was relatively low in this study compared to many other ML studies. Previous studies found limited applicability of such algorithms due to variance in ranges of physiological responses between participants . HoweverThis study provides early evidence for the successful detection of prolonged periods of stress in individuals. However, some limitations warrant discussion. This study was purely cross-sectional, meaning that we are unable to make connections in how our findings can be used for predicting mental health outcomes and resilience in the long term. Prospective and longitudinal designs with explicit measures of resilience are needed for this. This is also important within the context of promoting resilience, as prospective detection of vulnerability is the next step in this line of research, with the aim of identifying early warning signals . More reIt may also be argued that the uncontrolled nature of the study is a detriment to the findings and has an impact on the reliability of the proposed measure. However, the ecological validity of this study is rather a strength in providing a necessary translation of laboratory measures to a real-life setting . AdditioIn conclusion, this study shows that EPA may be used for monitoring stress-related mental health but highlights the importance of affect ratings to dissociate changes in arousal due to stress versus PA. A combination of physiology and mood measures is optimal for detecting prolonged stress, and personalized approaches to modeling these variables are necessary. If successfully implemented at a wider scale, our findings may have implications for disease prevention, potentially helping to reduce the overall disease burden of stress-related disorders through personalized early-warning systems and treatment strategies.