Plants have a high intrinsic capacity to regenerate from adult tissues, with the ability to reprogram adult cell fates. In contrast, epigenetic mechanisms have the potential to stabilize cell identity and maintain tissue organization. The question is whether epigenetic memory creates a barrier to reprogramming that needs to be erased or circumvented in plant regeneration. Early evidence suggests that, while chromatin dynamics impact gene expression in the meristem, a lasting constraint on cell fate is not established until late stages of plant cell differentiation. It is not yet clear whether the plasticity of plant cells arises from the ability of cells to erase identity memory or to deploy cells that may exhibit cellular specialization but still lack an epigenetic restriction on cell fate alteration. Consistently, bisulfite sequencing showed lower methylation at the WUS locus in the mutant  was also misregulated in the met1 mutant. These effects in the met1 background suggested a role for DNA methylation in regeneration but it was not clear if removal of DNA methylation at the WUS locus was necessary for regeneration.Studies investigating the role of chromatin changes in regeneration show involvement in both shutting down “old” cell fates and permitting upregulation of “new” cell fates during reprogramming from callus. One gene implicated in this transition, DOMAINS REARRANGED METHYLTRANSFERASE 1 and 2 (DRM1/DRM2), and CHROMOMETHYLASE 3 (CMT3)  could skip the competence step, forming shoots in cytokinin rich shoot inducing medium (SIM) without pre‐incubation in CIM  and (SAW2) were downregulated and also showed increased H3K27 methylation  gene, which was shown to recognize specific DNA sequences at H3K27me3‐marked genes  and the PRC2 complex (Matos, Lau, Hachez, Cruz‐Ramirez, Scheres, & Bergmann, FAMA could mediate H3K27 methylation of stomatal stem cell genes (Lee, Lucas, Goodrich, & Sack, FAMA recruits a complex that includes PRC2 to lock down differentiated cell fate in stomatal development (Matos et al., Interestingly, PRC2 was implicated in a somewhat similar “slipping back” phenotype in stomatal development. In wild type stomata, stem‐cell‐like meristemoid mother cells self‐renew and generate the precursors to the stomatal lineage (Bergmann & Sack, The two studies provide strong evidence that PRC2 can stabilize cellular differentiation independent of the early patterning mechanisms that establish cell fates since these phenotypes were observed after cells exited the meristem or progressed beyond early stomatal development. These studies did not specifically address the role of the PRC2 in regeneration, and it is not yet clear that the plant has or needs mechanisms to erase such an epigenetic control during endogenous regeneration. Root hairs and stomatal cells appear to represent quite stable differentiated fates, and these cells may never be employed for plant cell regeneration outside of the mutant phenotypes described above.6There is growing evidence in plants that epigenetic processes stabilize cell fate at least partially independently of early signals that specify fate. This appears to provide some memory of, at least, the developmental stage of a cell. Such a role is evident in recent studies showing that PRC2 stabilizes stomatal and root hair cell identity. For example, the switch from root hair to embryonic fate in the mutant PRC2 background occurred long after embryonic development was complete, presumably entailing ectopic activation of embryonic programs that are normally shut down. Indeed, chromatin level profiling shows that embryonic genes targeted by PRC2 are largely shut down in the adult root (Bouyer et al., Arabidopsis, callus was shown to originate from one specific tissue, pericycle (Sugimoto et al., Still, regeneration studies have begun to question whether the broad array of cells shown to demonstrate totipotency using hormone treatments truly represents the type of cells that participate in regeneration under endogenous conditions. For example, in In pursuit of the role of epigenetic memory as a gatekeeper to cell fate, one fundamental step is determining the extent to which chromatin marks reflect cell identity on a global level. One recent study showed that cells in the root meristem did indeed exhibit cell type specific methylation patterns (Kawakatsu et al., Overall, the evidence that persistent chromatin states present a barrier that the cell must overcome to regenerate is extremely limited, although the question is central to understanding the plant's high capacity to regenerate. Intriguingly, in mutants that lose almost all non‐CG methylation, a lengthy competence step typically required to induce regeneration through callus is no longer required, implying the competence step was necessary, in part, to alter the chromatin landscape. Such an erasure of methylation marks may occur through cell replication and dilution, as the study proposed, but it is not yet clear if reprogramming in plants requires cell division in any context. Most critically, to answer the question of whether dedifferentiation in plants requires an erasure of chromatin‐encoded memory, more evidence documenting the requirement to erase epigenetic marks during regeneration and cellular reprogramming is needed.


The published paper  containsThe errors are a result of the fortification level standards for rice being incorrectly interpreted as being in mg/kg instead of mg/100 g  and therWe apologize for any inconvenience caused to readers.


Thank you for the opportunity to respond.1As with many large‐scale research projects, we had more information than was possible to include in a single paper. We thus prepared multiple papers addressing different aspects of the study: overall trends in dental caries—tooth‐level dataThe authors focus on a single paper.deft prevalence  in the latter relative to the former. We reasonedConsidering our whole work,Importantly, we highlighted2The authors erroneously state that we included a comparison community instead of measuring potential confounders. In fact, we collected socio‐demographic and behavioural data as part of our 2013/2014 survey. We computed caries estimates adjusting for differences between the Calgary and Edmonton samples and showed that estimates did not materially change.We considered several potential confounders, including sealants and public health programs.The authors correctly note that our outcome assessment was not blind and could have some bias. In our 2013/2014 survey, we collected fingernail clippings from a small random subsample (n = 35) in each city. Total fluoride intake based on those biomarkers, blind to city and fluoridation status confirmed substantially lower fluoride in Calgary (cessation) than in Edmonton (still fluoridated).3One could study the effects of fluoridation cessation by observing one community over time, as some have performed.4The authors raise concern about low participation rates, which they erroneously conflate with selection bias .5The authors described our assessment of smooth tooth surfaces and of children with some tooth decay, as “subgroup analysis.” We had good reasons for these assessments. We examined trends focusing only on smooth surfaces because these are most likely to be affected by fluoridation for the age group and time frame studied. We examined trends among children with some (>0) decay because decay experience in the population is skewed.DMFS among those with DMFS > 0, the direction of change became positive, although not statistically significant. We reasonedThe commentary did not mention our analysis of permanent teeth. The observed tooth‐level decrease (improvement) in permanent decay in CalgaryDMFS among those with DMFS > 0 was higher in the subsample  than in the full sample.Increased bottled water consumption was one of several possible explanations offered for the increase in primary tooth caries. Perhaps more relevant for this was our analysis of lifelong residents who report usually drinking tap water. If there is an effect of fluoridation cessation on dental caries, it should be stronger in this subsample. Although estimates were based on small numbers, and again we are limited by the absence of this information at precessation, they were consistent with an apparent increase in permanent tooth smooth‐surface caries in Calgary: the 2013/2014 Calgary estimate of mean 6The authors argue that randomized controlled trials (RCTs) are needed, a comment which neglects that this population‐level measure is not under researcher control. While one might theoretically envision a cluster‐randomized design,They also assert (unreferenced) that “next in order of quality, after RCTs, is the longitudinal study with individual‐level information on the same subjects over time.” Instead, one might argue that a next‐best design would incorporate an individual‐level longitudinal component  and a cross‐sectional time‐series component (to compare children of the same age at different times). These are different but equally important questions here. One model is the British birth cohort studies, with staggered cohorts of individuals.While we agree with the value of stronger designs, one must be thoughtful about evaluation of public health measures, which by definition are complex and context‐dependent.7Studies of fluoridation cessation and dental caries are few in number, highly diverse in time and place, and variable in quality.


Providers have traditionally established priorities for quality improvement; however, patients and their family members have recently become involved in priority setting. Little is known about how to reconcile priorities of different stakeholder groups into a single prioritized list that is actionable for organizations.To describe the decision‐making process for establishing consensus used by a diverse panel of stakeholders to reconcile two sets of quality improvement priorities  into a single prioritized list.ICU). Proceedings were audio‐recorded, transcribed and analysed using qualitative content analysis to explore the decision‐making process for establishing consensus.We employed a modified Delphi process with a diverse group of panellists to reconcile priorities for improving care of critically ill patients in the intensive care unit , amalgamating priorities (negotiating priority scope), considering evaluation criteria and having a priority champion.Panellists rated and revised 28 priorities over three rounds of review and reached consensus on the “Top 5” priorities for quality improvement: transition of patient care from Our study demonstrates the feasibility of incorporating families of patients into a multistakeholder prioritization exercise. The approach described can be used to guide consensus building and reconcile priorities of diverse stakeholder groups. First, health‐care providers  and decision makers  generated a comprehensive list of candidate daily care practices in the ICU that warrant improvement and subsequently selected nine practices as priorities for quality improvement initiatives.2Using the aforementioned two sets of priorities , regardless of the other panellists’ ratings, were advanced for further deliberation. This was designed to ensure that when a stakeholder group was unanimous in selecting a given priority, the other stakeholders could not eliminate it. Based on panellists’ feedback in Round 1, the priorities were amalgamated and/or revised prior to Round 2.2.4.2The in‐person meeting was audio‐recorded and transcribed verbatim for the purpose of content analysis. One researcher (RBM) recorded qualitative observations and memos during the event. Two researchers  independently conducted a conventional qualitative content analysis of the data.2.5We obtained written consent from all participants to audio‐record the proceedings. The Conjoint Health Research Ethics Board, University of Calgary (REB13‐1157), approved this study.33.1We invited nine individuals to participate in the consensus process, and all nine individuals agreed to participate (participation rate: 100%). The flow of the priorities across the three rounds of panel review during the modified Delphi process is depicted in Figure 3.2Four main themes related to the decision‐making process to establish consensus for priorities for quality improvement were identified from the audio data and notes collected during the in‐person meeting: (i) storytelling, or sharing personal experiences; (ii) amalgamating or negotiating the scope of focus; (iii) consideration of evaluation criteria ; and (iv) having a priority champion Table .3.2.1Storytelling or sharing personal experiences” was an important contributor to how decisions were made during the consensus process. During round‐table discussions, several panellists, including family members and providers, shared personal experiences. A panellist described a lengthy wait as his/her daughter was undergoing an elective procedure, after which the panellist and his/her family had poor communication with the surgeon, and how this resulted in anxiety. The panellist juxtaposed the experience, which involved minor elective surgery to that of families of critically ill ICU patients and stressed the importance of family presence and effective communication. The sharing of personal experiences contextualized the concept of gaps between what best evidence suggests patients should receive and what they actually receive as care (evidence‐care gap)“And so eventually at about an hour and 45 minutes, the surgeon comes out and I knew exactly what happened ‘cause he passed [us] to talk to another family first. So he did another case without coming out [to speak with us]… my wife was decompensating, I was a little bit concerned. I couldn't imagine if my child or my loved one was actually in a life or death situation, not having information immediately’’.“3.2.2“Amalgamating or negotiating the scope of focus” was a critical strategy used by the panellists in moving towards consensus in their decision‐making process. For example, panellists began the in‐person meeting by suggesting that several priorities be amalgamated prior to the first in‐person voting round  to form a single priority entitled, “family presence and effective communication” , amalgamating priorities (negotiating the scope), consideration of evaluation criteria, and having a priority champion. The priorities can be used to guide quality improvement initiatives and the themes to guide consensus methods.There has been significant investment in priority setting across diverse fields in health‐care employing different methods including expert panels, focus groups, voting surveys, interviews and consensus meetings.Storytelling is a universal form of communication: stories are creative representations of a person's experiences.Amalgamating or negotiating the scope of a priority can be important in establishing consensus.Consideration of criteria is essential in focusing a discussion towards consensus.Champions influence the selection of priorities. For example, Hutten et al. conducted a priority‐setting study on psychological treatments and services for people experiencing longer‐term depression using multiple stakeholder views.priority champions) naturally evolved during the round‐table discussions in our consensus workshop, helping to galvanize panellists to consensus. The use of idea champions needs to be carefully managed and monitored to mitigate the introduction of biases during group decision making, such as “groupthink,” which occur in situations where individuals avoid raising controversial issues.The results of our study should be interpreted in the context of its strengths and limitations. Three primary limitations should be considered. First, our panellists were purposefully selected from participants in previous phases of the research programme. Although participants represented different constituents and geographical regions, their views may not be representative of the broader ICU provider, decision maker, family and patient population. However, the original list of 28 priorities shared with panellists at the start of the consensus process was developed through a population‐based initiative that incorporated the perspectives of 1,135 providers and decision makers and 32 patients and family members. Second, our panel membership did not include an ICU survivor. The severity and complexity of illness warranting care in the ICU often limits patient participation in care.5Historically, providers and decision makers have established priorities for quality improvement. Our study demonstrates the feasibility of engaging the families of patients in this process and achieving consensus among a diverse group of stakeholders. Storytelling , amalgamating priorities (negotiating the scope), consideration of evaluation criteria and having a priority champion appear to be important for establishing consensus. The approach employed in our study can be used to establish consensus among diverse stakeholder groups.None to declare.All authors  contributed to the study's conception, design and interpretation. EM and MLP conducted the analyses. EM and JMB drafted the manuscript, and all authors  assisted in the successive revisions of the final manuscript. SMB and HTS secured funding for the work. The final version has been seen and reviewed by all authors , and they assume responsibility for the integrity of the data and the accuracy of the analysis. Click here for additional data file. Click here for additional data file. Click here for additional data file. Click here for additional data file.


Increasing numbers of children with HIV are surviving to adolescence and encountering multiple clinical and social consequences of long‐standing HIV infection. We aimed to investigate the association between HIV and disability, social functioning and school inclusion among 6‐ to 16‐year‐olds in Zimbabwe.HIV‐infected children receiving antiretroviral therapy from a public‐sector HIV clinic and HIV‐uninfected children attending primary care clinics in the same catchment area were recruited. Standardised questionnaires were used to collect socio‐demographic, social functioning and disability data. Multivariable logistic regression was used to assess the relationship between HIV status and disability and functioning.vs. 18.5%, P < 0.001). HIV‐infected children were more likely to report anxiety (adjusted odds ratio (aOR) 4.4; 95% CI 2.4, 8.1), low mood  and difficulty forming friendships  than uninfected children. Children with HIV also reported more missed school days, repeating a school year and social exclusion in class. These associations remained apparent when comparing children with HIV and disability to those with HIV but no disabilities.We recruited 202 HIV‐infected and 285 HIV‐uninfected children. There was no difference in age and gender between the two groups, but a higher proportion of HIV‐infected children were orphaned. The prevalence of any disability was higher in HIV‐infected than uninfected children (37.6% Children with HIV commonly experience disabilities, and this is associated with social and educational exclusion. Rehabilitation and support services are needed to facilitate educational attainment and social participation in this group. Of the estimated 1.8 million children who are infected with HIV, 90% live in sub‐Saharan Africa (SSA) HIV may lead to impairments through sequelae of infections that occur as a result of immunosuppression. For example, HIV‐mediated immunosuppression leads to opportunistic infections such as CMV that can result in visual impairment These impairments may, in turn, negatively impact on social functioning and schooling We conducted a cross‐sectional study to investigate the association between HIV and disability, social functioning and school inclusion among HIV‐infected children compared to uninfected peers in Zimbabwe.HIV‐infected children aged 6 to 16 years and receiving either first or second line ART for at least 6 months were consecutively recruited from Harare Central Hospital (HCH); this is the largest public‐sector hospital in Harare, providing HIV care for more than 3000 children. Acutely ill children, not residing in Harare and without guardian consent and/or participant assent, were excluded. Recruitment was restricted to the first five eligible participants a day for logistical ease.A comparison group of HIV‐uninfected children aged 6–16 years were recruited from primary health care clinics (PHC) in seven high‐density communities in the same catchment area served by the clinic from which the HIV‐infected participants were enrolled. Provider‐initiated HIV testing and counselling are offered by PHCs to all attendees regardless of the reason for presentation.+ , and HIV viral load was measured using COBAS Ampliprep/Taqman 48 Version 2.0 .Socio‐demographic data including age, sex and orphan status were recorded. Trained research nurses administered standardised questionnaires to collect data on disability, education and social functioning. The Washington Group/UNICEF Child Functioning and Disability 21‐Question Set was administered to children and their caregivers to assess disability Ethical approval was obtained from the Medical Research Council of Zimbabwe (MRCZ/A/1856), the Biomedical Research and Training Institute (AP125), Institutional Review Board, Harare Hospital Ethics Committee and the London School of Hygiene and Tropical Medicine (LSHTM) Ethics Committee (8263). All guardians gave written consent, and participants gave assent to participate in the study.Data were collected using paper forms and entered into a Microsoft Access (MSACCESS) database using optical mark recognition software . Paper forms were manually checked for missing data and inconsistencies before being captured using TELEFORM which has inbuilt quality control checks. Further internal and external consistency checks were carried out after the data were committed into the database using MSACCESS database queries.a priori defined variables of age and sex. Orphan status and previous infection/co‐morbidity did not significantly affect the fit of the model (P < 0.05) on likelihood ratio testing and therefore were excluded. Hence, the final model was adjusted for age and sex alone.Data completeness was assessed by summary and descriptive statistics. There was a low proportion of missing data (<6%) in HIV‐infected and negative children for demographic, clinical, disability and school functioning and inclusion data. All statistical analyses were carried out using Stata v13.0 . The prevalence of functional difficulties and disability by HIV status was summarised as frequencies and percentages for each variable. Continuous variables were summarised as mean (SD) when normally distributed and median (IQR) when not. Univariable logistic regression analysis was used to compare functional, school and social outcomes between HIV‐infected and uninfected children. Multivariable logistic regression was used to adjust each functional outcome of interest for We recruited 202 HIV‐infected children  and 285 uninfected children . There was no significant difference in age or sex between the two groups, but HIV‐infected children were more likely to be orphaned   was higher in HIV‐infected than uninfected children (37.6% compared to 18.5% P < 0.001). HIV‐infected children were significantly more likely to report visual , hearing , speech , learning  and memory problems , low mood  and difficulty forming friendships  than their uninfected peers. There was no significant association between age at HIV diagnosis, CD4 count, viral load, ART duration or previous co‐morbidity and disability among HIV‐infected children Table .vs. 0.3 days (range 0–7 days). HIV‐infected children more frequently reported not getting help from teachers  or friends  at school. They were more likely to feel excluded in lessons and activities  and more likely to be hit, hurt or have nasty things said to them by other children . Among children with HIV, those with disabilities were less likely to be enrolled in the same school grade as their peers  and more likely to repeat a school year  than HIV‐infected peers without disability. They were also more likely to report that their peers did not look up to them as leaders  and that they experienced violence from their peers  . However, children living with HIV were more likely to have repeated a school year  and on average missed more days of school in the preceding month (mean 0.9 days (range 0–15 days) This study demonstrates a high prevalence of physical and cognitive functional difficulties in HIV‐infected children. HIV‐infected children are more likely to report low mood/anxiety and difficulty forming friendships, repeating a school year and to experience poor social support at school, particularly those who have both HIV and disability.Other studies have reported increased physical, sensory and cognitive difficulties in HIV‐infected children compared to uninfected children Our study showed that HIV has a negative association with forming friendships, school progression and inclusion in SSA, and this is worse among children with disability. A recent cross‐sectional study of hearing impairment in 380 HIV‐infected Malawian children with extensive audiological testing  showed that one quarter (24%) of children had hearing loss, and of those with hearing loss, 23% required a hearing aid to be fitted. Children with hearing impairment were less likely to attend school and had poorer emotional and school functioning than HIV‐positive children without hearing loss. Furthermore, only 40% of caregivers accurately perceived their child's hearing loss, and few had sought treatment, implying that routine screening may be necessary Evidence in the wider literature for the link between disability and HIV disease severity and treatment factors has been inconsistent. Previous studies have shown an association between CD4, viral load at enrolment, ART duration and disability. The above‐mentioned study in Malawi One study reviewed the inclusion of disability within 18 national strategic responses to HIV and AIDS in Eastern and Southern Africa and identified that 9 of 18 countries (50%) provided HIV prevention and only 5 of 18 countries (27%) recognised the need for specific impact mitigation and support services interventions for people with disabilities To our knowledge, this is the first study to estimate the prevalence of disability and its association with school and social functioning in HIV‐infected children. A comparison group was included, and participants were not selected on the basis of symptoms. Limitations of this study include possible misclassification and/or recall bias from the use of self‐reported outcome measures for functional difficulties and disability without contemporaneous clinical measures of impairments. There was also no information available on the nature and cause of these impairments. In addition, there is the possibility of selection bias and unknown confounding through the use of non‐probability‐based sampling. Unfortunately, socio‐economic data such as household income and size, asset ownership, caregiver education and food security were not available which meant that analyses could not be adjusted for socio‐economic status.Although it is evident that disability is common in HIV‐infected children and has a major impact on their lives, further epidemiological and operational research specifically analyses each type of impairment to understand which interventions are required to inform the design of effective rehabilitation services and guide policy decisions. Examples of the type of interventions for HIV‐infected children that could be introduced include (i) routine screening for impairments (ii) linking HIV care to rehabilitation and additional clinical services (e.g. ENT in the case of hearing impairment) (iii) interventions to promote school inclusion and social acceptance among children with HIV .This study suggests that physical and cognitive functional difficulties are common among children with HIV. These difficulties are associated with school exclusion, including impaired educational progress, difficulty forming friendships and reduced ability to participate in lessons and activities. Further work is required to develop tools to better detect and understand the need for rehabilitation and support services within paediatric HIV programmes.


Despite the multitude of stents implanted annually worldwide, the most common complication called in‐stent restenosis still poses a significant risk to patients. Here, a “smart” stent equipped with microscale sensors and wireless interface is developed to enable continuous monitoring of restenosis through the implanted stent. This electrically active stent functions as a radiofrequency wireless pressure transducer to track local hemodynamic changes upon a renarrowing condition. The smart stent is devised and constructed to fulfill both engineering and clinical requirements while proving its compatibility with the standard angioplasty procedure. Prototypes pass testing through assembly on balloon catheters withstanding crimping forces of >100 N and balloon expansion pressure up to 16 atm, and show wireless sensing with a resolution of 12.4 mmHg. In a swine model, this device demonstrates wireless detection of blood clot formation, as well as real‐time tracking of local blood pressure change over a range of 108 mmHg that well covers the range involved in human. The demonstrated results are expected to greatly advance smart stent technology toward its clinical practice. For example, in the United States, more than two thousand patients die from CVD each day.LC) resonant tank coupled with MEMS capacitive pressure sensors, and magnetoelastic resonator), and active sensing stent integrated with application‐specific integrated circuit and sensor chips have been proposed and widely studied.The need for a rapid, noninvasive, and easily accessible method to detect in‐stent restenosis has led to the development of “smart” stents with self‐sensing and communication ability via integration of micro‐electromechanical systems (MEMS), microelectronics, and antenna functions with stents.Here, we advance smart stent technology by achieving its compatibility with the standard PCI procedure through enhancing the electromechanical performance of the sensor‐integrated stent device, and demonstrating its expected functionality using a swine model. The primary focus of this work with respect to its engineering aspect is to build a balloon‐expanding smart stent integrated with a MEMS sensor that simultaneously offers both high‐performance wireless sensing function and mechanical robustness. To this end, we develop a stainless‐steel chip of capacitive pressure sensor and its microwelding‐based packaging on stents.22.1FigureLC tank, whose resonant frequency  represents the on‐site condition of surrounding blood pressure, which may be interrogated using a handheld wireless reader with an external antenna by establishing inductive coupling with the antenna stent.2.2Figure2) and low profile (200 µm thick) to minimize the disturbance of normal blood flow, and is made of all biocompatible materials.LC tank, i.e., the sensor‐stent combination. For example, microwelded bonds showed 2× larger shear strength and 6× higher electrical conductance when compared with those of conductive epoxy as we reported.For sensor integration with the antenna stent, we use laser microwelding for these two stainless‐steel parts Figure b instead2.3FigureIn order to translate this technology from bench to bedside, the smart stent device needs to meet the same standard as commercial stents. In light of this, we assessed the compatibility of fabricated prototypes with a PCI procedure and relevant devices through bench testing. For delivery testing, two types of commercial balloon catheter systems with different specifications  were used depending on the stent's length and diameter. Initially, a prototype smart stent was mounted onto the balloon region of the catheter . This was followed by the use of a stent crimper  to exert a radial compression force to the stent device Figure3a to rAfter crimping, the smart stent  has to be inserted through a sheath in order to reach the artery. This requires forcibly passing through a hemostatic valve. As shown in Figure Passing through the sheath‐valve channel, the device on the balloon catheter was delivered into a silicone‐based artificial artery  for the final deployment. Deionized water was injected into the balloon with an insufflator  to fully inflate the balloon with hydraulic pressure up to 16 atm. This full inflation was reached in three steps, so that the stent device was expanded to three different diameters, i.e., 4, 5, and 6 mm. Figure The laser‐microwelded prototypes  showed ≈80% success with no evidence of mechanical or electrical failure, while those integrated with conductive epoxy  showed frequent breakaway of the sensors from the stents when experiencing the same steps. We also verified that the microwelded samples also provided notably higher long‐term reliability than conductive epoxy joint through accelerated aging test (see the Supporting Information regarding the comparative experiment and results). These results indicate that this new generation of smart stent is highly robust and potentially useful for clinical practice.2.4LC circuits, and their frequency spectra of inductive phase were wirelessly measured using a spectrum‐impedance analyzer  via inductive coupling as shown in Figure S4 (Supporting Information). Both samples exhibited almost identical resonant frequencies (≈130 MHz) while significantly different amounts of the phase dip or Q factor  were connected with the impedance analyzer to read its serial resistances (RS) for both devices at their resonant frequencies; after closing the circuit, they were expanded to 4 mm in diameter using a balloon catheter to characterize their resonances in the wireless manner same as the above measurement. The results  were coupled with fabricated capacitive pressure sensors (with different base capacitances associated with fabrication variation), one with laser microwelding and the other with the conductive epoxy for comparison. The two ends of the open device , a 20 mm long device also fully expanded in the same graft, and another 30 mm long device expanded in a 5 mm diameter graft of the same type. Figure Γ) magnitude using the spectrum analyzer to which the antenna was connected (through a Bayonet Neill–Concelman (BNC) coaxial cable, to extend the working distance between the analyzer and the antenna). Figure −1). The shifts of the resonant frequency were clearly resolved toward lower values (due to increase of the sensor's capacitance) as pressure was increased with an increment of 12.4 mmHg. A total frequency shift of 200 KHz was observed over the full pressure change of 62 mmHg, suggesting an average sensitivity of 93 ppm mmHg−1. The pressure increment of 12.4 mmHg was found to represent a pressure resolution that the device could provide with the wireless interface used. It should be noted that this resolution is 5× higher than that of the previously reported stent device tested in air,Wireless hydrodynamic pressure sensing was tested on the fabricated prototypes in a flow circulation loop  as illustrated in Figure S5b (Supporting Information). A commercial pump  was used to force the water to flow through a stent device deployed in the 6 mm diameter commercial graft noted above. The pressure exerting on the device was controllable through two manual valves located upstream and downstream of the device. A reference pressure sensor  was connected to the flow loop to read intraluminal pressure applied to the device during the test . Frequency response of the device within the graft was wirelessly monitored through an external antenna by tracking a reflection coefficient , which shifted to 39 and 42.5 MHz with blood flow (at a blood pressure of 79/52 mmHg and a MAP of 61 mmHg).The developed prototypes were tested using a swine model under ethics protocol #A11‐0067 approved by the University of British Columbia. A 6 month old, 28 kg female pig was used in this test. During surgery, the pig was fully anesthetized and its vital signs  were constantly monitored using a multiparameter physiologic monitor system . The blood pressure (systolic/diastolic) and heart rate before surgery were measured to be 99/61 mmHg and 115 per minute, respectively. Given the small size of animal's blood vessels, a surgical model was created using GORE‐TEX vascular grafts. In the first test, a 5 mm diameter graft that contained two fully expanded 30 mm long devices, one with functional pressure response and the other with no pressure response serving as a control, was placed in a bypass model . For this procedure, following administration of heparin, the carotid artery was ligated in its mid‐section, and the two ends of the graft anastomosed upstream and downstream of the ligature to establish a bypass. Following completion of the bypass, flow was restored through the bypass loop and two external antennae (one as a backup) were looped around the graft Figure5a. TheAs a preliminary test of device's sensing function, blood flow through the graft was mechanically restricted by clamping it while wirelessly monitoring the resonant frequency of the device. When downstream flow was restricted, intraluminal pressure experienced by the functional device lowered its resonant frequency as expected, whereas no frequency shift was observed with the control device. However, after repetitive stoppage of blood flow several times, the functional device became to show no frequency response to the flow restriction. It was visually verified (after incising the graft) that the graft formed a blood clot that blocked the blood flow across the device Figure b. AlthouFiguresIn order to perform real‐time tracking of blood pressure with the device, another test was conducted using the same pig. Following the same bypass model, another 6 mm diameter graft that contained two fully expanded functional devices (one with 30 mm length and the other with 20 mm length) was studied to compare the dimensional effect on in vivo wireless sensing. A medical pressure transducer  was used as a reference sensor to measure the local blood pressure. For this, a 20 gauge tubular catheter was inserted into the artery upstream of the bypass , and the other end of the catheter was connected to a transducer linked to the multiparameter physiologic monitor system. This system showed the local arterial blood pressure (read from the reference transducer), its temporal plots, and other vital signs on the monitor. The readout  indicates a certain level of variation in the blood pressure read using a hemodynamometer applied to a model's limb (89/42 mmHg) from the local arterial pressure near the graft read with the reference transducer (83/56 mmHg) . The base resonant frequency of the 30 mm stent was wirelessly detected to be 27.96 MHz at a MAP of 59 mmHg  using an external antenna. Its reflection coefficient magnitude was higher while frequency was lower, compared to those of the two  30 mm devices expanded in the 5 mm diameter graft from the first test and the 20 mm device expanded in the same 6 mm diameter graft. These results are presumed to be due to a higher inductance of the current device with larger dimensions. This outcome is consistent with the result discussed earlier with Figure 3LC tanks that served as stent‐based wireless pressure sensors. The gold and Parylene C coatings applied to the devices ensured both biocompatibility and X‐ray opacity of them. Moreover, the adopted microwelding integration method provided clear merits in increasing both mechanical robustness and electrical performance of the device. The microfabricated prototypes were robust enough to achieve compatibility with the standard catheter assembly and PCI procedures. The combination of thick gold coating and microwelding integration was highly effective to raise the device's Q factor, which in turn led to significant resolution enhancement in wireless pressure sensing. The prototypes deployed in the vascular grafts were tested to demonstrate wireless monitoring of in‐stent blood pressure using a swine model. These results from both the bench tests and the animal study advance smart stent technology further, toward its clinical evaluation and application for long‐term monitoring of implanted stents. The technologies of robust electromechanical integration and biocompatible packaging developed for the current device can benefit the development of other types of smart medical implants.In summary, we have demonstrated advanced smart stent technology using a MEMS‐sensor‐integrated antenna stent with enhanced electromechanical performances. The custom‐designed implantable capacitive pressure sensor chips based on medical‐grade stainless steel were laser‐microwelded on 20 and 30 mm length inductive antenna stents made of the same alloy to form passive resonant 4Fabrication of Inductive Antenna Stent: Similar to commercial stent production, the antenna stents were laser‐micromachined from medical‐grade 316L stainless‐steel tubing  after which electropolishing was performed to smoothen the machined surfaces. Two tab‐like structures (0.6 × 2.0 mm2) were fabricated at both ends of the stent to be used as the platforms for sensor integration. The tubing has to be annealed (either before or after laser patterning) so that the stent can be balloon expandable. Postannealing stainless‐steel of fabricated stents exhibited a yield strength of ≈310 MPa and an elongation of >45%, suitable levels that enabled mechanical functionality of the stent.Fabrication of Implantable Micropressure Sensor: The sensor microchip used to prototype the smart stent was constructed on the stainless‐steel substrate with a reference cavity, which was hermetically sealed at atmospheric pressure by bonding a polyimide–metal multilayered diaphragm on the substrate to form a parallel‐plate capacitive pressure sensor. The fabrication followed three main steps, i.e., stainless‐steel chip micromachining, thin sensing diaphragm formation, and thermal bonding and releasing. First, a micromachining technique called micro‐electrodischarge machining , capable of high‐precision shaping of bulk metals/alloys, was used to 3D pattern a 15 µm deep reference cavity (containing eight dead‐end holes for enhanced sensitivity) for each chip on 200 µm thick foil of 316L stainless steel and then dice each chip from the foil. Next, the diaphragm component was prepared by electron‐beam evaporation of multiple metal layers  on copper foil serving as their temporary substrate, followed by spin coating and curing of 5 µm thick polyimide film on the metal (titanium) surface. The stainless‐steel chips were then thermally bonded on the polyimide side of the diaphragm at 260 °C for 35 min while applying a static pressure (≈60 MPa). After bonding, the excess regions of the polyimide and titanium‐gold layers were removed by oxygen plasma and wet etching, respectively. The fabrication was finalized by releasing the sensor chips by etching away the entire copper foil and chromium layer. The fabricated sensors showed an average sensitivity of 156 ppm mmHg−1.Laser Microwelding Integration and Device Packaging: The laser microwelding process was conducted using a commercial system based on a Nd:YAG fiber laser with 1070 nm wavelength . For this system, a focused laser beam with spot diameters down to ≈25 µm enabled microscale and direct (no filler) welding at the interface between the sensor die and the stent. To minimize the heat‐affected zone and avoid thermal shock to the sensor, this process used the single‐pulse mode  instead of the multiple‐pulse or seam mode. A three‐axis micromanipulator  was used to precisely position the sensor microchip with respect to the stent's tab platform while they made direct contact with each other. With the above setting, fabricated sensor chips were microwelded onto the stents  by shooting the laser at multiple spots around their interface  copper wire. Finally, another 2 µm thick Parylene C film was deposited over the entire device to ensure both electrical insulation and biocompatibility on all exposed surfaces of the device.Surgical Model with Vascular Graft: For this model, a surgical cut‐down to expose the carotid artery was performed on an anesthetized pig . The carotid artery was dissected out and isolated. Heparin with a dose of 50 IU kg−1 was administered intravenously. The mid‐section of the carotid artery was ligated with a 2‐0 silk ligature. Blood flow through the carotid artery was temporarily suspended by vascular clamps placed on the artery. Two separate 12 mm long incisions (arteriotomies) were made in the artery proximal and distal to the silk ligature. The 5/6 mm GORE‐TEX graft with the expanded devices was beveled to fit the length of the arteriotomy and anastomosed in sequence by suturing it with 6‐0 polypropylene vascular sutures to the proximal followed by the distal arteriotomies. Prior to completing the anastomoses, flow was temporarily established to flush out any air or blood clots that may have accumulated in the graft and around the vascular clamps. After completing the anastomoses, the clamps were removed to allow blood to flow through the bypass graft.The authors declare no conflict of interest.SupplementaryClick here for additional data file.


We normally react to individuals who exclude us socially by either avoiding them or increasing our attempts to interact with them. The neuropeptide oxytocin can promote social bonds and reduce social conflict and we therefore investigated whether it facilitates more positive social responses towards individuals who exclude or include us. In a double-blind, placebo-controlled, between-subject design 77 healthy Chinese male and female participants received intranasal oxytocin (40 IU) or placebo before playing a modified virtual ball-tossing game with three fictitious partners who either showed exclusion, inclusion or neutral behavioral interactions with them. Results showed that both male and female subjects threw the ball more often to individuals who excluded rather than included them, although oxytocin did not alter this or awareness/feelings of exclusion or inclusion. However, when subjects returned a week later males, but not females, in the oxytocin group exhibited an increased liking for, and preference for playing again with, players who had previously excluded them. This oxytocin effect was positively associated with independent traits. Our findings suggest that in a collectivist culture oxytocin may promote the desire of males, but not females, with a stronger independent orientation to rebuild social connections with individuals who have previously excluded them. Being excluded or rejected is an aversive and painful social experience even when observing others suffering from it134The aversive experience imposed by social rejection results in immediate and long-term threats to feelings of belonging9Previous studies have demonstrated that the hypothalamic neuropeptide oxytocin (OXT) plays a critical role in promoting social bonds and prosocial behaviors1316171820222325A number of previous studies have investigated associations between OXT and social rejection using the Cyberball game paradigm. In this paradigm subjects play a ball tossing game with players via the internet who either exclude or include them during the game and, unbeknownst to them, are actually computer controlled32Previous studies investigating OXT effects on social exclusion or inclusion of the subjects themselves using the Cyberball paradigm have either investigated inclusion and exclusion effects separately in different rounds of the game353639404142Independent t-tests on scores showed that there were no significant differences between participants in the two treatment groups for any of the different behavior trait, social experience and mood questionnaires completed immediately prior to the experiment see . There wF2,146 = 11.95, p < 0.001, F2,146 = 3.26, p = 0.041, Post-hoc Bonferroni-corrected paired comparisons showed that participants threw more balls to players who excluded than included them (excluders: 36.11 ± 0.49% (mean ± SE), includers: 31.69 ± 0.73%, p < 0.001, Cohen’s d = 0.947) or were neutral  × 3  × 2  repeated ANOVA was performed. This analysis revealed a significant main effect of players  and negative PANAS scores  across groups in the second test. This may indicate that both groups were experiencing a more neutral mood after the task had been completed. There were also no overall group differences in participants’ FNQ scores in relation to their experience of playing the Cyberball game, other than participants in the OXT group reporting significantly stronger feelings of being involved in the game  was carried out on participants awareness of either being excluded or included by other players . This revealed no significant treatment or gender differences in awareness of inclusion or exclusion , although a greater proportion of subjects reported being aware of being included than excluded . There were no other significant main effects or interactions.A 2 (treatment: PLC/OXT) × 2  Chi-square test . A 2 (treatment: OXT/PLC) × 3  × 2  repeated ANOVA analysis did not reveal any main or interaction effects. Thus recognition accuracy was similar across player types and was not influenced by OXT.Subjects from both treatment groups had a relatively low mean recognition accuracy of the faces of players from the games played a week before (60–70%). There was no significant difference in recognition accuracy for familiar  and novel faces in the PLC vs OXT groups in the surprise memory task . Both genders showed this effect . A 2 (treatment: OXT/PLC) × 3  × 2  repeated ANOVA found a main effect of face pictures . In addition, OXT significantly increased likeability ratings given by males, but not females, for the faces of the familiar excluders compared to those of includers  and for neutral players . Increased likeability ratings for excluders were not significantly correlated with the number of times subjects threw the ball to them in the original game in either treatment group .A 2 (treatment: OXT/PLC) × 2 (face pictures: familiar/novel) × 2  repeated ANOVA on subjects’ likeability ratings revealed a main effect of face pictures  and that OXT significantly increased this preference  and correspondingly decreased the preference for includers  and decreased their preference for includer players .A 2 (treatment: PLC/OXT) × 3  × 2  repeated ANOVA was also performed to investigate differential preferences for playing again with specific types of players. Results showed a marginal main effect of player (p = 0.007), whereas those under PLC did not . Thus males, but not females, in the current study show a greater effect of OXT in promoting an increased preference for re-engaging with excluders if they also show stronger independent traits. Interestingly males, but not females, from both treatment groups showed a positive correlation between their overall collectivism score and the proportion of balls they threw back to the excluders in the original game . This was primarily driven by the horizontal component scores in males .We next specifically investigated associations between OXT effects on increased likeability and preference for playing again with excluders, particularly in males, and ICS scores to assess potential modulation by collectivism or independent orientations. As expected subjects in both treatment groups scored higher overall for collectivism compared to independence see . For theOverall our results showed that OXT did not either influence subjects’ choice of throwing the ball in the Cyberball game to players who either excluded or included them, or their awareness of or feelings towards being included or excluded. Interestingly, in both OXT and PLC groups, subjects threw a significantly greater proportion of balls to individuals who excluded them in the game. However, one week after the game playing experience subjects originally treated with OXT exhibited an increased liking of individuals who had previously excluded them and also a greater preference for playing with them again. This OXT effect was only significant in males and was strongest in subjects scoring higher in independent traits. Thus overall our results suggest that when males play simultaneously with those who both include and exclude them, OXT treatment makes them subsequently more likely to try and re-establish connections with those who have previously excluded rather than included them, particularly if they have a higher independent orientation.In agreement with previous studies on subjects from independent cultures OXT did not influence patterns of play with either includers or excluders during the Cyberball game in Chinese subjects3536et al. studyIn Chinese collectivistic culture there is an emphasis on the importance of group harmony so that individuals show greater moderation in distributing any kind of resource to avoid conflict and embarrassment and to promote group harmony and solidarityWhile there was no gender difference in terms of the greater proportion of balls thrown to excluding players during the Cyberball game, in males this was positively correlated with a collectivist orientation whereas in females it was not. Thus it is possible that Chinese male and female subjects had different motivations for playing more with excluder players during the game, with males perhaps doing so in order to try to bring outsiders into the social collective and reduce their potential threat, whereas in females it may perhaps have derived from a greater personal sense of worth as a result of an altruistic action.Our findings that OXT treatment increased a subsequent preference to play again with excluder players is in contrast to a previous study on subjects from an independent culture which reported that intranasal OXT increased the preference for subjects to play again with includers rather than excluders immediately after the gameThere is considerable research showing that we are more sensitive to negative emotional events and that they are preferentially processed by the brain relative to neutral and positive ones46We did not have an a priori hypothesis that there would be gender differences in the current study although the sex-specific effects of OXT we found provide further support for the growing number of studies suggesting that it may play rather different functional roles in males and females39404142Thus OXT may particularly promote attempts to restore social connections following social rejection in males rather than females to help reduce the risk of further social exclusion and potential conflict. This is in broad agreement with previous studies showing that OXT promotes positive social behavior in men, but not women, following couple conflict282930There are several limitations in the current study. First, we did not ask participants to rate their likeability of and preference for replaying with other players immediately after the Cyberball game. Given that OXT increased the likeability and preference choice for excluders even after one week, it is possible that this effect might also have occurred immediately after the Cyberball game. Second, the modification of the Cyberball game integrated both inclusion and exclusion during each round and this may have reduced the degree of exclusion experienced by the participant’s due to potential compensatory effects of simultaneously being included. This could have contributed to the observed effects and future studies would in particular need to consider whether OXT has similar effects in Chinese subjects following a stronger experience of exclusion during the game.t = 0.73, p = 0.468) treatment using a double-blind between-subject design. No subjects reported having any current or previous neurological or psychiatric problems and none were taking any medication for at least 4 weeks before or during the whole study. All of female subjects reported having regular menstrual cycles and were not pregnant . None of the female subjects reported taking oral contraceptives. Using cycle length information we calculated that 24 participants were in the luteal phase  and 13 in the follicular phase . All subjects were asked to abstain from caffeine and alcohol consumption during the 24 hours before the experiments. The study was approved by the ethical committee of the University of Electronic Science and Technology of China and the experiments were carried out in accordance with the latest revision of the Declaration of Helsinki. Each participant signed written informed consent and was paid 80 RMB for participating.Seventy-seven healthy students  were recruited from the University of Electronic Science and Technology of China and were randomly assigned to receive either PLC  or OXT , Beck Depression Inventory (BDI), Self-Esteem Scale (SES), State-Trait Anxiety Inventory (STAI), the Revised Cheek and Buss Shyness Scale (RCBSS), the Social Provision Scale (SPS), the Adult Autism Spectrum Quotient (ASQ), the Individualism and Collectivism Scale (ICS) and the Interpersonal Sensitivity Measure (IPSM). Details of the Chinese versions of these questionnaires and Cronbach’s alpha values for subjects in the current study are given in the 54555658The Cyberball task paradigm was similar to the original versionOne week after the initial Cyberball experiment subjects returned to complete a further three tasks but with no additional treatment. First, a surprise memory test was administered where 36 face pictures  were presented on a screen. After each picture subjects had to respond whether they had played with the person shown in the picture last week or not by pressing one of two keys (“Yes” or “No”) and were then asked to rate how much they liked them on a 1 to 9 scale. Next the subjects were given a preference task which consisted of 36 trials where three pictures of previous Cyberball players were presented simultaneously on each trial and they were asked to choose which one they would like to play with again. In each case the familiar players comprised an excluder, includer and neutral one from the first experiment but in different groupings from those used originally. Subjects indicated their choice by pressing one of the three keys representing the three individual players. For all of these tasks subjects had no time constraints for making responses. After they completed the whole experiment, all subjects were asked whether they had any doubts that the other Cyberball players were real, and all confirmed that they thought they were. Subjects were also asked to guess whether they had received OXT or PLC treatment but their responses showed that they were unable to do so better than chance.2) and 2-factor ANOVA for ratings on Q2 and Q4. Correlations between ICS scores and behavior in the two treatment groups were performed using the Pearson test and differences in correlations between the groups were analyzed using Fisher’s Z. In an initial exploratory analysis we found no evidence for significant menstrual cycle effects on any measures taken and so this was not included as a factor analyses.In all cases statistical analyses were performed using SPSS 18.0 software . Differences between questionnaire scores in the OXT and PLC groups were analyzed using independent t-test. No corrections were made for multiple tests. Treatment effects were analyzed primarily using 3-factor ANOVAs  and where significant interactions occurred post-hoc analyses were carried out using a Bonferroni correction in SPSS. Treatment differences in responses to Q1 and Q3 by Chi-square test .Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


COMP), in close partnership with the Canadian Partnership for Quality Radiotherapy (CPQR) has developed a series of Technical Quality Control (TQC) guidelines for radiation treatment equipment. These guidelines outline the performance objectives that equipment should meet in order to ensure an acceptable level of radiation treatment quality. The TQC guidelines have been rigorously reviewed and field tested in a variety of Canadian radiation treatment facilities. The development process enables rapid review and update to keep the guidelines current with changes in technology. This article contains detailed performance objectives and safety criteria for low‐dose‐rate (LDR) permanent seed brachytherapy.The Canadian Organization of Medical Physicists ( Financial and strategic backing is provided by the federal government through the Canadian Partnership Against Cancer (CPAC), a national resource for advancing cancer prevention and treatment. The mandate of the CPQR is to support the universal availability of high quality and safe radiotherapy for all Canadians through system performance improvement and the development of consensus‐based guidelines and indicators to aid in radiation treatment program development and evaluation.low‐dose‐rate Permanent Seed Brachytherapy. Please refer to the overarching document Technical Quality Control Guidelines for Canadian Radiation Treatment CentresThis document contains detailed performance objectives and safety criteria for The development of the individual TQC guidelines, this one included, is spearheaded by expert practitioners and involves broad stakeholder input from the medical physics and radiation oncology community.2There are several other publications dealing with the performance, specifications, and quality control of low‐dose‐rate (LDR) permanent seed brachytherapy.125I, 103Pd, 131Cs, and, 192Ir. 192Ir is used for HDR brachytherapy. Quality control procedures are similar to those of other HDR procedures and can be found in the CPQR Technical Quality Control (TQC) guideline Brachytherapy Remote Afterloaders.131Cs, 125I, and, 103Pd are used for permanent implants and are the radionuclides of interest here.Brachytherapy is a procedure in which sealed radionuclide sources are placed in close proximity to, or inside, the tumor. For example, brachytherapy modalities for prostate cancer presently used in Canada include ultrasound guided transperineal interstitial permanent prostate brachytherapy (TIPPB) and high dose rate (HDR) brachytherapy. In prostate brachytherapy, four radionuclides are currently used: Transperineal interstitial permanent prostate brachytherapy was first proposed by Holm and colleagues.Transperineal interstitial permanent prostate brachytherapy has become a very popular treatment alternative for low risk prostate cancer patients due to the pioneering work of the Seattle group.For intermediate and high‐risk patients (PSA > 10 and/or Gleason score > 6 and/or stage > T2c), HDR brachytherapy is more commonly used, mainly as a boost strategy, producing excellent PSA control and negative biopsy results in patients with intermediate‐ and high‐risk prostate cancer.Recently, permanent seed implants have been proposed for breast cancer by Dr. Jean‐Philippe Pignol from Sunnybrook hospital in Toronto.A brachytherapy program, whether it involves permanent seed implants or HDR temporary implants, requires the competencies of multiple health professionals to be efficient and productive. From the physicist's point of view, there is a convergence of many technologies into a single procedure. American Association of Physicists in Medicine (AAPM) Task Groups 43U1,Furthermore, prostate brachytherapy is based first on the use of ultrasound as a real‐time guidance device. The AAPM has published a report from Task Group 128 dedicated to prostate brachytherapy ultrasounds quality assurance tasks.Conventional x ray films or fluoroscopy can also be used to visualize the seeds or the catheters after they have been implanted. Such verification can be made in the operating room or the brachytherapy suite. Finally, CT and MRI scans are used for TIPPB post‐plan quality assurance. For all prostate brachytherapy programs, a calibrated well chamber and hand‐held radiation monitor must be available at all times. Personal whole‐body dosimeters should be worn by all staff participating in the implant procedure. Other personal dosimeters, such as ring and wrist dosimeters, can also be used.http://rpc.mdanderson.org/RPC/), along with a description of the AAPM prerequisites. The medical physicist should regularly carry out a thorough search of the scientific literature for any new assessment of a seed's dosimetric parameters and its potential impact on clinical dosimetry. While the literature does point out the limitations to TG43 with regards to procedures described in this document , no commercial solution is available to the clinical users and therefore are not covered herein. The interested readers should refer to the Task Group 186 report for more details.The dosimetric description of the sources should be made according to AAPM Task Group 43 recommendation.http://rpc.mdanderson.org/RPC/). Before using a seed model clinically for the first time, a well chamber should be sent to an accredited dosimetry calibration laboratory (ADCL) for calibration. Alternatively, a single seed can be sent to an ADCL for measurement of its air‐kerma strength, and this value used to obtain a calibration factor for the well chamber. Compliance with applicable radiation safety codes must be ensured for each radionuclide, source type, and activity range to be used.Any new or upgraded TPS and/or new seed model should be validated against known test cases and also by hand calculation. Potentially helpful in this regard are the test cases used by the Radiological Physics Center (RPC) at the MD Anderson Cancer Center for credentialing participants in clinical trials research having an LDR brachytherapy component. See the “Credentialing” section of the IROC website  or once at the start of the day, depending of the nature of the test.Quality Assurance Guidelines for Canadian Radiation Treatment ProgramsRadiation safety related tests have not been included in Tables The authors declare no conflict of interest.


Although the majority of protein synthesis happens in the cytosol, an additional translation apparatus is required to translate the 13 mitochondrial DNA‐encoded proteins important for oxidative phosphorylation. Most ARS genes in these cellular compartments are distinct, but two genes are common, encoding aminoacyl‐tRNA synthetases of glycine (GARS) and lysine (KARS) in both mitochondria and the cytosol. Mutations in the majority of the 37 nuclear‐encoded human ARS genes have been linked to a variety of recessive and dominant tissue‐specific disorders. Current data indicate that impaired enzyme function could explain the pathogenicity, however not all pathogenic ARSs mutations result in deficient catalytic function; thus, the consequences of mutations may arise from other molecular mechanisms. The peripheral nerves are frequently affected, as illustrated by the high number of mutations in cytosolic and bifunctional tRNA synthetases causing Charcot–Marie–Tooth disease (CMT). Here we provide insights on the pathomechanisms of CMT‐causing tRNA synthetases with specific focus on the two bifunctional tRNA synthetases .Aminoacyl‐ ARSAL, Autosomal Recessive Spastic Ataxia with LeukoencephalopathyARSs, Aminoacyl‐tRNA synthetasesCMT, Charcot–Marie–Tooth diseaseGARS, glycyl‐ARSMLASA, mitochondrial myopathy, lactic acidosis and sideroblastic anaemiaMSC, multi‐tRNA synthetase complexNMJs, neuromuscular junctionsVEGF, vascular endothelial growth factorAminoacyl‐tRNA synthetase proteins (ARS) are a family of nuclear‐encoded enzymes that ensure correct translation of the genetic code by conjugating each of the 20 amino acids to their cognate tRNA molecule DARS2 mutations EARS2 mutations AARS2 gene result in two different phenotypes: late onset ovarian failure and leukodystrophy and infantile mitochondrial cardiomyopathy MARS2 mutations have been previously linked to Autosomal Recessive Spastic Ataxia with Leukoencephalopathy (ARSAL) CARS2FARS2, PARS2TARS2, VARS2RARS2WARS2NARS2, PARS2), pontocerebellar hypoplasia (RARS2), visual impairment (FARS2) psychomotor delay (TARS2) and microcephaly (VARS2). Other ARS2 diseases show characteristic tissue distribution, isolated sensorineural hearing loss , which is cleaved upon entry to the mitochondria AARSHARSYARSGARSWARSAARS, QARSAARS, QARSHARS, KARSIARS, KARS, QARS, YARSIARS, MARS, YARSMARSWhile autosomal dominant pathogenic variants of the cytosolic ARSs were originally reported in peripheral neuropathies, newly emerging data show a spectrum of recessive disorders. Autosomal dominant neuropathies have been associated with mutations in AARS, GARS, WARS, YARS and HARS) have been reported to cause dominant inherited CMT, with the number expected to increase, and remarkably, no other dominantly inherited disease has been linked with mutations  was the first human disorder to be linked to ARSs mutations. CMT is the most common inherited neurological disease in European populations, with an estimated prevalence of around 1–4 per 10 000 individuals Besides the fact that new mutations are continuously discovered, neither the cause of the selective vulnerability, nor the molecular mechanisms leading to the disease, are well understood. Currently, there are no disease modifying therapies for CMT and clinical care focuses on managing symptoms with physical therapy and orthopaedic surgery. The similarity of clinical presentation resulting from dominant inherited ARS mutations implies a shared mechanism of disease, though no mechanism so far has been proven. The major mechanisms proposed consist of: reduced aminoacylation activity, altered dimerisation or localisation, gain‐of‐function pathogenic interactions and loss of noncanonical function Fig. . We examin vitro using recombinant human protein YARS p.Glu196Lys variant  may be involved in conjunction with the catalytic deficit to cause peripheral nerve‐specific presentation. The question about aminoacylation deficiency and disease causality is controversial and still open in the literature, although we think that it may be causative at least in some mutations. However, other pathological mechanisms may have an additive effect and for certain mutations aminoacylation is not altered and different factors may explain the disease phenotype.et al. All CMT‐associated ARS enzymes  catalytically function as dimers, and disruption to the dimer functionality has been suggested as a mechanism of pathogenicity in ARS‐related CMT. Clustering of mutations of GARS has been reported around the homodimer interface, and mutations affecting the dimer interface have been shown to cause subtle conformational alterations to mutant wild‐type dimers GARS and YARS variants have been shown to have binding affinities equivalent to, or exceeding that of, the wild‐type protein per se is not a common mechanism. Animal studies of mutant and wild‐type YARS and GARS have shown equivalent expression of the protein in the cell body In vitro enzymatic assays have already shown that although aminoacylation is often affected in mutant homodimers, it is not a common feature of all CMT‐associated mutations and therefore, considering the dominant mode of inheritance, it should be examined whether the aminoacylation activity of tRNA heterodimers may have a role. A study, looking at CMT‐associated mutations in zebrafish showed that overexpression of the homologue of the nondimerising p.Thr130Lys mutation reduced NMJ toxicity of the CMT‐associated p.Gly526Arg mutation when alongside normal expression of wild‐type gars, suggesting that dimerisation of the mutant protein with the wild‐type is necessary for pathogenicity YARS variants and showed that, while other properties such as conformational alteration of dimer structure were not common, exposure of an internal site on the dimers was, and this facilitates increased binding to TRIM28 Addressing the first possibility, several in vitro and in vivo have shown mixed results in alterations resulting from CMT‐causing mutations. In the case of YARS, a clustering of expression can be observed around neuronal projections, which was abolished in N2a cells transfected with CMT‐causing YARS mutations  HARS mutation, p.Arg137G Caenorhabditis elegans has shown a normal pattern of axonal expression alongside morphological abnormalities and three different YARS variants  modelled in Drosophila showed no change in axonal localisation. Also the distribution of the mutant Gars in a CMT2D mouse model indicated unaltered localisation in the sciatic nerve fibres Alteration to the cellular distribution of cytosolic enzymes presents another pathogenic mechanism. If mutations disrupt the distribution of ARS proteins within the cell, and cause a deficit of protein activity in the axons of peripheral neurons, which are often much longer than axons of the central nervous system, this may plausibly explain why mutations cause length‐dependent pathology in the long axons. However, the few studies that have investigated distribution both C. elegans.The lack of clear mechanistic evidence supporting deficits in aminoacylation  has led the suggestion that cytosolic ARS disease may relate to entirely different ‘noncanonical’ ARS functions. This could include the loss of a noncanonical physiological ARS function, or alternatively can be a gain of pathological function. During the evolutionary process, cytosolic ARS proteins, or complexes formed from them, have accrued additional functions to their core ‘canonical’ role in aminoacylating tRNA molecules with roles as diverse as mRNA splicing GARS mutations have been identified in patients with axonal peripheral neuropathy  KARS have been so far associated with various phenotypes: autosomal recessive CMT KARS.Reported mutations in bifunctional enzymes, GARS and KARS show either recessive or dominant inheritance, with strikingly different tissue specific clinical manifestations. Dominant Despite of many efforts it is not clear how variants of bifunctional ARSs impact the mitochondrial function and whether or not the mitochondrial impairment is solely recessive, similar to mutations in other nuclear‐encoded genes affecting mitochondrial translation, while neuropathy is caused by the defect of another, probably cytosolic, function.KARS mutations developed CMT, recessive GARS or KARS mutations are not associated with peripheral neuropathy, rather with prominent heart and skeletal muscle dysfunction. As the majority of patients with recessive GARS and KARS mutations are children, it is possible that neuropathy will develop in a later stage; however, no reliable clinical data support this hypothesis. There is only limited clinical information available on parents of children with recessive disease, who carry heterozygous GARS or KARS mutations. In one case, the father presented with mild neuropathy detected on electrophysiology, but the mother showed no clinical or electrophysiological alterations With the exceptions of one patient with recessive GARS mutations introduce abnormal conformational changes leading to aberrant protein interactions. Supporting a toxic gain‐of‐function, recent findings in mice carrying pathogenic Gars mutations show that the mutant Gars protein acquires a neomorphic‐binding activity that directly antagonises an essential signalling pathway for motor neuron survival Among various ARSs, the secretion of wild‐type KARS  and GARS  to extracellular space via exosomes has been confirmed by several studies Several genetic forms of CMT are caused by mutations in proteins affecting mitochondrial function such as mitofusin 2 (MFN2), ganglioside‐induced differentiation‐associated‐protein 1 (GDAP1), heat shock protein beta 8 (HSPB8), and heat shock protein beta 1 (HSPB1) GARS mutations in Drosophila, which leads to progressive defects of dendritic morphology due to altered mitochondrial translation GARS mutations GARS mutations and a variety of mechanisms may underlie the mitochondrial dysfunction, including deficits in ATP production, failure of axonal transport, or changes in intracellular calcium dynamics. Keeping in line with this, antioxidants including ascorbic acid and forms of glutathione were reduced in mutant GarsNmf249/+ mice spinal cord and sciatic nerve, suggesting changes in oxidative pathways GARS‐related neuropathy suggest that mitochondrial dysfunction involving very specific pathways is essential for the motor nerve dysfunction (unpublished data).Investigation of mitochondrial function of bifunctional ARS has been reported in several studies. A mitochondrial isoform of KARS have been reported to interact with SOD1 in the mitochondria of the nervous system Drosophila where ubiquitous mutant gars was expressed As neurons and muscle fibres are highly metabolically active, it is rational to hypothesise that the neuromuscular junctions (NMJs) are affected by even minor mitochondrial dysfunction. Recent data showed synaptic maturation abnormalities with specific, progressive NMJ degeneration in in vitro aminoacylation assay and yeast complementation studies showed that some CMT mutations do not affect the enzymatic activity, indicating that loss of aminoacylation activity alone is not required to cause peripheral neuropathy Nmf249/+ and GarsC201R/+ mice), mutations in Gars do not reduce tRNAGly aminoacylation activity Drosophila model using a new method based on noncanonical amino acid tagging, which allows to cell‐type‐specifically monitor translation in vivoThe housekeeping function of the ARSs is to catalyse the aminoacylation of tRNA with their cognate amino acid, which is the first step of protein synthesis. Data from It is well documented that several cytoplasmic ARSs acquired unique signal mediators during evolution, which facilitate numerous noncanonical biological processes GARS mutations (unpublished data).The cytosolic form of KARS is part of the multi‐tRNA synthetase complex (MSC) and involved in the housekeeping role; however, N‐terminal cleavage of KARS by caspase‐8 and an interaction with syntenin through its C‐terminal end leads to dissociation from the MSC complex and translocation to the plasma membrane where it associates with and stabilises a 67‐kDa laminin receptor (p67LR) GarsNmf249/+) attempted to identify changes in metabolite abundance that may be indicative of the pathophysiology Recently, new investigations using a metabolomics analysis in a mouse model of CMT2D,  and in vitro  model systems have been developed to study ARSs in different tissues, which will hopefully provide further insights into the disease mechanism. Various noncanonical functions of ARSs have become increasingly interesting, and by being secreted could have widespread effects or could act as potential biomarkers. To date, there is no good biomarker available to study the progression of neuropathy in these slowly progressive diseases. Understanding why peripheral nerves are predominantly affected will open potential therapeutic targets for a larger group of CMT patients; however, further research is still needed.In this review, we summarised the research on the pathomechanisms of ARS mutations causing peripheral neuropathy; however, what remains particularly unclear is the cause of the high degree of tissue specificity. Some excellent


An evaluation of two anthropomorphic breast phantoms, which have been designed for quality assurance and dose verification of radiotherapy treatment of breast cancer patients, is presented. These phantoms are identical in terms of their dimensions and shape and composed of several layers of either Plastic Water™ or tissue‐equivalent material. Both water‐and tissue‐equivalent phantoms include lung‐ and rib‐equivalent components. The phantoms simulate large, medium and small breasts. The value of the phantoms as breast treatment quality assurance tools was assessed by dose measurements with ionization chamber and thermoluminescence dosimeters (TLD) at different points inside the phantom. Measurements were made by irradiating the phantoms under conditions representing the different treatment techniques found by the Radiological Physics Center (RPC) during its dosimetry quality audits. Most irradiations were performed with the water‐equivalent breast phantom. One experiment was performed under consistent irradiation conditions to compare the tissue‐equivalent phantom with the water‐equivalent phantom. Measurements were compared with the dose estimated by the RPC's manual calculations used to check clinical charts of patients entered in a National Surgical Adjuvant Breast and Bowel Project (NSABP) protocol. Measurements were also compared with isodose distributions generated by a commercial radiation treatment planning (RTP) system. In the homogeneous three‐dimensional (3‐D) phantom, fairly good agreement (within 5%) was observed at the NSABP dose prescription point between measurements and 2‐D dose estimation by manual calculations. At the same dose prescription point, but located in the heterogeneous 3‐D phantom, agreement between measurements and a 3‐D RTP system was within about 3%. Manual calculation resulted in overestimation of up to 6%. The general agreement between the TLD measurements and the 2‐D RTP values was within 3% at various off‐axis points, with the exception of a few points far off‐axis, near the high‐dose gradient region at the surface of the phantom.PACS number(s): 87.53Dq, 87.66Xa, 87.53Xd Radiotherapy of breast cancer is difficult because of the complex geometry of the target volume, which includes the breast, the adjacent lymph nodes, and the presence of critical organs such as the lungs and heart.–Although several anthropomorphic phantoms have been described in the literature,The Radiological Physics Center (RPC) provides quality assurance (QA) support to the cooperative clinical trials sponsored by the National Cancer Institute (NCI). The RPC's QA program for breast radiotherapy protocols includes verification of the dose delivered to the National Surgical Adjuvant Breast and Bowel Project (NSABP) prescription point. Therefore, these phantoms will enable the RPC to verify particular treatment plans and the institution's simulation, dosimetry, and treatment processes.The phantoms were evaluated under different planning and treatment conditions to validate their usefulness as a QA tool. Comparisons between the calculated dose to the protocol prescription point and dose measurements with and without lung and bone tissues were made. A comparison with an isodose distribution from a treatment‐planning system incorporating inhomogeneity corrections is also presented.1/3 the height of the breast's mediolateral plane projection, measured at the breast's height along the baseline's bisector : Inverse square correction due to the difference between the SSD at central axis and the distance to the breast surface at the point of entrance of a ray that passes through the NSABP prescription point for the SSD setup; for the SAD setup, ISQ (SAD) is the correction due to the difference between the SAD distance and the NSABP projected position on the central axisF: Mayneord factor that converts the percentage depth dose (PDD) at nominal SSD0 to another SSD1dmax : Depth of maximum doseTMR: Tissue maximum ratio for the effective field size at the depth of the NSABP prescription point for the SAD setupDD: Fractional depth dose for the effective field size at the depth of the NSABP point for theSSD setupWF : Wedge factor; function of field size and depthTF is the tray factorOAFwedge: A correction due to the off‐axis position of the NSABP prescription point with respect to the central axis and the wedge axis; a function of field size and depthThe parameters used in the equations above are:A water‐equivalent phantom Fig.  was desiTLD, and GAF‐Chromic film. The material used for the tissue‐equivalent phantom Fig. , also buThe location of the NSABP prescription point for each phantom size simulated depends, not only on how many slabs are used (breast size), but also on the position of the baseline used in the treatment plan simulation and hand calculations. The location of the NSABP prescription point for the medium and small phantom sizes was obtained by changing the position of the baseline used for the large‐size phantoms. In this report, point dose measurements in the three phantom sizes were performed at the corresponding NSABP reference points, for each phantom size.Computed tomography (CT) images of the inhomogeneous water‐equivalent phantom, including the ribs and lung inserts Fig. , were ob[(μ/ρ)muscle/[(μ/ρ)water=0.99).Breast treatment deliveries at different institutions monitored by the RPC cover a large range of techniques. Hence, the breast phantom was irradiated with several common tangential breast‐treatment techniques: parallel opposed offset fields, and co‐planar oblique fields with and without a wedge. The offset fields were defined either by asymmetric jaws or by half‐beam block devices. Some irradiation conditions investigated in this study might not have resulted in a clinically acceptable dose distribution, due to field combinations and/or wedge angles chosen for a symmetrically shaped breast phantom. However, they were considered appropriate for the purpose of evaluating the RPC manual calculation and radiation treatment planning (RTP) systems. Most irradiations were performed with the water‐equivalent breast phantom. One experiment was performed under consistent irradiation conditions to compare the tissue‐equivalent phantom with the water‐equivalent phantom. In detail, dose measurements at the NSABP point were made to compare the water‐equivalent phantom with the tissue‐equivalent phantom. The difference in dose between the phantoms was within 1% of each other as theoretically expected . However, only the results from Cobalt‐60 and one of the 6 MV photon beams will be presented because the results were similar for the 6 MV photon beams.To reduce the amount of effort, several irradiation field combinations were evaluated and compared using an ionization chamber rather than using a large number of TLD measurements. The photon beams used were Cobalt‐60, and the 6 MV photon beams from several linear accelerators: Clinac 2100, Clinac The RTP systems used in this study were Target II  and RenderPlan . Both RTP systems used patient data, treatment‐machine data, and setup information such as the position of the beams and beam modifiers with respect to the patient.The midline CT scan contour of the homogeneous water‐equivalent phantom was used for 2‐D dose calculations, comparing only the dose at the NSABP prescription point. Target II RTP system performed conventional 2‐D dose calculations; the CT images of the phantom were used by the Target II RTP system to generate isodose curves for the phantom treatment with and without inhomogeneity corrections  to simulate the 3‐D dose distribution inside a patient.30 cm×30 cm×30−cm solid Plastic Water™ phantom. A Farmer‐type ionization chamber was used for measuring beam outputs. Tello et al.(3 mm×3 mm×1 mm) were used for relative measurements. The TLDs were irradiated with their largest surface area parallel to the beam axis. Two TLD chips were placed inside a water‐equivalent plug with the shape of the ionization chamber. The plug was then placed at the NSABP prescription point to obtain the TLD calibration.The output calibration of the treatment machines was performed using the AAPM TG‐21 protocolTables The worst agreement up to 7% between ion chamber measurements and hand calculations was seen for an oblique 45°‐wedged 6 MV beam. The agreement between ion chamber measurements and hand calculations was within 5%, when the total dose to the NSABP prescription point contributed from both medial and lateral fields was considered.Treatment plans were generated with and without heterogeneity correction using a commercial RTP system (Render Plan). The phantoms were irradiated under several different conditions, including SSD and SAD setup, with and without the lung/rib material. Several treatment techniques were also used, including oblique field and asymmetric jaws. In Table ±3%, whereas the manual calculation would result in an overestimation of the dose up to 6%. The NSABP dose prescription point is located 1 cm from the apex of the lung. The amount of lung included in the treatment ranged from 1.3 to 2.2 cm of the breast apical height.The effect of the presence of the lung and ribs in the photon field appears to reduce the dose contribution to the NSABP dose prescription point by approximately 1 to 2%. At the NSABP dose prescription point, the agreement between the measurements and 3‐D RTP calculations was within The water‐equivalent phantom was irradiated under identical conditions with and without lung/rib materials. The latter condition was simulated by replacing the bottom two slabs (lung/rib section) by two water‐equivalent slabs of the same dimensions see Fig. .Figs. The isodose distributions in the two figures differ drastically in the region below the NSABP point location. Specifically, Fig. The numbers inside the boxes in Figs. As seen in Figs. The colored curves in each graph show the results for a midline CT slice, as shown in Fig. 10 cm×10 cm field size on a Cobalt‐60 beam. Comparison with BJR #17 tables±2.5%; 2) effective measurement position of the chip was within 1.5 mm ; and 3) partial chip shadowing (chip was staggered as a function of depth with maximum overlap of less than 1/5 of the chip's width). The uncertainty in ionization chamber calibration plus the ionization chamber measurements,The TLDs were placed with their 1‐mm thickness orthogonal to the direction of the photon beam. The accuracy of the TLD chips in that direction was assessed by measuring the percentage depth dose along the central axis for a The RPC continues developing advanced QA techniques and tools to monitor the quality of treatment of patients entered into NCI clinical trials that use technologically advanced treatment planning and dose‐delivery methods. In this regard, the RPC has developed several anthropomorphic phantoms, including the anthropomorphic breast phantoms presented in this paper. Before these phantoms can be used in the field as QA tools, they need to go through rigorous evaluation. This paper summarizes some of the measurements performed to accept the breast phantoms as reliable QA devices.,As mentioned earlier, some part of the discrepancies between ion chamber measurements and hand calculations could be due to an inaccurate estimation of the photon scatter during the hand calculations. In general, the 2‐D hand calculation tends to overestimate the full‐size breast volume because of the missing phantom material in the third dimension. As the breast size is reduced, therefore, the agreement between hand calculations and measurements for open Cobalt‐60 beams tends to improve. In addition, the backscatter for a Cobalt‐60 beam is larger than that for a 6‐MV photon beam,As 3‐D treatment planning is routinely performed for the majority of radiation treatments including breast treatment, the verification of 3‐D dose distributions could be an essential part of the QA program. In general, it is very difficult to accurately measure a full 3‐D dose distribution, in spite of recent advances in 3‐D dosimeters such as gel dosimetry. Therefore, as a practical alternative, researchers have developed anthropomorphic phantoms in conjunction with 2‐D dosimeters  or point dosimeters  to measure the doses at reference points and a particular plane inside the phantoms. Although this approach has been applied to many treatment sites, little has been reported for breast, especially for breast phantoms that include the lung and other inhomogeneities such as ribs. Accurate dose assessment for breast treatments cannot be achieved without taking into account these inhomogeneous anatomic structures, which are presented in the radiation field. As intensity‐modulated radiation therapy (IMRT) for breast becomes feasible, an accurate dose assessment and verification are essential for successful treatments. Certainly, the phantoms developed in this study could serve as simple and versatile QA tools for the IMRT  of breasts. In particular, they might be used as a credentialing tool during possible multi‐institutional clinical trials for breast 3‐D CRT or IMRT treatments in the future.Versatile anthropomorphic breast phantoms have been developed to facilitate the assessment of dosimetry in the breast treatment process. These phantoms are designed to simulate treatments with and without inhomogeneities such as lungs and ribs. These phantoms may serve as a valuable tool for quality assurance of breast treatments by providing a quick assessment of the accuracy of the dose delivery to the breast. At the NSABP dose prescription point located in a homogeneous 3D phantom, a fairly good agreement within 5% was observed between measurements in a 3‐D homogeneous phantom and 2‐D dose estimation by manual calculations. At the same dose prescription point but located in a heterogeneous 3‐D phantom, the agreement between measurements and a 3‐D RTP system's calculated values was within about 3%, whereas the manual calculation resulted in an overestimation of the dose up to 6%. The general agreement between the TLD measurements and the 2‐D RTP values was within 3% at various off‐axis points, with the exception of few points far off‐axis, near the high‐dose gradient region at the surface of the phantom.The anthropomorphic phantoms described in this work were originally designed, developed, and commissioned by Victor M. Tello, MS, while he was at the RPC. We acknowledge the engineers at CIRS Inc, who built the water‐equivalent phantom, the breast‐tissue‐ and bone‐equivalent materials. We would also like to recognize the help and expertise of the following staff of the Department of Radiation Oncology at M. D. Anderson Cancer Center: Eric Strom, MD, Becky Zikes, BS, CMD, Kim Hale, RT(R)(T), Agnes Potovsny, David Lege, RT, CNMT, Peter Balter, PhD., Nathan Wells, MS, Huy Duong, BS, and Mr. Ferrell Munson. We greatly appreciate the secretarial support of Mr. James DeVoge.This investigation was supported by PHS grant CA 10953 awarded by the National Cancer Institute, DHHS.