It's past your bedtime, but does it matter anymore? How longitudinal changes in bedtime rules relate to adolescents' sleep.

This study investigated how changing or maintaining parent-set bedtimes over time relates to adolescents' sleep timing, latency, and duration. Adolescents (n = 2509; Mage = 12.6 [0.5] years; 47% m) self-reported their sleep patterns, and whether they had parent-set bedtimes on two separate occasions in 2019 (T1; 12.6 years) and 2020 (T2; 13.7 years). We identified four groups based on parent-set bedtimes: (1) bedtime rules at both T1 and T2 (46%, n = 1155), (2) no bedtime rules at T1 nor T2 (26%, n = 656), (3) bedtime rules at T1 but not T2 (19%, n = 472), (4) no bedtime rules at T1 but a parent-set bedtime at T2 (9%, n = 226). As expected, the entire sample showed that bedtimes generally became later and sleep duration shorter across adolescence, but the change differed among the groups. Adolescents whose parents introduced bedtime rules at T2 reported earlier bedtimes and longer sleep duration (~20 min) compared with adolescents with no bedtime rules at T2. Importantly, they no longer differed from adolescents who consistently had bedtimes across T1 and T2. There was no significant interaction for sleep latency, which declined at a similar rate for all groups. These results are the first to suggest that maintaining or re-introducing a parent-set bedtime may be possible and beneficial for adolescents' sleep.

Playing for more than winning: Exploring sports participation, physical activity, and belongingness and their relationship with patterns of adolescent substance use and mental health.

BACKGROUND: Promoting adolescent sports participation and physical activity may be effective low-barrier prevention strategies for co-occurring adolescent substance use (SU) and mental health symptoms (MH). The objectives of this study were to: 1) explore associations between profiles of SU/MH and sports participation; and 2) determine whether physical activity and belongingness account for these associations. METHODS: Data came from a representative sample of 11,994 grade 9-12 Ontarian students (ages ~14-18) previously grouped into five SU/MH profiles based on patterns of use and symptoms. A series of multinomial logistic regressions, adjusted for socio-demographics and school clustering, were used to predict the risks of students belonging to SU/MH profiles based on: 1) school sports participation (>=weekly), 2) sports and physical activity (>=60minutes; 0-7 days), and 3) sports, physical activity, and school belongingness. RESULTS: Greater school sports participation, physical activity, and belongingness were each associated with reduced risks of belonging to most profiles with elevations in SU and/or MH symptoms relative to the low SU/MH profile (Relative Risk Ratios: sports=0.62-0.87, physical activity=0.78-0.98, belonging=0.75-0.83). Frequency of physical activity accounted for ~32-60% of the associations between sports and SU/MH profiles, while school belongingness accounted for the remaining associations. Physical activity and belongingness remained independently associated with SU/MH profiles. CONCLUSIONS: Findings suggest possible indirect associations between school sports participation and SU/MH profiles through physical activity and school belongingness, which may be promising prevention targets that have independent associations over and above sports. School sports participation may be one of a number of ways to achieve these goals.

Can regulatory T cells improve outcomes of sensitised patients after HLA-Ab incompatible renal transplantation: study protocol for the Phase IIa GAMECHANgER-1 trial.

BACKGROUND: Kidney transplantation is the gold-standard treatment for patients with kidney failure. However, one-third of patients awaiting a kidney transplant are highly sensitized to human leukocyte antigens (HLA), resulting in an increased waiting time for a suitable kidney, more acute and chronic rejection, and a shorter graft survival compared to non-highly sensitised patients. Current standard immunosuppression protocols do not adequately suppress memory responses, and so alternative strategies are needed. Autologous polyclonally expanded regulatory T cells (Tregs) have been demonstrated to be safe in transplant settings and could be a potential alternative to modulate memory immune alloresponses. METHODS: The aim of this trial is to determine whether adoptive transfer of autologous Tregs into HLA sensitised patients can suppress memory T and B cell responses against specific HLA antigens. This is a two-part, multi-centre, prospective clinical trial, comprising an observational phase (Part 1) aiming to identify patients with unregulated cellular memory responses to HLA (Pure HLA Proteins) followed by an interventional phase (Part 2). The first 9 patients identified as being eligible in Part 1 will undergo baseline immune monitoring for 2 months to inform statistical analysis of the primary endpoint. Part 2 is an adaptive, open labelled trial based on Simon's two-stage design, with 21 patients receiving Good Manufacturing Practice (GMP)-grade polyclonally expanded Tregs to a dose of 5-10 × 106 cells/kg body weight. The primary EP is suppression of in vitro memory responses for 2 months post-infusion. 12 patients will receive treatment in stage 1 of Part 2, and 9 patients will receive treatment in stage 2 of Part 2 if ≥ 50% patients pass the primary EP in stage 1. DISCUSSION: This is a prospective study aiming to identify patients with unregulated cellular memory responses to Pure HLA Proteins and determine baseline variation in these patterns of response. Part 2 will be an adaptive phase IIa clinical trial with 21 patients receiving a single infusion of GMP-grade polyclonally expanded Tregs in two stages. It remains to be demonstrated that modulating memory alloresponses clinically using Treg therapy is achievable. TRIAL REGISTRATION: EudraCT Number: 2021-001,664-23. REC Number: 21/SC/0253. Trial registration number ISRCTN14582152.

Spontaneous closure of a traumatic acquired Gerbode defect in a dog.

A one-year-old female English Springer Spaniel with no previous history of cardiac disease presented to the Queen's Veterinary School Hospital following a blunt traumatic incident with an acquired, direct Gerbode defect and associated third-degree atrioventricular block. Two months after the initial incident, follow-up echocardiography showed a nearly closed Gerbode defect with just trivial residual flow. A 24-h Holter monitor indicated second-degree atrioventricular block with occasional junctional tachycardia. A reassessment 22 months later confirmed spontaneous closure of the previously acquired traumatic Gerbode defect, with 2:1 second-degree atrioventricular block. The dog remained clinically asymptomatic, and free of treatment. To our knowledge, this is the first reported case of spontaneous closure of a previously acquired traumatic Gerbode defect in a dog.

Unilateral external jugular vein aneurysm in a dog.

An 11-month-old Staffordshire Bull Terrier was referred with a two-month history of fluctuating unilateral jugular groove swelling, which appeared to enlarge after exercise. There was no history of trauma. Multimodal imaging findings (using transdermal and transesophageal ultrasound and dual phase computed tomography angiography) were consistent with large, saccular, left jugular vein aneurysm, running parallel to the left carotid artery. There did not appear to be any arteriovenous communication present. There were no cardiac abnormalities found on echocardiography. Following surgical excision, histopathological analysis supported the clinical suspicion of a congenital external jugular venous aneurysm.

A data-centric approach to generative modelling for 3D-printed steel.

The emergence of additive manufacture (AM) for metallic material enables components of near arbitrary complexity to be produced. This has potential to disrupt traditional engineering approaches. However, metallic AM components exhibit greater levels of variation in their geometric and mechanical properties compared to standard components, which is not yet well understood. This uncertainty poses a fundamental barrier to potential users of the material, since extensive post-manufacture testing is currently required to ensure safety standards are met. Taking an interdisciplinary approach that combines probabilistic mechanics and uncertainty quantification, we demonstrate that intrinsic variation in AM steel can be well described by a generative statistical model that enables the quality of a design to be predicted before manufacture. Specifically, the geometric variation in the material can be described by an anisotropic spatial random field with oscillatory covariance structure, and the mechanical behaviour by a stochastic anisotropic elasto-plastic material model. The fitted generative model is validated on a held-out experimental dataset and our results underscore the need to combine both statistical and physics-based modelling in the characterization of new AM steel products.

Genetic epidemiology of malignant hyperthermia in the UK.

BACKGROUND: Gaps in our understanding of genetic susceptibility to malignant hyperthermia (MH) limit the application and interpretation of genetic diagnosis of the condition. Our aim was to define the prevalence and role of variants in the three genes implicated in MH susceptibility in the largest comprehensively phenotyped MH cohort worldwide. METHODS: We initially included one individual from each positive family tested in the UK MH Unit since 1971 to detect variants in RYR1, CACNA1S, or STAC3. Screening for genetic variants has been ongoing since 1991 and has involved a range of techniques, most recently next generation sequencing. We assessed the pathogenicity of variants using standard guidelines, including family segregation studies. The prevalence of recurrent variants of unknown significance was compared with the prevalence reported in a large database of sequence variants in low-risk populations. RESULTS: We have confirmed MH susceptibility in 795 independent families, for 722 of which we have a DNA sample. Potentially pathogenic variants were found in 555 families, with 25 RYR1 and one CACNA1S variants previously unclassified recurrent variants significantly over-represented (P<1×10-7) in our cohort compared with the Exome Aggregation Consortium database. There was genotype-phenotype discordance in 86 of 328 families suitable for segregation analysis. We estimate non-RYR1/CACNA1S/STAC3 susceptibility occurs in 14-23% of MH families. CONCLUSIONS: Our data provide current estimates of the role of variants in RYR1, CACNA1S, and STAC3 in susceptibility to MH in a predominantly white European population.

Risk stratification with longitudinal neutrophil to lymphocyte ratio assessment after left ventricular assist device implantation.

INTRODUCTION: Inflammatory processes are well-characterized risk factors in cardiovascular disease including advanced heart failure. Previous studies have utilized individual white cell subtypes in risk analysis, and a recent study has focused on the efficacy of the neutrophil-to-lymphocyte ratio in evaluating negative outcomes following left ventricular assist device implantation. To investigate the interaction between the left ventricular assist device and white cell counts, we assessed longitudinal changes in neutrophil-to-lymphocyte ratio following left ventricular assist device implantation. METHODS: This retrospective study included 100 patients who underwent left ventricular assist device implantation between 2012 and 2013. The neutrophil-to-lymphocyte ratio was calculated prior to left ventricular assist device implantation, daily for the first 30 postoperative days, and at the first two postoperative outpatient visits. Preoperative demographic and clinical data were collected for all patients. RESULTS: The mean neutrophil-to-lymphocyte ratio immediately before left ventricular assist device implantation was 5.2 ± 4.9. After surgery, the neutrophil-to-lymphocyte ratio decreased asymptotically, from a peak of 29.2 on postoperative day 1 to 4.1 at the second outpatient visit ( p < 0.001). Lack of improvement in the neutrophil-to-lymphocyte ratio at postoperative day 10 was associated with increased length of stay, right heart failure, and a trend toward worsened survival. CONCLUSION: Our results indicate a significant inflammatory response to implantation of the left ventricular assist device, a known effect. The magnitude of this response may be effectively and easily monitored over time using the neutrophil-to-lymphocyte ratio. In general, approximately 30 days is required for the neutrophil-to-lymphocyte ratio to return to preoperative levels. After several months, the neutrophil-to-lymphocyte ratio improves to below preoperative levels. It is possible that this reduction reflects the reversal of various heart failure-mediated inflammatory processes following left ventricular assist device implantation.

Patient-specific instrumentation improves the accuracy of acetabular component placement in total hip arthroplasty.

AIMS: Accurate placement of the acetabular component during total hip arthroplasty (THA) is an important factor in the success of the procedure. However, the reported accuracy varies greatly and is dependent upon whether free hand or navigated techniques are used. The aim of this study was to assess the accuracy of an instrument system that incorporates 3D printed, patient-specific guides designed to optimise the placement of the acetabular component. PATIENTS AND METHODS: A total of 100 consecutive patients were prospectively enrolled and the accuracy of placement of the acetabular component was measured using post-operative CT scans. PATIENTS AND METHODS: A total of 100 consecutive patients were prospectively enrolled and the accuracy of placement of the acetabular component was measured using post-operative CT scans. CONCLUSION: Accurate placement of the acetabular component can be achieved using patient-specific guides and is superior to free hand techniques and comparable to navigated and robotic techniques. Cite this article: Bone Joint J 2016;98-B:1342-6.

Quantified degree of poultry exposure differs for human cases of avian influenza H5N1 and H7N9.

Preliminary evidence suggests that direct poultry contact may play a lesser role in transmission of avian influenza A(H7N9) than A(H5N1) to humans. To better understand differences in risk factors, we quantified the degree of poultry contact reported by H5N1 and H7N9 World Health Organization-confirmed cases. We used publicly available data to classify cases by their degree of poultry contact, including direct and indirect. To account for potential data limitations, we used two methods: (1) case population method in which all cases were classified using a range of sources; and (2) case subset method in which only cases with detailed contact information from published research literature were classified. In the case population, detailed exposure information was unavailable for a large proportion of cases (H5N1, 54%; H7N9, 86%). In the case subset, direct contact proportions were higher in H5N1 cases (70·3%) than H7N9 cases (40·0%) (χ 2 = 18·5, P < 0·001), and indirect contact proportions were higher in H7N9 cases (44·6%) than H5N1 cases (19·4%) (χ 2 = 15·5, P < 0·001). Together with emerging evidence, our descriptive analysis suggests direct poultry contact is a clearer risk factor for H5N1 than for H7N9, and that other risk factors should also be considered for H7N9.

Imatinib methanesulfonate reduces hyperphosphorylation of tau following repeated peripheral exposure to lipopolysaccharide.

For years, the prevailing hypothesis for Alzheimer's Disease (AD) has proposed a mechanism by which deposition of amyloid-beta (Aß) in the brain is independent of tau-pathologies and cognitive decline. However, despite extensive research on the disease, the mechanisms underlying the etiology of tau-pathology remain unknown. Previous research in our lab has shown that imatinib methanesulfonate (IM) blocks the peripheral production of Aß in response to LPS, thereby preventing the buildup of Aß in the hippocampus, and rescuing the cognitive dysfunction that normally follows. The present study aimed to examine the link between Aß and tau following inflammation, and to expand our understanding of how IM affects AD pathology. Specifically, we hypothesized that the IM-mediated inhibition of Aß production following inflammation would successfully protect against the hyperphosphorylation of tau (ptau). Here we show that 7days of LPS treatment in male C57BL/6J mice, which normally produces elevations in peripheral and central Aß, also produces hyperphosphorylation of tau. However, just as pre-treatment and concurrent treatment with IM blocks Aß production, it also blocks the phosphorylation of tau. In addition, 7days of LPS-induced inflammation and Aß production also leads to elevated total tau protein expression. Our results may provide support for the hypothesis that enhanced expression of tau following LPS administration is a protective measure by hippocampal neurons to compensate for the loss of the microtubule-stabilizing protein due to phosphorylation. More importantly, our results support the hypothesis that blocking the production of Aß that follows inflammation also leads to reduced tau phosphorylation, lending credence to a model in which Aß initiates tau phosphorylation.

Anatomical Factors Influencing Selective Vestibular Neurectomy: A Comparison of Posterior Fossa Approaches.

Objectives To identify measurable anatomical factors that may guide the surgical approach for posterior fossa selective vestibular neurectomy (SVN) and predict identification of the vestibulocochlear cleavage (VCC) plane. Study Design Dissection of fixed cadaveric heads through retrolabyrinthine and retrosigmoid-internal auditory canal (RSG-IAC) approaches with measurement of landmarks. Setting Cadaveric dissection model. Main Outcome Measures Area of the Trautmann triangle (TT) and the distance from the posterior semicircular canal to the anterior border of the sigmoid along the posterior Donaldson line (pDL). VCC planes from each approach were calculated and compared. Results Overall mean pDL was 8.53 mm (range: 5-11.5 mm); mean TT area was 124 mm(2) (range: 95-237 mm(2)). The VCC was identified in 63% of ears through the retrolabyrinthine (RVN) approach alone, whereas 37% of ears required the RSG-IAC approach. In ears requiring IAC dissection, the VCC was found within 1 to 2 mm distal to the porus. The pDL (p < 0.05) and area of TT (p < 0.05) were significantly larger in the RVN group compared with the RSG-IAC group. Conclusion Ears amenable to the RVN approach had a greater pDL and TT area. These anatomical measurements may have a role in surgical planning and the choice of approach for SVN.

Psychosocial Evaluation in Patients Undergoing Left Ventricular Assist Device Implantation Using the Transplant Evaluation Rating Scale.

BACKGROUND: It has been recommended that all candidates for left ventricular assist device (LVAD) implantation undergo preoperative psychologic evaluation for risk assessment. OBJECTIVE: We used the transplant evaluation rating scale (TERS) that was established for pretransplant evaluation to investigate the psychosocial assessment of patients undergoing LVAD implantation. METHODS: This study retrospectively analyzed data from 125 patients with advanced heart failure who were evaluated by the TERS before LVAD implantation. Postoperative follow-up included survival, total length of hospital stay, readmissions, and post-LVAD out-of-hospital days after discharge. The cohort was stratified according to the TERS scores into low-, moderate-, and high-risk groups. The outcomes were analyzed to evaluate whether the TERS score was associated with post-LVAD adverse events. RESULTS: The TERS, when stratified into 3 risk groups showed significant difference in 8 of the 10 psychosocial domains (p < 0.001). The mean number of outpatient days after discharge was significantly different between the low-, moderate-, and high-risk groups (p < 0.001). All other outcomes were not significantly different. CONCLUSIONS: This study showed that the TERS is successful in stratifying our patients with an LVAD into 3 risk groups, indicating the internal validity of this test. The number of out-of-hospital (outpatient) days after discharge was significantly shorter in the TERS high-risk group, which may affect the quality of life and cost of post-LVAD care.

A Systematic Review of the Comparative Epidemiology of Avian and Human Influenza A H5N1 and H7N9 - Lessons and Unanswered Questions.

The aim of this work was to explore the comparative epidemiology of influenza viruses, H5N1 and H7N9, in both bird and human populations. Specifically, the article examines similarities and differences between the two viruses in their genetic characteristics, distribution patterns in human and bird populations and postulated mechanisms of global spread. In summary, H5N1 is pathogenic in birds, while H7N9 is not. Yet both have caused sporadic human cases, without evidence of sustained, human-to-human spread. The number of H7N9 human cases in the first year following its emergence far exceeded that of H5N1 over the same time frame. Despite the higher incidence of H7N9, the spatial distribution of H5N1 within a comparable time frame is considerably greater than that of H7N9, both within China and globally. The pattern of spread of H5N1 in humans and birds around the world is consistent with spread through wild bird migration and poultry trade activities. In contrast, human cases of H7N9 and isolations of H7N9 in birds and the environment have largely occurred in a number of contiguous provinces in south-eastern China. Although rates of contact with birds appear to be similar in H5N1 and H7N9 cases, there is a predominance of incidental contact reported for H7N9 as opposed to close, high-risk contact for H5N1. Despite the high number of human cases of H7N9 and the assumed transmission being from birds, the corresponding level of H7N9 virus in birds in surveillance studies has been low, particularly in poultry farms. H7N9 viruses are also diversifying at a much greater rate than H5N1 viruses. Analyses of certain H7N9 strains demonstrate similarities with engineered transmissible H5N1 viruses which make it more adaptable to the human respiratory tract. These differences in the human and bird epidemiology of H5N1 and H7N9 raise unanswered questions as to how H7N9 has spread, which should be investigated further.

Acoustic Characterization of Axial Flow Left Ventricular Assist Device Operation In Vitro and In Vivo.

The use of left ventricular assist devices (LVADs), implantable pumps used to supplement cardiac output, has become an increasingly common and effective treatment for advanced heart failure. Although modern continuous-flow LVADs improve quality of life and survival more than medical management of heart failure, device malfunction remains a common concern. Improved noninvasive methods for assessment of LVAD function are needed to detect device complications. An electronic stethoscope was used to record sounds from the HeartMate II axial flow pump in vitro and in vivo. The data were then uploaded to a computer and analyzed using two types of acoustic analysis software. Left ventricular assist device acoustics were quantified and were related to pump speed, acoustic environment, and inflow and outflow graft patency. Peak frequency values measured in vivo were found to correlate strongly with both predicted values and in vitro measurements (r > 0.999). Plots of the area under the acoustic spectrum curve, obtained by integrating over 50 Hz increments, showed strong correlations between in vivo and in vitro measurements (r > 0.966). Device thrombosis was found to be associated with reduced LVAD acoustic amplitude in two patients who underwent surgical device exchange.

Model for end-stage liver disease predicts right ventricular failure in patients with left ventricular assist devices.

High rates of right ventricular failure continue to affect postoperative outcomes in patients implanted with left ventricular assist devices (LVADs). Development of right ventricular failure and implantation with right ventricular assist devices is known to be associated with significantly increased mortality. The model for end-stage liver disease (MELD) score is an effective means of evaluating liver dysfunction. We investigated the prognostic utility of postoperative MELD on post-LVAD implantation outcomes. MELD scores, demographic data, and outcomes including length of stay, survival, and postoperative right ventricular failure were collected for 256 patients implanted with continuous flow LVADs. Regression and Kaplan-Meier analyses were used to investigate the relationship between MELD and all outcomes. Increased MELD score was found to be an independent predictor of both right heart failure and necessity for RVAD implantation (OR 1.097, CI 1.040-1.158, p = 0.001; OR 1.121, CI 1.015, p = 0.024, respectively). Patients with RV failure and who underwent RVAD implantation had reduced postoperative survival compared to patients with RV dysfunction (no RV failure = 651.4 ± 609.8 days, RV failure = 392.6 ± 444.8 days, RVAD = 89.3 ± 72.8 days; p < 0.001). In conclusion, MELD can be used to reliably predict postoperative right heart failure and the necessity for RVAD implantation. Those patients with RV failure and RVADs experience significantly increased postoperative mortality compared to those without RV dysfunction.

Neutrophil-to-Lymphocyte Ratio Predicts Outcomes in Patients Implanted with Left Ventricular Assist Devices.

The neutrophil-to-lymphocyte ratio (NLR) has been used to predict mortality in a wide range of cardiovascular diseases including acute decompensated heart failure and non-ST-elevation myocardial infarction. We investigated the prognostic utility of the NLR in patients with advanced heart failure who received left ventricular assist devices (LVADs). Two hundred seventy-three patients implanted with LVADs at our institution were divided into tertiles based on their NLR and were retrospectively analyzed. Outcomes, including survival and right ventricular (RV) failure, were compared between tertiles. The NLR was found to be an independent predictor of postoperative mortality (odds ratio [OR] = 1.159, confidence interval [CI] = 1.022-1.314, p = 0.021) and of postoperative RV failure (OR = 1.117, CI = 1.039-1.201, p = 0.003). In addition, patients in the highest NLR tertile were found to have significantly increased postoperative length of stay (tertile 1 = 20.6 ± 10.7 days, tertile 2 = 24.2 ± 20.7 days, and tertile 3 = 28.8 ± 18.6 days, p = 0.001). In conclusion, the NLR is a simple and practical method for predicting adverse outcomes including all-cause mortality and RV failure after LVAD implantation.

Collagen type IV at the fetal-maternal interface.

INTRODUCTION: Extracellular matrix proteins play a crucial role in influencing the invasion of trophoblast cells. However the role of collagens and collagen type IV (col-IV) in particular at the implantation site is not clear. METHODS: Immunohistochemistry was used to determine the distribution of collagen types I, III, IV and VI in endometrium and decidua during the menstrual cycle and the first trimester of pregnancy. Expression of col-IV alpha chains during the reproductive cycle was determined by qPCR and protein localisation by immunohistochemistry. The structure of col-IV in placenta was examined using transmission electron microscopy. Finally, the expression of col-IV alpha chain NC1 domains and collagen receptors was localised by immunohistochemistry. RESULTS: Col-IV alpha chains were selectively up-regulated during the menstrual cycle and decidualisation. Primary extravillous trophoblast cells express collagen receptors and secrete col-IV in vitro and in vivo, resulting in the increased levels found in decidua basalis compared to decidua parietalis. A novel expression pattern of col-IV in the mesenchyme of placental villi, as a three-dimensional network, was found. NC1 domains of col-IV alpha chains are known to regulate tumour cell migration and the selective expression of these domains in decidua basalis compared to decidua parietalis was determined. DISCUSSION: Col-IV is expressed as novel forms in the placenta. These findings suggest that col-IV not only represents a structural protein providing tissue integrity but also influences the invasive behaviour of trophoblast cells at the implantation site.

Energy status and HIF signalling in chorionic villi show no evidence of hypoxic stress during human early placental development.

Early human placental and embryonic development occurs in a physiologically low oxygen environment supported by histiotrophic secretions from endometrial glands. In this study, we compare the placental metabolomic profile in the first, second and third trimesters to determine whether the energy demands are adequately met in the first trimester. We investigated whether hypoxia-inducible factors, HIF-1α and/or HIF-2α, might regulate transcription during the first trimester. First and second trimester tissue was collected using a chorionic villus sampling-like (CVS) technique. Part of each villus sample was frozen immediately and the remainder cultured under 2 or 21% O2 ± 1 mM H2O2, and ±the p38 MAPK pathway inhibitor, PD169316. Levels of HIF-1α were assessed by western blotting and VEGFA, PlGF and GLUT3 transcripts were quantified by RT-PCR. Term samples were collected from normal elective Caesarean deliveries. There were no significant differences in concentrations of ADP, NAD(+), lactate, and glucose, and in the ATP/ADP ratio, across gestational age. Neither HIF-1α nor HIF-2α could be detected in time-zero CVS samples. However, culture under any condition (2 or 21% O2 ± 1 mM H2O2) increased HIF-1α and HIF-2α. HIF-1α and HIF-2α were additionally detected in specimens retrieved after curettage. HIF-1α stabilization was accompanied by significant increases in VEGFA and GLUT3 and a decrease in PlGF mRNAs. These effects were suppressed by PD169316. In conclusion, our data suggest that first trimester placental tissues are not energetically compromised, and that HIF-1α is unlikely to play an appreciable role in regulating transcriptional activity under steady-state conditions in vivo. However, the pathway may be activated by stress conditions.

Stress-induced inhibition of nonsense-mediated RNA decay regulates intracellular cystine transport and intracellular glutathione through regulation of the cystine/glutamate exchanger SLC7A11.

SLC7A11 encodes a subunit of the xCT cystine/glutamate amino-acid transport system and has a critical role in the generation of glutathione and the protection of cells from oxidative stress. Expression of SLC7A11 promotes tumorigenesis and chemotherapy resistance, but while SLC7A11 has been previously noted to be upregulated in hypoxic cells, its regulation has not been fully delineated. We have recently shown that nonsense-mediated RNA decay (NMD) is inhibited by cellular stresses generated by the tumor microenvironment, including hypoxia, and augments tumorigenesis. Here we demonstrate that the inhibition of NMD by various cellular stresses leads to the stabilization and upregulation of SLC7A11 mRNA and protein. The inhibition of NMD and upregulation of SLC7A11 augments intracellular cystine transport and increases intracellular levels of cysteine and glutathione. Accordingly, the inhibition of NMD protects cells against oxidative stress via SLC7A11 upregulation. Together our studies identify a mechanism for the dynamic regulation of SLC7A11, through the stress-inhibited regulation of NMD, and add to the growing evidence that the inhibition of NMD is an adaptive response.