Matriglycan maintains t-tubule structural integrity in cardiac muscle.

Maintaining the structure of cardiac membranes and membrane organelles is essential for heart function. A critical cardiac membrane organelle is the transverse tubule system (called the t-tubule system) which is an invagination of the surface membrane. A unique structural characteristic of the cardiac muscle t-tubule system is the extension of the extracellular matrix (ECM) from the surface membrane into the t-tubule lumen. However, the importance of the ECM extending into the cardiac t-tubule lumen is not well understood. Dystroglycan (DG) is an ECM receptor in the surface membrane of many cells, and it is also expressed in t-tubules in cardiac muscle. Extensive posttranslational processing and O-glycosylation are required for DG to bind ECM proteins and the binding is mediated by a glycan structure known as matriglycan. Genetic disruption resulting in defective O-glycosylation of DG results in muscular dystrophy with cardiorespiratory pathophysiology. Here, we show that DG is essential for maintaining cardiac t-tubule structural integrity. Mice with defects in O-glycosylation of DG developed normal t-tubules but were susceptible to stress-induced t-tubule loss or severing that contributed to cardiac dysfunction and disease progression. Finally, we observed similar stress-induced cardiac t-tubule disruption in a cohort of mice that solely lacked matriglycan. Collectively, our data indicate that DG in t-tubules anchors the luminal ECM to the t-tubule membrane via the polysaccharide matriglycan, which is critical to transmitting structural strength of the ECM to the t-tubules and provides resistance to mechanical stress, ultimately preventing disruptions in cardiac t-tubule integrity.

A comprehensive analysis of neuroblastoma incidence, survival, and racial and ethnic disparities from 2001 to 2019.

BACKGROUND: We characterize the incidence and 5-year survival of children and adolescents with neuroblastoma stratified by demographic and clinical factors based on the comprehensive data from United States Cancer Statistics (USCS) and the National Program of Cancer Registries (NPCR). METHODS: We analyzed the incidence of neuroblastoma from USCS (2003-2019) and survival data from NPCR (2001-2018) for patients less than 20 years old. Incidence trends were calculated by average annual percent change (AAPC) using joinpoint regression. Differences in relative survival were estimated comparing non-overlapping confidence intervals (CI). RESULTS: We identified 11,543 primary neuroblastoma cases in USCS. Age-adjusted incidence was 8.3 per million persons [95% CI: 8.2, 8.5], with an AAPC of 0.4% [95% CI: -0.1, 0.9]. Five-year relative survival from the NPCR dataset (n = 10,676) was 79.7% [95% CI: 78.9, 80.5]. Patients aged less than 1 year had the highest 5-year relative survival (92.5%). Five-year relative survival was higher for non-Hispanic White patients (80.7%) or Hispanic patients (80.8%) compared to non-Hispanic Black patients (72.6%). CONCLUSION: Neuroblastoma incidence was stable during 2003-2019. Differences in relative survival exist by sex, age, race/ethnicity, and stage; patients who were male, older, non-Hispanic Black, or with distant disease had worse survival. Future studies could seek to assess the upstream factors driving disparities in survival, and evaluate interventions to address inequities and improve survival across all groups.

Reporting and impact of subsequent cycle toxicities in oncology phase I clinical trials.

BACKGROUND/AIMS: As oncology treatments evolve, classic assumptions of toxicity associated with cytotoxic agents may be less relevant, requiring new design strategies for trials intended to inform dosing strategies for agents that may be administered beyond a set number of defined cycles. We describe the overall incidence of dose-limiting toxicities during and after cycle 1, frequency of reporting subsequent cycle toxicities, and the impact of post-cycle 1 dose-limiting toxicities on conclusions drawn from oncology phase 1 clinical trials. METHODS: We conducted a systematic review of subsequent cycle toxicities in oncology phase I clinical trials published in the Journal of Clinical Oncology from 2000 to 2020. We used chi-square tests and multivariate logistic regression to describe predictors of reporting subsequent cycle toxicity data. RESULTS: From 2000 to 2020, we identified 489 articles reporting on therapeutic phase 1 clinical trials. Of these, 421 (86%) reported data regarding cycle 1 dose-limiting toxicities and 170 (35%) reported data on cycle 1 dose modifications. Of the trials that reported cycle 1 dose-limiting toxicities, the median percentage of patients that experienced cycle 1 dose-limiting toxicities was 8.89%. Only 47 (9.6%) publications reported on post-cycle 1 dose-limiting toxicities and only 92 (19%) reported on dose modifications beyond cycle 1. Of the trials that reported post-cycle 1 dose-limiting toxicities, the median percentage of patients that experienced post-cycle 1 dose-limiting toxicities was 14.8%. Among the 371 studies with a recommended phase 2 dose, 89% did not report whether post-cycle 1 toxicities impacted the recommended phase 2 dose. More recent year of publication was independently associated with reduced odds of reporting subsequent cycle toxicity. CONCLUSION: Reporting of subsequent cycle toxicity is uncommon in oncology phase I clinical trial publications and becoming less common over time. Guidelines for reporting of phase I oncology clinical trials should expand to include toxicity data beyond the first cycle.

Thermoconforming rays of the star-nosed mole.

The star-nosed mole (Condylura cristata) is renowned for its densely innervated 22 appendage star-like rostrum ('star') specialized for tactile sensation. As a northerly distributed insectivorous mammal exploiting aquatic and terrestrial habitats, these vascularized nasal rays are regularly exposed to cold water and thermally conductive soil, leading us to ask whether the star surface temperature, a proxy for blood flow, conforms to the local ambient temperature to conserve body heat. Alternatively, given the exquisite sensory nature of the star, we posited that the uninsulated rays may be kept warm when foraging to maintain high mechanosensory function. To test these hypotheses, we remotely monitored surface temperatures in wild-caught star-nosed moles. Although the tail acted as a thermal window exhibiting clear vasoconstriction/vasodilation, the star varied passively in surface temperature, with little evidence for thermoregulatory vasomotion. This thermoconforming response may have evolved to minimize conductive heat loss to the water or wet soils when foraging.

Clinical and biological features prognostic of survival after relapse or progression of INRGSS stage MS pattern neuroblastoma: A report from the International Neuroblastoma Risk Group (INRG) project.

BACKGROUND: Outcomes for patients with INRGSS metastatic special (MS) metastatic pattern neuroblastoma at initial diagnosis are well described. Prognosis after an initial event (relapse, progression, secondary malignancy) is unclear. METHODS: We investigated characteristics of MS pattern neuroblastoma patients in the International Neuroblastoma Risk Group database who subsequently experienced an event. Post-event overall survival (OS) ± standard error was calculated overall and by diagnosis era: before 2000 versus 2001 or after. Cox models were used to identify factors prognostic of post-event OS. RESULTS: Among 209 patients with an event, 88% were less than 365 days old at diagnosis; tumors were MYCN amplified in 24% and diploid in 33%. The median (range) time from diagnosis to first event was 8.16 months (7 days to 11.24 years). Of 96 patients with known relapse/progression pattern, 75% were metastatic or primary plus metastatic. Five-year post-event OS was 53% ± 3.6% and was higher for 2001 and afterwards (62% ± 5.0%) compared to before 2001 (44% ± 4.9%; p = .0046). In patients diagnosed in 2001 and after, older age, Hispanic ethnicity, MYCN amplification, 1p LOH, diploidy, high Mitotic Karyorrhexis Index, high lactate dehydrogenase (LDH), unfavorable histology, and longer time to first event were prognostic of worse post-event OS. Independent adverse prognostic factors on multivariable testing were non-White race, MYCN amplification, and diploidy. SUMMARY: Patients diagnosed in and after 2001 have substantially better post-event OS compared to before 2001. In those diagnosed in and after 2001, most well-accepted prognostic factors for OS at diagnosis are also prognostic of post-event OS. Future studies may evaluate strategies to improve outcomes in this rare population.

Phase 1 study of cabozantinib in combination with topotecan-cyclophosphamide for patients with relapsed Ewing sarcoma or osteosarcoma.

PURPOSE: Phase 1 study assessing the safety and toxicity of cabozantinib in combination with topotecan and cyclophosphamide for relapsed osteosarcoma and Ewing sarcoma. METHODS: Oral cabozantinib (25 mg/m2 ) was administered daily for 21 (dose level 1) or 14 (dose level -1B) days. Topotecan (0.75 mg/m2 ) and cyclophosphamide (250 mg/m2 ) were administered intravenously (IV) on days 1-5. A modified 3+3 design based upon first cycle dose-limiting toxicities (DLT) was used for dose escalation. RESULTS: Twelve patients with a median age of 15 (12.9-33.2) years were enrolled (seven with Ewing sarcoma; five with osteosarcoma); all were evaluable for toxicity. At dose level 1, three of six patients developed first cycle DLT: grade 3 epistaxis, grade 3 transaminitis, and prolonged grade 2 thrombocytopenia. Six patients were enrolled on dose level -1B (interrupted cabozantinib, given days 8-21), with one first cycle DLT (grade 3 pneumothorax) observed. Of the 10 response evaluable patients, one had partial response (Ewing sarcoma), seven had stable disease, and two had progressive disease. CONCLUSIONS: The recommended phase 2 doses and schedules for this combination are topotecan 0.75 mg/m2 IV days 1-5, cyclophosphamide 250 mg/m2 IV days 1-5, and cabozantinib 25 mg/m2 days 8-21. Non-concomitant administration of cabozantinib with cytotoxic therapy in this population has acceptable toxicity, while allowing for potential disease control.

A Multilingual Chatbot Can Effectively Engage Arthroplasty Patients Who Have Limited English Proficiency.

BACKGROUND: In the United States, English language proficiency is widely accepted as a key social determinant of health. For patients with limited English proficiency (LEP), language barriers can make the delivery of perioperative instructions challenging. The purpose of this study was to evaluate whether a multilingual chatbot could effectively engage LEP patients and improve their outcome after total joint arthroplasty (TJA). METHODS: We identified 1,282 TJA patients (705 knees, 577 hips) who enrolled in a short message service (SMS) chatbot from 2020-2022. Forty-seven patients enrolled in the chatbot received their messages in a language other than English. A historical control of 68 LEP patients not enrolled in the chatbot was identified. Chi-squared, Fisher's exact test, and t-tests were performed to measure the effect that conversational engagement had on emergency department (ED) visits, hospital readmissions, and reoperations. RESULTS: There was no difference in the conversational engagement between LEP patients and those with English as their primary language (EPL) (12.3 versus 12.2 text responses, P = .959). The LEP cohort who enrolled in the chatbot had fewer readmissions (0% versus 8.3%, P = .013) and a near significant reduction in ED visits (0.9% versus 8.0%, P = .085) compared to those not enrolled. There was no difference in reoperations between the 2 cohorts. CONCLUSION: LEP and EPL patients engaged equally with the multilingual chatbot. LEP patients who enrolled in the chatbot had fewer readmissions and a near significant reduction in ED visits. Multilingual platforms such as this chatbot may provide more equitable care to our frequently encountered LEP patients.

Predictors of Stigma, Guilt, and Shame among Adults Bereaved by Fatal Overdose.

With the spectacular rise of US overdose deaths, bereavement for these affected families has become a matter of increasing concern. Qualitative research has highlighted the role of stigmatization as well as guilt and shame among this population. However, the magnitude and pre-death predictors of stigmatization, guilt, and shame have yet to be assessed quantitatively. In the current study, we assess the magnitude of stigmatization, guilt, and shame among 115 adults bereaved by overdose by drawing comparisons with 185 adults bereaved by suicide. Results revealed no significant differences regarding overall levels of stigmatization, guilt, and shame between the overdose and suicide bereaved. Among the overdose bereaved, regression models indicated a number of pre-death factors associated with stigmatization, guilt, and shame, such as the frequency of the decedent's drug use, family drug use severity, and interpersonal conflict between the bereaved and the decedent. Implications and future directions for research are discussed.

Change in alcohol demand following a brief intervention predicts change in alcohol use: A latent growth curve analysis.

BACKGROUND: The association between behavioral economic demand and various alcohol use outcomes is well established. However, few studies have examined whether changes in demand occur following a brief alcohol intervention (BAI), and whether this change predicts alcohol outcomes over the long term. METHODS: Parallel process piecewise latent growth curve models were examined in a sample of 393 heavy drinking emerging adults (60.8% women; 85.2% white; Mage  = 18.77). In these models, two linear slopes represented rates of change in alcohol use, heavy drinking episodes, alcohol-related problems, and demand (intensity and highest expenditure across all price points or Omax ) from baseline to 1 month (slope 1) and 1 month to 16 months (slope 2). Mediation analyses were conducted to estimate the effect of a BAI on 16-month alcohol outcomes through slope 1 demand. RESULTS: A two-session BAI predicted significant reductions in all five outcomes from baseline to 1-month follow-up. Although no further reduction was observed from the 1-month to the 16-month follow-up, there was no regression to baseline levels. Slope 1 demand intensity, but not Omax , significantly mediated the association between BAI and both outcomes-heavy drinking episodes (Est. = -0.23, SE = 0.08, p < 0.01) and alcohol-related problems (Est. = -0.15, SE = 0.07, p < 0.05)-at the 16-month follow-up. CONCLUSIONS: Reducing high valuation of alcohol among heavy drinking emerging adults within the first month following BAI is critical for the long-term efficacy of the intervention. A two-session BAI was associated with enduring reductions in alcohol demand, and the change in demand intensity, but not Omax , was associated with sustained reductions in heavy drinking and alcohol-related problems.

A unique variant of lymphocytic choriomeningitis virus that induces pheromone binding protein MUP: Critical role for CTL.

Lymphocytic choriomeningitis virus (LCMV) WE variant 2.2 (v2.2) generated a high level of the major mouse urinary protein: MUP. Mice infected with LCMV WE v54, which differed from v2.2 by a single amino acid in the viral glycoprotein, failed to generate MUP above baseline levels found in uninfected controls. Variant 54 bound at 2.5 logs higher affinity to the LCMV receptor α-dystroglycan (α-DG) than v2.2 and entered α-DG-expressing but not α-DG-null cells. Variant 2.2 infected both α-DG-null or -expressing cells. Variant 54 infected more dendritic cells, generated a negligible CD8 T cell response, and caused a persistent infection, while v2.2 generated cytotoxic T lymphocytes (CTLs) and cleared virus within 10 days. By 20 days postinfection and through the 80-day observation period, significantly higher amounts of MUP were found in v2.2-infected mice. Production of MUP was dependent on virus-specific CTL as deletion of such cells aborted MUP production. Furthermore, MUP production was not elevated in v2.2 persistently infected mice unless virus was cleared following transfer of virus-specific CTL.

Protective role for the N-terminal domain of α-dystroglycan in Influenza A virus proliferation.

α-Dystroglycan (α-DG) is a highly glycosylated basement membrane receptor that is cleaved by the proprotein convertase furin, which releases its N-terminal domain (α-DGN). Before cleavage, α-DGN interacts with the glycosyltransferase LARGE1 and initiates functional O-glycosylation of the mucin-like domain of α-DG. Notably, α-DGN has been detected in a wide variety of human bodily fluids, but the physiological significance of secreted α-DGN remains unknown. Here, we show that mice lacking α-DGN exhibit significantly higher viral titers in the lungs after Influenza A virus (IAV) infection (strain A/Puerto Rico/8/1934 H1N1), suggesting an inability to control virus load. Consistent with this, overexpression of α-DGN before infection or intranasal treatment with recombinant α-DGN prior and during infection, significantly reduced IAV titers in the lungs of wild-type mice. Hemagglutination inhibition assays using recombinant α-DGN showed in vitro neutralization of IAV. Collectively, our results support a protective role for α-DGN in IAV proliferation.

Ventricular arrhythmia burden during the coronavirus disease 2019 (COVID-19) pandemic.

AIMS: Our objective was to determine the ventricular arrhythmia burden in implantable cardioverter-defibrillator (ICD) patients during COVID-19. METHODS AND RESULTS: In this multicentre, observational, cohort study over a 100-day period during the COVID-19 pandemic in the USA, we assessed ventricular arrhythmias in ICD patients from 20 centres in 13 states, via remote monitoring. Comparison was via a 100-day control period (late 2019) and seasonal control period (early 2019). The primary outcome was the impact of COVID-19 on ventricular arrhythmia burden. The secondary outcome was correlation with COVID-19 incidence. During the COVID-19 period, 5963 ICD patients underwent remote monitoring, with 16 942 episodes of treated ventricular arrhythmias (2.8 events per 100 patient-days). Ventricular arrhythmia burden progressively declined during COVID-19 (P < 0.001). The proportion of patients with ventricular arrhythmias amongst the high COVID-19 incidence states was significantly reduced compared with those in low incidence states [odds ratio 0.61, 95% confidence interval (CI) 0.54-0.69, P < 0.001]. Comparing patients remotely monitored during both COVID-19 and control periods (n = 2458), significantly fewer ventricular arrhythmias occurred during COVID-19 [incident rate ratio (IRR) 0.68, 95% CI 0.58-0.79, P < 0.001]. This difference persisted when comparing the 1719 patients monitored during both the COVID-19 and seasonal control periods (IRR 0.69, 95% CI 0.56-0.85, P < 0.001). CONCLUSIONS: During COVID-19, there was a 32% reduction in ventricular arrhythmias needing device therapies, coinciding with measures of social isolation. There was a 39% reduction in the proportion of patients with ventricular arrhythmias in states with higher COVID-19 incidence. These findings highlight the potential role of real-life stressors in ventricular arrhythmia burden in individuals with ICDs. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry; URL: https://www.anzctr.org.au/; Unique Identifier: ACTRN12620000641998.

Examining bereavement-related needs and outcomes among survivors of sudden loss: A latent profile analysis.

OBJECTIVE: Recognizing important bereavement-related needs among sudden loss survivors (e.g., suicide, overdose)-a population that is burgeoning and at risk for deleterious outcomes-is a critical task as needs may reflect modifiable grief-related variables that can assist with post-loss adjustment. METHODS: Latent profile analysis was used among 347 sudden loss survivors to (a) identify distinct patterns of needs among survivors of sudden loss, (b) assess predictors of such profiles, and (c) investigate differences in profiles in terms of bereavement outcomes. RESULTS: Four classes of bereavement-related needs were identified: a low needs class, a moderate needs-spiritual class, a moderate needs-relational class, and a high needs (HN) class. Clear differences emerged between need classes with the HN class evidencing the greatest level of grief and mental health sequelae. CONCLUSION: Tending to bereavement-related needs is critical, as they indicate the degree of distress and reflect modifiable therapeutic variables.

Burrowing star-nosed moles (Condylura cristata) are not hypoxia tolerant.

Star-nosed moles (Condylura cristata) have an impressive diving performance and burrowing lifestyle, yet no ventilatory data are available for this or any other talpid mole species. We predicted that, like many other semi-aquatic and fossorial small mammals, star-nosed moles would exhibit: (i) a blunted (i.e. delayed or reduced) hypoxic ventilatory response, (ii) a reduced metabolic rate and (iii) a lowered body temperature (Tb) in hypoxia. We thus non-invasively measured these variables from wild-caught star-nosed moles exposed to normoxia (21% O2) or acute graded hypoxia (21-6% O2). Surprisingly, star-nosed moles did not exhibit a blunted HVR or decreased Tb in hypoxia, and only manifested a significant, albeit small (<8%), depression of metabolic rate at 6% O2 relative to normoxic controls. Unlike small rodents inhabiting similar niches, star-nosed moles are thus intolerant to hypoxia, which may reflect an evolutionary trade-off favouring the extreme sensory biology of this unusual insectivore.

Trajectories of reward availability moderate the impact of brief alcohol interventions on alcohol severity in heavy-drinking young adults.

BACKGROUND: Behavioral economic theory predicts that low access to environmental reward is a risk factor for alcohol use disorder (AUD). The Substance-Free Activity Session (SFAS) is a behavioral economic supplement to standard brief alcohol interventions that attempts to increase environmental reward and may therefore have beneficial effects, particularly for individuals with low levels of environmental reward. METHODS: Participants were 393 college students who reported at least 2 heavy-drinking episodes in the past month. Participants were randomly assigned to 1 of 3 conditions following a baseline assessment: a standard alcohol-focused brief motivational intervention plus relaxation training session (BMI + RT), BMI plus Substance-Free Activity Session (BMI + SFAS), or an assessment-only control condition (AO). In a secondary analysis of the data from this study, we used person-centered statistical techniques to describe trajectories of alcohol severity and environmental reward over a 16-month follow-up and examined whether environmental reward levels moderated the effectiveness of the interventions. RESULTS: Piecewise growth mixture modeling identified 2 trajectories of reward availability: low increasing (LR; n = 120) and high stable (HR; n = 273). Depressive symptoms, cannabis use, sensation seeking, and low life satisfaction were associated with a greater probability of classification in the LR trajectory. Alcohol severity was greater in the LR trajectory than the HR trajectory. For students in the LR trajectory, at 1, 6, and 12 months, BMI + SFAS led to greater increases in reward availability and reduced levels of alcohol severity compared with the BMI + RT and AO conditions and at 16 months compared with AO. CONCLUSIONS: Young adults with low levels of environmental reward are at heightened risk for greater alcohol severity and may show greater benefit from brief alcohol interventions that focus on increasing substance-free reward than individuals who are not deficient in reward availability.

Role of bone marrow biopsy for staging new patients with Ewing sarcoma: A systematic review.

The incidence of bone marrow metastasis (BMM) in newly diagnosed Ewing sarcoma (ES) is variable across studies. An optimal staging strategy for detecting BMM is not defined. While bone marrow (BM) biopsy and/or aspirate (BMBA) have been the gold standard, [F-18]fluorodeoxyglucose positron emission tomography (FDG-PET) to detect BMM may decrease reliance on BMBA. We conducted a systematic review to assess incidence of BMM and the role of FDG-PET. We observed a pooled incidence of BMM by BMBA of 4.8% in all newly diagnosed ES patients and 17.5% among patients with metastatic disease. Only 1.2% of patients had BMM as their sole metastatic site. FDG-PET detection of BMM compared to BMBA demonstrated pooled 100% sensitivity and 96% specificity, positive predictive value of 75%, and negative predictive value of 100%. In the era of FDG-PET imaging, omission of BMBA may be considered in patients with otherwise localized disease after initial staging studies.

Atrial fibrillation burden during the coronavirus disease 2019 pandemic.

AIMS: The aim of this study is to determine the association between the coronavirus disease 2019 (COVID-19) pandemic and atrial fibrillation (AF) occurrence in individuals with cardiac implantable electronic devices (CIEDs). METHOD AND RESULTS: Multi-centre, observational, cohort study over a 100-day period during the COVID-19 pandemic (COVID-19) in the USA. Remote monitoring was used to assess AF episodes in patients with a CIED (pacemaker or defibrillator; 20 centres, 13 states). For comparison, the identical 100-day period in 2019 was used (Control). The primary outcomes were the AF burden during the COVID-19 pandemic, and the association of the pandemic with AF occurrence, as compared with 1 year prior. The secondary outcome was the association of AF occurrence with per-state COVID-19 prevalence. During COVID-19, 10 346 CIEDs with an atrial lead were monitored. There were 16 570 AF episodes of ≥6 min transmitted (16 events per 1000 patient days) with a significant increase in proportion of patients with AF episodes in high COVID-19 prevalence states compared with low prevalence states [odds ratio 1.34, 95% confidence interval (CI) 1.21-1.48, P < 0.001]. There were significantly more AF episodes during COVID-19 compared with Control [incident rate ratio (IRR) 1.33, 95% CI 1.25-1.40, P < 0.001]. This relationship persisted for AF episodes ≥1 h (IRR 1.65, 95% CI 1.53-1.79, P < 0.001) and ≥6 h (IRR 1.54, 95% CI 1.38-1.73, P < 0.001). CONCLUSION: During the first 100 days of COVID-19, a 33% increase in AF episodes occurred with a 34% increase in the proportion of patients with AF episodes observed in states with higher COVID-19 prevalence. These findings suggest a possible association between pandemic-associated social disruptions and AF in patients with CIEDs. CLINICAL TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry: ACTRN12620000692932.

The quadriceps insertion of the medial patellofemoral complex demonstrates the greatest anisometry through flexion.

PURPOSE: A comprehensive understanding of the biomechanical properties of the medial patellofemoral complex (MPFC) is necessary when performing an MPFC reconstruction. How components of the MPFC change over the course of flexion can influence the surgeon's choice of location for graft fixation along the extensor mechanism. The purpose of this study was to (1) determine native MPFC length changes throughout a 90° arc using an anatomically based attachment and using Schöttle's point, and (2) compare native MPFC length changes with different MPFC attachment sites along the extensor mechanism. METHODS: Eight fresh-frozen (n = 8), cadaveric knees were dissected of all soft tissue structures except the MPFC. The distance between the femoral footprint (identified through anatomical landmarks and Schottle's point) and the MPFC was calculated at four attachment sites along the extensor mechanism [midpoint of the patella [MP], the center of the osseous footprint of the MPFC (FC), the superomedial corner of the patella at the quadriceps insertion (SM), and the proximal extent of the MPFC along the quadriceps tendon (QT)] at 0°, 20°, 40°, 60°, and 90° of flexion. RESULTS: Length changes were investigated between the MPFL femoral attachment site and the radiographic surrogate of the MPFL attachment site, Schottle's Point (SP). Paired t tests at each of the four components showed no differences in length change from 0° to 90° when comparing SP to the anatomic MPFC insertion. MPFL length changes from 0° to 90° were greatest at the QT point (13.9 ± 3.0 mm) and smallest at the MP point (2.7 ± 4.4 mm). The FC and SM points had a length change of 6.6 ± 4.2 and 9.0 ± 3.8, respectively. Finally, when examining how the length of the MPFC components changed through flexion, the greatest differences were seen at QT where all comparisons were significant (p < 0.01) except when comparing 0° vs 20° (n.s.). CONCLUSION: The MPFC demonstrates the most significant length changes between 0° and 20° of flexion, while more isometric behavior was seen during 20°-90°. The attachment points along the extensor mechanism demonstrate different length behaviors, where the more proximal components of the MPFC display greater anisometry through the arc of motion. When performing a proximal MPFC reconstruction, surgeons should expect increased length changes compared to reconstructions utilizing distal attachment sites.

HNK-1 sulfotransferase modulates α-dystroglycan glycosylation by 3-O-sulfation of glucuronic acid on matriglycan.

Mutations in multiple genes required for proper O-mannosylation of α-dystroglycan are causal for congenital/limb-girdle muscular dystrophies and abnormal brain development in mammals. Previously, we and others further elucidated the functional O-mannose glycan structure that is terminated by matriglycan, [(-GlcA-ß3-Xyl-α3-)n]. This repeating disaccharide serves as a receptor for proteins in the extracellular matrix. Here, we demonstrate in vitro that HNK-1 sulfotransferase (HNK-1ST/carbohydrate sulfotransferase) sulfates terminal glucuronyl residues of matriglycan at the 3-hydroxyl and prevents further matriglycan polymerization by the LARGE1 glycosyltransferase. While α-dystroglycan isolated from mouse heart and kidney is susceptible to exoglycosidase digestion of matriglycan, the functional, lower molecular weight α-dystroglycan detected in brain, where HNK-1ST expression is elevated, is resistant. Removal of the sulfate cap by a sulfatase facilitated dual-glycosidase digestion. Our data strongly support a tissue specific mechanism in which HNK-1ST regulates polymer length by competing with LARGE for the 3-position on the nonreducing GlcA of matriglycan.

Emergence of a Chimeric Globin Pseudogene and Increased Hemoglobin Oxygen Affinity Underlie the Evolution of Aquatic Specializations in Sirenia.

As limits on O2 availability during submergence impose severe constraints on aerobic respiration, the oxygen binding globin proteins of marine mammals are expected to have evolved under strong evolutionary pressures during their land-to-sea transition. Here, we address this question for the order Sirenia by retrieving, annotating, and performing detailed selection analyses on the globin repertoire of the extinct Steller's sea cow (Hydrodamalis gigas), dugong (Dugong dugon), and Florida manatee (Trichechus manatus latirostris) in relation to their closest living terrestrial relatives (elephants and hyraxes). These analyses indicate most loci experienced elevated nucleotide substitution rates during their transition to a fully aquatic lifestyle. While most of these genes evolved under neutrality or strong purifying selection, the rate of nonsynonymous/synonymous replacements increased in two genes (Hbz-T1 and Hba-T1) that encode the α-type chains of hemoglobin (Hb) during each stage of life. Notably, the relaxed evolution of Hba-T1 is temporally coupled with the emergence of a chimeric pseudogene (Hba-T2/Hbq-ps) that contributed to the tandemly linked Hba-T1 of stem sirenians via interparalog gene conversion. Functional tests on recombinant Hb proteins from extant and ancestral sirenians further revealed that the molecular remodeling of Hba-T1 coincided with increased Hb-O2 affinity in early sirenians. Available evidence suggests that this trait evolved to maximize O2 extraction from finite lung stores and suppress tissue O2 offloading, thereby facilitating the low metabolic intensities of extant sirenians. In contrast, the derived reduction in Hb-O2 affinity in (sub)Arctic Steller's sea cows is consistent with fueling increased thermogenesis by these once colossal marine herbivores.