Identification, Characterization, and Heritability of Murine Metastable Epialleles: Implications for Non-genetic Inheritance.

Generally repressed by epigenetic mechanisms, retrotransposons represent around 40% of the murine genome. At the Agouti viable yellow (Avy) locus, an endogenous retrovirus (ERV) of the intracisternal A particle (IAP) class retrotransposed upstream of the agouti coat-color locus, providing an alternative promoter that is variably DNA methylated in genetically identical individuals. This results in variable expressivity of coat color that is inherited transgenerationally. Here, a systematic genome-wide screen identifies multiple C57BL/6J murine IAPs with Avy epigenetic properties. Each exhibits a stable methylation state within an individual but varies between individuals. Only in rare instances do they act as promoters controlling adjacent gene expression. Their methylation state is locus-specific within an individual, and their flanking regions are enriched for CTCF. Variably methylated IAPs are reprogrammed after fertilization and re-established as variable loci in the next generation, indicating reconstruction of metastable epigenetic states and challenging the generalizability of non-genetic inheritance at these regions.

OPA1 disease-causing mutants have domain-specific effects on mitochondrial ultrastructure and fusion.

Inner mitochondrial membrane fusion and cristae shape depend on optic atrophy protein 1, OPA1. Mutations in OPA1 lead to autosomal dominant optic atrophy (ADOA), an important cause of inherited blindness. The Guanosin Triphosphatase (GTPase) and GTPase effector domains (GEDs) of OPA1 are essential for mitochondrial fusion; yet, their specific roles remain elusive. Intriguingly, patients carrying OPA1 GTPase mutations have a higher risk of developing more severe multisystemic symptoms in addition to optic atrophy, suggesting pathogenic contributions for the GTPase and GED domains, respectively. We studied OPA1 GTPase and GED mutations to understand their domain-specific contribution to protein function by analyzing patient-derived cells and gain-of-function paradigms. Mitochondria from OPA1 GTPase (c.870+5G>A and c.889C>T) and GED (c.2713C>T and c.2818+5G>A) mutants display distinct aberrant cristae ultrastructure. While all OPA1 mutants inhibited mitochondrial fusion, some GTPase mutants resulted in elongated mitochondria, suggesting fission inhibition. We show that the GED is dispensable for fusion and OPA1 oligomer formation but necessary for GTPase activity. Finally, splicing defect mutants displayed a posttranslational haploinsufficiency-like phenotype but retained domain-specific dysfunctions. Thus, OPA1 domain-specific mutants result in distinct impairments in mitochondrial dynamics, providing insight into OPA1 function and its contribution to ADOA pathogenesis and severity.

Trans-obliquus inferior capitis course of the greater occipital nerve: A potential cause of occipital neuralgia?

Occipital neuralgia can be due to multiple etiologies. One of these is potential compression of the greater occipital nerve (GON). In this regard, one relationship of the GON, its course through the obliquus inferior capitis muscle (OIC), has yet to be well studied. Therefore, the current anatomical study was performed to elucidate this relationship better. In the prone position, the suboccipital triangle was exposed, and the relationship between the GON and OIC was documented in 72 adult cadavers (144 sides). The GON was found to pierce the OIC on four sides (2.8%), unilaterally in two cadavers and bilaterally in one cadaver. Two cadavers were male, and one was female. Histological samples were taken from GONs with a normal course around the OIC, and nerves were found to pierce the OIC. The GON of all four sides identified histological changes consistent with nerve potential compression (e.g., epineurial and perineurial thickening). This is also the first histological analysis of the trans-OIC course of the GON, demonstrating signs of chronic nerve potential compression. Although uncommon, entrapment of the GON by the OIC may be an underrecognized etiology of occipital neuralgia.

Easy Access to Energy Fluctuations in Nonequilibrium Quantum Many-Body Systems.

We combine theoretical and experimental efforts to propose a method for studying energy fluctuations, in particular, to obtain the related bistochastic matrix of transition probabilities by means of simple measurements at the end of a protocol that drives a many-body quantum system out of equilibrium. This scheme is integrated with numerical optimizations in order to ensure a proper analysis of the experimental data, leading to physical probabilities. The method is experimentally evaluated employing a two interacting spin-1/2 system in a nuclear magnetic resonance setup. We show how to recover the transition probabilities using only local measures, which enables an experimental verification of the detailed fluctuation theorem in a many-body system driven out of equilibrium.

Unfamiliar partnerships limit cnidarian holobiont acclimation to warming.

Enhancing the resilience of corals to rising temperatures is now a matter of urgency, leading to growing efforts to explore the use of heat tolerant symbiont species to improve their thermal resilience. The notion that adaptive traits can be retained by transferring the symbionts alone, however, challenges the holobiont concept, a fundamental paradigm in coral research. Holobiont traits are products of a specific community (holobiont) and all its co-evolutionary and local adaptations, which might limit the retention or transference of holobiont traits by exchanging only one partner. Here we evaluate how interchanging partners affect the short- and long-term performance of holobionts under heat stress using clonal lineages of the cnidarian model system Aiptasia (host and Symbiodiniaceae strains) originating from distinct thermal environments. Our results show that holobionts from more thermally variable environments have higher plasticity to heat stress, but this resilience could not be transferred to other host genotypes through the exchange of symbionts. Importantly, our findings highlight the role of the host in determining holobiont productivity in response to thermal stress and indicate that local adaptations of holobionts will likely limit the efficacy of interchanging unfamiliar compartments to enhance thermal tolerance.

Experimental Characterization of a Spin Quantum Heat Engine.

Developments in the thermodynamics of small quantum systems envisage nonclassical thermal machines. In this scenario, energy fluctuations play a relevant role in the description of irreversibility. We experimentally implement a quantum heat engine based on a spin-1/2 system and nuclear magnetic resonance techniques. Irreversibility at a microscope scale is fully characterized by the assessment of energy fluctuations associated with the work and heat flows. We also investigate the efficiency lag related to the entropy production at finite time. The implemented heat engine operates in a regime where both thermal and quantum fluctuations (associated with transitions among the instantaneous energy eigenstates) are relevant to its description. Performing a quantum Otto cycle at maximum power, the proof-of-concept quantum heat engine is able to reach an efficiency for work extraction (η≈42%) very close to its thermodynamic limit (η=44%).

Inhibition of T-cell activation by the CTLA4-Fc Abatacept is sufficient to ameliorate proteinuric kidney disease.

Diabetic nephropathy (DN) remains an unmet medical challenge as its prevalence is projected to continue to increase and specific medicines for treatment remain undeveloped. Activation of the immune system, in particular T-cells, is emerging as a possible mechanism underlying DN disease progression in humans and animal models. We hypothesized that inhibition of T-cell activation will ameliorate DN. Interaction of B7-1 (CD80) on the surface of antigen presenting cells with its binding partners, CTLA4 (CD152) and CD28 on T-cells, is essential for T-cell activation. In this study we used the soluble CTLA4-Fc fusion protein Abatacept to block cell surface B7-1, preventing the cellular interaction and inhibiting T-cell activation. When Abatacept was dosed in an animal model of diabetes-induced albuminuria, it reduced albuminuria in both prevention and intervention modes. The number of T-cells infiltrating the kidneys of DN animals correlated with the degree of albuminuria, and treatment with Abatacept reduced the number of renal T-cells. As B7-1 induction has been recently proposed to underlie podocyte damage in DN, Abatacept could be efficacious in DN by protecting podocytes. However, this does not appear to be the case as B7-1 was not expressed in 1) kidneys of DN animals; 2) stimulated human podocytes in culture; or 3) glomeruli of DN patients. We conclude that Abatacept ameliorates DN by blocking systemic T-cell activation and not by interacting with podocytes.

Competing Actions of Type 1 Angiotensin II Receptors Expressed on T Lymphocytes and Kidney Epithelium during Cisplatin-Induced AKI.

Inappropriate activation of the renin-angiotensin system (RAS) contributes to many CKDs. However, the role of the RAS in modulating AKI requires elucidation, particularly because stimulating type 1 angiotensin II (AT1) receptors in the kidney or circulating inflammatory cells can have opposing effects on the generation of inflammatory mediators that underpin the pathogenesis of AKI. For example, TNF-α is a fundamental driver of cisplatin nephrotoxicity, and generation of TNF-α is suppressed or enhanced by AT1 receptor signaling in T lymphocytes or the distal nephron, respectively. In this study, cell tracking experiments with CD4-Cre mT/mG reporter mice revealed robust infiltration of T lymphocytes into the kidney after cisplatin injection. Notably, knockout of AT1 receptors on T lymphocytes exacerbated the severity of cisplatin-induced AKI and enhanced the cisplatin-induced increase in TNF-α levels locally within the kidney and in the systemic circulation. In contrast, knockout of AT1 receptors on kidney epithelial cells ameliorated the severity of AKI and suppressed local and systemic TNF-α production induced by cisplatin. Finally, disrupting TNF-α production specifically within the renal tubular epithelium attenuated the AKI and the increase in circulating TNF-α levels induced by cisplatin. These results illustrate discrepant tissue-specific effects of RAS stimulation on cisplatin nephrotoxicity and raise the concern that inflammatory mediators produced by renal parenchymal cells may influence the function of remote organs by altering systemic cytokine levels. Our findings suggest selective inhibition of AT1 receptors within the nephron as a promising intervention for protecting patients from cisplatin-induced nephrotoxicity.

Seascape and life-history traits do not predict self-recruitment in a coral reef fish.

The persistence and resilience of many coral reef species are dependent on rates of connectivity among sub-populations. However, despite increasing research efforts, the spatial scale of larval dispersal remains unpredictable for most marine metapopulations. Here, we assess patterns of larval dispersal in the angelfish Centropyge bicolor in Kimbe Bay, Papua New Guinea, using parentage and sibling reconstruction analyses based on 23 microsatellite DNA loci. We found that, contrary to previous findings in this system, self-recruitment (SR) was virtually absent at both the reef (0.4-0.5% at 0.15 km(2)) and the lagoon scale (0.6-0.8% at approx. 700 km(2)). While approximately 25% of the collected juveniles were identified as potential siblings, the majority of sibling pairs were sampled from separate reefs. Integrating our findings with earlier research from the same system suggests that geographical setting and life-history traits alone are not suitable predictors of SR and that high levels of localized recruitment are not universal in coral reef fishes.

Vascular Type 1A Angiotensin II Receptors Control BP by Regulating Renal Blood Flow and Urinary Sodium Excretion.

Inappropriate activation of the type 1A angiotensin (AT1A) receptor contributes to the pathogenesis of hypertension and its associated complications. To define the role for actions of vascular AT1A receptors in BP regulation and hypertension pathogenesis, we generated mice with cell-specific deletion of AT1A receptors in smooth muscle cells (SMKO mice) using Loxp technology and Cre transgenes with robust expression in both conductance and resistance arteries. We found that elimination of AT1A receptors from vascular smooth muscle cells (VSMCs) caused a modest (approximately 7 mmHg) yet significant reduction in baseline BP and exaggerated sodium sensitivity in mice. Additionally, the severity of angiotensin II (Ang II)-dependent hypertension was dramatically attenuated in SMKO mice, and this protection against hypertension was associated with enhanced urinary excretion of sodium. Despite the lower BP, acute vasoconstrictor responses to Ang II in the systemic vasculature were largely preserved (approximately 80% of control levels) in SMKO mice because of exaggerated activity of the sympathetic nervous system rather than residual actions of AT1B receptors. In contrast, Ang II-dependent responses in the renal circulation were almost completely eliminated in SMKO mice (approximately 5%-10% of control levels). These findings suggest that direct actions of AT1A receptors in VSMCs are essential for regulation of renal blood flow by Ang II and highlight the capacity of Ang II-dependent vascular responses in the kidney to effect natriuresis and BP control.

Regulation of renal NaCl transport by nitric oxide, endothelin, and ATP: clinical implications.

NaCl absorption along the nephron is regulated not just by humoral factors but also by factors that do not circulate or act on the cells where they are produced. Generally, nitric oxide (NO) inhibits NaCl absorption along the nephron. However, the effects of NO in the proximal tubule are controversial and may be biphasic. Similarly, the effects of endothelin on proximal tubule transport are biphasic. In more distal segments, endothelin inhibits NaCl absorption and may be mediated by NO. Adenosine triphosphate (ATP) inhibits sodium bicarbonate absorption in the proximal tubule, NaCl absorption in thick ascending limbs via NO, and water reabsorption in collecting ducts. Defects in the effects of NO, endothelin, and ATP increase blood pressure, especially in a NaCl-sensitive manner. In diabetes, disruption of NO-induced inhibition of transport may contribute to increased blood pressure and renal damage. However, our understanding of how NO, endothelin, and ATP work, and of their role in pathology, is rudimentary at best.

Stem cells: potential and challenges for kidney repair.

Renal damage resulting from acute and chronic kidney injury poses an important problem to public health. Currently, patients with end-stage renal disease rely solely on kidney transplantation or dialysis for survival. Emerging therapies aiming to prevent and reverse kidney damage are thus in urgent need. Although the kidney was initially thought to lack the capacity for self-repair, several studies have indicated that this might not be the case; progenitor and stem cells appear to play important roles in kidney repair under various pathological conditions. In this review, we summarize recent findings on the role of progenitor/stem cells on kidney repair as well as discuss their potential as a therapeutic approach for kidney diseases.

[Lipid formulations of amphotericin]. / Formas lipídicas de anfotericina.

Amphotericin B deoxycholate use has increased during the past years in parallel with the increase in the number of immunosuppressed patients suffering invasive fungal infections. This drug is associated with a high rate of side effects, especially renal toxicity. Lipid formulations (liposomal, lipid complex, colloidal suspension and the Indian liposomal formulation) have been developed, which share the same antifungal spectrum but differ in efficacy and toxicity. A review of amphotericin lipid formulations is presented, focusing on differences in efficacy and, especially renal toxicity. The main problem for use of these formulations in Latin America is their highcost.

The Impact of Mentoring on Academic Career Success in Surgical Subspecialties: A Systematic Review.

INTRODUCTION: As of 2019, women comprise 52.4% of medical school matriculants, make up more than one-third of the active physician workforce, and nearly half of residents and fellows. Although the number of women physicians continues to increase, many surgical subspecialities, including orthopaedic surgery, have not seen a substantial increase in the percentage of women physicians. This may be due to a lack of mentorship. Efforts within the medical community to decrease the burden of gender bias on women include attempts to increase access to mentorship opportunities. Effective mentoring is a critical aspect of any resident physician's training. The purpose of this study was to analyze the most important aspects of mentorship in the academic advancement of female surgical subspecialists. METHODS: A systematic review of the literature was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in July 2022 using the electronic databases PubMed, EMBASE, Cochrane Database, Scopus, and Web of Science.10 Search terms can be found in Appendix 1. An initial abstract screen of each article was conducted by 3 authors. Studies were included if they focused on mentorship of women in academic surgery, were published from 2000-2023, were peer-reviewed articles in the English language, and conducted in the United States. Two reviewers screened each article based on the criteria; the remaining studies were then reviewed in full text. After the full text screen, the eligible articles underwent data extraction and quality assessment using AXIS tool or CASP checklist. The results were then analyzed and synthesized. Additionally, risk of bias was assessed using the 2018 version of the Mixed Methods Appraisal Tool (MMAT). RESULTS: Several common themes among the 10 studies were identified. Six (60%) studies discussed the impact of mentorship on career success. One of the most important ways that mentors assist mentees is by serving as positive role models. Two (20%) studies noted that goal-setting assistance is one of the most helpful ways mentors can provide guidance. Guidance with academic politics (such as funding and research priorities) was identified as a major contribution by mentors in two (20%) studies. The second most common theme was female mentors (6; 60%). Most studies (9; 90%) agree that it's important for women surgeons to have female mentors. The importance of multiple mentors was explored in 4 (40%) papers. Three (30%) studies addressed the issue of balancing work and life responsibilities among female surgeons. CONCLUSION: This review suggests that female surgical subspecialists value mentorship in regard to career development, managing work-life balance, and academic productivity. Although many studies found that female physicians were more likely to express the desire for a same-sex mentor, these female subspecialists were also more likely to report not only a lack of mentorship but a lack of available female mentors. Effective mentoring from multiple mentors, preferably some of whom identify as female, may improve career advancement in female surgical subspecialists and promote gender equality in these fields. More research is needed to establish a baseline of knowledge on how mentoring specifically affects quantitative aspects of career development, such as research productivity and promotions, to continue to equilibrate these historically male-dominated subspecialities.

Survival benefits of extensive surgery in patients with papillary thyroid microcarcinoma.

BACKGROUND: Despite the guidelines recommending thyroid lobectomy, many papillary thyroid microcarcinoma (PTMC) patients still undergo total thyroidectomy. PTMC's optimal treatment remains unclear. We aimed to determine whether total thyroidectomy improves outcomes compared to less extensive surgery. METHODS: We analyzed 6064 PTMC adult patients from the Surveillance, Epidemiology, and End Results (SEER) database (2000-2019) who underwent either total thyroidectomy (n â€‹= â€‹3652) or less extensive surgery (n â€‹= â€‹2412). Endpoints were overall survival, cancer-specific survival, and recurrence. RESULTS: Total thyroidectomy patients had a 5.2 â€‹% mortality rate versus 8.1 â€‹% with less extensive surgery. Recurrence occurred in 1 (0.03 â€‹%) total thyroidectomy patient compared to 24 (1.0 â€‹%) less extensive surgery patients (HR 0.07, p â€‹= â€‹0.01). Median survival was 8.1 years for total thyroidectomy versus 8.8 years for less extensive surgery. Overall survival favored total thyroidectomy (p â€‹= â€‹0.001) but cancer-specific survival did not differ. CONCLUSION: Although total thyroidectomy may not improve cancer-specific survival, it lowers recurrence risk and confers an overall survival advantage for PTMC patients. These findings may help guide surgical decisions.

Radioactive iodine ablation therapy reduces the risk of recurrent disease in pediatric differentiated thyroid carcinoma.

BACKGROUND: While radioactive iodine (RAI) therapy in older adults with differentiated thyroid carcinoma (DTC) reduces recurrence, data in pediatrics remain limited. We conducted a meta-analysis to quantify outcomes and recurrence risk with RAI versus thyroidectomy alone in the pediatric population. METHODS: Systematic literature review identified 34 retrospective studies including 2913 DTC patients under age 22 years (published 2005-2023). Meta-analysis calculated pooled rates of disease persistence and recurrence. Relative risk ratios compared odds of recurrence with RAI versus no RAI. RESULTS: Patients had mean age 14.7 years (95 % CI, 14.2-15.2) and were 75.9 % female (95 % CI, 73.8-78.1 %). Majority (90.2 %) received RAI. Pooled persistence rate was 30.3 % (95 % CI, 21.7-39.5 %); higher with RAI (31.5 %; 95 % CI, 22.4-41.3 %) than no RAI (4.5 %; 95 % CI, 0.0-18.7 %) (OR 3.28; 95 % CI,1.82-5.91; p < 0.001). Recurrence rate was 8.97 % (95 % CI, 4.78-14.3 %). Those with RAI had 53.1 % lower recurrence risk versus no RAI (RR 0.47; 95 % CI, 0.27-0.82; p = 0.007). Median follow-up was 7.2 years (95 % CI, 5.8-8.5 years), with no association between follow-up duration and recurrence (r = -0.053; p = 0.80). CONCLUSIONS: RAI therapy as an adjunct to thyroidectomy is associated with a significantly lower risk of long-term recurrence in pediatric DTC. These findings advocate for the use of RAI in preventing recurrence among high-risk pediatric patients with DTC.

Risk Factors for Postoperative Infections Following Appendectomy of Complicated Appendicitis: A Meta-analysis and Retrospective Single-institutional Study.

Patients with complicated appendicitis have an increased risk for postoperative infections. Potential risk factors for postoperative infections through a meta-analysis and retrospective chart review are discussed. A meta-analysis consisting of 35 studies analyzing complicated appendicitis treated with an appendectomy noting at least 1 postoperative infection was performed. A retrospective review was then conducted in patients diagnosed with complicated appendicitis after appendectomy. Of 5326 patients in total, 15.4% developed postoperative infections. Laparoscopic surgery and perioperative hyperoxygenation were found to be protective factors for the development of infection. Retrospectively, 53.2% of patients presented with complicated appendicitis. Patients with complicated appendicitis were more likely to be older in age and have an increased length of stay. Patient demographics, operative time, and comorbid status had no effect on postoperative infection or readmission rate. Physicians should strongly consider minimally invasive techniques to treat all cases of complicated appendicitis irrespective of comorbidities, age, sex, or body mass index.

Modeling methyl-sensitive transcription factor motifs with an expanded epigenetic alphabet.

BACKGROUND: Transcription factors bind DNA in specific sequence contexts. In addition to distinguishing one nucleobase from another, some transcription factors can distinguish between unmodified and modified bases. Current models of transcription factor binding tend not to take DNA modifications into account, while the recent few that do often have limitations. This makes a comprehensive and accurate profiling of transcription factor affinities difficult. RESULTS: Here, we develop methods to identify transcription factor binding sites in modified DNA. Our models expand the standard A/C/G/T DNA alphabet to include cytosine modifications. We develop Cytomod to create modified genomic sequences and we also enhance the MEME Suite, adding the capacity to handle custom alphabets. We adapt the well-established position weight matrix (PWM) model of transcription factor binding affinity to this expanded DNA alphabet. Using these methods, we identify modification-sensitive transcription factor binding motifs. We confirm established binding preferences, such as the preference of ZFP57 and C/EBPß for methylated motifs and the preference of c-Myc for unmethylated E-box motifs. CONCLUSIONS: Using known binding preferences to tune model parameters, we discover novel modified motifs for a wide array of transcription factors. Finally, we validate our binding preference predictions for OCT4 using cleavage under targets and release using nuclease (CUT&RUN) experiments across conventional, methylation-, and hydroxymethylation-enriched sequences. Our approach readily extends to other DNA modifications. As more genome-wide single-base resolution modification data becomes available, we expect that our method will yield insights into altered transcription factor binding affinities across many different modifications.

Anemonefishes: A model system for evolutionary genomics.

Anemonefishes are an iconic group of coral reef fish particularly known for their mutualistic relationship with sea anemones. This mutualism is especially intriguing as it likely prompted the rapid diversification of anemonefish. Understanding the genomic architecture underlying this process has indeed become one of the holy grails of evolutionary research in these fishes. Recently, anemonefishes have also been used as a model system to study the molecular basis of highly complex traits such as color patterning, social sex change, larval dispersal and life span. Extensive genomic resources including several high-quality reference genomes, a linkage map, and various genetic tools have indeed enabled the identification of genomic features controlling some of these fascinating attributes, but also provided insights into the molecular mechanisms underlying adaptive responses to changing environments. Here, we review the latest findings and new avenues of research that have led to this group of fish being regarded as a model for evolutionary genomics.