Incidence and risk factors of acute kidney injury among childhood nephrotic syndrome: a prospective cohort study.

Acute kidney injury (AKI) is a known independent risk factor for morbidity/mortality but there is scarcity of robust data on it among childhood nephrotic syndrome (NS). We assessed the incidence of AKI among hospitalized children with NS as well as looked for any significant risk factors. Prospective observational study conducted across two tertiary pediatric hospitals in Eastern India from September 2020 to August 2021. Children aged 1-18 years admitted with NS and without any nephritic features or pre-existing chronic kidney disease (CKD) were included. In 200 admissions (n = 176; 63% female, median age 4 years [IQR: 3-7]), AKI occurred in 36 (18%; 95% CI 13 to 36%). Two children required kidney replacement therapy and one death was recorded. In 27/36 (75%), AKI resolved within 48 h, 4 had persistent AKI, 3 acute kidney disease, and two progressed to CKD. On multivariate regression analysis: fractional excretion of sodium ≤ 0.2% (OR 12.77; 95% CI 3.5-46.4), male gender (OR 6.38; 95% CI 2.76-14.74), underlying infection (OR 5.44; 95% CI 2.4-11.86), nephrotoxic drugs (OR 4.83; 95% CI 2.21-10.54), and albumin ≤ 1.4 g/dl (OR 4.35; 95% CI 1.55-12.8) were associated with AKI. A predictive equation using these five variables on admission had high AUC (0.86) in correctly identifying 17 children who subsequently developed AKI.   Conclusion: In a low resource setting, AKI is common among hospitalized children with NS. Larger multi-center prospective studies are needed to refine prediction equations and test its utility in preventing AKI development. What is Known: • Acute Kidney Injury is a known independent risk factor for increased morbidity and mortality. • There are few studies to assess the incidence of Acute kidney injury in hospitalised cases of childhood nephrotic syndrome.. What is New: • This is the largest prospective cohort of children suffering from nephrotic syndrome, in India, proposing a novel algorithm for predicting the risk of AKI among hospitalised cases of childhood nephrotic syndrome.

SYNPLA, a method to identify synapses displaying plasticity after learning.

Which neural circuits undergo synaptic changes when an animal learns? Although it is widely accepted that changes in synaptic strength underlie many forms of learning and memory, it remains challenging to connect changes in synaptic strength at specific neural pathways to specific behaviors and memories. Here we introduce SYNPLA (synaptic proximity ligation assay), a synapse-specific, high-throughput, and potentially brain-wide method capable of detecting circuit-specific learning-induced synaptic plasticity.

Topoisomerase I alone is sufficient to produce short DNA deletions and can also reverse nicks at ribonucleotide sites.

Ribonucleotide monophosphates (rNMPs) are among the most frequent form of DNA aberration, as high ratios of ribonucleotide triphosphate:deoxyribonucleotide triphosphate pools result in approximately two misincorporated rNMPs/kb of DNA. The main pathway for the removal of rNMPs is by RNase H2. However, in a RNase H2 knock-out yeast strain, a topoisomerase I (Top1)-dependent mutator effect develops with accumulation of short deletions within tandem repeats. Proposed models for these deletions implicated processing of Top1-generated nicks at rNMP sites and/or sequential Top1 binding, but experimental support has been lacking thus far. Here, we investigated the biochemical mechanism of the Top1-induced short deletions at the rNMP sites by generating nicked DNA substrates bearing 2',3'-cyclic phosphates at the nick sites, mimicking the Top1-induced nicks. We demonstrate that a second Top1 cleavage complex adjacent to the nick and subsequent faulty Top1 religation led to the short deletions. Moreover, when acting on the nicked DNA substrates containing 2',3'-cyclic phosphates, Top1 generated not only the short deletion, but also a full-length religated DNA product. A catalytically inactive Top1 mutant (Top1-Y723F) also induced the full-length products, indicating that Top1 binding independent of its enzymatic activity promotes the sealing of DNA backbones via nucleophilic attacks by the 5'-hydroxyl on the 2',3'-cyclic phosphate. The resealed DNA would allow renewed attempt for repair by the error-free RNase H2-dependent pathway in vivo. Our results provide direct evidence for the generation of short deletions by sequential Top1 cleavage events and for the promotion of nick religation at rNMP sites by Top1.

NAD: a master regulator of transcription.

Cellular processes such as proliferation, differentiation and death are intrinsically dependent upon the redox status of a cell. Among other indicators of redox flux, cellular NAD(H) levels play a predominant role in transcriptional reprogramming. In addition to this, normal physiological functions of a cell are regulated in response to perturbations in NAD(H) levels (for example, due to alterations in diet/metabolism) to maintain homeostatic conditions. Cells achieve this homeostasis by reprogramming various components that include changes in chromatin structure and function (transcription). The interdependence of changes in gene expression and NAD(H) is evolutionarily conserved and is considered crucial for the survival of a species (by affecting reproductive capacity and longevity). Proteins that bind and/or use NAD(H) as a co-substrate (such as, CtBP and PARPs/Sirtuins respectively) are known to induce changes in chromatin structure and transcriptional profiles. In fact, their ability to sense perturbations in NAD(H) levels has been implicated in their roles in development, stress responses, metabolic homeostasis, reproduction and aging or age-related diseases. It is also becoming increasingly clear that both the levels/activities of these proteins and the availability of NAD(H) are equally important. Here we discuss the pivotal role of NAD(H) in controlling the functions of some of these proteins, the functional interplay between them and physiological implications during calorie restriction, energy homeostasis, circadian rhythm and aging.

Corticostriatal Plasticity Established by Initial Learning Persists after Behavioral Reversal.

The neural mechanisms that allow animals to adapt their previously learned associations in response to changes in the environment remain poorly understood. To probe the synaptic mechanisms that mediate such adaptive behavior, we trained mice on an auditory-motor reversal task, and tracked changes in the strength of corticostriatal synapses associated with the formation of learned associations. Using a ChR2-based electrophysiological assay in acute striatal slices, we measured the strength of these synapses after animals learned to pair auditory stimuli with specific actions. Here, we report that the pattern of synaptic strength initially established by learning remains unchanged even when the task contingencies are reversed. Our findings reveal that synaptic changes associated with the initial acquisition of this task are not erased or overwritten, and that behavioral reversal of learned associations may recruit a separate neural circuit. These results suggest a more complex role of the striatum in regulating flexible behaviors where activity of striatal neurons may vary given the behavioral contexts of specific stimulus-action associations.

Transparency, health equity, and strategies in state-based protocols for remdesivir allocation and use.

BACKGROUND: The Emergency Use Authorization (EUA) of remdesivir for coronavirus disease 2019 raised questions on transparency of applied strategy, and how to equitably allocate and prioritize eligible patients given limited supply of the medication. The absence of federal oversight highlighted the critical role by states in health policymaking during a pandemic. OBJECTIVE: To identify public state-based protocols for remdesivir allocation and clinical guidance for prioritizing remdesivir use and assess approaches and inclusion of language promoting equitable access or mitigating health disparities. METHODS: We identified remdesivir allocation strategies and clinical use guidelines for all 50 states in the U.S. and the District of Columbia accessible on state health department websites or via internet searches. Public protocols dated between May 1, 2020 and September 30, 2020 were included in the study. We reviewed strategies for allocation and clinical use, including whether protocols contained explicit language on equitable access to remdesivir or mitigating health disparities. RESULTS: A total of 38 states had a remdesivir allocation strategy, with 33 states (87%) making these public. States used diverse allocation strategies, and only 10 (30%) of the 33 states included language on equitable allocation. A total of 30 states had remdesivir clinical use guidelines, where all were publicly accessible. All guidelines referenced recommendations by federal agencies but varied in their presentation format. Of the 30 states, 12 (40%) had guidelines that included language on equitable use. Neither an allocation strategy or clinical use guideline were identified (public or non-public) for 10 states and the District of Columbia during the study period. CONCLUSIONS: The experience with the remdesivir EUA presents an opportunity for federal and state governments to develop transparent protocols promoting fair and equal access to treatments for future pandemics.

Rheological properties of corn stover slurries during fermentation by Clostridium thermocellum.

BACKGROUND: Milling during fermentation, termed cotreatment, has recently been proposed as an alternative to thermochemical pretreatment as a means to increase the accessibility of lignocellulosic biomass to biological attack. A central premise of this approach is that partial solubilization of biomass changes the slurry's physical properties such that milling becomes more impactful and more feasible. A key uncertainty is the energy required to mill partially fermented biomass. To inform both of these issues, we report rheological characterization of small-particle, corn stover slurries undergoing fermentation by Clostridium thermocellum. RESULTS: Fermented and unfermented corn stover slurries were found to be shear-thinning and well described by a power law model with an exponent of 0.10. Plastic viscosity of a slurry, initially at 16 wt.% insoluble solids, decreased as a result of fermentation by a factor of 2000, with the first eightfold reduction occurring in the first 10% of carbohydrate conversion. Large amplitude oscillatory shear experiments revealed only minor changes to the slurry's rheological fingerprint as a result of fermentation, with the notable change being a reduction in the critical strain amplitude needed for the onset of nonlinearity. All slurries were found to be elastoviscoplastic, with the elastic/viscous crossover at roughly 100% strain amplitude. CONCLUSIONS: Whereas prior biomass rheology studies have involved pretreated feedstocks and solubilization mediated by fungal cellulase, we report results for feedstocks with no pretreatment other than autoclaving and for solubilization mediated by C. thermocellum. As observed in prior studies, C. thermocellum fermentation results in a dramatic decrease in viscosity. The magnitude of this decrease, however, is much larger starting with unpretreated feedstock than previously reported for pretreated feedstocks. LAOS measurements provide a detailed picture of the rheological fingerprint of the material. Viscosity measurements confirm the hypothesis that the physical character of corn stover slurries changes dramatically during fermentation by C. thermocellum, and indicate that the energy expended on overcoming slurry viscosity will be far less for partially fermented corn stover than for unfermented corn stover.

ErbB4 regulation of a thalamic reticular nucleus circuit for sensory selection.

Selective processing of behaviorally relevant sensory inputs against irrelevant ones is a fundamental cognitive function whose impairment has been implicated in major psychiatric disorders. It is known that the thalamic reticular nucleus (TRN) gates sensory information en route to the cortex, but the underlying mechanisms remain unclear. Here we show in mice that deficiency of the Erbb4 gene in somatostatin-expressing TRN neurons markedly alters behaviors that are dependent on sensory selection. Whereas the performance of the Erbb4-deficient mice in identifying targets from distractors was improved, their ability to switch attention between conflicting sensory cues was impaired. These behavioral changes were mediated by an enhanced cortical drive onto the TRN that promotes the TRN-mediated cortical feedback inhibition of thalamic neurons. Our results uncover a previously unknown role of ErbB4 in regulating cortico-TRN-thalamic circuit function. We propose that ErbB4 sets the sensitivity of the TRN to cortical inputs at levels that can support sensory selection while allowing behavioral flexibility.

Targeting ABL1-mediated oxidative stress adaptation in fumarate hydratase-deficient cancer.

Patients with germline fumarate hydratase (FH) mutation are predisposed to develop aggressive kidney cancer with few treatment options and poor therapeutic outcomes. Activity of the proto-oncogene ABL1 is upregulated in FH-deficient kidney tumors and drives a metabolic and survival signaling network necessary to cope with impaired mitochondrial function and abnormal accumulation of intracellular fumarate. Excess fumarate indirectly stimulates ABL1 activity, while restoration of wild-type FH abrogates both ABL1 activation and the cytotoxicity caused by ABL1 inhibition or knockdown. ABL1 upregulates aerobic glycolysis via the mTOR/HIF1α pathway and neutralizes fumarate-induced proteotoxic stress by promoting nuclear localization of the antioxidant response transcription factor NRF2. Our findings identify ABL1 as a pharmacologically tractable therapeutic target in glycolytically dependent, oxidatively stressed tumors.

Targeting HIF2α translation with Tempol in VHL-deficient clear cell renal cell carcinoma.

The tumor suppressor gene, Von Hippel-Lindau (VHL), is frequently mutated in the most common form of kidney cancer, clear cell renal cell carcinoma (CCRCC). In hypoxic conditions, or when there is a VHL mutation, the hypoxia inducible factors, HIF1α and HIF2α, are stabilized and transcribe a panel of genes associated with cancer such as vascular endothelial growth factor receptor (VEGFR), platelet derived growth factor (PDGF), and glucose transporter 1 (GLUT1). Recent studies in clear cell kidney cancer have suggested that HIF2α, but not HIF1α, is the critical oncoprotein in the VHL pathway. Therefore, targeting HIF2α could provide a potential therapeutic approach for patients with advanced CCRCC. Since iron regulatory protein 1 (IRP1) is known to inhibit the translation of HIF2α, we investigated whether Tempol, a stable nitroxide that activates IRP1 towards IRE-binding, might have a therapeutic effect on a panel of human CCRCC cells expressing both HIF1α and HIF2α. We first evaluated the protein expression of HIF1α and HIF2α in 15 different clear cell renal carcinoma cell lines established from patient tumors in our laboratory. Tempol decreased the expression of HIF2α, and its downstream targets in all the cell lines of the panel. This effect was attributed to a dramatic increase of IRE-binding activity of IRP1. Several cell lines were found to have an increased IRP1 basal activity at 20% O2 compared to 5% O2, which may lower HIF2α expression in some of the cell lines in a VHL-independent manner. Taken together our data identify Tempol as an agent with potential therapeutic activity targeting expression of HIF2α in VHL-deficient clear cell kidney cancer and illustrate the importance of studying biochemical processes at relevant physiological O2 levels.

Sirt1 and mir-9 expression is regulated during glucose-stimulated insulin secretion in pancreatic ß-islets.

MicroRNA mir-9 is speculated to be involved in insulin secretion because of its ability to regulate exocytosis. Sirt1 is an NAD-dependent protein deacetylase and a critical factor in the modulation of cellular responses to altered metabolic flux. It has also been shown recently to control insulin secretion from pancreatic ß-islets. However, little is known about the regulation of Sirt1 and mir-9 levels in pancreatic ß-cells, particularly during glucose-dependent insulin secretion. In this article, we report that mir-9 and Sirt1 protein levels are actively regulated in vivo in ß-islets during glucose-dependent insulin secretion. Our data also demonstrates that mir-9 targets and regulates Sirt1 expression in insulin-secreting cells. This targeting is relevant in pancreatic ß-islets, where we show a reduction in Sirt1 protein levels when mir-9 expression is high during glucose-dependent insulin secretion. This functional interplay between insulin secretion, mir-9 and Sirt1 expression could be relevant in diabetes. It also highlights the crosstalk between an NAD-dependent protein deacetylase and microRNA in pancreatic ß-cells.