SIRT1 activates MAO-A in the brain to mediate anxiety and exploratory drive.

SIRT1 is a NAD(+)-dependent deacetylase that governs a number of genetic programs to cope with changes in the nutritional status of cells and organisms. Behavioral responses to food abundance are important for the survival of higher animals. Here we used mice with increased or decreased brain SIRT1 to show that this sirtuin regulates anxiety and exploratory drive by activating transcription of the gene encoding the monoamine oxidase A (MAO-A) to reduce serotonin levels in the brain. Indeed, treating animals with MAO-A inhibitors or selective serotonin reuptake inhibitors (SSRIs) normalized anxiety differences between wild-type and mutant animals. SIRT1 deacetylates the brain-specific helix-loop-helix transcription factor NHLH2 on lysine 49 to increase its activation of the MAO-A promoter. Both common and rare variations in the SIRT1 gene were shown to be associated with risk of anxiety in human population samples. Together these data indicate that SIRT1 mediates levels of anxiety, and this regulation may be adaptive in a changing environment of food availability.

SIRT1 suppresses beta-amyloid production by activating the alpha-secretase gene ADAM10.

A hallmark of Alzheimer's disease (AD) is the accumulation of plaques of Abeta 1-40 and 1-42 peptides, which result from the sequential cleavage of APP by the beta and gamma-secretases. The production of Abeta peptides is avoided by alternate cleavage of APP by the alpha and gamma-secretases. Here we show that production of beta-amyloid and plaques in a mouse model of AD are reduced by overexpressing the NAD-dependent deacetylase SIRT1 in brain, and are increased by knocking out SIRT1 in brain. SIRT1 directly activates the transcription of the gene encoding the alpha-secretase, ADAM10. SIRT1 deacetylates and coactivates the retinoic acid receptor beta, a known regulator of ADAM10 transcription. ADAM10 activation by SIRT1 also induces the Notch pathway, which is known to repair neuronal damage in the brain. Our findings indicate SIRT1 activation is a viable strategy to combat AD and perhaps other neurodegenerative diseases.

Antibody Status, Disease History, and Incidence of SARS-CoV-2 Infection Among Patients on Chronic Dialysis.

BACKGROUND: Although reinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is rare among individuals with few coronavirus disease 2019 (COVID-19) risk factors, the ability of naturally acquired immunity to prevent reinfection among patients with ESKD is not known. METHODS: This prospective study was conducted among adults with ESKD treated with in-center hemodialysis (ICHD) in the United States. Exposure was ascribed on the basis of the presence or absence of IgG against SARS-CoV-2 at baseline, and separately, a history of documented COVID-19 before study entry. Outcomes were assessed after an infection-free period, and were any SARS-CoV-2 infection (i.e., detected by protocolized PCR tests or during routine clinical surveillance), and clinically manifest COVID-19 (consisting of only the latter). RESULTS: Of 2337 consented participants who met study inclusion criteria, 9.5% were anti-SARS-CoV-2 IgG positive at baseline; 3.6% had a history of COVID-19. Over 6679 patient-months of follow-up, 263 participants had evidence of any SARS-CoV-2 infection, including 141 who had clinically manifest COVID-19. Presence of anti-SARS-CoV-2 IgG (versus its absence) at baseline was associated with lower risk of any SARS-CoV-2 infection (incidence rate ratio, 0.55; 95% confidence interval, 0.32 to 0.95) and clinically manifest COVID-19 0.21 (95% confidence interval, 0.07 to 0.67). CONCLUSION: Among patients with ESKD, naturally acquired anti-SARS-CoV-2 IgG positivity is associated with a 45% lower risk of subsequent SARS-CoV-2 infection, and a 79% lower risk of clinically manifest COVID-19. Because natural immunity is incomplete, patients with ESKD should be prioritized for SARS-CoV-2 vaccination, independent of their COVID-19 disease history.

Correction to: Use of the KDQOL-36™ for assessment of health-related quality of life among dialysis patients in the United States.

Following publication of the original article [1], the authors reported an error in Figs. 3 and S3.

Response to correspondence from Hays and colleagues concerning our paper entitled, use of the KDQOL-36™ for assessment of health-related quality of life among dialysis patients in the United States.

In their correspondence, Hays et al. raise two main critiques of our recently published article entitled "Use of the KDQOL-36™ for assessment of health-related quality of life among dialysis patients in the United States." First, Hays et al. expressed concerns regarding the comparison of mean scores on five Kidney Disease Quality of Life (KDQOL) subscales, given that the Physical Component Summary (PCS) and Mental Component Summary (MCS) are scored on a different numeric scale compared to the other three subscales. Second, Hays et al. note that the correlations reported in our manuscript between the general health perceptions item ("In general, would you say your health is excellent, very good, good, fair, or poor") and the 5 KDQOL subscales were inconsistent with findings derived from other KDQOL datasets. Here, we respond to these two critiques.

Use of the KDQOL-36™ for assessment of health-related quality of life among dialysis patients in the United States.

BACKGROUND: Health-related quality of life (HRQOL) is a key outcome for dialysis patients, and its assessment is mandated by the Centers for Medicaid and Medicare Services. The Kidney Disease Quality of Life (KDQOL-36™) survey is widely used for this assessment. KDQOL-36™ completion rates, and the distributions of scores and item responses, have not been examined in a large, nationally representative cohort of dialysis patients. METHODS: This retrospective, observational study considered 413,951 survey opportunities contributed by adult patients who received dialysis at a large dialysis organization in the United States during calendar years 2014, 2015, and 2016 and were not Veterans Affairs beneficiaries. RESULTS: During the study period, 240,343 unique patients completed a total of 330,412 surveys (overall completion rate 79.8%). Mean domain scores on the physical component summary (PCS), mental component summary (MCS), burden of kidney disease (BKD), symptoms and problems of kidney disease (SPKD), and effects of kidney disease (EKD) subscales were 36.6, 49.0, 51.3, 78.1, and 73.0, respectively. Scores were similar across dialysis modalities. Patient perceptions of general health were not correlated (R < 0.05) with PCS or SPKD. The SPKD showed ceiling effects: among patients treated with in-center hemodialysis, for all 12 items, < 10% of patients were "extremely bothered," while > 65% of patients reported being "not at all" or only "somewhat bothered;" for 3 items, > 85% of patients gave these latter two responses. Interdialytic weight gain was not correlated with patient-reported shortness of breath, PCS, or SPKD. CONCLUSIONS: Survey completion rates for the KDQOL-36™ were high, and scores were similar across dialysis modalities. Ceiling effects were observed for SPKD. Revision of the KDQOL-36™ to address factors that are most important to contemporary dialysis patients may be warranted.

The Impact of Midodrine on Outcomes in Patients with Intradialytic Hypotension.

BACKGROUND: Intradialytic hypotension (IDH) is a frequent complication of hemodialysis, and is associated with significant morbidity and mortality. Off-label use of the alpha-1 andrenergic receptor agonist midodrine to reduce the frequency and severity of IDH is common. However, limited data exist to support this practice. This study sought to examine real-world efficacy of midodrine with respect to relevant clinical and hemodynamic outcomes. METHODS: Here, we compared a variety of clinical and hemodynamic outcomes among adult patients who were prescribed midodrine (n = 1,046) and matched controls (n = 2,037), all of whom were receiving in-center hemodialysis treatment at dialysis facilities in the United States (July 2015 - September 2016). Mortality, all-cause hospitalization, cardiovascular hospitalization, and hemodynamic outcomes were considered from the month following the initiation of midodrine (or corresponding month for controls) until censoring for discontinuation of dialysis, transplant, loss to follow-up, or study end (September 30, 2016). Rate outcomes were compared using Poisson models and quantitative outcomes using linear mixed models; all models were adjusted for imbalanced patient characteristics. RESULTS: Compared to non-use, midodrine use was associated with higher rates of death (adjusted incidence rate ratio 1.37, 95% CI 1.15-1.62), all-cause hospitalization (1.31, 1.19-1.43) and cardiovascular hospitalization (1.41, 1.17-1.71). During follow-up, midodrine use tended to be associated with lower pre-dialysis systolic blood pressure (SBP), lower nadir SBP, greater fall in SBP during dialysis, and a greater proportion of treatments affected by IDH. CONCLUSION: Although residual confounding may have influenced the results, the associations observed here are not consistent with a potent beneficial effect of midodrine with respect to either clinical or hemodynamic outcomes.

Turning straw into gold: directing cell fate for regenerative medicine.

Regenerative medicine offers the hope that cells for disease research and therapy might be created from readily available sources. To fulfil this promise, the cells available need to be converted into the desired cell types. We review two main approaches to accomplishing this goal: in vitro directed differentiation, which is used to push pluripotent stem cells, including embryonic stem cells or induced pluripotent stem cells, through steps similar to those that occur during embryonic development; and reprogramming (also known as transdifferentiation), in which a differentiated cell is converted directly into the cell of interest without proceeding through a pluripotent intermediate. We analyse the status of progress made using these strategies and highlight challenges that must be overcome to achieve the goal of cell-replacement therapy.

Neuronal SIRT1 regulates endocrine and behavioral responses to calorie restriction.

Mammalian life span can be extended by both calorie restriction (CR) and mutations that diminish somatotropic signaling. Sirt1 is a mediator of many effects of CR in mammals, but any role in controlling somatotropic signaling has not been shown. Since the somatotropic axis is controlled by the brain, we created mice lacking Sirt1 specifically in the brain and examined the impacts of this manipulation on somatotropic signaling and the CR response. These mutant mice displayed defects in somatotropic signaling when fed ad libitum, and defects in the endocrine and behavioral responses to CR. We conclude that Sirt1 in the brain is a link between somatotropic signaling and CR in mammals.

Brief report: VGLL4 is a novel regulator of survival in human embryonic stem cells.

Human embryonic stem cells (hESCs) are maintained in a self-renewing state by an interconnected network of mechanisms that sustain pluripotency, promote proliferation and survival, and prevent differentiation. We sought to find novel genes that could contribute to one or more of these processes using a gain-of-function screen of a large collection of human open reading frames. We identified Vestigial-like 4 (VGLL4), a cotranscriptional regulator with no previously described function in hESCs, as a positive regulator of survival in hESCs. Specifically, VGLL4 overexpression in hESCs significantly decreases cell death in response to dissociation stress. Additionally, VGLL4 overexpression enhances hESC colony formation from single cells. These effects may be attributable, in part, to a decreased activity of initiator and effector caspases observed in the context of VGLL4 overexpression. Additionally, we show an interaction between VGLL4 and the Rho/Rock pathway, previously implicated in hESC survival. This study introduces a novel gain-of-function approach for studying hESC maintenance and presents VGLL4 as a previously undescribed regulator of this process. Stem Cells 2013;31:2833-2841.

Urgent-start peritoneal dialysis: Association with outcomes.

The majority of end-stage kidney disease (ESKD) patients start dialysis without adequate pre-dialysis planning. Of these patients, the vast majority initiate in-centre haemodialysis using a central venous catheter (ICHD-CVC). A minority utilise urgent-start peritoneal dialysis (USPD), whereby a peritoneal dialysis catheter is placed and used for dialysis without the usual 2-4-week waiting period. In this multicentre, retrospective study of adult patients initiating dialysis during 2018, we compared outcomes among patients utilising these two dialysis initiation routes. Patients who initiated dialysis via ICHD-CVC were matched 1:1 to patients who utilised USPD on the basis of aetiology of ESKD, race, diabetes status and insurance type. Hospitalisation and mortality were evaluated from dialysis initiation through the first of death, transplant, loss to follow-up or study end (30 June 2019). Outcomes were compared using models adjusted for age and sex. A total of 717 USPD patients were matched to ICHD-CVC patients. During follow-up, USPD patients were hospitalised at a rate of 1.21 admissions/patient-year (pt-yr) versus 1.51 admissions/pt-yr for ICHD-CVC. This corresponded to a 24% lower rate of hospitalisation among USPD patients (adjusted incidence rate ratio 0.76, 95% confidence interval [CI] 0.65-0.88). Mortality rates were 0.08 and 0.11 deaths/pt-yr among USPD patients and ICHD-CVC patients, respectively (adjusted hazard ratio 0.84, 95% CI 0.62, 1.15). These findings suggest that more widespread adoption of USPD may be beneficial among patients with limited pre-dialysis planning.

The DXPas34 repeat regulates random and imprinted X inactivation.

X chromosome inactivation (XCI) is initiated by expression of the noncoding Xist RNA in the female embryo. Tsix, the antisense noncoding partner of Xist, serves as its regulator during both imprinted and random XCI. Here, we show that Tsix in part acts through a 34mer repeat, DXPas34. DXPas34 contains bidirectional promoter activity, producing overlapping forward and reverse transcripts. We generate three new Tsix alleles in mouse embryonic stem cells and show that, while the Tsix promoter is unexpectedly dispensable, DXPas34 plays dual positive-negative functions. At the onset of XCI, DXPas34 stimulates Tsix expression through its enhancer activity. Once XCI is established, DXPas34 becomes repressive and stably silences Tsix. Germline transmission of the DXPas34 mutation demonstrates its necessity for both random and imprinted XCI in mice. Intriguingly, sequence analysis suggests that DXPas34 could potentially have descended from an ancient retrotransposon. We hypothesize that DXPas34 was acquired by Tsix to regulate antisense function.

Impact of Rescheduling a Missed Hemodialysis Treatment on Clinical Outcomes.

RATIONALE & OBJECTIVE: Among patients treated with in-center hemodialysis (HD), missed treatments are associated with higher subsequent rates of hospitalization and other adverse outcomes compared with attending treatment. The objective of this study was to determine whether and to what degree attending a rescheduled treatment on the day following a missed treatment ameliorates these risks. STUDY DESIGN: Retrospective, observational. SETTING & PARTICIPANTS: Included patients were those who were, as of any of 12 index dates during 2014, adult Medicare beneficiaries treated with in-center HD (vintage ≥ 90 days) on a Monday/Wednesday/Friday schedule. EXPOSURE: Treatment attendance on the index date and the subsequent day. OUTCOMES: Hospital admissions, emergency department visits, mortality, blood pressure, and anemia measures, considered during the 7- and 30-day periods following exposure. ANALYTICAL APPROACH: In parallel analyses, patients who missed or rescheduled treatment were each matched (1:5) to patients who attended treatment on the index date on the basis of index day of week and propensity score. Within the matched cohorts, outcomes were compared across exposures using repeated-measures generalized linear models. RESULTS: Compared with attending treatment (N = 19,260), a missed treatment (N = 3,852) was associated with a 2.09-fold higher rate of hospitalization in the subsequent 7 days; a rescheduled treatment (N = 2,128) was associated with a 1.68-fold higher rate of hospitalization than attending (N = 10,640). Compared with attending treatment, hospitalization rates were 1.39- and 1.28-fold higher among patients who missed and rescheduled treatment, respectively, during the 30-day outcome period. Emergency department visits followed a similar pattern of associations as hospitalization. No statistically significant associations were observed with respect to mortality for either missed or rescheduled treatments compared with attending treatment. LIMITATIONS: Possible influence of unmeasured confounding; unknown generalizability to patients with non-Medicare insurance. CONCLUSIONS: Attending a rescheduled in-center HD treatment attenuates but does not fully mitigate the adverse effects of a missed treatment.

Association of Chronic Condition Special Needs Plan With Hospitalization and Mortality Among Patients With End-Stage Kidney Disease.

Importance: While several studies have demonstrated the benefit of enrollment in chronic condition special needs plans (C-SNPs) for other chronic diseases (eg, diabetes), there is no evaluation of the association of C-SNPs with outcomes among patients with end-stage kidney disease (ESKD). Objective: To examine whether and to what degree C-SNP enrollment was associated with improved clinical outcomes and quality of life in patients with ESKD. Design, Setting, and Participants: This multicenter cohort study included 2718 patients who were newly enrolled in an ESKD C-SNP between January 1, 2013, and September 30, 2017, and receiving dialysis from DaVita Kidney Care. Patients were followed up until death, loss to follow-up, or end of study (ie, December 31, 2018). Enrollees in C-SNP were matched via multiple clinical and demographic characteristics with 2 different control populations, as follows: (1) those in the same facilities (n = 2545) or (2) those in similar counties (n = 1986). Patients enrolled in CareMore C-SNPs (n = 206) were excluded from the study. Data analysis was conducted June to December 2019. Exposures: Standard ESKD care with dialysis plus access to an integrated care team who worked with the patient and the dialysis team, comprehensive health assessments done by the integrated care team, and access to select benefits (such as vision and dental care) as a C-SNP enrollee. Main Outcomes and Measures: Hospitalizations, mortality, laboratory values indicative of metabolic control, and Kidney Disease Quality of Life 36-item (KDQOL-36) survey scores. Results: The 2545 C-SNP enrollees in the facility-matched analysis had a mean (SD) age of 57.2 (12.9) years, and included 968 (38.0%) women, 1328 (52.2%) Hispanic individuals, and 553 (21.7%) African American individuals. The 1986 C-SNP enrollees in the county-matched analysis had a mean (SD) age of 57.8 (12.2) years, with 705 (35.5%) women, 1085 (54.6%) Hispanic individuals, and 472 (23.8%) African American individuals. Compared with patients not enrolled in C-SNP, enrollees had lower hospitalization rates, with incidence rate ratios of 0.90 (95% CI, 0.84-0.97; P = .006) in the facility-matched analysis and 0.76 (95% CI, 0.70-0.83; P < .001) in the county-matched analysis. Compared with patients not enrolled in C-SNP, enrollees had decreased mortality risk in the same facilities (hazard ratio, 0.77; 95% CI, 0.68-0.88; P < .001) and in the same counties (hazard ratio, 0.77; 95% CI, 0.66-0.88; P < .001). No significant differences were observed between C-SNP enrollees and matched patients in metabolic laboratory values or KDQOL-36 survey scores. Conclusions and Relevance: This cohort study found a positive association of C-SNP enrollment with lower rates of hospitalization and mortality. The findings suggest that the additional services and benefits C-SNPs provide may improve outcomes compared with standard of care for patients with ESKD.

Higher order chromatin structure at the X-inactivation center via looping DNA.

In mammals, the silencing step of the X-chromosome inactivation (XCI) process is initiated by the non-coding Xist RNA. Xist is known to be controlled by the non-coding Xite and Tsix loci, but the mechanisms by which Tsix and Xite regulate Xist are yet to be fully elucidated. Here, we examine the role of higher order chromatin structure across the 100-kb region of the mouse X-inactivation center (Xic) and map domains of specialized chromatin in vivo. By hypersensitive site mapping and chromosome conformation capture (3C), we identify two domains of higher order chromatin structure. Xite makes looping interactions with Tsix, while Xist makes contacts with Jpx/Enox, another non-coding gene not previously implicated in XCI. These regions interact in a developmentally-specific and sex-specific manner that is consistent with a regulatory role in XCI. We propose that dynamic changes in three-dimensional architecture leads to formation of separate chromatin hubs in Tsix and Xist that together regulate the initiation of X-chromosome inactivation.

Safety and efficacy of heparin during dialysis in the context of systemic anticoagulant and antiplatelet medications.

Heparin is widely used to prevent coagulation during hemodialysis. Although systemic anticoagulants and antiplatelet agents are commonly prescribed in the hemodialysis population, the safety and efficacy of heparin in the presence of these medications is unclear. This retrospective cohort study considered adult hemodialysis patients treated in the United States (August 2015-July 2017). For each month, patients were ascribed a three-part exposure status (heparin use, anticoagulant use, antiplatelet agent use) based on electronic health records. Outcomes included anemia measures, peri-treatment bleeding and clotting, and hospitalization for gastrointestinal (GI) bleeding. Within systemic medication exposure categories, associations of heparin use were examined using adjusted generalized linear, negative binomial, or Poisson models. Across all systemic medication exposures, heparin use was associated with lower erythropoiesis stimulating agent (ESA) dose, higher hemoglobin levels, and lower monthly intravenous (IV) iron dose; lower rates of clotting during treatment and hospitalization for GI bleeding; and similar rates of peri-treatment bleeding. Associations with respect to ESA, IV iron, hemoglobin, and clotting were approximately twofold more potent in the absence of a systemic anticoagulant; the presence of an antiplatelet agent had little impact. Neither medication type influenced associations between heparin use and peri-treatment or GI bleeding. These results suggest that heparin use is safe and effective in the presence and absence of systemic anticoagulants and antiplatelet agents. Clinical judgment must be applied to assess bleeding risk in individual patients; however, the decision to withhold heparin should not solely be based upon the concurrent use of anticoagulant or antiplatet agents.

X-chromosome inactivation and the search for chromosome-wide silencers.

X-chromosome inactivation leads to divergent fates for two homologous chromosomes. Whether one X remains active or becomes silenced depends on the activity of Xist, a gene expressed only from the inactive X and whose RNA product 'paints' the X in cis. Recent work argues that Xist RNA itself is the acting agent for initiating the silencing step. Xist RNA contains separable domains for RNA localization and chromosome silencing. While no Xist RNA-interacting factors have been identified, a growing collection of chromatin alterations have been identified on the inactive X, including variant histone H2A composition and histone H3 methylation. Some or all of these changes may be critical for chromosome-wide silencing. As none of the silencing proteins identified so far is unique to X chromosome inactivation, the specificity must partly reside in Xist RNA whose spread along the X orchestrates general silencing factors for this specific task.

Dialysate temperature of 36 °C: association with clinical outcomes.

Dialysate cooling, either individualized based upon patient body temperature, or to a standardized temperature below 37 °C, has been proposed to minimize hemodynamic insults and improve outcomes among hemodialysis patients. However, low dialysate temperatures (35-35.5 °C) are associated with patient discomfort, and individualized dialysate cooling is difficult to operationalize. Here, we tested whether a standardized dialysate temperature of 36 °C (dT36) was associated with improved clinical outcomes compared to the default temperature of 37 °C (dT37). Because patients with known hemodynamic instability may be selectively prescribed dT36, we minimized selection bias by considering only incident adult in-center hemodialysis patients who, between Jan 2011 and Dec 2013 received their first-ever hemodialysis treatment at a large dialysis organization. Exposure status was based on the treatment order for this first-ever treatment. 313 dT36 patients were identified and propensity-score matched (1:5) to 1565 dT37 controls. Death, hospitalization, and missed hemodialysis treatments were considered from the date of first-ever hemodialysis treatment until the earliest of death, loss to follow-up, crossover (month in which prescribed dialysate temperature was consistent with patient's exposure group for <80% of treatments), or study end (June 2015). During follow-up, rates of death, hospitalization and missed hemodialysis treatments did not differ between the two groups. This study therefor showed no benefit of dT36 vs. dT37 with respect to these clinical outcomes. Our results do not favor conversion to a default dialysate temperature of 36 °C. Individualized dialysate cooling may provide a more reliable approach to achieve the hemodynamic benefits associated with reduced dialysate temperature.

Vocational activity and health insurance type among patients with end-stage renal disease: association with outcomes.

It is widely thought that patients with end-stage renal disease who remain vocationally active and/or commercially insured following dialysis initiation have better clinical outcomes and higher quality of life than those who do not. However, scientifically robust data are lacking. Here, we examined whether vocational status (active, N = 1848; inactive, N = 10,001) and, separately, insurance status (commercial, N = 4858; Medicare/self-pay, N = 13,329; Medicaid, N = 3528) were associated with clinical outcomes and Kidney Disease Quality of Life (KDQOL) scores among a cohort of patients who initiated dialysis at a large US dialysis organization during 2015-2016. Outcomes were considered from the day after index (31 days after dialysis initiation for vocational status and 1 day after initiation for insurance status) until the earliest of death, discontinuation of dialysis, transplant, loss to follow-up, or end of study (30 September 2016). Comparisons were made using intention-to-treat principles and generalized linear models adjusted for imbalanced patient characteristics, including sociodemographic variables. Vocational inactivity (vs. vocational activity) was independently associated with higher rates of mortality and hospitalization, lower rates of transplant, and lower KDQoL scores in 4 of 5 domains. Similar trends were observed when comparing Medicare/self-pay or Medicaid insurance to commercial insurance. Vocational activity, and separately, commercial insurance, were independently associated with better clinical and quality of life outcomes compared to other insurance and vocational categories. These findings may inform patient and physician education, and guide advocacy efforts.