Chromogranin A in uremia: Progressive retention of immunoreactive fragments

Chromogranin A in uremia: Progressive retention of immunoreactive fragments. Chromogranin A is a soluble protein that is stored and released with catecholamines from their secretory vesicles. Its measurement is a probe of exocytotic sympathoadrenal activity, and in plasma it may also be a useful tool in the diagnosis of peptide producing endocrine neoplasms. Because we have found that chromogranin A is elevated in secondary (uremic) hyperparathyroidism, we systematically investigated the influence of renal dysfunction and its attendant hyperparathyroidism on chromogranin A in several subject groups: normal controls (serum creatinine≤1.2 mg/dl), nonazotemic renal transplant recipients, nonazotemic subjects with glomerular disease (serum creatinine between 1.2 and 2 mg/dl), mid-range renal disease subjects (serum creatinine between 2 and 7.5 mg/dl), and end-stage renal disease subjects (serum creatinine <7.5 mg/dl). Plasma chromogranin A rose with deterioration of renal function, and the rise was independent of etiologic diagnosis, blood pressure, or indices of sympathoadrenal activity or hyperparathyroidism. Size fractionation of uremic plasma by gel filtration, and immunoextraction by region-specific anti-chromo-granin A (anti-N-terminal, anti-C-terminal, and antimid-molecule) antibodies suggested that chromogranin A immunoreactivity circulates in uremia as lower molecular weight fragments of the parent chromogranin A molecule, with mid-molecule fragments the major constituent. This immunoreactivity is only minimally removed by peritoneal dialysis and is not at all hemodialyzable. The uremia-dose-dependent accumulation of chromogranin A immunoreactive fragments in renal failure suggests that the kidney is a major site of disposition or removal of the immunoreactivity. Furthermore, lack of detectable chromogranin A immunoreactivity in normal subjects' urine suggests that the immunoreactivity is destroyed as it is removed by the kidney. We conclude that plasma chromogranin A increases in proportion to degree of renal insufficiency and that renal function must therefore be controlled when using plasma chromogranin A in the investigation of amine or peptide hormone storage and release

Genome-wide association of sleep and circadian phenotypes

BACKGROUND: Numerous studies suggest genetic influences on sleepiness and circadian rhythms. The Sleep Heart Health Study collected questionnaire data on sleep habits and sleepiness from 2848 Framingham Heart Study Offspring Cohort participants. More than 700 participants were genotyped using the Affymetrix 100K SNP GeneChip, providing a unique opportunity to assess genetic linkage and association of these traits. METHODS: Sleepiness (defined as the Epworth Sleepiness Scale score), usual bedtime and usual sleep duration were assessed by self-completion questionnaire. Standardized residual measures adjusted for age, sex and BMI were analyzed. Multipoint variance components linkage analysis was performed. Association of SNPs to sleep phenotypes was analyzed with both population-based and family-based association tests, with analysis limited to 70,987 autosomal SNPs with minor allele frequency ≥10%, call rate ≥80%, and no significant deviation from Hardy-Weinberg equilibrium (p ≥ 0.001). RESULTS: Heritability of sleepiness was 0.29, bedtime 0.22, and sleep duration 0.17. Both genotype and sleep phenotype data were available for 749 subjects. Linkage analysis revealed five linkage peaks of LOD >2: four to usual bedtime, one to sleep duration. These peaks include several candidate sleep-related genes, including CSNK2A2, encoding a known component of the circadian molecular clock, and PROK2, encoding a putative transmitter of the behavioral circadian rhythm from the suprachiasmatic nucleus. Association tests identified an association of usual bedtime with a non-synonymous coding SNP in NPSR1 that has been shown to encode a gain of function mutation of the neuropeptide S receptor, whose endogenous ligand is a potent promoter of wakefulness. Each copy of the minor allele of this SNP was associated with a 15 minute later mean bedtime. The lowest p value was for association of sleepiness with a SNP located in an intron of PDE4D, which encodes a cAMP-specific phosphodiesterase widely expressed in human brain. Full association results are posted at. CONCLUSION: This analysis confirms prior reports of significant heritability of sleepiness, usual bedtime, and usual sleep duration. Several genetic loci with suggestive linkage to these traits are identified, including linkage peaks containing circadian clock-related genes. Association tests identify NPSR1 and PDE4D as possible mediators of bedtime and sleepiness.National Heart, Lung, and Blood Institute's Framingham Heart Study (N01-HC 25195); National Heart, Lung, and Blood Institute;s Sleep Heart Study (U01 HL53941); National Institutes of Health National Center for Research Resources Shared Instrumentation grant (1S10RR163736-01A1); Flight Attendant Medical Research Institute's young clinical scientist awar

CYBA Gene Polymorphisms and Adverse Outcomes in Acute Kidney Injury: A Prospective Cohort Study

Background: NADPH oxidase is an important enzyme involved in the generation of reactive oxygen species in acute kidney injury (AKI). Its key subunit, p22phox, is encoded by the highly polymorphic CYBA gene. Methods: We examined the associations of CYBA gene polymorphisms across the CYBA locus (rs8854, rs3794624, rs4673, rs4782390, and rs1049255) with dialysis requirement or in-hospital death in 256 hospitalized adults with AKI. Dominant and haplotype multivariable logistic regression analyses were performed, adjusted for sex, race, age, and severity of illness. Results: The baseline characteristics of the patients were not different among genotype groups with the exception of a lower prevalence of sepsis and shock in the CYBA rs8854 A-allele group; a higher prevalence of shock in the CYBA rs4782390 T-allele group, and a higher APACHE II score in the CYBA rs1049255 G-allele group. The CYBA rs8854 A-allele had an adjusted odds ratio (OR) of 0.41 (95% confidence interval, CI, 0.18–0.96) for the outcome of dialysis requirement or in-hospital death. The CYBA rs4673 T-allele and rs1049255 G-allele had unadjusted ORs of 1.69 (95% CI 1.03–2.79) and 1.66 (95% CI 1.01–2.73) for the composite outcome, respectively, which became non-significant after multivariable adjustment. The remaining 2 polymorphisms were not associated with the outcomes of interest. Finally, the presence of the CYBA A-A-G-G haplotype (generated from rs4782390, rs4673, rs3794624, and rs8854, all in Hardy-Weinberg equilibrium) was associated with an elevated OR of 1.81 (95% CI 1.07–3.08) for dialysis requirement or in-hospital death, which was attenuated after multivariable adjustment (OR 1.80; 95% CI 0.99–3.29). Conclusion: This study identifies several polymorphisms spanning the entire CYBA gene locus and a common haplotype as risk markers for dialysis requirement or in-hospital death in patients with AKI. Additional studies are needed to validate these findings

A new common functional coding variant at the DDC gene change renal enzyme activity and modify renal dopamine function.

The intra-renal dopamine (DA) system is highly expressed in the proximal tubule and contributes to Na+ and blood pressure homeostasis, as well as to the development of nephropathy. In the kidney, the enzyme DOPA Decarboxylase (DDC) originating from the circulation. We used a twin/family study design, followed by polymorphism association analysis at DDC locus to elucidate heritable influences on renal DA production. Dense single nucleotide polymorphism (SNP) genotyping across the DDC locus on chromosome 7p12 was analyzed by re-sequencing guided by trait-associated genetic markers to discover the responsible genetic variation. We also characterized kinetics of the expressed DDC mutant enzyme. Systematic polymorphism screening across the 15-Exon DDC locus revealed a single coding variant in Exon-14 that was associated with DA excretion and multiple other renal traits indicating pleiotropy. When expressed and characterized in eukaryotic cells, the 462Gln variant displayed lower Vmax (maximal rate of product formation by an enzyme) (21.3 versus 44.9 nmol/min/mg) and lower Km (substrate concentration at which half-maximal product formation is achieved by an enzyme.)(36.2 versus 46.8 μM) than the wild-type (Arg462) allele. The highly heritable DA excretion trait is substantially influenced by a previously uncharacterized common coding variant (Arg462Gln) at the DDC gene that affects multiple renal tubular and glomerular traits, and predicts accelerated functional decline in chronic kidney disease

A role for Dicer in immune regulation

Micro RNAs (miRNAs) regulate gene expression at the posttranscriptional level. Here we show that regulatory T (T reg) cells have a miRNA profile distinct from conventional CD4 T cells. A partial T reg cell–like miRNA profile is conferred by the enforced expression of Foxp3 and, surprisingly, by the activation of conventional CD4 T cells. Depleting miRNAs by eliminating Dicer, the RNAse III enzyme that generates functional miRNAs, reduces T reg cell numbers and results in immune pathology. Dicer facilitates, in a cell-autonomous fashion, the development of T reg cells in the thymus and the efficient induction of Foxp3 by transforming growth factor β. These results suggest that T reg cell development involves Dicer-generated RNAs

Physiology, behavior, and conservation

Many animal populations are in decline as a result of human activity. Conservation practitioners are attempting to prevent further declines and loss of biodiversity as well as to facilitate recovery of endangered species, and they often rely on interdisciplinary approaches to generate conservation solutions. Two recent interfaces in conservation science involve animal behavior (i.e., conservation behavior) and physiology (i.e., conservation physiology). To date, these interfaces have been considered separate entities, but from both pragmatic and biological perspectives, there is merit in better integrating behavior and physiology to address applied conservation problems and to inform resource management. Although there are some institutional, conceptual, methodological, and communication-oriented challenges to integrating behavior and physiology to inform conservation actions, most of these barriers can be overcome. Through outlining several successful examples that integrate these disciplines, we conclude that physiology and behavior can together generate meaningful data to support animal conservation and management actions. Tangentially, applied conservation and management problems can, in turn, also help advance and reinvigorate the fundamental disciplines of animal physiology and behavior by providing advanced natural experiments that challenge traditional frameworks

Identification of Subject-Specific Immunoglobulin Alleles From Expressed Repertoire Sequencing Data

The adaptive immune receptor repertoire (AIRR) contains information on an individuals' immune past, present and potential in the form of the evolving sequences that encode the B cell receptor (BCR) repertoire. AIRR sequencing (AIRR-seq) studies rely on databases of known BCR germline variable (V), diversity (D), and joining (J) genes to detect somatic mutations in AIRR-seq data via comparison to the best-aligning database alleles. However, it has been shown that these databases are far from complete, leading to systematic misidentification of mutated positions in subsets of sample sequences. We previously presented TIgGER, a computational method to identify subject-specific V gene genotypes, including the presence of novel V gene alleles, directly from AIRR-seq data. However, the original algorithm was unable to detect alleles that differed by more than 5 single nucleotide polymorphisms (SNPs) from a database allele. Here we present and apply an improved version of the TIgGER algorithm which can detect alleles that differ by any number of SNPs from the nearest database allele, and can construct subject-specific genotypes with minimal prior information. TIgGER predictions are validated both computationally (using a leave-one-out strategy) and experimentally (using genomic sequencing), resulting in the addition of three new immunoglobulin heavy chain V (IGHV) gene alleles to the IMGT repertoire. Finally, we develop a Bayesian strategy to provide a confidence estimate associated with genotype calls. All together, these methods allow for much higher accuracy in germline allele assignment, an essential step in AIRR-seq studies

Sleep-Disordered Breathing and Mortality: A Prospective Cohort Study

In a cohort of 6,441 volunteers followed over an average of 8.2 years, Naresh Punjabi and colleagues find sleep-disordered breathing to be independently associated with mortality and identify predictive characteristics

iPSCORE: A Resource of 222 iPSC Lines Enabling Functional Characterization of Genetic Variation across a Variety of Cell Types.

Large-scale collections of induced pluripotent stem cells (iPSCs) could serve as powerful model systems for examining how genetic variation affects biology and disease. Here we describe the iPSCORE resource: a collection of systematically derived and characterized iPSC lines from 222 ethnically diverse individuals that allows for both familial and association-based genetic studies. iPSCORE lines are pluripotent with high genomic integrity (no or low numbers of somatic copy-number variants) as determined using high-throughput RNA-sequencing and genotyping arrays, respectively. Using iPSCs from a family of individuals, we show that iPSC-derived cardiomyocytes demonstrate gene expression patterns that cluster by genetic background, and can be used to examine variants associated with physiological and disease phenotypes. The iPSCORE collection contains representative individuals for risk and non-risk alleles for&nbsp;95% of SNPs associated with human phenotypes through genome-wide association studies. Our study demonstrates the utility of iPSCORE for examining how genetic variants influence molecular and physiological traits in iPSCs and derived cell lines

Miscarriage and stillbirth following maternal Zika virus infection in nonhuman primates.

Zika virus (ZIKV) infection is associated with congenital defects and pregnancy loss. Here, we found that 26% of nonhuman primates infected with Asian/American ZIKV in early gestation experienced fetal demise later in pregnancy despite showing few clinical signs of infection. Pregnancy loss due to asymptomatic ZIKV infection may therefore be a common but under-recognized adverse outcome related to maternal ZIKV infection