Low prevalence of nonconservative mutations of serum and glucocorticoid-regulated kinase (SGK1) gene in hypertensive and renal patients

Background. The serum- and glucocorticoid-regulated kinase (SGK1) gene is an important mediator of aldosterone action, regulating the expression of the renal epithelial Na+ channel. In renal failure, blood pressure (BP) is markedly salt-dependent and increases with decreasing renal function. Mutations of the SGK1 gene affecting phosphorylation could be responsible for salt-mediated increases in BP and hypertension-related progression to end-stage renal disease (ESRD). Methods. The SGK1 gene was analysed for mutations in the exons 4, 5, 8 and 10-12, because of potential phosphorylation sites, in 591 subjects, including 311 ESRD patients (either dialysis or transplanted). In addition, an intron 6 single-nucleotide polymorphism (SNP) described previously was also investigated in this study. Genotyping was performed either by using a strategy based on single strand conformation polymorphism analysis of polymerase chain reaction (PCR) products and subsequent direct sequencing of identified gel shift variants or by using high throughput 5′ nuclease allelic discrimination assay. Results. Two SNPs in coding regions of SGK1 potentially influencing the phosphorylation of Sgk1 were identified. Both SNPs were synonymous. The prevalence of the first variant, a previously reported SNP at codon 240 in exon 8, did not differ between ESRD patients (16.3%) and controls (15.7%). There was no association between the SNP in exon 8 and either BP within the control population or progression of renal disease in the ESRD population. The second SNP at codon 398 in exon 12 was identified in one patient only. Intron 6 and exon 8 SNPs were in strong linkage disequilibrium, but did not show any association with either BP or renal diseases. Conclusions. Based on statistical analysis homozygosity for nonconservative mutations in the coding region of the SGK1 gene is estimated at < 1/300 000 when a white Caucasian population is considered, arguing against an important role of mutations of this coding region in hypertension and hypertension-associated progression of renal diseas

The Prognostic Significance of Protein-energy Malnutrition in Geriatric Patients

Although it has been shown that protein-energy malnutrition is a predictor of adverse outcome in geriatric patients, it is unclear whether this is due to underlying disease or disability, or whether malnutrition is an independent outcome predictor. To clarify the predictive role of malnutrition, we analysed the 4.5-year mortality and living location follow-ups of 219 geriatric patients admitted to a geriatric assessment unit. Prevalence of anthropometric and serological malnutrition indicators were between 13.7% and 39.8% at hospital admission. In bivariate models, prealbumin, subnormal arm muscle area, and subnormal body weight were predictors of mortality and survival at home. On the other hand, albumin, transferrin, and triceps skin-fold thickness did not predict these outcomes. In multivariate models the hazard ratio (HR) of 4.5-year mortality remained significant with an HR of 1.8 (95% CI 1.3−2.6) for subnormal arm muscle area, and 1.6 (95% CI 1.3−2.6) for subnormal body weight. Prealbumin was the strongest serological outcome predictor (multivariate mortality HR 1.9, 95% CI, 1.3−2.8). In these models, subnormal cognitive function, impaired physical function, and creatinine clearance < 30 ml/min were also associated with increased mortality. Malnutrition did not predict hospital discharge location, but among patients discharged home, those with initial malnutrition had a decreased length of survival at home. Our findings indicate that certain protein-energy malnutrition indicators are independent risk factors predicting decreased length of overall survival and survival at home in geriatric patients. Physicians should screen actively for this often unrecognized problem and initiate appropriate treatment strategie

Age-dependent Decrease in 11β-Hydroxysteroid Dehydrogenase Type 2 (11β-HSD2) Activity in Hypertensive Patients

Background The prevalence of arterial hypertension lacking a defined underlying cause increases with age. Age-related arterial hypertension is insufficiently understood, yet known characteristics suggest an aldosterone-independent activation of the mineralocorticoid receptor. Therefore, we hypothesized that 11β-HSD2 activity is age-dependently impaired, resulting in a compromised intracellular inactivation of cortisol (F) with F-mediated mineralocorticoid hypertension. Methods Steroid hormone metabolites in 24-h urine samples of 165 consecutive hypertensive patients were analyzed for F and cortisone (E), and their TH-metabolites tetrahydro-F (THF), 5αTHF, TH-deoxycortisol (THS), and THE by gas chromatography-mass spectroscopy. Apparent 11β-HSD2 and 11β-hydroxylase activity and excretion of F metabolites were assessed. Results In 72 female and 93 male patients aged 18-84 years, age correlated positively with the ratios of (THF + 5αTHF)/THE (P = 0.065) and F/E (P < 0.002) suggesting an age-dependent reduction in the apparent 11β-HSD2 activity, which persisted (F/E; P = 0.020) after excluding impaired renal function. Excretion of F metabolites remained age-independent most likely as a consequence of an age-dependent diminished apparent 11β-hydroxylase activity (P = 0.038). Conclusion Reduced 11β-HSD2 activity emerges as a previously unrecognized risk factor contributing to the rising prevalence of arterial hypertension in elderly. This opens new perspectives for targeted treatment of age-related hypertensio

Sodium retention in rats with liver cirrhosis is associated with increased renal abundance of NaCl cotransporter (NCC)

Background. Liver cirrhosis is associated with enhanced renal tubular sodium retention, the mechanism of which is still debated. We hypothesized that liver cirrhosis is associated with increased expression of renal epithelial sodium transporter(s). Methods. Liver cirrhosis was induced by bile duct ligation (BDL) in rats. Steady state mRNA of ENaC subunits α, β, γ serum and glucocorticoid inducible kinase (Sgk1) were measured by TaqMan PCR in kidney homogenates at week 1, 2, 3 and 4 after BDL. Renal protein content of ENaC subunits, ubiquitin-protein-ligase Nedd4-2 and NaCl cotransporter (NCC) were assessed by western blot. Subcellular localization of ENaC subunits and NCC were analysed by immunohistochemistry. Results. Steady state mRNA of ENaC α, β and γ were unchanged during the 4 weeks investigated, while ENaC protein decreased most prominently at week 2 (control vs BDL; α, −46%; β, −81%; and γ, −63%; n = 6). Subcellular localization of ENaC subunits was not altered at week 2. Sgk1 mRNA did not change, whereas Nedd4-2 protein was reduced by >50% 2-4 weeks after BDL. NCC protein significantly increased at week 1 (control vs BDL: +66%, n = 6, P<0.05) and decreased at week 3 (control vs BDL: −85%, n = 6, P<0.0005). Conclusions. Enhanced abundance of NCC was observed in the initial stage after BDL, followed by a marked decrease. ENaC transcription, translation or cell surface abundance was not increased after BD

Minimally invasive, imaging guided virtual autopsy compared to conventional autopsy in foetal, newborn and infant cases: study protocol for the paediatric virtual autopsy trial

BACKGROUND: In light of declining autopsy rates around the world, post-mortem MR imaging is a promising alternative to conventional autopsy in the investigation of infant death. A major drawback of this non-invasive autopsy approach is the fact that histopathological and microbiological examination of the tissue is not possible. The objective of this prospective study is to compare the performance of minimally invasive, virtual autopsy, including CT-guided biopsy, with conventional autopsy procedures in a paediatric population. METHODS/DESIGN: Foetuses, newborns and infants that are referred for autopsy at three different institutions associated with the University of Zurich will be eligible for recruitment. All bodies will be examined with a commercial CT and a 3 Tesla MRI scanner, masked to the results of conventional autopsy. After cross-sectional imaging, CT-guided tissue sampling will be performed by a multifunctional robotic system (Virtobot) allowing for automated post-mortem biopsies. Virtual autopsy results will be classified with regards to the likely final diagnosis and major pathological findings and compared to the results of conventional autopsy, which remains the diagnostic gold standard. DISCUSSION: There is an urgent need for the development of alternative post-mortem examination methods, not only as a counselling tool for families and as a quality control measure for clinical diagnosis and treatment but also as an instrument to advance medical knowledge and clinical practice. This interdisciplinary study will determine whether virtual autopsy will narrow the gap in information between non-invasive and traditional autopsy procedures. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01888380

High Salt Intake Down-Regulates Colonic Mineralocorticoid Receptors, Epithelial Sodium Channels and 11β-Hydroxysteroid Dehydrogenase Type 2

Besides the kidneys, the gastrointestinal tract is the principal organ responsible for sodium homeostasis. For sodium transport across the cell membranes the epithelial sodium channel (ENaC) is of pivotal relevance. The ENaC is mainly regulated by mineralocorticoid receptor mediated actions. The MR activation by endogenous 11β-hydroxy-glucocorticoids is modulated by the 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). Here we present evidence for intestinal segment specific 11β-HSD2 expression and hypothesize that a high salt intake and/or uninephrectomy (UNX) affects colonic 11β-HSD2, MR and ENaC expression. The 11β-HSD2 activity was measured by means of 3H-corticosterone conversion into 3H-11-dehydrocorticosterone in Sprague Dawley rats on a normal and high salt diet. The activity increased steadily from the ileum to the distal colon by a factor of about 3, an observation in line with the relevance of the distal colon for sodium handling. High salt intake diminished mRNA and protein of 11β-HSD2 by about 50% (p<0.001) and reduced the expression of the MR (p<0.01). The functionally relevant ENaC-β and ENaC-γ expression, a measure of mineralocorticoid action, diminished by more than 50% by high salt intake (p<0.001). The observed changes were present in rats with and without UNX. Thus, colonic epithelial cells appear to contribute to the protective armamentarium of the mammalian body against salt overload, a mechanism not modulated by UNX

Optimised and Rapid Pre-clinical Screening in the SOD1G93A Transgenic Mouse Model of Amyotrophic Lateral Sclerosis (ALS)

The human SOD1G93A transgenic mouse has been used extensively since its development in 1994 as a model for amyotrophic lateral sclerosis (ALS). In that time, a great many insights into the toxicity of mutant SOD1 have been gained using this and other mutant SOD transgenic mouse models. They all demonstrate a selective toxicity towards motor neurons and in some cases features of the pathology seen in the human disease. These models have two major drawbacks. Firstly the generation of robust preclinical data in these models has been highlighted as an area for concern. Secondly, the amount of time required for a single preclinical experiment in these models (3–4 months) is a hurdle to the development of new therapies. We have developed an inbred C57BL/6 mouse line from the original mixed background (SJLxC57BL/6) SOD1G93A transgenic line and show here that the disease course is remarkably consistent and much less prone to background noise, enabling reduced numbers of mice for testing of therapeutics. Secondly we have identified very early readouts showing a large decline in motor function compared to normal mice. This loss of motor function has allowed us to develop an early, sensitive and rapid screening protocol for the initial phases of denervation of muscle fibers, observed in this model. We describe multiple, quantitative readouts of motor function that can be used to interrogate this early mechanism. Such an approach will increase throughput for reduced costs, whilst reducing the severity of the experimental procedures involved