Angiotensin II type 1 receptor overexpression in podocytes induces glomerulosclerosis in transgenic rats.

Angiotensin II (AngII) is a critical determinant of glomerular function involving both hemodynamic and pressure-independent effects that are insufficiently understood. A novel transgenic rat (TGR) model with overexpression of the human AngII type 1 receptor (hAT1) in podocytes was developed to study the consequences of an increased AT1 signaling on the structure and function of the glomerular filter. Use of the nephrin promoter to target the podocytes resulted in an expression of the hAT1 at a level roughly two times higher than the endogenous AT1 throughout life.

Liver regeneration in FGF-2-deficient mice: VEGF acts as potential functional substitute for FGF-2.

Background/aims: The angiogenic properties, its role in mesoderm differentiation and cell culture studies implicate an important role of fibroblast growth factor (FGF-2) in liver regeneration. The aim of the study was to evaluate this role in a FGF-2 knockout mouse model.

Methods: Liver regeneration after left hemihepatectomy (partial hepatectomy, PH) was evaluated in homozygous FGF-2 deficient (-/-) mice (male C57BL/6J) and their FGF-2 competent (+/+) littermates (controls) (day 0-10).

Immunohistochemical and mRNA localization of the angiotensin II receptor subtype 2 (AT2) in follicular granulosa cells of the rat ovary.

A local renin-angiotensin system (RAS), including specific angiotensin II receptor subtypes, is present in the rat ovary. Immunohistochemistry using a polyclonal antibody and mRNA in situ hybridization were performed on perfusion-fixed, paraffin-embedded ovaries obtained from untreated sexually mature, normally cycling rats. Immunofluorescent staining revealed an exclusive and distinct labeling of follicular granulosa cells showing a plaque-like expression pattern at the cell borders, being detectable in different stages of atretic degeneration.

Enhanced green fluorescent protein-transfection of murine colon carcinoma cells: key for early tumor detection and quantification.

Many animal models for metastatic colorectal cancer represent clinical manifestations just inaccurately. We introduce a novel mouse model for metastastatic colorectal cancer. In order to remain close to the clinical disease a syngenic murine colon carcinoma cell line (colon 26 cells) was transfected with enhanced green fluorescent protein (EGFP).

Mutations in a novel gene, NPHP3, cause adolescent nephronophthisis, tapeto-retinal degeneration and hepatic fibrosis.

Nephronophthisis (NPHP), a group of autosomal recessive cystic kidney disorders, is the most common genetic cause of progressive renal failure in children and young adults. NPHP may be associated with Leber congenital amaurosis, tapeto-retinal degeneration, cerebellar ataxia, cone-shaped epiphyses, congenital oculomotor apraxia and hepatic fibrosis. Loci associated with an infantile type of NPHP on 9q22-q31 (NPHP2), juvenile types of NPHP on chromosomes 2q12-q13 (NPHP1) and 1p36 (NPHP4) and an adolescent type of NPHP on 3q21-q22 (NPHP3) have been mapped.

PAF-receptor in inflammatory versus non inflammatory human epidermis, cell cultures and embryonal cells.

Objective: PAF-R (platelet activating factor-receptor) has been found on human keratinocytes to bind PAF, a proinflammatory phospholipid. We aimed to study PAF-R in a range of dermal cell lines and in samples of normal and psoriatic human skin to learn about its further role in humans.

Methods: PAF-R was labeled immunocytochemically, histochemically and additionally studied with western blotting in human keratinocytes, human fibroblasts, embryonal keratinocytes, tumor cell lines and samples of normal and psoriatic human skin.

Pathways to recovery and loss of nephrons in anti-Thy-1 nephritis.

The present histopathologic study of anti-Thy-1.1 models of mesangioproliferative glomerulonephritis in rats provides a structural analysis of damage development and of pathways to recovery and to nephron loss. As long as the disease remains confined to the endocapillary compartment, the damage may be resolved or recover with a mesangial scar.

Supplementation and inhibition of nitric oxide synthesis influences bacterial transit time during bacterial translocation in rats.

In the obstructed gut, nitric oxide (NO) may influence intestinal barrier function and translocation of bacteria. By using a novel experimental approach, we investigated the effect of supplementation and inhibition of NO synthesis on the time interval necessary for translocation of green fluorescent protein-transfected Escherichia coli (GFP-uv E. coli) in a rat model of small bowel obstruction.

Urinary clusterin levels in the rat correlate with the severity of tubular damage and may help to differentiate between glomerular and tubular injuries.

Clusterin is a secreted glycoprotein that is synthesized after several types of tubular injury. We therefore wondered whether the urinary excretion of clusterin could serve as a parameter to determine the severity of tubular damage. Using an affinity-purified rabbit antiserum raised against recombinant clusterin, we established an enzyme-linked immunosorbent assay to measure the urinary excretion of clusterin after bilateral renal ischemia, in the (cy/ +) rat model of autosomal-dominant polycystic kidney disease and in the FHH rat model of focal segmental glomerulosclerosis.

The gut origin of bacterial pancreatic infection during acute experimental pancreatitis in rats.

Background: Infections are frequent complications and determine clinical course and outcome in severe pancreatitis. A novel animal model was used to assess minimal transit time of bacterial translocation (BT) across the gut mucosa in vivo using green fluorescent protein-transfected Escherichia coli and intravital video microscopy.

Methods: Three hours after induction of acute pancreatitis by i.

Analysis of differential gene expression in stretched podocytes: osteopontin enhances adaptation of podocytes to mechanical stress.

Glomerular hypertension is a major determinant advancing progression to end-stage renal failure. Podocytes, which are thought to counteract pressure-mediated capillary expansion, are increasingly challenged in glomerular hypertension. Studies in animal models of glomerular hypertension indicate that glomerulosclerosis develops from adhesions of the glomerular tuft to Bowman's capsule due to progressive podocyte loss.

Characterization of a major modifier locus for polycystic kidney disease (Modpkdr1) in the Han:SPRD(cy/+) rat in a region conserved with a mouse modifier locus for Alport syndrome.

The genetic analysis of rodent disease models provides a powerful tool to investigate how modifier loci cause variation in the phenotypic expression of a disease. In order to test the existence of modifier loci influencing polycystic kidney disease (PKD) phenotypes, we derived a backcross between PKD susceptible Han:SPRD(cy/+) and control Brown Norway (BN) rats, and performed a whole-genome scan in 182 PKD affected hybrids showing different grades of disease severity. The genetic dissection of PKD in the cross allowed us to detect a modifier locus, Modpkdr1, on rat chromosome 8 that controls PKD severity, kidney mass and plasma urea concentration.

Microscopy of bacterial translocation during small bowel obstruction and ischemia in vivo--a new animal model.

Background: Existing animal models provide only indirect information about the pathogenesis of infections caused by indigenous gastrointestinal microflora and the kinetics of bacterial translocation. The aim of this study was to develop a novel animal model to assess bacterial translocation and intestinal barrier function in vivo.

Methods: In anaesthetized male Wistar rats, 0.

Altered expression pattern of polycystin-2 in acute and chronic renal tubular diseases.

Polycystin-2 represents one of so far two proteins found to be mutated in patients with autosomal-dominant polycystic kidney disease. Evidence obtained from experiments carried out in cell lines and with native kidney tissue strongly suggests that polycystin-2 is located in the endoplasmic reticulum. In the kidney, polycystin-2 is highly expressed in cells of the distal and connecting tubules, where it is located in the basal compartment.

Molecular basis of autosomal-dominant polycystic kidney disease.

Autosomal-dominant polycystic kidney disease (ADPKD) is one of the most common monogenetic diseases in humans. The discovery that mutations in the PKD1 and PKD2 genes are responsible for ADPKD has sparked extensive research efforts into the physiological and pathogenetic role of polycystin-1 and polycystin-2, the proteins encoded by these two genes. While polycystin-1 may mediate the contact among cells or between cells and the extracellular matrix, a lot of evidence suggests that polycystin-2 represents an endoplasmic reticulum-bound cation channel.

Creatinine clearance, Cockcroft-Gault formula and cystatin C: estimators of true glomerular filtration rate in the elderly?

Background: The aim of this study was to assess the accuracy and precision of estimators of true glomerular filtration rate (GFR) (Cockcroft formula, measured creatinine clearance (CCR) and a cystatin-C-based estimation) in elderly patients attending a geriatric department. Additionally, parameters influencing GFR in the elderly were evaluated.

Methods: 30 patients aged 57-90 years treated in the Geriatric Department for pulmonary or cerebral diseases were included in the study.

Impaired endocytosis may represent an obstacle to gene therapy in polycystic kidney disease.

Background: Autosomal-dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease and a frequent cause of chronic renal failure. The cloning of the PKD1 and PKD2 genes, which are mutated in the great majority of patients with this disease, opens up the opportunity for somatic gene therapy by introduction of the wild-type gene or cDNA. Several publications have provided evidence, that many portions of the nephron and the collecting duct can form cysts, including the proximal tubule.

Complement analysis in children with idiopathic membranoproliferative glomerulonephritis: a long-term follow-up.

Fifty children with idiopathic membranoproliferative glomerulonephritis (MPGN), aged 2-14 years at apparent onset, were monitored for the presence of C3 nephritic factor (C3 NeF) and signs of complement activation in serum. In addition, C3 allotyping was performed in 32 patients. Observation time ranged from 2 to 20 (median 11) years.

Podocyte injury underlies the progression of focal segmental glomerulosclerosis in the fa/fa Zucker rat.

Background: The progression of diabetic nephropathy to chronic renal failure is based on the progressive loss of viable nephrons. The manner in which nephrons degenerate in diabetic nephropathy and whether the injury could be transferred from nephron to nephron are insufficiently understood. We studied nephron degeneration in the fa/fa Zucker rat, which is considered to be a model for non-insulin-dependent diabetes mellitus.

Changes of AT(2) receptor levels in the rat adrenal cortex and medulla induced by bilateral nephrectomy and its modulation by circulating ANG II.

We studied regulation of the AT(2) receptor by investigating the effect of bilateral nephrectomy (bNX) in Sprague-Dawley rats. The expression of aldosterone synthase (CYP11B2) and AT(2) receptor mRNA was detected by nonradioactive in situ hybridization. AT(2) receptor mRNA was detected in cells of the first two or three subcapsular cell layers of the zona glomerulosa (ZG) and in the medulla of sham-operated animals.

An endocytosis defect as a possible cause of proteinuria in polycystic kidney disease.

Because proteinuria has been demonstrated in patients with autosomal-dominant polycystic kidney disease (ADPKD), we have investigated whether proteinuria also occurs in the (cy/+) rat, a widely used model for ADPKD. Increased urinary excretion of proteins, in particular of albumin, can be found in 16-wk-old (cy/+) rats, with a gel electrophoresis pattern compatible with a tubular origin of proteinuria. Using FITC-labeled dextran as an in vivo tracer for renal tubular endosomal function, we could show that portions of cyst-lining epithelia from proximal tubules have lost the ability to endocytose, which is necessary for the reabsorption of low-molecular-weight proteins.

Tracer studies in the rat demonstrate misdirected filtration and peritubular filtrate spreading in nephrons with segmental glomerulosclerosis.

In two genetic models of "classic" focal segmental glomerulosclerosis (FSGS), the Milan normotensive and the Fawn-hooded hypertensive rats, tracer studies were performed to test the hypothesis that misdirected glomerular filtration and peritubular filtrate spreading are relevant mechanisms that contribute to nephron degeneration in this disease. Two exogenous tracers, lissamine green and horse spleen ferritin, were administered by intravenous injection and subsequently traced histologically in serial kidney sections. In contrast to control rats, both tracers in kidneys of Milan normotensive and Fawn-hooded hypertensive rats with established FSGS were found to accumulate extracellularly at the following sites: (1) within tuft adhesions to Bowman's capsule and associated paraglomerular spaces, (2) at the glomerulotubular junction contained within extensions of the paraglomerular spaces onto the tubule, and (3) within subepithelial peritubular spaces eventually encircling the entire proximal convolution of an affected nephron.

A possible role for metalloproteinases in renal cyst development.

The expansion of cysts in polycystic kidneys bears several similarities to the invasion of the extracellular matrix by benign tumors. We therefore hypothesized that cyst-lining epithelial cells produce extracellular matrix-degrading metalloproteinases and that the inhibition of these enzymes may represent a potential target for therapeutic intervention. Using in situ hybridization, we first analyzed the expression of membrane-type metalloproteinase 1 (MMP-14), an essential matrix metalloproteinase, of its inhibitor TIMP-2, and of the cytokine transforming growth factor (TGF)-beta2 in the (cy/+) rat model of autosomal-dominant polycystic kidney disease.

Striking increase of natriuresis by low-dose spironolactone in congestive heart failure only in combination with ACE inhibition: mechanistic evidence to support RALES.

Background: A marked reduction of overall mortality in patients with severe congestive heart failure (CHF) has been demonstrated by addition of the mineralocorticoid receptor antagonist spironolactone to ACE inhibition. The aim of the present study was to examine a hypothesized interaction of spironolactone and ACE inhibitors in renal electrolyte and volume regulation.

Methods And Results: Wistar rats with extensive myocardial infarction or sham operation were treated with either placebo, the ACE inhibitor trandolapril, low-dose spironolactone, or a combination of the 2.

Altered expression of type II sodium/phosphate cotransporter in polycystic kidney disease.

Renal phosphate (Pi) absorption is mediated via the type II sodium/Pi cotransporter (NaPi-2) in the brush border membrane (BBM) of proximal tubules. Simultaneous detection of NaPi-2 mRNA by in situ hybridization and of NaPi-2 immunoreactivity by immunohistochemistry was performed to investigate the distribution of the cotransporter in healthy control rats and during progression of autosomal dominant polycystic kidney disease (ADPKD). The purpose of the study was to disclose a relation between proximal tubular cell differentiation and NaPi-2 expression.