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E Ritz

Publications and source records attributed to E Ritz.

At least 271 records · Page 15Linked to original sources
PubMed1997

Renal expression of two rat kallikrein genes under diabetic conditions.

OBJECTIVE: We have reported that bradykinin (BK) excretion is increased in severely diabetic rats, independent of the activity of the main renal kinin-forming enzyme, true kallikrein (KLK). To further investigate the relationship between renal BK excretion and renal KLK in diabetes we studied the regulation of the renal kallikrein-like gene, rat kallikrein 7 (rKLK7), as well as of the KLK encoding gene, rKLK1, in streptozotocin-induced (STZ) diabetic rats. METHODS: Experiments were performed in STZ-induced diabetic male Wistar rats and their non-diabetic controls (n = 7 each group). Twelve weeks after STZ injection, urinary KLK activity, glomerular filtration rate and total protein excretion were determined. After extraction of total renal cortical RNA, specific oligonucleotides were used to generate a reverse transcription-polymerase chain reaction (RT-PCR) products of renal cortical rKLK1 and rKLK7 messenger (m)RNA. Southern blot analysis of these RT-PCR products were hybridized with appropriate gene-specific oligonucleotide probes. RESULTS: After 12 weeks, the rats showed hyperglycemia, proteinuria and a reduced glomerular filtration rate. Renal kininogenase was reduced, as indicated by a reduction in the expression of rKLK1, as well as of the KLK-related gene, rKLK7. CONCLUSIONS: Our data show that the expression of the two principal renal KLK genes is downregulated in the renal cortex of STZ-diabetic rats. We suggest that under severe diabetic conditions the rise in urinary BK excretion is not related to activation of the renal kinin-forming enzyme system.

Actins↗
PubMed1997

Genetics of the renin-angiotensin system and renal disease: a progress report.

The genes of the renin-angiotensin system and their relation to renal diseases are of great interest. The number of studies examining the role of polymorphism in these genes in development or progression of renal diseases has increased nearly logarithmically, but results remain conflicting. Evidence is increasing that progression of renal disease is more rapid in DD-homozygotes of the angiotensin-converting enzyme gene polymorphism, but other relationships have not been solidly established.

Angiotensinogen↗
PubMed1997

Aortic changes in experimental renal failure: hyperplasia or hypertrophy of smooth muscle cells?

Cardiovascular complications are a well-known feature of chronic renal failure. Increased wall thickness of intramyocardial arterioles and elastic (aorta) and peripheral (mesenteric) arteries is seen even after normalization of blood pressure. It is currently unknown whether such increases result from hyperplasia of vascular smooth muscle cells, hypertrophy, or a combination of both or from an increase in aortic extracellular matrix. Using a recently developed unbiased stereological technique (the dissector), we investigated the aortas of subtotally nephrectomized rats and sham-operated controls after perfusion fixation. We determined aortic wall thickness, cross-sectional area of aortic media, total number of vascular smooth muscle cells per unit aortic length (1 mm), mean cell and nuclear volumes, volume density of elastic fibers, extracellular matrix, vascular smooth muscle cells, and total volumes of these structures per unit of aortic length (1 mm). Blood pressure was not significantly increased in subtotally nephrectomized rats. In contrast, wall thickness, cross-sectional media, total number of aortic vascular smooth muscle cells, and volume of extracellular matrix including collagen were significantly increased after subtotal nephrectomy, whereas cellular hypertrophy was only modest and an increase in elastic fibers did not occur. In conclusion, increased aortic wall thickness in experimental renal failure results primarily from an increase in aortic extracellular matrix. In addition, however, proliferation of aortic vascular smooth muscle cells resulting in cell hyperplasia also contributed to aortic wall thickening to a minor degree. It appears that aortic wall thickening is caused by secretory stimulation of the proliferating vascular smooth muscle cells, resulting in increased matrix production. The nature of the underlying stimulus requires further investigation.

Animals↗
PubMed1997

Angiotensin II affects basal, pulsatile, and glucose-stimulated insulin secretion in humans.

Angiotensin II (Ang II) modulates the tissue response to insulin (insulin sensitivity), but the effect of Ang II on the secretion of insulin has not been investigated thus far. Nineteen healthy volunteers (17 male; mean age, 26+/-1 years) were studied. In a double-blind, randomized, placebo-controlled study, seven volunteers were allocated on three occasions in random order after an overnight fast to three interventions: (1) solvent (placebo) infusion; (2) infusion of 1.0 ng Ang II x kg(-1) x min(-1) (subpressor dose); and (3) infusion of 5.0 ng Ang II x kg(-1) x min(-1) (pressor dose). Frequent blood samples (each minute) were obtained for estimation of plasma insulin concentrations over a period of 120 minutes to assess basal and pulsatile insulin secretion. In an ancillary study, plasma glucose and insulin levels were measured after an oral glucose tolerance test while solvent (placebo) or Ang II was infused in 12 fasting healthy volunteers. Plasma insulin concentrations were measured immunoenzymatically (enzyme-linked immunosorbent assay). Insulin secretion pulses were analyzed with the deconvolution technique, and the regularity of insulin secretion was analyzed with the approximate entropy technique. Plasma insulin half-life was assessed using the hyperinsulinemic euglycemic clamp method. The pressor dose of Ang II reduced total, basal, and pulsatile insulin secretion, and this effect was highly significant (P<.01). The subpressor dose tended to suppress insulin secretion. The burst frequency (number of peaks) and the regularity of insulin secretion were not affected by administration of Ang II. After the oral glucose load, the insulinemic response was significantly lower and plasma glucose concentrations were significantly higher with infusion of Ang II compared with placebo. Ang II affects both the basal (nonpulsatile) and the pulsatile component of spontaneous insulin secretion and the glucose-stimulated insulin secretion in humans. This observation is of potential interest with respect to the interaction of Ang II and insulin, eg, in the genesis of hyperinsulinemia and hypertension.

Adult↗
PubMed1997

Angiotensin converting enzyme inhibitors, calcium channel blockers, and their combination in the treatment of glomerular disease.

BACKGROUND: Glomerular diseases may progress to end-stage renal failure via the development of glomerulosclerosis. Systemic hypertension and intraglomerular hypertension are important, although not the only, determinants of this process. Proteinuria (albuminuria) is a surrogate marker for glomerular damage and renal prognosis. EFFICACY OF ANGIOTENSIN CONVERTING ENZYME (ACE) INHIBITORS: In animal experiments and in controlled clinical studies, ACE inhibitors have proved to be effective in reducing proteinuria and in preventing glomerulosclerosis or progression to end-stage renal failure, possibly more than can be explained by their effects on blood pressure. EFFICACY OF CALCIUM CHANNEL BLOCKERS: In contrast to the uniform efficacy of ACE inhibitors, the effect of calcium channel blockers is less uniform. It depends on the model of renal damage used, the extent of the fall in systemic blood pressure and the type of calcium channel blocker used. Nevertheless, clinical studies have shown a reduction in proteinuria and at least an attenuation of progression with the use of long-acting calcium channel blockers. RATIONALE FOR THE COMBINATION OF ACE INHIBITORS AND CALCIUM CHANNEL BLOCKERS: If angiotensin II influences the progression of renal failure, as is universally accepted, then the combination of an ACE inhibitor (reducing the generation of angiotensin II) and a calcium channel blocker (reducing target-organ responsiveness to angiotensin II) appears a promising one. EVIDENCE FOR THE EFFECTIVENESS OF THIS COMBINATION: In animal experiments, co-administration of an ACE inhibitor and a calcium channel blocker caused a more marked reduction in glomerulosclerosis, and this was seen in the stroke-prone spontaneously hypertensive rat model even at non-antihypertensive doses. In human diabetic nephropathy at least, proteinuria (measured as a surrogate marker of the illness) was lowered more effectively by the combination of an ACE inhibitor and a calcium channel blocker than either drug used as monotherapy despite a similar fall in blood pressure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Risk factors for development of diabetic nephropathy: a review.

Recently evidence has accumulated that diabetic nephropathy clusters in families, both in insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetic patients. Furthermore, hypertension and cardiovascular accidents are found more frequently in families of NIDDM with diabetic nephropathy. Some observations in offspring of NIDDM patients with diabetic nephropathy point to high urinary albumin excretion and slightly greater blood pressure values, both within the normal range compared to offspring of patients without diabetic nephropathy. Further follow-up is required to assess whether these findings are indicative of a possible genetic predisposition to diabetic nephropathy.

Albuminuria↗
PubMed1997

Angiotensin I converting enzyme gene polymorphism and diabetic nephropathy in type II diabetes.

BACKGROUND: The factors leading to diabetic nephropathy (DN) are not completely understood. Besides glycaemic control, genetic predisposition seems to play an important role for the development of DN. Genes of the renin-angiotensin system are potential candidate genes. An insertion/deletion polymorphism in the gene coding for the angiotensin I converting enzyme (ACE) has been extensively examined, but results were conflicting. METHODS: We studied 658 patients with type II diabetes (n = 347 without DN, n = 311 with DN). RESULTS: No difference was found in genotype distribution or allele frequencies between diabetic patients with and without nephropathy as defined by albumin excretion > or = 30 mg/day, but patients on dialysis had more frequently the DD-genotype. CONCLUSION: Although we acknowledge certain problems in the design of the study the results in this large cohort suggest that the I/D polymorphism of the ACE gene does not play a major role in the development of DN. They are compatible, however, with a role of the gene in progression.

Adult↗
PubMed1997

Rapidly progressive IgA nephropathy with anti-myeloperoxidase antibodies benefits from immunosuppression.

CLINICAL OBSERVATIONS: Three patients with previous pulmonary infections were recently admitted with rapidly progressive renal failure. Renal biopsy showed crescentic glomerulonephritis with deposits of IgA, C3c and C3d. Serology disclosed P-ANCA with high-titer anti-myeloperoxidase antibodies. Two out of three patients became dialysis dependent despite immunosuppression with methylprednisolone and cyclophosphamide. Renal function improved in both patients after 2 weeks and 9 months, respectively, permitting termination of hemodialysis. All patients benefited from immunosuppressive treatment which is currently still being continued. CONCLUSION: The data suggest that early immunosuppression is beneficial in patients presenting with crescentic rapidly progressive IgA GN and anti-myeloperoxidase antibodies, which may represent a novel subset of crescentic IgA GN associated with high-titer anti-myeloperoxidase antibodies constituting an overlap group between microscopic polyangiitis and IgA GN.

Aged↗
PubMed1997

Genetic determinants of diabetic renal disease and their impact on therapeutic interventions.

Approximately 30% of patients with type 1 and type 2 diabetes develop diabetic nephropathy. Apart from metabolic control, genetic predisposition plays an important role in its genesis. Analysis of intermediate phenotypic markers showed that the activity of Na/Li- and Na+/H(+)-countertransport is increased in patients with diabetic nephropathy. The renin-angiotensin system is of crucial importance as a system for therapeutic intervention and as genetic marker for susceptibility to renal disease. Consequently, the analysis of molecular genetic markers has focused on a polymorphism in the gene for the angiotensin II converting enzyme (ACE). However, the analysis of the I/D-polymorphism with respect to development of diabetic nephropathy in type 1 and type 2 diabetes has yielded conflicting results, at least in type 1 diabetes. These discrepant results may be due to differences in definition, sample size and ethnic background of the patients. In IgA glomerulonephritis it has been shown that the DD genotype (which is correlated with higher serum and tissue ACE activity compared to II genotype) is associated with a more rapid deterioration of renal function. The same adverse effect of the DD genotype could also be demonstrated in patients with diabetic nephropathy. Two studies examined the response to treatment according to the different genotypes, with contradictory results. A Japanese study showed a more pronounced reduction in proteinuria under ACE inhibitor treatment in patients with DD genotype, whereas a Danish study showed that patients with the DD genotype exhibited a steeper decline in renal function despite ACE inhibitor treatment. The data available for other candidate genes are fragmentary and negative throughout.

Diabetic Nephropathies↗
PubMed1997

Long-term progression of chronic renal insufficiency in the AIPRI Extension Study. The Angiotensin-Converting-Enzyme Inhibition in Progressive Renal Insufficiency Study Group.

The Angiotensin-converting-enzyme Inhibition on Progressive Renal Insufficiency (AIPRI) Study showed that the ACE inhibitor benazepril provides protection against loss of renal function in patients with chronic renal insufficiency (CRI) caused by various renal diseases. As a result of unexpectedly low mortality in the placebo group, there was a substantial imbalance in mortality during the course of this study (8 patients on benazepril vs. 1 on placebo). The aim of the extension study was to follow-up the patients from the AIPRI core study until autumn 1996, focusing on CRI progression and mortality. Data collection was post hoc. Patients were treated according to investigators' usual practices, without knowledge of the core study trial medication or (initially) the core trial results. A new primary efficacy parameter was defined as the time from the start of core study treatment to the occurrence of the first event in the combined composite end-point of dialysis, renal transplantation or death related to renal disease. Serial serum creatinine levels and all-cause mortality were also recorded. The median total follow-up for core + extension periods was 6.6 years. Many patients from both treatment groups (64% on benazepril and 61% on placebo) received ACE inhibitors during follow-up. In the intention-to-treat analysis of the core + extension data, only 79 of 300 patients from the benazepril group, compared to 102 of the 283 patients from the placebo group needed dialysis or renal transplantation, or died related to renal disease (P < 0.013, log-rank test). The mortality imbalance seen in the core trial was not evident with the longer follow-up (25 deaths in the benazepril and 23 in the placebo group, before dialysis). These data clearly demonstrate a long-term beneficial effect in patients randomized to take benazepril during the core study, but because treatment during the extension period was not randomized, the results of this intention-to-treat analysis need to be interpreted with care.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

[Hypertension and the kidney].

In the past 30 years, the paradigms to explain the relation between hypertension and progression of renal disease have changed in a dramatic fashion. Thirty years ago it was believed that high blood pressure was necessary to permit the damaged kidney to maintain its function. In contrast, today solid evidence is available that blood pressure is the most important factor accelerating progressive loss of renal function. Furthermore, on the basis of recent observations, target blood pressure during antihypertensive therapy has been substantially lowered. Finally, it could be documented that for interfering with progressive loss of renal function, ACE (angiotensin converting enzyme) inhibitors and calcium channel blockers are superior to alternative antihypertensive agents (nephroprotection).

Animals↗
PubMed1996

[Permissive effect of PTH on vascular wall hypertrophy of intramyocardial arteries in experimental renal failure].

BACKGROUND: Abnormalities in cardiovascular structure e.g. LV hypertrophy and thickening of vessels (elastic and peripheral arteries, veins) are hallmarks of renal failure. Among other hormones parathyroid hormone (PTH) has been shown to affect cardiac function and has also been identified at a permissive factor for the activation of the cardiac interstitium leading to myocardial fibrosis. The present study was designed to examine whether PTH was also permissive for intramyocardial arteriolar wall thickening in an experimental model of renal failure. MATERIAL AND METHODS: Sham operated or subtotally nephrectomized rats (SNX) were parathyroidectomized (PTX) and received either saline or rat 1,34 PTH by osmotic minipump. After perfusion fixation, intramyocardial arterioles were assessed using stereological techniques (wall thickness, wall/lumen ratio, minimal lumen diameter, length density). RESULTS: Wall thickness of intramyocardial arterioles was significantly higher in SNX than in sham-op controls. SNX-PTX animals receiving solvent did not differ from sham-op controls while SNX-PTX animals receiving PTH had increased values which were comparable with those of SNX. In addition, PTH treated animals showed signs of marked vascular smooth-muscle cell and endothelial cell activation. CONCLUSIONS: The data suggest that intramyocardial arteriolar wall thickening in experimental renal failure and probable changes of vessel architecture in renal insufficiency in general are dependent upon the permissive effect of PTH.

Animals↗