Angiotensin II subtype AT1 receptor blockade prevents hypertension and renal insufficiency induced by chronic NO-synthase inhibition in rats.

Aim of the present study was to investigate the influence of the angiotensin II (ANG II) subtype 1 (AT(1)) receptor blockers fonsartan and losartan on blood pressure, cardiac -dynamics and -metabolism as well as functional and morphological changes in the kidney of rats after long-term inhibition of the nitric oxide (NO) synthase by N(G)-nitro-L-arginine methyl ester (L-NAME). Oral chronic treatment with L-NAME in a dose of 25 mg/kg/d over 6 weeks caused a significant increase in systolic blood pressure (198+/-13 mmHg) when compared to untreated rats (144+/-4 mmHg). Animals receiving simultaneously L-NAME and fonsartan (10 mg/kg/d) or losartan (30 mg/kg/d) were protected against blood pressure increase. L-NAME treatment caused a significant decrease in glomerular filtration rate (GFR) from 4.52+/-0.81 to 1.34+/-0.26 ml/kg(-1)/min(-1) and renal plasma flow (RPF) from 10.52+/-1.29 ml/kg(-1)/min(-1) to 5.66+/-1.06 ml/kg(-1)/min(-1). Co-treatment with fonsartan and losartan prevented L-NAME-induced reduction in GFR and RPF. There was no difference in urine, sodium and potassium excretion in groups under investigation. Plasma renin activity (PRA) was further stimulated by fonsartan and losartan treatment. L-NAME produced a significant elevation in urinary protein excretion which was antagonised by both AT(1) blockers. Isolated hearts from animals treated with L-NAME showed a significant prolongation in the duration of ventricular fibrillation and a significant decrease in coronary flow as compared to control hearts. Treatment with fonsartan and losartan significantly decreased the duration of ventricular fibrillation as compared to L-NAME group. In addition, both AT(1) blockers given alone significantly reduced the duration of ventricular fibrillation as compared to hearts from untreated controls. During ischemia the cytosolic enzymes lactate dehydrogenase and creatine kinase as well as lactate in the coronary effluent were significantly increased in the L-NAME group. Myocardial tissue values of glycogen, ATP, and creatine phosphate were decreased, whereas lactate was increased. Fonsartan and losartan treatment totally abolished these effects. Histological examination of kidneys revealed that simultaneous administration of fonsartan and losartan with L-NAME abolished L-NAME-induced arteriolar hyalinosis, segmental sclerosis of glomerular capillaries and focal tubular atrophies. In conclusion, long-term blockade of ANG II subtype AT(1) receptors by fonsartan and losartan prevented L-NAME-induced hypertension, renal insufficiency, as well as cardio-dynamic, cardio-metabolic, and morphological deteriorations.

S3226, a novel NHE3 inhibitor, attenuates ischemia-induced acute renal failure in rats.

BACKGROUND: Acute renal failure (ARF) remains a major problem in clinical nephrology characterized by sudden loss of the kidney function due to ischemia, trauma, and/or nephrotoxic drugs. The current therapy of ARF is symptomatic with mortality rates exceeding 50%. The aim of this study was to investigate the effects of an intravenous infusion of S3226 (3-[2-(3-guanidino-2-methyl-3-oxopropenyl)-5-methyl-phenyl]-N-isopropylidene-2-methyl-acrylamide dihydrochloride), a selective Na+/H+ exchange subtype 3 (NHE3) blocker, in ischemia-induced ARF in rats. In a second series of experiments cytosolic pH (pHi) changes in the kidney during ARF were continuously measured by means of nuclear magnetic resonance spectroscopy (MRS). METHODS: ARF was induced by bilateral occlusion of renal arteries for 40 minutes in three groups of anaesthetized Wistar rats. Control rats (N = 12) were infused with saline (6.25 mL/kg over 30 min) before occlusion and the compound groups (each N = 12) were infused with S3226 at a dose of 20 mg/kg over 30 minutes either before initiation of ischemia or immediately after release of clamps. Plasma creatinine (PCr), creatinine clearance (CCr), urine volume, sodium, and potassium excretion were determined up to seven days after release of clamps. In the second series of experiments in anaesthetized rats the left kidney was exposed by flank incision and fixed in a non-magnetic device. An inflatable cuff was positioned around the pedicle to induce ischemia without removing animals from the magnet. A double-tuned 1H-31P home-built surface coil was placed above the exposed kidney for the detection of pHi. RESULTS: At day 1 after ischemia CCr in the control group was significantly lower as compared to S3226-treated animals (control 0.30 +/- 0.05 vs. before 0.90 +/- 0.26 and reperfusion 0.83 +/- 0.15 mL/min/kg, respectively). PCr increased from 18 +/- 0.1 micromol/L before occlusion to 245 +/- 7 micromol/L in the control. The increase in PCr was significantly lower in the S3226 treated groups on days 1, 2, and 3 post-infusion. Fractional sodium excretion decreased significantly from 8.17% in the control to 1.42% and 1.88% in the treated groups. Renal pHi was significantly decreased by 0.15 units versus control during reperfusion. Histological examination of the kidneys on day 7 revealed pronounced reduction of tubular necrosis, dilatation, protein casts and cellular infiltration. CONCLUSIONS: These results demonstrate that an intravenous administration of S3226 acutely improves GFR and kidney function and structure in both treated groups. In addition, in a separate set of studies S3226 significantly decreased post-occlusion renal pHi values. Thus, the inhibition of NHE3 with S3226 may be beneficial in treatment of ischemic ARF.

[Renal morphometric investigations in pre-eclampsia-like syndrome in a Wistar rat model]. / Nierenmorphometrische Untersuchungen an einem Präeklampsie-ähnlichen Modell bei der Wistarratte.

OBJECTIVE: Etiology and pathogenesis of renal changes in pregnancy-induced hypertension (PIH) remain somewhat controversial. Reducing the uterine perfusion leads to the development of systemic hypertension in animal models. Aim of this study was to investigate the effect of systemic hypertension on the kidney during pregnancy. MATERIAL AND METHODS: A rat model was used and the degree of the renal changes was quantified by morphometry. Normotensive pregnant and virgin animals served as a control. RESULTS: Hypertensive animals showed a decrease of the intravascular space in comparison to the cellular component. This difference was significant not only in pregnant (p = 0.0026) but also in virgin (p = 0.001) animals. CONCLUSIONS: These findings indicate that renal changes are usually found in normotensive pregnancies, while PIH strongly aggravates these changes.

Nephroprotection by long-term ACE inhibition with ramipril in spontaneously hypertensive stroke prone rats.

BACKGROUND: The effect of life-long treatment with the ACE inhibitor ramipril on hypertension-induced histological changes in the kidney was tested in stroke-prone spontaneously hypertensive rats (SHR-SP). METHODS: One-month-old pre-hypertensive SHR-SP were randomized into three groups of 45 animals each, and exposed via drinking water for their lifetime to a dose of: 1 mg.kg-1.d-1 ramipril (antihypertensive dose, HRA); 10 micrograms.kg-1.d-1 slight dose of ramipril (non-antihypertensive dose, LRA); or placebo. Histological and biochemical assessments were conducted after 15 months in ten rats each, when about 80% of the placebo group had died. RESULTS: Kidneys from placebo treated SHR-SP showed pronounced arterial wall hypertrophy and sclerosis, arterial fibrinoid necrosis, glomerulopathy and tubular interstitial injury that were, in concert with normalized blood pressure, completely prevented by HRA treatment. LRA treatment did not affect any blood pressure increase, and also attenuated the development of arterial wall hypertrophy, sclerosis and arterial fibrinoid necrosis, though to a minor extent only, but did not change glomerular and tubulointerstitial degeneration. These effects of ramipril were associated with a dose-dependent inhibition of plasma and renal tissue ACE activities as well as lower serum concentrations of creatinine, but there were no changes in serum potassium. CONCLUSIONS: Life-long HRA-induced ACE inhibition protects against hypertension-induced renal damages in SHR-SP. This is associated with a doubling of the lifespan in these animals.

Subchronic intravenous toxicity studies with gamma-cyclodextrin in rats.

The toxicity of gamma-cyclodextrin (gamma-CD), a cyclic polymer of 8 alpha-1,4-linked glucopyranosyl units with potential applications in food and pharmaceutical preparations, was examined in two toxicity studies in rats with intravenous administration of gamma-CD for 1 and 3 months, respectively. Each study comprised four groups of 15 rats/sex each. In the 1-month study, gamma-CD was administered to the four groups at daily doses of 0 (controls), 200, 630, or 2000 mg/kg body wt, respectively. In the 3-month study, dose levels of 0, 60, 120, and 600 mg/kg body wt were tested. gamma-CD was administered by injection of an aqueous solution in the tail vein. At the end of the treatment period, 10 rats/sex/group were killed. The remaining 5 rats continued the study without treatment (recovery period) for 4 weeks (1-month study) or 5 weeks (3-month study). The treatment was generally well tolerated and there were no mortalities in either study. Mean body weights tended to be slightly reduced during the first and second week in the groups receiving gamma-CD at doses of >/=600 mg/kg body wt. Thereafter, body weights did not differ between treated groups and controls. Examination of standard hematological parameters at the end of the treatment period revealed decreased erythrocyte counts, hemoglobin, hematocrit values, and thrombocyte counts in both studies at gamma-CD doses of >/=600 mg/kg body wt. Concomitantly, the relative weight of the spleen was increased. In the high-dose group of the 1-month study, hemoglobin was detected in the urine. It is likely that a direct interaction of the injected gamma-CD with blood cells accounts for these effects. Examination of standard clinicochemical parameters at the end of the treatment period did not reveal any changes that would point to the liver as a target organ for gamma-CD toxicity. This was confirmed by the absence of histopathological changes in the liver. The only noteworthy observation was an increase of serum urea in the high-dose group (either sex) of the 1-month study and in males of the high-dose group of the 3-month study, suggesting a slight impairment of the renal function. On histopathological examination, reabsorptive vacuolation was seen in the renal tubular epithelium of some rats receiving gamma-CD at doses of 630 or 600 mg/kg body wt in the 1- and 3-month study, respectively. In the high-dose group of the 1-month study, all animals exhibited this morphological effect. However, degenerative changes were not observed in the kidneys, and the vacuolation was fully reversible on cessation of the treatment. The occurrence of absorptive vacuolation was attributed to the presence of gamma-CD in urine (parenterally administered gamma-CD is excreted unchanged in the urine). Simple or focal hyperplasia of the urinary bladder epithelium was observed in some animals of the high-dose group of the 3-month study. This hyperplasia was not seen at the end of the recovery period and, therefore, was considered to be a reactive response to the treatment. The most prominent morphological effect was an accumulation of phagocytosing alveolar macrophages (histiocytosis) in the lungs of rats receiving gamma-CD at a dose of >/=600 mg/kg body wt. This effect was associated with an increase of relative lung weights. However, degenerative changes (fibrosis) were not seen, and at the end of the recovery period only some small residual changes were noted in the lungs of a few animals. In conclusion, daily intravenous gamma-CD doses of 120-200 mg/kg body wt were tolerated without adverse effects. The changes observed at higher dose levels (>/=600-630 mg/kg body wt) were reversible on cessation of the treatment and are considered to be biochemical responses, without toxicological relevance, to the presence of transiently high concentrations of gamma-CD in the circulating blood.

Ramipril prevents the detrimental sequels of chronic NO synthase inhibition in rats: hypertension, cardiac hypertrophy and renal insufficiency.

Inhibition of the angiotensin converting enzyme (ACE) with ramipril was studied in male Wistar rats during long-term inhibition of nitric oxide (NO) synthase by NG-nitro-L-arginine methyl ester (L-NAME). Chronic treatment with L-NAME in a dose of 25 mg/kg per day over 6 weeks caused myocardial hypertrophy and a significant increase in systolic blood pressure (245 +/- 16 mmHg) as compared to controls (155 +/- 4 mmHg). Animals receiving simultaneously L-NAME and ramipril were protected against blood pressure increase and partially against myocardial hypertrophy. L-NAME caused a significant reduction in glomerular filtration rate (GFR: 2.56 +/- 0.73 ml.kg-1.min-1) and renal plasma flow (RPF: 6.93 +/- 1.70 ml.kg-1.min-1) as compared to control (GFR: 7.29 +/- 0.69, RPF: 21.36 +/- 2.33 ml.kg-1.min-1). Addition of ramipril prevented L-NAME-induced reduction in GFR and renal plasma flow. L-NAME produced an elevation in urinary protein excretion and serum creatinine and a decrease in potassium excretion which was antagonised by ramipril. L-NAME-induced increase in plasma renin activity (PRA) was further elevated with ramipril treatment. Isolated hearts from rats treated with L-NAME showed increased post-ischaemic reperfusion injuries. Compared to controls duration of ventricular fibrillation was increased and coronary flow reduced. During ischemia the cytosolic enzymes lactate dehydrogenase and creatine kinase, as well as lactate in the venous effluent were increased. Myocardial tissue values of glycogen, ATP, and creatine phosphate were decreased, whereas lactate was increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of the acute graft-versus-host disease (GVHD) in rats by the immunomodulating drug leflunomide.

The grafting of immunocompetent allogeneic cells into MHC-discordant, genetically nonresponsive F1 hybrids of inbred rat strains consistently leads to an acute, lethal graft-versus-host disease (GVHD). The novel immunomodulating drug leflunomide, which has been shown to be efficacious in animal models of autoimmunity and adverse transplantation reactions, was studied in a rat model of GVHD. It was found that this drug not only was a powerful agent to prevent this otherwise terminal disorder, but was also proficient when used as a therapy of an established GVHD. Since leflunomide has been shown to be efficacious and safe in patients with chronic rheumatoid arthritis, it would also be reasonable to investigate this drug in clinical trials for bone marrow transplantation and GVHD in human beings.

Leflunomide (HWA 486) inhibits experimental autoimmune tubulointerstitial nephritis in rats.

Experimental tubulointerstitial nephritis (TIN), induced in Brown Norway rats, is an autoimmune disorder in which afflicted animals display high levels of serum autoantibodies directed against antigens present on the tubular basement membrane (TBM). Serious functional damage, due to lesions of the kidney cortex, is evident 10 days after disease initiation. In an earlier study, we could show that cyclosporin A (CsA), an immunosuppressive drug, effectively prevented the onset of this illness, although it did not inhibit the formation of TBM autoantibodies. In the present study, the protective effects of CsA in autoimmune TIN was compared to those of drugs currently used to combat inflammatory ailments (i.e. prednisolone, indomethacin, naproxen, azathioprine) and a novel immunomodulating agent, leflunomide (HWA 486). Leflunomide is known to specifically inhibit the formation of T-dependent antibodies and is effective in preventing and curing animal autoimmune diseases, i.e. adjuvant arthritis disease of rats and murine lupus-like disorders. We found that not only could leflunomide inhibit TIN, but the drug-effects seemed to be more effective than those of CsA. Further, leflunomide was extremely effective in inhibiting the formation of autoantibodies to TBM, whereas CsA displayed only partial suppression. Neither prednisolone, indomethacin nor naproxen were effective in reducing the autoantibody titer, and did not offer any protection to the development of this disease. Together with the known effects on other autoimmune diseases we conclude that leflunomide is a novel immunointerventive drug protecting against several types of autoimmunity.

[Clinical pathology of the glomerulus--from phenomenon to entity. The membranous lesion]. / Klinische Pathologie des Glomerulus--vom Phänomen zur Entität. Die membranöse Läsion.

Characteristics of the membranous lesion are usually the capillary wall thickening in morphology and the clinical manifestation of a nephrotic syndrome. As entities of such a lesion the following types of glomerulonephritis (GN) could be considered: (peri-) membranous GN, garland type of postinfectious GN, and membranoproliferative (MP) GN. The morphological, especially the electronmicroscopical observations relative to separate immune deposit locations in the capillary wall--subendothelial, intramembranous, subepithelial--are the basis to differentiate the diseases as entities. The characteristic finding of the (peri-) membranous GN is the presence of subepithelial immune deposits along the capillary walls, which are separated by "spikes" and later on are incorporated into the basement membrane, while some of the deposits became rarefied; on the other hand, new subepithelial deposits can be observed when the disease of the most common idiopathic form starts again after a period of remission.--The deposits of the garland type of the postinfectious GN--the disease is more often a chronic progressive process than the other types of postinfectious GN--are in a subepithelial location. In contrast to the former the deposits vary in size and number and only some capillary walls are affected.--In type I of the MPGN the immune deposits are located mainly in a subendothelial position, often together with a mesangial interposition in such a manner, that the capillary wall has the appearance of "double contour" histologically. The most striking change of type II is the presence of dense deposits in the lamina densa of the capillary basement membrane ("dense deposit GN"). In type III of MPGN the deposits are located in all three positions of the capillary wall--subendothelial, intramembranous, subepithelial--and the lamina densa is markedly disrupted (little or no affinity for silver in thin sections after silver impregnation). Concerning the entity of the 3 types of MPGN, the depression of serum complement and the complement activating C3-nephritis factor are persistent features of type II, while these findings are obvious only in 50% of type I and III-diseases.

Cyclosporin A inhibits autoimmune experimental tubulointerstitial nephritis.

Tubulointerstitial nephritis, regularly induced in Brown Norway rats by autosensitization with tubular basement membranes, appeared acutely at about 10 days and was completely inhibited by Cyclosporin A (CyA) when this was given before and at the time of onset of the disease. It did not recur after the end of therapy. In spite of this disease inhibition, autoantibodies against tubular basement membranes persisted in the circulation and in the kidney. It is therefore suggested that it is not so much the antibodies that are the decisive factors in the pathogenesis of this and other autoimmune diseases but, rather cellular factors that are directly influenced by CyA. Although in this model CyA application was a preventive measure, the experiments provide a cogent reason for the application of CyA as early as possible in acute and seriously damaging diseases.

[Biophysicochemical structures of the glomerular filter]. / Biophysikochemische Strukturen des glomerulären Filters.

The ultrastructural and the biophysical and biochemical qualities of glomerular permeability to protein molecules are reviewed. With regard to differently located immune deposition in human glomerulonephritis, description and discussion are addressed in a fixed order of layers: 1. endothelial-subendothelial, i.e. the endothelial cells with fenestrate and the lamina rara interna of the basement membrane (bm), 2. membranous, i.e. the lamina densa of the bm, 3. subepithelial-epithelial, i.e. the lamina rara externa of the bm and the podocytes with food processes and slit diaphragms. It is emphasized that the 3 layers act as gradually (coarse to fine) filter barriers. On the basis of well known structural peculiarities, in the last 10 years experimental studies revealed that the meshwork of type IV collagen and the negatively charged heparan sulfate-proteoglycans - "the glomerular polyanion" - are integrated in sieving of protein molecules. These components are differently located in the stratified cellular and extracellular layers of the glomerular filter and their combined action is the basis of a size, charge and configuration depended filtration of macromolecules. In this way the passage of the mostly negative charge blood proteins, especially albumin, is prevented under normal conditions.

[Familial Mediterranean fever]. / Familiäres Mittelmeerfieber.

After 10 years of disease a Turkish boy and his sister were diagnosed to suffer from familial Mediterranean fever. Because an elder brother showed the symptoms of recurrent attacks of fever, abdominal pain, arthralgias and nephrotic syndrome due to amyloidosis. When these symptoms occur in residents of the Mediterranean area, the diagnosis "Familial Mediterranean Fever" has to be taken into account.

Endocytotic activity in epitheloid and Langhans' giant cells. Tracer studies with ferritin in the tubulointerstitial (anti-TBM) nephritis model.

In the experimental tubulo-interstitial (anti-basement membrane) nephritis in the rat, electron microscopic studies after the in vivo microinjection of native ferritin in areas of granulomatous inflammation near the surface of the kidney indicate that epitheloid and multinucleate Langhans' giant cells are capable of endocytosis and particularly of micropinocytosis. This suggests the possibility that endocytotic activities as well as secretion phenomena are important in the immune defense mechanisms linked with these "specifically" developed cells.

[(Progressive papillomatosis of the common bile duct with tendency to malignant change) ]. / Progressive Gallenwegspapillomatose mit maligner Entartungstendenz.

Report of a case of progressive papillomatosis of the common bile duct from our hospital--the sixteenth described in the literature. For the first time it had been possible to diagnose the progressive papillomatosis of the common bile duct is a precancer state, this disease should be listed among the differential diagnosis of obstructive jaundice, when all other causes have been excluded. Confirmation of the diagnosis necessitates radical surgery, in order to guarantee optimal management.

Cell fusion as a mechanism for the formation of giant cells (Langhans' type). Autoradiographic findings in autoimmune tubulo-interstitial nephritis of the rat.

The formation of multinuclear giant cells of the Langhans' type in tubulo-interstitial auto-immune nephritis in the rat has been investigated by means of autoradiography. While in the majority of giant cells all nuclei were radiolabeled, in a few both labeled and unlabeled nuclei were present. This latter finding represents strong evidence in favour of the hypothesis that giant cells do not form by endomitotic processes but rather through fusion of certain precursor cells. According to previous studies this precursor cell population consists mainly of epitheloid cells, i.e. modified monocytes.

Lecithin-cholesterol-acyltransferase deficiency: autosomal recessive transmission in a large kindred.

Thirty-four members of a single Sardinian kindred with lecithin-cholesterol-acyltransferase deficiency have been studied. The kindred spans four generations and the parents of the two affected siblings are blood relatives. Segregation of the acyltransferase deficiency gene in the family clearly demonstrated an autosomal recessive mode of inheritance. Thirteen family members, including all obligate heterozygotes, had roughly half-normal acyltransferase activities (mean +/- S.D. = 0.39 +/- 0.06 mU/ml) when compared to 17 intrafamilial controls and spouses (mean +/- S.D. = 0.72 +/- 0.09 mU/ml) and 40 blood donors from Marburg/Lahn (mean +/- S.D. =0.76 +/- 0.1 mU/ml). Characterization of the heterozygotes did not reveal abnormalities in their plasma lipoproteins. LCAT deficiency and the beta-thalassaemia trait coexisting in this kindred segregated independently.

Characterization of cells involved in the formation of granuloma. An ultrastructural study on macrophages, epitheloid cells, and giant cells in experimental tubulo-interstitial nephritis.

In experimental tubulo-interstitial (anti-basement membrane) nephritis of the rat, granulomatous inflammation develops around immunologically altered tubular basement membranes. The present light- and electron microscopic studies indicate that in the course of the granulomatous reaction, tissue monocytes evolve from blood monocytes and pursue two independent pathways of differentation. On the one hand they may differentiate into macrophages ("distant from tubules") or, alternatively, into epitheloid cells ("adjacent to tubules"). The latter, through cell fusion, develop into multinucleated giant cells of the Langhans' type. The cytoplasmic components of the epitheloid cells and the multinucleated giant cells should be interpreted as an activation of cellular biosynthesis. Its products, upon being secreted at the immunodefective basement membrane, will obviously serve immune defense mechanisms.