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R B Sterzel

Publications and source records attributed to R B Sterzel.

At least 91 records · Page 5Linked to original sources
PubMed1986

Enhancement of glomerular mesangial cell neutral proteinase secretion by macrophages: role of interleukin 1.

We have examined the ability of rat mesangial cells to regulate neutral proteinase production in vitro. Mesangial cells constitutively produced gelatinase when cultured in serum-free medium, and enzyme production by these cells was inhibited by cycloheximide. Coculture with thioglycollate-elicited rat peritoneal macrophages resulted in enhanced gelatinase production. The increase in enzyme released correlated directly with the number of macrophages added. Conditioned medium from LPS-activated peritoneal macrophages also enhanced gelatinase production in a dose-dependent manner. Fractionation of these macrophage supernatants on Sephacryl S-200 revealed a predominant fraction of gelatinase-enhancing activity in a m.w. range between 10,000 and 20,000. These data suggested that the enhanced mesangial cell gelatinase production was mediated through the action of interleukin 1. This was confirmed by the finding that purified interleukin 1, prepared from LPS-stimulated rat peritoneal macrophages, stimulated mesangial cells to secrete gelatinase in a dose-dependent manner. These findings may be of significance in the understanding of the pro-inflammatory role of macrophages in immune-mediated glomerulonephritis.

Animals↗
PubMed1986

Interleukin 1 and the glomerular mesangium. I. Purification and characterization of a mesangial cell-derived autogrowth factor.

The proteins expressing interleukin 1 (IL 1) activity from rat peritoneal macrophages and cultured glomerular mesangial cells were compared after purification to apparent homogeneity. The purified IL 1 shared a number of biochemical features including m.w., charge, and specific activity. These findings were extended by the results of proteolytic peptide mapping, which revealed similar breakdown oligopeptides, confirming the close resemblance of these two IL 1 species produced by macrophages and mesangial cells. The purified mesangial cell IL 1 acts as an autocrine or paracrine growth factor. The local release of this cytokine may be an important factor in glomerular diseases characterized by mesangial proliferation and matrix expansion.

Animals↗
PubMed1986

Progressive glomerular sclerosis in experimental antiglomerular basement membrane glomerulonephritis.

A model of chronic progressive glomerular sclerosis in experimental antiglomerular basement membrane (anti-GBM) glomerulonephritis was developed in Wistar rats. Wistar rats given the accelerated form of anti-GBM anti-body glomerulonephritis initially developed significant proteinuria and renal insufficiency associated primarily with a decrease in glomerular filtration rate (GFR) with normal renal clearance of para-aminohippuric acid and with markedly reduced filtration fraction. The glomerular functional abnormalities were associated with marked glomerular hypercellularity due to leukocytic infiltration as well as proliferation of intrinsic glomerular cells with crescent formation. Late in the course of the disease, by day 21, GFR had fallen further, associated with a parallel decrease in the clearance of para-aminohippuric acid and a normal filtration fraction. At this stage, glomerular hypercellularity had diminished and was replaced by glomerular sclerosis. The model appears to be a reproducible form of chronic glomerulosclerosis and demonstrates that the chronic phase of glomerular basement membrane (GBM) glomerulonephritis is distinctly different from that of the acute phase. It provides a controllable setting to study the glomerular sclerotic process independent of the initial inflammatory changes.

Animals↗
PubMed1986

Atrial natriuretic factor determinations and chronic sodium homeostasis.

To examine the physiological role of atrial natriuretic factor (ANF) in the maintenance of sodium homeostasis under various conditions, we performed experiments in rats across a wide range of sodium intake, in rats with chronic renal insufficiency at extremes of sodium intake, and in rats given desoxycorticosterone acetate. After three weeks of a very low sodium diet, regular diet, or regular diet plus 1% saline as drinking water, no difference in plasma values of immunoreactive atrial natriuretic factor (IR-ANF) were identified, while rats at the lowest level of sodium intake had elevated atrial values. Normal rats, and rats with 5/6 nephrectomy has plasma values of IR-ANF which were no different irrespective of their sodium intake, nor were atrial values in these rats different. Although mineralocorticoid "escape" could be documented by changes in urine sodium excretion, neither plasma nor atrial IR-ANF values showed differences either at 24 or 72 hr after "escape". The data are consistent with previous observations that ANF serves the purpose of affecting rapid adjustments to large alterations in circulating fluid volume. Chronic high sodium intake, adaptation to renal insufficiency, and adjustment to the effect of mineralocorticoid do not appear to be associated with increased circulating plasma concentrations of IR-ANF.

Animals↗
PubMed1986

Cell culture approaches to the analysis of glomerular inflammation.

In this paper, we have attempted to provide an overview of the methods and findings of a large number of investigators who have dealt with an analysis of the glomerular inflammatory response using tissue culture techniques. These observations represent only a beginning. With the growing interest in this aspect of kidney disease, it is to anticipated that many further advancements in the understanding of the cell biology of the glomerulus are forthcoming. The translation of this fundamental information into new diagnostic and therapeutic modalities is an exciting challenge to investigative nephrology.

Animals↗
PubMed1986

Atriopeptin III kinetics and pharmacodynamics in normal and anephric rats.

To elucidate the disposition of atriopeptin III in plasma we performed experiments in normal and anephric rats. Bolus, i.v. atriopeptin III (250 ng) was given after which the rats were decapitated at 30-sec intervals. The half-life of atriopeptin III in normal rats was 26.5 sec, the volume of distribution was 352 ml and the plasma clearance was 500 ml/min. In anephric rats the half-life was 56.8 sec, the volume of distribution was 345 ml and the plasma clearance was 206 ml/min. In other rats atriopeptin III was given and urine was collected simultaneously. No atriopeptin III could be measured in the urine. We gave 0.0, 0.067, 0.125, 0.25, 0.5 and 1.0 ng/kg of bolus atriopeptin III to normal rats and measured effects on blood pressure, heart rate and plasma concentration at 30 sec, the time at which maximum effect on blood pressure occurred. Dose, change in blood pressure and plasma concentration were correlated. Heart rate increased, but not in a dose-dependent fashion. We conclude that atriopeptin III is cleared from rat plasma rapidly and that the kidneys account for 59% of its elimination by degradation rather than excretion. Because the effect of atriopeptin III on blood pressure is concentration-dependent, the transient changes exerted by atriopeptin III may be related to its rapid disappearance from plasma.

Animals↗
PubMed1986

No aggravation of the course of experimental glomerulonephritis in spontaneously hypertensive rats.

Functional and morphologic glomerular alterations induced by antiglomerular basement membrane (anti-GBM) nephritis were investigated in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto controls (WKY) for assessment of the role of systemic hypertension in immunologically mediated renal injury. Over a 6-week period serial measurements of systolic blood pressure (BP), serum creatinine (SCreat), creatinine clearance (CCreat), and urinary albumin excretion (UAlbV) were obtained with inulin clearances (CInulin) at the end of the study. Renal tissue was examined by light microscopy (LM), electron microscopy, immunofluorescence, flash 3H-thymidine autoradiography (AR), and staining for nonspecific esterase (NSE). Immunologic humoral response was evaluated by measurement of rat anti-rabbit IgG antibody production. At all time periods studied, SHR and WKY rats with anti-GBM nephritis demonstrated comparable elevations in SCreat and UAlb V as well as diminution of CCreat and CInulin as compared with non-nephritic control rats of each strain. In nephritic WKY rats mild hypertension developed, whereas in nephritic and control SHR rats marked elevations in BP developed. Morphologic injury as assessed by percent glomerular crescents and hypercellularity on LM, numbers of monocyte macrophages by NSE staining, immunofluorescence for IgG, C3, fibrinogen and Ia positivity, and numbers of glomerular 3H-thymidine-labeled cells by AR was notably comparable in both nephritic strains. Humoral antibody responses were also shown to be similar in all rats studied. These results demonstrate that the 5-week course of experimental anti-GBM nephritis is not exacerbated by systemic hypertension. Glomerular autoregulatory capacity may be important in determining the extent of immune-mediated renal injury.

Albuminuria↗
PubMed1986

Studies of glomerular mesangial uptake and processing of macromolecules. I. Effect of polyvinyl alcohol-induced macrophages on uptake of iron dextran.

The influence of prior glomerular mesangial uptake of a macromolecule that induces the infiltration of macrophages (M phi) into the mesangium on the uptake of a second macromolecule by the mesangium was studied in inbred Lewis rats. Renal transplantation of kidneys from rats previously injected with polyvinyl alcohol (PVA) was performed to avoid the potential influences of ongoing uptake of PVA and altered host milieu on the glomerular uptake of iron dextran (ID), a macromolecule that localizes primarily in the intrinsic mesangial cells of unmodified rats. In contrast to that in the recipient's native kidney, the uptake of ID was markedly increased in the glomeruli in kidneys previously exposed to PVA. This enhanced uptake was the consequence of the phagocytic activity of mesangial M phi elicited by and containing PVA since the site of increased ID content was shown by ultrastructural studies to be within mesangial M phi. Isogeneic renal transplantation per se did not influence mesangial function since the glomerular uptake of ID in donor and recipient kidneys was the same when donors were normal rats. In addition to the enhanced uptake of ID into lysosomes by mesangial M phi these cells were also much more active in the further processing of ID to ferritin particles within the cytoplasm than were intrinsic mesangial cells. These studies demonstrate that M phi attracted to the mesangium by a stimulus such as PVA may have important effects on the consequences of additional challenges to the mesangium.

Animals↗
PubMed1986

Mesangial cell hillocks. Nodular foci of exaggerated growth of cells and matrix in prolonged culture.

To examine the capability of glomerular mesangial cells (MCs) to produce extracellular matrix, the authors studied MCs in culture by light and electron microscopy as well as immunocytochemistry. MCs were obtained from isolated rat glomeruli and maintained up to 12 weeks in medium containing 20% fetal calf serum. MC outgrowth of primary culture and of up to three subcultures showed characteristic organization consisting of bands of elongated or stellate intertwined cells. After confluency at 10-16 days, MCs continued to grow in irregular multilayers. MCs produced extracellular matrix material within 2-4 days after plating, and large amounts of matrix accumulated with time. By 2-3 weeks, foci of exaggerated MC proliferation, matrix secretion, and necrotic cell debris formed nodular protrusions, which gradually produced large hillocks. Immunocytochemical studies of MC outgrowths were performed on culture plates or on sectioned material with the use of specific rabbit polyclonal antibodies to isolated matrix proteins and FITC-conjugated, affinity-purified second antibodies. Within 3 days of culture, MCs elaborated fibronectin and collagen Types I, III, IV, and V. With time, strands of matrix, notably in the central mass of hillocks, stained extensively for these constituents. Staining for laminin was less pronounced. Smooth muscle cell myosin was regularly found on distinct intracellular fibrils and in the extracellular material of hillocks. Electron microscopy revealed the hillocks to be composed of elongated cells on the surface and stellate cells intermingled with matrix and necrotic cell debris in the core. The results show that proliferating MCs can be maintained in homogeneous culture for a prolonged time period. MCs produce large amounts of the extracellular matrix proteins (Type IV and V collagen, fibronectin, laminin), which are found in normal glomeruli. Cultured MCs also produce interstitial collagen Types I and III. MC hillocks show the nodular accumulation of matrix similar to that seen in the mesangium of diseased glomeruli. It is concluded that the in vitro model of prolonged MC outgrowth may facilitate the investigation of factors that govern mesangial matrix production. Such a model could be used in examining the response of the mesangium to defined inflammatory or metabolic stimuli.

Animals↗
PubMed1984

Renal interstitial pressure and sodium excretion during hilar lymphatic ligation.

Because lymphatic vessels drain the cortical interstitium of the kidney, lymphatic drainage might modulate cortical interstitial pressure and tubular Na+ reabsorption. We investigated the effects of short-term hilar lymph duct ligation in the rat on renal interstitial hydraulic pressure (assessed from subcapsular pressure), tubular Na+ reabsorption, and renal hemodynamics in the basal state and during volume expansion with saline. Subcapsular pressure was higher in lymphatic-ligated than in sham-operated kidneys both in the basal state (5.9 +/- 0.3 vs. 2.1 +/- 0.3 mmHg) and during short-term volume expansion (8.4 +/- 0.7 vs. 3.5 +/- 0.3). Compared with contralateral control kidneys, lymphatic ligation increased the basal urine flow (V) (1.76 +/- 0.2 vs. 1.18 +/- 0.2 microliter X min-1 X 100 g-1) and urinary Na+ excretion (UNaV) (0.10 +/- 0.03 vs. 0.05 +/- 0.02 mumol X min-1 X 100 g-1), but urea excretion, osmolar clearance, glomerular filtration rate, renal plasma flow, and filtration fraction were unchanged. The increases in V and UNaV with lymphatic ligation were not seen in salt-depleted rats but both were augmented by short-term volume expansion with saline. Sympathetic activation and inhibition by carotid occlusion and ganglionic blockade, respectively, elicited the same changes in vascular resistance in lymphatic-ligated and control kidneys. In conclusion, 1) lymphatic drainage is required to maintain a low renal cortical interstitial hydraulic pressure; 2) lymphatic ligation decreases Na+ and fluid reabsorption; 3) the natriuretic and diuretic effects of lymphatic ligation are not due to major changes in renal innervation or renal hemodynamics or to changes in osmolar or urea excretion but depend on the degree of extracellular fluid volume expansion.

Absorption↗
PubMed1984

Nitrendipine reverses vasoconstriction and renal hemodynamic changes in experimental hypertension.

Nitrendipine, a calcium entry blocker, was administered by gavage (3 mg/100 g body weight/day) to rats with prolonged angiotensin-II-(AII) induced hypertension. AII was infused by osmotic minipump implanted subcutaneously. Persistent hypertension was established after 5 days. Normotensive control rats had empty sham pumps. Nitrendipine, administered from day 11 to 15 after pump implantation, normalized blood pressure consistently in AII rats, whereas it had no significant hypotensive effect in controls. Renal clearance experiments in anesthetized rats revealed that nitrendipine reversed all noted abnormalities of AII-infused rats, including hypertension and reductions in glomerular filtration rate, renal blood flow, and urinary sodium excretion. When receiving nitrendipine, sham controls did not show significant changes in blood pressure, renal function, or natriuresis. The results demonstrate that oral administration of nitrendipine is highly effective in normalizing blood pressure during prolonged AII-induced hypertension. The antihypertensive effect is achieved by this calcium entry blocker's vasodilatory action, supported by a marked natriuretic effect. By contrast, blood pressure and renal function of normotensive control rats were not appreciably affected by oral nitrendipine.

Angiotensin II↗
PubMed1983

Cell renewal of glomerular cell types in normal rats. An autoradiographic analysis.

Normal adult Sprague-Dawley rats received either a single or repetitive injection of the DNA precursor 3H-thymidine (3H-TdR). For autoradiography semi-thin sections were prepared 2 hr to 14 days after labeling. The majority of labeled cells noted in glomerular tufts were endothelial cells. Mesangial cells had a lower production rate. Podocytes revealed no evidence of proliferation. Bowman's capsule cells showed a higher labeling index than tuft cells at all times. Neither the urinary nor the vascular pole was found to be a proliferative zone for Bowman's capsule cells. The flash and repetitive labeling experiments demonstrated a constant rate of cell renewal of about 1% per day, resulting in a long life span for endothelial and mesangial cells as well as Bowman's capsule cells. These data provide a basis for cell kinetic studies in models of glomerular diseases.

Animals↗
PubMed1983

Neutral proteinase activity produced in vitro by cells of the glomerular mesangium.

Cells derived from isolated glomerular tufts of rats were studied in primary tissue culture after the removal of epithelial cells by collagenase treatment. The cultured cells, fusiform or stellate in shape, grew readily over a 12-day period. Immunofluorescence staining was positive for myosin and fibronectin, while negative for Factor VIII, suggesting that the outgrowing cells were derived from the glomerular mesangium. In serum-free culture, these cells produced neutral proteinase activity that occurred as a latent trypsin-activable form (apparent molecular weight range, 78,000 to 100,000 daltons) and in an active form (44,000 to 58,000 daltons). Neutral proteinase activity was inhibited by EDTA and by cysteine, and exhibited a pH optimum of 7.2 to 7.8, characteristic of an extracellularly active metalloendopeptidase. The culture supernate which contained the neutral proteinase activity was capable of degrading purified rat glomerular basement membrane. The release of hydroxyproline-containing fragments from the basement membrane indicated that degradation of the type IV collagen component of the basement membrane was occurring. These findings suggest that the neutral proteinase activity generated by mesangium-derived cells may play a role in the physiologic turnover of glomerular structural proteins in vivo.

Animals↗
PubMed1983

Uptake of polyvinyl alcohol by macrophages in the glomerular mesangium of rats. Histologic and functional studies.

Rats received daily subcutaneous injections of the synthetic polysaccharide polyvinyl alcohol (PVA) for 1-28 days. The amount of PVA localized in the glomerular mesangium increased progressively during this time. By 28 days, all glomeruli showed extensive intracellular mesangial sequestrations of PVA, causing marked widening of mesangial areas, while the peripheral capillary loops were unaltered. Overall glomerular hypercellularity was mild to moderate, occurring mainly in areas of PVA deposition. Follow-up studies after 6, 12, 26, and 40 weeks revealed partial reduction of glomerular PVA masses. The PVA deposits were frequently associated with nonspecific esterase (NSE)-positive cells. The number of NSE-positive cells per glomerular tuft section increased from 0.1 in controls, to 2.1, 4.0, and 4.5 after 3, 14, and 28 days of PVA treatment, respectively. Similarly, glomerular counts for Ia-antigen-bearing cells rose from 2.1 in controls to 4.8 on Day 3 and showed further increases at later time periods with confluent staining of clusters of Ia-positive cells. In glomeruli, Ia-bearing cells were mainly noted in PVA-positive mesangial areas. These results indicate that PVA is taken up in the glomerulus primarily by cells that are NSE- and Ia-antigen-positive, suggesting that these cells are activated blood-borne monocyte-macrophages that sequester this polysaccharide. Clearance studies revealed that the glomerular filtration rate and effective renal plasma flow remained normal after 4 weeks of PVA injections. PVA-treated rats showed only mild elevations of urinary protein excretion. These findings indicate that confinement of marked structural and cellular alterations to the mesangium, even including the presence of infiltrating monocyte-macrophages, is compatible with absent or minimal dysfunction of the glomerular ultrafilter.

Animals↗
PubMed1983

Role of macrophages in the glomerular mesangial uptake of polyvinyl alcohol in rats.

Glomerular mesangial cell populations were characterized through sequential morphologic studies after injection of polyvinyl alcohol (PVA), a synthetic polysaccharide previously shown to accumulate in the mesangium. Renal tissue was obtained from groups of rats, 1 day to 28 days after initial subcutaneous injection of PVA, and studied by transmission electron microscopy and fluorescence microscopy using monoclonal antibodies to rat Ia. PVA was initially present in areas of attenuated mesangial matrix. Subsequently, only a small fraction of PVA was associated with "classical" mesangial cells. By 3 days, variable degrees of glomerular hypercellularity were noted, and PVA appeared within phagocytic vacuoles of immature macrophages in the mesangium and in occasional endocytic vacuoles of endothelial and mesangial cells. At later time points, increasing quantities of PVA were found within the large confluent phagolysosomes of more mature mesangial macrophages. By 2 weeks, features of epithelioid transformation were evident. By 3 and 4 weeks many glomeruli contained several mesangial microgranulomas, i.e., collections of epithelioid cells of variable degree of maturation, including giant cells. An increase in Ia-positive cells in glomeruli corresponded closely to the increase in numbers of cells with ultrastructural characteristics of macrophages and epithelioid cells within mesangial regions. These studies demonstrate a primary role for macrophages in the uptake of PVA, a process ultimately leading to granuloma formation in the mesangium.

Animals↗
PubMed1983

Role of angiotensin II-induced renal functional changes in mesangial deposition of exogenous ferritin in rats.

The relationship between acute angiotensin II (AII)-induced functional changes of the kidney and mesangial localization of macromolecules was investigated in rats utilizing native horse spleen ferritin as an exogenous tracer. One group of rats received a 30-minute infusion of a pressor dose of AII. Ten minutes before sacrifice they were injected with a single intravenous dose of ferritin. In the other group the injection of ferritin was followed by an 80-minute infusion of AII. Serial measurements of systolic blood pressure (BP), inulin clearance (CIN), p-aminohippuric acid (PAH) clearance (CPAH), filtration fraction (FF), and excretion of albumin (UAlb V) and ferritin (UFe V) were obtained. Although AII-treated rats showed significant increases of BP, FF, UAlb V and UFe V over controls, they were not different from controls with respect to plasma ferritin concentrations, renal delivery of ferritin, CPAH, and CIN. Semiquantitative evaluation of renal tissue by immunofluorescence and electron microscopy revealed that at 10 minutes no differences in the early and mild deposition of ferritin in the mesangium were appreciable. In contrast, at 80 minutes, AII-treated rats had markedly enhanced mesangial localization of ferritin when compared with controls. In the animals infused with AII for 80 minutes, the amount of glomerular ferritin deposition correlated strongly with UAlb V and UFe V. Combining the results of both, AII and controls at 80 minutes, these correlations were still present, in addition to weaker yet significant correlations of glomerular ferritin with BP and absolute changes of FF during the treatment period. The results show that, over a time interval of 80 minutes, AII augments the mesangial accumulation of ferritin in the presence of normal tracer delivery to the kidney. The enhanced mesangial localization of ferritin is observed under circumstances where overall increases in glomerular capillary permeability to albumin and ferritin are present. Although the precise mechanisms underlying these effects are not identified, AII-induced changes of glomerular microcirculatory forces and permeability properties of the glomerular capillary appear to be involved.

Albuminuria↗