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J R Diamond

Publications and source records attributed to J R Diamond.

At least 19 recordsLinked to original sources
PubMed1992

Diabetic glomerulosclerosis and chronic renal failure with absent-to-minimal microalbuminuria.

We report the case of an elderly black woman with a 20-year history of insulin-independent diabetes mellitus (IDDM), chronic renal failure, hypertension, proliferative retinopathy, and classical histologic features of diabetic glomerulosclerosis on renal biopsy. Repeat determinations of urinary albumin excretion rates failed to disclose significant microalbuminuria. This presentation should remind the clinician that a small minority of patients with IDDM of long duration may have severe diabetic glomerulosclerosis and renal insufficiency without detectable microalbuminuria.

Aged↗
PubMed1992

The role of reactive oxygen species in animal models of glomerular disease.

Reactive oxygen metabolites have been demonstrated to play a pathobiologic role in a number of experimental models of both immune and nonimmune glomerular injury. Using scavenging substances, enzyme inhibitors, and transition metal chelators, all of the major reactive oxygen metabolites have been implicated in glomerular injury. In addition, in neutrophil-dependent models, interaction between neutrophil-derived myeloperoxidase and halide anions has been shown to be involved in glomerular damage, as well as halogenation of the glomerular basement membrane (GBM). Finally, recent attention has focused on the role of cytokines (perhaps elaborated by infiltrating monocytes/macrophages) in stimulating mesangial cells (MC) to produce reactive oxygen species. Theoretically, this pathobiologic sequence could further enhance an inflammatory state within the glomerular tuft and enable the propagation of initial glomerular injury, which may be associated with an increase in monocyte infiltration into the mesangium, to glomerulosclerosis in experimental models that manifest this transition.

Animals↗
PubMed1992

Progressive albuminuria and glomerulosclerosis in a rat model of chronic renal allograft rejection.

A significant proportion of renal allografts fail within several months or years after transplantation, primarily because of chronic rejection. The etiology and pathophysiology of this condition remain unclear. We studied the renal function, morphology, and immunohistology, in parallel, among F344-to-Lewis allografts (n = 23) and isografts (n = 13) over the course of 24 weeks. Only an initial 10-day course of CsA (5 mg/kg/day) was given to both groups to prevent acute rejection. Hypertension did not develop, although awake systolic blood pressure was significantly higher in allografts at the end of the study. Significant differences in urine albumin excretion (UalbV) between isografts and allografts were evident as early as 4 weeks after engraftment but rose dramatically by 20 weeks (3.3 +/- 0.7 vs. 21.2 +/- 3.7 mg/day, respectively, P < .001). This pattern continued until the conclusion of the study (5.0 +/- 1.1 vs. 53.5 +/- 7.6 mg/day, P < .001). Serum creatinine values were only significantly elevated in allografts at 16 weeks, which temporally corresponded to the dramatic increase in UalbV. However, renal blood flow and glomerular filtration rate, measured by paraaminohippurate and inulin clearances, respectively, were significantly lower in allografted organs, at 24 weeks. The frequency of glomerulosclerosis lesions was significantly increased in allografted kidneys at 24 weeks and correlated with UalbV values. Glomerular localization of mononuclear leukocyte subsets were equivalent between allografts and isografts; however, the numbers of interstitial macrophages, CD8+, and pan-T-cells were all significantly greater in allografts at 24 weeks. The infiltration of significantly greater numbers of macrophages and lymphocytes into the tubulointerstitium of the allograft group suggests a mononuclear leukocyte effector cell mediation of the progressive glomerular abnormalities in this model of chronic renal allograft rejection in the rat.

Albuminuria↗
PubMed1992

A putative role of hypercholesterolemia in progressive glomerular injury.

Recently, much experimental evidence has accumulated contending that hypercholesterolemia is an aggravating factor in the progression of initial glomerular injury to glomerulosclerosis. Many of the features of progressive glomerular disease share biological properties with those of atherosclerosis, and data suggesting a noxious role for oxidized low-density lipoprotein in the glomerulosclerosis process are emerging. This review discusses these issues and examines the pathobiology of cholesterol-induced glomerular injury.

Animals↗
PubMed1992

Macrophages mediate adverse effects of cholesterol feeding in experimental nephrosis.

We tested whether the deleterious effects of hypercholesterolemia, in a progressive glomerular disease model, may be mediated by infiltrating renal macrophages. A single sublethal dose of whole body X-irradiation (XI) delivered to rats with acute puromycin aminonucleoside (PA) nephrosis fed a high-cholesterol (HC) diet resulted in significantly greater inulin and p-aminohippurate (PAH) clearances at 11 days after PA without any alterations in circulating lipid levels, in contrast to nonirradiated HC-fed nephrotic controls. This functional protection was associated with significant declines in both glomerular and cortical interstitial macrophage number. Over the course of this 16-wk model, HC-fed PA rats had significantly less albuminuria as well as significantly fewer glomerulosclerosis (GS) lesions and less mesangial matrix expansion at the end of the study despite an equivalent degree of sustained hypercholesterolemia. This data suggests that reducing the infiltrating glomerular and cortical interstitial macrophage burden with XI during acute PA nephrosis, unaccompanied by any hypolipidemic effect, produces not only early salutary effects on renal function but also a significant amelioration of the progressive glomerulopathic features of this model. This is consistent with the hypothesis that the infiltrating renal macrophage, in large part, directly mediates the adverse effects of hypercholesterolemia in this model.

Acute Disease↗
PubMed1992

Glomerular macrophages and the mesangial proliferative response in the experimental nephrotic syndrome.

Mesangial cell proliferation, which is a harbinger of glomerulosclerosis, occurs in both immune and nonimmune glomerulopathies. The proximity of infiltrating glomerular macrophages to the contractile mesangial cells during acute puromycin aminonucleoside (PA) nephrosis suggests the possibility of a paracrine effect on mesangial cell growth. To test this, three maneuvers to either raise or lower the glomerular macrophage number during acute PA nephrosis (2 weeks after PA) were employed: 1) an essential fatty acid-deficient (EFAD) diet; 2) a cholesterol-supplemented diet (CSD); and 3) a single dose (600 rad) whole-body X-irradiation (XI) given to CSD-fed PA rats. Both the glomerular macrophage number and proliferation within the mesangium were evaluated immunohistochemically with ED-1, a mouse monoclonal anti-rat macrophage label, and 19A2, a mouse monoclonal anti-proliferating cell nuclear antigen (PCNA)/cyclin antibody, respectively. Immunohistochemical detection of 5'-bromo-2'-deoxyuridine (BrdU) incorporation confirmed that proliferation was occurring within the mesangial zones. The EFAD diet significantly reduced both the glomerular macrophage and PCNA/cyclin-positive cell number at 2 weeks after PA with a positive correlation (r = 0.89, P < 0.05). The CSD maneuver significantly increased both the glomerular macrophage and PCNA/cyclin cell number with a strong degree of correlation (r = 0.95, P < 0.01). X-irradiation administered to CSD-fed PA rats significantly lowered both the glomerular macrophage and PCNA/cyclin-positive cell number at 2 weeks. In all groups, the glomerular tufts did not express muscle actin using HHF 35, a specific immunolabel, suggesting that the proliferation in this model is not related to direct mesangial cell injury. This study shows that maneuvers that modulate the glomerular macrophage number are also associated with corresponding changes in the number of proliferating cells within the mesangium, suggesting a paracrine growth stimulation by the infiltrating macrophage during acute PA nephrosis. The infiltrating glomerular macrophage may be an effector mechanism for the propagation of initial glomerular injury to glomerulosclerosis by augmenting mesangial cell proliferation early in the course of this nonimmune progressive glomerulopathy.

Animals↗
PubMed1991

Sublethal X-irradiation during acute puromycin nephrosis prevents late renal injury: role of macrophages.

Acute puromycin aminonucleoside (PA) nephrosis is associated with a surge in the glomerular macrophage number. Whole body X-irradiation (XI) was used to assess whether bone marrow depression, which depletes normal rat glomeruli of macrophages, is efficacious in ameliorating progressive glomerular disease. A solitary, sublethal dose of XI (600 rad) was administered 3 days after PA delivery to rats (PA/XI) that were followed for 18 wk. In contrast to a sham-irradiated nephrotic cohort (PA/Sham), the PA/XI rats had a complete prevention of the recurrent albuminuria and manifested a significant reduction in the percent of glomeruli exhibiting glomerulosclerosis (GS) lesions at 18 wk after PA. XI significantly reduced the glomerular and interstitial macrophage number as well as the circulating white blood and monocyte counts during peak albuminuria. This protection was independent of the magnitude of the acute albuminuria and elevations in the circulating lipid levels. These data show that whole body XI delivered during acute nephrosis is capable of preventing progressive glomerular disease in association with a reduction in the glomerular and interstitial macrophage number. Additionally, this study suggests that this immune effector cell is important in mediating the propagation of initial glomerular injury to GS.

Albuminuria↗
PubMed1991

Glomerular tumor necrosis factor and interleukin 1 during acute aminonucleoside nephrosis. An immunohistochemical study.

Acute aminonucleoside nephrosis progresses to glomerulosclerosis. The mechanisms for this phenomenon are not entirely known. Our objectives were to identify macrophage (m phi)-derived peptide growth factors (i.e., tumor necrosis factor and interleukin 1), using immunohistochemical means, in glomeruli of rats with acute aminonucleoside nephrosis. Recently, a role for glomerular m phi s has been suggested as one of the possible mechanisms responsible for this transition from acute glomerular injury to glomerulosclerosis. Since peptide growth factors are elaborated by m phi s and produce alterations in mesangial cell proliferation and protein biosynthesis, we investigated whether these cytokines were present in glomeruli during aminonucleoside nephrosis, which has been typically regarded as a nonimmune toxic glomerulopathy. Fourteen days after puromycin aminonucleoside (PA) delivery, nephrotic control rats (PA/control) and nephrotic animals that had been maintained on an essential fatty acid-deficient (EFAD) diet (PA/EFAD) for 8 weeks before PA, manifested cytoplasmic tumor necrosis factor and interleukin 1 within cells located in the glomerular mesangium as detected by immunohistochemical means. Despite equivalent levels of albuminuria and fasting total cholesterol during peak nephrosis, the PA/EFAD rats had significant reductions in the number of tumor necrosis factor-positive glomerular cells (1.8 +/- 0.1 versus 8.5 +/- 0.4, p less than .001) and interleukin 1-positive glomerular cells (1.5 +/- 0.1 versus 7.2 +/- 0.5, p less than .001) in comparison with the PA/control group. These data correlated with a reduction in the number of ED-1-positive cells (i.e. glomerular m phi s) in glomeruli of PA/EFAD animals as compared with PA/control rats (2.2 +/- 0.3 versus 10.9 +/- 1.4, p less than .001), suggesting that m phi-derived peptide growth factors may be important determinants in initiating a pathobiologic sequence culminating in glomerulosclerosis in this model.

Animals↗
PubMed1991

Analogous pathobiologic mechanisms in glomerulosclerosis and atherosclerosis.

This paper attempts to further delineate the similar pathobiologic mechanisms involved in the atherosclerosis and glomerulosclerosis processes. In particular, recent experimental data in models of both processes have focused on the roles of hypercholesterolemia and the monocyte/macrophage in propagating these lesions. In a nonimmune toxic glomerulopathy, chronic aminonucleoside nephrosis, our laboratory has demonstrated an important role for the glomerular macrophage, which is increased in number in temporal association with the onset of albuminuria, in propagating initial glomerular injury to glomerulosclerosis. In addition, a superimposition of dietary hypercholesterolemia further augments this heightened glomerular macrophage number and activates systemic macrophages. These data suggest a synergistic role between the hypercholesterolemia of nephrosis and the surge in glomerular macrophage number following initial glomerular injury in establishing a cascade of intercellular events that culminates in glomerulosclerosis. The intriguing histologic and immunohistochemical similarities between the evolving fatty streak in the atherosclerotic vessel wall and the progressive glomerular lesion leading to glomerulosclerosis suggest analogous pathobiologic mechanisms.

Animals↗
PubMed1990

Cholestyramine resin ameliorates chronic aminonucleoside nephrosis.

We chose to assess the role of cholesterol reduction in chronic aminonucleoside nephrosis by pharmacologically lowering serum cholesterol with cholestyramine. Two groups of rats were made nephrotic with a single intravenous dose of puromycin aminonucleoside (PA): one group (PA/resin) received 5% (w:w in diet) cholestyramine resin and the dietary control group (PA/cell) received 5% cellulose. Cholestyramine-treated rats demonstrated significant functional and histological protection. Recurrent proteinuria was significantly lower in PA/resin animals. Whole-kidney glomerular filtration rate in the PA/resin group was preserved at a level equivalent to normal age-matched control rats whereas the PA/cell group had a significantly lower value than did the normal animals. The extent of segmental glomerulosclerosis 24 wk after PA delivery was significantly lower in the PA/resin group. These results suggest a role for hyperlipidemia as one of the mechanisms involved in the pathogenesis of progressive glomerular disease.

Animals↗
PubMed1990

Effects of dietary interventions on glomerular pathophysiology.

Numerous dietary interventions have been utilized to modify the course of and further elucidate the pathophysiological processes involved in experimental progressive glomerulopathy. Alterations in dietary constituents can affect the glomerular capillary hemodynamic parameters, the permselectivity features of the filtration apparatus, as well as the morphology and function of resident glomerular cells and influxing bone marrow-derived monocytes. The three dietary modifications examined in this review are protein restriction, dietary cholesterol supplementation, and essential fatty acid deficiency. These maneuvers have been chosen from the myriad dietary interventions in the experimental and clinical literature and are not meant to be all inclusive. The implementation of these three dietary modifications, in experimental models of glomerular disease, amply demonstrate the concept of a stratified alteration in glomerular structure and function. Since perturbed glomerular pathobiology, involving the above-mentioned structures and cell types, is believed to contribute to progressive glomerulopathy, a review of these seemingly diverse, yet perhaps, interrelated responses to dietary modifications will only aid us in understanding this process.

Animals↗
PubMed1990

Irreversible tubulointerstitial damage associated with chronic aminonucleoside nephrosis. Amelioration by angiotensin I converting enzyme inhibition.

Chronic aminonucleoside nephrosis is variably associated with tubulointerstitial damage, depending on the route and frequency of drug administration. Recently, different groups have shown this injurious tubulointerstitial process to be reversible, coinciding with the resolution of heavy proteinuria to normal values. The authors have previously shown that a single jugular intravenous administration of puromycin aminonucleoside (PA) to male Munich-Wistar rats produces a triphasic pattern of glomerular injury and proteinuria, which culminates in focal glomerulosclerosis 70 weeks after drug administration. The authors now report the later progression of the tubulointerstitial morphologic abnormalities associated with acute nephrosis (phase I), despite spontaneous resolution of glomerular injury during the intermediate period (phase II) in this model. Although treatment of rats with the angiotensin I converting enzyme inhibitor enalapril (50 mg/l drinking water) over the 70-week period did not affect the magnitude of proteinuria during the acute nephrotic phase, enalapril prevented the recurrence of proteinuria (phase III), as well as significantly reducing the severity of interstitial fibrosis, extent of tubular dilatation, and number of intratubular casts on semiquantitative scoring at the conclusion of the study. In addition, enalapril-treated rats had less low-molecular-weight protein excretion during the recurrent phase of proteinuria, suggesting a preservation of tubular functional capacity to reabsorb these proteins. In vitro cytotoxicity studies showed only the glomerular visceral epithelial cell to be sensitive to PA, in contrast with rat tubular epithelium and other cellular controls. Although the exact pathogenetic mechanism responsible for the development of the tubulointerstitial damage remains unknown, PA in vitro does not adversely affect rat tubular epithelium; there is however a clear correlation between the magnitude of recurrent proteinuria and the severity of tubulointerstitial morphologic abnormalities, as suggested by the beneficial effect of converting enzyme inhibition on both of these untoward processes.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1989

Essential fatty acid deficiency during acute puromycin nephrosis ameliorates late renal injury.

Puromycin aminonucleoside (PA) nephrosis is associated with a significant increase in the glomerular macrophage number during peak proteinuria. The significance of this observation remains uncertain. An essential fatty acid-deficient (EFAD) diet depletes normal rat glomeruli of resident macrophages and alters glomerular eicosanoid metabolism. In this study, we found that an EFAD diet, administered only for the duration of the acute nephrotic phase, significantly ameliorated the recurrent albuminuria, renal dysfunction, and morphological injury characteristic of the late, recurrent phase of chronic aminonucleoside nephrosis. Glomerular macrophage number, isolated glomerular thromboxane B2 production, and circulating leukocyte and monocyte counts were significantly reduced in nephrotic rats on the EFAD diet 2 wk after PA injection, which temporally corresponds to peak albuminuria. The exact mechanism(s) by which the EFAD diet conferred protection in the late phase of chronic aminonucleoside nephrosis and lowered glomerular macrophage number during the acute nephrotic phase remain to be elucidated.

Acute Disease↗
PubMed1989

Hyperlipidemia of nephrosis: pathophysiologic role in progressive glomerular disease.

During the past few years, the increasing speculation that the hyperlipidemia of nephrosis may be one of several pathogenic mechanisms involved in the progression of initial glomerular injury to glomerulosclerosis has generated many clinical and experimental investigations. This discussion reviews pertinent studies that address two major issues. First, the underlying pathophysiologic mechanisms involved in the development of the hyperlipidemia of nephrosis are explored. Second, this article examines recent studies that investigate how this secondary hyperlipidemia may further aggravate initial glomerular injury and contribute to a progressive glomerulopathy, primarily mediated through alterations in monocyte/macrophage function.

Animals↗
PubMed1989

Altered functional characteristics of rat macrophages during nephrosis. Synergistic effects of hypercholesterolemia.

The effects of alimentary hypercholesterolemia and nephrotic hyperlipidemia, alone and in combination, on rat peritoneal macrophage phagocytosis, basal eicosanoid production, and glomerular macrophage number during peak PA nephrosis were evaluated in rats fed four different diets: 1) normal/standard chow; 2) PA/standard chow; 3) normal/cholesterol-supplemented diet; and 4) PA/cholesterol-supplemented diet. Both PA/standard chow and normal/cholesterol-supplemented rodent groups manifested significantly greater peritoneal macrophage phagocytosis and glomerular macrophage number when compared with normal/standard chow animals. However, the combination of the nephrotic state with superimposed alimentary hypercholesterolemia (PA/cholesterol-supplemented group) produced the greatest rise in these parameters, a rise that was significantly greater than was produced in the three other groups. Regarding basal eicosanoid production by macrophages, there was a numerical trend toward increased production of thromboxane B2 in the PA/standard chow animals and normal/cholesterol-supplemented rats when compared with normal/standard chow. Again, the combination of nephrosis and alimentary hypercholesterolemia in the PA/cholesterol-supplemented group was associated with a significantly greater amount of thromboxane B2 generated when compared with the other three groups. Regarding PGE2 production, there were no significant differences among the groups, despite marked differences in fasting serum lipid levels. This data suggest that there is a synergistic effect between alimentary hypercholesterolemia and the secondary hyperlipidemia of nephrosis in producing these macrophage functional alterations. Because fasting triglyceride values between the two nephrotic groups were indifferent, one can further speculate that it is the elevation of the serum cholesterol value that predominantly evokes these changes in macrophage function.

Animals↗
PubMed1988

Focal and segmental glomerulosclerosis: analogies to atherosclerosis.

In summary, both the developing atherosclerotic and FSGS lesions seem to share certain postulated pathophysiologic mechanisms, including endothelial cell injury, macrophage infiltration, hyperlipoproteinemia, and hypertension. As depicted in Figure 1, any initial glomerular injury results in flux of macromolecular substances into the glomerular mesangium. As an adjunct to increased glomerular barrier dysfunction, hyperlipoproteinemia is believed to secondarily develop from the dramatic losses of albumin, stimulating increased hepatic lipoprotein synthesis and the loss of lipoprotein lipase-activating substance into the urine which would effectively produce a reduction in circulating chylomicra and triglyceride catabolism. Certain elevated circulating lipoproteins could, theoretically, pass through the damaged glomerular filter into the mesangium, thereby enhancing the flux of macromolecules. Also associated with certain experimental glomerular disorders is the development of glomerular hypertension, as manifested by an elevated glomerular capillary hydrostatic pressure (PGC), which can further augment macromolecular flux into the mesangium. Overloading of the glomerular mesangium by the above mechanisms is believed to be an injurious stimulus for MC to both proliferate and produce excess mesangial matrix substance. Both of these events are thought to be pathologic harbingers of glomerulosclerosis. Glomerular hypertension is also capable of damaging endothelial cells within the glomerular microcirculation, and this purportedly can activate platelets and result in glomerular thrombosis. At present, it is unclear how glomerular thrombosis produces increased mesangial cell injury; however, this process is believed to cause both systemic and glomerular hypertension which may serve as intermediary mechanisms producing the untoward effects of mesangial cell proliferation and matrix overproduction.

Animals↗
PubMed1988

Mechanisms underlying transition from acute glomerular injury to late glomerular sclerosis in a rat model of nephrotic syndrome.

Functional and morphologic measurements were performed in Munich-Wistar rats after a single central venous injection of puromycin aminonucleoside (PA) or saline vehicle (sham). During phase I, PA rats exhibited overt nephrotic syndrome and impaired glomerular filtration, primarily due to a reduction in the glomerular capillary ultrafiltration coefficient. The morphologic counterpart of the latter consisted of effacement of glomerular epithelial cell foot processes and decrease in the number of filtration slit diaphragms. Administration of the angiotensin I converting enzyme inhibitor (CEI) enalapril to PA rats did not ameliorate glomerular dysfunction. During phase II, PA rats exhibited spontaneous resolution of proteinuria, impaired function, and morphologic abnormalities. However, PA rats now demonstrated marked glomerular capillary hypertension and continued, albeit lesser, reductions in the ultrafiltration coefficient. Concurrent CEI administration modestly lowered systemic arterial pressure, and normalized the glomerular capillary hydraulic pressure and ultrafiltration coefficient. Additional rats were studied during phase III, 70 wk after injection. In PA rats, prior glomerular hypertension was associated with development of recurrent proteinuria and extensive glomerular sclerosis, whereas concurrent CEI administration limited these parameters to values comparable to those in sham rats. Glomerular hypertension thus may explain the development of glomerular sclerosis and renal failure long after an episode of acute glomerular injury.

Animals↗