Detecting panic disorder in emergency department chest pain patients: a validated model to improve recognition

Non-insulin-dependent diabetes mellitus (NIDDM) and the renal disease attributable to it have been characterized extensively in the Pima Indians, a group of American Indians who form the Gila River Indian Community in Arizona. Both of these diseases are common in this community, and their onset and duration are known with greater certainty than in other populations because research examinations, which include oral glucose tolerance tests and measures of urinary protein excretion, have been performed frequently on most members of the population for the past 30 years. Studies of glomerular structure and hemodynamic function in diabetic Pima Indians indicate that glomerular hyperfiltration often develops at the onset of NIDDM and remains elevated until after overt nephropathy appears. Structurally, the glomeruli in subjects with microalbuminuria are not clearly distinguishable from those in subjects with normoalbuminuria, but macroalbuminuria is characterized by extensive glomerular sclerosis, mesangial expansion, and widening of epithelial cell foot processes that together lead to a rapid decline in the glomerular filtration rate. The decline in glomerular function in subjects with macroalbuminuria is due both to a loss of ultrafiltration surface area and to reduction in glomerular hydraulic permeability.     

Cyclosporine protects glomeruli from FSGS factor via an increase in glomerular cAMP

Cyclosporine (CsA) administration to patients with recurrent focal segmental glomerulosclerosis (FSGS) after transplantation results in remission of proteinuria. We have shown that sera from patients with recurrent FSGS can increase the glomerular albumin permeability (Palbumin) and that increase in glomerular cAMP levels can alter the permeability characteristics of glomeruli in vitro. The purpose of this study was to determine if the increased glomerular levels of cAMP were related to the protective effects of CsA on an increase in Palbumin by FSGS sera. Glomeruli from Sprague-Dawley rats following intraperitoneal administration of CsA (25 mg/kg/day), cremophore (25 mg/kg/day), or saline for 5 days were incubated with 1:50 dilution of serum from three FSGS patients or with pooled normal human serum prior to calculation of Palbumin. Glomerular cAMP was measured by radioimmunoassay. Glomerular ultrastructural changes were assessed by transmission electron microscopy (TEM). Serum from three FSGS patients markedly increased Palbumin of glomeruli from saline or cremophore treated rats (saline, 0.68+/-0.08; 0.72+/-0.07; 0.70+/-0.07; and cremophore, 0.79+/-0.05; 0.81+/-0.02; 0.79+/-0.01; n=25 glomeruli in each group). In contrast Palbumin of glomeruli from CsA treated rats was not increased by any of the three FSGS sera tested (0.03+/-0.02; 0.04+/-0.05; 0.02+/-0.07, n=25 glomeruli in each group). Glomerular cAMP (pmol/mg of protein) increased 5 fold in CsA treated rats (328+/-26; 5 rats) compared with cremophore or saline treated rats (87+/-24 and 65+/-23, P<0.01; 5 rats in each group). The glomerular basement membrane appeared to be thickened and the lamina densa had an irregular appearance after treatment with CsA. No ultrastructural changes of glomerular epithelial or endothelial cells were evident. We conclude that CsA may have a direct protective effect on the glomerular filtration barrier in FSGS. We postulate that increased levels of glomerular cAMP by CsA may play an important role in protecting the glomerular Palbumin effect of the FSGS factor and may contribute to remission of proteinuria in FSGS patients.     

Association of crescentic glomerulonephritis with membranous glomerulonephropathy: a report of three cases

Association of membranous glomerulonephropathy with crescentic glomerulonephritis is apparently extremely rare. We report three patients who had this combination. One patient had biopsy-proven membranous glomerulonephropathy thirteen months prior to sudden and rapid decline in renal function necessitating hemodialysis. A repeat renal biopsy showed a superimposed crescentic nephritis and antiglomerular (GBM) antibodies were demonstrable in the serum. A second patient had proteinuria of unknown duration and then developed renal failure. Renal biopsy showed crescentic nephritis with a fine granular glomerular immunofluorescence for IgG typical of membranous glomerulonephropathy. Anti-GBM antibodies were present in this patient's serum. The third patient presented with acute renal failure of moderate severity. A renal biopsy revealed crescentic nephritis, granular deposits of immunoglobulins, and epimembranous electron-dense deposits typical of membranous glomerulonephropathy. Although his creatinine clearance improved spontaneously, nephrotic syndrome has persisted and a repeat renal biopsy showed a progression of the membranous glomerulonephropathy with the disappearance of the crescentic lesions. The reason for this peculiar association of membranous glomerulonephropathy and crescentic glomerulonephritis is unclear. It is possible that deposition of immune-complexes along glomerular basement membrane may render the glomerulus more susceptible to additional injury from a variety of other agents. Alternatively, depostis formed in one disease could initiate release of normal or altered basement membrane material and lead to formation of anti-GBM antibodies and subsequent development.     

Pardaxin, a new pharmacological tool to stimulate the arachidonic acid cascade in PC12 cells

BACKGROUND: Calcium channel blockers (CCBs) are known to have differential effects on both changes in proteinuria as well as progression of diabetic nephropathy. No clinical study, however, has evaluated whether the differential antiproteinuric effects of CCBs may be explained by their effect on glomerular membrane permeability. We, therefore, tested the hypothesis that certain subclasses of CCBs reduce proteinuria by changing size selectivity of the glomerular membrane, hence changing its permeability. METHODS: Twenty-one patients with type 2 diabetes and the presence of nephropathy with hypertension were randomized to receive either diltiazem CD or nifedipine GITS after baseline data for mean systolic and diastolic pressure, urinary protein excretion, glomerular filtration rate, renal plasma flow, neutral dextran and IgG clearances were obtained. Glomerular filtration rate, renal plasma flow, neutral dextran and IgG clearance were measured every three months, arterial pressure and heart rate every month. Patients were followed for 21 months. RESULTS: At 21 months, both patient groups had similar levels of blood pressure control, however, only the diltiazem group had a change in proteinuria (4+/-10%delta, nifedipine vs. -57+/-18%delta, diltiazem; P < 0.001) with improvement in glomerular size selectivity and change in IgG clearance. CONCLUSIONS: These data support the hypothesis that CCBs that provide sustained reductions in proteinuria do so, in part, by improving glomerular size permselectivity.     

Renal biopsy in connection with long-term treatment of psoriasis with cyclosporine

Renal biopsies were performed in 30 psoriatics during long-term low-dose cyclosporin (CSA) therapy (range 2.5-6 mg/kg/day) of from six months to eight years. The study included pretreatment biopsies in 25 of the patients. After two years all biopsies shared features consistent with CSA nephropathy despite completely normal pretreatment morphology in 18 of the 25 patients. The severity of the findings, which consisted of arteriolar hyalinosis, focal interstitial fibrosis and sclerotic glomeruli, increased with length of therapy. Mild renal lesions were seen during the first two years. After four years all but one had arteriolar hyalinosis, with interstitial fibrosis pronounced in five and moderate in six of 11 patients. At the same time glomerular sclerosis had become significant. A decrease in glomerular filtration rate (GFR) correlated with the severity of the fibrosis. GFR studied in 14 patients six months to seven years after discontinuation of CSA was still significantly decreased in relation to baseline prior to therapy. The data from our study together with experiences from cardiac-transplanted patients indicate that patients with psoriasis, after two years therapy with CSA, should be rotated to other treatments or be followed carefully by GFR and sequential renal biopsies.     

Effect of intensive treatment on diabetic nephropathy in patients with type I diabetes

We evaluated the long-term effect of an intensive treatment of diabetic nephropathy (anti-hypertensive drugs, low protein diet, multiple insulin injections to achieve a good metabolic control) on glomerular filtration rate (GFR) and albumin excretion rate (AER). Fourteen type I diabetic patients (mean age 45 +/- 9.5 years, mean duration of diabetes 23.5 +/- 7.3 years, 8 males/6 females) with glomerular filtration rate < 70 ml/min-1/1.73 m2 and albumin excretion rate > 30 micrograms/min were treated intensively for 36 months. This intensive treatment consisted of multiple insulin injections, antihypertensive therapy with ACE inhibitors and a low-protein diet (0.8 g/kg body wt/day.) Renal function was evaluated as GFR and AER. HbA1c mean value decreased significantly from 8.7 +/- 0.8% to 6.5 +/- 0.5% (P < 0.0002). GFR rose from 58 +/- 12 ml/min-1/1.73 m2 to 84 +/- 11 ml/min-1/1.73 m2 (P < 0.0008). AER decreased from 208 micrograms/min (range: 73 to 500) to 63.8 micrograms/min (range 15 to 180; P < 0.05). Systolic and diastolic blood pressure decreased respectively from 144 +/- 26 mm Hg to 120 +/- 15 mm Hg and from 89 +/- 9 mm Hg to 75 +/- 8 mm Hg (P < 0.01). We obtained a rise of GFR and a reduction of proteinuria after three years of this treatment. We suggest that this intensive treatment in all patients with early stage diabetic nephropathy may be effective in slowing the progression to renal failure.     

The use of a novel monitoring apparatus and modified Belzer hydroxyethyl starch perfusate for analysis of glomerular filtration during hypothermic perfusion preservation

The present study describes an experimental model for measurement of glomerular filtration during hypothermic perfusion preservation (HPP). To facilitate glomerular filtration during HPP, perfusate oncotic pressure was reduced by lowering the concentration of hydroxyethyl starch. Lewis rats underwent HPP at a mean perfusion pressure of 40-46 mmHg. An isograft model was used to demonstrate that retrieval and preparation for HPP did not impact adversely on renal function. Total cold ischemic time (CIT) consisted of the time from retrieval and preparation for perfusion (2 hr) added to the time of HPP. Tubular function studies demonstrated identical concentrations of Na+ and iohexol in ureteral effluent (UE) compared with circulating perfusate and, as such, established that UE flow represented a direct measure of glomerular filtration. Glomerular filtration rate (GFR) was then monitored during HPP by collecting UE in a beaker housed within a computerized Mettler balance system. GFR evolved in a characteristic, biphasic pattern during HPP, increasing from baseline values to reach a peak level at 4.8+/-0.3 hr of CIT and declining progressively thereafter. At 2.5 hr, time of peak values, 10 hr, 19.5 hr, and 24 hr of CIT, GFR values were 29+/-6 microl/min, 39+/-7 microl/min, 20+/-4 microl/min (n=15; P<0.01), 7+/-2 microl/min (n=14; P<0.001), and 14+/-6 microl/min (n=5), respectively. Intrarenal perfusate flows at the same time intervals were 4180+/-292 microl/min, 4083+/-290 microl/min, 3577+/-294 microl/min (P=NS), 1948+/-393 microl/min (P<0.001), and 2175+/-743 microl/min, respectively. Filtration fraction (FF) initially changed in parallel to glomerular filtration. Thereafter, FF either declined at a disproportionately slow rate compared with GFR (n=8) or increased rapidly (n=7). The data suggest that (1) primary change(s) in glomerular dynamics occur during HPP and (2) declining perfusate flow during the later stages of HPP reflects increasing renal vascular resistance localized at a postglomerular level. The data provide an experimental basis for investigating the clinical utility of monitoring glomerular filtration during HPP.     

Hydroxyl radicals depolymerize glomerular heparan sulfate in vitro and in experimental nephrotic syndrome

Heparan sulfate, the polysaccharide side chain of heparan sulfate proteoglycan, is important for the permselective properties of the glomerular basement membrane. In this report, we show a role for hydroxyl radicals in heparan sulfate degradation and an enhanced glomerular basement membrane permeability. First, in enzyme-linked immunosorbent assay, exposure of coated heparan sulfate (proteoglycan) to reactive oxygen species resulted in a +/-50% decrease of binding of a monoclonal antibody against heparan sulfate, whereas binding of an antibody against the core protein remained unaltered. Second, on polyacrylamide gel electrophoresis, the molecular weight of heparan sulfate exposed to radicals was reduced which indicates depolymerization. Both in enzyme-linked immunosorbent assay and gel electrophoresis, hydroxyl radicals are instrumental for heparan sulfate degradation as shown by the addition of various radical scavengers. Third, in an experimental model for human nephrotic syndrome (Adriamycin nephropathy in rats), glomerular basement membrane staining of two recently described anti-heparan sulfate antibodies (JM403 and KJ865) was reduced by 24 and 43%. Treatment of Adriamycin-exposed rats with the hydroxyl radical scavenger dimethylthiourea both reduced albuminuria by 37% (p < 0.01) and partly prevented loss of heparan sulfate staining by 53% (JM403) and 39% (KJ865) (p < 0.03). In contrast to the heparan sulfate side chains, the core protein expression and the extent of glycanation did not change in Adriamycin nephropathy. We conclude that glomerular basement membrane heparan sulfate is susceptible to depolymerization by hydroxyl radicals leading to loss of glomerular basement membrane integrity and albuminuria.     

Centralis superior raphe, reticularis pontis nuclei, and sleep-wakefulness cycle in cats

It has been reported that circumferential mesangial interposition (CMI) is an important morphological feature suggesting the progression of glomerulosclerosis in glomerular disease. The relation between CMI and its associated lesions was investigated in various renal diseases by electron microscopy. In 276 patients, of whom the glomeruli were observed by electron microscopy, CMI was observed non-specifically in 48 patients with various glomerular diseases (IgA nephropathy, 11; non-IgA glomerulonephritis, 1; membranoproliferative glomerulonephritis, 8; membranous nephropathy, 5; lupus glomerulonephritis, 12; toxemia of pregnancy, 2; diabetic nephropathy, 7; mitomycin nephropathy, 1; and Seckel's dwarfism patients, 1). The glomeruli with CMI showed a marked increase in mesangial matrix, as well as various grades of mesangial cell proliferation. Mesangiolysis associated with subendothelial widening was observed in a lesion of CMI in most cases. This phenomenon appears to be an initial alteration that conducts proliferated cells to the peripheral portion of a capillary loop. Localized severe thinning of the glomerular basement membrane was frequently combined with CMI, particularly in IgA nephropathy patients. Endothelial cells were occasionally interposed into the widened subendothelial space. Subendothelial deposits were noticed in the CMI lesion, particularly in MPGN patients. In conclusion, in the process of glomerulosclerosis progression in various glomerular diseases, lytic and edematous changes initially occur in the mesangio-subendothelial system (mesangiolysis and subendothelial widening), then proliferating mesangial cells extend into the widened space (between GBM and endothelial cells), and reach the peripheral portion of a capillary loop.     

Contribution of tubular injury to loss of remnant kidney function

BACKGROUND: The remnant kidney model has been widely used to identify mechanisms responsible for the progression of renal disease. However, the structural changes associated with progressive loss of function in this model have not been well characterized. METHODS: Kidney function and structure were assessed at 10 weeks (REM 10) and 25 weeks (REM 25) after five-sixths renal ablation and in control rats (Control). Serial sections were examined to relate glomerular and tubular structure in individual nephrons. RESULTS: Remnant kidney function declined between 10 and 25 weeks after ablation (GFR 0.90 +/- 0.34 vs. 0.23 +/- 0.07 ml/min, REM 10 vs. REM 25, P < 0.05). This decline in function was associated with an increase in the prevalence of globally sclerotic glomeruli (14 +/- 10 vs. 0 +/- 0 vs. 0 +/- 0%, REM 25 vs. REM 10 vs. Control, P < 0.05 REM 25 vs. REM 10 and Control). The decline in remnant kidney function between 10 and 25 weeks was also associated with the appearance of glomeruli that were atubular (48 +/- 14 vs. 9 +/- 8 vs. 3 +/- 5%, REM 25 vs. REM 10 vs. Control, P < 0.05 REM 25 vs. REM 10 and Control) or connected to atrophic proximal tubule segments (26 +/- 10 vs. 11 +/- 6 vs. 1 +/- 2%, REM 25 vs. REM 10 vs. Control, P < 0.05 all comparisons). Atubular glomeruli, which usually had open capillary loops available for filtration, were more numerous than globally sclerotic glomeruli at 25 weeks after ablation. CONCLUSIONS: These findings indicate that tubular injury contributes to progressive loss of renal function following reduction in nephron number.     

Contractile cells of the kidney in primary glomerular disorders: an immunohistochemical study using an anti-alpha-smooth muscle actin monoclonal antibody

Mesangial cells of the renal glomerulus are thought to have contractile properties, resembling those of smooth muscle cells. Since actin synthesis in mesangial cells is increased in selected animal models of glomerulonephritis, we evaluated the expression of alpha-smooth muscle actin (ASMA), the principal actin isoform found in smooth muscle cells, in biopsy specimens from patients with primary glomerular disorders and in control tissues. Normal glomeruli and glomeruli in acute tubulointerstitial disorders showed few or no ASMA-positive cells in the glomeruli. In contrast, ASMA expression in mesangial cells was increased in minimal change disease, focal segmental glomerulosclerosis, mesangial proliferative glomerulonephritis, membranous glomerulonephritis, and immunoglobulin A nephropathy. In membranoproliferative glomerulonephritis and cryoglobulinemic glomerulonephritis both mesangial and capillary loop ASMA-positive cells were observed with a segmental distribution. In addition, ASMA-positive interstitial cells were seen in many biopsy specimens and often were increased in number in biopsy specimens showing early interstitial fibrosis and tubular atrophy. We conclude that ASMA synthesis in mesangial cells is upregulated in a variety of glomerular disorders, frequently associated with increased cell proliferation and mesangial matrix production. This phenotypic change may be an indicator of mesangial cell activation after injury and may have important pathophysiologic consequences.     

Synthesis of the esterified cerebroside in the epidermis of guinea pigs

BACKGROUND: The level of glomerular filtration rate (GFR) and its determinants in non-insulin-dependent diabetes mellitus (NIDDM) are currently controversial. DESIGN OF THE STUDY: We measured GFR and effective renal plasma flow (ERPF) in 121 consecutive NIDDM without evidence of overt diabetic nephropathy. Age varied from 28 to 70 years, 61.2% were women and known duration of NIDDM was 0-37 years. Hypertension was detected in 36.4% of patients and 47.8% had microalbuminuria. RESULTS: An inverse correlation was found between GFR and age, but not with known duration of NIDDM: It was a weak correlation (r = -0.41) but statistically significant (P < 0.001). The other variables considered were not significant by multiple stepwise regression analysis, but patients with lower GFR tended to have diabetic retinopathy more frequently. GFR was lower in hypertensive compared to normotensive patients (123 +/- 28.4 versus 136 +/- 32.5 ml/min/1.73 m2; P < 0.05), but was not different between patients with normal and elevated albumin excretion rate. ERPF also had an inverse correlation with age (r = -0.45, P < 0.001). CONCLUSION: We conclude that (i) age should be considered as a confounding variable when evaluating GFR in patients with NIDDM, and (ii) the age-dependent decline in GFR may mask hyperfiltration in the early stages of diabetic nephropathy in NIDDM:     

Glucose-induced changes in renal haemodynamics in proteinuric type 1 (insulin-dependent) diabetic patients: inhibition by acetylsalicilic acid infusion

The effect of hyperglycaemia on renal function in diabetic nephropathy remains poorly understood. We investigated the renal haemodynamic response to an acute plasma glucose rise from sustained euglycaemia to sustained hyperglycaemia in eight persistently proteinuric Type 1 (insulin-dependent) diabetic patients. Studies were performed in a double-blind cross-over manner after i.v. injection of 450 mg lysine acetylsalicilate (equivalent to 250 mg acetylsalicilic acid) or equal volume of 0.9% NaCl (isotonic saline). In the isotonic saline experiments hyperglycaemia produced a significant rise, by approximately 35%, in glomerular filtration rate in all patients from 41.5 +/- 5.2 to 55 +/- 6 ml.min-1.1.73 m-2 (p < 0.005) and an increase in sodium paraminohippurate clearance from 178 +/- 22.7 to 220 +/- 20.0 ml.min-1.1.73 m-2 (p < 0.05). These changes took place within the first 30 min of glucose infusion and were maintained for a 90 min hyperglycaemic period. Filtration fraction did not change significantly. Infusion of lysine acetylsalicilate lowered baseline glomerular filtration rate (isotonic saline vs lysine acetylsalicilate 41.5 +/- 5.2 vs 30.0 +/- 5.7 ml.min-1.1.73 m-2; p < 0.05) and significantly blunted the rise in glomerular filtration rate during hyperglycaemia (glomerular filtration rate increment: saline vs lysine acetylsalicilate: 13.6 +/- 2.8 vs 5.3 +/- 1.8 ml.min-1.1.73 m-2; p < 0.005). The effects on renal plasma flow were similarly blunted. In five additional patients, time- and volume-controlled isotonic saline experiments during sustained euglycaemia showed no significant changes in glomerular filtration rate and sodium paraminohippurate clearance.(ABSTRACT TRUNCATED AT 250 WORDS)     

The localisations in liposomal membranes of the tetrahydrofuran ring moieties of the annonaceous acetogenins, annonacin and sylvaticin, as determined by 1H NMR spectroscopy

We studied 34 apparently healthy children and 2 propositi from kindreds with familial juvenile hyperuricaemic nephropathy (FJHN) - a disorder characterised by early onset, hyperuricaemia, gout, familial renal disease and a similarly low urate clearance relative to glomerular filtration rate (GFR) [fractional excretion of uric acid (FEur) 5.1+/-1.6%] in young men and women. In addition to the propositi, 17 asymptomatic children were hyperuricaemic -- mean plasma urate (368+/-30 micromol/l), twice that of controls (154+/-41 micromol/l). Eight of them had a normal GFR ( > 80 ml/min per 1.73 m2), and 11 renal dysfunction, which was severe in 5. The FEur in the 14 hyperuricaemic children with a GFR > 50 ml/min was 5.0+/-0.5% and in the 5 with a GFR < or =50 ml/min was still low (11.5+/-0.2%) compared with controls (18.4+/-5.1%). The 17 normouricaemic children (185+/-37 micromol/l) had a normal GFR (>80 ml/min) and FEur (14.0+/-5.3%). The results highlight the dominant inheritance, absence of the usual child/adult difference in FEur in FJHN and presence of hyperuricaemia without renal disease in 42% of affected children, but not vice versa. Since early allopurinol treatment may retard progression to end-stage renal failure, screening of all relatives in FJHN kindreds is essential.     

Renal reserve filtration capacity in growth hormone deficient subjects

In normal subjects, the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) acutely increase in response to infusion of amino acids and to low doses of dopamine. It is uncertain whether circulatory growth hormone (GH) is a permissive factor for these stimulatory effects. GFR and ERPF (constant infusion technique using 125I-iothalamate and 131I-hippuran, respectively) were measured before and during the infusion of dopamine and amino acids in 8 GH deficient subjects. The clearance study was repeated during concomitant administration of octreotide to investigate whether this somatostatin analogue would modify the amino acid and dopamine-induced renal haemodynamic changes. Dopamine increased baseline GFR from 89 +/- 3 (mean +/- SEM, n = 8) to 102 +/- 4 ml min-1 1.73 m-2 and ERPF from 352 +/- 19 to 476 +/- 26 ml min-1 1.73 m-2, P less than 0.001 for both. During amino acid infusion GFR and ERPF increased to 108 +/- 3 and 415 +/- 23 ml min-1 1.73 m-2, respectively, P less than 0.001 for both. Octreotide did not significantly decrease baseline and dopamine-stimulated renal haemodynamics but lowered the amino acid-stimulated GFR (98 +/- 4 ml min-1 1.73 m-2, P less than 0.05) and ERPF (381 +/- 18 ml min-1 1.73 m-2, P less than 0.05). Basal plasma glucagon concentrations were not suppressed by octreotide, whereas the amino acid-induced increments in plasma glucagon were partially inhibited. It is concluded that GH is not a necessary factor for the stimulatory effects of amino acids and dopamine on renal haemodynamics.(ABSTRACT TRUNCATED AT 250 WORDS)     

Basic fibroblast growth factor augments podocyte injury and induces glomerulosclerosis in rats with experimental membranous nephropathy

Podocyte injury is believed to contribute to glomerulosclerosis in membranous nephropathy. To identify the factors involved, we investigated the effects of basic fibroblast growth factor (bFGF), a cytokine produced by podocytes, on rats with membranous nephropathy (passive Heymann nephritis [PHN]). All rats received a daily i.v. bolus of 10 microg bFGF or vehicle from days 3-8 after PHN induction. In proteinuric PHN rats on day 8, bFGF injections further increased proteinuria. Podocytes of bFGF-injected PHN rats showed dramatic increases in mitoses, pseudocyst formation, foot process retraction, focal detachment from the glomerular basement membrane, and desmin expression. bFGF injections in PHN rats did not alter antibody or complement deposition or glomerular leukocyte influx. bFGF-injected PHN rats developed increased glomerulosclerosis when compared with control PHN rats. Also, bFGF induced proteinuria and podocyte damage in rats injected with 10% of the regular PHN-serum dose. None of these changes occurred in bFGF-injected normal rats, complement-depleted PHN rats or rats injected with 5% of the regular PHN serum dose. These divergent bFGF effects were explained in part by upregulated glomerular bFGF receptor expression, induced by PHN serum. Thus, bFGF can augment podocyte damage, resulting in increased glomerular protein permeability and accelerated glomerulosclerosis. This bFGF action is confined to previously injured podocytes. Release of bFGF from glomerular sources (including podocytes themselves) during injury may represent an important mechanism by which podocyte damage is enhanced or becomes self sustained.     

Prevention of glomerular dysfunction in diabetic rats by treatment with d-alpha-tocopherol

Because d-alpha-tocopherol (vitamin E) has been shown to decrease diacylglycerol (DAG) levels and prevent the activation of protein kinase C (PKC), which is associated with retinal and renal dysfunctions in diabetes, the study presented here characterized the effect of d-alpha-tocopherol treatment to prevent glomerular hyperfiltration and increased albuminuria as well as PKC activities in streptozotocin (STZ)-induced diabetic rats. Two weeks after the induction of diabetes, total DAG content and PKC activity in glomeruli were significantly increased in diabetic rats by 106.4 +/- 16.8% and 66.4 +/- 8.4%, respectively, compared with control rats. Intraperitoneal injection of d-alpha-tocopherol (40 mg/kg of body weight) every other day prevented the increases in total DAG content and PKC activity in glomeruli of diabetic rats. Glomerular filtration rate (GFR) and filtration fraction (FF) were significantly elevated to 4.98 +/- 0.34 mL/min and 0.36 +/- 0.05, respectively, in diabetic rats, compared with 2.90 +/- 0.14 mL/min and 0.25 +/- 0.02, respectively, in control rats. These hemodynamic abnormalities in diabetic rats were normalized to 2.98 +/- 0.09 mL/min and 0.24 +/- 0.01, respectively, by d-alpha-tocopherol. Albuminuria in 10-wk diabetic rats was significantly increased to 9.1 +/- 2.2 mg/day compared with 1.2 +/- 0.3 mg/day in control rats, whereas d-alpha-tocopherol treatment improved albumin excretion rate to 2.4 +/- 0.6 mg/day in diabetic rats. To clarify the mechanism of d-alpha-tocopherol's effect on DAG-PKC pathway, the activity and protein levels of DAG kinase alpha and gamma, which metabolize DAG to phosphatidic acid, were examined. Treatment with d-alpha-tocopherol increased DAG kinase activity in the glomeruli of both control and diabetic rats, by 22.6 +/- 3.6% and 28.5 +/- 2.3% respectively, although no differences were observed in the basal DAG kinase activity between control and diabetic rats. Because immunoblotting studies did not exhibit any difference in the protein levels of DAG kinase alpha and gamma, the effect of d-alpha-tocopherol is probably modulating the enzyme kinetics of DAG kinase. These findings suggest that the increases in DAG-PKC pathway play an important role for the development of glomerular hyperfiltration and increased albuminuria in diabetes and that d-alpha-tocopherol treatment could be preventing early changes of diabetic renal dysfunctions by normalizing the increases in DAG and PKC levels in glomerular cells.     

Intraglomerular foam cells and human focal glomerulosclerosis

Experimental evidence suggests a pathogenetic role for lipids in focal glomerulosclerosis (FGS) analogous to atherosclerosis. As foam cells (FC) are an important factor in atherosclerosis, a retrospective comparative study was done to evaluate the significance of intraglomerular FC in human FGS. Glomerular FC infiltration was evaluated in 115 biopsies of FGS, 120 biopsies of membranous glomerulonephritis (MGN) and 50 biopsies of minimal-change disease (MCD). Selected clinical and laboratory data collected at about the time of biopsy were reviewed. The proportion of biopsies showing glomerular FC was much higher in FGS (70%) than in either MGN (12%) or MCD (0%) p less than 0.001. The mean percent (+/- SD) of glomeruli with FC per biopsy was significantly greater in FGS (7.9 +/- 9.9) than in MGN (2.0 +/- 7.8; p less than 0.0001). Of the 14 MGN biopsies with FC, 13 showed superimposed FGS. Mean serum total cholesterol and triglyceride were not significantly higher in FGS than in either MGN or MCD. The results demonstrate a close association of glomerular FC infiltration with FGS.     

Cholesterol: a renal risk factor in diabetic nephropathy?

In a prospective follow-up of 30 patients with type 1 diabetes and nephropathy, serum cholesterol, triglycerides, apolipoprotein Al and B, and lipoprotein(a) were determined to study their relationship to the rate of decline in glomerular filtration rate. The patients had proteinuria and advanced nephropathy with a mean +/- SD glomerular filtration rate of 39 mL/min/1.73 m2. The decline in glomerular filtration rate was determined during 2.5 +/- 0.5 years. High serum cholesterol, triglycerides, and apolipoprotein B were correlated to a more rapid deterioration in kidney function. The rate of decline in glomerular filtration rate was 1.0 +/- 2.5 mL/min/yr in the 10 patients with the lowest cholesterol level, compared with 4.5 +/- 3.2 mL/min/yr in the patients with the highest serum cholesterol (P = 0.015). The combined effect of the measured lipids, blood pressure, type of antihypertensive treatment, protein intake, proteinuria, and hemoglobin A1C on the rate of decline in glomerular filtration rate was assessed by multiple regression analysis. The measured factors together had a high explanatory power for the rate of decline in glomerular filtration rate. In this model, 73% of the variation in decline in glomerular filtration rate was explained by the measured variables (multiple r2 = 0.73). Low cholesterol and treatment with an angiotensin-converting enzyme inhibitor were the strongest predictors of a favorable renal prognosis. This suggests that hypercholesterolemia is an important risk factor for diabetic nephropathy.     

Glomerular epithelial protein 1 and podocalyxin-like protein 1 in inflammatory glomerular disease (crescentic nephritis) in rabbit and man

The podocyte is the cell responsible in large part for maintaining the glomerular filtration barrier. Glomerular epithelial protein 1 (GLEPP1) is a novel receptor-like transmembrane protein tyrosine phosphatase present on the apical surface of podocyte foot processes. Podocalyxin-like protein 1 (PCLP1) is a transmembrane sialoglycoprotein which is also present on the foot process apical surface as well as on the surface of endothelial cells. GLEPP1 and PCLP1 are thought to play a role in regulating the structure and function of podocyte foot processes. Glomerular injury affecting the podocyte is likely to be reflected by changes in these proteins. GLEPP1 distribution in human renal biopsy with inflammatory glomerular disease and crescent formation was examined by immunocytochemistry. A model of inflammatory glomerular injury induced by guinea pig anti-rabbit basement membrane (anti-GBM) antibody was used to examine the distribution and amount of GLEPP1 and PCLP1 mRNA and protein. A biopsy study was done to determine whether the extent of GLEPP1 depletion from glomeruli at early time points (Day 7) would predict the severity of crescent formation at Day 30. Glomeruli from human renal biopsies with crescentic nephritis showed focal to diffuse disappearance of GLEPP1 protein. No GLEPP1 was present within the cellular crescent. By Day 4 of the rabbit anti-GBM model, before cellular crescents had formed, GLEPP1 protein was reduced from 127 +/- 28 X 10(7) to 30 +/- 5 X 10(7) molecules per glomerulus (p < 0.001), and GLEPP1 mRNA was reduced by 62% (p < 0.05). In contrast, at this time there was no significant reduction of PCLP1 protein from the normal number of 309 X 10(9) molecules per glomerulus and the PCLP1 mRNA level had not decreased. At Day 4, podocyte foot processes were effaced and proteinuria was present. Glomerular culture supernatants from Day 4 rabbits caused a reduction in GLEPP1 but not PCLP1 protein expression by cultured normal glomeruli, showing that a soluble factor was produced at Day 4 which reduced the number of GLEPP1 molecules in glomeruli. There was no detectable proteolysis of GLEPP1 or PCLP1 in glomeruli and no increase in GLEPP1 or PCLP1 excretion in urine. Therefore, the reduction in glomerular GLEPP1 was associated with reduced synthetic capacity. The proportion of glomeruli with reduced GLEPP1 at Day 7 of the model was significantly associated with the percent of glomeruli which had formed crescents at Day 30 (r = 0.86, p < 0.0001). GLEPP1 appears to be a sensitive indicator of glomerular injury during inflammation in man and in the rabbit model. A reduction in amount of GLEPP1 is associated with worse outcome for the glomerulus.