Michinobu Hatano

Two types of C3 nephritic factor : properdin-dependent C3NeF and properdin-independent C3NeF

The IgG fraction of serum from patients with membranoproliferative glomerulonephritis (MPGN) types I and II or partial lipodystrophy (PLD) was found to contain C3 nephritic factor (C3NeF) which reacts with the alternative pathway C3 convertase C3bBb and stabilizes it. Two types of C3NeF were detected, of which one was heat sensitive (56 degrees C for 30 min) and properdin dependent (C3NeF:P) but the other was heat stable and properdin independent (C3NeF:nP). C3NeF:P was found in sera from patients with MPGN types I and II and it displayed the properties of properdin and IgG. C3NeF:P was observed in patients with reduced serum concentrations of C3 and terminal complement components (TCC), and the generation of SC5b-9 complex was increased in mixtures with normal human serum. C3NeF:nP was found in sera from patients with MPGN type II and PLD, whose sera revealed a selective decrease in C3 concentrations.

L-NG-monomethyl arginine inhibits the vasodilating effects of low dose of endothelin-3 on rat mesenteric arteries

We have reported that low doses of endothelin-3 (ET-3) elicited continuous vasodilation of rat mesenteric arteries, which is possibly related to endothelium-derived relaxing factor (EDRF). In order to clarify whether or not the vasodilating effects of ET-3 are associated with EDRF, we examined the effects of L-NG-monomethyl arginine (L-NMMA), an analog of L-arginine, on low-dose ET-3 induced vasodilation of rat mesente-Hc arteries. Infusion of 50 microM L-NMMA inhibited the vasodilation induced by 10(-13) M ET-3 and rather elicited an increase in perfusion pressure, which itself was decreased by infusion of 150 microM L-arginine. In the presence of 50 microM L-NMMA, 10(-13) M ET-3 did not elicit any vasodilation of the mesenteric arteries preconstricted with NE, in which 150 microM L-arginine, but not D-arginine, caused considerable vasodilation. These data suggest that the vasodilating effects of low doses of ET-3 are associated with EDRF as an endothelium-derived nitric oxide.

Effects of low magnesium diet on the vascular prostaglandin and fatty acid metabolism in rats

Deficiency of magnesium with cardiovascular effects is thought to be related to alterations in the biosynthesis of prostaglandins (PGs) in the vasculature. Measurements were made of the PGE2, 6-keto-PGF1 alpha and thromboxane B2 (TxB2) outflow from the perfused isolated mesenteric arterial bed and the fatty acid composition of the tissue in rats maintained for 14 weeks on a low magnesium (LMg) diet. The serum Mg levels were significantly decreased and the serum Ca levels were significantly increased in the LMg group as compared to the controls. The arachidonic acid concentration in the triacylglyceride fraction was significantly increased in the LMg group. Long chain polyunsaturates such as 22:4n6 and 22:6n3 were consistently increased in the LMg rats as compared to the controls in both the phospholipid and triglyceride fractions as previously reported in other tissues. The PGE2, 6-keto-PGF1 alpha and TxB2 outflows were significantly increased in the LMg group as compared to the controls. These findings suggest that the biosynthesis of eicosanoids, mainly PGI2, is stimulated in Mg deficiency, and this may provide protection against intracellular Mg depletion and Ca accumulation, so as to counteract to the constricted and hyperreactive state of the vasculature in such a condition.

Minimal-Change Nephrotic Syndrome Associated with Subcutaneous Eosinophilic Lymphoid Granuloma (Kimura’s Disease)

A 29-year-old Japanese male with a 19-year history of subcutaneous eosinophilic lymphoid granuloma (Kimuras disease) was referred to the Nephrology Service of the Nihon University Hospital for evaluation of edema and massive proteinuria. The renal biopsy disclosed minimal glomerular lesions. In this paper a case of nephrotic syndrome associated with eosinophilic lymphoid granuloma is reported.

Participation of the nucleus locus coeruleus in DOCA-salt hypertensive rats.

The locus coeruleus was subjected to biphasic electrical stimulation, and a group of deoxycorticosterone acetate (DOCA)-salt hypertensive rats revealed a greater pressor response than a group of normotensive control rats. The pressor threshold current (i.e. minimum current to raise the arterial pressure by 10 mm Hg) of DOCA-salt hypertensive rats was also lower. The threshold current was low even in the prehypertensive stage of DOCA-salt treated rats. During arterial pressure fall, the pressor threshold current lowered only in normotensive rats and neither group underwent a change during pressure rise. These data indicated that the locus coeruleus had a pressor role and it had been accelerated in DOCA-salt treated rats before hypertension was evident. Following bilateral electrical lesions of the locus coeruleus no significant differences were observed in the arterial pressure changes, while vascular reactivity to norepinephrine did not differ between the two groups. The results suggest that the locus coeruleus may be involved in the development of hypertension but may not be important in the maintenance of it.

Impaired cell-mediated immunity in lipoid nephrosis.

Cell-mediated immunity (CMI) was evaluated in 26 patients with lipoid nephrosis (LN), 50 patients suffering from chronic diffuse proliferative glomerulonephritis (CGN) without renal sufficiency and 24 healthy controls. The following parameters were measured: delayed hypersensitivity skin test responses to purified protein derivative (PPD) and candida, circulating lymphocytes. T lymphocytes and T lymphocytes with receptors for the Fc portion of IgG (T gamma cells) or IgM (Tmu cells). Patients with LN in relapse had less mean induration of skin reactivity and a smaller proportion reacting to both antigens as compared with the control subjects. In contrast, the intensity of skin reactivity and the frequency of negative reactions in patients with LN in remission and CGN were similar to those of the control subjects. It was also found that the LN patients in relapse had a significant T lymphocytopenia as well as a significant decrease in absolute numbers of Tmu and T gamma cells, whereas the patients with LN in remission and CGN did not differ significantly from the control population. Thus, the majority of patients with LN in relapse demonstrated an impaired response in a CMI assay system. The disturbed CMI may be secondary to hypoproteinemia and other nutritional factors induced by the nephrotic syndrome.

Lipoprotein(a) Predicts the Risk of Thrombogenic Complications in Nephrotic Syndrome

Takayuki Fujita, MD, 2nd Department of Medicine, Nihon University School of Medicine, Oyaguchi-kami 30-1, Itabashiku, Tokyo 173 (Japan) Dear Sir, Hypercoagulability is not a rare finding in nephrotic patients under the administration of adrenal steroids. The deposition of fibri-nogen in the renal biopsy specimen and the increase in plasma and/or urinary fibrinogen degradation products are often noted during the course of nephrosis. In the last 2 years we have seen 3 nephrotic patients with thrombogenic complications. All of them exhibited high concentrations of plasma lipoprotein(a) [Lp(a)], even when they were in the remission stage. Lp(a) is a cholesterol-rich plasma li-poprotein containing aρo(a) and apo B-100, and is said to be associated with the development of atherosclerosis [1]. It is also known to have thrombogenic properties because it has close structural homology with plasminogen [2]. Several investigators have demonstrated that Lp(a) is an independent risk factor for coronary heart disease (CHD) [3]. As reported by Armstrong et al. [4], when the plasma level of Lp(a) is above 30 mg/dl the risk for CHD increases two fold. We have measured plasma Lp(a) levels in patients with nephrotic syndrome, and investigated whether the increase in Lp(a) predicts the risk of thrombogenic complications in nephrotic patients under the adrenal steroid therapy. Plasma samples were taken from 32 normal volunteers, 20 nephrotic patients without thrombogenic complications (9 of them were in the remission stage), 1 nephrotic patient with acute myocardial infarction (case 2), and 2 nephrotic patients with cerebral infarction (cases 1 and 3). The plasma Lp(a) level was measured by the enzyme-linked immunoas-say kits (Biopool AB) [5]. Low density lipo-protein (LDL) cholesterol was calculated using the Friedwald approximation. As shown in table 1, Lp(a) and LDL cholesterol levels Table 1. Plasma Lp(a) and LDL cholesterol levels in nephrotic patients and normal volunteers (mean ± SD) were significantly elevated in nephrotic patients. These values were more increased in the nephrotic stage. The plasma Lp(a) levels of 3 complicated patients remained above 45 mg/dl even in the remission stage. Our results suggest that plasma Lp(a) may predict the risk of thrombogenic complications in nephrosis. Thereby, we propose that the simultaneous use of anticoagulant drugs should be

Detection of C3bBb-stabilizing activity (C3 nephritic factor) in the serum from patients with membranoproliferative glomerulonephritis

It is known that membranoproliferative glomerulonephritis (MPGN), hypocomplementaemia and C3 nephritic factor (C3NeF) are closely related to each other, and the presence or absence of C3NeF in the serum is important for evaluating the nature of MPGN. However, some difficulties have been encountered in detecting this factor and therefore a new assay permitting the direct detection of C3NeF without purifying IgG from the patients serum has been devised. Using this assay method, C3bBb-stabilizing activity was observed even in sera from MPGN patients who were non-hypocomplementaemic. Furthermore, among 98 cases with hypocomplementaemia. C3NeF was found to be absent in 66 cases.

Defective Cell-Mediated Immunity in Lipoid Nephrosis

Cell-mediated immunity (CMI) was studied in 28 patients with biopsy-proven lipoid nephrosis (LN). The LN patients with nephrotic syndrome (NS) had a significant depression in CMI, characterized by impaired delayed hypersensitivity skin reactivity to purified protein derivative (PPD), depressed local graft-versus-host reaction (GVHR), decreased proportion of T lymphocytes and diminished lymphocyte transformation to phytohemagglutinin (PHA). Concanavalin A (Con A)-induced suppressor cell activity (SCA) was found to be significantly increased in LN patients with NS compared to that in normal individuals. In contrast, the mean levels of CMI and SCA studied in LN patients in remission and in patients with chronic mesangial proliferative glomerulonephritis (CGN) did not differ from normal subjects. Our findings support the notion that at least in some LN patients with the NS, activated suppressor cells are present and possibly account for their decreased CMI.

Impaired Cell-Mediated Immunity in Focal Glomerular Sclerosis

Cell-mediated immunity (CMI) was evaluated in 8 patients with focal glomerular sclerosis (FGS), 50 patients suffering from chronic mesangial proliferative glomerulonephritis without renal insufficiency and 24 healthy controls. The following parameters were measured: delayed skin reactivity to purified protein derivative, circulating lymphocytes, lymphocyte cell-surface markers (neuraminidase-treated sheep erythrocyte and erythrocyte-antibody-complement rosettes) and functional markers (mitogenic responses to concanavalin A and phytohemagglutinin). The FGS patients with nephrotic syndrome (NS) had a significant depression in CMI, characterized by decreased responses of the lymphocytes to both concanavalin A and phytohemagglutinin, impaired delayed hypersensitivity to purified protein derivative and a decreased proportion of T lymphocytes as compared with normal subjects. In contrast, the levels of all CMI parameters studied in FGS patients in remission and in patients with chronic glomerulonephritis with or without NS did not differ from normal subjects. Thus, the majority of FGS patients with NS demonstrated an impaired response in a CMI assay system. The possible significance of these phenomena in the pathophysiology of FGS is discussed.