High pressure conditions promote the proliferation of rat cultured mesangial cells in vitro.

Glomerular capillary pressure is involved in the development of chronic renal failure and has at least two effects on mesangial cells: transmembrane hydrostatic pressure and stretch. To clarify whether pure hydrostatic pressure itself affects the proliferation of cultured rat mesangial cells, we compared the cell number under atmospheric pressure condition with high pressure condition. At 24 and 48 h with 0.5% serum, cell number was significantly higher under high pressure condition than under atmospheric pressure condition. At 48 h, cell number under high pressure condition was increased in a pressure-dependent manner. Furthermore, flow cytometric assay indicated that pressure-load could promote DNA synthesis rate at S phase and enhance G1/S progression induced by low concentration of serum (0.5%). These results suggest that pure hydrostatic pressure itself can promote the proliferation of cultured rat mesangial cells by advancing cell cycle progression in vitro.

Dilazep, a nucleoside transporter inhibitor, modulates cell cycle progression and DNA synthesis in rat mesangial cells in vitro.

The direct effects of the nucleoside transporter inhibitor dilazep on the cell cycle of mesangial cells have not before been investigated. The purpose of this study was to elucidate whether dilazep can inhibit the proliferation of mesangial cells and how it interferes with the cell cycle of these cells. DNA histograms were used and BrdUrd uptake rate was measured by flow cytometry. There was no significant difference in the cell numbers among the untreated group and the 10(-5) M, 10(-6) M or 10(-7) M dilazep-treated groups at 24 h of incubation. However, at 48 and 72 h, the cell numbers in the dilazep-treated groups were significantly lower compared with that of the untreated group (P < 0.005). The DNA histograms of cultured rat mesangial cells at 12, 24, and 48 h of incubation with 10(-5) M dilazep showed that the ratio of the S phase population in the dilazep-treated group decreased by 2.2% at 12 h, by 9.6% at 24 h, and by 18.9% at 48 h compared with the untreated group. The ratio of the G0/G1 phase population in the dilazep-treated group significantly increased: 6.8% at 12h (P < 0.05), 13.9% at 24 h (P < 0.001), and 76.5% at 48 h (P < 0.001) compared with the untreated group. A flow cytometric measurement of bivariate DNA/BrdUrd distribution demonstrated that the DNA synthesis rate in the S phase decreased after 6 h (P < 0.005) and 12 h (P < 0.05) of incubation compared with the untreated group. These results suggest that dilazep inhibits the proliferation of cultured rat mesangial cells by suppressing the G1/S transition by prolonging G2/M and through decreasing the DNA synthesis rate.

Heterogeneous expression of nonmuscle myosin heavy chain-B in mesangial cells of patients with Gitelman's syndrome.

AIMS: It has been suggested that angiotensin II (Ang II) promotes hypertrophy and hyperplasia of mesangial cells. Nonmuscle myosin heavy chain-B (NMHC-B) and alpha-smooth muscle (SM) actin are considered to be molecular markers for phenotypic change ofproliferative mesangial cells. One of the clinical characteristics in Gitelman's syndrome (GS) is the elevation of plasma Ang II. However, little is known about the relation between Ang II and phenotypic change of mesangial cells in patients with GS. In this report, we examined the expression of NMHC-B and alpha-SM actin in mesangial cells of two GS patients. MATERIALS AND METHODS: Plasma renin activity, and the concentrations of Ang II, 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), urinary kallikrein, and 6-keto-PGF1alpha were measured. Immunohistochemical staining of NMHC-B and alpha-SM actin in mesangial cells of GS patients was also performed. RESULTS: Both cases of GS showed normal glomerular function, few histological abnormalities, and higher than normal plasma concentrations of renin and Ang II. Furthermore, one case showed a high urinary concentration of kallikrein and the expression of both NMHC-B and alpha-SM actin in mesangial cells. The other case showed a high urinary concentration of 6-keto-PGF1alpha but not kallikrein and without the expression of NMHC-B and alpha-SM actin. CONCLUSION: Not only plasma kinin-kallikrein and prostaglandins, but the renal expression of NMHC-B and alpha-SM actin may be variable in different patients with GS.

[Serum lipoprotein abnormalities in patients with nephrotic syndrome and effects of steroid therapy].

With polyacrylamide gel electrophoresis (PAGE), we studied serum lipoprotein (Lp) abnormalities in patients with nephrotic syndrome (NS) caused by primary glomerulonephritis. Nineteen untreated nephrotic patients were studied. Seven patients of them were followed up with PAGE in the remitting course. Serum total cholesterol, triglycerides and beta-Lp concentrations were higher in untreated patients than those in normal control. Serum HDL-cholesterol concentration was lower in untreated patients than those in normal control. PAGE showed broad midband-Lp and increased pre-beta-Lp in 16 of 19 untreated patients. Those findings suggested that untreated nephrotic patients had impaired catabolism of VLDL to LDL in peripheral tissue or impaired hepatic catabolism of IDL and LDL. Furthermore, PAGE showed decreased alpha-Lp in all patients with untreated NS. Correlation was not found between histological classification of glomerulonephritis and broad midband or hyperlipidemia. After administration of prednisolone, PAGE revealed the appearance of chylomicron, and increased pre-beta-LP and alpha-Lp. After remission, broad midband-Lp and pre-beta-Lp were markedly decreased or dis appeared in all 6 patients with broad midband-Lp in untreated phase, and serum total cholesterol and beta-Lp concentrations were markedly decreased, and HDL- cholestrol was markedly increased. In the course of remission, serum total cholesterol, triglycerides and beta-Lp concentrations had negative correlation with serum albumin concentration. Furthermore, serum total cholesterol and beta-Lp concentrations were decreased along with decrease of urinary protein excretion. The results of the present study suggest that the loss of serum albumin and/or some other substances to the urine cause broad midband.

[Study on coagulation fibrinolytic systems in predialysis patients with chronic renal failure--comparison between patients with chronic glomerulonephritis and patients with diabetic nephropathy].

To clarify the abnormalities of coagulation and fibrinolytic systems on predialysis patients with chronic renal failure, we measured indices of coagulation and fibrinolytic systems in 33 predialysis patients whose creatinine (Cr) levels were over 3.0 mg/dl. We termed twenty-four patients with chronic glomerulonephritis the "CGN group". We also termed nine patients wit diabetes mellitus the "DM group". We measured thrombin.antithrombin III complex (TAT), alpha 2-plasmin inhibitor plasmin complex (PIC), D-dimer, protein C, protein S, thrombomodulin (TM), vitronectin, tissue plasminogen activator.plasminogen activator inhibitor-1 complex (tPAI-C) in theses two groups. Furthermore, we measured the same indices after 6 months in the CGN group. As a result, the plasma levels of both TAT, PIC, TM/Cr ration in the DM group were significantly higher that those in the CGN group, changes in both protein S activities and plasma levels of tPAI-C were reduced significantly after 6 months. In conclusion, the abnormalities of coagulation and fibrinolytic systems in predialysis diabetic patients were stronger than those in predialysis patients with CGN. Furthermore, these abnormalities were worsened after 6 months in predialysis patients with chronic renal failure.

[A case report of right ventricular infarction clearly detected by transesophageal echocardiography].

We reported a case of a 70 year-old woman who suffered from right ventricular infarction with cardiogenic shock, detected clearly by transesophageal echocardiography. On admission, her pulse rate was 31 bpm and her blood pressure was unobtainable. Conscious level was III-1-2 and she was cold and clammy. The ECG showed complete AV block with junctional escape rhythm at a rate of 31 bpm which required temporary pacing and ST elevation in leads II, III, a VF, V4R, V3R, V1. An echocardiogram showed akinesis of RV free wall and paradoxical septal motion. Transesophageal echocardiography was performed safely on the 5th hospital day and detected RV wall motion abnormality clearly. A Swan-Ganz catheter was inserted. Mean PCW was 12 mmHg. PA pressure was 19/11 mmHg. Mean RA pressure was 13 mmHg. Cardiac index was 1.33 l/min/m2. SvO2 was 54%. Volume loading, administration of dopamine, dobutamine and nitroprusside were started. Cardiac index increased to 1.88 l/min/m2, and SvO2 increased to 59%. On the 4th hospital day, mean RA pressure increased to 29 mmHg and PA pressure increased to 47/31 mmHg acutely. Endotracheal intubation was done and PEEP 6 cmH2O was used and mean RA pressure and PA pressure decreased. On the 6th hospital day, cardiac index increased 4.08 l/min/m2. Cardiac catheterization done two months after acute myocardial infarction showed 75% stenosis of the proximal right coronary artery.

Applied pressure enhances cell proliferation through mitogen-activated protein kinase activation in mesangial cells.

Progressive renal diseases lead to prolonged glomerular hypertension, which induces the proliferation of mesangial cells. This proliferation is thought to be involved in the development of renal injury. Here we investigate mitogen-activated protein kinase (MAPK) activation and cell proliferation in mesangial cells under conditions of high pressure. After pressure-load, the phosphorylation level of MAPK (at Tyr-204) increases rapidly with a peak at 1 min, although the amount of MAPK remains almost constant during pressure-load. To confirm the activation of MAPK, we carried out an immunoprecipitation-kinase assay. MAPK activity during pressure-load shows kinetics similar to that of the tyrosine phosphorylation. In contrast, c-Jun N-terminal kinase 1 (JNK1) phosphorylation falls below basal levels in response to high pressure. Immunocytochemical observations show phosphorylated MAPK in the nucleus at 10 min. The expression of c-Fos, a nuclear transcription factor, is induced by high pressure, and the induction is significantly inhibited by PD98059 (50 microM), an upstream MAPK/extracellular signal-regulated kinase kinase (MEK) inhibitor of MAPK. The expression of the c-Jun that is induced by JNK1 activation remains unchanged during pressure-load. MAPK phosphorylation and cell proliferation by applied pressure are significantly inhibited by genistein, a tyrosine kinase inhibitor in a dose-dependent manner, but not by protein kinase C inhibitors, chelerythrine and GF109203X. Genistein also blocks pressure-induced tyrosine phosphorylation of proteins with molecular masses of 35, 53, and 180 kDa. To clarify the physiological role in MAPK activation under high pressure conditions, we transfected antisense MAPK DNA into mesangial cells. The antisense DNA (2 microM) inhibited MAPK expression by 80% compared with expression in the presence of sense or scrambled DNA, and significantly blocked pressure-induced cell proliferation. Treatment of cells with MEK inhibitor also produced a similar result. MEK inhibitor strongly suppresses DNA synthesis induced by pressure-load. Cyclin D1 expression is significantly increased under high pressure conditions, and the increase is blocked by treatment with MEK inhibitor. These findings show that pressure-load, a novel activator of MAPK, induces the activation of tyrosine kinases, and enhances the proliferation of mesangial cells, probably through cyclin D1 expression.

Appropriate dosing of pilsicainide hydrochloride in patients on hemodialysis.

Appropriate dosing of pilsicainide hydrochloride, an anti-arrhythmic drug excreted via the kidney, was investigated in patients on dialysis. Ten chronic hemodialysis patients with coexisting severe palpitation of supraventricular premature contractions (SVPC) were treated with 25 mg of pilsicainide hydrochloride before dialysis. All of their plasma concentrations were maintained within the therapeutic range and their mean dialysis rate was 32%. After 2 weeks, 7 patients were followed with consecutive daily dose treatment. In 3 of them, the dosage was returned to the single pre-dialysis administration because of the elevated plasma concentration reaching the toxic range 1 month after the start of administration. The dose schedule was maintained, and plasma pilsicainide concentrations remained within the therapeutic range during the 6-month follow-up. No abnormal findings were found in any parameters of electrocardiography, echocardiography or biochemistry. The number of SVPC diminished > 90% compared to the pretreatment level.