Hitoshi Kusano

Heparin-induced Thrombocytopenia in a Uremic Patient Requiring Hemodialysis An Alternative Treatment and Reexposure to Heparin

Heparin-induced thrombocytopenia (HIT) is an uncommon but potentially serious complication of hemodialysis, and subsequent reexposure to heparin after the disappearance of antiheparin-PF4 complex antibodies (HIT antibody) has been controversial. We report a 60-year-old woman who was sensitized to unfractionated heparin (heparin) as anticoagulant during hemodialysis (HD) and heparin flush on a nonsession day. The patient suddenly developed acute systemic reactions with acute pulmonary embolism a few minutes after manipulation with heparin flush on day 9, a nonsession day. Although there was no evidence of pulmonary embolism on a pulmonary scintigram on the next day, the fifth HD session was discontinued owing to recurrence of acute systemic reactions and massive clots in the dialyzer 30 min into the session. After confirmation of the presence of HIT antibody and maturation of vascular access fistula, a sixth HD session was carried out with argatroban, a synthetic direct thrombin inhibitor, with a bolus of 10 mg and continuous infusion of 0.5 mg/kg/hr as an alternative to heparin. Optimal dose adjustment of argatroban through activated partial thromboplastin time (APTT) monitoring led to a bolus of 5 mg and continuous infusion of 0.15 mg/kg/hr. The patients HD treatment at the same doses 3 times a week followed an uneventful course over 6 months. HIT antibody was seronegative about 40 days after the cessation of heparin treatment. Reexposure to heparin was attempted with the monitoring of HIT antibody and platelet counts before and after the sessions on day 210. The titers of HIT antibody compared with before the level of reexposure showed a transient insignificantly small peak, and dialysis with heparin has been maintained to date with no recurrence of HIT. The measurement of HIT antibody titer could be useful in assessing not only the effect of argatroban to replace heparin but also in predicting the recurrence of HIT due to reexposure.

Broad Antiproliferative Effects of Benidipine on Cultured Human Mesangial Cells in Cell Cycle Phases

Background and Purpose: Recently, in vitro studies have shown that some calcium channel blockers inhibit the proliferation of mesangial cells. In the present study, we evaluated the antiproliferative effects of benidipine, a calcium channel blocker, in comparison with other calcium channel blockers, and attempted to further clarify its mechanism of action on cultured human mesangial cells in relation to cell cycle. Methods: Human mesangial cells were cultured in medium containing 5% fetal calf serum (FCS), with or without benidipine, or other calcium channel blockers for 20 h, and [3H]thymidine incorporation were measured. Analysis of cell cycle dependency was carried out, using platelet-derived growth factor as a competence factor, which transfers cells from the G0 to the G1 (G0/G1) phase, and insulin as a progression factor, which transfers cells from the G1 to the S (G1/S) phase. Cells were also analyzed by flow cytometry. Results: Benidipine and nifedipine showed significant inhibitory effects on FCS-induced proliferation (p < 0.001 and p < 0.01, respectively, by ANOVA), with 3.8 and 41.9% of the control level of [3H]thymidine incorporation at the concentration of 10 µM of the blockers, respectively. Diltiazem had no inhibitory effect at this concentration. Benidipine was found to inhibit cells in both the boundaries of G0/G1 and G1/S phases (p < 0.001 and p < 0.0001, respectively), whereas nifedipine inhibited only cells in G1/S phase (p < 0.05). The effects of benidipine (10 µM) on cells in G1/S were stronger than those on cells in the G0/G1 phase (p < 0.0001). Furthermore, flow cytometry showed that 10 mM benidipine significantly inhibited the G1 to S phase transition of FCS-stimulated mesangial cells (p < 0.03). Conclusions: Benidipine markedly inhibited the proliferation of mesangial cells, at both the G0/G1 and G1/S phases, and it might be effective to suppress the progression of mesangioproliferative glomerular diseases.

Heminephrectomy Causes the Progression of Glomerulosclerosis and Apoptosis in High IgA Strain ddY Mice

Background: The reduction in nephrons in IgA nephropathy is critical to the prognosis of this disease. However, the immunopathological mechanism of the modifications seen in glomerular lesions is not clear. We thus investigated the influence of nephron reduction by heminephrectomy on renal lesions in a high immunoglobulin A inbred strain of ddY mouse (HIGA mouse), which shows progressive mesangial sclerosis with elevated renal expression of transforming growth factor (TGF)-β. Methods: Five-week-old HIGA mice were heminephrectomized (Nx), and were evaluated in comparison with a sham-operated group (S) at 40 weeks old. Histological findings, immunoglobulin depositions (IgG, IgA, and IgM), and expressions of cytokine and extracellular matrix proteins (TGF-β, fibronectin, collagen type I and IV) were analysed. PCNA and TUNEL stainings were performed with electron microscopic detection of apoptosis. Tissue renin-angiotensin systems (RAS) were also investigated by real-time quantitative RT-PCR. Results: In the Nx group, the glomerular tuft area and ratio of mesangial matrix area per tuft were significantly increased, and the glomerular cell count per tuft area was significantly decreased. Glomerular immunoglobulin deposits of IgG, IgA, and IgM in Nx were all significantly expanded in the paramesangium. The glomerular expressions of TGF-β and the extracellular matrix proteins were significantly increased in Nx mice. In contrast to the significant decrease of PCNA-positive cells, TUNEL-positive cells were significantly increased in Nx. Angiotensin-converting enzyme (ACE) was significantly increased in the renal cortex of Nx. Conclusion: Simple heminephrectomy, other than 5/6 renal ablation, of HIGA mice may be a potential model for research into the progressive glomerulosclerosis of human IgA nephropathy. The pathological role of apoptosis is apparently involved in these disease processes, possibly through upregulated RAS.

Renal redox dysregulation in AKI: application for oxidative stress marker of AKI

Oxidative stress is a major determinant of acute kidney injury (AKI); however, the effects of an AKI on renal redox system are unclear, and few existing AKI markers are suitable for evaluating oxidative stress. We measured urinary levels of the redox-regulatory protein thioredoxin 1 (TRX1) in patients with various kinds of kidney disease and in mice with renal ischemia-reperfusion injury. Urinary TRX1 levels were markedly higher in patients with AKI than in those with chronic kidney disease or in healthy subjects. In a receiver operating characteristic curve analysis to differentiate between AKI and other renal diseases, the area under the curve for urinary TRX1 was 0.94 (95% confidence interval, 0.90-0.98), and the sensitivity and specificity were 0.88 and 0.88, respectively, at the optimal cutoff value of 43.0 μg/g creatinine. Immunostaining revealed TRX1 to be diffusely distributed in the tubules of normal kidneys, but to be shifted to the brush borders or urinary lumen in injured tubules in both mice and humans with AKI. Urinary TRX1 in AKI was predominantly in the oxidized form. In cultured human proximal tubular epithelial cells, hydrogen peroxide specifically and dose dependently increased TRX1 levels in the culture supernatant, while reducing intracellular levels. These findings suggest that urinary TRX1 is an oxidative stress-specific biomarker useful for distinguishing AKI from chronic kidney disease and healthy kidneys.