Hiroyuki Kaneto

The expression of mRNA for tumour necrosis factor-α increases in the obstructed kidney of rats soon after unilateral ureteral ligation

Summary: Cytokines, including transforming growth factor (TGF)‐β1, contribute to the tubulointerstitial fibrosis of ureteral obstruction. Tumour necrosis factor (TNF)‐α, a proinflammatory cytokine produced by multiple cells including macrophages and resident renal cells, has a role in inflammatory cell recruitment in glomerular injury. We measured TNF‐α mRNA in the renal cortex of rats at different times after the onset of unilateral ureteral obstruction (UUO) and determined whether angiotensin II (AngII) inhibition or total body irradiation affects the mRNA levels of TNF‐α. Rats were killed at 1, 2, 4, 24, 72 and 120h after UUO. Levels of TNF‐α mRNA increased significantly in the obstructed kidney at 1h (X 2), 2h (X 2.7), 4h (X 3.6), 24h (X 2.7), 72h (X 1.8) and 120h (X 2.8) after ureteral ligation when compared to the contralateral kidney of the same animals or to control (normal) kidneys. Tumour necrosis factor‐α mRNA increased in renal cortical tubules but not in glomeruli. Treatment with enalapril, an angiotensin‐converting enzyme (ACE) inhibitor, before and after UUO decreased TNF‐α mRNA levels in the obstructed kidney by about 40% at 4h after the onset of UUO, but at 120h there was no difference in TNF‐α levels in the obstructed kidney of treated and untreated animals. Total body irradiation, which depletes macrophages in the obstructed kidney, did not prevent the upregulation of TNF‐α mRNA expression at 4 h after UUO. Thus, TNF‐α may have a role in initiating tubulointerstitial injury in the obstructed kidney. Leucocytes infiltrating the renal interstitium of the obstructed kidney do not appear to contribute to the increased mRNA expression of TNF‐α. Angiotensin II may contribute, at least in part, to the early increased expression of TNF‐α mRNA in the obstructed kidney.

Role of protein kinase C in cisplatin nephrotoxicity

Background: Cisplatin is widely used in cancer treatment. The major disadvantage of this antitumor agent is its nephrotoxicity. The mechanism of cisplatin‐induced nephrotoxicity has not been clarified. Recent evidence suggests protein kinase C (PKC)‐related signal transduction pathways may modulate cisplatin‐induced cytotoxicity.

Role of leukocyte adhesion molecules in monocyte/ macrophage infiltration in weanling rats with unilateral ureteral obstruction.

Abstract Background Unilateral ureteral obstruction (UUO) of rats is a well‐established model for studying obstructive nephropathy. Meanwhile, pathophysiology of pediatric obstructive nephropathy is not well understood. In this report, we studied monocyte/macrophage infiltration and expression of intercellular adhesion molecule 1 (ICAM‐1) and macrophage antigen 1 (Mac‐1) in weanling rats with UUO.

Plasminogen activator inhibitor-1 and tissue-type plasminogen activator are up-regulated during unilateral ureteral obstruction in adult rats.

PURPOSE The plasminogen activator (PA)-plasmin system has been shown to influence turnover of the extracellular matrix in various tissues. We examined the alteration of plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (t-PA) in kidneys with unilateral ureteral obstruction in rats. MATERIALS AND METHODS Female rats that underwent ligation of the left ureter were sacrificed 12 hours, 1, 5 or 10 days later. The expressions of PAI-1 and t-PA was determined by reverse transcription-polymerase chain reaction and immunohistochemical studies in the obstructed and contralateral kidneys in each group. RESULTS Control kidneys showed no PAI-1 messenger (m)RNA expression. After days 1 through 10 of unilateral ureteral obstruction the amount of PAI-1 mRNA significantly increased in obstructed compared with contralateral kidneys (p <0.01). Meanwhile, slight polymerase chain reaction products of t-PA were observed in control kidneys. After 12 hours through 10 days of unilateral ureteral obstruction, t-PA mRNA in obstructed and contralateral kidneys was significantly elevated compared with in control kidneys (p <0.05). No significant difference in t-PA was observed in the obstructed and contralateral kidneys in each group. Immunoreactivity to PAI-1 and t-PA was identified in obstructed kidneys. CONCLUSIONS PAI-1 and t-PA are up-regulated in obstructed rat kidneys. Our results indicate that the PA-plasmin system has a role in the process of matrix accumulation and degradation during rat obstructive nephropathy.

Chronic Unilateral Ureteral Obstruction Represented as Renin-Dependent Hypertension

A 50-year-old woman developed renin-dependent hypertension immediately after accidental unilateral ureteral ligation during hysterectomy, and the hypertension lasted for 5 months. Surgical release of the obstruction was carried out 157 days after the ligation. Then, her blood pressure was normalized. However, the obstructed kidney showed intensive tubulointerstitial fibrosis and functional recovery was not obtained. This case suggests that the renin-angiotensin system may be upregulated in human kidney during unilateral ureteral obstruction for a long duration.

Determining the Origin of Hematuria by Immunocytochemical Staining of Erythrocytes in Urine for Tamm-Horsfall Protein

PURPOSE We analyzed the feasibility of immunocytochemical staining of urinary erythrocytes for Tamm-Horsfall protein to differentiate renal from nonrenal hematuria. MATERIALS AND METHODS Urine samples collected from 74 patients with hematuria were evaluated. Erythrocytes in urine were inspected morphologically and the same samples were immunocytochemically stained with antibody against human Tamm-Horsfall protein. RESULTS Erythrocytes in urine were clearly stained for Tamm-Horsfall protein in renal hematuria. Tamm-Horsfall protein immunocytochemistry was more consistent with clinical diagnosis than morphology. CONCLUSIONS Immunocytochemical staining of urine erythrocytes for Tamm-Horsfall protein appears to be a reliable tool to differentiate renal from nonrenal hematuria.

Characterization of G Proteins in Obstructed Kidneys

Background: Urinary tract obstruction has a marked effect on renal function. Activation of phospholipases which results in incremental production of vasoactive eicosanoids may contribute to the hemodynamic changes characteristic of an obstructed kidney. G proteins play an important role in transmembrane signal transduction, which controls phospholipase activities and eicosanoid production. The present study was designed to determine the presence of G proteins in obstructed kidneys in rats, and to characterize the differences between unilateral ureteral obstruction (UUO) and bilateral ureteral obstruction (BUO).