Search PubMed⌕ Search

Biomedical subjects

F Marumo

Publications and source records attributed to F Marumo.

At least 379 records · Page 21Linked to original sources
PubMed1994

Characterization of glutathione efflux from Hep G2 cells.

Previous studies have suggested that both cAMP-dependent signal transduction pathway and Ca2+/protein kinase C-dependent pathway are involved in GSH efflux from hepatocytes. In the present study, GSH efflux from Hep G2 cells, a human-derived hepatoma cell line, was further characterized. Both epidermal growth factor (0.1-10 ng/ml) and insulin (1 microgram/ml) significantly increased GSH efflux from Hep G2 cells. A fall in the membrane potential produced by the replacement of Na+ with equivalent K+ did not affect GSH efflux significantly. Neither ouabain, a Na+/K+ ATPase inhibitor, vanadate, a Ca2+ ATPase inhibitor, nor BaCl2, a K+ channel blocker, significantly affected the GSH efflux. Methionine (1mM) decreased GSH efflux from the cells, although total GSH content in the cells was not affected during the incubation time of 60 min. Signal transductions through tyrosine kinase-coupled receptors may also be involved in GSH efflux from hepatocytes.

Adenosine Triphosphatases↗
PubMed1994

Three cases of malignant hypertension: the roles of endothelin-1 and the renin-angiotensin-aldosterone system.

We experienced three cases of malignant hypertension. Plasma endothelin-1 (ET-1) was extremely high in all patients on admission (12.1 +/- 1.0 pg/ml, normal 1.5 +/- 0.5 pg/ml), and changed in parallel with the serum creatinine level. In one patient, during the recovery period, serum creatinine increased 1 mg/dl over a one-week period just after the increase of plasma ET-1 (14.2 pg/ml), while plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were stable. In contrast, the decline of renal dysfunction was larger in patients with high PRA and PAC. These data suggest that increased plasma ET-1 and an enhanced renin-aldosterone-angiotensin system act together in a vicious cycle to deteriorate renal function in patients with malignant hypertension.

Adult↗
PubMed1994

Enhanced presence of thrombomodulin in the glomeruli of lupus glomerulonephritis.

The intraglomerular presence of thrombomodulin (TM) was examined in 19 patients with lupus glomerulonephritis (GN). TM is a cell surface glycoprotein found on endothelial cells and plays a key role in the protein C anticoagulant pathway. Renal biopsy specimens of patients with lupus GN and several kinds of renal disease other than lupus GN, i.e., membranous GN, IgA GN, minimal change nephrotic syndrome (MCNS) and hemolytic uremic syndrome (HUS) were examined by indirect immunofluorescence, using three kinds of monoclonal antibodies against human TM: KA-2, KA-3 and KA-4. It has been reported that KA-3 and KA-4 bind to enzyme-digested TM as well as intact TM, while KA-2 recognizes intact TM only. In the glomeruli from both normal subjects and patients with MCNS, only very weak staining of TM was found. Patients with HUS showed negative TM staining in the glomeruli. In contrast, positive to strongly positive staining of KA-2 as well as of KA-3 and KA-4 was observed mainly along the capillary wall of glomeruli from patients with lupus GN. Some patients with non-lupus GN showed positive staining of these monoclonal antibodies, but the staining was far more intense in most patients with lupus GN than in the patients with non-lupus GN. Staining of albumin and transferrin by the indirect method was negative in all cases of lupus GN that showed positive staining of TM. There was no relationship between the intensity of TM staining and the degree of proteinuria, creatinine clearance or histologic types of lupus GN.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[A study of urine concentrating mechanism--a molecular biological approach].

Human urine can be concentrated up to four times higher than that of the plasma. Urine concentrating mechanism has attracted for a long time. However, studies in the field are now picking up momentum due to recent breakthrough discoveries using molecular biology techniques. Vasopressin-regulated water channel in the apical membrane of the collecting duct and water channel in the basolateral side of the membrane were cloned. cloned. Osmolality-dependent chloride channel in the thin ascending limb of Henle was also cloned. In addition, vasopressin-regulated urea transporter was found in the collecting duct. These newly discovered channels and transporter should be playing important physiological roles in urine concentrating mechanism. Furthermore, recent findings on osmolytes and their transporters also add to the list of urine concentrating mechanisms.

Amino Acids↗
PubMed1993

Up-regulation of ETB receptor subtype mRNA by angiotensin II in rat cardiomyocytes.

The effect of angiotensin (ANG) II on the expression of endothelin (ET) receptor subtype (ETA, ETB) mRNA in cultured neonatal rat cardiomyocytes was studied. ANG II (10(-7) M) increased steady-state mRNA levels of ETB receptor, but not ETA receptor, during 6-12 hr incubation, whose effect was dose-dependent (10(-9)-10(-7) M). ANG II receptor type-1 (AT1) antagonist (CV-11974) completely inhibited the ANG II-induced up-regulation of ETB receptor, whereas the inhibitory effect by ANG II receptor type-2 (AT2) antagonist (PD 123319) was incomplete. These results suggest that ANG II up-regulates cardiac ETB receptor, predominantly via AT1 receptor.

Angiotensin II↗
PubMed1993

Expression of the hepatocyte growth factor receptor in the regenerating rat liver.

The c-met oncogene product is a cell-surface receptor, which ligand is believed to be the hepatocyte growth factor. We studied the expression of c-met oncogene in the regenerating rat liver after either partial hepatectomy or CCl4-induced liver injury. Northern blot analysis showed that after partial hepatectomy the transcripts of c-met decreased at 8 h, reached the minimum at 36 h, and returned to the steady level on the seventh day. In contrast with the hepatectomized liver, the transcripts of c-met increased after CCl4 treatment. These observations suggest that c-met transcription may be regulated differently depending on regeneration signals.

Amino Acid Sequence↗
PubMed1993

Expression of bone morphogenic protein 7 mRNA in MDCK cells.

Recently, a family of proteins, bone morphogenic proteins (BMPs), have been identified, which promote osteoblast differentiation and bone mineralization. One of them, BMP7, has been shown to be expressed at high levels in the kidney. We detected the message in a kidney tubular cell line, Madin-Darby canine kidney (MDCK) cells. After serum starved for 48h, 8-bromo-cAMP enhanced BMP7 mRNA at 3h and forskolin enhanced it at 6h to 24h in MDCK cells. PMA increased BMP7 mRNA at 6h but down-regulated it at 12h and 20h. The result suggests that BMP7 gene expression may be regulated in MDCK cells by PKA and PKC. MDCK cells can be used in further studies of BMP7 regulation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

Tissue expression of mRNA of chloride channel from MDCK cells and its regulation by protein kinases.

A new chloride channel has recently been identified by expression cloning (Paulmichl, M., et al. Nature 356: 238). To date there is no information available on the distribution of this channel in mammalian tissues. We cloned rat homologue of this Cl channel and found 92% identity in deduced amino-acid sequence. We studied the tissue distribution of its mRNA and regulation by protein kinases. Its mRNA was expressed in all 17 bovine tissues we studied, most abundantly in the brain. In the kidney, it was expressed more in the medulla than cortex. Dehydration up to 5 days did not change its mRNA level in the rat kidney. Both phorbol myristate acetate (PMA) and forskolin down regulated its expression in MDCK cells, suggesting that both PKC and PKA modulated its expression. The physiological role of this chloride channel remains to be clarified.

Amino Acid Sequence↗
PubMed1993

Molecular cloning of a chloride channel that is regulated by dehydration and expressed predominantly in kidney medulla.

Complementary DNA encoding a rat kidney chloride channel (CIC-K1) was isolated by a polymerase chain reaction (PCR) cloning strategy. We designed degenerate primers, based on the regions where previously cloned chloride channels (CIC-0, -1, and -2) possess significant amino acid identity, and performed reverse transcription PCR with whole kidney mRNA. The 686-amino acid protein encoded by CIC-K1 is about 40% identical to the previously cloned chloride channels and has a similar hydropathy profile. Expression of CIC-K1 in Xenopus oocytes induced Cl- currents that activate instantaneously upon hyperpolarization and depolarization, and displayed a slightly outwardly rectifying current-voltage relationship. The message for CIC-K1 was 2.4 kilobases and was found predominantly in kidney, especially in the inner medulla. Reverse transcription PCR technique using micro-dissected nephron segments revealed that the main site of expression in kidney was the thin ascending limb of Henle's loop, which has the highest Cl- permeability among the nephron segments and is thought to be involved in a counter-current system for urine concentration in the inner medulla. The abundance of CIC-K1 mRNA in kidney increased about 4-fold as rats became dehydrated by deprivation of water for 5 days. The site of expression and the regulation by dehydration suggest that CIC-K1 function may be important in urinary concentrating mechanisms.

Amino Acid Sequence↗
PubMed1993

Cloning and expression of apical membrane water channel of rat kidney collecting tubule.

Concentrating urine is mandatory for most mammals to prevent water loss from the body. Concentrated urine is produced in response to vasopressin by the transepithelial recovery of water from the lumen of the kidney collecting tubule through highly water-permeable membranes. In this nephron segment, vasopressin regulates water permeability by endo- and exocytosis of water channels from or to the apical membrane. CHIP28 is a water channel in red blood cells and the kidney proximal tubule, but it is not expressed in the collecting tubule. Here we report the cloning of the complementary DNA for WCH-CD, a water channel of the apical membrane of the kidney collecting tubule. WCH-CD is 42% identical in amino-acid sequence to CHIP28. WCH-CD transcripts are detected only in the collecting tubule of the kidney. Immunohistochemically, WCH-CD is localized to the apical region of the kidney collecting tubule cells. Expression of WCH-CD in Xenopus oocytes markedly increases osmotic water permeability. The functional expression and the limited localization of WCH-CD to the apical region of the kidney collecting tubule suggest that WCH-CD is the vasopressin-regulated water channel.

Amino Acid Sequence↗
PubMed1993

Prevalence of hepatitis C virus infection among long-term hemodialysis patients: detection of hepatitis C virus RNA in plasma.

A high prevalence of anti-C100-3 antibodies has been reported in chronic hemodialysis patients. It is, however, unclear whether the results reflect true hepatitis C virus (HCV) infection in these patients, since false-positive results have been reported with this antibody assay. In the present study, plasma from 184 hemodialysis patients (110 males, 74 females) was examined for HCV-RNA by a reverse transcription-polymerase chain reaction method. Anti-C100-3 antibodies, second generation HCV antibodies, and anti-GOR antibodies were also examined by the respective EIAs. The positive rate of anti-C100-3 in the hemodialysis patients was 10.7% (20/184), which was significantly higher than the reported findings in the general population (P < 0.01). Using a second generation HCV antibody assay, the positive rate increased to 22%. HCV-RNA was detected in 15 of 184 patients (8.2%); 5 of 20 C100-3-positive patients (25%), and 10 of 164 C100-3-negative patients (6.1%). Serum alanine aminotransferase and gamma globulin levels were significantly higher in the patients with these HCV markers than those that were negative, while the history of blood transfusion was not related to the rate of the HCV markers. It is concluded that some hemodialysis patients have latent HCV infections that cannot be detected by currently available HCV antibody assays or routine biochemical liver function tests, and that the routes of transmission are not solely through blood transfusion.

Adolescent↗
PubMed1993

Correlation of plasma hepatitis C virus RNA levels with serum alanine aminotransferase in non-A, non-B chronic liver disease.

The relationship between plasma hepatitis C virus (HCV) RNA levels, antibody positivity, and hepatocellular damage were studied in 41 patients with non-A, non-B chronic liver disease. The patients were placed into two groups according to the plasma levels of HCV-RNA: plasma HCV-RNA level was estimated as high when detected by a one stage polymerase chain reaction (PCR) and as low when detectable only after a two stage PCR. Anti-HCV (first and second generation assays) and anti-GOR were also measured. The mean alanine aminotransferase (ALT) level of the high HCV-RNA group was 115 +/- 62 IU/l, whereas that of the low HCV-RNA group was 59 +/- 37 IU/l (P < 0.05). Patients with ALT levels above 100 IU/l had invariably a high level of HCV-RNA. There were no differences in clinical features in relation to the presence of anti-GOR or anti-HCV. Circulating HCV-RNA levels but not anti-HCV or anti-GOR antibodies correlated with hepatocellular damage.

Aged↗
PubMed1993

Ovariectomy enhances cadmium-induced nephrotoxicity and hepatotoxicity in rats.

The toxicity of cadmium (Cd) chloride was studied in ovariectomized (OX) female rats and non-OX female rats after intravenous administration of the compound at doses of 2.0 and 3.0 mg/kg for 14 days. Mild hypochromic microcytic anemia developed in all rats treated with Cd, but growth retardation in the OX rats was more prominent than that in the non-OX rats. There was an increase of AST and ALT and a decrease of total cholesterol and the A/G ratio in both OX and non-OX rats treated with Cd. The hepatic and renal Cd concentrations increased in a dose-dependent manner, and the concentrations in both organs on Day 14 were comparable in the 3.0 mg/kg OX group (liver, 270.0 +/- 39.6 micrograms/g; kidney, 121.3 +/- 10.1 micrograms/g) and non-OX group (liver, 277.0 +/- 29.9 micrograms/g; kidney, 100.8 +/- 1.3 micrograms/g). Hepatocyte necrosis developed only in OX rats treated with Cd, and the nephrotoxicity of Cd was also notably enhanced by ovariectomy, since Cd nephropathy affected the proximal convoluted epithelium more severely and more frequently in OX rats than in non-OX rats. BrdU-labeled cells in the renal cortex were increased by approximately 2.7-fold in OX rat (7.4 cells/mm2) over those in the renal cortex in non-OX rat (2.7 cells/mm2). In conclusion, the present study demonstrated that ovariectomy enhanced Cd-induced nephrotoxicity and hepatotoxicity in rats.

Animals↗
PubMed1993

Asymptomatic arteriovenous malformation of the pancreas. Demonstration by Doppler ultrasonography and magnetic resonance imaging.

We reported a case of asymptomatic pancreatic AVM, incidentally found on routine ultrasonography and diagnosed noninvasively by means of Doppler ultrasonography and MRI. The diagnosis was confirmed by angiography. This is the first report to demonstrate the characteristics of pancreatic AVM by these two imaging techniques. They proved to be useful in identifying the vascular nature of AVM without the use of a contrast material, which is a definite advantage over DSA and CT. The quality of the image obtained was equivalent or superior to that obtained by DSA and contrast-enhanced CT. Doppler ultrasonography and MRI may serve as the primary imaging techniques of choice in suspected cases of AVM.

Angiography, Digital Subtraction↗