Biomedical subjects

F Marumo

Publications and source records attributed to F Marumo.

At least 271 records · Page 15Linked to original sources

PubMed1995

Effects of nicorandil on kinetics of oxygen uptake at the onset of exercise in patients with coronary artery disease.

The beneficial effects of coronary vasodilators on exercise capacity in patients with angina pectoris are well known. However, their effects on oxygen uptake (VO2) kinetics at the onset of exercise have not been elucidated. The present study was undertaken to determine the acute effects of nicorandil, a newer coronary vasodilator, on the kinetics of VO2 at the onset of exercise in patients with ischemic heart disease. Ten patients with significant coronary stenosis performed constant mild-intensity cycle exercise (32 +/- 3 W) for 6 minutes after oral administration of 10 mg of nicorandil or an identical placebo in a double-blind, crossover manner. Nicorandil had no effect on resting heart rate, blood pressure, or VO2. However, the time constant for the increase in VO2 during constant work rate exercise was significantly shorter (the kinetics of VO2 were faster) after administration of nicorandil than after placebo (46.5 +/- 13.3 vs 51.1 +/- 11.9 seconds; p = 0.039). The increase in VO2 at 6 minutes compared with 3 minutes of constant work, which reflects the VO2 kinetics, also was reduced with nicorandil (3.8 +/- 37.9 vs 27.5 +/- 27.1 ml/min; p = 0.022). Nicorandil was found to increase the rate of VO2, increase during the onset of constant work rate exercise, probably as a result of an improved response in cardiac output. Analysis of VO2 kinetics provides new and useful parameters for the evaluation of circulatory adjustments at the onset of exercise in patients with ischemic heart disease.

Adult↗

PubMed1995

Isolation of human aquaporin 3 gene.

Human aquaporin 3 (AQP3) gene was isolated, and its structural organization was characterized. The gene appeared to exist as a single copy in the human genome and to comprise six exons distributing over 7 kilobases. The sizes of the exons are 171, 127, 138, 119, 218, and 1035 base pairs, and those of introns are approximately 3530, 300, 350, 330, and 90 base pairs, respectively. The initiation site of transcription was identified to locate 64 base pairs upstream of the first ATG codon by primer extension analysis and ribonuclease protection assay. The 5'-flanking region has a TATA box, two Sp1 sequences, and some consensus sequences including AP2 sites. With luciferase assay, the 5'-flanking region was demonstrated to have a promoter activity, which is up-regulated 4-fold by phorbol ester. These findings about the genomic clone of human AQP3 will contribute to elucidate the molecular mechanism of transcriptional regulation of AQP3.

Amino Acid Sequence↗

PubMed1995

Urinary excretion of aquaporin-2 in patients with diabetes insipidus.

BACKGROUND: Urine-concentrating ability is regulated by vasopressin. Recently, the specific water-channel protein of the renal collecting duct, known as aquaporin-2, was cloned. However, it is not certain whether this molecule is responsive to vasopressin. METHODS: We measured the urinary excretion of aquaporin-2 and its response to vasopressin in 11 normal subjects and 9 patients with central or nephrogenic diabetes insipidus. The urine samples were collected during periods of dehydration and hydration and after the administration of vasopressin. Urine samples were analyzed for aquaporin-2 by the Western blot assay and immunogold labeling, and the amount of aquaporin-2 was determined by radioimmunoassay. RESULTS: Aquaporin-2 was detectable in the urine in both soluble and membrane-bound forms. In the five normal subjects tested, the mean (+/- SE) urinary excretion of aquaporin-2 was 11.2 +/- 2.2 pmol per milligram of creatinine after a period of dehydration, and it decreased to 3.9 +/- 1.9 pmol per milligram of creatinine (P = 0.03) during the second hour after a period of hydration. In the six other normal subjects, an infusion of desmopressin (1-desamino-8-D-arginine vasopressin) increased the urinary excretion of aquaporin-2 from 0.8 +/- 0.3 to 11.2 +/- 1.6 pmol per milligram of creatinine (P < 0.001). The five patients with central diabetes insipidus also had increases in urinary excretion of aquaporin-2 in response to the administration of vasopressin, but the four patients with X-linked or non-X-linked nephrogenic diabetes insipidus did not. CONCLUSIONS: Aquaporin-2 is detectable in the urine, and changes in the urinary excretion of this protein can be used as an index of the action of vasopressin on the kidney.

Adult↗

PubMed1995

Structure and chromosomal localization of a human water channel (AQP3) gene.

A cDNA encoding rat AQP3, a water channel and a member of the MIP family, that is expressed predominantly in kidney medulla and colon was cloned recently. To determine the structure, tissue distribution, and chromosomal localization of the human AQP3 gene, we screened a human kidney cDNA library with rat AQP3 probe and isolated a cDNA coding for human AQP3 protein. The deduced amino acid sequence of human AQP3 was 91% identical to rat AQP3. Human AQP3 mRNA was expressed in colon, kidney, liver, pancreas, lung, peripheral leukocytes, spleen, and prostate. The human AQP3 gene was mapped to 7q36.2-q36.3 by chromosome fluorescence in situ hybridization.

Amino Acid Sequence↗

PubMed1995

cAMP-dependent phosphorylation stimulates water permeability of aquaporin-collecting duct water channel protein expressed in Xenopus oocytes.

Among water channel proteins (aquaporins), aquaporin-collecting duct (AQP-CD) is the vasopressin-regulated water channel. Vasopressin causes cAMP production in the renal collecting duct cells, and this is believed to lead to exocytic insertion of water channel into the apical membrane (shuttle hypothesis). AQP-CD contains a consensus sequence for cAMP-dependent protein kinase, residues at positions 253-256 (Arg-Arg-Gln-Ser). To determine the role of this site, Ser-256 was substituted for Ala, Leu, Thr, Asp, or Glu by site-directed mutagenesis. In Xenopus oocytes injected with wild-type or mutated AQP-CD cRNAs, osmotic water permeability (Pf) was 4.8-7.7 times higher than Pf of water-injected oocytes. Incubation with cAMP plus forskolin or direct cAMP injection into the oocytes increased Pf of wild-type, but not mutated, AQP-CD-expressing oocytes, whereas the amounts of AQP-CD expression were similar in wild and mutated types as identified by Western blot analysis. In vitro phosphorylation studies of AQP-CD proteins expressed in oocyte showed that cAMP-dependent protein kinase phosphorylated wild-type, but not mutated, AQP-CD proteins. Phosphoamino acid analysis revealed that this phosphorylation occurred at the serine residue. Moreover, phosphorylation of AQP-CD protein in intact rat kidney medulla tissues was stimulated by incubation with cAMP. Our data suggest that cAMP stimulates water permeability of AQP-CD by phosphorylation. This process may contribute to the vasopressin-regulated water permeability of collecting duct in addition to the apical insertion of AQP-CD by exocytosis.

Animals↗

PubMed1995

Evaluation of exercise capacity using submaximal exercise at a constant work rate in patients with cardiovascular disease.

BACKGROUND: Symptom-limited incremental exercise tests are used to estimate the severity of cardiovascular disease and the patient's daily activity. However, there is a need for objective parameters for submaximal exercise. To test the hypothesis that a decrease in maximal exercise capacity can be estimated by oxygen uptake (VO2) kinetics, we measured the time constant of VO2 both during the onset of constant work rate exercise at 50 W and during recovery from this exercise and compared it with data obtained during maximal exercise in patients with cardiovascular disease and in normal subjects. METHODS AND RESULTS: A total of 34 patients with cardiovascular disease and 14 normal subjects performed 6 minutes of 50-W constant work rate exercise and an incremental exercise test to the symptom-limited maximum on a cycle ergometer. VO2 was calculated from respiratory gas analysis on a breath-by-breath basis. The time constant of VO2 during the onset of 50-W exercise was 61.4 +/- 15.2 seconds in patients with cardiovascular disease, significantly longer (the kinetics of VO2 were slower) than that in normal subjects (48.8 +/- 10.4 seconds, P = .008). The time constant of VO2 during the onset of exercise was significantly negatively correlated with peak VO2 (r = -.67) and maximal work rate (r = -.66). The time constant during recovery, which did not differ significantly from that of exercise, was also prolonged in patients with cardiovascular disease; it showed a negative correlation with peak VO2 (r = -.63) and maximum work rate (r = -.54). CONCLUSIONS: The time constant of VO2 during and after recovery from 50 W of constant work rate exercise, which does not require the subject's maximal effort, is a useful and objective measure of exercise capacity in patients with mild to moderate cardiovascular disease.

Adult↗

PubMed1995

Comparison of the hypervariable region of hepatitis C virus genomes in plasma and liver.

Nucleotide sequences of the hypervariable region of hepatitis C virus genomes obtained from plasma change rapidly during the course of infection and are believed to play a part in immunological escape and consequently in the development of persistent infection. It is not known, however, whether these changes also occur in the liver. To clarify this aspect, RNA was extracted from the plasma and liver tissue of eight patients with chronic hepatitis C. After cDNA synthesis, DNA fragments that included the hypervariable region were amplified by the polymerase chain reaction. Consensus nucleotide sequences were determined directly from the polymerase chain reaction products by the dideoxy chain termination method. The diversity of the hypervariable region was analyzed further by the polymerase chain reaction-single strand conformation polymorphism analysis. Consensus nucleotide sequences of the hypervariable region were identical between the plasma and the liver in each patient. The polymerase chain reaction-single strand conformation polymorphism analysis showed multiple DNA bands that represented different hypervariable region sequences. Comparison of the single strand conformation polymorphism patterns revealed that the number, the mobility, and the density of bands were the same between the plasma and the liver. It is concluded that the population and the diversity of hepatitis C virus quasispecies as detected by the hypervariable region sequence are the same between the plasma and the liver despite rapid mutations, indicating that rapid changes in the population of hepatitis C virus quasispecies also occur in the liver.

Amino Acid Sequence↗

PubMed1995

Fraction-specific populations of the hypervariable region of the hepatitis C virus in a patient with cryoglobulinemia.

Nucleotide sequences of the hypervariable region (HVR) of the E2/NS1 gene of hepatitis C virus (HCV), which are now thought to contain epitopes for neutralizing antibodies, were compared between antibody-bound HCV and free HCV in a patient with type II cryoglobulinemia. Antibody-bound HCV was immunoprecipitated with anti-human immunoglobulins from serum of the patient. Total RNA was recovered from the pellet and the supernatant, respectively, and the envelope gene containing the HVR was amplified by the reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by the single strand conformation polymorphism (SSCP) analysis. Sequences of bands separated by SSCP analysis were determined by the dideoxy chain termination method. SSCP analyses revealed that the HCV populations were completely different between antibody-bound HCV and free HCV: antibody-bound HCV was composed of two bands and free HCV was composed of three bands. These five bands showed different mobility with each other on the SSCP gel. Sequencing of each band revealed distinct HVR sequences, differing in 1-34 nucleotides and 1-15 deduced amino acids. Three sequences of free HCV was similar with each other (1-5 nucleotide and 1-4 amino acid differences). On the other hand, two sequences of antibody-bound HCV had 5-34 nucleotide and 5-15 amino acid differences with free HCV. Thirteen amino acids in the 5' of HVR were completely identical in three sequences of free HCV, whereas there were three and seven amino acid differences in two sequences of antibody-bound HCV. These findings suggest that isolated specific epitopes for envelope antibodies exist within the HVR.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1995

Variations in the core region of hepatitis C virus genomes in patients with chronic hepatitis.

In each infected patient, the population of hepatitis C virus is composed of quasispecies that differ in their nucleotide sequences. Among regions in hepatitis C virus genomes, nucleotide sequences of the hypervariable region have been shown to change quickly during the course of infection. It is not known, however, whether these variations exist in the core region that has recently been suggested to contain human lymphocyte antigen class 1 restricted sites for cytotoxic T cell recognition. To clarify this, RNA was extracted from the plasma of four patients with chronic hepatitis C. After cDNA synthesis, DNA fragments that contain the core region were amplified by the polymerase chain reaction and the diversity of the core region was analyzed by the single strand conformation polymorphism analysis. Using this method, single or multiple DNA bands were observed in each patient, and representative bands showed different nucleotide sequences. Comparison of single strand conformation polymorphism patterns revealed that the population of quasispecies changed during the course of chronic infection. These changes were more remarkable in patients with high serum alanine aminotransferase levels than those with low serum alanine aminotransferase levels. Thus, sequential variations exist in the core region of hepatitis C virus in same individuals, and the population of quasispecies as determined by the sequence of the core region changes during the course of infection, which might be related to cytopathic effects of hepatitis C virus.

Alanine Transaminase↗

PubMed1995

Host dependent variation of hepatitis C virus: phylogenetic analyses.

Hepatitis C virus quasispecies in six patients from three families were separated by single strand conformation polymorphism analysis and by determination of nucleotide sequences of envelope regions containing the E1 gene segment and hypervariable region-1 of each quasispecies. Four of the six patients had multiple quasispecies. Phylogenetic analyses indicated that all quasispecies from one individual were highly homologous to each other. The homology was higher in the E1 gene segment than in hypervariable region-1. Furthermore, all quasispecies found in members of one family (husband and wife) were also highly homologous, suggesting direct intrafamilial transmission. The direction of hepatitis C virus variation in hypervariable region-1, however, seems to differ depending on the host in intrafamilial transmission.

Adolescent↗

PubMed1995

Severe chronic active hepatitis induced by UFTR containing tegafur and uracil.

A 77-year-old female patients developed severe hepatic injury after the administration of UFTR, which contains tegafur and uracil, for postoperative chemotherapy of colon cancer. Liver damage was recognized 10 months after its administration. Serum markers for viral hepatitis and various autoantibodies were negative. The wedged biopsied liver specimen revealed advanced chronic active hepatitis with periportal confluent necrosis, marked intralobular spotty necrosis, and significant proliferation of pseudo-bile ductules. Although the cessation of the drug and conservative therapies improved hepatic function, an accidental readministration of UFTR caused her severe hepatic damage again. These findings suggest that liver injury in the present case was caused by UFTR. Histological findings were unique. Although tegafur is known to worsen hepatic function when given to patients with liver cirrhosis, UFTR may also cause severe hepatic injury in those without preexisting liver disease.

Aged↗

PubMed1995

Increased renal susceptibility to gentamicin in the rat with obstructive jaundice. Role of lipid peroxidation.

To study whether renal susceptibility to nephrotoxic stimuli is increased in obstructive jaundice, the effect of gentamicin on the renal function in bile duct-ligated rats was investigated. Gentamicin (50 mg/kg/day, subcutaneously) or saline was given to bile duct-ligated rats or sham-operated rats for six days. Mortality in the bile duct-ligated group that received gentamicin was 64% whereas that in the other groups was 0%. In the bile duct-ligated group, although serum creatinine and blood urea nitrogen were minimally affected, focal granulo-vacuolar degeneration in the proximal tubule was observed, which was accompanied by an increase in renal malondialdehyde. Gentamicin significantly increased serum creatinine and blood urea nitrogen levels and caused marked degeneration in the proximal tubule in the bile duct-ligated group, which was accompanied by a further increase in renal malondialdehyde, while these changes were not observed in the sham group. The kidney in obstructive jaundice appears to be susceptible to gentamicin. Enhanced production of oxygen radicals may be responsible for this effect.

Animals↗

PubMed1995

Nonselective ETA/ETB receptor antagonist blocks proliferation of rat vascular smooth muscle cells after balloon angioplasty.

To elucidate the role of endothelin receptor subtypes in the abnormal proliferation of vascular smooth muscle cells (VSMC) associated with vascular injury, we have investigated the effects of a novel and potent nonselective ETA/ETB receptor antagonist (TAK-044) on the proliferation of rat VSMC in vitro and in vivo. TAK-044 dose-dependently inhibited DNA synthesis stimulated by 10(-7) M ET-1 in cultured rat VSMC from the late passage with the approximate IC50 of 6 x 10(-8) M. After balloon angioplasty, the neointimal lesion in the injured carotid arteries in the TAK-044-treated group (0.052 +/- 0.014 mm2) was significantly (p < 0.05) decreased compared to that in control group (0.26 +/- 0.045 mm2), while the medial surface area was not affected. The intima/media ratio in the TAK-044 group (31 +/- 6%) also significantly (p < 0.05) decreased from that of the control group (148 +/- 25%). Our data suggest that nonselective ETA/ETB receptor antagonists may be therapeutic potential for prevention against the intimal thickening associated with vascular injury.

Angioplasty, Balloon↗

PubMed1995

Characterization of immunoreactive adrenomedullin in human plasma and urine.

Adrenomedullin(AM) is a novel vasodilator peptide recently isolated from pheochromocytoma. Using a specific and sensitive radioimmunoassay for human AM, we have characterized immunoreactive AM in human plasma and urine. Patients with chronic renal failure had about five-fold higher plasma immunoreactive AM levels than normal subjects, which did not change before and after hemodialysis. Immunoreactive AM was present in normal human urine, whose concentrations were about six-fold greater than those in human plasma. Reverse-phase HPLC of human plasma and urine revealed that immunoreactive AM emerged as a single peak at a position identical to that of authentic human AM(1-52). These data suggest that circulating AM is cleared by the kidney and urinary excretion of AM may be derived from glomerular filtration and/or its renal production.

Adrenomedullin↗

PubMed1995

Detection and analysis of replicating hepatitis C virus RNA in hepatocellular carcinoma tissues.

Although persistent hepatitis C virus infection is closely associated with the development of hepatocellular carcinoma, the nature of hepatitis C virus replication in the hepatocellular carcinoma tissue has not been fully characterized. To study this, carcinoma and non-carcinoma tissues were obtained from five patients with hepatocellular carcinoma. Total RNA was recovered from each tissue, and a portion of the envelope gene of replicating hepatitis C virus was amplified by minus-strand-specific reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by single strand conformation polymorphism analysis and sequencing. Hepatitis C virus replication was detected in both carcinoma and non-carcinoma tissues in four patients who were positive for serum hepatitis C virus markers. In one patient, a single species with identical envelope 2 genome was obtained from both carcinoma and non-carcinoma tissues. In the other three patients, the replicating hepatitis C virus existed as a mixture of 2-5 species with different but highly homologous (82-99%) envelope 2 genomes (quasispecies populations). The constitution of viral populations was different between carcinoma and non-carcinoma tissues. A total of ten sequences were recovered; four sequences were found in both tissues, two were found in carcinoma tissues, and four were found in non-carcinoma tissues. The difference in the constitution of quasispecies populations between carcinoma and non-carcinoma tissues confirms the unequivocal replication of hepatitis C virus in both tissues, and may imply the presence of different biological properties among hepatitis C virus with different sequences.

Amino Acid Sequence↗

PubMed1995

Expression of gap junction protein connexin 32 and E-cadherin in human hepatocellular carcinoma.

The expression of connexin 32, a major gap junction protein, and E-cadherin, an intercellular adhesion molecule that is supposed to be involved in the regulation of gap junctional intercellular communications, was examined immunohistochemically in seven specimens of human hepatocellular carcinoma and surrounding non-carcinomatous tissues. We found that the number of connexin 32-positive spots per mm2 was significantly less in hepatocellular carcinoma tissues than in the surrounding non-carcinomatous cirrhotic tissues (4360 +/- 3390/mm2 vs 10,030 +/- 3690/mm2; p < 0.01). The number in the latter was also significantly less than that in normal controls (23,560 +/- 4170/mm2). E-cadherin was expressed in all non-carcinomatous hepatocytes as well as carcinomatous cells, except for one case of Edmondson's grade III hepatocellular carcinoma. These results suggest an impairment of cell-to-cell communications in human hepatocellular carcinomas.

Cadherins↗

PubMed1995

Differential localization of atrial natriuretic peptide and skeletal alpha-actin messenger RNAs in left ventricular myocytes of patients with dilated cardiomyopathy.

OBJECTIVES: This study was designed to determine whether atrial natriuretic peptide and skeletal alpha-actin messenger RNAs (mRNAs) are co-localized in ventricular myocytes of patients with dilated cardiomyopathy. BACKGROUND: Atrial natriuretic peptide and skeletal alpha-actin are known as augmented genes with cardiac hypertrophy. However, the expression and localization of both genes in chronic failing heart remain unclear. METHODS: Left ventricular biopsy specimens were obtained from 14 patients with dilated cardiomyopathy. Atrial natriuretic peptide and skeletal alpha-actin mRNAs were detected by in situ hybridization with specific sulfur-35 uridine triphosphate-labeled RNA probes in the serial sections. RESULTS: Atrial natriuretic peptide mRNA was detected in 10 patients, and intense signals were localized in the myocytes located in the subendocardium and around the interstitial fibrous area. By contrast, skeletal alpha-actin mRNA was homogeneously detected in all myocytes in seven patients. By left ventriculography, patients with skeletal alpha-actin-positive findings had a lower ejection fraction (37.1 +/- 6.0%) than those with negative findings (46.3 +/- 5.8%, p < 0.05), but atrial natriuretic peptide mRNA expression was not related to left ventricular function. CONCLUSIONS: These results indicate that the expression of atrial natriuretic peptide and skeletal alpha-actin mRNAs are not always co-localized in the left ventricle of patients with dilated cardiomyopathy and suggest that the mechanisms of the regulation of these two genes in the chronic failing heart are different.

Actins↗

PubMed1995

Stable and functional expression of the CIC-3 chloride channel in somatic cell lines.

The CIC family is the superfamily of voltage-gated Cl- channels. Although the CIC channels expressed in Xenopus oocytes have been characterized, their channel properties are still poorly understood. We recently cloned a unique member of the CIC family, CIC-3, that is expressed abundantly in neurons. Its channel activity was regulated by phorbol esters. Now, we have established a stably transfected somatic cell line expressing functional CIC-3 channels and examined the CIC-3 single-channel current by patch-clamp techniques. In inside-out patches from the stably transfected cells, a rise of bath Ca2+ concentration in the physiological range of intracellular Ca2+ concentrations inhibited the CIC-3 single-channel currents. This inhibition by Ca2+ was independent of phosphorylation and ATP. Thus, the CIC-3 channel is a Ca(2+)-sensitive Cl- channel localized in neuronal cells, and its Ca2+ sensitivity implies a physiological role in neuronal functions.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗