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Biomedical subjects

M Kuboki

Publications and source records attributed to M Kuboki.

At least 19 recordsLinked to original sources
PubMed1999

A cohort study of hepatitis C virus (HCV) infection in an HCV epidemic area of Japan: age and sex-related seroprevalence of anti-HCV antibody, frequency of viremia, biochemical abnormality and histological changes.

We studied the age- and sex-specific prevalence of hepatitis C virus (HCV) infection and aminotransferase abnormalities as well as histological changes in the liver associated with HCV infection. Of the eligible 3,707 inhabitants aged 6 years and older in an HCV infection epidemic area 2,382 (64.3%) were examined. The anti-HCV positivity rate was 20.7% on average and increased according to age. Age was the most potential risk indicator for anti-HCV positivity by multiple stepwise regression analysis. The HCV RNA positivity rate in females with anti-HCV was significantly lower than that in males. However, as the age of females increased, the HCV RNA positivity rate became higher. The proportion of subjects with aminotransferase abnormalities among HCV RNA-positive subjects was significantly lower in females than males. Aminotransferase abnormalities significantly increased with age in females. In subjects with abnormal aminotransferase levels, nearly half of the HCV RNA-positive females were aged 50 or older and also nearly half of the male subjects showed CAH2B or liver cirrhosis, while most of the HCV RNA-positive females younger than 50 exhibited histological findings consistent with CPH. In conclusion, age was the principal risk indicator for HCV infection in this area. Females, especially those younger than 50, both biochemically and histologically showed less severity of HCV infection than males. Gender and age might have effects on the outcome of HCV related liver disease.

Adolescent↗
PubMed1999

Molecular epidemiology of hepatitis C virus infection in an area endemic for community-acquired acute hepatitis C.

The southern district of N city (U area), Yamagata Prefecture, is highly endemic for hepatitic C virus (HCV) infection. Around 20% of the general population are positive for antibodies to HCV (anti-HCV). Community-acquired, acute non-A, non-B hepatitis was epidemic from 1967 to 1972 in this area. Our previous study revealed that these people are actually infected with HCV, but a relationship between this outbreak and the high positivity rate of anti-HCV in the U area has not been shown. We followed up 15 anti-HCV-positive individuals who developed hepatitis during the epidemic and used the serum collected to conduct molecular evolutional analysis to reveal the characteristics of the HCV epidemic in the U area. HCV genotypes in the U area were also analyzed. Phylogenetic analysis of the HCV core gene sequences showed that the subjects' HCV sequences were closely related and derived from the same cluster. All subjects were infected with HCV genotype 1b, which was frequently detected with a high positivity of over 80% of HCV-infected individuals in the U area. These results confirm that the community-acquired hepatitis C epidemic occurred around three decades ago through an unidentified route, and suggest that this episode may result in a continuing increase in the number of HCV-1b positive patients in this small area.

Acute Disease↗
PubMed1998

Secondary structure of the hepatitis C virus 5' untranslated region and efficacy of interferon therapy for chronic hepatitis C.

UNLABELLED: The hepatitis C virus 5' untranslated region (HCV 5'UTR) contains secondary structures typical of internal ribosome entry site elements leading to translation. Variations of this secondary structure in relation to the efficacy of interferon (IFN) therapy were investigated. METHODS: Natural IFN-alpha was administered to 22 patients with chronic hepatitis C due to HCV subtype 1b and their serum HCV-RNA levels were examined using the reverse-transcription polymerase chain reaction (RT-PCR). The HCV 5'UTR sequence was determined by direct sequencing, and variations of the putative secondary structure were detected by analyzing single-strand confirmation polymorphisms (SSCP) in the patient's sera. RESULTS: Five of the 22 patients (22%) were complete responders to IFN and eradicated HCV-RNA from their sera and 17/22 (78%) were nonresponders in whom HCV-RNA persisted. The SSCP electrophoretic results predicted the efficacy of IFN therapy: the complete responders showed greater pattern diversity than the nonresponders. The serum HCV-RNA level correlated with the SSCP electrophoretic pattern: patients with the IFN-resistant SSCP electrophoretic pattern had higher levels than the others (10.1+/-2.4 vs 1.2+/-0.4 Meq/ml; p<0.001). Sequencing analysis suggested three one-point mutations influence alteration of the secondary structure. CONCLUSIONS: Analysis of the secondary structure of the HCV 5'UTR contributes to predicting viremia severity and the efficacy of IFN therapy in patients with chronic hepatitis C.

5' Untranslated Regions↗
PubMed1996

Prevalence of inhabitants with anti-hepatitis C virus antibody in an area following an acute hepatitis C epidemic: age-and area-related features.

The northern district of R Town, Yamagata Prefecture, Japan, experienced an epidemic of acute hepatitis C during the 6 years following 1967. A mass survey health examination for hepatitis C virus (HCV) infection was performed on the inhabitants of this district aged 6 or over (4,655 people). Of the 3,094 inhabitants (66.5%) examined, 602 (19.5%) were anti-HCV antibody (anti-HCV) positive. Of the 602 anti-HCV positive subjects, 444 (73.7%) showed an anti-HCV cutoff index of over 4.0 (high titer), 54 (9.0%) showed 3.0 approximately 4.0 (middle titer), and 104 (17.3%) showed an index of under 3 (low titer). One hundred and sixty subjects, randomly selected, were examined for HCV RNA by nested polymerase chain reaction, and positive reactions were detected in 125 subjects (78.1%). The anti-HCV positive rate differed greatly between subjects younger than 40 years (18/1,289; 1.4%) and those 40 or over (584/1,805; 32.4%). Those who had lived in this district since before the acute hepatitis C epidemic had a high rate of positive anti-HCV. Among the 47 hamlets in this farming district, the hamlet with the highest rate (71.4%) was surrounded by other hamlets where the rates decreased as the distance from the high rate hamlet increased. The study suggested a marked regional accumulation of HCV infection in this district and an age-related difference in HCV infection rates. The cause of the accumulation was not identified, although the HCV infection in this district may have been spread during or before the acute hepatitis C epidemic and produced many HCV carriers.

Adolescent↗
PubMed1994

A randomized, controlled trial of human lymphoblastoid interferon in patients with compensated type C cirrhosis.

OBJECTIVE: To determine the efficacy of human lymphoblastoid interferon (L-IFN) in the treatment of compensated type C cirrhosis, 30 patients were assigned randomly to three groups, consisting of 10 patients each, who were treated as follows. METHODS: The 1- and 3-megaunit (MU) groups received 1 or 3 MU of L-IFN, respectively, daily for 2 wk, and three times weekly for 24 wk thereafter. The control group received no treatment. All of the patients had positive C100-3 hepatitis C virus antibody (anti-HCV) titers. RESULTS: The serum alanine aminotransferase (ALT) levels decreased 26 wk after L-IFN treatment was began, in both treatment groups. In the 3-MU group, the ALT levels became normal [complete response (CR)] in 40%, improved to less than twice the upper limit of the normal value [partial response (PR)] in 10%, and remained unchanged [no change (NC)] in 50%. In the 1-MU group, a PR occurred in 30%. There was NC in 70%, and NC occurred in the control group. Twenty-four weeks after stopping L-IFN, the CR and NC rates in the 3-MU group were 10% and 90%, respectively, and NC was observed in all of the 1-MU and control patients. 2',5'-Oligoadenylate synthetase activities increased in both treatment groups (p < 0.05), but not in the control group. The anti-HCV titers decreased in the 3-MU group (p < 0.05), but not in the 1-MU and control groups. Higher doses of L-IFN were more effective. No serious side effects occurred. CONCLUSIONS: These findings suggest that IFN administration can be effective and safe in patients with compensated type C cirrhosis, and that it would be worthwhile to evaluate IFN therapy for cirrhotic patients further.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Procalpain I in cytoplasm is translocated onto plasma and granule membranes during platelet stimulation with thrombin and then activated on the membranes.

Thrombin stimulation of platelets resulted in changes in the subcellular localization of calpain I, with a concomitant alteration of its molecular weight as measured by immunoblotting. Calpain I in resting platelets was distributed as procalpain I, an 80 kDa form which does not exhibit the enzyme activity, and 83% of the total antigen was localized in the cytosol fraction. When platelets were stimulated with thrombin, the total content of calpain I antigen was not significantly changed as compared with that of the resting platelets, though a decrease in the cytosolic distribution of 80 kDa form (from 83% to 47% of the total antigen) was observed with concomitant appearance of the active 76 kDa and intermediate 78 kDa forms of calpain I and increase in the 80 kDa form in the granule and membrane fractions. These results indicated that calpain I was translocated from the cytosol to both the plasma and granule membranes as procalpain I and then activated on the membranes during platelet stimulation with thrombin.

Blood Platelets↗
PubMed1992

Activation of calpain I in thrombin-stimulated platelets is regulated by the initial elevation of the cytosolic Ca2+ concentration.

The source and concentration of Ca2+ required to activate calpain I were investigated in thrombin-stimulated platelets. The concentration of cytosolic free Ca2+ ([Ca2+]i) was measured in platelets containing fura-2-AM, and exhibited a biphasic response after stimulation with 0.05, 0.1 or 0.5 NIH units of thrombin/ml. An initial transient elevation, which was predominantly dependent upon Ca2+ released from the internal stores into the cytosol, peaked at 15 s after stimulation, and a secondary sustained elevation, which was due to Ca2+ influx, was observed following the initial elevation. Calpain I was present at about 540 ng/10(8) unstimulated platelets, as measured by immunoblotting using rabbit anti-(human calpain I) IgG. Calpain I was activated 10 s after thrombin stimulation, as determined by the appearance of the 78 kDa and 76 kDa forms on immunoblots. The activation ratio of calpain I was calculated as the amount of the 78 + 76 kDa forms as a percentage of the total (80 + 78 + 76 kDa), and was influenced by the extent of the initial transient [Ca2+]i elevation after stimulation. An initial increase in [Ca2+]i of 300 nM was required to achieve the maximal activation (60%) of calpain I, and half-maximal activation occurred at 160 nM- Ca2+]i. These results suggest that the activation of calpain I in platelets is regulated by the initial elevation in Ca2+]i after thrombin stimulation, and does not necessarily require a Ca2+ influx.

Adult↗
PubMed1992

[Intracellular Ca2+ behavior and activation of calpain-I in activated platelets].

A relationship between intracellular Ca2+ concentration ([Ca2+]i) and calpain-I activation and change in subcellular localization of the enzyme in activated platelets were investigated. The [Ca2+]i exhibited a biphasic response after stimulation with thrombin. Activation of calpain-I was measured by determination of the appearance of active 76 and 78 kDa forms accompanying the disappearance of the 80 kDa form, the inactive form, on immunoblots. Calpain-I was activated dependent on the extent of the initial elevation of [Ca2+]i. For maximum activation (60%) 300-500 nM [Ca2+]i was required and half-maximal activation occurred at 160-220 nM [Ca2+]i. The active 76 kDa form was observed only in the fraction containing subcellular organelles and plasma membrane of activated platelets. It was demonstrated that the localization of calpain-I was changed from the cytosol to the membrane and calpain-I was activated on the membrane by Ca2+, elevated through the initial elevation after activation of platelets.

Calcium↗
PubMed1991

[Analysis of factors affecting hepatic dysfunction during group health checks for local inhabitants].

During health checks within the framework of the Geriatric Health Law, hepatic dysfunction was detected at a high incidence in inhabitants of K town. The factors affecting hepatic dysfunction in these cases were explored. The number of inhabitants who received health checks in 1989 in this town was 4,491 (78.5% of all inhabitants aged over 35 years). A diagnosis of hepatic dysfunction was made if GOT was equal to or higher than 41 IU/l or GPT was equal to or higher than 39 IU/l. On this basis, hepatic dysfunction was detected in 418 inhabitants (9.8%). The incidence of hepatic dysfunction was higher in males than in females. Inhabitants younger than 50 years had a higher incidence than those 50 years or older. The percentage of inhabitants with either a history of alcohol consumption or of receiving blood transfusion was significantly higher for inhabitants with hepatic dysfunction (29% and 10%, respectively) than for healthy inhabitants (10% and 3%, respectively). HBs antigen and anti HCV antibody positive rates for inhabitants with hepatic dysfunction were 3.3% and 36.1% respectively. These results suggest that the relatively high rate of hepatic dysfunction in this town is related to alcohol consumption, blood transfusion and hepatitis C virus (HCV) infection. Of these three factors, the influence of HCV infection seemed to be the most influential. The study additionally disclosed variations in the incidence of hepatic dysfunction among the different regions of the town probably related to regional differences in the anti-HCV antibody positive rate.

Adult↗
PubMed1990

Thiolprotease inhibitor, EST, can inhibit thrombin-induced platelet activation.

Participation of thiolprotease in platelet activation was investigated. When platelets were treated with EST (L-trans-epoxysuccinyl-leucylamide (3-methyl)butane-ethyl ester, a membrane-permeable thiolprotease inhibitor) for 30 min, thrombin-induced aggregation and secretion were inhibited, and remained so even when the platelets were washed and resuspended in EST-free medium after the pretreatment. The inhibitory action of EST on thrombin-induced platelet aggregation and secretion was both dose-dependent and incubation-time-dependent. The inhibitory action of EST on platelet aggregation and secretion was shown not only in response to thrombin but also to platelet activating factor (PAF). Pretreatment of platelets with 1 mM EST for 30 min inhibited the 65% of calpain (thiolprotease) activity in platelets. The phosphorylation of 40 kDa and 20 kDa proteins of platelets caused by stimulation with thrombin was blocked by the pretreatment with 1 mM EST. Phosphatidylinositol hydrolysis and inositol-1-phosphate production, which appear after stimulation of platelets with thrombin, were also inhibited by the pretreatment with 1 mM EST. The results suggest that EST was incorporated to inside of platelets, and inhibited activation of platelet through inhibition of thiolprotease.

Adult↗
PubMed1990

Characterization of calpain I-binding proteins in human erythrocyte plasma membrane.

The calpain-binding components on the plasma membrane were characterized using calpain I. 125I-labeled calpain was bound to inside-out membrane vesicles from human erythrocyte in a Ca2(+)-dependent manner, but not to right-side-out membrane vesicles. The maximum binding was observed at more than 5 microM Ca2+. The binding amount of calpain to the inside-out membrane vesicles was decreased when the vesicles were pretreated with 100 micrograms/ml of trypsin, chymotrypsin, elastase, or pronase P for 30 min at 37 degrees C, although the binding to the vesicles pretreated with 200 micrograms/ml of phospholipase A2 or C was not affected. Calpain-binding proteins in the membrane were analyzed by using a modified immunoblotting for calpain. Immunostained bands of 240, 220, 89, 72, 52, and 36 kDa were detected as the calpain-binding proteins in the native membrane. All of these bands had disappeared in trypsin-treated membrane. The disappearance of bands was dose-dependent with respect to trypsin and paralleled the reduction of binding amount of calpain to the trypsinized membrane. In calpain-treated membrane, the 240 and 36 kDa bands were retained in the blotting, though the other bands disappeared dose-dependently with respect to calpain. These results suggested that the significant component in the inner surface of plasma membrane for binding of calpain was proteinaceous and the calpain-binding proteins could be classified into two species, i.e. substrates of calpain (220, 89, 72, and 52 kDa protein) and non-substrates (240 and 36 kDa protein).

Calpain↗
PubMed1988

ST-segment fluctuation during treadmill exercise in patients with angina pectoris.

The level of the ST-segment fluctuates transiently during treadmill exercise in some patients with angina pectoris. In the present study, the incidence and clinical significance of ST-segment fluctuation were studied before and after propranolol in 52 patients with angina pectoris. A transient greater than 0.5-mm (0.05 mV) upward shift of the ST-segment during a graded treadmill test was considered a significant fluctuation in leads without signs of previous myocardial infarction. The fluctuation was observed in three of 30 patients with rest or rest and effort angina pectoris before propranolol and in 14 of them after propranolol, while only one of 22 patients with effort angina alone showed fluctuation after the drug. Coronary arteriography revealed that in 15 patients showing ST-segment fluctuation with propranolol, seven patients had no significant coronary stenosis, six had one-vessel disease and two had two-vessel disease. In 24 patients with documented coronary artery spasm, ST-segment fluctuation was induced in two (8%) before propranolol and in 13 (54%) after propranolol. Our results suggest that ST-segment fluctuation during graded treadmill exercise may be related to transient coronary vasospasms exacerbated by propranolol.

Adult↗
PubMed1987

Procalpain is activated on the plasma membrane and the calpain acts on the membrane.

The mechanism of activation of human erythrocyte calpain was investigated using the immunoblotting technique with anticalpain monoclonal antibody. The purified calpain underwent a Ca2+-induced fragmentation of the 80 kDa subunit to 76 kDa and 36 kDa fragments. The behavior of the 76 kDa fragment in electrophoresis corresponded to the proteinase activity of calpain, whereas the behavior of the 80 kDa subunit and the 36 kDa fragment did not. When inside-out membrane vesicles were added to the reaction mixture of calpain and Ca2+ and the vesicles were separated from the supernatant solution by centrifugation, the 80 kDa subunit and 76 kDa fragment were found in the vesicle fraction. No other fragments were found in this fraction. On the other hand, the 80 kDa subunit and 36 kDa fragment were found in the supernatant fraction. When right-side-out membrane vesicles were added to the reaction mixture and the vesicles were separated from the supernatant fraction, no fragment was found in the vesicle fraction, while only the 36 kDa fragment was found in the supernatant fraction. These results indicate that the 80 kDa subunit of procalpain was bound in a Ca2+-dependent manner to the cytosolic surface of the plasma membrane and then underwent fragmentation to produce the 76 kDa fragment (active form) and that it expressed its proteinase activity at the surface of the membrane.

Antibodies, Monoclonal↗
PubMed1985

[Effect of intraperitoneal injection of topical thrombin on the coagulation and fibrinolysis of rabbits with experimental liver damages].

Topically applied thrombin was known to be effective in hemostasis of local bleeding, but complications of shock, anaphylaxis or disseminated intravascular coagulation (DIC) have been reported recently in rare cases. In this experiment, the possibility of DIC was examined by intraperitoneal injection of topical thrombin (Parke-Davis) to rabbits with liver cirrhosis or acute liver damages induced by CCl4. No significant changes in the coagulation parameters were found in the groups of liver cirrhosis or the untreated control, but the injection of thrombin induced decreases of platelet count and fibrinogen and prolongation of prothrombin time and partial thromboplastin time in the groups of acute liver damages, 24 or 48 hr after CCl4 injection. When the "junk" prepared from the topical thrombin was injected to the 48 hr-damage group, no change was noted in these parameters. It was concluded that DIC could be induced by the intraperitoneal injection of topical thrombin only in cases of acute liver damages, where the increased permeability of peritoneum was postulated. However, such an immediate or marked change in coagulation was not found in our experiment as encountered in the clinical cases, which suggested the involvement of the anaphylactic reaction to the topical application of thrombin in the development of DIC in these clinical cases.

Anaphylaxis↗