Biomedical subjects

S Muramatsu

Publications and source records attributed to S Muramatsu.

At least 37 records · Page 2Linked to original sources

PubMed1999

Effect of truncal vagotomy on gallbladder bile kinetics in conscious dogs.

Previous studies on the effects of vagotomy on gallbladder (GB) motility have yielded conflicting results. The aim of this study was to evaluate the effects of vagotomy on GB motility and bile kinetics using a new method. Twelve dogs were divided into two groups of six (control and pyloroplasty) and, 4 weeks later, underwent truncal vagotomy. A catheter secured in the GB fundus was used to monitor GB volume. After injecting polyethylene glycol (PEG) into the GB, combined measurements of GB volume and PEG concentration enabled GB emptying and bile kinetics to be estimated. Seven and five of the 12 vagotomized dogs were classified as having large and normal fasting GB volumes, respectively. Postprandial GB emptying was impaired when the fasting GB volume was enlarged. In the fasting state, bile kinetics of vagotomized dogs were significantly smaller than the control values. The emptying ability of the GB of vagotomized dogs with large fasting GB volumes was reduced considerably both in the postprandial and the fasting states. Such retention of bile in the GB after vagotomy may facilitate cholesterol crystal nucleation and stone growth.

Animals↗

PubMed1999

A new type of Ser substitution for gamma Arg-275 in fibrinogen Kamogawa I characterized by impaired fibrin assembly.

A new type of substitution, Arg to Ser at gamma275, has been found in a heterozygous dysfibrinogen derived from a 23-year-old woman with no major bleeding or thrombosis. By sequence analyses of the affected gamma-chain and its gene. we found a single amino acid substitution of gamma Arg-275 to Ser in an aberrant gamma (274-302) residue peptide isolated from lysyl endopeptidase-digests of the patient's fibrinogen. In agreement with this amino acid substitution, we identified a single nucleotide exchange of A for C at position 5728 in the gamma-chain gene creating a codon (AGC) encoding Ser instead of the codon (CGC) encoding Arg at position gamma 275. Like two other known types of mutants with a His or Cys substitution at this position, the functional abnormality was characterized by delayed fibrin polymerization, most likely due to impaired abutting of two D domains of adjacent fibrin monomers in the same strand of fibrin protofibrils. The structural derangement that affects the D:D association may not be so severe as compared with those of Cys and His mutants, possessing an additional disulfide-linked Cys molecule and an imidazole ring at the mutation site, respectively.

Adult↗

PubMed1998

Regional pharmacokinetics of doxorubicin following hepatic arterial and portal venous administration: evaluation with hepatic venous isolation and charcoal hemoperfusion.

We evaluated the regional pharmacokinetics of doxorubicin after hepatic arterial infusion (HAI) and portal venous infusion (PVI) using a novel system for hepatic venous isolation and charcoal hemoperfusion (HVI-CHP). The HVI-CHP system was used to determine directly the doxorubicin plasma concentration in the hepatic vein and the hepatic venous flow rate, and simultaneously, to eliminate hepatic re-entry of the drug. Beagles received doxorubicin (1 mg/kg) through either the hepatic artery (HAI group, n = 6) or the portal vein (PVI group, n = 6). In both groups, hepatic venous blood was completely isolated and directed to the CHP filter. The filtered blood was returned through the left jugular vein. During HVI-CHP, the hepatic venous flow rate was monitored and plasma doxorubicin concentrations were serially measured in prefilter (= hepatic venous), postfilter, and systemic blood. The hepatic tissue uptake of doxorubicin was determined based on the blood flow rate and doxorubicin level in the hepatic vein. The hepatic extraction ratio of doxorubicin was defined as the percentage hepatic tissue uptake to the amount of drug administered. During drug infusion, similarly in either group, HVI-CHP produced a 66-87% reduction of the postfilter doxorubicin level as compared with the prefilter level. The prefilter drug level was significantly lower in HAI group than in PVI group (P < 0.01). Thus, the area under the time concentration curve for the prefilter drug level in the HAI group (6.90+/-0.96 microg min/ml) was significantly lower than that in the PVI group (18.10+/-2.90 microg min/ml, P < 0.01). Conversely, the hepatic extraction ratio in the HAI group (84.6+/-2.9%) was significantly higher than that in the PVI group (58.1+/-3.4%, P < 0.01). We conclude that in the beagle, doxorubicin is more effectively extracted by the liver when administered via the hepatic artery than when administered via the portal vein. These results indicate that HAI of doxorubicin is superior to PVI in terms of reduction of systemic drug exposure and systemic toxicity.

Animals↗

PubMed1998

Maternal anticipation in Machado-Joseph disease (MJD): some maternal factors independent of the number of CAG repeat units may play a role in genetic anticipation in a Japanese MJD family.

We studied the relationship between the number of CAG repeat units in the MJD1 gene and clinical features of Machado-Joseph disease (MJD) in eight patients from two generations of a Japanese MJD family. Because of lack of characteristic clinical signs of MJD such as dystonia, bulging eyes or facial myokymia, clinical diagnosis of MJD in this family was difficult to make prior to molecular testing for the CAG repeat expansion in the MJD1 gene. All the patients exhibited maternal transmission of MJD, and the intergenerational change in the number of CAG repeat units in the MJD1 gene was very small (+0.5+/-0.3, mean+/-S.E.M., n=4) in spite of marked genetic anticipation (-17.0 years/generation). In the present family, the degree of anticipation per repeat unit in maternal transmissions was much larger than that in maternal transmissions in the other six MJD families. This indicates that some maternal factors other than the increase of the number of CAG repeat units, which is known to be the basis of anticipation, may play a role in genetic anticipation in this MJD family.

Adult↗

PubMed1998

Resection of pheochromocytoma under inferior vena caval isolation and extracorporeal charcoal hemoperfusion.

Resection of pheochromocytoma is associated with potential risks of hypertensive crises and serious arrhythmias due to massive release of catecholamines from the tumor. We report our surgical experience with complete inferior vena caval isolation and extracorporeal charcoal hemoperfusion (IVCI-CHP), which were performed to prevent systemic exposure to catecholamines during surgical manipulation. The IVCI-CHP significantly reduced the postfilter and systemic catecholamine levels compared with the prefilter levels (P<.01), indicating substantial catecholamine extraction (>90%) by the CHP filter. Reflecting the reduction of systemic exposure to catecholamines during IVCI-CHP, the patient's blood pressures were markedly stable. Our findings suggest that IVCI-CHP may be useful to minimize the risk of hypertensive crises during surgical manipulation of pheochromocytoma, by preventing systemic exposure to high levels of circulatory catecholamines.

Adrenal Gland Neoplasms↗

PubMed1998

Percutaneous isolated liver chemoperfusion for treatment of unresectable malignant liver tumors: technique, pharmacokinetics, clinical results.

We have developed a single-catheter technique for percutaneous isolated liver chemoperfusion (PILP) with hepatic venous isolation and charcoal hemoperfusion (HVI-CHP) for the treatment of malignant liver tumors. We report here the surgical technique, pharmacokinetics, and effectiveness of PILP in multiple advanced liver tumors. Twenty-eight patients with hepatocellular carcinoma (HCC) and 18 with metastatic liver tumors underwent a total of 61 PILPs with HVI-CHP. HVI-CHP was accomplished mainly by the single-catheter technique using a novel four-lumen, two-balloon catheter; it was used to isolate and capture total hepatic venous outflow and, at the same time, to direct the filtered blood to the right atrium. Under HVI-CHP, either doxorubicin 960-150 mg/m2) or cisplatin (150-200 mg/m2) was infused via the hepatic artery. The PILP was completed successfully in all 61 trials. Two of forty-six patients died early; one of necrotizing pancreatitis and the other of hepatic arterial thrombosis. Both deaths were related directly to the hepatic arterial catheter. Excluding these two deaths, the treatments were well tolerated. The major side effects were mild to moderate chemical hepatitis and reversible myelosuppression. Of the 27 evaluable HCC patients, 17 (63%) had an objective tumor response (5 complete and 12 partial responses). In 15 patients with colorectal hepatic metastases (CHM), 7 had a sharp decrease in serum carcinoembryonic antigen (CEA) levels (to < 50% of their pretreatment levels) after treatment. However, a single PILP had limited efficacy in terms of the durability of remission (< or = 6 months in most CHM patients, as assessed by CEA levels). These results indicate that PILP with HVI-CHP has high efficacy in most patients with multiple advanced liver tumors. In addition, the results suggest a role of multiple treatment courses of PILP in the induction of long-term remission, especially for patients responsive to the first treatment.

Antineoplastic Agents↗

PubMed1998

Induction of long-term remission in advanced hepatocellular carcinoma with percutaneous isolated liver chemoperfusion.

OBJECTIVE: The aim of this study was to report the long-term results of percutaneous isolated liver chemoperfusion with hepatic venous isolation and charcoal hemoperfusion (HVI-CHP) in patients with multiple advanced hepatocellular carcinoma (HCC). SUMMARY BACKGROUND DATA: The results of conventional chemotherapy including regional and systemic chemotherapy in patients with HCC remain dismal, and long-term survivors after treatment are rare among patients with multiple advanced HCC. In an effort to improve this situation, we previously developed a novel system of percutaneous isolated liver chemoperfusion with HVI-CHP. METHODS: Doxorubicin (60 to 150 mg/m2) was administered via the hepatic artery, under conditions of extracorporeal drug elimination by HVI-CHP in 28 consecutive patients with advanced HCC (39 total treatments). Hepatic venous isolation and charcoal hemoperfusion was accomplished mainly by the single catheter technique using a newly developed 4-lumen-balloon catheter, which was used to isolate and capture total hepatic venous outflow and, at the same time, to direct the filtered blood to the right atrium. RESULTS: Complete remission was achieved in five patients, of which four received repeated treatments (two or three times). Although 1 of 5 patients with complete remission died of pulmonary metastases at 8 months, the other 4 remain healthy and free of disease at 20, 24, 27, and 42 months after the first treatment. Partial responses were observed in 12 patients. Duration of response in responders (complete and partial) with repeated treatments was significantly longer than that with a single treatment (p = 0.01). The overall survival rate by the Kaplan-Meier method was 39.7% at 5 years. The treatments were well-tolerated, and the primary side effects were mild to moderate chemical hepatitis and reversible myelosuppression. CONCLUSIONS: The results suggest that percutaneous isolated liver chemoperfusion with HVI-CHP is an effective palliative treatment in the majority of patients and yields long-term complete remission in some patients with multiple advanced HCC.

Adult↗

PubMed1998

Transcription-positive cofactor 4 enhances rescue of adeno-associated virus genome from an infectious clone.

While Rep proteins are required for adeno-associated virus (AAV) replication, little is known about cellular proteins that interact with Rep. We demonstrate here that transcription-positive cofactor 4 (PC4, p15) fused to Gal4-activating domain interacted with both AAV-2 and AAV-3 Rep proteins fused to Gal4 DNA-binding domain, leading to reporter activation in the yeast two-hybrid system. In addition to its coactivating function, PC4 recently has been shown to be involved in replication of simian virus 40. To study a functional role for the PC4-Rep protein interaction, 293-31 cells were cotransfected with a PC4 expression plasmid and an infectious clone of AAV-3, followed by super-infection with helper adenovirus. A significantly increased number of AAV-3 genomes were rescued in PC4 transfected cells. Our results support a possible involvement of PC4 in AAV replication and may be used in efficient production of AAV vectors for gene therapy.

Adenoviridae↗

PubMed1998

Protein kinase C gene expression in dispersed guinea-pig gastric parietal cells.

BACKGROUND AIMS: It has been implicated that protein kinase C (PKC) is involved in gastric acid secretion. The purpose of this study is to examine whether mRNA expression of PKC isoforms is observed in guinea-pig gastric parietal cells, and whether such PKC expression is regulated by agonists that stimulate gastric acid secretion. METHODS: Expression of PKC mRNA was assessed using isolated guinea-pig gastric parietal cells treated with or without three kinds of agonists by Northern blot analysis. RESULTS: (1) alpha, gamma and zetaPKC mRNAs were expressed in guinea-pig gastric parietal cells; (2) both carbachol and gastrin increased the level of alpha and gammaPKC mRNAs, but synthesis of zetaPKC mRNA was not affected by these agonists, and (3) histamine did not affect the expression level of alpha, gamma and zetaPKC mRNAs. CONCLUSION: alpha and gammaPKC isoforms may be involved in the regulation of gastric acid secretion.

Animals↗

PubMed1998

[The long-term results of percutaneous isolated hepatic perfusion for patients with advanced hepatocellular carcinoma].

We studied the long-term outcome of percutaneous isolated hepatic perfusion (PIHP) for patients with hepatocellular carcinoma. This study included 31 patients with Stage IVA and 5 with IVB disease treated by PIHP until December, 1997. The mean age and tumor diameter were 55 and 7.7 cm, respectively. Twenty-two had portal vein invasion, 13 had hepatic vein invasion, and all patients had multiple intrahepatic metastases of more than 5 tumor foci. The PIHP with adriamycin or cisplatin was undertaken in a total of 50 treatments in these 36 patients. CR was observed in 6 and PR in 13 with an overall response rate of 59%, excluding 4 patients who were not evaluable. Five of 6 patients with CR remain free of disease at 7 to 54 months after the first treatment. The overall survival rate was 67% at 1 year and 32% at 5 years. The survival rates of Stage IVA patients (1-year = 71%, 5-year = 36%) were higher than Stage IVB patients (1-year = 20%, 5-year = 0%). The 5-year survival rates of patients with vascular invasion (Vp1-3 = 23%, Vv1-3 = 8%) were lower than those without it (Vp0 = 47%, Vv0 = 51%). These results indicated that PIHP achieved a 5-year survival rate of approximately 40% in patients with multiple advanced hepatocellular carcinoma in the absence of distant organ metastases and marked vascular invasion, and yielded complete long-term remission in some of these patients.

Antibiotics, Antineoplastic↗

PubMed1998

[Pharmacokinetic comparison between cisplatin and nedaplatin in hepatic arterial chemotherapy using complete hepatic venous isolation and charcoal hemoperfusion].

We undertook a pharmacokinetic comparison between cisplatin and nedaplatin in hepatic arterial chemotherapy using complete hepatic venous isolation and charcoal hemoperfusion (HVI.CHP). Dogs received a 20-min hepatic arterial infusion of either 4 mg/kg cisplatin (Group I, n = 5) or 4 mg/kg nedaplatin (Group II, n = 5) under HVI.CHP. The CHP filter adsorption ratios did not differ significantly between the two groups. Drug clearance fractions by HVI.CHP in group II (free pt 45.9%, total pt 55.1%) were significantly higher than those in group I (free pt 23.4%, total pt 27.5%) (p < 0.05). In contrast, hepatic extraction ratios in group I tended to be higher than those in group II. These results indicated that extrahepatic distribution of cisplatin became lower than that of nedaplatin, when given via the hepatic artery, and that the pharmacokinetic advantage of HVI.CHP would be greater when a drug like nedaplatin with a relatively low hepatic extraction ratio is used. Thus, we concluded that nedaplatin is a more suitable drug than cisplatin.

Animals↗

PubMed1997

Effect of nitric oxide synthase inhibition on plasma motilin release in fasted dogs.

Inhibition of nitric oxide (NO) synthase on plasma motilin concentrations is not known. The aim of this study was to examine the effect of NO synthesis inhibitor on gastrointestinal motility and motilin release in conscious dogs. Dogs fitted with force transducers were given N omega-nitro-L-arginine (L-NNA) after the termination of phase III contractions. Blood samples were taken for measurement of motilin concentrations. L-NNA induced phase III-like contractions in the stomach in the duodenum in association with a significant increase in motilin level. Atropine or hexamethonium significantly inhibited L-NNA-induced phase III-like contractions and the increase in motilin level. Atropine or hexamethonium significantly inhibited L-NNA-induced phase III-like contractions and the increase in motilin level. Ondansetron markedly inhibited gastric, but not duodenal, phase III-like contractions without affecting the increase in motilin level caused by L-NNA. Vagotomy affected neither the occurence of phase III-like contractions nor the increase in motilin level produced by L-NNA. We conclude that inhibition of NO synthesis stimulates motilin release via cholinergic pathways independent of the vagus, and induces phase III-like contractions in the stomach and duodenum. Phase III-like contractions induced by L-NNA are mediated through the activation of 5-HT, receptors.

Animals↗

PubMed1997

Wild-type, but not mutant-type, p53 enhances nuclear accumulation of the NS3 protein of hepatitis C virus.

By using vaccinia virus-T7 hybrid expression system, subcellular localization of the NS3 protein of hepatitis C virus was studied. Full-size NS3 (NS3F) and a carboxy-terminally truncated form (NS3 deltaC) were localized in the cytoplasm and the nucleus when expressed alone. However, NS3F and NS3 deltaC, but not amino- and carboxy-terminally truncated form (NS3 deltaN deltaC), were each co-localized with wild-type p53 almost exclusively in the nucleus upon co-expression. The wild-type p53-induced nuclear accumulation of NS3F was inhibited only partially by NS4A. When co-expressed with mutant-type p53, NS3F and NS3 deltaC were each co-localized with it exclusively in the cytoplasm. Taken together, the present results suggest that wild-type p53 enhances nuclear accumulation of NS3F and NS3 deltaC through the involvement of their amino-terminal sequences even in the presence of NS4A, and that mutant-type p53 inhibits their nuclear, and enhances their cytoplasmic, accumulation.

Base Sequence↗

PubMed1997

Relationship between gallbladder bile concentration and motility in conscious dogs: role of cholecystokinin.

The relationship between gallbladder (GB) bile concentration and motility was studied in conscious dogs. The 12-h GB bile concentrations between meals could be divided into three periods: diluting, minimum, and concentrating periods. During the diluting period, inhibition of GB contractions by a CCKA receptor antagonist, atropine or hexamethonium, resulted in concentration of GB bile, whereas during the concentrating period, CCK-8 shifted the concentration process back to dilution. The GB appears to absorb water continuously from GB bile, which is not regulated by cholinergic or CCKA receptors. The postprandial progressive dilution of GB bile is brought about by GB pumping controlled by cholecystokinin (CCK).

Animals↗

PubMed1997

Long-term observations of uterine contractions in nonpregnant dogs.

Uterine contractile activity in nonpregnant conscious dogs was investigated based on 2- to 6-mo-long continuous recording by means of a chronically implanted force transducer. We found that nonpregnant uterine contractile activity could be classified into six major patterns: sporadic contractions, weak and strong tonic contractions, weak and strong phasic contractions, and phasic contraction bursts. The contractile patterns during proestrus and estrus were the most active, with strong phasic and tonic contractions and phasic contraction bursts. The phasic and tonic contractions were inhibited dose-dependently by a beta 2 adrenergic agonist, ritodrine, and reproduced by an alpha 2 adrenergic agonist, clonidine. In contrast, the cholinergic inhibitors atropine and hexamethonium did not affect the spontaneous occurrence of these contractions, although bethanechol evoked uterine contractions. Oxytocin and prostaglandin F2 alpha-induced contractions were phasic during estrus, whereas they showed tonic increases with phasic contractions during proestrus, diestrus, and anestrus, and these contractions did not resemble the spontaneous contractions. In conclusion, the nonpregnant uterus contracts continuously in harmony with the estrous cycle phases, and its contractile activity is enhanced by alpha adrenergic receptors and inhibited by beta 2 adrenergic receptors.

Adrenergic Agonists↗

PubMed1997

Nuclear localization of the NS3 protein of hepatitis C virus and factors affecting the localization.

Subcellular localization of the NS2 and NS3 proteins of hepatitis C virus was analyzed. In stable Ltk transfectants inducibly expressing an NS2-NS3 polyprotein (amino acids [aa] 810 to 1463), processed full-size NS2 (aa 810 to 1026) was detected exclusively in a cytoplasmic membrane fraction. On the other hand, the other processed product, carboxy-truncated NS3 (NS3 deltaC1463; aa 1027 to 1463), was present in both cytoplasmic and nuclear fractions. To further analyze subcellular localization of NS3, NS3 deltaC1459 (aa 1027 to 1459), full-size NS3 (NS3F; aa 1027 to 1657), and both amino- and carboxy-truncated NS3 (NS3 deltaNdeltaC; aa 1201 to 1459) were expressed in HeLa cells by using a vaccinia virus-T7 hybrid expression system. NS3 deltaC1459 and NS3F accumulated in the nucleus as well as in the cytoplasm, exhibiting a dot-like staining pattern. On the other hand, NS3 deltaNdeltaC was localized predominantly in the cytoplasm, suggesting the presence of a nuclear localization signal(s) in the amino-terminal sequence of NS3. NS4A, a viral cofactor for the NS3 protease, inhibited nuclear transport of NS3 deltaC1459 and NS3F, with the latter inhibited to a lesser extent than was the former. Interestingly, wild-type p53 tumor suppressor augmented nuclear localization of NS3 deltaC1459 and NS3F, whereas mutant-type p53 inhibited nuclear localization and augmented cytoplasmic localization of NS3 deltaC1459. However, subcellular localization of NS3 deltaNdeltaC was not affected by either type of p53. Wild-type p53-mediated nuclear accumulation of NS3 deltaC1459 and NS3F was inhibited partially, but not completely, by coexpressed NS4A, with NS3F again affected less prominently than was NS3 deltaC1459.

Animals↗

PubMed1997

Metabolism of pravastatin sodium by 3 alpha-hydroxysteroid dehydrogenase.

When incubated with isolated rat hepatocytes, pravastatin sodium (PS) yielded a small amount of a metabolite in addition to two major metabolites that have already been reported. The previously uncharacterized metabolite was found to be formed by at first being enzymatically dehydrogenated to 6'-keto intermediate (R-104), followed by decomposition to give the aromatized metabolite (R-195), through spontaneous deesterification with accompanying aromatization. The PS-6'beta-hydroxydehydrogenase activity was localized in cytosolic fraction and required NADP, preferentially over NAD, as a cofactor. The formation of R-195 by rat liver cytosol was strongly inhibited by indomethacin, 3 alpha-hydroxysteroids (but not 3 beta-isomers) and 3-ketosteroids. The results and high substrate specificity of purified PS-6'beta-hydroxydehydrogenase toward 3 alpha-hydroxysteroids suggested that the enzyme is identical to 3 alpha-hydroxysteroid dehydrogenase.

3-Hydroxysteroid Dehydrogenases↗

PubMed1997

[Apolipoprotein E epsilon 4 allel frequencies, plasma alpha 2-macroglobulin and plasminogen activator inhibitor 1 levels in residents of a rural area in Gunma prefecture].

The apolipoprotein E4 (apoE4) epsilon 4 allele is a major riks factor for Alzheimer's disease. However, epsilon 4 is neither a necessary nor a sufficient condition for the development of this disease, and many cognitively healthy elderly people carry the epsilon 4 allele. To look for age-dependent changes in epsilon 4 allele frequencies in the general population, we measured the frequencies in 141 normal healthy residents of a mountainous rural area in north-west Gunma prefecture. Levels of cholesterols in plasma were measured and their relation to apoE genotypes was studied. We also measured the levels of alpha 2-macroglobulin (alpha 2M) and plasminogen activator inhibitor 1 (PAI-1) in blood, and studied their relation to apoE genotypes. Because low-density lipoprotein receptor-related protein (LRP) binds apoE, alpha 2M, and PAI-1, it is of interest to see whether the alpha 2M and PAI-1 concentrations in blood differ between epsilon 4 carriers and non-carriers. ApoE allele frequencies were 0.05, 0.84, and 0.11 for epsilon 2, epsilon 3, and epsilon 4, respectively. In both men and women, the frequency of epsilon 4 was lowest among those in the seventh decade of life. The frequency of epsilon 4 among octagenarians was high (0.17). Serum levels of total cholesterol and low-density lipoprotein cholesterol did not differ significantly between epsilon 4 carriers and non-carriers. The alpha 2M level in serum was higher in women than in men and was higher in older subjects than in younger subjects. Plasma PAI-1 levels were significantly higher in men than in women (Student's t-test, p = 0.0197). Neither alpha 2M levels nor PAI-1 levels differed between epsilon 4 carriers and non-carriers, which suggests that the levels of these two proteins in blood do not reflect the status of LRP in individuals with various apoE genotypes. Studies that include data on life style and diet are necessary before we can conclude that rural life contributes to longevity in epsilon 4 carriers.

Adult↗