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Biomedical subjects

N Sakamoto

Publications and source records attributed to N Sakamoto.

At least 163 records · Page 9Linked to original sources
PubMed1996

Changes of phylloquinone and menaquinone-4 concentrations in rat liver after oral, intravenous and intraperitoneal administration.

To study the metabolism of K Vitamins (VK) in the liver, two types of natural VK, phylloquinone (K1) and menaquinone-4 (MK-4), were administered to male Wistar rats orally (P.O.), intravenously (I.V.) and intraperitoneally (I.P.). Blood and a small portion of the liver (and ascites by I.P.) were collected 8 times up to 72 h (P.O.) or 24 h (I.V. and I.P.). A modified assay procedure followed by high performance liquid chromatography (HPLC) was developed to detect VK from small amounts of liver tissue. After oral administration of both K1 and MK-4 (10 mumol/kg-P.O.), their concentrations in the liver increased from 1 h then reached a maximum at 6 h (10 nmol/g v.s. 0.35 nmol/g). After intravenous or intraperitoneal administration of K1 and MK-4 (0.5 mumol/kg-I.V. and I.P.), MK-4 concentrations in the liver reached a maximum faster than those of K1 (1.2 nmol/g -3 h vs. 1.3 nmol/g -0.5 h I.V. and 0.97 nmol/g -6 h vs. 0.47 nmol/g -1 h I.P.). MK-4 also increased in the liver from 6 h to 12 h (0.11 nmol/g -12 h) after oral administration of K1 (P.O.). These results indicate that K1 stays in plasma and liver longer than MK-4 and orally administered K1 might be transformed partially into MK-4 in the liver.

Animals↗
PubMed1996

Detection of Haemophilus influenzae in adenoids and nasopharyngeal secretions by polymerase chain reaction.

Haemophilus influenzae in the nasopharynx is thought to be related to the pathogenesis of otitis media with effusion (OME). However, the positive rate measured by the conventional culture method is not high enough for bacterial infection to be considered the chief pathogenic factor. Polymerase chain reaction (PRC) and the conventional culture method were applied to detect H. influenzae in the adenoids and nasopharyngeal secretions of 17 children with OME (2 to 7 years of age). The percentage of P6-positive adenoid samples was 82.4% while 70.6% were culture positive. In nasopharyngeal secretions, 88.2% were P6-positive and 64.7% were culture positive. All samples in which H. influenzae was cultured were positive with PCR. The positive rate was significantly greater with PCR than with the culture method, and it showed a significant concordance between adenoids and nasopharyngeal secretions (p = 0.0027). These findings suggest that the presence of H. influenzae in the nasopharynx is more common in children with OME than previously reported, and that H. influenzae in adenoids might play an important role in OME.

Adenoids↗
PubMed1995

Simultaneous determination of plasma phenytoin and its primary hydroxylated metabolites in carbon tetrachloride-intoxicated rats by high-performance liquid chromatography.

We have developed a simple and sensitive method for the simultaneous determination of phenytoin (PHT), 5-(p-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) and 5-(m-hydroxyphenyl)-5-phenylhydantoin (m-HPPH) in rat plasma by high-performance liquid chromatography. The three substances were separated on a reversed-phase column (5 microns TSK gel ODS-80TM, 250 mm x 4.6 mm I.D.) using acetonitrile-0.008 M NaH2PO4 (pH 6) (35:65, v/v) as a mobile phase at a flow-rate of 0.8 ml/min. Absorbance was monitored at 215 nm. The quantification limit was 50 ng/ml for each of PHT, m-HPPH and p-HPPH. The mean recoveries for DPH, m-HPPH and p-HPPH from plasma were 95.6 +/- 3.6, 94.5 +/- 4.2 and 98.6 +/- 2.9%, respectively.

Animals↗
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

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

Pressor response induced by the hippocampal administration of neostigmine is suppressed by M1 muscarinic antagonist.

We investigated the roles played by three muscarinic receptors (M1, M2, and M3) in the pressor response with bradycardia that followed the injection of neostigmine (5 x 10(-8) mol) into the hippocampus of anesthetized rats. These changes were blocked by the co-administration of methylatropine (5 x 10(-8) mol). The intrahippocampal injection of pirenzepine (M1 antagonist) (5 x 10(-9) - 5 x 10(-7) mol) suppressed the neostigmine-induced pressor response dose-dependently. However injection of gallamine (M2 antagonist) (5 x 10(-8) - 5 x 10(-7) mol) and of 4-DAMP (M1 and M3 antagonist) (5 x 10(-8) - 5 x 10(-7) mol) did not suppress this hypertensive response. These findings suggest that the neostigmine-induced pressor response with bradycardia is mediated through the M1 muscarinic receptor subtype.

Animals↗
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

Effects of an aldose reductase inhibitor, epalrestat, on diabetic neuropathy. Clinical benefit and indication for the drug assessed from the results of a placebo-controlled double-blind study.

The clinical efficacy of epalrestat (150 mg/day, 50 mg tid, po; A group), an aldose reductase inhibitor, was evaluated in 196 patients with diabetic neuropathy by a double-blind study using placebo (9 mg/day, 3 mg tid, po; P group) as a control for 12 weeks. The disappearance rates of upper limb spontaneous pain were 42.9% and 12.0% in the A and P groups, respectively, and those of lower limb spontaneous pain 48.6% and 22.6%, thus being significantly higher in the A group (p < 0.05, logrank-test). The motor nerve conduction velocity of the peroneal nerve significantly increased only in the A group (delta 1.6 +/- 0.6 m/sec, p < 0.01, paired t-test), and the extent of increase in that of the median nerve was significantly greater in the A group than in the P group (p < 0.05). Thresholds of vibratory sensation and autonomic nerve function were also significantly improved in the A group (p < 0.05). The data were reanalyzed by dividing patients into two groups according to their HbA1c values. The improvement ratings of subjective symptoms and of nerve function tests for cases with HbA1c > or = 7.5% were both significantly different between the A and P groups, with the improvement rate being higher in the A group, and also higher as compared to the analysis for cases with HbA1c < 7.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Effects of glucose and SNK-860, an aldose reductase inhibitor, on the polyol pathway and chemiluminescence response of human neutrophils in vitro.

An in vitro incubation study was conducted to investigate whether increased activity of the polyol pathway in human neutrophils under diabetic conditions resulted in a decrease of superoxide anion produced by NADPH oxidase on the membrane of neutrophils. Lucigenin-enhanced chemiluminescence (CL) to phorbol myristate acetate as respiratory burst and sorbitol levels in neutrophils after incubation with glucose and an aldose reductase (AR) inhibitor, SNK-860 (SNK) were measured. Sorbitol levels increased from 0.210 +/- 0.029 nmol 10(7) cells-1 in 5 mmol l-1 glucose to 0.446 +/- 0.036 nmol 10(7) cells-1 in 40 mmol l-1 glucose, while CL decreased from 0.542 +/- 0.034 cpm cell-1 in 5 mmol l-1 glucose to 0.430 +/- 0.018 cpm cell-1 in 40 mmol l-1 glucose. The addition of 10 mumol l-1 SNK normalized the increased sorbitol levels in neutrophils exposed to 40 mmol l-1 glucose and improved, but did not normalize, the decrease in CL induced by 40 mmol l-1 glucose (p < 0.001). Galactose (40 mmol l-1) also reduced CL, which was improved by the addition of SNK (p < 0.01). These results suggest that impaired respiratory burst induced by high-glucose concentrations is caused by competition for NADPH resulting from increased polyol pathway activity and/or glycation and that an AR inhibitor may be capable in part of preventing increased susceptibility to infection in diabetic patients.

Adult↗
PubMed1995

Changes of K vitamins in portal and femoral venous plasma of rats after oral administration of phylloquinone and menaquinone-4.

To clarify the mechanism of absorption and metabolism of K vitamins (VK), we administered phylloquinone (K1) and menaquinone-4 (MK-4) orally to male Wistar rats whose portal and femoral veins were cannulated. Blood was collected 9 times up to 120 min later, and 50 microliters plasma was used for VK analysis by high performance liquid chromatography (HPLC) using a modification of our previous method. There were no significant differences between portal and femoral venous VK concentrations throughout all the experiments. When K1 and MK-4 were administered simultaneously, K1 appeared in plasma at 15 min, and MK-4 at 10 min. The concentration of MK-4 was significantly higher than that of K1 up to 60 min. In contrast to the single administration, the MK-4 concentration was reduced after 60 min. After K1 single administration, the MK-4 was not detected in either portal or femoral venous plasma up to 120 min. These results suggested that (1) the main absorption route of both VK may be the extra-portal pathway, (2) MK-4 is absorbed faster than K1 (3) some interactions may exist between K1 and MK-4 and (4) the intestinal cells might not be the major site to transform K1 into MK-4.

Administration, Oral↗
PubMed1995

[Haloperidol].

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Antipsychotic Agents↗
PubMed1994

Effects of adrenoceptor antagonists on the hyperthermia and hyperglycemia induced by prostaglandin F2 alpha in rats.

We investigated the effects of intraperitoneal administration of adrenoceptor antagonists to the hyperthermia and hyperglycemia induced by prostaglandin F2 alpha (50 micrograms) injected into the third cerebral ventricle in anesthetized rats. Phentolamine inhibited the hyperthermia and hyperglycemia induced by prostaglandin F2 alpha. Prazosin inhibited the hyperthermia induced by prostaglandin F2 alpha, while enhancing the hyperglycemia. Yohimbine inhibited the prostaglandin F2 alpha-induced hyperglycemia without an effect on the hyperthermia. Propranolol had no effect on either prostaglandin F2 alpha-induced hyperglycemia or hyperthermia. These observations suggest that the hyperglycemia induced by prostaglandin F2 alpha is regulated by alpha 2-adrenoceptor systems while the hyperthermia is regulated by alpha 1-adrenoceptor systems in rats.

Adrenergic alpha-Antagonists↗
PubMed1994

Protein phosphatase inhibitors induce the release of serotonin from rat basophilic leukemia cells (RBL-2H3).

Effects of okadaic acid (OA) and calyculin-A (CL-A), selective inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A), on the release of serotonin from the rat basophilic leukemia cell line (RBL-2H3) were investigated. Both OA and CL-A induced the long-lasting release of serotonin in an extracellular Ca(2+)-independent manner. CL-A did not increase intracellular Ca2+ concentration in the fura-2-loaded cells. CL-A was 100-fold more potent than OA in inducing the release, suggesting that PP1 is a dominant protein phosphatase in regulating RBL-2H3 cells. The CL-A-induced release of serotonin was completely inhibited by the nonselective protein kinase inhibitors, staurosporine and K-252a. CL-A induced phosphorylation of several cellular proteins in RBL-2H3 cells, which could be inhibited by staurosporine. These findings suggest that the release of serotonin is subject to tonic, Ca(2+)-independent, inhibition by PP1 in RBL-2H3 cells.

Alkaloids↗
PubMed1994

Sequential change of the hypervariable region of the hepatitis C virus genome in acute infection.

Hepatitis C virus (HCV) infection is characterized by persistence of liver inflammation that often leads to end-stage liver disease, although the mechanisms are not fully understood. A hypervariable region (HVR) has been reported in the E2/NS1 region of the HCV genome, in which striking diversity is found among different HCV isolates. To investigate the association of the HVR alterations with the clinical courses of HCV infection, a longitudinal analysis of the HVR in patients with acute HCV infection was carried out. Plasma samples were obtained at several times in three patients with acute hepatitis C. Plasma RNA was extracted and reverse transcribed, and DNA fragments that included the HVR were amplified by PCR. The sequences of the HVR were directly determined from the PCR products by the dideoxy chain termination method, from which amino acid sequences were deduced. In all cases, plasma HCV-RNA disappeared with the improvement of the initial alanine aminotransferase (ALT) elevation, but HCV-RNA reappeared about 1 year later with or without deterioration of the hepatitis. In a case of sporadic acute hepatitis, the HCV in the recurrent phase had seven amino acid substitutions in the HVR compared with that in the acute phase, although no amino acid changes were noted during the initial acute phase. In a case of posttransfusion hepatitis, a marked difference was observed between the acute and the recurrent phases, with an amino acid homology of 30% (8/27). The mutation rate of the HVR had a tendency to accelerate as the HCV infection progressed to the chronic stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗