Biomedical subjects

K Chiba

Publications and source records attributed to K Chiba.

At least 235 records · Page 13Linked to original sources

PubMed1994

Comparison of symptomatic and asymptomatic reinfarctions after small subcortical stroke.

We compared possible factors leading to symptomatic and asymptomatic reinfarcts in 207 patients an average of 2.1 years after their index atherothrombotic stroke presenting with small subcortical infarcts. Symptomatic reinfarcts were mostly small infarcts in the perforating artery regions associated with angiographic evidence of atherosclerosis of parent arteries (large-artery disease), a high hematocrit, elevated fibrinogen and Lp(a) levels. They occurred with insufficient inhibition of platelet aggregability in patients receiving antiplatelet medication. In contrast, many asymptomatic reinfarcts were small perforator infarcts not associated with large-artery disease or cortical infarcts, and occurred in the absence of hematologic risk markers, and in spite of sufficient inhibition of platelet aggregability.

Aged↗

PubMed1994

Promotion of neuronal differentiation of PC12h cells by natural lignans and iridoids.

We studied the effect of (+)- and (-)-syringaresinol, (+)-syringaresinol glucosides, syringin, aucubin and catalpol on neurite outgrowth of a cultured cell line of paraneuron, PC12h cells. Of these compounds, (+)-syringaresinol diglucoside and partly glucosidase-hydrolyzed aucubin were found to be the most potent in promotion of the neurite outgrowth and stimulated responses to a high concentration of KCl and to carbachol in the cells, as observed by increase of the concentration of cytosolic free calcium. It is suggested that some of these herb-derived compounds can induce neuronal differentiation in PC12h cells.

Animals↗

PubMed1994

Inhibition of the nerve growth factor-induced neurite outgrowth by specific tyrosine kinase and phospholipase inhibitors.

The effects of nerve growth factor (NGF) on PC12h cells have been studied with reference to the relationship between neurite outgrowth and the activities of the enzymes involved in signal transduction in the early stage of NGF action. Pretreatment of cells with selective inhibitors of tyrosine kinase (ST638 and genistein) and phospholipases C (neomycin B) and A2 (p-Bromophenacyl bromide; BPB and indomethacin) depress neurite outgrowth following 60 min treatment with NGF (0.1 microgram/ml). The inhibitor of intracellular calcium mobilization, TMB-8, also significantly depresses the NGF-induced neurite outgrowth. Arachidonic acid release, induced by NGF, from the cell lipids is reduced following previous inhibition of above mentioned enzymes. Based on these results, it is suggested that NGF requires tyrosine kinase in its early stage of action (within 60 min) in PC12h cells, phospholipases C and A2 to release Ca2+ from intracellular stores and arachidonate from cellular phospholipids, in order to induce neurite outgrowth.

Animals↗

PubMed1994

Effects of organic acids on heterotrophic nitrification by Alcaligenes faecalis OKK17.

Factors affecting heterotrophic nitrification by Alcaligenes faecalis OKK17, which was isolated from sewage sludge, were examined. Specific nitrifying activity increased as the pH increased up to 8.5. Most of the nitrogenous compounds (88%) in the culture supernatant were converted to hydroxylamine or nitrite at pH 9 but 87% of them remained as ammonium at pH 7. These results imply that the substrate for heterotrophic nitrification is ammonium and that the organism oxidizes ammonium to lower its toxic effect. Although the addition of acetate to a defined medium increased growth of the bacterium up to C/N = ca. 6, the accumulation of nitrification products almost paralleled the growth and the specific nitrifying activity decreased. Pyruvate and oxaloacetate increased the specific nitrifying activity six- to eightfold compared with the other organic acids examined, but the key enzyme activities in the glyoxylate cycle were not increased. Acetate, glyoxylate, and malonate did not increase the specific nitrifying activity, but they increased the enzyme activities. These results imply that the involvement of acetate metabolism in the heterotrophic nitrification is unlikely.

Acetates↗

PubMed1994

[Radiation therapy of carcinoma of the esophagus in the aged--its results and problems].

Clinical records of 128 non-selected patients with esophageal cancer treated by radiation were reviewed to investigate reasons why treatment had to be discontinued, relationship between age and survival, and factors influencing prognosis. Radiation therapy was completed in 77 patients but was discontinued in 27 patients. Preoperative radiation was attempted in 24 patients. An overall median survival of 128 patients was 6.4 months, with 8.5 and 3.3 percent surviving 3 and 5 years. Median survivals of incomplete RT, completed Rt and RT + Surgery were 1.3, 7.7 and 11.3 months. By Kaplan-Meier analysis significant difference was observed in survival rate between incomplete RT and the other two groups, but not between RT and RT + surgery. T1 tumor cases with incomplete RT were characterized by a higher C-Score (higher incidence of comorbidity and complications), lower albumin concentration and poor performance status. Median survivals of 60 years, 70 and 80 were 12, 5.4 and 6.2 months, respectively. Performance status and C-score were significantly different between the 60 yr and 80 yr groups. Survival rates were also apparently affected by the size of the primary tumor and metastasis. Thus important factors influencing prognosis were performance status, albumin concentration, and comorbidity and complications, in addition to stage of tumor itself. Although performance status and albumin concentration were considered directly related to tumor stage, old age may have an adverse effect on these factors through increase of comorbidity and complication. The data may be useful for decision making for treatment of esophageal cancer of the aged.

Age Factors↗

PubMed1994

Fungal metabolites. Part 11. A potent immunosuppressive activity found in Isaria sinclairii metabolite.

A potent immunosuppressive activity was found in the culture broth of the fungus Isaria sinclairii (ATCC 24400). The metabolite, ISP-I ((2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2- hydroxymethyl-14-oxoeicos-6-enoic acid, myriocin = thermozymocidin) suppressed the proliferation of lymphocytes in mouse allogeneic mixed lymphocyte reaction, but had no effect on the growth of human tumor cell lines. It also suppressed the appearance of plaque-forming cells in response to sheep red blood cells and the generation of allo-reactive cytotoxic T lymphocytes in mice after intraperitoneal or oral administration. The metabolite was 10- to 100-fold more potent than cyclosporin A as an immunosuppressive agent of the immune response in vitro and in vivo, and appears to be a candidate for clinical application as a powerful immunosuppressant.

Animals↗

PubMed1994

Fungal metabolites. Part 12. Potent immunosuppressant, 14-deoxomyriocin, (2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2-hydroxymethyleicos-6-enoic acid and structure-activity relationships of myriocin derivatives.

In order to investigate the structure-activity relationships, fourteen derivatives of myriocin ((2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2-hydroxymethyl-14-oxoeicos- 6-enoic acid) were prepared and examined for immunosuppressive activity on mouse allogeneic mixed lymphocyte reaction in vitro. Among them, 14-deoxomyriocin ((2S,3R,4R)-(E)-2-amino-3,4-dihydroxy-2- hydroxymethyleicos-6-enoic acid) was the most potent. It also suppressed the generation of allo-reactive cytotoxic T lymphocytes in mice upon intraperitoneal administration, with a potency 10-fold greater than that of myriocin.

Animals↗

PubMed1994

Fungal metabolites. Part 14. Novel potent immunosuppressants, mycestericins, produced by Mycelia sterilia.

Mycestericins A, B, C, D and E were isolated from the culture broth of Mycelia sterilia ATCC 20349 along with thermozymocidin (= myriocin). Their structures were elucidated on the basis of spectroscopic studies and chemical evidence. The acetate of mycestericin C was identical with the acetate of 6,7-dihydromyriocin. Mycestericins suppressed the proliferation of lymphocytes in the mouse allogeneic mixed lymphocyte reaction, with a potency similar to that of myriocin.

Animals↗

PubMed1994

Long-lasting ex vivo inhibition by perindopril of rat vascular response to angiotensin I.

The ex vivo effects of perindopril and enalapril, inhibitors of angiotensin-converting enzyme (ACE), were studied on rat aortae and perfused hearts to clarify the inhibition of vascular response to angiotensin I. The duration of the effects of these inhibitors was also studied. One hour after oral administration of perindopril (0.1-30 mg/kg) or enalapril (0.3-100 mg/kg), the aortae and hearts were isolated for the measurement of isometric force and coronary flow, respectively. In aortae, perindopril and enalapril dose-dependently inhibited the maximal contractions to angiotensin I (1-1000 nM). In isolated perfused hearts, the compounds inhibited the decrease in coronary flow induced by angiotensin I (100 ng). In other experiments, the inhibitory effects of perindopril lasted for 24 h in both aortae (3 mg/kg, p.o.) and hearts (10 mg/kg, p.o.). In contrast, the effects of enalapril disappeared within 6 h in aortae (3 mg/kg, p.o.) and 12 h in hearts (100 mg/kg, p.o.). These results demonstrate that oral administration of ACE inhibitors reduce the ex vivo vascular response to angiotensin I and suggest that perindopril is a longer-lasting inhibitor than enalapril on vascular contraction to locally generated angiotensin II.

Administration, Oral↗

PubMed1994

[Clinical study on torsion of appendix in intrascrotal organ].

We reviewed 12 cases of torsion of appendix in the intrascrotal organ treated surgically and discussed its clinical features. An accurate diagnosis could be made in 5 of the 12 patients before operation because they had a palpable localized tender nodule at the affected area, but not in the other 7 patients because their whole scrotal contents had become swollen with time. The histological study on 6 patients with testicular swelling revealed their spermatogenesis intact. Therefore, we believe that torsion of the appendix in the intrascrotal organ has little influence on future fertility, and thus, correct preoperative diagnosis may diminish the necessity for surgical treatment.

Adult↗

PubMed1994

Metabolic disposition of imipramine in oriental subjects: relation to metoprolol alpha-hydroxylation and S-mephenytoin 4'-hydroxylation phenotypes.

We studied the metabolic disposition of imipramine by measuring imipramine and its metabolites in plasma and urine simultaneously after a single oral dose of 25 mg of imipramine hydrochloride administered to 16 healthy (three Japanese and 13 Korean) volunteers. Four of the subjects were poor metabolizers (PMs) of metoprolol but extensive metabolizers (EMs) of S-mephenytoin (PMML/EMMP), five subjects were EMs of metoprolol but PMs of S-mephenytoin (EMML/PMMP) and seven subjects were EMs of both metoprolol and S-mephenytoin (EMML/EMMP). The mean (+/- S.D.) oral clearances of imipramine were smaller in the PMML/EMMP group and the EMML/PMMP group than in the EMML/EMMP group, although a statistical difference (P < .05) was found only in the EMML/PMMP vs. the EMML/EMMP group. The mean area under the plasma concentration-time curve (AUC) of desipramine was 9 times greater (P < .01) in PMML/EMMP group, whereas the mean value was 0.6 times smaller (P < .05) in the EMML/PMMP group than in the EMML/EMMP group. The log10 metoprolol/alpha-hydroxymetoprolol ratio correlated positively with the AUC of desipramine (P < .01) and with the AUC ratio of desipramine/imipramine (P < .05) but negatively with the AUC ratio of 2-hydroxyimipramine/imipramine (P < .05). Log10 percent 4'-hydroxymephenytoin excreted in 8-hr urine correlated positively with the AUC of desipramine (P < .01) and with the AUC ratio of desipramine/imipramine (P < .01). The urinary excretions of imipramine and its metabolites also reflected the data derived from plasma samples in the three different phenotype-paired panels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Egg-jelly signal molecules for triggering the acrosome reaction in starfish spermatozoa.

It was in the early 1950s that J.C. Dan discovered the acrosome reaction in sea urchins, starfishes and several other marine invertebrates at Misaki Marine Biological Station on the Pacific coast of Japan. We now know that in many animals including mammals the acrosome reaction is an essential, and probably the most central, change in spermatozoa for fertilization. Starfish spermatozoa undergo the acrosome reaction upon encountering the jelly coat consisting of glycoproteins, steroid saponins, oligopeptides and inorganic components. To induce the acrosome reaction, three egg jelly components act in concert on the spermatozoa: a highly sulfated glycoprotein named acrosome reaction-inducing substance (ARIS), a group of sulfated steroidal saponins named Co-ARIS, and a group of glutamine-rich tetratriacontapeptides named sperm activating peptide (SAP). The action of ARIS is quite species-specific due to the specificity of ARIS-receptors in a restricted domain of the sperm surface and depends very much on sulfated saccharide chains. Co-ARIS is not much species-specific and its action depends on the sulfate group and steroid side chain. SAPs have a ring of 25 residues and increase the intracellular pH of spermatozoa. None of them can induce the acrosome reaction by itself in normal sea water, but ARIS does induce it in high Ca2+ or high pH sea water. Although a combination of ARIS and either Co-ARIS or SAP induces the acrosome reaction in normal sea water, all three are required to mimic the full activity of dissolved jelly coat.

Acrosome↗

PubMed1994

[Aspects of disinfectants for control of nosocomial infections].

Use of disinfectants is regarded as the most important procedure for preventing the transmission of nosocomial infections. Because microorganisms exhibit a wide range of resistance to disinfectants, it follows that the kinds of microorganisms known and the characteristics of selected disinfectants must be consideration. Chemical disinfectants can be classified to three categories according to its germicidal action, namely, high-, intermediate-and low -level disinfectant. The efficacy of disinfection is affected by a number of factors, each of which nullify or limit the efficacy of the process. Some of the factors are the organic load on the object; the prior cleaning of the object; the type and level of microbial contamination; the concentration of and exposure time to the germicide; the temperature and pH of the disinfection process. Handwashing is the single most important procedure for preventing nosocomial infections. Although plain soaps have been shown to be adequate for routine handwashing in the absence of a true emergency, antimicrobial handwashing products should be used for handwashing before personnel take care of newborns, severely immunocompromised patients and patients in high-risk units. It will be possible to reduce the nosocomial infection that the use of rationale handwashing technique, motivation and knowledge about the importance of handwashing are achieved.

Cross Infection↗

PubMed1994

[Ureteral polyp prolapsing from the external urethral meatus: report of a case].

We herein report a case of a ureteral polyp treated with transurethral resection (TUR) in a 41-year-old female with the chief complaint of urethral tumor. Cystoscopic findings revealed the tumor originating from the right ureteral orifice. However, intravenous pyelography showed no abnormalities. We resected the tumor transurethrally and the histological diagnosis was ureteral polyp. The postoperative course was uneventful without any signs of vesico-ureteral reflux or recurrence of the polyp. This is the first case of ureteral polyp prolapsing from the external urethral meatus in the Japanese literature.

Adult↗

PubMed1993

Molecular cloning of cDNA for vacuolar membrane proton-translocating inorganic pyrophosphatase in Hordeum vulgare.

We obtained a cDNA clone(PP10) for the vacuolar membrane proton-translocating inorganic pyrophosphatase from barley roots by immunoscreening. The nucleotide sequence contained a 2308 bp open reading frame capable of coding for a polypeptide with 761 amino acids (M(r) 79,841). The polypeptide is highly hydrophobic and 12 membrane-spanning regions are deduced from the hydropathic evaluation. The characteristic cluster of the basic and acidic residues is observed in the hydrophilic segment. A consensus sequence with the dicyclohexyl-carbodiimide binding subunits of FOF1-type and vacuolar-type H(+)-ATPase is also observed in the membrane-spanning domain 5. Comparison of the deduced amino acid sequence with that of pyrophosphatase cDNA from Arabidopsis thaliana revealed 85.8% homology.

Amino Acid Sequence↗

PubMed1993

Effects of amosulalol, a combined alpha 1- and beta-adrenoceptor-blocking agent, on ischemic myocardial energy metabolism in dogs.

The effect of amosulalol, a combined alpha 1- and beta-adrenoceptor-blocking agent, on changes in myocardial energy and carbohydrate metabolism during ischemia was studied. Ischemia was induced by ligating the left anterior descending coronary artery for 3 or 30 min during open-chest surgery in anesthetized dogs. The myocardial energy stores were depleted, and the levels of glycolytic intermediates were altered by 3 and 30 min of ischemia, indicating that anaerobic myocardial metabolism had occurred. Amosulalol (0.3 or 1 mg.kg-1) was injected intravenously 5 min before ischemia. Pretreatment with amosulalol, particularly at a dose of 0.3 mg.kg-1, reduced the myocardial energy depletion and the alteration of carbohydrate metabolism induced by ischemia. This result indicates that amosulalol can reduce ischemic influences on the myocardium.

Adenosine Diphosphate↗

PubMed1993

Effects of bunitrolol on ischemic myocardial energy metabolism in dogs.

The effect of bunitrolol, a beta-adrenergic blocking agent having intrinsic sympathomimetic activity, on ischemic myocardial metabolism was examined in anesthetized dog hearts. Ischemia was induced by ligating the left anterior descending coronary artery for 3 or 30 min. Bunitrolol (0.3 or 1.0 mg/kg of body weight) was injected intravenously 5 min before the onset of ischemia. Ischemia reduced myocardial high-energy phosphate levels and changed the levels of glycolytic intermediates. Bunitrolol at a dose of 0.3 mg/kg significantly decreased heart rate, whereas the drug at a dose of 1.0 mg/kg did not. This result suggests that intrinsic sympathomimetic activity is observed only at a high dose of bunitrolol. Pretreatment with bunitrolol at 0.3 but not 1.0 mg/kg attenuated the myocardial metabolic changes caused by 3 min of ischemia. After 30 min of ischemia, a beneficial effect of bunitrolol on the ischemic myocardium was not observed. These results suggest that bunitrolol may lessen the ischemic influence on the myocardium in the early stage of ischemia and that intrinsic sympathomimetic action may not have a beneficial effect on the ischemic myocardium.

Animals↗

PubMed1993

Development and preliminary application of a simple assay of S-mephenytoin 4-hydroxylase activity in human liver microsomes.

We have developed a simple HPLC assay to measure the activity of S-mephenytoin 4-hydroxylase in human liver microsomes, and have assessed its practical applicability by determining the kinetic parameters of the enzyme in 10 different human liver samples. The recovery of 4-hydroxymephenytoin and phenobarbital (the internal standard) after the precipitation of microsomal protein was almost complete, and the coefficients of variation for the intra- and interassay measurement of S-mephenytoin 4-hydroxylase activity were < 6.4 and 8.0%, respectively. Eadie-Hofstee plots for the formation of 4-hydroxymephenytoin gave a straight line for all of the 10 samples studied. There was large interindividual variability in the kinetic parameters estimated: 4.6- (36 to 166 microM), 11.8- (0.9 to 10.6 nmole/mg protein/h) and 30.1- times (0.10 to 3.01 microliters/mg protein/min) for Km, Vmax and Vmax/Km, respectively. The mean (+/- SD) Km, Vmax and Vmax/Km were 72.4 +/- 40.4 microM, 4.23 +/- 2.88 nmole/mg protein/h and 1.33 +/- 1.02 microliters/mg protein/min, respectively. Thus, the assay was sufficiently accurate and reproducible to permit estimation of the kinetic parameters of S-mephenytoin 4-hydroxylase in human liver microsomes, and it appears to be applicable to an in vitro study of the possible involvement of S-mephenytoin-type oxidation polymorphism in drug metabolism.

Aryl Hydrocarbon Hydroxylases↗