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Biomedical subjects

Y Sakai

Publications and source records attributed to Y Sakai.

At least 721 records · Page 40Linked to original sources
PubMed1989

Evidence that the Na+-Ca2+ exchange system is related to the antiarrhythmic action of disopyramide.

1. Disopyramide induced a concentration-dependent decrease in action potential amplitude and Vmax, and prolonged action potential durations (APD50 and APD90) in ventricular muscle. 2. Na+-loaded membrane vesicles isolated from canine ventricular muscle rapidly accumulated Ca2+. 3. Monensin (10(-5) M) abolished Na+-dependent Ca2+ uptake, and Na+ enhanced Ca2+ efflux. 4. Na+-Ca2+ exchange by membrane vesicles was more active in preparations pretreated with disopyramide (10(-5) M) than in control membranes. 5. The results suggest that disopyramide changes Na+ influx from Na+ channel mediated to Na+-Ca2+ exchange mediated. This is verified in part by increased Ca2+ efflux.

Animals↗
PubMed1989

Alcohol use and retinal vessels: insights into the mechanism of alcohol-induced stroke.

Alcohol use is a recognized risk factor for stroke. We hypothesized that alcohol use may increase the risk of stroke, independent of an effect on blood pressure, by causing cerebral vasoconstriction. To examine this, we used retinal vessels as a marker for cerebral vessels and analysed the cross-sectional associations between alcohol use and total retinal vessel width in 741 Japanese and 434 American white male telephone executives. Systolic and diastolic blood pressures were negatively associated with retinal vessel width in the Japanese (p less than 0.0001, 0.0001, respectively) but this association did not achieve statistical significance in the Americans (p less than 0.1, 0.3). Japanese drinkers had a larger mean retinal vessel width than Japanese abstainers, while American drinkers had a smaller retinal vessel width than abstainers. These associations between alcohol use and retinal vessel width were not significant within nationalities but the interaction between alcohol use and nationality was significant, independent of other stroke risk factors (p less than 0.04). Although these results do not support the initial hypothesis, they are consistent with known biological differences in alcohol metabolism between Japanese and American men and support different effects of alcohol use on retinal vessel calibre in these two nationalities.

Adult↗
PubMed1989

Purification and characterization of membrane-bound 5'-nucleotidase of Vibrio parahaemolyticus.

Membrane-bound 5'-nucleotidase from Vibrio parahaemolyticus was solubilized and purified using a nonionic detergent, heptyl-beta-D-thioglucoside, and was characterized. This enzyme required Mg2+ for activity, maximum activity being observed at 5 and 20 mM Mg2+ with AMP and ATP, respectively, as substrates. Of the divalent cations tested, Mn2+ and Co2+ were able to replace Mg2+ partially, whereas Ca2+ was ineffective. Zinc strongly inhibited the enzyme activity and Ni2+ caused partial inhibition. This enzyme required Cl- for activity, the optimal concentration being 20 mM or more. The order of effectiveness of anions was Cl- greater than Br- greater than I- approximately NO3-. Sulfate and acetate were ineffective. The optimal pH was 8.0. The activity of the purified enzyme was stimulated by the addition of lipid to the assay mixture. This enzyme hydrolyzed all 5'-nucleotides tested, but did not hydrolyze 3'-nucleotides or ribose 5-phosphate. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme appeared to be a single polypeptide, with a molecular weight of 72 kDa.

5'-Nucleotidase↗
PubMed1989

Cloning and expression of the 5'-nucleotidase gene of Vibrio parahaemolyticus in Escherichia coli and overproduction of the enzyme.

The gene encoding the membrane-bound 5'-nucleotidase of Vibrio parahaemolyticus was cloned and expressed in Escherichia coli. Cells of E. coli harboring a plasmid, pNUT5, which carries the 5'-nucleotidase gene were able to grow on ATP as the sole source of carbon, although the original cells were not. The 5'-nucleotidase activity was detected in whole cells of E. coli harboring pNUT5 and in membrane vesicles prepared from these cells. Most properties of the 5'-nucleotidase produced in E. coli, that is, its requirements for Cl- and Mg2+, substrate specificity, and inhibition by Zn2+, were similar to those observed in V. parahaemolyticus, but some alterations in properties were observed: The 5'-nucleotidase was partially inducible in V. parahaemolyticus, but its expression in E. coli was completely constitutive. The specific activity of the 5'-nucleotidase in membrane vesicles of E. coli harboring the plasmid was 30 times that observed in whole cells, whereas the specific activities in membrane vesicles and in whole cells of V. parahaemolyticus were almost the same. A new, dense band of protein with an apparent molecular mass of 63 kDa was detected when membrane proteins of E. coli harboring the plasmid were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

5'-Nucleotidase↗
PubMed1989

Urinary and serum zinc levels in chronic pancreatitis.

Urinary and serum zinc levels were determined in 51 patients with chronic pancreatitis. Urinary zinc excretion in patients with chronic calcified pancreatitis (832 +/- 111 micrograms/day) (mean +/- SE) but not in noncalcified pancreatitis (684 +/- 65 micrograms/day) was significantly higher than in normal controls (418 +/- 46 micrograms/day). The urinary zinc excretion increased with deterioration of exocrine pancreatic function. Serum zinc levels in advanced pancreatitis (105.9 +/- 4.5 micrograms/100 ml) were significantly higher when compared to the pancreatitis with normal exocrine pancreatic function (91.6 +/- 3.0 micrograms/100 ml), but the difference was less pronounced than for urinary zinc excretion. This may be due to complicating diabetes, which usually lowers serum zinc. Serum zinc and urinary zinc excretion were low in a patient with chronic calcified pancreatitis complicated with a pulmonary abscess and hypoalbuminemia. In conclusion, urinary and serum zinc levels in chronic pancreatitis were increased as a result of exocrine pancreatic dysfunction. Association of diabetes may lower serum zinc, and associated malnutrition depresses both urinary and serum zinc levels.

Adult↗
PubMed1989

Pyridine nucleotide fluorometry in preserved porcine liver with fluorocarbon emulsion.

Oxidation-reduction changes in pyridine nucleotide fluorescence were investigated in perfused and preserved porcine liver. A fluorocarbon emulsion (FC-43) was administered to the perfusate as an oxygen carrier to obtain full oxidation level by portal perfusion at a physiological low flow rate. A satisfactory reading was obtained by portal perfusion with EuroCollins' solution containing 10% v/v FC-43 at a rate of 0.5 ml/min/g liver. The amplitude (R x A) and the changing velocity (R x V) from full oxidation to full reduction were determined in the resultant trace curve. Both R x A and R x V decreased in inverse proportion to the duration of preservation period (3, 6, 12 hr). Adenine nucleotide content, hepatic energy charge level, and ketone body ratio in the tissue were simultaneously measured, and they also decreased proportionally to the duration of preservation. There were close positive correlations between R x A and total adenine nucleotide concentration (r = 0.841, P less than 0.01), between R x V and energy charge (r = 0.787, P less than 0.01), and between R x V and tissue ketone body ratio (r = 0.881, P less than 0.01). These results suggest that pyridine nucleotide fluorometry can accurately follow the cellular function of isolated porcine liver by administration of FC-43 in perfusate. This fluorometry may also have potential application in evaluating viability of a large organ like the human liver graft.

Adenine Nucleotides↗
PubMed1989

A sensitive IL-1 thymocyte co-stimulator assay using a novel beta-D-galactoside specific lectin from the beetle, Allomyrina dichotoma.

A sensitive thymocyte co-stimulator assay of IL-1 using a beta-D-galactoside specific lectin (allo A) obtained from the beetle (Allomyrina dichotoma) is reported here. Allo A stimulated [3H]thymidine uptake of mouse thymocytes in the presence of IL-1. The allo A assay was more sensitive than the PHA or PNA- thymocyte assay, especially at low doses of IL-1. Optimal conditions for the allo A assay were as follows: allo A, 2.5-5.0 micrograms/ml; whole thymocytes, 0.5-1.0 x 10(6) cells/well; incubation time, 72-96 hr. The assay is sensitive and convenient and can easily be performed in any laboratory.

Animals↗
PubMed1989

Clinical significance of serum antibodies against alcohol-altered hepatocyte membrane in alcoholic liver disease.

The clinical significance of serum antibodies against alcohol-altered rabbit hepatocytes was evaluated in 91 patients with alcoholic liver disease. Patients were divided into two groups according to the presence or absence of those antibodies at the time of first admission, and their clinical, biochemical, and histological findings were compared. In 38 seropositive patients, the total amount of ethanol consumption as well as serum activity of glutamate-oxaloacetate transaminase, serum levels of total bilirubin, gamma-globulin, IgG, and IgA were all significantly higher than in 53 seronegative patients. In addition, the extent of fibrosis, alcoholic hyalin, cholestasis, and lymphocytic and polymorpholeukocytic infiltrations in the liver were all significantly greater in the seropositive patients. Histological changes were compared in the 16 patients who continued to drink alcohol and who received repeated liver biopsies. Seven out of eight patients who were seropositive at the time of the first liver biopsy showed histological deterioration, whereas one of the eight seronegative patients showed a slight progression. These results suggest that the presence of serum antibodies against alcohol-altered liver cell membrane delineates a group of alcoholic patients with severe, advanced liver disease characterized by a tendency to progress with continued alcohol ingestion.

Alanine Transaminase↗
PubMed1989

Comparisons of sizes of pinealocyte nuclei and pinealocytes in young and adult Chinese hamsters (Cricetulus griseus) under different photoperiod conditions.

Semiquantitative electron microscopic observations on pinealocytes of the Chinese hamster (Cricetulus griseus) were made to compare the sizes of pinealocyte nuclei and pinealocytes as a whole, their nuclei and cytoplasm together, over a 24-hr period, between young animals (60-70 days old) and adult animals (120-130 days old) under LD 12:12 and between adults under LD 12:12 and LD 14:10. Under LD 12:12, similar 24-hr rhythms exist in the nuclear area and the area of pinealocytes of young animals, whereas in adults these values exhibit no significant 24-hr rhythm. In adults under LD 14:10, there is no significant 24-hr rhythm in the nuclear area, but the area of pinealocytes shows a statistically significant 24-hr rhythm. Thus, in the Chinese hamster, the relationships between nuclear area and area of pinealocytes with time of day vary, depending on the age of animals as well as different photoperiodic conditions, although they differ only slightly.

Aging↗
PubMed1989

Syncytium formation by recombinant vaccinia viruses carrying bovine parainfluenza 3 virus envelope protein genes.

The highly syncytium-inducing M strain and the weakly syncytium-inducing SC strain of bovine parainfluenza 3 virus differ by a single amino acid substitution in each of the hemagglutinin-neuraminidase (HN) and membrane (M) proteins, while their fusion (F) proteins are identical (T. Shioda, S. Wakao, S. Suzu, and H. Shibuta, Virology 162:388-396, 1988). We constructed recombinant vaccinia viruses which express separately the M virus HN (Vac-MHN), SC virus HN (Vac-SCHN), M virus M (Vac-MM), SC virus M (Vac-SCM), and common F (Vac-F) proteins. CV-1 cells were infected with the recombinants, singly or in combination, and implanted onto indicator MDBK cells for syncytium formation. Combinations of Vac-MHN plus Vac-F and Vac-SCHN plus Vac-F induced extensive and weak syncytium formation, respectively. Vac-F alone did not induce syncytium formation, and both Vac-MM and Vac-SCM had no effect on syncytium formation. These findings indicated that the syncytium formation by bovine parainfluenza 3 virus requires both the F and HN proteins and that the extensive syncytium formation by the M virus is due to the M virus HN protein. MSC, another weakly syncytium-inducing virus variant, newly isolated from the M virus, was identical to the M virus in the primary structure of the HN and M proteins but differed from the M virus by a single amino acid residue in the F protein. The combination of the recombinant vaccinia virus expressing the MSC virus F protein and Vac-MHN resulted in weak syncytium formation.

Amino Acids↗
PubMed1989

Orthotopic partial liver transplantation in dogs can be performed without cold perfusion of the donor liver. Evaluation of its feasibility in terms of energy metabolism.

To investigate the feasibility of obtaining grafts from living, genetically related adult donors without any complicated harvesting techniques, orthotopic partial liver transplantation (PLT) without cold perfusion of the donor graft was evaluated in beagles by assessing the graft viability using ketone body ratio (KBR). Ten PLT were performed under venovenous bypass. The left half of the donor liver was transected in situ followed by systemic heparinization, and immediately implanted with care taken to leave the recipient's inferior vena cava intact, and to maintain the normothermic state without cold perfusion. Four of ten dogs survived for 5 days or longer (longest survival was 9 days) and died of other causes than graft dysfunction. Four others died of thromboembolitic episode, accidental bleeding or technical failure. Two dogs died of graft dysfunction. The changes in KBR in 5 dogs without fatal complications after transplantation were maintained within normal range thereafter. These results suggest that the PLT without cold perfusion of donor graft is possible from the viewpoint of energy metabolism.

Animals↗
PubMed1989

Differential inhibitory effects of various herb extracts on the activities of reverse transcriptase and various deoxyribonucleic acid (DNA) polymerases.

Forty preparations of the extracts from 28 kinds of Asian herbs were tested for ability to inhibit the activities of murine retroviral reverse transcriptase and human deoxyribonucleic acid (DNA) polymerases. Among the 40 extracts, 35 inhibited reverse transcriptase activity and 29 inhibited DNA polymerase alpha activity. The inhibitory potencies of these extracts were expressed as the 50% inhibition concentrations (IC50), at which the enzyme activities were inhibited by 50%. Very strong inhibitions were observed with the extracts from Millettia pachycarpa (Leguminosae) and Mallotus apelta (Euphorbiaceae) as shown by their low IC50 values for reverse transcriptase (0.4-0.5 micrograms/ml) and DNA polymerase alpha (0.9-1.4 micrograms/ml). Enzyme kinetic analysis revealed that the mode of inhibition of reverse transcriptase by these two extracts was competitive with respect to the template.primer [poly(rA).oligo(dT)] and noncompetitive with respect to deoxythymidine triphosphate (dTTP) substrate. Besides reverse transcriptase and DNA polymerase alpha, DNA polymerase I and ribonucleic acid (RNA) polymerase from E. coli were inhibited by these two extracts. These results indicate that the herb extracts contain as yet unidentified substance(s) which inhibit the activities of reverse transcriptase and cellular DNA polymerases.

Humans↗
PubMed1989

Distribution-analyzing latex immunoassay (DALIA): methods for determination of antigen and for elimination of non-specific reaction induced by rheumatoid factor.

A highly sensitive distribution-analyzing latex immunoassay method (DALIA), which is based on analysis of the volume distribution of latex particles including both the agglutinates and the residual non-agglutinating particles, has been established. Numbers of latex particles, which are sensitized with specific antibodies, are counted by using an electric particle counter with a personal computer and simultaneously the extent of agglutination was quantified by analyzing the volume distribution of the reacted latex particles. It was found that ultramicrospheres coated with normal goat immunoglobulin G can completely eliminate non-specific reactions induced by human serum containing rheumatoid factor (RF) in this DALIA method. The degree of absorption of RF activity by these ultramicrospheres was associated with the diameters of the ultramicrospheres. Moreover, by use of the combination of ultramicrospheres and latex particles coated with monoclonal antibodies against alpha-fetoprotein (AFP) or with polyclonal antibody specific to C-reactive protein, specific DALIA systems were able to be developed. Both DALIA systems exhibited the high sensitivity (1 to 7 ng/ml). The correlation coefficient (gamma) of the results of DALIA with those of enzyme-linked immunoadsorbent assay in measuring AFP was 0.994.

Antigens↗
PubMed1989

Photo-switchable ion and enzyme sensors. Photoinduced potentiometric response of glassy carbon electrode coated with polymer or polymer/enzyme dual membrane.

Photo-switchable ion and enzyme sensors were fabricated by the use of glassy carbon electrode coated with nonactindoped or enzyme modified poly(vinyl chloride) (PVC) membranes. The ion sensor with nonactin-doped PVC membrane, which contained spirobenzopyran as the photosensitive dye, exhibited a potentiometric photoresponse to NH4+ ion in the solution. The dynamic range of the NH4+ ion sensor was 10(-7)--10(-3) M. Urea, adenosine, and asparagine sensors were prepared by coating the surface of the NH4+-ion sensor with urease, adenosine deaminase, and asparaginase membranes, respectively. These enzyme sensors could be used for determining the substrates at the micro mole level. The performance characteristics of these sensors were compared with those previously prepared membrane electrode sensors.

Carbon↗
PubMed1989

Induced ovulation in cats using porcine pituitary gland preparation during the non-breeding season.

An attempt was made to induce ovulation in 19 cats during the non-breeding season by the administration of a porcine pituitary gland preparation. The dosage was 2 mg for the first day and then 1 mg for each day until estrus was induced. Studies were made to determine whether fertilization and pregnancy were possible by mating at the time of induced estrus. Estrus was induced in 89.5% (17/19) of the cats, 3-8 days after the first administration. The average number of ovulations induced by mating was 7.3 +/- 1.3 (mean +/- SE) for 16 cats (excluding one cat that failed to ovulate). The uterine horn was flushed 6-8 days after mating in 9 of the 16 ovulated cats to determine the fertilization rate. An average of 3.6 ova were recovered from 8 out of the 9 cats (including one cat from which no ovum was recovered) which gave an average recovery rate of 38.6%. Expanded blastocysts were recovered from 5 cats, while from the other 3 cats, only unfertilized ova were recovered. Pregnancy was confirmed in the other 7 cats 15-20 days after mating. In two of the 7 cats implantation was observed, but abortion occurred at 24 and 27 days of pregnancy. Plasma progesterone concentrations were lower in the estrus-induced and bred cats as compared to these in the controls, with progesterone values approaching base concentrations, approximately by day 20 in 2 cats and by day 30 in 3 cats. It was concluded that estrus could be induced in cats during the non-breeding season by administration of porcine pituitary gland preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Selection error of upper anterior artificial teeth].

Seventy two cases of selection error of upper anterior artificial teeth due to the esthetic factors were investigated out of the 1,507 cases of removable dentures, which were made at the Prosthodontics department of Nihon University school of dentistry at Matsudo for 17 years from November, 1971 to November, 1988. The following were the results of the investigation. 1. Frequency of the selection errors amounted to 4.8% of the total selected cases as broken down in 1.6% by Shade and 4.0% by Mould, the rate of selection errors of the Mould being significantly high. 2. By Mould, selection errors in Ovoid type occupied a significantly high rate. 3. Regarding frequency of Mould after re-selection ST and TO occupied a high rate of 45.9%. 4. Mould of re-selection were almost uniformly small, showing a trend of intumescence becoming emphatically.

Denture, Partial, Removable↗