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Biomedical subjects

K Kuroda

Publications and source records attributed to K Kuroda.

At least 289 records · Page 16Linked to original sources
PubMed1991

Studies on the flavin-binding region of old yellow enzyme with an active site probe, 8-fluoro-8-demethyl FMN.

The brewer's yeast old yellow enzyme (OYE) was reconstituted with 8-fluoro-8-demethyl FMN (8F-FMN). The reconstituted enzyme exhibited absorption maxima at 355 and 450 nm in the visible region. This reconstituted enzyme underwent no further spectral changes, showing no evidence of modification in the flavin moiety. However, when the reconstituted enzyme was subjected to specific limited proteolysis with bovine alpha-chymotrypsin, gradual spectral changes were observed with disappearance of the 355- and 450-nm bands accompanied by the appearance of a new band at 496 nm. Identical spectral changes were observed when the proteolytically cleaved OYE (nicked OYE) was reconstituted with 8F-FMN. The process associated with these spectral changes was found to be unimolecular by kinetic analysis. Reverse-phase HPLC analysis revealed that these spectral changes resulted from covalent bond formation between 8F-FMN and the protein moiety after the proteolytic cleavage of the protein into 14K and 34K fragments. The reverse-phase HPLC monitored at 490 nm showed that the chromophore with 496 nm absorption maximum was covalently attached to the 14K fragment. The amino acid sequence analysis of the flavinylated 14K fragment together with that of the 14K fragment of native OYE indicated that the N-terminal leucine of the 14K fragment is the site of flavinylation. These findings imply that the amino group of the N-terminal leucine of the 14K fragment became available as the result of proteolysis and that this amino group nucleophilically attacked the 8-position of 8F-FMN, forming a covalent bond between the flavin moiety and the 14K fragment.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Actin cytoskeleton of resting bovine platelets.

Actin filaments in resting discoid bovine platelets were examined by fluorescence and electron microscopy. Rhodamine-phalloidin staining patterns showed a characteristic wheel-like structure which consisted of a central small circle connected by several radial spokes to a large peripheral circle. This wheel-like structure was composed of actin filaments forming a characteristic arrowhead structure with heavy meromyosin from muscle. Actin filaments were densely arrayed in parallel with a marginal microtubule band and radiated out from the center to the periphery. Platelets treated with colchicine lost their marginal microtubule band but retained their wheel-like structure and normal discoid form. Cytochalasin B disrupted the wheel-like structure but not the marginal microtubule band or the normal discoid form. After simultaneous treatment with both cytochalasin B and colchicine, platelets lost their discoid shape. These results suggest that actin filaments and microtubules both play important roles in the maintenance of the discoid shape of resting bovine platelets.

Actins↗
PubMed1990

The oligosaccharides of influenza virus hemagglutinin expressed in insect cells by a baculovirus vector.

The hemagglutinin of fowl plague virus has been expressed in Spodoptera frugiperda (SF) cell cultures using a baculovirus vector. To elucidate the structure of the carbohydrate side chains, radioactively labeled oligosaccharides were liberated by treatment with endoglucosaminidase H and glycopeptidase F. Sequential degradation with exoglycosidases and chromatographic analyses revealed the presence of oligomannosidic side chains, predominantly of the structures Man5-9GlcNAc2, and the truncated oligosaccharide cores Man3GlcNAc2 and Man3[Fuc]GlcNAc2. Polyacrylamide gel electrophoresis of endoglycosidase-treated hemagglutinin showed that most side chains of the HA1 subunit are truncated, whereas the HA2 subunit has one oligomannosidic and one truncated oligosaccharide. Comparison of these results with the glycosylation pattern of hemagglutinin obtained from vertebrate cells allowed a tentative allocation of the oligosaccharides to individual glycosylation sites. The results indicate that SF cells have the capacity to trim N-glycans to trimannosyl cores and to further process these by the addition of fucose. Thus, the complex oligosaccharides found on hemagglutinin from vertebrate hosts are replaced on hemagglutinin derived from insect cells by small truncated side chains.

Animals↗
PubMed1990

A host range mutant of Newcastle disease virus with an altered cleavage site for proteolytic activation of the F protein.

The primary structure of the F protein of a host range mutant of the Ulster strain of Newcastle Disease virus (NDV) has been determined by nucleotide sequence analysis and compared to that of the wild type and other NDV strains. The cleavage site of the mutant had the sequence Gly-Lys-Gln-Arg-Arg as compared to two isolated basic amino acids [Gly-Lys(Arg)-Gln-Gly-Arg] with the apathogenic strains and two pairs of basic amino acids [Arg-Arg-Gln-Lys(Arg)-Arg] with the pathogenic strains. The data indicate that the cleavability of the F protein of NDV increases with the number of arginine and lysine residues at the cleavage site and that the susceptibility of the pathogenic strains to ubiquitous host proteases depends on both pairs of basic amino acids.

Amino Acid Sequence↗
PubMed1990

The expression of the Autographa californica nuclear polyhedrosis virus genome in insect cells.

This report presents a synopsis of recently published work in our laboratory on the molecular biology of the insect baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV). The following studies have been summarized. (1) On the mode of transcription of the AcNPV genome in insect cells. (2) Translation of proteins encoded in the 81.2 to 85.0 map unit segment of AcNPV. (3) Inserts of insect cell DNA in the AcNPV genome. (4) Expression of influenza (fowl plague) virus haemagglutinin in Spodoptera frugiperda insect cells, and successful immunization of chickens. (5) Synthesis of the influenza virus haemagglutinin in insect larvae by recombinant AcNPV. This insect virus system will continue to serve as a model for research on the molecular biology of insects. Moreover, the baculovirus system has been recognized as a very efficient and safe eukaryotic expression vector.

Animals↗
PubMed1990

Immunoaffinity purification and properties of Drosophila melanogaster DNA polymerase alpha-primase complex.

Two hybrid cell lines (DM88-5E12 and DM88-4C9) secreting monoclonal antibodies against DNA polymerase alpha-primase complex from Drosophila melanogaster Kc cells were established by immunizing mice with the complex partially purified by a conventional method. The IgG subclasses of both antibodies were IgG1. Both antibodies immunoprecipitated the DNA polymerase alpha-primase complex from D. melanogaster Kc cells. The DNA-polymerizing activity was neutralized by 4C9 antibody, but not by 5E12 antibody. The DNA priming activity was not neutralized by either antibody. These antibodies did not cross-react to HeLa DNA polymerase alpha-primase complex. A rapid, two-step purification of DNA polymerase alpha-primase complex from D. melanogaster Kc cell was carried out by 5E12 antibody column chromatography followed by single-stranded DNA cellulose column chromatography. The immunoaffinity-purified enzyme had both DNA-polymerizing and DNA-priming activities with the specific activities of 50,000 and 2,000 units/mg, respectively. The effects of aphidicolin, NEM, ddTTP, BuPdGTP, and DMSO on the enzyme activity showed that the purified enzyme was DNA polymerase alpha, but not DNA polymerase beta, gamma, or delta. The purified enzyme consisted of polypeptides with apparent molecular weights of 180 (and 145, 140, 130 kDa), 72, 63, 51, and 49 kDa. The 5E12 antibody was shown to bind to all the high-molecular-weight polypeptides, 180, 145, 140, and 130 kDa, by immuno-Western blotting analysis.

Animals↗
PubMed1990

Inhibitory effect of fumaric acid on hepatocarcinogenesis by thioacetamide in mice.

The inhibitory effect of fumaric acid (FA) on hepatocarcinogenesis was examined in mice fed thioacetamide (TAA). A group of male ICR mice was fed TAA at a level of 0.035% in the diet for 40 weeks and then fed a basal diet for 48 weeks. Hepatic tumors developed in 11 of the 24 animals of this group and they were diagnosed as hepatocellular carcinomas. However, cirrhotic lesions and the enlargement of hepatocyte nucleoli were not as marked in mice as in previous findings in rats fed TAA. The effect of FA on the carcinogenesis was examined in a group of mice fed this compound at a level of 1% in a basal diet after ingestion of TAA. The inhibitory effect of FA on TAA carcinogenesis was so marked that no hepatic carcinomas were found in any of the 15 animals fed FA in combination with TAA.

Animals↗
PubMed1990

Calmodulin antagonistic action of KS-504a, a novel metabolite of the fungus Mollisia ventosa.

KS-504a inhibited bovine brain calmodulin-dependent cyclic nucleotide phosphodiesterase (CaM-PDE) with an IC50 value of 122 microM. The inhibition was reversed by a high concentration of calmodulin. Calmodulin-independent activities of the enzyme were not affected by the compound at the same concentration ranges. Ca2(+)-dependent interaction of the compounds with calmodulin was shown using hydrophobic fluorescence probes. These data indicated that the compound exerted its effects on CaM-PDE by interacting with calmodulin. KS-504a also inhibited other calmodulin-dependent enzymes at different concentration ranges; myosin light chain kinase was inhibited at the lowest concentrations with an IC50 value of 6.3 microM. The inhibition mechanism was competitive with respect to calmodulin and non-competitive to ATP.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1990

Antihypertensive mechanism of action of the novel angiotensin converting enzyme inhibitor benazepril. Effect on isolated vascular preparations.

Benazepril (CGS 14824A HCl) is a new prodrug type angiotensin converting enzyme (ACE) inhibitor. The active form is considered to be benazeprilat, a diacid hydrolyzed compound. Benazepril and benazeprilat inhibited the contraction induced by exposure with angiotensin I, not angiotensin II, in the isolated rabbit aorta. The ACE inhibiting activity of benazeprilat was 1000 times more potent than that of benazepril in this experiment. Benazepril as well as benazeprilat and captopril exerted little influence on norepinephrine, serotonin and high K(+)-induced contraction or bradykinin-induced relaxation in isolated blood vessel preparations, thus angiotensin II synthesis inhibition seemed to be the main cause for its vasodilation. Benazepril, unlike benazeprilat or captopril showed considerable influence on prostaglandin (PG)-induced responses at higher concentrations. The vasocontraction induced by PGF2 alpha was competitively antagonized at 10(-5)-10(-4) mol/l, while vascular responses induced by PGE1, PGE2 or PGI2 was inhibited at 3 x 10(-4) mol/l of benazepril. Although these influences on PGs might not contribute much to its vasodilatory mechanism, the action seemed interesting in relation to cough induction, a known side effect of ACE inhibitors in the market. Benazepril has two asymmetric carbon atoms, thus four optical isomers are possible, SS (benazepril), SR (CGP 14'829A), RS (CGP 42'454A), RR (CGP 42'456A). The SS configuration was the most potent for antagonizing angiotensin I-induced vasocontraction, which seemed to be the best fitted for the ACE molecule.

Alprostadil↗
PubMed1990

[Comparison of factors related to hospitalization versus home care of elderly].

This study was done to identify factors affecting present hospitalization versus home care in 4,578 elderly subjects representing 87.1% of the elderly population living in S. city near Osaka. Subjects or their families were asked by interviews regarding the age of the subjects, the kind of persons living together in the family unit, the kind of housing, the number of rooms in the family dwelling, and health conditions. Subjects were also asked whether he or she could walk unassisted and whether home care would be preferred in case of an illness. Among the 153 hospitalized subjects, ability to walk, age, and the number of rooms were all significant factors, in decreasing order. Among the 1,193 persons who preferred home care in case of an illness, the number of rooms, age, ability to walk, and the size of the family unit were all significant factors, in decreasing order. Among subjects who could not walk unassisted, the number of rooms was the main factor determining their admission and not preferring home care if their condition worsened. Thus, although the ability to walk is the major factor among the factors we investigated, housing conditions are also important if home care is to be possible.

Aged↗
PubMed1990

[A study of attitudes toward illness and its effect on mortality in patients with Parkinson's disease].

The standardized mortality ratio (SMR), i.e. the ratio of observed to expected deaths, was investigated among 433 patients with Parkinson's disease (172 males and 261 females), who had been visited by public health nurses for a period of more than one year between 1978 and 1987 in Osaka Prefecture. The mean age of the patients was 58.7, and the average duration of the disease was 6.1 years at study entry. The follow-up period averaged 4.1 years during which sixty eight deaths were observed. The SMR of the patients was 2.54 relative to the general population of Osaka Prefecture. The SMR of those who were able to walk without assistance at study entry was 1.73, while that of patients with severe gait disturbance was 3.81. Patients were divided into three groups according to the extent of daily physical exercise performed to maintain their remaining function. Among patients who had been able to walk, those doing daily physical exercise showed the lowest SMR of 1.46. Among those with severe gait disturbance, the SMR of the exercising group was also the lowest at 1.72. These results indicate that daily physical exercise affects the mortality of Parkinsonian patients independently of the grade of disability. Participation in daily exercise was strongly influenced by the patient's will to battle his illness, and was significantly related to the presence of a spouse, economic situation of household, and the number of rooms in their dwelling.

Adult↗
PubMed1990

[The effect of professional dental health care in the prevention of periodontal diseases in adults].

Dental health conditions of participants in adult general health examinations provided as a health service by a local government from 1983 to 1987, were analyzed to evaluate the effect of individual dental health instructions with prophylactic treatment (individual instructions) for preventing periodontal diseases. For this purpose, Periodontal Index (Russel) and Debris Index (Greene & Vermillion) of 557 dentate adults aged 40-59 were examined. In the group that received individual instructions, average PI showed a significantly greater decrease during the period from the first inspection in 1983-1986 to the last one in 1987, compared to the group that received no individual instructions. For those with PImax greater than or equal to 6 at the first examination in 1983-1986, the figures of average PI showed a significantly greater decrease in those receiving instruction than the group that received no individual instructions. Between 1983-1987, the proportion of persons with PImax greater than or equal to 6 decreased from 74.2% to 27.3% as a result of the individual instructions. The figures for average DI showed significant changes but, no significant difference was observed between the two groups.

Adult↗
PubMed1990

Malignant fibrous histiocytoma. Induced by thorium.

Thorium dioxide is a deleterious substance that was employed as a vascular contrast medium during the early 20th century. Our report entails a unique neoplastic complication of thorium administration.

Adolescent↗