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Biomedical subjects

M Nagai

Publications and source records attributed to M Nagai.

At least 361 records · Page 20Linked to original sources
PubMed1991

Ruptured distal anterior cerebral artery aneurysms presenting as acute subdural hematoma--report of three cases.

The authors report three cases of distal anterior cerebral artery aneurysm presenting as acute subdural hematoma (SDH). Two patients were comatose on admission and died of massive SDH. One patient underwent aneurysmal neck clipping in the chronic stage and returned to normal daily life. A convexity SDH continuous with a wedge-shaped interhemispheric SDH was the characteristic computed tomographic appearance in all cases. There was no accompanying subarachnoid or intracerebral hemorrhage in one case (pure SDH). These cases are 9.4% of 32 ruptured distal ACA aneurysms treated in our institute in the last 14 years, a higher incidence than reported previously.

Acute Disease↗
PubMed1991

Effect of pyridoxine-deficiency on degradation of cytosolic aspartate aminotransferase in rat liver lysosomes.

Highly purified lysosomes were isolated from the livers of control and pyridoxine-deficient rats. The calculation of the lysosomal protein contents indicated that the livers of both groups of rats contain virtually the same amounts of the lysosomal proteins (12.0 and 13.0 mg lysosomal proteins/g liver proteins for the control and pyridoxine-deficient rats, respectively). The immunoblotting of the lysosomal proteins with anti-cytosolic aspartate aminotransferase (cAspAT) showed 46 kDa band, corresponding to the subunit molecular weight of cAspAT, as well as the bands representing degradative intermediates of cAspAT. The relative amounts of the immuno-reactive substances were estimated by scanning the immuno-stained bands and measuring the densitometric tracings. It was found that the lysosomes in the pyridoxine-deficient rat liver contain almost twice as much cAspAT and its degradative intermediates as those in the control rat liver. On the basis of these observations, it was concluded that the increased rate of degradation of cAspAT in the liver of the pyridoxine-deficient rats is brought about by the increased rate of sequestration of cAspAT into lysosomes.

Animals↗
PubMed1991

AZT: a biochemical response modifier of methotrexate and 5-fluorouracil cytotoxicity in human ovarian and pancreatic carcinoma cells.

In ovarian and pancreatic carcinoma cell lines, the activity of the salvage enzyme, thymidine kinase (EC 2.7.1.21), was 2- to 13-fold higher than that of the key enzyme of thymidylate de novo biosynthesis, thymidylate synthase (dTMP synthase, EC 2.1.1.45). AZT (3'-azido-3'-deoxythymidine, zidovudine) competitively inhibited thymidine kinase activity in extracts of human ovarian and pancreatic carcinoma cells, with Dixon plots yielding Ki = 1.1 microM in both cell lines. AZT (20 microM) yielded synergistic cytotoxicity with methotrexate (0.4 microM) in human pancreatic carcinoma cells in clonogenic assay and also with methotrexate (0.02 microM) in human ovarian carcinoma cells, as measured by cell counts. Thymidine (10 microM) and hypoxanthine (100 microM) reversed these inhibitions. AZT (20 or 40 microM) also provided synergistic cytotoxicity with 5-fluorouracil (0.5 and 1.0 microM) in human pancreatic carcinoma cells in clonogenic assay. These studies suggest a new role for AZT, which, as an inhibitor of thymidine salvage, should be useful as a biochemical response modifier to provide a synergistic clinical anticancer impact on de novo biosynthesis of thymidylates in conjunction with methotrexate or 5-fluorouracil.

Animals↗
PubMed1991

Tiazofurin down-regulates expression of c-Ki-ras oncogene in a leukemic patient.

The increased activity in cancer cells of inosine 5'-monophosphate dehydrogenase (IMP DH, EC 1.1.1.205), the rate-limiting enzyme of de novo GTP biosynthesis, was suggested as a sensitive target for chemotherapy. Tiazofurin (NSC 286193), through its conversion to the active metabolite, thiazole-4-carboxamide adenine dinucleotide (TAD), is a strong inhibitor of IMP DH. In our clinical trial, tiazofurin caused return to the chronic phase in patients with chronic granulocytic leukemia in blast crisis (Tricot, G.; Jayaram, H.N.; Weber, G.; Hoffman, R. Tiazofurin: Biological effects and clinical uses. Int. J. Cell Cloning 8:161-170; 1990). In K562 human leukemic cells, tiazofurin down-regulated the expression of c-Ki-ras and c-myc oncogenes, which was followed by induced differentiation. We now report down-regulation by tiazofurin of the c-Ki-ras oncogene in a patient with chronic granulocytic leukemia in blast crisis. A single tiazofurin infusion (2,200 mg/m2) on days one and two decreased IMP dehydrogenase activity (the apparent t1/2 was 30 min), GTP concentration (the apparent t1/2 was 6 hr), and expression of ras (the apparent t1/2 was 8 hr) and c-myc (the apparent t1/2 was 38.5 hr) oncogenes in the leukemic cells. No further tiazofurin was given, because on days three and four the chemotherapeutic impact became evident in a tumor-lysis syndrome and the blast cells were cleared from the periphery by day five. The decrease in IMP DH activity, GTP concentration, and expression of c-Ki-ras oncogene were early markers of the successful chemotherapeutic impact of tiazofurin in a patient with chronic granulocytic leukemia in blast crisis.

Adenine Nucleotides↗
PubMed1991

Poststatin, a new inhibitor of prolyl endopeptidase, produced by Streptomyces viridochromogenes MH534-30F3. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

Poststatin, a new inhibitor of prolyl endopeptidase (PEP) was discovered in the fermentation broth of Streptomyces viridochromogenes MH534-30F3. It was purified by Diaion HP-20, Sephadex LH-20 and YMC-gel (ODS-A) column chromatography and then isolated as a colorless powder. Poststatin has the molecular formula C26H47N5O7. The IC50 value of poststatin against the PEP of partially purified porcine kidney was 0.03 microgram/ml. It has low acute toxicity. No deaths occured after iv injection of 250 mg/kg of this agent to mice.

Amino Acid Sequence↗
PubMed1991

Poststatin, a new inhibitor of prolyl endopeptidase, produced by Streptomyces viridochromogenes MH534-30F3. II. Structure determination and inhibitory activities.

Poststatin, a new inhibitor of prolyl endopeptidase, has been isolated from the culture broth of Streptomyces viridochromogenes MH534-30F3. The structure of poststatin was defined as L-valyl-L-valyl-3-amino-2-oxovaleryl-D-leucyl-L-valine by analysis of spectral properties and chemical studies of poststatin and its derivatives. The alpha-keto group of postine in poststatin plays the most important role on the inhibitory mechanism.

Amino Acid Sequence↗
PubMed1991

Cardiac sequelae of Kawasaki disease in Japan: statistical analysis.

The proportions of Kawasaki disease patients with cardiac sequelae in Japan were analyzed using nationwide survey data from the 6 1/2-year period July 1982 through December 1988. Of 46,864 cases of Kawasaki disease reported in the surveys, 7637 or 16.3% had cardiac sequelae such as dilation or stenosis of coronary arteries, myocardial infarction, and valvar lesions 1 month or more after onset. The prevalence of cardiac sequelae was particularly high in males, infants younger than 1 year, and children older than 5 years of age. In sequential observation, there was no correlation between the prevalence of cardiac sequelae and periods of high or low incidence of the disease. The prevalence of cardiac sequelae overall declined steadily over the observation period, perhaps as a consequence of increasing use of intravenous gamma globulin. However, children older than the age of 5 years manifested increasing prevalence of cardiac sequelae over the observation period, probably as a result of lower rates of intravenous gamma globulin administration.

Child↗
PubMed1991

[A method of interval estimation for number of patients in the nationwide epidemiological survey on intractable diseases].

A method for estimating the intervals for the number of patients with intractable diseases from nationwide epidemiological surveys was developed under the assumption that response is independent of frequency of patients. This method is based on data utilizing the number of response hospitals classified by their reported number of patients. The approximate 95% confidence intervals of numbers of several intractable diseases patients were estimated using this method.

Data Interpretation, Statistical↗
PubMed1991

[Treatment of severe infections in hematologic malignancies with piperacillin sodium].

Combination antibiotic therapies using piperacillin (PIPC) were evaluated in 60 episodes of severe infections in 38 neutropenic patients with hematologic malignancies. 1. The overall efficacy rate was 46.7%. Efficacy rates were 30% in patients with pneumonia, 60% in patients with sepsis and 50% in patients with suspected sepsis in which causative organisms were not identified. 2. Eradication rates were 44.4% for Gram-negative bacilli, 50% for Pseudomonas aeruginosa and 22.2% for Gram-positive cocci. 3. Efficacy rates were 33.3% in patients with initial count of neutrophil less than 100/microliters, 60% in patients with those 100 to 500/microliters and 66.7% in patients with those higher than 500/microliters. Initial neutrophil counts correlated well with efficacies of PIPC on severe infection in patients with hematologic malignancies. 4. Mild increases of transaminase were observed in 2 cases. From these results it is concluded that PIPC is one of the most important antibiotics in the treatment of severe infections in neutropenic patients with hematologic malignancies.

Adolescent↗
PubMed1991

Gangliosides administration causes sugar moiety-specific enzymatic changes in brain.

Exogenous gangliosides are known to affect the metabolism when administered to the body. To study the mechanism of this effect three types of gangliosides were administered intraperitoneally to mice and the changes in the enzyme activity of the cerebral tissues studied. The effect of GM2 from bovine brain was characterized by a decrease in the activity of various aminopeptidases, while GD3 from cow's milk caused an increase in the activity of sugar-related enzymes such as sialidase, glucosidase, and fucosidase. GM3 from horse erythrocytes showed intermediate effects between GM2 and GD3. Multivariate analysis showed that the effects of the three gangliosides are clearly separable statistically. These results which demonstrate the sugar moiety-specificity of gangliosides are discussed in relation to the A and B pathways of ganglioside synthesis.

Amino Acid Sequence↗
PubMed1991

[Advances of BRM therapy of malignant brain tumors].

The cooperative study on the beta-interferon (IFN) therapy for glioblastoma and malignant astrocytoma reported the response rate as 14.0%. Continuing study resulted the response rate of 24.0% to low grade astrocytoma and 20.0% to medulloblastoma. Totally, effectiveness of 19.2% to gliomas was confirmed in 120 evaluated cases. A randomized study was conducted on combination therapy with beta-interferon and chemoradiotherapy. The response rate of 41.2% (21/51) in the group treated with IFN, ACNU and Radiation was significantly higher than the rate of 19.6% (10/51) in the group treated with ACNU and radiation only. Application of IFN to a maintenance therapy is also on going. Adoptive immunotherapy has been developed as potential therapeutic method of malignant glioma. Lymphokine activated killer cells (LAK) and Tumor infiltrating lymphocytes (TIL) are put to clinical use. Clinical application of human monoclonal antibody (MAb) CLN-IgG was conducted to recurrent malignant glioma. 131I labeled MAb was administered intratumorously and the specific incorporation was confirmed by gamma-scintigraphy. Concomitant administration of interferon enhanced the efficacy of the therapy. This radio-immunotherapy holds future promise as a new therapeutic approach to gliomas.

Adult↗
PubMed1991

Genomic rearrangement of the c-myc proto-oncogene in non-AIDS-related lymphoma in Japan.

Southern blot analysis was employed to analyze the structural alterations of the c-myc oncogene in genomic DNA derived from tumor specimens of 35 adults with pathologically classified and immunophenotyped non-AIDS-related, non-Hodgkin's lymphoma in Japan. In this study, seven cases (20%), including one peripheral T-cell lymphoma and six B-cell lymphomas of various histological types, were demonstrated to have additional c-myc fragments. An interesting feature is that c-myc rearrangements were found in three out of eight primary gastrointestinal lymphomas. Analyses with several restriction enzymes revealed that the breakpoints in these cases were clustered in a region spanning the first exon, first intron and nearby 5'-flanking sequences of the c-myc gene, suggesting that the alteration of this region may represent an important molecular event in activating the oncogenic potential of the c-myc gene.

Adult↗
PubMed1990

One-step sandwich enzyme immunoassay for soluble human thrombomodulin using monoclonal antibodies.

Six monoclonal antibodies for human thrombomodulin (TM) were prepared. All of them recognized an elastase-digested fragment of TM which contains 6 epidermal growth factor (EGF)-like structural domains. We developed a one-step sandwich enzyme immunoassay for soluble TM by using 2 antibodies; one of them, which inhibited thrombin-binding to TM, was fixed to polystyrene balls, and the other, which did not inhibit the thrombin-binding, but inhibited the protein C-activating cofactor activity of TM, was used as peroxidase-labeled conjugate. The sensitivity of this assay was 1 microgram/l for soluble TM. The level of soluble TM was found to be significantly increased in sera of patients with systemic lupus erythematosus in comparison to the level in sera of healthy subjects.

Adult↗
PubMed1990

Deficiency of kallikrein-like enzyme activities in cerebral tissue of patients with Alzheimer's disease.

We examined the changes in the intracerebral activities, at the time of postmortem autopsy, in patients with Alzheimer's disease. When compared with the control group, the activity of kallikrein-like enzyme was significantly decreased, while prolyl endopeptidase activity increased, in the patients group. Aprotinin inhibited 50% of the activity of the former enzyme at 2 x 10(-7) M. Taken together with the results of a multivariate study, the above findings may indicate that intracerebral kallikrein deficiency plays an important role in the pathogenesis of Alzheimer's disease.

Aged↗
PubMed1990

Loss of constitutional heterozygosity in chromosome 10 in human glioblastoma.

Gene deletion of chromosome 10 in 11 tumor tissues removed from nine patients with malignant glioma (seven glioblastomas and two malignant astrocytomas) was investigated. Loss of heterozygosity was found in four of the seven (57%) cases with glioblastoma, whereas heterozygosity was preserved in two malignant astrocytome cases. One glioblastoma case showed loss of heterozygosity only in the recurring tumor tissue, although heterozygosity was maintained in the initial tumor tissue. The significance of loss of heterozygosity in the growth and recurrence of glioblastoma is discussed.

Adolescent↗