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Biomedical subjects

M Masuda

Publications and source records attributed to M Masuda.

At least 541 records · Page 30Linked to original sources
PubMed1985

[Laboratory and clinical studies on aztreonam in the pediatric field].

Laboratory and clinical studies were performed as follows on aztreonam (AZT), a new monobactam antibiotic. Pharmacokinetics Serum concentrations of AZT were measured in 1 patient given 20 mg/kg by intravenous bolus injection. The peak concentration was 100 micrograms/ml at 15 minutes, and T 1/2 was 1.85 hours. Clinical efficacy AZT was administrated intravenously to 10 patients in doses of 59.2-170.7 mg/kg (average 76.1 mg/kg) t.i.d. for 3-8 days (average 5.3 days); 5 with pneumonia, 1 with bronchitis, 1 with lymphadenitis, 1 with sepsis (suspected) and 2 with urinary tract infections. The overall efficacy rate was 80%, i.e., efficacy was excellent in 5, good in 3, fair in 1 and poor in 1. Bacteriological efficacy was excellent, i.e., 4 of 4 Gram-negative strains disappeared. Any clinical side effects and laboratory abnormalities were not observed. The above results suggest that AZT is a useful antibiotic for treating pediatric bacterial infections, especially due to Gram-negative bacteria.

Age Factors↗
PubMed1984

The periodic loss of metabolically unstable DNA during replication of chromosomal DNA of CHO cells.

The fate of 3H-thymidine incorporated into newly synthesized DNA of CHO cells was analyzed by either the estimation of the incorporated radioactivity per cell or sedimentation in alkaline sucrose gradient. Under conditions in which DNA synthesis proceeded continuously, the incorporated radioactivity was periodically lost and regained during a 90 min chase, corresponding to a cyclic change in the sedimentation profiles. When DNA synthesis was inhibited by hydroxyurea no cyclic change of the incorporated radioactivity was observed. The cyclic changes were regarded as the result of an actual metabolic change in 3H-labelled DNA probably joining to one of the newly formed sister strands of DNA and the loss of radioactivity seems to require active continued DNA synthesis.

Animals↗
PubMed1984

Dependence of conduction velocity on spike interval during voluntary muscular contraction in human motor units.

The dependence of the conduction velocity of the action potential on the spike interval from a preceding potential was studied using human single motor units during voluntary muscle contraction. The spike potential was recorded from the surface of the skin overlying M. vastus medialis by use of surface electrodes (diameter 5 mm). The results were as follows: Conduction velocity increased with a decrease in spike interval. The relation between conduction velocity and spike interval can be expressed as log v = kt + a, where v is conduction velocity (m X s-1), t is spike interval (ms) and k and a are constants. All data can be expressed by the above formula with a highly significant correlation. After arterial occlusion, there was little or no relation between conduction velocity and spike interval. This lack of correlation between these parameters was not restored to the initial correlation within a period of 15 min. Effects similar to occlusion could be seen in the result of prolonged isometric contraction. However the lack of correlation between these parameters was restored to the initial correlation within a 15 min recovery period. At low muscular temperature, the relation could not be described by a logarithmic regression. As the spike interval became shorter, the conduction velocity decreased. After cessation of cooling, the relation was restored to the initial correlation within 30 min. The mechanisms of these changes are still uncertain but some possible factors can be considered, for example, composition of the extracellular fluid, pH, temperature and permiability of the excitable membranes of the muscle.

Action Potentials↗
PubMed1984

Intestinal tumors in rats induced by mutagens from glutamic acid pyrolysate.

2-Amino-6-methyldipyrido[1,2-a:3',3'-d]imidazole (Glu-P-1) and 2-amino-dipyrido[1,2-a:3',2'-d]imidazole (Glu-P-2), which were isolated from a glutamic acid pyrolysate, were proved to be multipotent carcinogens in rats, inducing tumors of the liver, intestine, ear duct and clitoral gland when administered orally to F344 rats. Intestinal tumors were produced for the first time in a series of experiments with heterocyclic amines. Details of the morphologic features of the intestinal tumors induced in F344 rats by Glu-P-1 and Glu-P-2 are described. There were no marked differences between the tumors induced by Glu-P-1 and Glu-P-2. Grossly, the tumors of the small intestine were recognized as papillary, polypoid or umbilicated masses. The most common tumors in the large intestine showed polypoid growth with a short stalk. Histologically, the intestinal tumors were classified as adenomas, adenocarcinomas, and mucinous carcinomas. Several adenocarcinomas were found adjacent to adenomas. Mucinous carcinomas developed only in the small intestine. Most of these tumors showed endophytic growth with extensive mucus production. Tumor tissue from the small intestine transplanted into the subcutis of the flank grew into tumors within 3 months.

Adenocarcinoma↗
PubMed1984

Strand dissociation and cooperative melting of double-stranded DNAs detected by denaturant gradient gel electrophoresis.

Precise analysis using the denaturant gradient gel electrophoresis which was devised by Fischer and Lerman (Cell 16, 191-200, 1979), was found to present specific patterns of fine structures for double stranded DNA fragments. These seem to be a mobility change of DNA fragments caused by specific denaturation processes. The effect of denaturants on DNA melting was ascertained to be similar to the effect of temperature. The observed patterns, in comparison with the melting processes of DNAs theoretically obtained, were closely related to DNA meltings and strand dissociations. A number of electrophoretic mobility transitions showed the retardation correspondent to each of the cooperative meltings. Strand dissociations occurred under the conditions theoretically predicted. The degree of retardation in electrophoresis for DNA fragments seemed to correspond to the size of melted regions. Methods presented here were proved to have advantages over the conventional ones for the study of DNA stability maps.

Computers↗
PubMed1984

Trichilemmal keratinization in seborrheic keratoses.

In 33 of 112 seborrheic keratoses reviewed histologically, a keratinization process was observed, which was identical with or showed marked similarity to, trichilemmal keratinization (TK). This type of keratinization took place more frequently in lesions which were pruritic and in those located on the extremities. Histologically, the change was observed in the bottoms of pseudocysts and crypts, in areas showing evidence of inflammation, such as exocytosis, spongiosis and squamous eddy or whorl formation. No relationship was found between the presence of TK or TK-like keratinization and the various histologic types of seborrheic keratoses. It is concluded that a process which can not be distinguished from TK microscopically may occur frequently in seborrheic keratoses as a result of inflammation.

Dermatitis, Seborrheic↗
PubMed1984

7 alpha-Dehydroxylation of bile acids by resting cells of a Eubacterium lentum-like intestinal anaerobe, strain c-25.

7 alpha-Dehydroxylation of cholic acid and chenodeoxycholic acid by whole cells of strain c-25, a Eubacterium lentum-like intestinal anaerobe, was studied. 7 alpha-Dehydroxylase activity was observed only in whole cells grown in the presence of the primary bile acid (cholic acid or chenodeoxycholic acid). Chenodeoxycholic acid was twice as effective as cholic acid as an inducer. Although cells grown in the presence of chenodeoxycholic acid had no significant substrate specificity for the two primary bile acids, cells grown in the presence of cholic acid showed two times greater activity against cholic acid than chenodeoxycholic acid. Exposure of cell suspensions to atmospheric oxygen resulted in little loss of the 7 alpha-dehydroxylase activity. The induced enzyme had an optimal pH range of 7.3 to 7.7. Although adding flavin mononucleotide to the growth medium significantly increased the 7 alpha-dehydroxylation of bile acids without an increase in cell growth, inhibition of the enzyme activity was observed in the resting cell system when flavin mononucleotide was included in the reaction mixture.

Animals↗
PubMed1984

Induction of cancers in the intestine, liver and various other organs of rats by feeding mutagens from glutamic acid pyrolysate.

The mutagenic compounds 2-amino-6-methyldipyrido[1,2-alpha:3',2'-d]imidazole (Glu-P-1) and 2- aminodipyrido [1,2-alpha: 3',2'-d]imidazole (Glu-P-2), which were isolated from a glutamic acid pyrolysate and are potent carcinogens in the liver and brown adipose tissue of mice, were found to be multipotent carcinogens in rats. These compounds were each given to F344 rats of both sexes at a concentration of 500 ppm in pellet diet for up to 24 months. Glu-P-1 induced tumors in the colon, small intestine, liver, Zymbal gland, clitoral gland and brain. Glu-P-2 produced tumors in the same sites at slightly lower incidence. The multipotent carcinogenicities of Glu-P-1 and Glu-P-2 in rats and mice suggest that heterocyclic amines present in cooked food may be important in the development of human cancer.

Adenocarcinoma↗
PubMed1984

Demonstration of carcinogenicity in F344 rats of 2-amino-3-methyl-imidazo[4,5-f]quinoline from broiled sardine, fried beef and beef extract.

The mutagenic compound 2-amino-3-methylimidazo[4,5-f]quinoline, originally isolated from broiled sardines and also present in cooked beef and beef extract, is being tested for carcinogenicity in F344 rats of both sexes. High incidences of tumors of the Zymbal gland, colon, small intestine and liver in males have been observed in the first 300 days of the experiment.

Adenocarcinoma↗
PubMed1984

[Role of taurine in neutrophil function].

The influence of taurine on neutrophil phagocytic and bactericidal capacities and lysosomal enzyme-releasing ability was evaluated in the present study using neutrophils obtained from casein-elicited rat peritoneal exudates. Taurine was dissolved in drinking water at a concentration of 0.3%, and the solution was given to rats for 1-21 days (460 mg/kg/day). Taurine concentration in the serum increased with the term of its administration, while in the neutrophils, it increased significantly after administration for 1 or 3 days. When administered for 7 or 10 days, however, no difference was noted from the control group, but then the concentration remarkably increased after 21 days of administration. The bactericidal capacity of the neutrophils against Escherichia coli was strengthened as their concentration of taurine increased; phagocytic capacity was also strengthened. The release of myeloperoxidase following phagocytosis of yeasts increased with administration, while the release of beta-glucuronidase, lysozyme and lactate dehydrogenase, which are induced by N-formylmethionyl-leucyl-phenylalanine, were inhibited. The hypotonic hemolysis of erythrocytes was also inhibited. Taurine decreased the fluorescence depolarization of diphenylhexatriene, indicating an increase in membrane fluidity. These results suggested that taurine strengthens both phagocytic and bactericidal capacities of neutrophils by increasing the fluidity of neutrophil membrane and membrane stability and thus plays an important role in the mechanism of host defense.

Animals↗