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Biomedical subjects

N Yamada

Publications and source records attributed to N Yamada.

At least 883 records · Page 49Linked to original sources
PubMed1982

Three-dimensional structure of the crystalloid in the microbody of Kloeckera sp.: composite crystal model.

Electron microscopic investigations using the cryosectioning technique, together with electron diffraction, optical diffraction, and computer simulation, were carried out for the determination of the intrinsic structure of the crystalloid in the microbody of Kloeckera sp. The lattice images seen in the cryosections could be changed from one to another by tilting the specimen at an appropriate angle, the images obtained being well consistent with those obtained by computer simulation. The electron diffraction patterns also agreed with those obtained by optical diffraction. The results demonstrated that the crystalloid was composed of two different types of particles, large and small ones, arranged alternately and making up the composite crystal of rock salt structure. Large particles seemed to consist of alcohol oxidase molecules, while the small particles were presumably made up of catalase molecules.

Bacteria↗
PubMed1982

Lipoprotein lipase activity in adipose tissue of streptozotocin-induced diabetic rats.

Lipoprotein lipase activity of epididymal adipose tissue was measured in streptozotocin-induced diabetic rats. Diabetic rats of 3, 10 and 34 days duration were examined. The enzyme activity in adipose tissue of diabetic rats was similar to that of control rats of the same ages, compared on the tissue weight basis. However, since adipose tissue weight was markedly reduced in rats with both acute and chronic diabetes, total enzyme activity in the whole tissue was very low in such animals regardless of the duration of diabetes. We wish to point out that contradictory results on the adipose tissue lipoprotein lipase activity in diabetic rats in the previous reports have arisen depending on differences in the methods chosen to express enzyme activity.

Adipose Tissue↗
PubMed1982

Increase in stenotic resistance following a brief coronary occlusion in the anesthetized open-chest dog.

Changes in the stenotic resistance of a coronary artery following brief coronary occlusion were studied in the anesthetized open-chest dog. A critical coronary stenosis was constructed by tying a thick string around the circumflex coronary artery (LCx) near its origin. The LCx was occluded for 5, 10, 15, 20 and 30 seconds with and without coronary stenosis then the reactive hyperemia was observed. In the absence of the stenosis, resistance of the segment of the large coronary artery remained unchanged during the reactive hyperemia independent of the duration of occlusion. In the presence of the stenosis, however, stenotic resistance increased for a certain time after the release of occlusion. This increased resistance lasted longer with more severe stenosis and with longer duration of coronary occlusion. These results suggest that stenotic resistance can increase dynamically, and that the duration of increased resistance may reflect the severity of the stenosis.

Anesthesia↗
PubMed1982

Quantitative autoradiographic measurements of blood-brain barrier permeability in the rat glioma model.

Quantitative autoradiographic technique was applied in measuring blood-brain barrier (BBB) permeability of autochthonous gliomas in rats. In small tumors (less than 2 mm in diameter), no increase in BBB permeability was noted. As the tumor grew and neovascularization occurred, BBB permeability increased in the center of the tumor, and it was suggested that the BBB was partly disrupted in the neovascularized vessels. In the fully grown tumors, BBB permeability was markedly increased in the viable part of the tumor to levels similar to the choroid plexus. Yet, the BBB was partly preserved at the periphery of the tumor and in the brain adjacent to the tumor. The heterogeneity of the BBB phenomenon according to the stage of tumor growth may be a major obstacle for uptake of chemotherapeutic drugs that do not cross the BBB easily.

Animals↗
PubMed1982

[In vitro and in vivo antimicrobial activities of cefmetazole against Bacteroides fragilis].

Cefmetazole was investigated on stability to beta-lactamases produced by Bacteroides fragilis and on therapeutic effects in mice infected with B. fragilis. 1. Cefmetazole, like other cephamycins, was found extremely stable to beta-lactamases obtained from B. fragilis. 2. Cefmetazole showed good antimicrobial activities to 50 strains of B. fragilis and extremely high stability to their beta-lactamases. 3. Cefmetazole showed an excellent protecting effect to infections due to beta-lactamase producing B. fragilis. 4. Cefmetazole exhibited an excellent chemotherapeutic effect against polymicrobial infections in mice due to E. coli (beta-lactamase -)and B. fragilis (beta-lactamase +).

Animals↗
PubMed1982

[Local cerebral glucose utilization in the ethylnitrosourea-induced rat glioma].

Local cerebral glucose utilization (LCGU) of anesthetized rats bearing ethylnitrosourea (ENU)-induced gliomas was studied with 14C-deoxyglucose autoradiography. Single subcutaneous injection of ethylnitrosourea (50 mg/kg) was made to the newborn rats, and animals were used for experiment at 150 to 300 days after birth. Under ketamine anesthesia, 14C-deoxyglucose was injected through a venous catheter, and timed arterial sampling was made. Brains were removed at 45 min after injection, and prepared for macro-autoradiography. LCGU values were measured by the equation developed by Sokoloff et al. In the microtumors (less than 2 mm in diameter), mean LCGU value was 30 mumol/100 g/min, which was significantly (p less than 0.01) lower than mean value of normal cortex (63 mumol/100 g/min). In the macrotumors (greater than 2 mm in diameter). LCGU values in the tumor were separated to high part (mean; 49 mumol/100 g/min) and low part (mean; 38 mumol/100 g/min), which were still lower than mean cortical value and higher than mean white matter value (corpus callosum; 26 mumol/100 g/min). No LCGU changes were noted in the brain tissue adjacent to the microtumors. Whereas, macrotumor significantly reduced LCGU in the adjacent cortex. The present data may indicate that glucose metabolism of the ENU induced glioma and edematous peritumoral brain tissue is lower than that of normal cortex.

Animals↗
PubMed1982

Familial plasma lecithin: cholesterol acyltransferase deficiency. A new family with partial LCAT activity.

A 43-year-old woman and her 47-year-old brother were studied because of corneal opacity. They showed a marked decrease in plasma high density lipoproteins (HDL) and a decrease in the ester ratio of plasma total cholesterol. Discoidal particles were found in the HDL2 fraction (d 1.063-1.125). A marked heterogeneity of low density lipoproteins was disclosed in both patients by electron microscopy. Apoprotein analysis revealed an increase in apo E and a decrease in apo A-I and A-II in both patients. These abnormalities were similar to the data reported in other cases with hereditary lecithin : cholesterol acyltransferase (LCAT) deficiency. However, several interesting dissimilarities have been disclosed as compared with the previously reported cases. Neither patient had proteinuria, and their kidney functions were within the normal limits. The ester ratios of plasma cholesterol of both patients were the highest among the cases reported thus far. Their plasma LCAT activities were 14.4 and 15% of the normal mean values determined by Glomset-Wright's common-substrate method. The enzyme activities determined by Stokke-Norum's self-substrate method were 40.2 and 29% respectively. These results may indicate that this inherited disorder is not characterized by absence of plasma LCAT or presence of inhibitory factors in plasma, but by the presence of partially inactive LCAT in patients' plasma.

Adolescent↗
PubMed1982

Analog computer simulation of maternal - fetal transfer of cefazolin.

Cefazolin concentration-time data after normal vaginal delivery were obtained for maternal serum, placenta, umbilical cord blood, and amniotic fluid. After normalizing of the data, concentration-time profiles were generated for each sampling compartment. A pharmacokinetic model for analog computer simulation was developed. Multiple dosing simulation suggests a higher accumulation of cefazolin in fetal than in maternal blood, and a slow accumulation in amniotic fluid, which acts as a depot or storage. The drug is transferred diaplacentally; paraplacental transfer seems to be absent for cefazolin.

Amniotic Fluid↗
PubMed1982

[Clinical study of phase analysis by RI multigated method].

Phase analysis using RI multigated method was performed in 32 patients with various conditions including right and left bundle branch blocks (RBBB and LBBB), myocardial infarction, WPW syndrome, QT prolongation syndrome, atrioventricular (A-V) dissociation, valvular heart disease, and others. Pixel numbers were plotted into the histogram regarding the one cardiac cycle as 360 degrees. Standard deviation (S.D.) of a phase was calculated from the histogram in order to quantify asynchrony of the ventricles. Results were as follows: 1. Phase analysis was useful as a parameter of asynchrony. 2. There was a close negative correlation between left ventricular ejection fraction (LVEF) and S.D. of a phase. (r = -0.86, n = 32, p less than 0.001) 3. A marked time lag was observed in the infarcted area, and its value was mild in RBBB and LBBB. 4. A time lag between right and left ventricles was diminished or slightly reversed in the cases of RBBB with left anterior hemiblock compared to the cases of lone RBBB. 5. No significant changes were observed in other heart diseases with phase analysis.

Arrhythmias, Cardiac↗