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Biomedical subjects

K Machida

Publications and source records attributed to K Machida.

At least 289 records · Page 16Linked to original sources
PubMed1983

[Clinical efficacy of the liver scintigram--rates of interpretation of physiologically defective activity areas].

Liver scintigrams of 406 cases were interpreted by 11 physicians. The ratios of the interpretation of the physiologically decreased activity areas in the liver scintigrams were 27% in the regions of the porta hepatis, 23% in the gall bladder fossa, 20% in the inferior vena cava, 7% in the renal impression, 2% in the portal vein, 2% in the rib impression and 2% in others. The cases having space occupying lesions showed decreased ratio of the interpretation of the physiologically decreased activity areas, as compared with other groups. Cases of the liver cirrhosis showed decreased ratio in the region of inferior vena cava. Cases using Anger camera demonstrated more increased ratio than cases using a scanner. The 11 physicians could be divided for two groups. One group showed high ratios of the interpretation of the physiologically decreased activity areas, and another group showed very low ratio, because of the different interpretation about the physiologically decreased activity areas in the two groups. In our cases, a very few cases showing decreased activity on the liver image were false positive or false negative for diagnosis of space occupying lesions.

Evaluation Studies as Topic↗
PubMed1983

[Effects of guanabenz on the cardiovascular system, in comparison with clonidine and guanethidine].

Cardiovascular actions of guanabenz, a new antihypertensive agent, were studied in comparison with those of clonidine and guanethidine. Guanabenz, administered intravenously, produced a rise of blood pressure which was followed by a prolonged fall in anesthetized dogs. Guanabenz also decreased the heart rate, inhibited the respiration, and produced an alteration in T wave and a prolongation of PQ or TP interval in the ECG of the dog. Such effects of guanabenz on blood pressure and heart rate were observed in the cat, rabbit and rat, but there was a slight species-difference in the effects. Clonidine, but not guanethidine, produced responses similar to those of guanabenz. The potency of guanabenz to produce hypotension and bradycardia was approximately 1/10 that of clonidine and 10 times higher than that of guanethidine. The depressor effect of guanabenz was not observed in the spinal cats; thus, the blood pressure rose after the administration. When guanabenz was administered intracerebroventricularly or into the nucleus tractus solitarius of rats, the initial pressor response was not produced, and the depressor and bradycardiac responses were observed. Guanabenz, administered intravenously or intra-arterially, produced an inhibition of cardiac functions, decreased the blood flow of common carotid and femoral arteries, and elevated the perfusion-pressure of the hindlimb in the dog. In the isolated rabbit and guinea-pig atria, guanabenz produced negative inotropic and chronotropic effects and attenuated the rate of rise of the action potential. The contractile responses to serotonin and histamine in the isolated rabbit thoracic aorta were noncompetitively inhibited by guanabenz. From these results, it is suggested that the hypotensive and bradycardiac actions of guanabenz are mediated via central actions, as well as those of clonidine. Furthermore, in addition to the central actions, it was found that guanabenz acts directly on cardiovascular tissues and attenuates the responsiveness.

Animals↗
PubMed1981

Lateral mobility of erythrocyte membrane proteins studied by the fluorescence photobleaching recovery technique.

Erythrocyte membrane peripheral and integral proteins have been isolated and purified, and the lateral diffusion of these proteins in a well-defined phospholipid bilayer matrix (dimyristoylphosphatidylcholine) has been studied by fluorescence photobleaching recovery measurements. Our own instrument for the recovery measurements is described and some data for lipid diffusions are compared with those previously reported by other investigators. The peripheral proteins (spectrin and band 4.1) diffuse rapidly on the lipid membrane in its fluid phase. The diffusion constant of approximately 5 x 10(-8) cm2 . s-1 (30 degrees C) was only a little smaller than that for lipid diffusion. The diffusion was greatly slowed down when the host lipid matrix became solid. The integral protein band 3 also diffuses rapidly in the fluid membrane. The diffusion constant of 1.6 x 10(-8) cm2 . s-1 (30 degrees C) was smaller than those for lipids and for the peripheral proteins. The lateral motion is compatible with diffusion of a cylinder with radius 3 nm in a two dimensional matrix with an inner viscosity of 2 poises and an inner thickness of 4 nm. The band 3 lateral motion was restricted by binding of the cytoskeletal component proteins (ankyrin, spectrin, actin, and band 4.1) to the reconstituted membranes. The diffusion constant decreased to half. The results provide a basis for the elucidation of transmembrane control mechanisms in more complex cellular systems.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1981

[Clinical significance of RCT in liver diseases (author's transl)].

Radionuclide Computed Tomography (RCT) was performed in 40 cases with various liver diseases. Indication of RCT was determined by the fact that usual liver scintigrams showed or suspected space-occupying lesion. In diffuse hepatocellular disease, RCT added diagnostic informations in 10 out of 17 cases. In these patients, RCT referred decreased uptake area to morphological change such as prominent porta hepatis, widening of both lobes or lateral seg. and medial seg, of the left lobe, and so on. In cases with liver tumor, RCT demonstrated the liver by axial plane, so one could easily or precisely diagnose the location of the mass. RCT performance requires only 30 min, additionally, and no additional injection. We conclude RCT should be performed to the patients whose liver scintigrams show or suspect space-occupying lesion.

Adult↗
PubMed1980

Effect of bilayer membrane curvature on activity of phosphatidylcholine exchange protein.

Effect of bilayer membrane curvature of substrate phosphatidylcholine and inhibitor phosphatidylserine on the activity of phosphatidylcholine exchange protein has been studied by measuring transfer of spin-labeled phosphatidylcholine between vesicles, vesicles and liposomes, and between liposomes. The transfer rate between vesicles was more than 100 times larger than that between vesicles and liposomes. The transfer rate between liposomes was still smaller than that between vesicles and liposomes and nearly the same as that in the absence of exchange protein. The markedly enhanced exchange with vesicles was ascribed to the asymmetric packing of phospholipid molecules in the outer layer of the highly curved bilayer membrane. The inhibitory effect of phosphatidylserine was also greatly dependent on the membrane curvature. The vesicles with diameter of 17 nm showed more than 20 times larger inhibitory activity than those with diameter of 22 nm. The inhibitory effect of liposomes was very small. The size dependence was ascribed to stronger binding of the exchange protein to membranes with higher curvatures. The protein-mediated transfer from vesicles to spiculated erythrocyte ghosts was about four times faster than that to cup-shaped ghosts. This was ascribed to enhanced transfer to the highly curved spiculated membrane sites rather than greater mobility of phosphatidylcholine in the spiculated ghost membrane.

Androgen-Binding Protein↗