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Biomedical subjects

K Mabuchi

Publications and source records attributed to K Mabuchi.

At least 145 records · Page 8Linked to original sources
PubMed1983

Boundary lubricating property of synovial fluid on artificial material and lubrication of artificial joints.

Boundary lubricating property of the synovial fluid on artificial materials was investigated by using a pendulum-type friction tester. The coefficient of friction between metal and metal with synovial fluid as a lubricant ranged from 0.19 to 0.30. Those between metal and plastic in the same condition ranged from 0.26 to 0.43. It is concluded from the above data that synovial fluid is a poor lubricant for artificial materials. The coefficient of friction of a metal on plastic prosthesis was approximately five times better than that of a metal on metal prosthesis in the pendulum experiments using synovial fluid as a lubricant.

Adult↗
PubMed1982

Assessment of hospital performance by use of death rates. A recent case history.

This article discusses an analytical approach for integrating hospital death rates. A study of patient mortality in four hospitals in a large metropolitan areas demonstrates the principles underlying this approach. One hospital, which experienced an annual crude death rate almost twice that of the other three, was suspected of providing an inferior quality of care. Case-mix differences among the hospitals introduced a serious bias, however, and were later taken into account. The patients' primary diagnosis was found to be the most important case-mix variable, with a potential for biasing death rate comparisons. After readjustment for case mix, the maximum difference in death rates among the four hospitals was reduced from 19 to four deaths per 1,000 patients. Further analysis of diagnosis-specific mortality supported the thesis that the observed mortality excess was largely attributable to patient referral patterns in the community.

Adolescent↗
PubMed1982

Type IIB to IIA fiber transformation in intermittently stimulated rabbit muscles.

Long-term intermittent stimulation (10 Hz, 8 h/day, 7 wk) of the fast-twitch tibialis anterior results in a complete transformation of type IIB fibers to type IIA fibers. This is shown by the histochemical ATPase reaction and by a decrease in Ca2+-uptake ability by the sarcoplasmic reticulum. Furthermore, as shown by studies on bulk myosin and on single fibers, the LC1-to-LC3 light chain ratio is increased on sodium dodecylsulfate gel electrophoretograms, and there are changes in the myosin isozyme pattern manifested on pyrophosphate gels under nondissociating conditions. Thus the staining intensity of the slower moving putative LC1 homodimer band increases, and there is a difference in migration velocity between stimulated and unstimulated isozymes suggesting a possible difference in the heavy chain. This study underlines the importance of the stimulation schedule in determining whether a fast-to-slow transformation or a shift in subtype takes place.

Adenosine Triphosphatases↗
PubMed1980

Organization of unc gene cluster of Escherichia coli coding for proton-translocating ATPase of oxidative phosphorylation.

The proton-translocating ATPase (F1-F0) of oxidative phosphorylation (ATP phosphohydrolase, EC 3.6.1.3) is coded for by a set of structural genes comprising the unc operon in Escherichia coli. We have analyzed several new transducing phages and plasmids carrying various lengths of the DNA segments of the unc operon by complementation assay using 14 new unc- mutants and representatives of previously described strains which were made available to us. Transducing phages carrying parts of the unc gene cluster were isolated: lambda uncA-9 and lambda glmS phages converted only some of the unc- mutants to the Unc+, as determined by complementation assays. A new hybrid plasmid (pMCR533) carrying part of the unc operon was constructed by inserting the HindIII fragment of lambda asn-5 DNA (a phage carrying the entire unc operon) into the unique HindIII site of pBR322. This plasmid transformed eight unc- strains to Unc+, including uncB402 and uncA401, but did not complement uncD11 or four other strains. Two minichromosomes which carry the E. coli replication origin were also tested: plasmid pNH05 transformed the uncB402 but not the uncA401 strain to Unc+, whereas plasmid pMCF1 transformed none of the mutants tested. Analysis of the DNAs from these transducing phages and plasmids with restriction endonucleases suggested that all of the structural genes for the F1-F0 complex are localized within a DNA segment of approximately 4.5 megadaltons containing two EcoRI sites. The approximate locations of the unc- mutations were mapped on this DNA segment.

Adenosine Triphosphatases↗
PubMed1978

Use of type-specific antimyosins to demonstrate the transformation of individual fibers in chronically stimulated rabbit fast muscles.

Continuous stimulation of a rabbit fast muscle at 10 Hz changes its physiological and biochemical parameters to those of a slow muscle. These transformations include the replacement of myosin of one type by myosin of another type. Two hypotheses could explain the cellular basis of these changes. First, if fibers were permanently programmed to be fast or slow, but not both, a change from one muscle type to another would involve atrophy of one fiber type accompanied by de novo appearance of the other type. Alternatively, preexisting muscle fibers could be changing from the expression of one set of genes to the expression of another. Fluorescein-labeled antibodies against fast (AF) and slow (AS) muscle myosins of rabbits have been prepared by procedures originally applied to chicken muscle. In the unstimulated fast peroneus longus muscle, most fibers stained only with AF; a small percentage stained only with AS; and no fibers stained with both antibodies. In stimulated muscles, most fibers stained with both AF and AS; with increasing time of stimulation, there was a progressive decrease in staining intensity with AF and a progressive increase in staining intensity with AS within the same fibers. These results are consistent with a theory that individual preexisting muscle fibers can actually switch from the synthesis of fast myosin to the synthesis of slow myosin.

Adenosine Triphosphatases↗