Search PubMed⌕ Search

Biomedical subjects

M Kuroda

Publications and source records attributed to M Kuroda.

At least 541 records · Page 30Linked to original sources
PubMed1977

Connectin, an elastic protein of muscle. Its abundance in cardiac myofibrils.

Pure myofibrils were isolated from bovine heart by sucrose layer ultracentrifugation. Cardiac myofibrils thus prepared contained more protein as insoluble stroma than skeletal muscle. The insoluble stroma largely consisted of connectin, an elastic protein of muscle. The connectin content in cardiac myofibrils was about 18% of the total myofibrillar protein and was three times that in skeletal myofibrils. In view of the role of connectin as an elastic component of muscle, the abundance of connectin in cardiac myofibrils may be responsible for keeping myofibrils short at rest. This would account for the more effective tension generation in cardiac muscle on passive stretching due to blood inflow (Stirling's law).

Amino Acids↗
PubMed1976

Inhibition of in vitro cholesterol synthesis by fatty acids.

Inhibitory effect of 44 species of fatty acids on cholesterol synthesis has been examined with a rat liver enzyme system. In the case of saturated fatty acids, the inhibitory activity increased with chain length to a maximum at 11 to 14 carbons, after which activity decreased rapidly. The inhibition increased with the degree of unsaturation of fatty acids. Introduction of a hydroxy group at the alpha-position of fatty acids abolished the inhibition, while the inhibition was enhanced by the presence of a hydroxy group located in an intermediate position of the chain. Branched chain fatty acids having a methyl group at the terminal showed much higher activity than the corresponding saturated straight chain fatty acids with the same number of carbons. With respect to the mechanism for inhibition, tridecanoate was found to inhibit acetoacetyl-CoA thiolase specifically without affecting the other reaction steps in the cholesterol synthetic pathway. The highly unsaturated fatty acids, arachidonate and linoleate, were specific inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA synthase. On the other hand, ricinoleate (hydroxy acid) and phytanate (branched-chain acid) diminished the conversion of mevalonate to sterols by inhibiting a step or steps between squalene and lanosterol.

Acetates↗
PubMed1976

Repolymerizability of native thin filaments of rabbit skeletal muscle.

The repolymerizability of native thin filaments of rabbit skeletal muscle was examined under various conditions. The native thin filaments usually did not repolymerize after depolymerization, but it was found that the process was only inhibited at the nucleation step of the G-F transformation of actin. The inhibited state was released by the addition of sonicated F-actin fragments as seeds or by direct sonication. An attempt to isolate the actin moiety from native thin filaments showed that the isolated actin was very similar to Straub-type G-actin2 in its polymerizability. However, a protein factor which inhibits the polymerization of G-actin was obtained by ammonium sulfate fractionation of the depolymerized native thin filaments. Thus, the apparent lack of repolymerizability of native thin filaments was found to be due to the action of this factor on the polymerization of G-actin.

Actins↗
PubMed1976

Gamma-Actinin, a new regulatory protein from rabbit skeletal muscle. I. Purification and characterization.

A new regulatory protein which we have designated as gamma-actinin has been isolated from native thin filaments of rabbit skeletal muscle. Depolymerized native thin filaments were fractionated by salting out with ammonium sulfate, and the precipitates obtained at 40--60% ammonium sulfate saturation were further subjected to DEAE-Sephadex and Sephadex G-200 column chromatography. The purified gamma-actinin was shown to have a chain weight of 35,000 daltons and had a strong inhibitory action on the polymerization of G-actin. The results of amino acid analysis indicated a unique amino acid composition of gamma-actinin as compared with other structural proteins of muscle. Non-polar and neutral amino acid residues were abundant. One cysteine residue was contained per one molecule of gamma-actinin and played a critical role in the maintenance of the inhibitory activity. Pelleting of gamma-actinin with F-actin showed that gamma-actinin binds to F-action.

Actinin↗
PubMed1976

Gamma-Actinin, a new regulatory protein from rabbit skeletal muscle. II. Action on actin.

The interaction of gamma-actinin and actin was investigated under various conditions. It has been shown that gamma-actinin affects the G-F transformation of actin, causing an increase in the number of actin monomers required to form a nucleus in the initial step of polymerization. Sonicated fragments of F-actin and heavy meromyosin caused the immediate polymerization of actin under the influence of gamma-actinin. Therefore, it can be concluded that gamma-actinin inhibits the nucleation step of G-F transformation. Actin filaments which were formed in the presence of gamma-actinin (F-actin) were shown to possess certain characteristic properties when compared with control F-actin. These were as follows: F-actin solution had a high critical concentration; F-actin showed a high rate of depolymerization; the flow birefringence of F-actin decreased with time upon incubation in the absence of free ATP; finally, F-actin was demonstrated to have ATP-splitting activity. These dynamic features of F-actin were accounted for in terms of an increase in the rate constant of depolymerization in F-actin under the influence of gamma-actinin.

Actinin↗
PubMed1976

Occurrence of renovascular hypertension in two sisters.

Renovascular hypertension in two sisters, aged 22 and 20, respectively, has been described. Renal artery stenoses were observed unilaterally in the elder patient and bilaterally in the younger one. In both patients, the functional significance of unilateral stenosis of the renal artery was documented by the renal vein renin ratio between the affected side and the contralateral or less affected side. High blood pressure and elevated plasma renin activity have been normalized with a unilateral revascularization in the elder patient, and with the treatment of propranolol in the younger one. The histological examination of the stenotic renal artery in the elder patient showed a finding comparable to the perimedial fibroplasia in Harrison and McCormack's classification of idiopathic fibromuscular stenosis.

Adult↗
PubMed1976

[Comparative results of cephacetrile with cefazolin in complicated urinary tract infections by means of double-blind trials (author's transl)].

In order to elucidate the usefulness of cephacetrile (CEC), comparative trials with cefazolin (CEZ) were carried out in the patients with complicated infections of the urinary tract, and the following results were obtained: 1. There were no statistically significant differences or tendencies observed between the groups given CEC and CEZ in either of the global effects, bacteriological effects, rate of superinfection, relapse, relapse with bacterial alternation, drug usefulness, rate of improvements in symptoms and findings in all the cases. 2. According to a result of stratified analyses, there were statistically significant differences observed, showing more inferior results of CEC than CEZ in either stratum of "below 50" in the age, "acute" in the disease phase, "infections of the upper urinary tract" in the disease pattern, and "E. coli including mixed infections with gram-positive organisms" in the pathogenic strains. However, it should be taken into consideration that certain background factors influence greatly in the effects and there were some problems on deviated backgrounds in these strata. On the other hand, CEC displayed better bacteriological effects than those of CEZ in higher stratum of "chronic" in the disease phase and "Klebsiella, Proteus, Citrobacter, Enterobacter including mixed infections" in the pathogenic strains, and statistically significant differences were not observed. 3. In consequence of bacteriological studies, CEC showed stronger resistance than CEZ against beta-lactamase produced in all the strains of gram-negative bacilli. Particularly there were significant differences or tendencies observed in those of Proteus, Cirtobacter, and Enterobacter, and at the same time there were great differences in the activity of beta-lactamase between CEC and CEZ as the substrate. 4. In correlation of the MIC and effects, CEC showed weaker actions than CEZ against susceptible organisms, but slightly stronger actions against moderately or highly resistant strains. A study of the relationship between the MIC of pathogenic strains, beta-lactamase, and bacteriological effects, showed possibilities that even the high activity of beta-lactamase results in remarkable effects in susceptible strains and the drugs with stronger resistance against beta-lactamase given better results in moderately or highly resistant organisms. 5. The incidence rate of adverse reactions was 2 out of 51 cases in the CEC group (3.9%) and 3 out of 50 cases in the CEZ group (6.0%), showing no significant difference, and those symptoms were similar. In conclusion, when the usefulness of CEC in complicated infections of the urinary tract is compared with that of CEZ, the former is said to be equal to the latter without significant difference as a whole...

Adult↗