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Biomedical subjects

K Ohashi

Publications and source records attributed to K Ohashi.

At least 577 records · Page 32Linked to original sources
PubMed1983

Activation of pyridoxamine 5'-phosphate oxidase by aliphatic primary amine.

The reason for observed variable activities of yeast pyridoxaminephosphate oxidase (EC 1.4.3.5; deaminating) was studied. In the presence of an aliphatic primary amine, the pyridoxamine 5'-phosphate oxidase activity was elevated up to 5-fold, whereas pyridoxine 5'-phosphate oxidase was unchanged. Activation resulted from an enhanced Vmax with an almost constant Km. Polyamines (spermine greater than spermidine greater than putrescine) were excellent activators. On the contrary, oxidation of pyridoxine 5'-phosphate or synthetic N-(5'-phospho-4-pyridoxyl)-amino acid was not activated so much. However, a decrease in Km was observed with the increase in the putrescine concentrations.

Amines↗
PubMed1982

Localization of Z-protein in isolated Z-disk sheets of chicken leg muscle.

Immunoblotting studies with antisera against Z-protein, desmin, and alpha-actinin showed that Z-protein is clearly distinguishable from desmin and alpha-actinin. Z-protein is not a proteolytic product of another protein but is an intrinsic component of chicken breast muscle myofibrils. In these experiments, an SDS extract of intact muscle was first electrophoresed in a polyacrylamide gel, and then proteins were transferred to a nitrocellulose paper sheet. Detection of each protein on the sheet was made possible by the application of the indirect immunofluorescence technique with the respective antiserum. Immunofluorescence microscope studies using these antisera revealed that Z-protein has the same distribution as alpha-actinin in isolated Z-disk sheets. Anti-Z-protein antiserum and anti-alpha-actinin antiserum stained the interior of Z-disks. On the other hand, antiserum against desmin stained the periphery of Z-disks in isolated Z-disk sheets.

Actinin↗
PubMed1982

Ototoxicity of the anticancer drug cisplatin. An experimental study.

Cisplatin was administered to guinea pigs. Hearing function was tested using ABR, and morphological studies were conducted by scanning and transmission electron microscopy. The following findings were made. (1) The susceptibility to cochlear damage by cisplatin was dose dependent. (2) At the same dose, damage was most severe in the lower turns, particularly in the second turn. This tallies with the high tone loss. (3) Mainly the outer hair cells are the site of the damage and the inner hair cells are rarely damaged. (4) The first row of the outer hair cells tend to be more severely damaged. (5) Variation of the stria vascularis was moderate compared with the damage to the organ of Corti. (6) A tendency of recovery was observed in ABR in some animals after they were given 2 mg/kg/day cisplatin intramuscularly consecutively for 8 days.

Animals↗
PubMed1981

Connectin, an elastic protein of muscle. Identification of "titin" with connectin.

When whole muscle fibers or myofibrils of rabbit and chicken skeletal muscles are directly solubilized in hot SDS solution, a very high molecular protein called titin can be isolated by gel filtration (Wang et al. 1979). Connectin, an elastic protein of muscle (Maruyama et al. 1977), can be isolated by a similar method from thoroughly extracted muscle residues. Studies of electrophoretic mobility on 2-3% polyacrylamide gel electrophoresis, amino acid composition, and localization in myofibrils determined by the indirect immunofluorescence technique showed that titin and connectin are identical. Connectin was found to be unstable in SDS solution on storage for a few days at room temperature; the doublet band of connectin on SDS gel electrophoresis became diffuse and eventually disappeared. Connectin was concentrated around the A-I junction region of a myofibril, although it was present in an entire sarcomere except for the Z lines. On removal of myosin, the A-I junction was still fluorescent, when treated with fluorescent antibody against connectin. In the KI-extracted myofibril, materials accumulated on both sides of the Z lines were strongly stained, and there were fluorescent filaments between the neighboring Z lines, but the Z lines were not stained at all.

Animals↗
PubMed1981

Connectin, an elastic protein of muscle. Effects of proteolytic enzymes in situ.

The effects of various proteolytic enzymes on the high molecular weight protein (connectin) present in a direct sodium dodecyl sulfate extract of myofibrils from chicken breast muscle were studied in detail. To keep the high molecular weight proteins intact, myofibrils had to be prepared in the presence of EGTA. Trypsin, chymotrypsin, papain, and nagarse readily hydrolyzed connectin (doublet band of titin) and the band 3 protein (N2-line protein). Pepsin did not attack connectin, but digested the band 3 protein and myosin. Calcium-activated neutral proteinase hydrolyzed the band 3 protein, leaving connectin intact. On the other hand, serine protease digested connectin but not the band 3 protein.

Animals↗
PubMed1981

A new 220,000 dalton protein located in the Z lines of vertebrate skeletal muscle.

A new protein with a chain weight of approximately 220,000 was isolated from 0.6 M KI extracts of I-Z-I brushes of rabbit and chicken skeletal muscles, using (NH4)2SO4 precipitation and three column chromatographic procedures in succession. It was only possible to separate the high molecular weight protein from actin and alpha-actinin in the presence of 6 M urea or 0.1% sodium dodecyl sulfate (SDS). The purified protein migrated as a single band on SDS gel electrophoresis. The amino acid composition of the 220,000 dalton protein was distinct from any known proteins found in myofibrils, e.g., alpha-actinin and actin binding protein (ABP; filamin). An indirect immunofluorescence technique revealed that the new protein was exclusively located in the Z lines of myofibrils of chicken breast muscle. There is, however, a possibility that the 220,000 dalton protein is identical with synemin recently isolated from chicken gizzard (Granger, B.L. and Lazarides, E. (1980) Cell 22, 727).

Amino Acids↗
PubMed1981

Observations on the clinical pharmacology and plasma concentrations of diacetolol, the major human metabolite of acebutolol.

1 The pharmacological effects and plasma levels of diacetolol, the major human metabolite of acebutolol, were measured in a double-blind, balanced study in which five healthy men received single oral doses of diacetolol 100, 200, 400 and 800 mg, or placebo, at weekly intervals. 2 Resting and exercise heart rate (HR), forced expiratory volume in 1 second (FEV1), resting and exercise peak expiratory flow rate (PEFR), and plasma concentrations of diacetolol were determined at 0, 2, 4, 6, 8 and 24 h after each treatment. 3 Diacetolol caused a slight dose-related reduction in resting HR and a substantial dose-related reduction in exercise HR. AT the same time it was found that diacetolol had no significant effects on FEV1 and resting and exercise PEFR. 4 Mean highest observed plasma concentrations (ng/ml) of diacetolol were 177 at a mean of 4.4 h after the 100 mg dose, 243 at 4.0 h after the 200 mg dose, 807 at 5.2 h after the 400 mg dose, and 1,306 at 4.4 h after the 800 mg dose. 5 Using the mean data, there was a strong correlation (r = 0.90) between % reduction in exercise HR and the logarithm of the plasma concentration of diacetolol. 6 Diacetolol exhibits marked cardiac beta-adrenoceptor blocking activity in man which is still evident 24 h after the administration of the higher doses of the drug. No adverse effects on pulmonary function could be detected.

Acebutolol↗
PubMed1980

A novel purification and some properties of rat liver mitochondrial choline dehydrogenase.

Choline dehydrogenase (choline:(acceptor) oxidoreductase, EC 1.1.99.1) was purified from rat liver mitochondria. An approx. 240-fold purification was achieved by chemically modified enzyme with 5,5'-dithiobis(2-nitrobenzoic acid) through columns of DEAE-Sepharose CL-6B and the choline-Sepharose 4B with C3-spacer, and after the subsequent release of the thionitrobenzoate with dithiothreitol, through a second column of DEAE-Sepharose CL-6B in the presence of 0.1% Triton X-100. The purified preparation gave a specific activity of 6.3 mumol of O2 consumed/min per mg protein at 30 degrees C with phenazine methosulfate as the primary electron acceptor. After polyacrylamide gel electrophoresis in the presence of 0.5% sodium dodecyl sulfate, the enzyme showed activity in the gel. The preparation thus purified oxidized only choline and betaine aldehyde. The Km value for choline was 7.0 mM at an infinite concentration of phenazine methosulfate at pH 7.6 and 30 degrees C. 2-Dimethyl aminoethanol (Ki,app = 1.0 mM) and monoethanolamine did not work as substrates, inhibiting the enzyme competitively. The absolute requirement of any electron acceptor other than the molecular oxygen was confirmed. The Km value for phenazine methosulfate was about 1.1 mM at infinite concentration of choline. These findings suggested that coenzyme Q served as the primary electron acceptor in vivo.

Alcohol Oxidoreductases↗
PubMed1980

Drug recovery following buccal absorption of propranolol.

1 Buccal absorption of propranolol in two volunteers was followed by repeated rinsing of the mouth with buffer solutions for twelve 2 min periods. Values for absorption, recovery and asymptotic recovery were calculated. 2 Large amounts of propranolol were recoverable from the buccal mucosa; recovery was biexponential and the amount recovered depended on the time allowed for absorption and on the pH of buffers used for recovery. 3 In the case of the drug studied, the buccal absorption test was not an adequate model of passive drug transfer through lipid membranes, and more clearly reflected partitioning into the buccal mucosa. 4 It does not follow from disappearance of drug from the buccal cavity that it has entered the circulation. Unabsorbed drug clearly cannot enter the circulation, but other conclusions about systemic absorption cannot be drawn with certainty from the buccal absorption model. 5 Partitioning back into the saliva after absorption also needs to be taken into account for a true model of systemic absorption of orally administered drugs, and a revised schematic representation of the kinetics of oral drug absorption is presented.

Absorption↗
PubMed1980

Conditioned drug effects to d-amphetamine- and morphine-induced motor acceleration in mice: experimental approach for placebo effect.

Ninety-two mice were divided into 2 groups and 2.5 mg/kg of d-amphetamine sulfate was given to one group, and 10 mg/kg of morphine hydrochloride to the other, at daily intervals. These two groups were then further divided into flicking light-presented and non-presented groups. The acute effects of the drugs on the ambulatory activity of each mouse were observed for 180 min after the drug administration. The motor-accelerating effect of both drugs was progressively enhanced with repeated administration. After the drugs were administered 10 times, physiological saline was given subcutaneously to the mice and the motor-accelerating effect of the drugs could be observed for a short time, especially in the flicking light-presented groups. This effect disappeared after repeated administration of saline solution at daily intervals for 6 days. Thus, the motor-accelerating effect produced by saline is considered to have been elicited as the result of conditioning between the conditioned stimuli (flicking light and other environmental factors) and drug effects.

Animals↗
PubMed1980

Proportions of T- and B-lymphocytes in preauricular lymph nodes and aqueous humour of rabbits showing corneal graft reactions.

We wished to determine the proportions of T- and B-lymphocytes in the preauricular lymph nodes and the anterior chambers of rabbits during various stages of graft reactions. The animals received unilateral orthotopic corneal xenografts or skin allografts on the ear. The target cells were identified with the use of fluorescein-tagged antisera specific for rabbit T- and B-lymphocytes. As compared with the percentage in the rabbits that had not received a graft, in both the xenograft and the allograft recipients the percentage of T-lymphocytes in the preauricular lymph nodes during the graft reaction did not change on the side that received the graft but was higher on the side that did not receive a graft. In the recipients of the corneal grafts, as the severity of the graft reaction increased, the percentage of B-lymphocytes in the preauricular lymph nodes on the side that received the graft and the percentage of T-lymphocytes in the lymphoid cell population infiltrating the anterior chamber of the grafted eye increased. The possible mechanisms underlying these phenomena are discussed.

Animals↗