Search PubMed⌕ Search

Biomedical subjects

K Murayama

Publications and source records attributed to K Murayama.

At least 217 records · Page 12Linked to original sources
PubMed1977

Soluble proteins from fowl feather keratin. I. Fractionation and properties.

A method is described for the fractionation of reduced and alkylated proteins of fowl feather. Fowl feather extracts were chromatographed on a Sephadex G-75 column in 4 M urea containing 1 M NaCl and separated into four fractions, GF-1, 2, 3, and 4. The elution patterns were used to compare the components of different feather parts, barbs, rachis + medulla, and calamus. In all cases, GF-3 was the main fraction and the percentages with respect to the total peak area found for barbs, rachis + medulla, and calamus were about 65%, 74%, and 93%, respectively. Each of the fractions was examined by polyacrylamide disc gel electrophoresis and all were heterogeneous. The slowly moving bands mainly corresponded to fraction GF-1, intermediate bands to GF-2 and 3, and faster bands to GF-4. Many other polypeptide chains, which have not been found previously, were newly separated from three minor fractions of fowl body feather. The molecular weights of fractions GF-2 and 3 were estimated by calibrated gel filtration to be 33,000 and 10,500, respectively. Marked differences were found in the amino acid compositions of various fractions from fowl feather. The GF-1 fraction and insoluble residue had very similar compositions; in both cases the contents of serine, glycine, and proline were lower and those of helix-favoring amino acids, namely, lysine, tyrosine, and methionine, were higher than those found in other fractions.

Alkylation↗
PubMed1977

Soluble proteins from fowl feather keratin. II. Isolation of some proteins from barbs.

Four fractions, GF-1, 2, 3, and 4, which had been separated from S-carboxymethylated (SCM-) proteins of fowl feathers by gel filtration, were each chromatographed on a DEAE-cellulose column in 0.05 M Tris-HCl buffer (pH 8.5) containing 8 M urea. The major fraction, GF-3, was further separated into seven peaks; the first four were shown to be single components by polyacrylamide disc gel electrophoresis. Chromatograms of GF-1 and 2 showed broad peaks which appeared at nearly the same volume as in GF-3. The components from GF-3 had very similar amino acid compositions except that the SCM-cysteine content showed a tendency to increase in the order of elution from the column. SCM-extract prepared from barbs of the wing feathers of a fowl was more heterogeneous than that taken from the body feathers. A combination of gel filtration on Sephadex G-75 and chromatography on DEAE-cellulose was found to be more effective for the isolation of soluble SCM-proteins.

Amino Acids↗
PubMed1977

Soluble proteins from fowl feather keratin. III. Isolation and characteristics of some calamus proteins.

The main fraction, GF-3, separated from SCM-proteins of fowl feather calamus by gel filtration, was separated into seven peaks, C-1 to C-7, by ion exchange chromatography on a DEAE-cellulose column. Each fraction was found to contain two components by polyacrylamide gel electrophoresis. In order to separate these two components, recycling gel filtration on a Sephadex G-75 column was carried out. Two peaks separated from each of four fractions, C-3 to C-6, were termed C-3a and -3b, C-4a and -4b, and so on. Electrophoretic results showed that all the fractions were single protein components. Components a and b of a particular fraction had almost identical electric charge and slightly different molecular size. All components in Group a (C-3a to C-6a) had similar amino acid compositions except for SCM-cysteine content, and similar results were obtained for Group b (C-3b to C-7b). Groups a and b had significantly different amino acid compositions.

Amino Acids↗
PubMed1977

Action of histamine and H1 and H2 blockers on the cardiopulmonary circulation.

Systemic and pulmonary hemodynamic responses to histamine were investigated inchronically instrumented unanesthetized nonpregnant ewes. Histamine was administered intravenously and into the pulmonary artery. The effects of the same doses of histamine were assessed following H1 and H2 receptor blockade. The effects ocular changes were also monitored. Results indicate that intravenous histamine produces tachycardia, systemic hypotension, pulmonary hypertension, and reduced cardiac output. The pulmonary response could be modified significantly by pentobarbital anesthesia. When injected directly into the pulmonary artery histamine failed to elicit any circulatory response. Blockade of H1 and H2 receptors, as well as autonomic ganglia, resulted in a comparable attentuation of the histamine circulatory response. It is concluded that a) central hemodynamic responses do not seem to be mediated through specific H1 and H2 receptors; b) histamine-induced pulmonary vasoconstriction can be reversed by pentobarbital anesthesia, and c) the absence of circulatory response to intrapulmonary histamine administration suggests that whatever receptors that may exist in the pulmonary vascular bed are not necessary for the central hemodynamic effects.

Animals↗
PubMed1977

Autonomic control of cardiovascular functions during neonatal development and in adult sheep.

We studied the autonomic control of resting heart rate of systemic and pulmonary vascular blood pressures (BP) in chronically instrumented neonatal lambs 1-8 weeks of age. The maximum response to ganglionic blockade and sympathetic and parasympathetic antagonists was taken as an index of the magnitude of the total neural, adrenergic, and cholinergic tones. The reactivity of the circulatory parameters to adrenergic and cholinergic agonists also was investigated. All findings were compared with those in adult nonpregnant sheep studied concomitantly and with data previously obtained from term fetal lambs. The results of our studies show: (1) resting heart rate declines spontaneously throughout the 8 weeks of neonatal life approaching that of adult sheep; (2) the progressive bradycardia is not related to changes in the parasympathetic or sympathetic tone; (3) resting systemic BP is under strong neurohumoral control during the first two to three weeks of neonatal life; the control decreases progressively, becoming similar to that of adult sheep; (4) resting pulmonary artery pressure of neonatal and adult sheep has no neurohumoral control; (5) the systemic BP response of the neonate to autonomic agonists is greater than that of the term fetus and is similar to that of the adult; (6) in neonatal and adult sheep, compared to the term fetus, the pressor response to norepinephrine is accompanied by a baroreceptor-mediated bradycardia, and acetylcholine-induced systemci hypotension is accompanied by a "paradoxical" tachycardia mediated through beta-adrenergic stimulation; (7) in contrast to our finding for the fetus, the pulmonary vascular pressure of neonatal and adult sheep is unresponsive to autonomic agonists.

Acetylcholine↗
PubMed1975

Estimation of surface charges in some biological membranes.

The resting membrane potential data existing in the literature for the giant axon of the squid, frog muscle and barnacle muscle have been analyzed from the standpoint of the theory of membrane potential due to Kobatake and co-workers. The average values derived for the effective charge density phi chi (where phi is a constant, 0 less than phi less than 1, and represents the fraction of counterions that are free, and chi is the stoichiometric charge density in the membrane) present on the different biomembranes existing in their normal ionic environment are 0.3, 0.325 and 0.17 M for the squid axon, frog and barnacle muscles, respectively. On the assumption that the values of phi are 0.4 and 0.2 for nerve and muscle membranes, respectively, values of 0.75, 1.62 and 0.85 M have been derived for the stoichiometric charge density (chi) present in the respective biological membranes. These correspond to 1 negative charge per 222, 103 and 195 A2 of the membrane area of the squid axon, frog and barnacle muscles, respectively.

Animals↗
PubMed1975

Comparison of the action of different barbiturates on squid axon membranes.

Experiments utilizing squid giant axons have been carried out to determine if the duration of anesthesia obtained from phenobarbital, pentobarbital and hexobarbital can be explained by events related to their action at the nerve membrane level. For comparison, the barbiturates were perfused both outside and inside the squid axon at concentrations which produced an approximately equivalent depression of the maximum rate of rise of the action potential. The time to 50% maximum block and the time to 50% maximum recovery following washing, were compared for all three drugs. All three barbiturates were more potent from inside the squid axon than from the outside. This finding coupled with the fact that the time course of the drug effects was much shorter when applied inside as compared to outside suggests an internal site of action. There was no statistically significant difference between a short acting barbiturate and a long acting barbiturate with respect to their time course of action or recovery when they were both applied to either the inside or outside of the membrane.

Action Potentials↗