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Biomedical subjects

Y Kakiuchi

Publications and source records attributed to Y Kakiuchi.

At least 55 records · Page 3Linked to original sources
PubMed1979

Effect of alanine-containing dipeptides on germination of Bacillus thiaminolyticus spores.

Stereoisomeric alanylalanine (Ala-Ala) derivatives were examined for their effects on germination of Bacillus thiaminolyticus spores. L-Ala-L-Ala and L-Ala-glycine were effective in inducing germination, and their activities were completely inhibited by D-Ala. L-Ala-D-Ala and glycine-D-Ala competitively prevented L-Ala-induced germination. Sarcosine- or beta-Ala-containing L-alanyldipeptides and eight kinds of alanyltripeptides did not show any detectable effect on germinability or any inhibitory effect. No detectable amounts of Ala were found in germination exudates when alanylpeptides were incubated with spores. The ability of these peptides to induce or inhibit germination depends on their steric conformation and a certain distance between the primary amino group and the free carboxyl groups. Involvement of L-Ala dehydrogenase in the initiation of germination is unlikely because L-Ala-L-Ala was not a substrate and L-Ala-D-Ala was not an effective inhibitor of enzyme activity.

Alanine↗
PubMed1979

A new needle-type colloid osmometer for continuous determination of blood oncotic pressure.

For the purpose of facilitating measurement of colloid osmotic pressure of body fluids, a new needle-type colloid osmometer which uses a hollow fiber as a semipermeable membrane instead of a sheet ultrafilter was developed. The simple construction, easy production, and satisfactory performance of the osmometer are described in detail. Although hydrostatic pressure existing in the sample interfered a little with the accuracy of measurement, quickly interchangeable sensing probes brought great advantages in practice.

Animals↗
PubMed1979

An analysis of water movement between myocardial tissue and capillary blood during reactive hyperemia.

The colloid osmotic pressure (COP) of blood from the great cardiac vein was continuously measured by means of a membrane colloid osmometer during the reactive hyperemia following temporary occlusion of the anterior descending branch of the left coronary artery in anesthetized open-chest dogs. The COP increased sharply after releasing the occlusion, then decreased below the preocclusion level before gradually returning to it. These findings indicate that a measurable amount of water moved from the capillary blood into the myocardial tissues and then flowed back slowly into the capillary blood. To analyse the factors affecting this water movement, a method is proposed in which the Starling mechanism is combined with the interstitial volume elasticity and a steady-state solution of a Navier-Stokes equation. The pressure observed with a catheter wedged into a branch of the great cardiac vein was used as a measure of capillary perfusion pressure. During the coronary arterial occlusion, the filtration constant increased while the volume elasticity of the myocardial interstitial spaces decreased rapidly. The filtration constant and volume elasticity of the interstitial space under normal conditions were approximately estimated to be 2.4 X 10(-11) cm/(sec.dyn.cm-2) and 1.1 X 10(7) dyn.cm-2, respectively.

Animals↗
PubMed1979

Non-uniform oxygen supply to the left ventricular myocardium by systolic perfusion of coronary artery.

The left anterior descending branch of the coronary artery (LAD) of anesthetized, open-chest dogs was perfused by intraventricular pressure (systolic perfusion) and aortic blood pressure (aortic perfusion) alternately. When the LAD perfusion was switched from aortic perfusion to the systolic one, the subendocardial PO2 decreased to 9.8 mmHg, on an average, in 1 to 2 min from the initial level of 18.9 mmHg obtained during the aortic perfusion. On total occlusion of LAD, the subendocardial PO2 fell to 4.5 mmHg, while the subepicardial PO2 showed no significant change. These results suggest that a small amount of oxygen is transported to the subendocardium during the systolic phase despite the impaired blood flow to the subendocardium and that the oxygen supply to subepicardium can be supported even though the LAD perfusion is restricted to the systolic phase.

Animals↗
PubMed1978

Colloid osmotic pressure changes of dog's blood exposed to different mixtures of CO2 and air.

Hansen's membrane manometer method for measuring plasma colloid osmotic pressure was used to obtain the osmolality changes of dogs breathing different levels of CO2. Osmotic pressure was converted to osmolality by calibration of the manometer with saline and plasma, using freezing point depression osmometry. The addition of 10 vol% of CO2 to tonometered blood caused about a 2.0 mosmol/kg H2O increase of osmolality, or 1.2% increase of red blood cell volume. The swelling of the red blood cells was probably due to osmosis caused by Cl- exchanged for the HCO3- which was produced rapidly by carbonic anhydrase present in the red blood cells. The change in colloid osmotic pressure accompanying a change in co2 tension was measured on blood obtained from dogs breathing different CO2 mixtures. It was approximately 0.14 mosmol/kg H2O per Torr Pco2. The corresponding change in red cell volume could not be calculated from this because water can exchange between the plasma and tissues.

Animals↗
PubMed1977

Water movement between myocardial tissue and capillary blood during and after coronary reactive hyperemia as studied by continuous measurement of colloid osmotic pressure of cardiac venous blood.

Colloid osmotic pressure (COP) of blood from the great cardiac vein was continuously measured by the use of a membrane colloid osmometer during reactive hyperemia resulting from temporary occlusion of the anterior descending branch of left coronary artery. The COP increased sharply but transit was concluded that a measurable amount of water moved from the capillary blood into the myocardial tissue and then flowed back slowly into the capillary blood.

Animals↗
PubMed1977

Quick increase of pulmonary blood flow in response to an acute alveolar hypoxia in human subjects.

The effects of acute alveolar hypoxia on pulmonary blood flow were studied in upright standing human subjects by means of a constant expiration technique combined with continuous analysis of the C2H2 fraction in the expired gas. The subject rapidly and deeply inhaled a gas mixture containing 4.87% C2H2, 0.99% O2, N2 for balance and exhaled the alveolar gas via a constant flow valve. The Po2, of the alveolar gas fell to 37.6+/-5.6 mmHg. The C2H2 curve showed a clear downward inflection 7 to 10 sec after the completion of washout of the dead space gas. This inflection indicates an increase of the C2H2 uptake rate produced by an increase in pulmonary blood flow. The pulmonary blood flow calculated for the time range of 10.0 to 12.5 sec after the establishment of acute alveolar hypoxia (6.5+/-1.11/min) was significantly larger than the blood flow under normoxia (5.5+/-0.91/min). This increase associated with a quick rise in systemic arterial blood pressure which was probably induced by a chemical reflex.

Acetylene↗
PubMed1976

Directional non-uniformity of pulsatile intramyocardial pressure.

A method using piezoelectric ceramics was newly devised which permitted measurements of intramyocardial pressure. In open-chest dogs, a directional non-uniformity of the intramyocardial pressure was observed, which may be attributable to the variation in the myocardial fibre orientation.

Animals↗
PubMed1975

Solubilization of coat protein from Bacillus thiaminolyticus spores.

Solubilization of spore coat protein of Bacillus thiaminolyticus was investigated using various reagents, and partial characterization of solubilized protein was carried out. Five per cent of the sodium dodecyl sulphate (SDS) treatment was the most effective for solubilization of coat protein, and 5% SDS + 8 M urea and 0.06 N NaOH were also useful. Acrylamide gel disc electrophoresis indicated that the SDS-soluble fraction mainly consists of a single band of protein and its molecular weight was estimated at about 15,000. The SDS+ urea-soluble fraction comprised two proteins with a molecular weight of 14,500 and 32,000, and an alkali-soluble fraction of 12,000 and 25,000 respectively.

Bacillus↗