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Biomedical subjects

K Ohno

Publications and source records attributed to K Ohno.

At least 757 records · Page 42Linked to original sources
PubMed1979

Blood-brain barrier permeability in senescent rats.

Cerebrovascular permeability to 14C-sucrose was measured in 3-mo-old and 28-mo-old conscious, restrained Fischer 344 male rats. Tracer was injected intravenously in these animals and arterial plasma concentrations were followed for 50 to 240 min, when animals were killed and regional brain radioactivity was measured. Equations derived by a two-compartment diffusion model were fit to concentration data to estimate PA (product of cerebral capillary permeability and surface area) and Ve (cerebral distribution space of 14C-sucrose). PA in 3-mo-old rats averaged 7.53 x 10(-6) sec-1 in 14 cerebral regions, and was not significantly elevated in 28-mo-old rats except possibly at white matter. Ve fell from an average of 0.126 in control rats to 0.070 in 28-mo-old rats. This 45% reduction may reflect a reduced extracellular space in the older animals. The findings do not support the hypothesis that aging of the central nervous system is related to breakdown of the blood-brain barrier.

Aging↗
PubMed1979

Lissencephaly (agyria) on computed tomography.

Unusual computed tomographic findings were observed in two infants with similar clinical pictures including delay in developmental milestones, seizures, decerebrated posture, and microcephaly. Computed tomography revealed small brain with widened subarachnoid space, smooth surface of the brain, uniformly enlarged ventricles, wide sylvian cisterns, and lack of insular opercularization. These findings coincide with pathologic features of lissencephaly (agyria), a rare congenital anomaly of the brain due to interruption of neuronal migration.

Brain↗
PubMed1979

Osmotic opening of the blood-brain barrier to methotrexate in the rat.

Osmotic opening of the blood-brain barrier in the rat, by intracarotid infusion of 1.6 molal (m) arabinose solution, increases cerebrovascular permeability to 3H-methotrexate by a factor of about seven. PA (product of permeability and capillary surface area) increases from a mean of 3.3 X 10(-5) sec-1 in brains of control rats to as much as 28 X 10(-5) sec-1 at the cerebral hemisphere ipsilateral to carotid infusion. If tracer is introduced into the carotid artery after osmotic treatment, brain uptake is increased by a net factor of 50 (a factor of 70 due to elevation of PA, multiplied by 7 due to infusion by the carotid route) as compared to uptake by normal, untreated brain with infusion into a peripheral vein. Osmotic barrier opening followed by carotid drug administration may be of use in experimental chemotherapy of nervous system disease.

Animals↗
PubMed1978

Polyamine metabolism III: urinary acetyl polyamines in human cancer.

Polyamine levels were determined by high-pressure liquid chromatography in the unhydrolyzed 24-hr urine obtained from 15 cancer patients and nine normal subjects. N1-Acetylspermine, N4-acetylspermine, N4-acetylspermidine, and N-(3-aminopropyl)acetamide were not detected in any samples. N1-Acetylspermidine, N8-acetylspermidine, acetylputrescine, and acetylcadaverine were present in all samples. Furthermore, acetylspermidine and acetylputrescine were excreted in much greater quantities than the respective amines in the urine of both cancer patients and normal subjects. The levels of N1-acetylspermidine were considerably higher than the levels of N8-acetylspermidine in the 24-hr urine of cancer patients, resulting in a ratio of N1- to N8-acetylspermidine in the urine of cancer patients significantly higher than that in normal subjects. The urinary levels of acetylputrescine were also significantly higher in cancer patients. The urinary polyamines in 13 of the 15 cancer patients were outside the 95% confidence limits of the normal mean for the ratio of N1- to N8-acetylspermidine and acetylputrescine. All cancer patients showed values outside the 95% confidence limits of the mean for either of these two parameters. Diurnal variation was observed in the urinary excretion of the acetyl polyamines but not for the free amines in two normal subjects.

Acetylation↗
PubMed1978

Metabolism of lecithin and phosphatidylglycerol in surfactant fraction of the lung.

The metabolisms of lecithin and phosphatidylglycerol in the surfactant and residual fractions of rat lung were compared using the in vitro system where tissue slices and radioactive precursors such as [14C]palmitic acid, [14C]palmitoyl lysolecithin and [14C]stearoly lysolecithin were inculbated. The incorporation of precursors into the residual lecithin proceeded linearly during the incubation time, while the time curve on the incorporation into the surfactant lecithin exhibited a lag period before the incorporation increased significantly. A similar tendency was also observed in the incorporation into phosphatidylglycerol. These findings suggested a precursor-product relationship between the corresponding lipids in both the fractions. The turnover time of lecithin was approx. 340-370 min and that of phosphatidylglycerol was 118 min in the intracellular surfactant fraction. The turnover rates of lecithin and phosphatidlyglycerol were approx. 0.6 and 2 nmoles/g of wet tissue, respectively. The transfer of lecithin from the residual fraction to the surfactant fraction was hardly influenced by the difference of fatty acid moiety at the 2-position of 1-palmitoly-lysolecithin. However, the turnover time of 1-palmitoyl lecithin (360 min) was distinctly shorter than that of 1-stearoly species (730 min). The turnover time of the saturated lecithin was also shown to be 328 min. On the other hand, polyenoic species showed the shorter turnover time; 182 min for the tetraenoic species.

Animals↗
PubMed1978

Alveolar phospholipids in pulmonary alveolar proteinosis.

The biochemical compositions of lung lavage fluid from three patients and that of the lung tissue obtained by a biopsy from a patient with alveolar proteinosis were analyzed. The lung lavage fluid was separated to the supernatant and the insoluble precipitate fractions by a brief centrifugation and the lung tissue was separated to surfactant and residual fractions by sucrose density gradient centrifugation. The supernatant of lung washing contained larger quantities of protein and less lipid which was mainly composed of lecithin and sphingomyelin. In contrast, the insoluble material of lung washing contained 4--8 fold of lipid as compared with the supernatant, and lecithin was a predominant phospholipid. From the analysis of fatty acid and individual molecular species of major phospholipids, the higher contents of dipalmitoyllecithin and sphingomyelin containing palmitate were found in the insoluble material. The phospholipid composition and fatty acid composition of lecithin were similar between the precipitate fraction of lung washing and the surfactant fraction of lung tissue. The ratio of protein to phospholipid in the precipitate fraction was similar to that of lung washing. These analytical data suggest that the materials accumulated in the alveoli of the patients may be derived mainly from the lung surfactant fraction. The metabolic studies showed that lecithin synthesis through de novo and lysolecithin pathways works in human lung with this disease as actively as in rat lung. The secretion of lung lecithin to the surfactant fraction also appeared to be normal. From these analytical and metabolic findings, the causes for the accumulation of the materials which cover alveolar surface and impair gaseous exchange in the alveoli of pulmonary alveolar proteinosis, were discussed.

Animals↗
PubMed1977

Effect of light-adaptation on the photoreaction of bacteriorhodopsin from Halobacterium halobium.

Light-induced formation of the 410 nm intermediate was investigated on dark-and light-adapted bacteriorhodopsin. The amplitude of the light-induced absorption increase at 410 nm of the light-adapted bacteriorhodopsin was twice as large as that of the dark-adapted bacteriorhodopsin. The amount of protons released from bacteriorhodopsin in response to illumination was also enhanced by light-adaptation. The degree of the enhancement was independent of the temperature in the dark-adaptation. The relation between these photochemical events and the isomeric configurations of retinal is discussed.

Adaptation, Physiological↗
PubMed1977

Assimilation of liquid hydrocarbon by microorganisms. II. Growth kinetics.

The growth kinetics of a microorganism with high affinity for liquid hydrocarbon which has a low solubility in water was investigated for Candida intermedia IFO 0761 in our previous work. The microorganism contained a hydrocarbon pool in and/or on the cell. The transfer of water-soluble substrates to the cell was not the rate-limiting step in the growth of C. intermedia accompanied by clump formation with liquid hydrocarbon. The operating conditions necessary for the oxygen supply for the growth were adequate for the growth of C. intermedia on n-tetradecane. The saturation kinetics was valid for the specific growth rate of C. intermedia and specific concentration of hydrocarbon per unit cell mass; the specific growth rate was expressed by the following equation: (formula: see text).

Antifoaming Agents↗