Search PubMed⌕ Search

Biomedical subjects

A Okada

Publications and source records attributed to A Okada.

At least 397 records · Page 22Linked to original sources
PubMed1986

Physiological response of the rat to different vibration frequencies.

Vibration (acceleration of 50 m/s2 and frequencies from 30 to 960 Hz) was applied to the tail and hind legs of rats for a 4-h period. The responses of the peripheral circulatory and peripheral nervous systems, muscle function, and the central nervous system were examined. When a tail was exposed to the vibration stimulus, the skin temperature dropped significantly at 30 and 240 Hz; the blood flow decreased significantly at 30, 60, and 480 Hz; and the peripheral nerve conduction velocity was significantly slower at 30, 60, and 120 Hz. After vibration of the hind legs the activity of plasma creatine phosphokinase (CPK) showed significantly high values at 30, 60, 120, and 480 Hz and was especially high at 30 Hz; the content of brain norepinephrine was significantly decreased at 120 Hz in the hypothalamus; dopamine was significantly increased at 60 Hz in the medulla oblongata and pons; and serotonin was significantly increased at 120 Hz in the hypothalamus. Thus the physiological responses of the rat to local vibration depend on, among other variables, the vibration frequency. In the case of the response of plasma CPK it would appear to depend on the amplitude (displacement) of this stimulus.

Animals↗
PubMed1986

Total parenteral nutrition in familial hypercholesterolemia: importance of caloric control.

Effects of total parenteral nutrition (TPN) on serum cholesterol levels were examined in four patients with homozygous and three patients with heterozygous familial hypercholesterolemia and 13 patients without hypercholesterolemia. Fat-free TPN was administered in average doses of 26.5 cal/kg/day (43.6 cal/kg/day in a child) for 5 to 14 weeks. The serum cholesterol level decreased markedly by 47.5% and 58.6% in homozygous and heterozygous cases, respectively. Despite restriction in calories of TPN, protein nutrition was maintained in all patients. It became apparent that in familial hypercholesterolemia, whether the heterozygous or homozygous form, TPN performed at a well-adjusted caloric intake provided an adequate control of the serum cholesterol level as far as TPN was continued. In patients without hypercholesterolemia under TPN, serum cholesterol levels varied correlatively with the amount of calories to be administered. Compared with values before TPN, serum cholesterol level as far as TPN was continued. In patients without hypercholesterolemia under TPN, serum cholesterol levels varied correlatively with the amount of calories to be administered. Compared with values before TPN, serum cholesterol levels at the fourth week of TPN were elevated or maintained in patients receiving more than 40 cal/kg/day, while it was reduced in patients given less than 40 cal/kg/day. There was a statistically significant correlation between daily caloric intake per body weight and change of serum cholesterol level at the fourth week of TPN. This indicates that caloric control is of importance in TPN-induced change in serum cholesterol levels.

Adolescent↗
PubMed1986

[Hyperbilirubinemia in neonates associated with total parenteral nutrition].

Clinical studies on the pathogenesis of hyperbilirubinemia (HB) in neonates during total parenteral nutrition (TPN) were performed. From 1971 to 1982, 77 neonates underwent TPN for more than 2 weeks in our institutions. Forty-four of them (57.2%) developed HB during the first one month of life. Twenty eight of 32 patients (87.5%) with dominant infection developed hB, while only 16 of 45 (35.6%) without infection developed HB. Patients with any kind of obstructive intestinal diseases evoked HB more commonly than patients with other diseases. In addition, HB occurred more often in the patients receiving more than 110 kcal/kg/day than those receiving less than that. Gestational ages, birth weights, the duration of TPN and fasting periods had no significant influence on the occurrence of HB.

Age Factors↗
PubMed1986

Plasma concentration and peritoneal clearance of oxalate in patients on continuous ambulatory peritoneal dialysis (CAPD).

Accumulation of oxalate, resulting in high plasma levels, is a common finding in end-stage renal disease. We investigated plasma concentration and peritoneal clearance of oxalate in 14 patients on continuous ambulatory peritoneal dialysis. The plasma oxalate levels in these patients (30.2 +/- 11.2 mumol/l) were as high as those in hemodialysis patients before dialysis (31.9 +/- 11.1 mumol/l). There was a significant correlation between plasma oxalate and urea nitrogen appearance (UNA). Dietary protein seems to be an important oxalate source in these patients, because the UNA reflects protein intake in stable patients. The mean peritoneal oxalate clearance was 6.64 +/- 1.56 l/day, close to the creatinine clearance. These results suggest that the plasma oxalate levels in CAPD patients may be sufficiently high to induce calcium oxalate deposition, and that methods of increasing oxalate removal and reducing oxalate burden are necessary for CAPD patients.

Adolescent↗
PubMed1986

Development of a cortical granule-free area of cortex and the perivitelline space in the hamster oocyte during maturation and following ovulation.

The distribution and behavior of cortical granules (CGs) in hamster oocytes at various stages of maturation were examined using both light (phase-contrast) and electron microscopy. At the germinal vesicle stage, CGs were distributed almost evenly in the cortex of the oocyte. A 'small' CG-free area of the cortex, with prominent cytoplasmic protrusions, appeared twice during the progression of meiosis. The first time, immediately above the metaphase spindle of the first meiosis and secondly, above the metaphase spindle of the second meiosis. Both peripheral migration and exocytosis of CGs appeared to be responsible for the formation of CG-free cortex above the metaphase spindle of first meiosis. The development of CG-free cortex above the metaphase spindle of the second meiosis was definitely due to exocytosis of CGs. The CG-free cortex above the metaphase spindle of the second meiosis increased its size steadily even after the oocytes had been transported into oviducts. Concomitantly, the size of the perivitelline space increased. The enlargement of the perivitelline space in unfertilized oviductal oocytes seems to be attributed not only to the exocytosis of CGs, but also to an extrusion of non-CG materials by the oocytes and perhaps an accumulation of some materials secreted by the oviduct epithelium. The limited (premature) CG-exocytosis during oocyte maturation and prior to fertilization may alter the physico-chemical properties of the zona pellucida slightly in such a way that the zona can be penetrated only by a very 'strong' spermatozoon. The presence of the perivitelline space in the mature oocyte prior to fertilization seems to be essential or at least beneficial to normal fertilization. Distinct cytoplasmic protrusions appear on the cortex above the metaphase spindle. The plasma membrane covering these protrusions seems to represent the membrane synthetized by the oocyte in preparation for the extrusion of polar body.

Animals↗
PubMed1985

Study on the mechanism of the appearance of noise effects.

This study was undertaken to investigate the dose-response relationship between the biological effect and noise exposure, and to consider the mechanism of the appearance of noise effects. Rats were exposed to noise at intensities of 60 dB (A), 80 dB (A) and 100 dB (A) for 240 min and examined for the change of activities of dopamine-beta-hydroxylase (DBH) in serum and adrenal glands. Plasma cyclic adenosine 3',5'-monophosphate (c-AMP) levels were also measured. Some rats were given 6-hydroxydopamine (6-OHDA) as a chemical sympathectomyzing agent 20 h before noise exposure in order to consider the mechanism of the appearance of noise effects. By noise exposure, serum DBH activity was significantly (P less than 0.01) increased at each intensity compared with the control group, but there were no remarkable changes in adrenal DBH activity. Plasma c-AMP level was also significantly elevated in response to the noise stress. When the rats, which had been pretreated with 6-OHDA, were exposed to noise with an intensity of 100 dB (A), the response of serum DBH activity was no longer observed. Therefore it is suggested that the effect due to noise exposure appears through the post-ganglionic sympathetic nerve fiber.

Adrenal Glands↗
PubMed1985

A hapten-induced conformational change accompanies the cryoprecipitation of an immunoglobulin.

By simultaneous spectroscopic measurements (absorbance, light scattering, fluorescence and circular dichroism) the temp-dependent behavior of a cryoglobulin, the mouse monoclonal immunoglobulin G to N-acetyllactosamine, has been observed. The results show that a hapten-induced conformational change in the structure of a cryoglobulin can accompany its intermolecular association. This association of the immunoglobulin increases after hapten saturation of its two antigen-combining sites.

Amino Sugars↗
PubMed1985

Constancy of DNA organization of polymorphic and nonpolymorphic genes during development in Xenopus.

A study was undertaken to test for the occurrence of DNA rearrangements or amplifications during embryonic development in Xenopus laevis. DNA isolated from testes and liver was digested with four restriction enzymes, separated on agarose gels, transferred to nitrocellulose, and hybridized with over 50 cloned cDNA probes generated from embryonic poly (A)+ RNA. No qualitative or quantitative differences were detectable in the DNA hybridization patterns of testes and liver DNA, suggesting that, at least during liver development, selective amplifications or rearrangements occur rarely if at all. In the course of this investigation a wide range of restriction-site polymorphisms for different genes was observed. While some genes showed little polymorphism among different animals, several genes showed considerable polymorphism, involving changes in several restriction enzyme sites. These complex polymorphisms could be the result of gene rearrangements that occur occasionally during the course of sexual reproduction rather than during development.

Aging↗