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Biomedical subjects

Y Ohta

Publications and source records attributed to Y Ohta.

At least 919 records · Page 51Linked to original sources
PubMed1987

Recent studies on M-SHRSP and their crossbred offspring with WKY.

An inbred strain of M-SHRSP was established through successive selective brother-sister breeding of SHRSP for over 20 generations while administering hydralazine hydrochloride. This strain shows blood pressures as high as 250 mmHg or more in males at 12 weeks of age and in females at 15 weeks of age. The incidence of cerebrovascular lesions is over 97%, somewhat higher than that of SHRSP, in both sexes. But there is a remarkable increase in the incidence of multiple small hemorrhages at the base of the brain. Plasma renin activity increases more rapidly than that of SHRSP. Blood pressure of the hybrid (WT) obtained by crossbreeding M-SHRSP and WKY were intermediate to those of the parents. Those offspring obtained by backcrossing WT with WKY for 3 generations were intermediate to those of the parents and had gradually decreased nearly to the level of WKY. Those offspring obtained by backcrossing WT with M-SHRSP for 4 generations were also intermediate to those of the parents and had gradually rose nearly to the level of M-SHRSP. These various M-SHRSP, WKY and hybrid crosses and backcrosses have resulted in rat colonies with eight gradients of blood pressure, ranging from 135 to 250 mmHg.

Animals↗
PubMed1987

Seadragon VI: a 7-day saturation dive at 31 ATA. V. Cardiovascular responses to a 90 degree body tilt.

Cardiovascular deconditioning (CD) has been reported to occur in weightlessness, bed rest, and head-out water immersion. An expanded intrathoracic blood volume results, at least initially, in all these diverse conditions. Subjects in hyperbaric environments exhibit cephalad redistribution of blood volume, which also occurs in weightlessness, bed rest, and head-out water immersion. This physiologic similarity led us to suspect that CD may also occur as a consequence of hyperbaric exposure. We examined this possibility in 3 young male subjects during a 7-d dry saturation dive at 31 ATA. Changes in blood pressure, heart rate, and stroke volume were measured before and during 15 min of the 90 degree body tilt. These changes, expressed either singly or in combination, provided indications of CD during and immediately after hyperbaric exposure. One of the principal indicators of CD was the inability to exert adequate vasoconstriction. In addition, 1 subject fainted during hyperbaric exposure, whereas no such episode occurred before or after the exposure. These findings suggest that inappropriate orthostatic reflexes may be evoked by hyperbaria and reduced physical activity over the period of confinement. It should be noted, however, that CD was already evident within 24 h of hyperbaric exposure, suggesting that the initial phase of CD was unrelated to physical confinement. We postulate that CD occurs during hyperbaric exposure as an expression of cardiovascular and neurohumoral adaptation to an expanded central blood volume with a reduced total blood volume.

Adult↗
PubMed1986

Type II Ca2+/calmodulin-dependent protein kinase binds to actin filaments in a calmodulin-sensitive manner.

Multifunctional type II Ca2+/calmodulin-dependent protein kinase purified from rat brain cytosol was found to bind to actin filaments in vitro. The binding was saturable, and the dissociation constant for the binding was determined to be about 4 X 10(-8)M. Electron microscopic observation indicated that the kinase binds to the side of actin filaments. Calmodulin inhibited the binding of the kinase to actin filaments in a Ca2+-dependent manner. The Ca2+/calmodulin-regulated binding of the kinase to actin filaments revealed here may be important for the substrate recognition of the kinase.

Actin Cytoskeleton↗
PubMed1986

The Wiedemann-Beckwith syndrome: pedigree studies on five families with evidence for autosomal dominant inheritance with variable expressivity.

We describe 18 individuals from five unrelated families with various manifestations of the Wiedemann-Beckwith syndrome. Pedigree analysis was performed on the 5 families and on another 19 families in the literature, each of which included more than one affected person. The following findings were obtained: 1) the clinical manifestations among the affected individuals were highly variable--those obvious in infancy tended to become less distinct with increasing age; 2) the syndrome was transmitted directly and vertically through three generations in four families, and through two generations in seven families; 3) male-to-male transmission was noted once; 4) the sex ratio in the affected individuals was not significantly different from 1; 5) the segregation ratio of the trait among the sibs of the probands was 0.571 +/- 0.066; 6) the affected + carrier/normal ratio was one among the offspring of the affected individuals and obligate carriers; 7) phenotrance (the expected presence of the trait in a generation) of the syndrome in the sibship of probands was complete, whereas that in earlier generations appeared low. The discrepancy is attributable to the lessening of the clinical features with increasing age as well as to a possibly less aggressive search for abnormalities in older generations. These findings indicate that the syndrome is an autosomal dominant trait with variable expressivity. High-resolution chromosome banding analysis in seven affected individuals and their respective parents showed no abnormalities.

Adult↗
PubMed1986

Inhibitory activity of the serum from patients with fulminant hepatitis against liver regeneration.

The effect of sera from 8 patients with fulminant hepatitis, including 2 survival cases, on DNA and protein synthesis in primary cultured rat hepatocytes was studied. The serum from patients at an early stage or within 10 days after onset tended to intensify DNA synthesis in isolated hepatocytes, whereas the serum from patients with a history of over 50 days distinctly inhibited synthesis. When the serum was fractionated by gel filtration or free-flow electrophoresis, only the albumin fraction inhibited DNA synthesis in cultured hepatocytes. The suppressive effect of the albumin fraction was demonstrated even in patients suffering for only a short period of time. The inhibitory activity against DNA and protein synthesis in cultured hepatocytes was demonstrated in a substance extracted with a chloroform and methanol mixture from the albumin fraction of patients with fulminant hepatitis. The extract from the patients' sera also inhibited acceleration of DNA synthesis by epidermal growth factor (EGF) in the same cells.

Acute Disease↗
PubMed1986

Thymosin alpha 1 enhances haemopoietic colony formation by stimulating the production of interleukin 3 in nu/nu mice.

We have studied the action mechanism of thymosin alpha 1 in modulation of haemopoietic system. The present study demonstrated that thymosin alpha 1 enhanced the colony formation as determined by CFU-s, GM-CFU and T-CFU, as well as the production of IL-3, when administered twice a week for a total of six or twelve times into nu/nu mice. The incubation of bone marrow cells with thymosin alpha 1 in vitro did not cause an increase of CFU-s, in contrast to IL-3 which caused a marked increase of CFU-s during the incubation of 72 h. These experiments indicate that thymosin alpha 1 exerts its effect on colony formation of haemopoietic stem cells (CFU-s) indirectly through the enhancement of the IL-3 production. The present finding may support clinical applications of thymosin alpha 1 in a wide range, since IL-3 is known to be the growth factor for many kinds of haemopoietic precursor cells including not only CFU-s but also GM-CFU, BFU-E, Eos-CFU, Meg-CFU, Mast cells, Pre B-cells and Pre T-cells.

Animals↗
PubMed1986

Effect of ammonia on glucagon secretion from the perfused pancreas of cirrhotic rats.

Effects of ammonia on glucagon and insulin secretion from the perfused pancreas of cirrhotic rats were investigated to clarify the occurring mechanism of hypersecretion of pancreatic glucagon in liver cirrhotics. The results were as follows: During ammonia loading, insulin secretion was inhibited in a dose-related manner, whereas glucagon secretion was gradually increased at high concentrations of ammonia (2 mM) in control rats; this tendency was augmented in the presence of alpha-ketoglutarate in cirrhotic rats. On cessation of ammonia loading, a transient but definite increase in glucagon and insulin secretion was observed. Basal plasma glucagon and ammonia levels as well as basal glucagon secretion from the perfused pancreas of cirrhotic rats were significantly higher than in control rats. Basal insulin secretion from the perfused pancreas of cirrhotic rats was not different in spite of high levels of plasma insulin. Glucagon secretory response to glucose and arginine from the perfused pancreas of cirrhotic rats was higher than in the control pancreas, whereas insulin secretion was lower. In these cirrhotic rats, an increase in the number of islet cells, particularly A cells, was observed. These data suggested that hypersecretion of pancreatic glucagon which was responsible for hyperglucagonemia in cirrhotic rats might be attributed to high levels of ammonia and alpha-ketoglutarate in blood as well as to the fluctuation of abnormal ammonia concentration in blood and to the hypertrophy of islets, particularly of the A cell group due to hypersecretion.

Ammonia↗
PubMed1986

Nephropathy of familial lecithin-cholesterol acyltransferase deficiency: report of a case.

A ninth Japanese patient afflicted with lecithin-cholesterol acyltransferase (LCAT) deficiency is described with emphasis on renal pathology. The most striking feature is massive deposition of lipid material in the glomeruli, particularly in the glomerular basement membrane (GBM) and in the mesangial region. The glomerular changes appear to be similar to that seen in some cases with cirrhosis of the liver. Lipid material contains a large amount of apolipoprotein-B detected by immunohistology. In two renal biopsies, taken three years apart, renal pathology is essentially the same and glomerular pathology is most characteristic. It is suggested that lipid deposition in glomeruli in this patient is rather slow. Family study of the present case reveals consanguinous marriages in the previous two generations suggesting the exaggerated gene expression of LCAT deficiency in this family.

Adult↗
PubMed1986

Excitability level-setting mechanisms in the pons: their behavioral support in decerebrate, reflex standing and freely moving, intact cats.

In the acute precollicular-postmammillary decerebrate cat, stimulation of the mesencephalic locomotor region (MLR) induces "controlled locomotion" on a moving treadmill. Stimulation of the dorsal area and of the ventral area of the pons at its midline elicited a long-lasting decrease and an increase in the tone of the hindlimb extensor muscles, respectively. By selecting the stimulus strength according to the stimulus site, it was possible to set the extensor muscle tone level, that is the "background excitability" of the brain stem and the spinal cord. Locomotor effects induced by MLR stimulation were greatly modified by the set level of background excitability. When the background excitability was high, MLR stimulation evoked "spastic" locomotor movement, while "atonic" locomotor movement was evoked when it was low. Furthermore, stimulation of the ventral area alone also evoked "spastic" locomotor movement. During locomotion in intact cats, stimulation of the dorsal area evoked a series of postural changes. Within a few seconds from the beginning of stimulation, the cat ceased to walk, but maintained a standing posture with or without a locomotor figure. With continuation of this stimulation, it squatted and then lay down on the floor in a sequential manner. Stimulation of the ventral area of the pons evoked an almost opposite series of postural changes. Within a few seconds from the beginning of stimulation, the cat changed from a lying to a squatting posture, and then stood, started to walk and continued to walk during the period of stimulation. All these results demonstrate that an increase in extensor muscle tone and activation of the spinal stepping generator are not separate phenomena, and suggest that integration of neuronal mechanisms involved in the setting of the background excitability and in locomotor movement is a prerequisite for successful expression of locomotor behavior both in decerebrate and intact cats.

Animals↗
PubMed1986

High-efficiency genetic transformation of maize by a mixture of pollen and exogenous DNA.

High-efficiency genetic transformation was induced in a genetic stock of maize, Zea mays Linnaeus, by self-pollination of the recipient plants along with DNA of the donor. The highest frequency of transformed endosperm per ear was 9.29%. DNA was applied onto silks in a pollen/DNA pasty mixture. The exogenous DNA transferred into endosperm expressed itself in endosperm formation. It is not known, however, whether the exogenous DNA segment in endosperm had been incorporated or whether it was present in the nucleus additionally, fragmentally, or in some other state. It was revealed that all of four possible cases had occurred as follows: exogenous DNA was transferred into (i) both embryo and endosperm of the same kernel, (ii) embryo only, (iii) endosperm only, and (iv) neither embryo nor endosperm. It was also revealed that exogenous DNA that had entered into the embryo had been maintained through embryo formation, germination, vegetative growth and differentiation, and reproductive growth, and finally was manifested in embryo and/or endosperm of the following generation and acted in endosperm formation. The frequency of transformed endosperm in this generation, however, was rather low. It may be that exogenous DNA taken into the embryo was unstable.

Journal Article↗
PubMed1986

[Studies on the occupational maladjustment syndrome. (Part 3). In reference to the therapeutic system for the OMA syndrome and the industrial physician's roles].

In order to ascertain the effects of the newly-devised therapeutic system (described later) and clarify the industrial doctor's roles, a study was made on 96 patients with O.M.A.S. (34 in core group, 26 in dropout group, 15 in other group, 13 in transient reaction group and 8 in special job maladjustment group) whom we had directly treated. The subjects of the present study were 54 patients with O.M.A.S. who were treated in the clinic (our clinic) at the Dept. of Mental Health, Osaka Prefectural Institute of Public Health during the past 19 years and 42 patients who were examined in the company's clinic (this company consists of 15,000 employees) where we have practiced mental hygiene of industrial medicine during the past 15 years. Two typical cases in respect of the therapeutic system are presented. We developed a newly-devised therapeutic system of O.M.A.S. (I. Medical examination, II. Counselling for the patients and their family, III. Psychiatric rehabilitation, and IV. Therapeutic advices for their colleagues or superiors in their working place). Of the 96 patients, 81 were reinstated to their office and are at work by using the therapeutic system. Of 96 patients it was necessary for 59 to accept the therapeutic advices. In 49 of 59 patients (Accepted group), doctor's therapeutic advices were accepted by their colleagues or superiors in their working place. In the remaining 10 patients (Refused group) treated by our clinic, the therapeutic advices were refused. Accepted group was observed to be more adaptable to their jobs than refused group. As to the therapeutic content we manipulated their conditions as follows: therapeutic transposition in 27 patients, reduction of duty and guidance of work in 18 patients, and therapeutic preliminary reappointment in 13 patients. It is considered that the industrial doctor of mental hygiene plays an important role in order to establish the therapeutic system of O.M.A.S.

Adaptation, Psychological↗
PubMed1986

[Study on the toxicity of SF-1008C (II): Subacute toxicity study in rats].

The toxicity of an elemental diet (SF-1008C) for hepatic failure and recovery after administration were investigated in Sprague-Dawley rats. The rats were orally administered the drug in doses of 10, 20 and 30 g/kg/day for five weeks, after which, recovery was studied for five weeks. The results were summarized as below: In the 30 g/kg/day group, decreases in food and water consumption were observed, while the body weight gain and the rate of body weight gain were high compared to the treated control group. In addition, urinary pH and serum total protein were lower, and serum glucose and calcium levels were higher than in the treated control group, but these results were not considered to be due to the drug's toxicity. In the 20 and 10 g/kg/day groups, a slight decrease in food consumption was observed, though the rate of body weight gain was higher than in the treated control group. Slight decreases in urinary pH and serum total protein were observed, but were not considered to be due to the toxic effect of the drug. From the above results, it was concluded that the maximal non-effect dose of SF-1008C in oral administration was 30 g/kg/day, which was the maximally applicable dose in rats.

Administration, Oral↗