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Biomedical subjects

Y Ohira

Publications and source records attributed to Y Ohira.

At least 19 recordsLinked to original sources
PubMed1992

Rat soleus muscle fiber responses to 14 days of spaceflight and hindlimb suspension.

Morphological and enzymatic responses in fibers expressing fast, slow, or both types of myosin heavy chain (MHC) were studied in rats after 14 days of spaceflight (COSMOS 2044) or hindlimb suspension. Although the percentage of slow-twitch fibers was unchanged, a higher percentage of fibers that expressed both slow and fast MHC was observed in flight and suspended rats than in synchronous ground-based controls. The soleus was 25 and 34% smaller than control after 14 days of flight and suspension, with the reduction in fiber cross-sectional area (CSA) being greater in slow- than in fast-twitch fibers in both experimental groups. The activities of succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPD) were not significantly affected by flight or suspension. The total SDH activity (i.e., SDH activity x CSA) decreased significantly in the slow-twitch fibers of the flight and the fast-twitch fibers of the suspended rats, in large part due to fiber atrophy. A shift in MHC expression in 14 and 9% of the fibers in flight and suspended rats occurred without a change in myosin adenosinetriphosphatase activity. The SDH and GPD activities of the fibers that expressed both slow and fast MHC were slightly higher than the slow-twitch fibers and slightly lower than the fast-twitch fibers. These data indicate that events were initiated within 14 days of spaceflight or suspension that began to reconfigure the protein profiles of 9-14% of the slow-twitch fibers from typical slow-twitch toward those of fast-twitch fibers, while all fibers were dramatically losing total protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1992

Adaptation of fibers in fast-twitch muscles of rats to spaceflight and hindlimb suspension.

The adaptation of single fibers in medial gastrocnemius (MG), a fast-twitch extensor, and tibialis anterior (TA), a fast-twitch flexor, was studied after 14 days of spaceflight (COSMOS 2044) or hindlimb suspension. Cross-sectional area (CSA) and succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosinetriphosphatase (ATPase) activities were determined in fibers identified in frozen serial cross sections. Fibers were categorized as light, dark, or intermediate on the basis of myosin ATPase staining and alkaline preincubation and immunohistochemically as reacting with slow, fast, or both slow and fast myosin heavy chain monoclonal antibodies. Because there was a close relationship between these two means of categorizing fibers, all fibers were categorized on the basis of the immunohistochemical reaction. The percentage of slow- and fast-twitch fibers of the MG and TA were unchanged in either group. Mean fiber size of all fibers, irrespective of type, was unaffected in either muscle after flight or suspension. The fibers that expressed both fast and slow myosin heavy chains were smaller than control in the MG of both experimental groups. Compared with control, the SDH and total SDH activities in the MG were significantly less in suspended rats, with the fast-twitch fibers showing the largest difference. The ATPase activity in the MG was higher in flight than in control or suspended rats. There were no significant effects of flight on fibers of the TA. In contrast, the TA in suspended rats had higher GPD activities than either control or flight rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1992

Muscle metabolism during exercise: anaerobic threshold does not exist.

Blood lactate level begins to increase at a certain work load or oxygen consumption which is called as anaerobic threshold (AT). However, numerous studies showed that anaerobic glycolysis is not the cause of the enhanced accumulation of blood lactate during exercise. Increased lactate production is seen even in fully aerobic muscles. Some studies suggest that elevation of lactate is due to a temporary imbalance between the rates of pyruvate formation by aerobic glycolysis and pyruvate utilization in the Krebs cycle. These results clearly suggest that AT does not exist.

Anaerobic Threshold↗
PubMed1991

Reduced growth of Ehrlich ascites tumor cells in creatine depleted mice fed beta-guanidinopropionic acid.

The effect of implantation of Ehrlich ascites tumor (EAT) cells on creatine distribution was investigated. It was also studied how depletion of creatine by feeding creatine-analogue beta-guanidinopropionic acid (beta-GPA) affects the growth of EAT cells in mice. Enhanced mobilization of creatine from host tissues to EAT cells against a greater concentration gradient was observed. The creatine (but not creatinine) level in blood plasma was lowered to 22% of the normal value by beta-GPA feeding alone and assimilation of 14C-creatine into EAT cells was inhibited. The growth of EAT cells was significantly reduced and the duration of survival of mice after implantation of EAT cells was extended when the creatine concentration was decreased. A decrease in daily food consumption and the degree of muscle atrophy after implantation of EAT cells was less in beta-GPA than control groups. In the creatine-depleted mice, the rate of increase in total EAT cell number and the volume of abdominal ascites were approximately half of the control values, and more dead EAT cells were observed. These results suggest that supplementation of beta-GPA inhibits creatine transfer to EAT cells and reduces the growth of cancer cells.

Administration, Oral↗
PubMed1991

Structure and mineral content in weight-bearing bones following hindlimb suspension in young rats.

Responses of structure and mineral content in weight-bearing bones to 1-week hindlimb suspension were studied in growing rats. The weight, volume, and length of femur, tibia, and fibula were less in suspended rats than cage controls, although there was no significant difference in the weight/volume ratio. The diameter of mid-shaft, the thickness of cortical bone, and the ratio of cortical bone thickness to femur diameter were significantly less in the suspended rats. The width of marrow space showed no differences, suggesting that the cortical bone was mainly affected. The sum of mineral content and the mineral content per diameter in the cross section of femurs were decreased following suspension, suggesting a change in the internal structure of cortical bone. Data also indicated that the reduction of femur diameter was caused by decreased thickness which is accompanied by the decreased mineral content of the cortical bone. It was suggested that there is a close relationship between the responses of bones and muscles to hindlimb suspension of young rats, although the degree of weight loss was greater in muscles than in bones.

Animals↗
PubMed1991

[A case of bilateral sudden hearing loss and vertigo caused by bilateral temporal bone metastasis from pancreatic carcinoma--comparison of clinical findings and temporal bone pathological findings].

We report temporal bone pathology in a 25-year-old man with bilateral temporal bone adenocarcinoma which was caused by metastasis from a primary lesion in the pancreas. The initial symptoms began with vertigo and headache and the patient noticed left hearing loss in the left ear on the following day. A few days later, he noticed hearing loss in the right ear, and bilateral hearing was totally lost within two weeks of the onset. In addition to severe bilateral sensorineural hearing loss, left IInd, bilateral Vth and VIIIth cranial nerve paralysis occurred. Brain CT showed multiple metastatic lesions in the brain. The patient's general condition rapidly deteriorated, and he died of acute pneumonia on the 42nd day after onset. At autopsy it was revealed adenocarcinoma of the tail and body of the pancreas and its metastasis to the brain and meninges. Pathological study of the temporal bone showed infiltration of carcinomatous cells along the VIIth and VIIIth nerves in the bilateral internal auditory canals.

Adenocarcinoma↗
PubMed1991

[Gallbladder function and CCK after gastrectomy].

Postgastrectomy cholelithiasis has become a problem and biliary tract dyskinesia has been cited as an etiologic factor. CCK is the most important gut hormone with respect to biliary tract function, so we conducted an experimental study of postgastrectomy gallbladder function and CCK levels which gave the following results: 1. Although postprandial gallbladder contraction for the most part occurred in response to endogenous CCK, another mechanism (the gastro-cholecystic reflex) seemed to be responsible for some of them. 2. The postgastrectomy decrease in postprandial gallbladder contraction appeared to be due to disappearance of this gastro-cholecystic reflex. 3. Gallbladder contraction occurred in association with postprandial CCK secretion following total gastrectomy and Roux-en-Y reconstruction, but the altered food passage route caused changes in the dynamics of CCK secretion, and this is believed to have had an influence on the gallbladder contractile response.

Animals↗
PubMed1979

Iron-deficiency anaemia and its effect on worker productivity and activity patterns.

The effects of iron-deficiency anaemia on workers productivity were studied in a tea plantation in Sri Lanka. The quantity of tea picked per day was studied before and after iron supplementation or placebo treatment. After one month's treatment significantly more tea was picked when the haemoglobin (Hb) concentration was increased by iron supplementation than when it was not. The degree of improvement was greater in more-anaemic subjects (those with concentrations of 6.0-9.0 g Hb/dl). The level of physical activity of anaemic subjects in their everyday environment was also recorded for four or 24 hours continuously both before and after treatment. After three weeks these levels was significantly greater in the iron-treated than matched placebo-treated subjects. The economic implications of increased work productively with iron treatment are evident, particularly in developing countries. These results also provide strong evidence for the clinical impression that people with iron-deficiency anaemia suffer from tiredness and weakness.

Adult↗
PubMed1979

Work capacity, heart rate and blood lactate responses to iron treatment.

Changes in haemoglobin (Hb), work performance, heart rate and postexercise blood lactate were studied in iron deficient, anaemic subjects for 16 d following total dosage infusion of iron dextran, i.v. (30-50 ml). Six adult men and 14 women were subjects with initial Hb levels of 6.6 +/- 0.6 g/dl (mean +/- SEM) for the iron treatment group (n=10) and 8.0 +/- 0.7 for the placebo group (saline infusion, n=10). Serum levels were 0.51 +/- 0.15 and 0.67 +/- 0.12 mg/l for the two groups, respectively. Haemoglobin and maximal work time increased significantly within 4 d after iron treatment and continued to increase up to 16 d. No changes were found in the placebo subjects. Heart rates at a given exercise intensity were lower in the iron treatment group than in control subjects who had the same Hb levels but had not been treated with iron. Post-exercise venous blood lactate was similar on succeeding days after iron treatment even though the subjects reached higher work loads. These results demonstrate the treatment of iron deficient, anaemic subjects with iron dextran results in improved work capacity within 4 d and a lower heart rate at a given work load after treatment which cannot be accounted for totally by the elevation of Hb concentration.

Adult↗
PubMed1977

Correction of water content and solute concentration in blood during hemoconcentration.

Eleven, healthy male students were subjected to an exhaustive bicyle ergometer exercise. Many parameters of hemoconcentration were examined in blood and urine samples which were collected before and after exercise. In an exercise lasting approximately 10 min, it was found that serum total protein (STP) would be a suitable parameter that could be used to calculate water content and actual decrease in water volume in blood due to exercise. Further, it is described how STP values before and during hemoconcentration can be used to eliminate the effect of plasma water loss from the determined values of various solute levels in blood.

Adult↗
PubMed1977

Hemoconcentration during isotonic handgrip exercise.

Three healthy males performed an intense isotonic handgrip ergometer exercise to exhaustion (approximately 10 min). Serum water, serum total protein (STP), and hematocrit were determined in the venous blood taken from the brachial veins in both exercised and nonexercised arms before exercise and 10 s, 1, 2, and 3 min after the termination of exercise. Although no sweat was observed, hemoconcentration occurred in both arms. The peak degree of water loss in the nonexercised arm, however, was delayed and lower than that in the exercised arm. Further, three healthy males were exposed to a sauna (76 degrees C) for 20 min to test the effect of sweating on hemoconcentration in the absence of physical movement. Venous blood was withdrawn from the forearm vein before the sauna, after 5 min in the sauna, and at 3 and 30 min during sitting recovery period. No hemoconcentration was observed during the course of the experiment.

Adult↗