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Biomedical subjects

H Ohyama

Publications and source records attributed to H Ohyama.

At least 127 records · Page 7Linked to original sources
PubMed1980

[Gastric perforation in ventriculo-peritoneal shunt--a case report (author's transl)].

The case is a 69-year-old female who was admitted to our hospital under the diagnosis of normal pressure hydrocephalus secondary to cerebral infarction. V-P shunt was performed and postoperative course was uneventful until 7 months after operation, when she developed meningitis. Since then the level of consciousness became gradually worse down to akinetic mutism. Two years and 3 months after the operation she died of pneumonia. At autopsy peritoneal end of the shunt tube was found to have perforated the antero-inferior wall of the stomach. In this report, we discussed the mechanism of development of bowel perforation and preventive measures against this complication. As the causative factors it should be noted first that any foreign body in the peritoneal cavity is potentially able to cause bowel perforation. The second factor is the sharp tip of the peritoneal tube which perforates the bowel more easily. The third factor is the constant pressure at the same site of the bowel wall over a long period of time to cause necrosis of it. The fourth factor is the poor general condition of the patient with decreased resistance of the bowel wall against the foreign body. We therefore postulate for the prophylaxis and early diagnosis of this complication that a careful procedure with adequate tube is required at operation and a low grade fever and abdominal symptoms should not be overlooked afterward.

Aged↗
PubMed1980

[Electrical activity of the dorsal hippocampus during DRL learning in the rabbit (author's transl)].

The change of electrical activity of the dorsal hippocampus during differential reinforcement of low rate (DRL) learning was examined in six rabbits. Bipolar electrodes were implanted stereotaxically into the dorsal hippocampus (3 mm posterior to bregma, 4-4.5 mm lateral and 7-7.5 mm ventral from bregma). After completion of continuous reinforcement learning, the animals learned DRL on a 10 sec. schedule. Rhythmic theta waves (6-8 Hz, 0.6-1.5 mV) were predominant in the early sessions of the DRL schedule. With further sessions, regular theta waves decreased and desynchronized waves or slightly irregular theta waves increased especially during the 10 second waiting period. Contrary to the report of Bennett et al., synchronized waves were always seen from 1-2 sec. before lever-press until completing of lever-press. Moreover, these preceding synchronized waves became more pronounced and of higher frequencies (8-10 Hz.) as learning proceeded. These high frequency regular waves (alpha-bursts) were seen in 5.6-35.8% of reinforced lever-press in the 10th session, and 79.5-93.8% in the 60th session. Alpha bursts were sometimes seen after 8-9 sec. waiting in the later sessions, but never seen within five secs.. During the extinction of DRL learning, the occurrence rate of alpha-bursts on adequate but non-rewarded lever-pressing decreased. These results cannot be explained satisfactorily in terms of an association between synchronized waves and voluntary movement. Frequency increase was seen when rabbits expected reinforcement after waiting for about 10 sec. or more. These results indicate that frequency increase of hippocampal synchronized waves is seen in association with higher central processing, most likely with memory.

Alpha Rhythm↗
PubMed1978

Collagenolytic activities of cultured human malignant melanoma cells.

Three human malignant melanomas were cultured in pure populations and one tumor was cloned into melanotic and amelanotic cell lines. In the homogenates of these cultured cells, specific collagenase activities were demonstrated by isotope release from 14C-labeled collagen, disc electrophoresis, and specific cleavage of collagen molecules as demonstrated in the segment long spacing form. No significant collagenase activity was observed in the culture media. Interestingly, early cultures had a high collagenase activity in the cells and as they were successively subcultured, the activity diminished. Cysteine completely inhibited the degradation of tropocollagen as determined by disc electrophoresis and EDTA partially inhibited the degradation. It is concluded that human malignant melanoma cells produce a specific collagenase in vitro which can be extracted in early culture directly from the homogenate.

Adult↗
PubMed1977

Collagenase of human skin basal cell epithelioma.

Collagenase of human basal cell epithelioma was purified by sequential ammonium sulfate precipitation, Sephadex gel filtration and affinity chromatography on collagen-polyacrylamide gel. The collagenase, when partially purified, was found to have an approximate molecular weight of 50,000. The purified enzyme contained no caseinolytic activity. On polyacrylamide gel electrophoresis, the purified enzyme gave a single protein band. The purified collagenase cleaved native acid-soluble guinea pig skin collagen at 37 degrees C with a pH optimum of 8. The enzyme was inhibited by EDTA, cysteine, and human serum but not by soybean trypsin inhibitor. Heparin did not stimulate the enzyme activity. Purified collagenase reduced the specific viscosity of native acid-soluble guinea pig skin collagen to 50 per cent of its original value at 27 degrees C. Polyacrylamide gel disc electrophoresis of the reaction products showed bands corresponding to alphaA, betaA, and alphaB fragments. Electron microscopic examination of SLS aggregates of the reaction products showed that the cleavage site by the enzyme was at a point 75 per cent from the "A" end (TCA75) and 25 per cent from the "B" end (TCB25) of the collagen molecule.

Binding Sites↗
PubMed1976

Effect of vitamin B6 deficiency on collagen metabolism in rats.

The effects of VB6 deficiency on collagen metabolism were studied using young and adult rats. It was observed in VB6 deficient rats, that both the amount of urinary hydroxyproline and salt soluble fraction of skin collagen decreased. Furthermore, decrease of the alpha-component and increase of the beta-component were also found in the soluble collagen. However, the activity of plasma amine oxidase was lower and the aldehyde content in the acid soluble collagen were also lower than the control group. These changes were revealed more clearly in young growing rats than in adult rats. Based on these results, it may be that VB6 participates in the allysine (alpha-amino-adipic-delta-semialdehyde) formation which is considered as the first step of collagen maturation and also in the synthesis of protocollagen peptide chains.

2-Aminoadipic Acid↗