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Biomedical subjects

N Murayama

Publications and source records attributed to N Murayama.

212 records · Page 12Linked to original sources
PubMed1977

A pharmacokinetic model to study the excretion of trichloroethylene and its metabolites after an inhalation exposure.

For a better understanding of absorption, distribution, excretion, and metabolism of trichloroethylene the time-course of blood concentration of the vapour and urinary excretion of its metabolites was examined using a pharmacokinetic model. After a single experimental exposure in which four men inhaled 100 parts per million (ppm) of trichloroethylene for four hours an elimination curve showed three exponential components, that is, X=1-0005e(-16.71t)+0-449e(-1.710t)+0-255e(-0.2027t), where X is that blood concentration in mg/l and t the time in hours from 0 to 10. The overall rate constant for the disappearance of trichloroethylene was found to a agree with the theoretical one, estimated by means of a mathematical model for the blood concentration data. A D8- XD plot, developed from a mathematical model for urinary excretion, could also give a good estimate of rate constant for the transfer of trichloroethylene in the body. The rate constant thus estimated from urinary excretion was consistent with data on the blood concentration.

Adult↗
PubMed1977

[Clindamycin-2-phosphate and surgical infections (author's transl)].

Blood levels of clindamycin-2-phosphate in dog at dosis of 10 mg/kg body weight showed the maximum of 21 mug/ml 30 seconds after one-shot i.v. administration. Continuous infusion of the antibiotic at the infusion speed of 150 and 300 ml/hour/10 kg b.w. with 6 mg/ml solution maintained blood levels of 30 and 170 mug/ml respectively. It may be recommended clinically to use lower concentration than 6 mg/ml to avoid cardiocirculatory disturbances. Four cases of surgical mixed infections with gram-positive cocci, gram-negative bacilli and anaerobes were treated with clindamycin-2-phosphate at a daily dosis of 1,200 mg intravenously and 2 of 4 cases revealed good clinical response. There was none of the haematological, hepatic, nephrontic, cardiocirculatory and allergic side effects.

Abscess↗
PubMed1975

Kinetic studies on sex difference in susceptibility to chronic benzene intoxication--with special reference to body fat content.

The sex difference in the susceptibility to haematopoietic disorders induced by benzene was studied kinetically with a special reference to its relation with the body fat content. In rats of both sexes with a large body fat content, benzene was eliminated more slowly and remained in the body for a longer time than in rats with a small body fat content. In accord with this finding, the decrease in white blood cell numbers during a chronic benzene exposure was observed only in the groups of rats which had a large volume of fat tissue. In an experimental human exposure, the elimination of benzene was slower in the females than in the males. The kinetic study revealed that the slower elimination in the females is due primarily to the bulky distribution of body fat tissue in that sex. From these results obtained from the experimental exposure of men and rats to benzene, it was concluded that the human female, with her massive body fat tissue, shows an inherent disposition to be susceptible to a chemical such as benzene which has a high affinity with fat tissue.

Adipose Tissue↗
PubMedDate not supplied

Proton magnetic resonance spectroscopy on childhood-onset dentatorubral-pallidoluysian atrophy (DRPLA).

To evaluate brain dysfunction of childhood-onset dentatorubral-pallidoluysian atrophy (DRPLA), three children with progressive myoclonus epilepsy, who were diagnosed as having DRPLA by DNA analysis, for the first time, underwent a study of proton magnetic resonance spectroscopy (1H-MRS). 1H-MRS obtained from both the parietal and basal ganglia regions disclosed markedly reduced ratios of N-acetylaspartate to both choline and creatine. Especially regarding the basal ganglia region, the latter (ratio of N-acetylaspartate to creatine) closely correlated to severity of genetic abnormality, i.e. number of expanded CAG repeats, suggesting that the degree of neuronal loss in the region strongly depends on genetic factors. 1H-MRS must be a valuable tool to clarify the pathophysiology of DRPLA.

Adolescent↗
PubMedDate not supplied

Characteristic evoked potentials in childhood-onset dentatorubral-pallidoluysian atrophy.

To determine the characteristics of multimodal evoked potentials (MEPs) in childhood-onset dentatorubral-palli-doluysian atrophy (DRPLA) we studied three DRPLA patients with progressive myoclonus epilepsy. Brainstem auditory evoked potentials showed reduced or absent brainstem components as well as delayed latencies. In addition, short latency somatosensory evoked potentials (S-SEPs) had prolonged central conduction time and reduced amplitude of cortical components. Two patients with symptom onset in the first decade of life had extremely enlarged flash visual evoked potentials with shortened latency even in the absence of giant SEPs. Therefore, children with progressive myoclonus epilepsy and the above MEP findings are likely candidates for childhood-onset DRPLA and should undergo DNA analysis for DRPLA.

Adolescent↗
PubMedDate not supplied

Surgical and radiotherapy treatment of a spinal cord ependymoma in a dog.

A 4-year-old Beagle dog was presented for investigation of a left pelvic limb gait abnormality. Neurolocalisation indicated a lumbar (L2 to L5) spinal cord lesion. On magnetic resonance imaging (MRI), an intramedullary mass was demonstrated at L3. The mass was partially removed under general anaesthesia and a diagnosis of ependymoma was made on histological examination. The dog was treated with postoperative orthovoltage x-ray radiation (total dose; 44 Gy given in 11 fractions over a 4 week period) combined with low dose carboplatin (25 mg/m2). The dog was alive 16 months after surgery without further neurological deficits. No further tumour growth was detected on subsequent MRI evaluations.

Animals↗
PubMedDate not supplied

Marked atherosclerosis in a patient with familiar lecithin: cholesterol acyltransferase deficiency associated with end-stage renal disease and diabetes mellitus.

Familial lecithin:cholesterol acyltransferase (LCAT) deficiency is a rare genetic disorder of the lipid metabolism caused by the absence of LCAT activity in plasma. It is not generally accompanied by atherosclerosis in spite of low high-density lipoprotein cholesterol levels nor by diabetes mellitus. However, reports of long-term follow-up or autopsy findings are rare, and the true incidence of atherosclerosis in LCAT deficiency is not clear. We report on the long-term observation of a patient with familial LCAT deficiency who developed renal failure, diabetes mellitus, and marked atherosclerosis. The patient died of sepsis from foot ulcers 7 years after starting hemodialysis and 13 years after the diagnosis. Marked atherosclerosis characterized by medial calcification in small arteries was observed at autopsy. The genesis of the atherosclerosis seemed to be on the basis of a combination of factors.

Arteriosclerosis↗
PubMedDate not supplied

Effects of omeprazole on rat gastric mucus glycoproteins with acetylsalicylic acid-induced gastric damage.

Investigations were carried out to determine the effects of omeprazole on mucus glycoprotein in rat gastric mucosa. Quantitative and qualitative changes in mucus glycoprotein, isolated from omeprazole-treated rats with or without acetylsalicylic acid-induced gastric damage, and the degree of gastric mucosal injury were studied. Omeprazole, in a dose-dependent manner, prevented macroscopical mucosal damage induced by acidified acetylsalicylic acid. A considerable decrease in corpus mucus glycoprotein (54%) and antral mucus glycoprotein (72%) was observed in acetylsalicylic acid-treated rats and acetylsalicylic acid reduced the amounts of fucose and galactose of corpus mucus glycoprotein. Pretreatment with omeprazole partially restored a quantitative reduction and a qualitative change of carbohydrate portion in corpus mucus glycoprotein induced by acetylsalicylic acid. A single administration of a high dose of omeprazole (200 mumol/kg) also induced the reduction of corpus mucus glycoprotein content (82%), although no changes in the carbohydrate component were observed. The decrease in corpus mucus glycoproteins induced by omeprazole might be due to a cause different from that of acetylsalicylic acid-induced mucus glycoprotein reduction.

Animals↗
PubMedDate not supplied

Interaction of forskolin with vasopressin-sensitive cyclic AMP system in renal medullary tubules.

The medullary collecting tubules (MCT) and the medullary thick ascending limb of Henle's loop (MAL) are two major sites of [8-Arg]-vasopressin (AVP) action, via cyclic AMP, on the mammalian nephron. In the present study, the effect of forskolin and forskolin in combination with AVP on accumulation of cyclic AMP in tubular segments of MAL and MCT microdissected from rat kidney was examined in vitro. Under all tested conditions, forskolin stimulated the accumulation of cyclic AMP to a greater degree in MCT than in MAL. In MAL, the effects of forskolin and AVP were synergistic; the increase in cyclic AMP after incubation with forskolin and AVP added together was 150% greater than the arithmetic sum of the increases elicited either by AVP or by forskolin alone. On the other hand, in MCT the stimulatory effects of AVP and forskolin were strictly additive. These results suggest that an intramembranous arrangement of AVP-sensitive adenylate cyclase complex differs in two types of epithelial cells located in the same tissue. The potentiating effect of forskolin on AVP-stimulated cAMP generation in MAL can be helpful in experimental studies of AVP-sensitive cyclic AMP metabolism in this nephron segment, which has a variable sensitivity to AVP in the kidneys of diverse mammalian species.

Animals↗