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Biomedical subjects

M Oka

Publications and source records attributed to M Oka.

At least 667 records · Page 37Linked to original sources
PubMed1985

Naviculo-cuneiform coalition. A report of two cases.

This solidus article reports on two unique cases of naviculo-medial cuneiform coalition in a 20-year-old man and a 22-year-old woman. In the first patient, arthrodesis was successful in relieving the localized pain, whereas in the second patient the pain gradually decreased without treatment.

Adult↗
PubMed1985

Differential effects of haloperidol decanoate, a long-acting neuroleptic, in behavioral and biochemical tests.

The pharmacological activities of haloperidol decanoate in several behavioral and biochemical tests for neuroleptics were pursued to validate its clinical mode of action. Haloperidol decanoate itself was about 40 times less potent than haloperidol in inhibiting 3H-spiperone binding to rat striatum in vitro and its direct application into the cerebral ventricle of mice showed no effect on brain concentrations of dopamine metabolites, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC). When injected intramuscularly, haloperidol decanoate exhibited various behavioral and biochemical effects together with prolonged accumulation of the parent drug haloperidol in dopamine-rich areas of the brain, but there was a clear difference in the time-course patterns of the effects. Conditioned avoidance responses in mice and rats were suppressed for a long period of days in the time-course pattern parallel to the elevation of brain haloperidol levels; the effect reached the peak a couple of days after the treatment and remained there over a week with gradual recovery towards 1 month after the injection. On the other hand, tolerance developed as rapidly as within 7 days to the antagonistic effects on apomorphine-induced stereotyped behaviours in mice and rats and to prolactin-releasing activity in rats. Biochemically, there was a regional difference in the brain in the time-course of effect of haloperidol decanoate. Namely, the initial increase in dopamine metabolites was no longer seen in the striatum on day 21, whereas it still persisted in the frontal cortex. Thus, the present study has confirmed on the one hand the assumption that haloperidol decanoate is a pro-drug which itself has no neuroleptic activity and validated on the other hand the clinical results that it exhibits long-lasting antipsychotic activities with minimum and tolerable extrapyramidal and prolactin-related side effects.

Animals↗
PubMed1985

[Gastrointestinal hormones and operations for achalasia of the esophagus and sliding esophageal hiatal hernia: their surgical significance].

Experimental achalasia dogs produced with Deloyer's method showed higher resting pressure at the gastroesophageal junction and the increase in LES pressure in response to tetragastrin and cholecystokinin. Dose-response curve of the LES to each dose of tetragastrin in achalasia dog shifted to the left. Resting LES pressure in 11 patients with achalasia was 42.73 +/- 23.31 cm H2O. It increased significantly after intramuscular injection of 5 micrograms/kg of tetragastrin and fluoroscopic observation showed the tonic contraction of the lower esophagus and cardia. After the performance of Jekler-Lhotka operation, LES pressure decreased to lower values sufficient to prevent the gastroesophageal reflux. Comparing 5 kinds of hiatal herniorrhaphies in dogs, LES pressure increased postoperatively in the following order: Nissen, Belsey Mark IV, Stensrud, Hill and Harrington methods. Responses to tetragastrin increased after Nissen and Belsey Mark IV methods. In 12 out of 21 clinical cases of sliding esophageal hiatal hernia who had undergone Nissen-Rossetti method adding fundopexy and posterior gastropexy, preoperative esophageal manometry showed HPZ of 24.98 +/- 8.87 cm H2O in peak value and 5.1 +/- 3.46 cm in length. Seven cases showed the biphasic pattern and 5 cases showed the negative response to tetragastrin. Postoperative manometry showed HPZ of 31.42 +/- 18.46 cm H2O in peak value and 4.5 +/- 1.73 cm in length. One case showed the biphasic pattern and 3 cases showed the negative response to tetragastrin.

Animals↗
PubMed1984

Co-storage and co-secretion of somatostatin and catecholamine in bovine adrenal medulla.

Co-storage and co-secretion of somatostatin (SRIF) and catecholamine (CA) were demonstrated using bovine adrenal medulla. In the experiment of retrograde perfusion system of isolated adrenal gland, the basal concentration of immunoreactive (IR)-SRIF was 20 pg/4 ml/min, but a significant increase of the value (142 pg/4 ml/min) was observed at 1-2 min after a brief infusion of acetylcholine (10 mM) and the marked release continued for over 6 min. Similar result was obtained for CA release. On gel-filtration chromatography of a soluble lysate of chromaffin vesicles prepared by differential and discontinuous sucrose density centrifugation, IR-SRIF was separated into three components with molecular sizes corresponding to prepro-SRIF (76.8% of the total immunoreactivity), SRIF28 (14.1%) and SRIF14 (9.1%).

Adrenal Medulla↗
PubMed1984

Development of morphologic heterogeneity of hepatocyte mitochondria in the mouse.

The ultrastructure of mitochondria in periportal and perihepatic hepatocytes from newborn, 5-, 10-, and 20-day-old, and adult male ddY mice was analyzed by quantitative electron microscopy. In newborn and 5- and 10-day-old animals, the axial ratio (length per diameter), surface to volume ratio (area of the outer membrane per unit mitochondrial volume), and volume density were not significantly different between periportal and perihepatic cells. In 20-day-old and adult animals, the surface to volume ratio was greater in perihepatic cells than periportal cells, and the volume density was greater in periportal cells than perihepatic cells. The axial ratio became greater in perihepatic cells than periportal cells in adult animals. However, there were no differences in the surface density of the outer membrane, and of the inner membrane and cristae between the cells of both zones in all age groups examined. When the data were expressed as volume and area per cell, the patterns of subacinar distribution and age-related changes differed from the patterns seen in the volume and surface density data mainly in adult animals. This difference was generally caused by the marked increase in hepatocyte volume between 20 days of age and adulthood, especially in perihepatic cells. The results show that differences between mitochondria in periportal cells and those in perihepatic cells in the shape (the axial and surface to volume ratios), volume density, and area of the outer membrane per cell, evident in adult animals, are not present in newborn animals but arise during postnatal development.

Animals↗
PubMed1984

Receptor-mediated endocytosis of glucagon in isolated mouse hepatocytes.

The binding of glucagon to the cell surface and the pathway of intracellular transport of the hormone in isolated mouse hepatocytes were studied by autoradiography, colloidal gold-labeled glucagon (Au-glucagon), and biochemical methods. In cells incubated with 1251-glucagon at 4 degrees C, the label was mainly localized to the plasma membrane even after 60 min of incubation. At 20 degrees C, the labeled ligand was internalized by the cells and the amount of internalized ligand increased with time of incubation. At 37 degrees C, the ligand was rapidly internalized and found to be associated with coated or uncoated vesicles. Au-glucagon experiments revealed clearly the process of internalization of glucagon. Au-glucagon bound to the plasma membrane was transported to coated regions and then internalized into vesicles via coated pits. Biochemical results supported these findings from autoradiography and Au-glucagon experiments. Thus, glucagon is internalized by hepatocytes via receptor-mediated endocytosis.

Animals↗
PubMed1984

Clinical and echocardiographic features of isolated severe pure mitral regurgitation.

Recent studies have shown that rheumatic heart disease is no longer the main cause of isolated severe pure mitral regurgitation. In this study, we evaluated various clinical and echocardiographic features found in the syndrome of mitral regurgitation. Our data is consistent with recent reports that mitral valve prolapse and coronary artery disease are now the predominant causes of mitral regurgitation and that rheumatic heart disease is a much less common etiology. In addition, our data suggest that clinical evaluation alone is usually very accurate in identifying the correct etiology. Various clinical and echocardiographic features found in the subsets of acute and chronic mitral regurgitation are described. Specifically, patients with acute mitral regurgitation were more likely to have echocardiographic evidence of segmental left ventricular dysfunction and flail mitral valve leaflet. In chronic mitral regurgitation, atrial fibrillation and left atrial dilatation were more commonly present. Echocardiography was found to be more useful in the detection of the complications of coronary artery disease rather than in identifying its presence. Patients with a New York Heart Association classification of IV and those with echocardiographic evidence of an increased left ventricular endsystolic dimension or left ventricular hypertrophy had a worse prognosis.

Adolescent↗
PubMed1984

Glutathione and selenium in rheumatoid arthritis.

The concentration of selenium in serum (S-Se) was studied in 20 patients and glutathione in erythrocytes (E-GSH) in 16 patients with rheumatoid arthritis (RA) at onset and after 3 and 6 months of antirheumatic therapy with aurothiomalate (19 cases) or with D-penicillamine (one case). The values were compared to those of age and sex matched healthy controls. S-Se was significantly (p less than 0.01) lower in RA patients at the onset of the trial, but increased to the level of the controls during the follow-up. On the other hand, there was no difference in E-GSH between the patients and their controls before the onset of antirheumatic medication but the increase in E-GSH of RA patients during the trial was highly significant (p less than 0.001). Nevertheless, neither S-Se nor E-GSH correlated to changes in clinical or laboratory indicators of disease activity or to the development of new erosions in X-ray. It is concluded that changes in rheumatoid activity or disease progress occur independently of changes in S-Se or E-GSH.

Adult↗
PubMed1984

Trypanosoma gambiense: immunosuppression and polyclonal B-cell activation in mice.

The relationship between the suppression of antibody response and polyclonal B-cell activation was studied in mice treated with a cell homogenate of Trypanosoma gambiense. The cell homogenate injection in mice caused a progressive increase in splenic background plaque-forming cell response to sheep erythrocyte. In the mice with markedly increased background plaque-forming cell response, the different reactivity in the primary antibody response to sheep erythrocytes was observed between the intraperitoneal and intravenous immunization with sheep erythrocytes. The intraperitoneal immunization of mice with sheep erythrocytes strongly suppressed the antibody response, while the intravenous immunization with sheep erythrocytes led to an enhancement of the antibody response. The intraperitoneal injection of silica particles, a toxic agent to macrophages, 30 min before intraperitoneal immunization with sheep erythrocytes abolished the suppression of the antibody response completely. In addition, restoration of the suppressed antibody response was found in mice immunized intraperitoneally with a high dose of sheep erythrocytes. It appears that the suppression of antibody response is not attributable to polyclonal B-cell activation, and is associated with the elevation of the phagocytic activity of peritoneal macrophages.

Animals↗
PubMed1984

Fine structural alterations in Trypanosoma rhodesiense grown in vitro, treated with WR 163577.

Fine-structural alterations in Trypanosoma rhodesiense trypomastigotes exposed to WR 163577, a prophylactic agent against animal African trypanosomiasis, were determined from cells grown in vitro. Exposure of trypomastigotes to a low concentration of drug resulted only in condensation of kinetoplast DNA fibrils. Exposure to higher drug concentrations caused clumping of nuclear chromatin and of cytoplasmic contents. Although alteration of kinetoplast DNA is the first detectable drug-induced change, the function of the kinetoplast in mammalian forms of African trypanosomes is unclear, and the secondary changes in the nucleus and cytoplasm may constitute the functionally significant alterations caused by WR 163577.

Aminoquinolines↗
PubMed1984

Ultrastructural localization of protective antigens of Plasmodium yoelii merozoites by the use of monoclonal antibodies and ultrathin cryomicrotomy.

The production of two hybridoma cell lines secreting monoclonal antibodies (MAb), both of which react specifically with erythrocytic merozoites of Plasmodium yoelii in the indirect immunofluorescence assay, has been reported earlier. MAb 25.77 was reactive with a localized region within each merozoite, while MAb 25.1 appeared to be specific for the plasma membrane of schizonts and merozoites. The parasite antigens recognized by antibodies 25.77 and 25.1 are proteins of 235,000 and 230,000 molecular weight, respectively, both of which induce protective immunity against P. yoelii in mice. In order to establish the precise localization of these protective antigens within erythrocyte merozoites, ultrathin cryomicrotomy was used in conjunction with the MAb and protein A-gold. This technique showed that gold particles were exclusively concentrated over the rhoptries when erythrocytic merozoites were incubated with MAb 25.77. On the other hand, gold particles were distributed uniformly over the merozoite surface when parasites were incubated with MAb 25.1. These results demonstrate, for the first time, that a protective antigen of the erythrocytic stage of P. yoelii is localized within the rhoptries as well as on the merozoite surface.

Animals↗