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Biomedical subjects

M Koga

Publications and source records attributed to M Koga.

At least 397 records · Page 22Linked to original sources
PubMed1987

Demonstration of specific dopamine receptors on human pituitary adenomas.

Dopamine receptors on human pituitary adenoma membranes were characterized using [3H] spiperone as the radioligand. The specific [3H]spiperone binding sites on prolactin (PRL)-secreting adenoma membranes were recognized as a dopamine receptor, based upon the data showing high affinity binding, saturability, specificity, temperature dependence, and reversibility. All of 14 PRL-secreting adenomas had high affinity dopamine receptors, with a dissociation constant (Kd) of 0.85 +/- 0.11 nmol/l (mean +/- SEM) and a maximal binding capacity (Bmax) of 428 +/- 48.6 fmol/mg protein. Among 14 growth hormone (GH)-secreting adenomas examined, 8 (57%) had dopamine receptors with a Kd of 1.90 +/- 0.47 nmol/l and a Bmax of 131 +/- 36.9 fmol/mg protein. Furthermore, 15 of 24 (58%) nonsecreting pituitary adenomas also had dopamine receptors with a Kd of 1.86 +/- 0.37 nmol/l and a Bmax of 162 +/- 26.0 fmol/mg protein. These results indicate that some GH-secreting adenomas as well as some nonsecreting pituitary adenomas contain dopamine receptors. But their affinity and number of binding sites are significantly lower (P less than 0.05) and fewer (P less than 0.001) respectively, than those in PRL-secreting adenomas.

Adenoma↗
PubMed1987

A case of virilizing adrenocortical carcinoma.

A 36-year-old woman who had experienced two pregnancies consulted our hospital, because of scant menses and virilization. A 24-hour excretion of 17-ketosteroids and 17-hydroxy-corticosteroids demonstrated a decrease in 11-hydroxylase. A computed tomogram showed a huge inhomogenous tumefaction in the left adrenal. Left selective renal angiography revealed a large adrenal tumefaction. Selective adrenal venous samplings revealed that testosterone and dehydroepiandrosterone (DHA) were produced in response to stimulation by 0.25 mg exogenous adrenocorticotropic hormone (ACTH). After left adrenalectomy was performed, a diagnosis of adrenocortical carcinoma was made by pathological examination. This is the first report of a patient with a virilizing adrenocortical carcinoma, which produced testosterone and DHA in response to exogenous ACTH stimulation.

17-Hydroxycorticosteroids↗
PubMed1987

[Intraoperative autotransfusion in aortic aneurysm operations combined with temporary external shunt].

Intraoperative autotransfusion was done in nine patients who underwent major vascular surgery for thoracic aortic aneurysms including one total abdominal aneurysm using temporal external shunt. After general heparinization (1mg/kg), shed blood was collected by Sorenson Autotransfusion System with local heparinization. After confirming ACT longer than 300-400 second, 425-3700 ml, averaged 1804 ml, of shed blood was reinfused to the patients by gravity flow. The reinfusion rate of shed blood was 43.1 +/- 15.8%. There were no deaths and no complications referable to autotransfusion. Although mild hemolysis was observed immediately after surgery, plasma free hemoglobin level returned to normal in the first operative day and no renal failure occurred. The volume of bleeding after surgery was not differed from that of control. Microembolism was not evident clinically. We concluded that intraoperative autotransfusion is safe and useful procedure in major vascular surgery if proper anticoagulation is done.

Adult↗
PubMed1987

[Surgery of the patients on anticoagulants following prosthetic valve replacement].

The surgical operations including 5 cholecystectomies, gastrectomy, and graft implantation for abdominal aortic aneurysm were performed on 7 patients 2 to 98 months after valve replacement. Sodium warfarin was routinely used in an amount to reduce the prothrombin activity in a range of 20-30% normal by thrombotest. In all cases, anticoagulants were reduced in doses gradually in the period of 4 to 15 days proceeding to the operation. Heparin therapy was instituted for the prevention of thromboembolism, when prothrombin activity recovered to 50% normal by thrombotest, in 5 of 7 cases. Heparin therapy was interrupted just prior to operations and it was reinstituted soon after operations in 6 cases. Heparin therapy was maintained by continuous intravenous infusion to produce ACT of 130 to 150 seconds. Heparin therapy was stopped when prothrombin activity reached a therapeutic level with sodium warfarin. There were two episodes of hemorrhage required blood transfusion, observed in patients receiving heparin therapy, but there was no thromboembolism. We believe that our method which minimizes the nonanticoagulated time appears safe and effective in patients with prosthetic heart valves who require noncardiac operations.

Anticoagulants↗
PubMed1986

[Distribution and morphological characterization of chemical substances in environment. 2. Analysis of trace organic compounds in the aquatic environment].

In section 2, the presence and occurrence of organic compounds in the aquatic environment were investigated by means of gas chromatography-mass spectrometry (GC/MS) and high performance liquid chromatography (HPLC). Following chapters are included in this section. Introduction Detection and identification of trace organic compounds in tap water. Determination of trace aliphatic amines in water by GC/MS. Determination of trace aliphatic amines in water by HPLC. Fractionation of pollutants by HPLC.

Amines↗
PubMed1986

Biochemical and immunological characterization of estrogen binding components in human neoplastic adrenocortical tissues.

The estrogen binding components in human adrenocortical tissues were examined. Two adrenocortical cancer cytosols were found to contain the binder with a relative low affinity (Kd 5 X 10(-9) M) for estradiol. The association of [3H]estradiol to these cytosols was inhibited by a large dose of unlabeled estrone, estradiol or estriol, but neither by diethylstilbestrol nor by dihydrotestosterone. Incubation of cultured cells derived from these cancers with [3H]estradiol also showed the presence of this low-affinity estradiol binder. The addition of bovine serum albumin into these cytosols surprisingly resulted in a marked increase in estradiol binding capacity in a concentration-dependent manner. This component sedimented at 5 S in the low salt sucrose density gradient. This binding ability was found to be heat-labile in the absence of estradiol, but preformation of complexes with estradiol markedly stabilized its binding ability against thermal inactivation. In addition, experiments using monoclonal antibodies to human estrogen receptor revealed that the estrogen binder from one adrenocortical cancer cytosol shared antigenic determinants with human estrogen receptor. These results suggest that the unique estrogen binder in some adrenocortical cancer has the characteristics similar to estrogen receptors in terms of thermal stability and immunological cross-reactivity to antibodies.

Adrenal Cortex Neoplasms↗
PubMed1986

Ethylene oxide neuropathy in rats. Exposure to 250 ppm.

In Wistar rats subjected to a 6-h exposure to ethylene oxide at the concentration of 250 parts per million once, 5 times a week for 9 months, histopathologic studies of myelinated fibers of the proximal sural, distal sural and peroneal nerves and of the fasciculus gracilis at the 5th thoracic and 3rd cervical segments of the spinal cord were performed to observe whether ethylene oxide of such a concentration would lead to degeneration of primary sensory neurons. Throughout the study, no definite abnormality of the gait or posture was observed in both control and test rats. Qualitative histologic studies disclosed preferential distal axonal degeneration of myelinated fibers in both sural nerves and gracile fascicles in the test rats, although the extent of the distribution and the severity of the degenerative findings were variable. Such findings are consistent with mild axonal degeneration found among patients suffering from ethylene oxide toxicity. Therefore, in rats, exposure to 250 ppm ethylene oxide produces central-peripheral distal axonal degeneration of primary sensory neurons.

Animals↗
PubMed1986

An autopsy case of chronic nodular encephalomyelitis simulating neuro-Behçet syndrome.

A 29-year-old man suffered from neurological symptoms such as urinary disturbance, changes in personality, gait and speech disturbances, amnesia, myoclonus, dysphagia and muscle atrophy for nine years with exacerbations and remissions. A postmortem examination revealed many inflammatory and necrotic foci in the brain and spinal cord, especially in the brainstem and cerebral cortex. Numerous minute scar foci were also scattered in the gray matter, accompanied by some demyelinating lesions in the white matter. The presence of microthrombi and plasma exudation into the vessel wall suggested the importance of vascular factors in the pathogenesis of these CNS lesions. Peripheral neuropathy was also present. The neuropathological features were almost the same as those of neuro-Behçet syndrome, but he lacked the extraneural symptoms of Behçet disease.

Adult↗