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Biomedical subjects

H Oyama

Publications and source records attributed to H Oyama.

At least 127 records · Page 7Linked to original sources
PubMed1993

Functional role of charybdotoxin-sensitive K+ channels in the resting state of cerebral, coronary and mesenteric arteries of the dog.

To determine the possible role of Ca(++)-activated K+ (KCa) channels in the regulation of resting tone of arteries, the effects of agents that interact with these channels on tension and 86Rb efflux were examined in endothelium-denuded strips of cerebral (middle cerebral, posterior cerebral and basilar), coronary and mesenteric arteries of the dog. Strips of cerebral arteries maintained a myogenic tone; i.e., the resting tone decreased when either the Krebs' solution was replaced with a Ca(++)-free solution or nifedipine was added. The addition of charybdotoxin, a blocker of large conductance KCa channels, to the resting strips (strips at a resting state) caused a concentration-dependent contraction in the cerebral arteries but not in the coronary or mesenteric artery. In resting strips preloaded with 86Rb, the basal 86Rb efflux rate constant was significantly greater in the cerebral arteries than in the coronary and mesenteric arteries. The addition of nifedipine to the resting strips decreased the basal 86Rb efflux rate constant in the cerebral and coronary arteries. Effects of nifedipine on tension and 86Rb efflux in 20.9 mM K(+)-contracted strips of the mesenteric artery were comparable to the effects of this blocker in the resting strips of the middle cerebral artery. The 86Rb efflux rate constant during the stimulation with 65.9 mM K+ was similar for the middle cerebral and mesenteric arteries. Studies using 1- or 5-min pulse labeling with 45Ca demonstrated increased basal 45Ca influx in the resting state of cerebral arteries compared with the coronary and mesenteric arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

[Congenital bicuspid aortic valve with regurgitation--a rare case showing a fibrous band between the conjoined cusp and the ascending aorta].

It is quite unusual that the congenital bicuspid aortic valve shows aortic valve regurgitation except postinflammatory event. In a case of aortic regurgitation with bicuspid valve, a fibrous band was recognized between the conjoined cusp and the ascending aorta at the operation. Since a degenerative change alone was discerned histologically in the resected specimen, this abnormal band was supposed to be an embryogenic remnant of the aortic valve. Six cases were reported previously and all of them were male, and five were Japanese.

Aorta↗
PubMed1993

[Two cases of acute progressive interstitial pneumonia associated with dermatomyositis--clinical features and immunological disorders].

Some patients of dermatomyositis (DM) with interstitial pneumonia (IP) have common clinical features. Clinical features of these patients are acute onset, very poor prognosis and that patients have fever, arthritis, typical skin rash, mild myositis and show low ratio of CPK/LDH, low incidence of antinuclear antibody (ANA) appearance, low inflammatory signs. We experienced two cases of this category of DM with IP and examined immunological aspects. Case 1. A 52-year-old woman was admitted in June 1, 1990 with a one-month history of arthralgia and a ten-days history of fever, skin rash, myalgia and dyspnea on exertion. On examination she had Gottron's papules on her fingers, erythema on back, bilateral elbows and legs, proximal muscle weakness and arthritis. Fine crackles were audible in the lower lung fields. Laboratory data included CPK 200 IU/l, ALD 3.2 IU/l, LDH 805 IU/l. Analysis of bronchoalveolar lavage fluid (BALF) revealed increased cellularity with lymphocytosis. She was treated with oral corticosteroid (CS), pulse CS, cyclosporin A. Inspite of these therapies, she died of progressive respiratory insufficiency in July 10, 1990. Case 2. A 23-year-old woman was admitted in April 1, 1991, with a two-month history of arthralgia and a one-month history of fever, skin rash, stomatitis, alopecia. On examination she had Gottron's papules on her fingers, erythema on malar, bilateral elbows and legs, arthritis and stomatitis. Laboratory data included CPK 97 IU/l, ALD 8.5 IU/l, LDH 779 IU/l. She began experiencing dry cough and dyspnea on exertion in May 1991. Analysis of BALF revealed increased cellularity with lymphocytosis. She was treated with oral corticosteroid(CS), pulse CS, pulse cyclophosphamide.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

[Gamma-radiosurgery of metastatic brain tumors].

Twenty-six cases of various brain metastases were treated with Gamma-knife. Their primary sites were: lung in 13, colon in 5, breast in 2, kidney in 2, liver in 1, ovary in 1, and a malignant melanoma. The origin of one case was not verified. There were 11 single and 15 multiple metastases. In total 70 tumors were involved. Following localization with MRI and dose planning using a computer system, radiosurgery was carried out. Tumors were treated with the maximum dose between 24 and 50Gy, and with the marginal dose between 12 and 25Gy. Early follow-up results demonstrated favorable responses chiefly by tumor shrinkage, central tumor necrosis or by decreased peritumoral edema. In fact after radiosurgery, the rates of tumor shrinkage were 55.7%, 61.8% and 66.7% at 3, 6 and 9 months respectively. The tumor control rates, including regressed and stable tumors, were 98.6%, 97.1 and 85.7 at 3, 6 and 9 month intervals respectively. Meanwhile, 14 cases were neurologically improved, and another 4 showed either no perceivable change. Neurological deterioration occurred in 4 cases by progression of brain metastasis in 2 and by perifocal edema after radiosurgery. Recurrent brain metastases occurring after radiosurgery were treated with a repetition of Gamma-knife surgery in 4 cases, resulting in good tumor control. In conclusion most of the brain metastasis can be well controlled by radiosurgery for relatively long period of time.

Adult↗
PubMed1993

[Recurrence with tumor bleeding in a patient with malignant astrocytoma during the treatment with intracranial injection of lymphokine-activated killer cells--a case report].

A 22-year-old woman harboring recurrent malignant astrocytoma presented with intracranial hypertension by tumor hemorrhage during repeated administration of lymphokine-activated killer (LAK) cells via Ommaya's reservoir. She first suffered from the tumor located at the right occipital lobe at the age of 13. The tumor regressed completely by subtotal removal of the tumor, followed by external irradiation. Nine years later, however, the occipital tumor recurred and was subtotally resected. Pathological diagnosis was astrocytoma grade 3. Postoperatively, LAK cells induced from her peripheral blood lymphocytes incubated with interleukin-2 and anti-CD3 antibody were injected into the tumor cavity via Ommaya's reservoir for eight times. At the end of the LAK therapy, the tumor regrew with massive hemorrhage in the tumor cavity causing intracranial hypertension. At the reoperation, thick granulation tissue covered the surface of the recurrent tumor and dense deposits of clot were noted around the tip of the Ommaya's tube. Histologically the superficial layer of the tumor was infiltrated with macrophages and lymphocytes, mostly CD3-positive T cells, accompanied with capillary hyperplasia. Viable astrocytoma cells were abundant beneath the granulation layer. It should be considered that in local LAK therapy granulation tissue formation with hypervascularization at the surface of the tumor cavity may lead to tumor bleeding as well as resistance to the treatment.

Adult↗
PubMed1993

[Clinical study of rheumatoid interstitial lung disease evaluated by high resolution CT].

High resolution computed tomographic (HRCT) scans were obtained in 215 patients with rheumatoid arthritis to assess pulmonary fibrosis (PF). We classified the HRCT appearances as five-point scale (0-4) based on the degrees of PF. The results were as follows: 1. We found 117 cases (54.4%) of PF on HRCT. 2. Patients with PF (grade 1-4) showed significantly increased leucocyte cell counts and significantly worsened pulmonary function test than patients without PF (grade 0). 3. Patients with advanced articular involvement had significantly higher prevalence of PF than others without them. 4. Patients who were previously or currently receiving gold sodium thiomalate (GST) injection or administration of methotrexate had higher prevalence of PF than others. However, patients who were receiving long term GST therapy (1 year long or sigma 1000 mg) had slightly lower prevalence of PF than others. This finding suggests that dose-dependent lung injury is not related to GST therapy. 5. Patients with advanced PF (grade 3, 4) had high prevalence of male sex, smoker, extraarticular manifestation.

Adolescent↗
PubMed1992

Angiographically occult arteriovenous malformation in the septal region--case report.

An occult arteriovenous malformation (AVM) in the septal region occurred in a 14-year-old boy, manifesting as headache and vomiting. Computed tomography showed a high-density mass in the septal region, faintly enhanced postcontrast. Mild hydrocephalus was also seen. Angiography revealed no abnormalities other than hydrocephalic signs. The lesion was totally removed by the transventricular approach after corticotomy of the left frontal lobe. The histological diagnosis was AVM. He was discharged without neurological or endocrinological deficits.

Adolescent↗
PubMed1992

Giant meningioma fed by the anterior choroidal artery: successful removal following embolization--case report.

A 53-year-old female was admitted with apathy, left sensory and motor disturbance, left homonymous hemianopsia, and dressing apraxia. Computed tomography and magnetic resonance imaging showed a huge mass markedly enhanced in and around the right trigone. Cerebral angiography revealed rich vascularity of the tumor mainly fed by the right anterior choroidal artery. The feeding vessel was embolized with microfibrillar collagen after superselective catheterization. Seven days later, the tumor was totally removed with low blood loss. The histological diagnosis was fibroblastic meningioma. She was discharged without neurological deficit, except for left homonymous hemianopsia.

Arteries↗
PubMed1992

Growth inhibition of glioma cells by liposome-mediated cell transfection with tumor necrosis factor-alpha gene--its enhancement by prior gamma-interferon treatment.

A new approach to the treatment of malignant glioma is cytokine gene therapy to produce growth inhibitors in cells. Previously, we showed that human glioma cells selectively transfected with the gene of interferon (IFN)-beta and/or IFN-gamma by our novel liposomes tagged with monoclonal antibody against a glioma-associated antigen achieved a remarkable growth inhibition effect. In the present experiment, we demonstrated the effectiveness of gene therapy against glioma cells using liposomes bearing a plasmid containing the gene for tumor necrosis factor (TNF)-alpha. We also found that the effect of endogenous TNF-alpha was enhanced by treatment of IFN-gamma prior to the transfection with the TNF-alpha gene.

Cell Division↗
PubMed1992

Effects of vasopressin and oxytocin on canine cerebral circulation in vivo.

In vivo experiments on the vasoactive effects of vasopressin and oxytocin on cerebral circulation were carried out in anesthetized dogs, using an electromagnetic flowmeter to measure vertebral blood flow and angiography to measure the internal diameter of the basilar artery. Direct bolus infusion of 1 pmol to 1 nmol of vasopressin or 10 pmol to 10 nmol of oxytocin into a femoral-vertebral artery shunt produced a dose-dependent decrease in vertebral artery blood flow without significantly affecting mean arterial blood pressure. Vasopressin was more potent than endothelin and neuropeptide Y, which have also been demonstrated to induce long-lasting decreases in vertebral artery blood flow. However, direct bolus infusion of vasopressin (100 pmol and 1 nmol) or oxytocin (1 nmol and 10 nmol) into the vertebral artery dilated major vessels including the vertebral, anterior spinal, and basilar arteries, as well as the circle of Willis and its main branches, while endothelin (1 nmol) and neuropeptide Y (5 nmol) caused no change in the diameters of major cerebral arteries. The V1 antagonist d(CH2)5tyrosine(methyl) arginine vasopressin suppressed the effects of both vasopressin and oxytocin. Vasopressin was over 10 times as potent as oxytocin in both assays. The vasodilatory effect of vasopressin, which may be mediated by an endothelium-dependent mechanism, was functionally damaged in dogs after experimental subarachnoid hemorrhage. These data suggest regional differences in the sensitivity and responsiveness of vasculature to vasopressin and oxytocin, and specifically that both peptides act through V1 receptors to decrease the resistance of large vessels and increase the resistance of small vessels.

Animals↗
PubMed1992

Intracellular distribution of CPT-11 in CPT-11-resistant cells with confocal laser scanning microscopy.

CPT-11, 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxy camptothecin, is a well-known DNA topoisomerase I inhibitor. SN-38 is a metabolite of this compound. Both emit fluorescence when activated by a laser beam. With a confocal laser scanning microscope (CLSM), we determined the intracellular distribution of CPT-11 and SN-38 and the chronological changes in drug-treated PC-7, a cell line of human non-small cell lung cancer, and its CPT-11 resistant variant, PC-7/CPT cells. There were many more granules in the cytoplasm in PC-7/CPT than in the parent cell line (PC-7). The granule formation of the resistant cell could indicate a different drug metabolism in the cytoplasm from that of the parent cell. This technique would provide a new way of investigating the mechanism of resistance of cancer cells to anticancer drugs.

Antineoplastic Agents, Phytogenic↗
PubMed1992

Skull base malignant lymphoma: a case report and review of the literature.

A case of primary malignant lymphoma of the skull base is reported. A 62-year-old man was admitted with headache and diplopia. Computed tomography and magnetic resonance imaging showed an abnormal mass in the right parasellar region. The final diagnosis after surgery was primary malignant lymphoma of the skull base. Primary malignant lymphomas sometimes occur in the central nervous system but those in the skull base are exceptional. The present paper presents just such a rare case of malignant lymphoma of the skull base. Diagnosis and combined therapy consisting of surgery, radiotherapy and chemotherapy for the disease are discussed, and the literature on recent clinical problems of central nervous system lymphomas is reviewed.

Brain Neoplasms↗
PubMed1991

Cloning and sequencing of the 7 alpha-hydroxysteroid dehydrogenase gene from Escherichia coli HB101 and characterization of the expressed enzyme.

The 7 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.159) gene from Escherichia coli HB101 was cloned and expressed in E. coli DH1. The hybrid plasmid pSD1, with a 2.8-kbp insert of chromosomal DNA at the BamHI site of pBR322, was subcloned into pUC19 to construct plasmid pSD3. The entire nucleotide sequence of an inserted PstI-BamHI fragment of plasmid pSD3 was determined by the dideoxy chain-termination method. Within this sequence, the mature enzyme protein-encoding sequence was found to start at a GTG initiation codon and to comprise 765 bp, as judged by comparison with the protein sequence. The deduced amino acid sequence of the enzyme indicated that the molecular weight is 26,778. The transformant of E. coli DH1 harboring pSD3 with a 1.8-kbp fragment showed about 200-fold-higher enzyme activity than the host. The enzyme was purified by a single chromatography step on DEAE-Toyopearl and obtained as crystals, with an activity yield of 39%. The purified enzyme was homogeneous, as judged by sodium dodecyl sulfate gel electrophoresis. The enzyme was most active at pH 8.5 and stable between pH 8 and 9. The enzyme was NAD+ dependent and had a pI of 4.3. The molecular mass was estimated to be 120 kDa by the gel filtration method and 28 kDa by electrophoresis, indicating that the enzyme exists in a tetrameric form.

Amino Acid Sequence↗
PubMed1991

Effects of changes in angiotensin converting enzyme activity on renin release: pretreatment with dexamethasone enhances a plasma renin activity response to captopril in normal subjects.

Healthy adults were given captopril (25 mg and 75 mg) po with or without dexamethasone (DXM) pretreatment (1 mg po 2 h before and simultaneously with the captopril). We determined the serum potassium and sodium concentrations, plasma prostaglandin E2 level, PRA, serum angiotensin converting enzyme (ACE) activity, and aldosterone level from 20 min before to 120 min after administration of captopril. DXM pretreatment stimulated the PRA response to captopril. This stimulation was suppressed by indomethacin. However, the administration of DXM did not induce a consistent rise in the prostaglandin E2 level. The administration of DXM induced a significant rise in the potassium concentration, but since simultaneous administration of indomethacin with captopril induced the suppression of PRA without affecting the potassium level, the PRA increase in response to captopril with DXM was not caused directly by the potassium increase. There were no significant differences in the PRA increase between 25 mg captopril and 75 mg captopril, or between DXM-25 mg captopril and DXM-75 mg captopril, though the inhibitions of ACE activity by captopril differed according to dose. The PRA increases, but not the captopril-induced inhibition of ACE activity, were significantly different between captopril alone and captopril with DXM pretreatment at either dose of captopril. Thus, the inhibition of ACE activity perhaps allows PRA to increase in response to captopril. These results suggest that the DXM stimulation of PRA may have been dependent on the inhibition of ACE activity by captopril.

Adult↗
PubMed1991

Siblings with malignant glioma--report of two cases.

The authors report malignant glioma occurring in two sibling cases. The elder brother presented with right hemiparesis and hemihypesthesia at 14-year-old. Computed tomographic (CT) scanning demonstrated a low-density area in the left frontoparietal lobe. The tumor was partially removed. Histologic diagnosis was glioblastoma multiforme. Radiation therapy was given postoperatively, but he died due to tumor recurrence 15 months after onset. The younger sister was admitted comatose due to intratumoral bleeding at 19-year-old. CT scans showed a high-density area in the right temporal lobe. The tumor was excised subtotally. Histological diagnosis was malignant astrocytoma (grade III). Radiation therapy, chemotherapy (ACNU), and immunotherapy (interferon) were given postoperatively, but she died due to recurrence 34 months after onset.

Adolescent↗
PubMed1990

[Choroid plexus involvement in malignant lymphoma. Case report].

Involvement of the choroid plexus by malignant lymphoma is rare. This case showed mass lesions at the choroid plexus in the first stage of systemic non-Hodgkin's malignant lymphoma. A 53-year-old female was admitted with headache, diplopia, and gait disturbance. The patient was alert but had left supraclavicular and axially lymph node swelling. Computed tomography scan revealed enhanced masses at the lateral and fourth ventricles. The lymph node biopsy disclosed non-Hodgkin's malignant lymphoma, diffuse large cell type. The immunological marker was the B-cell type. At surgery, there was highly vascular white tumor at the choroid plexus of the right lateral ventricle. The tumor also involved adjacent brain tissue. Pathological examination revealed infiltration of lymphoma cells to the choroid plexus. The subependymal and perivascular spaces of the choroid plexus were filled with lymphoma cells. Virchow-Robin space and white matter of adjacent brain tissue were also involved by lymphoma. After surgery, whole brain irradiation of 35 Gy and chemotherapy were performed. However, 14 months after initial diagnosis, the patient expired because of systemic involvement by the lymphoma.

Cerebral Ventricle Neoplasms↗