Biomedical subjects

T Okamura

Publications and source records attributed to T Okamura.

At least 19 recordsLinked to original sources

PubMed1997

Biotechnological potential of P450 monooxygenases high-level production of bovine cytochrome P450c17 monooxygenase during medium cell density culture of a recombinant yeast, Saccharomyces cerevisiae GRF 18 (YEp-Toku1).

Bovine cytochrome P450c17 monooxygenase was produced in a 30-L fermenter by Saccharomyces cerevisiae GRF18 (YEp-Toku1), harboring the GAL10 promoter, and using conditions of medium cell density culture. Upon addition of D-galactose as an inducer and FeCl3 as a cofactor, cells began to produce the P450 hemoprotein. The yield of this enzyme reached a maximum after 31 h but its formation continued for more than 60 h after induction. The amount of P450c17 produced was 4.7-fold as compared to shake flask experiments.

Cell Count↗

PubMed1997

Flunarizine, an anti-migraine agent, impairs nitroxidergic nerve function in cerebral arteries.

Flunarizine is an anti-migraine agent that blocks the Ca2+ entry across cell membrane. In order to obtain a clue of mechanisms underlying the migraine headache, modifications by flunarizine of the response to nitric oxide (NO), a cerebral vasodilator and algogenic agent, derived from perivascular nerves were evaluated. Relaxations due to nerve stimulation by electrical pulses (5 Hz) and nicotine (10(-4) M) in canine cerebral arterial strips were attenuated by treatment with flunarizine dose-dependently, whereas the responses to exogenous NO (10(-7)-10(-6) M) and nitroprusside (10(-8)-10(-6) M) were unaffected. The inhibition by the Ca2+ entry blocker of the response to electrical nerve stimulation and nicotine was obtained in a concentration (10(-6) M) that did not significantly relax the arterial strips. NO derived from perivascular nerve may be one of the factors involved in the genesis of migraine attack, which is expected to be relieved by a reduction of neural NO synthase activity associated with a decreased Ca2+ influx by flunarizine during nerve activation.

Animals↗

PubMed1997

Analysis of the vasodilator nerve function by nicotine in isolated dog skin artery.

Mechanisms underlying the relaxation induced by nicotine were analyzed in cutaneous arterial strips isolated from dogs and with the endothelium removed. In the strips treated with prazosin and precontracted with prostaglandin F2 alpha, nicotine produced relaxations which were not influenced by atropine but abolished by hexamethonium. Relaxations induced by nicotine were partially inhibited by NG-nitro-L-arginine (L-NA), a nitric oxide (NO) synthase inhibitor; the remaining relaxations were abolished by desensitization to calcitonin gene-related peptide (CGRP) or treatment with CGRP-(8-37), a CGRP receptor antagonist, or with capsaicin. Desensitization to vasoactive intestinal polypeptide (VIP) or a VIP receptor antagonist did not influence the nicotine-induced relaxation. In the strips densensitized to CGRP, the nicotine-induced relaxation was abolished by L-NA; the inhibitory effect was reversed by L-arginine. Perivascular nerves containing NADPH diaphorase and CGRP immunoreactivity were histochemically identified in the cutaneous artery. CGRP immunoreactivity was abolished by treatment with capsaicin. It is concluded that nicotine produces relaxation in dog cutaneous arterial strips, possibly mediated by NO and CGRP liberated from vasodilator nerves.

Animals↗

PubMed1997

18F-fluorodeoxyglucose positron emission tomography and the prognosis of patients with pancreatic adenocarcinoma.

BACKGROUND: Fluorodeoxyglucose (FDG) detected by positron emission tomography (PET) can be used to measure the glycolytic activity of tumor cells. Though the prognosis of patients with pancreatic adenocarcinoma is usually poor, a subset of patients with good prognoses may be discovered by determining the degree of FDG integration into tumors. METHODS: Fourteen patients with histologically proven pancreatic adenocarcinoma underwent 18F-FDG PET. The standardized uptake value (SUV) of 18F-FDG was calculated, and the patients were divided into high (> or = 3.0) and low (< 3.0) SUV groups. RESULTS: The two groups were not significantly different in terms of age, tumor location and size, staging, and treatment. However, analysis by the Kaplan-Meier method revealed that the groups had different prognoses (log rank test, P < 0.05). The mean survival of patients with high SUV was 5 months, whereas that of patients with low SUV was 14 months. There were not strong correlations between the SUVs and tumor size (0.56), serum carbohydrate antigen 19-9 (0.39), or carcinoembryonic antigen (0.52). CONCLUSIONS: SUV calculated with 18F-FDG can be utilized as a prognostic factor for patients with pancreatic adenocarcinoma.

Adenocarcinoma↗

PubMed1997

Inhibition of nitroxidergic nerve function by neurogenic acetylcholine in monkey cerebral arteries.

1. Modification by endogenous or exogenous acetylcholine and vasoactive intestinal polypeptide (VIP) of vasodilatation mediated by nitric oxide (NO) released from nitroxidergic nerves was studied in isolated monkey cerebral arteries. In arterial strips denuded of endothelium, transmural electrical stimulation (2-20 Hz) produced relaxations that were abolished by tetrodotoxin. 2. The relaxation response was attenuated by acetylcholine, and the attenuation was reversed by atropine. Attenuation was also observed with AF-DX 116, an antagonist of the muscarinic acetylcholine receptor subtype, M2. NO-induced relaxation was not affected by acetylcholine. Neurogenic relaxation was also inhibited by physostigmine and potentiated by atropine. 3. VIP in concentrations that elicited slight relaxation did not alter the response to nerve stimulation. In the strips showing tachyphylaxis to VIP, the neurogenic response was not inhibited. 4. Histochemical studies of whole-mount preparations revealed nerve fibres with NO synthase and VIP immunoreactivity, and also acetylcholinesterase, suggesting the presence of perivascular nitroxidergic, VIPergic and cholinergic innervation. 5. It is concluded that the actions of nitroxidergic nerve fibres on the monkey cerebral artery are inhibited by nerve-released acetylcholine acting on prejunctional muscarinic receptors, possibly of the M2 subtype. Despite the presence of VIP immunoreactive nerve fibres and the ability of exogenous VIP to relax the artery, there is no evidence supporting either a prejunctional modulation of nitroxidergic nerve function by VIP or a role for VIP as a vasodilatory neurotransmitter.

Acetylcholine↗

PubMed1997

Pure red cell aplasia with thymona: evidence of T-cell clonal disorder.

Pure red cell aplasia (PRCA) sometimes accompanies thymoma. Herein, we report a PRCA patient with thymoma with a clonal disorder of T cells. A 55-year-old man presented with anemia and anterior mediastinum tumor. The laboratory study revealed hemoglobin 8.2 g/dl; leukocytes 15.8 x 10(9)/L with 76.5% neutrophils, 20.0% lymphocytes, and reticulocytes 0.0%. Bone marrow aspirate smears and biopsy sections revealed normal myeloid and megakaryocyte differentiation and contained no erythroid precursors. We made the diagnosis of PRCA. The size of the lymphocytes was small without any granules in the cytoplasm. The surface marker of peripheral blood mononuclear cells demonstrated increased CD2+, CD3+, CD4-, and CD8+ populations. The mediastinal tumor was resected and a thymoma diagnosed. A monoclonal rearrangement of T-cell receptor (TCR)-beta-chain gene was found using Southern blot analysis of the mononuclear cells in both peripheral blood and thymoma. Treatment with prednisolone, thymectomy, and cyclophosphamide exerted no beneficial effect. After initiation of the Cyclosporin A therapy, the patient developed reticulocytosis. This PRCA case seems to present a neoplastic proliferation of CD8+ T cells in peripheral blood and thymus with a monoclonal rearrangement of the TCR-beta-chain gene.

Cell Differentiation↗

PubMed1997

Positron emission tomographic imaging of head and neck lesions.

Positron emission tomography (PET) produces images that reflect the rate and distribution of biochemical and physiological processes in tissue in vivo. This has been observed with many types of neoplasm not evident when using such anatomical imaging techniques as computed tomography or magnetic resonance imaging. We evaluated the feasibility of 2-18F-2-deoxy-D-glucose (FDG) PET studies in diagnosing and assessing the effects of treatment on lesions of the tongue, maxillary sinus and nasopharynx. FDG-PET imaging was performed 45 times in 17 patients with tumors before treatment. Ten patients with malignant lesions also underwent imaging after treatment. The differential absorption ratio (DAR) of the isotope was calculated at 55 min and the time activity curve (TAC) was obtained by dynamic emission scans for 0-55 min following injection of FDG. FDG-PET images, DAR and TAC were evaluated in all lesions. Findings showed that FDG-PET images could be used to diagnose malignant tumors and evaluate treatment when the DAR was > 4.0 and TAC was steep upward. Images suggestive of benign lesions had low DAR values (< 4.0) and mildly upward or flat TACs.

Absorption↗

PubMed1997

Pericentric inversion of chromosome 16 and eosinophilia in chronic myelomonocytic leukemia.

We report a case of myelodysplastic syndrome with bone marrow eosinophilia and the chromosomal abnormality, inv(16)(p13q22). Hematologic findings including monocytosis and trilineage myelodysplasia were consistent with chronic myelomonocytic leukemia, and numerous abnormal eosinophils were present in the bone marrow. Chromosomal analysis of all metaphase cells from peripheral blood and bone marrow revealed in(16)(p13q22), which is well known characteristic of acute myelomonocytic leukemia with eosinophilia (M4Eo). Both monocytes and eosinophils in this case may be derived from common leukemic progenitors affected by inv(16)(p13q22).

Aged↗

PubMed1997

Increased incidence of cytomegalovirus (CMV) infection and CMV-associated disease after allogeneic bone marrow transplantation from unrelated donors. The Fukuoka Bone Marrow Transplantation Group.

Cytomegalovirus (CMV) infection and CMV-associated disease were monitored using the CMV antigenemia assay in 72 patients who received allogeneic bone marrow transplantation (BMT), and their incidences were compared between related and unrelated donor transplant patients. The incidence of CMV infection after BMT was significantly higher in patients who received transplants from HLA-matched unrelated donors than from HLA-matched sibling donors (87% vs 53%, P < 0.05). CMV-associated disease developed in 73% of unrelated and in 14% of sibling donor transplant patients (P < 0.01). The peak levels of CMV antigenemia were significantly higher in unrelated donors than in sibling donor transplant patients (16 vs 1 CMV antigen-positive cells per 50000 WBCs, P < 0.01). The median number of CMV antigen-positive cells on first detection was also significantly higher in unrelated donor transplant patients (15 vs 1, P < 0.01). The detection of CMV antigen-positive cells preceded the development of CMV-associated disease in 18% of unrelated donor transplant patients, suggesting a lower predictive value of CMV antigenemia for subsequent CMV-associated disease in unrelated donor BMT. Careful monitoring and further studies are needed for the early diagnosis and prevention of CMV-associated disease in unrelated donor BMT.

Adolescent↗

PubMed1997

Changes in hemostatic parameters in hepatic veno-occlusive disease following bone marrow transplantation.

Hepatic veno-occlusive disease (VOD) is a major complication after bone marrow transplantation (BMT). Its prediction, diagnosis and treatment remain unclear. Examination was made of changes in hemostatic parameters in patients with or without VOD after BMT. Twenty-seven children were studied following BMT. Eight of them developed VOD. Tissue plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), thrombomodulin (TM), von Willebrand factor (vWF), factor VII, fibrinogen (FBG), FDP, D-dimer (D-D), plasminogen (PLG), thrombin-antithrombin III (TAT), alpha 2-plasmin inhibitor/plasmin complex (PIC), antithrombin III (AT-III), protein C, N-terminal propeptide for type III procollagen (P-III-P), were measured weekly from pre-BMT to day 28 after BMT. In VOD patients, t-PA and PAI-1 significantly increased (P < 0.05) and FBG significantly fell during the post-transplant period (P < 0.05). Significantly low AT-III and PLG were also noted before VOD (P < 0.05). There were no changes in other hemostatic parameters. t-PA, PAI-1 and FBG would thus appear useful markers for the diagnosis of VOD, and AT-III and PLG, predictive markers for VOD. The coagulation-fibrinolysis system following endothelial cell damage may contribute to the onset of VOD.

Adolescent↗

PubMed1997

Angina pectoris occurring during granulocyte colony-stimulating factor-combined preparatory regimen for autologous peripheral blood stem cell transplantation in a patient with acute myelogenous leukaemia.

We describe a patient with acute myelogenous leukaemia who developed angina pectoris during pretransplant conditioning for autologous peripheral blood stem cell transplantation (PBSCT); the conditioning regimen consisted of cytotoxic drugs in combination with granulocyte colony-stimulating factor (G-CSF). Neutrophilia and hypercoagulability were observed at the time of angina pectoris. Recurrence of angina pectoris was not seen after nitrate and aspirin therapy. Exercise stress testing performed after PBSCT suggested the presence of myocardial ischaemia. Therefore cases at risk of vascular events should be carefully managed with prophylactic treatment during G-CSF administration.

Angina Pectoris↗

PubMed1997

Hepatitis GB virus C genome in the serum of aplastic anaemia patients receiving frequent blood transfusions.

GB virus C (GBV-C) RNA was detected in five of 18 patients with aplastic anaemia who had received blood transfusions, whereas it was not detected in eight patients who had not received any transfusions. Antibody against hepatitis C virus (anti-HCV) was detected in nine patients in the transfusion group, compared with one of eight who had not received any transfusions. Therefore, the route of transmission of both GBV-C and HCV in these patients appeared to have been multiple blood transfusion. Since all of the GBV-C RNA-positive patients harboured anti-HCV, GBV-C seems to frequently superinfect with HCV. Neither GBV-C nor HCV is likely to have been a causative agent of the anaemia in the cases examined.

Adolescent↗

PubMed1997

Decreased expression of the p16/MTS1 gene without mutation is frequent in human urinary bladder carcinomas.

The p16 (CDKN2,MTS1) gene is located at 9p21 and its product, p16, inhibits the cyclin D/CDK4 complex. Loss of heterozygosity on chromosome 9p is very common in human bladder carcinomas and has been found in all stages of lesions, suggesting that it occurs early in bladder tumor progression. Several studies have revealed frequent homozygous deletion of the p16 gene in cell lines, and that such deletions are also common in some types of cancers. In addition, point mutations in the p16 gene have been identified in several types of neoplasia. In the present examination of urinary bladder tumors, no p16 gene mutations were detected, but nine cases out of 23 (39%) showed decreased mRNA expression, revealed by the reverse transcriptase polymerase chain reaction. There were no histological differences apparent between those cases with normal and those with decreased p16 expression. These results indicate that while p16 gene mutations may be rare, changes in the level of the p16 transcripts could play a role in human bladder carcinoma development.

Carrier Proteins↗

PubMed1997

Radioimmunodetection with 111In-labeled monoclonal antibody Nd2 in patients with pancreatic cancer.

This report summarizes results from an initial clinical evaluation of radioimmunodetection (RAID) in patients with pancreatic cancer using murine monoclonal antibody Nd2, directed against mucins from pancreatic cancer. Nd2 (2 mg) was labeled with 111In (2 mCi) and injected into 19 patients suspected of having pancreatic cancer. Planar scintigrams were taken 3 days post-infusion. As for final diagnoses after surgery, 14 cases were pancreatic cancer, and one case each was chronic pancreatitis, neurilemmoma, islet cell carcinoma, cholangioma, and apparent absence of suspected recurrent lesion of pancreatic cancer. Of 14 patients with pancreatic cancer, RAID was positive in 10 cases (71.4%). Cases other than pancreatic cancer were all negative, so the specificity was 100%. These results demonstrate that RAID using 111In-Nd2 can be useful in differentiating exocrine pancreatic cancer from benign conditions and other types of carcinomas in the pancreatoduodenal regions.

Adenocarcinoma↗

PubMed1997

Urethral recurrence of an urachal carcinoma: a case report.

A 68-year-old man presented with microscopic hematuria. Cystoscopy revealed a papillary and pedunculated tumor in the bladder dome which, on punch biopsy, proved to be adenocarcinoma. Partial cystectomy and urachal remnant resection were performed. Histopathologically, the tumor was diagnosed as an urachal tumor. Four months after surgery, multiple posterior urethral tumors were found; punch biopsy revealed adenocarcinoma, which was quite similar to the previous tumor. Based on the histopathological examination of the transurethrally resected tissue, the urethral tumor was diagnosed as a recurrence of the urachal carcinoma. No evidence of either tumor recurrence or metastasis was found within the 15 months following the second surgery.

Adenocarcinoma↗

PubMed1997

A chance SPECT study of ictal aphasia during simple partial seizures.

We report obtaining an ictal single photon emission computed tomographic (SPECT) scan in a right-handed 51-year-old man who had an astrocytoma in the left cerebral hemisphere and simple partial seizures characterized by aphasia. An epileptic seizure producing loss of speech and right-sided facial twitching occurred by chance during a SPECT scan. During the attack, he was unable to speak, but auditory comprehension and writing were intact. Ictal SPECT showed an area of increased perfusion in the left frontal cortex, with the area of highest perfusion involving the left frontal operculum to the inferior part of the left precentral gyrus. Interictal SPECT showed hypoperfusion in the same area. These SPECT findings suggest that the frontal operculum of the dominant hemisphere is one of the regions that can give rise to epileptic aphasia.

Astrocytoma↗

PubMed1997

Nitric oxide-mediated neurogenic vasodilatation in isolated monkey lingual arteries.

In isolated monkey lingual arteries denuded of the endothelium and contracted with prostaglandin F2alpha, transmural electrical stimulation produced a contraction that was reduced by prazosin and reversed to a relaxation by additional treatment with alpha,beta-methylene ATP. The relaxation thus induced was abolished by tetrodotoxin and N(G)-nitro-L-arginine (L-NNA), a nitric oxide (NO) synthase inhibitor, and L- but not D-arginine restored the response in the L-NNA-treated arteries. Under treatment with prazosin and alpha,beta-methylene ATP, the arterial strips responded to nicotine with a relaxation that was not influenced by atropine and timolol but was abolished by hexamethonium, oxyhemoglobin, and methylene blue. The nicotine-induced relaxation was abolished by L-NNA but not by N(G)-nitro-D-arginine and was reversed by L-arginine. Relaxations to exogenously applied NO (acidified NaNO2 solution) were not influenced by L-NNA but were abolished by oxyhemoglobin and methylene blue. The response was not affected in the strips made unresponsive to vasoactive intestinal polypeptide and calcitonin gene-related peptide by desensitization. Histochemical study demonstrated the presence of perivascular neurons containing neuronal NO synthase. It is concluded that monkey lingual arteries are innervated by vasoconstrictor nerves liberating norepinephrine and possibly ATP and also by nonadrenergic noncholinergic vasodilator nerves liberating NO as a neurotransmitter to activate soluble guanylate cyclase. Vasoactive intestinal polypeptide and calcitonin gene-related peptide do not appear to be involved in the neurogenic vasodilatation.

Adenosine Triphosphate↗

PubMed1997

beta1-Adrenoceptor-mediated relaxation by norepinephrine in dog hepatic arteries.

Dog hepatic arterial strips treated with prazosin responded to norepinephrine with concentration-related, endothelium-independent relaxations, the maximal response being 81.7% of the papaverine-induced maximal relaxation that was markedly greater than that in renal arteries. The norepinephrine-induced relaxation in hepatic arteries was significantly attenuated by metoprolol but not influenced by butoxamine. Relaxant responses to norepinephrine of dog hepatic arteries appear to be mediated by the beta1-adrenoceptor subtype, like those of coronary arteries. Evidence for functioning of the beta1-subtype in hepatic arteries would contribute to the analysis of neural and hormonal regulation of blood flow in the liver.

Adrenergic alpha-Antagonists↗