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Biomedical subjects

T Okamura

Publications and source records attributed to T Okamura.

At least 523 records · Page 29Linked to original sources
PubMed1990

Transcerebellar thrombectomy for the successful clipping of thrombosed giant vertebral artery-posterior inferior cerebellar artery aneurysm: case report.

The operative technique used for a thrombosed vertebral artery-posterior inferior cerebellar artery aneurysm that was treated by combined transcerebellar (petrosal surface) thrombectomy and neck clipping is presented. Transcerebellar thrombectomy permitted the successful clipping of this thrombosed vertebral artery-posterior inferior cerebellar artery aneurysm via the cerebello-medullary cistern.

Aged↗
PubMed1990

Clinical characteristics of hybrid leukemia: report of five cases.

We studied clinical and biological features of five cases of hybrid leukemia. Three of the five patients were classified as biphenotypic leukemia because of the coexpression of myeloid/B lymphoid markers in patients 1 (FAB M2) and 2 (FAB CMMoL) and myeloid/T lymphoid markers in patient 3 (FAB M4). Patient 4 was identified as bilineal-biphenotypic leukemia because acute myelogenous leukemia (AML) (FAB M4) and acute lymphoblastic leukemia (ALL) (FAB L1) coexisted and each population coexpressed myeloid and T lymphoid markers. Patient 5 was identified as bilineal leukemia due to the conversion from AML (FAB M1) to ALL (FAB L1) at an interval of 3 months. The Philadelphia (Ph1) chromosome was negative in all cases. A leukemic blast colony formation using cell line 5637 conditioned medium as a stimulator was obtained in all four patients examined. Three of the five patients had been suffering from so-called stem cell disorders such as aplastic anemia in patient 2, trilineage myelodysplasia in patient 4 and refractory anemia with excess of blasts in transformation in patient 5. The pre-existing impairment of pluripotent stem cell was probably the background of these hybrid leukemia. Hybrid leukemia appears to have an inferior prognosis: an AML-directed chemotherapy resulted in a low remission rate (2/5) with a short duration of relapse free survival (1/2) and an ALL-directed chemotherapy produced no remission (0/3). Chronological phenotypic analysis revealed that hybrid features of leukemic blasts disappeared at the time of relapse in patient 1 and progression to AML in patient 2. Monitoring of lineage-associated markers should be required for the management of hybrid leukemia.

Adult↗
PubMed1990

Treatment of myelodysplastic syndrome and atypical leukemia with low-dose aclarubicin.

To study the therapeutic effect of low-dose aclarubicin (ACR), we carried out comparative treatment of 15 patients with myelodysplastic syndrome (MDS) and atypical leukemia using this drug. Complete remission (CR) was achieved in three patients with RAEB-t and one patient with AML, partial remission was obtained in one patient with RAEB and hematological improvement in one patient with refractory anemia (RA). Interestingly, prolonged CR for more than 26 months with persistent chromosomal abnormalities was observed in a case of AML, which progressed from RA. Myelosuppression caused by low-dose ACR was milder than that caused by low-dose Ara-C. Furthermore, in vitro studies indicated that ACR induced differentiation of bone marrow cells from one patient with MDS. From these observations, it is suggested that low-dose ACR may be an alternative to low-dose Ara-C for treatment of MDS, and that the in vivo effect of ACR may be mediated by the differentiation of abnormal hemopoietic clones.

Aclarubicin↗
PubMed1990

Various urinary properties in bladder tumor patients.

Urinary electrolytes, pH, urea nitrogen, creatinine, uric acid and osmolarity were measured in patients with bladder tumors and compared with those of a control group. There were 41 bladder tumor patients ranging in age from 29 to 87 (average 64) years with a male:female ratio of 32:9. According to histopathological classification of the bladder tumors, there were 34 transitional cell carcinomas (TCC) (21 G1, 10 G2, 3 G3), four squamous cell carcinomas, two adenocarcinomas and one inverted papilloma. The control group comprised 29 patients ranging in age from 35 to 80 (average 63) years with a male:female ratio of 26:3. Four urine samples were collected from each patient: early morning on the day of admission, just after admission, early morning on the day of return to hospital after temporary discharge, immediately after return to hospital after temporary discharge. The results indicated that the urinary Ca2+ and uric acid values were significantly lower in the bladder tumor group than in the control group. The urinary pH tended to be somewhat higher than in the control group, and the pH values tended to be especially high in the TCC G3 patients. There were differences in the various urinary properties between the TCC G1 and G2 and the TCC G3 patients.

Adult↗
PubMed1990

Conversion of angiotensin I to angiotensin II in dog isolated renal artery: role of two different angiotensin II-generating enzymes.

The functional role of the endothelium in conversion of angiotensin (Ang) I to Ang II was studied in helical strips of dog renal arteries. In the arteries precontracted with PGF2 alpha, Angs I and II caused a moderate relaxation, which was abolished by treatment with saralasin and reversed to a contraction by indomethacin. Removal of the endothelium attenuated the response to Ang I but did not abolish it. The Ang I-induced relaxation in the arteries without endothelium was not significantly attenuated by an Ang-converting enzyme inhibitor, SA446, but was markedly suppressed by chymostatin. On the other hand, in the arteries with endothelium, the relaxation was suppressed but not abolished by SA446, and the remaining relaxation was abolished by additional treatment with chymostatin. Relaxation induced by prostaglandin I2 was unaffected by these enzyme inhibitors. These results strongly suggest that the conversion of Ang I to Ang II is due mainly to the Ang-converting enzyme in the endothelium and to the chymostatin-sensitive Ang II-generating enzyme in subendothelial tissues.

3-Mercaptopropionic Acid↗
PubMed1990

Effect of N-methionine-free, bacterially synthesized recombinant human granulocyte-macrophage colony-stimulating factor in a primate model.

We demonstrate the in vivo effects of bacterially synthesized, N-methionine-free recombinant human granulocyte-macrophage colony stimulating factor (rh GM-CSF) using a crab-eating monkey model. Monkeys were treated with cyclophosphamide (60 mg/kg) and administered with rh GM-CSF (30 micrograms/kg/d) subcutaneously (s.c.) for 7 days. Within 12 h, a transient increase of neutrophils (greater than 15.0 x 10(9)/l) was observed, and complete recovery of WBC counts was obtained by d 9 (d 16 in control monkeys). Neutrophils and eosinophils were absolutely increased (greater than 8 x 10(9)/l) on d 10. Readministration of rh GM-CSF (30 micrograms/kg/d, s.c.) for 3 d (including control monkeys) revealed absolute increases of neutrophils, eosinophils, monocytes and platelets. A two-fold increase of granulocyte/macrophage colony-forming units was also seen in the bone marrow, while the number of burst-forming units-erythroid was not affected. These data indicate that rh GM-CSF of this type stimulates granulopoiesis and thrombopoiesis in vivo.

Animals↗
PubMed1990

Mechanism underlying the response to vasodilator nerve stimulation in isolated dog and monkey cerebral arteries.

Relaxant responses to transmural electrical stimulation and nicotine of cerebral artery strips obtained from dogs and Japanese monkeys were abolished by tetrodotoxin and hexamethonium, respectively, and suppressed by treatment with NG-monomethyl-L-arginine (L-NMMA), a nitric oxide (NO) synthesis inhibitor. The inhibitory effect was prevented and reversed by L-arginine but not by D-arginine. The relaxations suppressed by L-NMMA were not increased by exogenously applied NO. Endothelium denudation did not alter the response to transmural stimulation and nicotine or the inhibitory effect of L-NMMA. D-NMMA did not inhibit the response to vasodilator nerve stimulation. Dog coronary artery relaxations caused by transmural stimulation were not inhibited by L-NMMA but reversed to contractions by propranolol. Relaxations caused by substance P of dog cerebral arteries treated with indomethacin were dependent on endothelium and inhibited by L-NMMA, whereas those by NO and nitroglycerin, endothelium-independent relaxations, were unaffected. It is concluded that chemical and electrical stimulation of vasodilator nerves relaxes dog and monkey cerebral arteries, possibly by a mediation of NO rather than a stimulating action of NO on the release of vasodilator transmitter. Endothelium-dependent relaxations by substance P of dog cerebral arteries appear to be mediated by NO.

Animals↗
PubMed1990

[Endothelium-derived relaxing factor (EDRF)].

The great discovery by Furchgott of the relaxing factor released from the endothelium (EDRF) awakened us to the necessity to reevaluate the functional importance of endothelial cells that have been chemically or physically stimulated. EDRF was first demonstrated to be released by acetylcholine, substance P, bradykinin and calcium ionophore A23187; thereafter, many substances have been found to release EDRF. This factor is quite unstable, is not produced by cyclooxygenase, and is an activator of soluble guanylate cyclase that synthesizes cyclic GMP; its action is suppressed by antioxidants via the superoxide anions produced, potentiated by superoxide dismutase and abolished by methylene blue and oxyhemoglobin. Recently, the role of lipoxygenase products in the production of EDRF was evaluated with new 5-lipoxygenase inhibitors without antioxidant activity. During the last couple of years, the actions and chemical properties of EDRF were verified to be quite similar to those of nitric oxide (NO); therefore, the hypothesis of "EDRF = NO" is widely being accepted. NO is produced from L-arginine via catalysis by an enzyme that is activated by Ca2+. The enzyme activity is inhibited by L-monomethyl arginine and other L-arginine analogs. Chemical and physical stimulations increase intracellular Ca2+ in endothelial cells that seems to be associated with K(+)-channel opening and hyperpolarization. Current interests are directed to the possible roles of NO in the regulation of nerve function. There are evidences suggesting that NO modulates adrenergic nerve function in blood vessels and some brain cell functions regulated by cellular cyclic GMP. Particularly, NO may be a transmitter substance in non-adrenergic, non-cholinergic vasodilator nerves innervating the cerebral arteries. Future investigations will determine the physiological roles of EDRF or NO and its relationships to pathophysiology of vascular dysfunctions, such as vasospasm and those related to hypertension, diabetes, aging, etc., and the extended roles of NO in nerve function, inflammation, immune reactions, etc. would be clarified more extensively by accelerated progress in this field of research.

Animals↗
PubMed1990

Modification by L-NG-monomethyl arginine (L-NMMA) of the response to nerve stimulation in isolated dog mesenteric and cerebral arteries.

Treatment with L-NG-monomethyl arginine (L-NMMA) increased the vasoconstriction induced by adrenergic nerve stimulation in perfused dog mesenteric artery segments and suppressed the relaxant response to transmural nerve stimulation in dog cerebral artery strips, the effects of L-NMMA being reversed by L-arginine. The observed changes in nerve function may be associated with the inhibition of synthesis of nitric oxide.

Animals↗
PubMed1990

Role of nitric oxide in non-adrenergic, non-cholinergic nerve-mediated relaxation in dog duodenal longitudinal muscle strips.

Transmural electrical stimulation caused a relaxation in the dog duodenal longitudinal muscle strips treated with atropine, phentolamine and propranolol, which was abolished by tetrodotoxin. The relaxation was suppressed by oxyhemoglobin and L-NG-nitro-arginine (L-NA), but not influenced by D-NA. Inhibition by L-NA was reversed by L-arginine, but not by D-arginine. The response to transmural electrical stimulation was similar to that caused by nitric oxide or nitroglycerin. Nitric oxide appears to participate importantly in non-adrenergic, non-cholinergic nerve-mediated relaxation.

Animals↗
PubMed1990

Distribution of catecholaminergic receptors in the rat's pancreas islet.

The effects of noradrenaline, adrenaline, isoproterenol, dopamine, apomorphine and their blockers on biphasic insulin secretion induced by 0.3% glucose were observed by means of a modified Lacy's perifusion method. Noradrenaline and adrenaline completely inhibit biphasic insulin secretion, and their effects disappeared completely after pretreatment with phentolamine. Dopamine inhibited the first phase completely and inhibited the second phase partially, and the inhibitory action of the dopamine disappeared after the pretreatment with phentolamine or propranolol. Isoproterenol had no effect on glucose-induced insulin secretion, whereas after treatment with phentolamine, isoproterenol produced a first-phase type of response. Domperidone blocked the effect of dopamine on the suppression of the first phase response. Apomorphine produced the second phase suppression slightly. It was concluded that the sympathetic alpha receptor and DA1 was distributed on the B-cells, the sympathetic beta 2 receptors on the D-cell and the DA2 on the varicosity of the sympathetic beta 2 neuron.

Animals↗
PubMed1990

Granulocyte-macrophage colony-stimulating factor suppresses induction of neutrophil alkaline phosphatase synthesis by granulocyte colony-stimulating factor.

We evaluated the in vitro effects of recombinant human (rh) granulocyte colony-stimulating factor (G-CSF) and rh granulocyte-macrophage CSF (GM-CSF) on neutrophil alkaline phosphatase (NAP) activity and the incorporation of amino acids into polymorphonuclear leukocytes (PMN) from normal individuals and patients with chronic myelogenous leukemia (CML). Both the NAP activity and incorporation of amino acids into PMN were enhanced by the addition of G-CSF in a dose-dependent manner. NAP activity induced by G-CSF in PMN from CML patients showed a greater increase than that in PMN from normal controls. In contrast to G-CSF, GM-CSF did not affect the NAP activity in PMN in spite of the enhanced incorporation of amino acids into PMN by GM-CSF. Interestingly, both the NAP-inducing ability of G-CSF and its enhancing ability for amino acid incorporation were suppressed by GM-CSF in a dose-dependent manner when PMN were incubated with various concentrations of GM-CSF in addition to 100 ng/ml of G-CSF. These observations suggest that G-CSF and GM-CSF act differently: G-CSF induces NAP synthesis in PMN, whereas GM-CSF negatively modulates the effect of G-CSF. Further, it is suggested that protein synthesis induced by G-CSF is negatively modulated by GM-CSF in a general fashion.

Alkaline Phosphatase↗
PubMed1990

[Adult T-cell leukemia/lymphoma associated with unusual positivity of anti-ATLA (adult T-cell leukemia-cell-associated antigen) antibodies].

A 56-year-old female was admitted because of generalized lymphadenopathy. Based upon histological findings of biopsied lymph node, malignant lymphoma, diffuse large cell type was diagnosed. The surface marker analysis showed that malignant cells were positive for CD4 and CD2 but negative for CD8. Although anti-ATLA (adult T-cell leukemia associated antigen) antibody was negative with the use of a gelatin particle agglutination method (P.A.), other methods such as an indirect immunofluorescence assay (I.F.), an enzyme-linked immunosorbent assay (E.I.A.) and a Western blotting assay revealed the positivity for anti-ATLA antibody. Adult T-cell leukemia/lymphoma (ATL/L) was confirmed by the presence of monoclonal integration of HTLV-I proviral DNA in biopsied specimen. This case, showing a pattern of P.A. (-) and I.F. (+), is extremely unusual, because I.F. and P.A. show highly close correlation. Thus, it is important to employ different methods for screening of anti-ATLA antibodies in the diagnosis of ATL/L.

Agglutination Tests↗
PubMed1990

Inhibitory effect of an anti-lipoxygenase agent on immunoglobulin G-mediated anaphylactic contraction of single smooth muscle cells.

Intracellular signal transduction during anaphylactic contractions of smooth muscle and the site of signal generation, or antigen-antibody reaction, participating in the appearance of these contractions were studied. The taenia coli was removed from a guinea-pig which had previously been sensitized with anti-egg albumin (EA) rabbit serum or anti-EA rabbit immunoglobulin G (IgG) fraction. Dispersed smooth muscle cells, obtained after enzymatic digestion, were used as the specimen. The dispersed single smooth muscle cells sensitized with anti-EA rabbit IgG fraction showed anaphylactic contractions in response to antigen administration. The method using enzyme-linked antibody revealed binding of IgG by these single muscle cells. Anaphylactic contractions of the single cells were not inhibited by antihistamines or anti-5-hydroxy-tryptamine (5HT) agents, but they were suppressed by Y-19,432 [1-butyl-5-hydroxy-2-methyl-N-[1-(2-phenylethyl)-4-piperidyl] indole-3-carboxamide hydrochloride hydrate], an inhibitor of 5-lipoxygenase. The anaphylactic contractions of the single smooth muscle cells of the guinea-pig taenia coli appear to be initiated in response to IgG binding with the antigen bound to the smooth muscle plasma membrane. For contraction development, the lipoxygenase pathway was shown to participate as a part of the intracellular signal transduction.

Anaphylaxis↗
PubMed1990

Suppression by methylene blue of prostaglandin I2 synthesis in isolated dog renal arteries.

In dog renal artery strips with intact and damaged endothelium, relaxations induced by angiotensin II possibly mediated via the release of prostaglandin (PG) I2 were abolished or reversed to contractions by treatment with methylene blue and indomethacin. Relaxations elicited by arachidonic acid were also inhibited markedly. PGH2-induced contractions in the arteries with endothelium were potentiated, and relaxations caused by PGH2 in the endothelium-denuded arteries were suppressed by methylene blue, whereas these responses were not influenced by indomethacin. Relaxant responses to PGI2 and beraprost, a stable analog of PGI2, were not reduced by methylene blue. The amount of 6-keto PGF1 alpha in the bathing media released from the renal artery was decreased by treatment with methylene blue and indomethacin, whereas amounts of PGE2 and thromboxane B2 were not influenced by methylene blue but were reduced by indomethacin. It may be concluded that methylene blue interferes with the synthesis and release of PGI2 in the dog renal arteries; therefore, the relaxation mediated by endogenous PGI2 is suppressed. However, methylene blue does not appear to inhibit the synthesis of other cyclooxygenase products.

Angiotensin II↗
PubMed1990

[Clinical evaluation of protocol for the craniomandibular disorders. 2. Craniomandibular disorders according to new classification].

The purpose of this study is to clarify the actual state in the patients with extensive pathological states of craniomandibular disorders (CMDs). 100 patients, with their ages ranging from 11 to 77 years old, were selected for the study and they were divided into 5 groups according to classification of Japanese Society for Temporomandibular Joint. The following results were obtained: 1. By classification type, the ratio was 88, 16, 8 and 2% for Type III, Type I, Type IV and Type II. Type V was not found. 2. 22% of patients were male and 78% were female. The ratio of male and female was 1:4. 3. By age group, the ratio was 34, 23, 18, 12, 11, 1 and 1% for twenties, tens, thirties, fifties, forties, sixties and seventies. CMDs was found highly in younger ages (tens and twenties). 4. The ratio diagnosed Type III was 86.9, 97.0, 88.8 and 83.3% for tens, twenties, thirties and forties. Type III was found high ratio in all ages. 5. In all patients, right TMJ with disorder 37%, left TMJ with disorder 34%, bilateral TMJ with disorder 29%. There were no difference between right and left. 6. As can be seen from the above, young individuals with CMDs were clearly high ratio and many CMDs were diagnosed Type III through all the ages. Therefore, the results of our study suggest that young CMDs patients could be increasing gradually and complicating a pathological state.

Adolescent↗
PubMed1990

[Clinical evaluation of protocol for the craniomandibular disorders. 3. Questionnaire for the craniomandibular disorders].

The purpose of this study is to clarify the effectiveness of questionnaire which is included in the protocol designed for screening the patients with extensive pathological states of craniomandibular disorders. 100 patients, with their ages ranging from 11 to 77 years old, were selected for the study and they were classified under various disorder classification which is based on the criteria of Japanese society for Temporomandibular Joint. Statistical analysis was performed to find the relationship between the different pathological states and the results of the questionnaire. The following results were obtained: 1. The ratio of appearance on TMJ pain was as follows: Type I (100%), Type II (0%), Type III (43.8-75.0%) and Type IV (75.0%). 2. The ratio of appearance on TMJ pain on chewing was as follows: Type I (50.0%), Type II (100%), Type III (20.0-100%) and type IV (37.5%). 3. The ratio of appearance on TMJ pain on maximum opening was as follows: Type I (100%), Type II (100%), Type III (50.0-100%) and Type IV (75.0%). 4. The ratio of appearance on TMJ noise was as follows: Type I (0%), Type II (0%), Type III (40.9-81.3%) and Type IV (50.0%). 5. The ratio of appearance on the fatigue by mastication was as follows: Type I (0%), Type II (50.0%), Type III (40.0-100%) and Type IV (75.0%). 6. The ratio of appearance on bruxism was as follows: Type I (0%), Type II (0%), Type III (10.4-40.0%) and Type IV (25.0%). 7. The ratio of appearance on the stiff of jaw on awakening was as follows: Type I (50.0%), Type II (0%), Type III (20.8-70.0%) and Type IV (37.5%). 8. The ratio of appearance on the unilateral chewing was as follows: Type I (50.0%), Type II (0%), Type III (20.0-50.0%) and Type IV (62.5%). 9. There were significances among those types about each items on the questionnaire, it can be suggested that the questionnaire for screening about craniomandibular disorders was effective.

Adolescent↗