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Biomedical subjects

T Oshima

Publications and source records attributed to T Oshima.

At least 487 records · Page 27Linked to original sources
PubMed1985

Reconstitution of the GTP-dependent adenylate cyclase from products of the yeast CYR1 and RAS2 genes in Escherichia coli.

Plasmids carrying the CYR1 gene of yeast Saccharomyces cerevisiae, which encodes adenylate cyclase, were introduced into the cya mutant strain of Escherichia coli. The transformants had a GTP-independent adenylate cyclase activity but did not produce cAMP. The E. coli transformant carrying the yeast RAS2 or RAS2val19 gene had no adenylate cyclase activity. Transformant cells carrying both CYR1 and RAS2 produced GTP-dependent adenylate cyclase and cAMP, and those carrying CYR1 and RAS2val19 produced GTP-independent adenylate cyclase and a large amount of cAMP. Production of cAMP in the transformant carrying CYR1 and either RAS2 or RAS2val19 was confirmed by staining colonies on maltose-MacConkey plates and by measuring induction of beta-galactosidase by isopropyl beta-D-thiogalactopyranoside. Mixing a crude extract from the E. coli transformant carrying CYR1 with a crude extract from cells carrying RAS2 reconstituted the GTP-dependent adenylate cyclase. Reconstitution of the GTP-dependent adenylate cyclase was observed by mixing the plasma membrane fraction of yeast CYR1 ras1 ras2 bcy1 mutant and a crude extract from the E. coli transformant carrying RAS2 or by mixing a crude extract from the E. coli transformant carrying CYR1 and the membrane fraction of yeast cyr1 RAS1 RAS2 BCY1 mutant. The data suggest that the yeast GTP-dependent adenylate cyclase consists of catalytic and regulatory subunits encoded by the CYR1 and RAS2 genes, respectively.

Adenylyl Cyclases↗
PubMed1985

Induction of a marked eosinophilia by cyclophosphamide in Toxocara canis infected SJL mice.

Cyclophosphamide (Cy) is known to produce a marked eosinophilia in mice after antigen challenge. In this study, we studied the effect of Cy on eosinophilia in helminthic infection. Peripheral blood eosinophils were counted in SJL mice following a large dose of Cy injection, infection with Toxocara canis, and both Cy injection and T. canis infection simultaneously. Following the injection with Cy (150 mg/kg), the eosinophil counts fell sharply, then rose abruptly to six times the normal level followed by a decrease. Infection with T. canis induced eosinophilia in mice. However, when mice were both infected with T. canis and given Cy injection, the eosinophilia was markedly enhanced. The results suggest that the marked eosinophilia in mice induced by Cy is not only observed in antigen challenge but also in helminthic infection.

Animals↗
PubMed1985

Comparative vascular pharmacology of the atriopeptins.

The atriopeptins are potent relaxants of norepinephrine-constricted aortic strips or are dilators of renal blood vessels in isolated perfused rat kidneys that are constricted by norepinephrine. This vasorelaxant property of the atriopeptins requires the presence of phenylalanine arginine (i.e., atriopeptin II, III, or ser-leu-arg-arg atriopeptin III) residues in the carboxy terminus which are considerably more effective than atriopeptin I (the 21 amino acid peptide which lacks the phe-arg C-terminus) or the core peptide (residues 3-19). However, these artificially in vitro precontracted preparations do not accurately predict the vascular effectiveness of the atriopeptins in intact rats. Intravenous administration of the atriopeptins (including atriopeptin I) to anesthetized rats produces concentration-dependent hypotension, a selective decrease in renal resistance in low doses (determined with microspheres), and pronounced diuresis. At higher doses, atriopeptins increase blood flow in other vascular beds. On the other hand, in the anesthetized dog, injection (intraarterially) of the phe-arg-containing peptides produces a concentration-dependent increase in both renal blood flow and sodium excretion, whereas atriopeptin I is inactive. Although there is a species difference in responsiveness to atriopeptin I, these data demonstrate a direct correlation between the renal vasodilation and diuresis produced by this novel family of atrial peptides.

Animals↗
PubMed1985

Vertical spread of neuronal activity within the cat motor cortex investigated with epicortical stimulation and intracellular recording.

In the encéphale isolé cat preparation the surface of precruciate cortex was electrically stimulated. Intracellular responses underneath the stimulated site were recorded to assess the vertical spread of activities across the cortical layers. To the epicortical stimulation (EPICS) with intensity adjusted to evoke a pure negative wave in the direct cortical response (DCR), only some neurons in relatively superficial layers responded with excitatory postsynaptic potentials (EPSPs). Stimuli intensified to evoke both the negative and subsequent positive waves in DCR produced in all tested cells either EPSPs, inhibitory postsynaptic potentials (IPSPs), or both. Direct or axonal antidromic excitation of the cell was observed only infrequently. Cells with EPSPs distributed through all the layers with two peak populations in laminae II and V-VI. Those with IPSPs were located mainly in the upper half of lamina III with a few in more superficial as well as in deeper layers. Both EPSPs and IPSPs showed mono- or oligosynaptic latencies (0.6-10 msec) that tended to become longer in deep than in superficial layers. Some deep layer cells including fast and slow pyramidal tract cells showed slowly rising monosynaptic EPSPs of dendritic origin. Further late responses consisted of EPSPs, IPSPs, disfacilitation (DF), and disinhibition (DI). DF or DI occurred in some deep layer cells. Two modes of vertical spread of activities were postulated: one the cascade transmissions which increased response repertoire toward the depths, and the other the electrotonic spread of EPSPs along dendrites.

Animals↗
PubMed1985

Lateral spread of neuronal activity within the motor cortex investigated with intracellular responses to distant epicortical stimulation.

Lateral spread of activity within the motor cortex was examined by means of analyses of the direct cortical responses (DCRs) and intracellular responses to distant epicortical stimulation (EPICS) using cat encéphale isolé preparations. DCRs to the EPICS at a distance of 1.5-6.5 mm consisted of initial small positive (Pd) and subsequent negative waves (Nd). The reversal of polarity in depths occurred at 400-550 microns for Pd and at 150-250 microns for Nd as well as for the initial negative wave elicited by near EPICS. Intracellular responses to distant EPICS consisted of excitatory (EPSP) and inhibitory postsynaptic potentials (IPSP), disfacilitation (DF), and disinhibition (DI). Depth distributions of cells with EPSPs at two peaks in laminae II and V-VI, with IPSPs mainly in lamina III, and with DF or DI in laminae V-VI were the same with those by near EPICS. The inhibitory effects of distant EPICS on middle layer cells were much greater than those by near EPICS. No linear relations of the latency of EPSPs or IPSPs to the depth were seen for distant EPICS. Instead, the latency increased in proportion to the lateral distance in EPSPs at a slower rate than in IPSPs compared in superficial and middle layer cells. Several routes for lateral spread of activity were postulated. Most conspicuous are the excitatory route via horizontal axons in lamina I and the inhibitory route via laterally running axons in laminae II-III, which produce overall excitation of superficial layer cells and depression of middle and deep layer cells. Their possible role in phasic cortical arousal was discussed.

Animals↗
PubMed1985

Common response repertoire of motor cortical neurons in arousal and epicortical activation.

Intracellular responses during phasic Electroencephalograph (EEG) arousal were recorded from 229 motor cortical neurons in the cat encéphale isolé preparations. Identified dominant responses were excitatory postsynaptic potentials (EPSPs) in 105 cells (E cells), inhibitory postsynaptic potentials (IPSPs) in 74 cells (I cells), disfacilitation in 48 cells (DF cells), and disinhibition in two cells (DI cells). These responses were comparable with those to near or distant epicortical stimulation (EPICS). thus, most E cells in phasic arousal were EPSP-dominant in response to near (incidence, 104/105) or distant EPICS (51/54), and only a few of the remaining were IPSP-dominant. About two-thirds of I cells were IPSP-dominant (49/74), and the remaining one-third EPSP-dominant (25/74) to near EPICS. However, most I cells became IPSP-dominant (45/49) to distant EPICS. DF and DI cells were initially EPSP- or IPSP-dominant to EPICS, but later responsive with DF in DF cells and DI in DI cells, respectively. In the interaction experiments, the initial negative wave in the direct cortical responses (DCRs) or the EPSPs of dendritic origin elicited by near EPICS and the initial positive wave in DCRs to distant EPICS were all reduced during phasic EEG arousal perhaps due to the occlusion effect. Common response repertoire in EEG arousal and epicortical activation may support the earlier proposed cascade transmission model of phasic EEG arousal, in which the spread of neuronal activities occurs vertically from the superficial to deep cortical layers as well as laterally along various layers.

Animals↗
PubMed1985

Intracortical spread of neuronal activities induced by stimulation of recurrent and thalamic afferent pathways compared with epicortical activation.

In the encéphale isolé cat preparation the cerebral peduncle (CP) and the nucleus ventralis lateralis (VL) of the thalamus were stimulated. Short-latency responses recorded from precruciate cortical neurons consisted of excitatory (EPSP) and inhibitory postsynaptic potentials (IPSP). Laminar distributions of these responses and their latencies wee viewed as the spatiotemporal pattern of spread of excitation and inhibition within the cortex in comparison with those obtained by epicortical stimulation (EPICS). In contrast with activities by EPICS spreading downwards from superficial to deep layers, CP recurrent activities spread upwards from deep to middle or superficial layers, and those by VL afferents spread from middle to both superficial and deep layers bidirectionally. These three intracortical routes shared common cell assemblies in that they received convergent EPSPs or IPSPs to various extents from different inputs. The routes for EPICS and VL inputs were overlapped particularly with abundant supply of convergence in spite of their functional difference. Relevant potentiality of the cerebral network in forming plural patterns was discussed.

Afferent Pathways↗
PubMed1985

[Fundamental and clinical studies on aztreonam in the gynecological field].

Aztreonam (AZT), a new monocyclic beta-lactam antibiotic was studied on clinical efficacy for infectious disease in gynecological field. At about 80 minutes following intravenous injection of 1 g dose of AZT, it penetrated well into internal genital organs at therapeutic levels. Moreover it transferred very fast and enough into intrapelvic dead space exudate, and its level was kept still as high at 12 hours after administration. AZT was given to 20 women affected with gynecological infectious disease. The outcome of AZT therapy was as follows: effective in 5 out of 6 patients (83.3%) administered intravenously and in all of 14 patients (100%) received intramuscularly. Notable adverse effects or abnormal laboratory findings were not observed except 1 case of diarrhea and 2 cases of transient and slight elevation of serum CPK and transaminases. Based on these results, we may conclude that AZT is a highly effective and a very safe antibiotic for the treatment of infectious disease in gynecological field.

Adult↗
PubMed1985

Inhibitory effects of the 3'-noncoding region derived from eukaryotic cDNA on the expression of the upstream structure gene in E. coli.

The influence of 3'-noncoding region (ncr) of the cDNA derived from an eukaryotic mRNA on the preceding structure gene expression in E. coli was investigated using human immune interferon (GIF) and human tumor necrosis factor (TNF) cDNAs. Two sets of gene, with (ncr+) and without (ncr-) 3'-noncoding region, have been expressed in E. coli. In both cases, the level of ncr+ gene expression was five times lower than that of ncr- gene. When these ncrs were placed just downstream of various structure genes, the same effects were also observed. The RNA brot analysis showed that the ncr+ genes were transcribed into shorter and much less mRNA than ncr- genes. These results suggest that these ncrs accelerate the degradation of the mRNA by either causing the premature termination of transcription or the generation of sequence on the transcripts hypersensitive to E. coli endoribonucleases.

DNA↗
PubMed1985

[Surgical treatment of fusiform thoracoabdominal aortic aneurysm with Marfan's syndrome. A report on reconstruction of 4 major abdominal visceral branches].

A fusiform thoracoabdominal aortic aneurysm involving celiac, superior mesenteric and renal arteries was successfully replaced in a 53-year-old female with Marfan's syndrome who also had annuloaortic ectasia, dissecting aneurysm of descending aorta and bilateral subclavian arterial aneurysms. Exposure of the aneurysm was obtained with a thoracoabdominal incision by reflecting the abdominal viscera to the right. First the limbs of a 24 X 12mm dacron bifurcated prosthesis were attached to common iliac arteries in an end-to-side fashion. Then renal arteries were anastomosed end-to-end to the branches previously attached to the body of the prosthesis. With the temporary bypass from left subclavian to left limb of the dacron graft, reconstruction of the celiac and superior mesenteric arteries was performed by direct suture of orifices to the opening made in the graft. Proximal anastomosis between descending aorta and the graft was made in an end-to-end fashion. The dissecting lesion of the proximal descending aorta was wrapped by dacron mesh. The immediate postoperative course was uneventful except transient hepatitis and pneumonia. The patient was discharged 49 days after operation. One month later, however, she died suddenly. Autopsy could not reveal the exact cause of death. Retrograde revascularization combined with Crawford's method was useful in shortening the occlusion time.

Aorta, Abdominal↗
PubMed1984

High guanine plus cytosine content in the third letter of codons of an extreme thermophile. DNA sequence of the isopropylmalate dehydrogenase of Thermus thermophilus.

In studies on the cause of the extreme stability of the macromolecules of Thermus thermophilus HB8, the leuB gene coding for 3-isopropylmalate dehydrogenase of the leucine synthesis pathway and its flanking regions were cloned and sequenced. The leuB gene of T. thermophilus was expressed in a leuB-less mutant of Escherichia coli, and thermostable dehydrogenase was purified from an extract of the cells. The primary structure of the thermophilic isopropylmalate dehydrogenase was deduced from the nucleotide sequence leuB gene (1017 base pairs) and the amino acid sequence of the peptides isolated from the purified dehydrogenase. The thermophilic dehydrogenase has Mr = 35,968, and the value was close to that determined for the monomer of dehydrogenase (36,000) by gel electrophoresis. The molecular weight of active dimeric dehydrogenase was found to be 73,000 by high speed liquid chromatography. The primary structure of dehydrogenase was consistent with the amino acid composition of the dehydrogenase. In contrast to the isopropylmalate dehydrogenase of E. coli which contains 8 cysteine residues, there was no cysteine in thermophilic isopropylmalate dehydrogenase. The 5'-noncoding region contained a typical Shine-Dalgarno sequence. The guanine plus cytosine content of the coding region was 70.1%, and that of the third letter of the codons was extremely high (89.4%).

3-Isopropylmalate Dehydrogenase↗
PubMed1984

Survey of CELSS concepts and preliminary research in Japan.

Many agricultural and other experiments relating to the development of a Controlled Ecological Life Support System (CELSS) were proposed by scientists throughout Japan in the fall of 1982. To develop concrete experimental concepts from these proposals, the engineering feasibility of each proposal was investigated by a CELSS experiment concept study group under the support of the National Aerospace Laboratory. The conclusions of the group were described in two documents. Originally, the study group did not clearly define necessary missions leading to the goal of an operational CELSS for spaceflight. Therefore, the CELSS experiment concept study group met again to clarify the goals of CELSS and to determine three phases to achieve the goals. The resulting phases, or missions, and preliminary proposals and studies needed to develop a CELSS are described herein.

Animals↗
PubMed1984

Induction of peripheral blood eosinophilia in mice by excretory and secretory antigen of Toxocara canis larvae.

Medium in which T. canis larvae had been cultured was applied to a Sephadex G-25 gel column and four fractions (Fr. 1-Fr. 4) were isolated. Each fraction was administered to mice by implanting a mini-osmotic pump into the peritoneal cavity and the subsequent peripheral blood eosinophilic counts were recorded. Mice given Fr. 1 showed a markedly greater eosinophilic response than did those given the other fractions. Complement activation by each fraction was investigated using normal human serum. Fr. 1 and Fr. 3 had a capacity to activate complement. The results suggest that Fr. 1 may be not only antigenetic and allergenic but also could induce eosinophilia and activate complement.

Animals↗