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Biomedical subjects

R Shibata

Publications and source records attributed to R Shibata.

At least 55 records · Page 3Linked to original sources
PubMed1996

Development of protamine-bonded phase for separation of saccharides in liquid chromatography.

A protamine-bonded polymer gel was synthesized by passing this protein through an activated carbamate polyamine polymer gel layer. This new packing material was suitable for versatile separation of monosaccharides, oligosaccharides, sugar alcohols and uronic acids in liquid chromatography. The column packed with this gel could be operated at room temperature and gave excellent recovery for the reducing monosaccharides such as 2-deoxyribose, 2-deoxyglucose, ribose and mannose for which the conventional alkylamine-bonded phase column gave poor recovery. This column was used for the analysis of saccharides in urine using a post-column reaction detection system.

Amino Acid Sequence↗
PubMed1996

Genetic complementation between replication-defective mutants of HIV-1 and SIVagm.

To investigate the functional complementation of essential genes for virus growth between HIV-1 and SIVagm derived from African green monkeys, we co-transfected replication-defective molecular clones containing mutations in gag, pol, env, tat or rev, and monitored transient complementation by reverse transcriptase assay (RT), cytopathic effect (CPE) and immunofluorescence assay (IFA). The following results were obtained: 1) No complementation was observed in combinations of the gag and pol mutants. 2) The rev mutant of HIV-1 was minimally complemented by other SIVagm mutants, although the rev mutant of SIVagm was significantly complemented by other HIV-1 mutants. 3) Among all combinations tested, the env mutant of HIV-1 was the most effectively complemented by SIVagm mutants. 4) CPE was mostly absent in combinations of the env mutant of SIVagm and the gag, pol, or tat mutants of HIV-1, although there were significant positive results in RT and IFA assays. These findings provided basic information about the functional compatibility of pathogenic HIV-1 and nonpathogenic SIVagm which will be useful for generating chimeras of these two viruses.

Animals↗
PubMed1996

The role of low-density lipoprotein apheresis as postoperative care of bypass grafting for chronic arterial occlusion.

Since November 1989, low-density lipoprotein apheresis has been applied to patients with intractable hyperlipidaemia following bypass grafting for chronic arterial occlusion of the lower extremities. The treatment group comprised six patients (four men, two women) with arteriosclerosis obliterans. In five patients, the ankle pressure index deteriorated and intermittent claudication recurred due to atherosclerotic progression. Results of low-density lipoprotein apheresis were dramatic; the deteriorated ankle pressure index and intermittent claudication improved significantly after several applications of low-density lipoprotein apheresis. Significant angiographic improvement was obtained in two patients. It is concluded that low-density lipoprotein apheresis appears to be an efficient method to preserve graft patency and treat postoperative patients with deteriorated ankle pressure index.

Angiography↗
PubMed1996

Brain SPECT of Creutzfeldt-Jakob disease.

SPECT imaging with I-123 IMP or Tc-99m HMPAO was performed in two patients with Creutzfeldt-Jakob disease to evaluate abnormalities in brain perfusion. In the first patient, there was decreased perfusion of the left frontal, parietal, and temporal lobes. CT and MRI were negative. In the second patient, there was patchy perfusion and slightly decreased perfusion of the right hemisphere. MRI revealed slight brain atrophy and bilateral high intensity areas in the basal ganglia on T2 weighted images. Subsequent SPECT imaging revealed severely decreased perfusion of the entire brain. Subsequent MRI demonstrated severe brain atrophy.

Aged↗
PubMed1996

Genomic and biological alteration of a human immunodeficiency virus type 1 (HIV-1)-simian immunodeficiency virus strain mac chimera, with HIV-1 Env, recovered from a long-term carrier monkey.

A macaque monkey infected with NM-3, a human immunodeficiency virus type 1 (HIV-1)-simian immunodeficiency virus strain mac (SIVmac) chimeric virus with env, rev, tat and vpu derived from HIV-1 and LTR, gag, pol, vif and vpx derived from SIVmac, became a long-term carrier (more than 2.8 years). This monkey produced neutralizing antibodies to the original NM-3 as well as to the parental HIV-1. The virus recovered at 116 weeks replicated more rapidly and productively in macaque peripheral blood mononuclear cells than the original virus. The recovered virus was not neutralized either by antibodies raised early in the monkey or by a neutralizing monoclonal antibody that recognizes the V3 loop of HIV-1 Env, whereas both the early antibodies and the monoclonal antibody neutralized the original NM-3. Analysis of the virus genomic population revealed a few common mutations in the V3 region that caused amino acid changes. These data are consistent with the hypothesis that the virus escaped from the early antibodies and that the observed mutations contributed to this, as with HIV-1-infected humans. The observed mutations could equally well be the result of adaptation to simian cells. These results suggest that the HIV-1-SIVmac chimeric virus will be useful for investigating genetic variation of HIV-1 env and alteration of biological properties in vivo in relation to the host immune response.

Amino Acid Sequence↗
PubMed1996

Infection of chimpanzee peripheral blood mononuclear cells by human immunodeficiency virus type 1 requires cooperative interaction between multiple variable regions of gp120.

We have recently reported the isolation and molecular cloning of a human immunodeficiency virus type 1 isolate (HIV-1 DH125) that exhibits rapid replication kinetics and marked cytopathicity in both human and chimpanzee peripheral blood mononuclear cells (PBMC). To identify the viral determinants responsible for infectivity of chimpanzee PBMC, chimeric viruses containing the following components were constructed: (i) the entire envelope gene; (ii) gp120 sequences; (iii) gp41 sequences; and (iv) individual or various combinations of the gp120 variable regions of HIV-1 DH125 inserted into the backbone of another HIV-1 isolate (HIV-1 AD8), which is unable to infect chimpanzee PBMC. Analyses of virus replication kinetics in human and chimpanzee PBMC revealed that gp120 contains determinants which confer infectivity for chimpanzee PBMC and that the capacity to establish such an infection requires the cooperative interaction between multiple variable regions of the HIV-1 DH125 gp120.

Animals↗
PubMed1996

Resistance of previously infected chimpanzees to successive challenges with a heterologous intraclade B strain of human immunodeficiency virus type 1.

To test whether the protective effects of attenuated simian immunodeficiency virus vaccines in macaques were applicable to the human immunodeficiency virus type 1 (HIV-1)-chimpanzee system, two groups of animals, previously infected with HIV-1(IIIB) or HIV-1(SF2) were each challenged with a heterologous clade B virus, HIV-1(DH12). Following challenge, the parameters measured included virus isolation (from plasma, peripheral blood mononuclear cells, and lymph node tissue); quantitative DNA PCR using primers capable of distinguishing HIV-1(IIIB), HIV-1(SF2), and HIV-1(DH12) from one another; and serologic assays to monitor changes in binding and neutralizing antibodies. In contrast to an HIV-1-naive chimpanzee that rapidly became infected following the inoculation of HIV-1(DH12), the two chimpanzees previously infected with HIV-1(IIIB) resisted repeated and escalating inoculations of HIV-1(DH12), as monitored by virus isolation and PCR. The two animals previously infected with HIV-1(SF2) became infected with HIV-1(DH12) but in contrast to the case with the HIV-1-naive chimpanzee, no cell-free viral RNA was detected in the plasma by the branched DNA procedure and levels of peripheral blood mononuclear cell-associated viral DNA were reduced 35- to 50-fold.

AIDS Vaccines↗
PubMed1996

Differential glycosylation, virion incorporation, and sensitivity to neutralizing antibodies of human immunodeficiency virus type 1 envelope produced from infected primary T-lymphocyte and macrophage cultures.

Two primary cell targets for human immunodeficiency virus type 1 (HIV-1) infection in vivo are CD4+ T lymphocytes and monocyte-derived macrophages (MDM). HIV-1 encodes envelope glycoproteins which mediate virus entry into these cells. We have utilized infected and radiolabelled primary peripheral blood mononuclear cell (PBMC) and MDM cultures to examine the biochemical and antigenic properties of the HIV-1 envelope produced in these two cell types. The gp120 produced in MDM migrates as a broad, diffuse band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels compared with that of the more homogeneous gp120 released from PBMCs. Glycosidase analyses indicated that the diffuse appearance of the MDM gp120 is due to the presence of asparagine-linked carbohydrates containing lactosaminoglycans, a modification not observed with the gp120 produced in PBMCs. Neutralization experiments, using isogeneic PBMC and MDM-derived macrophage-tropic HIV-1 isolates, indicate that 8- to 10-fold more neutralizing antibody, directed against the viral envelope, is required to block virus produced from MDM. These results demonstrate that HIV-1 released from infected PBMC and MDM cultures differs in its biochemical and antigenic properties.

Autoradiography↗
PubMed1996

[Simultaneous mitral valve replacement and splenectomy in a patient with chronic idiopathic thrombocytopenic purpura].

A 57-year-old female with valvular heart disease and chronic idiopathic thrombocytopenic purpura (ITP) underwent successful open-heart surgery. Preoperative administration of steroids and high-dose gamma-globulin increased the platelet count from 3 x 10(4)/microgram at admission to 10 x 10(4)/microgram before the operation. Splenectomy followed by mitral valve replacement (SJM 27M) were performed simultaneously. No platelet transfusion needed during and after the operation owing to rapid increase in platelets that would occur following splenectomy. The postoperative course was uneventful. The present simultaneous splenectomy and open-heart operation appears to be a safe and effective procedure for minimizing perioperative blood loss in patients with ITP and heart disease.

Chronic Disease↗
PubMed1995

Myocardial recovery during post-ischemic reperfusion: optimal concentrations of Na+ and Ca2+ in the reperfusate and protective effects of amiloride added to cardioplegic solution.

The effects of Na+ and Ca2+ concentrations in the reperfusate on post-ischemic myocardial recovery were examined. Also, the myocardial protective effects of amiloride, an inhibitor of the Na+/Ca2+ and Na+/H+ exchange systems, added to cardioplegic solutions were assessed, using an isolated working rat heart perfusion system. Global myocardial ischemia was induced by 30-min normothermic cardioplegic arrest, using St. Thomas' solution. The concentration of Na+ in the reperfusate varied, stepwise, from 75 to 145 mM/l, and that of Ca2+, from 0.1 to 2.5 mM/l. In this study post-ischemic functional recovery was best at 110mM/l Na+ and 1.2-1.8 mM/l Ca2+ in the reperfusate. A significantly greater post-ischemic functional recovery and a lower creatine kinase release were observed when amiloride was added to the cardioplegic solution. Ca2+ overload via Na+/Ca2+ and Na+/H+ exchange systems would, thus, appear to be due, at least in part, to post-ischemic reperfusion injury.

Amiloride↗
PubMed1995

Hypofrontality does not occur with 6-hydroxydopamine lesions of the medial prefrontal cortex in rat brain.

This study examined the effect of lesions of dopamine (DA) nerve terminals the medial prefrontal cortex on local cerebral glucose utilization (LCGU) and dopamine metabolism in the rat brain. Bilateral 6-hydroxydopamine lesions were stereotaxically placed in the medial prefrontal cortex. Twenty-eight days after the lesion, concentrations of DA and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were determined in eight brain regions with a high-performance liquid chromatographic assay. LCGU was assessed by [14C]2-deoxy-D-glucose autoradiography. The lesion produced a striking reduction in DA (to 6% of the control value), and a moderate reduction in DOPAC and HVA in the medial prefrontal cortex. The ratio of DOPAC to DA in the medial prefrontal cortex was significantly elevated in the 6-OHDA lesioned animals. In contrast to DA depletion, LCGU in the medial prefrontal cortex of the lesioned rats was unaltered when compared with the control. These findings suggest that decreased energy metabolism in the frontal cortex, i.e., hypofrontality, does not occur with decreased DA innervation of that site.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1995

Effect of 6-hydroxydopamine lesions of the medial prefrontal cortex of the rat on performance in a reaction time task.

Rats were trained to keep pressing a panel and then release it within a time limit after a light cue. Reaction time was measured from the light cue to the release of the panel. In 'regular' preparatory interval (PI) sessions, the rat had to wait (keep pressing the panel) for a light cue during an interval fixed in a session. In 'irregular' PI sessions, which followed regular PI sessions, intervals until a light cue presentation changed randomly from trial to trial in a session. Rats lesioned by 6-hydroxydopamine infusion into their medial prefrontal cortices showed shorter and more stable reaction times in irregular PI sessions than sham-operated control rats. Cross-over patterns of reaction time of the lesioned rats were not as clear as those of the control rats. Impairment of mnemonic predictive function might underlie the reaction time features in irregular PI sessions in the lesioned rats.

Animals↗
PubMed1995

Effects of 6-hydroxydopamine lesions of the medial prefrontal cortex on local cerebral blood flow and D1 and D2 dopamine receptor binding in rats: a quantitative autoradiographic study.

The effects of lesions of the dopamine (DA) nerve terminals in the medial prefrontal cortex (MPFC) on local cerebral blood flow (LCBF) and DA receptor binding in rats were investigated. 4 micrograms of 6-hydroxydopamine (6-OHDA) was infused stereotaxically into the area of the bilateral MPFC of rats pretreated with desmethylimipramine, and control rats received a vehicle solution. Twenty-four days after the operation LCBFs of 23 brain regions were measured using the quantitative autoradiographic N-isopropyl-p-[125I]iodoamphetamine technique D1 and D2 DA receptor binding in various brain regions was also quantified autoradiographically using [3H]SCH 23390 and [3H]YM 09151-2 as the respective ligands. 6-OHDA lesions of MPFC produced significant increases in LCBF of the nucleus accumbens, the dorsolateral portion of the caudate-putamen and the anterior cingulate cortex. The lesioned animals did not show decreased LCBF in MPFC per se. D1 and D2 DA receptor binding was not affected in any brain region examined. These results suggest that lesions of the DA nerve terminals in MPFC induce an enhancement of functional activity in the terminal regions of the subcortical DA systems, and that hypofunction of the mesocortical dopamine system does not elicit reduced metabolic activity in the prefrontal cortex.

Animals↗
PubMed1995

Early replication block of human immunodeficiency virus type 1 in monkey cells.

The genetic and functional basis of the replication-defective nature of human immunodeficiency virus type 1 (HIV-1) in monkey cells was studied. By the generation and characterization of chimeras between HIV-1 and simian immunodeficiency virus, the sequence encompassing the 3' half of the long terminal repeat, gag and pol genes of HIV-1 was found to be responsible for the growth restriction. Early and late phases of HIV-1 replication in monkey cells were analysed in detail using several assay systems: transfection/coculture, transcomplementation between various proviral clones carrying the CAT gene and effector clones and evaluation of transcription and reverse transcription. All the data were consistent with the notion that HIV-1 replication is blocked at a very early stage(s) such as uncoating and/or reverse transcription in monkey cells.

Animals↗
PubMed1995

Isolation and characterization of a syncytium-inducing, macrophage/T-cell line-tropic human immunodeficiency virus type 1 isolate that readily infects chimpanzee cells in vitro and in vivo.

Fresh human immunodeficiency virus type 1 (HIV-1) isolates from patients with AIDS were screened for infectivity in chimpanzee peripheral blood mononuclear cells (PBMC) to identify strains potentially able to generate high virus loads in an inoculated animal. Only 3 of 23 isolates obtained were infectious in chimpanzee cells. Of these three, only one (HIV-1DH12) was able to initiate a productive infection in PBMC samples from all 25 chimpanzees tested. HIV-1DH12 tissue culture infections were characterized by extremely rapid replication kinetics, profound cytopathicity, and tropism for chimp and human PBMC, primary human macrophage, and several human T-cell lines. An infection was established within 1 week of inoculating a chimpanzee with 50 50% tissue culture infective doses of HIV-1DH12; cell-free virus was recovered from the plasma at weeks 1, 2, and 4 and was associated with the development of lymphadenopathy. Virus loads during the primary infection and at 6 months postinoculation were comparable to those reported in HIV-1-seropositive individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1995

[Vascular irritability study of montirelin hydrate (NS-3) injection in rabbits].

A vascular irritability study of montirelin hydrate (NS-3) injection, a new drug for the treatment of disturbance of consciousness, was conducted in Japanese white rabbits. The concentration of montirelin hydrate was 4 mg/ml. Saline and 0.75% acetic acid were used as negative and positive control, respectively. In a part of the ear vein, 0.05 ml of each compound was allowed to remain for 3 min after intravenous injections once a day for 8 days. Inflammation in peri-venous region and thrombus were macroscopically observed in injection sites of rabbits with the montirelin hydrate injection group. However, no changes were seen with the negative control group. Histopathological examination revealed periphlebitis, desquamation of endothelial cells and thrombus in rabbits given montirelin hydrate injection or saline. But incidence and degree of periphlebitis caused by montirelin hydrate injection were higher than those caused by saline. On the other hand, the irritating changes caused by 0.75% acetic acid were severer than those by montirelin hydrate injection. These results show that montirelin hydrate injection has a very weak vascular irritability in the ear of rabbits.

Animals↗
PubMed1994

Comparative study of dopamine metabolism with local cerebral glucose utilization in rat brain following the administration of haloperidol decanoate.

The effects of haloperidol decanoate on dopamine (DA) metabolism in discrete regions of rat brain were investigated and compared with changes in local cerebral glucose utilization (LCGU). The concentration of DA and its metabolite, homovanillic acid, and the alpha-methyl-p-tyrosine (alpha-MT)-induced decline of DA were measured in 6 brain regions by a high-performance liquid chromatographic assay. LCGU in 26 brain regions were examined by [14C]2-deoxy-D-glucose autoradiography. At 24-hr after intramuscular injection of haloperidol decanoate (60 mg eq/kg to haloperidol), the concentration of homovanillic acid in the prefrontal cortex, caudate-putamen, accumbens nucleus, lateral amygdala, and medial thalamus showed significant increase compared with control values. On day 21, the increase in these regions was significantly attenuated with no significant difference from the controls. Furthermore, chronic haloperidol rats showed alpha-MT-induced decline of DA to a similar extent in the control rats. LCGU on day 21 showed significant decrease in the parietal cortex, and a tendency toward decrease in the prefrontal cortex, lateral amygdala and medial thalamus compared with the controls. There was no significant change in LCGU in the caudate-putamen or accumbens nucleus. Chronic haloperidol would thus appear to affect energy metabolism mainly in the cortico-thalamo-limbic circuits, and this may not correspond well to presynaptic DA metabolism.

Animals↗