Biomedical subjects

T Nishimura

Publications and source records attributed to T Nishimura.

At least 19 recordsLinked to original sources

PubMed1992

Assembly regulatory domain of glial fibrillary acidic protein. A single phosphorylation diminishes its assembly-accelerating property.

Phosphorylation of glial fibrillary acidic protein (GFAP) induces disassembly of the filaments. An amino-terminal fragment of bovine GFAP (G-Hf) was produced by lysylendopeptidase digestion. G-Hf formed ribbon-like filaments in the presence of GFAP even in low ionic strength, whereas the fragment itself did not form any structures. Only one (PK3) of the five V8 protease fragments of G-Hf accelerated GFAP assembly to the same degree as G-Hf did, whereas the other fragments did not. When PK3 was cleaved into two fragments, it lost the assembly-accelerating property. The sequence of PK3 was determined as RRRVTSATRRSYVSSSE, which corresponded to residues 3-19 of porcine GFAP. It was concluded that PK3 contains a sequence indispensable for GFAP assembly and that neither PK1 (RRRVTS) nor PK2 (ATRRSYVSSSE) included all of the sequence. A single phosphorylation of PK3 by cyclic AMP-dependent protein kinase diminished its assembly-accelerating property. The phosphorylation site was determined as Ser-12 of porcine GFAP. It was shown that single phosphorylation of the amino-terminal head domain, which contains an indispensable sequence for GFAP assembly, might be sufficient for GFAP disassembly.

Amino Acid Sequence↗

PubMed1992

Cellular and peptide requirements for in vitro clonal deletion of immature thymocytes.

Thymocytes from DO10 T-cell-receptor transgenic mice undergo apoptosis, or programmed cell death, when chicken ovalbumin-(323-339) peptide is administered in vivo. Using DO10 mice thymocytes, we have now developed a simple in vitro model system that recapitulates the in vivo clonal-deletion process. When transgenic thymocytes were cocultured with fibroblasts, B cells, or thymic nurse cell lines (all bearing I-Ad) in the presence of chicken ovalbumin-(323-339), deletion of the transgenic TCR+CD4+CD8+ thymocytes was seen within 8-20 hr. Thymocytes designed to bear I-Ad on their surface could mediate the deletion themselves. Thus, thymocyte clonal deletion entirely depends on the stage at which the thymocytes are vulnerable to the onset of apoptosis, rather than on the nature of the peptide antigen-presenting cells. Furthermore, thymic nurse cell line TNC-R3.1 could cause deletion, strongly suggesting that some thymic epithelial/stromal components are potentially capable of participating in negative selection. In all cases examined, little deletion could be induced at a peptide concentration less than 10 nM, thus defining the minimum amount of peptide antigen required for negative selection. The peptide-dependent in vitro negative-selection system will allow further dissection of the molecular and cellular processes involved in clonal deletion due to apoptosis in the thymus.

Amino Acid Sequence↗

PubMed1992

[Detectability of diagonal branch disease by 201TlCl exercised myocardial scintigraphy].

The detectability of diagonal branch disease in 10 patients (five with angina pectoris, five with myocardial infarction) with isolated diagonal branch lesions (more than 75% luminal stenosis in coronary angiography) was reviewed. In exercised 201TlCl myocardial scintigraphy, chest pain occurred in four of 10 patients, electrocardiographic change indicating myocardial ischemia was seen in four, and diagonal branch lesion was detected in only four patients by planar images. In contrast, diagonal branch lesions were detected in 10 of 10 patients by SPECT (single photon emission computed tomography). In planar images, perfusion defects appeared high in the anterolateral, posterolateral, and anterior walls of the left ventricle. In SPECT images they appeared high in the anterior to anterolateral wall. The extent of diagonal branch lesions could be quantitatively evaluated by coronary territory maps developed from unfolded maps of exercised SPECT. The mean ratio of the extent of diagonal branch lesion to left anterior descending branch territory was 24.7%, and the extent of myocardial infarction was significantly larger than that of angina pectoris (p < 0.05). In conclusion, SPECT is useful for detecting diagonal branch lesions and can quantitatively show the extent of these lesions by coronary territory map.

Aged↗

PubMed1992

Purification and properties of aminopeptidase H from chicken skeletal muscle.

Aminopeptidase H was purified from fresh chicken breast muscle by ammonium sulfate fractionation and successive chromatographies on DEAE-cellulose, Ultrogel AcA 34, activated thiol-Sepharose 4B, phenyl-Sepharose CL-4B and DEAE-cellulose again. The purified enzyme migrated as a single band on SDS/PAGE. Aminopeptidase H exhibits activity against both L-leucine beta-naphthylamide and alpha-N-benzoyl-DL-arginine beta-naphthylamide. The molecular mass of this enzyme was found to be 52 kDa on SDS/PAGE and 400 kDa on Sepharose 6B column chromatography. The optimum pH for the hydrolysis of both substrates was 8.0 and this activity was remarkably enhanced by reducing agents. The enzyme was strongly inhibited by monoiodoacetate and leupeptin, but not affected by EDTA, phenylmethylsulfonyl fluoride, pepstatin, bestatin or puromycin. Aminopeptidase H has been shown to hydrolyze di-, tri- and tetrapeptides in the manner of an aminopeptidase, as well as the beta-naphthylamide derivatives of amino acids. However, the enzyme has not been shown to hydrolyze proteins such as hemoglobin, bovine serum albumin, myofibrillar proteins or sarcoplasmic proteins.

Amino Acid Sequence↗

PubMed1992

[Raise up 99mTc-HMPAO brain SPECT for detecting the changes in cerebral perfusion pressure].

99mTc-HMPAO crossed the blood brain barrier instantly in proportional to cerebral blood flow. Raise up stress and supine resting 99mTc-HMPAO with brain SPECT was devised for detecting abnormal response in the changes of cerebral perfusion pressure. Asymmetric ratio in the middle cerebral artery area in patients with internal carotid artery occlusion (n = 5) was changed significantly from 0.82 +/- 0.06 to 0.90 +/- 0.06 and that of normal (n = 5) was not changed from 0.94 +/- 0.03 to 0.95 +/- 0.01. Raise up 99mTc-HMPAO brain SPECT enhanced the detectability in abnormality of regional cerebral blood flow and visualized the dys-autoregulated area during blood pressure falls.

Blood Pressure↗

PubMed1992

Dimethyl sulfoxide (DMSO) blocks GABA-induced current in rat dorsal root ganglion neurons.

The effects of dimethyl sulfoxide (DMSO) on gamma-aminobutyric acid (GABA)-induced Cl- currents of rat dorsal root ganglion neurons in primary culture were studied by the whole-cell patch-clamp technique. Bath application of 5 microM GABA evoked sustained inward and outward currents at membrane potentials of -60 mV and +30 mV, respectively, when the external and internal solutions both contained 142 mM Cl-. DMSO at concentrations of 0.3-3% (v/v) caused a dose-dependent inhibition of the inward current induced by 5 microM GABA at -60 mV. DMSO at 3% inhibited the GABA-induced inward and outward currents at -60 mV and +30 mV to similar extents (54% and 53% of the control, respectively), but the time-course of inhibition of the outward current at +30 mV was much faster than that of the inward current at -60 mV. These results suggest that DMSO suppressed the currents by interacting with GABA receptor-Cl- channel complex protein rather than by affecting the lipid-bilayer of the cell membrane.

Animals↗

PubMed1992

Human c-erbB-2 proto-oncogene product as a target for bispecific-antibody-directed adoptive tumor immunotherapy.

To develop an efficient strategy for the targeting of anti-tumor effector cells, we prepared bispecific antibody (BsAb) containing anti-CD3 and an anti-c-erbB-2 proto-oncogene product. The prepared BsAb specifically reacts with both c-erbB-2-positive tumor cells and CD3+ CTL. Human CD4+ helper/killer T cells, induced from peripheral-blood mononuclear cells by activation with immobilized anti-CD3 monoclonal antibody (MAb) plus IL-2, showed no significant cytotoxicity against tumor cells. However, treatment of human CD4+ helper/killer cells with the BsAb caused the induction of specific cytotoxicity against c-erbB-2-positive tumor cells. CD4+ helper/killer cells also produced significant amounts of IL-2 during co-culture with c-erbB-2-positive tumor cells in the presence of the BsAb. Moreover, by combination with the BsAb, CD4+ helper/killer cells showed a strong in vivo anti-tumor effect against c-erbB-2 transfectant or human colon-cancer cells implanted in nude mice. Our results strongly suggest that the c-erbB-2 proto-oncogene product on human tumor cells may be a good target for BsAb-directed adoptive tumor immunotherapy.

Antibodies, Monoclonal↗

PubMed1992

Amyloid beta-protein precursor deposition in rat hippocampus lesioned by ibotenic acid injection.

Ibotenic acid was injected into 3 parts of the lateral rat hippocampus. The animals were sacrificed 100 days after treatment, and studied immunohistochemically. The lesioned side of the hippocampus was highly atrophic with extensive neuronal loss and gliosis. Although silver staining revealed no particular structures such as neurofibrillary tangles or senile plaques, globular and granular depositions of amyloid beta-protein precursor (APP) immunoreactivity was observed by immunostaining in the lesion with the monoclonal antibody (clone 22C11). Increased immunoreactivities of glial fibrillary acidic protein (GFAP) and ubiquitin were found in the lesioned area, while the immunoreactivities of microtubule-associated protein 2 (MAP2) and 200 kDa neurofilament subunit protein (NF-H) were diminished. The results indicate that APP deposition is formed in the lesioned area where neuronal degeneration is produced by ibotenic acid in rat hippocampus.

Amyloid beta-Protein Precursor↗

PubMed1992

Generation propagation, and targeting of human CD4+ helper/killer T cells induced by anti-CD3 monoclonal antibody plus recombinant IL-2. An efficient strategy for adoptive tumor immunotherapy.

We developed a culture system for the rapid generation of CD4+ T cells that have both helper and killer functions. CD4+ T cells isolated from human PBL did not proliferate or develop significant cytotoxicity when treated with rIL-2 because of the lack of p75 IL-2R expression. However, culture of isolated CD4+ T cells with immobilized anti-CD3 mAb plus rIL-2 resulted in a marked proliferation (500-fold increase in 14 days) of CD4+ T cells. The proliferating CD4+ T cells produced IL-2 (92 U/ml) and showed strong cytotoxicity against OKT3 hybridoma cells and Daudi, K562, and U937 tumor cells in an anti-CD3 mAb-dependent manner. The CD4+ T cells contained significant amounts of cytolytic granule-related proteins such as serine esterase and perforin. Activated CD4+ helper/killer cells can be generated from both healthy donors and tumor patients and can be propagated in vitro for 14 to 35 days by biweekly restimulation with immobilized anti-CD3 mAb plus rIL-2. This culture yielded about 20,000-fold increase in cell number after a 21-day culture. Bispecific antibody containing anti-CD3 and anti-glioma Fab components enhanced the cytotoxicity of activated CD4+ helper/killer cells against IMR32 glioma cells. Moreover, the activated CD4+ helper/killer cells showed both helper and antitumor activity in vivo and prevented growth of anti-CD3 hybridoma cells in nude mice whether or not IL-2 was administered. These results indicate that anti-CD3 mAb plus IL-2-activated CD4+ helper/killer cells may provide an effective strategy for adoptive tumor immunotherapy of cancer.

Antibodies, Monoclonal↗

PubMed1992

Mouse rRNA gene transcription factor mUBF requires both HMG-box1 and an acidic tail for nucleolar accumulation: molecular analysis of the nucleolar targeting mechanism.

RNA polymerase I requires at least two nucleolar transcription factors, UBF and SL-1, for ribosomal RNA gene (rDNA) transcription. UBF requires SL-1 for the formation of a stable initiation complex on the rDNA promoter region. We have determined the region of mouse UBF (mUBF) required for nucleolar targeting. Although mUBF has a nuclear localization sequence, this sequence alone is not sufficient for mUBF to accumulate in the nucleolus. Deletion analyses show that mUBF requires a wide region except for the N-terminal 101 amino acids for nucleolar targeting. Deletion of either the HMG-box1, a region crucial for rDNA binding, or the acidic tail, a region that may interact with SL-1, results in the loss of nucleolar targeting. We show by DNA affinity analysis that the HMG-box1 is absolutely necessary for mUBF to bind to the upstream control element of the rDNA. We also show that mUBFs with various internal deletions retain both nucleolar targeting and DNA binding ability. A clear correlation was demonstrated between the DNA binding and nucleolar targeting ability. These results suggest that UBF is transferred to the nucleus by its NLS and is sequestered in the nucleolus by its specific and stable binding to the rDNA promoter via HMG-boxes and the acidic tail.

Animals↗

PubMed1992

Visualization of posture-dependent cerebral blood flow in a patient with Takayasu's disease by means of 99mTc-HMPAO brain single photon emission tomography.

A case of Takayasu's disease in a 22-year-old woman who complained of severe fainting attacks is presented. Bilateral obstruction of the cervical arteries was confirmed by digital subtraction angiography. Preoperative technetium-99m hexamethylpropylene amine oxime brain SPET in the sitting position showed bilateral hypoactivity in the temporoparietal areas. Subtraction brain SPET showed slightly increased activity in the lying position. The patient has had no fainting attacks since bypass surgery. Postoperative 99mTc-HMPAO brain SPET in the sitting position showed normal activity except in the right temporoparietal area. This area was filled in the lying position. 99mTc-HMPAO brain SPET is the only technique that can visualize the cerebral blood flow in any position, this capability deriving on the fact that the distribution of 99mTc-HMPAO in the brain is fixed in the first 2-3 min following injection. The use of both sitting and lying 99mTc-HMPAO brain SPET is very useful for detecting an abnormality (i.e. an inhomogeneous response due to the fall in perfusion pressure) that could not be seen if the cerebral blood flow were to be assessed only in the lying position.

Adult↗

PubMed1992

Serial assessment of denervated but viable myocardium following acute myocardial infarction in dogs using iodine-123 metaiodobenzylguanidine and thallium-201 chloride myocardial single photon emission tomography.

Iodine-123 metaiodobenzylguanidine (mIBG) is taken up by sympathetic nerve endings, allowing scintigraphic imaging of myocardial sympathetic innervation. We investigated the denervated but viable canine myocardium after acute myocardial infarction by serial mIBG and thallium-201 chloride (201TlCl) single photon emission tomography (SPET). In 12 dogs, acute myocardial infarction was produced by ligation of the left circumflex coronary artery. Images of mIBG and thallium SPET were obtained 6 h, 1, 4 and 6 weeks later. The defect size was calculated in percentage points from short axial views, and the 123I-mIBG/201TlCl ratio was determined. The uptake ratio was high at 1 week but gradually decreased. Three dogs were killed at each time point, and tissue samples were obtained from infarcted (both 201TlCl and 123I-mIBG defects), peri-infarcted (123I-mIBG defect and 201TlCl normal) and normal myocardium (both mIBG and 201TlCl normal). The changes in tissue content of noradrenaline in these lesions were measured. Noradrenaline tissue content gradually recovered in the peri-infarcted area. However, no recovery was noted in the infarcted area at 6 weeks. We conclude that sympathetic denervation and re-innervation occur following acute myocardial infarction, and the denervated but viable myocardium could be detected non-invasively by combined mIBG and thallium SPET.

3-Iodobenzylguanidine↗

PubMed1992

Cumulative white matter changes in the gerbil brain under chronic cerebral hypoperfusion.

An animal model of chronic brain hypoperfusion has been developed by applying coiled clips to the bilateral carotid artery of Mongolian gerbils. The brain tissue damage was neuropathologically studied after 1, 4, 8, and 12 weeks of hypoperfusion. The hippocampus, basal ganglia, and cerebral cortex of the chronically hypoperfused gerbil showed lesions with various severity which are probably due to ischemic episodes. In the cerebral white matter, however, two types of lesions were observed; one similar to those in the gray matter, and the other observed only in the white matter after more than an 8-week duration of brain hypoperfusion. The lesion specific to the white matter showed rarefaction and gliosis without locally associated ischemic changes. This type of the white matter lesion was never found in the gerbil brain before 8 weeks and, significantly, increased in number and size by 12 weeks post operation. The accumulation of the white matter lesions is characteristic in the gerbil with chronic hypoperfusion. The observed white matter-specific lesion resembles the histological changes in aged brain with cerebrovascular diseases.

Animals↗

PubMed1992

Sequential change of hemodynamic reserve in patients with major cerebral artery occlusion or severe stenosis.

To identify regional vasodilatory capacity and its sequential change, we evaluated prospectively a total of 78 acetazolamide tests in 51 patients with occlusion or greater than 75% stenosis of the carotid or middle cerebral arteries. The relative distribution of cerebral blood flow was determined by single photon emission computed tomography using N-isopropyl-p-[123I]-iodoamphetamine before and after intravenous injection of acetazolamide. Reduced vasodilatory capacity was demonstrated in 20 patients (38%), including 5 patients with hemodynamic transient ischemic attacks or infarction. Follow-up acetazolamide tests revealed asymptomatic progression of the arterial lesion (from stenosis to occlusion) in 1 patient and almost complete improvement of vasodilatory capacity in 5 patients, including 3 without surgical intervention. During an average follow-up period of 18.5 months, 4 patients died from cardiac causes or neoplasm; no neurovascular events occurred. Much larger numbers of patients with longer observation periods will be necessary to clarify the contribution of chronic hemodynamic failure to subsequent stroke. However, the present data indicate that the acetazolamide test is useful for assessing the course of high grade stenosis or occlusion of major cerebral arteries.

Acetazolamide↗

PubMed1992

Coronary arterial involvement in aortitis syndrome: assessment by exercise thallium scintigraphy.

It is important in patient management to evaluate coronary arterial involvement in aortitis syndrome. Twenty-one cases of aortitis syndrome who experienced chest pain were examined using exercise thallium scintigraphy. The patients were divided into 4 groups according to the angiographic findings. There were five patients with left main coronary arterial involvement (group A), four with left or right coronary arterial involvement (group B), nine with aortic regurgitation (group C), and three with pulmonary arterial involvement (group D). In groups A and B, all patients had positive ECGs and thallium perfusion defects. Group A patients showed extensive anterolateral perfusion defects, which were compatible with left main coronary arterial involvement. Groups C and D patients, who had normal coronary arteries, showed no remarkable perfusion defects although five had positive ECG findings. Thus, the sensitivity and specificity of exercise scintigraphy for detection of myocardial ischemia were 9/9 and 12/12, while those of stress ECG were 9/9 and 7/12 (58%), respectively. it is recommended that exercise thallium scintigraphy be used for detecting clinically occult but significant coronary arterial involvement in aortitis syndrome with chest pain.

Adult↗

PubMed1992

Favorable biodistribution of 99mTc-ECD for brain SPECT comparing with 123I-IMP using alternative body scan.

In order to evaluate the lung and brain uptake of 99mTc ethyl cysteinate dimer (99mTc-ECD) and N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP), alternative body scans were carried out in 15 cases of cerebrovascular disease. The biodistribution of 99mTc-ECD was 5.5 +/- 0.7%, 3.8 +/- 0.7% in the brain; 13.1 +/- 3.7%, 2.2 +/- 1.2%, in the lung at 15 min and at 4 hours, respectively, whereas that of 123I-IMP was 3.9 +/- 1.4%, 5.0 +/- 1.0% in the brain; 32.2 +/- 7.6%, 12.7 +/- 3.3%, in the lung at 15 min and at 4 hours, respectively. 99mTc-ECD accumulated in comparatively high amounts in the brain but remained low in the lung in the early image compared to 123I-IMP. However there was a high inverse correlation between brain and lung uptake of 123I-IMP (r = -0.82), but not of 99mTc-ECD (r = -0.18). We concluded that 99mTc-ECD had a better biodistribution in terms of low lung accumulation than 123I-IMP in brain SPECT.

Aged↗

PubMed1992

Ischemic injury in cirrhotic livers: an experimental study of the temporary arrest of hepatic circulation.

In order to prevent massive bleeding at hepatectomy, the temporary arrest of hepatic circulation is often performed but it is not clear whether this arrest of circulation is tolerated equally by the cirrhotic liver and the normal liver. We investigated biochemically the detailed effects of ischemia on cirrhotic livers in rats with experimentally induced liver cirrhosis. Thioacetoamide was used to prepare the rat cirrhotic liver model (LC group, n = 6). After laparotomy, the vessels to the left lateral lobe were clamped for 30 min and then declamped. Changes in AST isozymes and the aminogram in the blood were examined after ischemia. Postischemic changes in hepatic adenine nucleotides (AdN) and the brain aminogram were also examined. These were compared with those of normal liver ischemia (N group, n = 6) at 24 hr after recirculation. In the LC group, serum levels of mitochondrial AST, a parameter of necrotic cells, were significantly higher than those of the N group. Hepatic AdN levels decreased to 60.6% of the original levels after ischemic injury but those of the N group remained at 95.4% of the original level. Since AdN in tissue is accepted as a reliable parameter of viable cells, cirrhotic livers subjected to ischemia might have more necrotic cells than normal livers. Sequential analysis of serum aminograms of the LC group after ischemia revealed that the ratio of Val+Leu+Ileu/Tyr+Phe decreased to near 1.0 but that of the N group always remained higher than 3.0. Based on these results, it was concluded that ischemic injury in cirrhotic livers is more hazardous than that in normal livers.

Adenosine Triphosphate↗

PubMed1992

Natural cytotoxic T cells responsible for anti-CD3-induced cytotoxicity in mice.

T cells obtained from normal mouse spleen cells showed significant cytotoxic activity against Fc receptor positive tumor cells in the presence of anti-CD3 monoclonal antibody (mAb). This activity was designated as natural cytotoxic T cell (NCT) activity and compared with natural killer (NK) activity. Considerable levels of NCT activity were detected in mouse strains with both high and low NK activity. NCT cells were distributed in both lower and higher density fractions of Percoll discontinuous density gradients, while NK cells were enriched in the lower density fraction of Percoll gradients. Moreover, NCT activity was resistant to in vivo anti-asialo GM1 treatment, in contrast to NK cells. These results indicate that NCT cells, which have different characteristics from NK cells, are present in normal, nonimmunized mouse spleen cells. Unexpectedly, CD4+ T cells sorted from normal mouse spleen T cells revealed significant NCT activity, as did CD8+ T cells. It was also demonstrated that NCT cells require the LFA-1 molecule to lyse tumor cells in the presence of anti-CD3 mAb.

Animals↗