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Biomedical subjects

M Ishida

Publications and source records attributed to M Ishida.

At least 163 records · Page 9Linked to original sources
PubMed1997

Evidence that expression of a mutated p53 gene attenuates apoptotic cell death in human gastric intestinal-type carcinomas in vivo.

To examine in vivo the validity of the results of experiments in vitro, we analyzed the relationship between p53 gene status and apoptotic cell death of human gastric intestinal-type adenocarcinomas. Surgical specimens were classified into two categories: 18 gastric cancers with nuclear p53 protein (A), and 17 gastric cancers without nuclear p53 protein (B). Polymerase chain reaction-single strand conformation polymorphism disclosed a shifted band that corresponded to a mutation in the p53 gene in 13 cases (72%) in category A and 3 cases (18%) in category B, the frequency being significantly higher in the former (P < 0.05). Apoptotic cells were identified from routinely stained sections and by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The TUNEL index [TI; (the number of TUNEL-positive apoptotic cells/the total number of tumor cells) x 100] was 3.8 +/- 1.4% in category A and 4.9 +/- 1.2% in category B, the value being significantly lower in the former (P < 0.05). The proliferating cell nuclear antigen index, defined similarly to the TI, was 56.4 +/- 16.3% in category A, and it was significantly higher than that in category B (P < 0.05). The immunohistochemically detected expression of p21CIP1/WAP1 did not differ between the two categories, while Bax-positive tumor cells were more frequently detected in category A. These results indicate that (1) expression of a mutated p53 gene attenuates apoptotic cell death of gastric cancer, in accordance with the previous in vitro finding that p53 gene mutation provides a possible selective advantage for tumor cell proliferation, and (2) apoptosis is related not only to expression of p53 and the stage of the cell cycle, but also to p53-independent and cell cycle-independent events.

Adenocarcinoma↗
PubMed1997

Angiotensin II stimulates tyrosine phosphorylation of phospholipase C-gamma-associated proteins. Characterization of a c-Src-dependent 97-kD protein in vascular smooth muscle cells.

Stimulation of phospholipase C-gamma (PLC-gamma) is a critical event in angiotensin II (Ang II) signal transduction. We have previously shown that in rat aortic smooth muscle (RASM) cells Ang II stimulates tyrosine phosphorylation of PLC-gamma via activation of c-Src. Because we failed to demonstrate a direct association between c-Src and PLC-gamma, we hypothesized that a linker protein mediates the interaction between these molecules. To identify PLC-gamma-associated proteins, RASM cells were labeled with [32P]orthophosphate and stimulated with 100 nmol/L Ang II for 5 minutes. PLC-gamma was immunoprecipitated, and associated proteins were characterized by autoradiography and Western blotting with anti-phosphotyrosine antibodies. Ang II stimulated the phosphorylation of 47-, 60-, 84-, and 97-kD PLC-gamma-associated proteins. Because Ang II increased tyrosine phosphorylation of only the 97-kD protein, we characterized p97 further. An important role for Src in tyrosine phosphorylation of p97 was suggested by findings that p97 phosphorylation was inhibited by the selective Src-family kinase inhibitor CP-118,556, diminished in mouse aortic smooth muscle (MASM) cells from c-Src knockout mice compared with wild-type MASM cells, and increased in v-Src-transformed NIH-3T3 cells compared with wild-type NIH-3T3 cells. These studies are the first to define a PLC-gamma-associated protein that may be required for Ang II-mediated signal transduction.

Angiotensin II↗
PubMed1997

How does the contractile vacuole of Paramecium multimicronucleatum expel fluid? Modelling the expulsion mechanism

To examine the forces needed for discharge of the fluid contents from the contractile vacuole of Paramecium multimicronucleatum, the time course of the decrease in vacuole diameter during systole (the fluid-discharging period) was compared with that of various vacuole discharge models. The observed time course did not fit that predicted by a model in which contraction of an actin&shy;myosin network surrounding the vacuole caused discharge nor that predicted by a model in which the surface tension of the lipid bilayer of the vacuole caused discharge. Rather, it fitted that predicted by a model in which the cell's cytosolic pressure was responsible for discharge. Cytochalasin B, an effective inhibitor of actin polymerization, had no effect on the in vivo time course of systole. An injection of a monoclonal antibody raised against the proton pumps of the decorated spongiomes (now known to be the locus of fluid segregation in P. multimicronucleatum) disrupted the decorated spongiomes and reduced the rate of fluid segregation, whereas it did not alter the time course of systole. We conclude that in P. multimicronucleatum the internal pressure of the contractile vacuole is caused predominantly by the cytosolic pressure and that the fluid-segregation mechanism does not directly affect the fluid-discharge mechanism. Elimination of this cytosolic pressure by rupturing the cell revealed the presence of a novel fluid-discharge mechanism, apparently centered in the vacuole membrane. The involvement of tubulation of the vacuole membrane as the force-generating mechanism for fluid discharge in disrupted cells is discussed.

Journal Article↗
PubMed1997

Release behavior of poly(lactic acid-co-glycolic acid) implants containing phosphorothioate oligodeoxynucleotide.

The release behavior of phosphorothioate oligodeoxynucleotide, 5'-GCCGAGGTCCATGTCGTACGC-3' (ODN), from poly(lactic acid-co-glycolic acid) (PLGA) implant was studied. The pillar shape implant was fabricated by the heating mold method. About 20% of ODN were released initially, and the subsequent pseudo-zero-order release lasted for more than 20 d from a PLGA10000 implant loaded with 8.4% ODN in phosphate buffered saline, pH 7.4. The duration of ODN release did not depend on the molecular weights of PLGA, and pseudo-zero-order release may be achieved by changing the loaded amount of ODN in fabrication of the PLGA implant. Almost the same release profiles were obtained in the pH range of 7.2 to 7.6, which is known as the physiological pH of a vitreous body. Furthermore, the duration of intact ODN release in bovine vitreous was found. The implant in the present study may possibly be applicable to intravitreal implantation for the treatment of ocular disease.

Animals↗
PubMed1997

Protective effect of transfection with secretable superoxide dismutase (SOD) (a signal sequence-SOD fusion protein coding cDNA) expression vector on superoxide anion-induced cytotoxicity in vitro.

For ex vivo gene therapy, superoxide dismutase (SOD) must be secreted into the extracellular space and delivered to damaged cells. Recombinant DNA technique can be used to produce a secretory protein that is fused to a non-secretory protein and a signal peptide of another secretory protein gene. We constructed a secretable SOD eukaryotic expression vector which expresses human SOD cDNA by fusing it to the signal peptide DNA sequence of the human interleukin-2 (IL-2) gene. The ILSOD cDNA constructed by PCR-based gene expression was ligated into the multicloning site of the pRc/CMV plasmid (pRc/CMV-ILSOD). Rat lung epithelial like cells (L2 cells) were transfected with pRc/CMV-ILSOD by lipofection. The extracellular SOD activity of ILSOD-L2 cells (transfected cells with pRc/CMV-ILSOD) was 3 times as high as that of host cells. We used the xanthin (X)/xanthin oxidase (XO) system to produce superoxide anions at the extracellular space. We initially investigated the direct cytotoxicity of superoxide anions upon cells. Host and ILSOD-L2 cells were killed by using X/XO, although the sensitivity of the ILSOD-L2 cells to X/XO induced cytotoxicity was significantly decreased compared with that of host cells. The production of lipid peroxidated substances in the host in the presence of X/XO increased to about twice the control (absence of X/XO) level. However, that of ILSOD-L2 cells did not change in the presence of X/XO. Therefore, ILSOD-L2 cells were resistant to X/XO induced lipid peroxidation. These findings indicated that ILSOD gene transfection protected against direct oxidant stress by X/XO. We then investigated the effect of extracellular SOD secreted from ILSOD-L2 cells on extracellular superoxide anion induced cytotoxicity in normal cells. The conditioned media of host cells had no significant effect upon X/XO induced cytotoxicity. However, the conditioned media of ILSOD-L2 cells protected against X/XO induced cytotoxicity. Furthermore, the conditioned medium of ILSOD-L2 cells was more effective than that of host cells against the production of lipid peroxidated substances by normal cells under conditions of oxidative stress. These results indicated that non-secretable protein could be delivered to target cells by means of DNA engineering. This strategy could thus provide an ex vivo means of applying gene therapy using non-secretable proteins.

Animals↗
PubMed1997

Angiotensin II signal transduction in vascular smooth muscle cells: role of tyrosine kinases.

Originally known to be a vasoconstrictor and thought to play a critical role in hypertension, angiotensin II has recently emerged to be important in inflammation, atherosclerosis and congestive heart failure. The expanding role of angiotensin II implies that multiple signal transduction pathways are likely to be activated in a tissue-specific manner. Recent data show that angiotensin II stimulates not only cytoplasmic tyrosine kinases including c-Src, focal adhesion kinase (FAK), and Janus kinases (JAK2 and TYK2), but also may transactivate receptor tyrosine kinases such as Axl and PDGF by as yet undefined autocrine/paracrine mechanisms. Finally, tyrosine kinases, which mediate tyrosine phosphorylation of key signal mediators such as Shc, Raf, and phospholipase C-gamma following angiotensin II stimulation, remain to be defined. These tyrosine kinases, activated by angiotensin II, appear to be required for angiotensin II effects such as vasoconstriction, proto-oncogene expression, protein synthesis, and cell proliferation. Thus, it is important to understand angiotensin II-mediated signaling events, especially those related to tyrosine kinase activity, to develop new therapies for cardiovascular diseases.

Angiotensin II↗
PubMed1997

Pingueculae and pterygia in motorcycle policemen.

PURPOSE: Pinguecula and pterygium are speculated to be associated with corneal and conjunctival microtrauma from exposure to sunlight and/or dust. Occupational motorcycle driving is suspected to be associated with such exposure, so we investigated the prevalence of pingueculae and pterygia in motorcycle policemen. METHOD: Silt lamp finding obtained by periodic eye checkup for policemen (783 motorcycle policemen and 207 control indoor workers) together with questionnaire were used for analyses. All pingueculae and pterygia were diagnosed under the definite criteria. RESULTS: The overall prevalence of pingueculae was 590/1,566 eyes (37.7%) among motorcycle policemen against 127/414 eyes (30.6%) among the indoor workers (p < 0.01). Besides, with increasing age, the prevalence of pingueculae in the motorcycle policemen clearly exceeded those among the indoor controls. The prevalence of pterygia were very small to be analysed. CONCLUSION: Our results exhibited a significant relationship between occupational motorcycle driving and the prevalence of pingueculae. Thus it is strongly suggested that they should wear eye protection equipment (goggles, face shield and so on) to prevent from developing these lesions.

Adult↗
PubMed1997

Serum gamma-glutamyl transferase levels and blood pressure falls after alcohol moderation.

Drinkers showing higher serum gamma-glutamyl transferase (GGT) levels tend to have higher blood pressure (BP), independent of the volume of alcohol consumed. To further evaluate the link between alcohol consumption and elevated serum GGT and BP, we observed BP, serum biochemical parameters, plasma pressor hormones and intraplatelet free calcium (Plt. [Ca2+]i) in 40 moderate drinkers who were composed of four categories of 10 each with or without hypertension (> or = 140/90 mmHg) or high serum GGT level (> or = 50 U/L) during four-week alcohol moderation. BP and serum hepatic enzymes including GGT decreased more conspicuously in both normotensive and hypertensive drinkers with high serum GGT. Serum triglyceride was higher and potassium was lower in the drinkers with high serum GGT, and were normalized during alcohol moderation. Serum calcium, Plt. [Ca2+]i and plasma renin activity and cortisol showed some decreases during alcohol moderation, but were not different in the drinkers with different serum GGT and BP levels. No significant changes were observed in plasma catecholamines and aldosterone. These results suggest that BP elevations in moderate drinkers are closely related to hepatic, lipid and electrolyte metabolic alterations induced by alcohol rather than specific pressor agents.

Adult↗
PubMed1997

Comparison of iodine-123-iomazenil SPECT and technetium-99m-HMPAO-SPECT in Alzheimer's disease.

UNLABELLED: This study was designed to elucidate a central type of benzodiazepine (Bz) receptor distribution in patients with Alzheimer's disease using SPECT with [123I]iomazenil (IMZ). METHODS: Eight patients with probable Alzheimer's disease were studied. Benzodiazepine receptor imaging was performed 15 min (early) and 180 min (delayed) after intravenous administration of 167 MBq IMZ, sequentially, using hexamethylpropylene amine oxime (HMPAO) SPECT to evaluate regional cerebral perfusion. RESULTS: Early IMZ-SPECT depicted areas of reduced uptake in sites of decreased cerebral blood flow (CBF), but each area of decreased uptake was extended wider than the area of hypoperfusion. Delayed IMZ-SPECT images demonstrated a similar pattern of decreased area of CBF; the affected region in Bz receptor bindings, however, was clearer and broader compared with that in either HMPAO-SPECT or early IMZ-SPECT. In comparison with the uptakes for the normal cerebral hemisphere (ratio to the contralateral cerebellum) in patients with unilateral cerebral infarction as a control group (n = 4), the patients with Alzheimer's disease showed distinctive bilateral frontal or parietal defects (p < 0.05). CONCLUSION: Brain SPECT using IMZ may be more sensitive than CBF images in patients with Alzheimer's disease.

Alzheimer Disease↗
PubMed1997

Intra-individual differences between technetium-99m-HMPAO and technetium-99m-ECD in the normal medial temporal lobe.

UNLABELLED: Regional distributions of 99mTc-hexamethyl propyleneamine oxime (99mTc-HMPAO) and 99mTc-ethyl cysteinate dimer (99mTc-ECD) were compared in the normal brain. METHODS: Six paid, healthy volunteers (mean age 26 yr) had high-resolution neuroperfusion SPECT using both 99mTc-HMPAO and 99mTc-ECD on separate days. RESULTS: Regional distribution of the two tracers differed. Technetium-99m-HMPAO accumulated more in the thalamus, frontal lobe, temporal lobe and cerebellum than 99mTc-ECD, which accumulated more in the occipital and parietal lobes. There was a considerable difference in the accumulation of the two tracers in the medial temporal lobe. The percent accumulations of 99mTc-HMPAO and 99mTc-ECD in the medial temporal lobe compared with the mean global cerebral cortical accumulation were 93.9% +/- 2.4% and 83.1% +/- 4.1% (mean +/- s.d.), respectively. CONCLUSION: The results suggest that 99mTc-HMPAO and 99mTc-ECD require specific and separate criteria for diagnosing temporal lobe pathologies, such as dementia and temporal lobe epilepsy.

Adult↗
PubMed1997

[Novel autoantibodies that recognize native transfer RNAs in patients with systemic rheumatic diseases].

Autoantibodies directed against aminoacyl-tRNA synthetases are well described in adult polymyositis/dermatomyositis. However, the characteristics of antibodies against other tRNA and tRNA-associated proteins have not been well defined. In this study, we identified novel autoantibodies to total tRNAs in patients with systemic rheumatic diseases and characterized the structure that was recognized by anti-tRNA antibodies. We identified fifteen patients sera that immunoprecipitated the deproteinized cognate tRNA. Two of them were identified as having previously well-defined anti-PL-12 antibodies. Three of the remaining 13 patient sera immunoprecipitated naked tRNA of E. coli. To investigate the antibody binding site on tRNAs, we have used in vitro transcripts from cDNAs encoding wild type tRNAs of E. coli and their synthesized mutants. These sera revealed different reactivity to mutated tRNAs. Eleven of these 13 patients met disease specific criteria for: SLE (3 patients), Sjögren's syndrome (6), or SLE/Sjögren's syndrome overlap (2). In addition, fever, Raynaud's phenomenon, and non-erosive polyarthritis, were frequently found in these patients. In summary, we have identified novel antibodies to tRNAs which appear to be quite common, and distinct from previously described anti-aminoacyl-tRNA synthetase antibodies.

Adult↗
PubMed1997

Hemodynamic aspect of cerebral watershed infarction: assessment of perfusion reserve using iodine-123-iodoamphetamine SPECT.

UNLABELLED: The mechanism whereby watershed (WS) infarcts develop remains controversial, although a hemodynamic cause is usually assumed. The aim of this study was to investigate the relationship between the site of WS infarcts and the hemodynamic status of the cerebral circulation. METHODS: From among 96 consecutive patients with angiographically confirmed unilateral major cerebral artery obstruction (occlusion or > 70% stenosis), we investigated 29 patients with supratentorial WS infarcts on magnetic resonance imaging. The regional cerebral blood flow and perfusion reserve were quantified using the split-dose [123I]iodoamphetamine SPECT method, coupled with intravenous injection of 1 g of acetazolamide. Seven patients had a cortical WS infarct between the superficial branches of the anterior and middle cerebral arteries (MCAs) or between the middle and posterior cerebral arteries (Group C), and 22 had a deep WS infarct between the superficial branches and deep penetrating arteries of the MCA (Group D). Moreover, the patients in Group D were classified into two subgroups, i.e., Type A (n = 12), with lesions lying in the centrum semiovale above the level of the lateral ventricles, and Type B (n = 10), with lesions lying in the corona radiata adjacent to the lateral ventricles. RESULTS: Comparison of the Type of WS infarct with the clinical course of onset showed that sudden onset was more frequent in Group C than in Group D (p < 0.05). The perfusion reserve in the affected MCA territory in Group D (20.1% +/- 15.6%) was significantly lower than that in Group C (43.8% +/- 10.8%; p < 0.01) and that in 20 hemispheres (10 control subjects) without a major arterial lesion (54.7% +/- 16.4%; p < 0.01). Among the Group D patients, the patients with Type A infarcts showed a significantly lower perfusion reserve compared with those with Type B infarcts (p < 0.05). CONCLUSION: Patients with deep WS infarcts, especially Type A infarcts, showed severe hemodynamic impairment, whereas patients with cortical WS infarcts showed preserved perfusion reserve which appeared to be secondary to the embolism. The mechanism of development of WS infarcts is multifactorial, and distinguishing among these WS infarcts and from other types of infarct is important, because different pathogenic mechanisms require different therapeutic strategies.

Acetazolamide↗
PubMed1997

Helicobacter pylori infection in early gastric adenocarcinoma: relationship between histologic subtypes and ulcer-formation.

Early stage of gastric cancers were divided into two subtypes; differentiated and undifferentiated adenocarcinomas, histologically. We examined the involvement of Helicobacter pylori (Hp) infection in the development and progression of cancer, and presence or absence of peptic ulcer (UL+/UL-). From the results, these findings obtained as follows; 1) Hp positive rate of UL+ group was significantly higher than that of UL-group. 2) Neither of gross features nor depth of the tumor did not correlate with Hp positive rates. 3) Hp positive rate of undifferentiated type carcinoma was significantly higher than that of differentiated type, contrarily to our expectation. These findings suggested that Hp infection might relate with ulcer formation in the cancerous lesion. The hypothesis which is "gastritis-intestinal metaplasia-differentiated type carcinoma sequence" was not supported by present study. Hence, Hp infection was suggested as an important factor of the gastric cancer development and progression, not only in differentiated type but also in undifferentiated type.

Adenocarcinoma↗