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Biomedical subjects

M Ishiguro

Publications and source records attributed to M Ishiguro.

At least 109 records · Page 6Linked to original sources
PubMed1995

Purification and characterization of high molecular weight hCG from human first trimester placenta.

Human chorionic gonadotropin (hCG) in first trimester placental cells is composed of immature alpha- and beta-subunits containing only N-linked high-mannose sugar chains. Intracellular immature intermediates are accumulated in rough endoplasmic reticulum in much greater quantity than mature hCG composed of mature subunits. We have previously shown that this immature hCG might be bound to other protein(s), including an ATP-binding protein, forming high molecular weight-hCG (HMW-hCG), which is not aggregate of immature hCG alone. To identify the ATP-binding protein forming the HMW-hCG in detail, proteins in HMW-hCG preparation were photoaffinity-labeled with 8-azido-[alpha-32P]ATP. Autoradiography followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the labeled protein with M(r) = 78000 was immunoprecipitated with any antibody against alpha-subunit, beta-subunit and hCG, indicating that this protein is bound to immature hCG. Furthermore, to determine whether some other proteins associate to form HMW-hCG, we purified HMW-hCG without breakdown to its components using columns of DE52, Heparin-Sepharose and Sephacryl S-300. As the final step of the purification, HMW-hCG was allowed to adsorb on a column of ATP-agarose and anti-hCG IgG-agarose, respectively. SDS-PAGE analysis of eluted proteins from the columns bound to the respective column via the constituent of HMW-hCG, such as ATP-binding protein or immature hCG, showed four common protein bands with molecular weights of 78000, 43000, 28000 and 20000. The protein with M(r) = 43000 was stained with any antibody against alpha-subunit, beta-subunit and hCG, indicating it to be immature hCG. The protein band with M(r) = 78000, which might correspond to the ATP-binding protein described above, was stained with anti-heat shock protein 70 (HSP70) monoclonal antibody. To confirm the association of immature hCG and HSP70-like protein, immature hCG preparation was incubated with HSP70-like protein purified from placental extracts. The molecular weight change of immature hCG appeared to increase by this incubation and was close to HMW-hCG, but not exactly the same. These results suggest that immature hCG intermediate exists as HMW-hCG containing HSP70-like protein, which has ATP-binding capacity, and two other proteins in first trimester placental cells.

Chorionic Gonadotropin↗
PubMed1995

The binding of ricin to its receptor is not required for the expression of its toxicity.

Ricin toxin is a toxic glycoprotein comprising two polypeptide chains, A and B, joined by a disulfide bond. The binding of its B-chain to the cell surface glycoconjugate having non-reducing terminal galactose (ricin receptors) has been assumed to allow the internalization of ricin into the cell, followed by the release of the free A-chain into cytosol, which then inhibits cellular protein synthesis in eukaryotic cells (cytotoxic effect). In order to investigate whether the binding of ricin to its receptors is essential to the expression of its toxicity, ricin was allowed to be incorporated into the cells using liposome encapsulated ricin (ricin-encapsulated liposomes). Protein synthesis in cultured Hela cells was inhibited by incubation not only with intact ricin but also with ricin-encapsulated liposomes, indicating that the binding of ricin to its receptor is not required for the expression of its toxicity.

Dose-Response Relationship, Drug↗
PubMed1995

The occurrence of nicked human chorionic gonadotropin (hCG) by a thermolytic endoprotease.

A nicked form of human chorionic gonadotropin (nicked hCG), in which only one peptide bond between residues 47 and 48 (-Gly-Val-) of beta-subunit is cleaved, has been found in the urine and blood of pregnant women. In this study, we investigated the occurrence of nicked hCG and the localization of the nicking enzyme for hCG. First, to determine what type of protease nicks hCG, an in vitro proteolytic study using various proteases was performed. Amino-terminal amino acid sequence analysis of the beta-subunit purified from protease-treated hCG indicated that thermolysin actively nicks hCG. Secondly, to determine which tissues are related to the formation of nicked hCG, the distribution of radioactivity in various tissues after i.v. administration of radiolabeled hCG to female rats was examined. The radioactivity accumulated predominantly in the kidney (17%), liver (9.3%) and ovary (0.9%) after 30 min of injection. Analysis of molecular species of beta-radiolabeled hCG in various tissues and body fluids, using sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by autoradiography, indicated that a nicked hCG-like molecule was found in the kidney, predominantly, as well as in the serum and urine. To examine the role of the kidney in producing nicked hCG, hCG was incubated with rat kidney particulate fraction (KPF). Immunoblot analysis of KPF-treated hCG indicated that KPF produced a nicked hCG-like molecule. Furthermore, the possibility that placental trophoblast cells produce nicked hCG was also examined using the choriocarcinoma cell BeWo.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

[De novo aneurysm associated with a persistent primitive trigeminal artery: case report].

This paper presents a case of a de novo unruptured anterior communicating aneurysm associated with a persistent primitive trigeminal artery. The patient was a 65-year-old female with tinitis, for whom computed tomography with contrast medium indicated right dural enhancement. Dural arteriovernous malformation was suspected and angiography was thus conducted. A right persistent primitive trigeminal artery was demonstrated but no aneurysm could be found. Six years later, magnetic resonance angiography indicated an aneurysm on the anterior communicating artery. It was subsequently removed by surgery. A persistent primitive artery is frequently found to accompany aneurysm but de novo aneurysm associated with such an artery does not appear in the literature to date. The authors emphasize the importance of follow-up angiography in cases of persistent primitive artery not accompanied by an aneurysm.

Aged↗
PubMed1995

[Percutaneous transluminal angioplasty for cervical carotid artery stenosis].

Percutaneous transluminal angioplasty (PTA) was attempted in 16 patients (17 procedures) with cervical internal carotid artery (ICA) stenosis. Among the 16 patients, 14 were male and 2 were female aged from 44 to 76 years (average 63.4 years). One had cerebral infarction on the acute stage, and the other 15 were in the chronic stage. On CT scan and MRI, there were nine multiple lacunar infarctions and seven watershed infarctions. On angiographical findings, 13 had Rt.-ICA stenosis and 4 had Lt. ICA stenosis. Stenotic lesion existed beyond the level of the third cervical vertebral body in eleven cases, and so-called long segmental stenosis ranged from 3 to 5 cervical vertebral bodies in 3 cases. Before PTA, 14 patients underwent a balloon occlusion test for 3 to 20 minutes (average 9 minutes). Neurological symptoms of hemiparesis or sensory disturbance occurred in 3 patients during balloon inflation, but these disappeared completely after balloon deflation. It took from 1.5 to 2 hours (average 1.7 hours) to carry out PTA including the balloon occlusion test. All cases had satisfactory results with no morbidity or mortality. The mean stenosis ratio of pre-PTA, approximately 80% (55-93%), improved to that of 22% (0-50%) after PTA. Bradycardia and hypotension occurred transiently in 9 cases during and after PTA, but no symptoms remained by atropine sulfate and catecholamine infusion intravenously. In the following 1 to 26 months (mean 9.0 months) after PTA, 3 cases restenosed. The restenosis was recognized by MR angiography after 8 to 26 months (average 15.7 months) of PTA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Synthesis of a glycopeptide with phytoalexin elicitor activity. I. Synthesis of a triglycosyl L-serine and a triglycosyl L-seryl-L-proline dipeptide.

A stereocontrolled synthesis of the model compound for the phytoalexin elicitor-active glycoprotein is described. Glycosylation of the disaccharide, 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl-(1-->6)-2,3,4-tri-O-acetyl- alpha- D-mannopyranosyl trichloroacetimidate, with N-(carbobenzoxy)-(2,3,4-tri-O-acetyl-alpha-D-mannopyranosyl)-(1-->3)-L- serine methyl ester or N-(carbobenzoxy)-(2,3,4-tri-O-acetyl-alpha-D-mannopyranosyl)-(1-->3)-L- seryl-L- proline methyl ester by use of AgOTf gave the desired trisaccharide-serine or trisaccharide-seryl-proline derivatives, which were transformed into beta-D-glucopyranosyl-(1-->6)-alpha-D-mannopyranosyl-(1-->6)-alpha-D- mannopyranosyl-(1-->3)-L-serine and triglycosyl-(1-->3)-L-seryl-L-proline via removal of the N-carbobenzoxy group, followed by deacylation.

Carbohydrate Conformation↗
PubMed1994

Better grading systems for evaluating the degree of lymph node invasion in cancer of the thoracic esophagus.

To evaluate the quality of various grading systems for lymph node invasion in cancer of the thoracic esophagus, the surgical results of 142 patients who underwent systematic lymph node dissection with curative intent were analyzed. The survival probability of patients in the same grade was modeled using a Weibull distribution and the parameters were estimated by the maximum likelihood principle. The quality of each grading system was measured by the Akaike Information Criterion (AIC) of the estimated statistical model, by which the smaller the AIC of a grading system, the smaller the loss of information for predicting outcomes. The AIC of the TNM grading of the International Union Against Cancer, the grading of the Japanese Society for Esophageal Diseases, and the grading designed according to the total number of positive lymph nodes became substantially smaller in that order. The AIC of grading systems variously designed on rather simple criteria were examined with the aim of creating a better grading system. It was concluded that a grading system based on the total number of positive nodes and the state of the paratracheal and/or middle mediastinal node groups was better than the other systems examined.

Esophageal Neoplasms↗
PubMed1994

The specific inhibition of crystal growth of monohydrogen potassium L-tartrate by d-catechin.

Crystal growth of monohydrogen potassium L-tartrate in an ethanolic aqueous solution was specifically inhibited by d-catechin, but not by either its epimeric isomer at C3, l-epicatechin or by gallic acid and caffeic acid. 3D-Structure similarity search of d-catechin with two molecules of the tartrate and docking study of d-catechin with the crystal model of the tartrate suggested that d-catechin mimics a structure consisting of the two tartrate molecules in the inhibition. Differences in the conformation of the catechol moieties of d-catechin and l-epicatechin may explain the distinct inhibitory effects of the epimeric isomers.

Catechin↗
PubMed1994

Antibody against a peptide corresponding to the extracellular domain of the luteinizing hormone/chorionic gonadotropin receptor stimulates testosterone production in rat Leydig cells.

In order to study the function of LH/CG receptor, we prepared four synthetic peptides (RP1, 2, 3, and 4 for residues 242-255, 49-66, 493-504, and 573-584) corresponding to extracellular domains of rat ovary LH/CG receptor and raised antibodies against RP1 and RP2 (anti-receptor peptide IgGs). These peptides and IgGs were assayed for inhibition of 125I-labeled hCG binding to Leydig cell membrane receptors. However, neither the peptides nor the IgGs inhibited hCG binding to the receptor at doses up to 10(-3) and 10(-5) M, respectively. On the other hand, although anti-receptor peptide IgGs did not show inhibition of hCG binding to the receptor, it was found that one of the IgGs (anti-RP1IgG) was bound to the cell membrane and stimulated testosterone production in rat Leydig cells. F(ab')2 fragment lacking the N-linked sugar chain in the IgG molecule, whose sugar chains are similar to those of hCG, was prepared from anti-RP1IgG. Anti-RP1F(ab')2 was still bound to the cell membrane but no longer stimulated testosterone production. These results suggested that when LH/CG receptor binds to a glycoprotein, even if it is different from the native ligand hCG, it may interact with sugar chains of the glycoprotein to cause signal transduction. Thus, a lectin-like domain in or near the receptor may play a key role in the receptor function.

Amino Acid Sequence↗
PubMed1994

Evaluation of calcium hydroxide-containing root canal sealers with an improved rabbit ear chamber.

An improved rabbit ear chamber was used to evaluate calcium hydroxide-containing root canal sealers on their potential to induce dystrophic calcification in connective tissue. Four sealers and two control materials were introduced into the chambers and the effects of these materials on the living vascular tissue were observed continuously under a biomicroscope up to 9 weeks. Conventional histopathological investigation and examinations with a scanning electron microscope and an X-ray microanalyzer were done to supplement the results. Sealapex and Calvital (Ca(OH)2 + iodoform) revealed almost the same tissue reaction as calcium hydroxide-saline paste; they rapidly made a precipitate-barrier of calcium phosphate in the connective tissue, inducing calcification. However, Dentalis KEZ (ZnO-Ca(OH)2 + eugenol) caused mild disorders of microcirculation without calcification, as well as Canals (ZnO + eugenol). New A (Ca(OH)2 + fatty acid) had good compatibility with microvessels as well as New B (ZnO + fatty acid), however they induced no calcification and disintegrated rapidly in the tissue. These sealers were reclassified according to what they actually bring about in the tissue, not according to what they include.

Animals↗
PubMed1994

The effect of recombinant human erythropoietin (r-HuEPO) on left ventricular mass and left ventricular hemodynamics in hemodialysis patients.

The purpose of this study was to examine the effect of recombinant human erythropoietin (r-HuEPO) on left ventricular mass. Twenty-seven hemodialysis patients (13 men and 14 women) were given r-HuEPO for renal anemia. Blood pressure and heart rate were measured before and after the 16-week course of r-HuEPO, and at the same time echocardiography was performed to measure left ventricular dimensions and wall thickness. These measurements were used to calculate left ventricular volume, cardiac output (CO), and left ventricular mass (LVmass). Diastolic blood pressure (DBP) increased after administration of r-HuEPO (from 75.8 +/- 10.8 mmHg to 85.6 +/- 12.7 mmHg), but there was no change in systolic blood pressure (SBP) or heart rate. LVmass increased significantly in seven cases (from 194.7 +/- 40.0 g to 240.3 +/- 47.3 g). These cases, Group I, showed no decline in stroke volume (SV) or CO, and showed significant increases in SBP. In the remaining 20 cases, Group II, LVmass decreased or was unchanged. In this group SV and CO decreased, but there was no increase in SBP. We conclude that increases in LVmass may be associated with elevated systolic blood pressure and hypertrophy of the left ventricular wall, when hemodialysis patients with severe renal anemia are given r-HuEPO.

Adult↗
PubMed1994

[A case of an intracerebral mass lesion consisting of traumatic granulation tissue].

We reported a rare case of an intracerebral granulomatous lesion accompanying severe edema formation in the healing stage of traumatic brain contusions. A 44-year-old male patient came to our outpatient clinic due to progressing headache and nausea. Upon computed tomographic examination, a low density mass with strong surrounding edema was detected at the right frontal base. Magnetic resonance images revealed a high intensity mass on both T1- and T2-weighted images at the right frontal base. Upon intravenous injection of a contrast agent, this lesion exhibited multifocal marginal contrast enhancement. Two additional small enhanced mass lesions were detected at the tip of the right temporal lobe and the medial portion of the left temporal lobe. We tentatively diagnosed it as a right frontal brain tumor and attempted the total removal of the right frontal mass. Unexpectedly, pathological diagnosis was intracerebral granulation tissue associated with accumulation of hemosiderin-laden macrophages and capillary wall thickening. In addition, there was no reactive gliosis. We speculated on the pathogenesis of intracerebral granulation tissue as follows. Since the patient was a heavy drinker and often fell down when he was drunk, it is likely that he might be suffering from intracerebral hematomas due to traumatic contusions. This assumption may be supported by the fact that an old subdural hematoma was observed during the operation and the radiological examination revealed multiple lesions. The gathering and proliferation of mesenchymal cells possibly derived from blood circulation probably began at the site of the damaged brain tissue, thus forming intracerebral granulation tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[The effects of various doses of lipopolysaccharide on endotoxin-induced uveitis in rats].

We induced intraocular inflammation by foot pad injection of lipopolysaccharide (LPS) in rats to investigate the inflammatory effects of the various doses of the LPS and the anti-inflammatory effects of prostaglandin (PG) synthetase inhibitor. The aqueous protein concentration curve showed two peaks, an early one at 3 hours and another at 24 hours after the injection, at doses higher than 12.5 micrograms per rat. The PG synthetase inhibitor reduced the aqueous protein concentration by 30 to 60% at both of the two peaks. These results suggest the involvement of PG in the mechanism of the endotoxin-induced uveitis.

Animals↗
PubMed1994

[The relation between Behçet's disease and interleukin-1 beta production].

Interleukin-1 beta (IL-1 beta) is an inflammatory cytokine. We measured its production in 21 Behçet's disease patients, 4 healthy controls, and 4 sarcoidosis patients, by enzyme-linked immunosorbent assay (ELISA) after stimulation with lipopolysaccharide from peripheral blood monocytes. IL-1 beta production of the posterior segment type was significantly greater (p < 0.001) than in healthy controls, sarcoidosis patients, and anterior segment type. In all posterior segment type cases, IL-1 beta production in the active period was greater than in the remission period. IL-1 beta production is considered to be related to posterior segment type attacks of Behçet's disease.

Adolescent↗
PubMed1994

[A case of suprasellar intradural chordoma].

An extraosseous and intradural chordoma of the suprasellar region is described in a 54-year-old male who presented himself with left homonymous hemianopia. Computed tomography showed an isodensity tumor containing a cyst in the suprasellar region. Magnetic resonance images demonstrated the tumor as an isointense mass with heterogeneous enhancement after intravenous administration of a contrast agent, and as a high signal intensity mass on T2-weighted images. The associated cyst was also clearly demonstrated. The tumor was diagnosed preoperatively as a craniopharyngioma and was resected using the frontobasal interhemispheric approach. However, the resected tumor had the typical histological and immunohistochemical characteristics of chordoma. Only ten cases of totally extraosseous and intradural chordoma have been reported. The histogenetic background of this tumor is also discussed in this paper.

Brain Neoplasms↗
PubMed1993

A survey of a functional amino acid of class C beta-lactamase corresponding to Glu166 of class A beta-lactamases.

The class C beta-lactamase of Citrobacter freundii GN346 is a typical cephalosporinase comprising 361 amino acids. The aspartic acid at position 217 and glutamic acid at position 219 in this beta-lactamase were, respectively, previously shown not to be the counterpart of Glu166 (ABL166) in class A beta-lactamases, even though sequence alignment of class A and C enzymes strongly suggested this possibility [(1990) FEBS Lett. 264, 211-214; (1990) J. Bacteriol. 172, 4348-4351]. We tried again to assign candidates for the counterpart of Glu166 through sequence alignment based on other criteria, the glutamic acids at positions 195 and 205 in the class C beta-lactamase being selected. To investigate this possibility, these two glutamic acids were changed to glutamine, lysine or alanine, respectively. All the mutant enzymes showed more than 50% of the activity of the wild-type enzyme, indicating that the possibility was ruled out. These results strongly suggested the possibility that the class C beta-lactamase lacks a functional acidic residue corresponding to Glu166 in class A enzymes.

Alanine↗