Biomedical subjects

N Nishi

Publications and source records attributed to N Nishi.

At least 55 records · Page 3Linked to original sources

PubMed1998

A study of the collagen-binding domain of a 116-kDa Clostridium histolyticum collagenase.

The Clostridium histolyticum 116-kDa collagenase consists of four segments, S1, S2a, S2b, and S3. A 98-kDa gelatinase, which can degrade denatured but not native collagen, lacks the C-terminal fragment containing a part of S2b and S3. In this paper we have investigated the function of the C-terminal segments using recombinant proteins. Full-length collagenase degraded both native type I collagen and a synthetic substrate, Pz-peptide, while an 88-kDa protein containing only S1 and S2a (S1S2a) degraded only Pz-peptide. Unlike the full-length enzyme, S1S2a did not bind to insoluble type I collagen. To determine the molecular determinant of collagen binding activity, various C-terminal regions were fused to the C terminus of glutathione S-transferase. S3 as well as S2bS3 conferred collagen binding. However, a glutathione S-transferase fusion protein with a region shorter than S3 exhibited reduced collagen binding activity. S3 liberated from the fusion protein also showed collagen binding activity, but not S2aS2b or S2b. S1 had 100% of the Pz-peptidase activity but only 5% of the collagenolytic activity of the full-length collagenase. These results indicate that S1 and S3 are the catalytic and binding domains, respectively, and that S2a and S2b form an interdomain structure.

Catalysis↗

PubMed1998

Receptor-mediated and receptor-independent activation of G-proteins in rat brain membranes.

High-affinity GTPase activity intrinsic to G-proteins, which serves as an index of G-protein activation elicited through agonist-stimulated receptors as well as by receptor-independent direct G-protein activators like mastoparan, was measured in rat brain membranes. Receptor-mediated high-affinity GTPase activity was detectable preferentially for the Gi subfamily associated with adenylyl cyclase inhibition mediated by group II metabotropic glutamate, pirenzepine-insensitive muscarinic acetylcholine, GABA(B), adenosine A1, dopamine D2-like (striatum), and serotonin 5-HT1A (hippocampus) receptors. The pharmacological characteristics of such receptor-mediated high-affinity GTPase activities were presented. Mastoparan, a tetradecapeptide from wasp venom which has been shown to directly activate Gi and Go, inhibited low-affinity GTP hydrolyzing activity, probably due to its activating effect on nucleoside diphosphokinase (NDPK). When NDPK activity was inhibited completely by UDP, mastoparan stimulated high-affinity GTPase activity in a concentration-dependent manner. There are many compounds other than mastoparan with apparently diverse structural properties which have been shown to directly activate G-proteins. The relevance and possible participation of receptor-independent mode of G-protein activation for some neuropeptides were discussed.

Animals↗

PubMed1998

Dural arteriovenous malformation of the anterior cranial fossa occurring after bifrontal craniotomy.

A case of dural arteriovenous malformation of the anterior cranial fossa developing after bifrontal craniotomy is reported. The nidus was fed mainly by the left anterior ethmoidal artery. It was drained into the right sylvian vein and superior ophthalmic vein with patency of the superior sagittal sinus. A left frontal hemorrhage resulted from the nidus itself. This is the first reported case of an acquired dural arteriovenous malformation of the anterior cranial fossa verified by angiography. This rare lesion is discussed with regard to its etiology.

Cerebral Angiography↗

PubMed1998

Expression of a synthetic gene for initiation factor 4E-binding protein 1 in Escherichia coli and its interaction with eIF-4E and eIF-4E x m7GTP complex.

An artificial gene coding for the human initiation factor (eIF) 4E-binding protein 1 (4E-BP1) was chemically synthesized and cloned. Although the expression of the 4E-BP1 gene alone has not yet been accomplished, the gene was expressed in Escherichia coli [BL21(DE3)] as a fusion gene with the glutathione-S-transferase (GST) gene using a prokaryotic gene fusion vector (pGEX-4T-2), which contains a gene sequence coding the cleavage site for a specific protease, alpha-thrombin. The fusion gene product was purified to homogeneity by glutathione Sepharose-4B affinity column chromatography. It was shown by m7GTP- and glutathione-affinity chromatography that the binding ability of 4E-BP1 to eIF-4E is nearly the same as that to the eIF-4E x m7GTP complex, implying different binding sites of eIF-4E and its nonallosteric obligation for 4E-BP1 and mRNA cap structure. In contrast with the binding of eIF-4E to the mRNA cap structure, where some functional amino acids play an important role in the binding, the binding to 4E-BP1 was suggested to occur via multiple nonspecific interactions.

Amino Acid Sequence↗

PubMed1998

A meta-analytic review of the effect of exercise on smoking cessation.

OBJECTIVE: To assess the effect of group exercise programs on smoking cessation. DATA SOURCES: A MEDLINE search, a manual review of journal articles, and a search of previous reviews were used. STUDY SELECTION: Published studies which 1) employed an exercise program for an intervention group and, 2) reported numbers of smokers of both exercise and control groups at baseline and at 6 to 24 months later were selected. DATA EXTRACTION: Five randomized trials were selected. In three of these, smoking cessation was the main aim and exercise was employed for relapse prevention concurrently with or after a group smoking cessation program. The studies produced a moderate qualitative score of 7 to 9 out of a 13 total score of modified DerSimonian's quality checklist. DATA SYNTHESIS: The summary odds ratio of the three studies which primarily aimed at smoking cessation was 2.35 (95% C.I. 0.75-7.31). When the two other studies were added, it dropped to 1.85 (95% C.I. 0.65-5.24). CONCLUSIONS: Due to the small number of studies and the small sample size for each study, the effect remains unclear. Further analysis, both qualitative and quantitative, is necessary to clarify these issues.

Adult↗

PubMed1998

[Detection of recurrent rectal cancer using helical CT with SmartPrep: a new technique for obtaining optimal contrast enhancement].

Seven patients with suspected recurrent rectal cancer underwent Helical CT using SmartPrep. SmartPrep is a software application developed by GE in which the ROI is placed at the desired level of the aorta prior to contrast injection. Using a low-dose continuous scan, the time density curve was obtained instantly, and the optimal timing of scanning was judged from the curve. Four patients who demonstrated intense enhancement at the anastomotic site had local recurrence. No intense enhancement was observed in these areas on conventional delayed CT. Thus, SmartPrep appears to be useful for the accurate diagnosis of recurrent rectal cancer.

Aged↗

PubMed1998

[Intra-arterial injection therapy of mitoxantrone for locally advanced breast cancer].

Mitoxantrone (MIT) is a new anthraquinone anticancer agent. We treated 14 patients with locally advanced breast cancer, 3 of which were inflammatory breast cancers, by pre-operative arterial injection of MIT. The treatment protocol was MIT 12 mg/m2 injected into both the internal mammary and the subclavian arteries with oral administration of 5'-DFUR 1,200 mg/day for 20 days. After 2 courses, all tumors were decreased over 50% in size. Down-staging was obtained in all of 8 cases. Mastectomy could be carried out on all patients, without microscopically residual tumor cells. Preoperative arterial injection of MIT might be the treatment of choice for locally advanced breast cancer to perform down-staging, however the survival benefit has remained equivocal. These preliminary results are encouraging to further studies.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1998

[Relation between dietary behavior and body mass index, serum lipids and socioeconomic factors in urban residents].

The purpose of this study was to obtain basic information of factors which improve the dietary behavior of urban residents. For this reason, we studied the relation between dietary behavior and BMI, serum lipids and socioeconomic factors. We surveyed the dietary behavior of those who underwent medical examinations at a health center in the city of A. The subjects for this study were 2,627 persons aged 30 to 69 years. For purposes of analysis, the data derived in the survey was divided into two types of categories. One category is that of practicing and non-practicing group relative to specific dietary behaviors. The other is that of better dietary behaviors group and worse dietary behaviors group. (1) A comparison between the practicing and non-practicing group showed that the mean value of the total cholesterol values for the former was lower than for the latter. Similar results for the triglyceride values was obtained. The mean value of the HDL-cholesterol values for the practicing group was higher than for the non-practicing group. (2) We also compared the better dietary behaviors group with the worse group. For women, the mean value of the body mass indices in the better dietary behaviors group was lower than in worse group. We obtained similar differences for women with regard to the mean values of total cholesterol values and triglyceride values. (3) More of Breslow's health practices were followed by the better dietary behaviors group than by the worse group. (4) The number of good dietary practices was significantly related to the following socioeconomic factors: marital status, floor area of residence, steady employment, and working hours. Better dietary behaviors showed parallel correlation with better health status. Dietary behaviors of younger generations and temporary workers showed a tendency of needing to be improved.

Adult↗

PubMed1997

Lack of interfering effects of lithium on receptor/G protein coupling in human platelet and rat brain membranes.

To verify the theory that lithium exerts its multiple effects by altering the receptor-mediated G protein's activation, in vitro effects of lithium on agonist-induced guanosine triphosphate (GTP) hydrolysis were examined. The basal GTP hydrolyzing activity in human platelet membranes was decreased nonselectively by either LiCl or NaCl at millimolar concentrations, whereas (-)-epinephrine-stimulated increase in the activity (an index of alpha (2A)-adrenoceptor coupled Gi2 function) was unaltered. Furthermore, the stimulation of high-affinity GTPase activity induced by dopamine, carbachol, and R-N(6)-phenylisopropyladenosine in rat brain membranes (indices of the functional coupling between dopamine D2-like, pirenzepine-insensitive muscarinic, and adenosine A1 receptors and their respective Gi proteins) was substantially unaltered regardless of whether 0.5 mmol/L adenosine 5'-(beta, gamma-imido)triphosphate (i.e., 1.75 mmol/L lithium) was included in the assay mixture or not. These results indicate that lithium does not affect in vitro the receptor-mediated activational process of G proteins, at least not of Gi associated with adenylate cyclase inhibition.

Animals↗

PubMed1997

Molecular cloning of a novel receptor-type protein tyrosine phosphatase from murine fetal liver.

A cDNA fragment encoding a novel tyrosine phosphatase (PTPase), termed ptpf, was isolated from day 11.5 mouse fetal liver using reverse transcription-polymerase chain reaction (RT-PCR) with degenerate primers. The 5.5-kb cDNA encoding the complete coding region was isolated from an adult mouse kidney cDNA library. This cDNA contained a single open reading frame (ORF) encoding a predicted 1436-amino-acid protein with a molecular mass of 161,150 Da. Sequence analysis revealed that PTPf was homologous to PTPmu and PTPkappa, and a putative receptor-type PTPase. Northern blotting analysis of adult mouse mRNA indicated the existence of four major ptpf transcripts of approximately 10, 6, 3 and 2.7 kb, and these transcripts were expressed in a tissue-specific manner. During embryogenesis, only the 6-kb transcript was detected.

Amino Acid Sequence↗

PubMed1997

Marked effect of DNA on collagen fibrillogenesis in vitro.

Growth of collagen fibrils in the presence of DNA was more rapid than that in the absence of DNA. Some of collagen fibrils formed in the presence of DNA were significantly wider than those in the absence of DNA. Moreover, the cross-bandings were also very distinct in spite of using pepsin-digested collagen. These results suggest that DNA not only adsorbs to collagen but induces the extraordinary fibrillogenesis of collagen.

Collagen↗

PubMed1997

Suppression for the proliferation of fibroblasts by external DNA.

Phase-contrast and fluorescence microscopic observation showed that DNA added in the cell-culture medium for fibroblasts localized just on the surface of fibroblasts. The DNA bound to fibroblasts was found to be eluted by treating with collagenase. The suppression for the proliferation of fibroblasts by external DNA was confirmed with microscopic observation for the cells cultured in the presence and absence of DNA. Proliferation of the cells decreased from 412 to 155% by the addition of DNA. These results indicate that DNA has an affinity for collagen, the most major extracellular-matrix produced by fibroblasts, and suppresses the growth of fibroblasts.

Cell Division↗

PubMed1997

DNA-alginate complex recognized by autoantibodies against DNA.

Double-stranded DNA was effectively complexed with alginic acid and immobilized on a surface of polystyrene microtiter plate. Dose-dependent binding of anti-DNA autoantibodies was finely observed to the solid phase DNA-alginate complex in enzyme-linked immunosorbent assay (ELISA). In contrast, non-specific binding of antibodies to alginate was scarcely detected rather than to poly-L-lysine. These results shown an availability of the solid phase DNA-alginate complex as an antigen in ELISA for detection of anti-DNA antibodies.

Alginates↗

PubMed1997

Conformation of nucleoplasmin and its interaction with DNA-protamine complex as a simple model of fish sperm nuclei.

Nucleoplasmin was isolated from Xenopus laevis eggs and purified by an improved method using an open column. Its conformation was investigated spectrophotometrically by UV, CD and fluorescence. It was shown that alpha-helix content of nucleoplasmin was 30-40%, and one of the two tryptophan residues in nucleoplasmin located in the hydrophobic surroundings and the other in the relatively hydrophilic surroundings. The isolated nucleoplasmin was found to decondense sperm nuclei of salmon also, suggesting a possibility of the existence of nucleoplasmin-like protein in fish as well. Collapse of the protamine (salmine)-DNA complex as a simple model for fish sperm nuclei by nucleoplasmin was directly observed by measuring OD320 of aqueous protamine-DNA mixtures. This is a molecular level observation for the removal of protamine from DNA-protamine complex.

Amino Acid Sequence↗

PubMed1997

Superoxide generation by monocytes following infection with human cytomegalovirus.

A significant level of superoxide (O2-) generation was observed in a U937-derived subclone following infection with human cytomegalovirus (HCMV). Although there were no detectable levels of viral mRNA and/or protein expression, HCMV DNA content transiently increased immediately before O2- generation. Similarly, O2- generation was also observed in peripheral blood monocytes derived from healthy donors.

Cytomegalovirus↗

PubMed1997

Effects of the wasp venom peptide, mastoparan, on GTP hydrolysis in rat brain membranes.

1. The effects of mastoparan, a wasp venom toxin, on GTP hydrolyzing activity were examined in rat brain membranes. 2. Mastoparan inhibited the low-affinity GTPase activity, defined as the amount of 32Pi released from 0.3 microm [gamma-32P]-GTP in the presence of 100 microM unlabelled GTP, in a concentration-dependent manner. This inhibitory effect of mastoparan on low-affinity GTPase activity was diminished by increasing concentrations of UDP and was completely attenuated at 20 mM, indicating that activation of nucleoside diphosphokinase (NDPK) is inolved in the phenomenon. 3. In the presence of 20 mM UDP, mastoparan stimulated the high-affinity GTPase activity by increasing the Vmax value without affecting the apparent K(M) for GTP. Mastoparan-stimulated high-affinity GTPase activity was apparent at concentrations higher than 1 microM, in a concentration-dependent manner, but without saturation even at 100 microM. 4. Mastoparan-induced high-affinity GTPase activity showed a characteristic sensitivity to MgCl2, quite different from that seen in L-glutamate-stimulated activity, a representative of receptor-mediated G-protein activation. 5. There appeared to be a simple additive interaction between mastoparan- and L-glutamate-stimulated high-affinity GTPase activities, indicting that distinct pools of G-proteins are involved in receptor-independent and receptor-mediated G-protein activation. 6. These results suggest that G-proteins in brain membranes are functionally altered by mastoparan through multiple mechanisms of action and that the mastoparan-induced, direct G-protein activating process lacks a synergistic or antagonistic interaction with an agonist-induced, receptor-mediated activation of G-proteins.

Animals↗

PubMed1997

Isolation and characterization of invasive and noninvasive variants of a rat bladder tumor cell line.

We isolated, in vitro, spontaneous variants of the rat bladder tumor NBT-II cell line with a distinctive morphology. Of five sublines obtained, three (NBT-L1, L2a and L2b) exhibited an elongated shape and moderate to high invasive activity in vitro. The other two sublines (NBT-T1 and T2) formed tight colonies and exhibited very low or negligible invasive activity. The contents of mRNAs coding for E-cadherin and cadherin-associated molecules (alpha-catenin and beta-catenin) were not correlated with the invasive activity of the cells. However, the expression level of the E-cadherin protein, but not those of catenins, was lower in invasive cells (NBT-L1, L2a and L2b) than in noninvasive cells (NBT-T1 and T2). Analysis of mRNAs coding for several growth factors and their receptors showed that the transforming growth factor alpha mRNA content in invasive cells was higher than that in noninvasive cells, and that the content of epidermal growth factor receptor mRNA was low in NBT-T2. Although NBT-II is known to acquire a fibroblastic appearance and cell motility in response to several growth factors, the conditioned media of the invasive sublines hardly affected the morphology or motility of noninvasive cells. These results indicate that the decreased E-cadherin expression is closely associated with the transition from the noninvasive to the invasive phenotype of the bladder tumor cells, and that a post-transcriptional process is important in the control of E-cadherin expression in the cells. These sublines may be useful as models for studies on the progression of bladder tumors.

Animals↗

PubMed1997

Prevalence of asymptomatic carotid atherosclerotic lesions detected by high-resolution ultrasonography and its relation to cardiovascular risk factors in the general population of a Japanese city: the Suita study.

BACKGROUND AND PURPOSE: Because extracranial carotid atherosclerotic lesions have been considered rare, no reports have been published on the prevalence and distribution of these lesions in a general Japanese population. However, recent changes in lifestyle are thought to have caused an increase in these lesions. The aim of this study was to use high-resolution ultrasonography to examine the prevalence of asymptomatic extracranial carotid artery lesions and its relation to cardiovascular risk factors in an urban Japanese population. METHODS: The subjects were 814 men and 880 women aged 50 to 79 years randomly sampled from the residents of Suita, a city located in the second largest urban area of Japan. Asymptomatic carotid lesions were detected and evaluated by a single physician with high-resolution B-mode ultrasonography. RESULTS: We found significant sex differences in the prevalence of atherosclerotic lesions in the extracranial carotid artery; 4.4% of all the subjects, 7.9% of the men, and 1.3% of the women had atherosclerosis accompanied by stenosis of >50%. A strong association between these lesions and the results of a 75-g oral glucose tolerance test was found in both sexes. Multiple regression analysis of carotid atherosclerosis showed significant relationships with age, systolic blood pressure, fasting blood glucose, pack-years of smoking, total serum cholesterol, and HDL cholesterol in men (P<.05) and significant relationships with age, systolic blood pressure, pack-years of smoking, and total serum cholesterol in women (P<.05). CONCLUSIONS: Our data showed that cardiovascular risk factors were strongly related to carotid atherosclerosis and that the proportion of severe carotid atherosclerosis with >50% stenosis was not low and was almost equal to that reported in developed western countries.

Aged↗