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Biomedical subjects

T Higuchi

Publications and source records attributed to T Higuchi.

At least 127 records · Page 7Linked to original sources
PubMed2000

Analysis of tumor necrosis factor-alpha promoter polymorphism in type 1 diabetes: HLA-B and -DRB1 alleles are primarily associated with the disease in Japanese.

Polymorphisms in the 5'-flanking region of the tumor necrosis factor (TNF)-alpha gene were examined to study the genetic background of type 1 diabetes in Japanese. Five different biallelic polymorphisms were examined in 136 type 1 diabetic patients and 300 control subjects. The frequencies of individuals carrying TNF-alpha-857T allele (designated as TNFP-D allele) or -863A/-1,031C allele (designated as TNFP-B allele) were significantly increased in the patients as compared with the controls. Since these TNF-alpha alleles are in linkage disequilibria with certain DRB1 and HLA-B alleles, two-locus analyses were carried out. The TNFP-D allele did not increase the risk in either the presence or absence of the DRB1*0405 or HLA-B54 allele, while the DRB1*0405 and HLA-B54 alleles per se could confer susceptibility in both the TNFP-D allele-positive and -negative populations. Moreover, an odds ratio was remarkably elevated in the population carrying both DRB1*0405 and HLA-B54. Similarly, the TNFP-B allele did not show significant association with the disease in either the HLA-B61-positive or -negative population, while the HLA-B61 allele could significantly increase the risk in the TNFP-B allele-positive population. These data suggest that the associations of TNFP-D and -B alleles may be secondary to their linkage disequilibria with the susceptible HLA class I and class II alleles. Because HLA-B and DRB1 genes were independently associated, both of these genes may be contributed primarily to the pathogenesis of type 1 diabetes in Japanese.

Adolescent↗
PubMed2000

Susceptible locus for obese type 2 diabetes mellitus in the 5'-flanking region of the tumor necrosis factor-alpha gene.

We have identified three novel polymorphisms in the promoter/enhancer region of the tumor necrosis factor (TNF)-alpha gene. In this study we investigated the role of the polymorphisms in predisposition to Type 2 diabetes. The allele frequency of C-->T substitution at -857 tended to be higher in obese patients with diabetes than in lean subjects with normal glucose tolerance (0280 vs. 0.190). This tendency was due to a significantly higher ratio of -857T homozygotes in the obese patients with diabetes (15%) than in lean subjects with normal glucose tolerance (4%). There was no significant association between polymorphisms at positions -863 or -1,013, and diabetes. The homozygous -857T allele may be associated with genetic susceptibility to type 2 diabetes in obese subjects.

5' Untranslated Regions↗
PubMed2000

Effect of suckling on NADPH-diaphorase (Nitric oxide synthase, NOS) reactivity and NOS gene expression in the paraventricular and supraoptic nuclei of lactating rats.

This study examined the effect of suckling on nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d, a histochemical marker for nitric oxide synthase, NOS) reactivity and neuronal NOS mRNA expression in the paraventricular (PVN) and supraoptic (SON) nuclei of lactating rats. Freely nursing (non-separated) dams and those separated from pups for 12 h and then reunited for 0, 15, 30, 60, 90, 120 and 180 min were used for the study. Dams separated from pups and sacrificed at time zero (without reunion) showed a significant decrease in NADPH-d staining and NADPH-d positive cells as well as in the NOS mRNA expression in the PVN and SON compared to that observed in non-separated dams. Reunion with pups and restoration of suckling significantly increased NADPH-d reactivity after 15, 30, 60 min, but not after 90, 120 and 180 min compared to non-reunited pups-deprived dams. A pattern of NADPH-d reactivity and neuronal NOS mRNA expression indistinguishable from that observed during free lactation was reinstated shortly (15 min) after the restoration of suckling stimulus, suggesting that the NADPH-d reactivity in lactation depends on the presence of the suckling stimulus. These results show that suckling stimulus may play a modulatory role in the regulation of NOS reactivity in the magnocellular neurones of the hypothalamic PVN and SON during lactation.

Animals↗
PubMed2000

A zinc-finger protein, Rst2p, regulates transcription of the fission yeast ste11(+) gene, which encodes a pivotal transcription factor for sexual development.

Schizosaccharomyces pombe ste11 encodes a high-mobility group family transcriptional activator that is pivotal in sexual development. Transcription of ste11 is induced by starvation of nutrients via a decrease of the cAMP-dependent protein kinase (PKA) activity. Here we report the identification of a novel transcription factor, Rst2p, that directly regulates ste11 expression. Cells in which the rst2 gene was disrupted expressed ste11 poorly and were sterile, and this sterility could be suppressed by artificial expression of ste11. Disruption of rst2 suppressed hypermating and hypersporulation in the PKA-null mutant, whereas overexpression of rst2 induced sexual development in the PKA-activated mutant. Cloning analysis indicated that Rst2p was a Cys(2)His(2) zinc-finger protein carrying 567 amino acid residues. Rst2p could bind specifically to a stress response element-like cis element located in the ste11 promoter region, which was important for ste11 expression. Meanwhile, transcription of ste11 was reduced significantly by a defective mutation in itself. An artificial supply of functional Ste11p circumvented this reduction. A complete Ste11p-binding motif (TR box) found in the promoter region was necessary for the full expression of ste11, suggesting that Ste11p is involved in the activation of ste11. We conclude that transcription of ste11 is under autoregulation in addition to control through the PKA-Rst2p pathway.

Amino Acid Sequence↗
PubMed2000

Characterization of the rabbit homolog of human MUC1 glycoprotein isolated from bladder by affinity chromatography on immobilized jacalin.

The urinary bladder is lined by transitional epithelium, the glycocalyx on the luminal surface has interesting properties and is implicated in protective functions. Glycoconjugates are major components of the glycocalyx, but their biochemical nature is not well understood. Previous studies on rabbit bladder indicated the presence of significant levels of sialoglycoproteins compared to glycosaminoglycans in the epithelium. In this study, rabbit explant cultures were radiolabeled by precursor sugars or amino acids and a major lectin-reactive glycoprotein of rabbit bladder mucosa was isolated by affinity chromatography on jacalin-agarose. The radiolabeled glycoprotein was purified to homogeneity by a second cycle on the lectin column, followed by gel filtration and density gradient centrifugation. The average molecular mass of the glycoprotein was estimated to be 245 kDa and 210 kDa by gel filtration and SDS-PAGE, respectively. Its buoyant density was 1.40 g/ml, suggesting a carbohydrate content of approximately 50%. The percent distribution of glucosamine-derived tritium label in sialic acid, galactosamine, and glucosamine was 30, 52, and 18, respectively. The glycoprotein consisted entirely of small sialylated and neutral oligosaccharides O-glycosidically linked to serine and threonine residues. The same glycoprotein could be immunoprecipitated with an antibody against the carboxy terminal 17 amino acid peptide of human MUC1 mucin glycoprotein. This suggests that this mucin glycoprotein is the rabbit homolog of MUC1 glycoprotein, which has been previously established to be a component of human bladder urothelium and has been purified from human urine and biochemically characterized.

Animals↗
PubMed2000

Rapid B cell apoptosis induced by antigen receptor ligation does not require Fas (CD95/APO-1), the adaptor protein FADD/MORT1 or CrmA-sensitive caspases but is defective in both MRL-+/+ and MRL-lpr/lpr mice.

Antigen receptor ligation-induced apoptosis is thought to play a role in self-tolerance by deleting autoreactive lymphocytes. Antigen receptor ligation-induced apoptosis of mature T cells and T cell lines requires autocrine or paracrine activation of Fas (CD95/APO-1). Whether B cell antigen receptor (BCR)-mediated apoptosis requires Fas or related molecules is unclear. Here we demonstrate that expression of either CrmA, the cowpox virus serpin, or an inhibitor of the adapter protein FADD/MORT1 blocks Fas-mediated apoptosis but has no effect on BCR ligation-induced apoptosis of the B cell line WEHI-231. In contrast, expression of Bcl-2 blocks BCR-mediated but not Fas-induced apoptosis in WEHI-231 cells. These results indicate that BCR ligation activates an apoptotic signaling pathway distinct from Fas-mediated apoptosis in WEHI-231 cells, and that BCR-mediated apoptosis of WEHI-231 cells does not require Fas or related molecules such as DR3, DR4 and DR5, as all of these death receptors require FADD/MORT1 and/or CrmA-sensitive caspases for induction of apoptosis. Moreover, extensive BCR ligation induces death of mature B cells from C57BL/6-lpr/lpr mice as efficiently as those from C57BL/6 mice, indicating that Fas is not essential for BCR-mediated apoptosis of mature B cells. In contrast, BCR ligation-induced apoptosis is reduced in mature B cells from MRL mice and this is not affected by the lpr mutation. Since MRL-lpr/lpr mice but not C57BL/6-lpr/lpr mice develop severe autoimmune disease, defects in BCR-mediated apoptosis in the MRL background, together with lpr mutation, may contribute to the development of severe autoimmune disease in MRL-lpr/lpr mice by allowing survival of self-reactive B cells.

Adaptor Proteins, Signal Transducing↗
PubMed2000

CD9 is expressed on human endometrial epithelial cells in association with integrins alpha(6), alpha(3) and beta(1).

Recently we reported that CD9 is involved in the invasion of a trophoblast-like choriocarcinoma cell line, BeWo, probably through the regulation of integrin functions. Integrins have also been reported to be expressed in the human endometrium and it has been suggested that they play important roles in blastocyst implantation. This study used immunohistochemistry to investigate the expression of CD9 in the endometrium during the menstrual cycle. CD9 was found to be intensely expressed on the cell surface of the glandular epithelium throughout the menstrual cycle without any apparent differences in staining intensity. In addition, Western blotting analysis of the affinity-purified proteins confirmed that CD9 was associated with integrins beta(1), alpha(3) and alpha(6) in the human endometrium. Therefore it can be concluded that CD9, in association with integrins alpha(6), alpha(3) and beta(1), is a constitutive molecule of the endometrial glandular epithelium. These results also suggest that CD9 may be an important regulator of these integrins in the human endometrium.

Antibodies, Monoclonal↗
PubMed2000

Anti-CD9 monoclonal antibody-stimulated invasion of endometrial cancer cell lines in vitro: possible inhibitory effect of CD9 in endometrial cancer invasion.

Cell surface marker CD9 has been reported to play a role in inhibiting trophoblastic cell invasion. Since the invasive properties of cancer cells may resemble those of trophoblasts, we decided to investigate the role of CD9 in the invasion of endometrial cancer cells. In normal human endometrium, CD9 was found to be constitutively expressed on epithelial cells, as reported previously. While epithelial cells of endometrial hyperplasia (n = 5) were also positive for the expression of CD9, endometrial adenocarcinomas (n = 15) showed reduced expression. In order to clarify the significance of this reduced CD9 expression in endometrial cancer, an in-vitro invasion assay system was used to assess the effect of anti-CD9 monoclonal antibody (mAb) on the invasive properties of endometrial cancer cell line. Anti-CD9 mAb significantly enhanced invasion of the RL95-2 and Ishikawa cell lines, without affecting cell proliferation. Since CD9 is associated with the integrin subunits beta(1), alpha(3) and alpha(6) in human endometrium, we investigated the functional relationship between CD9 and these integrins in the RL95-2 cell line. Monoclonal antibodies against the integrins beta(1), alpha(3) and alpha(6) inhibited RL95-2 cell invasion. However, anti-CD9 mAb continued to show a stimulatory effect on RL95-2 cell invasion after treatment with anti-integrin alpha(3) mAb. In contrast, the anti-CD9 mAb had no effect after treatment with the mAb for integrins alpha(6) and beta(1). These findings indicate that CD9 is involved in regulating the invasive properties of endometrial carcinoma cells and that this effect is partially mediated by integrin subunits alpha(6) and beta(1). Thus, CD9 appears to be involved in the prevention of endometrial cancer invasion.

Adult↗
PubMed2000

The role of structural intersubunit microheterogeneity in the regulation of the activity in hysteresis of ribulose 1, 5-bisphosphate carboxylase/oxygenase.

Many enzymes are composed of subunits with the identical primary structure. It has been believed that the protein structure of these subunits is the same. Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) comprises eight large subunits with the identical amino acid sequence and eight small subunits. Rotation of the side chains of the lysine residues, Lys-21 and Lys-305, in each of the eight large subunits in spinach RuBisCO in two ways produces microheterogeneity among the subunits. These structures are stabilized through hydrogen bonds by water molecules incorporated into the large subunits. This may cause different effects upon catalysis and a hysteretic, time-dependent decrease in activity in spinach RuBisCO. Changing the amino acid residues corresponding to Lys-21 and Lys-305 in non-hysteretic Chromatium vinosum RuBisCO to lysine induces hysteresis and increases the catalytic activity from 8.8 to 15.8 per site per second. This rate is approximately five times higher than that of the higher-plant enzyme.

Catalysis↗
PubMed2000

Superoxide dismutase activity of iron(II)TPEN complex and its derivatives.

Superoxide is involved in the pathogenesis of various diseases, such as inflammation, ischemia-reperfusion injury and carcinogenesis. Superoxide dismutases (SODs) catalyze the disproportionation reaction of superoxide to produce oxygen and hydrogen peroxide, and can protect living cells against the toxicity of free radicals derived from oxygen. Thus, SODs and their functional mimics have potential value as pharmaceuticals. We have previously reported that Fe(II)tetrakis-N,N,N',N'-(2-pyridylmethyl)ethylenediamine (Fe(II)TPEN) has an excellent SOD activity (IC50 = 0.5 microM) among many iron complexes examined (J. Biol. Chem., 264, 9243-9249 (1989)). Fe(II)TPEN can act like native SOD in living cells, and protect Escherichia coli cells from free radical toxicity caused by paraquat. In order to develop more effective SOD functional mimics, we synthesized Fe(II)TPEN derivatives with electron-donating or electron-withdrawing groups at the 4-position of all pyridines of TPEN, and measured the SOD activities and the redox potentials of these complexes. Fe(II) tetrakis-N,N,N',N'-(4-methoxy-2-pyridylmethyl)ethylenediamine (Fe(II)(4MeO)4TPEN) had the highest SOD activity (IC50 = 0.1 microM) among these iron-based SOD mimics. In addition, a good correlation was found between the redox potential and the SOD activity of 15 Fe(II) complexes, including iron-based SOD mimics reported in the previous paper (J. Organometal. Chem., in press). Iron-based SOD mimics may be clinically applicable, because these complexes are generally tissue-permeable and show low toxicity. Therefore our findings should be significant for the development of clinically useful SOD mimics.

Ethylenediamines↗
PubMed2000

A novel lantibiotic, nukacin ISK-1, of Staphylococcus warneri ISK-1: cloning of the structural gene and identification of the structure.

Staphylococcus warneri ISK-1, which we had previously reported as Pediococcus sp. ISK-1, produces a novel bacteriocin, nukacin ISK-1. Edman degradation of the chemically reduced nukacin ISK-1 produced a sequence of 27 amino acids, 7 of which were unidentified. Using single-specific-primer-PCR product as a probe, a 3.6-kb HindIII fragment containing the nukacin ISK-1 structural gene (nukA) was cloned and sequenced. The deduced amino acid sequence of nukacin ISK-1 had 57 amino acids, including a 30-amino acid leader region. The propeptide sequence showed significant similarity to those of lacticin-481 type lantibiotics. In the region upstream of nukA, a part of a long open reading frame (ORF), designated as nukM, encoding a putative modification enzyme was oriented in the opposite direction. In the region downstream of nukA, ORF1 was found in which the sequence of the putative translational product was similar to various response regulatory proteins.

Amino Acid Sequence↗
PubMed2000

Oxytocin receptor gene expression in rat uterus: regulation by ovarian steroids.

The present study was designed to investigate a possible role for ovarian steroids in the regulation of rat uterine oxytocin receptor (OTR) mRNA expression before labour. By using a competitive RT-PCR system, we have previously reported that parturition was associated with high levels of uterine OTR mRNA in all the animals examined. On the other hand, near term, some rats showed high OTR mRNA levels while others did not. We therefore examined the changes in OTR mRNA expression before and during prostaglandin F(2)(alpha) (PGF(2)(alpha))-induced parturition; a paradigm adopted to reduce the variation in the onset of parturition. Injection of PGF(2)(alpha) on day 18 of pregnancy significantly increased OTR mRNA expression in all the rats within 24 h of treatment, suggesting that the variation in OTR mRNA levels during spontaneous parturition may be due to the difference in the timing of the onset of parturition. The increase in OTR mRNA was significantly abolished by injection of the anti-oestrogen compound, tamoxifen. The stimulatory action of oestrogen on OTR mRNA expression was then examined in the presence or absence of ovarian factors. Pregnant rats were ovariectomized (OVX) or sham-operated on day 18 of pregnancy and either oestrogen or vehicle was administered 6 h after the surgical operation. Oestrogen increased OTR mRNA significantly in OVX rats 18 h after administration compared with sham-operated animals. Moreover, ovariectomy alone on day 18 of pregnancy increased OTR mRNA expression to a level which reached statistical significance 24 h after the operation. In addition, oestrogen treatment increased OTR mRNA levels in OVX virgin rats in which progesterone tubes were implanted for 1 week and removed 6 h before oestrogen injection. The stimulatory effect of oestrogen was not observed in rats in which the progesterone tubes were implanted for 1 week and not removed. These results suggest that the decline of progesterone is necessary for the expression of the stimulatory effects of oestrogen on uterine OTR mRNA.

Analysis of Variance↗
PubMed2000

Evaluation of nasotracheal aspiration as a diagnostic tool for Rhodococcus equi pneumonia in foals.

The reliability of preparing bacteriological cultures from nasotracheal aspirates of foals routinely in order to diagnose R. equi pneumonia in foals was studied by isolating Rhodococcus equi from specimens obtained from 96 foals by nasotracheal aspiration with a silicon catheter. Results were compared with specimens obtained from 21 foals by transtracheal aspiration (percutaneous tracheal puncture). These 117 foals showed clinical signs of respiratory tract infection at sampling. R. equi was isolated from 14 of 21 (66.7%) specimens by transtracheal aspiration and from 59 of 96 (61.4%) specimens by nasotracheal aspiration, 649 of 655 isolates (99.1%) from the 73 positive specimens were virulent R. equi, and the culture-positive foals were diagnosed as having R. equi pneumonia. To assess the contamination of aspirates by organisms from the nasopharynx, the results of R. equi isolation from nasal swabs obtained from 56 of the 96 foals were compared to those obtained by nasotracheal aspiration from the same foals. R. equi was isolated from 2 of the 56 nasal swabs: one from a tracheal aspirate was positive, and the other was not. These results suggest that the nasotracheal aspiration technique, which is noninvasive and not associated with complications, could be used as an alternative to the transtracheal aspiration method, especially for the diagnosis of R. equi pneumonia in foals.

Actinomycetales Infections↗
PubMed2000

[Measurement of myocardial blood flow increase rate at exercise with 99mTc-tetrofosmin radionuclide angiography].

UNLABELLED: We developed new method to calculate myocardial blood flow increase rate at exercise (MBF-IR) with 99mTc-tetrofosmin (TF) radionuclide (RN) angiography and myocardial perfusion SPECT and assessed its feasibility using clinical data. METHOD: Fifteen patients who were suspected to have coronary artery disease underwent TF RN angiography and SPECT at exercise and at rest. Seven patients had coronary stenosis and eight patients had no significant coronary stenosis in coronary angiography. MBF-IRs were calculated by the following equation: [formula: see text] where Cr = regional myocardial count at rest, Ce = regional myocardial count at exercise [formula: see text] = the area under ventricular time activity curve at rest and [formula: see text] = the area under ventricular time activity curve at exercise. RESULT: Rate pressure product (RPP) was similar in patients with and without coronary stenosis (24,509 +/- 6701.9 vs. 27,196 +/- 4862.4, p = 0.39). MBF-IR was 1.88 +/- 0.73 in the area covered by stenosed coronary artery, 2.53 +/- 0.75 in unstenosed coronary artery in patients who have significant coronary stenosis and 2.97 +/- 0.77 in normal coronary patients. MBF-IRs in the area covered by stenosed coronary arteries were significantly smaller than that of normal coronary artery patient (p = 0.037). Interobserver and intraobserber reproducibility were good (r = 0.96, 0.95 respectively). There was strong positive correlation between MBF-IR and RPP in normal patients (r = 0.69, p = 0.0018), suggesting MBF increase depends on the cardiac workload. CONCLUSION: MBF-IR can be estimated by the combination of TF RN angiography and SPECT at exercise and at rest.

Aged↗
PubMed2000

Regional cerebral blood flow in the patients with depressive disorders.

Regional Cerebral blood flow (rCBF) and metabolism in major depression have been studied intently. Those studies are expected to reveal the mechanisms of the mood disorders, and also to give us valuable informations that the specific brain regions participating mood regulation. However, the data still have been inconsistent. In the present study we measured rCBF in patients with major depression and depressive state using xenon-CT CBF method. There is a tendencies that the rCBF values of normal control is the highest, and those of major depression is the lowest in most of the regions. The rCBF values in the patients with major depression are significantly lower than those in normal control in the right anterior frontal cortex, temporal cortex, putamen and thalamus. We also measured rCBF before and 90 minutes after giving calcium antagonist nilvadipine (4 mg, p.o.) in those subject. There is a tendency that nilvadipine increased in rCBF in normal control, however, it decreased in rCBF in major depression.

Adult↗
PubMed2000

Thrombopoietin enhances neutrophil production by bone marrow hematopoietic progenitors with the aid of stem cell factor in congenital neutropenia.

We examined the effects of granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), and thrombopoietin (TPO), alone or in combination, on the generation of neutrophils by bone marrow (BM) cells from three patients with severe congenital neutropenia (SCN) through the use of a serum-deprived liquid culture system. Synergistic effects of G-CSF and SCF on the neutrophil production by BM CD34+CD38+c-kit+ cells were observed in SCN patients as well as in normal controls. The addition of TPO to the culture containing G-CSF and SCF further augmented the growth of neutrophils in the two groups. Single-cell culture experiments revealed that the three-factor combination caused increases in both the number and size of neutrophil colonies compared with G-CSF + SCF in normal BM cells, whereas only a significant increment in the colony size was observed in SCN patients. Even in the presence of SCF or SCF + TPO, the concentrations of G-CSF necessary for the substantial production of neutrophils by CD34+CD38+c-kit+ cells were higher in two patients compared with the levels obtained by normal control cells. In addition, TPO did not accelerate the maturation of neutrophilic cells supported by G-CSF + SCF. When BM CD34+CD38-c-kit+ cells were targeted, the addition of TPO to the culture containing G-CSF and SCF was required for significant neutrophil colony growth in the two groups. These results suggest that TPO enhances the G-CSF-dependent neutrophil production with the aid of SCF in this disorder.

ADP-ribosyl Cyclase↗