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Biomedical subjects

T Higuchi

Publications and source records attributed to T Higuchi.

At least 361 records · Page 20Linked to original sources
PubMed1995

Identification of two highly homologous presynaptic proteins distinctly localized at the dendritic and somatic synapses.

Through screening of a murine brain cDNA library, we have isolated two brain specific cDNAs encoding highly homologous proteins, named 921-L and 921-S, comprised of 134 amino acids with 80% identity. Immunohistological study with the mAbs raised against the bacterially expressed 921 proteins showed that 921-L protein is distributed at the dendritic region and 921-S at the neuronal somatic surface. Immuno-electron microscopic study revealed that both 921 proteins are localized at the presynaptic terminal, indicating that the 921 proteins are differentially expressed at the dendritic and somatic presynapses.

Adaptor Proteins, Vesicular Transport↗
PubMed1995

Hyaluronic-acid-deficient extracellular matrix induced by addition of 4-methylumbelliferone to the medium of cultured human skin fibroblasts.

The effects of xylosyl-beta-D-(4-methylumbelliferone) and its aglycone, 4-methylumbelliferone, on hyaluronic acid synthesis were investigated in cultured human skin fibroblasts. Xylosyl-beta-D-(4-methylumbelliferone) added to the medium of cultured cell reduced the synthesis of hyaluronic acid. Furthermore, 4-methylumbelliferone reduced the production of hyaluronic acid markedly. In addition, 4-methylumbelliferone had hardly any effect on proteoglycan synthesis, whereas xylosyl-beta-D-(4-methylumbelliferone) produced a large amount of glycosaminoglycan chains. The present results indicate that cells cultured with 4-methylumbelliferone produce a hyaluronic-acid-deficient extracellular matrix, which will be useful for functional studies of hyaluronic acid.

Cells, Cultured↗
PubMed1995

Leukemic transformation of polycythemia vera and essential thrombocythemia possibly associated with an alkylating agent.

BACKGROUND: Leukemic transformation of polycythemia vera (PV) and essential thrombocythemia (ET) is influenced by the therapeutic modalities used. A high incidence of leukemic transformation was found among patients with PV or ET treated with an alkylating agent, carboquone (CQ). The study was conducted to assess the causal relationship between CQ and leukemic transformation of PV and ET. METHOD: Twenty-seven patients with PV and 29 with ET diagnosed from January 1975 to August 1993 and whose clinical course could be followed comprised the members of this retrospective study. The patients were examined for the treatment administered, hematologic data, vascular complications, malignancies including leukemia, and eventual outcome. RESULTS: Eighteen patients with PV and 16 with ET were treated with CQ. The follow-up was 51-209 months for patients with PV and 28-176 months for those with ET. Three patients with PV (17% of those treated with CQ) and 5 with ET (31% of those treated with CQ) had subsequent transformation to acute leukemia. The median period until transformation of patients with PV was 94 months, whereas the median follow-up of patients without transformation was 146 months (P < 0.01). The median total days of CQ administration and the median total dose of CQ were 2022 days and 1226 mg, respectively, for the patients with transformation and 1051 days (P < 0.05) and 435 mg (P < 0.01), respectively, for those without transformation. Likewise, the median follow-ups for patients with ET with or without transformation were 130 and 90 months, respectively; the difference was insignificant. The median total days of CQ administration and the median total dose of CQ were 2075 days and 1019 mg, respectively, for patients with transformation and 571 days (P < 0.05) and 231 mg (P < 0.01), respectively, for those without transformation. These observations suggest that CQ may be involved in the leukemic transformation of PV and ET. The subtypes of leukemia transformed from PV corresponded to M2 in two patients and to M4 in one. All five patients with ET were found to have megakaryoblastic features at transformation, and three were diagnosed as having leukemic subtype M7. Chromosomal abnormalities were found in all five patients (two PV and three ET) examined after leukemic transformation, showing multiple and complex abnormalities in four. CONCLUSION: Showing that both the total days of CQ administration and the total dose of CQ were larger for patients with PV or ET whose disease subsequently transformed to leukemia, with this study, a possible causal role of CQ in leukemic transformation of PV and ET is suggested.

Adult↗
PubMed1995

Failure of intrabulbar and peripheral administration of N omega-nitro-L-arginine to prevent the formation of an olfactory memory in mice.

The gaseous neurotransmitter molecule nitric oxide (NO) has recently generated a lot of interest on account of its possible physiological role in several models of learning and memory, both in vitro and in vivo. The presence of its synthesizing enzyme has been reported in the granule cell and external plexiform layers of the accessory olfactory bulb (AOB) in mice and rats. We have tested the effect of different doses of the nitric oxide synthase inhibitor, N omega-nitro-L-arginine applied locally and peripherally, on the formation of olfactory recognition memory in the context of pregnancy block in mice. Local infusions of 5, 10, and 40 nmol of the NOS inhibitor into the AOB failed to prevent memory formation of the stud male without affecting the effectiveness of the strange male to induce pregnancy block. Peripheral administration of the NOS inhibitor produced a pregnancy block rate that was linearly related to the dose regardless of whether or not exposure to the familiar or no male subsequently followed. This suggests that the effect of peripheral administration of the NOS inhibitor on memory formation could not be assessed using this experimental paradigm. The observations made in this study do not enable us to envisage any critical or primary physiological role for NO in this memory model. Its role, at best, may be modulatory and not obligatory.

Animals↗
PubMed1995

The importance of calmodulin in the accessory olfactory bulb in the formation of an olfactory memory in mice.

Female mice form an olfactory memory to the pheromones of the mating male, during a critical period after mating. Failure to form this memory results in the male being treated as strange, and hence, his pheromones block pregnancy. Previous studies have shown that formation of this memory is dependent on synaptic mechanisms in the accessory olfactory bulb. A number of studies have pointed to calmodulin as a critical mediator of synaptic plasticity. In this study we have examined the effects of local infusions of drugs which block calmodulin-regulated processes, into the accessory olfactory bulb on the formation of this memory. Infusions of the calmodulin antagonist calmidazolium during the critical period prevented memory formation. However, the specific inhibitor of calcium/calmodulin-dependent protein kinase II, KN-62, or the selective inhibitor of calcium/calmodulin-dependent protein phosphatase 2B (calcineurin), FK506, was without effect on memory formation at any of the doses used. Instead of preventing memory formation, FK506 permitted the formation of a non-selective memory to strange male pheromones in the presence of mating, although FK506 alone could not induce a memory without the occurrence of mating. These results suggest that calmodulin in the accessory olfactory bulb is important in the formation of the olfactory memory to male pheromones. However, memory formation may be independent of calmodulin-kinase II. Calcineurin may play a role in processes antagonizing memory formation.

Animals↗
PubMed1995

Application of chemical cytochrome P-450 model systems to studies on drug metabolism--VIII. Novel metabolism of carboxylic acids via oxidative decarboxylation.

The oxidative decarboxylation of carboxylic acids by the chemical cytochrome P-450 model and rat liver microsomal systems was investigated. In the chemical system using meso-tetrakis(pentafluorophenyl)porphyrin iron chloride [Fe(TPFPP)Cl] with iodosylbenzene (PhIO), alpha-arylcarboxylic acids and alpha,alpha,alpha-trisubstituted acetic acids are converted to the corresponding one-carbon-reduced alcohol (I) and carbonyl derivatives (II) via oxidative decarboxylation. These products were then used as standards to identify the metabolites in vivo and in vitro. Biliary excretion of Ia and IIa in bile duct-cannulated rats after oral administration of ketoprofen amounted to 0.22 and 0.03% of the dose, respectively. In the case of indomethacin, Ib and IIb were detected as metabolites in the rat liver microsomal system, in yields of 2.8 and 0.29%, respectively. Further, the yields of Ib and IIb were decreased in the presence of SKF-525A. Thus, these metabolites were formed by cytochrome P-450-dependent reactions. Metabolites Ia, Ib, IIa and IIb had moderate to strong inhibitory activities on arachidonic acid-induced platelet aggregation and cyclooxygenase activity in vitro, comparable to those of the parent compounds.

Animals↗
PubMed1995

Expression of messenger ribonucleic acid for gonadal steroid receptors in the human pelvic peritoneum.

OBJECTIVE: To investigate the expression of messenger RNA (mRNA) for gonadal steroid hormone receptors in the human pelvic peritoneum. DESIGN: Analysis of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR) mRNA expressions in the pelvic peritoneum was carried out using the quantitative reverse transcription-polymerase chain reaction (PCR) method. SETTING: Department of Gynecology and Obstetrics, Kyoto University Hospital, Kyoto, Japan. PATIENTS: Pelvic peritoneal tissues from patients with (n = 10) and without (n = 10) endometriosis who had undergone gynecological surgery were studied. RESULTS: Estrogen receptor, PR, and AR mRNAs were detected in all pelvic peritoneal samples analyzed. In the pelvic peritoneum of patients without endometriosis, ER mRNA levels were significantly lower in the luteal phase than in the follicular phase. This cyclic profile of ER mRNA expression was not observed in the pelvic peritoneum of patients with endometriosis. During the follicular phase, ER mRNA levels in the pelvic peritoneum of patients with endometriosis were significantly lower than those of patients with endometriosis. Neither PR nor AR mRNA levels in the pelvic peritoneum of either patient group showed significant cyclic variations throughout the menstrual cycle. A comparison of PR and AR mRNA levels in the pelvic peritoneum of the endometriosis and the nonendometriosis groups revealed no significant differences. CONCLUSIONS: These data indicate a decrease in ER gene expression in the pelvic peritoneum of patients with endometriosis during the follicular phase. This suggests that the possible responsiveness of peritoneal cells to estrogen may be related to the occurrence and/or development of endometriosis.

Adult↗
PubMed1995

Induction of CL100 protein tyrosine phosphatase following transient forebrain ischemia in the rat brain.

Protein tyrosine phosphorylation is thought to play an important role in the regulation of neural function. To elucidate the role that protein tyrosine phosphatases (PTPs) may play in the postischemic brain, PTPs expressed in regions of the rat brain vulnerable to transient forebrain ischemia were examined. With the reverse-transcriptase polymerase chain reaction using degenerate primers, three PTPs, STEP, PTP delta, and SH-PTP2, were identified. They were expressed in the hippocampus 12 h after transient ischemia for 20 min. During the reperfusion period, the mRNA levels of these PTPs were not different from those in sham-operated rats. In contrast, a fourfold increase in the mRNA level of CL100 (3CH134), a PTP that is inducible by oxidative stress, was detected by Northern blotting in the hippocampus and cerebral cortex 1 h after the onset of reperfusion. In situ hybridization histochemistry showed a slight increase in the level of CL100 mRNA in neuronal cells in the hippocampus and cortex of postischemic rats compared to control rats. These findings suggest that PTPs play a role in the normal function of the hippocampus and cerebral cortex and demonstrate that ischemia induced CL100 expression.

Amino Acid Sequence↗
PubMed1995

Expression of leukaemia inhibitory factor (LIF) receptor in human placenta: a possible role for LIF in the growth and differentiation of trophoblasts.

Leukaemia inhibitory factor (LIF) is a cytokine that displays multiple activities in various tissues and is essential for blastocyst implantation in mice. In the human uterus, LIF is expressed in endometrial tissue and the decidua. To elucidate the role it plays, the mRNA levels for two LIF receptor (R) subunits, LIF-R and gp130, were examined in human endometrium, placenta and decidua by Northern blot hybridization. The expression of LIF-R gene was detected in the chorionic villus during the first trimester, in term placenta, and at lower levels in the decidua. The expression of LIF-R gene was not detectable in non-pregnant endometrium. The expression of the gp130 gene was detected in all tissues examined. During pregnancy, there was no significant change in the mRNA concentration of LIF-R in the placenta, while that of gp130 increased after the second trimester. The human choriocarcinoma cell line, BeWo, was found to express LIF-R and gp130. LIF inhibited forskolin-induced human chorionic gonadotrophin (HCG)-beta production by BeWo in a dose-dependent manner, and it ameliorated forskolin-induced growth suppression. These findings suggest that LIF plays a regulatory role in trophoblast growth and differentiation during pregnancy in human placenta.

Base Sequence↗
PubMed1995

Expression of vav proto-oncogene by nonhematopoietic trophoblast cells at the human uteroplacental interface.

Vav is a signal transducing molecule containing SH2 and SH3 domains and a guanine nucleotide releasing factor-like domain. Its expression is thought to be highly specific for hematopoietic cells. Here we describe the expression of vav transcripts in human nonhematopoietic trophoblasts. By northern blotting, expression of 2.8-kb vav mRNA was detected in human decidual, placental, and chorionic villous tissues and in a choriocarcinoma cell line BeWo. By in situ hybridization, vav mRNA was found to be expressed in the cytotrophoblast shell and columns and in the extravillous trophoblasts in the maternal decidua from the first through third trimesters. Vav mRNA was also detected in villous syncytiotrophoblasts during the second and third, but not the first, trimesters. When 1 microM oligodeoxynucleotide antisense to the vav mRNA was added to the medium, growth of BeWo cells was significantly inhibited. These results suggest that vav plays an important role for successful implantation and placental development by regulating development of trophoblasts.

Amino Acid Sequence↗
PubMed1995

Evaluation of cerebral blood flow in patients with idiopathic orthostatic hypotension using Tc-99m HMPAO brain SPECT during postural testing.

To determine whether regional cerebral blood flow (rCBF) would change on standing in patients with idiopathic orthostatic hypotension (IOH), Tc-99m HMPAO SPECT studies were performed during postural testing in five patients with IOH. After 10 minutes of quiet rest on a bed, the patients arose quickly and, at the same time, the radiotracer was injected intravenously. SPECT data were obtained with a ring-type SPECT scanner. Another dose of Tc-99m HMPAO was injected with the subjects in the supine position, and SPECT was performed again. Image subtraction was used to evaluate the change in rCBF caused by postural testing. In all patients, the authors observed a decrease of rCBF ni the frontal cortex and basal ganglia. This preliminary study suggests that changes in rCBF occur in patients with IOH on standing, and Tc-99m HMPAO SPECT performed during postural testing may have an important role in evaluating these changes.

Brain↗
PubMed1995

Non-invasive measurement of brain activity using functional MRI: toward the study of brain response to acupuncture stimulation.

We studied functional MRI in 15 male and 13 female normal volunteers on a clinical MRI system using gradient echo sequence. During the experiments, brain activation was induced by grasping the unilateral hand once or twice a second for motor tasks. A localized increase of MRI signal in the contralateral motor cortex was observed in 17 out of 21 cases (81%) under right hand motor task and 11 out of 21 cases (52%) under left hand motor task. The application of this method may be useful to evaluate brain response to acupuncture.

Acupuncture Therapy↗
PubMed1995

Induction of tissue inhibitor of metalloproteinase 3 gene expression during in vitro decidualization of human endometrial stromal cells.

Endometrial stromal differentiation (decidualization) is essential for implantation of the developing blastocyst. To investigate the process of progesterone (P)-induced decidualization of human endometrial stromal cells (ESC), a complementary DNA library enriched with P-induced genes was constructed from cultured human ESC by subtractive hybridization and the polymerase chain reaction. One of the isolated clones was the complementary DNA for the tissue inhibitor of metalloproteinase-3 (TIMP-3), a recently identified member of the human TIMP family. When human ESC were cultured in the presence of P for 6 days, the induction of TIMP-3 messenger RNA (mRNA) expression was observed by Northern blotting. In contrast, the marked induction of PRL mRNA expression and morphological changes were observed after 9 days of culture. P-induced TIMP-3 mRNA expression was dose dependent, and this induction was inhibited by the antiprogestin RU486. Estrogen did not induce TIMP-3 mRNA expression under similar conditions. In situ hybridization analysis of endometria from nonpregnant women revealed that the TIMP-3 mRNA expression was restricted to predecidualized stromal cells. At the feto-maternal interface, TIMP-3 expression was observed in fetal extravillous trophoblasts that had invaded the maternal decidual tissues as well as in the maternal decidual cells. These findings suggest that TIMP-3 is a sensitive indicator of ESC decidualization, and that the induction of TIMP-3 expression in decidual cells and trophoblasts may be important in the regulation of trophoblast invasion.

Adult↗
PubMed1995

Regulation of sex steroid receptor gene expression by progesterone and testosterone in cultured human endometrial stromal cells.

Progesterone (P) is known to regulate sex steroid receptors in uterine cells. However, its precise regulation at the messenger ribonucleic acid (mRNA) level is unclear. In this study we examined the effects of P and testosterone (T) on the regulation of sex steroid receptors in cultured human endometrial stromal cells (ESC), using the quantitative reverse transcriptase polymerase chain reaction method. We isolated ESC from human endometrial tissues and cultured them with or without P (10(-6) mol/L) or T (10(-8) mol/L) for 9 days. Incubation with P decreased progesterone receptor (PR), estrogen receptor, and androgen receptor mRNA levels in cultured human ESC to 0.56 +/- 0.04-, 0.53 +/- 0.08-, and 0.84 +/- 0.04-fold (mean +/- SE), respectively. T also decreased PR, estrogen receptor, and androgen receptor mRNA levels in cultured human ESC to 0.48 +/- 0.06-, 0.52 +/- 0.05-, and 0.82 +/- 0.04-fold (mean +/- SE), respectively. These decreases by P and T occurred in a dose-dependent manner. We also examined the sex steroid receptor levels in human ESC cultured for 0, 3, 6, and 9 days. The PR mRNA level in ESC without P was increased in a time-dependent manner. This increase was also inhibited by P, and the mRNA level in the presence of P was almost constant throughout the culture period. Our results demonstrated that P or T is a regulator of sex steroid receptors in ESC and that this regulation may influence the responsiveness to P of decidual change in ESC.

Base Sequence↗
PubMed1995

Mechanism of inhibition of carbonyl reductase from rabbit kidney by phenylbutazone.

Phenylbutazone showed significant inhibition against the metabolic reduction of acetohexamide catalyzed by carbonyl reductase purified from rabbit kidney. Thus, the inhibitory effect of phenylbutazone was kinetically examined. Phenylbutazone was a competitive inhibitor for the enzyme with respect to NADPH, whereas it noncompetitively inhibited the enzyme activity with respect to acetohexamide. A fluorescence study revealed that phenylbutazone decreases the binding of NADPH to the free enzyme (apoenzyme). These results suggest that phenylbutazone causes the inhibition of carbonyl reductase by competing with NADPH in its coenzyme-binding domain.

Alcohol Oxidoreductases↗
PubMed1995

Effect of ovarian steroid hormones and the presence of the fetus on oxytocin gene expression in the uterus.

Oxytocin (OT) is a neurohypophysial hormone with potent stimulating activity of the pregnant uterus, but its physiological role in parturition is still unclear. Recently, OT was found to be synthesized in the pregnant uterus, indicating that OT originating from the uterus, not from the posterior pituitary gland, may trigger the onset of labour. In order to define the factors responsible for the induction of uterine OT, the effect of ovarian steroid hormones and conceptus on the induction of OT mRNA in the rat uterus was examined by Northern and dot blot hybridization analysis. OT mRNA in the uterus started to increase on day 14 of pregnancy and showed very high levels at the time of parturition. Uterine OT mRNA was not altered by any steroid treatment, oestradiol-17 beta (0.2 microgram), progesterone (4 mg) or both in combination, for 6 days. The gravid horn of the uterus had 3.6-fold as much OT mRNA as the non-gravid horn on day 21 of pregnancy in hemipregnant rats with one ligated oviduct. The ovarian steroid hormones could not induce accumulation of OT mRNA in the uterus of ovariectomized rats, at least under the conditions used, but the presence of a conceptus may be critical for the very high levels of OT mRNA.

Animals↗