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K Obata

Publications and source records attributed to K Obata.

At least 55 records · Page 3Linked to original sources
PubMed2000

Recovery of emotional behaviour in neural cell adhesion molecule (NCAM) null mutant mice through transgenic expression of NCAM180.

In the present study we further investigate functions of the neural cell adhesion molecule (NCAM) in the mature central nervous system and its implications for animal behaviour. To this end we generated transgenic mice expressing the major NCAM isoform with the largest cytoplasmic domain, NCAM180, under control of a promoter for the small form neurofilament gene. Transgenic mice were also bred with mice deficient in endogenous NCAM (Ncam-/- mice) so that effects of NCAM180 could be analysed in the presence and absence of endogenous NCAM. While overexpression of transgenic NCAM180 was without apparent behavioural or morphological effect, its expression in Ncam-/- mice counteracted NCAM ablation-induced aggressive, anxiety-like and antidepressant-like behaviour. It furthermore prevented a hypersensitivity of Ncam-/- mice to the anxiolytic serotonin1A (5-HT1A) receptor agonist buspirone. Such recovery of emotional behaviour and behavioural 5-HT1A response occurred in spite of misdevelopment of the olfactory bulb and hippocampus that is characteristic of Ncam-/- mice, and without an apparent change in the expression of 5-HT1A binding sites in the brain. Hippocampus- and amygdala-dependent learning, though disturbed in Ncam-/- mice, remained unaffected by the transgenic NCAM180. We suggest an involvement of NCAM180-mediated cell recognition processes in the serotonergic modulation of emotional behaviour in adult mice.

Aggression↗
PubMed2000

Structure of the mouse glutamate decarboxylase 65 gene and its promoter: preferential expression of its promoter in the GABAergic neurons of transgenic mice.

GABA is synthesized by glutamate decarboxylase (GAD), which has two forms, GAD65 and GAD67. To elucidate the molecular mechanisms of mouse GAD65 (mGAD65) gene expression, we isolated and characterized the mGAD65 gene. The mGAD65 gene was found to be divided into 16 exons and spread over 75 kb. The sequence of the first exon and the 5'-flanking region indicated the presence of potential neuron-specific cis-regulatory elements. We used transgenic mice to examine the expression pattern conferred by a 9.2-kb promoter-proximal DNA fragment of the mGAD65 gene fused to the bacterial lacZ reporter gene. Transgenic mice showed high beta-galactosidase activity specifically in brain and testis. They also showed characteristic patterns of transgene expression in olfactory bulb, cerebellar cortex, and spinal cord, a similar expression pattern to that of endogenous mGAD65. However, no transgene expression was observed in the ventral thalamus or hypothalamus, in which high mGAD65 gene expression levels have been observed. These results suggest that the 9.2-kb DNA fragment of the mGAD65 gene is associated with its tissue-specific expression and its targeted expression in GABAergic neurons of specific brain regions but that additional regulatory elements are necessary to obtain fully correct expression.

Amino Acid Sequence↗
PubMed2000

An ileostomy at the aganglionic ileum for total colon aganglionosis.

For the initial management of total colon aganglionosis (TCA), an ileostomy is usually created at the distal end of the ganglionic bowel, which is associated with profuse diarrhea resulting in a water and electrolyte imbalance as well as malnutrition during the ileostomy period. An ileostomy at the aganglionic ileum several centimeters toward the anal side of the transition for TCA is thus expected to cause bowel retention without any bowel obstruction and to facilitate water reabsorption in the small bowel. We performed this procedure in 2 babies with TCA. The length of the aganglionic ileum was 50 cm and 10 cm, respectively. The ileostomies were made 5 cm distal to the transition at 1 month and 1 day after birth, respectively. Oral feedings were well tolerated, resulting in adequate weight gain and the stools were semisolid during the ileostomy periods. Definitive operations using the Duhamel procedure with a right colon patch graft without the creation of a new ileostomy were successfully performed at 7 and 3 months of age, respectively. The postoperative courses were satisfactory. An ileostomy at the aganglionic ileum appears to be the method of choice as initial management for patients with TCA.

Female↗
PubMed2000

Co-administration of furosemide augments tacrolimus-induced impairment in kidney function in rats.

Sodium-depletion in rats reproduces functional and morphological tacrolimus nephrotoxicity observed in man. Potent diuretics induce sodium-depletion. Our objective was to determine the effect of a loop diuretic furosemide on tacrolimus-mediated functional and pathological impairment of the kidney in rats. Sprague-Dawley rats were divided into four groups; group 1, rats received vehicle (saline) only; group 2, rats were treated with tacrolimus (1 mg/kg body weight) and furosemide (5 mg/kg body weight); group 3, rats were treated with tacrolimus alone; and group 4, rats were treated with furosemide (5 mg/kg body weight) alone. On day 28, tail blood pressure was measured and the rats were placed in metabolic cages for urine collection. After 24 hr the rats were sacrificed. Tacrolimus alone tended to cause growth retardation, hypotension, hypomagnesemia and a rise in blood urea nitrogen. Furosemide co-administration enhanced the effects of tacrolimus on hypotension, hypomagnesemia and a rise in blood urea nitrogen. The renal histology characterized by cytoplasmic vacuolization of the proximal tubules was not different between the rats treated with both tacrolimus and furosemide and the rats treated with tacrolimus alone. A strong immunostaining for FKBP-12, a tacrolimus-binding protein, was observed in the medulla of the kidneys of rats treated with tacrolimus either with or without furosemide. These results indicate that furosemide further augments tacrolimus induced impairment in kidney function, and that furosemide should be used with discretion in patients on tacrolimus therapy.

Animals↗
PubMed2000

Changes in mint1, a novel synaptic protein, after transient global ischemia in mouse hippocampus.

Mints (munc18-interacting proteins) are novel multimodular adapter proteins in membrane transport and organization. Mint1, a neuronal isoform, is involved in synaptic vesicle exocytosis. Its potential effects on development of ischemic damage to neurons have not yet been evaluated. The authors examined changes in mint1 and other synaptic proteins by immunohistochemistry after transient global ischemia in mouse hippocampus. In sham-ischemic mice, immunoreactivity for mint1 was rich in fibers projecting from the entorhinal cortex to the hippocampus and in the mossy fibers linking the granule cells of the dentate gyrus to CA3 pyramidal neurons. Munc18-1, a binding partner of mint1, was distributed uniformly throughout the hippocampus, and synaptophysin 2, a synaptic vesicle protein, was localized mainly in mossy fibers. After transient global ischemia, mint1 immunoreactivity in mossy fibers was dramatically decreased at 1 day of reperfusion but actually showed enhancement at 3 days. However, munc18-1 and synaptophysin 2 were substantially expressed in the same region throughout the reperfusion period. These findings suggest that mint1 participates in neuronal transmission along the excitatory pathway linking the entorhinal cortex to CA3 in the hippocampus. Because mint1 was transiently decreased in the mossy fiber projection after ischemia, functional impairment of neuronal transmission in the projection from the dentate gyrus to CA3 pyramidal neurons might be involved in delayed neuronal death.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Matrix metalloproteinases and tissue inhibitors of metalloproteinases in synovial fluids from patients with rheumatoid arthritis or osteoarthritis.

OBJECTIVE: Matrix metalloproteinases (MMPs) are expressed in joint tissues of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). The objective of this study was to define the steady state levels of seven different MMPs and two tissue inhibitors of metalloproteinases (TIMPs) as well as the potential metalloproteinase activity in the synovial fluid (SF) to provide more insight into the role of MMPs in cartilage destruction in RA and OA. METHODS: Levels of MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-13, TIMP-1, and TIMP-2 in SF aspirated from knee joints of 97 patients with RA and 103 patients with OA were measured by the corresponding one step sandwich enzyme immunoassays. Proteolytic activity of MMPs in these SFs was examined in an assay using [(3)H]carboxymethylated transferrin substrate in the presence of inhibitors of serine and cysteine proteinases after activation with p-aminophenylmercuric acetate (APMA). Destruction of RA knee joints was radiographically evaluated. RESULTS: Levels of MMP-1, MMP-2, MMP-3, MMP-8, and MMP-9 were significantly higher in RA SF than in OA SF. MMP-7 and MMP-13 were detectable in more than 45% of RA SFs and in less than 20% of OA SFs, respectively. Among the MMPs examined, MMP-3 levels were extremely high compared with those of other MMPs. Direct correlations were seen between the levels of MMP-1 and MMP-3 and between those of MMP-8 and MMP-9 in RA SF. Although the levels of MMP-1 and MMP-3 increased even in the early stage of RA, those of MMP-8 and MMP-9 were low in the early stage and increased with the progression of RA. Molar ratios of the total amounts of the MMPs to those of the TIMPs were 5.2-fold higher in patients with RA than in OA, which was significant. APMA-activated metalloproteinase activity in SF showed a similar result, and a direct correlation was seen between the molar ratios and the activity in RA SF. CONCLUSIONS: Our results show that high levels of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, and TIMP-1 are present in RA SF and suggest that once these MMPs are fully activated, they have an imbalance against TIMPs, which may contribute to the cartilage destruction in RA.

Adult↗
PubMed2000

Common genetic changes between endometriosis and ovarian cancer.

We analyzed 81 ovarian cancers for loss of heterozygosity (LOH) on 10q23 and for mutations in PTEN. LOH was common among the endometrioid (43%) and serous (28%) cancers, but was infrequent among the other histological subtypes. Somatic PTEN mutations were detected in seven (21%) endometrioid cancers and the mutation in all informative cases was accompanied by loss of the wild-type allele. One mucinous cancer without 10q23 LOH was shown to harbor two somatic PTEN mutations. Frequent LOH was observed on chromosome 6q (60.0%) and chromosome 10q (40.0%) in ovarian atypical endometriosis, but no PTEN mutations were observed. These findings support the hypothesis that endometrioid and clear cell ovarian carcinomas may arise through malignant transformation of endometriotic lesions.

Adenocarcinoma, Clear Cell↗
PubMed2000

Foods and nutrients in relation to bladder cancer risk: a case-control study in Aichi Prefecture, Central Japan.

To elucidate the role of diet in the etiology of bladder cancer, we conducted a case-control study from 1996 to 1999 in Aichi Prefecture, Central Japan. Cases were patients newly diagnosed with bladder cancer, and one hospital control was selected for each case, matching gender, age, and hospital. A well-validated food frequency questionnaire was adopted to estimate intakes of nutrients and food groups. Odds ratios (ORs) adjusted for smoking and occupational history were computed using conditional logistic models. The analyses based on 297 cases and 295 controls revealed the following. 1) The more the intake of milk and dairy products, the lower the OR; the ORs across quartiles in all subjects were 1.02, 0.73, and 0.52. Fruit intake was negatively associated with the risk, particularly in men (ORs across quartiles = 0.76, 0.77, and 0.52). Green-yellow vegetables were associated with a decreased risk in the highest quartile of consumption in men (OR = 0.57). 2) Dietary intakes of retinol and saturated fatty acids were related to a reduced risk in all subjects (ORs across quartiles = 0.75, 0.54, and 0.66 and 0.55, 0.54, and 0.60, respectively). Monounsaturated fatty acids had an inverse association with bladder cancer risk in men.

Adult↗
PubMed1999

Norbin, a neurite-outgrowth-related protein, is a cytosolic protein localized in the somatodendritic region of neurons and distributed prominently in dendritic outgrowth in Purkinje cells.

Distribution of norbin protein in rats was characterized by immunohistochemical study. It was distributed not only in whole brain but also in peripheral nervous system. The protein was localized in the somata, except for nuclei, and dendrites of neurons. Subcellular fractionation revealed that norbin is a cytosolic protein. Prominent distribution was observed in dendrites of dendritic outgrowth in Purkinje cells. Norbin should play a role in somatodendritic functions of neurons.

Animals↗
PubMed1999

An AciI polymorphism in the 3' untranslated region of the human phosphomannomutase 2 (PMM2) gene.

We found an AciI polymorphism in the 3' untranslated region of the phosphomannomutase 2 (PMM2) gene located at 16p13. A G-to-C transition at nucleotide position 96 bp downstream from the PMM2 stop codon was detected in polymerase chain reaction (PCR) products after AciI digestion. The heterozygosity of the polymorphic alleles was 0.375 in a Japanese population. This polymorphism is useful for genetic analysis in patients with carbohydrate-deficient glycoprotein syndromes, of which there are four subtypes.

3' Untranslated Regions↗
PubMed1999

Development of the GABA system in organotypic culture of hippocampal and cerebellar slices from a 67-kDa isoform of glutamic acid decarboxylase (GAD67)-deficient mice.

Mice lacking glutamic acid decarboxylase 67kDa (GAD67) are born with much reduced GABA contents but do not survive after birth. To estimate the subsequent development of GAD67-deficient neural tissue, the hippocampal and cerebellar slices were prepared while the mice were alive, and subjected to organotypic culture. Although GABA contents were initially less than 5%, they were markedly increased, and GABA-containing fiber networks were well developed during the culture, indicating that GAD65, the other GAD isoform, largely compensates for the lack of GAD67. Cerebellar Purkinje cells developed similarly in culture.

Animals↗
PubMed1999

GABA and histogenesis in fetal and neonatal mouse brain lacking both the isoforms of glutamic acid decarboxylase.

Recent in vitro investigations have suggested that GABA is involved in the development of the mammalian central nervous system. To evaluate the roles of GABA in neurogenesis in vivo, we generated mice lacking both the isoforms of glutamic acid decarboxylase (GAD), GAD65 and GAD67, by mating GAD65- and GAD67-mutant mice generated by homologous recombination in this laboratory. Similar to GAD67-deficient mice, the GAD65/67-deficient mice did not survive after birth because of cleft palate. We thus analyzed these mice at the fetal and newborn stages. GABA was scarcely detectable in the GAD65/67-deficient brains, indicating that the GAD-independent GABA synthetic pathway was not active. The activity of ornithine decarboxylase, which is possibly involved in such a pathway, did not increase with the GAD deficiency. Histological and immunohistochemical studies of the GAD65/67-deficient brain did not reveal any discernible disorders of histogenesis. The discrepancy between the results of previous in vitro investigations, performed mostly on rat tissue, and those of the present analysis on mutant mice may be attributed to the different species used or to the possibility that other mediators can compensate for GABA functions in vivo.

Animals↗
PubMed1999

Synaptic localization of the 67,000 mol. wt isoform of glutamate decarboxylase and transmitter function of GABA in the mouse cerebellum lacking the 65,000 mol. wt isoform.

Subcellular localization of the 67,000 mol. wt isoform of glutamate decarboxylase and neurotransmitter function of GABA were investigated in the cerebellum of the mice lacking the 65,000 mol. wt isoform of glutamate decarboxylase. The GABA content decreased by 25% in the cerebellum. Putative GABA-releasing terminals from basket/stellate and Golgi cells were immunostained with glutamate decarboxylase-67 antibody. Basket cell-derived inhibitory postsynaptic currents in Purkinje cells and the high potassium-induced release of GABA were not significantly affected. Although previous investigations have suggested that glutamate decarboxylase-65 is mainly involved in transmitter synthesis and that glutamate decarboxylase-67 is transported to the nerve terminals only after association with glutamate decarboxylase-65, the present results indicate that glutamate decarboxylase-67 is independently concentrated in the nerve terminals and provides GABA for synaptic transmission in the absence of glutamate decarboxylase-65.

Animals↗
PubMed1999

Urinary nuclear matrix protein 22 as a new marker for the screening of urothelial cancer in patients with microscopic hematuria.

PURPOSE: The aim of the present study was to determine the clinical usefulness of nuclear matrix protein 22 (NMP22) as a new urinary marker for the screening of urothelial cancer in patients with microscopic hematuria, especially in comparison with that of voided urine cytology. METHODS: Patients with microscopic hematuria detected at a health examination, who were advised by a consulted urologist to have a cystoscopical examination, were asked to enter this study. Urine samples were collected before cystoscopy and divided into two portions for NMP22 test and voided urine cytology. RESULTS: Of the 309 patients with microscopic hematuria, 22 cases (7.1%) of urothelial cancer and one case of prostate cancer were detected. For the other cases, 128 (41.4%) were of benign diseases and 158 (51.1%) were designated as having no evidence of disease (NED). The median NMP22 values for urothelial cancer, other diseases and NED were 35.5, 6.7 and 6.0 U/mL, respectively, with 95% confidence intervals of 19.9-228.2, 5.1-9.3 and 5.4-7.2, respectively. The sensitivity of the NMP22 test for urothelial cancer was 90.9% (20/22), whereas the sensitivity of voided urine cytology was only 54.5% (12/22). CONCLUSIONS: The present study indicates that urinary NMP22 is a useful tool for the screening of urothelial cancer in patients with microscopic hematuria.

Adult↗
PubMed1999

Enhanced synaptic transmission and reduced threshold for LTP induction in fyn-transgenic mice.

To elucidate the physiological role of Fyn, we analysed the properties of synaptic transmission and synaptic plasticity in hippocampal slices of mice overexpressing either wild-type Fyn (w-Fyn) or its constitutively active mutant (m-Fyn). These fyn-transgenes were driven by the calcium/calmodulin-dependent protein kinase II alpha promoter which turned on in the forebrain neurons including hippocampal pyramidal cells and in late neural development. In the hippocampal slices expressing m-Fyn the paired-pulse facilitation was reduced and the basal synaptic transmission was enhanced. A weak theta-burst stimulation, which was subthreshold for the induction of long-term potentiation (LTP) in control slices, elicited LTP in CA1 region of the slices expressing m-Fyn. When a relatively strong stimulation was applied, the magnitude of LTP in m-Fyn slices was similar to that in control slices. By contrast, the basal synaptic transmission and the threshold for the induction of LTP were not altered in the slices overexpressing wild-type Fyn. To examine the effect of expression of m-Fyn on GABAergic inhibitory system, we applied bicuculline, a GABAA receptor blocker, to the hippocampal slices. The ability of bicuculline to enhance excitatory postsynaptic potentials was attenuated in slices expressing m-Fyn, suggesting that the overexpression of m-Fyn reduced the GABAergic inhibition. The enhancement of synaptic transmission and the reduction of GABAergic inhibition may contribute to the enhanced seizure susceptibility in the mice expressing m-Fyn. Thus, these results suggest that regulation of Fyn tyrosine kinase activity is important for both synaptic transmission and plasticity.

Animals↗