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Biomedical subjects

K Obata

Publications and source records attributed to K Obata.

At least 37 records · Page 2Linked to original sources
PubMed2001

Mutational analysis of BRCA1 and BRCA2 and clinicopathologic analysis of ovarian cancer in 82 ovarian cancer families: two common founder mutations of BRCA1 in Japanese population.

We analyzed genetic alterations in BRCA1 and BRCA2 genes among 82 ovarian cancer families in Japan. The clinical characteristics of BRCA-associated ovarian cancer patients were compared with cases carrying no mutations as well as with population controls. Using a direct sequencing method, 45 of the 82 ovarian cancer families were found to carry BRCA1 or BRCA2 germ-line mutations (40 with BRCA1 and 5 with BRCA2). In 24 independent mutations of BRCA1, 5 recurrent mutations were found and 2 of them, the L63X and Q934X mutations, were detected in seven and eight independent families, respectively. In addition, 16 mutations of BRCA1 and 3 mutations of BRCA2 have never been described previously. In consideration of clinicopathological features, there was a significantly higher proportion of tumors with serous adenocarcinoma and of cases of advanced stages in the BRCA1 or BRCA2 cases than in those of the controls. On the other hand, there were no differences of mean age at diagnosis between patients with BRCA1 or BRCA2 mutation and those of the controls. Our results indicate that the features of BRCA-associated ovarian cancer in Japan appear to be similar to those in Western countries, and the L63X and Q934X mutations of BRCA1 appear to be common founder mutations unique to the Japanese population.

Adolescent↗
PubMed2000

Identification and characterization of 5' extension of mammalian agrin cDNA, the exons and the promoter sequences.

Agrin, which is secreted from motor neurons, is essential for the formation and maintenance of the vertebrate neuromuscular junctions. Here we show the complete N-terminal sequence of the mammalian cDNA required for the expression and secretion as well as the intron/exon structure and the 5'-flanking sequence required for basal promoter activity. The 5'-flanking region and the first exon are extremely GC rich and contain a CpG island. These features may account for hindrance in identification of the 5' end of the cDNA and the promoter region of the mammalian agrin gene.

Agrin↗
PubMed2000

Decreased locomotor activity in mice carrying transgenic Fyn tyrosine kinase.

We found that mice carrying constitutively active Fyn tyrosine kinase show low levels of spontaneous locomotor activity and that this activity increases when the mice are treated with the NMDA receptor antagonist MK-801. These findings indicate that the tyrosine phosphorylation of the NMDA receptors by Fyn participates in the control of locomotor activity.

Animals↗
PubMed2000

Pro-carboxypeptidase R is an acute phase protein in the mouse, whereas carboxypeptidase N is not.

Carboxypeptidase R (EC 3.4.17.20; CPR) and carboxypeptidase N (EC 3. 4.17.3; CPN) cleave carboxyl-terminal arginine and lysine residues from biologically active peptides such as kinins and anaphylatoxins, resulting in regulation of their biological activity. Human proCPR, also known as thrombin-activatable fibrinolysis inhibitor, plasma pro-carboxypeptidase B, and pro-carboxypeptidase U, is a plasma zymogen activated during coagulation. CPN, however, previously termed kininase I and anaphylatoxin inactivator, is present in a stable active form in plasma. We report here the isolation of mouse proCPR and CPN cDNA clones that can induce their respective enzymatic activities in culture supernatants of transiently transfected cells. Potato carboxypeptidase inhibitor can inhibit carboxypeptidase activity in culture medium of mouse proCPR-transfected cells. The expression of proCPR mRNA in murine liver is greatly enhanced following LPS injection, whereas CPN mRNA expression remains unaffected. Furthermore, the CPR activity in plasma increased 2-fold at 24 h after LPS treatment. Therefore, proCPR can be considered a type of acute phase protein, whereas CPN is not. An increase in CPR activity may facilitate rapid inactivation of inflammatory mediators generated at the site of Gram-negative bacterial infection and may consequently prevent septic shock. In view of the ability of proCPR to also inhibit fibrinolysis, an excess of proCPR induced by LPS may contribute to hypofibrinolysis in patients suffering from disseminated intravascular coagulation caused by sepsis.

Acute-Phase Proteins↗
PubMed2000

Postnatal development of a GABA deficit and disturbance of neural functions in mice lacking GAD65.

The 65-kDa isoform of glutamic acid decarboxylase (GAD65) is believed to play an essential role for GABA synthesis in the central nervous system. Using mice with targeted disruption of the GAD65 gene (GAD65(-/-) mice) we investigated the contribution of GAD65 to GABA synthesis in different brain areas during postnatal development and in adulthood. In the amygdala, hypothalamus and parietal cortex of GAD65(+/+) mice an increase of GABA levels was observed during postnatal development, most prominently between the first and second month after birth. This increase appeared to be dependent on GAD65, as it was delayed by 2 months in GAD65(+/-) mice and was not observed in GAD65(-/-) mice. Likely as a consequence of their GABA deficit, adult GAD65(-/-) mice showed a largely abnormal neural activity with frequent paroxysmal discharges and spontaneous seizures. They furthermore displayed increased anxiety-like behaviour in a light/dark avoidance test and reduced intermale aggression, as well as a reduced forced-swimming-induced immobility indicative of an antidepressant-like behavioural change. Adult GAD65(+/-) mice did not show behavioural disturbances except for a reduced aggressive behaviour that was comparable to that in GAD65(-/-) mice. We conclude that GAD65-mediated GABA synthesis may be crucially involved in control of emotional behaviour and indispensable for a tonic inhibition that prevents the development of hyperexcitability in the maturating central nervous system. Aggressive, and possibly other social behaviour may be especially prone to regulation through GAD65-mediated GABA synthesis.

Age Factors↗
PubMed2000

A case of biliary atresia with cystic dilatation of the extrahepatic bile duct and polysplenia syndrome.

A 79-day-old girl presented with jaundice and acholia. Laboratory findings disclosed elevated levels of bilirubin, transaminases, and gamma-glutamyl transferase. A chest X-ray film showed dextrocardia. A computed tomographic scan revealed a cystic mass at the porta hepatis, multiple spleens in the right side of the abdomen, and absence of the inferior vena cava. Under the diagnosis of biliary atresia (BA) (I-cyst) associated with polysplenia syndrome, a hepatic portojejunostomy was performed at 80 days of age. The postoperative course was uneventful, and the jaundice cleared. Although the occurrence of associated anomalies in BA is rare, polysplenia is most commonly seen, and its incidence is reported to be 2% to 10%. Patients with BA and polysplenia usually have a poor prognosis, however, this patient may have a good prognosis due to uneventful recovery from the jaundice.

Bile Duct Diseases↗
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↗