Biomedical subjects

H Nawata

Publications and source records attributed to H Nawata.

At least 235 records · Page 13Linked to original sources

PubMed1996

Androgen insensitivity syndrome due to new mutations in the DNA-binding domain of the androgen receptor.

Androgen insensitivity syndrome (AIS) is associated with a wide range of quantitative or qualitative defects in the androgen receptor (AR). In some patients with AIS, however, no defects are detectable in the ligand-binding properties of the AR. We have analyzed the ARs of two unrelated patients with this category (termed 'receptor-positive type') of AIS. Sequence analysis of these patients' AR gene revealed single amino acid substitutions (579Cys(TGC)-->Phe(TTC) and 582Phe(TTC)-->Tyr(TAC)) in exon B encoding the first zinc finger of the DNA-binding domain of the AR. These mutations have not been previously reported. Moreover, cotransfection assays and mobility shift assays revealed that these patients' mutant ARs had defective transcriptional activity of the target gene because of impaired DNA-binding ability to the androgen-responsive element. These findings strongly indicate that these mutations are responsible for the pathogenesis of AIS in these patients.

Adult↗

PubMed1996

Autoregulatory loop in the regulation of the mammalian ftz-f1 gene.

The mammalian ftz-f1 (mftz-f1) gene encoding Ad4BP/SF-1 has been demonstrated to be essential for the development of adrenal and gonadal glands. In a previous study, we identified an E box as the transcriptional element in the 5'-upstream region of the rat mftz-f1 gene. In the present study, we found a steroidogenic cell-specific transcriptional element in the first intron of the gene. Gel mobility shift and DNase I footprint analyses clearly revealed that Ad4BP itself binds to the element (Ad4 site). This finding was further supported by the positive effect of an Ad4BP expression vector on the transcription and by the significant decrease in the transcription caused by nucleotide substitutions within the Ad4 site. Similar loss was also caused by substitutions in the E box, indicating that the two elements are essential for the full transcriptional activity of the gene. DNase I hypersensitivity assays revealed that the chromatin structure around the Ad4 site and the E box was "open up" in the adrenal glands and Y-1 cells, whereas "closed down" in the liver. These observations indicated that the mftz-f1 gene is controlled by the autoregulatory loop in the steroidogenic tissues. The autoregulatory mechanism seems to be necessary to keep the mftz-f1 gene activated and thus maintain the tissues differentiated.

Animals↗

PubMed1996

Clinical implications of microsatellite instability in colorectal cancers.

BACKGROUND: Microsatellite instability (MI) has been reported in some sporadic colon tumors and in cases of hereditary nonpolyposis colorectal cancer (HNPCC). The criteria for HNPCC have not been fully defined, and clinical criteria are used to identify as many HNPCC patients as possible. To clarify the conformity of these criteria with the identification of eligible HNPCC cases, we analyzed MI in HNPCC patients diagnosed using clinical criteria. METHODS: Genomic DNA was extracted from surgical specimens of 56 colorectal cancers, including 36 from patients diagnosed with HNPCC using the clinical criteria. We analyzed four microsatellite loci using 32P-labeled primers. RESULTS: Among HNPCC patients diagnosed using clinical criteria, patients who were positive for MI accounted for 62% of Group A (a confirmed group) and 35% of Group B (a high risk group); only 5% of randomly selected colorectal cancer patients (Group C), were positive for MI. Furthermore, MI-positive tumors were found in patients who had a tendency for tumors to involve the right side of the colon, an association with cancers in other organs, a lower incidence of p53 protein positivity, and a higher proportion of poorly differentiated cancers. CONCLUSIONS: The presence of MI, in concert with modified clinical criteria, may identify legitimate cases of HNPCC in patients who might otherwise be excluded by the minimum criteria.

Age of Onset↗

PubMed1996

Expression of EVI1 and the Retinoblastoma genes in acute myelogenous leukemia with t(3;13)(q26;q13-14).

The EVI1 DNA-binding protein gene on chromosome 3q26 has been reported to be activated in some leukemia cells with alterations in 3q26. We present an acute myelogenous leukemia (AML) patient with a rare chromosomal translocation, t(3;13)(q26.2;q13-14). By reverse transcription-polymerase chain reaction, we detected active transcription of the EVI1 gene in the patient's leukemia cells. The retinoblastoma susceptibility (Rb) gene, a tumor-suppressor gene, is located at chromosome 13ql4 and is within the other translocation breakpoint in this patient. The expression of the Rb gene product was found to be substantially decreased in the patient's leukemia cells by Western blotting. Southern blot analysis, however, revealed no gross abnormalities of the Rb gene. Although it is unlikely that the Rb gene is directly involved in this translocation, the loss of the Rb gene product combined with the activation of the EVI1 gene may have led to the development of leukemia.

Asian People↗

PubMed1996

Natural killing activities in chronic liver diseases and hepatocellular carcinoma.

Previously we proposed a new analysis of natural killing activity, for comparison, employing an individual effector/target cell ratio according to the peripheral number of effector cells. Using this analysis, we studied natural killing activities in chronic liver diseases and hepatocellular carcinoma (HCC). The activity in chronic persistent hepatitis remained nearly at the level of the nonactivated state, but that was significantly elevated in chronic active hepatitis. The activity in liver cirrhosis (LC) of Child's A or B grade was at the level of a nonactivated or reduced-activity state, while LC patients with impaired general conditions showed significantly elevated activities. In HCC, each of which was accompanied by LC in our cases, the activity appeared to be associated with the progression of HCC. Thus, natural killing activity showed a close relationship with the condition of chronic liver diseases.

Adolescent↗

PubMed1996

Direct inhibitory effect of corticotropin releasing hormone on isolated caecal circular smooth muscle cells of guinea pig via adenylate cyclase system.

Smooth muscle cells isolated separately from the caecal circular smooth muscle layer of the guinea pig were used to investigate whether corticotropin releasing hormone (CRH) can inhibit directly the contraction produced by cholecystokinin octapeptide (CCK-8). In addition, the role of adenylate cyclase and guanylate cyclase in the direct inhibitory effect of CRH was examined. CRH inhibited the contractile response produced by 10(-9)M CCK-8 in a concentration-dependent manner, with an IC50 value of 0.16nM. An inhibitor of particulate guanylate cyclase and an inhibitor of soluble guanylate cyclase had no significant effect of the relaxation produced by CRH. In contrast, an inhibitor of adenylate cyclase and an inhibitor of cAMP-dependent protein kinase significantly inhibited the relaxation produced by CRH. This is the first report demonstrating the direct inhibitory action of CRH on the isolated caecal smooth muscle cells via adenylate cyclase system.

Adenylyl Cyclase Inhibitors↗

PubMed1996

The effects of pravastatin, an HMG-CoA reductase inhibitor, on cell viability and DNA production of rat hepatocytes.

Some metabolites and products of mevalonic acid are involved in various cellular functions, particularly cell growth. In this study, we assessed the effects of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on cell viability and DNA production of rat hepatocytes stimulated with epidermal growth factor. Pravastatin (0.1 to 10 microM) induced a dose-dependent reduction of DNA synthesis, assessed by 3H-thymidine incorporation in rat hepatocytes, which dropped by approximately 60% at a drug concentration of 10 microM. This suppression of DNA synthesis was nearly reversed by exogenous mevalonic acid, but was not prevented by purified low-density lipoprotein cholesterol. Pravastatin did not affect the mitochondrial reduction of Dimethylthiazolyl-diphenyl-tetrazolium bromide (MTT), but induced apoptotic change as assessed by nuclear chromatin staining. This apoptotic change was also reversed by exogenous mevalonic acid. These results indicate that mevalonic acid metabolites are necessary for DNA synthesis by rat hepatocytes stimulated by epidermal growth factor and for suppressing cell death.

Adenine↗

PubMed1996

Effect of beraprost sodium on response to tests of autonomic control of heart rate in patients with diabetes mellitus.

Prostaglandin I2 (PGI2) produces greater vasodilating and anti-platelet effects than PGE1, but is chemically unstable. Beraprost sodium, a stable analog of PGI2, was given orally, 120 micrograms daily for 12 weeks, to 15 patients with non-insulin-dependent diabetes mellitus to evaluate its effect on autonomic function. The effect of the drug on heart rate (HR) was evaluated in response to standing, rest, and deep breathing. The drug had a significant effect on HR in response to standing, but not during rest or deep breathing. Nine patients without preproliferative or proliferative retinopathy, and in whom factor analysis suggested the drug was effective with respect to autonomic nerve dysfunction, showed a significant improvement in their response to the three tests after beraprost administration for 12 weeks. Blood glucose was unaffected. Results thus indicate that beraprost sodium alleviates autonomic nerve dysfunction in diabetic patients in the absence of severe retinopathy.

Adult↗

PubMed1996

Augmented expression of LCK message directed from the downstream promoter in human colorectal cancer specimens.

Lck protein is expressed in some colon carcinoma cell lines but its expression in colon cancer cells in vivo has not been clarified. LCK transcription is regulated from two distinct promoters and initiated exclusively from the downstream promoter in colon carcinoma cell lines in contrast to peripheral lymphocytes. We investigated the expression of the downstream promoter-initiated LCK transcript in 18 colorectal primary cancer and normal mucosae, and two hepatic metastases, using a RNase protection assay with the EcoRI-BglII fragment of human LCK cDNA, YT16. In normal tissues, only traces of the LCK transcript were detected. The expression of the LCK transcript was augmented in 3/18 cancer specimens. The relative level of the LCK transcript in the cancer tissue compared to the average value of normal adjacent tissue was 10-60 in 3 cases, and 3-10 in 7 cases. One hepatic metastasis expressed more LCK message than the primary lesion. Our results indicate that the LCK message is strongly expressed in some colorectal cancers.

Adult↗

PubMed1996

Infective endocarditis caused by Campylobacter fetus after allogeneic tooth transplantation: a case report.

A patient developed infective endocarditis caused by Campylobacter fetus. He gave a history of recent dental extraction and allogeneic tooth transplantation. He was treated with various antibodies to which the organism was said to be sensitive, but it was not until the transplanted tooth was removed that he started to improve. The mode of infection was thought to be blood borne through the open tooth socket from the raw chicken that he ate regularly.

Animals↗

PubMed1996

Follicle stimulating hormone-beta subunit gene is expressed in parallel with a transcription factor Ad4BP/SF-1 in human pituitary adenomas.

OBJECTIVES: A transcription factor Ad4BP/SF-1 is implicated in the differentiation of gonadotrophs in the pituitary gland, but it is not known whether human pituitary cells express this factor. The present study aimed to disclose (1) whether human pituitary adenomas express Ad4BP/SF-1, and (2) if this is the case, what kinds of adenoma express the factor. MATERIAL: Total RNA was extracted from 23 pituitary adenomas obtained by transsphenoidal surgery, and subjected to Northern blot analyses using cDNAs of bovine Ad4BP/SF-1, porcine FSH-beta, LH-beta and glycoprotein hormone-alpha (GPH-alpha) subunts as radiolabelled probes. These adenomas included 13 clinically non-functioning adenomas, 1 GH/PRL-producing adenoma, 6 GH-producing adenomas, 2 PRL-producing adenomas and 1 ACTH-producing adenoma. RESULTS: The expression of Ad4BP/SF-1 exactly coincided with the expression of FSH-beta. Thus 5 out of 13 clinically non-functioning adenomas expressed Ad4BP/SF-1 and only these 5 adenomas expressed FSH-beta. Interestingly, only one of the GH-producing adenomas also expressed Ad4BP/SF-1 as well as FSH-beta. GPH-alpha was expressed in 4 non-functioning adenomas and 2 hormonally functioning adenomas, but did not necessarily coincide with Ad4BP/SF-1 expression. None of the 23 adenomas we tested expressed LH-beta, probably because LH-beta-producing adenomas are rather rare. CONCLUSIONS: The expression of FSH-beta was parallel with Ad4BP/SF-1 expression, indicating that the expression of Ad4BP/SF-1 is restricted to cells derived from gonadotroph lineages in human pituitary adenomas.

Adenoma↗

PubMed1996

A hamster temperature-sensitive G1 mutant, tsBN250 has a single point mutation in histidyl-tRNA synthetase that inhibits an accumulation of cyclin D1.

BACKGROUND: We have previously isolated a series of temperature-sensitive mutants for cell-proliferation from the BHK21 cell line, derived from the golden hamster. These mutants proliferate at 33.5 degrees C, the permissive temperature, but not at 39.5 degrees C the restrictive temperature. Using DNA-mediated gene transfer, human genes complementing these ts mutants were cloned. RESULTS: At 39.5 degrees C the tsBN250 cell line, a temperature-sensitive mutant of the BHK21 cell line, had a defect in the G1 phase, but not in the S phase. The human gene complementing tsBN250 cells was found to encode histidyl-tRNA synthetase. Indeed, the tsBN250 cell line had a single base change--guanine to adenine at the second position of the 362nd codon of hamster histidyl-tRNA-synthetase, converting arginine to histidine. Following release from serum starvation, cyclin E, but not cyclin D1, was accumulated, while, at 39.5 degrees C, the mRNA of cyclin D1 was normally expressed in tsBN250 cells. A similar inhibition of cyclin D1 accumulation was observed in another ts mutant, tsBN269, which has a single point mutation in lysyl-tRNA synthetase. Overexpression of cyclin D1 enabled tsBN250 cells to enter the S phase. CONCLUSION: tsBN250 cells have a single point mutation in histidyl tRNA synthetase that causes a loss of histidyl-tRNA synthetase activity which in turn reduces the content of cyclin D1, but not of cyclin E, thereby resulting in G1 arrest.

Amino Acid Sequence↗

PubMed1996

Isolation and characterization of the human chromosomal gene for prostacyclin-stimulating factor.

Prostacyclin-stimulating factor (PSF) is a protein which acts on vascular endothelial cells and stimulates the production of prostacyclin. Recently, we were able to purify PSF from the conditioned medium of cultured human diploid fibroblasts and clone PSF cDNA. In this study, we screened a human genomic library and isolated genomic clones to determine the structure of the human chromosomal PSF gene. By determining the nucleotide sequence and transcription initiation site of this gene, we found that it comprises 5 exons and 4 introns. Southern hybridization analysis indicated the presence of a single copy of the PSF gene per haploid set of chromosomes. The 300 bp upstream of the transcription initiation site had a very high GC content, and 7 binding sites for the transcription regulating factor Sp1 were present.

Base Sequence↗

PubMed1996

Measurement of pancreatic blood flow with the intraductal electrode method of the hydrogen clearance technique in acute pancreatitis in rats.

Measurement of local pancreatic blood flow during acute pancreatitis is thought of as being technically difficult in smaller animals. In this study, we first employed an intraductal electrode method of the hydrogen clearance technique for measurement of changes in local pancreatic blood flow in two types of acute pancreatitis in rats, then compared this method with an interstitial electrode method that has been used in rats. There was a very close correlation between these methods (r = 0.998, p < 0.001). The intraductal electrode method was easily performed and caused minimal tissue damage.

Acute Disease↗

PubMed1996

E-cadherin gene mutations in signet ring cell carcinoma of the stomach.

To clarify the significance of E-cadherin gene alterations in the development of diffuse-type adenocarcinoma of the stomach, we analyzed mutations of the E-cadherin gene using the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) method followed by direct sequencing. Twenty-two signet ring cell carcinomas of the stomach (10 intramucosal and 12 advanced cancers) were examined. Genomic DNA was extracted separately from cancerous and non-cancerous tissues and PCR-SSCP analysis was performed on exons 5 to 9 and the adjacent 30- to 40-base-pair intron sequences of the E-cadherin gene. Mobility shifts were found in 2 of the 10 intramucosal cancers. In 2 of the 12 advanced cancers, abnormalities of the E-cadherin gene were observed in intramucosal lesions as well as in deeply invaded areas. These results indicated that E-cadherin gene mutations are an early event in the development of signet ring cell carcinoma of the stomach. Direct sequencing revealed that the locations of mutations of the E-cadherin gene included the branch point sequence in the intron which is responsible for RNA splicing. Reverse transcriptase-PCR demonstrated aberrant RNA splicing in a case with a branch point mutation, suggesting that branch point mutations play an important role in functional modifications of E-cadherin in signet ring cell carcinoma of the stomach.

Adult↗

PubMed1996

Establishment and characterization of choroid plexus carcinoma cell lines: connection between choroid plexus and immune systems.

Murine choroid plexus cell lines were produced from choroid plexus carcinoma generated in transgenic mice harboring the viral oncogene simian virus 40 large tumor antigen under transcriptional control of an intronic enhancer region from the human immunoglobulin heavy chain (IgH) gene. Two morphologically distinct cell lines have been cloned. These established cell lines retained the characteristics of choroid plexus cells in that they expressed such choroid plexus cell marker or related proteins as transthyretin and alpha2-macroglobulin. They were tumorigenic in nude mice. In the cell lines, the muA and muB (HE2) motifs within the IgH intronic enhancer were active and we also demonstrated the existence of the proteins binding to these motifs, suggesting a potential link between the choroid plexus and immune systems. It is considered that these binding proteins act as trans-activators for the enhancer and may belong to the class of ETS-related proteins. These cell lines and xenografts should be useful materials for analyses of choroid plexus functions.

Animals↗

PubMed1996

Acute pancreatitis induced by hypercalcaemia associated with adult T-cell leukaemia: a case report.

A 44 year old Japanese woman with adult T-cell leukaemia (ATL) was admitted to Kyushu University hospital to receive a course of alpha-interferon treatment. She experienced a sudden onset of hypercalcaemia and epigastric pain associated with an increase in the level of pancreatic enzymes. Her serum parathyroid hormone related protein level was above normal although her high sensitive PTH level was within the normal range. Ultrasonography and computed tomography (CT) of the abdomen showed enlargement of the pancreas with indistinct margins and massive accumulation of extrapancreatic fluid. Cullen's sign was observed. A few days after the onset of acute pancreatitis, the serum amylase level increased to 3400 IU/L, and the serum calcium level fell to 4.2 mg/dL from 13.3 mg/dl. Her fasting blood glucose level increased to 242 mg/dL. Although the first episode of pancreatitis appeared to respond to treatment, she experienced a second episode of pancreatitis accompanied by an elevation of the serum calcium level. These findings suggest that acute pancreatitis was caused by hypercalcaemia associated with ATL.

Acute Disease↗

PubMed1996

Portal-systemic shunting in a patient with normal portal vain pressures and histological evidence of idiopathic portal hypertension.

Although idiopathic portal hypertension (IPH) is clinically characterized by portal hypertension and marked splenomegaly, we have experienced a case of spontaneous portal-systemic shunt without splenomegaly in whom the liver histology resembled IPH but with normal portal pressure. We admitted a 64 year old man who had suffered from hepatic encephalopathy for 2 years. Laparoscopy revealed a dark grey liver with a sharp edge and a concave surface. Examination of a liver biopsy specimen revealed peri-portal fibrosis consistent with IPH. A single, large, portal-systemic shunt was identified by percutaneous transhepatic portography. The shunt arose from the left gastric vein and flowed through the left renal vein into the inferior vena cava. No varices were identified. There were no morphological changes in the hepatic or portal veins. Portal vain pressure was normal. There was a slight difference between the portal pressure and the wedged hepatic vein pressure, suggesting a presinusoidal block. This case raises important questions concerning the aetiology of IPH and the relationship between portal hypertension and the development of collateral venous circulation.

Collateral Circulation↗