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Biomedical subjects

K Ohba

Publications and source records attributed to K Ohba.

At least 19 recordsLinked to original sources
PubMed2001

Analysis of inhibition by H89 of UCP1 gene expression and thermogenesis indicates protein kinase A mediation of beta(3)-adrenergic signalling rather than beta(3)-adrenoceptor antagonism by H89.

Although it has generally been assumed that protein kinase A (PKA) is essential for brown adipose tissue function, this has not as yet been clearly demonstrated. H89, an inhibitor of PKA, was used here to inhibit PKA activity. In cell extracts, it was confirmed that norepinephrine stimulated PKA activity, which was abolished by H89 treatment. In isolated brown adipocytes, H89 inhibited adrenergically induced thermogenesis (with an IC(50) of approx. 40 microM), and in cultured cells, adrenergically stimulated expression of the uncoupling protein-1 (UCP1) gene was abolished by H89 (full inhibition with 50 microM). However, H89 has been reported to be an adrenergic antagonist on beta(1)/beta(2)-adrenoceptors (AR). Although adrenergic stimulation of thermogenesis and UCP1 gene expression are mediated via beta(3)-ARs, it was deemed necessary to investigate whether H89 also had antagonistic potency on beta(3)-ARs. It was found that EC(50) values for beta(3)-AR-selective stimulation of cAMP production (with BRL-37344) in brown adipose tissue membrane fractions and in intact cells were not affected by H89. Similarly, the EC(50) of adrenergically stimulated oxygen consumption was not affected by H89. As H89 also abolished forskolin-induced UCP1 gene expression, and potentiated selective beta(3)-AR-induced cAMP production, H89 must be active downstream of cAMP. Thus, no antagonism of H89 on beta(3)-ARs could be detected. We conclude that H89 can be used as a pharmacological tool for elucidation of the involvement of PKA in cellular signalling processes regulated via beta(3)-ARs, and that the results are concordant with adrenergic stimulation of thermogenesis and UCP1 gene expression in brown adipocytes being mediated via a PKA-dependent pathway.

Adipocytes↗
PubMed2001

Synchronized disappearance of serum HCV-RNA, anti-U1 RNP, anti-La/SS-B, and anti-Scl-70 in a patient with chronic hepatitis.

The authors report a rare case of chronic hepatitis in whom normalization of serum aminotransferases was associated with disappearance of serum hepatitic C virus (HCV)-ribonucleic acid (RNA), anti-U1 RNP, anti-La/SS-B, and anti-Scl-70 antibodies without treatment of interferon or corticosteroids. A 27-year-old Japanese woman was diagnosed with chronic hepatitis C, with positive anti-nuclear antibody, anti-U1 RNP, anti-La/SS-B, and anti-Scl-70 antibodies. Histopathologic examination of a liver biopsy specimen showed a periportal interface hepatitis with a predominantly lymphoplasmacytic necroinflammatory infiltrate and lobular hepatitis. After two-year treatment with ursodeoxycholic acid (UDCA), serum aminotransferases normalized and serum HCV-RNA, anti-U1 RNP, anti-La/SS-B, and anti-Scl-70 antibodies disappeared. It was unclear whether disappearance of HCV-RNA was spontaneous, due to some immunomodulating effects of UDCA, or other unknown mechanism, but host immune response may be associated with HCV elimination.

Journal Article↗
PubMed2001

Identification of two novel splicing variants of human type II iodothyronine deiodinase mRNA.

Human type II iodothyronine deiodinase (hDII) belongs to a family of selenoproteins. It catalyzes 5'-deiodination of thyroxine to generate an active thyroid hormone, 3,3',5-triiodothyronine. Two novel splice variants of hDII gene transcript; namely hDII-b and hDII-c, were identified. Three distinct DNA fragments (hDII-a-c) were amplified by a reverse transcription-polymerase chain reaction (RT-PCR) with hDII intron-spanning primers using total-RNA from human umbilical vein endothelial cell line, ECV304. The sequence of hDII-a was identical to that of previously reported hDII. hDII-b and hDII-c had an additional insertion of 108 and 242 bp, respectively. The insertion sequences were found in the intron of hDII gene, therefore, two novel exons exist between exons 1 and 2 of hDII gene. The splice sites of new exons (b and c) conserved the consensus sequences of splice acceptor and donor sites. hDII-b contains exon b with an in-frame TGA codon that may encode an extra selenocysteine. hDII-c contained exons b and c and the predicted open reading frame is interrupted by a stop codon (TAA) produced by a frame shift. RT-PCR analysis showed that hDII-a and hDII-b mRNAs are expressed in human tissues including brain, kidney, lung and trachea. The mRNA abundance of hDII-c was lower than that of hDII-a or hDII-b. Thus, the new variants of hDII transcripts suggest the presence of two short exons between exons 1 and 2 of hDII gene, and of functional variant of hDII.

Alternative Splicing↗
PubMed2001

Low density lipoprotein receptor mRNA in rat liver is affected by resistant starch of beans.

The effects of resistant starches of beans on serum cholesterol and hepatic low density lipoprotein (LDL) receptor mRNA in rats were investigated. Rats were fed a cholesterol-free diet with 150 g/kg corn starch (CS), 150 g/kg adzuki (Vigna angularis) starch (AS), 150 g/kg kintoki (Phaseolus vulgaris, variety) starch (KS), or 150 g/kg tebou (P. vulgaris, variety) starch (TS) for 4 wk. There were no significant differences in body weight among groups through the experimental period. The liver weight in the CS group was 1.1-1.2 times higher than that in the AS, KS, and TS groups. The cecum weight in the TS was 1.4 times higher than that in the CS group, and the cecal pH in the CS group was significantly higher than in the other groups. The serum total cholesterol, very low density lipoprotein + intermediate density lipoprotein + LDL-cholesterol and high density lipoprotein (HDL)-cholesterol concentrations in the bean starch groups were significantly lower than those in the CS group through the feeding period. The total cholesterol/HDL-cholesterol ratio in the bean starch groups was also significantly lower than that in the CS group at the end of the 4-wk feeding period. The hepatic cholesterol concentration in the TS group was significantly higher than in the CS group at the end of the 4-wk feeding period. The relative quantity of hepatic apo B mRNA in the AS group was 1.2 times higher than that in the CS group, and the hepatic LDL receptor mRNA levels in the AS and TS groups were 1.8-2.0 times higher than that in the CS group. The results of this study demonstrate that AS, KS, and TS lowered the serum total cholesterol level by enhancing the hepatic LDL receptor mRNA level.

Animals↗
PubMed2001

Primary biliary cirrhosis among atomic bomb survivors in Nagasaki, Japan.

Despite rapid progress in methods for analyzing radiation effects, much remains to be learned about the mechanisms and processes of radiation-induced immunological dysfunction. Among 17,899 sera obtained from atomic bomb survivors in Nagasaki, Japan, sera from 484 participants who complied with a reexamination for alkaline phosphatase (ALP) were tested for antimitochondrial antibody (AMA) by indirect immunofluorescence, and autoantibodies against 2-oxo-acid dehydrogenase complex (2-OADC) by immunoblotting to investigate the prevalence of primary biliary cirrhosis (PBC). Of these 484 sera, 28 (5.8%) were seropositive for AMA. The 484 participants were divided into three groups according to distance from the hypocenter: 72 who were exposed within 1999 m (closest group), 368 from 2000 to 5999 m (intermediate distant group), and 44 outside 6000 m (distant group). The positivity rates for AMA in these three groups were 6/72 (8.3%), 22/368 (6.0%), and 0/44 (0%), respectively (P =.08). Furthermore, high titers ( > 1:320) of AMA were observed in 3/6 (50%) AMA-positive sera from the closest group, in contrast to 4/22 (18%) from the intermediate distant group, although there was no significant correlation between AMA titer and distance from the hypocenter (P =.07). Of these 28 AMA-positive sera, 11 (39%) were from participants who had already been diagnosed with PBC, and 25 (89%) contained antibodies against at least one component of 2-OADC enzymes by immunoblotting. Therefore, the prevalence of PBC was estimated to be at least 615 cases per million (792 per million women). Our results suggest that the prevalence of PBC in atomic bomb survivors in Nagasaki is higher than that reported for the general population in Japan, and a further survey of the environmental factors, including radiation exposure, that predispose to PBC would be needed for understanding this disease of unknown etiology.

Aged↗
PubMed2001

Previous or occult hepatitis B virus infection in hepatitis C virus-associated hepatocellular carcinoma without hepatic fibrosis.

We investigated the role of hepatitis B virus infection in development of hepatocellular carcinoma in hepatitis C virus-infected patients without hepatic fibrosis. Of 253 patients, 8 lacked hepatic fibrosis (group 1); group 2 included the remaining 245 patients. Clinicopathologic findings were compared between the groups. Hepatitis B x gene was sought in cancers and adjoining noncancerous liver. Group 1 showed better liver function parameters and milder active hepatitis than group 2. The proportion of patients with anti-hepatitis B virus antibody tended to be higher in group 1 than in group 2. The proportion of patients with hepatitis B x RNA in cancers was significantly higher in group 1 than in group 2. All group 1 patients had previous or occult hepatitis B virus infection. Previous or occult hepatitis B virus infection may be critical in development of hepatocellular carcinomas in hepatitis C virus-infected patients without hepatic fibrosis.

Aged↗
PubMed2001

Life without UCP1: mitochondrial, cellular and organismal characteristics of the UCP1-ablated mice.

Mice devoid of the original uncoupling protein UCP1 have provided opportunities to delineate UCP1 function in a series of biochemical and physiological contexts. The isolated brown-fat mitochondria from such mice are fully coupled (without the addition of GDP), but still exhibit a depressed capacity for ATP synthesis. However, they only show a 2-fold decrease in sensitivity to the de-energizing effect of free fatty acids, compared with UCP1-containing mitochondria, whereas they possess a (UCP1-independent) 50-fold higher sensitivity than liver mitochondria; the fatty acid sensitivities in wild-type and UCP1-deficient mitochondria may, however, be of different natures. Despite the fact that brown-fat cells from UCP1-ablated mice cannot produce heat when stimulated by noradrenaline ('norepinephrine') or fatty acids, UCP1-ablated mice can be induced to tolerate extended cold exposure, but the heat then fully results from shivering thermogenesis. Recruitable or adaptive (by cold acclimation or adaptation to a cafeteria diet) adrenergically-stimulated thermogenesis does not exist in the UCP1-ablated animals, demonstrating the unique ability of UCP1 to mediate recruitable non-shivering thermogenesis. In addition to information on the function of UCP1, the UCP1-ablated mice can be used to gain information concerning the function of the UCP1 homologues. Thus whereas an uncoupling function of the UCP1 homologues cannot be excluded, UCP1-ablated animals clearly lack any ability to recruit any UCP1 homologue to functionally replace the loss of thermogenesis resulting from UCP1. UCP1 (thermogenin) thus remains the only protein the activity of which can be recruited for the purpose of facultative thermogenesis.

Adipose Tissue, Brown↗
PubMed2001

Changes in titers of antimitochondrial and antinuclear antibodies during the course of primary biliary cirrhosis.

A case of primary biliary cirrhosis (PBC) in whom a complete biochemical (serum bilirubin, transaminases and alkaline phosphatase) remission was noted after combination treatment with ursodeoxycholic acid (UDCA) and corticosteroid is reported. The antimitochondrial antibody (AMA) detected by indirect immunofluorescence was initially positive, and the antinuclear antibody (ANA) was negative, but these two antibodies subsequently fluctuated independently (AMA-positive/ANA-negative, AMA-negative/ANA-negative, AMA-negative/ANA-positive, AMA-positive/ANA-positive, and again AMA-negative/ANA-positive) in spite of a lack of histopathological improvement in the liver after treatment. The clinical presentation in our case suggests that in some cases the diagnosis of PBC or so-called autoimmune cholangitis (AIC) might depend on the 'phase' of the same disease. Our results also suggest that detailed immunoreactive profiles against 2-oxo-acid dehydrogenase complex (2-OADC) enzymes by using immunoblotting, together with a serial histological examination, should provide more precise information for a diagnosis of PBC.

Adult↗
PubMed2001

Prevention of hepatic and peritoneal metastases by the angiogenesis inhibitor fr-118487 after removal of growing tumor in mice.

We established a mouse rising dbl quote, left (low)primary tumor resection model" in which a transplanted tumor was resected after an orthotopic transplantation of colorectal cancer tissue to estimate the therapeutic effect of an angiogenesis inhibitor on metastasis. The angiogenesis inhibitor FR-118487 is a member of the fumagillin family. Here, 1 mg / kg / day of FR-118487 was subcutaneously administered to nude mice for 1 week, 2 weeks, or 4 weeks through an osmotic pump. Liver metastasis developed in 7 of 9 control mice, 2 of 6 mice that underwent the tumor resection 2 weeks after transplantation (early resection), and in all 7 of the mice that underwent the tumor resection 4 weeks after transplantation (late resection). In the short treatment trial, the FR-118487 administration immediately after the early resection completely inhibited both hepatic and peritoneal metastases, whereas its administration after the late resection had no effect on liver metastasis. In the prolonged treatment trial, inhibitory effects of prolonged treatment with FR-118487 on both hepatic and peritoneal metastases after the late resection were clearly demonstrated. The mice of the resection-alone group all died within 106 days after tumor inoculation, due to metastases of colon carcinoma. In contrast, half of the mice that underwent resection and then received antiangiogenic therapy were alive at the end of the observation period (160 days after transplantation). In conclusion, the combination of surgery and subsequent antiangiogenic therapy may be useful to prevent the distant metastasis of colorectal cancer and to improve the prognosis of patients with colorectal cancer.

Angiogenesis Inhibitors↗
PubMed2001

Successful treatment of dissemination of hepatocellular carcinoma to the pleura and diaphragm after percutaneous liver biopsy.

BACKGROUND/AIM: Treatment for dissemination of hepatocellular carcinoma to the pleura and diaphragm following percutaneous needle biopsy has not been established. METHODS: The case of a 57-year-old man who underwent percutaneous needle biopsy for liver tumor is presented. RESULTS: Ten months after resection of the tumor (moderately differentiated hepatocellular carcinoma), masses in the right pleural cavity and on the diaphragm were detected by computed tomography. Resections of the masses with surrounding tissue and the diaphragm and wedge resection of the right lung were performed. A wide range of the pleura and the diaphragm was coagulated with an argon beam coagulator. The patient is in good health without recurrence 4 years after the operation. CONCLUSION: Aggressive surgical treatment should be considered for patients with dissemination of hepatocellular carcinoma by needle biopsy when the lesions are limited.

Biopsy, Needle↗
PubMed2001

[Complex translocation (8;15;21) (q22;p12;q22) in a child with AML-M2 showing de novo appearance of the short form of AML1-MTG8 chimeric mRNA during the course].

A 4-year-old boy admitted with exophthalmos was diagnosed as having acute myeloblastic leukemia with maturation (AML-M2). Chromosomal analysis (G-banding) showed t(8;15;21). Fluorescence in situ hybridization (FISH), reverse transcriptase-polymerase chain reaction (RT-PCR), spectral karyotyping (SKY), and nucleolar organizer region (NOR) staining suggested that this complex translocation might have resulted from stepwise translocation, namely an initial translocation between chromosomes 8 and 21, followed by a second translocation between der(21) and chromosome 15, rather than the other possibility of clockwise translocation. During chemotherapy, RT-PCR demonstrated the short form of AML1-MTG8 mRNA, in addition to chimeric mRNA of the usual length. Sequence analysis revealed that this shorter chimeric mRNA had resulted from deletion of a 250-bp sequence at the 5' end of MTG8. A literature search failed to reveal any similar cases of t(8;21) AML-M2 associated with this deletion of chimeric mRNA.

Base Sequence↗
PubMed2000

Identification of novel first exons in Ad4BP/SF-1 (NR5A1) gene and their tissue- and species-specific usage.

It has been demonstrated that the mammalian Ad4BP/SF-1 (NR5A1) gene is regulated precisely in sex, tissue, and developmental stage specific manners. To clarify the complex transcriptional regulation, we investigated in the present study whether the gene transcription is regulated by multiple promoters accompanied by noncoding first exons. Novel first exons (Io and Ig) were identified downstream of the already identified exon Ia. Nucleotide sequences revealed that Ia and Ig exons were well conserved, whereas Io exon was less conserved among the mouse, rat, and human genes. Interestingly, the splice donor of the mouse and human Io and human Ig exons do not satisfy the consensus sequence. Transcripts containing Ia, Io, and Ig were detected in all rat tissues examined, while the transcript containing Io was undetectable in the corresponding tissues of mice. The lack of exon Io usage in the mouse was confirmed by transient transfection assays with cultured cells. Quantitative RT-PCR analysis revealed that the transcript containing Ig exon was the main product in the pituitary but significantly less in the spleen, suggesting that the regulation of Ad4BP/SF-1 gene transcription in the pituitary and spleen is distinct from that of other tissues. The above findings, together with the structural abnormality at the splice donor site, suggest that acquisition of the multiple first exons enables the Ad4BP/SF-1 gene to be regulated differentially in different animal species and in different tissues in the same animal.

Alternative Splicing↗
PubMed2000

Serial changes in enzyme inhibitory antibody to pyruvate dehydrogenase complex during the course of primary biliary cirrhosis.

To assess the usefulness of enzyme inhibition assay for the diagnosis of primary biliary cirrhosis (PBC), we determined the serial changes in enzymatic inhibitory antibody to pyruvate dehydrogenase complex (PDC) in patients with PBC, and compared the results to those of immunofluorescence and immunoblotting. Forty-nine sera from 19 patients with PBC who were followed-up for at least 16 months were tested for antimitochondrial antibodies (AMA) by indirect immunofluorescence, immunoblotting on bovine heart mitochondria, and enzyme inhibition assay using commercially available TRACE Enzymatic Mitochondrial Antibody (M2) Assay (EMA) kit. Of the 49 sera, 39 (80%), 35 (71%), 38 (78%), 31 (63%), and 36 (73%) were positive for AMA by immunofluorescence, for immunoglobulin G (IgG), IgM, and IgA class antibody against E2 subunit of PDC (PDC-E2) by immunoblotting, and for enzymatic inhibitory antibody to PDC by EMA, respectively. AMA titers determined by immunofluorescence did not change in 9 patients (47%), increased in 4 (21%), decreased in 3 (16%), and fluctuated in 3 (16%) during follow-up. The number of anti-M2 bands by immunoblotting did not change in 9 (47%), increased in 6 (32%), decreased in 2 (11%), and fluctuated in 2 (11%). Units of PDC activity by EMA did not change markedly in 16 (84%), increased in 2 (11%), and fluctuated in 1 (5%). Positive EMA results were common in cases with high levels of serum alkaline phosphatase and IgM, and the units of PDC activity by EMA correlated significantly and inversely with AMA titers by immunofluorescence, and serum reactivity to PDC-E2 by immunoblotting, respectively. There was no correlation between serial changes in biochemical data and units of PDC activity by EMA. In three patients who showed a decrease in AMA titers, AMA titers correlated more with EMA results than immunoblotting. Moreover, in a patient with fluctuating AMA titers, the units of PDC activity by EMA paralleled AMA titers. Our results suggest that EMA is useful for the diagnosis of AMA-positive PBC, and also could be used for monitoring the disease course in PBC.

Adult↗
PubMed2000

Management of pancreatic arteriovenous malformation.

Pancreatic arteriovenous malformations (AVM), while extremely rare, are frequently complicated by gastrointestinal bleeding. The elimination of pancreatic AVM is difficult once portal hypertension has developed. We describe herein a patient with congenital AVM of the pancreatic head presenting with recurrent episodes of melena, in whom pylorus-preserving pancreatoduodenectomy provided a means of definitive management. We also review the literature and focus on the diagnostic and therapeutic approaches. Angiography is always necessary to facilitate tactics of treatment, even if diagnosis has been established by non-invasive imaging modalities. To obtain complete regression, total extirpation of the affected organ, or at least the involved portion, should be performed before this disease leads to the lethal complications of gastrointestinal bleeding and portal hypertension. Transcatheter arterial embolization is the only alternative treatment for the control of hemorrhage.

Adolescent↗
PubMed2000

Combination therapy with vascular endothelial growth factor neutralizing antibody and mitomycin C on human gastric cancer xenograft.

Antiangiogenic therapy has been proposed as a new strategy for the treatment of solid tumors. To enhance the therapeutic effect of antiangiogenic agents, combination with conventional anticancer therapy should be investigated. In the present study, we investigated the therapeutic effect of the combination of vascular endothelial growth factor neutralizing antibody (VEGF Ab) and mitomycin C (MMC) on MT-2, a human gastric cancer xenograft. When small pieces of MT-2 were transplanted orthotopically into 62 nude mice, liver metastasis developed 6 weeks after transplantation. The VEGF Ab (100 micro g / mouse) was administered i.p. in the VEGF Ab group (n = 14) and the combination group (n = 16) twice a week from day 10 after transplantation. MMC (2 mg / kg) was administered in the MMC group (n = 16) and the combination group (n = 16) on days 10, 17 and 24 after transplantation. Compared with the control group, in which saline solution was administered i.p., all three treatments inhibited tumor growth significantly and the effects of MMC and combination therapy were potent. Liver metastases were also inhibited significantly by the administration of VEGF Ab alone, MMC alone or combination therapy. Liver metastasis developed in 9 mice of the control group, 3 of the VEGF Ab group, and 4 of the MMC group, but no mice had liver metastasis in the combination therapy group. However a significant body weight loss and a decrease in spleen weight were observed in the MMC and combination groups, with no significant difference between the two groups. These results suggest that combination therapy with VEGF Ab and MMC may be a potent therapy for human gastric cancer.

Adenocarcinoma↗