Biomedical subjects
Publications and source records attributed to Junko Tanaka.
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During the past 30 years, hepatocellular carcinoma (HCC) in Japan has kept linearly increasing from 10 to 30 per 100,000 population per year and is expected to grow further. The increment is attributed to infection with hepatitis C virus (HCV). Hence, there is a pressing need to find subjects with persistent HCV infection in the general population of Japan and take necessary measures to prevent HCC developing in them. As a first approach toward this goal, the sex- and age-specific prevalence of ongoing HCV infection was surveyed in 3,485,648 first-time blood donors during 1995-2000. Taking into account the size of subpopulations with different sex and age in Japan registered at the Census 2000, there are an estimated 884,954 HCV carriers aged from 16 to 69 years, and 759,316 (86%) of them are older than 40 years, with an increased risk for HCC; they are hidden in the society, without overt liver disease. The national 5-year project searching for HCV carriers in the general population was started in April 2002. Subjects are examinees of health check-ups, which they receive every 5 years when reaching the age of 40, as well as those at increased risk for HCV infection. The project detected HCV RNA in 14,672 of the 1,298,746 (1.1%) health check examinees and in 16,721 of the 624,734 (2.7%) high-risk individuals during the first fiscal year. Subjects found with HCV RNA have been referred to clinics and hospitals with expert hepatologists. Hopefully, this project will decrease HCC development in HCV carriers in Japan and be considered in other countries where increases in HCC are predicted from the current age-specific prevalence of anti-HCV.
In hepatic disorders, abnormal plasma amino acid profiles are observed. In this study, we examined whether soy protein isolate (SPI) improved plasma methionine concentration in the model animals. Portacaval shunt (PCS) increased alanine aminotransferase (ALT) activity and methionine concentration in blood of rats fed a 40% casein diet supplemented with 0.6% methionine (casein-M diet). A 40% SPI diet supplemented with 1.28% methionine (SPI-M diet), which contained the same amount of methionine as that in 40% casein-M diet, normalized plasma ALT activity and methionine level in PCS rats. These effects of a SPI diet may be due to its amino acid composition, since an amino acid mixture diet mimicking a 40% SPI-M diet was also effective to hypermethioninemia of PCS rats. To find key enzymes for the beneficial effect of soy protein, we examined effects of a 40% SPI-M or casein-M diet on the activities of three methionine-metabolizing enzymes in liver of PCS rats. A SPI-M diet stimulated only the activity of cystathionine gamma-lyase, compared with a casein-M diet. A SPI diet has a preventive effect on hypermethioninemia, at least in part, by stimulating cystathionine gamma-lyase activity in liver and may be used for nutritional management of liver disorders with hypermethioninemia.
Since some antagonists or antidotes in cases of acute poisoning are not commercially available in Japan, in many hospitals they are prepared on their premises for clinical use. However, no specific legislation for the procedures of quality assurance and informed consent of these hospital-prepared products as yet exists. Further, the standard procedures for clinical use of the hospital-prepared products have yet to be established. For the treatment of patients with methemoglobinemia, we prepared methylene blue for injectable use in our hospital. In this paper, we describe our procedures ranging from its preparation to clinical use of this product. Methylene blue injection was prepared by using reagent-grade chemicals. The quality of hospital-prepared methylene blue injection was examined in accordance with the United States Pharmacopoeia. The contents of methylene blue injection remained constant at room temperature during storage for 12-month. The sterility testing also gave negative results during the same period. In order to obtain approval for its clinical use by the in-hospital ethical committee, relevant documents such as instructions for the preparation method, product information on safety usage and consent form were created. After these procedures, clinical applications of methylene blue injection were finally initiated.
Patients on maintenance hemodialysis (HD) are at increased risk of infection with hepatitis C virus (HCV). A prospective follow-up study on HCV infection from November 1999 to February 2003 was conducted in nine hemodialysis (HD) units in Hiroshima. A total of 2,744 HD patients were surveyed regularly for HCV RNA in serum. The prevalence of HCV RNA decreased from 15.7% (262/1,664) on the first survey to 12.9% (242/1,882) in the last one (P<0.05). This decrease may be attributed to the inclusion of patients with a lower prevalence of HCV RNA compared to patients leaving dialysis centers (111/1,080 [10.3%] vs. 132/862 [15.3%], P<0.01). During the 40 months of this study, 16 de novo HCV infections were documented in the nine HD units corresponding to an incidence of 0.33% per year. These cases included eight new HCV infections, three re-infections, and five infections that presumably occured in the window period when tested during the first survey. Our study shows that the annual incidence of de novo HCV infection during HD was 0.33%, and emphasizes the need for frequent serum HCV RNA testing and for stringent disinfection procedures in order to prevent the transmission of HCV in these settings.
Two chimpanzees were inoculated with hepatitis C virus (HCV) and followed on a daily basis for 12 days. HCV RNA became detectable in their sera on day 5 by polymerase chain reaction with the detection limit of 10(2) copies/ml. Based on an exponential growth observed until 8 or 9 days after inoculation in their sera, the doubling time of HCV in the circulation was estimated at 6.3-8.6 h and log time (time required to grow 10-fold) at 31.3- 42.9 h. The exact doubling time of HCV determined in them would help plan an efficient strategy for screening out blood donors in the window period of infection between the exposure and the development of antibody to HCV in serum.
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BACKGROUND: Sperm concentration and motility are poor predictors of the outcome of intrauterine insemination (IUI), hysteroscopic intratubal insemination (HIT), or complete fertilization failure (CFF) in conventional IVF. We investigated whether the calcium ionophore-induced acrosome reaction (AR) constitutes an additional indicator of CFF and pregnancy that is independent of these semen parameters. METHODS: Infertile couples with no female factor (n=388) and women with tubal obstruction (n=32) were studied: IVF (n=133), ICSI (n=72), HIT (n=245) and IUI (n=61). The percentage of acrosome-reacted sperm in relation to viable sperm was calculated. Receiver operating characteristic curve and multiple logistic regression analyses were used to determine threshold values and the best predictor for CFF and pregnancy. RESULTS: Threshold values of AR for predicting CFF in IVF and pregnancy in IVF and HIT + IUI were 21, 26 and 22% respectively. These values were independent of the conventional semen analysis parameters. CFF was lower (2 versus 20%; P<0.01) and the pregnancy rate was higher (46 versus 24% P<0.05) for those with AR >21% in IVF. CFF and pregnancy rate in ICSI did not differ according to AR. Pregnancy rate was higher for those with an AR >22% for HIT + IUI (23 versus 11% P<0.01). CONCLUSIONS: Ionophore-induced AR appears to be a useful indicator in addition to routine semen analysis for selection of patients for treatment with appropriate assisted reproduction procedure.
Mitogen-activated protein kinase (MAPK) cascades are involved in a variety of cellular responses including proliferation, differentiation, and apoptosis. We have developed an expression screening method to detect in vivo substrates of MAPKs in mammalian cells, and identified a membrane protein, linker for activation of T cells (LAT), as an MAPK target. LAT, an adapter protein essential for T-cell signaling, is phosphorylated at its Thr 155 by ERK in response to T-cell receptor stimulation. Thr 155 phosphorylation reduces the ability of LAT to recruit PLCgamma1 and SLP76, leading to attenuation of subsequent downstream events such as [Ca2+]i mobilization and activation of the ERK pathway. Our data reveal a new role for MAPKs in a negative feedback loop in T-cell activation via threonine phosphorylation of LAT.
Cdt1 is a licensing factor for DNA replication, the function of which is tightly controlled to maintain genome integrity. Previous studies have indicated that the cell cycle-dependent degradation of Cdt1 is triggered at S phase to prevent re-replication. In this study, we found that Cdt1 is degraded upon DNA damage induced by either UV treatment or gamma-irradiation (IR). Although the IR-triggered degradation of Cdt1 was caffeine-insensitive, the UV-triggered degradation of Cdt1 was caffeine-sensitive. This indicates that the cells treated with UV utilize the checkpoint pathway, which differs from that triggered by IR. A recent study has suggested that Cdt1 is phosphorylated, ubiquitylated, and degraded at the G(1)/S boundary in the normal cell cycle. Treatment with MG132, a proteasome inhibitor, inhibited the degradation of Cdt1 and resulted in the accumulation of the phosphorylated form of Cdt1 after UV treatment. In the case of UV treatment, phosphorylation of Cdt1 induced the recruitment of Cdt1 to a SCF(Skp2) complex. Moreover, ectopic overexpression of Cdt1 after UV treatment interfered the inhibition of DNA synthesis. These results indicate that Cdt1 is a target molecule of the cell cycle checkpoint in UV-induced DNA damage.
A ligand-receptor pair, bone morphogenetic protein-7 (BMP7) and activin receptor IIB (actRIIB), was identified from a pool of DNA fragments recovered from MCF7 cells treated with 17beta-estradiol (E2) by chromatin immunoprecipitation with antiestrogen receptor-alphaantibody. The E2 responsiveness of both genes was confirmed in MCF cells and in the mouse uterus. Repeated treatment with E2 resulted in decreased expression of both actRIIB and BMP7 mRNA in the uteri of ovariectomized mice. A single oral administration of bisphenol A (BPA), an environmental estrogen, inhibited actRIIB and BMP7 expression and apoptosis in the luminal epithelium of the mouse uterus at diestrus (or early proestrus). This decrease, due to BPA administration, was restored by an estrogen receptor (ER) antagonist suggesting that it is mediated through ERs. These results suggest that E2 and BPA suppress estrogen-dependent apoptosis of epithelial cells of the endometrium through down-regulation of actRIIB and BMP7. Thus, we propose that BMP7 and actRIIB, a ligand-receptor pair, are involved in regulation of the apoptotic signaling pathway and might therefore be new biomarkers of the effects of environmental estrogens on the female reproductive tract.
We have observed that tetrahydrobiopterin (BH4), a cofactor of nitric oxide synthase (NOS), acts as a self-protection factor against nitric oxide (NO) toxicity in PC12 cells. To further investigate the self-protection action of BH4 in vivo, the effect of deletion of endogenous BH4 on NO-producing cells was examined in the rat hippocampus. Following the peripheral infusion of 50 mM 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of GTP cyclohydrolase I, using a miniosmotic pump for 14 days, BH4 content in the hippocampus decreased as compared with the control group administered with vehicle solution, which had no effect on brain BH4 content. When the rats were administered with 50 mM DAHP and 10 mM BH4, the DAHP-induced decrease in BH4 content was prevented. The extracellular concentration of NO metabolites remained unchanged following DAHP administration, suggesting that DAHP-induced decrease in BH4 content had no effect on NO production. The number of NOS-positive cells decreased following DAHP administration in the hippocampal regions, while the number of NOS-negative cells remained unchanged. The DAHP-induced decrease in the NOS-positive cell number was prevented by the administration of 10 mM BH4 and DAHP. These results suggest that endogenous BH4 may affect NOS-positive cell number in the rat hippocampus.
BACKGROUND: Synthesis of nitric oxide by endothelial nitric oxide synthase (ENOS) plays a key role in the atherosclerotic process. Several polymorphisms of the gene encoding ENOS are now known and have been investigated with respect to their influence on cardiovascular disease risk in the general population. The authors prospectively investigated whether ENOS gene polymorphisms determined the risk of cardiovascular complications in a cohort of hemodialysis patients. METHODS: A total of 335 nondiabetic hemodialysis patients were genotyped for 3 ENOS polymorphisms (T-786-->C, intron 4, and Glu298Asp polymorphism) and were followed up prospectively for a mean of 44.2 +/- 9.0 months. The end-points of the study were major cardiac, cerebrovascular, or peripheral vascular events. RESULTS: Two ENOS polymorphisms were associated with cardiovascular events: a T to C substitution at position -786 of the promoter and a deletion-insertion in intron 4 (the a allele having 4 repeats of a consensus sequence and the b allele having 5 repeats). A total of 84 subjects were -786C carriers (CC+TC), and 15 (18%) suffered from cardiovascular events compared with only 13 of 251 TT patients (5%). The relative risk of cardiovascular events was higher for -786C carriers compared with noncarriers (relative risk: 2.05, P = 0.0003). It was also higher for a allele carriers (intron 4 polymorphism) compared with noncarriers (relative risk: 1.97, P = 0.0005). CONCLUSION: T-786-->C polymorphism and intron 4 polymorphism, but not Glu298Asp polymorphism, of the ENOS gene can influence the risk of cardiovascular events in Japanese nondiabetic hemodialysis patients.
The effects of a new benzimidazole derivative, ME3407 (n-butyl-2-(thiazolo-[5,4-b]pyrid-2-yl) sulfinylacetate, CAS 133903-90-9), on gastric acid secretion and gastric and duodenal ulcers in rats were examined. ME3407, given orally, inhibited dose-dependently (0.3-30 mg/kg) the incidence of gastric lesions such as Shay ulcers, and water-immersion stress-, acetylsalicylic acid (ASA)- and histamine-induced erosions. In addition, ME3407 showed marked therapeutic effect on HCl- and ASA-induced lesions. In the lumen-perfused rats, oral administration of ME3407 inhibited dose-dependently (1-100 mg/kg) gastric acid secretion induced by histamine and tetragastrin with ED50 values of 3.02 and 3.37 mg/kg, respectively. Oral administration of ME3407 at a dose of 30 mg/kg also inhibited the elevation of serum gastrin level. The development of duodenal ulcers caused by mepirizole and systeamine was also potently inhibited by ME3407 at an oral dose of 0.1-30 mg/kg. However, when given at 30 mg/kg intraduodenally, subcutaneously or intravenously, ME3407 did not inhibit these acutely induced gastric elosion and acid output. ME3407 was not detected in the serum upon oral administration. These results indicated that ME3407 was active only by oral administration, and exerts direct action on the ulcers and acid secretion from the gastric membrane.
Rho GTPases, Cdc42 and Rac1, play pivotal roles in cell migration by efficiently integrating cell-substrate adhesion and actin polymerization. Although it has been suggested that integrins stimulate these Rho GTPases via some of integrin binding proteins such as focal adhesion kinase (FAK) and paxillin, the precise molecular mechanism is largely unknown. In this study, we showed that the over-expression of RP1 corresponding to the first CH domain (CH1) of affixin, an integrin-linked kinase (ILK)-binding protein, induced a significant actin reorganization in MDCK cells by activating Cdc42/Rac1. Affixin full length and RP1 co-immunoprecipitated with alphaPIX, a Cdc42/Rac1-specific guanine nucleotide exchanging factor (GEF), and they co-localized at the tips of lamellipodia in motile cells. The involvement of alphaPIX in the RP1-induced Cdc42 activation was demonstrated by the significant dominant negative effect of a point mutant of alphaPIX, alphaPIX (L383R, L384S), lacking GEF activity. Our data strongly support that ILK and affixin provide a novel signalling pathway that links integrin signalling to Cdc42/Rac1 activation.
Cohesive interactions between Porphyromonas gingivalis and plaque-forming bacteria, such as Streptococcus oralis, are considered to play an important role in the colonization of P. gingivalis in periodontal sites. Although P. gingivalis fimbriae have been reported to mediate coaggregation with S. oralis, the S. oralis molecule involved has not been identified. We identified the coadhesin of S. oralis ATCC 9811 and purified it by affinity column chromatography. We found that the molecular mass of the purified protein was approximately 40 kDa. Dot blot and Western blot assays showed binding of the 40-kDa protein to P. gingivalis fimbriae. Further, turbidimetric assays showed that the coadhesin inhibited coaggregation between P. gingivalis and S. oralis in a dose-dependent manner. Analyses of the amino-terminal sequences of the protein and its lysyl endopeptidase-cleaved fragments revealed that the coadhesin was identical to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Next, we cloned the gene that encodes S. oralis GAPDH and found that the sequence had a high degree of homology with the sequences of GAPDHs of various bacteria, including Streptococcus gordonii and Fusobacterium nucleatum. To confirm the contribution of S. oralis GAPDH to the interaction with P. gingivalis, a recombinant GAPDH protein was generated in Escherichia coli; this protein bound to P. gingivalis fimbriae and had an inhibitory effect on coaggregation. These results suggest that S. oralis GAPDH functions as a coadhesin for P. gingivalis fimbriae. In addition, considering the high degree of homology of the GAPDHs of various bacteria, those of other plaque-forming bacteria also may contribute to the colonization of P. gingivalis.
OBJECTIVE: Carriers of hepatitis B virus (HBV) and hepatitis C virus (HCV) in Japan were estimated on a national basis. METHODS: Sera from the first-time blood donors aged 16-64 years in eight jurisdictions of the Japanese Red Cross Blood Center during 1995-2000 were tested for hepatitis B surface antigen (HBsAg) and antibody to HCV (anti-HCV). Viremia with HCV was estimated to be present in 70% of donors with anti-HCV. RESULTS: HBsAg was detected in 22,018 of 3,485,648 (0.63%) blood donors including 12,990 of 1,780,149 (0.73%) men and 9,028 of 1,705,499 (0.53%) women, and anti-HCV in 17,010 (0.49%) including 8,504 (0.48%) men and 8,506 (0.50%) women. Multiplying the carrier rate by the population registered in the Census 2000, the total HBV carriers aged 15-65 years were estimated at 967,753 (95% confidence interval 806,760-1,128,745), of whom 571,210 (479,267-663,152) were men and 396,543 (327,494-465,593) were women. Likewise, the total HCV carriers were estimated at 884,954 (95% confidence interval 725,082-1,044,826), of whom 464,363 (377,927-550,799) were men and 420,591 (347,156-494,027) were women. CONCLUSION: Estimated numbers of HBV and HCV carriers would help plan to prevent the development of hepatocellular carcinoma in Japan.