Search PubMed⌕ Search

Biomedical subjects

S Otani

Publications and source records attributed to S Otani.

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

Specific preinduction of 60-kDa heat shock protein (chaperonin homolog) by TRH does not protect colonic mucosa against acetic acid-induced lesion in rats.

In order to study the cytoprotective function of colonic heat shock proteins (HSPs) in vivo, the effect of specific preinduction of HSP60 by thyrotropin-releasing hormone (TRH) administration on the development of acetic acid-induced colonic mucosal lesion was investigated. Expression of 60-kDa, 72-kDa, and 90-kDa heat shock proteins (HSP60, HSP72, and HSP90, respectively) in rat colonic mucosa was investigated by western blot and immunohistochemical analyses before and after TRH administration. Following pretreatment with or without TRH administration, the rats received intrarectal infusion of 5% acetic acid. The colonic mucosal damage was macroscopically evaluated 24 hr after the intrarectal infusion of acetic acid. Expression of HSP60 was significantly increased by TRH administration in the colonic mucosa, whereas HSP72 and HSP90 did not increase. Immunohistochemical study also showed a significant increase in HSP60 in colonic mucosal cells, especially at the surface of the colonic mucosa after TRH administration. No histopathologic alteration was observed in the colonic mucosa after TRH administration. The colonic mucosal damage caused by intrarectal infusion of 5% acetic acid was not prevented by preinduction of HSP60. We demonstrated that specific preinduction of HSP60 by TRH administration did not show cytoprotective function in the colonic mucosa, although this protein plays a crucial role for cytoprotection in the pancreatic acinar cells. Our results indicate that the role of HSP60 may be different in each organ with respect to cytoprotection.

Acetic Acid↗
PubMed2000

Identification and characterization of testis specific ornithine decarboxylase antizyme (OAZ-t) gene: expression in haploid germ cells and polyamine-induced frameshifting.

BACKGROUND: Polyamines are known to play important roles in the proliferation and differentiation of many types of cells. However, in the testis, where polyamines such as spermidine and spermine exist in high concentrations, their roles still remains to be elucidated. RESULTS: We have cloned a testis-specific gene encoding an ornithine decarboxylase antizyme known to control intracellular concentrations of polyamines in a feedback manner. The mRNA encoding the protein named ornithine decarboxylase antizyme in testis (OAZ-t) was specifically expressed in haploid germ cells. In contrast, the mRNA level of somatic ornithine decarboxylase antizyme 1 (OAZ1) decreased markedly at the late stages of haploid germ cell differentiation. OAZ-t mRNA was first observed in 23-day-old mice, whereas the OAZ-t protein was detected much later, at 35 days after birth. Further experiments on OAZ-t revealed that polyamines were capable of inducing a frameshifting at the frameshift sequence of OAZ-t mRNA, resulting in the translation of OAZ-t, as was the case with the somatic OAZ1. Transfection of OAZ-t cDNA inactivated the ornithine decarboxylase activity in the HEK293 cells. CONCLUSIONS: Results indicate that the expression of OAZ-t is controlled at both transcriptional and translational levels, and that OAZ-t likely plays a key role in spermatogenesis by regulating the intracellular concentration of polyamines in haploid germ cells.

Amino Acid Sequence↗
PubMed2000

Novel prenyltransferase gene encoding farnesylgeranyl diphosphate synthase from a hyperthermophilic archaeon, Aeropyrum pernix. Molecularevolution with alteration in product specificity.

Prenyltransferases catalyse sequential condensations of isopentenyl diphosphate with allylic diphosphates. Previously, we reported the presence of farnesylgeranyl diphosphate (FGPP) synthase activity synthesizing C25 isoprenyl diphosphate in Natronobacterium pharaonis which is a haloalkaliphilic archaeon having C20-C25 diether lipids in addition to C20-C20 diether lipids commonly occurring in archaea [Tachibana, A. (1994) FEBS Lett. 341, 291-294]. Recently, it was found that a newly isolated aerobic hyperthermophilic archaeon, Aeropyrum pernix, had only C25-C25 diether lipids, not the usual C20-containing lipids [Morii, H., Yagi, H., Akutsu, H., Nomura, N., Sako, Y. & Koga, Y. (1999) Biochim. Biophys. Acta 1436, 426-436]. In this report, we describe the isoloation from A. pernix of the novel prenyltransferase gene, fgs, encoding FGPP synthase. The protein encoded by fgs was expressed in Escherichia coli as a glutathione S-transferase fusion protein and produced FGPP as a final product. Phylogenetic analysis of fgs with other prenyltransferases revealed that the short-chain prenyltransferase family is divided into three subfamilies: bacterial subfamily I, eukaryotic subfamily II, and archaeal subfamily III. fgs is clearly contained within the archaeal geranylgeranyl diphosphate (GGPP) synthase group (subfamily III), suggesting that FGPP synthase evolved from an archaeal GGPP synthase with an alteration in product specificity.

Alkyl and Aryl Transferases↗
PubMed2000

Vitamin E inhibits cell proliferation and the activation of extracellular signal-regulated kinase during the promotion phase of lung tumorigenesis irrespective of antioxidative effect.

We have already reported that the activation of extracellular signal-regulated kinase (Erk) is critical in the stimulation of cell proliferation during the promotion stage of urethane-induced lung tumorigenesis in mice. Also, we have found that vitamin E suppresses lung tumorigenesis by inhibiting cell proliferation at the promotion stage. However, it is still unclear whether this inhibitory effect at the promotion stage is based on the antioxidative effect of vitamin E or not. In order to address this question, we examined the inhibitory effect of alpha-tocopheryloxybutyric acid (TSE), an ether derivative of vitamin E that cannot act as an antioxidant in vivo, on cell proliferation and the activation of Erk during promotion of lung tumorigenesis. On day 30 after urethane injection (750 mg/kg, i. p.) in A/J mice, TSE or vitamin E at 100 micromol/kg, p.o. was administered. Twenty-four hours after the final administration, the mice were killed to analyze cell proliferation and related parameters. The labeling index of proliferating cell nuclear antigen (a marker of cell proliferation) and ornithine decarboxylase activity (a marker of the promotion stage in lungs) were attenuated by treatment with TSE or vitamin E. TSE or vitamin E treatment also inhibited urethane-induced activation of Erk and suppressed the activation of other essential members of the Erk cascade (Ras, Raf and Mek). These results suggest that vitamin E inhibits cell proliferation and activation of the Erk cascade during promotion of urethane-induced lung tumorigenesis in mice, independent of its antioxidative effect.

Animals↗
PubMed2000

Chemopreventive effect of 24R,25-dihydroxyvitamin D(3) in N, N'-dimethylhydrazine-induced rat colon carcinogenesis.

In this study we investigated the effects of 24R,25-dihydroxyvitamin D(3) [24R,25(OH)(2)D(3)] on N,N'-dimethylhydrazine (DMH)-induced rat colon carcinogenesis. For experiments 1 and 2, 50 F344 male, 6-week-old rats were divided into five groups in each experiment. Animals were given s.c. injections of DMH once a week for 4 weeks. Those in groups 1-5 were given 24R,25(OH)(2)D(3) in the diet (10, 5, 2.5, 1.25 or 0 p.p.m., respectively) during the post-initiation stage in experiment 1 and during the initiation stage in experiment 2. At termination, the numbers of aberrant crypt foci (ACF) in the rat colonic mucosa were decreased dose-dependently in rats treated with 24R,25(OH)(2)D(3) during the post-initiation stage, but not in the initiation stage. For experiment 3, 15 male, 9-week-old rats were divided into three groups and given 24R,25(OH)(2)D(3) in the diet (10, 5 or 0 p.p.m.). Animals were injected with 5-bromo-2'-deoxyuridine (BrdU) i.p. 1 h before death to examine DNA synthesis in the colon mucosa. BrdU labeling indices were decreased dose-dependently in colonic crypts of rats treated with 24R, 25(OH)(2)D(3). In experiment 4, using the multicarcinogenic protocol we could analyze our data with respect to not only one separate organ, but at the organism level. Sixty-eight male, 6-week-old rats were treated with DMH, N-methylnitrosourea, 2, 2'-dihydroxy-di-n-propylnitrosamine, diethylnitrosamine and N-butyl-N-(4-hydroxybutyl)nitrosamine in weeks 1-4 and were then given 24R,25(OH)(2)D(3) in the diet (5, 1 or 0 p.p.m.) throughout weeks 5-30. Examination of the development of tumors and preneoplastic lesions in various organs revealed that 24R, 25(OH)(2)D(3) inhibited colonic tumor development significantly but exerted no effects on tumor induction in other organs. In conclusion, these results strongly indicate that 24R,25(OH)(2)D(3) inhibits colon carcinogenesis specifically, without any enhancement of carcinogenesis in other organs, when administered in the post-initiation phase.

1,2-Dimethylhydrazine↗
PubMed2000

Chemopreventive effects of bovine lactoferrin on N-butyl-N-(4-hydroxybutyl)nitrosamine-induced rat bladder carcinogenesis.

Chemopreventive effects of bovine lactoferrin (bLF), which is found at high concentrations in colostrum, on rat bladder carcinogenesis were investigated using a rat bladder medium-term bioassay. In experiment 1, a total of 80 F344 male rats, 6 weeks old, were divided into 5 groups. Groups 1 and 2 were treated with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in the drinking water for 8 weeks and after a 1-week interval, received dietary supplementation with 2% and 0.2% bLF, respectively. Group 3 received 0.05% BBN for 8 weeks and then no treatment. Group 4 was administered 2% bLF alone from week 9, without prior carcinogen exposure. Group 5 was maintained without any treatment throughout the experiment. All rats were killed at the end of week 36. Group 1 demonstrated a significantly decreased multiplicity of the bladder tumors (carcinomas and papillomas) as compared with group 3. Maximum cut surface areas of bladder tumors were also significantly decreased in groups 1 and 2 compared with group 3. No bladder tumors were observed in groups 4 or 5. In experiment 2, a total of 60 rats were divided into two groups (30 rats each); both were treated with 0.05% BBN for 4 weeks and after a 1-week interval, one received 2% bLF (group 1) and the other, basal diet (group 2) for 4 weeks. Group 1 demonstrated a tendency for decrease of the 5-bromo-2'-deoxyuridine (BrdU) labeling index. bLF was detected in the urine of rats fed bLF by ELISA as well as western blot analysis. The findings indicate that 2% bLF can inhibit BBN-induced rat bladder carcinogenesis, and that this may be due to bLF in the urine.

Acetyltransferases↗
PubMed2000

Inhibitory effects of S-methylcysteine and cysteine on the promoting potential of sodium phenobarbital on rat liver carcinogenesis.

The effects of S-methylcysteine (SMC) and cysteine on the promotion stages of rodent hepatocarcinogenesis in a medium-term bioassay previously developed by Ito were examined. Initiation was induced by a single dose of diethylnitrosamine (DEN), followed by dietary administration of the promoter sodium phenobarbital (NaPB) 2 weeks later, for 6 weeks. Partial hepatectomy was conducted on all the animals at week 3. Inhibitory potential was evaluated by analyzing two markers of carcinogenesis, namely numbers of glutathione S-transferase placental form (GST-P)-positive foci, and proliferating cell nuclear antigen (PCNA). In addition, the level of ornithine decarboxylase (ODC), one of the rate-limiting enzymes of polyamine metabolism induced by promoters, was analyzed. SMC and cysteine induced significant reduction in the areas of GST-P-positive foci. A significant reduction in the PCNA index was observed in the entire liver as well as in GST-P-positive areas. SMC also induced down-regulation of the ODC enzyme activity. Thus, SMC and cysteine were found to inhibit the promotion stage of DEN-induced hepatocarcinogenesis. No cocarcinogenic effects were evident on administration of either of these chemicals with NaPB.

Animals↗
PubMed2000

Cannabinoids modulate synaptic strength and plasticity at glutamatergic synapses of rat prefrontal cortex pyramidal neurons.

Cannabinoids receptors have been reported to modulate synaptic transmission in many structures of the CNS, but yet little is known about their role in the prefrontal cortex where type I cannabinoid receptor (CB-1) are expressed. In this study, we tested first the acute effects of selective agonists and antagonist of CB-1 on glutamatergic excitatory postsynaptic currents (EPSCs) in slices of rat prefrontal cortex (PFC). EPSCs were evoked in patch-clamped layer V pyramidal cells by stimulation of layer V afferents. Monosynaptic EPSCs were strongly depressed by bath application (1 microM) of the cannabinoid receptors agonists WIN55212-2 (-50.4 +/- 8.8%) and CP55940 (-42.4 +/- 10.9%). The CB-1 antagonist SR141716A reversed these effects. Unexpectedly, SR141716A alone produced a significant increase of glutamatergic synaptic transmission (+46.9 +/- 11.2%), which could be partly reversed by WIN55212-2. In the presence of strontium in the bath, the frequency but not the amplitude of asynchronous synaptic events evoked in layer V pyramidal cells by stimulating layer V afferents, was markedly decreased (-54.2 +/- 8%), indicating a presynaptic site of action of cannabinoids at these synapses. Tetanic stimulation (100 pulses at 100 Hz, 4 trains) induced in control condition, no changes (n = 7/18), long-term depression (LTD; n = 6/18), or long-term potentiation (LTP; n = 5/18) of monosynaptic EPSCs evoked by stimulation of layer V afferents. When tetanus was applied in the presence of WIN 55,212-2 or SR141716-A (1 microM) in the bath, the proportion of "nonplastic" cells were not significantly changed (n = 7/15 in both cases). For the plastic ones (n = 8 in both cases), WIN 55,212-2 strongly favored LTD (n = 7/8) at the apparent expense of LTP (n = 1/8), whereas the opposite effect was observed with SR141716-A (7/8 LTP; 1/8 LTD). These results demonstrate that cannabinoids influence glutamatergic synaptic transmission and plasticity in the PFC of rodent.

Animals↗
PubMed2000

Interleukin-1beta induces elevation of spermidine/spermine N1-acetyltransferase activity and an increase in the amount of putrescine in synovial adherent cells from patients with rheumatoid arthritis.

OBJECTIVE: To investigate polyamine metabolism in rheumatoid synovial adherent cells stimulated by interleukin- 1beta (IL-1beta). METHODS: Synovial adherent cells obtained from patients with rheumatoid arthritis (RA) were cultured and incubated in the presence or absence of human recombinant IL-1beta at a concentration of 10 ng/ml for 24 h. The cellular contents of polyamines as well as the activities of spermidine/spermine N1-acetyltransferase (SAT) and ornithine decarboxylase (ODC) were measured. RESULTS: Polyamines in synovial adherent cells decreased significantly after 24 h incubation in the absence of IL-1beta. However, in the presence of IL-Ibeta, putrescine and N'-acetylspermidine increased significantly. No significant difference was observed between the amount of spermidine in synovial adherent cells incubated with and without IL-1beta. Spermine and N8-acetylspermidine in synovial adherent cells incubated with IL-1beta decreased significantly more than in synovial adherent cells incubated without. SAT activity reached a peak 12 h after the addition of IL-1beta and then decreased, while the ODC activity did not increase. SAT activity was elevated by the addition of IL-1beta in a dose dependent manner. CONCLUSION: An increase in the putrescine level in rheumatoid synovial adherent cells as a result of the elevation of SAT activity induced by IL-1beta may play a role in RA.

Acetyltransferases↗
PubMed1999

Dopamine receptors and groups I and II mGluRs cooperate for long-term depression induction in rat prefrontal cortex through converging postsynaptic activation of MAP kinases.

Tetanic stimuli to layer I-II afferents in rat prefrontal cortex induced long-term depression (LTD) of layer I-II to layer V pyramidal neuron glutamatergic synapses when tetani were coupled to bath application of dopamine. This LTD was blocked by the following metabotropic glutamate receptor (mGluR) antagonists coapplied with dopamine: (S)-alpha-methyl-4-carboxyphenylglycine (MCPG; group I and II antagonist), (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA; group I antagonist), or (RS)-alpha-methylserine-O-phosphate monophenyl ester (MSOPPE; group II antagonist). This suggests that the dopamine-facilitated LTD requires synaptic activation of groups I and II mGluRs during tetanus. LTD could also be induced by coupling tetani to bath application of groups I and II mGluR agonist (1S, 3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD). In the next series of experiments, coapplication of dopamine and 1S,3R-ACPD, but not application of either drug alone, consistently induced LTD without tetani or even single test stimuli during drug application, suggesting that coactivation of dopamine receptors and the mGluRs is sufficient for LTD induction. Immunoblot analyses with anti-active mitogen-activated protein kinases (MAP-Ks) revealed that D1 receptors, D2 receptors, group I mGluRs, and group II mGluRs all contribute to MAP-K activation in prefrontal cortex, and that combined activation of dopamine receptors and mGluRs synergistically or additively activate MAP-Ks. Consistently, LTD by dopamine + 1S, 3R-ACPD coapplication, as well as the two other forms of LTD (LTD by dopamine + tetani and LTD by 1S,3R-ACPD + tetani), was blocked by bath application of MAP-K kinase inhibitor PD98059. LTD by dopamine + 1S,3R-ACPD coapplication was also blocked by postsynaptic injection of synthetic MAP-K substrate peptide. Our results suggest that dopamine receptors and groups I and II mGluRs cooperate to induce LTD through converging postsynaptic activation of MAP-Ks.

Animals↗
PubMed1999

Inhibition of liver glutathione S-transferase placental form-positive foci development in the rat hepatocarcinogenesis by Porphyra tenera (Asakusa-nori).

The effects of Asakusa-nori, Porphyra tenera (PT), a popular edible seaweed in Japan, on the development of putative preneoplastic lesions, glutathione S-transferase placental form (GST-P)-positive foci, in the male F344 rat liver were examined using a medium-term bioassay system. PT significantly decreased both the number and area of GST-P-positive foci in rat livers initiated with diethylnitrosamine (DEN). To investigate possible mechanisms of inhibition, effects of PT on 5-bromo-2'-deoxyuridine (BrdU) labeling in GST-P-positive foci and the surrounding area of hepatocytes were studied. The ratio of the GST-P-positive foci to surrounding tissue labeling indices was decreased in the PT-treated group as compared with the DEN alone group. Ornithine decarboxylase activity in the liver was slightly increased and spermidine/spermine N'-acetyltransferase activity was slightly decreased in the PT-treated animals. These results suggest that PT possesses chemopreventive effects against DEN-induced hepatocarcinogenesis.

Acetyltransferases↗
PubMed1999

Potent suppressive effect of a Japanese edible seaweed, Enteromorpha prolifera (Sujiao-nori) on initiation and promotion phases of chemically induced mouse skin tumorigenesis.

Potent antigenotoxic and anti-tumor promoting activities of a Japanese edible seaweed, Enteromorpha prolifera (Sujiao-nori in Japanese) were previously identified using an in vitro cell culture experiment (Y. Okai, K. Higashi-Okai, S. Nakamura, Y. Yano, S. Otani, Cancer Lett. 87 (1994) 25-32). However, in vivo anti-carcinogenic activity of this seaweed has not been elucidated until now. In the present study, the anticarcinogenic activity of E. prolifera was analyzed using an initiation and promotion model experiment of mouse skin tumorigenesis caused by 7,12-dimethylbenz[a]anthracene (initiator) and 12-O-tetradecanoylphorbol-13-acetate (promoter). (1) Application of the extract of E. prolifera prior to the treatment with a tumor initiator or promoter caused a significant suppression against skin tumorigenesis, and the combined application of the extract prior to both treatments with initiator and promoter exhibited much stronger suppression against the same skin tumorigenesis. (2) As a possible active principle for the anticarcinogenic activity of the extract, we propose a chlorophyll-related compound, pheophytin-a, which has been recently identified in the extract of this alga as an antigenotoxic substance (Y. Okai, K. Higashi-Okai, J. Sci. Food Agric. 74 (1997) 531-535), and showed significant suppressive effects in the same tumorigenesis experiment. These results suggest that E. prolifera has a potent suppressive activity against chemically induced mouse skin tumorigenesis through the suppression at the initiation and promotion phases, and that pheophytin-a might be partially associated with the in vivo anticarcinogenic activity.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

Colocalization of leptin receptor (OB-R) mRNA and placental lactogen-II in rat trophoblast cells: gestational profile of OB-R mRNA expression in placentae.

The present study was designed to clarify the cellular localization and expression of leptin receptor(s) [OB-R(s)] mRNA including its splice variants and their correlation with the cells which secrete placental hormone, placental lactogen-II (PL-II), in rat placentae. By in situ hybridization analysis, hybridization signals for OB-Rb and the common extracellular domain of OB-R were first detectable in some cells of the labyrinth zone of the placentae on day 14 of pregnancy and then a lot of cells dispersed in the entire area of the labyrinth zone expressed OB-Rb during the latter half of pregnancy. However, no expression was observed in the decidua and the junctional zone of the placentae during pregnancy. Double staining study revealed that signals for OB-R expressing trophoblast cells showed PL-II immunoreactivity in the labyrinth zone of the placentae. In Northern blot analysis, two bands (2.8 kb and 5.1 kb) of OB-R mRNA expression were observed in the placentae from day 17 to 21 of pregnancy and the expression of both increased markedly up to day 21 of pregnancy. RT-PCR analysis revealed that OB-Rb, OB-Ra, and OB-Re are expressed in the placentae on days 19 and 21 of pregnancy. These results suggest that the OB-R may have a physiological significance in the placental function during the latter half of pregnancy.

Alternative Splicing↗
PubMed1999

Thiols and polyamines in the cytoprotective effect of taurine on carbon tetrachloride-induced hepatotoxicity.

The mechanism by which taurine (2-aminoethanesulfonic acid) protects hepatocytes injury induced by carbon tetrachloride (CCl4) is not fully understood. In a previous study, we reported that cellular polyamines play an important role in this mechanism. The relationship between cellular glutathione (GSH), protein-SH levels, and lactate dehydrogenase (LDH), with respect to the effect of polyamine on the cytoprotective ability of taurine in CCl4-induced toxicity in isolated rat hepatocytes, was examined. CCl4 induced a LDH release and decreased cellular thiols and polyamine levels. Treating with taurine reversed these depletions. The effect of CCl4 was also reversed by the addition of exogenous polyamines. Pretreating with alpha-difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, which is a key enzyme in polyamine biosynthesis and therefore used to deplete cellular polyamine, prevented the protective effect of taurine. Adding diethyl maleate, a cellular glutathione-depleting agent, reduced the effect of exogenous polyamines. The role of polyamine in the cytoprotective effect of taurine in CCl4-induced toxicity may therefore be by preventing, among others, GSH and protein-SH depletions.

Animals↗
PubMed1999

Possible contribution to hepatocarcinogenesis of X transcript of hepatitis B virus in Japanese patients with hepatitis C virus.

Serological research suggests that hepatitis B virus (HBV) and hepatitis C virus (HCV) are associated with the development of hepatocellular carcinoma (HCC). It is unclear how genes of hepatitis viruses participate in hepatocarcinogenesis in patients infected with HCV. We investigated the expression of hepatitis virus-related RNAs in resected liver from 51 patients with HCV antibodies (Ab) and without hepatitis B surface antigen (HBsAg). mRNA transcripts of the genes HBx, HBc, HBs, nonstructural (NS) region 3 of HCV, the 5'-untranslated region (UTR) of HCV, and the 5'-UTR of hepatitis G virus (HGV) were amplified by reverse-transcription polymerase chain reaction (RT-PCR) with specific primers for each gene. The HBx transcript was detected in 19 (37%) tumors and in 8 (16%) specimens of noncancerous tissues (P =.014). The NS3 gene of HCV was detected in 35 (69%) tumors and 41 (80%) noncancerous tissues. HGV RNA was detected in 3 tumors (6%). Patients with HBx transcripts were younger than patients without HBx transcripts (P =.012). HBx transcripts were detected in 3 (33%) of 9 well-differentiated HCCs, in 8 (31%) of 26 moderately differentiated HCCs, and in 8 (50%) of 16 poorly differentiated HCCs. Codon 130 (AAG) and codon 131 (GTC) of HBx were changed to ATG and ATC, respectively, in all HCCs with HBx transcripts. In conclusion, we found that the HBx gene was expressed in many HCCs; the gene might promote hepatocarcinogenesis in patients with HCVAb and without HBsAg, but HGV is not closely related to hepatocarcinogenesis in such patients.

Base Sequence↗
PubMed1999

Deletion of the trichodiene synthase gene of Fusarium venenatum: two systems for repeated gene deletions.

The trichodiene synthase (tri5) gene of Fusarium venenatum was cloned from a genomic library. Vectors were created in which the tri5 coding sequence was replaced with the Neurospora crassa nitrate reductase (nit3) gene and with the Aspergillus nidulans acetamidase (amdS) gene flanked by direct repeats. The first vector was utilized to transform a nitrate reductase (niaD) mutant of F. venenatum to prototrophy, and the second vector was utilized to confer acetamide utilization to the wild-type strain. Several of the transformants lost the capacity to produce the trichothecene diacetoxyscirpenol and were shown by hybridization analysis to have gene replacements at the tri5 locus. The nit3 gene was removed by retransformation with a tri5 deletion fragment and selection on chlorate. The amdS gene was shown to excise spontaneously via the flanking direct repeats when spores were plated onto fluoroacetamide.

Amidohydrolases↗
PubMed1999

Prevalence of TT virus in patients with fulminant hepatic failure in Japan.

A novel virus (TT virus) was isolated from patients with posttransfusion hepatitis of unknown etiology. We studied the prevalence of TT virus in 26 patients with fulminant hepatic failure without risk factors, including blood transfusion, and also examined 106 healthy blood donors as controls. We assayed serum TT virus DNA by seminested polymerase chain reactions and also examined the genotypes of this virus. Serum was obtained at admission from patients with fulminant hepatic failure. Serum samples at admission from seven (27%) of the 26 patients were positive for TT virus DNA. There were no differences in clinical findings, duration from onset to coma, or results of laboratory tests in patients with and without TT virus DNA. However, all 7 patients with TT virus died, whereas 9 of the 19 patients without TT virus died. The outcome for patients with fulminant hepatic failure and TT virus was significantly worse than for patients without the virus (P = 0.0227). TT virus was also detected in 29 (27%) of the 106 healthy blood donors. The genotype of the TT virus was mainly 1a in both groups. There were no differences in the rate of positivity and the genotypes of TT virus between patients with fulminant hepatic failure and healthy blood donors. TT virus infection may not cause severe hepatitis, such as fulminant hepatic failure, but it may indicate a poor outcome in such patients.

Adolescent↗