Complete genome structure of the nitrogen-fixing symbiotic bacterium Mesorhizobium loti

The complete nucleotide sequence of the genome of a symbiotic bacterium Mesorhizobium loti strain MAFF303099 was determined. The genome of M. loti consisted of a single chromosome (7,036,071 bp) and two plasmids, designated as pMLa (351,911 bp) and pMLb (208, 315 bp). The chromosome comprises 6752 potential protein-coding genes, two sets of rRNA genes and 50 tRNA genes representing 47 tRNA species. Fifty-four percent of the potential protein genes showed sequence similarity to genes of known function, 21% to hypothetical genes, and the remaining 25% had no apparent similarity to reported genes. A 611-kb DNA segment, a highly probable candidate of a symbiotic island, was identified, and 30 genes for nitrogen fixation and 24 genes for nodulation were assigned in this region. Codon usage analysis suggested that the symbiotic island as well as the plasmids originated and were transmitted from other genetic systems. The genomes of two plasmids, pMLa and pMLb, contained 320 and 209 potential protein-coding genes, respectively, for a variety of biological functions. These include genes for the ABC-transporter system, phosphate assimilation, two-component system, DNA replication and conjugation, but only one gene for nodulation was identified.

Sequence and analysis of chromosome 3 of the plant Arabidopsis thaliana

Arabidopsis thaliana is an important model system for plant biologists. In 1996 an international collaboration (the Arabidopsis Genome Initiative) was formed to sequence the whole genome of Arabidopsis and in 1999 the sequence of the first two chromosomes was reported. The sequence of the last three chromosomes and an analysis of the whole genome are reported in this issue. Here we present the sequence of chromosome 3, organized into four sequence segments (contigs). The two largest (13.5 and 9.2 Mb) correspond to the top (long) and the bottom (short) arms of chromosome 3, and the two small contigs are located in the genetically defined centromere. This chromosome encodes 5,220 of the roughly 25,500 predicted protein-coding genes in the genome. About 20% of the predicted proteins have significant homology to proteins in eukaryotic genomes for which the complete sequence is available, pointing to important conserved cellular functions among eukaryotes.

Renin-producing adrenal tumor: report of a case

A 19-year-old man with an adrenal tumor associated with hypertension is herein described. The plasma renin activity (PRA) was markedly elevated and the plasma aldosterone level was also increased. The catecholamine level was within the normal range and the glucagone-regitine test was negative. An angiogram revealed the left renal artery to have no stenotic segments, but instead was curved caudally. Magnetic resonance imaging showed a tumor measuring about 8 cm in diameter to be clearly recognized from the left kidney. The blood pressure did not drop when a calcium-channel blocker was used, but was gradually stabilized with the angiotensin converting enzyme (ACE) antagonist. The adrenal tumor was then removed surgically. Normal adrenal tissue was scarcely recognized to the left of the tumor. After surgery, the PRA decreased and blood pressure stabilized rapidly without the ACE antagonist. The possibility of massive renal renin secretion due to suppression by the adrenal tumor was excluded by a method using an antibody to purified human renin.

Involvement of calcineurin in Ca2+ paradox-like injury of cultured rat astrocytes

The Ca2+/calmodulin-dependent phosphatase calcineurin may have physiological and pathological roles in neurons, but little is known about the roles of the enzyme in glial cells. We have previously reported that reperfusion of cultured astrocytes in Ca2+-containing medium after exposure to Ca2+-free medium caused Ca2+ influx followed by delayed cell death. In this study, we examined if calcineurin is involved in this Ca2+-mediated astrocytic injury. FK506, an inhibitor of calcineurin, protected cultured rat astrocytes against paradoxical Ca2+ challenge-induced injury in a dose-dependent manner (10(-10)-10(-8) M). Cyclosporin A at 1 microM mimicked the effect of FK506. Rapamycin (1 microM) did not affect astrocyte injury, but it blocked the protective effect of FK506. Deltamethrin (20 nM), another calcineurin inhibitor, had a similar protective effect, whereas okadaic acid did not. FK506 affected neither paradoxical Ca2+ challenge-induced increase in cytosolic Ca2+ level nor Na+-Ca2+ exchange activity in the cells, suggesting that the calcineurin is involved in processes downstream of increased cytosolic Ca2+ level. Immunochemical studies showed that both calcineurin A (probably the A beta2 isoform) and B subunits were expressed in the cells. It is concluded that calcineurin is present in cultured astrocytes and it has a pathological role in the cells.

Role of Na(+)-Ca2+ exchanger in agonist-induced Ca2+ signaling in cultured rat astrocytes

We have previously demonstrated that activation of the Na(+)-Ca2+ exchanger in the reverse mode causes Ca2+ influx in astrocytes. In addition, we showed that the exchange activity was stimulated by nitric oxide (NO)/cyclic GMP and inhibited by ascorbic acid. The present study demonstrates that the Na(+)-Ca2+ exchanger is involved in agonist-induced Ca2+ signaling in cultured rat astrocytes. The astrocytic intracellular Ca2+ concentration ([Ca2+]i) was increased by L-glutamate, noradrenaline (NA), and ATP, and the increases were all attenuated by the NO generator sodium nitroprusside (SNP). SNP also reduced the ionomycin-induced increase in [Ca2+]i. The NA-induced Ca2+ signal was also attenuated by S-nitroso-L-cysteine and 8-bromo cyclic GMP, whereas it was enhanced by 3,4-dichlorobenzamil, an inhibitor of the Na(+)-Ca2+ exchanger. Treatment of astrocytes with antisense, but not sense, deoxynucleotides to the sequence encoding the Na(+)-Ca2+ exchanger enhanced the ionomycin-induced increase in [Ca2+]i and blocked the effects of SNP and 8-bromo cyclic GMP in reducing the NA-induced Ca2+ signal. Furthermore, the ionomycin-induced Ca2+ signal was enhanced by removal of extracellular Na+ and pretreatment with ascorbic acid. These findings indicate that the Na(+)-Ca2+ exchanger is a target for NO modulation of elevated [Ca2+]i and that the exchanger plays a role in Ca2+ efflux when [Ca2+]i is raised above basal levels in astrocytes.

Heat shock protects cultured rat astrocytes in a model of reperfusion injury

We have previously found that incubation of cultured rat astrocytes in Ca(2+)-free medium caused an increase in intracellular Ca2+ ([Ca2+]i) followed by delayed cell death. Here, we examined whether thermal stress protects astrocytes from cell death in this model system of reperfusion injury. Cultured astrocytes were preincubated at 40-44 degrees C for 10-20 min in fetal calf serum-free medium, incubated at 37 degrees C for 24 h in serum-containing medium, and subjected to the in vitro reperfusion experiment. Thermal stress attenuated reperfusion-induced cell toxicity. Furthermore, the stress increased cell viability after incubation with serum-free medium containing Ca2+. These effects of heat shock required incubation in serum-containing medium for at least 12 h after heat shock, and it was blocked by the protein synthesis inhibitor cycloheximide. Thermal stress increased synthesis of several proteins, and one of the inducible proteins was identified as the 72-kDa heat shock protein by an immunoblot analysis. Neither the increase in [Ca2+]i nor the Na(+)-Ca2+ exchange activity in astrocytes induced in this model were affected by thermal stress. These findings suggest that heat shock proteins protect astrocytes from cell death in a model of reperfusion injury and they may affect processes down stream of the increase in [Ca2+]i.

Ca2+ depletion facilitates taurine release in cultured rat astrocytes

Removal of external Ca2+ facilitated endogenous taurine release in cultured rat astrocytes. The stimulated release was not affected by furosemide, sucrose, tetrodotoxin and 3,4-dichlorobenzamil, but partially inhibited by nifedipine. Omission of external Na+ increased basal taurine release, and the effects of Na+ removal and Ca2+ depletion on the release were additive. The Na(+)-free condition did not affect Ca2+ paradox-induced cell death in astrocytes. These findings suggest that Ca2+ depletion facilitates taurine release in a mechanism independent of volume and the Na+ gradient and that the release is not involved in Ca2+ paradox-induced delayed cell toxicity in astrocytes.

Protective effect of taurine against reperfusion injury in cultured rat astrocytes

Reperfusion of cultured rat astrocytes with Ca(2+)-containing medium after exposure to Ca(2+)-free medium for a short time caused an increase in intracellular Ca2+ ([Ca2+]i), and delayed cell death (Ca2+ paradox-like injury). Exposure of astrocytes to Ca(2+)-free medium caused a marked release of taurine. Taurine (3-30 mM) reduced the reperfusion-induced increase in [Ca2+]i and attenuated the delayed glial cell death. Glycine, GABA and beta-alanine did not affect reperfusion-induced cell toxicity. The protective effect of taurine required addition at an early time during reperfusion. Ouabain and monensin mimicked reperfusion injury and their toxicity was also reduced by taurine. Taurine (3-30 mM) inhibited dose-dependently 45Ca2+ uptake stimulated by ouabain and monensin in astrocytes. These findings suggest that taurine has a protective effect against reperfusion injury via an inhibition of Na+/Ca2+ exchange activity in the reverse mode.

Predictive factors for efficacy of interferon therapy in chronic hepatitis type C

BACKGROUND/AIMS

It has recently become possible to quantify HCV-RNA in serum and to analyze the HCV-RNA genotype. In this study, we investigated the relationship among the response to interferon therapy, the HCV-RNA concentration, genotype and histological findings of the liver.

PATIENTS AND METHODS

Sixty-three patients with chronic hepatitis type C received interferon alfa therapy for 24 weeks. The HCV-RNA concentration in serum was measured semiquantitatively with reverse transcript semi-nested polymerase chain reaction and classified as negative to +3. HCV-RNA genotype was analyzed using a mixture of four type specific primers.

RESULTS

HCV-RNA concentration was significantly higher in patients with genotype II and CAH2B than genotype III, CPH and CAH2A (p < 0.05). At 24 weeks after the end of interferon therapy, HCV-RNA in serum disappeared in 24 of 63 patients (38%). Strong resistance to the therapy was noted in patients with both genotype II and a high concentration of HCV-RNA in serum (the efficacy was only 7%). Therapy efficacy decreased with the severity of liver histological findings, reaching only 20% in those with CAH2B.

CONCLUSION

Both the concentration and genotype of HCV-RNA seem to be important factors in determining the efficacy of interferon therapy.

Ability of prolonged interferon treatment to suppress relapse after cessation of therapy in patients with chronic hepatitis C: a multicenter randomized controlled trial

The aim of this study was to determine whether 12 months course of interferon alfa (IFN-alpha) therapy could improve the beneficial effect of IFN in chronic hepatitis C. Eighty-eight patients were treated with natural IFN-alpha for either 28 weeks (45 cases) or 52 weeks (43 cases). Sustained response was achieved in 15 (33.3%) of 45 cases treated for 28 weeks and in 23 (53.5%) of 43 cases treated for 52 weeks. Transient response with relapse of alanine transaminase (ALT) after completion of therapy was observed in 13 cases (28.9%) treated for 28 weeks and in 4 cases (9.3%) treated for 52 weeks. Thus, ALT relapse was suppressed by prolonged IFN treatment. No response was found in 17 cases (37.8%) treated for 28 weeks and in 16 cases (37.2%) treated for 52 weeks, indicating that approximately 38% of the patients with chronic hepatitis C were resistant to IFN therapy even with prolonged treatment. The rate of sustained response was significantly higher in patients with type 2a or 2b than in those with type 1b. Even in type 1b cases, it was higher in the 52-week treatment group than in the 28-week treatment group, and the rate of transient response was lower in the 52-week treatment group, indicating that relapse in type 1b cases was suppressed by prolonged IFN therapy. IFN therapy was not effective for patients with advanced liver fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Three-dimensional display of liver, spleen, hepatoma, and blood vessels by MR imaging and computer graphics

The technique of generating 3-D images from CT and MR data has made progress. Manipulation of the images has become simpler, the processing time shorter, and the quality better. Clinical application of this technique has been performed for images of brain (5, 7, 8) and bone (1, 2, 6), but only a few studies have been done of abdominal organs (3, 4).

Pulmonary venoocclusive disease in a patient with systemic lupus erythematosus

A 26-year-old woman with systemic lupus erythematosus (SLE) developed dyspnea and hypoxemia on exertion. She died from rapidly progressive respiratory failure. Autopsy revealed right ventricular hypertrophy and occlusion of the pulmonary veins compatible with pulmonary venoocclusive disease (PVOD). Although PVOD has been reported in patients with suspected collagen vascular disease, this appears to be the first reported case of PVOD occurring in a patient with SLE.

Prevalence of hepatitis C virus in family members of patients with hepatitis C

To investigate the prevalence of hepatitis C virus in the family members of patients with hepatitis C, we examined antibody to hepatitis C virus with a second-generation enzyme-linked immunosorbent assay and viral RNA with a combined assay of reverse transcription and polymerase chain reaction in sera. Among 219 (75 spouses, 110 children, and 34 others), 26 (12%) were antibody positive. The positive rate of antibody to hepatitis C virus was significantly higher than that of the control group (2.0%) and of volunteer blood donors in our district (1.5%), and it increased with age. In particular, the positive rate of antibody to hepatitis C virus among spouses was high (24%). Among family members with elevated ALT, 59% were antibody positive, which was significantly higher than that of the control group (11%). Of the 26 who were antibody positive, 21 (81%) had viral RNA, whereas of the 70 who were antibody negative, only one (1.4%) had viral RNA. These data suggest that hepatitis C virus was transmitted by the infrafamilial route during long duration of contact with patients or sexual transmission. In family members, hepatitis C viral infection is the main cause of liver disorder, and many who were antibody-positive with a second-generation enzyme-linked immunosorbent assay had viremia in the sera.

[Research and development of pravastatin]

The attempts to find a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase which catalyzes the rate limiting step of cholesterol biosynthesis were started from 1971. The first potent inhibitor, ML-236B (compactin), was found from the culture broth of Penicillium citrinum. Among many derivatives of ML-236B, pravastatin sodium (hereafter refer to pravastatin) was finally selected because of its potency and tissue selectivity. Since pravastatin has a hydroxyl group at 6 beta position in the skeleton of decaline of ML-236B, the microbial hydroxylation was adopted for the production of pravastatin. Streptomyces carbophilus was finally chosen as a potent converter with the formation of a lesser amount of by-products. For the sake of industrial production of pravastatin, many devices and improvements were performed for selecting high potent strains and for culturing conditions both with ML-236B and pravastatin. Pravastatin strongly inhibited the sterol synthesis in freshly isolated rat hepatocytes, but only weakly inhibited in the cells from nonhepatic tissues. This selective inhibition of pravastatin in sterol synthesis was further confirmed by ex vivo and in vivo experiments by using rats and mice. Pravastatin markedly reduced serum cholesterol levels in dogs, monkeys and rabbits, including Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model for familial hypercholesterolemia. Pravastatin showed the preventive effect on the development of coronary atherosclerosis and xanthoma in young WHHL rabbits in consequence of maintaining the serum cholesterol levels low. In the clinical trials, pravastatin significantly reduced serum cholesterol and low density lipoprotein cholesterol levels, whereas inversely increased high density lipoprotein cholesterol levels.

Management of congenital diaphragmatic hernia by extracorporeal membrane oxygenation (ECMO)

The purpose of this study was to evaluate the efficacy of extracorporeal membrane oxygenation (ECMO) for patients with congenital diaphragmatic hernia (CDH). Ten patients whose mortality was predicted to be more than 80% with previous therapeutics, were selected to use ECMO over the past five years. Patients were placed on ECMO by cannulating the right jugular vein and the right carotid artery. ECMO was started at 34.3 hours after birth on an average, and the average time on ECMO was 96.3 hours. Seven patients (70%) survived, and six out of them are in good health without any sequelae. In particular, all five patients whose pathological condition needing ECMO was persistent fetal circulation (PFC), survived. Therefore we believe ECMO is highly beneficial to overcome the condition of PFC. The survival rate of CDH patients under 24 hours of age in our hospital is 76.2% (16/21 cases) over the last 5 years, and it has improved compared with 57.1% (12/21 cases) before then. The fact that some of the critical patients who were lethal with conventional management, have been successfully treated by ECMO, played a great role in this improvement.

Fv-1 restriction of endogenous feline C-type RD114 virus genome phenotypically mixed with ecotropic murine leukemia viruses

Endogenous feline leukemia RD114 virus genome rendered capable of infecting mouse cells by phenotypic mixing with an ecotropic murine leukemia virus (MuLV) exhibited the Fv-1 restriction pattern of the ecotropic murine virus. However, RD114 genomes phenotypically mixed with ecotropic MuLV showed one-hit dose-response kinetics, even when titrated with murine cells with the restricted Fv-1 phenotype.

Mutational analysis of the human immunodeficiency virus vpr open reading frame

Mutations were introduced by recombinant DNA techniques into the vpr open reading frame of an infectious molecular clone of human immunodeficiency virus type 1. The effect of these changes on the replicative and cytopathologic properties of the virus recovered from transfected cells was studied in several human CD4+ lymphocyte cell lines. In all cases, mutant viruses were infectious and cytopathic. However, when a low-input dose was used, mutants grew significantly more slowly than the wild-type virus. The growth kinetics of vpr mutants were distinct from those of vif and vpu mutants.