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Biomedical subjects

T Iida

Publications and source records attributed to T Iida.

At least 91 records · Page 5Linked to original sources
PubMed2000

FK506 binding protein from a thermophilic archaeon, Methanococcus thermolithotrophicus, has chaperone-like activity in vitro.

The in vitro protein folding activity of an FKBP (FK506 binding protein, abbreviated to MTFK) from a thermophilic archaeon, Methanococcus thermolithotrophicus, was investigated. MTFK exhibited FK506 sensitive PPIase (peptidyl prolyl cis-trans isomerase) activity which accelerated the speed of ribonuclease T1 refolding, which is rate-limited by isomerization of two prolyl peptide bonds. In addition, MTFK suppressed the aggregation of folding intermediates and elevated the final yield of rhodanese refolding. We called this activity of MTFK the chaperone activity. The chaperone activity of MTFK was also inhibited by FK506. Alignment of the amino acid sequences of MTFK with human FKBP12 showed that MTFK has two insertion sequences, consisting of 13 and 44 amino acids, at the N- and C-termini, respectively [Furutani, M., Iida, T., Yamano, S., Kamino, K., and Maruyama, T. (1998) J. Bacteriol. 180, 388-394]. To study the relationship between chaperone and PPIase activities of MTFK, mutant MTFKs with deletions of these insertion sequences or with amino acid substitutions were created. Their PPIase and chaperone activities were measured using a synthetic oligopeptide and denatured rhodanese as the substrates, respectively. The far-UV circular dichroism spectra of the wild type and the mutants were also analyzed. The results suggested that (1) the PPIase activity did not correlate with chaperone activity, (2) both insertion sequences were required for MTFK to take a proper conformation, and (3) the insertion sequence (44 amino acids) in the C-terminus was important for the chaperone activity.

Binding Sites↗
PubMed2000

Role of apoptosis induction in both peripheral lymph nodes and thymus in progressive loss of CD4+ cells in SHIV-infected macaques.

To investigate the role of apoptosis in the progressive loss of CD4+ lymphocytes in HIV infection, we have used macaques infected with SHIV, a hybrid virus of HIV and simian immunodeficiency virus (SIV). In the present study, we sequentially analyzed apoptosis induction in the acute phase of SHIV infection. Four macaques infected with a pathogenic SHIV, SHIV89.6P, and four macaques infected with a nonpathogenic SHIV, NM-3rN, were analyzed during the first 2 or 4 weeks postinfection. In the 89.6P-infected macaques the number of peripheral CD4+ cells sharply decreased at 2 weeks postinfection and was maintained below 50/microl until 4 weeks postinfection, while in the NM-3rN-infected macques the number of the CD4+ cells did not change significantly. Plasma viral loads peaked at 2 and 2-3 weeks postinfection, and the peak values were about 1 x 10(9) and 10(6)-10(7) copies/ml in the 89.6P- and the NM-3rN-infected macaques, respectively. In the 89.6P-infected macaques, Fas antigen expression and the extent of apoptosis in PBMCs and peripheral lymph nodes increased at 1-2 weeks postinfection. A high number of apoptotic cells was also observed in thymus sections 2 and 4 weeks postinfection. On the other hand, apoptosis was scarcely induced in the NM-3rN-infected macaques. These results suggest that the extent of apoptosis induction is closely correlated with the pathogenicity of SHIV and that the apoptosis induction in peripheral lymphoid tissues and thymus, where T cell maturation occurs, may play an important role in the depletion of CD4+ lymphocytes in 89.6P infection.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Optical coherence tomographic features of idiopathic submacular choroidal neovascularization.

PURPOSE: To clarify the morphologic features of idiopathic submacular choroidal neovascularization using optical coherence tomography. METHODS: Using optical coherence tomography, we prospectively examined 17 consecutive eyes (17 patients; eight men, nine women; mean age +/- SD, 36.0 +/- 9.3 years) with idiopathic submacular choroidal neovascularization. During the follow-up period (mean +/- SD, 7.5 +/- 3.8 months), we repeated optical coherence tomography in 15 eyes; optical coherence tomography was performed only at the initial examination in two eyes that underwent submacular surgery. RESULTS: Choroidal neovascularization was observed in the subsensory retinal space anterior to the retinal pigment epithelium as a highly or moderately reflective mass, which protruded from the retinal pigment epithelium in 13 of 17 eyes (protruding type). In four eyes, choroidal neovascularization was a highly reflective fusiform mass at the level of the retinal pigment epithelium and choriocapillaris (fusiform type). During the follow-up period, choroidal neovascularization regressed and the protruding mass became a highly reflective fusiform mass in 10 of 11 eyes with the protruding type that underwent repeated examination. In three of the 10 eyes, during 5 to 10 months from initial examination, the choroidal neovascularization was exacerbated and it again protruded into the subsensory retinal space anterior to the retinal pigment epithelium. Four eyes with the fusiform type remained the same throughout the follow-up period. The overlying retina was thickened and had low reflectivity in all 17 eyes at the initial examination. Optical coherence tomography identified subretinal fluid in only 11 of the 13 eyes with protruding type choroidal neovascularization. CONCLUSIONS: Optical coherence tomography confirmed subsensory retinal location of idiopathic submacular choroidal neovascularization anterior to the retinal pigment epithelium. Protruding choroidal neovascularization transforms to fusiform tissue at the level of the retinal pigment epithelium during the process of regression. Sensory retinal edema was always associated with choroidal neovascularization.

Adult↗
PubMed2000

Optical coherence tomography of orange-red subretinal lesions in eyes with idiopathic polypoidal choroidal vasculopathy.

PURPOSE: To study the cross-section images of orange-red lesions in eyes with idiopathic polypoidal choroidal vasculopathy and compare their protrusions quantitatively with those of serous retinal pigment epithelium detachment. METHODS: Optical coherent tomography images scanning remarkable orange-red lesions in eyes with idiopathic polypoidal choroidal vasculopathy and serous retinal pigment epithelium detachment in age-related macular degeneration or central serous chorioretinopathy were prospectively recorded. The correlation between the base diameter and the height of the lesions was analyzed. RESULTS: Optical coherence tomography images show prominent anterior protrusion of the orange-red lesions. The ratio of the height to the base diameter of the orange-red lesions in eyes with idiopathic polypoidal choroidal vasculopathy is 0.32+/-0.05, and it is significantly larger than lesions in eyes with serous retinal pigment epithelium detachment (0.18+/-0.05, P< .001). CONCLUSION: The orange-red lesions in eyes with idiopathic polypoidal choroidal vasculopathy have a more sharply peaked shape than serous retinal pigment epithelium detachment as a subretinal structure, suggesting polypoidal vascular lesions in eyes with idiopathic polypoidal choroidal vasculopathy are situated beneath the Bruch membrane and covered anteriorly with both the retinal pigment epithelium and the Bruch membrane.

Aged↗
PubMed2000

Evaluation of central serous chorioretinopathy with optical coherence tomography.

PURPOSE: To evaluate central serous chorioretinopathy with optical coherence tomography during the acute phase and after resolution of the acute phase. METHODS: In a prospective study, 23 consecutive eyes of 23 patients (19 men, four women; mean age +/- SD, 46.0+/-8.1 years; range, 29 to 60 years) with central serous chorioretinopathy were examined with optical coherence tomography during the acute phase and after resolution of the retinal detachment. After the initial examination, the patients were reexamined for 3 to 6 months (mean, 4.7+/-1.1 months). Cross-sectional retinal images through the center of the fovea were obtained from all eyes by optical coherence tomography. The retinal thickness at the center of the fovea was measured. The difference between the retinal thickness during the acute phase and after resolution of the retinal detachment was statistically analyzed using the Wilcoxon test. We also examined a grayish-white lesion that corresponded to the leakage point in fluorescein angiography in four eyes. RESULTS: In the acute phase, neurosensory retina was thickened within the area of serous retinal detachment in all 23 eyes. The detached retina was thicker than the reattached retina after resolution of the retinal detachment in all eyes. The retinal thickness at the center of the fovea during the acute phase (range, 157 to 236 microm; mean +/- SD, 196.9+/-22.6 microm) was significantly thickened compared with that after resolution (range, 105 to 152 microm; mean +/- SD, 124.8+/-10.7 microm; P<.0001, Wilcoxon test). In the acute phase, areas of low reflectivity localized within the detached retina were observed in 18 of the 23 eyes. In the area of the grayish-white lesion, optical coherence tomography showed a moderately reflective mass bridging the detached neurosensory retina and retinal pigment epithelium in the four eyes; the outer layer of the detached retina was more highly reflective in these eyes. The retinal pigment epithelium was focally detached beneath the subretinal reflective mass in three of the four eyes. CONCLUSIONS: In all eyes studied, neurosensory retina was thickened within the area of serous retinal detachment in the acute phase of central serous chorioretinopathy. The grayish-white lesion seems to be a fibrinous exudate that accumulates in the subretinal space and infiltrates into the outer retina.

Acute Disease↗
PubMed2000

Optical coherence tomography of the neurosensory retina in rhegmatogenous retinal detachment.

PURPOSE: To clarify the pathologic changes of the detached neurosensory retina in rhegmatogenous retinal detachment. METHODS: Retinal images were prospectively examined by optical coherence tomography in 25 eyes of 25 consecutive patients with rhegmatogenous retinal detachment. We excluded the patients whose retinal detachment did not involve the central fovea or patients with poor fixation during optical coherence tomography (OCT) examination. Optical coherence tomography was scanned through the center of the fovea. The patients ranged in age from 15 to 77 years (mean, 45 years; SD, 20 years). The period from onset of subjective symptoms of retinal detachment to OCT ranged from 2 to 60 days (mean, 16 days; SD, 18 days). Optical coherence tomography findings, best-corrected visual acuity, and the height of the retinal detachment at the central fovea were statistically analyzed using ANCOVA (analysis of covariance) and the Mann-Whitney U test. RESULTS: In 25 eyes of 25 patients, OCT of the detached neurosensory retina at and adjacent to the center of the fovea demonstrated normal retinal structure (10 eyes, 40%), intraretinal separation (7 eyes, 28%), and an undulated separated outer retina (8 eyes, 32%). Three statistically significant factors affected best-corrected visual acuity: intraretinal separation (P = .001), intraretinal separation with undulated outer retina (P = .001), and height of retinal detachment at the central fovea (P<.001). Best-corrected visual acuity was significantly worse in the 15 eyes with intraretinal separation with or without an undulated outer retina than in the 10 eyes with retinal thickening but no intraretinal separation (P = .036). The eight eyes with undulated separated outer retina showed significantly higher retinal detachment at the central fovea than the seven eyes with intraretinal separation but no undulated outer retina (P = .009) and the 10 eyes without intraretinal separation (P = .016). The duration from onset of subjective symptoms to OCT was not related to the occurrence of intraretinal separation of the detached retina. CONCLUSIONS: Intraretinal separation of the detached retina occurred frequently and shortly after retinal detachment in rhegmatogenous retinal detachment and was one of the factors associated with poor vision in rhegmatogenous retinal detachment. Best-corrected visual acuity significantly decreased in the highly detached retina.

Adolescent↗
PubMed2000

The natural history and prognostic factors in patients with cirrhosis and gastric fundal varices without prior bleeding.

Objectives and methods: The prognostic factors have not yet been fully evaluated in patients with cirrhosis and gastric fundal varices (FV). We investigated the natural history of 145 patients with cirrhosis and FV with no history of bleeding. Various possible prognostic factors, which include clinical, biochemical, and endoscopical variables, were analyzed using Cox's proportional hazard model. Results: Among the 145 patients with cirrhosis and FV, there were 76 patients in class A, 45 in class B and 24 class C according to Child's classification. Sixty-five patients had concomitant hepatocellular carcinoma at the time of enrollment. Seventy deaths and 34 episodes of the hemorrhage from FV occurred during the mean follow-up period of 26.4 months. The cumulative survival rates at 1, 3, and 5 years were 75, 53 and 34%, respectively. The cause of death was related to gastrointestinal hemorrhage in 18 patients (15 deaths were related to FV hemorrhage), hepatic failure in 22, hepatocellular carcinoma in 22, and other causes in eight patients. In patients with small-, medium-, and large-sized FV, the deaths related to FV hemorrhage were 4, 21 and 54%, respectively. Overall, the death related to FV hemorrhage was 21%. A multiple regression analysis using Cox's model showed hemorrhage from FV, the presence of hepatocellular carcinoma and poor Child's status were all highly significant prognostic factors. Conclusion: The natural history of the patients with cirrhosis and FV was adversely modified by the hemorrhage from FV, concomitant hepatocellular carcinoma and poor hepatic functional reserve. Since the number of deaths related to FV hemorrhage was great in patients with large-sized FV, it is important to identify high-risk large FV and its prophylactic obliteration. Further studies are needed to elucidate the efficacy of prophylactic obliteration of large-sized FV.

Journal Article↗
PubMed2000

Delocalization of polar plasm components caused by grandchildless mutations, gs(1)N26 and gs(1)N441, in Drosophila melanogaster.

Two maternal-effect grandchildless (gs) mutations of Drosophila melanogaster, gs(1)N26 and gs(1)N441, cause delay in nuclear arrival at the polar plasm. In mutant embryos, polar plasm loses its ability to induce pole cells during retarded nuclear migration to the posterior pole of embryos. In the present study, it was shown that in N26 and N441 embryos, mitochondrial large rRNA (mtlrRNA), an essential factor for pole cell formation, is delocalized during the delay in nuclear arrival. This suggests that the loss of mtlrRNA causes failure of the mutants to form pole cells. Furthermore, it was shown that all of the other polar plasm components examined, namely Vasa protein, Germ cell-less protein, nanos mRNA and Polar granule component RNA start to be delocalized during the delay in nuclear arrival. This suggests that polar plasm integrity is not maintained in mutant embryos. It was finally shown that Vas is also delocalized in embryos that are inhibited to form pole cells by reducing the amount of mtlrRNA. This indicates that the segregation of polar plasm into pole cells is required to maintain polar plasm integrity. The mechanism regulating polar plasm integrity in embryos is discussed.

Animals↗
PubMed2000

Functional modulation of the mineralocorticoid receptor by cis-diamminedichloroplatinum (II).

BACKGROUND: Renal salt wasting and hypotension are some of the frequent complications in patients treated with cis-diamminedichloroplatinum (II) (cDDP), and it is suggested that cDDP produces an abnormality in the renin-angiotensin system. However, not only the underlying mechanism but also prophylactic treatment of this cDDP toxicity remains unknown. In the present study, we investigated the molecular mechanism of this cDDP-induced disturbance of renal sodium handling with focusing on the effect of cDDP on mineralocorticoid receptor (MR) function. METHODS: The effect of cDDP was studied on nuclear translocation, DNA binding activity, and transactivation function of the MR. RESULTS: In a transient transfection assay, cDDP suppressed MR-dependent reporter gene expression. This cDDP-mediated repression of MR function, at least in part, is suggested to be due to the generation of reactive oxygen species and a subsequent decrease in ligand-dependent nuclear translocation and suppression of the interaction with DNA of the MR. This redox-dependent repression of MR function both in vitro and in vivo was reversed by treatment with reducing reagents. Moreover, cDDP, most possibly via formation of DNA adducts, inhibited MR-DNA interaction in a redox-independent fashion. CONCLUSIONS: MR function is impaired by cDDP at multiple levels, via redox-dependent and -independent mechanisms.

Animals↗
PubMed2000

Alcoholic fatty liver differentially induces a neutrophil-chemokine and hepatic necrosis after ischemia-reperfusion in rat.

Primary graft nonfunction of steatotic liver allograft is one of the factors causing shortage of donor livers. Ischemia/reperfusion (I/R) injury is an important contributory factor to primary graft nonfunction. In this study, we investigated the complex chain of events from transcription factor activation to necrosis through cytokine induction and apoptosis in steatotic rat liver after warm I/R. Rats with alcoholic or nonalcoholic fatty liver were subjected to hepatic warm I/R and compared with control rats. Rats fed an ethanol diet for 6 to 8 weeks developed severe hepatic necrosis accompanied by increased neutrophil recruitment after I/R, compared with rats with nonalcoholic fatty liver or control. Hepatic apoptosis as assessed by DNA fragmentation at 4 hours after I/R, however, increased to a similar degree in each of the 2 fatty liver models compared with the control. Alcoholic fatty liver exposed to I/R showed a rapid increase in nuclear factor-kappaB (NF-kappaB) binding activity at 1 hour after I/R, which preceded an increased expression of tumor necrosis factor alpha (TNF-alpha) and cytokine-induced neutrophil chemoattractant-1 (CINC-1). In contrast, nonalcoholic fatty liver did not show such potentiation of either NF-kappaB activation or cytokine induction after I/R. Our results have indicated that alcoholic fatty liver may differentially induce CINC-1 production and hepatic necrosis after I/R. Furthermore, our results suggest that apoptosis per se does not always lead to necrosis in the liver following I/R.

Animals↗
PubMed2000

Stress-induced factor involved in flower formation of Lemna is an alpha-ketol derivative of linolenic acid.

A stress-induced substance(s) (factor C) incubated with norepinephrine (NE) has strong flower-inducing activity in Lemna paucicostata. We isolated an essential component (FIF) of factor C, and clarified its chemical structure as 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid, an alpha-ketol derivative of linolenic acid, which is formed via 9-hydroperoxy linolenic acid. Synthesized FIF showed flower-inducing activity after incubation with NE (factor C activity) equivalent to that formed in the stressed Lemna. Jasmonic acid and 13-hydroxy-12-oxo-9(Z),15(Z)-octadecadienoic acid (12,13-alpha-ketol linolenic acid), both of which are formed via 13-hydroperoxide of linolenic acid and all other derivatives of FIF synthesized by chemical and enzymatic processes failed to show the factor C activity. These results suggest that the molecular structure of FIF is very specific for the factor C activity.

Fatty Acids, Unsaturated↗
PubMed2000

Optimal propofol plasma concentration during upper gastrointestinal endoscopy in young, middle-aged, and elderly patients.

BACKGROUND: Suitable propofol plasma concentrations during gastroscopy have not been determined for suppressing somatic and hemodynamic responses in different age groups. METHODS: Propofol sedation at target plasma concentrations from 0.5 to 4.0 microgram/ml were performed randomly in three groups of patients (23 per group) who were undergoing elective outpatient gastroscopy: ages 17-49 yr (group 1), 50-69 yr (group 2), and 70-89 yr (group 3). Plasma propofol concentration in which 50% of patients do not respond to these different stimuli were determined by logistic regression: verbal command (Cp50ls), somatic response to gastroscopy (Cp50endo), and gag response to gastroscopy (Cp50gag). Hemodynamic responses were also investigated in the different age groups. RESULTS: Cp50ls concentrations were 2.23 microgram/ml (group 1), 1.75 microgram/ml (group 2), and 1.40 microgram/ml (group 3). The Cp50endo values in groups 1 and 2 were 2.87 and 2.34 microgram/ml, respectively, which were significantly higher than their respective Cp50ls values. Cp50endo value in group 3 was 1.64 microgram/ml, which was close to its Cp50ls value. Because of a high degree of interpatient variability, Cp50gag could not be defined. Systolic blood pressure response decreased with increasing propofol concentrations. CONCLUSIONS: The authors determined the propofol concentration necessary for gastroscopy and showed that increasing age reduces it. Propofol concentration that suppresses somatic response induces loss of consciousness in almost all young patients.

Adolescent↗
PubMed2000

Protein-losing enteropathy caused by mesenteric venous thrombosis with protein C deficiency.

A 64-year-old man presented with leg edema and hypoproteinemia. His alpha-1 antitrypsin clearance rate of 174 mL/day indicated the presence of protein-losing enteropathy (PLE). Computed tomographic scans demonstrated thickened ileal wall and mesenteric edema. Angiography revealed occlusion in a peripheral branch of the superior mesenteric vein. Furthermore, both the patient and his son had low protein C levels. The patient was treated successfully with partial resection of the ileum. Histologic examination of the resected ileum revealed multiple erosions and submucosal fibrosis with organized venous thrombi in the mesenteric veins. This is the first case report of PLE caused by mesenteric venous thrombosis, and our findings suggest that serum protein was lost through erosion of the ileum caused by ischemia due to mesenteric venous thrombosis.

Humans↗
PubMed2000

Mechanisms of chloride secretion induced by thermostable direct haemolysin of Vibrio parahaemolyticus in human colonic tissue and a human intestinal epithelial cell line.

Thermostable direct haemolysin (TDH) produced by Vibrio parahaemolyticus is thought to play an important role in the severe diarrhoea caused by this organism. This study investigated the enterotoxicity of TDH for human intestinal cells. Addition of TDH to the mucosal side of human colonic tissue in Ussing chambers caused increased short circuit currents (Isc), a process that was inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS), an inhibitor of Ca2+ -activated chloride (Cl-) channels. With human colonic epithelial (Caco-2) cells, high Isc and intracellular Ca2+ concentrations ([Ca2+]in) were detected after the addition of TDH to the apical side of the cell monolayer. The Isc decreased with the addition of DIDS, but not with glybenclamide, 5-nitro-2-(3-phenylpropylamino) benzoic acid, or gadolinium chloride. No Isc increase with TDH was observed when the Cl- in the medium was replaced by gluconate or when Ca2+ was depleted. Similarly, TDH did not raise [Ca2+]in after depletion of extracellular Ca2+. R7, a mutant form of TDH, reduced the effects of TDH on Isc and [Ca2+]in, as did protein kinase C (PKC) inhibitors. Thus, TDH increases Cl- secretion in human colonic epithelial cells, apparently through mechanisms involving cell binding and Ca2+ influx, followed by elevation of [Ca2+]in associated with PKC phosphorylation.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2000

Improvement of exercise tolerance by single lead VDD pacemaker: evaluation using cardiopulmonary exercise test.

We used a cardiopulmonary test to assess the physiological benefit of single lead VDD pacing in ten patients (six men, four women; aged 32-84 years, mean 69 years) with atrioventricular block. Maximal symptom-limited treadmill exercise test using a ramp protocol was performed under VDD and VVIR or VVI pacing (VVI) in random sequence. The pacemaker was then programmed to the VDD mode, and Holter ECG was recorded in nine patients. Compared with findings during the VVI, the VDD mode had a greater chronotropic response (mean maximal heart rate, VDD 106 +/- 17 beats/min vs VVI 79 +/- 19 beats/min, P = 0.03), and was associated with prolongation of exercise duration (VDD 11.2 +/- 2.9 minute vs VVI 10.5 +/- 3.1 minute; P = 0.01), and the onset of anaerobic threshold at a higher oxygen uptake (VDD 12.4 +/- 3.4 mL/min per kilogram vs VVI 10.0 +/- 2.1 mL/min per kilogram; P < 0.01). Atrial sensing was recognized in almost all normal sinus P waves for all cases examined using Holter ECG. Thus, chronotropic response during exercise by VDD pacemaker improved exercise tolerance, indicating that a VDD pacemaker might be useful for patients requiring physical activity.

Adult↗
PubMed2000

Ultrasonographic evaluation of lansoprazole-induced improvement of submucosal injury in patients with gastroesophageal reflux.

OBJECTIVE: Endoscopic ultrasonographic (EUS) changes in gastroesophageal reflux disease (GERD) after treatment with proton pump inhibitor have been poorly evaluated. We conducted a randomized, double-blind 12-wk clinical trial to compare the EUS effects of lansoprazole to histamine H2-receptor antagonist therapy in GERD. METHODS: Seventeen patients with reflux-related symptoms received 40 mg of famotidine for 6 wk or 30 mg of lansoprazole for 6 wk followed by 40 mg of famotidine or 30 mg of lansoprazole for another 6 wk, respectively. Patients underwent EUS before and at 6 and 12 wk after treatment. RESULTS: Before treatment, a variable degree of wall thickening was noted on EUS in the lower esophagus, compared with 20 normal subjects. After 6 wk of therapy, esophageal wall was significantly thicker in the famotidine group compared with the lansoprazole group (p<0.01). Surprisingly, thickening of esophageal wall and abnormal architecture were also detected in endoscopically negative reflux disease. Lansoprazole was superior to famotidine in reducing the thickness of esophageal wall. CONCLUSIONS: EUS was very useful for evaluation of submucosal injury in patients with GERD. EUS showed that a 6-wk course of lansoprazole therapy reduced thickening of esophageal wall, which was resistant to histamine H2-receptor antagonist therapy. Our results also suggest that inflammatory damage to the submucosal and muscle layers of the lower esophagus is the underlying mechanism of heartburn and associated symptoms in patients with endoscopically negative reflux disease.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

Genetic characterization of DNA region containing the trh and ure genes of Vibrio parahaemolyticus.

We have demonstrated that possession of the gene for thermostable direct hemolysin-related hemolysin (trh) coincides with the presence of the urease gene among clinical Vibrio parahaemolyticus strains and that the location of the two genes are in close proximity on the chromosome. Here, we cloned and sequenced the 15,754-bp DNA region containing the trh gene and the gene cluster for urease production from the chromosome of clinical V. parahaemolyticus (TH3996). We found 16 open reading frames (ORFs) and a lower G+C content (41%) compared with the total genome of this bacterium (46 to 47%). The ure cluster consisted of eight genes, namely, ureDABCEFG and ureR. ureR was located 5.2 kb upstream of the other seven genes in the opposite direction. The genetic organization and sequences of the ure genes resembled those found in Proteus mirabilis. Between ureR and the other ure genes, there were five ORFs, which are homologous with the nickel transport operon (nik) of Escherichia coli. We disrupted each of the ureR, ureC, and nikD genes in TH3996 by homologous recombination and analyzed the phenotype of the mutants. In the presence of urea these mutant strains had dramatically less urease activity than the strain they were derived from. Disruption of ureR, nikD, or ureC, however, had no effect on TRH production. The DNA region containing the trh, nik, and ure genes was found in only trh-positive strains and not in Kanagawa phenomenon-positive and environmental V. parahaemolyticus strains. At the end of the region, an insertion sequence-like element existed. These results suggest that the DNA region was introduced into V. parahaemolyticus in the past through a mechanism mediated by insertion sequences. This is the first reported case that the genes for an ATP-binding cassette-type nickel transport system, which may play a role in nickel transport through bacterial cytoplasmic membrane, are located adjacent to the ure cluster on the genome of an organism.

ATP-Binding Cassette Transporters↗