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T Tobe

Publications and source records attributed to T Tobe.

At least 37 records · Page 2Linked to original sources
PubMed2000

Identification of epitopes for cross-reaction, auto-reaction and autoantibodies to catalase.

We identified in bovine and rat catalase two epitopes that were responsible for a cross-reaction between the two species using cross-reactive antibodies raised in rabbits by immunization with their respective catalases. The epitopes were(444)TFYLK(448)and(458)LCENIAGHLK(467)in bovine catalase and(445)TFYTK(449)and(459)LCENIANHLK(468)in rat catalase. The two epitopes in rats were also identified as epitopes for auto-reactive antibodies that were raised in rats by immunization with bovine catalase and were reactive with a homologous rat catalase. Furthermore, one of the rat epitopes,(459)LCENIANHLK(468), was identified as the epitope for autoantibodies which were inducible by intensive immunization in rats with the homologous rat catalase. A possible implication of the epitopes in certain human diseases is discussed.

Amino Acid Sequence↗
PubMed2000

SdiA, an Escherichia coli homologue of quorum-sensing regulators, controls the expression of virulence factors in enterohaemorrhagic Escherichia coli O157:H7.

The quorum-sensing system in bacteria is a well-known regulatory system that controls gene expression in a cell density-dependent manner. A transcriptional regulator (LuxR homologue), signal synthase (LuxI homologue) and autoinducer (acyl homoserine lactone) are indispensable for this system in most Gram-negative bacteria. In this study, we found that SdiA, an Escherichia coli LuxR homologue, is a negative regulator of the expression of virulence factors EspD and intimin in enterohaemorrhagic E. coli (EHEC) O157:H7. The expression of EspD and intimin was inhibited at the RNA level upon SdiA overexpression. SdiA has a DNA-binding motif in its C-terminal part and can bind to the promoter regions of the esp and eae genes in vitro. Extracellular factors, which accumulate in culture supernatants of O157:H7 at the stationary phase of growth and inhibit EspD and intimin synthesis, bind to the N-terminal part of SdiA in vivo and in vitro. O157:H7 overproducing the N-terminal part of SdiA exhibited hypertranscription of EspD and intimin, suggesting that the overproduced N-terminal part had inhibited the activity of intact SdiA through titration of the extracellular factors. These results indicate that a quorum-sensing system including the SdiA protein controls colonization by O157:H7.

Bacterial Proteins↗
PubMed2000

Changes in serum prostate-specific antigen following prostatectomy in patients with benign prostate hyperplasia.

PURPOSE: To investigate how prostatectomy for patients with benign prostate hyperplasia (BPH) affected the serum prostate-specific antigen (PSA) levels. METHODS: In 193 patients who underwent prostatectomy for BPH, serum PSA levels were measured before and three months after the operation. The total prostate weight measured by transrectal ultrasonography (TRUS) and the weight of the surgical specimen were examined in relation to the pretreatment PSA value and the changes in PSA levels after the operation. RESULTS: The transition zone volume measured by TRUS could well estimate the weight of the surgical specimen in patients who underwent subcapsular prostatectomy and transurethral resection of the prostate. The concentration of preoperative serum PSA showed a significant correlation with the prostatic volume and with the transition zone volume. Removal of 1 g of BPH tissue reduced serum PSA levels by an average of 0.18 ng/mL. The change in serum PSA levels after the prostatectomy correlated with the total prostatic gland volume and with the transition zone volume. CONCLUSIONS: The elevated PSA levels in patients with BPH were caused by the enlargement of the transition zone. After the resection of the adenoma, PSA levels should be expected to decrease to the normal range.

Adenoma↗
PubMed2000

Isolation and characterization of mini-Tn5Km2 insertion mutants of enterohemorrhagic Escherichia coli O157:H7 deficient in adherence to Caco-2 cells.

Adherence of enterohemorrhagic Escherichia coli (EHEC) to intestinal epithelium is essential for initiation of the infection. To identify genes involved in adherence, an EHEC O157:H7 strain (O157Sakai) was mutagenized by mini-Tn5Km2, where Km refers to kanamycin resistance, and 4,677 insertion mutants were screened for their ability to form microcolonies (MC) on Caco-2 cells. The less adherent mutants were divided into three groups: those with no adherent ability (designated as class 1 mutants, n = 10), those less adherent than the wild type (class 2 mutants, n = 16), and those unable to form MC but which adhered in a diffuse manner (class 3 mutants, n = 1). The sites of insertion in class 1 mutants were all found within genes of the locus for enterocyte effacement (LEE) thought to be required for type III protein secretion. Indeed, the class 1 mutants failed to secrete type III secreted proteins such as EspA and Tir into the culture medium. The insertions in class 2 mutants were outside the LEE, and all the mutants except one were able to secrete type III proteins into the culture medium. The class 3 mutant had the insertion in the tir gene in the LEE and was deficient in Tir and intimin expression, suggesting that in the absence of intimin-Tir, O157Sakai can still adhere to Caco-2 cells but in a diffused manner. This was confirmed by construction of a nonpolar eae (encoding intimin) mutant. Examination of the eae mutant together with O157Sakai and one of the class 1 mutants for the ability to form MC revealed that EHEC initially adhered diffusely at 1.5 h after infection. Following washing out of the nonadherent bacteria, while wild-type EHEC bacteria developed MC for another 2 to 3 h on Caco-2 cells, the eae mutant diffusely adhered throughout the infection without forming MC. MC with O157Sakai but not the diffusely adherent eae mutant could evoke F-actin condensation beneath the bacterium. Our results suggest that EHEC encodes additional adherence-associated loci and that the type III secreted proteins are involved in the initial diffuse adherence, while the intimin-Tir interaction is required for the subsequent development of MC.

Adhesins, Bacterial↗
PubMed2000

Regulation of virulence factors of enterohemorrhagic Escherichia coli O157:H7 by self-produced extracellular factors.

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes serious diarrhea and hemolytic uremic syndrome in humans. The expressions of EspD and intimin by O157:H7 have now been shown to be down-regulated by medium conditioned by O157:H7 grown at stationary phase. Preparation of conditioned medium showing the effect on the amount of EspD was not dependent on temperature or growth medium, but was dependent on growth phase. Inhibition of EspD and intimin expression was also induced by medium conditioned by E. coli K-12 strains and homoserine lactone, a signal molecule of the quorum-sensing system in gram-negative bacteria. These results suggest the possibility that the quorum-sensing system mediated by self-produced extracellular factors plays an important role in control of colonization of EHEC O157:H7.

Adhesins, Bacterial↗
PubMed1999

Organization of the gene for gelatin-binding protein (GBP28).

GBP28 is a novel human plasma gelatin-binding protein that is encoded by apM1 mRNA, expressed specifically in adipose tissue. Three overlapping clones (two lambda clones and one BAC clone) containing the human plasma gelatin-binding protein (GBP28) gene were isolated and characterized. The GBP28 gene spans 16kb and is composed of three exons from 18bp to 4277bp in size with consensus splice sites. The sizes of the two introns were 0.8 and 12kb, respectively. The gene's regulatory sequences contain putative promoter elements, but no typical TATA box. The third exon of this gene contains a long 3'-untranslated sequence containing three Alu repeats. The exon-intron organization of this gene was very similar to that of obese gene, encoding leptin. We also report the chromosome mapping of this gene by fluorescence in situ hybridization (FISH) using a genomic DNA fragment as a probe. The GBP28 gene was located on human chromosome 3q27. The nucleotide sequence data reported in this paper will appear in the DDBJ/EMBL/GenBank nucleotide sequence databases with the accession numbers ABO12163, ABO12164 or ABO12165.

Adiponectin↗
PubMed1999

Prospective Randomized Study of Cyclophosphamide, Epirubicin, and 5-Fluorouracil versus Cyclophosphamide, Adriamycin, and 5-Fluorouracil in Advanced or Recurrent Breast Cancer.

BACKGROUND: Treatment with cyclophosphamide, adriamycin, and 5-fluorouracil (CAF), a widely used, potent regimen is sometimes restricted by the myelotoxicityand myocardiotoxicity of adriamycin (ADR). In a prospective randomized controlled study of patients with advanced or recurrent breast cancer, the efficacy and toxicity of a CEF regimen, in which epirubicin (EPI) was substituted for ADR, was compared with CAF. METHODS: 138 female patients under 75 years of age who had unresectable or recurrent breast cancer during the period from October, 1989 to September, 1991, were randomized to one of two treatment regimens. The first regimen consisted of cyclophosphamide 100 mg p.o. d1-14, adriamycin 30 mg/m(2) i.v. d1, 8 and 5-fluorouracil 500 mg/m(2) i.v. d1, 8 (CAF). In the second regimen, EPI 30 mg/m(2) i.v. d1, 8was substituted for ADR (CEF). Both regimens were delivered q4 weeks. RESULTS: Of 138 patients, 105 (CEF 56, CAF 49) were evaluable for response and survival, and all were evaluable for toxicity (CEF 68, CAF 70). The median course of lots CEF and CAF was 3 cycles. Response rates (complete response plus partial response) with CEF and CAF were 35.7% (20/56) and 36.7% (18/49), respectively. Adverse effects were similar in the two groups, but severe leukopenia (CEF 36.8%, CAF 64.3%) and hepatic toxicity (CEF 1.5%, CAF 12.9%) were encountered more frequently with CAF than with CEF. The duration of 50% survival was 135.9 weeks for CEF and 172.1 weeks for CAF (not significant). CONCLUSION: At an equal dose of EPI and ADR response rates and survival of the CEF group were similar to those of the CAF group, but adverse effects were fewer in the CEF group.

Journal Article↗
PubMed1999

A novel chromosomal locus of enteropathogenic Escherichia coli (EPEC), which encodes a bfpT-regulated chaperone-like protein, TrcA, involved in microcolony formation by EPEC.

The bfpTVW operon, also known as the per operon, of enteropathogenic Escherichia coli (EPEC) is required for the transcriptional activation of the bfp operon, which encodes the major subunit and assembly machinery of bundle-forming pili (BFP). An immobilized T7-tagged BfpT fusion protein that binds specifically to upstream promoter sequences of bfpA and eae was used to 'fish out' from a promoter library other EPEC chromosomal fragments that are bound by the BfpT protein. After screening for promoters exhibiting bfpTVW-dependent expression, one was identified that was positively regulated by bfpTVW and that is not present in the chromosomes of two non-virulent E. coli laboratory strains, DH5alpha and HB101. Further analysis of this positively regulated promoter in EPEC showed that it resided within a 4.9 kb sequence that is not present in E. coli K12. This locus, located downstream of the potB gene, was found to contain four open reading frames (ORFs): bfpTVW-activated promoter was localized upstream of ORF1. An ORF1 knockout mutant produced less of the BFP structural subunit (BfpA) and formed smaller than normal adherent microcolonies on cultured epithelial cells; however, this mutation did not affect bfp transcription. An ORF1-His6 fusion protein specifically bound the preprocessed and mature forms of the BfpA protein and thus appears to stabilize the former within the cytoplasmic compartment. ORF1 therefore is a newly isolated EPEC chromosomal gene that encodes a chaperone-like protein involved in the production of BFP. Hence, ORF1 was designated trcA (bfpT-regulated chaperone-like protein gene). The TrcA protein also specifically bound 39 kDa and 90 kDa proteins that are expressed by EPEC but not by E. coli K12. The 90 kDa protein was revealed to be intimin, a protein product of the eae gene, which is required for the EPEC attaching/effacing phenotype, suggesting a direct interaction of TrcA with intimin in the cytoplasmic compartment.

Adhesins, Bacterial↗
PubMed1999

Complete DNA sequence and structural analysis of the enteropathogenic Escherichia coli adherence factor plasmid.

The complete nucleotide sequence and organization of the enteropathogenic Escherichia coli (EPEC) adherence factor (EAF) plasmid of EPEC strain B171 (O111:NM) were determined. The EAF plasmid encodes two known virulence-related operons, the bfp operon, which is composed of genes necessary for biosynthesis of bundle-forming pili, and the bfpTVW (perABC) operon, composed of regulatory genes required for bfp transcription and also for transcriptional activation of the eae gene in the LEE pathogenicity island on the EPEC chromosome. The 69-kb EAF plasmid, henceforth designated pB171, contains, besides the bfp and bfpTVW (perABC) operons, potential virulence-associated genes, plasmid replication and maintenance genes, and many insertion sequence elements. Of the newly identified open reading frames (ORFs), two which comprise a single operon had the potential to encode proteins with high similarity to a C-terminal region of ToxB whose coding sequence is located on pO157, a large plasmid harbored by enterohemorrhagic E. coli. Another ORF, located between the bfp and bfpTVW operons, showed high similarity with trcA, a bfpT-regulated chaperone-like protein gene of EPEC. Two sites were found to be putative replication regions: one similar to RepFIIA of p307 or F, and the other similar to RepFIB of R100 (NR1). In addition, we identified a third region that contains plasmid maintenance genes. Insertion elements were scattered throughout the plasmid, indicating the mosaic nature of the EAF plasmid and suggesting evolutionary events by which virulence genes may have been obtained.

Bacterial Adhesion↗
PubMed1999

Regulation of gelatin-binding protein 28 (GBP28) gene expression by C/EBP.

We have previously reported the isolation of human gelatin-binding protein 28 (GBP28) gene which is specifically expressed in adipose tissue. The transcriptional activity of the flanking region of the GBP28 gene was examined by the transient transfection of promoter-luciferase reporter constructs into 3T3 adipocytes and electrophoretic mobility shift assay. This revealed the existence of a protein which binds to the 5'-flanking region of the GBP28 gene in nuclear extracts from human adipose tissue, but not in nuclear extracts from mouse liver. The C/EBP sites contained in this region are thought to take part in the regulation of GBP28 gene expression.

3T3 Cells↗
PubMed1999

[Effects of local administration of interferon-beta on proliferation of the retinal pigment epithelium].

PURPOSE: We demonstrated effects of local administration of human interferon (IFN)-beta on the repair process of the rabbit retinal pigment epithelium (RPE). MATERIAL AND METHODS: We used adult pigmented rabbits in this experiment. We measured IFN-beta levels in the ocular tissues after sub-Tenon administration of human IFN-beta by means of enzyme-linked immunosorbent assay (ELISA) methods. Laser photocoagulation in moderate intensity was applied after IFN administration. The repair process of the RPE in laser lesion sites was examined histopathologically. RESULTS: Locally administrated IFN spread by diffusion into the intraocular tissues. The highest IFN level was detected in the choroid. In eyes treated with IFN, RPE cells proliferated vigorously to the center of the photocoagulated lesions on early stages after laser photocoagulation. Proliferation of RPE cells after laser photocoagulation was remarkable in eyes treated with large amounts of IFN. CONCLUSION: It was demonstrated histopathologically that sub-Tenon administration of IFN-beta promoted proliferation of RPE cells during the repair process after laser photocoagulation.

Administration, Topical↗
PubMed1998

Type IV pili, transient bacterial aggregates, and virulence of enteropathogenic Escherichia coli.

Type IV bundle-forming pili of enteropathogenic Escherichia coli are required for the localized adherence and autoaggregation phenotypes. Whether these pili are also required for virulence was tested in volunteers by inactivating bfpA or bfpT (perA) encoding, respectively, the pilus subunit and the bfp operon transcriptional activator. Both mutants caused significantly less diarrhea. Mutation of the bfpF nucleotide-binding domain caused increased piliation, enhanced localized adherence, and abolished the twitching motility-dispersal phase of the autoaggregation phenotype. The bfpF mutant colonized the human intestine but was about 200-fold less virulent. Thus, BfpF is required for dispersal from the bacterial aggregate and for full virulence.

Adolescent↗
PubMed1998

Glutamate-stimulated proliferation of rat retinal pigment epithelial cells.

We investigated the effects of glutamate on cell proliferation and the expression of basic fibroblast growth factor (bFGF) and its receptor (FGF-R1) mRNA in cultured rat retinal pigment epithelial (RPE) cells. The number of primary RPE cells was significantly higher after treatment with 0.2 to 1.0 mM glutamate (maximum at 1.0 mM) for 7 days than in controls. Glutamate-stimulated cell proliferation was abolished by (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), but not by 6,7-dinitroquinoxaline-2,3-dione or L(+)-2-amino-3-phosphonopropionic acid. Proliferation was increased to a similar extent by N-methyl-D-aspartate (NMDA), but not by kainate, alpha-amino-3-hydroxy-3-methyl-4-isoxazolepropionic acid or trans-(+/-)-1-amino-1,3-cyclopentanedicarboxylic acid. NMDA-receptor-like immunoreactivity was detected in most cells cultured. Treatment of cells with glutamate increased the level of bFGF mRNA and, to a lesser extent, that of FGF-R1 mRNA, which peaked 2 and 4 days, respectively, after glutamate was added. The increase in bFGF mRNA induced by glutamate was inhibited by MK-801. These findings suggest that glutamate might stimulate proliferation of RPE cells through activation of NMDA receptors and expression of bFGF and further suggest that glutamate may be involved in the proliferative changes of RPE cells in retinal wound healing.

Animals↗
PubMed1998

Targeted disruption of the FGF2 gene does not prevent choroidal neovascularization in a murine model.

Choroidal neovascularization (CNV) is the major cause of severe visual loss in patients with age-related macular degeneration. Laser treatment is helpful for a minority of patients with CNV, and development of new treatments is hampered by a poor understanding of the molecular signals involved. Several lines of evidence have suggested that basic fibroblast growth factor (FGF2) plays a role in stimulating CNV. In this study, we tested this hypothesis using mice with targeted disruption of the FGF2 gene in a newly developed murine model of laser-induced CNV. One week after krypton laser photocoagulation in C57BL/6J mice, 34 of 60 burns (57%) showed fluorescein leakage and 13 of 16 (81%) showed histopathological evidence of CNV. At 2 weeks, CNV was detected in 9 of 10 burns (90%) in which a bubble had been observed at the time of the laser treatment. Electron microscopy showed fenestrated vessels with large lumens within choroidal neovascular lesions. Two weeks after laser-induced rupture of Bruch's membrane, 27 of 36 burns (75%) contained CNV in FGF2-deficient mice compared with 26 of 30 (87%) in wild-type control mice, a difference that is not statistically significant. This study demonstrates that FGF2 is not required for the development of CNV after laser-induced rupture of Bruch's membrane and provides a new model to investigate molecular mechanisms and anti-angiogenic therapy in CNV.

Animals↗
PubMed1998

Identification and characterization of a newly isolated shiga toxin 2-converting phage from shiga toxin-producing Escherichia coli.

Shiga toxins 1 (Stx1) and 2 (Stx2) are encoded by toxin-converting bacteriophages of Stx-producing Escherichia coli (STEC), and so far two Stx1- and one Stx2-converting phages have been isolated from two STEC strains (A. D. O'Brien, J. W. Newlands, S. F. Miller, R. K. Holmes, H. W. Smith, and S. B. Formal, Science 226:694-696, 1984). In this study, we isolated two Stx2-converting phages, designated Stx2Phi-I and Stx2Phi-II, from two clinical strains of STEC associated with the outbreaks in Japan in 1996 and found that Stx2Phi-I resembled 933W, the previously reported Stx2-converting phage, in its infective properties for E. coli K-12 strain C600 while Stx2Phi-II was distinct from them. The sizes of the plaques of Stx2Phi-I and Stx2Phi-II in C600 were different; the former was larger than the latter. The restriction maps of Stx2Phi-I and Stx2Phi-II were not identical; rather, Stx2Phi-II DNA was approximately 3 kb larger than Stx2Phi-I DNA. Furthermore, Stx2Phi-I and Stx2Phi-II showed different phage immunity, with Stx2Phi-I and 933W belonging to the same group. Infection of C600 by Stx2Phi-I or 933W was affected by environmental osmolarity differently from that by Stx2Phi-II. When C600 was grown under conditions of high osmolarity, the infectivity of Stx2Phi-I and 933W was greatly decreased compared with that of Stx2Phi-II. Examination of the plating efficiency of the three phages for the defined mutations in C600 revealed that the efficiency of Stx2Phi-I and 933W for the fadL mutant decreased to less than 10(-7) compared with that for C600 whereas the efficiency of Stx2Phi-II decreased to 0.1% of that for C600. In contrast, while the plating efficiency of Stx2Phi-II for the lamB mutant decreased to a low level (0.05% of that for C600), the efficiencies of Stx2Phi-I and 933W were not changed. This was confirmed by the phage neutralization experiments with isolated outer membrane fractions from C600, fadL mutant, or lamB mutant or the purified His6-tagged FadL and LamB proteins. Based on the data, we concluded that FadL acts as the receptor for Stx2Phi-I and Stx2Phi-II whereas LamB acts as the receptor only for Stx2Phi-II.

Animals↗
PubMed1998

Evolution of neovascularization in mice with overexpression of vascular endothelial growth factor in photoreceptors.

PURPOSE: To determine the earliest changes that occur in the retina after the onset of ectopic expression of vascular endothelial growth factor (VEGF) by photoreceptors in transgenic mice, to characterize the development of neovascularization (NV), and to determine the feasibility of using these mice to test the efficacy of antiangiogenic agents. METHODS: The time course of expression of VEGF transgene mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR). Histopathologic changes in the retina were investigated by light and electron microscopy and immunocytochemistry. Standard and confocal fluorescence microscopy and image analysis were used to evaluate NV in retinal whole mounts. RESULTS: VEGF transgene mRNA was first detected in the retina by RT-PCR on postnatal day 6 (P6) and increased over the next several days to reach a constant steady-state level between P14 and P21. Abnormal cells were seen in the outer nuclear layer on P10 and among photoreceptors on P14; by P18 there were cell aggregates in the subretinal space with evidence of lumen formation. The invading cells were demonstrated to be endothelial cells by staining with an endothelial cell-specific lectin. Whole mounts of retinas perfused with fluorescein-labeled dextran showed a similar sequence of events, with sprouts from retinal vessels in the deep capillary bed seen on P14 and vessels reaching the subretinal space by P18. Confocal and standard fluorescence microscopy and changes in the number and area of neovascular lesions in the subretinal space over time measured by image analysis suggest gradual enlargement and coalescence of vascular complexes. The subretinal NV was progressively engulfed by the retinal pigmented epithelium. Invasion of blood vessels from the choroid was not identified in any specimen. CONCLUSIONS: These data support the feasibility of using rhodopsin-VEGF transgenic mice to study tissue-specific aspects of NV in the retina and to test antiangiogenic agents for inhibition of intraretinal and subretinal NV.

Animals↗
PubMed1998

[Cystic vein: as a perfusion vein of hepatic portion-angiographical study].

In order to determine the hepatic portions by cystic vein, we carried out abdominal angiography in 153 patients. The cystic vein was recognized in eleven patients, but only in nine cystic venous flow could be measured. In this group of patients, in which the cystic venous flow was detected, hepatic angiography was performed through the right hepatic artery (RHA) in six patients, the anterior branch of RHA in one patient, and the cystic artery in two patients. Simultaneously, angiographical CT was performed in five patients. As the results, it is presumed that the cystic venous flow perfused segment 4 portal branch (P4) + segment 5 (S5) in four patients, P4 in two patients, segment 6 portal branch (P6), S5 + right portal vein (RPV) + right hepatic vein (RHV), and S5 + RHV in one patient, respectively, and we concluded that in 70% of cases cystic venous flow perfused either P4 or S5.

Cysts↗