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J Brunton

Publications and source records attributed to J Brunton.

At least 37 records · Page 2Linked to original sources
PubMed1993

Comparison of Helicobacter pylori and attaching-effacing Escherichia coli adhesion to eukaryotic cells.

Adhesion of Helicobacter pylori was reported previously to be morphologically identical to "attaching and effacing" Escherichia coli. Therefore, the aim of the present study was to define the adhesion phenotype of H. pylori LC-11 to HEp-2, KATO-III, HEL, and CHO tissue culture cells. By using both staining of F-actin with fluorescein-labeled phalloidin and ultrastructural analysis, diffuse bacterial adhesion to discrete microvillus-denuded regions of the plasma membrane was observed in each of the infected cell lines. However, strain LC-11 did not induce formation of F-actin adhesion pedestals on the eukaryotic cells. H. pylori was negative by colony blot hybridization with an E. coli attaching and effacing gene probe. Elevations in inositol triphosphates followed infection of HEp-2 cells with H. pylori (405% of control values +/- 147%; P < 0.05). To correlate the observed histopathology with expression of the H. pylori phosphatidylethanolamine receptor, a thin-layer chromatography overlay-binding assay was used to identify receptors in each of the cell lines. H. pylori adhered to eukaryotic cells regardless of the presence (HEp-2, KATO-III, and CHO cells) or absence (HEL cells) of the lipid receptor as detected under the assay conditions. However, in comparison to cell lines that possess the phosphatidylethanolamine receptor, HEL cells demonstrated less quantitative H. pylori binding. These findings suggest that mechanisms distinct from E. coli enteropathogens underlie the adhesion of H. pylori to mucosal surfaces. In addition to the phosphatidylethanolamine H. pylori receptor, another host factor(s) likely mediates the attachment of H. pylori to human eukaryotic cells.

Animals↗
PubMed1993

Multiple determinants of verotoxin-producing Escherichia coli O157:H7 attachment-effacement.

Verotoxin-producing Escherichia coli strains of the serotype O157:H7 belong to a class of gastrointestinal pathogens that adhere to epithelial cells in a characteristic pattern known as attaching and effacing. Recent insight into the nature of E. coli O157:H7 adhesion was provided by the cloning and sequencing of the chromosomal eaeA (for E. coli attaching and effacing) gene homolog (G. Beebakhee, M. Louie, J. De Azavedo, and J. Brunton, FEMS Microbiol. Lett. 91:63-68, 1992, and J. Yu and J. B. Kaper, Mol. Microbiol. 6:411-417, 1992) and isolation of a 60-MDa plasmid referred to as pO157 (I. Toth, M. L. Cohen, H. S. Rumschlag, L. W. Riley, E. H. White, J. H. Carr, W. W. Bond, and I. K. Wachsmuth, Infect. Immun. 58:1223-1231, 1990, and S. Tzipori, H. Karch, K. I. Wachsmuth, R. M. Robins-Browne, A. D. O'Brien, H. Lior, M. L. Cohen, J. Smithers, and M. M. Levine, Infect. Immun. 55:3117-3125, 1987) and an approximately 94-kDa outer membrane protein (94-kDa OMP; P. Sherman, F. Cockerill III, R. Soni, and J. Brunton, Infect. Immun. 59:890-899, 1991). In this study, we examined the gene products of both eaeA and pO157 in relation to the 94-kDa OMP and as candidate effectors for O157:H7 attachment-effacement. Peptide sequencing and immunoassay demonstrated that the C. coli O157:H7 eaeA gene product is distinct from the 94-kDa OMP. Using ultrastructural analyses, we found that both parent and pO157 plasmid-cured O157:H7 strains demonstrated attaching and effacing adhesion to host epithelial cells and reacted equally well to rabbit antiserum raised against the 94-kDa OMP. By both transmission electron microscopy and light microscopy, E. coli HB101 transformed separately with the cloned eaeA gene and the pO157 plasmid did not form attaching and effacing lesions on cultured epithelial cells in vitro and rabbit intestinal tissues in vivo. Since additional determinants may mediate the attaching and effacing phenotype, we examined transposon TnphoA mutants constructed from E. coli O157:H7 strain CL8. Two TnphoA mutants were found deficient in bacterial factors that are necessary for O157:H7 attachment-effacement and likely distinct from the eaeA gene product.

Adhesins, Bacterial↗
PubMed1992

Cloning and nucleotide sequence of the eae gene homologue from enterohemorrhagic Escherichia coli serotype O157:H7.

The eae gene has recently been shown to be necessary for the attaching and effacing (AE) activity of enteropathogenic Escherichia coli (EPEC) on intestinal epithelial cells. In this paper we report the cloning and nucleotide sequence of a similar gene from a strain of enterohemorrhagic E. coli (EHEC) serotype O157:H7. An EHEC eae sequence was identified which was 97% homologous to the EPEC eae gene for the first 2200 bp and 59% homologous over the last 800 bp. Both eae sequences show 50% homology to the central region of the Yersinia pseudotuberculosis inv gene. The receptor-binding domain of the inv gene product lies near the carboxyl terminus. This suggests that the predicted amino acid sequence divergence in the carboxyl termini of the eae gene products might result in different antigenic and receptor specificity of these putative adhesins.

Adhesins, Bacterial↗
PubMed1991

Crystallization and preliminary X-ray crystallographic analysis of verotoxin-1 B-subunit.

The B-subunit of verotoxin-1, which is believed to form a pentamer (monomer Mr = 7691), has been crystallized by vapor diffusion over a wide range of conditions. The best crystals, obtained with polyethylene glycol 8000 as the precipitant, belong to the orthorhombic space group P2(1)2(1)2(1), with cell dimensions a = 59.2 A, b = 102.7 A, c = 56.3 A. The cell dimensions are consistent with one B-subunit pentamer per asymmetric unit, and the crystals diffract to at least 2.0 A resolution. Data collected using synchrotron radiation at a wavelength of 2.070 A may allow the structure to be solved using the anomalous signal from three sulfur atoms in the monomer, combined with averaging over the non-crystallographic symmetry.

Bacterial Toxins↗
PubMed1991

Outer membranes are competitive inhibitors of Escherichia coli O157:H7 adherence to epithelial cells.

Escherichia coli of serotype O157:H7 are Vero cytotoxin-producing enteric pathogens that have been associated recently with sporadic cases and outbreaks of hemorrhagic colitis and with the hemolytic-uremic syndrome. Adherence of many enteropathogenic bacteria to mucosal surfaces is a critical step in the pathogenesis of diarrheal disease. We showed previously that adherence of E. coli O157:H7 strain CL-56 to epithelial cells in vitro is inhibited by outer membranes. In this study we examined whether outer membranes from a series of E. coli O157:H7 strains mediated competitive inhibition of bacterial binding to epithelial cells grown in tissue culture. We also determined which constituents of the outer membrane mediated inhibition of CL-56 adherence. Binding of six O157:H7 strains to HEp-2 cells was determined by quantitating the number of adherent bacteria in the presence and absence of outer membranes which were extracted from each strain with N-lauroyl sarcosinate (1.7%, wt/vol). After separation of outer membranes by gel electrophoresis, four bands (94, 40, 36, and 30 kDa) were collected by electroelution. Immune sera were raised in rabbits to each of the four eluted bands. Outer membrane extracts from each of the six O157:H7 strains inhibited binding of homologous organisms to the HEp-2 cells. At dilutions which did not cause bacterial agglutination, antiserum raised against the 94-kDa outer membrane protein showed maximal inhibition of bacterial adherence (17.0 +/- 7.3% adherence of control levels). Growth of bacteria in iron-depleted broth did not affect their binding to HEp-2 cells, suggesting that iron-regulated outer membranes were not involved. Fluid accumulation in ileal ligated loops of rabbits in response to E. coli O157:H7 challenge was diminished following both parenteral immunization with outer membranes extracted from the homologous strain and coincubation of organisms with immune serum which contained antibodies to outer membrane extracts. These data indicate that outer membranes are competitive inhibitors of E. coli O157:H7 adherence. Specific constituents of the outer membrane may function as bacterial attachment factors (i.e., adhesins) for E. coli O157:H7 adherence to epithelial cell surfaces.

Actins↗
PubMed1990

Characterization of Shiga-like toxin I B subunit purified from overproducing clones of the SLT-I B cistron.

The cistron encoding the B subunit of Escherichia coli Shiga-like toxin I (SLT-I) was cloned under control of the tac promoter in the expression vector pKK223-3 and the SLT-I B subunit was expressed constitutively in a wild-type background and inducibly in a lacIq background. The B subunit was located in the periplasmic space, and less than 10% was found in the culture medium after 24 h incubation. Polymyxin B extracts contained as much as 160 micrograms of B subunit/ml of culture. B subunit was purified to homogeneity by ion-exchange chromatography followed by chromatofocusing. Cross-linking analysis of purified native B subunit showed that it exists as a pentamer. In gels containing 0.1% SDS the native protein dissociated into monomers. B subunit was found to have the same glycolipid-receptor-specificity as SLT-I holotoxin. Competitive binding studies showed that B subunit and holotoxin had the same affinity for the globotriosylceramide receptor. We conclude that this recombinant plasmid is a convenient source of large amounts of purified SLT-I B subunit, which could be used for biophysical and structural studies or as a natural toxoid.

Antibodies, Monoclonal↗
PubMed1990

A randomized study to determine complications associated with duration of insertion of heparin locks.

A randomized trial was conducted to assess the effect of leaving heparin locks in place longer than 72 hours. Three hundred and one patients were randomly assigned to one of two groups. Group A had the lock changed every 72 hours and Group B had the lock left in place up to 168 hours. Due to withdrawals following randomization, Group A contained 116 subjects and Group B 140 subjects. No significant differences were found between the two groups in relation to age, sex, medical condition, drug used, entries into the lock, minor complications, or incidence of phlebitis. The findings suggest that consideration could be given to extending insertion time up to 96 hours and possibly up to 118 hours.

Adult↗
PubMed1989

Globotetraosylceramide is recognized by the pig edema disease toxin.

The pig edema disease toxin has been shown by a tlc glycolipid binding assay to bind specifically to globotetraosylceramide (Gb4, GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4GlcCer.). Binding was reduced for globotriosylceramide (Gb3, Gal alpha 1-4Gal beta 1-4GlcCer) and more markedly for the Forssman antigen (GalNAc alpha 1-3GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4GlcCer). Paragloboside, blood group A glycolipids, glycolipids terminating in Gal NAc beta 1-4Gal-, and glycolipids in which globoside was present as an internal sequence did not bind the toxin. Isogloboside (GalNAc beta 1-3Gal alpha 1-3Gal beta 1-4GlcCer) was efficiently recognized. This toxin is genetically related to the verotoxin (or Shiga-like) family of toxins for which Gb3 has been shown to be the receptor. The difference in susceptibility of cell lines to the cytotoxicity of the pig edema disease toxin and the Shiga and Shiga-like toxins is consistent with the difference in receptor glycolipid binding.

Animals↗
PubMed1989

The acute non-hospital: a California model.

Crisis residential programs were established by the California legislature in 1978 to provide an alternative to hospitalization for treatment of voluntary acute psychiatric patients. The five crisis residential programs in San Diego County, California, provide high-quality mental health care that is community-based and considerably less expensive than traditional in-hospital programs. Currently, the majority of public-sector, voluntary adult patients in San Diego County receives acute psychiatric inpatient services in these programs. This paper provides a description of the facilities, staff composition, patients, treatment model, and costs.

California↗
PubMed1988

The influence of corticosteroids on human erythropoiesis. An in vivo study.

Three groups of patients were studied to assess the effect of oral corticosteroid therapy on erythropoiesis in vivo as measured by changes in haemoglobin concentration (Hb) and red blood cell count (RBC). Fifteen patients with acute lymphoblastic leukaemia, who were in remission and receiving pulses of vincristine and prednisone during maintenance chemotherapy, showed no rise in Hb or RBC with steroid therapy. Likewise, 15 patients completing chemotherapy for ALL did not show a rise in Hb or RBC after stopping treatment. However, 14 children with acute immune thrombocytopenic purpura demonstrated a significant increase in Hb and RBC during a course of treatment with prednisone. These findings complement the results of in vitro studies, indicating that erythropoiesis in normal human bone marrow is stimulated by corticosteroid therapy.

Child↗
PubMed1988

The possible role of corticosteroid therapy for pneumocystis pneumonia in the acquired immune deficiency syndrome (AIDS).

Twenty-one episodes of Pneumocystis carinii pneumonia (PCP) and the acquired immune deficiency syndrome (AIDS) were treated with corticosteroids in the form of intravenous methylprednisolone or oral prednisone. A standard dose of 80 mg/day x 5 days was given for 15 episodes, whereas 6 patients received variable doses of 20-120 mg/day x 4-20 days. All were treated with trimethoprim-sulfamethoxazole (TMP-SMX). Comparison was made with 12 AIDS patients with PCP who were not treated with steroids. The steroid group was more severely ill than the controls as measured by alveolar-arterial oxygen difference but were otherwise comparable. Mortality from the pneumonia in the steroid group was 2/21 (10%) vs. 3/12 (25%) in the control group. Significant differences were seen in the following parameters: time to defervescence (1 day vs. greater than 9.3 days), the proportion of patients with pO2 greater than 70 mm Hg at day 5 [12/21 (57%) vs. 1/12 (9%)] and at day 10 [19/21 (90%) vs. 7/12 (58%)], and number of adverse drug reactions [4/21 (19%) vs. 9/12 (75%)]. There were fewer late relapses [1/19 (5%) vs. 2/9 (22%)] after a 5.5 month (mean) follow-up. All patients had improvements in their clinical status when initially given corticosteroid therapy but early relapses occurred when steroids were discontinued in five patients (24%). No other complications could be attributed to steroid therapy in this study. A brief course of high-dose corticosteroids appears to be beneficial in severely ill AIDS patients with pneumocystis pneumonia. This suggests the need for randomized, double-blind, placebo-controlled trials to confirm these findings.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Nucleotide sequence and promoter mapping of the Escherichia coli Shiga-like toxin operon of bacteriophage H-19B.

We determined the nucleotide sequence of the Shiga-like toxin-1 (SLT-1) genes carried by the toxin-converting bacteriophage H-19B. Two open reading frames were identified; these were separated by 12 base pairs and encoded proteins of 315 (A subunit) and 89 (B subunit) amino acids. The predicted protein subunits had N-terminal hydrophobic signal sequences of 22 and 20 amino acids, respectively. The predicted amino acid sequence of the B subunit was identical to that of the B subunit of Shiga toxin. The A chain of ricin was found to be significantly related to the predicted A1 fragment of the SLT-1 A subunit. S1 nuclease protection experiments showed that the two cistrons formed a single transcriptional unit, with the A subunit being proximal to the promoter. A probable promoter was identified by primer extension, and transcription was found to increase dramatically under conditions of iron starvation. A 21-base-pair sequence with dyad symmetry was found in the region of the SLT-1 -10 sequence, which was found to be 68% homologous to a region of dyad symmetry found in the -35 region of the promoter of the iucA gene on plasmid ColV-K30, which specifies the 74,000-dalton ferric-aerobactin receptor protein. Betley et al. (M. Betley, V. Miller, and J. Mekalanos, Annu. Rev. Microbiol. 40:577-605, 1986) have recently summarized evidence suggesting that the slt operon is under the control of the fur regulatory system. The area of dyad symmetry found in both promoters may represent a regulatory site. A rho-independent terminator sequence was found 230 base pairs downstream from the B cistron stop codon.

Amino Acid Sequence↗
PubMed1986

Origin of small beta-lactamase-specifying plasmids in Haemophilus species and Neisseria gonorrhoeae.

Fifty-nine percent of unselected strains of Haemophilus parainfluenzae were found to carry small, phenotypically cryptic plasmid DNA species. Using filter blot hybridization, we found several plasmids which were homologous to the small beta-lactamase-specifying plasmids pJB1 and pFA7, which were originally isolated from Haemophilus ducreyi and Neisseria gonorrhoeae, respectively. Detailed filter hybridization studies combined with electron microscope heteroduplex analysis suggested that three cryptic plasmids are completely homologous to the non-TnA sequences of pJB1. One cryptic plasmid was found to be highly homologous to pJB603, a small beta-lactamase plasmid previously found in two isolates of H. influenzae. A second group of plasmids were found to carry sequences homologous to pJB1 and other sequences homologous to pJB603. These results strongly suggest that small beta-lactamase plasmids found in Haemophilus species and N. gonorrhoeae may have arisen by insertion of the transposable beta-lactamase-specifying element TnA into small, phenotypically cryptic replicons resident in H. parainfluenzae. Attempts to reproduce such a recombination event in the laboratory were not successful.

DNA Transposable Elements↗
PubMed1986

Ileal perforation due to cytomegaloviral enteritis.

As the AIDS epidemic unfolds, many newly described clinical syndromes resulting from unusual manifestations of opportunistic infections are being seen. The authors report the clinical and pathological features of intestinal perforation in an AIDS patient caused by extensive small-bowel ulcerations due to cytomegalovirus. The diagnosis was confirmed by ultrastructural and immunohistochemical studies. It is suggested that infection and destruction of the muscularis propria by the virus contributes to intestinal perforation.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Local hepatic tuberculosis, the cause of a painful hepatic mass: case report and review of the literature.

Local hepatic tuberculosis is an unusual form of extrapulmonary tuberculosis. The authors describe the case of a 39-year-old woman with this disease who posed diagnostic difficulties. She presented with abdominal pain, minimal constitutional symptoms, hepatomegaly and radiologic findings of a focal hepatic lesion. Laparotomy was required for diagnosis. A literature review revealed that most individuals with local hepatic tuberculosis have fever, night sweats and weight loss. Hepatomegaly is often the only abnormal physical sign. Minimally elevated serum bilirubin and alkaline phosphatase levels are common. Ultrasonography and computerized tomography will demonstrate a lobulated, hypoechoic liver mass. Definitive diagnosis requires demonstration of acid-fast bacilli in biopsy material obtained by percutaneous techniques or at laparotomy. Cultures of the diseased liver are usually negative. Antituberculous drug therapy appears to be the preferred method of treatment.

Abdomen↗
PubMed1984

Comparison between short-term renal haemodynamic effects of propranolol and nadolol in essential hypertension: a cross-over study.

The effect of 4-6 weeks' treatment with propranolol and nadolol on effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) was studied, in 14 patients with essential hypertension, in single blind, random and cross-over design. Both drugs caused comparable effective lowering of pulse and blood pressure. When taken as the first drug, propranolol caused significant reduction in ERPF and GFR and a rise in filtration fraction (FF) and renal vascular resistance (RVR), whereas nadolol caused distinct rise in ERPF and a fall in FF and RVR but GFR remained unchanged. These haemodynamic effects were reduced when propranolol was given immediately after the withdrawal of nadolol and were obviated when nadolol followed propranolol therapy. This suggested a carry-over effect of the first drug into the second phase of treatment. We conclude that with short term therapy in essential hypertension, propranolol has a renal vasoconstrictor and nadolol a vasodilator effect.

Adrenergic beta-Antagonists↗
PubMed1983

Diarrhea among infants and young children in Canada: a longitudinal study in three northern communities.

Diarrhea among neonates and their siblings was studied in 98 families living in Winnipeg, Manitoba, and in 31 native Indian families and in 15 Inuit (Eskimo) families living in isolated settlements in northern Canada. The rate of infection due to rotavirus in neonates was significantly higher and infection occurred more often in the first six months of life in the northern communities (range, 0.36 in Winnipeg to 1.07 in Eskimo Point). No protective effect of breast-feeding was discerned, since infection due to rotavirus occurred more frequently and earliest in neonatal life in Eskimo Point, the community with the highest rate of breast-feeding. In contrast, infection due to Norwalk virus was most common among the neonates of Berens River (0.15 infections per child per year), the only community with relatively unsafe water supplies. Infection due to rotavirus appears to be more frequent in the far North, whereas infection due to Norwalk virus appears to be related more to inadequate sanitation.

Child↗