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Biomedical subjects

H R Smith

Publications and source records attributed to H R Smith.

At least 163 records · Page 9Linked to original sources
PubMed1990

Expression of CFA/I fimbriae is positively regulated.

Production of the plasmid-coded fimbrial antigen CFA/I of Escherichia coli requires both CFA/I region 1 and CFA/I region 2, which are separated by about 40 kb on the wildtype plasmid. The nucleotide sequence of region 2 was determined and contains an open reading frame (cfa d), encoding a protein of 265 amino acids. The protein has no signal sequence and upon sequence analysis appeared to be a DNA-binding protein. A plasmid was constituted, with a promoterless beta-galactosidase gene preceded by the promoter of region 1. Introduction of a plasmid, carrying the cfa d gene, into a strain containing this construct enhanced expression of beta-galactosidase by at least five-fold indicating that the cfa d protein was enhancing expression from the promoter of region 1. The cfa d gene sequence differed at 28 positions from the Rns gene, which encodes a protein that is a positive regulator of the expression of CS1 or CS2 fimbriae. It was shown that the cfa d gene and the Rns gene can functionally substitute each other in regulating fimbrial synthesis.

Amino Acid Sequence↗
PubMed1990

Properties of strains of Escherichia coli O26:H11 in relation to their enteropathogenic or enterohemorrhagic classification.

Thirty-seven strains of Escherichia coli O26:H11 from infants and calves with diarrhea were examined for properties associated with enteropathogenic (EPEC) or enterohemorrhagic E. coli (EHEC). Strains were heterogeneous with respect to Vero cytotoxin (VT) production and hybridization with the EHEC plasmid-specific (CVD419) probe; 26 strains produced VT1; 1 produced VT2. Twenty-four of 27 VT+ strains and 5 of 10 VT- strains hybridized with the CVD419 probe and produced enterohemolysin; these properties are characteristic of EHEC. The strains did not hybridize with the EPEC adherence factor probe, a property characteristic of some EPEC. Nevertheless, 36 strains adhered to HEp-2 cells in a localized manner and were positive by the fluorescence actin staining (FAS) test that is considered to correlate with the ability to cause attaching and effacing lesions in vivo. EPEC and EHEC cause these lesions. Although the FAS test appeared to be the most general pathogenicity test for the O26:H11 strains, it could not be used to assign strains specifically to EPEC or EHEC groups.

Animals↗
PubMed1990

Attaching and effacing lesions in vivo and adhesion to tissue culture cells of Vero-cytotoxin-producing Escherichia coli belonging to serogroups O5 and O103.

Certain isolates of Escherichia coli from humans and animals with enteric disease attach to enterocytes and cause 'attaching and effacing' (AE) lesions. E. coli strain S22-1, serotype O103:H2, isolated from a child with diarrhoea, contained two plasmids; one of these (pDEP12) hybridized with the CVD419 DNA probe derived from a plasmid found in E. coli O157:H7 and associated with expression of fimbriae and ability to adhere to Intestine 407 cells. Strain S102-9, serotype O5:H-, isolated from a calf with dysentery, contained six plasmids, one of which also hybridized with the CVD419 probe. Loss of pDEP12 coincided with reduced adhesion to HEp-2 or Intestine 407 cells cultured in vitro; reintroduction of this plasmid restored adhesiveness. Loss of the plasmid in strain S102-9 that hybridized with the CVD419 probe did not cause a decrease in adhesion. Accumulations of actin were seen in vitro in the fluorescence actin staining (FAS) test of strains S22-1, S102-9 and their derivatives, irrespective of the plasmid content of these strains or the prevalence of attached bacteria. Strain S22-1 and its plasmidless derivative caused AE lesions of equal severity in experimentally infected gnotobiotic piglets; piglets inoculated with an isolate from a healthy human or pig did not develop these lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adhesins, Escherichia coli↗
PubMed1990

Examination of strains belonging to enteropathogenic Escherichia coli serogroups for genes encoding EPEC adherence factor and Vero cytotoxins.

Four hundred and forty-nine strains isolated from patients with diarrhoea and belonging to 13 enteropathogenic Escherichia coli (EPEC) O serogroups were tested with a DNA probe for the EPEC adherence factor (EAF). Positive results were obtained with only 36 strains; they belonged to 10 O serogroups and flagellar typing showed they were usually of the "classical" EPEC serotypes. Thirty-four of the 36 EAF-positive strains showed localised adhesion to HEp-2 cells. The two remaining strains, of serotypes O114:H2 and O127:H4, showed low level or no adhesion to HEp-2 cells. No colonies hybridising with the EAF probe were identified in cultures from 115 faecal specimens from healthy children. Sixteen of the 449 strains hybridised with one or both probes for the Vero cytotoxin genes VT1 and VT2; 15 of the 16 strains belonged to serogroups O26 and O128. None of the strains hybridised with both the EAF and VT gene probes. These studies show that the great majority of strains belonging to EPEC O serogroups do not possess the EPEC adherence factor or carry VT genes.

Bacterial Adhesion↗
PubMed1990

Haemolytic uraemic syndromes in the British Isles, 1985-8: association with verocytotoxin producing Escherichia coli. Part 2: Microbiological aspects.

In a three year study of children under 16 years with haemolytic uraemic syndrome faecal samples were examined for the presence of Verocytotoxin producing Escherichia coli (VTEC) using DNA probes and for free neutralisable Verocytotoxin in a Vero cell assay with specific antisera. There was evidence of VTEC infection in 58 of 185 (31%) samples. A total of 53 VTEC was identified from patients with haemolytic uraemic syndrome. Thirty eight VTEC belonged to serotype O157:H7 or O157:H-, 34 produced VT2 only, and four strains produced both VT1 and VT2. The remaining 15 VTEC belonged to nine different O serogroups; three strains produced VT1, 10 produced VT2, and two were positive for VT1 and VT2. Three control groups of patients without haemolytic uraemic syndrome were also examined. There was evidence of VTEC infection in 8%, 6%, and 4% of specimens from individuals with bloody diarrhoea, those with diarrhoea only, and healthy controls respectively. VTEC from the bloody diarrhoeal and diarrhoeal controls were O157:H7 but those from the healty controls could not be O serogrouped. This study confirms the association of VTEC, and particularly strains of O157:H7, with haemolytic uraemic syndrome. Strains producing VT1, VT2, or both toxins were isolated, although over 94% of VTEC produced VT2 alone or together with VT1.

Adolescent↗
PubMed1990

CD5+ B lymphocytes in systemic lupus erythematosus and rheumatoid arthritis.

B lymphocytes which express the CD5 antigen on their cell surface have the ability to produce autoantibodies in vitro. We describe 2 patients, one with systemic lupus erythematosus and another with rheumatoid arthritis, whose percentages of peripheral blood CD5+ B lymphocytes were dramatically increased to 68 and 100%, respectively. A reduction of this subpopulation of B cells was associated with clinical improvement after therapy. This association suggests a relationship between CD5+ B cells and autoimmune disease activity.

Adult↗
PubMed1990

Production of anticardiolipin antibodies by cultured human lymphocytes.

Antibodies against negatively charged phospholipids, such as those to cardiolipin, can often be detected in the serum of patients with autoimmune related conditions, chronic infections and in patients treated with phenothiazines. In the present study, peripheral blood lymphocytes from nine healthy controls and eight patients with phenothiazine-induced IgM anticardiolipin antibodies (ACA) and the lupus anticoagulant were placed in vitro. Culture supernatants were assayed for ACA by measurement of optical densities using an ELISA. A significant difference (p less than 0.05) was demonstrated between the mean concentration of culture supernatant ACA from the patients as compared to healthy controls. The concentration of ACA in culture supernatants strongly correlated (r = 0.85) with that from the serum. There was a weak correlation between serum and culture supernatant ACA concentration and the lupus anticoagulant activity as measured by prolongation of the partial thromboplastin time. This technique uses readily accessible peripheral blood lymphocytes and should permit dissection of cytokine and cellular immune pathways regulating APA production.

Antiphospholipid Syndrome↗
PubMed1990

Autoimmune MRL-1 pr/1pr mice are an animal model for the secondary antiphospholipid syndrome.

Patients with systemic lupus erythematosus often develop thrombosis, recurrent abortion, thrombocytopenia and neurological disease, in association with serum antibodies against phospholipids, termed the secondary antiphospholipid syndrome. In our search for an animal model for the human antiphospholipid syndrome, we examined the MRL-1pr/pr mouse, which develops a lupus-like illness. These mice were found to have significantly elevated levels of serum antiphospholipid antibodies (aPL) and thrombocytopenia compared to normal mice. By immunodiffusion, these antibodies are similar to human aPL. We observed histologic evidence of central nervous system thromboses as well as perivascular infiltrates of the choroid plexus. The high titers of serum aPL, thrombocytopenia, and thrombosis establish this strain as an animal model for the secondary antiphospholipid syndrome.

Animals↗
PubMed1989

Adhesion to cells in culture and plasmid profiles of enteropathogenic Escherichia coli isolated from outbreaks and sporadic cases of infant diarrhoea.

Enteropathogenic strains of Escherichia coli (EPEC) that caused 10 outbreaks of infant diarrhoea in the U.K. between 1968 and 1986 were studied. All gave localised adherence (LA) to HEp-2 cells, HeLa cells and Intestine 407 cells in culture. All hybridised with the EPEC adherence factor (EAF) probe. The hybridising sequences were carried on plasmids ranging in size from 26 to 76 MDa. EPEC from sporadic cases of infant diarrhoea occurring between 1979 and 1986 that belonged to the same serotypes as the outbreak strains were also studied. All strains of serotypes O111ab.H2, O114.H2, O119.H6, O127.H6 and O142.H6 gave LA and were EAF-positive. In other serotypes, non-adhering strains or strains giving diffuse adherence were found also. In addition, strains of serotype O128.H2 which gave LA but did not hybridise with the EAF probe were identified. The strains isolated from sporadic cases of diarrhoea in the U.K. were similar, with respect to adhesion and hybridisation, to those isolated from sporadic cases of diarrhoea in developing countries.

Bacterial Adhesion↗
PubMed1989

Phage-typing of Vero-cytotoxin (VT) producing Escherichia coli O157 isolated in the United Kingdom.

Vero-cytotoxin (VT) producing Escherichia coli serogroup O157 have been isolated from patients with diarrhoea, haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS). A phage-typing scheme developed in Canada has been used to type 155 VT+ E. coli O157 serogroup isolated from sporadic infections in the UK since 1983, and 48 strains from HC or HUS outbreaks. Twelve phage types were identified of which three, types 49, 51 and 52, have not been found in North America. All strains carried a 60 x 10(6) plasmid and most VT1+VT2+ strains also had a 5 x 10(6) plasmid coding for colicin D production. The majority of strains producing both VT1 and VT2 belonged to phage type 1, or the related types 4, 8 and 14. Most strains producing only VT2 belonged to types 2 or 49. Four outbreaks were included in the survey. Three had strains of a single phage type while strains from the fourth outbreak were more variable. The distribution of phage types throughout the UK showed no marked geographical variations.

Bacterial Toxins↗
PubMed1989

Properties of Vero cytotoxin-producing Escherichia coli of human and animal origin belonging to serotypes other than O157:H7.

Eight non-O157:H7 Vero cytotoxin (VT)-producing Escherichia coli (VTEC) strains isolated from ill persons and nine bovine and lamb strains of serogroups matching the human strains, were characterized for various properties known to be associated with E. coli virulence. Five different serogroups were represented: O5, O55, O103, O111 and O153. The bovine and lamb strains produced VT1, while 3 human strains produced VT1, 3 produced VT2 and 2 were positive for both VT1 and VT2. The strains were non-haemolytic on horse blood agar, did not produce either heat stable toxin A (STA) or heat labile toxin (LT), and were noninvasive. The CVD419 probe which has been proposed to identify enterohaemorrhagic E. coli (EHEC) hybridized with all of the O5 and O103 strains, none of the O55 and O153 strains, and 3 of the 4 O111 strains. The strains carried several different sized plasmids and hybridization of Southern blots with the CVD419 probe identified plasmids ranging in size from 42 x 10(6) to 90 x 10(6). The strains did not hybridize with the enteroadherence factor (EAF) probe derived from an enteropathogenic strain and associated with the ability to give localized adherence to HEp-2 cells. Nevertheless five of the strains adhered in a localized pattern to HEp-2 cells and Intestine 407 cells. Adhesion to either HEp-2 or Intestine 407 cells did not correlate with hybridization with the CVD419 probe or haemagglutinating properties.

Animals↗
PubMed1989

Properties of adherence factor plasmids of enteropathogenic Escherichia coli and the effect of host strain on expression of adherence to HEp-2 cells.

EPEC adherence factor (EAF) plasmids from three strains of enteropathogenic Escherichia coli (EPEC) - E2347/69 (O127:H6), E20517 (O111:H2) and E24582 (O142:H6) - were examined. The EAF plasmids were all marked with ampicillin resistance by transposition of Tn801 to give pDEP1, pDEP2 and pDEP11, respectively. All three plasmids showed incompatibility with an FIme and an FIV plasmid and had some similarity in restriction enzyme digest patterns. Plasmid pDEP1 differed from pDEP2 and pDEP11 in being autotransferring and fertility-inhibition positive. An EAF probe consisting of a 1 kb BamHI-SalI restriction endonuclease fragment of the prototype EAF-associated plasmid pMAR2 hybridized to similar-sized SalI-BamHI fragments of pDEP1 and pDEP11 but to a different-sized fragment of plasmid pDEP2. Loss of the EAF plasmids from EPEC strains resulted in a marked reduction in the ability of these strains to adhere to HEp-2 cells. The EAF-plasmid-negative variants did not express a 94 kDa outer-membrane protein (OMP). When these EAF plasmids were reintroduced into EAF-plasmid-negative EPEC strains a high level of adherence equivalent to that of the parent EPEC strains was restored and a 94 kDa OMP was usually expressed. However, when EAF plasmids were transferred into E. coli K12 or non-EPEC E. coli the host strains either did not adhere or adhered poorly to the HEp-2 cells. These transconjugants did not express a 94 kDa OMP.

Adhesins, Escherichia coli↗
PubMed1989

Comparison of Vero-cytotoxin-encoding phages from Escherichia coli of human and bovine origin.

Phages encoding production of Vero cytotoxins VT1 or VT2 were isolated from strains of Escherichia coli of human and bovine origin. Two human strains of serotype O157: H7 produced both VT1 and VT2 and each carried two separate phages encoding either VT1 or VT2. The phages were morphologically similar to each other and to a VT2 phage previously isolated from a strain of serotype O157: H-; all had regular hexagonal heads and short tails. The phages had similar genome sizes and DNA hybridization and restriction enzyme digestion showed that the DNAs were very closely related. This contrasts with another report that one of the strains tested (933) released two clearly distinguishable phages separately encoding VT1 and VT2. The O157 phages differed from a VT1 phage isolated from a bovine E. coli strain belonging to serotype O26: H11 and from the reference VT1 phage isolated previously from a human strain, H19, of serotype O26: H11. The two O26 phages were morphologically similar with elongated heads and long tails. They had similar genome sizes and DNA hybridization indicated a high level of homology between them. Hybridization of an O157 phage DNA probe to DNA of the O26 phages, and vice versa, showed there was some cross-hybridization between the two types of phage. A phage from a bovine strain of serotype O29: H34 had a regular hexagonal head and short tail resembling those of the O157 phages. The DNA was distinguishable from that of all the other phages tested in restriction digest patterns but hybridized significantly to that of an O157 phage. Hybridization of the phage genomes with VT1 and VT2 gene probes showed that sequences encoding these toxins were highly conserved in the different phages from strains belonging to the three serogroups.

Animals↗
PubMed1989

Identification of Escherichia coli that produces heat-stable enterotoxin STA by a commercially available enzyme-linked immunoassay and comparison of the assay with infant mouse and DNA probe tests.

By using the infant mouse test and a commercially available competitive enzyme-linked immunosorbent assay (ELISA), 100 strains of Escherichia coli carrying STA1 or STA2 genes were shown to produce the heat-stable enterotoxin STA. An additional 100 strains were negative in both tests. The ELISA was easy to perform, and results were available within 24 h. Testing strains with an enzyme-linked DNA probe kit that incorporated both STA1- and STA2-specific oligonucleotides showed that the 100 strains positive in the mouse test and ELISA also hybridized with the mixed probe. Two strains carrying STA1 genes but negative in the mouse test and ELISA also hybridized with the mixed probe.

Animals↗
PubMed1989

Acute non-infectious arthritis of the hip in rheumatoid arthritis: synovial membrane findings.

A case of acute hip pain in rheumatoid arthritis is presented, with synovial membrane findings. A patient with classical rheumatoid arthritis suffered three unusual bouts of sudden, severe but transient hip pain. The hips were clinically normal between these episodes. The clinical picture on two of these occasions strongly suggested septic arthritis. Although the synovial fluid was highly inflammatory, cultures were negative. The synovial membrane showed mild lining cell hyperplasia, vascular congestion, and scattered inflammatory cells, predominantly lymphocytes. These findings were not compatible with either pyogenic infection or longstanding rheumatoid arthritis. The clinical and pathological features of acute non-infectious arthritis of the hip appear to delineate a distinct syndrome.

Acute Disease↗
PubMed1989

Antibodies to Escherichia coli O157 in patients with haemorrhagic colitis and haemolytic uraemic syndrome.

Twenty four sera from patients with haemolytic uraemic syndrome or haemorrhagic colitis and healthy controls were examined for antibodies to the lipopolysaccharide (LPS) of Escherichia coli O157. Faecal specimens from these patients were also examined for Vero cytotoxin producing E coli (VTEC) by DNA probes, and for faecal Vero cytotoxin. Eight patients with faecal E coli O157:H7 gave a strong antibody response to O157 LPS, shown by immunoblotting and an enzyme linked immunosorbent assay. Six symptomatic patients without evidence of faecal VTEC also gave a strong antibody response to O157 LPS. Sera from the remaining five patients and five healthy controls did not contain antibodies to E coli O157. The results suggest that the testing of sera from patients with haemorrhagic colitis or haemolytic uraemic syndrome by ELISA or immunoblot would prove valuable in addition to the established procedures for detecting VTEC, using DNA probes and testing for faecal Vero cytotoxin.

Antibodies, Bacterial↗
PubMed1989

Spectrum of prostanoid release after bronchoalveolar allergen challenge in atopic asthmatics and in control groups. An alteration in the ratio of bronchoconstrictive to bronchoprotective mediators.

Prostanoids have been implicated in the pathogenesis of asthma because of their potential role in the modulation of airway tone. In the present study, the bronchoconstrictors prostaglandin D2 (PGD2) and thromboxane (TX), and those prostanoids able to protect against bronchoconstriction, prostaglandin E2 (PGE2), and the stable metabolite of prostacyclin, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), were measured in bronchoalveolar lavage fluid (BALF) before and 5 min after endobronchial allergen challenge in four subject groups: nonatopic nonasthmatics (n = 6), nonatopic asthmatics (n = 3), atopic nonasthmatics (n = 9), and atopic asthmatics (n = 8). There were no significant differences in prechallenge prostanoid levels between the four groups, with the potentially bronchoprotective mediators present in highest concentration. Allergen challenge in atopic asthmatics resulted in significant increases (p less than 0.05) in PGD2 (97.4 +/- 19.4 to 1,053.2 +/- 338.6 pg/ml, mean +/- SEM) and TX (45.5 +/- 7.5 to 150.7 +/- 37.8 pg/ml) over prechallenge levels and control groups. Similarly, histamine increased in the atopic asthmatics after challenge (0.36 +/- 0.22 to 6.84 +/- 1.86 ng/ml; p less than 0.05). Atopic nonasthmatics had slight increases in PGD2 (96.9 +/- 25.4 to 219.7 +/- 47.5 pg/ml; p greater than 0.1) after challenge, whereas PGD2 and TX did not change in nonatopic subjects. A significant positive correlation was found between histamine, PGD2, and TX levels after challenge among all groups (p less than 0.001). There were no significant changes among the four groups after allergen challenge in 6-keto-PGF1 alpha or PGE2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗