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Biomedical subjects

H R Smith

Publications and source records attributed to H R Smith.

At least 109 records · Page 6Linked to original sources
PubMed1996

General outbreaks of vero cytotoxin producing Escherichia coli O157 in England and Wales from 1992 to 1994.

We have reviewed all general outbreaks of infection due to Vero cytotoxin producing Escherichia coli (VTEC) O157 reported in England and Wales from 1992 to 1994. One hundred and seventy-three people were affected in 18 outbreaks, compared with 76 people in seven outbreaks in the preceding three years (1989 to 1991). Outbreaks occurred throughout England and Wales. Thirty-eight per cent of cases were admitted to hospital, 21% developed haemolytic uraemic syndrome, and 3% died. VTEC O157 infection causes particular concern because of its serious complications--haemorrhagic colitis and haemolytic uraemic syndrome, its capacity to spread from person to person as well as by food and water, and its reservoir in dairy and beef cattle.

Adult↗
PubMed1996

Vero cytotoxin-producing Escherichia coli, particularly serogroup O157, associated with human infections in England and Wales: 1992-4.

Investigations were performed by the Laboratory of Enteric Pathogens on Vero cytotoxin-producing Escherichia coli (VTEC) in England and Wales from 1992-4. Bacterial isolates, faeces and sera obtained from patients with diarrhoea, bloody diarrhoea and haemolytic uraemic syndrome were examined. Using serotyping, Vero cytotoxin gene probing and serodiagnostic tests for E. coli O157, evidence of infection was detected in 543, 434 and 491 individuals in 1992, 1993 and 1994 respectively; VTEC of serogroup O157 were isolated from 470, 385 and 411 cases. The O157 VTEC strains belonged to at least 19 different phage types (PT) although 84% belonged to PT2, PT49, PT8, PT1 or PT4. Antibodies to E. coli O157 lipopolysaccharide were detected in 13% of the cases. The average annual rate of infection with O157 VTEC was 0.83/100000 and 12% of the 1458 individuals with evidence of infection with VTEC or E. coli O157 developed haemolytic uraemic syndrome. There were at least 18 general outbreaks and many family outbreaks.

Adolescent↗
PubMed1996

Use of gene probes and adhesion tests to characterise Escherichia coli belonging to enteropathogenic serogroups isolated in the United Kingdom.

Nine hundred and twenty-five Escherichia coli isolates from cases of diarrhoea in the United Kingdom and belonging to enteropathogenic E. coli (EPEC) O serogroups were examined for virulence properties. The tests included adhesion to HEp-2 cells, the fluorescence actin staining (FAS) test (which correlates with the ability to cause attaching and effacing lesions) and DNA hybridisations with probes to detect sequences for eaeA (E. coli attaching and effacing factor), EAF (EPEC adherence factor), verocytotoxins VT1 and VT2, enteroaggregative E. coli and diffusely adherent E. coli. The O serogroups examined were 18, 26, 44, 55, 86, 111, 114, 119, 125, 126, 127, 128 and 142. Six hundred and sixty strains (71.4%) hybridised with at least one of the DNA probes. Over 80% of strains in O serogroups 26, 55, 119, 125, 127 and 142 and 41% of strains of serogroups 86, 111, 114, 126 and 128 hybridised with the eae probe and most showed localised attachment and were FAS-positive. However, <10% of these eae probe-positive strains hybridised with the EAF probe. Eighty-four of 232 strains in O serogroups 44, 86, 111, and 126 were enteroaggregative. VT genes were detected in 57 of 402 strains in O serogroups 26, 55, 111 and 128. Identification of EPEC by serogrouping was shown to be an effective method of identifying strains with pathogenic potential, although the organisms were diverse in their properties.

Bacterial Adhesion↗
PubMed1996

Zieve's syndrome a potential surgical pitfall?

Zieve's syndrome consists of transient haemolytic anaemic, jaundice, hyperlipidaemia and alcohol-induced liver disease. It is rare with less than 75 cases reported in a Medicine literature search from 1966. It can present acutely with abdominal pain.

Abdominal Pain↗
PubMed1996

Severe pulmonary dysfunction following acute respiratory distress syndrome.

Recovery of lung function following the acute respiratory distress syndrome (ARDS) is thought to be related to the severity of the initial insult. We report a case demonstrating virtually complete functional recovery following severe ARDS. The significance of this and the need for comprehensive follow-up of such patients is discussed.

Accidental Falls↗
PubMed1995

Enteroaggregative strains of Escherichia coli belonging to serotypes O126:H27 and O44:H18 express antigenically similar 18 kDa outer membrane-associated proteins.

Outer membrane-associated proteins of 18 kDa were expressed by enteroaggregative Escherichia coli (EAggEC) belonging to serotypes O126:H27 and O44:H18, which hybridized with a probe derived from a plasmid necessary for enteroaggregative adhesion. The 18 kDa proteins expressed by strains of E. coli, belonging to these serotypes, were surface exposed and antigenically similar but not structurally identical.

Antigens, Bacterial↗
PubMed1995

Detection and differentiation of the gene for toxin co-regulated pili (tcpA) in Vibrio cholerae non-O1 using the polymerase chain reaction.

The polymerase chain reaction has been used to differentiate the gene which encodes the toxin co-regulated pili (tcpA) of the El Tor and classical biotypes of Vibrio cholerae O1. The same PCR primers were applied to strains belonging to non-O1 serogroups that produced cholera toxin. The size of fragment amplified was either identical to the tcpA of biotype El Tor (471 bp) or to the tcpA of biotype classical (617 bp). All strains belonging to the novel epidemic serogroup O139 generated a 471-bp fragment identical to El Tor tcpA. The present study suggests that there may be an association between non-O1 serogroup and tcpA type.

Bacterial Outer Membrane Proteins↗
PubMed1995

A family of murine NK cell receptors specific for target cell MHC class I molecules.

The Ly-49A molecule is an NK cell receptor specific for MHC class I molecules on target cells. When Ly-49A engages H-2Dd, Ly-49A+ NK cells become globally incapable of killing their targets in vitro. This interaction also occurs in vivo. Ly-49A belongs to a family of highly related molecules, including Ly-49C (5E6 antigen) and LGL-1 that also determine NK cell specificity. In the NK gene complex, the Ly-49 family is genetically linked to genes encoding NKR-P1 and CD69 that are structurally related and capable of activating NK cells. Finally, Ly-49 may be related to human molecules that are selectively expressed on NK cells and influence NK cell specificity. These findings highlight the emerging significance of the Ly-49 family in NK cell activity.

Animals↗
PubMed1995

Catabolite repression of the adhesion of Vero cytotoxin-producing Escherichia coli of serogroups O157 and O111.

The virulence traits that mediate Vero cytotoxin-producing E. coli (VTEC) adherence are unclear. Many VTEC strains possess the eaeA gene which is involved in the attaching and effacing effects of enteropathogenic E. coli (EPEC). Most eae-positive VTEC adhered to HEp-2 cells in a localized manner; however some strains did not adhere. Thus we investigated the adhesion of poorly adherent strains, especially those of serogroups O111 and O157. To establish a model, the adherence to HEp-2, INT407 and Caco-2 cells of 12 O157 VTEC and six O111 VTEC isolated from cases of human infection were studied after growth of the bacteria under different conditions. For adhesion tests mannose is usually added during prior broth culture of the bacteria, and during the period of attachment, so that any adhesion due to mannose-sensitive type 1 pili is inhibited. Bacteria cultured in peptone water in the absence of mannose adhered to all three lines; there were localized clusters of bacteria on 1%-82% cells, whether mannose was present during the attachment period or not. Bacteria grown in the presence of D-mannose, or any other sugar that was metabolized, showed little adherence (range 0-9%). alpha-Methyl-glucoside also caused marked inhibition of adhesion. It was concluded that inhibition of adhesion was due to catabolite repression.

Animals↗
PubMed1995

Isolation of enterotoxigenic Escherichia coli from British troops in Saudi Arabia.

Specimens from 181 patients with diarrhoea were examined by a Military General Hospital in a 3-month period during deployment of troops to Saudi Arabia in 1990/1. DNA probes for heat labile (LT) and heat stable (ST) enterotoxin genes identified enterotoxigenic Escherichia coli (ETEC) in 47 of the specimens (26%) and 49 ETEC strains were isolated. The majority (55%) belonged to a novel ETEC serotype having the O-antigen 159 and a flagellar antigen designated as a provisional new type. They produced ST and the coli surface associated antigen (CS)6. Strains of serotype O6:H16 represented 22% of the ETEC examined. They produced ST, LT and CS3 together with either CS1 or CS2. The remaining ETEC belonged to seven O:H serotypes. Overall, ST was the only enterotoxin gene identified in 73% of the ETEC and 67% of the strains expressed CS6 in the absence of other colonization antigens. Resistance to three or more antibiotics was observed in 53% of the ETEC, including most of the O159 strains.

Anti-Bacterial Agents↗
PubMed1995

Do silicone breast implants cause autoimmune rheumatic diseases?

Current estimates are that up to a million women in the U.S. have breast implants with the predominant type being the silicone gel implant. Concerns have been raised regarding the safety of silicone gel breast implants with focus upon whether escaped gel might cause inflammatory and immune responses that subsequently lead to autoimmune rheumatic diseases such as progressive systemic sclerosis (scleroderma), systemic lupus erythematosus (SLE), Sjögren's syndrome or rheumatoid arthritis. A spectrum of illnesses ranging from local symptoms to systemic disease is seen in some patients with silicone breast implants, however, it remains to be determined whether such illnesses in these patients are coincidentally associated or are secondary to the implants. Our understanding of the relationship between the presence of autoimmune rheumatic diseases and silicone breast implants is limited. The available data indicate that silicone elicits a minimal immunological response as compared to conventional antigens. The histological, immunological and epidemiological experimental data derived from patients with silicone implants, as well as those from animal studies, are reviewed. These data do not convincingly demonstrate that there is a cause and effect relationship between silicone breast implants and autoimmune diseases. Further investigations are needed to clarify the interaction of silicone with the cellular and humoral immune systems, as well as with host and environmental factors.

Antibodies, Antinuclear↗
PubMed1994

Ly-49 multigene family expressed by IL-2-activated NK cells.

The susceptibility of a target cell to killing by NK cells is inversely correlated with target cell expression of MHC class I molecules. We have recently demonstrated that a murine NK cell surface molecule, Ly-49, is a primary determinant of IL-2-activated NK cell specificity by apparently acting as an inhibitory receptor. Ly-49 seems to interact with polymorphic regions of certain MHC class I molecules on target cells, yet is expressed only by a subset (15 to 20%) of NK cells. If the interaction between Ly-49 and MHC class I represents a paradigm for understanding IL-2-activated NK cell specificity and putative inhibitory IL-2-activated NK cell receptors, these effector cells should express other molecules, perhaps related to Ly-49, that provide the inhibitory receptor function. We now report the isolation of cDNAs, encoding polypeptides related to Ly-49, from a CD3-, IL-2-activated NK cell library. Full length PCR products were also cloned and sequenced, confirming expression in IL-2-activated NK cells. These cDNAs were homologous to the Ly-49 cDNA and seem to be derived from distinct genes. The new cDNAs encode type II integral membrane proteins having lectin superfamily homology and 66 to 79% amino acid identity with Ly-49A. In contrast to previous reports, these cDNAs cannot be allelic variants because they were all isolated from C57BL/6-derived cells. On the basis of nucleotide homology, the cDNAs could be segregated into five groups; one with Ly-49 itself (now termed Ly-49A) and four others containing distinct sequences. One of the new groups comprised three cDNAs that shared identical sequences, but differed from one another by deletions or insertions of short DNA segments in the predicted extracellular region of the polypeptides. Thus, IL-2-activated NK cells express mRNAs for multiple, Ly-49-related molecules.

Animals↗
PubMed1994

Prospective study of verocytotoxin-producing, enteroaggregative and diffusely adherent Escherichia coli in different diarrhoeal states.

One hundred and eighty-one stool specimens from patients with various types of diarrhoea (135 patients) or from non-diarrhoeal controls (23 acute medical patients, 23 inflammatory bowel disease in remission) were investigated using a colony-blot DNA hybridization assay for the presence of Verocytotoxin-producing (VTEC), enteroaggregative (EAggEC) and diffusely adherent (DAEC) Escherichia coli. Twelve patients had probe-positive EAggEC in the stool and 8 of these had diarrhoea, 6 following recent travel. Eight patients had DAEC, 7 of whom had travellers' diarrhoea. Six of 10 (60%) travellers with gastroenteritis, but without a recognized enteric pathogen, were positive for EAggEC (4) or DAEC (2). Five of 10 (50%) travellers with gastroenteritis related to a recognized enteric pathogen also had DAEC identified in their stool. Of the 23 acute medical control patients 11 had been abroad, 4 of these were immigrants and had EAggEC. VTEC were not found and, with one exception, immunoassays for antibodies to E. coli O 157 and O 2 lipopolysaccharides were negative.

Adult↗
PubMed1994

Isolates of Escherichia coli O44:H18 of diverse origin are enteroaggregative.

One hundred thirteen strains of Escherichia coli O44:H18 isolated in several countries over 25 years were examined for adhesion to tissue culture cells and for hybridization with DNA probes. Fifty-nine strains were from sporadic cases of infection; 54 were from 12 outbreaks. Of the 113 strains, 85 showed aggregative adhesion to HEp-2 cells; 36 were from sporadic cases and 49 were from 9 outbreaks. All adhesive strains hybridized with the probe for enteroaggregative E. coli (EAggEC) and 1 nonadhesive strain was also positive. However, 80 of the 86 EAggEC probe-positive strains also hybridized with the probe for diffusely adherent E. coli (DAEC) derived from the daaC gene of strain F1845. The EAggEC and DAEC probes hybridized to different fragments of a large plasmid in the O44:H18 strains.

Aged↗
PubMed1994

Adhesion to and invasion of human colon carcinoma Caco-2 cells by Aeromonas strains.

The enteropathogenicity of Aeromonas strains that showed mannose-resistant adhesion to INT407 cells was evaluated by infecting Caco-2 cells and observing them by light and electronmicroscopy. Five of six strains adhered in large numbers to Caco-2 cells in the presence of mannose and caused cytopathic effects. Two strains of Aeromonas spp. seemed to invade Caco-2 cells, as membrane-bound bacteria were seen within the cytoplasm of these cells; however, staining by acridine orange-crystal violet appeared to show intracellular fluorescent bacteria in three strains. Fimbriae did not appear to play an important role in adhesion because fimbrial structures were not seen by transmission electronmicroscopy. Adhesion of four strains was inhibited by the addition of L-fucose. The strains were negative in the fluorescence actin staining test, which in enteropathogenic Escherichia coli strains correlates with the ability to attach and efface intestinal microvilli. The DNA of the Aeromonas strains did not hybridise with the E. coli eae and ipaB probes, associated with attaching and effacing ability and invasion, respectively. These results give support to the enteropathogenicity of adhesive strains of Aeromonas spp., although the mechanisms of adhesion, and possibly invasion, remain to be elucidated.

Acridine Orange↗