PubMed Health⌕ Search

Biomedical subjects

H J Ball

Publications and source records attributed to H J Ball.

At least 37 records · Page 2Linked to original sources
PubMed2001

A comparison of a monoclonal antibody-based sandwich ELISA and immunomagnetic bead selective enrichment for the detection of Escherichia coli O157 from bovine faeces.

AIMS: To compare a recently developed monoclonal antibody (MAb) based sandwich ELISA (sELISA) with an immunomagnetic separation (IMS) method for the detection of Escherichia coli O157 in bovine faeces. METHODS AND RESULTS: Faecal samples from 345 cattle were obtained from eight farms in Northern Ireland, in which human disease due to E. coli O157 had occurred. Both assays detected E. coli O157 on five of the farms and the phage-type of the majority of the bovine strains were the same as the corresponding human isolates. Similar numbers of the organism were detected by the two methods, 59 by the sELISA and 53 by the IMS procedure, 39 of the positive samples being common to both. Twenty samples were sELISA positive/IMS negative. CONCLUSIONS: If the IMS is regarded as the gold standard, then the sELISA is less sensitive and less specific, but under the conditions used sELISA positive results were obtained from all positive farms, and the sELISA gave a presumptive positive a day earlier than the IMS method. SIGNIFICANCE AND IMPACT OF THE STUDY: The sELISA has the potential to be used as a rapid method for screening large numbers of samples for E. coli O157, but further work is required to determine its specificity.

Animals↗
PubMed2001

Changes in lymphocyte subsets in the bronchus-associated lymphoid tissue of goats naturally infected with different Mycoplasma species.

The distribution of cells containing lysozyme, S-100 protein, CD3, CD4, CD8, major histocompatibility complex class II antigen and immunoglobulin G (IgG) was analysed in the bronchus-associated lymphoid tissue (BALT) of goats naturally infected with three Mycoplasma species. This study included the immunohistochemical characterization of the pneumonic lesions of 18 goats (3-5 months old) infected with one of the following Mycoplasma species: M. mycoides ssp. mycoides, Large Colony type (goats no. 1-6), M. mycoides ssp. capri (goats no. 7-12) and M. capricolum ssp. capricolum (goats no. 13-18). Microscopically, infected animals showed a moderate broncho-interstitial pneumonia, characterized by lymphoid hyperplasia of the BALT and infiltration of mononuclear cells in the alveolar walls and airways. The main cellular type in the BALT was represented by CD3+ T lymphocytes, and the ratio of CD4+:CD8+ cells was > 2. The BALT showed large germinal centres mainly composed of IgG+ B lymphocytes, with numerous S-100+ follicular dendritic cells. The presence of follicular dendritic cells confirmed the high degree of organization of this lymphoid tissue. The immunohistochemical results showed that activated T lymphocytes, particularly in the CD4 subset, and IgG+ B cells, play a major role in the immune response of the caprine lung infected with these species of mycoplasmas.

Animals↗
PubMed2001

Comparative evaluation of four decontamination protocols for the isolation of Mycobacterium avium subsp. paratuberculosis from milk.

AIMS: Four chemical decontamination protocols for milk were compared with respect to mean percentage recovery of spiked Mycobacterium avium subsp. paratuberculosis, minimum detection limit and ease of application. METHODS AND RESULTS: Raw milk spiked with 106 cfu M.a. paratuberculosis was decontaminated prior to culture by: (1) treatment with 0.75% (w/v) hexadecylpyridinium chloride (HPC) for 5 h; (2) and (3) Cornell methods employing brain heart infusion broth containing 0.75% (w/v) and 0.9% (w/v) HPC, respectively; and (4) a C18-carboxypropylbetaine (CB-18) METHOD: The 0.75% HPC method yielded the highest mean percentage recovery of M.a. paratuberculosis (28.7%) and was capable of detecting the lowest number of cells (30 cfu/40 ml). CONCLUSION: Treatment of milk with 0.75% HPC for 5 h was shown to be superior to the other methods for decontaminating milk prior to culture for M.a. paratuberculosis. SIGNIFICANCE AND IMPACT OF STUDY: Certain chemical decontamination protocols are too harsh for application to milk. The "best" decontamination protocol only recovered a fraction of the M.a. paratuberculosis cells present in a milk sample.

Animals↗
PubMed2001

Bactericidal effect of chlorine on Mycobacterium paratuberculosis in drinking water.

AIMS: One possible route of transmission of Mycobacterium paratuberculosis from cattle to humans is via contaminated water supplies. The aim of this work was to determine whether this organism can survive standard water treatment processes. METHODS AND RESULTS: Two strains of M. paratuberculosis (bovine strain, NCTC 8578 and human strain Linda, ATCC 43015) were subjected to various chlorine concentrations (0.5, 1.0 and 2.0 microg ml(-1)) for 15 and 30 min. Chlorine test solutions were made up in two types of water, sterile water that had been deionized and subjected to reverse osmosis (DRO) and DRO water containing MgCl(2), CaCl(2), NaHCO(3) and bovine serum albumin (0.3% w/v), the latter to mimic conditions the organism would experience in commercial water treatment operations. CONCLUSION: The data showed that when initial inoculum levels were high (10(6) cfu ml(-1)) neither M. paratuberculosis strain was completely killed at the free chlorine concentrations and contact times applied. Log10 reductions in the range 1.32-2.82 were observed. The greatest log(10) reduction in cell numbers (2.82 and 2.35 for the bovine and human strains, respectively) was observed at the highest chlorine concentration (2 microg ml(-1)) and longest contact time (30 min). SIGNIFICANCE AND IMPACT OF THE STUDY: This work highlights the need for further research into the survival of M. paratuberculosis during water treatment.

Chlorine↗
PubMed2000

Improved detection of Mycobacterium avium subsp. paratuberculosis In milk by immunomagnetic PCR.

The potential use of a novel immunomagnetic PCR (IMS-PCR) technique as a rapid method to screen milk samples for the presence of Mycobacterium avium subsp. paratuberculosis (M. ptb) was assessed. Immunomagnetic separation (IMS) for M. ptb, developed at Queen's University, Belfast, was applied to milk samples prior to IS900 PCR in order to selectively concentrate any M. ptb cells present and, at the same time, separate the cells from constituents of milk likely to inhibit subsequent PCR. This increased the sensitivity of IS900 PCR. IMS-PCR sensitivity could be further increased by initial centrifugation (2500 g for 20 min) of larger volumes of milk (10 and 50 ml), and resuspension of the sediment into a 1 ml volume appropriate for IMS treatment. Following IMS, template DNA for IS900 PCR was obtained by heating the bead-cell suspension in a thermal cycler at 100 degrees C for 15 min. It was estimated that the IMS-PCR assay could detect approximately 10(3)CFU of M. ptb per 50 ml of milk (equivalent to 20 CFU/ml), whereas the minimum detection limit of direct IS900 PCR was estimated at 10(5)CFU of M. ptb per 50 ml (equivalent to 2000 CFU/ml). A blind trial was carried out in which a total of 40 spiked (10(6)CFU M. ptb) and unspiked, raw and laboratory-pasteurised milk samples were independently tested by IMS-PCR and conventional IS900 PCR. IMS-PCR correctly identified 97. 5% of milk samples (sensitivity 100%, specificity 95%), including spiked milk samples before and after laboratory-pasteurisation. One false positive result was obtained which may have resulted from carryover between samples during the IMS procedure. Conventional IS900 PCR correctly identified only 72.5% of the same 40 milk samples (sensitivity 23%, specificity 100%). IMS-PCR was also shown to be capable of detecting natural M. ptb infection in raw sheep's milk, and raw and commercially pasteurised cows' milk.

Animals↗
PubMed2000

Application of an indirect ELISA to milk samples to identify cows with Mycoplasma bovis mastitis.

An indirect ELISA was used to detect antibodies to Mycoplasma bovis in milk samples collected from a herd with M bovis mastitis. Antibodies were detected in samples from nine cows which had developed clinical M bovis mastitis. Milk from only three consistently antigen-negative cows tested positive for M bovis antibodies. These results indicate the potential value of the indirect ELISA for the detection of cows which have recently developed M bovis mastitis during the early stages of an outbreak.

Animals↗
PubMed2000

Immunohistochemical characterization of lung lesions induced experimentally by Mycoplasma agalactiae and Mycoplasma bovis in goats.

Goats aged 3 months were inoculated with a recent isolate of Mycoplasma agalactiae (five animals) or Mycoplasma bovis (five animals) by a combined (intratracheal+intranasal) route. Two control goats were inoculated by the same route with sterile mycoplasma broth. Animals were killed 14 or 21 days after infection. At necropsy, tracheal and lung tissue was taken for pathological and immunohistochemical examination to determine changes in the lymphocyte subpopulations in the bronchus-associated lymphoid tissue (BALT). Consolidation of the lungs was not observed in any animal. M. agalactiae or M. bovis was recovered from the respiratory tract and lung of all but two infected animals. Both Mycoplasma spp. induced a moderate bronchointerstitial pneumonia, characterized by lymphoid hyperplasia of the BALT and infiltration of mononuclear cells into the alveolar walls. The predominant phagocytic cell in the pulmonary parenchyma and the airways was the macrophage. The main cellular type in the BALT was the CD3(+)T lymphocyte, and the ratio of CD4(+): CD8(+)cells was >1. It is likely that cellular immune mechanisms, through the activation of CD4(+)T lymphocytes, plays a prominent role in the acute and subacute phase of these infections.

Animals↗
PubMed2000

The ETO protein disrupted in t(8;21)-associated acute myeloid leukemia is a corepressor for the promyelocytic leukemia zinc finger protein.

The ETO protein was originally identified by its fusion to the AML-1 transcription factor in translocation (8;21) associated with the M2 form of acute myeloid leukemia (AML). The resulting AML-1-ETO fusion is an aberrant transcriptional regulator due to the ability of ETO, which does not bind DNA itself, to recruit the transcriptional corepressors N-CoR, SMRT, and Sin3A and histone deacetylases. The promyelocytic leukemia zinc finger (PLZF) protein is a sequence-specific DNA-binding transcriptional factor fused to retinoic acid receptor alpha in acute promyelocytic leukemia associated with the (11;17)(q23;q21) translocation. PLZF also mediates transcriptional repression through the actions of corepressors and histone deacetylases. We found that ETO is one of the corepressors recruited by PLZF. The PLZF and ETO proteins associate in vivo and in vitro, and ETO can potentiate transcriptional repression by PLZF. The N-terminal portion of ETO forms complexes with PLZF, while the C-terminal region, which was shown to bind to N-CoR and SMRT, is required for the ability of ETO to augment transcriptional repression by PLZF. The second repression domain (RD2) of PLZF, not the POZ/BTB domain, is necessary to bind to ETO. Corepression by ETO was completely abrogated by histone deacetylase inhibitors. This identifies ETO as a cofactor for a sequence-specific transcription factor and indicates that, like other corepressors, it functions through the action of histone deactylase.

Acute Disease↗
PubMed1999

The promyelocytic leukemia zinc finger (PLZF) protein binds DNA in a high molecular weight complex associated with cdc2 kinase.

A binding site selection from a CpG island library for the promyelocytic leukemia zinc finger protein (PLZF) identified two high affinity PLZF binding sites. These sequences also bound RARalpha/PLZF, a fusion protein formed in chromosomal translocation t(11;17)(q23;q21) associated with acute promyelocytic leukemia. PLZF bound DNA as a slowly migrating complex with an estimated mol. wt of 600 kDa whose formation was dependent on the POZ/dimerization domain of PLZF. The PLZF-DNA complex was unable to form in the presence of cdc2 antibodies. A PLZF-cdc2 interaction was further demonstrated by co-immunoprecipitation and a biotin-streptavidin pull-down assay. PLZF is a phosphoprotein and immunoprecipi-tates with a cdc2-like kinase activity. The PLZF-DNA complex was abolished with the addition of a phosphatase. These studies suggest that the activity of PLZF, a regulator of the cell cycle, may be modulated by cell cycle proteins. RARalpha/PLZF did not complex with cdc2, this potentially contributing to its aberrant transcriptional properties and potential role in leukemo-genesis.

Animals↗
PubMed1999

Comparison of Staphylococcus aureus recovered from personnel in a poultry hatchery and in broiler parent farms with those isolated from skeletal disease in broilers.

Personnel from one broiler hatchery, and workers on 18 separate broiler parent farms which supply the hatchery, were tested for hand and nasal carriage of Staphylococcus aureus. In both locations, nasal carriage of S. aureus was more common than hand carriage. A total of 63 S. aureus strains were characterised by biotyping, protein A analysis and pulsed field gel electrophoresis (PFGE) typing. Of these, 36 were recovered from broiler hatchery personnel, 14 from broiler parent farm personnel and 13 from cases of skeletal disease in commercial broilers. Biotyping and protein A analysis indicated that none of the strains recovered from hatchery personnel were of the poultry biotype, but that two strains recovered from the hands of two broiler parent farm personnel could be grouped together with 12/13 of strains recovered from skeletal disease in broilers, as poultry biotypes. PFGE-typing could not distinguish 9/13 strains recovered from skeletal disease in broilers and one of the strains from the broiler parent farm personnel from isolate 24 (I. 24), which is the predominant S. aureus strain type associated with clinical disease in N. Ireland broiler flocks. The present study found no evidence of nasal carriage of S. aureus strains of poultry biotype by humans. The finding of hand carriage by broiler parent farm personnel, suggests that handling by personnel may contribute to the dissemination of I. 24 or other S. aureus strains associated with skeletal disease in broilers.

Animal Husbandry↗
PubMed1999

Leukemia translocation protein PLZF inhibits cell growth and expression of cyclin A.

The PLZF gene was identified by its fusion with the RARalpha locus in a therapy resistant form of acute promyelocytic leukemia (APL) associated with the t(11;17)(q23;q21) translocation. Here we describe PLZF as a negative regulator of cell cycle progression ultimately leading to growth suppression. PLZF can bind and repress the cyclin A2 promoter while expression of cyclin A2 reverts the growth suppressed phenotype of myeloid cells expressing PLZF. In contrast RARalpha-PLZF, a fusion protein generated in t(11;17)(q23;q21)-APL activates cyclin A2 transcription and allows expression of cyclin A in anchorage-deprived NIH3T3 cells. Therefore, cyclin A2 is a candidate target gene for PLZF and inhibition of cyclin A expression may contribute to the growth suppressive properties of PLZF. Deregulation of cyclin A2 by RARalpha-PLZF may represent an oncogenic mechanism of this chimeric protein and contribute to the aggressive clinical phenotype of t(11;17)(q23;q21)-associated APL.

3T3 Cells↗
PubMed1999

Comparison of necrotoxigenic Escherichia coli isolates from farm animals and from humans.

Necrotoxigenic Escherichia coli (NTEC) isolated from animals and humans can belong to the same serogroups/types and produce or carry the genes coding for fimbrial and afimbrial adhesins of the same family, P, S, F17, and/or AFA, raising the question of a potential zoonotic source of human infection. The main purpose of this study was to compare 239 NTEC1 strains (45 from cattle, 65 from humans and 129 from piglets) and 98 NTEC2 strains from cattle, using a uniform and standardized typing scheme. The O serogroups and the biotypes recognized amongst NTEC1 and NTEC2 strains were quite varied, although some were more frequently observed (serogroups O2, O4, O6, O8, O18, O78, and O83 and biotypes 1, 2, 5, 6, and 9). Hybridization, results with gene probes for the P family (PAP probe), S family (SFA probe), AFA family (AFA probe), F17 family (F17 probe) of fimbrial and afimbrial adhesins, could differentiate most NTEC1 strains, which are PAP-, SFA- and/or AFA-positive, from NTEC2 strains, which are mainly F17- and/or AFA-positive, but were of no help in differentiating between NTEC1 strains from cattle, humans, and piglets. All but seven (98%) NTEC1 and NTEC2 strains were serum resistant, 199 (59%) produced an aerobactin, and colicin (I, V, or unidentified) was produced by 22-34% of them. On the other hand, more than 90% of the NTEC1 strains were haemolytic on sheep blood agar compared with only 40% of the NTEC2 strains. Production of a classical haemolysin, active on sheep erythrocytes, and hybridization with the PAP probe were associated in a majority of NTEC1 strains (63-81%), but very rarely in NTEC2 strains (3%). Production of enterohaemolysin and hybridization with the PAP probe were much less frequently associated in NTEC strains (1-9%). It was thus possible neither to completely differentiate NTEC1 strains from cattle, humans, and pigs, nor to define a signature for the NTEC strains. Necrotoxigenic E. coli must still be identified on the basis of the production of the Cytotoxic Necrotizing Factors 1 or 2 (or of their encoding genes) and complete differentiation of NTEC1 strains from cattle, humans, and piglets, use additionnal methods.

Animals↗
PubMed1999

Effect of higher pasteurization temperatures, and longer holding times at 72 degrees C, on the inactivation of Mycobacterium paratuberculosis in milk.

Raw cow's milk spiked with 10(6) cfu ml-1 of Mycobacterium paratuberculosis was subjected to heat treatments of 72, 75, 78, 80, 85 or 90 degrees C for 15 s, and 72 degrees C for 20 and 25 s, using laboratory pasteurizing units. Three bovine strains of Myco. paratuberculosis were studied (NCTC 8578, B2 and DVL 943). Each strain was subjected to all the heat treatments indicated on three separate occasions. Although each of the heat treatments achieved a substantial (5-6 log10) reduction in numbers of viable Myco. paratuberculosis, small numbers of the organism (4-16 cfu 10 ml-1) survived in a proportion of the milk samples at each of the higher temperatures investigated, right up to 90 degrees C for 15 s. A longer holding time of 25 s at 72 degrees C was found to be more effective at inactivating Myco. paratuberculosis. Only one of the three strains studied, B2, yielded small numbers of survivors after heating at 72 degrees C for 20 s, but it was completely inactivated by extending the holding time at 72 degrees C by a further 5 s to 25 s. It was concluded that a longer holding time is more likely to achieve the complete inactivation of Myco. paratuberculosis in milk than a higher pasteurization temperature.

Animals↗
PubMed1999

Development of an experimental model of bacterial chondronecrosis with osteomyelitis in broilers following exposure to Staphylococcus aureus by aerosol, and inoculation with chicken anaemia and infectious bursal disease viruses.

A series of experiments was designed in an attempt to reproduce bacterial chondronecrosis with osteomyelitis in broiler chickens using a natural route of infection. Birds in isolators were exposed to a suspension of Staphylococcus aureus by aerosol or exposed to S. aureus and subsequently inoculated with chicken anaemia virus (CAV) alone, or with CAV and infectious bursal disease virus (IBDV). Subsequently, S. aureus was recovered and bacterial chondronecrosis with osteomyelitis was diagnosed, by histology, in the proximal end of the femur and/or tibiotarsus of lame birds exposed to S. aureus with and without CAV and IBDV infections. Birds fed 60% of the recommended feed intake for the breed developed a lower incidence of S. aureus infection and/or bacterial chondronecrosis (P < 0.05) than birds fed 100% of the recommended intake. A significantly lower incidence of S. aureus was recovered (P < 0.05) in birds simultaneously exposed to S. aureus and inoculated with CAV and IBDV at day 21, than in birds exposed to S. aureus at day 10, and inoculated with CAV and IBDV at day 21. With the exception of birds exposed to S. aureus at 1 day old, a higher incidence of bacterial chondronecrosis was diagnosed in birds exposed to S. aureus and inoculated with CAV and IBDV than in birds exposed to S. aureus alone. It is hypothesised that inoculation with CAV and IBDV at day 21 enhanced the development of bacterial chondronecrosis in birds exposed to S. aureus at day 10 and fed 100% of the recommended feed intake or ad libitum.

Journal Article↗