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Biomedical subjects

J B Wilson

Publications and source records attributed to J B Wilson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Temporal and geographical distributions of reported cases of Escherichia coli O157:H7 infection in Ontario.

The distribution of 3001 cases of verocytotoxigenic Escherichia coli (VTEC) reported in the Province of Ontario, Canada, were examined to describe the magnitude of this condition geographically and to evaluate the spatial relationship between livestock density and human VTEC incidence using a Geographical Information System. Incidence of VTEC cases had a marked seasonal pattern with peaks in July. Areas with a relatively high incidence of VTEC cases were situated predominantly in areas of mixed agriculture. Spatial models indicated that cattle density had a positive and significant association with VTEC incidence of reported cases (P = 0.000). An elevated risk of VTEC infection in a rural population could be associated with living in areas with high cattle density. Results of this study suggested that the importance of contact with cattle and the consumption of contaminated well water or locally produced food products may have been previously underestimated as risk factors for this condition.

Agriculture↗
PubMed1999

Associations between virulence factors of Shiga toxin-producing Escherichia coli and disease in humans.

Associations between known or putative virulence factors of Shiga toxin-producing Escherichia coli and disease in humans were investigated. Univariate analysis and multivariate logistic regression analysis of a set of 237 isolates from 118 serotypes showed significant associations between the presence of genes for intimin (eae) and Shiga toxin 2 (stx2) and isolates from serotypes reported in humans. Similar associations were found with isolates from serotypes reported in hemorrhagic colitis and hemolytic-uremic syndrome. The enterohemorrhagic E. coli (EHEC) hemolysin gene was significantly associated with isolates from serotypes found in severe diseases in univariate analysis but not in multivariate logistic regression models. A strong association between the intimin and EHEC-hemolysin genes may explain the lack of statistical significance of EHEC hemolysin in these multivariate models, but a true lack of biological significance of the hemolysin in humans or in disease cannot be excluded. This result warrants further investigations of this topic. Multivariate analysis revealed an interaction between the eae and stx2 genes, thus supporting the hypothesis of the synergism between the adhesin intimin and Shiga toxin 2. A strong statistical association was observed between the stx2 gene and severity of disease for a set of 112 human isolates from eight major serotypes. A comparison of 77 isolates of bovine origin and 91 human isolates belonging to six major serotypes showed significant associations of the genes for Shiga toxin 1 and EspP protease with bovine isolates and an increased adherence on HEp-2 cell cultures for human isolates, particularly from diarrheic patients and healthy persons.

Adhesins, Bacterial↗
PubMed1999

Reliability of an ordinal rating system for assessing the amount of mud and feces (tag) on cattle hides at slaughter.

A study was conducted to provide a quantitative description of the amount of tag (mud, soil, and bedding) adhered to the hides of feedlot beef cattle and to appraise the statistical reliability of a subjective rating system for assessing this trait. Initially, a single rater obtained baseline data by assessing 2,417 cattle for 1 month at an Ontario beef processing plant. Analysis revealed that there was a strong tendency for animals within sale-lots to have a similar total tag score (intralot correlation = 0.42). Baseline data were summarized by fitting a linear model describing an individual's total tag score as the sum of their lot mean tag score (LMTS) plus an amount representing normal variation within the lot. LMTSs predicted by the linear model were adequately described by a beta distribution with parameters nu = 3.12 and omega = 5.82 scaled to fit on the 0-to-9 interval. Five raters, trained in use of the tag scoring system, made 1,334 tag score observations in a commercial abattoir, allowing reliability to be assessed at the individual level and at the lot level. High values for reliability were obtained for individual total tag score (0.84) and lot total tag score (0.83); these values suggest that the tag scoring system could be used in the marketing and slaughter of Ontario beef cattle to improve the cleanliness of animals presented for slaughter in an effort to control the entry of microbial contamination into abattoirs. Implications for the use of the tag scoring system in research are discussed.

Abattoirs↗
PubMed1999

Antenatal haemoglobin profile at Korle-Bu Teaching Hospital.

OBJECTIVE: To determine the frequency of haemoglobin (Hb) measurement and some socio-demographic characteristics in women attending antenatal clinic. DESIGN: Prospective cross-sectional study. SETTING: Antenatal clinic, Korle-Bu Teaching Hospital. SUBJECTS: Nine hundred and thirty two pregnant mothers attending antenatal clinic at the hospital. Patients with sickle cell disease, thalassaemia, sickling test positive or unknown sickling status were excluded. MAIN OUTCOME MEASURES: Proportion of patients whose records showed various frequencies of Hb determinations and the proportion of those with anaemia at 26 weeks and 34 weeks gestations. RESULTS: One hundred and seventy five (18.8%) patients did not have antenatal Hb measurement; 248 (26.6%) had two, and 251 (26.9%) had more than two measurements. The mean of booking Hb was 10.6 + 1.53 gm/dl. Of the 458 subjects with reliable dates, 293 had their booking Hb measurement at < 26 weeks. For this sub-group the mean was 10.8 +/- 1.43 gm/dl. (22.5% were < 10 gm/dl). For 272 subjects with reliable dates whose last Hb measurement was at > 34 weeks, the mean last Hb was 11.0 +/- 1.37 gm/dl. (last Hb was < 10 gm/dl in 19.1%). Nulliparity and booking antenatal weight < 64.0 kg were significantly associated with Hb < 10 gm/dl at some time during pregnancy. CONCLUSION: Anaemia in pregnancy is common in this urban population. Combined effects of iron-folate supplementation, malaria chemoprophylaxis as well as early booking and a waiver of antenatal care user fees for needy patients are suggested as remedial measures.

Anemia↗
PubMed1999

A descriptive study of the frequency and characteristics of proliferative enteropathy in swine in Ontario by analyzing routine animal health surveillance data.

Routine surveillance data, collected on pathology submissions at the Animal Health Laboratory in Guelph between 1992 and 1997, were analyzed to determine demographic, clinical, and pathologic characteristics of cases of proliferative enteropathy and the frequency of this condition relative to other infectious enteric diseases in swine in Ontario. The most commonly reported disease was Escherichia coli enteritis (average cases/year = 70.0). Among infectious enteropathies that occur typically in neonatal pigs, coccidiosis (28.4 cases/year) and rotaviral enteritis (5.6 cases/year) were reported. Among infectious enteropathies generally associated with diarrhea in weaner and grower/finisher pigs, the most frequently reported was proliferative enteropathy (27.6 cases/year), followed by swine dysentery (23.3 cases/year), transmissible gastroenteritis (19.6 cases/year), and salmonellosis (8.4 cases/year). Diarrhea and bloody diarrhea were reported in 29% and 31%, respectively, of herds diagnosed with proliferative enteropathy. Important gross intestinal lesions included mucosal hypertrophy (62% of cases), hemorrhage (47%), and mucosal necrosis (34%). Histologic intestinal lesions included epithelial hyperplasia (90% of cases), mucosal necrosis (59%), and inflammation (49%). Our results suggest that proliferative enteropathy is a major infectious enteric disease in grower/finisher pigs in Ontario.

Animal Husbandry↗
PubMed1998

Murine CASK is disrupted in a sex-linked cleft palate mouse mutant.

A transgenic mouse insertional mutant displayed the phenotype of altered cranial morphology with sex-linked cleft palate. We have cloned the disrupted genomic X-linked locus and report the identification of the mCASK gene. The gene is transcribed to produce two messages of 4.5 and 9.5 kb expressed during development and in adult tissues, particularly the brain. We describe the isolation of two differentially spliced mouse cDNAs from the locus (mCASK-A and mCASK-B). The mCASK-B cDNA probably represents the full-length product of the 4.5-kb transcript. The identical N-termini of the predicted encoded proteins (mCASK-A and -B) are highly homologous to Ca2+/calmodulin-dependent protein kinase II, while the deduced C-terminus of mCASK-B is highly homologous to a family of multidomain proteins containing a guanylate kinase motif, the MAGUK proteins. mCASK-B is a new member of an emerging family of genes in which the encoded proteins combine these domains, termed here, the CAMGUKs, including rat CASK, Caenorhabditis elegans lin-2, and Drosophila caki/camguk. The CAMGUKs are likely to be effectors in signal transduction as regulatory partners of transmembrane molecules, modulated by calcium and nucleotides. The transgene in this mutant mouse line integrated into an intron that bisects the encoded calmodulin-binding domain, a potentially important regulatory domain of the predicted protein, generating hybrid transcripts.

Alternative Splicing↗
PubMed1998

Risk factors for infection with verocytotoxigenic Escherichia coli in cattle on Ontario dairy farms.

Risk factors for prevalent infection with verocytotoxigenic Escherichia coli (VTEC) were studied in a random sample of 886 cows and 592 calves under 3 months of age on 80 randomly selected dairy farms in southern Ontario. Fecal-culture supernatants from each animal were screened for verocytotoxicity using a Vero cell assay (VCA) and for verocytotoxin (VT) genes by a polymerase chain reaction (PCR) procedure. Up to 20 F. colt isolates from positive samples were tested for VT production using VCA and PCR. VTEC isolates were serotyped. Farm managers were interviewed using a standardized questionnaire to obtain information on farm- and individual animal-level management practices and characteristics. There was a significant (P < 0.001) positive association between age of calves and their VTEC infection status, and calves were significantly more likely to be infected than cows. The proportion of calves infected on the farm was positively associated with both the use of regular pails for feeding calves (as opposed to nipple bottles or nipple pails) and bringing new animals into the herd in the previous year.

Age Factors↗
PubMed1998

ELISA detection of restriction site polymorphisms in the pig ryanodine receptor locus.

We compare two strategies for ELISA detection of restriction site polymorphisms (EDRSP) that are suitable for high-throughput genotyping of the pig ryanodine receptor point mutation (RYR1(hal)). In both procedures, target DNA is amplified by PCR with one primer that is 5' biotinylated and a second primer that is 5' fluoresceinylated. PCR products are captured in duplicate wells on a streptavidin-coated, 96-well plate. The duplicates may be treated in two ways. In a single restriction enzyme assay, one duplicate is exposed to a restriction enzyme that cuts one allele specifically, and the second duplicate is exposed to no restriction enzyme. In a dual restriction enzyme assay, the second replicate is exposed to a second restriction enzyme that cuts the alternate allele specifically. Thereafter, the two procedures are similar; anti-fluorescein antibodies conjugated to peroxidase are allowed to bind to the fluoresceinylated ends, the plate is washed, and a substrate is converted to a colored end product. The ratio of the absorbances in the two wells is used to classify subjects by genotype. When the dual restriction enzyme assay is run, three genotype groups are easily distinguishable. When the single restriction enzyme assay is run, heterozygotes generate values that may overlap with those of the homozygotes that are not cut by the restriction enzyme. Dual restriction enzyme assays are more accurate than single restriction enzyme assays; however, single restriction enzyme assays are sufficient for identifying pigs that carry RYR1(hal).

Animals↗
PubMed1998

Epstein-Barr virus LMP2A drives B cell development and survival in the absence of normal B cell receptor signals.

Epstein-Barr virus (EBV) establishes a persistent latent infection in peripheral B lymphocytes in humans and is associated with a variety of malignancies and proliferative disorders. Latent membrane protein 2A (LMP2A) is one of only two viral proteins expressed in latently infected B lymphocytes in vivo. LMP2A blocks B cell receptor (BCR) signal transduction in vitro by binding the Syk and Lyn protein tyrosine kinases. To analyze the significance of LMP2A expression in vivo, transgenic mice with B cell lineage expression of LMP2A were generated. LMP2A expression results in the bypass of normal B lymphocyte developmental checkpoints allowing immunoglobulin-negative cells to colonize peripheral lymphoid organs, indicating that LMP2A possesses a constitutive signaling activity in nontransformed cells.

Animals↗
PubMed1998

Escherichia coli O157:H7 diarrhoea associated with well water and infected cattle on an Ontario farm.

A 16-month old female child living on an Ontario dairy farm was taken to hospital suffering from bloody diarrhoea. Escherichia coli O157:H7 was isolated from her stool. Initial tests of well water samples were negative for E. coli by standard methods but culture of selected coliform colonies on sorbitol-MacConkey agar led to isolation of E. coli O157:H7. E. coli O157:H7 was also isolated from 63% of cattle on the farm. The E. coli O157:H7 isolates from the child, the water and the cattle were phage type 14, produced verotoxins 1 and 2, and were highly related on analysis by pulsed field gel electrophoresis. The child did not have known direct contact with the cattle and did not consume unpasteurized milk. Hydrogeological investigation revealed the design and location of the well would allow manure-contaminated surface water to flow into the well. This investigation demonstrates that cattle farm well water is a potential source of E. coli O157:H7 which may not be identified by standard screening for E. coli in water.

Agriculture↗
PubMed1998

A case-control study of verocytotoxigenic Escherichia coli infection in cats with diarrhea.

The objectives of this study were to determine the prevalence of enteric verocytotoxigenic E. coli (VTEC) infection in a population of cats in Ontario, and to determine whether an association exists between the presence of VTEC and feline diarrhea. Fecal samples from 179 cats, representing 113 cats with diarrhea and 66 cats with normal feces, were cultured for E. coli. The fecal cultures were screened for verocytotoxin activity with a Vero cell assay. Confirmation of the presence of verocytotoxin (VT) genes was done with polymerase chain reaction (PCR) amplification; the frequency of occurrence of the genes for generic VT, VT1, and VT2 was determined. VTEC-positive samples were defined as those that demonstrated cytotoxicity on the Vero cell assay and yielded E. coli possessing one or more of the VT genes. All VTEC-positive isolates were serotyped. The overall prevalence of enteric VTEC infection in the cats was 12.3% (22/179). Statistical analysis of the case-control data showed no significant association between VTEC infection and diarrheal illness. The majority of the cats with VT-positive E. coli were positive for the presence of the generic VT, rather than for VT1 or VT2; it is therefore possible that a novel verocytotoxin gene may exist in E. coli isolated from cats. Eight VTEC strains were identified by serotyping; 4 of these serotypes have previously been isolated from humans, and 2 from cattle, suggesting that cats may be capable of acting as reservoirs for human and bovine VTEC serotypes.

Animals↗
PubMed1997

Smoking behavior of recent mothers, 18-44 years of age, before and after pregnancy: United States, 1990.

OBJECTIVE: This report presents a comprehensive review of data on the smoking behaviors of women with a recent birth from the 1990 National Health Interview Survey. Data on current and lifetime smoking status and smoking behaviors before and after learning of pregnancy are presented. Selected demographic characteristics of women--including age, race, education, and family income--are also presented. METHODS: Data presented in this report are from the 1990 National Health Interview Survey on Health Promotion and Disease Prevention (NHIS-HPDP). Questions on pregnancy and smoking were administered as part of this supplement to women 18-44 years of age who either had a live birth in the 5 years preceding the interview, or who were pregnant at the time of the interview. These analyses were limited to women with a live birth in the 5 years preceding the 1990 NHIS who were not currently pregnant. RESULTS: Of 13,674,000 women with a recent live birth, about 39 percent had ever smoked, 25 percent smoked in the year before they became pregnant, and 15 percent smoked during their most recent pregnancy. Women who smoked prior to learning of their pregnancy were most likely to be moderate smokers, white women, never married, and of lower income. Women who smoked after learning of their pregnancy were most likely to be light smokers, representing a shift in smoking behaviors after learning of pregnancy. Nearly 23 percent of women reported that they stopped smoking altogether after learning of their pregnancy. CONCLUSIONS: These findings are consistent with data from other sources and provide support for recently observed trends in smoking and pregnancy. A majority of women who had ever smoked continued to smoke throughout pregnancy. Although many women altered their smoking behaviors, only about one quarter of women reported that they stopped smoking entirely. Public health service messages must continue to encourage women to stop smoking entirely during pregnancy to maximize the health benefits to their infants.

Adult↗
PubMed1997

From abandoned warehouse to life-saving facility, Pakro, Ghana. The Accra PMM Team.

PRELIMINARY STUDIES: Focus group discussions in Akwapim South District, Ghana, highlighted a lack of accessible health facilities as an important factor contributing to maternal deaths. INTERVENTIONS: In 1991, a health center was established by rennovating an abandoned warehouse. The center was equipped with beds, a refrigerator, a safe water supply, drugs and supplies. With the posting of a community health nurse from the Ministry of Health (MOH), it began functioning as a maternal and child health/family planning clinic. A senior nurse-midwife was posted in 1992 and obstetric services were offered. Starting in 1994, community interventions focused on reducing the delay in seeking care. RESULTS: An average of nine women with major obstetric complications were seen each 12-month period between 1992 and 1995. Many minor complications and non-obstetric ailments were also treated. COSTS: The material costs of establishing the health center amounted to US $12,550: 47% came from the community, 43% came from non-governmental organizations (NGOs), 7% from PMM and 3% from MOH. The costs of staff salaries were paid by MOH. CONCLUSIONS: It is possible to mobilize communities, government and NGOs to help provide emergency obstetric services. If emergency obstetric services are available, women will use them, even before the launching of community information and education campaigns.

Community Health Centers↗
PubMed1997

The maternity waiting home concept: the Nsawam, Ghana experience. The Accra PMM Team.

PRELIMINARY STUDIES: Focus group discussions with community members in Nsawam District, Ghana, identified poor roads, scarce transport and exorbitant fees for emergency transport as barriers to reaching the district hospital for treatment of an obstetric complication. INTERVENTIONS: To minimize delay in the event of a complication, a maternity waiting home (MWH) was established in Nsawam in 1994. One ward of an abandoned hospital was renovated and furnished for this purpose. The objective was to encourage women at high risk of obstetric complications to move to the MWH so they could be transferred to the hospital when labor began. RESULTS: Of 25 women referred to the MWH by health personnel over 12 months, only one complied, for one night. Focus group discussions with community members and hospital staff later revealed that cost and hardship of staying away from home, absence of health personnel, distance from hospital, desolate surroundings and lack of perceived need were reasons for poor utilization. COSTS: The intervention cost approximately US $10,500, shared approximately equally between the project and government. The main government contribution was the building. CONCLUSIONS: It is important to consult potential users not only to identify problems, but also to identify appropriate solutions. Careful 'market research' should be done before launching interventions.

Emergencies↗
PubMed1997

Persistence of Escherichia coli O157:H7 in dairy cattle and the dairy farm environment.

The persistence of Escherichia coli O157:H7 in cattle and the farm environment was investigated on eight Ontario dairy farms positive for E. coli O157:H7 in a longitudinal study commenced one year previously. Faecal samples from cows, calves, humans, cats, rodents, wild birds, a composite fly sample and numerous composite and individual environmental samples were cultured and tested for verotoxin-producing E. coli (VTEC). VTEC isolates were serotyped and E. coli O157:H7 isolates were phage typed. E. coli O157:H7 phage type 34 was isolated from one calf on each of two farms. The same phage type had been isolated on one of these farms 12 months earlier. Most E. coli O157:H7-positive animals and farms became culture-negative within 2 and 3 months, respectively. E. coli O157:H7 was not isolated from any environmental samples, although evidence of VTEC was found in composite samples from calf feeders (19.1%), calf barn surfaces (18%), cow feeders (14.9%), flies (12.5%), cow barn surfaces (11.3%), and individual milk filters (12.5%). VTEC belonging to 21 non-O157 serotypes were isolated from 24 cows (8.2%), 21 calves (18.3%), 2 cow feeder samples (3.0%), and 1 calf feeder sample (4.8%). Shedding of E. coli O157:H7 by infected dairy cattle appears to be transient and persistence of E. coli O157:H7 was not demonstrated from the farm environment sites tested.

Animals↗
PubMed1996

Expression of Epstein-Barr virus nuclear antigen-1 induces B cell neoplasia in transgenic mice.

The Epstein-Barr virus (EBV) nuclear antigen-1 (EBNA-1) is a pleiotropic protein which has been characterized extensively both biochemically and functionally. It is the only one of the identified latent protein-encoding genes to be consistently expressed in viral-associated endemic Burkitt's lymphoma cells. As such, it is the only candidate viral protein to possibly perform a maintenance function in the tumour pathology. Despite this, no oncogenic activity has been attributed to the protein in tissue culture assays. The experiments described here were initiated to explore the activity of the protein in B cells in vivo. EBNA-1 transgenic mice were generated with transgene expression directed to the B cell compartment using the mouse Ig heavy chain intron enhancer. Transgene expression was demonstrated in the lymphoid tissues of mice of two independent lines. Transgenic positive mice of both lines succumb to B cell lymphoma. The B cell tumours are monoclonal, frequently of follicular centre cell origin and remarkably similar to those induced by transgenic c-myc expression. These results demonstrate that EBNA-1 is oncogenic in vivo and suggest that the gene product may play a direct role in the pathogenesis of Burkitt's lymphoma and possibly other EBV-associated malignancies.

Animals↗
PubMed1996

Pregnancy, abortion, and birth rates among US adolescents--1980, 1985, and 1990.

OBJECTIVE: To analyze pregnancy, abortion, and birth rates among US adolescent girls in 1980, 1985, and 1990. DESIGN: Retrospective analysis of trends in data on pregnancies, abortions, and births. POPULATION: US adolescent girls aged 13 to 19 years. MAIN OUTCOME MEASURES: Pregnancy, abortion, and birth rates (with and without adjustment for sexual experience) among teenaged girls aged 15 to 19 years and girls under 15 years. RESULTS: Although pregnancy rates among all teenaged girls 15 to 19 years old remained fairly stable from 1980 to 1985, they increased by 9% during the last half of the decade, totaling 95.9 pregnancies per 1000 teenaged girls 15 to 19 years old by 1990. Because rates of sexual experience increased even faster, pregnancy rates among sexually experienced teens aged 15 to 19 actually declined between 1980 and 1990 by approximately 8%. Abortion rates among these teens remained stable during the 1980s, with 35.8 and 36.0 abortions per 1000 in 1980 and 1990, respectively. As with overall pregnancy rates, abortion rates among these sexually experienced teenaged girls declined during the 1980s. Between 1980 and 1985, birth rates among teenaged girls aged 15 to 19 years declined by 4%, but they increased by 18% during the latter half of the decade, totaling 59.9 births per 1000 in 1990. Among these sexually experienced teenagers, birth rates also declined between 1980 and 1985 and then increased over the next 5 years. In 1990, pregnancies and abortions among girls younger than 15 years accounted for only 3% of all adolescent pregnancies and abortions. However, the number of births among these younger adolescents increased by 15% over the decade. In that age group, trends in pregnancy, abortion and birth rates over the decade were similar to those for older teens. However, during the late 1980s, the abortion rate declined and the pregnancy rate remained stable, resulting in a 26% increase in the birth rate. CONCLUSIONS: Despite efforts to reduce adolescent pregnancy in the United States, pregnancy and birth rates for that group continue to be the highest among developed countries. Considering that 95% of adolescent pregnancies are unintended, increased efforts to prevent these pregnancies are warranted.

Abortion, Induced↗