Work-family life courses and BMI trajectories in three British birth cohorts.

BACKGROUND/OBJECTIVES: Combining work and family responsibilities has previously been associated with improved health in mid-life, yet little is known about how these associations change over time (both biographical and historical) and whether this extends to body mass index (BMI) trajectories for British men and women. The purpose of this study was to investigate relationships between work-family life courses and BMI trajectories across adulthood (16-42 years) for men and women in three British birth cohorts. SUBJECTS/METHODS: Multiply imputed data from three nationally representative British birth cohorts were used-the MRC National Survey of Health and Development (NSHD; 1946 birth cohort, n=3012), the National Child Development Study (NCDS; 1958 birth cohort, n=9614) and the British Cohort Study (BCS; 1970 birth cohort, n=8140). A typology of work-family life course types was developed using multi-channel sequence analysis, linking annual information on work, partnerships and parenthood from 16 to 42 years. Work-family life courses were related to BMI trajectories using multi-level growth models. Analyses adjusted for indicators of prior health, birthweight, child BMI, educational attainment and socioeconomic position across the life course, and were stratified by gender and cohort. RESULTS: Work-family life courses characterised by earlier transitions to parenthood and weaker long-term links to employment were associated with greater increases in BMI across adulthood. Some of these differences, particularly for work-family groups, which are becoming increasingly non-normative, became more pronounced across cohorts (for example, increases in BMI between 16 and 42 years in long-term homemaking women: NSHD: 4.35 kg m-2, 95% confidence interval (CI): 3.44, 5.26; NCDS: 5.53 kg m-2, 95% CI: 5.18, 5.88; BCS: 6.69 kg m-2, 95% CI: 6.36, 7.02). CONCLUSIONS: Becoming a parent earlier and weaker long-term ties to employment are associated with greater increases in BMI across adulthood in British men and women.

Antimicrobial susceptibilities and random amplified polymorphic DNA-PCR fingerprint characterization of Lactococcus lactis ssp. lactis and Lactococcus garvieae isolated from bovine intramammary infections.

In total, 181 streptococci-like bacteria isolated from intramammary infections (IMI) were submitted by a veterinary clinic to Quality Milk Production Services (QMPS, Cornell University, Ithaca, NY). The isolates were characterized by sequence analysis, and 46 Lactococcus lactis ssp. lactis and 47 Lactococcus garvieae were tested for susceptibility to 17 antibiotics. No resistant strains were found for ß-lactam antibiotics widely used in clinical practice (penicillin, ampicillin, and amoxicillin), and all minimum inhibitory concentrations (MIC) were far from the resistance breakpoints. Eight strains had MIC intermediate to cefazolin. The random amplification of polymorphic DNA (RAPD)-PCR fingerprint patterns showed a slightly higher heterogeneity for Lc. lactis ssp. lactis isolates than for Lc. garvieae isolates.

Human Brucella canis Infection and Subsequent Laboratory Exposures Associated with a Puppy, New York City, 2012.

Human Brucella canis infection incidence is unknown. Most identified cases are associated with pet dogs. Laboratory-acquired infections can occur following contact with Brucella spp. We identified a paediatric B. canis case, the source and other exposed persons. A 3-year-old New York City child with fever and dyspnoea was hospitalized for 48 h for bronchiolitis. After her admission, blood culture grew B. canis, she was prescribed anti-microbials and recovered. B. canis was also isolated from blood of the child's pet dog; these isolates were genetically similar. The dog originated from an Iowa breeding facility which was quarantined after identification of the dog's infection. Additionally, 31 laboratory workers were exposed and subsequently monitored for symptoms; 15 completed post-exposure prophylaxis. To our knowledge, this is the first report strongly suggesting B. canis zoonotic transmission to a child in the United States, and highlights the need for coordinated control policies to minimize human illness.

Antimicrobial drug resistance patterns among cattle- and human-associated Salmonella strains.

During the year 2004, 178 human and 158 bovine clinical Salmonella isolates were collected across New York State to better understand the transmission dynamics and genetic determinants of antimicrobial resistance among human and bovine hosts. Serotyping, sequence typing, and pulsed-field gel electrophoresis typing results have been reported previously. Here we tested all isolates for phenotypic susceptibility to 15 antimicrobial drugs that are part of the National Antimicrobial Monitoring System bovine susceptibility panel. PCR was performed on a representative subset of unique isolates (n = 53) to screen for the presence of 21 known antimicrobial resistance genes (i.e., ampC, blaTEM-1, blaCMY-2, blaPSE-1, cat1, cat2, cmlA, flo, aadA1, aadA2, aacC2, strA, strB, aphA1-IAB, dhrfI, dhrfXII, sulI, sulII, tetA, tetB, and tetG); selected fluoroquinolone- and nalidixic acid-resistant (n = 3) and -sensitive (n = 6) isolates were also tested for known resistance-conferring mutations in gyrA and parC. Genes responsible for antimicrobial resistance were shared among isolates of human and bovine origin. However, bovine isolates were significantly more likely than human isolates to be multidrug resistant (P < 0.0001; Fisher's exact test). Our analyses showed perfect categorical agreement between phenotypic and genotypic resistance for beta-lactam and chloramphenicol. Our data confirm that resistance profiles of amoxicillin-clavulanic acid, chloramphenicol, kanamycin, and tetracycline were strongly associated with the presence of blaCMY or ampC, flo, aphA1-IAB, and tetA, respectively. Our findings provide evidence for the clinical value of genotypic resistance typing if incorporating multiple known genes that can confer a phenotypic resistance profile.

Equine stomachs harbor an abundant and diverse mucosal microbiota.

Little is known about the gastric mucosal microbiota in healthy horses, and its role in gastric disease has not been critically examined. The present study used a combination of 16S rRNA bacterial tag-encoded pyrosequencing (bTEFAP) and fluorescence in situ hybridization (FISH) to characterize the composition and spatial distribution of selected gastric mucosal microbiota of healthy horses. Biopsy specimens of the squamous, glandular, antral, and any ulcerated mucosa were obtained from 6 healthy horses by gastroscopy and from 3 horses immediately postmortem. Pyrosequencing was performed on biopsy specimens from 6 of the horses and yielded 53,920 reads in total, with 631 to 4,345 reads in each region per horse. The microbiome segregated into two distinct clusters comprised of horses that were stabled, fed hay, and sampled at postmortem (cluster 1) and horses that were pastured on grass, fed hay, and biopsied gastroscopically after a 12-h fast (cluster 2). The types of bacteria obtained from different anatomic regions clustered by horse rather than region. The dominant bacteria in cluster 1 were Firmicutes (>83% reads/sample), mainly Streptococcus spp., Lactobacillus spp. and, Sarcina spp. Cluster 2 was more diverse, with predominantly Proteobacteria, Bacteroidetes, and Firmicutes, consisting of Actinobacillus spp. Moraxella spp., Prevotella spp., and Porphyromonas spp. Helicobacter sp. sequences were not identified in any of 53,920 reads. FISH (n = 9) revealed bacteria throughout the stomach in close apposition to the mucosa, with significantly more Streptococcus spp. present in the glandular region of the stomach. The equine stomach harbors an abundant and diverse mucosal microbiota that varies by individual.

The prevalence of multidrug resistance is higher among bovine than human Salmonella enterica serotype Newport, Typhimurium, and 4,5,12:i:- isolates in the United States but differs by serotype and geographic region.

Salmonella represents an important zoonotic pathogen worldwide, but the transmission dynamics between humans and animals as well as within animal populations are incompletely understood. We characterized Salmonella isolates from cattle and humans in two geographic regions of the United States, the Pacific Northwest and the Northeast, using three common subtyping methods (pulsed-field gel electrophoresis [PFGE], multilocus variable number of tandem repeat analysis [MLVA], and multilocus sequence typing [MLST]). In addition, we analyzed the distribution of antimicrobial resistance among human and cattle Salmonella isolates from the two study areas and characterized Salmonella persistence on individual dairy farms. For both Salmonella enterica subsp. enterica serotypes Newport and Typhimurium, we found multidrug resistance to be significantly associated with bovine origin of isolates, with the odds of multidrug resistance for Newport isolates from cattle approximately 18 times higher than for Newport isolates from humans. Isolates from the Northwest were significantly more likely to be multidrug resistant than those from the Northeast, and susceptible and resistant isolates appeared to represent distinct Salmonella subtypes. We detected evidence for strain diversification during Salmonella persistence on farms, which included changes in antimicrobial resistance as well as genetic changes manifested in PFGE and MLVA pattern shifts. While discriminatory power was serotype dependent, the combination of PFGE data with either MLVA or resistance typing data consistently allowed for improved subtype discrimination. Our results are consistent with the idea that cattle are an important reservoir of multidrug-resistant Salmonella infections in humans. In addition, the study provides evidence for the value of including antimicrobial resistance data in epidemiological investigations and highlights the benefits and potential problems of combining subtyping methods.

Antimicrobial resistance impacts clinical outcome of granulomatous colitis in boxer dogs.

BACKGROUND: Escherichia coli have recently been identified within the colonic mucosa of Boxer dogs with granulomatous colitis (GC). Eradication of invasive E. coli is associated with clinical and histological remission. OBJECTIVES: To determine antimicrobial susceptibility profiles of E. coli strains from GC and healthy dogs, and the association of antimicrobial resistance with clinical outcome. ANIMALS: Fourteen Boxer dogs with GC and 17 healthy pet dogs. METHODS: Prospective study: E. coli was cultured from GC biopsies and rectal mucosal swabs of healthy dogs. Individual strains were selected by phylogroup and overall genotype, determined by triplex- and random amplified polymorphic DNA-polymerase chain reaction respectively. Antimicrobial susceptibility was determined by broth microdilution minimal inhibitory concentration. RESULTS: Culture yielded 23 E. coli strains from GC (1-3/dog, median 2) and 34 strains from healthy (1-3/dog, median 2). E. coli phylogroups were similar (P=.18) in GC (5A, 7B1, 5B2, 6D) and healthy (2A, 10B1, 15B2, 7D). Resistance to ampicillin, amoxicillin-clavulanate, cefoxitin, tetracycline, trimethoprim-sulfa (TMS), ciprofloxacin, and chloramphenicol was greater (P<.05) in GC (21-64%) than healthy (0-24%). Enrofloxacin resistant E. coli were isolated from 6/14 GC versus 0/17 healthy (P=.004). Of the enrofloxacin resistant cases, 4/6 were also resistant to macrophage-penetrating antimicrobials such as chloramphenicol, rifampicin, and TMS. Enrofloxacin treatment before definitive diagnosis was associated with antimicrobial resistance (P<.01) and poor clinical outcome (P<.01). CONCLUSIONS AND CLINICAL IMPORTANCE: Antimicrobial resistance is common among GC-associated E. coli and impacts clinical response. Antimicrobial therapy should be guided by mucosal culture and antimicrobial susceptibility testing rather than empirical wisdom.

The risk of Listeria monocytogenes infection in beef cattle operations.

AIM: To determine the prevalence of Listeria monocytogenes and associated risk factors among beef operations (cow-calf and feedlot) in central and southern California. METHODS AND RESULTS: A repeated cross-sectional study where faecal and environmental samples were collected from 50 operations three times a year at different seasons was carried out. Samples were tested for presence of L. monocytogenes using a combination of enrichment and polymerase chain reaction tests. Data on putative risk factors were also collected. Listeria monocytogenes was detected in faecal samples from cows, calves and other animals on calf-cow operations at proportions of 3.1%, 3.75% and 2.5%, respectively. The organism was detected in 5.3% of cut-grass, 5.3% of soil, 14.3% of irrigation ditches, 3.1% of the ponds and 6.5% of water troughs samples. Listeria monocytogenes was less common in faecal (0.3%) and soil (0.75%) samples collected from feedlots. CONCLUSIONS: Listeria monocytogenes was present at a higher proportion among cow-calf operations than feedlots. There was no significant seasonal variation in the occurrence of this pathogen within the two types of operations. SIGNIFICANCE AND IMPACT OF THE STUDY: If risk mitigation strategies were implemented to reduce the public health risk these should focus in cow-calf operations.

Salmonella enterica serotype 4,5,12:i:-, an emerging Salmonella serotype that represents multiple distinct clones.

The prevalence, among human clinical cases, of Salmonella enterica serotype 4,5,12:i:-, a serotype antigenically similar to Salmonella enterica serotype Typhimurium but lacking second-phase flagellar antigens, has increased considerably over the last 10 years. To probe the evolution and ecology of this emerging serotype, we characterized 190 Salmonella isolates initially classified as Salmonella serotypes 4,5,12:i:- (n = 90) and Typhimurium (n = 100) and obtained from various sources in the United States and Spain. These isolates were characterized into six sequence types (determined by multilocus sequence typing [MLST]) and 79 pulsed-field gel electrophoresis types. The majority of Salmonella serotype 4,5,12:i:- and Typhimurium isolates (85 and 84 isolates, respectively) represented a single MLST type. Existing genome information revealed different genome deletions (which included genes responsible for phase 2 flagellum expression) in four Spanish Salmonella serotype 4,5,12:i:- isolates and one U.S. Salmonella serotype 4,5,12:i:- isolate. Fifty-nine isolates of both serotypes, representing different sources and geographical locations as well as different molecular subtypes, were thus screened for the presence of six genes and one specific region, all of which were previously found to show variable presence among Salmonella serotype 4,5,12:i:- and Typhimurium strains. All Salmonella serotype 4,5,12:i:- isolates lacked the phase 2 flagella genes fljA and fljB, which were present in all Salmonella serotype Typhimurium isolates. While all Spanish Salmonella serotype 4,5,12:i:- isolates carried the same deletion surrounding fljAB, all but two U.S. isolates showed a different genomic deletion; the two atypical U.S. isolates represented the "Spanish" deletion genotype and a unique deletion genotype. Salmonella serotype 4,5,12:i:- thus appears to represent at least two common clones, which cannot easily be differentiated with standard diagnostic procedures.

The duration of fecal Salmonella shedding following clinical disease among dairy cattle in the northeastern USA.

The objectives of this study were to determine the duration of fecal Salmonella shedding among dairy cattle in the northeastern United States following laboratory-confirmed clinical disease and to evaluate whether age group or serotype was associated with either shedding period or mortality. Study farms included 22 dairy herds that had at least two previous salmonellosis cases confirmed by fecal culture. Veterinarians continued to submit culture samples from clinical suspects following herd enrollment, and fecal samples from positive cattle were collected monthly until three sequential negative results were obtained or until loss to follow-up. There were 357 culture-positive clinical cases that each involved a single serotype during the shedding period. The Kaplan-Meier median duration of fecal Salmonella shedding was 50 days, and the maximum was 391 days. S. Newport was the predominant serotype, accounting for 51% of the cases. Age group and serotype were not significant predictors of Salmonella shedding duration in a Cox proportional hazards model, when stratifying by herd. However, the proportion of adult cows shedding for at least two consecutive monthly samples was significantly greater than the proportion of female calves shedding for this duration (Fisher's exact test p-value<0.01). Age group was also associated with mortality in this study; calves with salmonellosis were more likely to die than cows as estimated by a logistic regression model which controlled for herd as a random effect (p-value=0.04).

Recovery dynamics of skeletal muscle oxygen uptake during the exercise off-transient.

UNLABELLED: The time course of muscle .V(O2) recovery from contractions (i.e., muscle .V(O2) off-kinetics), measured directly at the site of O(2) exchange, i.e., in the microcirculation, is unknown. Whereas biochemical models based upon creatine kinase flux rates predict slower .V(O2) off- than on-transients [Kushmerick, M.J., 1998. Comp. Biochem. Physiol. B: Biochem. Mol. Biol.], whole muscle .V(O2) data [Krustrup, et al. J. Physiol.] suggest on-off symmetry. PURPOSE: We tested the hypothesis that the slowed recovery blood flow (Qm) kinetics profile in the spinotrapezius muscle [Ferreira et al., 2006. J. Physiol.] was associated with a slowed muscle .V(O2) recovery compared with that seen at the onset of contractions (time constant, tau approximately 23s, Behnke et al., 2002. Resp. Physiol.), i.e., on-off asymmetry. METHODS: Measurements of capillary red blood cell flux and microvascular pressure of O(2) (P(O2) mv) were combined to resolve the temporal profile of muscle .V(O2) across the moderate intensity contractions-to-rest transition. RESULTS: Muscle .V(O2) decreased from an end-contracting value of 7.7+/-0.2 ml/100 g/min to 1.7+/-0.1 ml/100g/min at the end of the 3 min recovery period, which was not different from pre-stimulation .V(O2). Contrary to our hypothesis, muscle .V(O2) in recovery began to decrease immediately (i.e., time delay <2s) and demonstrated rapid first-order kinetics (tau, 25.5+/-2.6s) not different (i.e., symmetrical to) to those during the on-transient. This resulted in a systematic increase in microvascular P(O2) during the recovery from contractions. CONCLUSIONS: The slowed Qm kinetics in recovery serves to elevate the Qm/.V(O2) ratio and thus microvascular P(O2) . Whether this Qm response is obligatory to the rapid muscle .V(O2) kinetics and hence speeds the repletion of high-energy phosphates by maximizing conductive and diffusive O(2) flux is an important question that awaits resolution.

The incidence of salmonellosis among dairy herds in the northeastern United States.

The objectives of this study were to estimate the incidence of salmonellosis among a large sample of dairy herds in the northeastern United States (both at the animal level and the herd level), to describe the serotypes and antimicrobial resistance profiles of the positive samples, and to determine whether various herd-level factors were important predictors of incidence. Participating veterinarians enrolled 831 dairy herds and submitted fecal samples from 2,565 female dairy cattle for Salmonella culture because of suspicion of clinical disease. Estimates of animal-level incidence rates were calculated for each age group as the number of cases per animal time at risk, and an estimate of herd-level incidence rate was calculated as the number of positive herds per herd time at risk. Descriptive analysis of serotype data and level of antimicrobial resistance was performed, and Poisson regression analysis was used to study associations between the within-herd incidence of salmonellosis and certain predictor variables (herd size, housing type, vaccination status, and prior history of Salmonella infection). Salmonella was isolated from 576 (22.5%) samples representing 93 herds. The animal-level incidence rates for preweaned female calves, heifers, and adult cows were 8.1, 0.04, and 1.8 cases per 1,000 animal-years, respectively. The herd-level incidence rate was 8.6 positive herds per 100 herd-years. Salmonella Newport was the predominant serotype, accounting for 41% of the cases, followed by Salmonella Typhimurium. Over 68% of all isolates were resistant to 5 or more antimicrobial agents. Herd size was the only significant predictor of the incidence of salmonellosis in a multivariable model; herds with at least 400 female dairy cattle had a higher incidence rate than smaller herds. Our results shed light on the impact of salmonellosis on the dairy industry in the northeastern United States, and they help clarify the role of dairy cattle as a source of Salmonella serotypes that are also important human pathogens.

The relationship of mucosal bacteria to duodenal histopathology, cytokine mRNA, and clinical disease activity in cats with inflammatory bowel disease.

Feline inflammatory bowel disease (IBD) is the term applied to a group of poorly understood enteropathies that are considered a consequence of uncontrolled intestinal inflammation in response to a combination of elusive environmental, enteric microbial, and immunoregulatory factors in genetically susceptible cats. The present study sought to examine the relationship of mucosal bacteria to intestinal inflammation and clinical disease activity in cats with inflammatory bowel disease. Duodenal biopsies were collected from 27 cats: 17 undergoing diagnostic investigation of signs of gastrointestinal disease, and 10 healthy controls. Subjective duodenal histopathology ranged from normal (10), through mild (6), moderate (8), and severe (3) IBD. The number and spatial distribution of mucosal bacteria was determined by fluorescence in situ hybridization with probes to 16S rDNA. Mucosal inflammation was evaluated by objective histopathology and cytokine profiles of duodenal biopsies. The number of mucosa-associated Enterobacteriaceae was higher in cats with signs of gastrointestinal disease than healthy cats (P<0.001). Total numbers of mucosal bacteria were strongly associated with changes in mucosal architecture (P<0.001) and the density of cellular infiltrates, particularly macrophages (P<0.002) and CD3(+)lymphocytes (P<0.05). The number of Enterobacteriaceae, E. coli, and Clostridium spp. correlated with abnormalities in mucosal architecture (principally atrophy and fusion), upregulation of cytokine mRNA (particularly IL-1, -8 and -12), and the number of clinical signs exhibited by the affected cats. These data establish that the density and composition of the mucosal flora is related to the presence and severity of intestinal inflammation in cats and suggest that mucosal bacteria are involved in the etiopathogenesis of feline IBD.

Multilocus sequence typing supports the hypothesis that cow- and human-associated Salmonella isolates represent distinct and overlapping populations.

A collection of 179 human and 156 bovine clinical Salmonella isolates obtained from across New York state over the course of 1 year was characterized using serotyping and a multilocus sequence typing (MLST) scheme based on the sequencing of three genes (fimA, manB, and mdh). The 335 isolates were differentiated into 52 serotypes and 72 sequence types (STs). Analyses of bovine isolates collected on different farms over time indicated that specific subtypes can persist over time on a given farm; in particular, a number of farms showed evidence for the persistence of a specific Salmonella enterica serotype Newport sequence type. Serotypes and STs were not randomly distributed among human and bovine isolates, and selected serotypes and STs were associated exclusively with either human or bovine sources. A number of common STs were geographically widespread. For example, ST6, which includes isolates representing serotype Typhimurium as well as the emerging serotype 4,5,12:i:-, was found among human and bovine isolates in a number of counties in New York state. Phylogenetic analyses supported the possibility that serotype 4,5,12:i:- is closely related to Salmonella serotype Typhimurium. Salmonella serotype Newport was found to represent two distinct evolutionary lineages that differ in their frequencies among human and bovine isolates. A number of Salmonella isolates carried two copies of manB (33 isolates) or showed small deletion events in fimA (nine isolates); these duplication and deletion events may provide mechanisms for the rapid diversification of Salmonella surface molecules. We conclude that the combined use of an economical three-gene MLST scheme and serotyping can provide considerable new insights into the evolution and transmission of Salmonella.

Association of Helicobacter with cholangiohepatitis in cats.

Infection with Helicobacter spp. is increasingly linked with hepatobiliary inflammation and neoplasia in people and in a variety of animals. We sought to determine if Helicobacter species infection is associated with cholangiohepatitis in cats. Deoxyribonucleic acid was extracted from tissue blocks from cats with cholangiohepatitis (32), noninflammatory liver disease (13), and cats with normal liver histology (4). Deoxyribonucleic acid was polymerase chain reaction-amplified with 2 sets of Helicobacter genus-specific primers, gel purified, and sequenced. Polymerase chain reaction-positive hepatic tissue was further examined with Steiner's stain, immunocytochemistry for Helicobacter species, and eubacterial fluorescent in situ hybridization. Gastric tissues of cats with known Helicobacter infection status served as controls for deoxyribonucleic acid extraction and sequence comparison. Helicobacter species were detected in 2/32 cats with cholangiohepatitis, and 1/17 controls. Sequences had 100% identity with Helicobacter species liver, Helicobacter pylori, and Helicobacter fenelliae/cinaedii in a cat with suppurative cholangitis, Helicobacter species liver, Helicobacter pylori, and Helicobacter nemistrineae in a cat with mild lymphocytic portal hepatitis, and Helicobacter bilis in a cat with portosystemic vascular anomaly. In contrast, sequences from gastric biopsies showed highest homology (99-100%) to "Helicobacter heilmannii," Helicobacter bizzozeronii, Helicobacter felis, and Helicobacter salomonis. Fluorescent in situ hybridization revealed a semicurved bacterium, with Helicobacter-like morphology, in an intrahepatic bile duct of the cat with suppurative cholangitis. This study has identified Helicobacter deoxyribonucleic acid in 2/32 cats with cholangiohepatitis and 1/13 cats with noninflammatory liver disease. Deoxyribonucleic acid sequences of hepatic Helicobacter species were distinct from those found in the stomach and are broadly consistent with those identified in cat intestine and bile, and hepatobiliary disease in people and rodents.

Healthcare use before and after a workplace injury in British Columbia, Canada.

OBJECTIVES: There is growing evidence that occupational injuries influence workers' emotional and physical wellbeing, extending healthcare use beyond what is covered by the Workers' Compensation Board (WCB). METHODS: The authors used an administrative database that links individual publicly funded healthcare and WCB data for the population of British Columbia (BC), Canada. They examined change in service use, relative to one year before the injury, for workers who required time off for their injuries (lost time = LT) and compared them to other injured workers (no lost time = NLT) and individuals in the population who were not injured (non-injured = NI). RESULTS: LT workers increased physician visits (22%), hospital days (50%), and mental healthcare use (43% physician visits; and 70% hospital days) five years after the injury, relative to the year before the injury, at a higher rate than the NI group. For the NLT workers, the level of increased use following the injury was between that of these two groups. These patterns persisted when adjusting for registration in the BC Medical Service Plan (MSP) and several workplace characteristics. CONCLUSIONS: Although the WCB system is the primary mechanism for processing claims and providing information about workplace injury, it is clear that the consequences of workplace injury extend beyond what is covered by the WCB into the publicly funded healthcare system.

Retrospective study of predictive variables for maximal heart rate (HRmax) in horses undergoing strenuous treadmill exercise.

REASONS FOR PERFORMING STUDY: Heart rate is one of the most commonly measured variables in equine exercise physiology and relative exercise intensity commonly expressed as % of maximal heart rate. A number of influences affect maximal heart rate (HRmax), including age of the horse but other factors have not been described. OBJECTIVES: To determine if fitness, health status, gender, breed, athletic use, body mass, in addition to age, are predictive of HRmax in the horse. METHODS: Maximal heart rate data from 328 horses which underwent treadmill exercise tests at 5 different laboratories were obtained retrospectively. Univariable linear regression analyses were performed on individual variables. Multiple linear regression analysis using a backward elimination modelling procedure was then used to relate the observed HRmax values simultaneously with different predictive variables. Variables were retained in the final regression model if they or any of their categories were significantly predictive of HRmax at P<0.05 and if there was a significant collective contribution to the model from inclusion of each variable, also at P<0.05. RESULTS: Age, fitness status, laboratory, gender and breed/use (combined category) were all statistically significantly predictive of HRmax. Together these variables accounted for 41% of the variance in HRmax. Age alone accounted for only approximately 13% of the variation between horses in HRmax. Neither body mass nor health status were significantly predictive. CONCLUSIONS: HRmax in the horse declines with age but is also influenced by other factors. As the factors investigated accounted for only 41% of the variation between horses, other unidentified variables with a strong influence on HRmax remain to be identified. POTENTIAL RELEVANCE: Factors such as fitness, age, gender, breed and use need to be considered when interpreting estimates or measurements of HRmax.

Effects of a specific endothelin-1A antagonist on exercise-induced pulmonary haemorrhage (EIPH) in thoroughbred horses.

REASONS FOR PERFORMING STUDY: During high intensity exercise, the very high pulmonary artery pressure (Ppa) experienced by Thoroughbred horses is considered a major factor in the aetiology of exercise-induced pulmonary haemorrhage (EIPH). Recently, endothelin-1 (ET-1), a potent vasoconstrictive hormone, has been found to increase Ppa in horses at rest via binding to its ET-1A receptor subtype. In addition, plasma concentrations of ET-1 are increased in horses during and after high intensity exercise. HYPOTHESIS: If ET-1 increases Ppa during exercise in the horse, administration of a specific ET-1A antagonist would decrease Ppa and therefore EIPH. METHODS: Saline (CON) or an ET-1A receptor antagonist, TBC3214 (3 mg/kg bwt i.v.; ANTAG) was administered to horses 1 h prior to maximal incremental exercise on a high-speed treadmill. Gas exchange measurements were made breath-by-breath and blood samples collected during each 1 min stage to determine blood gases, acid-base status and cardiac output. EIPH was determined via bronchoalveolar lavage (BAL) approximately 30 min after exercise. RESULTS: The time to fatigue, gas exchange and cardiovascular responses were not different between groups (P>0.05). Resting and peak Ppa did not differ significantly between treatments. Most importantly, ANTAG did not decrease EIPH. CONCLUSIONS: These results do not support a deterministic role for ET-1 in the increased Ppa and therefore EIPH, during maximal exercise in the equine athlete. POTENTIAL RELEVANCE: Treatment with an ET-1A receptor antagonist does not appear to be a viable therapeutic intervention in the prevention of EIPH.

Exercise-induced pulmonary haemorrhage during submaximal exercise.

REASONS FOR PERFORMING STUDY: Maximally exercising horses achieve mean pulmonary artery pressures (Ppa(mean)) that exceed the minimum threshold (75 mmHg) estimated for pulmonary capillary rupture and exercise-induced pulmonary haemorrhage (EIPH). EIPH is not expected to occur during moderate submaximal exercise (i.e. 40-60% VO2max) since Ppa(mean) remains well below this threshold. HYPOTHESIS: Prolonged submaximal exercise (trotting) would precipitate locomotory respiratory uncoupling and cause EIPH. This would be present as a result of the most negative intrapleural pressures (as estimated by the minimum oesophageal pressure; Poes(min)) occurring simultaneously with the most positive Ppa (Ppa(peak)) to produce estimated maximal pulmonary artery transmural pressures (PATMPmax) that surpass the EIPH threshold. METHODS: Five Thoroughbred horses trotted to fatigue (approximately 25 min) at 5 m/sec on a 10% incline. Ventilation (V(E)), Poes, and Ppa were measured at 5 min intervals, and bronchoalveolar lavage (BAL) red blood cells (RBCs) were quantified 45 min post exercise. RESULTS: BAL revealed an increased EIPH (rest: 2.0 +/- 1 x 10(5), exercise: 17 +/- 10 x 10(5) RBCs/ml BALF; P<0.05), despite the highest Ppamean reaching only mean +/- s.e. 55 +/- 3 mmHg, while V(E), tidal volume and Poes(min) approached 70-80% of the values achieved at maximal running speeds (10% incline: 12-13 m/sec) by these same horses. The resulting PATMPmax was well above the level considered causative of EIPH. CONCLUSIONS: The finding of significant EIPH during submaximal exercise broadens the spectrum of performance horses susceptible to EIPH and supports studies that suggest that extravascular factors are of primary importance in the aetiology of EIPH. POTENTIAL RELEVANCE: Consideration of strategies such as the equine nasal strip for reducing negative extravascular pressures is warranted even for exercise at moderate intensities.

Ceftiofur-resistant Salmonella strains isolated from dairy farms represent multiple widely distributed subtypes that evolved by independent horizontal gene transfer.

Salmonella is the leading cause of known food-borne bacterial infections in the United States, with an incidence rate of approximately 15 cases per 100,000 people. The rise of antimicrobial-resistant Salmonella subtypes, including the appearance of subtypes resistant to ceftriaxone, represents a particular concern. Ceftriaxone is used to treat invasive cases of Salmonella in children and is closely related to ceftiofur, an antibiotic commonly used to treat diseases of cattle. In order to develop a better understanding of the evolution and transmission of ceftiofur resistance in Salmonella, we characterized ceftiofur-resistant and -sensitive Salmonella isolates from seven New York dairy farms. A total of 39 isolates from these seven farms were analyzed for evolutionary relatedness (by DNA sequencing of the Salmonella genes fimA, manB, and mdh), antibiotic resistance profiles, and the presence of bla(CMY-2), a beta-lactamase gene associated with resistance to cephalosporins. Our data indicate that (i) resistance to ceftriaxone and ceftiofur was highly correlated with the presence of bla(CMY-2); (ii) ceftiofur-resistant Salmonella strains were geographically widespread, as shown by their isolation from farms located throughout New York State; (iii) ceftiofur-resistant Salmonella strains isolated from farms represent multiple distinct subtypes and evolutionary lineages, as determined by serotyping, DNA sequence typing, and antimicrobial-resistance profiles; and (iv) ceftiofur-resistant Salmonella strains evolved by multiple independent acquisitions of an identical bla(CMY-2) allele and by clonal spread of ceftiofur-resistant subtypes.