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Biomedical subjects

C S Rhodes

Publications and source records attributed to C S Rhodes.

17 recordsLinked to original sources
PubMed2000

Evaluation of site and age of weaning on pig growth performance.

Site-segregated early weaning (SSEW) refers to the practice of weaning pigs from the sow at an early age and placing them in a nursery that is physically isolated from the breeding herd. An experiment involving 369 pigs was conducted at the Prairie Swine Center to investigate the impact of SSEW on pig performance when the herd of origin has a high health status and when housing and management conditions are kept as similar as possible across weaning regime. Three treatments were compared: weaning at 21+/-3 d and keeping the pigs on-site in an all-in-all-out nursery room (Control), weaning at 12+/-2 d of age and keeping the pigs on-site in a separate but identical all-in-all-out nursery room (OSEW), or weaning at 12+/-2 d of age and moving the pigs off-site to an all-in-all-out nursery room located 16 km from the Center (SSEW). Ventilation, feed, penning, feeders, and drinkers were kept as similar as possible for all treatments. Off-site weaning improved 56-d body weight (P < .05) by 12.5 and 8.3% compared with OSEW and Control, respectively. The improvement appeared to be the result of improvements primarily in feed intake but also due to enhanced efficiency of nutrient utilization. This experiment confirms that SSEW results in significant improvements in 56-d weights, even when the herd of origin has a relatively high health status.

Aging↗
PubMed1997

Positive human health effects of dust suppression with canola oil in swine barns.

A crossover trial was conducted to evaluate the acute human health effects of a dust control technology in a swine confinement facility. Twenty lifetime nonsmoking male subjects, with no evidence of allergy or asthma and no previous swine barn exposure, participated in the study, which included a laboratory session (baseline), 5-h exposure in a swine room sprinkled with canola oil (treatment) and 5-h exposure in a traditional swine room (control). Mean values of inhalable dust concentrations and endotoxin levels in the control room were significantly greater than those observed in the treatment room. Mean shift changes in FEV1 from preexposure to end of exposure were 1.1% (standard error, 0.63%) on baseline day, -1.9% (0.63%) on treatment day, and -9.9% (1.12%) on control day; the differences in the shift changes were statistically significant. Mean value of methacholine concentration that reduced the FEV1 by 20% (PC20) in bronchoprovocation tests on baseline day was significantly different from that on treatment day (p = 0.04) and that on control day (p < 0.001). Significant increases were also observed in white blood cell counts and nasal lavage cell counts on the control day in comparison with the other two days. Blood neutrophil counts after control room exposure were twice those observed on baseline and after exposure to the treatment room. Significant differences were also observed in IL-1 beta, IL-6, and IL-8 nasal lavage cytokines and in IL-6 serum cytokine. These results suggest that the canola oil dust control method is effective in improving indoor air quality in swine barns and reducing acute health effects in naive healthy subjects.

Adolescent↗
PubMed1997

Accelerated lung function decline in swine confinement workers.

We conducted a longitudinal study to determine the annual rate decline in pulmonary function measurements in male swine confinement workers. For comparison, a grain farming group and a nonfarming rural-dwelling control group were also chosen for the longitudinal study. Two hundred seventeen swine confinement workers, 218 grain farmers, and 179 nonfarming control subjects had valid pulmonary function measurements at the baseline observation conducted in 1990 to 1991 and at the second observation conducted in 1994 to 1995. The swine confinement workers were younger (mean age=38.3+/-11.7 [SD] years) than the nonfarming control subjects (42.6+/-10.4 years) and the grain farmers (44.5+/-11.9 years). When stratified by age, nonfarming control subjects had the lowest mean annual rate decline in FEV1 and FVC in all age categories. The swine confinement workers had the largest annual rate decline in FEV1 and FVC, and this was most obvious in the middle age categories. After controlling for age, height, smoking, and baseline pulmonary function, swine confinement workers had excess annual decline of 26.1 mL in FEV1 (p=0.0005), 33.5 mL in FVC (p=0.0002), and 42.0 mL/s in forced expiratory flow between 25% and 75% of FVC (FEF[25-75%]) (p=0.02) over nonfarming control subjects. Grain farmers had excess annual decline of 16.4 mL in FEV1 (p=0.03), 26.7 mL in FVC (p=0.002), and 11.2 mL/s in FEF(25-75%) (p=0.38) over control subjects. These findings suggest that workers engaged in the swine industry and grain farmers appear prone to accelerated yearly losses in lung function and may therefore be at risk for the future development of chronic airflow limitation.

Adult↗
PubMed1996

Identification of a minimum enhancer sequence for the type II collagen gene reveals several core sequence motifs in common with the link protein gene.

The type II collagen gene (Col2a1) is expressed primarily in chondrocytes. Transcription of Col2a1 is mediated by cell-specific regulatory elements located within the promoter and first intron. Here, we map a minimal enhancer and identify elements that determine cartilage-specific Col2a1 expression by analyzing the activity of a series of chimeric genes consisting of rat Col2a1 first intron deletion mutants ligated to the chloramphenicol acetyltransferase reporter gene. We show that a 100-base pair (bp) segment within the first intron is the minimum size necessary for high level, cell type-specific expression of Col2a1. Sequence analysis of this 100-bp Col2a1 enhancer revealed several sequence motifs similar to motifs present within the regulatory region of the link protein gene, another cartilage gene. These motifs include an AT-rich element, a C1 motif and a C3 motif. Deletion of any of these elements reduced Col2a1 enhancer activity in chick embryo chondrocytes. We also tested enhancer-mediated activity in CFK2 cells which differentiate to a chondrogenic phenotype and begin to express type II collagen mRNA after extended culture. In stably transfected CFK2 cells, constructs containing the 100-bp enhancer were activated during the transition from prechondrogenic to chondrogenic cell populations and deletions within the enhancer strongly down-regulated activity. Chondrocyte-specific DNA-protein complexes were identified using nuclear extracts prepared from chick embryo chondrocytes and 32P-labeled oligonucleotides from these regions of the first intron. These results suggest that interaction of chondrocyte specific nuclear factors with multiple core elements from a small region within the first intron are important for cell-type specific Col2a1 enhancer activity.

Animals↗
PubMed1993

Respiratory health of swine producers. Focus on young workers.

In this report, we compare the respiratory health of swine producers, grain farmers, and nonfarming control subjects, separately in all age groups and in young subjects. We examined 249 swine producers (age 37.7 years), 251 grain farmers (age 44.7 years), and 263 nonfarming subjects (age 40.7 years). Swine producers had significantly more symptoms of chronic bronchitis (15.3 percent) than did grain farmers (7.2 percent) or nonfarming men (5.7 percent). After controlling for age, height, and smoking, the functional indices of airflow (FEV1, FEV1/FVC, FEF25-75, Vmax50, and Vmax25) were slightly but significantly lower in swine producers than in grain farmers. In comparison with nonfarming subjects, swine producers also had significantly lower FEV1/FVC, FEF25-75, and Vmax50. Respiratory symptoms were associated with the number of hours of work per day. This indirect index of exposure was also inversely associated with FVC (p < 0.01) and FEV1 (p = 0.06), after adjustment for age, height, smoking, and dust mask usage. A relative excess of respiratory symptoms and lower lung function variables were found in swine producers aged 26 to 35 years. Also in this age group, a multivariate analysis revealed statistically significant effects of daily duration of work on FVC and FEV1. The results confirm that working in swine confinement units is a risk factor for chronic respiratory symptoms and minor lung function changes. An increased risk in young workers may reflect more intense occupational exposure in this subgroup of swine producers.

Adult↗
PubMed1983

Posterior paralysis due to fibrocartilaginous embolism in two weaner pigs.

Acute posterior paralysis in two weaner pigs was attributed to ischemic infarction of the lumbar spinal cord due to fibrocartilaginous emboli. These arterial and venous emboli were assumed to have originated from the nucleus pulposus of one or more intervertebral discs. There was no indication of an initiating factor in either instance, although some form of trauma may have been involved. Lesions were not grossly evident and were limited to one or two lumbar segments. Although it appears to be a rare occurrence, fibrocartilaginous embolism of the spinal cord should be considered in cases of acute paralysis in pigs particularly when gross lesions are absent.

Age Factors↗
PubMed1982

Construction of a genetic map for Caulobacter crescentus.

RP4-mediated conjugation has been used to transfer large fragments of chromosomal material in Caulobacter crescentus. In this system, conjugation proceeds from multiple origins, and haploid recombinants are recovered at frequencies of 10(-6) and 10(-7) per donor cell. The data from five-factor crosses were subjected to computer-assisted crossover analyses as a rapid method to determine marker order. Using this information and data from additional two- and three-factor crosses mediated by RP4 or the generalized transducing bacteriophage phi Cr30, we constructed the first genetic map for C. crescentus.

Bacteria↗
PubMedDate not supplied

Depletion of penicillin G residues in tissues, plasma and injection sites of market pigs injected intramuscularly with procaine penicillin G.

Procaine penicillin G was administered by intramuscular (i.m.) injection to groups of healthy 100 kg market pigs at the approved label dose (15,000 IU/kg body weight), once daily for three consecutive days; or an extra-label dose (66,000 IU/kg body weight), once daily for five consecutive days. Penicillin G residue depletion was followed in plasma, tissue and injection sites using a liquid chromatographic method. Groups of pigs were killed 1, 2, 3, 4, 5 and 8 days after the last injection with the label dose. Penicillin G was not detected in liver after 1 day of withdrawal, in muscle and fat after 2 days of withdrawal, in plasma after 4 days of withdrawal, in skin after 5 days of withdrawal, or in kidney and the injection sites after 8 days of withdrawal. Other groups of pigs were killed 1, 2, 3, 5 and 7 days after injection with the extra-label dose. In these pigs penicillin G was not found in liver after 2 days of withdrawal, in fat after 3 days of withdrawal, or in the muscle, skin, plasma and injection sites after 7 days of withdrawal. Penicillin G was found at all times in the kidneys of the groups of pigs that received the high dose. The technique used for neck injections was critical to obtain intramuscular rather than intermuscular injections. The Bureau of Veterinary Drugs, Health Protection Branch, Health Canada calculated that the appropriate withdrawal period for pigs was 8 days for a dose of 15,000 IU procaine penicillin G/kg body weight and 15 days for a dose of 66,000 IU/kg.

Adipose Tissue↗
PubMedDate not supplied

Predictors of longitudinal changes in pulmonary function among swine confinement workers.

OBJECTIVE: To determine predictors of longitudinal changes in pulmonary function in swine confinement workers. DESIGN: Longitudinal study conducted from November 1989 to June 1991 and January 1994 to May 1995. SETTING: Swine confinement workers in Saskatchewan. PARTICIPANTS: Forty-two swine confinement workers who were studied in 1989/90 and studied again in 1994/95. RESULTS: Of 98 male swine confinement workers (mean age SD 36.3 11.1 years) studied at baseline, 42 were studied again five years following. Complete information on baseline across-shift pulmonary function (preshift forced expiratory volume in 1 s [FEV1], forced vital capacity [FVC], and every 2 h FEV1 and FVC during the shift), and five-year follow-up pulmonary function (with FEV1 and FVC) were available on all 42 subjects. Mean across-shift changes (preshift measurement to last measurement of the day) at baseline were -159. 8 61.7 mL in FEV1 and -35.3 65.6 mL in FVC. Mean annual rate change between baseline and follow-up for FEV1 was -53.9 61.7 mL/year and for FVC -48.9 71.6 mL/year. After adjusting for age, height, smoking and hours spent in the barn, the baseline across-shift change in FEV1 and FVC was a significant predictor of annual rate change in FEV1 (P=0.01) and FVC (P=0.02), respectively. To determine the effects of indoor air quality on longitudinal lung function decline, indoor air environmental measurements were analysed. Complete information on respiratory health and indoor air quality was available on 34 of the 42 subjects. Assessment of indoor environment of swine barns included a summer and winter measurement for airborne dust, gases and endotoxin levels. After adjusting for age, height, smoking, ammonia and hours spent in the barn, the endotoxin level (Eu/mg)was a significant predictor of annual rate change for FEV1 but not FVC. CONCLUSIONS: These results suggest that shift change is an important predictor of longitudinal changes in lung function in swine confinement workers and that endotoxin exposures may mediate annual decline in FEV1 in these workers.

Adolescent↗