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Biomedical subjects

J W Lloyd

Publications and source records attributed to J W Lloyd.

At least 37 records · Page 2Linked to original sources
PubMed1998

Influence of exogenous hyaluronan on synthesis of hyaluronan and collagenase by equine synoviocytes.

OBJECTIVE: To evaluate the influence of exogenous hyaluronan (HA) on in vitro synthesis of HA and collagenase by equine synoviocytes from normal and inflamed joints. ANIMALS: 9 adult horses. PROCEDURE: Synoviocytes for culture were taken from the middle carpal joint of 3 horses with normal joints (control) and 6 horses with osteochondral fractures (principal). Synoviocytes were propagated in monolayer cultures and were incubated with 3 commercial HA products at concentrations of 0, 200, 400, and 1,500 micrograms/ml. Newly synthesized HA was radiolabeled with [3H]glucosamine and quantified by cetylpyridinium chloride precipitation and liquid scintillation counting. The hydrodynamic size of radioactive HA was determined by high-performance liquid chromatography, and collagenase activity was evaluated by use of a quantitative radioactive collagen film assay. RESULTS: Exogenous HA influenced neither the rate of synthesis nor the hydrodynamic size of the newly produced HA by control or principal cell cultures. Culture supernatants from abnormal synovium, exposed to 400 and 1,500 micrograms of exogenous HA/ml, contained significantly more collagenase activity than did those exposed to lower concentrations. CONCLUSION: Although HA is thought to have beneficial effects in equine arthropathies, the principal mechanisms of action of HA do not appear to be stimulation of synthesis of HA of augmented molecular weight or marked inhibition of collagenase synthesis.

Animals↗
PubMed1997

Evaluation of a practice-based ambulatory program in food animal medicine, surgery, and herd health management.

OBJECTIVE: To assess the educational value of a practice-based ambulatory program used at a school of veterinary medicine. DESIGN: Retrospective cohort study. SAMPLE POPULATION: Graduates of US veterinary medical schools between 1987 and 1994. PROCEDURE: Phase I involved use of interviews and focus groups to assist in development of the questionnaire used in phase II, a retrospective cohort study. The pretested questionnaire was sent to a study population consisting of all graduates of the University of Wisconsin-Madison, School of Veterinary Medicine, between 1987 and 1994 as well as a control group who were randomly selected from the 1994 AVMA list of veterinarians. Control-group veterinarians were matched on the basis of professional activity, region, and year of graduation. RESULTS: 728 of 1,067 veterinarians completed the questionnaire in phase II of the study (response rate, 68%). The practice-based ambulatory program at the University of Wisconsin-Madison compared favorably with university-based ambulatory programs in volume of experiences and perceived educational quality. Regardless of rotation type, female students were significantly less likely to observe or perform 12 specific clinical procedures and were significantly less likely to rate instructional quality as excellent or very good, compared with male students. CLINICAL IMPLICATIONS: Practice-based ambulatory rotations can be a good alternative to existing university-based ambulatory rotations. Implementation of these programs should emphasize performance of procedures while striving to ensure participation of female students.

Animal Husbandry↗
PubMed1997

Comparison of racing performance before and after treatment of incomplete, midsagittal fractures of the proximal phalanx in standardbreds: 49 cases (1986-1992)

OBJECTIVE: To assess the effect of incomplete, midsagittal fractures of the proximal phalanx (P1) on racing performance in Standardbreds. DESIGN: Retrospective cohort study. ANIMALS: 49 Standardbred horses admitted to the George D. Widener Hospital for Large Animals between July 1986 and December 1992 with a definitive radiographic diagnosis of an incomplete, midsagittal fracture of P1 and a known method of treatment. PROCEDURE: Performance index and racing time were compared before and after diagnosis and treatment of fracture, using ANOVA that controlled for the effects of horse, gender, age, track length, and track condition. RESULTS: Expected racing time increased by 0.7 seconds and performance index decreased by 0.7 points, although controlling for factors known to affect racing performance had a substantial impact on these results. CLINICAL IMPLICATIONS: Standardbreds with incomplete, midsagittal fractures of P1 have a favorable prognosis for return to racing; recovered horses will likely have slower racing times and decreased performance indices.

Animals↗
PubMed1997

Economics of health management in the Michigan, USA equine industry.

A study was developed to describe direct expenses, labor use, and performance days lost associated with health management in the Michigan equine industry. A prospective design with stratified, random sampling, was employed involving 77 operations from February 1992 through January 1993, and 61 different operations from May 1993 through April 1994. Data on the cost of health management were collected during monthly visits, and included monetary expenditures, death losses, days lost, and labor use. Median health care costs (when they were incurred) were $4.84 per horse per month for monetary expenditures plus death losses, 0.20 hours per horse per month for labor use, and 0.81 performance days lost per horse per month for therapy and prevention of all diseases combined. There were large variations both within and between specific disease groups, operation-size strata, and months. General linear models indicated that health-management costs (when incurred) were significantly higher (per horse per month) on smaller operations. The only disease group that showed a significant difference between months was respiratory disease. However, these differences did not appear to demonstrate a definitive seasonal pattern. Monetary expenditures and labor use for management of lameness tended to be lower on operations with more riding and showing activities. Also, monetary expenditures to manage lameness tended to be lower on operations with a higher proportion of conditioning activity. Our results are consistent with other studies, and implications for management and future research are discussed.

Animals↗
PubMed1997

Relationship between body condition scores and milk yield in a large dairy herd of high yielding Holstein cows.

This study investigated the relationship between body condition and milk yield of dairy cows. Holstein cows (n = 779) on a commercial dairy farm were scored for body condition weekly beginning at dry-off and continuing until 120 d of lactation. Multiple linear regression and principal component analysis were used to characterize relationships. Mean body condition scores were 2.77 and 2.66 at dry-off and parturition, respectively. Principal component analysis was used to reduce the collinearity among independent variables, to calculate new parameter estimates, and to rank the relationship of each variable with milk yield. Results indicated that change in body condition during the dry period was ranked first, followed by lactation number, and then body condition score at dry-off for multiparous cows. A one-point increase in body condition score between dry-off and parturition was associated with 545.5 kg more milk in the first 120 d of lactation. Each additional point of body condition at dry-off was associated with 300 kg less milk at 120 d of lactation. Results suggested that cows that gained condition during the dry period yielded more milk in the first 120 d of lactation and had an accelerated rate of increase in milk yield. The results of this study indicate that body condition score is an important tool for monitoring dairy herds.

Adipose Tissue↗
PubMed1997

Relationship between body condition scores and conception at first artificial insemination in a large dairy herd of high yielding Holstein cows.

This study investigated the relationship between changes in body condition during the dry period and early lactation and conception to first postpartum AI. Holstein cows (n = 720) on a commercial dairy farm were scored weekly for body condition beginning at dry-off and continuing until first AI. Occurrence of postpartum diseases was recorded. A multiple logistic regression model was a significant predictor of the success or failure of conception for multiparous cows, but not for primiparous cows. Principal component analysis reduced collinearity among independent variables and allowed the variables to be ranked based on their contribution to the interval from first AI to conception. The top three ranking variables were lactation number, milk yield at 120 d of lactation, and change in body condition score between parturition and wk 4 of lactation. Increased milk yield at 120 d of lactation was associated with an increased likelihood of conception, and decreased body condition during the 1st mo of lactation was associated with a decreased likelihood of conception. Health problems were less associated with conception than were body condition or milk yield in this herd. Body condition during the dry period and during the first 30 d of lactation is an important tool to identify cows at risk for failure to conceive at first AI.

Adipose Tissue↗
PubMed1997

Effects of diet and bovine somatotropin on heifer growth and mammary development.

Forty Holstein heifers [body weight (BW) = 126 kg] were blocked by BW into groups of 4, and, within each block, heifers were randomly assigned to one of four treatments. Twenty heifers had ad libitum access to a diet formulated to produce a BW gain of 0.8 kg/d (control diet), and 20 heifers had ad libitum access to a diet formulated to produce a BW gain of 1.2 kg/d. (high diet). Half of the heifers fed each diet were injected daily with bovine somatotropin (bST; 25 micrograms/ kg of BW). The high diet increased daily BW gain as well as body condition score. Injection of bST also increased daily BW gain, but did not affect body condition score. The high diet reduced age at puberty by 58 d, but did not affect BW, withers height at puberty, or pelvic area at slaughter. Injection of bST had no effect on age at puberty, but increased BW, withers height at puberty, and pelvic area at slaughter. The high diet did not affect mammary parenchymal DNA, RNA, or the ratio of RNA to DNA. The injection of bST increased mammary parenchymal DNA, RNA, and the ratio of RNA to DNA. The high diet was more cost effective for rearing dairy heifers from 120 d of age to potential breeding size (> or = 363 kg of BW and postpubertal) than was the control diet. In conclusion, the high protein, high energy diet increased growth rate without detrimental effects on mammary development. Injection of bST increased BW, skeletal size, and mammary development.

Animals↗
PubMed1997

Effects of a 6-week strength and proprioception training program on measures of dynamic balance: a single-case design.

OBJECTIVE: To examine the effects of a 6-week strength and proprioception training program on clinical measures of balance, and to introduce characteristics of a single-case research design that may be beneficial to the athletic training profession as both a research and a clinical tool. DESIGN AND SETTING: A multiple baseline design across subjects was used to assess the effects of the intervention. The training program was performed three times a week and consisted of manual muscle strengthening and proprioception training for the plantar flexor, dorsiflexor, inversion, and eversion muscle groups. SUBJECTS: Three subjects (age = 17.6 +/- 1.24 yr, wt = 78.6 +/- 1.07 kg, ht = 186.2 +/- 4.3 cm) who had previously sustained first-degree lateral ankle sprains. MEASUREMENTS: Dynamic balance was tested three times a week using a single-plane balance board (SPBB). Each subject was tested for two double-leg conditions (forward/backward, right/left) and one single-leg condition (forward/backward) for each extremity. The dependent variable was the number of times that the balance board made contact with the floor. Visual inspection was used to evaluate whether the treatment resulted in a change of performance. RESULTS: Although the intervention did not produce obvious improvements in balance for all evaluation criteria for all testing conditions, it is apparent that the strength and proprioception training program positively influenced all three subjects' ability to balance dynamically on an SPBB. A change in mean scores from baseline to intervention phase was evident for all testing conditions. However, a change in slope and level was not as apparent for all testing conditions, especially the single-leg conditions. CONCLUSION: The results revealed that the strength and proprioception training program produced improvements in the ability to balance as assessed dynamically on an SPBB.

Journal Article↗
PubMed1997

Multi-element assay of mammary secretions and sera from periparturient mares by inductively coupled argon plasma emission spectroscopy.

OBJECTIVE: To document and determine changes in the mineral profiles of sera and mammary secretions from a population of periparturient mares. ANIMALS: 18 clinically normal periparturient Arabian broodmares. PROCEDURE: Inductively coupled argon emission spectroscopy was used to measure Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn concentrations in sera and mammary secretions of periparturient mares. In addition, S was measured in mammary secretions. RESULTS: Serum concentrations of Ca, Cu, Fe, K, Mg, Na, P, and Zn remained constant throughout late pregnancy and the first 7 days of lactation. Compared with values on day 11 before foaling, mammary fluid concentrations of Ca, Cu, K, Mg, P, S, and Zn increased prior to parturition and all element concentrations, except Ca, decreased with the onset of lactation. In contrast, Na concentrations in mammary secretions decreased precipitously as parturition approached. Iron concentrations in mammary secretions remained relatively constant up to the time of parturition, decreased at parturition, and remained constant during lactation. CONCLUSIONS AND CLINICAL RELEVANCE: Prior to foaling, increasing concentrations of Ca, Cu, K, Mg, P, S, or Zn in mammary secretions in concert with precipitous decreases in Na concentrations may provide a predictive index of impending parturition in the mare and a means of assessing fetal readiness for birth.

Animals↗
PubMed1996

Patterns of chemical residues detected in US beef carcasses between 1991 and 1993.

A study of data from 12 states in the Food Safety Inspection Service's Residue Violation Information System was conducted to describe patterns of violative chemical residues in US beef during 1991, 1992, and 1993. In 1991, 3,249 violative residues were found in 2,734 carcasses in the 12 states included in the study. In 1992, 3,132 violative residues were found in 2,813 carcasses, and in 1993, 2,317 violative residues were found in 2,051 carcasses. During each of the 3 years, the Calf Antibiotic and Sulfonamide Test and Swab Test On Premises projects detected most of the violative residues, and producers/independent growers and dairy farms were recorded as the responsible sources for most of the violations. Also, most of the animals found to have violative residues were bob calves and culled cows. In bob calves, neomycin was the most frequently identified violative chemical, followed by tetracycline, gentamicin, oxytetracycline, and penicillin. In culled cows, penicillin was the most frequently identified violative chemical and was the chemical most frequently found in combination with other chemicals in cows with multiple violative residues. Distribution patterns of violative chemical residues by slaughter class and residue type varied among the 5 Food Safety Inspection Service regions. These specific regional characteristics support the need for customized intervention, education, assessment, and prevention programs.

Animals↗
PubMed1996

Use of a hand-held, metered-dose aerosol delivery device to administer pirbuterol acetate to horses with 'heaves'.

Aerosol administration of bronchodilators to horses is recommended for treatment of certain airway diseases such as 'heaves'. We have developed a novel, hand-held, metered-dose inhaler and we sought to determine the bronchodilator efficacy of the beta 2 adrenoceptor agonist pirbuterol delivered by this device to horses affected with 'heaves'. To induce airway obstruction, 6 heaves-susceptible horses were stabled, bedded on straw and fed hay. When the maximum change in pleural pressure during tidal breathing (delta Pplmax) was greater than 20 cmH2O on 2 consecutive days, pulmonary function was measured before and 5, 10 and 30 min, as well as 1, 2, 3, 4, 5, 6 and 7 h after administration of aerosol pirbuterol. Pirbuterol was administered using a metered canister and the hand-held delivery device that was inserted into the left nostril. Either vehicle or pirbuterol acetate (400, 600, 800, 1200 or 1600 micrograms) was administered to each horse. Relief of airway obstruction indicated by changes in pulmonary function was observed within 5 min after administration of both vehicle and pirbuterol. Significant decreases in delta Pplmax and pulmonary resistance (RL) and an increase in dynamic compliance (Cdyn) persisted for the 7 h duration of the experiment. Comparison of the effect of vehicle and pirbuterol at each time period showed that pirbuterol decreased RL and delta Pplmax significantly for up to 1 h. The optimal dose was determined to be 600 micrograms. Immediate response to treatment, magnitude of drug effect and lack of side effects indicated that aerosol pirbuterol is an effective and safe bronchodilator in horses with 'heaves'. The hand-held, metered-dose aerosol delivery device was very convenient and extremely effective and is, therefore, recommended for delivery of therapeutic aerosols to horses.

Administration, Inhalation↗
PubMed1996

Group versus individual reinforcement contingencies within the context of group study conditions.

We investigated the effects of two teaching variables on students' Spanish vocabulary quiz performance: (a) group study and (b) individual versus group contingencies. In Experiment 1, we compared students' quiz scores under conditions in which students either studied independently and received no programmed reinforcement or studied in groups and received individual rewards for high scores. The results showed that, on average, the group-study individual-reward condition produced superior quiz scores. In Experiment 2, we compared individual (i.e., the superior condition in Experiment 1) and group contingencies within the context of the group study condition. On average across the class, group contingencies produced performance superior to individual contingencies. In both studies, however, benefits for the classes as a whole were mitigated by effects on individual students. These results extend the literature on the effects of group-based instructional activities and reinforcement contingencies. Educators who choose such procedures may encounter conflicting findings depending on whether they examine results at the group or individual level.

Journal Article↗
PubMed1996

Efficacy of prosthetic laryngoplasty with and without bilateral ventriculocordectomy as treatments for laryngeal hemiplegia in horses.

OBJECTIVE: To evaluate the efficacy of prosthetic laryngoplasty with and without bilateral ventriculocordectomy for treatment of experimentally induced left laryngeal hemiplegia (LLH). ANIMALS: 15 adult Standardbreds. PROCEDURE: Horses were allotted to 3 equal groups. Sham operation (group 1), prosthetic laryngoplasty (group 2), or prosthetic laryngoplasty with bilateral ventriculocordectomy (group 3) was performed after induction of LLH. Upper airway function testing was performed prior to left recurrent laryngeal neurectomy (LRLN), 14 days after LRLN, and 60 and 180 days after surgical treatment. Measurements were obtained at rest and at treadmill speeds corresponding to 75 and 100% of maximal heart rate. Videoendoscopy was performed at rest and during exercise in all horses prior to LRLN and 60 and 180 days after surgical treatment. Upper airway endoscopy was performed immediately after LRLN to document induction of grade-IV LLH. Also, horses in group 3 were endoscopically examined at 7, 14, 21, 28, and 120 days after surgical treatment to evaluate healing of the ventriculocordectomy sites. RESULTS: When horses were at rest, significant differences were not apparent between groups at any period or between periods for any measured variable. LRLN induced airway obstruction in all horses during exercise. In sham-operated horses, this obstruction was unaffected by time. In contrast, 60 and 180 days after surgical treatment, inspiratory flow limitations induced by LRLN were reversed in horses of groups 2 and 3. There were no significant differences between the 2 treatment groups. Endoscopy revealed the left arytenoid cartilage abducted beyond the intermediate position, but not touching the pharyngeal wall in all horses with a laryngeal prosthesis. After surgical treatment, 4 group-2 horses had filling of both ventricles with air during exercise. There was moderate to marked swelling of the ventriculocordectomy sites immediately after surgery, and this swelling resolved by 7 days after surgery. The ventriculocordectomy sites looked best at 14 and 180 days. CONCLUSIONS: 60 and 180 days after prosthetic laryngoplasty, upper airway function returned to pre-LRLN values in horses with experimentally induced LLH exercising at 100% of maximal heart rate. Combining ventriculocordectomy with prosthetic laryngoplasty does not further improve upper airway function in these horses.

Animals↗
PubMed1995

Prevalence of cattle persistently infected with bovine viral diarrhea virus in 20 dairy herds in two counties in central Michigan and comparison of prevalence of antibody-positive cattle among herds with different infection and vaccination status.

All cattle in 20 dairy herds randomly selected from herds participating in the Dairy Herd Improvement Association program in 2 counties in central Michigan were tested for the presence of bovine viral diarrhea virus (BVDV). Virus-positive animals were retested to ascertain persistent infection with the virus. A total of 5,481 animals were tested for presence of BVDV. In 9 of the herds, all animals were also tested for virus neutralizing antibody titer. Based on infection and vaccination status, these 9 herds were divided into 3 different herd categories: A, 5 herds with currently no cattle persistently infected (PI) with BVDV and without any vaccination program against BVDV in recent years; B, 2 herds with no current PI cattle but using killed BVDV vaccines; and C, 2 herds with PI cattle. PI cattle were detected in 3 out of 20 herds (15%). A total of 7 of 5,481 animals (0.13%) were PI. The mean prevalences of antibody carriers in herd categories A, B, and C were 28.8%, 76.4% and 90.6%, respectively. For one herd in category A, antibody analyses indicated that mostly young stock was seropositive, suggested recent BVDV infection in a previously closed and naive herd. Cattle in category B herds were vaccinated with killed vaccine from the age of 15 months. These herds had several antibody negative animals among the younger cows, suggesting incomplete protection against BVDV infection. In the 3 herds in which PI animals were detected, all cattle had been vaccinated with killed vaccine. The antibody-positive animals had antibody titers that were significantly different both among herds and among herd categories.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1995

Application of antibody titers against bovine viral diarrhea virus (BVDV) as a measure to detect herds with cattle persistently infected with BVDV.

Based on the distribution of antibody titers against bovine viral diarrhea virus (BVDV) in 10 Michigan dairy herds, it was calculated that screening of 5 young stock for BVDV antibody titer could be used to distinguish herds with persistently infected (PI) animals from herds without such animals. The herds were selected to represent 3 different herd categories: A, herds without use of vaccination and without PI animals (5 herds); B, herds with use of killed vaccine but no PI animals (2 herds); C, herds with use of killed vaccine and presence of PI animals (3 herds). The animals were described as having high antibody titers (> or = 128) or low antibody titers (< or = 64). For animals from 9 to 18 months of age, the probability of obtaining at least 3 animals with high titers among a screening sample of 5 animals was calculated as < 0.001 for all herds in category A, < 0.01 for the 2 herds in category B, and > 0.99 for all herds in category C. Thus, among herds in this study, by categorizing 9-18-month-old animals as having high titers (> or = 128) or low titers (< or = 64), herds with PI cattle could be distinguished from other herds by testing only 5 animals.

Animals↗
PubMed1995

Validation of body condition scores with ultrasound measurements of subcutaneous fat of dairy cows.

This research validated body condition scores with ultrasound measurements of subcutaneous fat. Fifty Holstein cows were evaluated during three sessions in 1993. Cows scored during each session were divided into three groups of 15 or 20 cows. Body condition scores were assigned by one trained individual, utilizing a five-point (1 = thin to 5 = fat) visual scoring technique. Cows were scored to the nearest quarter point. Ultrasound measurements of subcutaneous fat were obtained by another individual at the lumbar, thurl, and tailhead areas of both sides of the cow. Body condition scores and ultrasound measurements were collected on the same day, but obtained independently. Correlations between ultrasound measurements ranged from .36 to .86. Regression models were developed to validate the body condition scoring technique across the three cow groups. Group number and different combinations of ultrasound measurements were independent variables, and body condition score was the dependent variable. Ultrasound measurements were significantly associated with body condition scores. The coefficients of determination for the models ranged from .36 to .65, depending on which ultrasound measurements were included in the model. These results suggest that the body condition scoring technique used in this study was as valid as ultrasound techniques for measurement of subcutaneous fat.

Adipose Tissue↗
PubMed1995

Comparison of the prevalence and incidence of infection with bovine virus diarrhoea virus (BVDV) in Denmark and Michigan and association with possible risk factors.

Based on 2 previous surveys on the occurrence of infection with bovine virus diarrhoea virus (BVDV) in Danish and Michigan dairy herds, the prevalence and incidence of the infection were compared. The presence of certain possible risk factors for the occurrence of infection in the 2 areas were summarized and it was investigated if any of these risk factors had significant effect on the presence of animals persistently infected (PI) with BVDV in the dairy herds. Information on the cattle population density in the 2 areas was obtained from statistical yearbooks. Further information for the individual farms on age distribution, housing of animals, herd size, pasturing and purchasing policy was gathered. The prevalence of PI animals was more than 10 times higher in Denmark as compared to Michigan. In herds without PI animals, the annual incidence of seroconversion as calculated from the age specific prevalence of antibody carriers varied in most age groups between 20-25% in Denmark and between 5-10% in Michigan. All investigated risk factors except for herd size were in favour of a lower prevalence of infection in Michigan. The use of having animals on pasture and at the same time having purchased more than 40 animals within recent 3 1/2-4 years were significantly associated with presence of PI animals in the dairy herds (p = 0.01) when tested by the Mantel-Haenszel chi 2. Using multivariable logistic regression, the occurrence of PI animals was found to be significantly related to the study area (Michigan and Denmark) as well as to herd size and purchase intensity.

Animals↗