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Biomedical subjects

R H Whitlock

Publications and source records attributed to R H Whitlock.

At least 19 recordsLinked to original sources
PubMed1997

Epithelial antibiotic induced in states of disease.

Epithelial defensins provide an active defense against the external microbial environment. We investigated the distribution and expression of this class of antimicrobial peptides in normal cattle and in animals in varying states of disease. beta-defensin mRNA was found to be widely expressed in numerous exposed epithelia but was found at higher levels in tissues that are constantly exposed to and colonized by microorganisms. We observed induction in ileal mucosa during chronic infection with Mycobacterium paratuberculosis and in bronchial epithelium after acute infection with Pasteurella haemolytica. It has been proposed that expression of antimicrobial peptides is an integral component of the inflammatory response. The results reported here support this hypothesis and suggest that epithelial defensins provide a rapidly mobilized local defense against infectious organisms.

Animals↗
PubMed1997

Hypokalemia syndrome in dairy cows: 10 cases (1992-1996)

OBJECTIVE: To evaluate clinical findings in cows with recumbency associated with hypokalemia. DESIGN: Retrospective case series. ANIMALS: 10 adult dairy cows with weakness or recumbency and hypokalemia. PROCEDURE: Signalment, history, physical examination findings, results of diagnostic tests, and response to treatment were extracted from the medical record of each cow. RESULTS: 8 cows were recumbent on admission and 2 were profoundly weak. All cows had been given isoflupredone acetate as treatment for ketosis prior to admission. All were hypokalemic (serum potassium concentration, 1.4 to 2.3 mEq/L) with no other apparent cause for recumbency. Despite treatment with potassium, plasma potassium concentrations within the reference range were achieved in only 6 of the 9 cows treated. Two cows responded to treatment. Three cows died, 3 were euthanatized, 2 improved clinically and were discharged, 1 was discharged while still recumbent, and 1 was sent to slaughter prior to treatment. Histologic examination of muscle tissue from 2 cows revealed myonecrosis and vacuolation consistent with hypokalemic myopathy. CLINICAL IMPLICATIONS: Hypokalemia should be considered in the differential diagnosis for cows that are weak or recumbent, particularly after treatment for ketosis with isoflupredone acetate. Aggressive treatment with potassium salts administered orally is indicated.

Administration, Oral↗
PubMed1997

Botulism.

Equine botulism is being recognized with increasing frequency by veterinarians throughout North America. Muscular weakness and dysphagia that progress during a period of 1 to 4 days, in the absence of laboratory derangements that indicate the presence of systemic disease, are suggestive of botulism. A tentative diagnosis usually is based on the presence of the following findings on physical examination: delayed pupillary light response, mydriasis, ptosis, generalized weakness, decreased tail tone, and slow prehension of feed. Definitive diagnosis requires detection of botulinum toxin in plasma, serum, gastrointestinal contents, or body tissues. Early treatment with antitoxin generally results in a favorable outcome. Botulism in foals and adult horses can be prevented by vaccination.

Animals↗
PubMed1996

Preclinical and clinical manifestations of paratuberculosis (including pathology).

The term Johne's disease immediately brings to mind an image of an emaciated, debilitated ruminant with bottlejaw and fluid, pipestream diarrhea. However, the clinical case is merely the tip of the iceberg in terms of the total number of infected animals on the farm. If the clinically affected animal was born on the farm, a minimum of 25 other animals are probably infected and less than 30% of those will be detectable by currently available tests. Infected animals in the early stages of the disease progress slowly over a period of months or several years to stages that may be detected by antigen detection tests and antibody-based diagnostic tests. The duration of each stage of infection depends on age at the time of exposure and the dose of organisms ingested. The lack of tests sensitive enough to detect infected animals in the earliest stages of disease is a serious obstacle to eradication of Johne's disease. The animals with overt infection may be culled from the herd immediately on detection. However, the animals that are shedding organisms below the threshold of detectability and have not mounted an immune response remain behind to contaminate the environment and infect herdmates.

Animals↗
PubMed1995

Streptococcal fibrinous pericarditis and peritonitis in a Vietnamese pot-bellied pig.

An 8-month-old female Vietnamese pot-bellied pig was examined because of a 48-hour history of anorexia and signs of depression. Hypothermia, dehydration, pronounced respiratory effort, and muffled heart sounds were detected. Abdominal ultrasonography revealed ascites and hepatic congestion. Echocardiography revealed pericardial effusion and fibrinous pericarditis. Ultrasound-guided pericardiocentesis was diagnostic and therapeutic. Cytologic examination of pericardial and peritoneal fluid revealed degenerated neutrophils and intra-and extracellular gram-positive cocci. On microbial culture of pericardial and peritoneal fluid specimens, moderate growth of a beta-hemolytic Streptococcus sp of group G was observed. After initial treatment corrected hypothermia and dehydration, the pig was treated with sulfadiazine/sulfamerazine/sulfamethazine and oxytetracycline for 30 days. Echocardiographic examination 3 months after the initial examination revealed resolution of the pericardial effusion and fibrinous pericarditis.

Animals↗
PubMed1995

Evaluation of a commercial enzyme-linked immunosorbent assay for the diagnosis of paratuberculosis in dairy cattle.

The performance of a commercially available ELISA for detection of antibodies to Mycobacterium paratuberculosis was evaluated using sera from 1,146 cows. Samples were from uninfected cattle, infected subclinical cattle shedding low numbers of organism in feces, subclinical heavy shedders, clinical cases, and randomly selected cattle in a slaughterhouse survey for paratuberculosis. The overall sensitivity of the test, using the manufacturer's recommended cutoff was 45% +/- 4.8%, and the specificity was 99% +/- 0.9%. The ELISA result was significantly correlated with the number of colonies of M. paratuberculosis detected by fecal culturing. The sensitivity of the test was highest for clinical cases of paratuberculosis (87% +/- 8.4%), and lowest for subclinical, light-shedding cattle (15% +/- 6.6%). Changing the cutoff point did not improve performance of the test. Evaluating ELISA results with a kinetic-based method reduced plate-to-plate variation in results but did not improve performance of the test based on receiver-operating characteristic curve analysis.

Animals↗
PubMed1994

Results of using histologic examination and acid-fast staining to confirm a diagnosis of swine mycobacteriosis made on the basis of gross examination.

Overall, 74% of the tissue specimens that meat inspectors at a large Pennsylvania packing plant identified as lesions of swine mycobacteriosis yielded Mycobacterium avium on bacteriologic culture. Histopathologic lesions compatible with mycobacteriosis were identified in 83% of the specimens; only 12% of the specimens had acid-fast staining organisms.

Abattoirs↗
PubMed1994

Diagnosis of paratuberculosis in dairy cattle, using enzyme-linked immunosorbent assay for detection of antibodies against Mycobacterium paratuberculosis in milk.

An ELISA containing lipoarabinomannan (LAM) antigen was used to detect antibodies in milk and serum for diagnosis of Mycobacterium paratuberculosis infection in dairy cattle. In experiment 1, milk and serum samples were obtained from 25 cows, and subjected to LAM ELISA testing immediately, and after 1 year of storage at -70 C. Milk samples, with and without a commonly used chemical preservative, were tested. There was no significant difference in LAM ELISA results between fresh and frozen samples or between preserved and unpreserved milk samples. In experiment 2, milk samples were collected daily from 30 cows over a 14-day period. The day-to-day coefficient of variation was 0.19 for milk LAM ELISA and was 0.15 for serum LAM ELISA, with no statistically significant time effect detected. In experiment 3, single milk, serum, and fecal samples were obtained from 764 cows. The fecal samples were cultured for M paratuberculosis to identify infected cows, and the serum and milk samples were subjected to LAM ELISA testing. Results were compared, using the area under the receiver operating characteristic curves. The milk LAM ELISA had specificity (+/- 95% confidence limits) of 87 +/- 8.1% when the cutoff was set at 50% sensitivity, and specificity of 83 +/- 9.1% when sensitivity was set at 60%. The area under the receiver operating characteristic curve was 0.85 +/- 0.03 for the milk ELISA and 0.75 +/- 0.02 for the serum ELISA. In this population of cattle, the milk LAM ELISA had comparable accuracy to serum LAM ELISA, although the milk LAM ELISA was slightly less reproducible (higher coefficient of variation).

Animals↗
PubMed1993

An in-depth study of Crohn's disease in two French families.

BACKGROUND: Two French families were investigated. In the first a husband, wife, and 4 children had Crohn's disease; in the second 7 of 11 children had the disease. There was no history of Crohn's disease in antecedent generations and no linkage to HLA haplotypes. METHODS: Methods included family interviews; review of medical records, radiographs, and pathology slides; serology; selective stool culture; enzyme-linked immunosorbent assay for fecal viral detection; and immunocytochemistry. RESULTS: In both families multiple cases occurred among siblings in 7-13-month periods. There appeared to be a 4-8-year recurrence of new disease in both families. Radiographs showed a remarkable similarity in the pattern of disease, confined to distal ileum and cecum, in the members of family 1. Examination for pathology showed granulomas in all 8 patients for whom tissues were available. Acid-fast organisms or Campylobacter-like organisms were not found in tissue sections, and immunocytochemistry was negative for mycobacteria and Yersinia. Stool cultures were negative for mycobacteria, Yersinia, and Mycoplasma. Torovirus and coronavirus antigens were not found in stool. Serology was negative for antibodies to Brucella, Yersinia, influenza, and three enteropathogenic viruses of animals. CONCLUSIONS: The circumstances and data suggest that an infectious microorganism is responsible for these clusterings of Crohn's disease.

Adult↗
PubMed1993

Reproducibility of a commercial enzyme-linked immunosorbent assay for bovine paratuberculosis among eight laboratories.

Interlaboratory reproducibility of an absorbed enzyme-linked immunosorbent assay (ELISA) kit for detection of bovine serum antibodies to Mycobacterium paratuberculosis was evaluated. A panel of 30 bovine sera (15 positives and 15 negatives) was tested in triplicate microtiter wells on each of 2 days at 8 different laboratories. One laboratory had invalid results because of positive or negative serum control optical density (OD) readings beyond the acceptable range specified by the kit. The coefficient of variation (CV) for mean OD values was influenced by low ODs on test negative sera at 2 laboratories, thus the CVs on positive sera were considered a more representative measure of kit reproducibility. Between-well CVs averaged 6.7% +/- 2.8% (mean +/- standard deviation), and between-day CVs averaged 14.5% +/- 9.8% among the 7 laboratories with valid assays on the 15 positive sera. The OD values were converted to positive or negative classifications for each assay well, and the results were compared. Among 1,392 assays in 7 laboratories, 98.6% were in agreement. Eleven of 18 discrepant results were due to a sample that consistently gave OD values near the cutoff for a positive test. Exclusion of that serum from the analysis resulted in a 99.8% rate of agreement among laboratories. Results indicated that the absorbed ELISA kit provided reproducible results within and between laboratories.

Analysis of Variance↗
PubMed1992

Mycobacterium paratuberculosis cultured from milk and supramammary lymph nodes of infected asymptomatic cows.

Milk and supramammary lymph node samples were obtained from asymptomatic cows infected with Mycobacterium paratuberculosis at the time of slaughter. Of 81 supramammary lymph node samples, 22 (27%) were culture positive for M. paratuberculosis. Of 77 milk samples, 9 (11.6%) were culture positive. The prevalence of supramammary lymph node or milk infection was highest with heavy fecal shedding of M. paratuberculosis and lowest with light shedding. The serologic status of the cow was not useful for predicting the risk of supramammary lymph node or milk infection. Shedding of M. paratuberculosis occurs in the milk of asymptomatic infected cows but, apparently, less frequently than previously reported for symptomatic cows.

Animals↗
PubMed1992

Effect of treatment with oxytetracycline during the acute stages of experimentally induced equine ehrlichial colitis in ponies.

Eighteen ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocyte cells. Twenty-four hours after onset of fever (rectal temperature > 38.8 C), 9 ponies were treated with oxytetracycline (6.6 mg/kg of body weight, IV, q 24 h) for 5 days. The remaining 9 ponies served as infected nontreated controls. Mean scores of the following variables were not significantly different between groups on the day treatment was begun: rectal temperature, diarrhea, borborygmal sounds, feed intake, mental attitude, and evidence of a hyperresonant area in the abdomen. All ponies were observed for progression of clinical signs typical of ehrlichial colitis. Within 12 hours of initiation of treatment, only 1 treated pony had a rectal temperature > 38.8 C and most rectal temperatures were < 38.3 C. In contrast, only 2 control ponies had rectal temperatures < 38.8 C (mean rectal temperature values were significantly, P = 0.01, different between groups). In the treatment group, 4 ponies had no signs of depression after the first day of treatment, and only 1 had signs of depression after the second day of treatment (mean scores between groups were significantly different, P = 0.01). Feed intake remained normal in 4 treated ponies and improved in 4 of the remaining 5 after treatment began. Most of the control ponies had a progressive decrease in their feed intake during the observation period (mean scores between groups were significantly, P = 0.01, different). Three ponies in the control group and 2 ponies in the treatment group developed diarrhea before the treatment observation period began.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Isolation of Mycobacterium paratuberculosis after oral inoculation in uninfected cattle.

Feces from cows naturally infected with Mycobacterium paratuberculosis was given to 6 uninfected heifers by orogastric intubation, to determine whether ingested organisms could be passively excreted and detected by bacteriologic culture of feces (ie, false-positive result). Heifers were paired, and each pair received a different dose of feces on days 1 and 2. Fecal samples were collected from the heifers 3 times daily. Mycobacterium paratuberculosis was detected in fecal samples of all heifers within 18 hours of being given the first dose of feces. The number of colony-forming units peaked on days 3 or 4, and organisms were no longer detected by day 7. The number of colony-forming units in fecal samples from the heifers was approximately proportional to the dose given. On days 15 and 16, the experiment was repeated with feces from a second infected cow. Results were similar to those in the first experiment. All heifers remained seronegative (agar-gel immunodiffusion test and ELISA) and had negative results to the intradermal johnin test throughout the experiment. Lymph node and intestinal tissues were obtained from all 6 heifers at slaughter on day 28. Mycobacterium paratuberculosis was not isolated from mesenteric lymph nodes from the ileocecal valve region, but was isolated from ileal mucosal samples from each heifer.

Animals↗
PubMed1992

Mycobacterium paratuberculosis isolated from fetuses of infected cows not manifesting signs of the disease.

Fetuses were obtained from 58 cows that were fecal culture-positive for Mycobacterium paratuberculosis, but were not manifesting signs of paratuberculosis. Fetal tissues from 5 of 58 cows were culture-positive for M paratuberculosis. All 5 culture-positive fetuses were from cows that were classified as heavy fecal shedders (5/28; 17.8%). Difference in prevalence of fetal infection between light (less than 70 colonies/tube) and heavy fecal shedders was significant (Fisher's exact test, P less than 0.05). Association was not evident between serologic status of the dam and prevalence of fetal infection. In infected cows without signs of paratuberculosis, fetal infection develops with lower frequency than previously reported for cows with clinical signs of the disease. In this study, fetal infection was found only in cows that were heavy fecal shedders.

Animals↗
PubMed1991

Botulism associated with feeding alfalfa hay to horses.

Botulism was believed to be the cause of progressive symmetric myasthenia in 8 horses on a farm in North Carolina. One horse was found dead, 6 were euthanatized after becoming recumbent, and 1 affected horse recovered. Cecal and colonic contents of 2 horses were determined to contain Clostridium botulinum spores. Alfalfa hay that was fed to the horses contained spores and toxin.

Animals↗
PubMed1990

Feed additives and contaminants as a cause of equine disease.

The equine practitioner often encounters serious diagnostic and therapeutic challenges regarding the specific origin of a disease. Such challenges may occur when horses become unaccountably ill after consuming what was thought to be acceptable feed but which in fact was contaminated or contained additives intended for other species. Examples of such additives and contaminants are monensin, lasalocid, salinomycin, blister beetles, and such antimicrobics as lincomycin and clindamycin.

Animal Feed↗
PubMed1990

Resistance to development of equine ehrlichial colitis in experimentally inoculated horses and ponies.

Fourteen ponies and 3 horses were inoculated with Ehrlichia risticii 2 to 20 months after a similar initial inoculation. Although all 17 had clinical signs of equine ehrlichial colitis after the first inoculation, 16 of 17 remained clinically normal following the second inoculation. The remaining pony had a transient fever and developed signs of depression. Before the initial inoculation, none of the animals had a detectable antibody titer to E risticii. All animals developed titers after the initial infection; however, a significant change of titer did not develop after reinoculation in most animals.

Animals↗