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Biomedical subjects

M T Collins

Publications and source records attributed to M T Collins.

At least 19 recordsLinked to original sources
PubMed1996

Associations between subclinical paratuberculosis and milk production, milk components, and somatic cell counts in dairy herds.

OBJECTIVE: To determine associations between subclinical Mycobacterium paratuberculosis infection and milk production, milk components, and somatic cell counts of dairy cattle. DESIGN: Cross-sectional epidemiologic survey. ANIMALS: 23 dairy herds in Wisconsin containing 1,653 adult cows were studied. The herds had above average milk production and a history of bovine paratuberculosis in the herd within the previous 12 months. PROCEDURE: All adult cows in the herds were tested for paratuberculosis by use of an absorbed ELISA. Milk yield, fat, protein, and somatic cell count data were retrieved electronically from Dairy Herd Improvement Association records. RESULTS: 147 ELISA-positive and 1,506 ELISA-negative cows were identified. ELISA-positive cows had a mature-equivalent milk production of 376 kg (829 lb)/lactation less than that for ELISA-negative herdmates. Significant difference was not found in lactation average percent-ages of fat and protein, or somatic cell count linear score. When comparing ELISA-positive and -negative cow's current mature equivalent milk with all previous lactations, significant difference was found only from the immediate-preceding lactation. When this difference was examined by parity group, significant difference was confined to cows in the second lactation. CLINICAL IMPLICATIONS: Subclinical paratuberculosis infections, as determined by ELISA, are associated with a 4% reduction in milk yield and add to the already substantial costs of clinical M paratuberculosis infection in the dairy industry.

Analysis of Variance↗
PubMed1996

Epidemiologic study of on-farm management practices associated with prevalence of Mycobacterium paratuberculosis infections in dairy cattle.

OBJECTIVE: To use an on-farm recording form to quantity the effect of specific management practices on apparent prevalence of Mycobacterium paratuberculosis in dairy cattle herds. DESIGN: Epidemiologic survey. ANIMALS: 26 commercial Wisconsin dairy farms. PROCEDURES: An instrument was developed on the basis of literature review and expert interviews to quantify on-farm management practices associated with increased apparent prevalence of M paratuberculosis. On-farm visits were conducted to assess how specific management practices were conducted. Apparent prevalence of M paratuberculosis infection was measured for all animals > 20 months old on all farms, using a commercial ELISA. Regression analysis was used to identify management variables that were significantly associated with apparent prevalence of M paratuberculosis. RESULTS: Regression analysis (R2 = 0.90) identified that high scores for environmental conditions, newborn calf care, grower calf care, bred heifer care, and manure handling were significantly associated with M paratuberculosis apparent prevalence in Wisconsin dairy herds. CLINICAL IMPLICATIONS: Environmental conditions, newborn calf care, grower calf management, bred heifer management, and manure handling factors may serve as a prioritized checklist for instructing owners and managers where to place emphasis in changing management practices to limit M paratuberculosis prevalence. Likewise, the factors identified as having low association with apparent prevalence may be de-emphasized in control programs, allowing dairy managers to focus time and finances on more effective components of an M paratuberculosis control program.

Animal Husbandry↗
PubMed1996

Induction of L-arginine-dependent production of nitric oxide in bovine monocytes by interferon gamma and lipopolysaccharide.

Bovine monocytes freshly isolated from peripheral blood were induced to produce nitric oxide by exposing them to recombinant bovine interferon gamma (rbIFN-y) and Escherichia coli lipopolysaccharide (LPS) in vitro. Moderate amounts of nitric oxide were induced by rbIFN-gamma alone, but larger amounts were induced by rbIFN-gamma and LPS together, the amount being dependent on the quantity of rbIFN-gamma added. Reactive nitrogen intermediates (RNI) were produced within six hours, their concentration peaked at four days and they were detectable for at least eight days after the cells had been stimulated with rbIFN-gamma and LPS. The production of RNI was diminished by the addition of NG-monomethyl-L-arginine. The data suggest that bovine monocytes can produce RNI via a pathway involving an inducible nitric oxide synthase.

Animals↗
PubMed1996

Diagnosis of paratuberculosis.

The currently available and accurate diagnostic tests for paratuberculosis are reviewed. Technical issues concerning test performance are briefly mentioned and the advantages, disadvantages, and comparative accuracy are described. The article concludes with recommendations on which tests to use in eight different situations requiring laboratory diagnostics for paratuberculosis.

Animals↗
PubMed1996

Large scale synthesis of recombinant human thyrotropin using methotrexate amplification: chromatographic, immunological, and biological characterization.

Studies of human TSH (hTSH) structure and function have been limited by difficulties in producing large quantities of recombinant hormone. We describe a system for the stable expression of high levels of recombinant human TSH (rec hTSH) using a mutant form of dihydrofolate reductase (dhfr) as an amplifiable dominant selectable marker. A vector expressing both the hTSH alpha-subunit and the mutant dhfr was cotransfected with a hTSH beta-subunit expression vector into dhfr-deficient cells. Amplification of the transfected sequences by methotrexate selection, followed by cell culture in a hollow fiber perfusion system, yielded rec hTSH production as high as 100,000 microU/ mL. Immunoradiometric assays using five different antibodies revealed no differences in the immunological activities of rec hTSH and pituitary hTSH. Bioactivity was measured in a novel TSH bioassay coupling the generation of cAMP by a transfected hTSH receptor to the cAMP-dependent regulation of a luciferase reporter gene. The ED50 for bovine TSH in this bioassay was 1.4 ng/mL (3.5 x 10(-11) mol/L). The ratio of the ED50 values for rec hTSH and pituitary hTSH was 1.0:1.1 (P = NS), indicating that the two TSHs were of equivalent potency. In conclusion, we have developed techniques for the high level production of rec hTSH that is immunologically and biologically equivalent to pituitary hTSH. The ability to produce large quantities of rec hTSH using standard laboratory techniques should facilitate future studies, such as the development of clinically useful TSH analogs.

Animals↗
PubMed1996

Polymerase chain reaction analysis of TNF-alpha and IL-6 mRNA levels in whole blood from cattle naturally or experimentally infected with Mycobacterium paratuberculosis.

Johne's disease is characterized by a chronic enteritis that results in granulomatous inflammation, cachexia, and eventual death of cattle infected with Mycobacterium paratuberculosis. The cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) have been associated with granuloma formation and wasting in other disease syndromes. The potential role of these cytokines in the development and progression of Johne's disease has not been investigated. Using the polymerase chain reaction (PCR) and specific bovine oligonucleotide cytokine primers and probes, we examined the expression of messenger RNA for these cytokines in whole blood from M. paratuberculosis infected and uninfected cattle. Cytokine mRNA levels were examined before and after in vitro incubation with E.coli lipopolysaccharide (LPS) and lipoarabinomannan (LAM) purified from M. paratuberculosis. Uninfected calves, experimentally infected calves, and naturally infected cattle all displayed similar cytokine mRNA expression patterns. However, individual animals demonstrated variability in the levels of IL-6 and TNF-alpha mRNA expression as determined by a semiquantitative PCR method using 32P-labelled oligonucleotide probes.

Animals↗
PubMed1994

Herd prevalence and geographic distribution of, and risk factors for, bovine paratuberculosis in Wisconsin.

A random sample of Wisconsin dairy herds, stratified by herd size, were tested for paratuberculosis by use of an absorbed ELISA procedure. The ELISA was optimized for overall accuracy by means of receiver operating characteristic curve analysis, and had a sensitivity and specificity of 50.9 and 94.9%, respectively. Herd prevalence was analyzed for correlation with responses to a management practices questionnaire completed by the herd owners. One hundred and fifty-eight herds and 4,990 cattle were tested. Of these, 50% of herds and 7.29% of cattle had positive test results. Calculation of true prevalence from the apparent prevalence indicated that 4.79% of cattle and 34% of the Wisconsin dairy herds tested had serologic evidence of paratuberculosis. Among the 54 herds classified as positive on the basis of true prevalence estimation, the mean number of test positive cattle was 20.3%. The geographic distribution of herds with positive results was not uniform. More infected herds were found in the southern and western districts of Wisconsin than in the eastern district. The west-central district had a larger number of infected herds than did other districts. By use of chi 2 analysis, the only management factor found to be significantly associated with herd prevalence was housing of calves after weaning (P = 0.03). Specifically, in herds with higher prevalence, calves were separated after weaning into calf barns and hutches rather than into pens in the cow barn more often than in herds with lower prevalence. This factor was also considered significant by use of logistic regression analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗
PubMed1994

A sudden outbreak of illness suggestive of mass hysteria in schoolchildren.

OBJECTIVE: To clarify factors contributing to mass illness of sudden onset by studying an outbreak that was apparently triggered by a gaseous odor and that involved a rapid, extensive response by school and fire officials. SETTING: Urban elementary school. MAIN OUTCOME MEASURE: A standardized student questionnaire was designed to identify potential illness predictors. DESIGN: Four weeks following the outbreak, public health officials distributed the questionnaire to all students in regular classes in grades 3 through 6 (N = 319), representing 46% of the estimated 680 students present the day of the outbreak. RESULTS: Seventy-seven percent of the students who completed the questionnaire reported that they experienced physical symptoms during the epidemic. A stepwise regression analysis demonstrated several independent variables that predicted the severity of illness, including the intensity of the odor smelled during the outbreak (P < .0001), becoming sick after the fire trucks arrived (P < .0001), and believing in an environmental cause for the illness (P < .002). CONCLUSIONS: These results indicate that both psychological and environmental factors, real or perceived, may contribute to sudden-onset epidemics of hysteria. Moreover, the response intervention of officials may influence the extent of such outbreaks. Early recognition of psychological causes and dispersion of groups at risk could reduce morbidity and associated health care costs.

Child↗
PubMed1994

Evaluation of an enzyme-linked immunosorbent assay that uses the 41-kd flagellin as the antigen for detection of antibodies to Borrelia burgdorferi in cattle.

An ELISA was developed to detect antibodies to the 41-kd flagellin (P41) of Borrelia burgdorferi in serum obtained from cattle. Absorption studies, immunoblot analysis, immunoelectron microscopy, and correlation of results of the P41-ELISA and the P39-ELISA as well as measurement of the antibody to P41 in calves challenge-exposed with Borrelia theileri were used to assess the specificity of the P41-ELISA. Antigens derived from Escherichia coli, Leptospira interrogans serovar hardjo, and B burgdorferi were used for absorption studies and immunoblot analysis. Antibodies to P41 of B burgdorferi cross-reacted with antigens of E coli, but were not cross-reactive with L hardjo. A value 3 SD higher than the mean of the negative-control population of cattle was defined as the minimum value (cutoff value) for a positive result by the P41-ELISA. Use of this value for classification of test results reduced the predicted rate of false-positive results attributable to E coli cross-reactivity to 1%. Immunoblot analysis revealed that test-positive serum from cattle reacted mainly with 41-, 39-, 34-, and 31-kd proteins of B burgdorferi, as well as several smaller proteins. Immunoelectron microscopy revealed that serum from cattle that was test-positive by the P41-ELISA bound to the flagellin and outer membrane of B burgdorferi. Results of absorption studies, immunoblot analysis, and immunoelectron microscopy were correlated and indicated that serum from cattle that was test-positive by P41-ELISA had stronger reactivity to B burgdorferi antigens than to antigens of E coli or L hardjo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Seroepidemiologic survey of Borrelia burgdorferi exposure of dairy cattle in Wisconsin.

An ELISA, using purified flagellin of Borrelia burgdorferi as the solid-phase antigen, was used to measure antibody concentrations to B burgdorferi in dairy cattle in Wisconsin. Serum obtained from 5,060 cows in 160 randomly selected herds in the state were tested. Serum from an additional 2,600 cattle in Barron County, Wis, a county with a high annual incidence of B burgdorferi infections in human beings, was also tested. Only 7% of the cows that were tested, but 66% of the herds that were tested, were seropositive for B burgdorferi. Sixteen percent of the herds had a prevalence of > or = 15% seropositive cows, whereas 50% of the herds had a prevalence of 1 to 14% seropositive cows. Seropositive herds were concentrated in the west-central part of Wisconsin. An association existed between the geographic location of seropositive herds and counties in which B burgdorferi infection of human beings was acquired (P < 0.05) as well as the geographic location of seropositive herds and the geographic distribution of Ixodes scapularis (P < 0.05). Barron County, in which B burgdorferi infection is endemic, had a significantly (P < 0.05) higher percentage of seropositive cows (17%) than did the state of Wisconsin (7%).

Analysis of Variance↗
PubMed1994

Experimental model of swine pneumonic pasteurellosis using crude Actinobacillus pleuropneumoniae cytotoxin and Pasteurella multocida given endobronchially.

This study was designed to develop and characterize a swine pneumonic pasteurellosis model by concurrent introduction of Pasteurella multocida type A and Actinobacillus pleuropneumoniae crude cytotoxin. After a series of preliminary experiments, a combination of 4 x 10(9) P. multocida and 4,000 toxic units of A. pleuropneumoniae crude cytotoxin was determined to produce optimal results. A total of 48 pigs were divided into four groups of 12 pigs each. The control group received buffered saline only. Four pigs from each group were randomly selected for necropsy 3, 7 and 14 days postinoculation (PI). Inoculation of pigs with P. multocida and A. pleuropneumoniae cytotoxin (group 1) resulted in moderate to severe pneumonia. Pasteurella multocida was isolated from pneumonic lesions, grossly normal lung, and bronchial lymph nodes of all group 1 pigs throughout the 14 day experimental period. Pathological changes typical of field cases of swine pneumonic pasteurellosis were produced. Pigs inoculated with P. multocida alone (group 2) had pneumonic lesions and P. multocida was reisolated from lungs at three days PI. Pasteurella multocida was not isolated from these pigs at 7 and 14 days PI, except for one pig in which an abscess developed in the thorax. Pulmonary lesions induced by A. pleuropneumoniae crude cytotoxin alone (group 3) were transient and resolved by seven days PI. Group 1 pigs had significantly greater lung lesion volumes than group 2 and 3 pigs at 3, 7 and 14 days PI. Statistical analysis indicated a significant interactive effect of P. multocida and A. pleuropneumoniae cytotoxin on the development of lung lesion volumes at 7 and 14 days PI (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Actinobacillus pleuropneumoniae↗
PubMed1993

Inability to detect mycobactin in mycobacteria-infected tissues suggests an alternative iron acquisition mechanism by mycobacteria in vivo.

Although most species of mycobacterium are capable of producing mycobactin, it is not known if conditions within the host allow for mycobactin synthesis or whether it even plays a role in iron acquisition in vivo. We employed the mycobactin-auxotroph, Mycobacterium paratuberculosis, in a bioassay to examine tissues from animals infected with either Mycobacterium tuberculosis, Mycobacterium avium or M. paratuberculosis for the presence of mycobactin or compounds which demonstrate mycobactin-like activity. Other iron-binding compounds, including purified siderophores from unrelated organisms and host iron-binding proteins were also evaluated in the bioassay for growth induction of M. paratuberculosis in the absence of mycobactin. Although mycobactin could be easily demonstrated in tissues artificially seeded with mycobacteria, no mycobactin could be detected in heavily infected tissues. None of the purified siderophores from unrelated microorganisms were found to support growth of M. paratuberculosis in the absence of mycobactin. Host iron-binding proteins (transferrin, lactoferrin, ferritin, hemin) also failed to induce growth in the bioassay at pH 6.8, however, when the pH was adjusted between 5-6.2, transferrin and lactoferrin promoted growth of M. paratuberculosis without mycobactin, probably as a result of the dissociation of iron rather than a specific interaction. We confirm that mycobacteria are incapable of iron uptake when iron is chelated to siderophores from unrelated organisms and conclude that mycobactin-mediated mechanisms of iron-acquisition by mycobacteria do not appear to have as significant a role in vivo as in vitro. In addition, evidence is presented that suggests iron-containing transferrin and lactoferrin at low pH may circumvent the need for mycobactin by M. paratuberculosis.

Animals↗
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↗
PubMed1993

Cefazolin antibacterial activity and concentrations in serum and the surgical wound in dogs.

An antibiotic selected for surgical antimicrobial prophylaxis must be present in the surgical site throughout the operation in concentration sufficient to prevent growth of contaminating pathogens. The antimicrobial spectrum, minimal toxicity, and low cost of cefazolin make this first-generation cephalosporin a logical choice for antimicrobial prophylaxis in small animal surgical procedures in which the normal microbiologic flora of skin and gastrointestinal tract are the most likely pathogens. Pharmacokinetic variables of cefazolin were determined in serum and surgical wounds in dogs. Drug concentration in interstitial fluid of muscle biopsy specimens taken at random from wound surfaces and in postoperative wound fluid samples were determined. Effective surgical wound concentration of cefazolin was defined as 4 micrograms/ml, a concentration that inhibited the growth in vitro of 100% of staphylococcal and 80% of Escherichia coli clinical isolates. After IV and SC administrations, cefazolin equilibrated rapidly between serum and the surgical wound, and concentrations in the 2 sites decreased in parallel. With a bolus dose of 20 mg/kg of body weight given IV at the beginning of surgery and repeated by SC administration at 6 hours, cefazolin concentration in the surgical wound remained > 4 micrograms/ml for longer than 12 hours.

Animals↗
PubMed1993

The (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) colorimetric assay for the quantitation of Actinobacillus pleuropneumoniae cytotoxin.

Using swine neutrophils as target cells, two MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) colorimetric assay systems, one with and one without phorbol 12-myristate 13-acetate (PMA) stimulation were established for the quantitation of Actinobacillus pleuropneumoniae cytotoxin. The MTT assays were optimized for the number of neutrophils, incubation time, and PMA concentration by a series of experiments. The optimal conditions were 25 x 10(4) cells/well incubated for four hours for the assay system without PMA stimulation, and 12.5 x 10(4) cells/well incubated for two hours for the assay system with PMA stimulation. One culture supernatant of a toxigenic Pasteurella multocida strain and five A. pleuropneumoniae cytotoxin preparations produced from three A. pleuropneumoniae strains were used to test assay reproducibility. Results showed both assays were reproducible with a coefficient of variation ranging from 7.8 to 18% for the assay system without PMA stimulation and from 10.7 to 18.2% for the assay system with PMA stimulation. The PMA-stimulated assay had 40 to 60-fold higher sensitivity than the nonstimulated MTT assay. The MTT assay also was applied to the measurement of neutralizing antibody titers against A. pleuropneumoniae cytotoxin.

Actinobacillus pleuropneumoniae↗