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Biomedical subjects

C O Thoen

Publications and source records attributed to C O Thoen.

At least 19 recordsLinked to original sources
PubMed1992

Plasmid profile analysis, phage typing, and antibiotic sensitivity of Salmonella dublin from clinical isolates in the United States.

One hundred clinical isolates of Salmonella choleraesuis subsp. choleraesuis serovar dublin (Salmonella dublin) were examined for phage sensitivity, antibiotic resistance patterns, and plasmid content. Computer analysis of the lysis patterns observed by using 27 typing phages divided the S. dublin isolates into 26 groups. One lytic pattern (Designated pattern 16) contained 52% of the isolates examined whereas 16 isolates had unique patterns, and nine patterns had fewer than ten members. Although 14 antibiotic resistance patterns were observed among the 100 isolates, 79% of the isolates grouped in three major patterns. Seven plasmid groups were identified and designated A-G based on the large plasmids found in the isolates. Of the 100 isolates, 28 contained the plasmid profile of Group A, 28 were Group B, 7 were Group C, 34 were Group D, and 1 isolate each was observed in Groups E, F, and G. The strong association between antibiotic resistance pattern and plasmid type suggest that the drug resistance genes are plasmid borne.

Animals↗
PubMed1992

Molecular cloning and characterization of Mycobacterium paratuberculosis promoters in Escherichia coli.

DNA fragments from Mycobacterium paratuberculosis were cloned in the promoter probe plasmid pKO1. Of 957 recombinant DNA clones, 24 induced synthesis of galactokinase (the reporter gene) when these plasmids were transformed into an Escherichia coli strain deficient for the enzyme. A DNA insert from one putative promoter-containing plasmid, designated pAG5, was sequenced and shown to contain, a characteristic RNA polymerase binding site, a probable ribosomal binding site and a putative open reading frame.

Amino Acid Sequence↗
PubMed1992

Mycobacterium bovis infection in North American elk (Cervus elaphus).

A naturally occurring outbreak of Mycobacterium bovis infection in captive wild elk (wapiti) in Montana was confirmed by mycobacteriologic examination. Twenty-eight of 143 elk responded to M. bovis purified protein derivative (PPD) tuberculin injected intradermally in the cervical region (SCT). The results of comparative cervical tuberculin skin tests conducted within 9 days of SCT revealed greater responses to M. bovis PPD tuberculin than to M. avium PPD tuberculin in 23 of 28 elk responding. At necropsy, several grossly visible tuberculous lesions were observed in the parenchyma of the lung, thoracic lymph nodes, and submandibular lymph nodes. Microscopic examination of appropriately stained tissue sections revealed the presence of granulomatous lesions containing acid-fast bacilli. An enzyme-linked immunosorbent assay (ELISA) was developed using a sarkosyl extract of M. bovis (antigen) and peroxidase-labeled protein G (conjugate); reactions were detected in the sera of 8 of 9 elk responding to M. bovis PPD tuberculin. Lymphocyte blastogenic assay responses were detected using M. bovis antigens in 7 of 9 elk positive on skin tests using M. bovis PPD.

Animals↗
PubMed1991

Application of an enzyme immunoassay for detecting antibodies in sera of Macaca fascicularis naturally exposed to Mycobacterium tuberculosis.

An enzyme immunoassay (EIA) was developed for detecting mycobacterial antibodies in the sera of 22 Macaca fascicularis following a natural outbreak of tuberculosis. EIAs were conducted using four antigens (lysozyme, triton, or deoxycholate extracts of Mycobacterium tuberculosis or a purified protein derivative) and two conjugates (protein A or antihuman). Mycobacterial antibodies were detected in two of two culture-positive monkeys, in nine of ten tuberculin test-suspect monkeys (culture-negative), and in five of ten tuberculin test-negative monkeys (culture-negative). Results indicate EIA may be of practical value in detecting monkeys exposed to M. tuberculosis.

Animals↗
PubMed1990

Some immune responses in cattle exposed to Mycobacterium paratuberculosis after injection with modified-live bovine viral diarrhea virus vaccine.

Delayed-type hypersensitivity responses to Mycobacterium paratuberculosis purified protein derivative (PPD) were decreased in cows experimentally exposed to M. paratuberculosis 7 days after exposure to a modified-live bovine viral diarrhea virus (ML-BVDV) vaccine. In vitro lymphocyte blastogenic responses to phytohemagglutinin were decreased in each of 3 cows 7 days after exposure to ML-BVDV vaccine. Also, decreased lymphocyte blastogenic responses to M. paratuberculosis PPD were observed in cultures of 2 of 3 cows 7 days after exposure to ML-BVDV vaccine. No significant differences in enzyme-linked immunosorbent assay reactions were detected in sera of M. paratuberculosis-infected cattle collected before and at 4 and 12 weeks after exposure to ML-BVDV vaccine.

Animals↗
PubMed1990

Evaluation of an enzyme immunoassay for diagnosis of bovine leptospirosis caused by Leptospira interrogans serovar hardjo type hardjo-bovis.

Sensitivity and specificity of 4 different antigen preparations from Leptospira interrogans serovar hardjo were compared in an enzyme immunoassay for detection of antibodies against serovar hardjo type hardjo-bovis in serum. Two antigens prepared using detergents showed serogroup cross-reactivity. A mechanically extracted membrane and a lipopolysaccharide antigen showed a high degree of leptospiral serogroup specificity. The lipopolysaccharide antigen was the most suitable antigen for detection of anti-hardjo antibodies. Enzyme immunoassay was more sensitive than the microscopic agglutination test for detecting antibodies in serum from experimentally and naturally infected cattle. It was not possible to differentiate vaccinated from infected animals or to detect a secondary immune response in vaccinated animals that were subsequently infected.

Agglutination Tests↗
PubMed1990

Production and partial characterization of monoclonal antibodies to the neotype strain of Mycobacterium bovis.

Six monoclonal antibodies (MAB) to virulent Mycobacterium bovis ATCC 19210 were produced, using a suspension of heat-inactivated whole cells. Immunoglobulin isotype for MAB VMB6, VMB73, and VMB93 was IgG1, and for VMB31, VMB99, and VMB119, it was IgG2a. Monoclonal antibodies were examined for cross-reactivity to M tuberculosis, M kansasii, M fortuitum, M paratuberculosis, M avium serovars 1, 2, 4, 8, and 10, M chelonei, M phlei, M scrofulaceum, M smegmatis, Nocardia asteroides, and Rhodococcus equi. Monoclonal antibodies could be grouped on the basis of binding activity by ELISA and immunoblot analysis, in which MAB VMB6, VMB31, and VMB119 had binding activity to M bovis; MAB VMB93 and VMB99 detected M bovis and M tuberculosis antigens, and MAB VMB73 reacted with other mycobacterial species, as well as with N asteroides and R equi. Apparent molecular mass of antigens was 30 to 25 kilodaltons (kD) for VMB6, VMB31, and VMB119 and 63 kD for VMB93 and VMB99, and ranged from greater than 200 to 31 kD for VMB73, as estimated by immunoblot analysis. Monoclonal antibody binding activity to 18 field isolates of M bovis was evaluated, using ELISA. Each of 18 field isolates was detected, using MAB VMB6, VMB31, or VMB119; 10 isolates were detected, using MAB VMB93/VMB99, and 14 were detected by use of MAB VMB73. Use of MAB in ELISA failed to detect antigens from M bovis strain AN-5.

Animals↗
PubMed1989

Paratuberculosis in cattle: a comparison of three serologic tests with results of fecal culture.

Feces and blood were collected from cattle in 13 herds known to be infected with Mycobacterium paratuberculosis to evaluate a complement-fixation (CF) test, an agar gel immunodiffusion (AGID) test and an enzyme-linked immunosorbent assay (ELISA) for the serologic diagnosis of paratuberculosis. M. paratuberculosis was isolated from the feces of 36 of 192 cattle examined. Twenty-three culture-positive animals had CF test titers regarded as suspect or positive, 10 were positive by the AGID test and 34 were suspect or positive by the ELISA. Of the 156 culture-negative animals, the CF test agreed on 136, the ELISA on 129 and the AGID on 151.

Animals↗
PubMed1989

Serum biochemical and hematologic values of normal and Mycobacterium bovis-infected American bison.

Hematologic and serum biochemical tests were used to monitor the health of 3 groups of bison in an experimental study of tuberculosis. Bison were randomly assigned to Mycobacterium bovis-infected, M. bovis-sensitized, and uninfected control groups. Hematologic measurements included total and differential leukocyte counts, hemoglobin (Hb), packed cell volume (PCV), fibrinogen, and plasma proteins. Biochemical tests included serum urea nitrogen, creatinine, aspartate amino transferase, sorbitol dehydrogenase, serum calcium, and serum phosphorus. There were no significant differences (P = 0.05) in any test values between groups of bison. The bison data were combined and compared to similar data of cattle. The mean values for PCV and Hb were higher than values (PCV 24-46%, Hb 8-15 g/dl) for cattle. Mycobacterium bovis-infected bison had a slight increase in the number of blood monocytes and lymphocytes when compared to the uninfected bison but were within the normal ranges for bison and cattle. Other hematologic parameters were within normal ranges reported for cattle. Creatinine levels in all bison were above the normal range (1.0-1.5 mg/dl) for cattle. Phosphorus levels for M. bovis-infected and M. bovis-sensitized bison exceeded the normal range (5.6-8.0 mg/dl) reported for cattle. The level for uninfected bison was near the upper limit of normal for cattle. Mean values for other serum biochemical tests were within the normal ranges reported for cattle.

Animals↗
PubMed1989

Control of Johne's disease in four commercial dairy herds in Iowa.

A 6-year study was conducted in 4 dairy herds in Iowa in which Johne's disease was diagnosed previously. Fecal specimens were collected at 6-month intervals from animals 2 years of age and over for mycobacteriologic examination. Serum samples were obtained at 3-month intervals and tested by enzyme-linked immunosorbent assay (ELISA). The antigen used in the ELISA was a potassium chloride extract of a field strain of Mycobacterium paratuberculosis. The ELISA reactions were observed in 87% of the cows from which M. paratuberculosis was isolated. Dairy producers that participated in the Johne's control program reported reduced economic losses. Increased income was attributed to improved milk production, increased value of vaccinated animals sold as replacements to other dairy herds in which Johne's disease had been diagnosed, and the increased market value of slaughter animals removed from the herd.

Animals↗
PubMed1989

Genetic relatedness among Mycobacterium paratuberculosis and M. avium complex.

Total DNA was extracted from M. paratuberculosis (ATCC 19698) and from M. avium complex (ATCC 25291) cultivated on RVB-10 enriched liquid media. Restriction endonuclease analysis of total DNA was performed with 34 enzymes and DNA digestion profiles were compared. Fifteen enzymes revealed important differences between the two species. Two pairs of enzymes (EcoRII, BstNI) and (MboI, Sau3AI) provide evidence for the presence of dcmI and dam methylation in DNA of M. avium complex and M. paratuberculosis. The differences in DNA fragments of these two species could be of potential value in differentiating these clinically significant mycobacteria.

DNA Probes↗
PubMed1989

Genetic relatedness among Mycobacterium tuberculosis and M. bovis.

Total DNA from two slowly-growing pathogenic mycobacterial species propagated in vitro was isolated, digested with each of 34 restriction endonucleases and analyzed by agarose gel electrophoresis. The most resolved patterns for M. tuberculosis (ATCC 27294) and for M. bovis (ATCC 19210) were obtained respectively using (BamHI, DraI, ClaI, EcoRI, EcoRV, HindIII, HpaI, SalI, SmaI, XbaI and XmaI). The patterns produced for these strains were reproducible and distinguishable from each other respectively using (HindIII, DraI, EcoRI, MboI, Sau3AI and AvaI). However, with several enzymes (SalI, AsuI, Sau96I, MspI and HpaII) the patterns for M. tuberculosis and M. bovis were similar. Evidence was obtained for the presence of dam and dcmI methylations in the DNA of each mycobacterial species respectively using (MboI, Sau3AI, EcoRII, BstNI, Sau96I and AsuI).

Biological Evolution↗
PubMed1988

Tuberculosis.

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Animals↗
PubMed1988

Pathogenesis of Mycobacterium bovis infection in American bison.

Eighteen 12-month-old bison were randomly placed in each of 3 groups (6 animals/group): group-1 bison were exposed to live Mycobacterium bovis, group-2 bison were inoculated with killed M bovis in oil, and group-3 bison were noninfected controls. Six, 6-month-old, tuberculin test-negative calves were placed (pen contact) with group-1 bison 30 days after exposure to M bovis. Tuberculin skin test responses (caudal fold and/or comparative cervical) were detected in all bison in groups 1 and 2 at 2, 4, 6, 10, and 12 months. Tuberculin skin test responses were observed in 2 of 6 calves at 9 and 11 months after pen contact with M bovis-exposed bison (group 1). Statistically significant lymphocyte blastogenic responses to M bovis purified protein derivative were detected in group-1 bison exposed to live M bovis at 2 months after exposure (P less than 0.025). Significant ELISA reactions were detected in sera of bison at 2 months after exposure to killed M bovis in oil (P less than 0.005) and in bison 2 months after exposure to live M bovis (P less than 0.01). Significant tuberculin skin responses, ELISA reactions, or lymphocyte blastogenic responses to M bovis purified protein derivative were not observed in the 6 control bison. Grossly visible tuberculous lesions were observed in lymph nodes and/or lung collected at necropsy in 4 of 6 bison at 12 months after exposure to live M bovis. Microscopic granulomas compatible with tuberculosis were detected in 5 of 6 bison; M bovis was isolated from tissues of each of the 6 bison.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗