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Biomedical subjects

J B Jorgensen

Publications and source records attributed to J B Jorgensen.

At least 19 recordsLinked to original sources
PubMed1993

Use of a dot enzyme-linked immunosorbent assay on absorbed sera for the diagnosis of bovine paratuberculosis.

This study describes the response of cattle to a dot enzyme-linked immunosorbent assay (ELISA) using sera absorbed with Mycobacterium phlei. Results obtained by visual observation are compared with those obtained using a densitometer. Infection status of cattle was determined by faecal culture. Cattle of different levels of exposure and disease manifestation were examined. A significantly higher dot ELISA response was observed (using both absorbed and non-absorbed sera) in animals with heavy shedding of M. paratuberculosis than in animals which tested negative by faecal culture or shed M. paratuberculosis at lower levels (P < 0.05). Paratuberculosis was diagnosed by visual determination of dot ELISA results using non-absorbed sera in 29 of 44 (65.9%) clinically-suspect animals giving positive results by faecal culture, and 85 of 93 (91.4%) cattle testing negative by faecal culture. With absorbed sera, the sensitivity of visual determination decreased to 15 of 44 (34.1%), while specificity increased to 91 of 93 (97.8%). Approximately 75% of cattle yielding positive results by dot ELISA were heavy bacterial shedders (> 1,500 colonies/g of faeces) at the time of serological testing. Comparison of the dot ELISA results determined visually with results obtained by objective densitometric measurement showed compatible specificity. Sensitivity of the dot ELISA was 65.9% for non-absorbed sera using visual evaluation and 87.5% using densitometric evaluation at a cut-off optical density value of 0.2. For absorbed sera, the values were 34.1% and 82.5%, respectively.

Absorption↗
PubMed1992

Diagnostic accuracy of a Mycobacterium phlei-absorbed serum enzyme-linked immunosorbent assay for diagnosis of bovine paratuberculosis in dairy cows.

The purpose of this study was to describe the responses of sera from five groups of cattle to an enzyme-linked immunosorbent assay (ELISA) for paratuberculosis by using serum absorbed with Mycobacterium phlei at a single working dilution. The infection status of the cattle was determined by fecal culture. Cattle with different levels of exposure (high versus low prevalence and test negative) and disease manifestation (clinically suspect infection versus subclinical infection) were examined, as follows: (i) two paratuberculosis-negative herds; (ii) a fecal culture-confirmed, clinically suspect cases of paratuberculosis; (iii) cows from a paratuberculosis-infected herd with a high infection rate, as determined by fecal culture, but with no clinical cases at the time of sampling; (iv) cows from three paratuberculosis-infected herds known to have paratuberculosis diagnosed on the farm (low infection rate determined by fecal culture); and (v) one fecal culture-negative herd with known serologically positive cattle. Results generally showed a decreased ELISA response when absorbed rather than nonabsorbed serum from each animal was used. The results of the fecal culture confirmed clinically suspect cases, which were analyzed in relation to the amount of colonies isolated from the animals on fecal culture (0, +, ++,+++ , ++++, and above). There was a significant increase in the ELISA response for animals with heavy Mycobacterium paratuberculosis shedding ( ++++ or above), when both unabsorbed and absorbed sera were used, compared with the response in animals that were fecal culture negative or that shed M. paratuberculosis at lower levels (less than +) (P less than 0.05). The effects on sensitivity and specificity by using different cutoff points for the five groups of cattle with different levels of exposure is described, since sera were not discretely segregated into distinct groups of positive and negative samples. The specificity of the ELISA in the two fecal culture-negative herds was 100% at an ELISA cutoff of an optical density (OD) of 0.1 and above for absorbed serum. For unabsorbed serum the specificity was 62.9% at a similar cutoff value. Similarly, the specificity of the fecal culture-negative, serologically positive herd increased from 37.5 to 72.2 at an ELISA cutoff value of 0.1 to 0.2 (OD) by using absorbed versus unabsorbed serum from 75.0 to 94.4 at an ELISA cutoff value of 0.2 to 0.3 (OD).

Animals↗
PubMed1992

Comparison of subjective and objective test evaluations for use of Mycobacterium phlei-adsorbed serum in a dot-enzyme-linked immunosorbent assay for diagnosis of paratuberculosis in cattle.

Use of a dot-ELISA with serum adsorbed with Mycobacterium phlei or with nonadsorbed serum was compared. In addition, results attained using visual observation were compared with those obtained using a densitometer. Infection status of cattle was determined by results of culture of feces from a number of cattle with various degrees of exposure (low prevalence and test-negative) and disease manifestation (clinical suspect vs subclinical infection). Two paratuberculosis-negative herds, fecal culture-confirmed clinically suspect cases of paratuberculosis, and cows from 2 paratuberculosis-infected herds with diagnosis confirmed on the farm (low infection rate) were tested. Significant (P less than 0.05) increase in the dot-ELISA response was found in cattle with heavy M paratuberculosis shedding when nonadsorbed and adsorbed sera were used, compared with the response in cattle that were fecal culture-negative or were shedding M paratuberculosis at lower amounts. Paratuberculosis was diagnosed by visual determination in 29 of 44 (65.9%) of fecal culture-positive, clinically suspect cattle when nonadsorbed serum was used. Results of the visual test were negative in 85 of 93 (91.4%) of the fecal culture-negative cattle when nonadsorbed serum was used. However, when using M phlei-adsorbed serum, the sensitivity of the visual determination decreased to 34.1% (15/44), and the specificity increased to 97.8% (91/93).(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1990

Enhanced radiometric detection of Mycobacterium paratuberculosis by using filter-concentrated bovine fecal specimens.

A commercial radiometric medium, BACTEC 12B, was modified by addition of mycobactin, egg yolk suspension, and antibiotics (vancomycin, amphotericin B, and nalidixic acid). Decontaminated bovine fecal specimens were filter concentrated by using 3-microns-pore-size, 13-mm-diameter polycarbonate filters, and the entire filter was placed into the radiometric broth. Comparison of the radiometric technique with conventional methods on 603 cattle from 9 Mycobacterium paratuberculosis-infected herds found that of 75 positive specimens, the radiometric technique detected 92% while conventional methods detected 60% (P less than 0.0005). Only 3.9% of radiometric cultures were contaminated. To measure the effect of filter concentration of specimens on the detection rate, 5 cattle with minimal and 5 with moderate ileum histopathology were sampled weekly for 3 weeks. M. paratuberculosis was detected in 33.3% of nonfiltered specimens and 76.7% of filtered specimens (P less than 0.005). Detection rates were directly correlated with the severity of disease, and the advantage of specimen concentration was greatest on fecal specimens from cattle with low-grade infections. Detection times were also correlated with infection severity: 13.4 +/- 5.9 days with smear-positive specimens, 27.9 +/- 8.7 days with feces from cows with typical subclinical infections, and 38.7 +/- 3.8 days with fecal specimens from cows with low-grade infections. Use of a cocktail of vancomycin, amphotericin B, and nalidixic acid for selective suppression of nonmycobacterial contaminants was better than the commercial product PANTA (Becton Dickinson Microbiologic Systems, Towson, Md.) only when specimens contained very low numbers of M. paratuberculosis. Radiometric culture of filter-concentrated specimens generally doubled the number of positive fecal specimens detected over conventional methods, making it a useful tool for diagnosis and control of bovine paratuberculosis.

Animals↗
PubMed1981

Lack of intracellular degradation of Mycobacterium paratuberculosis by bovine macrophages infected in vitro and in vivo: light microscopic and electron microscopic observations.

Blood-derived macrophages from clinically healthy cows and cows infected with Mycobacterium paratuberculosis were cultured in vitro and inoculated with heat-killed M paratuberculosis. Five weeks after infection, acid-fast bacteria continued to be demonstrated in the macrophages. Macrophage cultures also were infected with living M paratuberculosis and were examined by electron microscopy. Four weeks after infection, intact bacteria were found in all cultures. Electron microscopic examinations of intestinal macrophages from infected cows also demonstrated intracellular intact bacteria.

Animals↗
PubMed1979

Paratuberculosis in cattle and free-living exotic deer.

Paratuberculosis was studied among dairy cows and exotic deer that shared grazing areas at Point Reyes National Seashore, California. Of the 10 dairy herds tested, 5 (50%) were infected with Mycobacterium paratuberculosis (based on results of fecal culture). Mycobacterium paratuberculosis was cultured from 9 (8.7%) of the 103 bovine fecal samples and from 4 (3.9%) of the 103 bovine rectal mucosa scapings tested. Of 89 fecal samples from 52 axis deer (Axis axis) and 37 fallow deer (Dama dama), 5 (9.6%) and 3 (8.1%), respectively, contained M paratuberculosis. Culture of intestinal necropsy samples from the same deer indicated that 3 (5.8%) of the axis deer and 2 (5.4%) of the fallow deer were infected with M paratuberculosis. The cows were tested for serum antibodies by the complement-fixation test and by radioimmunoassay. Of 95 sera tested by complement fixation, 15 (15.8%) were positive, as were 15 (14.7%) of 102 sera tested by radioimmunoassay. Culture results and serologic test results were compared on a herd basis.

Animals↗
PubMed1977

"R"-living vaccine against colibacillosis. Communication I.

After our estimation of the LD100 of enteropathogenic E. coli 0149 and 0138 (and their toxins) in rabbits and mice (intravenously and subcutaneously or intraperitoneally, respectively), rabbits and mice were vaccinated subcutaneously by the living "R" 0149 vaccine. All animals showed resistance against the LD100 of both E. coli serotypes; this state of resistance lasted 1-5 months in rabbits, and 1-3 months in mice. Sera of vaccinated rabbits showed bactericidal activity against both E. coli serotypes. The R-E-system of rabbits which were immunized by the endotoxin of "R" 0149 living vaccine, showed mobilization of immunocytes. The vaccine seems to be harmless to newborn piglets after oral vaccination; 2 colostrum deprived piglets, despite vaccination at once after birth, did not survive the big chalenge with 100 ml of broth culture of E. coli 0149 "S" (anapylactic shock). But in comparison to 1 not vaccinated control piglet, the two piglests showed only few E. coli colonies in the intestines, while the intestine of the control animal was very massively colonized by the virulent strain. As the immunizing potency of the "R" 0149 living vaccine was clearly shown in rabbits and mice, further investigations on piglets (newborns, weaning epriod, and after weaning) are needed, to state whether the value of this vaccine corresponds with the immunizing potency shown in our preliminary experiments. The "R"-vaccine seems to open some perspective in colibacillosis prevention of children and animals, and therefore it deserves our attention.

Animals↗
PubMed1977

Survival of Mycobacterium paratuberculosis in slurry.

Cattle and swine slurry and a mixture of equal parts of both, was mixed with a culture of M. paratuberculosis, 0.1 mg per ml (1 mg = 33 X 10(6) viable units) and stored under anaerobic conditions at 5 degrees and 15 degrees C. At 5 degrees C the survival time for M. paratuberculosis was 252 days in all 3 kinds of slurry, and at 15 degrees C it was 98 days in cattle slurry, 182 days in swine slurry, and 168 days in mixed slurry.

Animal Husbandry↗