In JoVE (1)

Other Publications (3)

Articles by Georgina L. Dobek in JoVE

Other articles by Georgina L. Dobek on PubMed

Preliminary Investigation of a Humoral and Cell-mediated Immunity Ratio for Diagnosis of Paratuberculosis in Beef Cattle

Preventive Veterinary Medicine. Oct, 2009  |  Pubmed ID: 19577813

One thousand three hundred and twenty-four adult beef cattle were tested for paratuberculosis using 2 antibody enzyme-linked immunosorbent assays (ELISA), an interferon-gamma (INF-gamma) ELISA, and radiometric bacterial culture of feces from 5 populations. Two populations of cattle (n=226) had data available to calculate a ratio of humoral to cell-mediated immunity based on results from one antibody test and the INF-gamma ELISA. Latent class analysis was used to estimate accuracy of the 4 paratuberculosis assays within a Bayesian framework. Determination of test accuracy and paratuberculosis prevalence in the latent class analysis allowed for estimation of predictive value positive (PVP) functions. The estimated PVP functions were used to iteratively assign paratuberculosis status to sampled cattle. Accuracy of the immunity ratio, an antibody ELISA, and the INF-gamma ELISA were determined for multiple cutoffs based on probabilistically assigned paratuberculosis status. Area under the receiver-operating characteristic (ROC) curves (95% probability interval) were estimated as 0.78 (0.66, 0.89), 0.81 (0.68, 0.92), and 0.59 (0.47, 0.71) for the immunity ratio, antibody ELISA, and INF-gamma ELISA, respectively. The Youden index (sensitivity+specificity-1) peaked at immunity ratios of 0.5 (J=0.48) and 1.0 (J=0.46). Sensitivity and specificity (95% probability interval) at an immunity ratio cutoff of 0.5 were 0.65 (0.44, 0.85) and 0.83 (0.78, 0.88), respectively. Sensitivity and specificity (95% probability interval) at the 1.0 cutoff were 0.55 (0.33, 0.77) and 0.91 (0.87, 0.95), respectively. An immunity ratio could be used to diagnosis paratuberculosis in beef cattle but requires further investigation.

Diagnostic Accuracy of Methods for Detecting Anaplasma Marginale Infection in Lactating Dairy Cattle of Puerto Rico

Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc. Mar, 2010  |  Pubmed ID: 20224076

Bovine anaplasmosis (BA) is a hemoparasitic disease of great importance in cattle within the tropical and subtropical regions of the world. Control programs for BA require accurate diagnostic assays but validation can be challenging because the true disease status of all animals is frequently not known with certainty. The objective of this study was to estimate the accuracy of assays for detection of Anaplasma marginale infection in lactating dairy cattle of Puerto Rico using Bayesian methods without a perfect reference test. There were 2,331 cattle with complete diagnostic results sampled from 79 herds, and the prevalence of BA was estimated as 22% (95% probability interval [PI]: 19-25%). The sensitivity (Se) and specificity (Sp) of a major surface protein 5 competitive enzyme-linked immunosorbent assay (MSP-5 cELISA) were estimated as 99% (95% PI: 96-100%) and 89% (95% PI: 87-92%), respectively. The Se and Sp of a quantitative polymerase chain reaction (qPCR) were 67% (95% PI: 60-74%) and 99% (95% PI: 99-100%). The Se and Sp of a card agglutination test were 34% (95% PI: 29-39%) and 99% (95% PI: 99-100%). Area under the receiver-operating characteristic curve for the MSP-5 cELISA was 0.748 (95% PI: 0.71-0.79). The MSP-5 cELISA appears to be the test of choice for screening cattle for subclinical BA based on the high estimated Se, rapidity of results, relative low cost, and ease of standardization.

Analysis of Promoters and Expression-targeted Gene Therapy Optimization Based on Doubling Time and Transfectability

FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology. Sep, 2011  |  Pubmed ID: 21602450

Genes under the control of the cyclooxygenase-2 (Cox-2), human epidermal growth factor receptor 2 (Her-2), and survivin promoters were constructed and delivered to murine and human carcinoma cells. It was found that (P)Cox-2-driven reporter expression was strong and correlated well with endogenous Cox-2 levels, while (P)Her-2 and (P)survivin yielded poor results, consistent with the three distinct expression mechanisms used by cancer cells to overexpress the endogenous versions of the selected genes. The (P)Cox-2 was then used to drive the expression of caspase genes both in vitro and in vivo to bring about targeted apoptosis of carcinoma cells successfully. The results led to the following conclusions. 1) When selecting a promoter/enhancer for expression-targeted gene delivery, it is not enough to perform a microarray on some tumor tissue and select the control element associated with the greatest amount of gene up-regulation vs. normal controls. The mechanism of expression for the particular gene should be taken into account to prevent lengthy and costly research trials. 2) When overexpression is due to activator binding, a predictive model based on endogenous gene expression levels, overall cell transfectability, and cell doubling rates can be used to predict expression-targeted gene delivery outcomes with significant accuracy.

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