Accuracy Of Polymerase Chain Reaction Research Articles

Performance and Diagnostic Accuracy of Human Papillomavirus Testing on Self-Collected Urine and Vaginal Samples in a Referral Population.

PurposeThe study aimed to evaluate the diagnostic accuracy of polymerase chain reaction–based high-risk human papillomavirus (HPV) assays on self-collected vaginal and urine samples for detection of precancerous cervical lesions in referral population.Materials and MethodsWomen referred for colposcopy following abnormal cytology, were included this study. A total of 314 matched urine, vaginal, and cervical samples were collected. All samples were tested for HPV DNA using the RealTime HR-S HPV and Anyplex II HPV 28 assays. Primary endpoints were sensitivity for cervical intraepithelial neoplasia (CIN) 2+/CIN3+ and specificity for <CIN2. Secondary endpoints were the relative accuracy of high-risk HPV (hrHPV) test results in vaginal and urine samples versus cervical samples.ResultsThe sensitivity of Realtime HR-S and Anyplex HPV assay was 93.13% (95% confidence interval [CI], 87.36 to 96.81) and 90.08% (95% CI, 83.63 to 94.61) for CIN2+ (n=130); specificity for <CIN2 was 32.69% (95% CI, 25.03 to 38.97) and 33.33% (95% CI, 26.26 to 41.00), respectively. Relative sensitivity of Realtime HR-S and Anyplex HPV tests for the detection of CIN2+ in vaginal versus cervical samples were 0.91 (95% CI, 0.90 to 1.03) and 0.87 (95% CI, 0.75 to 1.02), respectively; urine versus cervical comparisons were 0.79 (95% CI, 0.70 to 0.92) and 0.74 (95% CI, 0.61 to 0.89).ConclusionThe detection performance for hrHPV and CIN2+ on self-collected vaginal samples was comparable to that of clinician-collected cervical samples. On the other hand, HPV tests using urine were inferior to those using clinician-collected cervical samples in terms of detecting hrHPV and CIN2+.

What is the accuracy of polymerase chain reaction (PCR) blood testing for the diagnosis of invasive aspergillosis in immunocompromised people?

What is the accuracy of polymerase chain reaction (PCR) blood testing for the diagnosis of invasive aspergillosis in immunocompromised people?

Prospective multicenter comparison of urine culture with PCR on dried blood spots using 2 different extraction and PCR methods in neonates suspected for congenital cytomegalovirus infection

To evaluate the potential of dried blood spots (DBS) as a congenital cytomegalovirus (cCMV) testing specimen, the laboratory diagnostic accuracy of polymerase chain reaction (PCR) on DBS was compared to viral urine cultures from neonates suspected for cCMV. Two different extraction methods (EasyMAG, bioMérieux versus Qiagen) and 2 real-time PCR protocols (in-house versus Argene) were compared. We were able to collect both DBS and urine samples in 6 Belgian neonatal units from 276 neonates suspected for cCMV registered in CMVREG (an online neonatal registry system). Forty-eight neonates (17.4%) were positive by viral culture in urine. Laboratory diagnostic accuracy parameters of DBS-PCR were both extraction method and PCR protocol dependent. Not all DBS-CMV-PCR methods successfully detected urine-culture–positive neonates born after first-trimester seroconversions. Interestingly, however, all urine-culture–positive neonates having clinical signs of cCMV did consistently score positive.

Diagnostic value of polymerase chain reaction/acid-fast bacilli in conjunction with computed tomography-guided pleural biopsy in tuberculous pleurisy: A diagnostic accuracy study.

Patients with tuberculous pleurisy often remain undiagnosed even after blind thoracentesis and closed pleural biopsy (PB). In this study, we assessed the value of computed tomography (CT)-guided core needle biopsy of pleural lesion and evaluated the diagnostic accuracy of polymerase chain reaction (PCR)/staining for acid-fast bacilli (AFB) in suspicious tuberculous pleurisy undiagnosed in blind thoracentesis.Patients with exudative pleural effusion (PE) without specific etiology after blind thoracentesis and closed PB were enrolled in this study. PB specimens were obtained through CT-guided core needle biopsy of pleural lesion, then underwent PCR, AFB, histopathological examination, and some routine tests. Diagnostic values were evaluated through sensitivity, specificity, negative predictive value, positive predictive value, and accuracy.A total of 261 participants (TB group: 241, non-TB group: 20) were recruited. In this cohort, the sensitivity, specificity, and accuracy were 56.0%, 95.0%, and 59.0%, respectively for PCR, whereas 57.3%, 95.0%, and 60.2%, respectively for AFB. Their parallel test achieved an improved sensitivity (76.8%) and accuracy (77.8%), with a slight decrease in specificity (90.0%). In histopathological examination, granuloma was the most common finding in TB group (88.4%, 213/241), but also observed in non-TB group (10.0%, 2/20). In addition, pleural lymphocyte percentage in TB group was significantly higher than that of non-TB group (92% vs 61%, respectively; P = .003). However, no significant differences were found for other biomarkers.CT-guided core needle PB is essential for patients with exudative PE but undiagnosed after blind thoracentesis. Combining with PCR and AFB, it strongly improves the diagnosis of tuberculous pleurisy.

Quantification of cDNA on GMR biosensor array towards point-of-care gene expression analysis

Gene expression analysis at the point-of-care is important for rapid disease diagnosis, but traditional techniques are limited by multiplexing capabilities, bulky equipment, and cost. We present a gene expression analysis platform using a giant magnetoresistive (GMR) biosensor array, which allows multiplexed transcript detection and quantification through cost-effective magnetic detection. In this work, we have characterized the sensitivity, dynamic range, and quantification accuracy of Polymerase chain reaction (PCR)-amplified complementary DNA (cDNA) on the GMR for the reference gene GAPDH. A synthetic GAPDH single-stranded DNA (ssDNA) standard was used to calibrate the detection, and ssDNA dilutions were qPCR-amplified to obtain a standard curve. We demonstrate that the GMR platform provides a dynamic range of 4 orders of magnitude and a limit of detection of 1 pM and 0.1 pM respectively for 15 and 18-cycle amplified synthetic GAPDH PCR products. The quantitative results of GMR analysis of cell-line RNA were confirmed by qPCR.

Clinical usefulness and accuracy of polymerase chain reaction in the detection of bacterial meningitis agents in pediatric cerebrospinal fluid

Bacterial meningitis poses enormous healthcare challenges due to a high mortality, morbidity and sequelae. Neisseria (N.) meningitidis, Haemophilus (H.) influenzae, Streptococcus (S.) pneumoniae and S. agalactiae remain among the most prevalent infectious agents that cause bacterial meningitis in children. The objective of this study was the simultaneous detection of these pathogens in suspected cerebrospinal fluid (CSF) by using multiplex polymerase chain reaction (mPCR) and compare PCR results with standard diagnostics currently used in clinical practice. CSF specimens were obtained from 515 children (<5 years) clinically suspected of having acute bacterial meningitis. Based on bacterial culture, four isolates of salmonella sp and one Citrobacter freundii isolate were identified. The remaining 510 CSF specimens, having negative culture, were subjected to mPCR. Twenty-three (4.51%) CSF samples yielded a PCR positive signal. The pathogens identified were: S. pneumoniae (n=13), H. influenzae (n=7) and N. meningitidis (n=3). S. agalactiae was not detected. Using sequential multiplex PCR, serogrouping of S. pneumoniae revealed 3 different serotypes: serotype 19A (n=6), 19F (n=4) and serotype 23F (n=3). Only the serotype A was identified for the 3N. meningitidis isolates. Despite vaccination, S. pneumoniae remains a leading cause of pediatric invasive disease. Detecting causative organism remains the most critical aspect for management of children with suspected meningitis. PCR method is more sensitive and rapid than culture for detecting the infectious agents. Institution of PCR diagnostics is recommended for early and appropriate therapy.

A systematic review of test accuracy studies evaluating molecular micro-satellite instability testing for the detection of individuals with lynch syndrome

BackgroundA systematic review was conducted to assess the diagnostic test accuracy of polymerase chain reaction (PCR)-based microsatellite instability (MSI) testing for identifying Lynch syndrome in patients with colorectal cancer (CRC). Unlike previous reviews, this was based on assessing MSI testing against best practice for the reference standard, and included CRC populations that were unselected, age-limited or high-risk for Lynch syndrome.MethodsSingle- and two-gate diagnostic test accuracy studies, or similar, were identified, assessed for inclusion, data extracted and quality appraised by two reviewers according to a pre-specified protocol. Sensitivity of MSI testing was estimated for all included studies. Specificity, likelihood ratios and predictive values were estimated for studies that were not based on high-risk samples. Narrative synthesis was conducted.ResultsNine study samples were included. When MSI-Low results were considered to be negative, sensitivity estimates ranged from 67% (95% CI 47, 83) to 100% (95% CI 94, 100). Three studies contributed to estimates of both sensitivity and specificity, with specificity ranging from 61% (95% CI 57, 65), to 93% (95% CI 89, 95). Good sensitivity was achieved at the expense of specificity. When MSI-L was considered to be positive (effectively lowering the threshold for a positive index test result) sensitivity increased and specificity decreased. Between-study heterogeneity in both the MSI and reference standard testing, combined with the low number of studies contributing to both sensitivity and specificity estimates, precluded pooling by meta-analysis.ConclusionsMSI testing is an effective screening test for Lynch syndrome. However, there is significant uncertainty surrounding what balance of sensitivity and specificity will be achieved in clinical practice and how this relates to specific characteristics of the test (such as the panel of markers used or the thresholds used to denote a positive test).

Performance of Virological Testing for Early Infant Diagnosis: A Systematic Review.

Improved access to both maternal antiretroviral therapy and infant prophylaxis may have an impact on the performance of virological assays for diagnosis of HIV infection in infants. This systematic review was performed to assess the diagnostic accuracy of virological testing at birth as well as the performance of virological testing on dried blood spots at 6 weeks among HIV- and antiretroviral (ARV)-exposed infants. A systematic review was performed for studies published between January 1, 2009 and January 30, 2015. The search strategy included studies related to HIV, nucleic acid amplification tests, and newborns/infants and queried PubMed, Embase, the Cochrane Library, LILACS as well as several conference proceedings. Two independent reviewers collected studies and extracted data. The final analysis includes summary estimates of the sensitivities and specificities of the virological assays assessed. The GRADE approach was used to assess the overall quality of evidence and Quality Assessment of Diagnostic Accuracy Studies was used to evaluate the risk of bias in the studies. A total of 2243 records were screened with a final selection of 5 manuscripts. To assess the test characteristics of virological testing at birth, 2 studies were used to calculate a pooled sensitivity of 69.3% (95% confidence interval: 61.1 to 77.4) and a specificity of 99.9% (98.6-100%). The quality of evidence to support the sensitivity of assays at birth was low, whereas the quality of evidence for the specificity of such tests was intermediate-high. In terms of the performance of virological testing on dried blood spots for HIV- and ARV-exposed infants, 3 studies were used to calculate a pooled sensitivity of 99.4% (98.3-100.00%) and specificity of 99.6% (99.1-100.00%). The quality of evidence for both outcomes was low. The performance of polymerase chain reaction at birth demonstrates low sensitivity and high specificity, reflecting the difficulty of detecting intrapartum infections at birth and transmission dynamics. In addition, there is no evidence to suggest poor performance of virological testing on dried blood spots for ARV-exposed infants. Overall, given the very limited and low-quality evidence, further research is needed to assess the accuracy of polymerase chain reaction at different time points and in the context of more effective prevention of mother-to-child transmission interventions.

The accuracy of Influenza A (H1N1) “swine flu” laboratory testing: A systematic review of diagnostic test accuracy

Background Influenza A (H1N1) recently became pandemic, highlighting the need for a cheap and accurate diagnostic test to diagnose this virus in a clinically relevant timeframe. The current reference standard (viral culture) requires a significant degree of technical expertise, laboratory time, resources and can take up to ten days to obtain a result, during which time there could be a significant spread of infection. Objectives To obtain summary estimates of the diagnostic accuracy of currently available laboratory tests compared to viral culture for the diagnosis of Influenza A (H1N1) from respiratory samples. Inclusion criteria Types of participants Patients presenting with influenza-like illnesses and who underwent both an index and reference test specific for influenza A (H1N1). Focus of the review The diagnostic test accuracy of tests for laboratory tests for Influenza A (H1N1) Types of studies Diagnostic test accuracy studies that compared the diagnostic accuracy of any laboratory test (index test) compared to viral culture as the reference test were considered for inclusion. Search strategy Diagnostic tests are still poorly indexed by major databases; therefore the search strategy was deliberately very broad and was conducted across 14 major databases during May 2010. Methodological quality Methodological quality was determined using the QUADAS checklist. Overall the methodological quality of the studies was moderate, however all suffered from incomplete reporting. Data collection Data was collected to determine the accuracy of the index tests and completeness of the conduct and reporting. Patients were identified as being either H1N1 positive or negative on the basis of the viral culture results. The index test results were then compared for sensitivity and specificity. Data synthesis Meta analysis was not appropriate as the included studies were heterogeneous, therefore data was synthesized in narrative summary. Results The search identified 3843 studies. Of these 56 full text articles were retrieved for further analysis. Twenty nine articles were critically appraised, with 24 being excluded on the basis of incongruence with the review objective or for containing insufficient detail. The remaining five cross sectional studies examined the diagnostic accuracy of polymerase chain reaction (PCR), and were included. Two studies reported accuracy measures and when reported, the sensitivity and specificity of PCR was high. Conclusions Although unable to generate a summary estimate of the overall accuracy of PCR, the available evidence suggests that PCR using respiratory specimens appears to be highly sensitive and specific at identifying patients with H1N1. Implications for practice When reported, PCR had high test sensitivity and specificity compared with viral culture, suggesting that patients were accurately being diagnosed by this method and in a much shorter timeframe. Caution should be taken interpreting these results, as this is based on the findings from two included studies Implications for research This systematic review highlights the need for better reporting and indexing of studies that examine the diagnostic accuracy of laboratory tests in general, and H1N1 specifically. This rapidly expanding area of research needs structure and consistency in order for its findings to be useful to health care clinicians and decision makers.

Diagnostic Accuracy of PCR-Based Detection Tests for Helicobacter Pylori in Otitis Media: A Meta-Analysis

Background and objectives: Helicobacter pylori (H. Pylori) infection has serious consequences such as peptic ulcers and gastric cancer. Histologic identification of organisms remains the gold standard in the diagnosis of H. pylori. This meta-analysis reviewed the overall diagnostic accuracy of polymerase chain reaction (PCR) vs histology of H. pylori infection in the patients with otitis media with effusion (OME). Methods: Medline, Scopus and ISI web of science were systematically searched. Articles meeting the selection criteria were retrieved for the data collection and analysis. Diagnostic odds ratio (DOR) and symmetric summary receiver operating characteristic (sROC) of OME -associated .H. pylori infection was estimated for each study. The PCR techniques were compared to the histological tests as the gold standard in .diagnosing H. pylori infection. Results: We included eight relevant studies compromising 259 case of OME. The pooled sensitivity and specificity of PCR compared to the histological diagnosis of H. Pylori infection in patient with OME were 71% (95%CI: 61% - 80%, I2: 0.0%) and 81% (95%CI: 76% - 86%, I2: 59.9%), respectively. Pooled positive likelihood ratio (PLR) and negative likelihood ratio (NLR) for PCR were 3.61(95%CI: 2.34 – 5.59, I2: 44.5%) and 0.42 (95%CI: 0.31 – 0.57, I2: 0.1%), respectively. For DOR analysis, the pooled accuracy of PCR was 10.78 (95%CI: 5.95 – 19.53, I2: 0.0%) in diagnosing H. Pylori infection. Conclusions: This review showed statistically significant differences in the diagnostic accuracy between the PCR and histological tests. This meta-analysis also suggests a higher sensitivity and specificity of PCR-based molecular diagnostic of H. Pylori infection in OME patients compared to the histological tests.

HIV-associated tuberculous lymphadenitis: the importance of polymerase chain reaction (PCR) as a complementary tool for the diagnosis of tuberculosis - a study of 104 patients

Lymphadenitis is common in HIV-positive patients. Diagnosis of the infections associated with this condition is complex, particularly in the case of tuberculosis. Rapid and specific detection of Mycobacterium tuberculosis (M. tuberculosis) is fundamental in ensuring adequate treatment. In addition, frequent causes of lymphadenitis such as those associated with lymphoma and histoplasmosis, among others, must be eliminated as possible causes. To evaluate the accuracy of polymerase chain reaction as a tool for the diagnosis of lymphadenitis resulting from M. tuberculosis. In this study, a protocol was developed using the following procedures: direct microscopy using Ziehl-Neelsen staining, culture in Lowenstein-Jensen medium, histology and polymerase chain reaction. A total of 104 patients were included in the study. According to histopathology, 38 patients (36%) were found to have nonspecific chronic lymphadenitis, 27 (26%) had tuberculous lymphadenitis, 11 patients (10.5%) had lymphoma and 9 (8.7%) had histoplasmosis. When Lowenstein-Jensen culture was performed, positive tests for tuberculous lymphadenitis increased by 30%. With polymerase chain reaction, M. tuberculosis DNA was detected in 6 out of 38 samples of non-specific chronic lymphadenitis. Three of these patients were followed up, developed symptoms of tuberculosis and were cured following specific treatment. The data obtained in this study suggest that all cases of lymphadenopathies should be submitted to histopathology, Lowenstein-Jensen or Ogawa culture and polymerase chain reaction. Polymerase chain reaction may prove to be useful in providing an early and accurate detection of cases of extrapulmonary tuberculosis in HIV-positive patients with lymphadenopathies, avoiding empirical treatment and the possible development of resistant strains.

Uniform deletion junctions of complete azoospermia factor region c deletion in infertile men in Taiwan

To determine the deletion junctions of infertile men in Taiwan with azoospermia factor region c (AZFc) deletions and to evaluate the genotype/phenotype correlation. Genomic DNAs from 460 infertile men were examined. Bacterial artificial chromosome clones were used to verify the accuracy of polymerase chain reaction. Deletion junctions of the AZFc region were determined by analysis of sequence-tagged sites and gene-specific markers. Complete AZFc deletions, including BPY2, CDY1 and DAZ genes, were identified in 24 men. The proximal breakpoints were clustered between sY1197 and sY1192, and the distal breakpoints were clustered between sY1054 and sY1125 in all but one of the 24 men. The testicular phenotypes of men with complete AZFc deletion varied from oligozoospermia, to hypospermatogenesis, to maturation arrest. We identified a group of infertile men with uniform deletion junctions of AZFc in the Taiwan population. Despite this homogeneous genetic defect in the AZFc region, no clear genotype/phenotype correlation could be demonstrated.

Modifying a standard method allows simultaneous extraction of RNA and protein, enabling detection of enzymes in the rat retina with low expressions and protein levels

The aim of the study was to evaluate messenger RNA and protein expression in limited amounts of tissue with low protein content. The Chomczynski method was used for simultaneous extraction of RNA, and protein was modified in the protein isolation step. Template mass and cycling time for the complementary DNA synthesis step of real-time reverse transcription–polymerase chain reaction (RT-PCR) for analysis of catalase, copper/zinc superoxide dismutase, manganese superoxide dismutase, the catalytic subunit of glutamylcysteine ligase, glutathione peroxidase 1, and the endogenous control cyclophilin B (CypB) were optimized before PCR. Polymerase chain reaction accuracy and efficacy were demonstrated by calculating the regression ( R 2) values of the separate amplification curves. Appropriate antibodies, blocking buffers, and running conditions were established for Western blot, and protein detection and multiplex assays with CypB were performed for each target. During the extraction procedure, the protein phase was dissolved in a modified washing buffer containing 0.1% sodium dodecyl sulfate, followed by ultrafiltration. Enzyme expression on real-time RT-PCR was accomplished with high reliability and reproducibility ( R 2, 0.990-0.999), and all enzymes except for glutathione peroxidase 1 were detectable in individual retinas on Western blot. Western blot multiplexing with CypB was possible for all targets. In conclusion, connecting gene expression directly to protein levels in the individual rat retina was possible by simultaneous extraction of RNA and protein. Real-time RT-PCR and Western blot allowed accurate detection of retinal protein expressions and levels.

Quantitative analysis of survival of transplanted smooth muscle cells with real-time polymerase chain reaction

Cell transplantation improves heart function after myocardial infarction. This study investigated the survival of implanted cells in normal and infarcted myocardium. Male rat aortic smooth muscle cells were cultured. For the in vitro study, male smooth muscle cells mixed with female smooth muscle cells or male smooth muscle cells injected into a piece of female rat myocardium were used to evaluate the accuracy of quantitative real-time polymerase chain reaction to measure Y chromosomes. For the in vivo study, 2 million live or dead male smooth muscle cells were injected into normal or infarcted female myocardium. At 1 hour and 1 and 4 weeks after transplantation, hearts, lungs, and kidneys were harvested for measurement of Y chromosomes. In vitro, the accuracy of polymerase chain reaction measurement was excellent in cultured cells (r2 = 0.996) and the myocardium (r2 = 0.786). In vivo, 1 hour after 2 x 10(6) cell implantation, live cell numbers decreased to 1.0 +/- 0.2 x 10 6 and 1.1 +/- 0.3 x 10(6) , and dead cell numbers decreased to 0.9 +/- 0.2 x 10(6) and 0.8 +/- 0.2 x 10(6) in the normal and infarcted myocardium, respectively (P < .01 for all groups). Lungs and kidneys contained 8.5% and 1.5% of the implanted cells, but no cells were detected at 1 week. At 1 week, no dead smooth muscle cells were detected in the normal or infarcted myocardium. The numbers of live cells at 1 and 4 weeks were 0.48 +/- 0.06 x 10(6) and 0.27 +/- 0.07 x 10(6) in normal myocardium and 0.29 +/- 0.08 x 10(6) and 0.18 +/- 0.05 x 10(6) in infarcted myocardium. One hour after implantation, only 50% of smooth muscle cells remained in the implanted area. Some implanted cells deposited in other tissue. Implanted cell survival progressively decreased during the 4-week study.

Prediction of congenital toxoplasmosis by polymerase chain reaction analysis of amniotic fluid

To determine the accuracy of polymerase chain reaction (PCR) analysis of amniotic fluid for fetal toxoplasmosis according to clinical predictors of outcome and study centre. Prospective cohort study. Nine European centres. Women with suspected toxoplasma infection identified by prenatal screening. Logistic regression was used to examine the effects of gestational age at maternal seroconversion, treatment and timing of amniocentesis, on PCR accuracy, and to calculate the post-test probability of congenital toxoplasmosis. Infants had congenital toxoplasmosis if specific IgG persisted beyond 11.5 months. Uninfected infants had undetectable IgG in the absence of anti-toxoplasma treatment. Of 593 PCR results, 64 were positive (57 confirmed infected), and 529 were negative (23 confirmed infected). The likelihood ratio for a positive PCR result decreased significantly with trimester at seroconversion, but did not change significantly for a negative result. Weak associations were detected between sensitivity and, inversely, with specificity, and gestational age at maternal seroconversion. There was no significant association between sensitivity and centre, type or duration of treatment, or timing of amniocentesis. Specificity differed significantly between centres (P < 0.001). The change in pre- to post-test probability of infection was maximal for a positive PCR after first trimester seroconversion, affecting 1% of women tested, and a negative PCR after third trimester seroconversion, affecting half the women tested. Prediction of the risk of congenital toxoplasmosis should combine estimates of test accuracy and maternal-fetal transmission, which take account of the gestational age at which the mother seroconverted. Local laboratory standards will affect the generalisability of these results.

Simplified DNA Extraction Methods for Sexing Chick Embryos

We investigated the efficiency of DNA extraction and the accuracy of polymerase chain reaction- (PCR-) based sexing of DNA that was obtained from adult chickens and early chicken embryos. DNA samples were prepared using water-, ammonium-, and proteinase-mediated extraction. PCR-based sexing was performed by amplifying a 276-bp fragment of the 717-bp W-chromosome-specific XhoI repetitive sequence. In blood samples from adult chickens, the time required for DNA extraction using the three aforementioned methods was less than that required by the conventional method of using phenol/chloroform/isoamyl alcohol (PCI). Accurate PCR-based sexing was possible using DNA samples that were prepared using the ammonium and proteinase methods. PCR-based sexing was successful for DNA samples from a 2-day-old embryo and the small intestine, gonad, and kidney of a 7-day-old embryo that were extracted using the ammonium and proteinase methods. However, DNA from the gonads of the 7-day-old embryo could not be sexed reliably using the ammonium method. In summary, the ammonium and proteinase methods are simple and practical means of extracting DNA for PCR-based sexing, but the reliability of sexing after use of the ammonium method should be checked when DNA samples have not been used previously for sexing.

Chinese literature associated with diagnosis of Helicobacter pylori.

To synthetically analyze and probe into the diagnosis of H pylori infection, we followed the principles of evidence-based medicine. A total of 22 papers of prevalence survey and case-control studies were selected for studying about diadynamic methods. Using meta-analysis, we analyzed the different diadynamic methods of H pylori in China. Through meta-analysis, among the five diadynamic methods, the accuracy of polymerase chain reaction (PCR) was the highest (98.47%) and PCR was the most sensitive method (Sp: 99.03%). Among the five diadynamic methods, the accuracy of PCR is the highest and PCR is the most sensitive method to diagnose the infection of H pylori.

Sexing of Sheep Embryos Produced In vitro by Polymerase Chain Reaction and Sex-specific Polymorphism

The accuracy of Polymerase chain reaction (PCR) assay in sexing of sheep embryos was assessed in this study. A total of 174 ovine embryos produced in vitro at different stages of development (2, 4-8 cell stages, morula and blastocyst) were sexed. The universal primers (P1-5EZ and P2-3EZ) used in this assay amplified ZFY/ZFX-specific sequences and yielded a 445 bp fragment in both sexes. Restriction enzyme analysis of ZFY/ZFX-amplified fragments with Sac I exhibited polymorphism between sexes, three and two fragments in males and in females, respectively. For verification of accuracy, blood samples of known sex were utilized as positive controls in each test. The mean percentages of sex identification by this method at 2 cell, 4-8 cell, morula and blastocyst were 73.00±5.72, 89.77±3.79, 83.33±8.08 and 79.6±9.09, respectively with the over all male to female ratio of 1:0.87. It is concluded that the ZFY/ZFX based method is highly reliable for the sexing of sheep embryos. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 5 : 650-654)

Detection of Candida albicans in blood by PCR in a rabbit animal model of disseminated candidiasis

A model of acute disseminated Candida albicans infection in New Zealand rabbits was developed to determine the sensitivity and accuracy of polymerase chain reaction (PCR) assay compared with the lysis-centrifugation blood culture method. Primers used amplify a DNA fragment from the multicopy gene coding for the small subunit rRNA, highly conserved in fungi. The sensitivity of PCR achieved in rabbit blood samples spiked with Candida albicans was 10–50 CFU/100 μL. A nested-PCR increased the limit of detection 10-fold. The sensitivity achieved exclusively with the lysis-centrifugation method (37.5%) was higher than that obtained with PCR (25%), but lower than nested PCR (52.5%). The combination of both techniques, lysis-centrifugation and nested PCR, increased the overall sensitivity rate to 62.5%. These results have demonstrated that, globally, the nested PCR was more sensitive than both single PCR and lysis-centrifugation culture in detecting C. albicans in blood from immunecompetent rabbits with acute disseminated candidosis. PCR could be a useful complementary technique to traditional methods in the early diagnosis of candidemia.

Polymerase chain reaction determination of RhD blood type: An evaluation of accuracy

To evaluate the accuracy of polymerase chain reaction (PCR) amplification of a portion of the RhD gene by testing a large number of DNA samples derived from individuals whose RhD status was established by the standard serologic method. Seven hundred sixty-five samples were obtained from two sources: subjects taking part in studies at the University of Iowa Hospitals and Clinics (n = 107), and Centre d'Etude du Polymorphisme Humain (CEPH) families used for studies of genetic variation (n = 658). Deoxyribonucleic acid was extracted from blood samples of University of Iowa volunteers and from CEPH families by standard techniques. With few modifications, published primers, reaction and electrophoresis conditions, which yield a 1200-bp fragment in all individuals and a 600-bp fragment in RhD-positive individuals, were used. By standard serologic techniques, we identified samples from 632 RhD-positive and 133 RhD-negative individuals. Two (both from CEPH) of the 632 RhD-positive individuals were characterized as RhD-negative by PCR. Seven of the 133 RhD-negative samples were judged to be RhD-positive by PCR because of the presence of a light 600-bp band. Despite repeated attempts, no bands or DNA were identified in one RhD-negative sample. Thus, the sensitivity of RhD typing by PCR was 99.7%, the specificity 94.0%. Based on our data, it would appear that the use of PCR to establish RhD type can be introduced cautiously into current management schemes in the evaluation of RhD sensitization.