No role for quality scores in systematic reviews of diagnostic accuracy studies

BACKGROUND: There is a lack of consensus regarding the use of quality scores in diagnostic systematic reviews. The objective of this study was to use different methods of weighting items included in a quality assessment tool for diagnostic accuracy studies (QUADAS) to produce an overall quality score, and to examine the effects of incorporating these into a systematic review. METHODS: We developed five schemes for weighting QUADAS to produce quality scores. We used three methods to investigate the effects of quality scores on test performance. We used a set of 28 studies that assessed the accuracy of ultrasound for the diagnosis of vesico-ureteral reflux in children. RESULTS: The different methods of weighting individual items from the same quality assessment tool produced different quality scores. The different scoring schemes ranked different studies in different orders; this was especially evident for the intermediate quality studies. Comparing the results of studies stratified as "high" and "low" quality based on quality scores resulted in different conclusions regarding the effects of quality on estimates of diagnostic accuracy depending on the method used to produce the quality score. A similar effect was observed when quality scores were included in meta-regression analysis as continuous variables, although the differences were less apparent. CONCLUSION: Quality scores should not be incorporated into diagnostic systematic reviews. Incorporation of the results of the quality assessment into the systematic review should involve investigation of the association of individual quality items with estimates of diagnostic accuracy, rather than using a combined quality score

Plasmonic DNA: Towards Genetic Diagnosis Chips

"Plasmonics and DNA" special issueInternational audienc

<span style="font-size: 21.5pt;mso-bidi-font-size:14.5pt;font-family:"Times New Roman","serif"">Screening of <i>Bacillus thuringiensis </i>serotypes by polymerase chain reaction (PCR) for insecticidal crystal genes toxic against coffee berry borer </span>

148-154<span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">Using PCR,257 isolates of Bacillus thuringiensis(Bt) were screened for cry-type genes. Of 257 isolates/strains, 60 isolates were identified as cry7/8, 10 isolates as cry3 and 36 isolates as cry II. One specific strain of B.thuringiensis (sumiyoshiensis;T03B 001) was investigated for the presence of cry7 and cry8 genes. Genes Cry7 and cry8 were first <span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">detected in this strain using family primers prior to analysis by exclusion polymerase chain reaction (E-PCR) using specific type primers. E-PCR conducted with the above said primers led to the identification by agarose gel electrophoresis of a remaining 1.5 Kb family band indicating a potentially novel gene. This PCR product, (1.5 Kb), was purified from the gel and cloned in pGEM-T Easy vector. Twenty recombinant colonies bearing 1.5 Kb insert were identified and three randomly selected representatives of the group, clones 7,8 and 10, were sequenced and compared to all cry7<span style="font-size:13.0pt;mso-bidi-font-size:6.0pt;font-family:HiddenHorzOCR; mso-hansi-font-family:" times="" new="" roman";mso-bidi-font-family:hiddenhorzocr"=""> and cry8 sequences available from Gene Bank. Alignments with available DNA and protein sequences showed that all these clones contained a gene related to cry8Aa1. Analysis using protein sequence alignment showed that the sequence from clone 7 differed from the closest relative, known under the new nomenclature as cry 8Aal, by 44%. The crystal proteins from B.thuringiensis  sumiyoshiensis (T03B 001) was toxic to coffee berry borer larvae. </span

Transgenic cabbage (<i style="">Brassica oleracea</i> var. <i style="">capitata</i>) resistant to Diamondback moth (<i style="">Plutella xylostella</i>)

72-77A synthetic fusion gene of Bacillus thuringiensis encoding a translational fusion product of Cry1B and Cry1Ab δ-endotoxins was transferred to a tropical cabbage breeding line by Agrobacterium-mediated transformation. Selection of transformants was carried out on media containing kanamycin. Polymerase chain reaction (PCR) analysis revealed that twelve of the putative transformants contained the transgene. Insect bioassays carried out with the leaves of PCR-positive plants and neonate larvae of Diamondback moth (DBM) showed that one of the transgenic plants was completely resistant to repeated infestation by the larvae. Southern hybridization confirmed gene integration in the DBM-resistant plant. Double-antibody sandwich Enzyme-Linked Immunosorbant Assay (ELISA) analysis revealed accumulation of fusion protein up to 0.16% of total soluble protein in the leaves of the transgenic plants. Progeny (T1 generation) of the selfed transgenic plants were analyzed for the transgene segregation and insect protection. These studies clearly demonstrated the efficacy of Cry1B-Cry1Ab fusion protein to confer protection to cabbage against DBM infestation. The transgenic cabbage plants will serve as a good system to study the role of gene pyramiding in resistance management strategies intended to prevent evolution of resistance in DBM