Quantitative evaluation of recall and precision of CAT Crawler,a search engine specialized on retrieval of Critically Appraised Topics

Background

Critically Appraised Topics (CATs) are a useful tool that helps physicians to make clinical decisions as the healthcare moves towards the practice of Evidence-Based Medicine (EBM). The fast growing World Wide Web has provided a place for physicians to share their appraised topics online, but an increasing amount of time is needed to find a particular topic within such a rich repository.

Methods

A web-based application, namely the CAT Crawler, was developed by Singapore's Bioinformatics Institute to allow physicians to adequately access available appraised topics on the Internet. A meta-search engine, as the core component of the application, finds relevant topics following keyword input. The primary objective of the work presented here is to evaluate the quantity and quality of search results obtained from the meta-search engine of the CAT Crawler by comparing them with those obtained from two individual CAT search engines. From the CAT libraries at these two sites, all possible keywords were extracted using a keyword extractor. Of those common to both libraries, ten were randomly chosen for evaluation. All ten were submitted to the two search engines individually, and through the meta-search engine of the CAT Crawler. Search results were evaluated for relevance both by medical amateurs and professionals, and the respective recall and precision were calculated.

Results

While achieving an identical recall, the meta-search engine showed a precision of 77.26% (±14.45) compared to the individual search engines' 52.65% (±12.0) (p < 0.001).

Conclusion

The results demonstrate the validity of the CAT Crawler meta-search engine approach. The improved precision due to inherent filters underlines the practical usefulness of this tool for clinicians.

     

Clara cell secretory protein deficiency alters clara cell secretory apparatus and the protein composition of airway lining fluid

Clara cells represent the predominant secretory cell within distal conducting airways of mammals and exhibit functional alterations with chronic lung disease. We previously demonstrated that Clara cell secretory protein (CCSP) deficiency results in enhanced susceptibility to environmental agents. The present study was undertaken to define changes in Clara cell secretory function associated with CCSP deficiency in knockout mice. Comparative morphometry of Clara cell ultrastructure revealed dramatic alterations in secretory apparatus between wild-type (WT) and CCSP knockout (CCSP-/-) mice. Secretory granules, which occupy greater than 2% of Clara cell cytoplasmic volume in WT mice, were completely absent among Clara cells of CCSP-/- mice. Moreover, Clara cells of CCSP-/- mice exhibited a > 95% reduction in rough endoplasmic reticulum and alterations to Golgi apparatus, relative to WT controls. Ultrastructural perturbations to Clara cells were associated with altered protein composition of airway lining fluid as revealed by two-dimensional gel analysis of bronchoalveolar lavage proteins, but were not associated with altered abundance or secretion of CC26, another Clara cell secretory protein. We conclude that CCSP is required for the appearance of Clara cell secretory granules and that functional changes to Clara cells that result from CCSP deficiency lead to alterations in the composition of epithelial lining fluid.     

No association between the Pro197Leu polymorphism in the glutathione peroxidase (GPX1) gene and schizophrenia

OBJECTIVE: Oxidative stress such as free radical-mediated neuronal dysfunction may be involved in the pathophysiology of schizophrenia. The human glutathione peroxidase (GPX1) is a selenium-dependent enzyme, which plays an important role in the detoxification of free radicals. We therefore hypothesized that the GPX1 gene, which is located on chromosome 3p21.3, may be involved in the pathophysiology of schizophrenia. The aim of this study is to examine whether a potentially functional polymorphism, a proline (Pro) to leucine (Leu) substitution at codon 197 (Pro197Leu) of the human GPX1 gene, is associated with susceptibility to schizophrenia. METHODS: We genotyped the Pro197Leu polymorphism in a total of 113 nuclear families that had a proband with schizophrenia. Genetic association was tested using the transmission disequilibrium test (TDT), the sib transmission disequilibrium test (STDT), and the family-based association test (FBAT). RESULTS: The minor allele (Leu) frequency was calculated to be 0.282. We could not find significant transmission disequilibrium of the alleles for the Pro197Leu polymorphism in the GPX1 gene in association with the presence of schizophrenia in our family sample (TDT, chi2=0.03, degrees of freedom=1, P=0.86; combined TDT-STDT, Z'=-0.052, P=0.47; FBAT, Z=0.000, P=1.000). CONCLUSION: The results of this study suggest that the GPX1 polymorphism is unlikely to be associated with susceptibility to schizophrenia.     

Hepatic dysfunction in Alstr?m disease.

Alstr?m disease is a rare disorder; less than 20 cases have been reported. An 11-year-old girl is described with this condition. She has pigmentary retinopathy, sensory neural deafness, obesity, Type II diabetes mellitus, hyperlipidemia, and acanthosis nigricans. However, in addition she developed hepatic dysfunction, pathologically similar to chronic active hepatitis. This may be a further, previously undescribed systemic manifestation of Alstr?m disease.     

Influence of volume dilution, lactate, phosphate, and calcium on mitochondrial functions.

Oxidative phosphorylation of isolated canine myocardial mitochondria has been evaluated after exposure to different concentrations of phosphate (5--50 mM), lactate ion in excess (5--40 mM, pH 7.4), calcium (50--270 nmol/mg protein), to lactic acidosis (pH 6.3), and to mitochondrial protein dilution (in vitro volume expansion) for 10 min to 8 h. The influence of phosphate and lactate ion addition, lactic acidosis, and in vitro volume expansion on mitochondrial function were studied in the isolation medium (0.18 M KCl, 0.5% BSA (bovine serum albumin), with or without Tris-EDTA, pH 7.4) prior to evaluation of mitochondrial function in the assay medium (0.25 M sucrose, 10 mM Tris-HCl, and 10 mM inorganic phosphate, pH 7.4). The effect of calcium addition was assessed in the assay medium. The results of these studies demonstrate that each of these interventions detrimentally alters mitochondrial oxidative phosphorylative ability. The most severe mitochondrial functional impairment resulted from phosphate or calcium addition. The detrimental effect of phosphate and in vitro volume expansion was partially corrected by the addition of cytochrome c.     

Categorization of clinical isolates of Helicobacter pylori on the basis of restriction digest analyses of polymerase chain reaction-amplified ureC genes.

Restriction endonuclease analyses of a 1.1-kb polymerase chain reaction-amplified portion of the ureC gene from Helicobacter pylori were used to group or to differentiate 21 clinical isolates. Isolates were placed into 4 groups after HindIII digestion alone, and placement was expanded into 15 groups after isolates were digested with AluI and PvuI.