Multiple genetic modifications of the erythromycin polyketide synthase to produce a library of novel "unnatural" natural products

The structures of complex polyketide natural products, such as erythromycin, are programmed by multifunctional polyketide synthases (PKSs) that contain modular arrangements of functional domains. The colinearity between the activities of modular PKS domains and structure of the polyketide product portends the generation of novel organic compounds-"unnatural" natural products-by genetic manipulation. We have engineered the erythromycin polyketide synthase genes to effect combinatorial alterations of catalytic activities in the biosynthetic pathway, generating a library of >50 macrolides that would be impractical to produce by chemical methods. The library includes examples of analogs with one, two, and three altered carbon centers of the polyketide products. The manipulation of multiple biosynthetic steps in a PKS is an important milestone toward the goal of producing large libraries of unnatural natural products for biological and pharmaceutical applications.     

Performance of Antinuclear Antibodies for Classifying Systemic Lupus Erythematosus: A Systematic Literature Review and Meta‐Regression of Diagnostic Data

Objective

To review the published literature on the performance of indirect immunofluorescence (IIF)–HEp‐2 antinuclear antibody (ANA) testing for classification of systemic lupus erythematosus (SLE).

Methods

A systematic literature search was conducted in the Medline, Embase, and Cochrane databases for articles published between January 1990 and October 2015. The research question was structured according to Population, Intervention, Comparator, Outcome (PICO) format rules, and Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) recommendations were followed where appropriate. Meta‐regression analysis for diagnostic tests was performed, using the ANA titer as independent variable, while sensitivity and specificity were dependent variables.

Results

Of 4,483 publications screened, 62 matched the eligibility criteria, and another 2 articles were identified through reference analysis. The included studies comprised 13,080 SLE patients in total, of whom 12,542 (95.9%) were reported to be IIF‐ANA positive at various titers. For ANA at titers of 1:40, 1:80, 1:160, and 1:320, meta‐regression gave sensitivity values of 98.4% (95% confidence interval [95% CI] 97.6–99.0%), 97.8% (95% CI 96.8–98.5%), 95.8% (95% CI 94.1–97.1%), and 86.0% (95% CI 77.0–91.9%), respectively. The corresponding specificities were 66.9% (95% CI 57.8–74.9%), 74.7% (95% CI 66.7–81.3%), 86.2% (95% CI 80.4–90.5%), and 96.6% (95% CI 93.9–98.1%), respectively.

Conclusion

The results of this systematic literature review and meta‐regression confirm that IIF‐ANAs have high sensitivity for SLE. ANAs at a titer of 1:80 have sufficiently high sensitivity to be considered as an entry criterion for SLE classification criteria, i.e., formally test other classification criteria for SLE only if ANAs of at least 1:80 have been found.

     

Prediction,identification and progression of histopathological liver disease activity in children with intestinal failure

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Association between Gm allotypes and asthma severity from childhood to young middle age

Immunoglobulin constant heavy G chain (IGHG) gene polymorphisms are associated with atopy and can be determined by the serum Gm allotypes. We studied whether certain polymorphisms are related to asthma severity and to the extent or intensity of allergic sensitization in asthmatic subjects followed from childhood to young middle age. Fifty-five subjects (28 males) with childhood asthma were all followed-up prospectively on six occasions from a mean age of 9 to 35 years in a study including asthma severity scoring, spirometry, skin prick, and specific serum IgE antibody testing. At the last visit, extended lung function tests and a cold air challenge were performed, and IGHG gene polymorphisms were identified by the alternative serum IgG subclass allotypes, employing ELISA and double immunodiffusion. The 19 subjects with the homozygous IGHG*bf/*bf genotype (originating from the IGHG3*b and the IGHG1*f alleles, which are in strong linkage disequilibrium), showed significantly higher asthma scores, lower airway function, and greater bronchodilator responses from childhood to adulthood, and in middle age greater airway hyperresponsiveness, compared to the subjects with the IGHG*bf/*ga or IGHG*ga/*ga genotypes. Among the subjects sensitized to animal danders, those with the IGHG*bf/*bf genotype showed the highest specific IgE levels. In conclusion, IGHG gene polymorphisms were associated with the severity and outcome of childhood asthma, and with the intensity of allergic sensitization.