Exonuclease VII repairs quinolone-induced damage by resolving DNA gyrase cleavage complexes.

The widely used quinolone antibiotics act by trapping prokaryotic type IIA topoisomerases, resulting in irreversible topoisomerase cleavage complexes (TOPcc). Whereas the excision repair pathways of TOPcc in eukaryotes have been extensively studied, it is not known whether equivalent repair pathways for prokaryotic TOPcc exist. By combining genetic, biochemical, and molecular biology approaches, we demonstrate that exonuclease VII (ExoVII) excises quinolone-induced trapped DNA gyrase, an essential prokaryotic type IIA topoisomerase.

Mitochondrial tyrosyl-DNA phosphodiesterase 2 and its TDP2 short isoform.

Tyrosyl-DNA phosphodiesterase 2 (TDP2) repairs abortive topoisomerase II cleavage complexes. Here, we identify a novel short isoform of TDP2 (TDP2) expressed from an alternative transcription start site. TDP2 contains a mitochondrial targeting sequence, contributing to its enrichment in the mitochondria and cytosol, while full-length TDP2 contains a nuclear localization signal and the ubiquitin-associated domain in the N-terminus.

The association of serum lactate dehydrogenase level with selected opportunistic infections and HIV progression.

Background: The purpose of this study was to determine the association of serum lactate dehydrogenase (LDH) levels with certain opportunistic infection and to determine an association between LDH levels and CD4+ lymphocyte counts.

Method: We studied 352 patients retrospectively with HIV infection and one of the following infections: histoplasmosis; toxoplasmosis; tuberculosis (pulmonary and disseminated); bacterial pneumonia; Pneumocystis carinii pneumonia. Demographic and clinical data were obtained from the Adult Spectrum of Diseases (ASD) database in New Orleans.

Serum LDH level as a clue to the diagnosis of histoplasmosis.

The purpose of this study was to determine whether serum lactate dehydrogenase (LDH) level could be used as an adjunct clinical marker to differentiate between histoplasmosis and Pneumocystis carinii pneumonia (PCP). In a retrospective, case-controlled study, 30 patients with a diagnosis of histoplasmosis (all but 1 with disseminated disease) were compared with 120 patients with PCP (33 patients with definitive PCP, 87 with presumed PCP). Groups were matched for CD4+ lymphocyte counts, sex, and year of diagnosis.