Treatment and prognosis of AIDS-related lymphoma in the era of highly active antiretroviral therapy: findings from the Swiss HIV Cohort Study

OBJECTIVE: To assess the characteristics of combination antiretroviral therapy (cART) administered concomitantly with chemotherapy and to establish prognostic determinants of patients with AIDS-related non-Hodgkin's lymphoma. METHODS: The study included 91 patients with AIDS-related non-Hodgkin's lymphoma from the Swiss HIV Cohort Study enrolled between January 1997 and October 2003, excluding lymphomas of the brain. We extracted AIDS-related non-Hodgkin's lymphoma- and HIV-specific variables at the time of lymphoma diagnosis as well as treatment changes over time from charts and from the Swiss HIV Cohort Study database. Cox regression analyses were performed to study predictors of overall and progression-free survival. RESULTS: During a median follow up of 1.6 years, 57 patients died or progressed. Thirty-five patients stopped chemotherapy prematurely (before the sixth cycle) usually due to disease progression; these patients had a shorter median survival than those who completed six or more cycles (14 versus 28 months). Interruptions of cART decreased from 35% before chemotherapy to 5% during chemotherapy. Factors associated with overall survival were CD4+ T-cell count (<100 cells/microl) (hazard ratio [HR] 2.95 [95% confidence interval (CI) 1.53-5.67], hepatitis C seropositivity (HR 2.39 [95% CI 1.01-5.67]), the international prognostic index score (HR 1.98-3.62 across categories) and Burkitt histological subtypes (HR 2.56 [95% CI 1.13-5.78]). CONCLUSIONS: Interruptions of cART were usually not induced by chemotherapy. The effect of cART interruptions on AIDS-related non-Hodgkin's lymphoma prognosis remains unclear, however, hepatitis C seropositivity emerged-as a predictor of death beyond the well-known international prognostic index score and CD4+ T-cell count.

Narrow dust jets in a diffuse gas coma: a natural product of small active regions on comets

Comets often display narrow dust jets but more diffuse gas comae when their eccentric orbits bring them into the inner solar system and sunlight sublimates the ice on the nucleus. Comets are also understood to have one or more active areas covering only a fraction of the total surface active with sublimating volatile ices. Calculations of the gas and dust distribution from a small active area on a comet’s nucleus show that as the gas moves out radially into the vacuum of space it expands tangentially, filling much of the hemisphere centered on the active region. The dust dragged by the gas remains more concentrated over the active area. This explains some puzzling appearances of comets having collimated dust jets but more diffuse gaseous atmospheres. Our test case is 67P/Churyumov–Gerasimenko, the Rosetta mission target comet, whose activity is dominated by a single area covering only 4% of its surface.

Structure and mechanism of an active lipid-linked oligosaccharide flippase

The flipping of membrane-embedded lipids containing large, polar head groups is slow and energetically unfavourable, and is therefore catalysed by flippases, the mechanisms of which are unknown. A prominent example of a flipping reaction is the translocation of lipid-linked oligosaccharides that serve as donors in N-linked protein glycosylation. In Campylobacter jejuni, this process is catalysed by the ABC transporter PglK. Here we present a mechanism of PglK-catalysed lipid-linked oligosaccharide flipping based on crystal structures in distinct states, a newly devised in vitro flipping assay, and in vivo studies. PglK can adopt inward- and outward-facing conformations in vitro, but only outward-facing states are required for flipping. While the pyrophosphate-oligosaccharide head group of lipid-linked oligosaccharides enters the translocation cavity and interacts with positively charged side chains, the lipidic polyprenyl tail binds and activates the transporter but remains exposed to the lipid bilayer during the reaction. The proposed mechanism is distinct from the classical alternating-access model applied to other transporters.

Isolation of an active gene and of two pseudogenes for mouse U7 small nuclear RNA

Three U7 RNA-related sequences were isolated from mouse genomic DNA libraries. Only one of the sequences completely matches the published mouse U7 RNA sequence, whereas the other two apparently represent pseudogenes. The matching sequence represents a functional gene, as it is expressed after microinjection into Xenopus laevis oocytes. Sequence variations of the conserved cis-acting 5' and 3' elements of U RNA genes may partly explain the low abundance of U7 RNA.

Shulamit an Ancient Love-Drama. Known as the "Song of Songs," and attributed to Solomon, King of Israel

Gershon Katz