Martin Tammemägi and colleagues evaluate which risk groups of individuals, including nonsmokers and high-risk individuals from 65 to 80 years of age, should be screened for lung cancer using computed tomography. Please see later in the article for the Editors' Summary

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Energy conservation via the pathway of dissimilatory sulfate reduction is present in a diverse group of prokaryotes, but is most comprehensively studied in Deltaproteobacteria. In this study, whole-genome microarray analyses were used to provide a model of the energy metabolism of the sulfate-reducing archaeon Archaeoglobus fulgidus, based on comparative analysis of litoautotrophic growth with H2/CO2 and thiosulfate, and heterotrophic growth on lactate with sulfate or thiosulfate. Only 72 genes were expressed differentially between the cultures utilizing sulfate or thiosulfate, whereas 269 genes were affected by a shift in energy source. We identified co-located gene cluster encoding putative lactate dehydrogenases (LDHs; lldD, dld, lldEFG), also present in sulfate-reducing bacteria. These enzymes may take part in energy conservation in A. fulgidus by specifically linking lactate oxidation with APS reduction via the Qmo complex. High transcriptional levels of Fqo confirm an important role of F420H2, as well as a menaquinone-mediated electron transport chain, during heterotrophic growth. A putative periplasmic thiosulfate reductase was identified by specific up-regulation. Also, putative genes for transport of sulfate and sulfite are discussed. We present a model for hydrogen metabolism, based on the probable bifurcation reaction of the Mvh:Hdl hydrogenase, which may inhibit the utilization of Fdred for energy conservation. Energy conservation is probably facilitated via menaquinone to multiple membrane-bound heterodisulfide reductase (Hdr) complexes and the DsrC protein—linking periplasmic hydrogenase (Vht) to the cytoplasmic reduction of sulfite. The ambiguous roles of genes corresponding to fatty acid metabolism induced during growth with H2 are discussed. Putative co-assimilation of organic acids is favored over a homologous secondary carbon fixation pathway, although both mechanisms may contribute to conserve the amount of Fdred needed during autotrophic growth with H2.

Background The NLST (National Lung Screening Trial) showed reduced lung cancer mortality in high-risk participants (smoking history of ≥30 pack-years) aged 55 to 74 years who were randomly assigned to screening with low-dose computed tomography (LDCT) versus those assigned to chest radiography. An advisory panel recently expressed reservations about Medicare coverage of LDCT screening because of concerns about performance in the Medicare-aged population, which accounted for only 25% of the NLST participants. Objective To examine the results of the NLST LDCT group by age (Medicare-eligible vs. <65 years). Design Secondary analysis of a group from a randomized trial (NCT00047385). Setting 33 U.S. screening centers. Patients 19 612 participants aged 55 to 64 years (under-65 cohort) and 7110 participants aged 65 to 74 years (65+ cohort) at randomization. Intervention 3 annual rounds of LDCT screening. Measurements Demographics, smoking and medical history, screening examination adherence and results, diagnostic follow-up procedures and complications, lung cancer diagnoses, treatment, survival, and mortality. Results The aggregate false-positive rate was higher in the 65+ cohort than in the under-65 cohort (27.7% vs. 22.0%; P < 0.001). Invasive diagnostic procedures after false-positive screening results were modestly more frequent in the older cohort (3.3% vs. 2.7%; P = 0.039). Complications from invasive procedures were low in both groups (9.8% in the under-65 cohort vs. 8.5% in the 65+ cohort). Prevalence and positive predictive value (PPV) were higher in the 65+ cohort (PPV, 4.9% vs. 3.0%). Resection rates for screen-detected cancer were similar (75.6% in the under-65 cohort vs. 73.2% in the 65+ cohort). Five-year all-cause survival was lower in the 65+ cohort (55.1% vs. 64.1%; P = 0.018). Limitation The oldest screened patient was aged 76 years. Conclusion NLST participants aged 65 years or older had a higher rate of false-positive screening results than those younger than 65 years but a higher cancer prevalence and PPV. Screen-detected cancer was treated similarly in the groups. Primary Funding Source National Institutes of Health.

Methane seepages typically harbor communities of anaerobic methane oxidizers (ANME); however, knowledge about fine-scale vertical variation of ANME in response to geochemical gradients is limited. We investigated microbial communities in sediments below a white microbial mat in the G11 pockmark at Nyegga by 16S rRNA gene tag pyrosequencing and real-time quantitative PCR. A vertical stratification of dominating ANME communities was observed at 4 cmbsf (cm below seafloor) and below in the following order: ANME-2a/b, ANME-1 and ANME-2c. The ANME-1 community was most numerous and comprised single or chains of cells with typical rectangular morphology, accounting up to 89.2% of the retrieved 16S rRNA gene sequences. Detection rates for sulfate-reducing Deltaproteobacteria possibly involved in anaerobic oxidation of methane were low throughout the core. However, a correlation in the abundance of Candidate division JS-1 with ANME-2 was observed, indicating involvement in metabolisms occurring in ANME-2-dominated horizons. The white microbial mat and shallow sediments were dominated by organisms affiliated with Sulfurovum (Epsilonproteobacteria) and Methylococcales (Gammaproteobacteria), suggesting that aerobic oxidation of sulfur and methane is taking place. In intermediate horizons, typical microbial groups associated with methane seeps were recovered. The data are discussed with respect to co-occurring microbial assemblages and interspecies interactions.