Inactivation of a single gene enables microaerobic growth of the obligate anaerobe Bacteroides fragilis

Bacteroides fragilis can replicate in atmospheres containing ≤0.05% oxygen, but higher concentrations arrest growth by an unknown mechanism. Here we show that inactivation of a single gene, oxe (i.e., oxygen enabled) in B. fragilis allows for growth in concentrations as high as 2% oxygen while increasing the tolerance of this organism to room air. Known components of the oxidative stress response including the ahpC, kat, batA-E, and tpx genes were not individually important for microaerobic growth. However, a Δoxe strain scavenged H(2)O(2) at a faster rate than WT, indicating that reactive oxygen species may play a critical role in limiting growth of this organism to low-oxygen environments. Clinical isolates of B. fragilis displayed a greater capacity for growth under microaerobic conditions than fecal isolates, with some encoding polymorphisms in oxe. Additionally, isolation of oxygen-enabled mutants of Bacteroides thetaiotaomicron suggests that Oxe may mediate growth arrest of other anaerobes in oxygenated environments.     

Quantitative computed tomography and cranial burr holes: a model to evaluate the quality of cranial reconstruction in humans

Current methods to evaluate the biologic development of bone grafts in human beings do not quantify results accurately. Cranial burr holes are standardized critical bone defects, and the differences between bone powder and bone grafts have been determined in numerous experimental studies. This study evaluated quantitative computed tomography (QCT) as a method to objectively measure cranial bone density after cranial reconstruction with autografts. In each of 8 patients, 2 of 4 surgical burr holes were reconstructed with autogenous wet bone powder collected during skull trephination, and the other 2 holes, with a circular cortical bone fragment removed from the inner table of the cranial bone flap. After 12 months, the reconstructed areas and a sample of normal bone were studied using three-dimensional QCT; bone density was measured in Hounsfield units (HU). Mean (SD) bone density was 1535.89 (141) HU for normal bone (P < 0.0001), 964 (176) HU for bone fragments, and 453 (241) HU for bone powder (P < 0.001). As expected, the density of the bone fragment graft was consistently greater than that of bone powder. Results confirm the accuracy and reproducibility of QCT, already demonstrated for bone in other locations, and suggest that it is an adequate tool to evaluate cranial reconstructions. The combination of QCT and cranial burr holes is an excellent model to accurately measure the quality of new bone in cranial reconstructions and also seems to be an appropriate choice of experimental model to clinically test any cranial bone or bone substitute reconstruction.     

A positive 2-item Patient Health Questionnaire depression screen among hospitalized heart failure patients is associated with elevated 12-month mortality

BackgroundGiven the association of depression with poorer cardiac outcomes, an American Heart Association Science Advisory has advocated routine screening of cardiac patients for depression using the 2-item Patient Health Questionnaire (PHQ-2) “at a minimum.” However, the prognostic value of the PHQ-2 among HF patients is unknown.Methods and ResultsWe screened hospitalized HF patients (ejection fraction [EF] <40%) that staff suspected may be depressed with the PHQ-2, and then determined vital status at up to 12-months follow-up. At baseline, PHQ-2 depression screen–positive patients (PHQ-2+; n = 371), compared with PHQ-2 screen–negative patients (PHQ-2?; n = 100), were younger (65 vs 70 years) and more likely to report New York Heart Association (NYHA) functional class III/IV than class II symptoms (67% vs. 39%) and lower levels of physical and mental health–related quality of life (all P ≤ .002); they were similar in other characteristics (65% male, 26% mean EF). At 12 months, 20% of PHQ-2+ versus 8% of PHQ-2? patients had died (P = .007) and PHQ-2 status remained associated with both all-cause (hazard ratio [HR] 3.1, 95% confidence interval [CI] 1.4–6.7; P = .003) and cardiovascular (HR 2.7, 95% CI 1.1–6.6; P = .03) mortality even after adjustment for age, gender, EF, NYHA functional class, and a variety of other covariates.ConclusionsAmong hospitalized HF patients, a positive PHQ-2 depression screen is associated with an elevated 12-month mortality risk.     

Corticosteroid Therapy, Vitamin D Status, and Inflammatory Cytokine Profile in the HIV-Tuberculosis Immune Reconstitution Inflammatory Syndrome

Background.?Tuberculosis-immune reconstitution inflammatory syndrome (TB-IRIS) in patients coinfected with human immunodeficiency virus (HIV) and tuberculosis starting antiretroviral therapy (ART) is associated with hypercytokinemia. As adjunctive corticosteroid therapy and vitamin D have immunomodulatory properties, we investigated the relationship between cytokine/chemokine profiles, corticosteroid use, and vitamin D deficiency in TB-IRIS patients. Methods.?Plasma from 39 TB-IRIS and 42 non-IRIS patients was collected during a prospective study of HIV-associated tuberculosis patients starting ART. In total, 26% of patients received corticosteroid (CTC) therapy pre-ART for severe tuberculosis. Concentrations of total 25-hydroxyvitamin D (25(OH)D) and 14 cytokines/chemokines were determined at ART initiation and 2 weeks later. Results.?Patients prescribed concurrent CTC had lower interferon γ (IFN-γ), IP-10, tumor necrosis factor (TNF), interleukin (IL)-6, IL-8, IL-10, IL-12p40, and IL-18 pre-ART (P?≤?.02). TB-IRIS presented at 12 days (median) of ART, irrespective of CTC use. In patients who developed TB-IRIS (not on CTC) IL-6, IL-8, IL-12p40, IL-18, IP-10, and TNF increased during 2 weeks (P?≤?.04) of ART. Vitamin D deficiency (total 25(OH)D <75?nmol/L) was highly prevalent (89%) at baseline. Although vitamin D deficiency at either baseline or 2 weeks was not associated with TB-IRIS, in those not on CTC the median 25(OH)D decreased during 2 weeks (P?=?.004) of ART. Severe vitamin D deficiency (total 25(OH)D <25?nmol/L) was associated with higher baseline TNF, IL-6, and IL-8 irrespective of IRIS status. Conclusions.?CTC modifies the inflammatory profile of those who develop TB-IRIS. The association between severe vitamin D deficiency and elevated proinflammatory cytokines support a study of vitamin D supplementation in HIV-TB co-infected patients starting ART.