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.     

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.     

Endolumenal colon occlusion device for transanal and transrectal surgery—a porcine feasibility study

Purpose

Although several studies have demonstrated the feasibility of transrectal natural orifice translumenal endoscopic surgery (NOTES), its clinical application has been hindered by concerns regarding potential infectious complications. The aim of this study was to evaluate the feasibility of a newly developed device for endolumenal colon occlusion (ColoShield) in an acute porcine model.

Methods

The principle of the ColoShield device is based on two balloons, with negative pressure in between. The ColoShield device and a gauze tamponade as a control group were evaluated in a non-survival study on 16 pigs. The efficacy of the occlusion system in establishing a leak-proof pneumorectum and in sealing the colon from proximal (watertight sealing) was tested by a standardized study course. Finally, the colon/rectum was explanted for macroscopic and microscopic examination.

Results

A 20-mmHg leak-proof pneumorectum over a period of 10 min could be achieved in seven of eight (87 %) animals with the ColoShield device and in none of eight (0 %) animals with gauze tamponade (p?<?0.001). In the watertight sealing test, mean intracolonic pressures of 23.5?±?18.1 (0–53) mmHg using the ColoShield device and 0?±?1.1 (0–3) mmHg using gauze tamponade (p?=?0.003) were documented proximal to the occlusion system before a leakage occurred. Macroscopic and histopathological examinations revealed no significant impairment of the colon specimen in either group.

Conclusions

ColoShield proved to be a safe and effective device for a reversible endolumenal colon occlusion. Further studies should evaluate its impact on procedural sterility during transrectal NOTES.     

Attitudes about the safety and efficacy of bariatric surgery among patients with type 2 diabetes and a body mass index of 30–40 kg/m2

BackgroundDespite increasing awareness within the medical community about the benefits of bariatric surgery for type 2 diabetes mellitus (T2DM), little is known about patients’ attitudes toward bariatric surgery as a treatment for T2DM. The objective of this study was to investigate the attitudes of individuals with T2DM and a body mass index of 30 to 40 kg/m² concerning bariatric surgery for the treatment of T2DM.MethodsPatients identified from the Pennsylvania Integrated Clinical and Administrative Research Database (PICARD) were surveyed about perceptions of the safety profile and efficacy of bariatric surgery as a treatment for obesity and T2DM and their willingness to be randomly assigned to receive a surgical procedure.ResultsA total of 130 individuals of 513 (25.3%) responded. Respondents had a median (interquartile range) age of 58.0 (range 51.0–63.0) years and self-reported body mass index of 32.9 (range 30.9–35.2) kg/m². Roughly half (66 of 130) were female. Overall, only 20.3% of respondents had positive views of bariatric surgery, with few reporting that it is a safe (14.3%) and effective (28.5%) treatment for T2DM. Less than 20% of respondents were willing to be randomly assigned to undergo a surgical procedure for the treatment of diabetes (16.1%) or obesity (17.5%).ConclusionsFew obese individuals with T2DM who responded to the survey had positive views about bariatric surgery. Patients’ concerns about the procedure’s safety profile and efficacy must be addressed to improve the acceptability of bariatric surgery as well as the feasibility of randomized, controlled trials of bariatric surgery for these individuals.