The gut microbiome modulates the impact of Anaerobutyricum soehngenii supplementation on glucose homeostasis in mice.

Background: There is growing interest in the development of next-generation probiotics to prevent or treat metabolic syndrome. Previous studies suggested that Anaerobutyricum soehngenii may represent a promising probiotic candidate. A recent human study showed that while A. soehngenii supplementation is well tolerated and safe, it resulted in variable responses among individuals with a subset of the subjects significantly benefiting from the treatment. We hypothesized that gut microbiome variation is linked to the heterogeneous responses to A. soehngenii treatment observed in humans. Results: We colonized germ-free mice with fecal microbiota from human subjects that responded to A. soehngenii treatment (R65 and R55) and non-responder subjects (N96 and N40). Colonized mice were fed a high-fat diet (45% kcal from fat) to induce insulin resistance, and orally treated with either live A. soehngenii culture or heat-killed culture. We found that R65-colonized mice received a benefit in glycemic control with live A. soehngenii treatment while mice colonized with microbiota from the other donors did not. The glucose homeostasis improvements observed in R65-colonized mice were positively correlated with levels of cecal propionate, an association that was reversed in N40-colonized mice. To test whether the microbiome modulates the effects of propionate, R65- or N40-colonized mice were treated with tripropionin (TP, glycerol tripropionate), a pro-drug of propionate, or glycerol (control). TP supplementation showed a similar response pattern as that observed in live A. soehngenii treatment, suggesting that propionate may mediate the effects of A. soehngenii. We also found that TP supplementation to conventional mice reduces adiposity, improves glycemic control, and reduces plasma insulin compared to control animals supplemented with glycerol. Conclusions: These findings highlight the importance of the microbiome on glycemic control and underscore the need to better understand personal microbiome-by-therapeutic interactions to develop more effective treatment strategies.

A bioluminescent reporter for the halophilic archaeon Haloferax volcanii.

Haloarchaea have evolved to thrive in hypersaline environments. Haloferax volcanii is of particular interest due to its genetic tractability; however, few in vivo reporters exist for halophiles. Haloarchaeal proteins evolved characteristics that promote proper folding and function at high salt concentrations, but many mesophilic reporter proteins lack these characteristics. Mesophilic proteins that acquire salt-stabilizing mutations, however, can lead to proper function in haloarchaea. Using laboratory-directed evolution, we developed and demonstrated an in vivo luciferase that functions in the hypersaline cytosol of H. volcanii.

Visible light alters yeast metabolic rhythms by inhibiting respiration.

Exposure of cells to visible light in nature or in fluorescence microscopy often is considered to be relatively innocuous. However, using the yeast respiratory oscillation (YRO) as a sensitive measurement of metabolism, we find that non-UV visible light has a significant impact on yeast metabolism. Blue/green wavelengths of visible light shorten the period and dampen the amplitude of the YRO, which is an ultradian rhythm of cell metabolism and transcription. The wavelengths of light that have the greatest effect coincide with the peak absorption regions of cytochromes. Moreover, treating yeast with the electron transport inhibitor sodium azide has similar effects on the YRO as visible light. Because impairment of respiration by light would change several state variables believed to play vital roles in the YRO (e.g., oxygen tension and ATP levels), we tested oxygen's role in YRO stability and found that externally induced oxygen depletion can reset the phase of the oscillation, demonstrating that respiratory capacity plays a role in the oscillation's period and phase. Light-induced damage to the cytochromes also produces reactive oxygen species that up-regulate the oxidative stress response gene TRX2 that is involved in pathways that enable sustained growth in bright visible light. Therefore, visible light can modulate cellular rhythmicity and metabolism through unexpectedly photosensitive pathways.

The trends in prostate specific antigen usage amongst United Kingdom urologists--a questionnaire based study.

BACKGROUND: Worldwide, the use of prostate specific antigen (PSA) testing as a screen for prostate cancer is contentious. Whilst there is no National UK Screening programme, many men undergo opportunistic screening. This study investigates UK urologist's usage of PSA and the awareness surrounding the Department of Health (DoH) PSA guidelines. METHODS: Urologists were sent a questionnaire regarding PSA cut-off values. RESULTS: Of the 733 urologists eligible to participate in this study 346 returned completed questionnaires giving a response rate of 47%. The most commonly generally used age-related PSA cut-off values (36% of respondents) are--3.5 ng/ml for 50 - 59 year olds, 4.5 ng/ml for 60 - 69 year olds and 6.5 ng/ml for over 70 year olds. Two-thirds (58%, 200/346) of respondents were aware of the DoH PSA guidelines but only 20% (n = 69/346) follow these guidelines. The majority of respondents (68%, n = 234/346) used higher PSA cut-offs than recommended by the DoH. The level of compliance showed marked regional variation with a range from 7% to 44% (median 19%). In addition, it was apparent that lower PSA cut-off values were used in private practice as opposed to the National Health Service. CONCLUSION: A nationwide lack of agreement on PSA cut-off values may generate a variable standard of care both regionally and in NHS versus private practice. Generally, higher PSA cut-off values are being used than recommended by the DoH guidance.