Taking real steps in virtual nature: a randomized blinded trial

Studies show that green exercise (i.e., physical activity in the presence of nature) can provide the synergistic psychophysiological benefits of both physical exercise and nature exposure. The present study aimed to investigate the extent to which virtual green exercise may extend these benefits to people that are unable to engage in active visits to natural environments, as well as to promote enhanced exercise behavior. After watching a video validated to elicit sadness, participants either performed a treadmill walk while exposed to one of two virtual conditions, which were created using different techniques (360° video or 3D model), or walked on a treadmill while facing a blank wall (control). Quantitative and qualitative data were collected in relation to three overarching themes: "Experience," "Physical engagement" and "Psychophysiological recovery." Compared to control, greater enjoyment was found in the 3D model, while lower walking speed was found in the 360° video. No significant differences among conditions were found with respect to heart rate, perceived exertion, or changes in blood pressure and affect. The analysis of qualitative data provided further understanding on the participants' perceptions and experiences. These findings indicate that 3D model-based virtual green exercise can provide some additional benefits compared to indoor exercise, while 360° video-based virtual green exercise may result in lower physical engagement.

Exploratory study of once-daily transcranial direct current stimulation (tDCS) as a treatment for auditory hallucinations in schizophrenia

BACKGROUND

Auditory hallucinations are resistant to pharmacotherapy in about 25% of adults with schizophrenia. Treatment with noninvasive brain stimulation would provide a welcomed additional tool for the clinical management of auditory hallucinations. A recent study found a significant reduction in auditory hallucinations in people with schizophrenia after five days of twice-daily transcranial direct current stimulation (tDCS) that simultaneously targeted left dorsolateral prefrontal cortex and left temporo-parietal cortex.

HYPOTHESIS

We hypothesized that once-daily tDCS with stimulation electrodes over left frontal and temporo-parietal areas reduces auditory hallucinations in patients with schizophrenia.

METHODS

We performed a randomized, double-blind, sham-controlled study that evaluated five days of daily tDCS of the same cortical targets in 26 outpatients with schizophrenia and schizoaffective disorder with auditory hallucinations.

RESULTS

We found a significant reduction in auditory hallucinations measured by the Auditory Hallucination Rating Scale (F2,50=12.22, P<0.0001) that was not specific to the treatment group (F2,48=0.43, P=0.65). No significant change of overall schizophrenia symptom severity measured by the Positive and Negative Syndrome Scale was observed.

CONCLUSIONS

The lack of efficacy of tDCS for treatment of auditory hallucinations and the pronounced response in the sham-treated group in this study contrasts with the previous finding and demonstrates the need for further optimization and evaluation of noninvasive brain stimulation strategies. In particular, higher cumulative doses and higher treatment frequencies of tDCS together with strategies to reduce placebo responses should be investigated. Additionally, consideration of more targeted stimulation to engage specific deficits in temporal organization of brain activity in patients with auditory hallucinations may be warranted.

Taming the sphinx: Mechanisms of cellular sphingolipid homeostasis

Sphingolipids are important structural membrane components of eukaryotic cells, and potent signaling molecules. As such, their levels must be maintained to optimize cellular functions in different cellular membranes. Here, we review the current knowledge of homeostatic sphingolipid regulation. We describe recent studies in Saccharomyces cerevisiae that have provided insights into how cells sense changes in sphingolipid levels in the plasma membrane and acutely regulate sphingolipid biosynthesis by altering signaling pathways. We also discuss how cellular trafficking has emerged as an important determinant of sphingolipid homeostasis. Finally, we highlight areas where work is still needed to elucidate the mechanisms of sphingolipid regulation and the physiological functions of such regulatory networks, especially in mammalian cells. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

Gastric and duodenal bacterial colonization in HIV-infected patients without gastrointestinal symptoms

OBJECTIVE

To assess the prevalence of gastric and duodenal bacterial colonization in HIV-infected patients.

METHODS

Twenty-three consecutive outpatients at various stages of HIV infection were examined. No patient received antibiotic therapy or antisecretory drugs, and none presented with digestive symptoms. A second group consisted of 39 patients without risk factors for HIV infection referred to the gastroenterology outpatient clinic for suspected peptic ulcer disease. Gastric and duodenal juices were aspirated separately through the endoscope under direct visual control, using a sterilized double-sheathed tube. Specimens were plated quantitatively for both aerobic and anaerobic organisms. Parasitological evaluation was done on duodenal samples.

RESULTS

gastric and/or duodenal bacterial colonization was documented in 7/23 (30%) HIV+patients and in 3/39 (8%) patients in the second group (p < 0.05). No parasites were detected. All isolates were oral Gram-positive cocci or bacilli. Mean fasting gastric pH was significantly higher in HIV-infected patients with bacterial colonization than in HIV-infected patients and patients in the second group without bacterial colonization (p < 0.02). There was no correlation between the presence of bacterial colonization and CD4+ cells counts.

CONCLUSION

HIV infection may predispose to asymptomatic digestive bacterial colonization. Further studies are needed to assess the role of bacterial colonization in symptomatic patients presenting with diarrhea and/or weight loss.