Budesonide Versus Acetazolamide for Prevention of Acute Mountain Sickness

Background

Inhaled budesonide has been suggested as a novel prevention for acute mountain sickness. However, efficacy has not been compared with the standard acute mountain sickness prevention medication acetazolamide.

Cell Labeling with Magneto-Endosymbionts and the Dissection of the Subcellular Location,Fate, and Host Cell Interactions

Purpose

The purposes of this study are to characterize magneto-endosymbiont (ME) labeling of mammalian cells and to discern the subcellular fate of these living contrast agents. MEs are novel magnetic resonance imaging (MRI) contrast agents that are being used for cell tracking studies. Understanding the fate of MEs in host cells is valuable for designing in vivo cell tracking experiments.

Procedures

The ME’s surface epitopes, contrast-producing paramagnetic magnetosomal iron, and genome were studied using immunocytochemistry (ICC), Fe and MRI contrast measurements, and quantitative polymerase chain reaction (qPCR), respectively. These assays, coupled with other common assays, enabled validation of ME cell labeling and dissection of ME subcellular processing.

Results

The assays mentioned above provide qualitative and quantitative assessments of cell labeling, the subcellular localization and the fate of MEs. ICC results, with an ME-specific antibody, qualitatively shows homogenous labeling with MEs. The ferrozine assay shows that MEs have an average of 7 fg Fe/ME, ～30 % of which contributes to MRI contrast and ME-labeled MDA-MB-231 (MDA-231) cells generally have 2.4 pg Fe/cell, implying ～350 MEs/cell. Adjusting the concentration of Fe in the ME growth media reduces the concentration of non-MRI contrast-producing Fe. Results from the qPCR assay, which quantifies ME genomes in labeled cells, shows that processing of MEs begins within 24 h in MDA-231 cells. ICC results suggest this intracellular digestion of MEs occurs by the lysosomal degradation pathway. MEs coated with listeriolysin O (LLO) are able to escape the primary phagosome, but subsequently co-localize with LC3, an autophagy-associated molecule, and are processed for digestion. In embryos, where autophagy is transiently suppressed, MEs show an increased capacity for survival and even replication. Finally, transmission electron microscopy (TEM) of ME-labeled MDA-231 cells confirms that the magnetosomes (the MRI contrast-producing particles) remain intact and enable in vivo cell tracking.

Conclusions

MEs are used to label mammalian cells for the purpose of cell tracking in vivo, with MRI. Various assays described herein (ICC, ferrozine, and qPCR) allow qualitative and quantitative assessments of labeling efficiency and provide a detailed understanding of subcellular processing of MEs. In some cell types, MEs are digested, but the MRI-producing particles remain. Coating with LLO allows MEs to escape the primary phagosome, enhances retention slightly, and confirms that MEs are ultimately processed by autophagy. Numerous intracellular bacteria and all endosymbiotically derived organelles have evolved molecular mechanisms to avoid intracellular clearance, and identification of the specific processes involved in ME clearance provides a framework on which to develop MEs with enhanced retention in mammalian cells.

     

National Prevalence of Lifestyle Counseling or Referral Among African-Americans and Whites with Diabetes

Background  Modifiable risk factors such as diet and physical activity contribute to racial disparities among patients with diabetes. Despite this, little is known about how frequently physicians provide counseling or referral to address these risk factors, or whether such rates differ by patient race. Methods  We analyzed cross-sectional data from the 2002–2004 National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey. We used logistic regression to investigate the relationship between counseling/referral for nutrition or exercise and patient factors, provider factors, and geographic location, with a focus on whether counseling rates were independently associated with patient race. Results  Overall, counseling/referral for nutrition occurred in 36% of patient visits and counseling/referral for exercise occurred in 18% of patient visits. After adjusting for patient, physician, and practice characteristics, there was no statistically significant association between race and counseling/referral for nutrition (odds ratio for African-Americans compared to whites [OR] 1.00, 95% confidence intervals [CI] 0.71–1.41) or for exercise (OR 0.74, CI 0.49–1.11). Significant predictors of counseling/referral for both lifestyle interventions included younger patient age, private insurance, and treatment by a primary care provider. Conclusions  Rates of lifestyle modification counseling/referral were similarly low among African-Americans and whites in this national study. Our results highlight a need for interventions to enhance physician counseling for patients with diabetes, particularly those at high-risk for diabetes-associated morbidity and mortality, such as racial/ethnic minorities.     

Anesthesia and the developing brain: a way forward for clinical research

It is now well established that many general anesthetics have a variety of effects on the developing brain in animal models. In contrast, human cohort studies show mixed evidence for any association between neurobehavioural outcome and anesthesia exposure in early childhood. In spite of large volumes of research, it remains very unclear if the animal studies have any clinical relevance; or indeed how, or if, clinical practice needs to be altered. Answering these questions is of great importance given the huge numbers of young children exposed to general anesthetics. A recent meeting in Genoa brought together researchers and clinicians to map a path forward for future clinical studies. This paper describes these discussions and conclusions. It was agreed that there is a need for large, detailed, prospective, observational studies, and for carefully designed trials. It may be impossible to design or conduct a single study to completely exclude the possibility that anesthetics can, under certain circumstances, produce long‐term neurobehavioural changes in humans; however , observational studies will improve our understanding of which children are at greatest risk, and may also suggest potential underlying etiologies, and clinical trials will provide the strongest evidence to test the effectiveness of different strategies or anesthetic regimens with respect to better neurobehavioral outcome.