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Human adult muscle-type acetylcholine receptors are heteropentameric ion channels formed from two α-subunits, and one each of the β-, δ-, and ε-subunits. To form functional channels, the subunits must assemble with one another in a precise stoichiometry and arrangement. Despite being different, the four subunits share a common ancestor that is presumed to have formed homopentamers. The extent to which the properties of the modern-day receptor result from its subunit complexity is unknown. Here, we discover that a reconstructed ancestral muscle-type β-subunit can form homopentameric ion channels. These homopentamers open spontaneously and display single-channel hallmarks of muscle-type acetylcholine receptor activity. Our findings attest to the homopentameric origin of the muscle-type acetylcholine receptor, and demonstrate that signature features of its function are both independent of agonist and do not necessitate the complex heteropentameric architecture of the modern-day protein.

An abstract of the article "Clinic-Based Support to Help Overweight Patients With Type 2 Diabetes Increase Physical Activity and Lose Weight," by J. G. Christian and colleagues is presented.

Parasites of the Leishmania genus infect and survive within macrophages by inhibiting several microbicidal molecules, such as nitric oxide and pro-inflammatory cytokines. In this context, various species of Leishmania have been reported to inhibit or reduce the production of IL-1β both in vitro and in vivo. However, the mechanism whereby Leishmania parasites are able to affect IL-1β production and secretion by macrophages is still not fully understood. Dependent on the stimulus at hand, the maturation of IL-1β is facilitated by different inflammasome complexes. The NLRP3 inflammasome has been shown to be of pivotal importance in the detection of danger molecules such as inorganic crystals like asbestos, silica and malarial hemozoin, (HZ) as well as infectious agents. In the present work, we investigated whether Leishmania parasites modulate NLRP3 inflammasome activation. Using PMA-differentiated THP-1 cells, we demonstrate that Leishmania infection effectively inhibits macrophage IL-1β production upon stimulation. In this context, the expression and activity of the metalloprotease GP63 - a critical virulence factor expressed by all infectious Leishmania species - is a prerequisite for a Leishmania-mediated reduction of IL-1β secretion. Accordingly, L. mexicana, purified GP63 and GP63-containing exosomes, caused the inhibition of macrophage IL-1β production. Leishmania-dependent suppression of IL-1β secretion is accompanied by an inhibition of reactive oxygen species (ROS) production that has previously been shown to be associated with NLRP3 inflammasome activation. The observed loss of ROS production was due to an impaired PKC-mediated protein phosphorylation. Furthermore, ROS-independent inflammasome activation was inhibited, possibly due to an observed GP63-dependent cleavage of inflammasome and inflammasome-related proteins. Collectively for the first time, we herein provide evidence that the protozoan parasite Leishmania, through its surface metalloprotease GP63, can significantly inhibit NLRP3 inflammasome function and IL-1β production.

The protease GP63 is an important virulence factor of Leishmania parasites. We previously showed that GP63 reaches the perinuclear area of host macrophages and that it directly modifies nuclear translocation of the transcription factors NF-κB and AP-1. Here we describe for the first time, using molecular biology and in-depth proteomic analyses, that GP63 alters the host macrophage nuclear envelope, and impacts on nuclear processes. Our results suggest that GP63 does not appear to use a classical nuclear localization signal common between Leishmania species for import, but degrades nucleoporins, and is responsible for nuclear transport alterations. In the nucleoplasm, GP63 activity accounts for the degradation and mislocalization of proteins involved amongst others in gene expression and in translation. Collectively, our data indicates that Leishmania infection strongly affects nuclear physiology, suggesting that targeting of nuclear physiology may be a strategy beneficial for virulent Leishmania parasites.

Chlamydiae are obligate intracellular bacteria that propagate in a cytosolic vacuole. Recent work has shown that growth of Chlamydia induces the fragmentation of the Golgi apparatus (GA) into ministacks, which facilitates the acquisition of host lipids into the growing inclusion. GA fragmentation results from infection-associated cleavage of the integral GA protein, golgin-84. Golgin-84-cleavage, GA fragmentation and growth of Chlamydia trachomatis can be blocked by the peptide inhibitor WEHD-fmk. Here we identify the bacterial protease chlamydial protease-like activity factor (CPAF) as the factor mediating cleavage of golgin-84 and as the target of WEHD-fmk-inhibition. WEHD-fmk blocked cleavage of golgin-84 as well as cleavage of known CPAF targets during infection with C. trachomatis and C. pneumoniae. The same effect was seen when active CPAF was expressed in non-infected cells and in a cell-free system. Ectopic expression of active CPAF in non-infected cells was sufficient for GA fragmentation. GA fragmentation required the small GTPases Rab6 and Rab11 downstream of CPAF-activity. These results define CPAF as the first protein that is essential for replication of Chlamydia. We suggest that this role makes CPAF a potential anti-infective therapeutic target.

Background: Physician counseling can help patients make substantial changes in diet and physical activity behaviors that can result in weight loss and a reduction in metabolic risk factors. Unfortunately, time constraints and a lack of training often make it difficult for physicians to provide effective counseling. The objective in this study was to test the effect of a computerized support tool to enhance brief physician-delivered health lifestyle counseling to patients with increased metabolic risk factors during two usual care visits., Design/setting/participants: This is a prospective controlled trial of a 12-month intervention conducted at two large community health centers serving mostly Hispanic patients. Participants (n = 279) had a body mass index (calculated as kg/m²) ≥ 25 and at least two components of the metabolic syndrome., Intervention: In the intervention group, a computer program was used to help patients set tailored self-management goals for weight loss, nutrition, and physical activity. Goals were then reviewed and reinforced at clinic visits with participants' physicians at baseline and again at 6 months. The control group received care as usual. Data were collected between July 2007 and August 2008., Main Outcome Measures: Change in body weight was the primary outcome. Secondary measures included changes in blood glucose, blood cholesterol, blood pressure, physical activity, and energy intake., Results: Significantly more patients in the intervention group lost ≥ 5% of their body weight at 12 months than controls (26.3% vs 8.5%; odds ratio = 3.86; P < 0.01). Loss of > 5% of total body weight was associated with improvements in cardiovascular risk factors, including low-density lipoprotein cholesterol (-14.0 vs -4.1 mg/dL; P = 0.04)., Conclusions: A brief computer-based intervention designed to increase the dialogue between patients and clinicians about behavioral goals can lead to increased 12-month weight loss., (Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.)

The phylum Chlamydiae consists exclusively of obligate intracellular bacteria. Some of them are formidable pathogens of humans, while others occur as symbionts of amoebae. These genetically intractable bacteria possess a developmental cycle consisting of replicative reticulate bodies and infectious elementary bodies, which are believed to be physiologically inactive. Confocal Raman microspectroscopy was applied to differentiate between reticulate bodies and elementary bodies of Protochlamydia amoebophila and to demonstrate in situ the labelling of this amoeba symbiont after addition of isotope-labelled phenylalanine. Unexpectedly, uptake of this amino acid was also observed for both developmental stages for up to 3 weeks, if incubated extracellularly with labelled phenylalanine, and P. amoebophila remained infective during this period. Furthermore, P. amoebophila energizes its membrane and performs protein synthesis outside of its host. Importantly, amino acid uptake and protein synthesis after extended extracellular incubation could also be demonstrated for the human pathogen Chlamydia trachomatis, which synthesizes stress-related proteins under these conditions as shown by 2-D gel electrophoresis and MALDI-TOF/TOF mass spectrometry. These findings change our perception of chlamydial biology and reveal that host-free analyses possess a previously not recognized potential for direct experimental access to these elusive microorganisms.

Chlamydiae replicate in a vacuole within epithelial cells and commonly induce cell damage and a deleterious inflammatory response of unknown molecular pathogenesis. The chlamydial protease-like activity factor (CPAF) translocates from the vacuole to the cytosol, where it cleaves several cellular proteins. CPAF is synthesized as an inactive precursor that is processed and activated during infection. Here, we show that CPAF can be activated in uninfected cells by experimentally induced oligomerization, reminiscent of the activation mode of initiator caspases. CPAF activity induces proteolysis of cellular substrates including two novel targets, cyclin B1 and PARP, and indirectly results in the processing of pro-apoptotic BH3-only proteins. CPAF activation induces striking morphological changes in the cell and, later, cell death. Biochemical and ultrastructural analysis of the cell death pathway identify the mechanism of cell death as nonapoptotic. Active CPAF in uninfected human cells thus mimics many features of chlamydial infection, implicating CPAF as a major factor of chlamydial pathogenicity, Chlamydia-associated cell damage, and inflammation.

Background: Our objective was to test the effect of physicians providing brief health lifestyle counseling to patients with type 2 diabetes mellitus during usual care visits., Methods: We conducted a randomized controlled trial of a 12-month intervention at 2 large community health centers, enrolling 310 patients with a body mass index (calculated as weight in kilograms divided by height in meters squared) of 25 or greater. In the intervention group, self-management goals for nutrition and physical activity were set using a tailored computer program. Goals were then reviewed at each clinic visit by physicians. The control group received only printed health education materials. The main outcome measures included change in physical activity and body weight., Results: In the intervention group, recommended levels of physical activity increased from 26% at baseline to 53% at 12 months (P< .001) compared with controls (30% to 37%; P= .27), and 32% of patients in the intervention group lost 6 or more pounds at 12 months compared with 18.9% of controls (odds ratio, 2.2; P= .006)., Conclusion: A brief intervention to increase the dialogue between patients and health care providers about behavioral goals can lead to increased physical activity and weight loss.

Infection with Chlamydia protects mammalian host cells against apoptosis. Hypotheses have been proposed to explain this molecularly, including the up-regulation of host anti-apoptotic proteins such as cellular Inhibitor of Apoptosis Protein (IAP) 2 and the Bcl-2 protein Mcl-1. To test for the importance of these proteins, we used mouse embryonic fibroblasts from gene-targeted mice that were deficient in cIAP1, cIAP2, cIAP1/cIAP2, XIAP, or Mcl-1. Infection with Chlamydia trachomatis protected all cells equally well against apoptosis, which was induced either with tumour necrosis factor/cycloheximide (IAP-knock-out cells) or staurosporine (Mcl-1-knock-out). Therefore, these cellular anti-apoptotic proteins are not essential for apoptosis-protection by C. trachomatis.

Context: Partners in Health Education (PHE) is a Dartmouth Medical School elective that pairs first- and second-year medical students with local elementary school classroom teachers to provide health messages to students. The primary aim of the programme is to help medical students improve their communication skills through teaching children about health. Secondary aims are to teach children about health and the prevention of injury and disease and to support community teachers in their health promotion efforts. This report contains the results of the assessment of the programme's impact on the medical students., Methods: Sixteen first- and second-year medical students comprised the participants for the study. Students were assessed during their first and fourth teaching experiences using a variety of evaluation measures, including student surveys of expectations and perceptions; ratings of performance in the classroom by students, teachers, and classroom observers; coded videotapes of classroom teaching sessions; and performance on a measure of physician-patient communication skills., Findings: Over the course of the teaching experience, medical students' teaching and communication skills increased on a number of measures., Discussion: Programmes such as PHE can provide true service-learning experiences in which all participants benefit. Medical students can learn how to communicate about health, a set of skills they will need to become effective physicians. School children can learn about health, so they are empowered to take charge of their health and to make healthy choices.

Nitrous oxide is produced by the catalytic oxidation of organic nitrogen compounds of several distinct structural types with Hopcalite catalyst at a space velocity of 21,000 hours(-1) and at temperatures near 300 degrees C.