Probing the transient dark state of substrate binding to GroEL by relaxation-based solution NMR

The mechanism whereby the prototypical chaperonin GroEL performs work on substrate proteins has not yet been fully elucidated, hindered by lack of detailed structural and dynamic information on the bound substrate. Previous investigations have produced conflicting reports on the state of GroEL-bound polypeptides, largely due to the transient and dynamic nature of these complexes. Here, we present a unique approach, based on combined analysis of four complementary relaxation-based NMR experiments, to probe directly the “dark” NMR-invisible state of the model, intrinsically disordered, polypeptide amyloid β (Aβ40) bound to GroEL. The four NMR experiments, lifetime line-broadening, dark-state exchange saturation transfer, relaxation dispersion, and small exchange-induced chemical shifts, are dependent in different ways on the overall exchange rates and populations of the free and bound states of the substrate, as well as on residue-specific dynamics and structure within the bound state as reported by transverse magnetization relaxation rates and backbone chemical shifts, respectively. Global fitting of all the NMR data shows that the complex is transient with a lifetime of <1 ms, that binding involves two predominantly hydrophobic segments corresponding to predicted GroEL consensus binding sequences, and that the structure of the bound polypeptide remains intrinsically and dynamically disordered with minimal changes in secondary structure propensity relative to the free state. Our results establish a unique method to observe NMR-invisible dynamic states of GroEL-bound substrates and to describe at atomic resolution the events between substrate binding and encapsulation that are crucial for understanding the normal and stress-related metabolic function of chaperonins.     

Polyunsaturated Fatty Acids and Disease-associated and Cytokine-induced Neurological Manifestations

Fish oil supplementation is suggested as possible mean to improve neurological manifestations of chronic diseases and cytokine immunotherapies. Preclinical and clinical studies show that fish oil supplementation seems able to reduce disease-associated anorexia and body weight loss. This improvement could be due to shifts in metabolism and changes in proinflammatory cytokine production and action. ω-3 Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid, are used as substrates for eicosanoid synthesis, competing for enzymes with arachidonic acid, which is a substrate for the synthesis of proinflammatory immunomodulators, such as prostaglandin E₂. Fish oil supplementation is generally found to lower production of cytokines including interleukin-1 and tumor necrosis factor-α, thereby reducing various immune responses, including inflammation. However, conflicting results regarding the effects of fish oil interventions have been reported. The main factor that emerges from the contradictory reports is the variety of models, assays and methodologies that have been used. This brief review presents an overall perspective on the potential use of ω-3 PUFAs as a nutritional intervention to ameliorate disease-associated and cytokine-induced neurological manifestations. We conclude that substantial further research is required to understand the exact nature of n-3 PUFA-induced immunomodulation in health and disease.     

Identifying the core competencies of mental health telephone triage

Aims and objectives. The primary aim of this study was to identify the core competencies of mental health telephone triage, including key role tasks, skills, knowledge and responsibilities, in which clinicians are required to be competent to perform safe and effective triage. Background. Recent global trends indicate an increased reliance on telephone‐based health services to facilitate access to health care across large populations. The trend towards telephone‐based health services has also extended to mental health settings, evidenced by the growing number of mental health telephone triage services providing 24‐hour access to specialist mental health assessment and treatment. Mental health telephone triage services are critical to the early identification of mental health problems and the provision of timely, appropriate interventions. In spite of the rapid growth in mental health telephone triage and the important role these services play in the assessment and management of mental illness and related risks, there has been very little research investigating this area of practice. Design. An observational design was employed to address the research aims. Methods. Structured observations (using dual wireless headphones) were undertaken on 197 occasions of mental health telephone triage over a three‐month period from January to March 2011. Results. The research identified seven core areas of mental health telephone triage practice in which clinicians are required to be competent in to perform effective mental health telephone triage, including opening the call; performing mental status examination; risk assessment; planning and action; termination of call; referral and reporting; and documentation. Conclusions. The findings of this research contribute to the evidence base for mental health telephone triage by articulating the core competencies for practice. Relevance to clinical practice. The mental health telephone triage competencies identified in this research may be used to define an evidence‐based framework for mental health telephone triage practice that aims to improve the quality, consistency and accuracy of telephone‐based mental health triage assessment.     

Efficacy of Chloroquine for the Treatment of Uncomplicated Plasmodium falciparum Malaria in Honduras

Chloroquine (CQ) is officially used for the primary treatment of Plasmodium falciparum malaria in Honduras. In this study, the therapeutic efficacy of CQ for the treatment of uncomplicated P. falciparum malaria in the municipality of Puerto Lempira, Gracias a Dios, Honduras was evaluated using the Pan American Health Organization—World Health Organization protocol with a follow-up of 28 days. Sixty-eight patients from 6 months to 60 years of age microscopically diagnosed with uncomplicated P. falciparum malaria were included in the final analysis. All patients who were treated with CQ (25 mg/kg over 3 days) cleared parasitemia by day 3 and acquired no new P. falciparum infection within 28 days of follow-up. All the parasite samples sequenced for CQ resistance mutations (pfcrt) showed only the CQ-sensitive genotype (CVMNK). This finding shows that CQ remains highly efficacious for the treatment of uncomplicated P. falciparum malaria in Gracias a Dios, Honduras.     

Standardizing Postoperative Complications—Validating the Clavien-Dindo Complications Classification in Cardiac Surgery

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