Closely Related G-Protein-Coupled Receptors Use Multiple And Distinct Domains On G-Protein Α-Subunits For Selective Coupling

The molecular basis of selectivity in G-protein receptor coupling has been explored by comparing the abilities of G-protein heterotrimers containing chimeric Galpha subunits, comprised of various regions of Gi1alpha, Gtalpha, and Gqalpha, to stabilize the high affinity agonist binding state of serotonin, adenosine, and muscarinic receptors. The data indicate that multiple and distinct determinants of selectivity exist for individual receptors. While the A1 adenosine receptor does not distinguish between Gi1alpha and Gtalpha sequences, the 5-HT1A and 5-HT1B serotonin and M2 muscarinic receptors can couple with Gi1 but not Gt. It is possible to distinguish domains that eliminate coupling and are defined as critical, from those that impair coupling and are defined as important. Domains within the N terminus, alpha4-helix, and alpha4-helix-alpha4/beta6-loop of Gi1alpha are involved in 5-HT and M2 receptor interactions. Chimeric Gi1alpha/Gqalpha subunits verify the critical role of the Galpha C terminus in receptor coupling, however, the individual receptors differ in the C-terminal amino acids required for coupling. Furthermore, the EC50 for interactions with Gi1 differ among the individual receptors. These results suggest that coupling selectivity ultimately involves subtle and cooperative interactions among various domains on both the G-protein and the associated receptor as well as the G-protein concentration

Characterisation of Anopheles strains used for laboratory screening of new vector control products

Background: Insecticides formulated into products that target Anopheles mosquitos have had an immense impact on reducing malaria cases in Africa. However, resistance to currently used insecticides is spreading rapidly and there is an urgent need for alternative public health insecticides. Potential new insecticides must be screened against a range of characterized mosquito strains to identify potential resistance liabilities. The Liverpool School of Tropical Medicine maintains three susceptible and four resistant Anopheles strains that are widely used for screening for new insecticides. The properties of these strains are described in this paper. Methods: WHO tube susceptibility bioassays were used for colony selection and to screen for resistance to the major classes of public health insecticides. Topical and tarsal contact bioassays were used to produce dose response curves to assess resistance intensity. Bioassays with the synergist piperonyl butoxide were also performed. Taqman™ assays were used to screen for known target site resistance alleles (kdr and ace-1). RT-qPCR was used to quantify expression of genes associated with pyrethroid resistance. Results: Pyrethroid selection pressure has maintained resistance to this class in all four resistant strains. Some carbamate and organophosphate resistance has been lost through lack of exposure to these insecticide classes. The Anopheles gambiae (sensu lato) strains, VK7 2014, Banfora M and Tiassalé 13 have higher levels of pyrethroid resistance than the An. funestus FUMOZ-R strain. Elevated expression of P450s is found in all four strains and the 1014F kdr mutation is present in all three An. gambiae strains at varying frequencies. Tarsal contact data and overexpression of CYP4G16 and SAP2 suggest penetration barriers and/or sequestration also confer resistance in Banfora M. Conclusions: Continual selection with deltamethrin has maintained a stable pyrethroid-resistant phenotype over many generations. In conjunction with a standardized rearing regime, this ensures quality control of strains over time allowing for robust product comparison and selection of optimal products for further development. The identification of multiple mechanisms underpinning insecticide resistance highlights the importance of screening new compounds against a range of mosquito strains

Three years of insecticide resistance monitoring in <it>Anopheles gambiae</it> in Burkina Faso: resistance on the rise?

<p>Abstract</p> <p>Background and methods</p> <p>A longitudinal <it>Anopheles gambiae s.l.</it> insecticide-resistance monitoring programme was established in four sentinel sites in Burkina Faso. For three years, between 2008 and 2010, WHO diagnostic dose assays were used to measure the prevalence of resistance to all the major classes of insecticides at the beginning and end of the malaria transmission season. Species identification and genotyping for target site mutations was also performed and the sporozoite rate in adults determined.</p> <p>Results</p> <p>At the onset of the study, resistance to DDT and pyrethroids was already prevalent in <it>An. gambiae s.l.</it> from the south-west of the country but mosquitoes from the two sites in central Burkina Faso were largely susceptible. Within three years, DDT and permethrin resistance was established in all four sites. Carbamate and organophosphate resistance remains relatively rare and largely confined to the south-western areas although a small number of bendiocarb survivors were found in all sites by the final round of monitoring. The <it>ace-1</it>^<it>R</it> target site resistance allele was present in all localities and its frequency exceeded 20% in 2010 in two of the sites. The frequency of the <it>1014F kdr</it> mutation increased throughout the three years and by 2010, the frequency of <it>1014F</it> in all sites combined was 0.02 in <it>Anopheles arabiensis</it>, 0.56 in <it>An. gambiae</it> M form and 0.96 in <it>An. gambiae</it> S form. This frequency did not differ significantly between the sites. The <it>1014S kdr</it> allele was only found in <it>An. arabiensis</it> but its frequency increased significantly throughout the study (P = 0.0003) and in 2010 the <it>1014S</it> allele frequency was 0.08 in <it>An. arabiensis.</it> Maximum sporozoite rates (12%) were observed in Soumousso in 2009 and the difference between sites is significant for each year.</p> <p>Conclusion</p> <p>Pyrethroid and DDT resistance is now established in <it>An. gambiae s.l.</it> throughout Burkina Faso. Results from diagnostic dose assays are highly variable within and between rounds of testing, and hence it is important that resistance monitoring is carried out on more than one occasion before decisions on insecticide procurement for vector control are made. The presence of <it>1014S</it> in <it>An. gambiae s.l.</it>, in addition to <it>1014F</it>, is not unexpected given the recent report of <it>1014S</it> in Benin but highlights the importance of monitoring for both mutations throughout the continent. Future research must now focus on the impact that this resistance is having on malaria control in Burkina Faso.</p

Treatment Practices, Outcomes, and Costs of Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis, United States, 2005–2007

To describe factors associated with multidrug-resistant (MDR), including extensively-drug-resistant (XDR), tuberculosis (TB) in the United States, we abstracted inpatient, laboratory, and public health clinic records of a sample of MDR TB patients reported to the Centers for Disease Control and Prevention from California, New York City, and Texas during 2005–2007. At initial diagnosis, MDR TB was detected in 94% of 130 MDR TB patients and XDR TB in 80% of 5 XDR TB patients. Mutually exclusive resistance was 4% XDR, 17% pre-XDR, 24% total first-line resistance, 43% isoniazid/rifampin/rifabutin-plus-other resistance, and 13% isoniazid/rifampin/rifabutin-only resistance. Nearly three-quarters of patients were hospitalized, 78% completed treatment, and 9% died during treatment. Direct costs, mostly covered by the public sector, averaged $134,000 per MDR TB and$430,000 per XDR TB patient; in comparison, estimated cost per non-MDR TB patient is $17,000. Drug resistance was extensive, care was complex, treatment completion rates were high, and treatment was expensive

Methodologic Innovation in Creating Clinical Practice Guidelines : Insights From the 2018 Society of Critical Care Medicine Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption Guideline Effort

OBJECTIVES: To describe novel guideline development strategies created and implemented as part of the Society of Critical Care Medicine's 2018 clinical practice guidelines for pain, agitation (sedation), delirium, immobility (rehabilitation/mobility), and sleep (disruption) in critically ill adults. DESIGN: We involved critical illness survivors from start to finish, used and expanded upon Grading of Recommendations, Assessment, Development and Evaluation methodology for making recommendations, identified evidence gaps, and developed communication strategies to mitigate challenges. SETTING/SUBJECTS: Thirty-two experts from five countries, across five topic-specific sections; four methodologists, two medical librarians, four critical illness survivors, and two Society of Critical Care Medicine support staff. INTERVENTIONS: Unique approaches included the following: 1) critical illness survivor involvement to help ensure patient-centered questions and recommendations; 2) qualitative and semiquantitative approaches for developing descriptive statements; 3) operationalizing a three-step approach to generating final recommendations; and 4) systematic identification of evidence gaps. MEASUREMENTS AND MAIN RESULTS: Critical illness survivors contributed to prioritizing topics, questions, and outcomes, evidence interpretation, recommendation formulation, and article review to ensure that their values and preferences were considered in the guidelines. Qualitative and semiquantitative approaches supported formulating descriptive statements using comprehensive literature reviews, summaries, and large-group discussion. Experts (including the methodologists and guideline chairs) developed and refined guideline recommendations through monthly topic-specific section conference calls. Recommendations were precirculated to all members, presented to, and vetted by, most members at a live meeting. Final electronic voting provided links to all forest plots, evidence summaries, and "evidence to decision" frameworks. Written comments during voting captured dissenting views and were integrated into evidence to decision frameworks and the guideline article. Evidence gaps, reflecting clinical uncertainty in the literature, were identified during the evidence to decision process, live meeting, and voting and formally incorporated into all written recommendation rationales. Frequent scheduled "check-ins" mitigated communication gaps. CONCLUSIONS: Our multifaceted, interdisciplinary approach and novel methodologic strategies can help inform the development of future critical care clinical practice guidelines