Gene expression in heart, kidney, and liver identifies possible mechanisms underpinning fetal resistance and susceptibility to in utero PRRSV infection.

Porcine reproductive and respiratory syndrome (PRRS) is one of the costliest diseases to pork producers worldwide. We tested samples from the pregnant gilt model (PGM) to better understand the fetal response to in-utero PRRS virus (PRRSV) infection. Our goal was to identify critical tissues and genes associated with fetal resilience or susceptibility. Pregnant gilts (N=22) were infected with PRRSV on day 86 of gestation. At 21 days post maternal infection, the gilts and fetuses were euthanized, and fetal tissues collected. Fetuses were characterized for PRRS viral load in fetal serum and thymus, and preservation status (viable or meconium stained: VIA or MEC). Fetuses (N=10 per group) were compared: uninfected (UNIF; <1 log/µL PRRSV RNA), resilient (HV_VIA, >5 log virus/µL but viable), and susceptible (HV_MEC, >5 log virus/µL with MEC). Gene expression in fetal heart, kidney, and liver was investigated using NanoString transcriptomics. Gene categories investigated were hypothesized to be involved in fetal response to PRRSV infection: renin- angiotensin-aldosterone, inflammatory, transporter and metabolic systems. Following PRRSV infection, CCL5 increased expression in heart and kidney, and ACE2 decreased expression in kidney, each associated with fetal PRRS susceptibility. Liver revealed the most significant differential gene expression: CXCL10 decreased and IL10 increased indicative of immune suppression. Increased liver gene expression indicated potential associations with fetal PRRS susceptibility on several systems including blood pressure regulation (AGTR1), energy metabolism (SLC16A1 and SLC16A7), tissue specific responses (KL) and growth modulation (TGFB1). Overall, analyses of non-lymphoid tissues provided clues to mechanisms of fetal compromise following maternal PRRSV infection.

Do certain phrases in letters of recommendation predict success in fellowship performance?

BACKGROUND: Letters of recommendation (LORs) are a valued, yet imperfect tool. Program directors (PDs) score phrases such as give my highest recommendation and top 5 to 10% of students as positive. Although positive phrases are valued by PDs, there is no evidence that these phrases predict performance. We attempt to identify whether 12 specific phrases found in letters of recommendation predict future performance of fellows. METHODS: LORs were evaluated for 12 select phrases and statements. Alpha Omega Alpha (AOA) status, Step 2 Clinical Knowledge (CK) score, and whether the letter writer was personally known to our admission's committee were also categorized. Logistic regressions were performed to evaluate the relationship of the independent variables with fellow performance. RESULTS: Using multivariate logistic regression, one of the best residents (OR = 4.02, 95% CI (1.0, 15.9), p < 0.05), exceeds expectations (OR = 4.74, 95% CI (1.4, 16.3), p = 0.01), and give my highest recommendation (OR = 3.87, 95% CI (1.3, 11.7), p = 0.02) predicted positive performance. Highly recommend (OR = 0.31, 95% CI (0.1, 1.0), p < 0.05) and top 5 to 10% (OR = 0.05, 95% CI (0.0, 0.6), p = 0.02) predicted negative performance. The remaining phrases did not correlate to fellowship performance. CONCLUSION: The current LOR evaluation process may place undo importance on phrases that have limited bearing on a candidate's success in training. Training both letter readers and writers to avoid using coded language or avoid assigning improper importance to select phrases may help improve the candidate selection process.

Pediatric Anesthesiology Milestones 2.0: An Update, Rationale, and Plan Forward.

Formal training in the subspecialty of pediatric anesthesiology began >60 years ago. Over the years, the duration and clinical work has varied, but what has stayed constant is a mission to develop clinically competent and professionally responsible pediatric anesthesiologists. Since accreditation in 1997, there has been additional guidance by the Accreditation Council on Graduate Medical Education (ACGME) and greater accountability to the public that we, indeed, are producing competent and professional pediatric anesthesiologists. This has been influenced by the slow evolution from time-based educational curriculum to a competency-based paradigm. As with all ACGME-accredited specialties, education leaders in pediatric anesthesiology first convened in 2014 to design specialty-specific developmental trajectories within the framework of the 6 core competencies, known as milestones, on which fellows were to be tracked during the 1-year fellowship. With 5 years of implementation, and substantial data and feedback, it has become clear that an iterative improvement was necessary to mirror the evolution of the profession. It was evident that the community required brevity and clarity in the next version of the milestones and required additional resources for assessment and faculty development. We describe here the methodology and considerations of our working group, guided by ACGME, in the rewriting of the milestones. We also provide suggestions for implementation and collaboration to support the education and assessment of pediatric anesthesiology fellows across the country.

Surgical sensation during caesarean section: a qualitative analysis.

BACKGROUND: Caesarean section (CS) is a major abdominal surgery performed usually on a young and healthy population under neuraxial anesthesia with little to no sedation. This creates a distinct surgical experience whereby patients are aware of the surgical process, physical sensations, and their environment. This study aimed to provide an in-depth descriptive assessment of subjective surgical experience during CS under regional anaesthesia. We expected the information gained would enhance our current understanding and better alleviate patient anxiety through informed counselling. METHODS: This qualitative descriptive study was conducted at a Canadian academic centre. Twenty patients participated in semi-structured interviews within a week of CS, using an interview guide developed for this study. Patient medical records were reviewed to collect demographic and surgical information. Thematic analysis was conducted using an inductive approach to determine common themes. RESULTS: Nine themes were identified. Five themes were identified in the category of surgical sensation and four themes were identified in the category of peri-operative education. CONCLUSIONS: Patients commonly experienced pressure and movement sensations at varying intensity, and most did not experience pain. Environmental factors, including sounds and distraction by the newborn, affected perception of surgical sensation. Patients wish to receive pre-operative counselling regarding potential surgical sensations, as well as ongoing communication from their anaesthesiologist. These results can be used to guide informed discussions with patients and direct further investigation in this area.

Development and validation of a prognostic model for death 30 days after adult emergency laparotomy.

The probability of death after emergency laparotomy varies greatly between patients. Accurate pre-operative risk prediction is fundamental to planning care and improving outcomes. We aimed to develop a model limited to a few pre-operative factors that performed well irrespective of surgical indication: obstruction; sepsis; ischaemia; bleeding; and other. We derived a model with data from the National Emergency Laparotomy Audit for patients who had emergency laparotomy between December 2016 and November 2018. We tested the model on patients who underwent emergency laparotomy between December 2018 and November 2019. There were 4077/40,816 (10%) deaths 30 days after surgery in the derivation cohort. The final model had 13 pre-operative variables: surgical indication; age; blood pressure; heart rate; respiratory history; urgency; biochemical markers; anticipated malignancy; anticipated peritoneal soiling; and ASA physical status. The predicted mortality probability deciles ranged from 0.1% to 47%. There were 1888/11,187 deaths in the test cohort. The scaled Brier score, integrated calibration index and concordance for the model were 20%, 0.006 and 0.86, respectively. Model metrics were similar for the five surgical indications. In conclusion, we think that this prognostic model is suitable to support decision-making before emergency laparotomy as well as for risk adjustment for comparing organisations.

Severity of Dementia and Survival in Patients Diagnosed with Colorectal Cancer: A National Cohort Study in England and Wales.

AIMS: There is little evidence about the survival of patients with colorectal cancer (CRC) also diagnosed with dementia. We quantified dementia severity and estimated how it is associated with 2-year overall survival. MATERIALS AND METHODS: Records of patients aged 65 years or older diagnosed with CRC in England and Wales were identified. A novel proxy for dementia severity combined dementia diagnosis in administrative hospital data with Eastern Cooperative Oncology Group performance status. Cox regression was used to estimate hazard ratios with and without risk adjustment. RESULTS: In total, 4033 of 105 250 CRC patients (3.8%) had dementia recorded. Two-year survival decreased with increasing dementia severity from 65.4% without dementia, 53.5% with mild dementia, 33.0% with moderate dementia to 16.5% with severe dementia (hazard ratio comparing severe with no dementia: 2.97; 95% confidence interval 2.79, 3.16). Risk adjustment for comorbidity and cancer stage reduced this association slightly (hazard ratio 2.52; 95% confidence interval 2.37, 2.68) and additional adjustment for treatment factors reduced it further (hazard ratio 1.60; 95% confidence interval 1.50, 1.70). CONCLUSIONS: Survival of CRC patients varied strongly according to dementia severity, suggesting that a 'one-size-fits-all' policy for the care of CRC patients with dementia is not appropriate. Comprehensive assessment of cancer patients with dementia that considers dementia severity is essential in a shared decision-making process that ensures patients receive the most appropriate treatment for their individual needs and preferences.

Using body size as an indicator for age structure in field populations of Aedes aegypti (Diptera: Culicidae).

BACKGROUND: The Aedes aegypti mosquito is a vector of several viruses including dengue, chikungunya, zika, and yellow fever. Vector surveillance and control are the primary methods used for the control and prevention of disease transmission; however, public health institutions largely rely on measures of population abundance as a trigger for initiating control activities. Previous research found evidence that at the northern edge of Ae. aegypti's geographic range, survival, rather than abundance, is likely to be the factor limiting disease transmission. In this study, we sought to test the utility of using body size as an entomological index to surveil changes in the age structure of field-collected female Aedes aegypti. METHODS: We collected female Ae. aegypti mosquitoes using BG sentinel traps in three cities at the northern edge of their geographic range. Collections took place during their active season over the course of 3 years. Female wing size was measured as an estimate of body size, and reproductive status was characterized by examining ovary tracheation. Chronological age was determined by measuring transcript abundance of an age-dependent gene. These data were then tested with female abundance at each site and weather data from the estimated larval development period and adulthood (1 week prior to capture). Two sources of weather data were tested to determine which was more appropriate for evaluating impacts on mosquito physiology. All variables were then used to parameterize structural equation models to predict age. RESULTS: In comparing city-specific NOAA weather data and site-specific data from HOBO remote temperature and humidity loggers, we found that HOBO data were more tightly associated with body size. This information is useful for justifying the cost of more precise weather monitoring when studying intra-population heterogeneity of eco-physiological factors. We found that body size itself was not significantly associated with age. Of all the variables measured, we found that best fitting model for age included temperature during development, body size, female abundance, and relative humidity in the 1 week prior to capture . The strength of models improved drastically when testing one city at a time, with Hermosillo (the only study city with seasonal dengue transmission) having the best fitting model for age. Despite our finding that there was a bias in the body size of mosquitoes collected alive from the BG sentinel traps that favored large females, there was still sufficient variation in the size of females collected alive to show that inclusion of this entomological indicator improved the predictive capacity of our models. CONCLUSIONS: Inclusion of body size data increased the strength of weather-based models for age. Importantly, we found that variation in age was greater within cities than between cities, suggesting that modeling of age must be made on a city-by-city basis. These results contribute to efforts to use weather forecasts to predict changes in the probability of disease transmission by mosquito vectors.

Small bowel stomas are associated with higher risk of circulating food-specific-IgG than patients with organic gastrointestinal conditions and colostomies.

OBJECTIVE: The effects of food sensitivity can easily be masked by other digestive symptoms in ostomates and are unknown. We investigated food-specific-IgG presence in ostomates relative to participants affected by other digestive diseases. DESIGN: Food-specific-IgG was evaluated for 198 participants with a panel of 109 foods. Immunocompetency status was also tested. Jejunostomates, ileostomates and colostomates were compared with individuals with digestive tract diseases with inflammatory components (periodontitis, eosinophilic esophagitis, duodenitis, ulcerative colitis, Crohn's disease and appendicitis), as well as food malabsorption due to intolerance. A logistic regression model with covariates was used to estimate the effect of the experimental data and demographic characteristics on the likelihood of the immune response. RESULTS: Jejunostomates and ileostomates had a significant risk of presenting circulating food-specific-IgG in contrast to colostomates (OR 12.70 (p=0.002), 6.19 (p=0.011) and 2.69 (p=0.22), respectively). Crohn's disease, eosinophilic esophagitis and food malabsorption groups also showed significantly elevated risks (OR 4.67 (p=0.048), 8.16 (p=0.016) and 18.00 (p=0.003), respectively), but not the ulcerative colitis group (OR 2.05 (p=0.36)). Individuals with profoundly or significantly reduced, and mild to moderately reduced, levels of total IgG were protected from the formation of food-specific IgG (OR 0.09 (p=<0.001) and 0.33 (p=0.005), respectively). Males were at higher risk than females. CONCLUSION: The strength of a subject's immunocompetence plays a role in the intensity to which the humoral system responds via food-specific-IgG. An element of biogeography emerges in which the maintenance of a colonic space might influence the risk of having circulating food-specific-IgG in ostomates.

Face Value: Remote facial expression analysis adds predictive power to perceived effectiveness for selecting anti-tobacco PSAs.

Perceived effectiveness (PE) is a validated tool for predicting the potential impact of anti-tobacco public service announcements (PSAs). We set out to evaluate the added predictive value of facial expression analysis when combined with PE in a remote (online) survey. Each of 302 tobacco users watched 3 PSAs and allowed transmission of webcam videos from which metrics for "attention" (head position) and "facial action units" (FAU) were computed. The participants completed scales for their subjective emotions, willingness to share on social media, and intention to quit smoking using the Tobacco Free Florida website. Based on PE, both ready to quit (RTQ) and not ready (NR) respondents favored the same PSAs but RTQs assigned higher PE scores. Negative PSAs ("sad" or "frightening") were more compelling overall but RTQs also favored surprising ads and were more willing to share them on social media. Logistic regression showed that the combination of Attention + FAU+ PE (AUC = .816, p < .0001) outperformed single factors or factor combinations in distinguishing RTQ from NR. This study demonstrates that on-line assessment of facial expressions enhances the predictive value of PE and can be deployed on large remote samples.

NASA GEOS Composition Forecast Modeling System GEOS-CF v1.0: Stratospheric Composition.

The NASA Goddard Earth Observing System (GEOS) Composition Forecast (GEOS-CF) provides recent estimates and 5-day forecasts of atmospheric composition to the public in near-real time. To do this, the GEOS Earth system model is coupled with the GEOS-Chem tropospheric-stratospheric unified chemistry extension (UCX) to represent composition from the surface to the top of the GEOS atmosphere (0.01 hPa). The GEOS-CF system is described, including updates made to the GEOS-Chem UCX mechanism within GEOS-CF for improved representation of stratospheric chemistry. Comparisons are made against balloon, lidar, and satellite observations for stratospheric composition, including measurements of ozone (O3) and important nitrogen and chlorine species related to stratospheric O3 recovery. The GEOS-CF nudges the stratospheric O3 toward the GEOS Forward Processing (GEOS FP) assimilated O3 product; as a result the stratospheric O3 in the GEOS-CF historical estimate agrees well with observations. During abnormal dynamical and chemical environments such as the 2020 polar vortexes, the GEOS-CF O3 forecasts are more realistic than GEOS FP O3 forecasts because of the inclusion of the complex GEOS-Chem UCX stratospheric chemistry. Overall, the spatial patterns of the GEOS-CF simulated concentrations of stratospheric composition agree well with satellite observations. However, there are notable biases-such as low NO x and HNO3 in the polar regions and generally low HCl throughout the stratosphere-and future improvements to the chemistry mechanism and emissions are discussed. GEOS-CF is a new tool for the research community and instrument teams observing trace gases in the stratosphere and troposphere, providing near-real-time three-dimensional gridded information on atmospheric composition.

Maternity services' responses to the COVID-19 pandemic: how Public Health England guidance was implemented in practice.

INTRODUCTION: The rapidly evolving COVID-19 pandemic required systemic change in how healthcare was delivered to minimize virus transmission whilst maintaining safe service delivery. Deemed at 'moderate-high risk', maternity patients are an important patient group that require consideration. Public Health England (PHE) issued national guidance on how to adjust these services. AIM: To explore how maternity units in England implemented PHE guidance. METHODS: An online survey of 22 items was distributed to individuals that had worked on an England-based maternity unit during the COVID-19 pandemic. The questionnaire was designed and tested by the multidisciplinary research team. Data was collected from November 2020 to July 2021. FINDINGS: Forty-four participants across 33 maternity units responded. Ninety-three percent were able to test all women requiring an overnight stay for COVID-19. Only 27% reported birth partners were tested for COVID-19. Only 73% reported they were able to isolate all COVID-19-positive patients in single rooms. Eighty-four percent stated they were aware of current PHE guidance on personal protective equipment (PPE) and 82% felt 'confident' in donning/doffing of PPE. Priorities for the future include rapid testing and a focus on community service provision. CONCLUSIONS: PHE COVID-19 guidance was implemented differently in maternity units across England due to the varying resources available at each trust leading to variable ability to test and isolate patients as recommended. More specific, tailored guidance for infection control measures against COVID-19 is needed for maternity settings due to their unique position.

Implementation of Public Health England infection prevention and control guidance in maternity units in response to the COVID-19 pandemic.

BACKGROUND: This study aimed to explore the successes and barriers to the implementation of Public Health England (PHE) infection prevention and control guidance in English maternity units during the COVID-19 pandemic. METHODS: Qualitative semi-structured interviews with obstetricians, midwives and neonatologists who worked in a maternity unit in England, UK, between March 2020 and July 2021. A thematic analysis was performed. RESULTS: Successes to the implementation of PHE guidance were related to existing infrastructure, training satisfaction, and organisational culture where subthemes considered the importance of a multidisciplinary approach, COVID-19 dedicated roles and hospital-wide communication. Barriers to implementation related to the applicability of the guidance with subthemes highlighting contradictions between updates, specialties and hospitals, undesirable timings and frequency of guidance updates, reductions in staff compliance and delayed implementation. Finally, the layout of some units made it difficult to implement various aspects of the guidance (e.g., social distancing), and many detailed issues related to information technology compatibility, a lack of availability and accessibility to appropriate personal protective equipment (PPE), and variations in testing arrangements between units. CONCLUSIONS: This research provides information on the experiences of healthcare professionals working on maternity units during the COVID-19 pandemic. Findings illustrate the importance of effective hospital-wide communication and the need for consistent, easily understood guidance. These results will be used to inform the content of an expert panel consensus meeting.

Accuracy and cost effectiveness of a waferless osteotomy approach, using patient specific guides and plates in orthognathic surgery: a systematic review.

The aim of this systematic review is to evaluate the accuracy of waferless osteotomy procedures in orthognathic surgery with a secondary aim to determine the cost-effectiveness of the procedure. A literature search was conducted on the databases PubMed and Scopus, with PRISMA guidelines followed. An initial yield of 4149 articles were identified, ten of which met the desired inclusion criteria. The total sample of patients undergoing waferless osteotomies included in this review was 142 patients. Nine of the studies used surgical cutting guides along with customised surgical plates to eliminate the surgical wafer and one study used pre-bent locking plates instead of customised plates. The eligible articles determined their surgical accuracy by comparing the positions of bony or dental landmarks on the pre-operative and post-operative images. The articles all reported acceptable accuracy within previously established clinical parameters. The majority of authors concluded that it is an accurate surgical approach and can be cost effective which is often a barrier to novel techniques however there were studies that contrasted the view of the cost efficacy. Due to the lack of published randomised controlled trials, current evidence is not strong enough to recommend the use of surgical cutting guides and customised/pre-bent plates for orthognathic surgery.

Genome Sequence of Dermacoccus Strain Tok2021, a Soil Actinobacterium Isolated from a Pinus radiata Forest.

Dermacoccus strain Tok2021 (Actinobacteria) is a soil bacterium, isolated from commercial Pinus radiata forest soil from Tokoiti, New Zealand. The bacterium has a draft genome size of 3,101,786 bp and harbors genes involved in antibiotic production, siderophore production, and N2 fixation.

Associations between ethnicity and admission to intensive care among women giving birth: a cohort study.

OBJECTIVE: To determine the association between ethnic group and likelihood of admission to intensive care in pregnancy and the postnatal period. DESIGN: Cohort study. SETTING: Maternity and intensive care units in England and Wales. POPULATION OR SAMPLE: A total of 631 851 women who had a record of a registerable birth between 1 April 2015 and 31 March 2016 in a database used for national audit. METHODS: Logistic regression analyses of linked maternity and intensive care records, with multiple imputation to account for missing data. MAIN OUTCOME MEASURES: Admission to intensive care in pregnancy or postnatal period to 6 weeks after birth. RESULTS: In all, 2.24 per 1000 maternities were associated with intensive care admission. Black women were more than twice as likely as women from other ethnic groups to be admitted (odds ratio [OR] 2.21, 95% CI 1.82-2.68). This association was only partially explained by demographic, lifestyle, pregnancy and birth factors (adjusted OR 1.69, 95% CI 1.37-2.09). A higher proportion of intensive care admissions in Black women were for obstetric haemorrhage than in women from other ethnic groups. CONCLUSIONS: Black women have an increased risk of intensive care admission that cannot be explained by demographic, health, lifestyle, pregnancy and birth factors. Clinical and policy intervention should focus on the early identification and management of severe illness, particularly obstetric haemorrhage, in Black women, in order to reduce inequalities in intensive care admission. TWEETABLE ABSTRACT: Black women are almost twice as likely as White women to be admitted to intensive care during pregnancy and the postpartum period; this risk remains after accounting for demographic, health, lifestyle, pregnancy and birth factors.

Epidemiology and pathogenesis of stroke in preterm infants: A systematic review.

BACKGROUND: Perinatal stroke is one of the principal causes of cerebral palsy (CP) in preterm infants. Stroke in preterm infants is different from stroke in term infants, given the differences in brain maturation and the mechanisms of injury exclusive to the immature brain. We conducted a systematic review to explore the epidemiology and pathogenesis of periventricular hemorrhagic infarction (PVHI), perinatal arterial ischemic stroke (PAIS) and cerebral sinovenous thrombosis (CSVT) in preterm infants. METHODS: Studies were identified based on predefined study criteria from MEDLINE, EMBASE, SCOPUS and WEB OF SCIENCE electronic databases from 2000 -2019. Results were combined using descriptive statistics. RESULTS: Fourteen studies encompassed 546 stroke cases in preterm infants between 23 -36 weeks gestational ages and birth weights between 450 -3500 grams. Eighty percent (436/546) of the stroke cases were PVHI, 17%(93/546) were PAIS and 3%(17/546) were CSVT. Parietal PVHI was more common than temporal and frontal lobe PVHI. For PAIS, left middle cerebral artery (MCA) was more common than right MCA or cerebellar stroke. For CSVT partial or complete thrombosis in the transverse sinus was universal. All cases included multiple possible risk factors, but the data were discordant precluding aggregation within a meta-analysis. CONCLUSION: This systematic review confirms paucity of data regarding the etiology and the precise causal pathway of stroke in preterm infants. Moreover, the preterm infants unlike the term infants do not typically present with seizures. Hence high index of clinical suspicion and routine cUS will assist in the timely diagnosis and understanding of stroke in this population.

Hemispheric asymmetry in ocean change and the productivity of ecosystem sentinels.

Climate change and other human activities are causing profound effects on marine ecosystem productivity. We show that the breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts, with the strongest effects on fish-eating, surface-foraging species in the north. Hemispheric asymmetry suggests the need for ocean management at hemispheric scales. For the north, tactical, climate-based recovery plans for forage fish resources are needed to recover seabird breeding productivity. In the south, lower-magnitude change in seabird productivity presents opportunities for strategic management approaches such as large marine protected areas to sustain food webs and maintain predator productivity. Global monitoring of seabird productivity enables the detection of ecosystem change in remote regions and contributes to our understanding of marine climate impacts on ecosystems.

The Anesthesiology Milestones 2.0: An Improved Competency-Based Assessment for Residency Training.

The evolution of medical education, from a time-based to a competency-based platform, began nearly 30 years ago and continues to slowly take shape. The development of valid and reproducible assessment tools is the first step. Medical educators across specialties acknowledge the challenges and remain motivated to develop a relevant, generalizable, and measurable system. The Accreditation Council for Graduate Medical Education (ACGME) remains committed to its responsibility to the public by assuring that the process and outcome of graduate medical education in the nation's residency programs produce competent, safe, and compassionate doctors. The Milestones Project is the ACGME's current strategy in the evolution to a competency-based system, which allows each specialty to develop its own set of subcompetencies and 5-level progression, or milestones, along a continuum of novice to expert. The education community has now had nearly 5 years of experience with these rubrics. While not perfect, Milestones 1.0 provided important foundational information and insights. The first iteration of the Anesthesiology Milestones highlighted some mismatch between subcompetencies and current and future clinical practices. They have also highlighted challenges with assessment and evaluation of learners, and the need for faculty development tools. Committed to an iterative process, the ACGME assembled representatives from stakeholder groups within the Anesthesiology community to develop the second generation of Milestones. This special article describes the foundational data from Milestones 1.0 that was useful in the development process of Milestones 2.0, the rationale behind the important changes, and the additional tools made available with this iteration.

Assessing cross-resistance within the pyrethroids in terms of their interactions with key cytochrome P450 enzymes and resistance in vector populations.

BACKGROUND: It is important to understand whether the potential impact of pyrethroid resistance on malaria control can be mitigated by switching between different pyrethroids or whether cross-resistance within this insecticide class precludes this approach. METHODS: Here we assess the relationships among pyrethroids in terms of their binding affinity to, and depletion by, key cytochrome P450 enzymes (hereafter P450s) that are known to confer metabolic pyrethroid resistance in Anopheles gambiae (s.l.) and An. funestus, in order to identify which pyrethroids may diverge from the others in their vulnerability to resistance. We then investigate whether these same pyrethroids also diverge from the others in terms of resistance in vector populations. RESULTS: We found that the type I and II pyrethroids permethrin and deltamethrin, respectively, are closely related in terms of binding affinity to key P450s, depletion by P450s and resistance within vector populations. Bifenthrin, which lacks the common structural moiety of most pyrethroids, diverged from the other pyrethroids tested in terms of both binding affinity to key P450s and depletion by P450s, but resistance to bifenthrin has rarely been tested in vector populations and was not analysed here. Etofenprox, which also lacks the common structural moiety of most pyrethroids, diverged from the more commonly deployed pyrethroids in terms of binding affinity to key P450s and resistance in vector populations, but did not diverge from these pyrethroids in terms of depletion by the P450s. The analysis of depletion by the P450s indicated that etofenprox may be more vulnerable to metabolic resistance mechanisms in vector populations. In addition, greater resistance to etofenprox was found across Aedes aegypti populations, but greater resistance to this compound was not found in any of the malaria vector species analysed. The results for pyrethroid depletion by anopheline P450s in the laboratory were largely not repeated in the findings for resistance in malaria vector populations. CONCLUSION: Importantly, the prevalence of resistance to the pyrethroids α-cypermethrin, cyfluthrin, deltamethrin, λ-cyhalothrin and permethrin was correlated across malaria vector populations, and switching between these compounds as a tool to mitigate against pyrethroid resistance is not advised without strong evidence supporting a true difference in resistance.