Hydration and nutrition care practices in stroke: findings from the UK and Australia.

BACKGROUND: Dehydration and malnutrition are common in hospitalised patients following stroke leading to poor outcomes including increased mortality. Little is known about hydration and nutrition care practices in hospital to avoid dehydration or malnutrition, and how these practices vary in different countries. This study sought to capture how the hydration and nutrition needs of patients' post-stroke are assessed and managed in the United Kingdom (UK) and Australia (AUS). AIM: To examine and compare current in-hospital hydration and nutrition care practice for patients with stroke in the UK and Australia. METHODS: A cross-sectional survey was conducted between April and November 2019. Questionnaires were mailed to stroke specialist nurses in UK and Australian hospitals providing post-stroke inpatient acute care or rehabilitation. Non-respondents were contacted up to five times. RESULTS: We received 150/174 (86%) completed surveys from hospitals in the UK, and 120/162 (74%) in Australia. Of the 270 responding hospitals, 96% reported undertaking assessment of hydration status during an admission, with nurses most likely to complete assessments (85%). The most common methods of admission assessment were visual assessment of the patient (UK 62%; AUS 58%), weight (UK 52%; AUS 52%), and body mass index (UK 47%; AUS 42%). Almost all (99%) sites reported that nutrition status was assessed at some point during admission, and these were mainly completed by nurses (91%). Use of standardised nutrition screening tools were more common in the UK (91%) than Australia (60%). Similar proportions of hydration management decisions were made by physicians (UK 84%; AUS 83%), and nutrition management decisions by dietitians (UK 98%; AUS 97%). CONCLUSION: Despite broadly similar hydration and nutrition care practices after stroke in the UK and Australia, some variability was identified. Although nutrition assessment was more often informed by structured screening tools, the routine assessment of hydration was generally not. Nurses were responsible for assessment and monitoring, while dietitians and physicians undertook decision-making regarding management. Hydration care could be improved through the development of standardised assessment tools. This study highlights the need for increased implementation and use of evidence-based protocols in stroke hydration and nutrition care to improve patient outcomes.

Healthcare professionals' perspectives of the provision of, and challenges for, eating, drinking and psychological support post stroke: findings from semistructured interviews across India.

AIM: This qualitative study explores with health professionals the provision of, and challenges for, postdischarge stroke care, focussing on eating, drinking and psychological support across India. DESIGN: Qualitative semistructured interviews. SETTING: Seven geographically diverse hospitals taking part in a Global Health Research Programme on Improving Stroke Care in India. PARTICIPANTS: A purposive sample of healthcare professionals with current experience of working with patients who had a stroke. RESULTS: Interviews with 66 healthcare professionals (23 nurses (14 staff nurses; 7 senior nurse officers; 1 intensive care unit nurse; 1 palliative care nurse)); 16 doctors (10 neurologists; 6 physicians); 10 physiotherapists; 5 speech and language therapists; 4 occupational therapists; 4 dieticians; 2 psychiatrists; and 2 social workers resulted in three main themes: integrated inpatient discharge care planning processes; postdischarge patient and caregiver role and challenges; patient and caregiver engagement post discharge. CONCLUSIONS: Discharge planning was integrated and customised, although resources were limited in some sites. Task shifting compensated for a lack of specialists but was limited by staff education and training. Caregivers faced challenges in accessing and providing postdischarge care. Postdischarge care was mainly hospital based, supported by teleservices, especially for rural populations. Further research is needed to understand postdischarge care provision and the needs of stroke survivors and their caregivers.

Diagnosis and treatment of dehydration after stroke: A synthesis of existing evidence.

Dehydration after stroke is associated with poor health outcomes, increased mortality, and poses a significant economic burden to health services. Yet research suggests that monitoring and assessment of hydration status is not routinely undertaken. In this commentary, we critically appraise a systematic review which aimed to synthesise the existing evidence regarding diagnosis and treatment of dehydration after stroke. The review discusses common measures of dehydration, describes studies evaluating rehydration treatments, and highlights the link between dehydration and poorer health outcomes in both human and animal studies. The reviewers suggest, future research should focus on determining a single, validated, objective measure to clinically diagnose dehydration in stroke patients. Research designs should include clearly defined patient characteristics, type and severity of stroke, and type and time point of dehydration measurement, to enable comparison between studies. Management of hydration status is a crucial element of acute stroke care which should be routinely practiced.

Stroke in India: A systematic review of the incidence, prevalence, and case fatality.

BACKGROUND: The burden of stroke is increasing in India; stroke is now the fourth leading cause of death and the fifth leading cause of disability. Previous research suggests that the incidence of stroke in India ranges between 105 and 152/100,000 people per year. However, there is a paucity of available data and a lack of uniform methods across published studies. AIM: To identify high-quality prospective studies reporting the epidemiology of stroke in India. SUMMARY OF REVIEW: A search strategy was modified from the Cochrane Stroke Strategy and adapted for a range of bibliographic databases from January 1997 to August 2020. From 7717 identified records, nine studies were selected for inclusion; three population-based registries, a further three population-based registries also using community-based ascertainment and three community-based door-to-door surveys. Studies represented the four cities of Mumbai, Trivandrum, Ludhiana, Kolkata, the state of Punjab, and 12 villages of Baruipur in the state of West Bengal. The total population denominator was 22,479,509 and 11,654 (mean 1294 SD 1710) people were identified with incident stroke. Crude incidence of stroke ranged from 108 to 172/100,000 people per year, crude prevalence from 26 to 757/100,000 people per year, and one-month case fatality rates from 18% to 42%. CONCLUSIONS: Further high-quality evidence is needed across India to guide stroke policy and inform the development and organization of stroke services. Future researchers should consider the World Health Organization STEPwise approach to Surveillance framework, including longitudinal data collection, the inclusion of census population data, and a combination of hospital-registry and comprehensive community ascertainment strategies to ensure complete stroke identification.

Progress towards an OECD reporting framework for transcriptomics and metabolomics in regulatory toxicology.

Omics methodologies are widely used in toxicological research to understand modes and mechanisms of toxicity. Increasingly, these methodologies are being applied to questions of regulatory interest such as molecular point-of-departure derivation and chemical grouping/read-across. Despite its value, widespread regulatory acceptance of omics data has not yet occurred. Barriers to the routine application of omics data in regulatory decision making have been: 1) lack of transparency for data processing methods used to convert raw data into an interpretable list of observations; and 2) lack of standardization in reporting to ensure that omics data, associated metadata and the methodologies used to generate results are available for review by stakeholders, including regulators. Thus, in 2017, the Organisation for Economic Co-operation and Development (OECD) Extended Advisory Group on Molecular Screening and Toxicogenomics (EAGMST) launched a project to develop guidance for the reporting of omics data aimed at fostering further regulatory use. Here, we report on the ongoing development of the first formal reporting framework describing the processing and analysis of both transcriptomic and metabolomic data for regulatory toxicology. We introduce the modular structure, content, harmonization and strategy for trialling this reporting framework prior to its publication by the OECD.

Concentration- and time-dependent induction of Cyp1a and DNA damage response by benzo(a)pyrene in LMH three-dimensional spheroids.

In vitro liver toxicity tests performed using cell lines cultured as two-dimensional (2D) monolayer have limited CYP450 activity and may be inadequate for screening chemicals that require activation to exert toxicity. Metabolic competence is greatly improved using three-dimensional (3D) cell culture. In this study, Cyp1a induction, and subsequent DNA damage response induced by benzo(a)pyrene (BaP) were compared in 2D monolayer cells and 3D spheroids of the chicken hepatic cell line, LMH. Cells were exposed to BaP (0.1-100 µM) for different durations: 8, 24, 35, or 48 hr. Cyp1a activity, mRNA expression of Cyp1a and DNA damage response (DDR) genes, and phosphorylation of H2AX (γH2AX) were determined using the EROD assay, a customized PCR array, and flow cytometry, respectively. EROD activity was induced at 8 hr and achieved maximal induction at 24 hr in spheroids; earlier time points than for monolayer cells. In spheroids, BaP exposure resulted in a concentration-dependent increase in Cyp1a4 mRNA expression at 8 hr followed by upregulation of DDR genes at 24 hr, whereas Cyp1a4 mRNA induction was only observed at 48 hr in monolayer cells. Cyp1a5 mRNA was induced at 8 hr in monolayer cells but maximum induction was greater in spheroids. An increase in γH2AX was observed at 24 hr in spheroids; this endpoint was not evaluated in monolayer cells. These results suggest that BaP metabolism precedes the DNA damage response and occurs earlier in 3D spheroids. This study demonstrates that LMH 3D spheroids could be a suitable metabolically-competent in vitro model to measure genotoxicity of chemicals that require metabolic activation by Cyp1a.

Characteristics of patients who had a stroke not initially identified during emergency prehospital assessment: a systematic review.

BACKGROUND: Around 25% of patients who had a stroke do not present with typical 'face, arm, speech' symptoms at onset, and are challenging for emergency medical services (EMS) to identify. The aim of this systematic review was to identify the characteristics of acute stroke presentations associated with inaccurate EMS identification (false negatives). METHOD: We performed a systematic search of MEDLINE, EMBASE, CINAHL and PubMed from 1995 to August 2020 using key terms: stroke, EMS, paramedics, identification and assessment. Studies included: patients who had a stroke or patient records; ≥18 years; any stroke type; prehospital assessment undertaken by health professionals including paramedics or technicians; data reported on prehospital diagnostic accuracy and/or presenting symptoms. Data were extracted and study quality assessed by two researchers using the Quality Assessment of Diagnostic Accuracy Studies V.2 tool. RESULTS: Of 845 studies initially identified, 21 observational studies met the inclusion criteria. Of the 6934 stroke and Transient Ischaemic Attack patients included, there were 1774 (26%) false negative patients (range from 4 (2%) to 247 (52%)). Commonly documented symptoms in false negative cases were speech problems (n=107; 13%-28%), nausea/vomiting (n=94; 8%-38%), dizziness (n=86; 23%-27%), changes in mental status (n=51; 8%-25%) and visual disturbance/impairment (n=43; 13%-28%). CONCLUSION: Speech problems and posterior circulation symptoms were the most commonly documented symptoms among stroke presentations that were not correctly identified by EMS (false negatives). However, the addition of further symptoms to stroke screening tools requires valuation of subsequent sensitivity and specificity, training needs and possible overuse of high priority resources.

Predictors of recognition of out of hospital cardiac arrest by emergency medical services call handlers in England: a mixed methods diagnostic accuracy study.

BACKGROUND: The aim of this study was to identify key indicator symptoms and patient factors associated with correct out of hospital cardiac arrest (OHCA) dispatch allocation. In previous studies, from 3% to 62% of OHCAs are not recognised by Emergency Medical Service call handlers, resulting in delayed arrival at scene. METHODS: Retrospective, mixed methods study including all suspected or confirmed OHCA patients transferred to one acute hospital from its associated regional Emergency Medical Service in England from 1/7/2013 to 30/6/2014. Emergency Medical Service and hospital data, including voice recordings of EMS calls, were analysed to identify predictors of recognition of OHCA by call handlers. Logistic regression was used to explore the role of the most frequently occurring (key) indicator symptoms and characteristics in predicting a correct dispatch for patients with OHCA. RESULTS: A total of 39,136 dispatches were made which resulted in transfer to the hospital within the study period, including 184 patients with OHCA. The use of the term 'Unconscious' plus one or more of symptoms 'Not breathing/Ineffective breathing/Noisy breathing' occurred in 79.8% of all OHCAs, but only 72.8% of OHCAs were correctly dispatched as such. 'Not breathing' was associated with recognition of OHCA by call handlers (Odds Ratio (OR) 3.76). The presence of key indicator symptoms 'Breathing' (OR 0.29), 'Reduced or fluctuating level of consciousness' (OR 0.24), abnormal pulse/heart rate (OR 0.26) and the characteristic 'Female patient' (OR 0.40) were associated with lack of recognition of OHCA by call handlers (p-values < 0.05). CONCLUSIONS: There is a small proportion of calls in which cardiac arrest indicators are described but the call is not dispatched as such. Stricter adherence to dispatch protocols may improve call handlers' OHCA recognition. The existing dispatch protocol would not be improved by the addition of further terms as this would be at the expense of dispatch specificity.

Glucagon-like peptide-1 receptor agonists as neuroprotective agents for ischemic stroke: a systematic scoping review.

Stroke mortality and morbidity is expected to rise. Despite considerable recent advances within acute ischemic stroke treatment, scope remains for development of widely applicable neuroprotective agents. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), originally licensed for the management of Type 2 Diabetes Mellitus, have demonstrated pre-clinical neuroprotective efficacy in a range of neurodegenerative conditions. This systematic scoping review reports the pre-clinical basis of GLP-1RAs as neuroprotective agents in acute ischemic stroke and their translation into clinical trials. We included 35 pre-clinical studies, 11 retrospective database studies, 7 cardiovascular outcome trials and 4 prospective clinical studies. Pre-clinical neuroprotection was demonstrated in normoglycemic models when administration was delayed by up to 24 h following stroke induction. Outcomes included reduced infarct volume, apoptosis, oxidative stress and inflammation alongside increased neurogenesis, angiogenesis and cerebral blood flow. Improved neurological function and a trend towards increased survival were also reported. Cardiovascular outcomes trials reported a significant reduction in stroke incidence with semaglutide and dulaglutide. Retrospective database studies show a trend towards neuroprotection. Prospective interventional clinical trials are on-going, but initial indicators of safety and tolerability are favourable. Ultimately, we propose that repurposing GLP-1RAs is potentially advantageous but appropriately designed trials are needed to determine clinical efficacy and cost-effectiveness.

Medication-taking after stroke: a qualitative meta-synthesis of the perspectives of stroke survivors, informal carers and health professionals.

BACKGROUND: Lifelong secondary prevention medication is recommended after stroke or transient ischaemic attack. However, poor medication adherence and persistence, which lead to suboptimal health outcomes, are common, but the reasons for this are not well understood, mainly because there have been few studies reporting adherence barriers in stroke survivors. OBJECTIVE: The aim of this review was to undertake a meta-synthesis of qualitative studies of medication-taking after stroke. Outcomes of interest were: lived experiences, views and beliefs, and strategies and solutions used by community-dwelling stroke and transient ischaemic attack survivors, informal carers and health care professionals in relation to medication-taking. METHOD: The review protocol was registered on PROSPERO (CRD42018086792). A search of online bibliographic databases was performed using key search terms of stroke, persistence, adherence and medication for years 1980-2018. Citation tracking was also carried out. Studies using qualitative or mixed methods were included. Systematic data extraction and synthesis were conducted using a meta-ethnographic approach. RESULTS: Twelve studies were eligible for inclusion, with a total of 412 participants, two-thirds of whom were stroke survivors, ranging from 1 month to over 20 years post-stroke. Third-order themes identified were 'Medicines Work'-Information Work; Health Care Work; Carer Work; Emotional Work; Practical Work and an underpinning theme of Trust. However, many studies had significant methodological weaknesses. CONCLUSIONS: This synthesis suggests that the burden of 'medicines work' after stroke is substantial and multifaceted. Its successful undertaking depends on mutual trust between stroke survivors, carers and health care professionals and trust in the benefits of medicines themselves.

Healthcare practitioners' views and experiences of barriers and facilitators to weight management interventions for adults with intellectual disabilities.

BACKGROUND: Obesity is common in adults with intellectual disabilities, yet little is known about how weight management interventions are provided for this population. METHODS: Semi-structured interviews were held with 14 healthcare practitioners involved in weight management interventions in an English county. A study topic guide was developed to elicit practitioners' views and experiences of barriers and facilitators to weight management for adults with intellectual disabilities. Responses were analysed using thematic analysis. RESULTS: Several barriers are involved in weight management for people with intellectual disabilities including communication challenges, general practitioners' lack of knowledge and awareness of weight management services, inconsistencies in caring support, resource constraints, wider external circumstances surrounding the individuals and motivational issues. Facilitators include reasonable adjustments to existing weight management services. However, there is a need for specialist weight management provision for people with intellectual disabilities. CONCLUSIONS: This study provides suggestions for future research, policy and practice consideration.

Prioritization of 10 organic flame retardants using an avian hepatocyte toxicogenomic assay.

As the number of chemicals developed and used by industry increases, the inherent limitations of traditional toxicology approaches become an unavoidable issue. To help meet the demand for toxicity evaluation, new methods, such as high-throughput toxicity screening, are currently being developed to permit rapid determination of toxic, molecular, and/or biochemical effects of a wide range of chemicals. In the present study, we demonstrate the utility of an avian in vitro toxicogenomics screening approach to determine the cytotoxic and transcriptomic effects of 10 organic flame retardants (OFRs) currently of international priority for ecological risk evaluation to prioritize and inform future toxicological studies. Hepatocytes from 2 avian species, chicken and double-crested cormorant, were prepared and exposed for 24 h to various concentrations (0-300 µM) of the following 10 OFRs: Chemical Abstracts Service registration numbers 29761-21-5, 56803-37-3 (p-tert-butylphenyl diphenyl phosphate [BPDP]), 65652-41-7, 68937-41-7 (phenol, isopropylated, phosphate [3:1] [IPPP]), 95906-11-9, 19186-97-1, 26040-51-7, 35948-25-5, 21850-44-2, and 25713-60-4. Cell viability, the 7-ethoxyresorufin-O-deethylase assay, and transcriptomic analysis using species-specific ToxChip polymerase chain reaction arrays were performed to evaluate the in vitro effect of these OFRs. Of the 10 OFRs assessed, BPDP and IPPP elicited the strongest cytotoxic and transcriptomic responses in both chicken and double-crested cormorant hepatocytes and are therefore recommended as priority candidates for further wildlife toxicological investigations. Environ Toxicol Chem 2018;37:3134-3144. © 2018 Crown in the right of Canada. Published by Wiley Periodicals Inc. on behalf of SETAC.

An integrative review of multicomponent weight management interventions for adults with intellectual disabilities.

BACKGROUND: Obesity is more prevalent in people with intellectual disabilities and increases the risk of developing serious medical conditions. UK guidance recommends multicomponent weight management interventions (MCIs), tailored for different population groups. METHODS: An integrative review utilizing systematic review methodology was conducted to identify the types of MCIs delivered to adults with intellectual disabilities. FINDINGS: Five studies were identified. All of the studies' MCIs were tailored for adults with intellectual disabilities. Tailoring included measures such as simplified communication tools, individualized sessions, and the presence of carers where appropriate. CONCLUSIONS: Emerging evidence suggests ways in which MCIs can be tailored for adults with intellectual disabilities but, given the few studies identified, it is not possible to recommend how they can be routinely tailored. Further studies are justified for adults with intellectual disabilities at risk of obesity-related conditions.

The impact of education and training interventions for nurses and other health care staff involved in the delivery of stroke care: An integrative review.

OBJECTIVES: The aim of this review was to explore the impact of stroke education and training of nurses and other health care staff involved in the delivery of stroke care. DESIGN: We performed an integrative review, following PRISMA guidance where possible. DATA SOURCES: We searched MEDLINE, ERIC, PubMed, AMED, EMBASE, HMIC, CINAHL, Google Scholar, IBSS, Web of Knowledge, and the British Nursing Index from 1980 to 2016. REVIEW METHODS: Any intervention studies were included if they focused on the education or training of nurses and other health care staff in relation to stroke care. Articles that appeared to meet the inclusion criteria were read in full. Data were extracted from the articles, and the study quality assessed by two researchers. We assessed risk of bias of included studies using a pre-specified tool based on Cochrane guidance. RESULTS: Our initial search identified 2850 studies of which 21 met the inclusion criteria. Six studies were randomised controlled trials, and one was an interrupted time series. Fourteen studies were quasi-experimental: eight were pretest-posttest; five were non-equivalent groups; one study had a single assessment. Thirteen studies used quality of care outcomes and eight used a patient outcome measure. None of the studies was identified as having a low risk of bias. Only nine studies used a multi-disciplinary approach to education and training and nurses were often taught alone. Interactive education and training delivered to multi-disciplinary stroke teams, and the use of protocols or guidelines tended to be associated with a positive impact on patient and quality of care outcomes. CONCLUSIONS: Practice educators should consider the delivery of interactive education and training delivered to multi-disciplinary groups, and the use of protocols or guidelines, which tend to be associated with a positive impact on both patient and quality of care outcomes. Future research should incorporate a robust design.

Catbirds are the New Chickens: High Sensitivity to a Dioxin-like Compound in a Wildlife Species.

Dioxins and dioxin-like compounds (DLCs) are highly toxic and persistent global pollutants with extremely large differences in sensitivity across taxonomic groups. The chicken has long been considered uniquely sensitive to DLCs among avian species; but DLC toxicity in nondomesticated birds is largely untested, and the relevance of the chicken as an ecological model is uncertain. New approaches that use genotyping of the AHR1 ligand binding domain to screen for DLC sensitivity among avian species predicted that the gray catbird, a relevant wildlife species, is also highly sensitive. We tested this prediction using egg injections of a dioxin-like PCB (PCB-126) and found that the catbird is at least as sensitive as the chicken to DLCs, based on both embryotoxicity and mRNA induction of phase I metabolizing enzymes (CYP1A4/5). This study is the first to confirm that there are wildlife species as sensitive as the chicken and demonstrates how using predictive genotyping methods and targeted bioassays can focus toxicity assessments on ecologically relevant species.

Time-dependent transcriptomic and biochemical responses of 6-formylindolo[3,2-b]carbazole (FICZ) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are explained by AHR activation time.

6-Formylindolo[3,2-b]carbazole (FICZ) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are ligands of the aryl hydrocarbon receptor (AHR) and bind to the AHR with high affinity. Until recently, TCDD was considered to be the most potent AHR agonist, but several recent studies indicate that FICZ binds with greater affinity to the AHR than TCDD. To advance our understanding of the similarities and differences of the effects of FICZ and TCDD exposure in chicken embryo hepatocyte (CEH) cultures, we compared relative expression changes of 27 dioxin-responsive genes by the use of a chicken PCR array, porphyrin accumulation and ethoxyresorufin-O-deethylase (EROD) activity at different time points. In addition, an egg injection study was performed to assess the effects of FICZ on the developing chicken embryo. The results of the current study showed: (1) mean EROD-derived relative potency values for FICZ compared to TCDD changed as a function of time (i.e. 9, 0.004, 0.0008 and 0.00008 at 3, 8, 24, and 48h, respectively) in CEH cultures; (2) FICZ exposure did not result in porphyrin accumulation in CEH cultures; (3) concordance between gene expression profiles for FICZ and TCDD was time- and concentration-dependent, and (4) no mortality or morphological abnormalities were observed in chicken embryos injected with 0.87ng FICZ/g egg into the air cell. The results presented herein suggest that while FICZ and TCDD share similar molecular targets, transient versus sustained AHR activation by FICZ and TCDD result in differential transcriptomic responses. Moreover, rapid metabolism of FICZ in hepatocytes resulted in a significant decrease in the induction of EROD activity.

Use of a Novel Double-Crested Cormorant ToxChip PCR Array and the EROD Assay to Determine Effects of Environmental Contaminants in Primary Hepatocytes.

In vitro screening tools and 'omics methods are increasingly being incorporated into toxicity studies to determine mechanistic effects of chemicals and mixtures. To date, the majority of these studies have been conducted with well-characterized laboratory animal models. In the present study, well-established methods developed for chicken embryonic hepatocyte (CEH) studies were extended to a wild avian species, the double-crested cormorant (DCCO; Phalacrocorax auritus), in order to compare the effects of several environmental contaminants on cytotoxicity, ethoxyresorufin O-deethylase (EROD) activity, and mRNA expression. Five organic flame retardants and one plasticizer decreased cormorant hepatocyte viability in a similar manner to that observed in previous studies with CEH. EROD activity was induced in a concentration-dependent manner following exposure to two dioxin-like chemicals and the calculated EC50 values were concordant with domestic avian species from similar species sensitivity categories. Transcriptomic effects were determined using a novel DCCO PCR array, which was designed, constructed and validated in our laboratory based on a commercially available chicken PCR array. The DCCO array has 27 target genes covering a wide range of toxicity pathways. Gene profiles were variable among the 10 chemicals screened; however, good directional concordance was observed with regard to results previously obtained in CEH. Overall, the application of well-established methods (i.e., CEH and chicken PCR array) to the double-crested cormorant demonstrated the portability of the techniques to an indicator species of ecological relevance.

Feathers as a source of RNA for genomic studies in avian species.

Dioxins and dioxin-like chemicals (DLCs) cause a suite of adverse effects in terrestrial species. Most of the adverse effects occur subsequent to binding to the aryl hydrocarbon receptor. Avian species vary in their sensitivity to the effects of DLCs and current research indicates that this is mediated by variations in the amino acid sequence within the ligand binding domain (LBD) of the aryl hydrocarbon receptor 1 (AHR1). Eighty-eight avian species have been classified into three broad categories of sensitivity, based on the amino acid variations within the AHR1 LBD: sensitive type 1 (Ile324_Ser380), moderately sensitive type 2 (Ile324_Ala380), and relatively insensitive type 3 (Val324_Ala380). Risk assessment of avian species can be complicated due to the variability in sensitivity among species. A predictive tool for selecting the priority species at a given site would have broad implications for the risk assessment community. We present a method for AHR1 genotyping using plucked feathers as a source of RNA. The method is extremely robust, requires minimal sample processing and handling, and eliminates the need for blood sampling or tissue collection from the species of interest. Using this method we were able to determine the amino acid sequence of the AHR LBD of three avian species: the chicken, the herring gull, and the zebra finch, and to categorize them based on the identity of amino acids at key sites within the LBD.

Amino acid sequence of the AhR1 ligand-binding domain predicts avian sensitivity to dioxin like compounds: in vivo verification in European starlings.

Research has demonstrated that the sensitivity of avian species to the embyrotoxic effects of dioxin-like compounds can be predicted by the amino acid identities at two key sites within the ligand-binding domain of the aryl hydrocarbon receptor 1 (AhR1). The domestic chicken (Gallus gallus domesticus) has been established as a highly sensitive species to the toxic effects of dioxin-like compounds. Results from genotyping and in vitro assays predict that the European starling (Sturnus vulgaris) is also highly sensitive to dioxin-like compound toxicity. The objective of the present study was to test that prediction in vivo. To do this, we used egg injections in field nesting starlings with 3,3',4,4',5-pentachlorobiphenyl (PCB-126), a dioxin-like polychlorinated biphenyl. Eggs were dosed with either the vehicle control or 1 of 5 doses (1.4, 7.1, 15.9, 32.1, and 52.9 ng PCB-126/g egg). A dose-dependent increase in embryo mortality occurred, and the median lethal dose (LD50; 95% confidence interval [CI]) was 5.61 (2.33-9.08) ng/g. Hepatic CYP1A4/5 messenger RNA (mRNA) expression in hatchlings also increased in a dose-dependent manner, with CYP1A4 being more induced than CYP1A5. No effect of dose on morphological measures was seen, and we did not observe any overt malformations. These results indicate that, other than the chicken, the European starling is the most sensitive species to the effects of PCB-126 on avian embryo mortality reported to date, which supports the prediction of relative sensitivity to dioxin-like compounds based on amino acid sequence of the AhR1.

Ethoxyresorufin-O-deethylase (EROD) induction by TCDD, PeCDF and PCB 126 in bobwhite quail hepatocytes.

World Health Organization (WHO) toxic equivalency factors are used to calculate toxic equivalent (TEQ) concentrations of complex mixtures of dioxin-like compounds (DLCs), such as polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls (PCBs), for mammals, fish and birds. The TEQ concept assumes that all species of a taxa respond with similar sensitivity to individual DLCs, but several reports do not support this assumption for birds. Our laboratory is conducting research to attempt to uncover the fundamental mechanism(s) underlying the reasons why avian species differ in sensitivity to DLCs. The present study determined concentration-dependent effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 3,3',4,4',5-pentachlorobiphenyl (PCB 126) on ethoxyresorufin-O-deethylase (EROD) activity in primary cultures of northern bobwhite quail (Colinus virginianus) hepatocytes. Bobwhite quail were studied because (1) this species is used in the laboratory for toxicity testing and (2) the amino acids at all locations within the ligand binding domain (LBD) of aryl hydrocarbon receptor 1 (AHR1) in bobwhite quail and ring necked pheasant (Phasianus colchicus) are identical. Because earlier work indicated the importance of the identity of amino acids at key sites within the AHR1 LBD, we hypothesized that bobwhite quail and ring necked pheasant hepatocytes should have similar sensitivity to EROD induction by DLCs. ECthreshold-based relative sensitivity of the bobwhite quail compared to chicken for TCDD, PeCDF and PCB 126 was 0.11, 0.17 and 0.02, respectively. The rank order of potency was PeCDF > TCDD > PCB 126. The results confirm that bobwhite quail and ring-necked pheasant hepatocytes have similar sensitivity to EROD induction by TCDD, PeCDF and PCB 126.