Vesicourachal diverticulum.

We report a rare complication involving a healthy 45-year-old male patient who underwent an emergency laparoscopic appendicectomy for acute perforated gangrenous appendicitis. The patient was catheterised pre- procedure and the ports were inserted under vision. Upon completion of the procedure, a 15 Fr Robinson drain was left in the pelvis and was fed through the suprapubic port hole. Postoperatively the patient developed worsening, generalised abdominal pain and high output from the drain. The patient was re-catheterised but the computed tomography (CT) cystogram did not show any injury to the bladder. The drain fluid creatinine was noted to be raised (>4,000), indicating that urine was leaking into the drain. Conventional cystogram confirmed a contrast leak from the dome around the drain. Flexible cystoscopy confirmed that the drain had transversed the vesicourachal diverticula. The drain was pulled back and converted to a suprapubic catheter with the patient subsequently being discharged. Vesicourachal diverticula is a rare and often asymptomatic anomaly. When undertaking laparoscopic surgery, precautions should be taken to prevent port site injury such as catheterising the patient to ensure the bladder is empty and inserting the ports under direct vision. It is safer to visualise muscle rather than peritoneum during port insertion. In this case, the bladder diverticula was noticed extraperitoneally. Though the indirect CT cystogram reported no injury, this was unreliable as the bladder was not distended which led to the subtle injury being missed. Traditional cystogram should be considered in cases with a negative CT cystogram and a strong suspicion of bladder injury.

Building momentum for local action on problem gambling in Leeds and Yorkshire.

Problem gambling has not been a priority within either Leeds City Council or partnership plans. However, financial inclusion, licencing and public health teams have been able to develop a cross-Council approach to problem gambling. This has been aided by an upfront payment plus annual payments to the Council that have been part of the licencing agreement for a new casino. As a result, research has been commissioned on local prevalence. This showed a higher rate of problem gamblers (1.8%) than national estimates with a similar level to nationally of those 'at risk'. The research also showed that local services had difficulties identifying problem gamblers and signposting for support. This had led to a high profile communications campaign to coincide with 'Responsible Gambling Week' complemented by training for frontline workers. The interviews undertaken for the research, plus the findings themselves, have been a powerful help in securing interest and commitment beyond the Council and to the health and third sectors. The use of local stories has helped build momentum for partnership working. For example, focus groups to explore how gambling affected migrants and medical student interviews with university students. The article will describe how increasing understanding across partners has helped build confidence to provide cross city responses to national consultations and contribute to national publications and conferences. Of even greater significance, the local National Health Service has secured funding from GambleAware for a Northern Gambling Service to be based in Leeds with satellites in the North East and Greater Manchester. This will provide treatment for those with severe gambling addiction. Additional support will come from a significant increased provision of GamCare services working to identify, screen and support problem gamblers. The use of Council premises for both of these services is testament to joint working. Recognising that this is a new emerging agenda has led to the creation of a Yorkshire and Humber Problem Gambling Working Group, endorsed by the Association of Directors of Public Health. This has resulted in shared learning and determining a consistent approach to harm. Even during a short time, the degree of interest has risen substantially. A regional gambling harm reduction framework has been produced that sets out a menu of actions. This intends to help local areas determine their own priorities. There is increasing recognition that problem gambling is a public health issue. Leadership requires a systems led, and Health in All Policies, approach to ensure problem gambling is not seen as a narrow niche issue led by public health staff. There is a need to recognise that engagement takes time. However, this is a new and emerging issue. The solutions to problem gambling are not clear and this allows for more creative, pragmatic and coproduced approaches.

Two-step hybrid calibration of remote microphones.

A two-step, hybrid procedure to calibrate the remote microphones is presented. The calibration obtained in this manner can be directly applied to the measured pressure spectrum without resorting to any modeling or assumptions about the shape of the calibration curve. To demonstrate an application of the methodology, measurements of wall pressure fluctuations underneath a zero pressure gradient turbulent boundary layer were made. The calibrated pressure spectrum is shown to be qualitatively and quantitatively consistent with previous experimental studies and an empirical model, indicating the accuracy of the hybrid calibration technique.

Clinical Audit of Sexual Abuse Referral Forms to the Sexual Assault Follow-up and Evaluation Clinic, Nassau, The Bahamas, among Females Aged 13 to 19 Years / Auditoría clínica de los formularios de remisión de abuso sexual a la Clínica de Evaluación y Seguimiento de Agresiones Sexuales, Nassau, Bahamas, entre mujeres de 13 a 19 años

ABSTRACT Objective: To evaluate the adequacy of the documentation of referral forms for sexually abused females aged 13-19 years directed to the Sexual Assault Follow-up and Evaluation (SAFE) Clinic at the Agape Family Medicine Clinic, Nassau, The Bahamas, for interim management. Methods: An approved review was performed on 123 referral forms regarding sexually abused females aged 13-19 years who attended the SAFE Clinic from 2011 to 2015. The exercise focussed on documentation adequacy based on a scoring system developed by the researchers (> 50% was assessed to be adequate; records of the referee's disposition of the patient, the date of the incident and evidence of sexually transmitted infection (STI) screening were considered vital for adequacy). Descriptive and inferential statistics were calculated. Results: The median age of the participants was 14 years (interquartile range: 13-15). Of the 63.4% (78) with documented nationality, 88.5% (69) were Bahamian and 11.5% (9) Haitian. Documentation status did not differ statistically significantly by nationality. Regarding documentation, 74% (91) recorded the name of the patient's school, 59.3% (73) recorded that the patient knew the assailant and 17.9% (22) indicated that the patient did not know the assailant, while 22.8% (28) did not document this latter information. Type of sexual penetration was indicated by 65.9% (81). Of the vital variables, 18.7% (23) recorded the referee's disposition of the patient, 29.8% (36) the date of the incident and 60.2% (74) evidence of STI screening; 7.3% (9) documented all three and 22.8% (28) two. The mean percentage of documentation for vital variables was 49.3% (± 3.6) for the Accident and Emergency (A&E) Department, Princess Margaret Hospital, Nassau, versus 30.5% (± 4.0) for public health clinics (PHCs) (p = 0.001). Overall, 69.9% (86 of 123) of the referral forms were deemed inadequate: 64.7% (33 of 51) from the A&E Department versus 73.4% (47 of 64) from PHCs among the 115 patients who provided referral information. Conclusion: Documentation deficiencies of the sexual abuse referral forms demand reform. Complete and consistent documentation is required.

RESUMEN Objetivo: Evaluar la idoneidad de la documentación de los formularios de remisión para mujeres de 13 a 19 años sexualmente abusadas, dirigidas a la Clínica de Evaluación y Seguimiento de Agresiones Sexuales (ESAS) en la Clínica Ágape de Medicina Familiar, Nassau, Bahamas, para la administración interina. Métodos: Se aprobó una revisión para examinar 123 formularios de remisión con respecto a las mujeres de 13 a 19 años sexualmente abusadas, que asistieron a la clínica de ESAS de 2011 a 2015. El ejercicio se centró en la idoneidad de la documentación basada en un sistema de puntuación desarrollado por los investigadores (50% fue adecuado según la valoración; los registros de la disposición de la paciente en el arbitraje, la fecha del incidente y la evidencia del tamizaje de la infección de transmisión sexual (ITS), fueron todos vitales a la hora de determinar la idoneidad). Se calcularon las estadísticas descriptivas e inferenciales. Resultados: La edad promedio de las participantes fue 14 años (rango intercuartil: 13-15). De 63.4% (78) con nacionalidad documentada, el 88.5% (69) fueron bahameñas y el 11.5% (9) haitianas. El estado de la documentación en término de las estadísticas no difirió significativamente por nacionalidad. Con respecto a la documentación, el 74% (91) registró el nombre de la escuela de la paciente, 59.3% (73) registró que la paciente conocía al agresor, y el 17.9% (22) indicó que la paciente no conocía al agresor, mientras que el 22.8% (28) no documentó esta última información. El tipo de penetración sexual fue indicado por 65.9% (81). De las variables vitales, 18.7% (23) registró la disposición de la paciente en el arbitraje, 29.8% (36) la fecha del incidente, y el 60.2% (74) evidencia del tamizaje de las ITS; 7.3% (9) documentó tres de ellas y 2.8% (28) dos. El porcentaje medio de documentación de las variables vitales fue 49.3% (± 3.6) para el Departamento de Accidentes y Emergencias (A&E), Hospital Princess Margaret, Nassau, frente al 30.5% (± 4.0) de las clínicas de salud pública (CSP) (p = 0.001). En general, el 69.9% (86 de 123) de los formularios de referencia se consideró inadecuado: 64.7% (33 de 51) del Departamento de A&E frente al 73.4% (47 de 64) de las CSP entre las 115 pacientes que proporcionaron la información de la remisión. Conclusión: Las deficiencias de la documentación de los formularios de remisión de abuso sexual exigen reformas. Se requiere una documentación completa y consistente.

The HLA-C*05 family allele - C*05:142.

The sequencing of exons 2-7 of a likely new HLA-C*05 allele identified the second example of HLA-C*05:142, in a male UK European, within a few months of the first example being found in Germany. C*05:142 differs from C*05:01:01:01 by a single base (395G>C) in exon 3 resulting in an amino acid substitution of R108P. Comprehensive serological HLA-Cw5 typing, using 19 antisera, indicated that C*05:142 encodes a "normal" Cw5 specificity. Failure to identify the involvement of position 108 in published HLA-C epitopes supported this assertion. The likely HLA class I C*05:142-bearing haplotype is A*02:01~C*05:142~B*44:02. This new allele has a maximum frequency of 0.00001, in 34,743 sequenced-based typed subjects, contrasting with that of C*05:01 (allele frequency 0.10441), in our local, largely UK European, blood donors.

HLA-A*24:374-A novel allele encoding the HLA-A2403 specificity.

HLA-A*24:374 differs from A*24:03:01:01 by 2 exon 3 bases resulting in a substitution of T163E.

Helping palliative care healthcare professionals get the most out of mentoring in a low-income country: a qualitative study.

BACKGROUND: Being a mentor in any setting brings challenges in addition to recognised benefits. Working in a low-income country confers specific challenges including logistical and communication issues. The need to adequately support UK-based international health volunteers prior to, during and after their trip is recognised at government level. Whilst the need to support mentors is recognised little is known about their support needs. This study aims to explore the lived experience of mentorship in a low-income country and gain insight into mentors' support and information needs and the barriers and facilitators to mentoring. METHODS: Purposive sampling was used to recruit UK-employed, palliative care clinicians: four consultants, two specialty trainees, and two nurses, who were mentors with an international palliative care project. Semi-structured telephone interviews were recorded and analysed using interpretive phenomenological analysis. RESULTS: Participants became mentors to help others. Uncertainty about their achievements constituted a significant challenge. This study highlights the need to prepare mentors before their in-country visits by exploring motivation, describing the reality of international volunteering and ensuring realistic expectations. Post-trip debriefing is important for reducing uncertainty around trip outcomes and maximising transferable impacts. Challenges to mentoring were logistical, related to the concept of mentorship and cultural. Facilitators included shared passion, mentor credibility and serendipity. CONCLUSION: Awareness of the support needs of mentors and the facilitators and challenges to mentoring can improve mentor preparation and support. This may minimise potential negative emotional impact of being a mentor, maximise positive personal and professional impacts and improve in-country project impact.

Immunological characterization of the aryl hydrocarbon receptor (AHR) knockout rat in the presence and absence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

The aryl hydrocarbon receptor (AHR) has been extensively characterized for the essential role it plays in mediating the toxic responses elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Despite similarities across animal species, species-specific differences exist in the profile of toxicity and sensitivity to TCDD owing, in part, to differences in the AHR. Newer reports have implicated the importance of AHR in the development and regulation of the immune system. Our present studies seek to further explore the essential role of AHR in lymphoid tissue composition, B cell function and the immunological responses after TCDD administration using the recently established AHR KO rats. Comprehensive immune cell phenotyping showed a decrease in the CD8+ T cell, CD11c+ populations and an increase in NKT cells in 3-week-old AHR KO rats compared to the WT controls. The lipopolysaccharide-induced IgM response and proliferation was markedly suppressed in the WT but not in the AHR KO B cells in the presence of TCDD. However, the percentage of LPS-activated IgM+ B cells was significantly higher in the AHR KO B cells as compared to that of WT suggesting the role of AHR in regulating the IgM response. The use of an AHR antagonist further alluded to the endogenous role of AHR in regulating B cell responses in the rat. Overall, the studies report for the first time, comprehensive immune cell phenotyping of the AHR KO rat and the endogenous role of AHR in the regulation of B cell function in the rat.

Adverse outcome pathways: From research to regulation scientific workshop report.

An adverse outcome pathway (AOP) helps to organize existing knowledge on chemical mode of action, starting with a molecular initiating event such as receptor binding, continuing through key events, and ending with an adverse outcome such as reproductive impairment. AOPs can help identify knowledge gaps where more research is needed to understand the underlying mechanisms, aid in chemical hazard characterization, and guide the development of new testing approaches that use fewer or no animals. A September 2014 workshop in Bethesda, Maryland considered how the AOP concept could improve regulatory assessments of chemical toxicity. Scientists from 21 countries, representing industry, academia, regulatory agencies, and special interest groups, attended the workshop, titled Adverse Outcome Pathways: From Research to Regulation. Workshop plenary presentations were followed by breakout sessions that considered regulatory acceptance of AOPs and AOP-based tools, criteria for building confidence in an AOP for regulatory use, and requirements to build quantitative AOPs and AOP networks. Discussions during the closing session emphasized a need to increase transparent and inclusive collaboration, especially with disciplines outside of toxicology. Additionally, to increase impact, working groups should be established to systematically prioritize and develop AOPs. Multiple collaborative projects and follow-up activities resulted from the workshop.

Aryl hydrocarbon receptor knockout rats are insensitive to the pathological effects of repeated oral exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Sustained activation of the aryl hydrocarbon receptor (AHR) is believed to be the initial key event in AHR receptor-mediated tumorigenesis in the rat liver. The role of AHR in mediating pathological changes in the liver prior to tumor formation was investigated in a 4-week, repeated-dose study using adult female wild-type (WT) and AHR knockout (AHR-KO) rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Beginning at 8 weeks of age, AHR-KO and WT rats were dosed by oral gavage with varying concentrations of TCDD (0, 3, 22, 100, 300 and 1000 ng kg(-1) day(-1) ). Lung, liver and thymus histopathology, hematology, serum chemistry and the distribution of TCDD in liver and adipose tissue were examined. Treatment-related increases in the severity of liver and thymus pathology were observed in WT, but not AHR-KO rats. In the liver, these included hepatocellular hypertrophy, bile duct hyperplasia, multinucleated hepatocytes and inflammatory cell foci. A loss of cellularity in the thymic cortex and thymic atrophy was observed. Treatment-related changes in serum chemistry parameters were also observed in WT, but not AHR-KO rats. Finally, dose-dependent accumulation of TCDD was observed primarily in the liver of WT rats and primarily in the adipose tissue of AHR-KO rats. The results suggest that AHR activation is the initial key event underlying the progression of histological effects leading to liver tumorigenesis following TCDD treatment. Copyright © 2015 John Wiley & Sons, Ltd.

Clinical audit of referrals for sexual abuse among females ages 13–19 years attending the Agape Family Medicine Clinic, Nassau, Bahamas, 2011–2015

OBJECTIVE: To evaluate the adequacy of the documentation of referrals for sexually abused females ages 13–19 years directed to the Agape Family Medicine Clinic for interim management. SUBJECTS AND METHODS: An approved review was performed on 123 referral forms regarding sexually abused females 13–19 years old who attended Agape’s Sexual Assault Follow-up and Evaluation (SAFE) clinic, Nassau, Bahamas. The exercise focussed on documentation adequacy based on a scoring system developed by the researchers: > 50% was assessed to be adequate, and recording disposition, date of incident and sexually transmitted infection (STI) screening was considered vital for adequacy. A current version of Statistical Package for the Social Sciences (IBM SPSS, v 21) generated descriptive and inferential statistics. RESULTS: Participants’ median age was 14 (IQR: 13, 15) years old. Of 63.4% (n = 78) with documented nationality, 88.5% (n = 69) were Bahamian and 11.5% (n = 9) Haitian. Documentation status did not differ statistically significantly by nationality. Regarding documentation, 74% (n =91) recorded school, 59.3% (n = 73) recorded knowing the assailant and 17.9% (n = 22) indicated not knowing. Approximately two-thirds (65.9%; n = 81) indicated penetration type; 18.7% recorded disposition, 29.8% (n =36) incident date and 60.2% STI screening; 7.3% (n = 9) documented all three and 22.8% (n = 28) two. Among public health clinics (PHCs), 45.3% (n = 29) did not indicate any of the three vital variables versus 7.8% (n = 4) for Accident and Emergency (A&E) referrals. Mean percent documentation for vital variables was 49.3 (± 3.6)%for A&E versus 30.5 (± 4.0)% for PHCs (p = 0.001). CONCLUSION: The deficient documentation status of referral forms demands the need for reform. Complete, consistent documentation is required.

The adverse outcome pathway for rodent liver tumor promotion by sustained activation of the aryl hydrocarbon receptor.

An Adverse Outcome Pathway (AOP) represents the existing knowledge of a biological pathway leading from initial molecular interactions of a toxicant and progressing through a series of key events (KEs), culminating with an apical adverse outcome (AO) that has to be of regulatory relevance. An AOP based on the mode of action (MOA) of rodent liver tumor promotion by dioxin-like compounds (DLCs) has been developed and the weight of evidence (WoE) of key event relationships (KERs) evaluated using evolved Bradford Hill considerations. Dioxins and DLCs are potent aryl hydrocarbon receptor (AHR) ligands that cause a range of species-specific adverse outcomes. The occurrence of KEs is necessary for inducing downstream biological responses and KEs may occur at the molecular, cellular, tissue and organ levels. The common convention is that an AOP begins with the toxicant interaction with a biological response element; for this AOP, this initial event is binding of a DLC ligand to the AHR. Data from mechanistic studies, lifetime bioassays and approximately thirty initiation-promotion studies have established dioxin and DLCs as rat liver tumor promoters. Such studies clearly show that sustained AHR activation, weeks or months in duration, is necessary to induce rodent liver tumor promotion--hence, sustained AHR activation is deemed the molecular initiating event (MIE). After this MIE, subsequent KEs are 1) changes in cellular growth homeostasis likely associated with expression changes in a number of genes and observed as development of hepatic foci and decreases in apoptosis within foci; 2) extensive liver toxicity observed as the constellation of effects called toxic hepatopathy; 3) cellular proliferation and hyperplasia in several hepatic cell types. This progression of KEs culminates in the AO, the development of hepatocellular adenomas and carcinomas and cholangiolar carcinomas. A rich data set provides both qualitative and quantitative knowledge of the progression of this AOP through KEs and the KERs. Thus, the WoE for this AOP is judged to be strong. Species-specific effects of dioxins and DLCs are well known--humans are less responsive than rodents and rodent species differ in sensitivity between strains. Consequently, application of this AOP to evaluate potential human health risks must take these differences into account.

A model for aryl hydrocarbon receptor-activated gene expression shows potency and efficacy changes and predicts squelching due to competition for transcription co-activators.

A stochastic model of nuclear receptor-mediated transcription was developed based on activation of the aryl hydrocarbon receptor (AHR) by 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and subsequent binding the activated AHR to xenobiotic response elements (XREs) on DNA. The model was based on effects observed in cells lines commonly used as in vitro experimental systems. Following ligand binding, the AHR moves into the cell nucleus and forms a heterodimer with the aryl hydrocarbon nuclear translocator (ARNT). In the model, a requirement for binding to DNA is that a generic coregulatory protein is subsequently bound to the AHR-ARNT dimer. Varying the amount of coregulator available within the nucleus altered both the potency and efficacy of TCDD for inducing for transcription of CYP1A1 mRNA, a commonly used marker for activation of the AHR. Lowering the amount of available cofactor slightly increased the EC50 for the transcriptional response without changing the efficacy or maximal response. Further reduction in the amount of cofactor reduced the efficacy and produced non-monotonic dose-response curves (NMDRCs) at higher ligand concentrations. The shapes of these NMDRCs were reminiscent of the phenomenon of squelching. Resource limitations for transcriptional machinery are becoming apparent in eukaryotic cells. Within single cells, nuclear receptor-mediated gene expression appears to be a stochastic process; however, intercellular communication and other aspects of tissue coordination may represent a compensatory process to maintain an organism's ability to respond on a phenotypic level to various stimuli within an inconstant environment.

An exposure:activity profiling method for interpreting high-throughput screening data for estrogenic activity--proof of concept.

Rapid high throughput in vitro screening (HTS) assays are now available for characterizing dose-responses in assays that have been selected for their sensitivity in detecting estrogen-related endpoints. For example, EPA's ToxCast™ program recently released endocrine assay results for more than 1800 substances and the interagency Tox21 consortium is in the process of releasing data for approximately 10,000 chemicals. But such activity measurements alone fall short for the purposes of priority setting or screening because the relevant exposure context is not considered. Here, we extend the method of exposure:activity profiling by calculating the exposure:activity ratios (EARs) using human exposure estimates and AC50 values for a range of chemicals tested in a suite of seven estrogenic assays in ToxCast™ and Tox21. To provide additional context, relative estrogenic exposure:activity quotients (REEAQ) were derived by comparing chemical-specific EARs to the EAR of the ubiquitous dietary phytoestrogen, genistein (GEN). Although the activity of a substance in HTS-endocrine assays is not a measure of health hazard or risk, understanding how such a dose compares to human exposures provides a valuable additional metric that can be used in decision-making; substances with small EARs and REEAQs would indicate low priority for further endocrine screening or testing.

Proposing a scientific confidence framework to help support the application of adverse outcome pathways for regulatory purposes.

An adverse outcome pathway (AOP) describes the causal linkage between initial molecular events and an adverse outcome at individual or population levels. Whilst there has been considerable momentum in AOP development, far less attention has been paid to how AOPs might be practically applied for different regulatory purposes. This paper proposes a scientific confidence framework (SCF) for evaluating and applying a given AOP for different regulatory purposes ranging from prioritizing chemicals for further evaluation, to hazard prediction, and ultimately, risk assessment. The framework is illustrated using three different AOPs for several typical regulatory applications. The AOPs chosen are ones that have been recently developed and/or published, namely those for estrogenic effects, skin sensitisation, and rodent liver tumor promotion. The examples confirm how critical the data-richness of an AOP is for driving its practical application. In terms of performing risk assessment, human dosimetry methods are necessary to inform meaningful comparisons with human exposures; dosimetry is applied to effect levels based on non-testing approaches and in vitro data. Such a comparison is presented in the form of an exposure:activity ratio (EAR) to interpret biological activity in the context of exposure and to provide a basis for product stewardship and regulatory decision making.

A critical assessment of the methodologies to investigate the role of inhibition of apoptosis in rodent hepatocarcinogenesis.

Non-genotoxic carcinogens act by promoting the clonal expansion of preneoplastic cells by directly or indirectly stimulating cell division or inhibiting cell loss in the target organ. The specific mode-of-action (MoA) by which some non-genotoxic carcinogens ultimately cause cancer is not completely understood. To date, there are several proposed MoAs for non-genotoxic carcinogens, and some of these propose inhibition of apoptosis as one of the key events. In general, inhibition of apoptosis is considered a necessary step for cell survival and in theory can occur in combination or in association with other key promotional events, such as cell proliferation, oxidative stress and inhibition of intercellular communication to promote carcinogenesis. However, the evidence supporting the role of inhibition of apoptosis as a necessary step in promoting specific chemically induced tumors is often debated. To address this evidence, we reviewed studies that utilized prototypical nuclear receptor-mediated hepatocarcinogens. Based on this review, it is proposed that the ability to determine the importance of inhibition of apoptosis as a key event in the MoA for tumor promotion is hampered by the limitations of the methods utilized for its detection. This review provides an assessment of the strengths and limitations of the current methodology used for detection of apoptosis and provides suggestions for improving its detection, thereby strengthening the weight of evidence supporting inhibition of apoptosis as a key event in a MoA for tumor promotion.

Lineage-dependent effects of aryl hydrocarbon receptor agonists contribute to liver tumorigenesis.

UNLABELLED: Rodent cancer bioassays indicate that the aryl hydrocarbon receptor (AHR) agonist, 2,3,7,8-tetracholorodibenzo-p-dioxin (TCDD), causes increases in both hepatocytic and cholangiocytic tumors. Effects of AHR activation have been evaluated on rodent hepatic stem cells (rHpSCs) versus their descendants, hepatoblasts (rHBs), two lineage stages of multipotent, hepatic precursors with overlapping but also distinct phenotypic traits. This was made possible by defining the first successful culture conditions for ex vivo maintenance of rHpScs consisting of a substratum of hyaluronans and Kubota's medium (KM), a serum-free medium designed for endodermal stem/progenitor cells. Supplementation of KM with leukemia inhibitory factor elicited lineage restriction to rHBs. Cultures were treated with various AHR agonists including TCDD, 6-formylindolo-[3,2-b]carbazole (FICZ), and 3-3'-diindolylmethane (DIM) and then analyzed with a combination of immunocytochemistry, gene expression, and high-content image analysis. The AHR agonists increased proliferation of rHpSCs at concentrations producing a persistent AHR activation as indicated by induction of Cyp1a1. By contrast, treatment with TCDD resulted in a rapid loss of viability of rHBs, even though the culture conditions, in the absence of the agonists, were permissive for survival and expansion of rHBs. The effects were not observed with FICZ and at lower concentrations of DIM. CONCLUSION: Our findings are consistent with a lineage-dependent mode of action for AHR agonists in rodent liver tumorigenesis through selective expansion of rHpSCs in combination with a toxicity-induced loss of viability of rHBs. These lineage-dependent effects correlate with increased frequency of liver tumors.

A 21st century roadmap for human health risk assessment.

The Health and Environmental Sciences Institute (HESI)-coordinated Risk Assessment in the 21st Century (RISK21) project was initiated to develop a scientific, transparent, and efficient approach to the evolving world of human health risk assessment, and involved over 120 participants from 12 countries, 15 government institutions, 20 universities, 2 non-governmental organizations, and 12 corporations. This paper provides a brief overview of the tiered RISK21 framework called the roadmap and risk visualization matrix, and articulates the core principles derived by RISK21 participants that guided its development. Subsequent papers describe the roadmap and matrix in greater detail. RISK21 principles include focusing on problem formulation, utilizing existing information, starting with exposure assessment (rather than toxicity), and using a tiered process for data development. Bringing estimates of exposure and toxicity together on a two-dimensional matrix provides a clear rendition of human safety and risk. The value of the roadmap is its capacity to chronicle the stepwise acquisition of scientific information and display it in a clear and concise fashion. Furthermore, the tiered approach and transparent display of information will contribute to greater efficiencies by calling for data only as needed (enough precision to make a decision), thus conserving animals and other resources.

Risk assessment in the 21st century: roadmap and matrix.

Abstract The RISK21 integrated evaluation strategy is a problem formulation-based exposure-driven risk assessment roadmap that takes advantage of existing information to graphically represent the intersection of exposure and toxicity data on a highly visual matrix. This paper describes in detail the process for using the roadmap and matrix. The purpose of this methodology is to optimize the use of prior information and testing resources (animals, time, facilities, and personnel) to efficiently and transparently reach a risk and/or safety determination. Based on the particular problem, exposure and toxicity data should have sufficient precision to make such a decision. Estimates of exposure and toxicity, bounded by variability and/or uncertainty, are plotted on the X- and Y-axes of the RISK21 matrix, respectively. The resulting intersection is a highly visual representation of estimated risk. Decisions can then be made to increase precision in the exposure or toxicity estimates or declare that the available information is sufficient. RISK21 represents a step forward in the goal to introduce new methodologies into 21st century risk assessment. Indeed, because of its transparent and visual process, RISK21 has the potential to widen the scope of risk communication beyond those with technical expertise.

The use of mode of action information in risk assessment: quantitative key events/dose-response framework for modeling the dose-response for key events.

The HESI RISK21 project formed the Dose-Response/Mode-of-Action Subteam to develop strategies for using all available data (in vitro, in vivo, and in silico) to advance the next-generation of chemical risk assessments. A goal of the Subteam is to enhance the existing Mode of Action/Human Relevance Framework and Key Events/Dose Response Framework (KEDRF) to make the best use of quantitative dose-response and timing information for Key Events (KEs). The resulting Quantitative Key Events/Dose-Response Framework (Q-KEDRF) provides a structured quantitative approach for systematic examination of the dose-response and timing of KEs resulting from a dose of a bioactive agent that causes a potential adverse outcome. Two concepts are described as aids to increasing the understanding of mode of action-Associative Events and Modulating Factors. These concepts are illustrated in two case studies; 1) cholinesterase inhibition by the pesticide chlorpyrifos, which illustrates the necessity of considering quantitative dose-response information when assessing the effect of a Modulating Factor, that is, enzyme polymorphisms in humans, and 2) estrogen-induced uterotrophic responses in rodents, which demonstrate how quantitative dose-response modeling for KE, the understanding of temporal relationships between KEs and a counterfactual examination of hypothesized KEs can determine whether they are Associative Events or true KEs.