Heterogenous Populations of Tissue-Resident CD8+ T Cells Are Generated in Response to Infection and Malignancy.

Tissue-resident memory CD8+ T cells (Trm) provide host protection through continuous surveillance of non-lymphoid tissues. Using single-cell RNA-sequencing (scRNA-seq) and genetic reporter mice, we identified discrete lineages of intestinal antigen-specific CD8+ T cells, including a Blimp1hiId3lo tissue-resident effector cell population most prominent in the early phase of acute viral and bacterial infections and a molecularly distinct Blimp1loId3hi tissue-resident memory population that subsequently accumulated at later infection time points. These Trm populations exhibited distinct cytokine production, secondary memory potential, and transcriptional programs including differential roles for transcriptional regulators Blimp1, T-bet, Id2, and Id3 in supporting and maintaining intestinal Trm. Extending our analysis to malignant tissue, we also identified discrete populations of effector-like and memory-like CD8+ T cell populations with tissue-resident gene-expression signatures that shared features of terminally exhausted and progenitor-exhausted T cells, respectively. Our findings provide insight into the development and functional heterogeneity of Trm cells, which has implications for enhancing vaccination and immunotherapy approaches.

Id2 reinforces TH1 differentiation and inhibits E2A to repress TFH differentiation.

The differentiation of helper T cells into effector subsets is critical to host protection. Transcription factors of the E-protein and Id families are important arbiters of T cell development, but their role in the differentiation of the TH1 and TFH subsets of helper T cells is not well understood. Here, TH1 cells showed more robust Id2 expression than that of TFH cells, and depletion of Id2 via RNA-mediated interference increased the frequency of TFH cells. Furthermore, TH1 differentiation was blocked by Id2 deficiency, which led to E-protein-dependent accumulation of effector cells with mixed characteristics during viral infection and severely impaired the generation of TH1 cells following infection with Toxoplasma gondii. The TFH cell-defining transcriptional repressor Bcl6 bound the Id2 locus, which provides a mechanism for the bimodal Id2 expression and reciprocal development of TH1 cells and TFH cells.

Id3 expression identifies CD4+ memory Th1 cells.

Memory CD4+ T cells play a pivotal role in mediating long-term protective immunity, positioning them as an important target in vaccine development. However, multiple functionally distinct helper CD4+ T-cell subsets can arise in response to a single invading pathogen, complicating the identification of rare populations of memory precursor cells during the effector phase of infection and memory CD4+ T cells following pathogen clearance and the contraction phase of infection. Furthermore, current literature remains unclear regarding whether a single CD4+ memory T-cell lineage gives rise to secondary CD4+ T helper subsets or if there are unique memory precursor cells within each helper lineage. A majority of T follicular helper (Tfh) cells, which have established memory potential, express Id3, an inhibitor of E protein transcription factors, following acute viral infection. We show that expression of Id3 definitively identified a subset of cells within both the CD4+ Tfh and T helper 1 (Th1) lineages at memory time points that exhibited memory potential, with the capacity for significant re-expansion in response to secondary infection. Notably, we demonstrate that a subset of Th1 cells that survive into the memory phase were marked by Id3 expression and possessed the potential for enhanced expansion and generation of both Th1 and Tfh secondary effector cell populations in a secondary response to pathogen. Additionally, these cells exhibited enrichment of key molecules associated with memory potential when compared with Id3lo Th1 cells. Therefore, we propose that Id3 expression serves as an important marker to indicate multipotent potential in memory CD4+ T cells.

Ubiquitin Specific Protease 1 Expression and Function in T Cell Immunity.

T cells are essential mediators of immune responses against infectious diseases and provide long-lived protection from reinfection. The differentiation of naive to effector T cells and the subsequent differentiation and persistence of memory T cell populations in response to infection is a highly regulated process. E protein transcription factors and their inhibitors, Id proteins, are important regulators of both CD4+ and CD8+ T cell responses; however, their regulation at the protein level has not been explored. Recently, the deubiquitinase USP1 was shown to stabilize Id2 and modulate cellular differentiation in osteosarcomas. In this study, we investigated a role for Usp1 in posttranslational control of Id2 and Id3 in murine T cells. We show that Usp1 was upregulated in T cells following activation in vitro or following infection in vivo, and the extent of Usp1 expression correlated with the degree of T cell expansion. Usp1 directly interacted with Id2 and Id3 following T cell activation. However, Usp1 deficiency did not impact Id protein abundance in effector T cells or alter effector T cell expansion or differentiation following a primary infection. Usp1 deficiency resulted in a gradual loss of memory CD8+ T cells over time and reduced Id2 protein levels and proliferation of effector CD8+ T cell following reinfection. Together, these results identify Usp1 as a player in modulating recall responses at the protein level and highlight differences in regulation of T cell responses between primary and subsequent infection encounters. Finally, our observations reveal differential regulation of Id2/3 proteins between immune versus nonimmune cell types.

Trends in referrals to liaison psychiatry teams from UK emergency departments for patients over 65.

INTRODUCTION: The number of people over the age of 65 attending Emergency Departments (ED) in the United Kingdom (UK) is increasing. Those who attend with a mental health related problem may be referred to liaison psychiatry for assessment. Improving responsiveness and integration of liaison psychiatry in general hospital settings is a national priority. To do this psychiatry teams must be adequately resourced and organised. However, it is unknown how trends in the number and type referrals of older people to liaison psychiatry teams by EDs are changing, making this difficult. METHODS: We performed a national multi-centre retrospective service evaluation, analysing existing psychiatry referral data from EDs of people over 65. We described trends in the number, rate, age, mental health presentation, and time taken to assessment over a 7 years period. RESULTS: Referral data from 28 EDs across England and Scotland were analysed (n = 18,828 referrals). There was a general trend towards increasing numbers of people referred to liaison psychiatry year on year. Variability in referral numbers between different departments, ranged from 0.1 to 24.3 per 1000 ED attendances. The most common reasons for referral were mood disorders, self-harm and suicidal ideas. The majority of referrals were assessed within 60 min, however there is variability between departments, some recording waits over 11 h. DISCUSSION: The data suggests great inter-departmental variability in referral numbers. Is not possible to establish the cause of variability. However, the data highlights the importance of asking further questions about why the differences exist, and the impact that has on patient care.

Cost-effectiveness of the BRECONDA decision aid for women with breast cancer: Results from a randomized controlled trial.

OBJECTIVE: To report on the cost-effectiveness of BRECONDA (Breast RECONstruction Decision Aid), a web-based decision aid to facilitate decisions regarding breast reconstruction surgery, with usual care for women with breast cancer. METHODS: The economic evaluation was conducted alongside a randomized controlled trial. Women diagnosed with breast cancer or ductal carcinoma in situ and eligible for breast reconstruction following mastectomy were randomized to access BRECONDA for 6 months + usual care (n = 106) or usual care (n = 116) and were assessed at baseline preintervention, and then 1-month and 6-months post-randomization. Decisional conflict, satisfaction with information, decisional regret, and utilities were assessed by using maximum-likelihood linear mixed effects models. Costs included the fixed costs of BRECONDA, health care provider time, and health care resource use. Nonparametric bootstrapping was used to estimate incremental cost-effectiveness ratios. RESULTS: BRECONDA resulted in significantly less decisional conflict and greater satisfaction with information over time. Quality-adjusted life years did not differ between participants who received the decision aid compared with usual care. The cost of BRECONDA was estimated to be small (AUD$10) relative to other health care interventions and resulted in decreased health care costs overall (AUD$764). Based on the point estimates, the decision aid was more effective and less costly (dominant) for all measures of effectiveness. It was estimated that the decision aid has an 87% probability of being cost-effective at $60 000 per quality-adjusted life year gained. CONCLUSIONS: The BRECONDA web-based intervention designed to facilitate decisions regarding breast reconstruction surgery is likely to be cost-effective compared with usual care for women with breast cancer.

Qualitatively understanding patients' and health professionals' experiences of the BRECONDA breast reconstruction decision aid.

OBJECTIVE: Women diagnosed with breast cancer or ductal carcinoma in situ and those with a genetic susceptibility to developing this disease face the challenging decision of whether or not to undergo breast reconstruction following mastectomy. As part of a large randomized controlled trial, this qualitative study examined women's experiences of using the Breast RECONstruction Decision Aid (BRECONDA) and health professionals' feedback regarding the impact of this resource on patients' knowledge and decision making about breast reconstruction. METHOD: Semistructured interviews were conducted with women who accessed the BRECONDA intervention (N = 36) and with their healthcare providers (N = 6). All interviews were transcribed verbatim and subjected to thematic analysis by 3 independent coders. RESULTS: Participants reported an overall positive impression, with all interviewees endorsing this decision aid as a useful resource for women considering reconstructive surgery. Thematic analysis of patient interviews revealed 4 themes: overall impressions and aesthetics; personal relevance and utility; introducing BRECONDA; and advantages and suggested improvements. Analysis of health professionals' interviews also revealed 4 themes: need for BRECONDA, impact of BRECONDA, potential difficulties that may arise in using the decision aid, and recommending BRECONDA to patients. Patients indicated that they derived benefit from this resource at all stages of their decision-making process, with the greatest perceived benefit being for those early in their breast reconstruction journey. CONCLUSION: These findings support the use of BRECONDA as an adjunct to clinical consultation and other information sources.

Women's experiences of dating after breast cancer.

This study examined women's experiences of romantically dating after breast cancer. Semistructured interviews were conducted with 22 female breast cancer survivors who attempted to form new relationships post-breast cancer. Interview transcripts were analyzed using grounded theory methodology. We identified an overarching theme of "navigating the breast cancer dating journey," comprising seven themes including women's decision to consider dating; ability/desire to commence a new relationship; cancer-related disclosure; changes to intimacy and sexuality; body image difficulties; changing values; and trusting a new partner. Future research should empirically determine factors predicting a woman's ability to form a romantic relationship after breast cancer.

The Effect of Eating Disorder Memoirs in Individuals With Self-Identified Eating Pathologies.

As part of a larger, mixed-methods study, we posted an invitation to participate in a study on the effects of reading eating disorder memoirs on the website of an organization that provides support for people with eating disorders. Twenty-four women completed the questionnaire. Qualitative analysis of their responses indicated a recovery continuum, whereby the direction of memoir influence seemed to depend on an individual's recovery stage and motivation to recover. Individuals who reported that they were exposed to memoirs before, or during, their illness reported experiencing negative consequences including making unfavorable social comparisons, along with emulation and triggering of disordered behaviors, whereas those who reported being exposed when in recovery reported more positive outcomes including hope, validation, and social support. Findings have implications for the use of personal accounts as a means of facilitating patient recovery in eating disorder treatment settings. Future research should test the influence of memoirs using a larger eating disorder sample, and across different recovery stages.

The effect of disease risk probability and disease type on interest in clinic-based versus direct-to-consumer genetic testing services.

The effect of disease-specific cognitions on interest in clinic-based and direct-to-consumer (DTC) genetic testing was assessed. Participants (N = 309) responded to an online hypothetical scenario and received genetic testing-related messages that varied by risk probability (25, 50, 75 %) and disease type (Alzheimer's disease vs. Type 2 Diabetes). Post-manipulation interest increased for both testing types, but was greater for clinic-based testing. Interest was greater for Type 2 Diabetes than for Alzheimer's disease, the latter perceived as more severe and likely, and less treatable and preventable. For DTC testing only, participants allocated to the high risk condition (75 %) had greater testing interest than those in the low (25 %) category. DTC testing is perceived as a viable, but less preferred, option compared with clinic-based testing. Particularly when considering DTC genetic testing, there is a need to emphasize subjective disease-related perceptions, including risk probability.

SLAP deficiency decreases dsDNA autoantibody production.

Src-like adaptor protein (SLAP) adapts c-Cbl, an E3 ubiquitin ligase, to activated components of the BCR signaling complex regulating BCR levels and signaling in developing B cells. Based on this function, we asked whether SLAP deficiency could decrease the threshold for tolerance and eliminate development of autoreactive B cells in two models of autoantibody production. First, we sensitized mice with a dsDNA mimetope that causes an anti-dsDNA response. Despite equivalent production of anti-peptide antibodies compared to BALB/c controls, SLAP(-/-) mice did not produce anti-dsDNA. Second, we used the 56R tolerance model. SLAP(-/-) 56R mice had decreased levels of dsDNA-reactive antibodies compared to 56R mice due to skewed light chain usage. Thus, SLAP is a critical regulator of B-cell development and function and its deficiency leads to decreased autoreactive B cells that are otherwise maintained by inefficient receptor editing or failed negative selection.

MHC heterozygosity limits T cell receptor variability in CD4 T cells.

αß T cell receptor (TCR) V(D)J genes code for billions of TCR combinations. However, only some appear on peripheral T cells in any individual because, to mature, thymocytes must react with low affinity but not high affinity with thymus expressed major histocompatibility (MHC)/peptides. MHC proteins are very polymorphic. Different alleles bind different peptides. Therefore, any individual might express many different MHC alleles to ensure that some peptides from an invader are bound to MHC and activate T cells. However, most individuals express limited numbers of MHC alleles. To explore this, we compared the TCR repertoires of naïve CD4 T cells in mice expressing one or two MHC alleles. Unexpectedly, the TCRs in heterozygotes were less diverse that those in the sum of their MHC homozygous relatives. Our results suggest that thymus negative selection cancels out the advantages of increased thymic positive selection in the MHC heterozygotes.

SLAP deficiency enhances number and function of regulatory T cells preventing chronic autoimmune arthritis in SKG mice.

To test if manipulating TCR complex-mediated signaling (TCR signaling) could treat autoimmune disease, we generated the double SKG Src-like adapter protein (SLAP) knockout (DSSKO) mouse model. The SKG mutation in ZAP70 and SLAP have opposing functions on the regulation of TCR signaling. The combination of these two mutations alters TCR signaling in the context of a defined genetic background, uniform environmental conditions, and a well-characterized signaling disruption. In contrast to SKG mice, DSSKO mice do not develop zymosan-induced chronic autoimmune arthritis. This arthritis prevention is not due to significant alterations in thymocyte development or repertoire selection but instead enhanced numbers of regulatory T cells (Tregs) and decreased numbers of Th17 cells skewing the ratio of Tregs to autoreactive effector T cells. Treg depletion and/or functional blockade led to the development of arthritis in DSSKO mice. In vitro suppression of effector T cell proliferation was also enhanced, demonstrating that DSSKO mice have increased numbers of Tregs with increased function. Understanding how TCR signals influence development, expansion, and function of Tregs in DSSKO mice could advance our ability to manipulate Treg biology to treat ultimately autoimmune disease.

SLAP, a regulator of immunoreceptor ubiquitination, signaling, and trafficking.

Src-like adapter proteins (SLAP and SLAP-2) constitute a family of proteins that are expressed in a variety of cell types but are studied most extensively in lymphocytes. They have been shown to associate with proximal components of the T-cell receptor (TCR) and B-cell receptor (BCR) signaling complexes. An interaction of SLAP with c-Cbl leads to the ubiquitination and degradation of phosphorylated components of the TCR- and BCR-signaling complexes. The absence of this process in immature SLAP-deficient T and B cells leads to increased immunoreceptor levels due to decreased intracellular retention and degradation. We propose a model in which SLAP-dependent regulation of immunoreceptor levels allows for finer control of immunoreceptor signaling. Thus, SLAP functions to dampen immunoreceptor signaling, thereby influencing lymphocyte development and repertoire selection.

Social Determinants of Health: A Multilingual Standardized Patient Case to Practice Interpreter Use in a Telehealth Visit.

Introduction: The growing diversity of the United States population and strong evidence of disparities in health care make it critically important to educate health care professionals to effectively address issues of culture. To that end, we developed a simulation for teaching interpreter use in a telehealth setting. Our contribution of non-English language preference (NELP) patient cases in Spanish, Tagalog, French, and Igbo advances existing literature by combining the skills of interpreter use and telehealth while widening the array of cultures represented. Methods: Simulations were implemented for two cohorts of 60 first-year medical students. In the pilot, nine groups of six to seven students and one faculty met via Zoom with an NELP patient complaining of fatigue, weakness, and cough. When students determined the need for an interpreter, faculty admitted one to the meeting, and the telehealth visit continued. Postsession activities included debriefing and writing a progress note. Results: Course evaluation comments from the first cohort and a postencounter survey of the second cohort were positive. They revealed that students learned to speak slower, in shorter phrases, and directly to the patient. Learners completed note documentation according to a rubric. Discussion: This low-stakes activity provides faculty with a resource for introducing cultural competence into the curriculum. The original Spanish version of the case has been translated into three additional languages, providing a diverse representation of the NELP population. Important points for communicating through an interpreter are practiced in a telehealth setting with a fatigue case.

Cancer centre supportive oncology service: health economic evaluation.

OBJECTIVES: There have been many models of providing oncology and palliative care to hospitals. Many patients will use the hospital non-electively or semielectively, and a large proportion are likely to be in the last years of life. We describe our multidisciplinary service to treatable but not curable cancer patients at University Hospitals Sussex. The team was a mixture of clinical nurse specialists and a clinical fellow supported by dedicated palliative medicine consultant time and oncology expertise. METHODS: We identified patients with cancer who had identifiable supportive care needs and record activity with clinical coding. We used a baseline 2019/2020 dataset of national (secondary uses service) data with discharge code 79 (patients who died during that year) to compare a dataset of patients seen by the service between September 2020 and September 2021 in order to compare outcomes. While this was during COVID-19 this was when the funding was available. RESULTS: We demonstrated a reduction in length of stay by an average of 1.43 days per admission and a reduction of 0.95 episodes of readmission rates. However, the costs of those admissions were found to be marginally higher. Even with the costs of the service, there is a clear return on investment with a benefit cost ratio of 1.4. CONCLUSIONS: A supportive oncology service alongside or allied to acute oncology but in conjunction with palliative care is feasible and cost-effective. This would support investment in such a service and should be nationally commissioned in conjunction with palliative care services seeing all conditions.

Impact of a focussed teaching programme on practical prescribing skills among final year medical students.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Medication errors, and particularly prescribing errors, are common in UK hospitals. Junior doctors make the majority of prescribing errors. Deficiencies in prescribing education and training have been closely linked to the high frequency of medication errors. WHAT THIS STUDY ADDS: Focussed prescribing teaching can lead to an improvement in prescribing ability. Prescribing confidence can be significantly improved through education. Education is insufficient alone in eradicating prescribing errors. AIM: To assess the impact of prescribing teaching on final year medical students. METHODS: Students randomly allocated to two hospitals completed a prescribing assessment. Prescribing teaching was delivered to the intervention group while no additional teaching was provided for the control group. All students then completed a second prescribing assessment. RESULTS: Teaching improved the assessment score: mean assessment 2 vs. 1, 70% vs. 62%, P= 0.007; allergy documentation: 98% vs. 74%, P= 0.0001; and confidence. However, 30% of prescriptions continued to include prescribing errors. CONCLUSION: Medical students make significant errors in prescribing. Teaching improves ability and confidence but is insufficient alone in eradicating errors.

The AED Project: Multiorganization Collaboration to Streamline Automatic External Defibrillator Data in Out-of-Hospital Cardiac Arrests.

BACKGROUND: In patients with out-of-hospital cardiac arrest (OHCA), automated external defibrillator (AED) devices contain valuable data about the patient's initial rhythm. The retrieval process was previously without protocol, despite its critical role in the patient journey. METHODS: Through a Plan-Do-Study-Act model, the cardiology department at Royal Jubilee Hospital (Victoria, British Columbia, Canada) collaborated with provincial emergency health services (British Columbia Emergency Health Services) to cocreate a request process for data from AEDs used by first responders. British Columbia Fire Departments, which are under municipal oversight, required an alternate strategy. Educational presentations allowed for feedback and spread. Patients surviving OHCA and transfer to the regional cardiac centre were consecutively enrolled from November 2018 to April 2020. We evaluated the timeliness of AED information retrieval, and tracked the process to admission. A retrospective chart review informed specifics after admission. A survey to the Coronary Intensive Care Unit staff was used to assess clinical utility. RESULTS: Seventy-one consecutive patients were enrolled during the study period. Seven rhythm strips arrived with the patient, thus not affected by the initiative. From the remaining 64 cases, 80% (n = 51/64) were received within 48 hours, and 88% (n = 45/51) were received within 24 hours with a median of 1 hour. Eighteen Coronary Intensive Care Unit staff completed the survey; 81% reported AED data as "very useful" to clinical decision-making (n = 13/16). The AED rhythm strips provided insight into OHCA etiology (100%; n = 11/11), supported evidence for diagnoses (100%; n = 11/11), and reduced unnecessary testing (64%; n = 7/11). CONCLUSIONS: Implementing an organized protocol allowed for timely access to AED data, which was directly integrated into clinical decision-making and positively affected hospital stay.

CONTEXTE: Lorsqu'un patient subit un arrêt cardiaque extrahospitalier (ACEH), le défibrillateur externe automatisé (DEA) utilisé par les premiers intervenants contient des données précieuses sur son rythme cardiaque initial. Malgré l'importance de ces données pour le parcours du patient, leur récupération n'était auparavant soumise à aucun protocole. MÉTHODOLOGIE: Dans le cadre d'une initiative fondée sur le modèle Planifier, Développer, Contrôler, Ajuster, le service de cardiologie de l'hôpital Royal Jubilee (Victoria, Colombie-Britannique, Canada) a travaillé en collaboration avec les services médicaux d'urgence de la province (British Columbia Emergency Health Services) afin de créer un processus de demande des données enregistrées dans les DEA utilisés par les premiers intervenants. Pour les services des incendies de la Colombie-Britannique, qui relèvent des administrations municipales, il a fallu adopter une autre stratégie. Des séances de sensibilisation ont permis de recueillir une rétroaction et de diffuser l'information. Nous avons retenu pour notre étude les cas des patients consécutifs qui ont survécu à un ACEH et ont été transférés à un centre de cardiologie régional entre novembre 2018 et avril 2020. Nous avons évalué le caractère opportun de la récupération des données des DEA et fait le suivi du processus jusqu'à l'admission du patient à l'hôpital. L'examen rétrospectif des dossiers a permis d'obtenir les données recueillies après l'admission. Un sondage a été mené auprès du personnel de l'unité de soins intensifs de cardiologie pour évaluer l'utilité clinique de l'initiative. RÉSULTATS: Au total, 71 patients consécutifs ont été recrutés durant la période de l'étude. Sept patients sont arrivés à l'hôpital avec le tracé de l'enregistrement de leur rythme cardiaque, et n'ont donc pas été touchés par l'initiative. Sur les 64 autres cas, 80 % (n = 51/64) des tracés ont été obtenus dans les 48 heures, et 88 % (n = 45/51), dans les 24 heures, l'intervalle médian étant de 1 heure. En tout, 18 membres du personnel de l'unité de soins intensifs de cardiologie ont répondu au sondage; 81 % d'entre eux ont dit que les données des DEA étaient « très utiles ¼ à la prise de décisions cliniques (n = 13/16). Les tracés du rythme cardiaque produits par les DEA ont permis de mieux comprendre l'étiologie des ACEH (100 %; n = 11/11), fourni des données facilitant le diagnostic (100 %; n = 11/11) et réduit l'exécution de tests non nécessaires (64 %; n = 7/11). CONCLUSIONS: La mise en œuvre d'un protocole structuré a permis d'accéder en temps opportun aux données des DEA, qui ont été directement prises en compte dans la prise de décisions cliniques et ont eu un effet positif sur l'hospitalisation.

Unchanged triclabendazole kinetics after co-administration with ivermectin and methimazole: failure of its therapeutic activity against triclabendazole-resistant liver flukes.

BACKGROUND: The reduced drug accumulation based on enhanced drug efflux and metabolic capacity, identified in triclabendazole (TCBZ)-resistant Fasciola hepatica may contribute to the development of resistance to TCBZ. The aim of this work was to evaluate the pharmacokinetics and clinical efficacy of TCBZ administered alone or co-administered with ivermectin (IVM, efflux modulator) and methimazole (MTZ, metabolic inhibitor) in TCBZ-resistant F. hepatica-parasitized sheep. Sheep infected with TCBZ-resistant F. hepatica (Sligo isolate) were divided into three groups (n = 4): untreated control, TCBZ-treated (i.r. at 10 mg/kg) and TCBZ+IVM+MTZ treated sheep (10 i.r., 0.2 s.c. and 1.5 i.m. mg/kg, respectively). Plasma samples were collected and analysed by HPLC. In the clinical efficacy study, the animals were sacrificed at 15 days post-treatment to evaluate the comparative efficacy against TCBZ-resistant F. hepatica. RESULTS: The presence of IVM and MTZ did not affect the plasma disposition kinetics of TCBZ metabolites after the i.r. administration of TCBZ. The AUC value of TCBZ.SO obtained after TCBZ administration (653.9 +/- 140.6 microgxh/ml) was similar to that obtained after TCBZ co-administered with IVM and MTZ (650.7 +/- 122.8 microgxh/ml). Efficacy values of 56 and 38% were observed for TCBZ alone and for the combined treatment, respectively. No statistical differences (P > 0.05) were observed in fluke counts between treated groups and untreated control, which confirm the resistant status of the Sligo isolate. CONCLUSIONS: The presence of IVM and MTZ did not affect the disposition kinetics of TCBZ and its metabolites. Thus, the combined drug treatment did not reverse the poor efficacy of TCBZ against TCBZ-resistant F. hepatica.