Animal Care Research Articles

Sutterella and its metabolic pathways positively correlate with vaccine-elicited antibody responses in infant rhesus macaques.

It is becoming clearer that the microbiota helps drive responses to vaccines; however, little is known about the underlying mechanism. In this study, we aimed to identify microbial features that are associated with vaccine immunogenicity in infant rhesus macaques. We analyzed 16S rRNA gene sequencing data of 215 fecal samples collected at multiple timepoints from 64 nursery-reared infant macaques that received various HIV vaccine regimens. PERMANOVA tests were performed to determine factors affecting composition of the gut microbiota throughout the first eight months of life in these monkeys. We used DESeq2 to identify differentially abundant bacterial taxa, PICRUSt2 to impute metagenomic information, and mass spectrophotometry to determine levels of fecal short-chain fatty acids and bile acids. Composition of the early-life gut microbial communities in nursery-reared rhesus macaques from the same animal care facility was driven by age, birth year, and vaccination status. We identified a Sutterella and a Rodentibacter species that positively correlated with vaccine-elicited antibody responses, with the Sutterella species exhibiting more robust findings. Analysis of Sutterella-related metagenomic data revealed five metabolic pathways that significantly correlated with improved antibody responses following HIV vaccination. Given these pathways have been associated with short-chain fatty acids and bile acids, we quantified the fecal concentration of these metabolites and found several that correlated with higher levels of HIV immunogen-elicited plasma IgG. Our findings highlight an intricate bidirectional relationship between the microbiota and vaccines, where multiple aspects of the vaccination regimen modulate the microbiota and specific microbial features facilitate vaccine responses. An improved understanding of this microbiota-vaccine interplay will help develop more effective vaccines, particularly those that are tailored for early life.

Bereavement and the veterinary nurse

Bereavement is an issue that all pet owners and animal care staff face. Veterinary nurses frequently face not only the bereavement of clients, but also their own as pet owners, or from taking part in euthanasia. As a result, veterinary nurses are at risk of further challenges such as disenfranchised or complicated grief. This article discusses what is known about the experience of bereavement, methods to support those experiencing bereavement, and how these may affect practicing veterinary nurses.

The Ecological Role of Probiotics in in vitro Culture for the Improvement of Health in the Poultry Industry

The general objective of this work was to isolate from yoghourts cultured strains of lactobacilli with potential for use as probiotics in poultry farming. Three yoghourts were cultured to see the presence of lactobacilli in the Rogosa agar base culture medium. It was found that only one yoghourt (number 1) showed the growth of lactobacilli. This yoghourt was immediately selected for further cultivation. Afterwards, the Lactobacillus strains were isolated and fortified under CO2 and then inoculated into a solution of peptone water, which constituted inoculums to be administered to an experimental group of poultry. Another group served as controls. Pathogenic strains of Escherichia coli were also administered to both groups (experimental and control, each comprising five hens). The results showed significant weight gain from the experimental group (positive effect on immunity) and freedom from disease after an incubation period (inhibitory effect of the lactobacillus strains on the Escherichia coli strains), whereas the control group showed less weight gain than the experimental group and development of colibacillosis after an incubation period. The positive effects of the Lactobacillus strains observed on the poultry of the experimental group proved the ecological role of these microorganisms in improving the health of the poultry by inhibiting the effects of pathogenic Escherichia coli strains. This suggests reassuring prospects for the reduction of antibiotic use in both human and animal care.

Improving access to advanced veterinary care for rescued cats and dogs.

The objectives of this study were as follows: (1) to describe the AMC to the Rescue (AMCTTR) funding criteria and the application process; (2) to describe the distribution of species cared for through the program, the medical conditions treated in cats compared with those treated in dogs and the cost of that care; and (3) to define the successes and challenges of the program. The AMCTTR database was reviewed for applications submitted between 1 January 2020 and 31 December 2022. Data collected included the following: the date of application; rescue organization seeking financial support; species; age of pet at time of application; expenditures funded by AMCTTR; and the method by which the rescue organization learned about AMCTTR. The animals in the AMCTTR database were sorted into two groups: those accepted for funding and those that did not meet funding criteria. The Animal Medical Center (AMC) medical record system was searched for the total number of individual animals, species and age seen at AMC during the study period. In total, 267 applications were reviewed and 190 applications from 134 cats, 52 dogs and four rabbits were accepted for advanced veterinary care funded by AMCTTR. Over the 3-year study period, US$612,564 were awarded and over half of those funds were awarded to cats. The average expenditure per animal during this time period was US$3224. The most common referrals to AMCTTR were made to ophthalmology, surgery and dentistry. The needs of cats differed from dogs in that feline applications were most commonly submitted for ophthalmology or dentistry. Expenditures per cat were less than per dog because dogs were referred for more expensive orthopedic surgery. The need for advanced veterinary care for rescue animals is enormous, especially for cats. Programs that subsidize advanced veterinary care increase access to that care.

Assessing Animal Welfare Risk in Fibre-Producing Animals by Applying the Five Domains Framework.

Nearly 5 billion farm animals, including waterfowl, cattle, sheep, goats, and alpacas, are being affected by the fashion industry. There is an urgent need for a system that evaluates their welfare. The rise in public interest on the topic of animal welfare is leading to the creation of different textile standards or certification schemes, which can give us an overview of the general state of expectations in terms of animal welfare within the textile industry. We therefore created a risk assessment tool and applied it to 17 different textile standards. Our results showed that only one of the standards reached a score in the "Acceptable" animal welfare risk category, and the rest of the standards had even lower scores of risks for animal welfare. In general, industry standards have not demanded sufficient requirements for higher levels of animal welfare. While the current risk assessment gave us a good idea of what is considered acceptable within the industry, it is also not necessarily representative of the risks for the majority of farm animals that are part of the textile industry. Only a small number of animal-derived materials are certified with some form of animal welfare standards, even though these standards can play an important role in improving the standard of care for animals. To evaluate the actual welfare states of the animals in fibre production, further research is needed to apply the proposed tool to actual farms.

Towards Sustainable Equine Welfare: Comparative Analysis of Machine Learning Techniques in Predicting Horse Survival

Promoting sustainable equine welfare is pivotal in ensuring the well-being of horses, particularly concerning their survival based on past medical conditions. This study presents a comprehensive comparative analysis of various machine learning techniques employed to predict the survival prospects of horses using historical medical data. By leveraging a dataset encompassing diverse medical attributes and survival outcomes, this research assesses the efficacy and comparative performance of distinct machine learning algorithms. The study delves into the application of supervised learning models, including but not limited to decision trees, random forests, support vector machines, and neural networks, in predicting equine survival. Evaluative metrics such as accuracy, precision, recall, and F1 score are employed to assess the predictive capabilities and generalizability of each model. Moreover, this research emphasizes the importance of sustainable equine welfare within the broader context of responsible animal care.

Endogenous Protein C Activation with AB002 Improves Outcomes in a Rat Model of Acute Ischemic Stroke

Background: The hemorrhagic side-effects of current thrombolytic agents limit their usefulness to a small subset of acute ischemic stroke patients. An early, effective, and hemostatically safe antithrombotic/neuroprotectant in addition to standard of care could improve outcomes. AB002 (E-WE thrombin) is an engineered recombinant thrombin analog (W215A/E217A) that activates cytoprotective and antithrombotic endogenous protein C on intravascular surfaces without any measurable procoagulant activity. In renal failure patients undergoing hemodialysis, AB002 treatment reduced dialyzer clotting without increasing markers of hemostasis impairment or coagulation (NCT03963895). Preclinical studies also showed that AB002 exhibits potent antithrombotic/thrombolytic effects in a non-human primate model of acute vascular graft thrombosis, as well as reduces infarct size and improves outcomes in an experimental acute myocardial ischemia-reperfusion model in mice. Aims: Here, we evaluated whether neuroprotective effects of AB002 can be observed following middle cerebral artery occlusion-recanalization (MCAO-R) in rats. Methods: The local animal care and use committee approved all studies. 8 to 9-week-old male rats (275-377 g) were anesthetized under isoflurane and a small laser-Doppler probe was affixed to the skull to monitor cortical perfusion and verify vascular occlusion and reperfusion. A silicone-coated 4-0 nylon monofilament was inserted into the right internal carotid artery (ICA) via the external carotid artery (ECA) until the laser-Doppler signal dropped to < 30 % of baseline. To evaluate the effect of AB002 on outcomes, rats (n = 4/ group) were treated with 25 µg/kg (0.25 mL/kg; i.v.) or saline placebo, administered 30 min after induction of ischemia. Since prolongation of the activated partial plasminogen time (aPTT) is a pharmacologic effect of high dose drug exposure, a 0.45 mL blood sample was collected at 20 min post treatment from the right jugular vein, processed to plasma and frozen for subsequent aPTT evaluation. At 90 min, the filament was removed, the surgical incisions were sutured closed and postoperative animals were monitored during recovery. Neurological performance scores and weight were assessed daily for 4 days. Rats were sacrificed on day 7 post-surgery and infarct size was measured using 2,3,5-triphenyltetrazolium chloride (TTC) staining. To account for the effect of edema, the infarcted area was estimated indirectly by subtracting the non-infarcted area in the ipsilateral hemisphere from the contralateral hemisphere and expressing infarct volume as a percentage of contralateral hemisphere. APTT was measured in duplicate using a KC-4 coagulometer. All analyses were performed by researchers blinded to treatment. Results: Compared to placebo, rats that received AB002 exhibited less ischemic damage, evidenced by a statistically significant reduction in infarct volume of the cortex (32.3% versus 8.9%, P < 0.05) and hemisphere (28.0% versus 9.8%, P < 0.01). In addition, rats had better neurological scores and greater weight gains during recovery following treatment with AB002, compared to placebo. Mean aPTT values were higher in AB002 treated rats compared to placebo (34 ± 2.2 s versus 21 ± 1.6 s), confirming drug exposure. Conclusions: Treatment with AB002 during ischemia reduced infarct volume and improved outcomes in the rat experimental stroke model. Considering its neuroprotective and antithrombotic properties, we propose that early treatment with AB002 may confer outcome benefit for patients experiencing acute thrombotic emergencies.

1954. Dynamic PET facilitated Modeling and Novel Antibiotic Regimens for Tuberculous Meningitis due to Multidrug-Resistant Strains

1954. Dynamic PET facilitated Modeling and Novel Antibiotic Regimens for Tuberculous Meningitis due to Multidrug-Resistant Strains

Exotic pet trade in Canada: The influence of social media on public sentiment and behaviour

The live trade in wild animals can increase the risk of escape of exotic animals, introduce invasive species, spread zoonotic diseases, over-exploit wild populations, and harm animal welfare. Trade in exotic pets is a particularly understudied issue in Canada. While Canadians generally have pro-environmental attitudes, it is unclear whether this extends to the trade in exotic animals. With most Canadians on social media, we aimed to use Natural Language Processing of social data to examine public sentiment towards exotic pet trade in Canada. We analysed 9,274 posts on Twitter (now 'X') about exotic pets between 2012 and 2022, and 150,236 comments from 2568 TikTok videos showing exotic pets from 50 unique Canadian accounts. We found that social media users demonstrate markedly positive attitudes towards the live trade in reptiles and amphibians, mammals, birds, and arachnids and insects, even on TikTok videos showing poor animal care and questionable legality. We propose a conceptual framework for how exotic pet influencers directly and indirectly contribute to increased demand for exotic pets through opinion leadership, sharing information on where to buy exotic pets, and normalising exotic pet ownership. We suggest that it is important to raise public awareness among social media users about the challenges associated with wildlife trade, including animal welfare considerations, and the links between exotic pet trade and conservation.

Human Behaviour in Veterinary Care

Abstract The human in veterinary practice is an oft-neglected component of both human and animal welfare. Those in vet practice, including veterinarians, vet nurses, technical staff, and front-of-house staff all have a role to play in ensuring that animals receive the best possible care. How should clinicians approach the cognitive load of decision making in stressful situations, recognise the biases in their decision making, and balance non-technical skills alongside highly specialised clinical skills to support animal health? Veterinary work requires effective communication across diverse teams in stressful situations, and good animal care necessitates an understanding of human factors in the veterinary practice. Even after care has concluded, veterinarians need to recognise the impact that human behaviour has on supporting animal welfare. We describe how human behaviour impacts veterinary care, and how veterinarians can utilise up-to-date research on human behaviour such as the Knowledge Deficit Model of communication, the Theory of Planned Behaviour, and the 5As Behavioural Change model to improve animal welfare. Information © The Authors 2023

Social Network Analysis as a Tool in the Care and Wellbeing of Zoo Animals: A Case Study of a Family Group of Black Lemurs (Eulemur macaco).

Social network analysis (SNA) is an increasingly utilised technique in the literature examining the social structures and organisation of animals and understanding the bonds between groups and individuals. Using a case study as an illustration, the applications of SNA are explored, including the identification of dominance hierarchies and detection of sources of social pressure, with a particular focus on the applications of SNA to holistic assessments of animal welfare alongside other methods. Based on the examination of social dynamics in a family group of four black lemurs (Eulemur macaco), a primate whose social organisation is characterised by patterns of female dominance, it is demonstrated that SNA can be used to examine the affiliative and agonistic interactions between individuals living in human care. SNA showed species-typical forms of female dominance that were largely directed towards the two males, characterised by the initiation of aggressive interactions and male submission. More intricate relationships and consistent social roles across networks were revealed through the examination of SNA. It is concluded that SNA has wide-ranging benefits in the assessment of effects of environmental changes, such as informing social management decisions, developing enrichment and intervention programs, and guiding overall improvements to the housing and care of individual animals. SNA, as part of an animal welfare toolbox, could, therefore, be a pivotal technique for modern animal welfare assessment that considers individual animals and their social lives. By sharing a case study of the technique in use, it is hoped that animal collections may adopt similar modern and evidence-based assessment methods.

Evaluating the awareness level of zoonotic diseases among final-year veterinary students

Zoonotic diseases have significant implications for public health, and veterinary professionals are essential in their prevention and control. This study aimed to evaluate the level of zoonotic disease awareness among final-year veterinary students and explore their perspectives on protection against these diseases. A survey was administered to 128 final-year veterinary students, and the data were analyzed to investigate the associations between demographic factors and cumulative scores, which were based on six statements related to zoonosis awareness. The results showed a moderate level of awareness among the participants. No significant differences in cumulative scores were observed with respect to age (P = 0.769), gender (P = 0.342), geographical region of residence (P = 0.565), living area (P = 0.748), and grade point average (P = 0.468). However, students who owned or took care of companion animals (4 [1-6]) exhibited higher cumulative scores compared to those who did not own companion animals (3 [1-6]; P = 0.011). Further research is needed to explore the underlying factors and develop educational interventions that promote zoonotic disease awareness among veterinary students

The Impact of Head Position on Neurological and Histopathological Outcome Following Controlled Automated Reperfusion of the Whole Body (CARL) in a Pig Model.

Introduction: Based on extracorporeal circulation, targeted reperfusion strategies have been developed to improve survival and neurologic recovery in refractory cardiac arrest: Controlled Automated Reperfusion of the whoLe Body (CARL). Furthermore, animal and human cadaver studies have shown beneficial effects on cerebral pressure due to head elevation during conventional cardiopulmonary resuscitation. Our aim was to evaluate the impact of head elevation on survival, neurologic recovery and histopathologic outcome in addition to CARL in an animal model. Methods: After 20 min of ventricular fibrillation, 46 domestic pigs underwent CARL, including high, pulsatile extracorporeal blood flow, pH-stat acid-base management, priming with a colloid, mannitol and citrate, targeted oxygen, carbon dioxide and blood pressure management, rapid cooling and slow rewarming. N = 25 were head-up (HUP) during CARL, and N = 21 were supine (SUP). After weaning from ECC, the pigs were extubated and followed up in the animal care facility for up to seven days. Neuronal density was evaluated in neurohistopathology. Results: More animals in the HUP group survived and achieved a favorable neurological recovery, 21/25 (84%) versus 6/21 (29%) in the SUP group. Head positioning was an independent factor in neurologically favorable survival (p < 0.00012). Neurohistopathology showed no significant structural differences between HUP and SUP. Distinct, partly transient clinical neurologic deficits were blindness and ataxia. Conclusions: Head elevation during CARL after 20 min of cardiac arrest independently improved survival and neurologic outcome in pigs. Clinical follow-up revealed transient neurologic deficits potentially attributable to functions localized in the posterior perfusion area, whereas histopathologic findings did not show corresponding differences between the groups. A possible explanation of our findings may be venous congestion and edema as modifiable contributing factors of neurologic injury following prolonged cardiac arrest.

Knowledge, Attitudes, and Practices on Ethics in Biomedical Animal Research in Mexico.

The most widely accepted ethical concept for the mitigation of harm to animals used in biomedical research is known as the 3Rs, which refer to replacement, reduction, and refinement. The aim of our study was to determine the ethical and regulatory criteria that researchers in Mexico consider when developing their animal research protocols and that members of the ethics committees use when they evaluate and approve these protocols. We circulated a survey to 300 individuals from different research institutions and received responses from 179 researchers and members of ethics committees on questions related to their knowledge, attitudes, and practices toward the use of animals in research based on the 3Rs. The responses obtained indicate that the respondents were aware of the 3R concept, and they claim to apply these principles. However, the responses revealed resistance to using alternatives for research, testing, and teaching (66%). Nineteen percent of the researchers reported that their institutions do not have an integrated Institutional Animal Care and Use Committee (IACUC). Around 80% of respondents were aware of Mexican regulations. The knowledge and application of the 3Rs by researchers and members of the IACUC is a fundamental concept in animal research. Such knowledge contributes the use of ethical standards, attitudes, and practices relevant to the use of animals in research.

Contrasting Experimental Rodent Aftercare With Human Clinical Treatment for Cervical Spinal Cord Injury: Bridging the Translational "Valley of Death".

More than half of all spinal cord injuries (SCIs) occur at the cervical level and often lead to life-threatening breathing motor dysfunction. The C2 hemisection (C2Hx) and high cervical contusion mouse and rat models of SCI are widely utilized both to understand the pathological effects of SCI and to develop potential therapies. Despite rigorous research effort, pre-clinical therapeutics studied in those animal models of SCI sometimes fail when evaluated in the clinical setting. Differences between standard-of-care treatment for acute SCI administered to clinical populations and experimental animal models of SCI could influence the heterogeneity of outcome between pre-clinical and clinical studies. In this review, we have summarized both the standard clinical interventions used to treat patients with cervical SCI and the various veterinary aftercare protocols used to care for rats and mice after experimentally induced C2Hx and high cervical contusion models of SCI. Through this analysis, we have identified areas of marked dissimilarity between clinical and veterinary protocols and suggest the modification of pre-clinical animal care particularly with respect to analgesia, anticoagulative measures, and stress ulcer prophylaxis. In our discussion, we intend to inspire consideration of potential changes to aftercare for animal subjects of experimental SCI that may help to bridge the translational "Valley of Death" and ultimately contribute more effectively to finding treatments capable of restoring independent breathing function to persons with cervical SCI.

Cardiosphere derived cell secretome therapy after experimental myocardial infarction: effects of intracoronary administration on ventricular tachycardia inducibility and cardiac function

Abstract Background Myocardial infarction (MI) carries high risk of sudden cardiac death due to the development of ventricular tachycardia (VT) which is caused by viable myocytes located within the infarct scar tissue [1]. Cardiosphere derived cell secretome (S-CDCs) has been demonstrated to possess antiarrhythmic properties when delivered transendocardially [2]. Further, S-CDCs has been proven to reduce scar size and increase viable myocardial mass in chronic MI [3]. Purpose The objective of this study was to evaluate the effects of an intracoronary (IC) administration of S-CDCs on VT inducibility and cardiac function in a porcine MI model. Methods After obtaining the approval of the Institutional Animal Care and Use Committee, 14 Large White swine were subjected to closed chest MI induction carrying out balloon occlusion of the left anterior descending coronary artery (below the second diagonal branch) for 150 minutes. One month after MI creation, pigs received an IC administration of saline (CON; 5mL; n=7) or S-CDCs (S-CDCs; 9.16 mg of protein in 5mL of saline; n=7). VT inducibility and magnetic resonance (MR) studies were performed pre- and four months post-injection determining ejection fraction (EF), infarct size (IS) and indexed end diastolic and systolic volumes (EDVi, ESVi). Results Before injection VT was inducible in all cases and no differences were observed between groups in any MR-derived parameter (figure). IC infusion was successful in all swine. At four months VT inducibility study revealed lower inducibility rates in S-CDCs compared to CON (57% versus 100%; p=0.05). At this timepoint EF was higher in S-CDCs (35±10% versus 29±10%) although differences between groups were not statistically significant. Conversely, IS was significantly lower in S-CDCs (12±3% versus 16±2% (p=0.03)). Moreover, a trend towards lower ventricular volumes (EDVi: 83±18mL/m² versus 88±29mL/m² and ESVi: 56±20mL/m² versus 64±27mL/m²) was detected in this group. Conclusions The IC administration of S-CDCs suggests a potential reduction on post-MI VT development as well as a beneficial effect on cardiac function. This therapy seems to reduce IS in this porcine MI model.MR derived parameters

Erythrocyte-derived extracellular vesicles from type 2 diabetes patients induce endothelial dysfunction through arginase 1

Abstract Background The mechanisms driving the development of cardiovascular injury in type 2 diabetes (T2D) remain incompletely understood. We recently demonstrated that red blood cells (RBCs) from patients with T2D (T2D-RBCs) act as mediators of endothelial dysfunction, but the mechanisms underlying this interaction are not clarified. We found that RBCs via upregulation of arginase 1 attenuate nitric oxide bioavailability and endothelial function. It is increasingly clear that extracellular vesicles (EVs) are actively secreted by practically all cell types, including RBCs, and represent a novel mechanism of intercellular communication. Purpose This study aimed to determine whether EVs derived from T2D-RBCs are involved as mediators in vascular injury through the signalling of arginase 1. Methods T2D-RBCs and RBCs from age-matched healthy controls (H-RBCs) were isolated and incubated with Krebs-Henseleit buffer (20% haematocrit). Following 18h incubation, the conditioned medium was collected for EV isolation using sequential ultracentrifugation and membrane affinity column. EV concentration was measured by nanoparticle tracking analysis. Aortas isolated from wild-type mice were incubated with EVs derived from T2D-RBCs and H-RBCs for 18h. Endothelium-dependent and -independent relaxations (EDR and EIDR, respectively) of the aortae were evaluated in a wire myograph. The involvement of arginase was investigated by the addition of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH) either to the 18h co-incubation of EVs with the aortic segments to selectively investigate the contribution of EV-derived arginase (ABH, 10 mM) or to the aortae following the 18h co-incubation to selectively target vascular arginase (ABH, 100 µM). All animal experiments were performed according to the principles of laboratory animal care (NIH Publication no. 85-23 revised 1985) and human procedures according to the declaration of Helsinki and approved by the Swedish Ethical Review Authority. Results T2D-RBCs had a ten times lower EV concentration compared to H-RBCs. T2D-RBC-derived EVs isolated using both methods significantly impaired EDR (Fig. 1A-C), whereas EIDR was not affected. This effect was observed irrespective of if the same volume or concentration of EVs were administered. Inhibition of arginase with ABH during the co-incubation with EVs derived from T2D-RBCs completely prevented the impairment of EDR induced by the EVs (Fig. 1D). Administration of ABH to the aortae following the co-incubation also attenuated the impairment of EDR. Immunohistochemical staining revealed upregulation of arginase 1 (Fig. 2A-B) but not arginase 2 (Fig. 2C-D) in the vasculature following incubation with EVs from T2D-RBCs. Conclusion EVs derived from T2D-RBCs induce endothelial dysfunction, and arginase 1 derived from these EVs mediates this endothelial dysfunction. These results shed new important light on the mechanism underlying vascular injury mediated by RBCs in T2D.

The acute hemodynamic effects of sodium lactate infusion: increased cardiac output and decreased afterload in a randomized trial in pigs

Abstract Background Lactate is traditionally acknowledged as a by-product of anaerobic glucose metabolism. Recently, however, lactate has been proven to be a preferred oxidative substrate for stressed myocardium. Studies have shown that exogenous lactate infusion provides beneficial hemodynamic effects including increased cardiac output (CO). Nevertheless, the exact mechanism of action underlying the hemodynamic effects of lactate infusion has not been fully elucidated. Aim To identify the cardiovascular mechanisms behind the acute hemodynamic effects of exogenous sodium lactate infusion in an experimental model of healthy human-sized pigs. Methods We performed a randomized, assessor-blinded crossover study in eight female 60 kg pigs. In randomized order, the pigs received an infusion with 1 M sodium lactate for two hours and a control infusion with iso-osmolar and isovolumetric sodium chloride for two hours. The two infusion periods were separated by a one-hour washout period. We measured CO and pulmonary pressures hourly with a pulmonary artery catheter. A pressure-volume admittance catheter was inserted in the left ventricle to assess measures of cardiac efficiency, contractility, afterload, and preload. Hemodynamic measures as arterial blood pressure, heart rate, and mixed venous saturation (SvO2) were measured hourly as well. The study followed the principles of laboratory animal care (NIH Publication no. 85-23 revised 1985) and national and European legislations. Results Lactate levels increased by 9.9 mmol/L (95% CI 9.1 to 11.0) and CO increased by 2.0 L/min (95% CI 1.2 to 2.8) during lactate infusion as compared with the control period (figure 1). During lactate infusion, ejection fraction increased by 16.0 percentage points (95% CI 1.9 to 31.0) and heart rate by 21 bpm (95% CI 9 to 32) compared with control. Arterial elastance decreased by -1.1 mmHg/ml (95% CI -2.1 to -0.18). Lactate infusion also increased cardiac efficiency, SvO2, arterial pH, and arterial glucose concentration significantly. The infusion of lactate led to no changes in systemic arterial pressure nor pulmonary pressures including pulmonary artery wedge pressure. Also, no changes were found in left ventricle end systolic elastance (contractility). Futhermore, no change in left ventricle end-diastolic volume or -pressure (preload) were observed during lactate infusion compared with the control (figure 2). Conclusion High dose lactate infusion increased cardiac output by reducing afterload. No changes in left ventricular contractility or -preload were observed.Fig 1:Lactate concentration and COFig 2:Changes of endpoint parameters

'When I receive ARVs through my group, my heart settles': Participants' perceptions and experiences of Friends for Life Circles for Option B+ in Kampala and Mityana Districts, Uganda.

The Friends for Life Circles (FLC) was a parallel randomized controlled trial testing the efficacy of a group peer support intervention to support long-term adherence to Option B+ in Kampala and Mityana districts in Uganda. We explored FLC participants' experiences and perceptions of the intervention on adherence to Option B+ for PMTCT and potential implications for strengthening the PMTCT program. We collected data from six focus group discussions with lactating women enrolled in the FLC intervention, and from 14 key informant interviews with health workers, district and national level stakeholders, as well as male partners of FLC participants. Data were analysed using a content thematic approach in a continuous and iterative process. Women described the FLC intervention as acceptable and beneficial in enhancing their understanding of HIV and the need for ART. The FLC helped women, especially those newly diagnosed with HIV infection to come to terms with their diagnosis and overcome the fear of death linked to testing HIV positive, and provided opportunities to enhance ART initiation, resumption and adherence. The FLC provided safe spaces for women, to learn about ART, and to receive support from peers including adherence reminders through home visits and 'coded' reminder messages. Receiving ART from support groups protected members from stigma and long lines at health facilities. Fear of stigma, health system challenges, the high cost of caring for animals and lack of money to save in groups were key challenges noted. The FLC support groups were crucial in providing needed support for women to initiate, resume and adhere to lifelong ART for Option B+. It is important that women who test HIV positive and start ART for life receive psychosocial support from peers and health workers to improve chances of preventing HIV transmission from mothers to children.

Abstract 11774: Right Ventricular Function and Myocardial Blood Volume Analyses by Convolutional Neural Network in Experimental Pulmonary Hypertension

Introduction: Survival of patients with pulmonary hypertension (PH) is highly dependent on the right ventricular (RV) function. Despite the association of various factors with adaptive or maladaptive RV phenotypes, the contribution of microvascular density to RV adaptation to pressure overload remains unclear. Hypothesis: This study aimed to evaluate the RV myocardial blood volume and its role in the RV adaptation to pressure overload. Methods: Both the University Animal Care Committee and the federal authorities for animal research of the Regierungsprasidium Giessen (Hessen, Germany) approved the study protocol. The study used adult Wistar-Kyoto rats and Sprague-Dawley rats to induce PH using SuHx and monocrotaline (MCT), respectively. Echocardiography, in vivo contrast-μCT, and invasive hemodynamic measurements were performed. The researchers used an artificial intelligence (AI)-based convolutional neural network (CNN) approach to reconstruct, segment, and analyze the cardiac μCT images. The RV functional reserve was evaluated during mCT acquisition and dobutamine stress test, and metabolomics analysis was performed. Results: The data showed that SuHx rats developed maladaptive cardiac function and RV-PA uncoupling. MCT rats exhibited adaptive RV function at days 14 and 21, but maladaptive function at day 35, which was associated with RV-PA uncoupling and reduced RV functional reserve. Impaired PKA-CREB signaling pathway was also found to be associated with the reduced RV functional reserve in the MCT rats. In both PH models, the absolute RV blood volume significantly increased with the development of RV hypertrophy, but the relative blood volume decreased, which was associated with maladaptive RV function Conclusions: This study is the first to demonstrate the use of AI CNN in post-processing of μCT-derived cardiac images from experimental PH models. Additionally, a single-beat PV loop was established for the first time in a rat model of PH by combining non-invasive and invasive techniques. The findings suggest that RV maladaptive function in rat models of PH is characterized by capillary rarefaction, impaired RV reserve in response to dobutamine infusion, which is associated with impaired PKA-CREB signaling pathway in the RV.