Developing a Clinically Relevant Hemorrhagic Shock Model in Rats.

Over the recent decades, the development of animal models allowed us to better understand various pathologies and identify new treatments. Hemorrhagic shock, i.e., organ failure due to rapid loss of a large volume of blood, is associated with a highly complex pathophysiology involving several pathways. Numerous existing animal models of hemorrhagic shock strive to replicate what happens in humans, but these models have limits in terms of clinical relevance, reproducibility, or standardization. The aim of this study was to refine these models to develop a new model of hemorrhagic shock. Briefly, hemorrhagic shock was induced in male Wistar Han rats (11-13 weeks old) by a controlled exsanguination responsible for a drop in the mean arterial pressure. The next phase of 75 min was to maintain a low mean arterial blood pressure, between 32 mmHg and 38 mmHg, to trigger the pathophysiological pathways of hemorrhagic shock. The final phase of the protocol mimicked patient care with an administration of intravenous fluids, Ringer Lactate solution, to elevate the blood pressure. Lactate and behavioral scores were assessed 16 h after the protocol started, while hemodynamics parameters and plasmatic markers were evaluated 24 h after injury. Twenty-four hours post-hemorrhagic shock induction, the mean arterial and diastolic blood pressure were decreased in the hemorrhagic shock group (p < 0.05). Heart rate and systolic blood pressure remained unchanged. All organ damage markers were increased with the hemorrhagic shock (p < 0.05). The lactatemia and behavioral scores were increased compared to the sham group (p < 0.05). In conclusion, we demonstrated that the protocol described here is a relevant model of hemorrhagic shock that can be used in subsequent studies, particularly to evaluate the therapeutic potential of new molecules.

Spontaneous Sepsis in Adult Horses: From Veterinary to Human Medicine Perspectives.

Sepsis is a life-threatening disease defined as an organ dysfunction caused by a dysregulated host response to an infection. Early diagnosis and prognosis of sepsis are necessary for specific and timely treatment. However, no predictive biomarkers or therapeutic targets are available yet, mainly due to the lack of a pertinent model. A better understanding of the pathophysiological mechanisms associated with sepsis will allow for earlier and more appropriate management. For this purpose, experimental models of sepsis have been set up to decipher the progression and pathophysiology of human sepsis but also to identify new biomarkers or therapeutic targets. These experimental models, although imperfect, have mostly been performed on a murine model. However, due to the different pathophysiology of the species, the results obtained in these studies are difficult to transpose to humans. This underlines the importance of identifying pertinent situations to improve patient care. As humans, horses have the predisposition to develop sepsis spontaneously and may be a promising model for spontaneous sepsis. This review proposes to give first an overview of the different animal species used to model human sepsis, and, secondly, to focus on adult equine sepsis as a spontaneous model of sepsis and its potential implications for human and veterinary medicine.

Beneficial Effects of O-GlcNAc Stimulation in a Young Rat Model of Sepsis: Beyond Modulation of Gene Expression.

The young population, which is particularly at risk of sepsis, is, paradoxically, rarely studied. Acute stimulation of O-GlcNAcylation, a post-translational modification involved in metabolic regulation, cell survival and stress response, is beneficial in young rats with sepsis. Considering that sepsis impacts the gene expression profile and that O-GlcNAcylation is a regulator of transcription, the aims of this study are to (i) unveil beneficial mechanisms of O-GlcNAcylation and (ii) decipher the relationship between O-GlcNAcylation and transcription during sepsis. Endotoxemic challenge was induced in 28-day-old male rats using a lipopolysaccharide injection (E. coli O111:B4, 20 mg·kg−1) and compared to control rats (NaCl 0.9%). One hour after, rats were assigned to no therapy or fluidotherapy (NaCl 0.9%, 10 mL.kg−1) ± NButGT (10 mg·kg−1) to stimulate O-GlcNAc levels. Cardiac O-GlcNAcylation levels were evaluated via Western blot and gene transcription using 3' SRP analysis. Lipopolysaccharide injection favorizes inflammatory state with the overexpression of genes involved in the NF-κB, JAK/STAT and MAPK pathways. NButGT treatment increased cardiac O-GlcNAcylation levels (p < 0.05). Yet, the mRNA expression was not impacted two hours after fluidotherapy or NButGT treatment. In conclusion, O-GlcNAc stimulation-induced beneficial effects are not dependent on the gene expression profile at the early phase of sepsis.

Comparison of Flunixin Meglumine, Meloxicam and Ketoprofen on Mild Visceral Post-Operative Pain in Horses.

The analgesic efficacy of meloxicam and ketoprofen against equine visceral pain is unclear. The aim of this study was to compare the analgesic efficacy of meloxicam (M) and ketoprofen (K) to flunixin meglumine (F) following inguinal castration. Horses undergoing inguinal castration under general anesthesia were randomly assigned F (1.1 mg/kg), M (0.6 mg/kg) or K (2.2 mg/kg) intravenously two hours pre-operatively and 24 h later. A pain score (out of 31) was recorded blindly by a senior clinician and veterinary student before NSAIDs administration (T0), and after the first (T1) and second (T2) administrations, using a modified post-abdominal surgery pain assessment scale (PASPAS). Pain was classified as mild (score ≤ 7), moderate (score = 8-14) or severe (score > 14). Thirty horses (12 F, 10 M, 8 K) aged 6.2 ± 4.9 years, mostly warmbloods, were included. Horse welfare was not compromised regardless of the drug assigned. There was no statistically significant effect of NSAIDs on pain score. Mean pain scores were significantly higher at T1 than T0 for each NSAID (F: 5.08 ± 2.50 vs. 1.58 ± 1.38 (p < 0.001); M: 4.60 ± 2.32 vs. 1.10 ± 1.20 (p < 0.001); K: 5.25 ± 1.39 vs. 1.50 ± 1.51 (p < 0.0001)) and lower at T2 than T1 for F (2.92 ± 2.423 vs. 5.08 ± 2.50 (p < 0.001)) and M (2.90 ± 1.37 vs. 4.60 ± 2.32 (p < 0.0325)). At T1, senior pain scores were significantly different than for junior (5.56 ± 0.54 vs. 3.22 ± 0.62, p = 0.005). This study indicates that meloxicam and ketoprofen provide a similar level of analgesia to flunixin meglumine for the management of mild visceral pain in horses. PASPAS is not reliable for junior evaluators.

An O-GlcNAcylomic Approach Reveals ACLY as a Potential Target in Sepsis in the Young Rat.

Sepsis in the young population, which is particularly at risk, is rarely studied. O-GlcNAcylation is a post-translational modification involved in cell survival, stress response and metabolic regulation. O-GlcNAc stimulation is beneficial in adult septic rats. This modification is physiologically higher in the young rat, potentially limiting the therapeutic potential of O-GlcNAc stimulation in young septic rats. The aim is to evaluate whether O-GlcNAc stimulation can improve sepsis outcome in young rats. Endotoxemic challenge was induced in 28-day-old rats by lipopolysaccharide injection (E. Coli O111:B4, 20 mg·kg-1) and compared to control rats (NaCl 0.9%). One hour after lipopolysaccharide injection, rats were randomly assigned to no therapy, fluidotherapy (NaCl 0.9%, 10 mL·kg-1) ± NButGT (10 mg·kg-1) to increase O-GlcNAcylation levels. Physiological parameters and plasmatic markers were evaluated 2h later. Finally, untargeted mass spectrometry was performed to map cardiac O-GlcNAcylated proteins. Lipopolysaccharide injection induced shock with a decrease in mean arterial pressure and alteration of biological parameters (p < 0.05). NButGT, contrary to fluidotherapy, was associated with an improvement of arterial pressure (p < 0.05). ATP citrate lyase was identified among the O-GlcNAcylated proteins. In conclusion, O-GlcNAc stimulation improves outcomes in young septic rats. Interestingly, identified O-GlcNAcylated proteins are mainly involved in cellular metabolism.

Two-dimensional speckle tracking echocardiography in goats: repeatability, variability, and validation of the technique using an exercise test and an experimentally induced acute ischemic cardiomyopathy.

BACKGROUND: Two-dimensional speckle tracking (2DST) technique has been validated in numerous animal species, but neither studies of repeatability nor measurements after exercise or in animals with cardiac disease have been reported in goats. Goats are an attractive candidate for animal models in human cardiology because they are easy to handle and have a body and heart size comparable to that of humans. Therefore, the aim of this study was to validate this technique in goats for further clinical and experimental applications in this species. RESULTS: This study was divided into several steps. First, a standardized echocardiographic protocol was performed and 5 cineloops of a right parasternal short-axis view at papillary muscles level were recorded three times at one-day intervals in ten healthy adult unsedated Saanen goats to test repeatability and variability of 2DST measurements. Then, the same measurements were performed immediately before and after a standardized exercise on treadmill in seven of the goats, and at 24 h after induction of an experimental ischemic cardiomyopathy in five of the goats, to test the reliability of the technique to assess physiological and pathological changes. Average and regional measurements of radial and circumferential strain and strain rate, radial displacement, rotation and rotation rate were obtained. Comparisons were performed using two-way ANOVA (p < 0.05). Caprine 2DST average measurements have demonstrated a good repeatability with a low to moderate variability for all measurements except for the diastolic peaks of the circumferential strain rate, radial strain rate and rotation rate. Segmental 2DST measurements were less repeatable than average measurements. Time effect of two-way ANOVA was significant for anteroseptal segment diastolic peaks measurements, rotation and rotation rate measurements. Overall variability of segmental measurements was moderate or high. Segmental and average peak values obtained after exercise and after myocardial ischemia were significantly different than curves obtained at baseline. CONCLUSIONS: The results of this study are consistent with those previously described in other animal species and humans. 2DST echocardiography is a valid technique to evaluate physiological and pathological changes in myocardial function in goats, despite the technical limitations observed in this species.

Prognostic value of echocardiographic and Doppler parameters in horses admitted for colic complicated by systemic inflammatory response syndrome.

OBJECTIVE: To assess the prognostic value of echocardiographic parameters of left ventricular (LV) function in horses with systemic inflammatory response syndrome (SIRS). DESIGN: Prospective observational study. SETTING: Veterinary teaching hospital. ANIMALS: Forty-one horses admitted for colic with clinical evidence of SIRS. INTERVENTIONS: All horses underwent Doppler echocardiographic examination on admission. LV echocardiographic parameters, including pulsed-wave tissue Doppler imaging parameters, were compared between nonsurvivors (n = 29) and horses that survived to discharge (n = 12). MEASUREMENTS AND MAIN RESULTS: With comparable heart rate and LV preload estimate, LV stroke volume index, the velocity time integral, deceleration time, ejection time of Doppler aortic flow, and peak early diastolic myocardial velocity were lower in the nonsurviving than in the surviving horses, while pre-ejection period to ejection time ratio (PEP/ET) of Doppler aortic flow and the peak early diastolic filling velocity to peak early diastolic myocardial velocity ratio (E/Em) were higher (P < 0.05). A cut-off value of 0.26 for PEP/ET predicted mortality with 100% sensitivity and 42% specificity (area under the receiver operating characteristic curve: 0.71), whereas a cut-off value of 2.67 for E/Em predicted mortality with 100% sensitivity and 83% specificity (area under the receiver operating characteristic curve: 0.89). CONCLUSIONS: Echocardiography may provide prognostic information in colic horses with clinical evidence of SIRS. Especially, PEP/ET and E/Em could be useful markers of systolic and diastolic dysfunction, respectively, to detect horses with a high risk of death requiring more intensive cardiovascular monitoring as it has been reported in human patients with septic shock.

Repeatability, variability and reference values of pulsed wave Doppler echocardiographic measurements in healthy Saanen goats.

BACKGROUND: Pulsed wave (PW) Doppler echocardiography has become a routine non invasive cardiac diagnostic tool in most species. However, evaluation of intracardiac blood flow requires reference values, which are poorly documented in goats. The aim of this study was to test the repeatability, the variability, and to establish the reference values of PW measurements in healthy adult Saanen goats. Using a standardised PW Doppler echocardiographic protocol, 10 healthy adult unsedated female Saanen goats were investigated three times at one day intervals by the same observer. Mitral, tricuspid, aortic and pulmonary flows were measured from a right parasternal view, and mitral and aortic flows were also measured from a left parasternal view. The difference between left and right side measurements and the intra-observer inter-day repeatability were tested and then the reference values of PW Doppler echocardiographic parameters in healthy adult female Saanen goats were established. RESULTS: As documented in other species, all caprine PW Doppler parameters demonstrated a poor inter-day repeatability and a moderate variability. Tricuspid and pulmonary flows were best evaluated on the right side whereas mitral and aortic flows were best obtained on the left side, and reference values are reported for healthy adult Saanen goats. CONCLUSIONS: PW Doppler echocardiography allows the measurement of intracardiac blood flow indices in goats. The reference values establishment will help interpreting these indices of cardiac function in clinical cardiac cases and developing animal models for human cardiology research.

Animal models of mitral regurgitation induced by mitral valve chordae tendineae rupture.

BACKGROUND AND AIM OF THE STUDY: Mitral regurgitation (MR) is a common valvular disease throughout the world. Various diagnostic techniques have been developed to assess the causes and severity of MR, and the therapeutic approaches to this disease have been widely documented. However, treatments for chronic MR remain controversial, and various animal models of chronic MR (including chordae tendineae rupture, rapid pacing and ischemia) have been developed to study the pathophysiology and therapeutic approaches to this condition. The study aim was to review the animal MR models that have been developed using a mitral valve chordae tendineae rupture technique. METHODS AND RESULTS: Among the animals used for these investigations, dogs and sheep have been most commonly used as models of MR induced by mitral valve chordae tendineae rupture, mainly due to considerations of cardiac size. Chordae tendineae cutting is performed using either closed- or open-chest techniques. In the closed-chest model, long flexible grasping forceps are positioned percutaneously in order to tear the mitral valve chordae. In the open-chest model, cardiopulmonary bypass is performed, and either selected chordae are cut under direct visualization or a non-specified number of chordae are cut, using a metal device inserted through the left ventricular apex. Whichever model is used, MR has been found to become chronic at three to six months after the induction of MR by chordae rupture. The reported mortality and complication rates of these models are high. CONCLUSION: In the long term, the experimental evolution of chronic MR is similar to the evolution occurring naturally in patients suffering from the condition. Hence, these models could be useful in understanding the disease better, and in testing new therapeutic modalities. The present review summarizes the physiological effects of each of these techniques, and compares the advantages and disadvantages of each procedure.