Hydroxychloroquine inhibits hemolysis-induced arterial thrombosis ex vivo and improves lung perfusion in hemin-treated mice.

BACKGROUND: Free labile hemin acts as a damage-associated molecular pattern during acute and chronic hemolysis and muscle injury supporting platelet activation and thrombosis. AIM: We investigated the anti-thrombotic potential of hydroxychloroquine on hemolysis-induced arterial thrombosis ex vivo, hemin-induced platelet activation, ferric-chloride (FeCl3)-induced arterial thrombosis and lung perfusion following hemin injection in mice. RESULTS: Erythrocyte lysis and endothelial cell activation cooperatively supported platelet aggregation and thrombosis at arterial shear stress. This thrombotic effect was reversed by hydroxychloroquine. In a purified system, hydroxychloroquine inhibited platelet build-up on immobilized von Willebrand factor in hemolyzed blood without altering initial platelet recruitment. Hydroxychloroquine inhibited hemin-induced platelet activation and phosphatidylserine exposure independently of reactive oxygen species generation. In the presence of hemin, hydroxychloroquine did not alter glycoprotein VI shedding but reduced C-type-lectin-like-2 expression on platelets. In vivo, hydroxychloroquine reversed pulmonary perfusion decline induced by exogenous administration of hemin. In arterial thrombosis models, hydroxychloroquine inhibited FeCl3-induced thrombosis in the carotid artery and reduced von Willebrand factor accumulation in the thrombi. CONCLUSION: Hydroxychloroquine inhibited hemolysis-induced arterial thrombosis ex-vivo and improved pulmonary perfusion in hemin-treated mice, supporting a potential benefit of its use as an adjuvant therapy in hemolytic diseases to limit arterial thrombosis and to improve organ perfusion.

Comparison of insulin infusion protocols for management of canine and feline diabetic ketoacidosis.

OBJECTIVE: Describe the use of fixed-rate intravenous insulin infusions (FRIs) in cats and dogs with diabetic ketoacidosis (DKA) and determine if this is associated with faster resolution of ketosis compared to variable-rate intravenous insulin infusions (VRIs). Secondary objectives were to evaluate complication rates, length of hospitalization (LOH), and survival to discharge (STD). DESIGN: Randomized clinical trial (January 2019 to July 2020). SETTING: University veterinary teaching hospital and private referral hospital. ANIMALS: Dogs and cats with DKA and venous pH <7.3, blood glucose concentration >11 mmol/L (198 mg/dL), and ß-hydroxybutyrate (BHB) concentration >3 mmol/L were eligible for inclusion. Patients were randomly assigned to receive either FRI or VRI. INTERVENTIONS: Neutral (regular) insulin was administered IV as an FRI or VRI. For FRI, the rate was maintained at 0.01 IU/kg/h. For VRI, the dose was adjusted according to blood glucose concentration. MEASUREMENTS AND RESULTS: Sixteen cats and 20 dogs were enrolled. Population characteristics, mean insulin infusion rate, time to resolution of ketosis (BHB <0.6 mmol/L), complications, LOH, and STD were evaluated. In cats, overall resolution of ketosis was low (9/16 [56.3%]), limiting comparison of protocols. In dogs, resolution of ketosis was high (19/20 dogs [95.0%]) but the time to resolution in the FRI group was not different than that in the VRI group (P = 0.89), despite a 25% higher average insulin infusion rate in the FRI group (P = 0.04). The incidence of complications was low and did not differ between protocols. In cats, LOH and STD did not differ between protocols. All cats that died (5/16) did so within 78 hours and none had resolution of ketosis. Dogs receiving FRI had a shorter LOH (P = 0.01) but STD did not differ between protocols. Six dogs (30.0%) did not survive to hospital discharge but all had resolution of ketosis. CONCLUSIONS: FRIs can be used in veterinary species but may not hasten resolution of ketosis.

Novel mechanisms of thrombo-inflammation during infection: spotlight on neutrophil extracellular trap-mediated platelet activation.

A state-of-the-art lecture titled "novel mechanisms of thrombo-inflammation during infection" was presented at the ISTH Congress in 2022. Platelet, neutrophil, and endothelial cell activation coordinate the development, progression, and resolution of thrombo-inflammatory events during infection. Activated platelets and neutrophil extracellular traps (NETs) are frequently observed in patients with sepsis and COVID-19, and high levels of NET-derived damage-associated molecular patterns (DAMPs) correlate with thrombotic complications. NET-associated DAMPs induce direct and indirect platelet activation, which in return potentiates neutrophil activation and NET formation. These coordinated interactions involve multiple receptors and signaling pathways contributing to vascular and organ damage exacerbating disease severity. This state-of-the-art review describes the main mechanisms by which platelets support NETosis and the key mechanisms by which NET-derived DAMPs trigger platelet activation and the formation of procoagulant platelets leading to thrombosis. We report how these DAMPs act through multiple receptors and signaling pathways differentially regulating cell activation and disease outcome, focusing on histones and S100A8/A9 and their contribution to the pathogenesis of sepsis and COVID-19. We further discuss the complexity of platelet activation during NETosis and the potential benefit of targeting selective or multiple NET-associated DAMPs to limit thrombo-inflammation during infection. Finally, we summarize relevant new data on this topic presented during the 2022 ISTH Congress.

Retrospective evaluation of factors influencing transfusion requirements and outcome in cats with pelvic injury (2009-2014): 122 cases.

OBJECTIVE: To characterize a population of cats with pelvic trauma and evaluate factors influencing transfusion requirement and outcome. DESIGN: Retrospective case series (2009-2014). SETTING: University teaching hospital. ANIMALS: One hundred twelve client-owned cats with pelvic trauma. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Twenty-one (18.8%) cats received a transfusion. Most cats required only 1 fresh whole blood transfusion (85.8%). Packed cell volume at admission was significantly lower in cats that required transfusion but was not associated with hospitalization time or survival to discharge. Increasing Animal Trauma Triage (ATT) score at admission was significantly associated with transfusion requirement (P = 0.0001) and nonsurvival to discharge (P = 0.03). Number of pelvic fractures was not associated with transfusion requirement but cats with sacroiliac luxations and pubic fractures were more likely to require a transfusion (P = 0.0015 and P = 0.0026, respectively). However, fracture type was not associated with survival to discharge. Most cats (86%) required a surgical procedure and half of transfusions were administered preoperatively. No surgical comorbidities were associated with transfusion requirement or survival. Transfusion requirement was associated with longer length of hospitalization but not survival to discharge. CONCLUSIONS: Transfusion requirement in this population of cats with pelvic fractures was fairly high. Transfusion requirement was associated with lower packed cell volume, higher ATT score at admission, longer length of hospitalization, and certain types of pelvic fractures. Transfusion requirement was not associated with surgical comorbidities, surgical intervention, or survival to discharge. Lower ATT score at admission was associated with survival to discharge.

Can you estimate body composition in dogs from photographs?

BACKGROUND: A validated method for assessing the visual characteristics of body condition from photographs (vBCS), would be a useful initial screening tool for client-owned dogs. METHODS: In this retrospective study, photographs taken before and after weight loss from 155 overweight and obese dogs attending a weight management referral clinic were used in designing and testing the feasibility of vBCS. Observers with a range of experience examined the photographs, and estimated body condition indirectly (vBCS) using three different methods. In the first method (vBCSmeasured), the ratio of abdominal width to thoracic width (A:T) was measured, and cut-points used to determine body condition; the second method (iBCSsubjective) involved semi-quantitative examination using visual descriptors of BCS; the third (vBCSadjusted) was a combined approach whereby A:T ratio was first determined, and the final score modified if necessary after assessing photographs. RESULTS: When an experienced observer performed vBCS, there were moderate-to-good associations between body fat (measured by dual-energy X-ray absorptiometry) and the three vBCS methods (median Rs: 0.51-0.75; P < 0.001), and also moderate-to-substantial agreement with actual BCS (median kappa 0.51-0.63; P < 0.001). For operators with a range of experience, moderate-to-substantial agreement was generally seen between actual BCS and the scores determined by all three methods (median Kappa 0.55-0.70, P < 0.001), but the strength of agreement varied amongst observers. Age, sex, breed, coat length, and coat colour had no significant effect on vBCS (P > 0.05 for all). Compared with ideal weight and obese dogs, errors in assessing body condition were more common for overweight dogs (e.g. BCS 6-7/9, P < 0.001) by vBCSadjusted (P = 0.008), and vBCSsubjective (P = 0.021), but not by vBCSmeasured (P = 0.150). For vBCSadjusted, body condition was most often overestimated whilst, for vBCSsubjective, body condition was most often under-estimated. CONCLUSIONS: An estimate of body condition can be obtained from an indirect assessment of photographs, but performance varies amongst observers.