Calcium-induced platelet aggregation in washed platelets from guinea pigs

Innate coagulability changes with age in stored packed red blood cells

BACKGROUND

Packed red blood cell (pRBC) units administered during resuscitation from hemorrhagic shock are of varied storage ages. We have previously shown that RBC-derived microparticles' impact on thrombogenesis. However, the impact of storage age on pRBC coagulability is unknown. Therefore, we sought to investigate the effect of storage age on innate coagulability and aggregability of stored pRBCs.

METHODS

pRBCs prepared from male C57BL/6J mice were stored in Additive Solution-3 according to our standardized murine blood banking protocols for 14 days. Rotational thromboelastometry (ROTEM) was used to assess the innate coagulation status of fresh and 14-day old pRBCs. Viscoelastic coagulation parameters of clotting time (CT), clot formation time (CFT), alpha angle, and maximum clot firmness (MCF) were analyzed to determine coagulability. Plasma was added to the fresh pRBCs and 15-day old pRBCs to determine if the storage-associated coagulopathy was reversible with plasma. Statistical analyses were conducted with a Student's t-test.

RESULTS

Fifteen-day old pRBCs demonstrated a significant reduction in MCF (10.3 vs. 24.4 mm, P-value <0.001) and alpha angle (6.0 vs. 27.2 degrees, P-value <0.001) as well as significant prolongation of CFT and CT (1126.5 vs. 571.4 s, P-value <0.001) compared to fresh pRBCs. FFP addition to 15-day old and fresh pRBCs, demonstrated a significant reduction in MCF and persistent prolongation of CFT. This suggests that pRBCs lost coagulability as they aged and this deficit was not completely corrected by plasma administration.

CONCLUSIONS

Storage duration may be an important factor in coagulation potential of pRBCs. Transfusion with older pRBCs may contribute to coagulopathy in massively transfused patients.

Effects of ethanol on aggregation, serotonin release, and amyloid precursor protein processing in rat and human platelets

It is known that oxidative stress leads to amyloid precursor protein (APP) dysregulation in platelets. Ethanol (EtOH) is a vascular risk factor and induces oxidative stress. The aim of the present study was thus to investigate whether EtOH affects APP processing in rat and human platelets. Platelets were exposed to 50 mM EtOH with and without 2 mM calcium-chloride (CaCl₂) for 20 or 180 minutes at 37°C. Platelet aggregation, serotonin release and APP isoforms 130 and 106/110 kDa were analyzed. As a control, 100 mM H₂O₂ was tested in rat platelets. Our data show that EtOH alone did not affect any of the analyzed parameters, whereas CaCl₂ significantly increased aggregation of rat and human platelets. In addition, CaCl₂ alone enhanced serotonin release in rat platelets. EtOH counteracted CaCl₂-induced aggregation and serotonin release. In the presence of CaCl₂, EtOH reduced the 130 kDa APP isoform in rat and human platelets. In conclusion, this study shows that in the presence of CaCl₂, EtOH affects the platelet function and APP processing in rat and human platelets.

Calcipotriol toxicity in a dog

A six-month-old Labrador retriever was presented for investigation of acute polyuria, polydipsia and haematemesis six hours following ingestion of a tube of the topical antipsoriatic vitamin D analogue, calcipotriol. Transient hypercalcaemia, azotaemia, proteinuria, thrombocytopenia and ventricular arrhythmias ensued. Abdominal ultrasonography and echocardiography revealed evidence of diffuse soft tissue mineralisation. Despite 13 days of intensive supportive care, the dog was euthanased due to continued haematemesis and anorexia. Necropsy confirmed mineralisation and necrosis of multiple organ systems consistent with vitamin D toxicity.