Platelets are small fragments, but they are of crucial importance for the coagulation. The risk of spontaneous bleeding increases when the level of Platelets falls below a thrombocyte particle concentration threshold value of 50 x 109/L. In those cases a platelet transfusion might be compulsory. Ongoing research tries to improve the quality of the Platelets and to increase the safety of the method used. However, we still need to better understand which factors that affect how patients react upon platelet transfusion.

 Conclusion:Medical treatment may have a role in platelet count after transfusion. Since the TACSI Platelets passed the quality requirements, and the vast majority of patients platelet count increased after TACSI platelet transfusion, the TACSI Platelets will replace the old method to produce Platelets at the Uppsala University hospital.  Methods: A new approach that pools 8 buffy coats (TACSI Platelets) that were separated into 2 units instead of 4-6 buffy coats pooled to 1 unit was investigated in this study. After the Platelets were extracted from the buffy coats their quality was controlled and subsequently the platelet product was evaluated in 96 patients. Results: The results showed that 80 % of the platelet units passed the European quality requirements. Further, the platelet count was increased in most patients that received TACSI Platelets. Conclusion: Medical treatment may have a role in platelet count after transfusion.

Tissue factor (TF), a 47 kDa glycoprotein, is the initiator of the extrinsic pathway of blood coagulation and consequently of the upmost importance when damage to blood vessel occurs. The source of TF in circulation has been investigated. However, the source of TF is still not clear. One theory is that Platelets express and increases the expression of TF after stimulation and the aim of our report was to investigate whether Platelets really are a source for TF in circulation.Using specific primers for TF mRNA, Platelets in plasma from healthy volunteers and from patients suffering from cardiac infarction were analyzed by using real-time polymerase chain reaction (PCR). Gel electrophoresis was performed after amplification of TF mRNA to verify the results.The samples were negative for TF when using real-time PCR and the few positive all had cycle threshold (Ct) values above 35.

Platelet aggregation is a major and common problem in blood samples from cats. This greatly affects the accuracy of counting of the Platelets. Because of the difficulties in counting feline Platelets, results for patients and reliable reference values for cat Platelets are currently so inaccurate as to be almost useless in diagnosis of thrombocytopenia. In this study we used an effective method to prevent platelet aggregation. Blood was collected in CTAD test tubes and prostaglandin E1 was added to the blood sample.

Platelets are important for the healing of damaged blood vessels since they have an importantpart to play in the coagulation process. At the same time, the blood must be kept fluid and notcoagulate at the wrong time. Therefore there are factors that effect the aggregation of Plateletsin a positive or a negative way.Previous investigations have shown that Platelets during stirring conditions produce reactiveoxygen species (ROS) that weaken the inhibiting effect of nitric oxides (NO) on Platelets andthat the drug Dexamethasone (Dex) can reduce the ROS-production.The aim of this project was to investigate if glucocorticoids, in this case Dexamethasone,could restore the inhibiting effect of NO on Platelets and if there was any decrease in ROS-production.The result of the ROS-measurements showed a great variance and it was difficult to draw anyconclusions from them, but a clear decrease in ROS, as previous reported, was not shown. In the aggregation experiments the inhibiting effect of NO was observed through the drug S-nitroso-N-acetylpenicillamine (SNAP), a NO-donator.From the aggregation experiments, the result seemed to be that SNAP during longerincubation time lost its inhibiting effect, probably because the cells become desensitized.With superoxid dismutase (SOD), the effect of SNAP increased, both in the experiment withlonger and shorter incubation times. Dex seemed to reinforce the aggregation in relation toboth SOD and SNAP.

Platelet transfusions can be necessary during treatment of patients with thrombocytopenia or impaired platelet function. Platelet function in platelet concentrates (PC) deteriorate with storage time. Studying swirling is often used to control the quality of PC?s before transfusion but the method has some disadvantages. Therefore other methods can be useful, for example impedance aggregometry (IA, Multiplate® Analyzer) to measure platelet function.     In this study the change in platelet function over time was examined in buffy coat and apheresis Platelets with IA where aggregation had been induced with adenosine diphosphate (ADP) and collagen.

During the years 2005-2007 several cases of abnormal bleeding were seen after surgery in Bengal cats on veterinary clinics and animal hospitals in Sweden. In this study we have examined if the observed bleedings are due to an inherited defect of the coagulation cascade. Ten Bengal cats were tested for activated partial thromboplastin time (P-APT-time) and one-stage protrombin time (P-PK), and nine of these cats were tested for fibrinogen quantity (P-fibrinogen). Four of the tested cats had shown signs of an abnormal bleeding after surgery, and five of the cats were genetically related to these cats. One cat had a small bleeding wound at the internal base of the right auricle.

Introduction: It is recommended to place all the vacuum tubes directly on a sample cradle after vein puncture to prevent analytic error. This recommendation is not always easy to follow because the samples are taken by different professionals under different situations.  The three most common analyses, Platelets count, haemoglobin and prothrombin time were tested.  Therefore, it was interesting to compare results from the three most common analyses with or without sample cradle, to evaluate the influence of this step on the result. Methods: Three analyses were preformed, using blood from 50 different persons. Each person gave two vacuum tubes, each contained 4.5mL of venous blood for the study.