| RRT | random response technique; Registered Respiratory Therapist; relative retention time |
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| RS | radioscaphoid; random sample; rating schedule; Raynaud syndrome; recipient's serum; rectal sinus; re... |
| RTC | random control trial; rape treatment center; renal tubular cell; residential treatment center; retur... |
| RV | random variable; rat virus; Rauscher virus; rectovaginal; reinforcement value; renal vein; residual ... |
| SRAM | static random access memory |
| platelet count | <haematology> The number of platelets per cubic millimetre of blood. The normal range is 150,000-400,000 platelets per cubic mm. Platelet counts under 10,000 per cubic millimetre place the patient at risk for spontaneous haemorrhage. Platelets are produced in the bone marrow in increased quantities in response to stress. (27 Sep 1997) |
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| platelet-derived growth factor | <growth factor> The major mitogen in serum for growth in culture of cells of connective tissue origin. It consists of 2 different but homologous polypeptides A and B (~30,000 D) linked by disulphide bonds. Believed to play a role in wound healing. It is carried in the alpha-granules of platelets and is released when platelets adhere to traumatised tissues. Connective tissue cells near the traumatised region respond by initiating the process of replication. The B chain is almost identical in sequence to p28sis, the transforming protein of simian sarcoma virus, that can transform only those cells that express receptors for platelet derived growth factor, suggesting that transformation is caused by autocrine stimulation. The receptor is a tyrosine kinase. Acronym: PDGF (12 Dec 1998) |
| platelet endothelial cell activated protease | <enzyme> Degrades casein and fibrinogen; secreted by endothelial cells and activated in the extracellular medium by platelets; not inhibited by serine protease inhibitors, metalloproteinase inhibitors, or cystein protease inhibitors; pH optimum 7.5 Registry number: EC 3.4.99.- Synonym: pecap (26 Jun 1999) |
| platelet factor 3 | <haematology> Phospholipid associated with the platelet plasma membrane that contributes to the blood clotting cascade by forming a complex (thromboplastin) with other plasma proteins and activating prothrombin. (31 Dec 1997) |
| platelet factor 4 | <haematology> Platelet released protein that promotes blood clotting by neutralising heparin. (31 Dec 1997) |
| platelet function disorders | <haematology> Platelet function can be affected by a number of different disease processes including polycythaemia vera, leukaemia, myelofibrosis, renal failure, multiple myeloma and some medications (for example penicillins, salicylates, phenothiazines). Disturbed blood clotting can be manifested by: easy bruising, bleeding gums, nosebleeds, abnormal vaginal bleeding, rectal bleeding, skin rash, vomiting blood, coughing up blood or blood in the urine. A measure of bleeding time and coagulation profile will be part of the evaluation. (31 Dec 1997) |
| platelet glycoprotein gpib-ix complex | Platelet membrane glycoprotein complex essential for normal platelet adhesion and clot formation at sites of vascular injury. It is composed of three polypeptides, gpib alpha, gpib beta, and gpix. Glycoprotein ib functions as a receptor for von willebrand factor and for thrombin. Congenital deficiency of the gpib-ix complex results in bernard-soulier syndrome. The platelet glycoprotein gpv associates with gpib-ix and is also absent in bernard-soulier syndrome. (12 Dec 1998) |
| platelet glycoprotein gpiib-iiia complex | Platelet membrane glycoprotein complex important for platelet adhesion and aggregation. The complex is an integrin which recognises the arginine-glycine-aspartic acid (rgd) sequence present on several adhesive proteins. As such, it is a receptor for fibrinogen, von willebrand factor, fibronectin, vitronectin, and thrombospondin. A deficiency of gpiib-iiia results in glanzmann's thrombasthenia. (12 Dec 1998) |
| platelet membrane glycoproteins | Surface glycoproteins on platelets which have a key role in haemostasis and thrombosis such as platelet adhesion and aggregation. Many of these are receptors. (12 Dec 1998) |
| platelet storage pool deficiency | A group of disorders characterised by a decrease or lack of platelet dense bodies in which the releasable pool of adenine nucleotides and 5ht are normally stored. (12 Dec 1998) |
| platelet thrombosis | Thrombosis due to an abnormal accumulation of platelets. (05 Mar 2000) |
| platelet tissue factor | <haematology> Traditional name for substance in plasma that converts prothrombin to thrombin. Now known not to be a single substance. (See thrombin). (18 Nov 1997) |
| platelet transfusion | The transfer of blood platelets from a donor to a recipient or reinfusion to the donor. (12 Dec 1998) |
| low affinity platelet factor IV | Cytokine, produced from platelet basic protein, that acts as a growth factor. (18 Nov 1997) |
| low platelet count | <haematology> An abnormally low platelet count. Normal platelet counts are 150,000-400,000 per cubic millimetre. Those with low platelet counts may exhibit haematuria, haematemesis, easy bruising, bleeding gums, melena (blood in stools), prolonged menses or nosebleeds. Spontaneous intracranial haemorrhage can occur with platelet counts of 10-15,000 (or less). (27 Sep 1997) |