The effect of anticoagulation on platelet size stability was studied using blood collected in seven different anticoagulants and stored at room temperature for up to eight hours. The mean platelet volume (MPV) value was most stable in blood collected in 15% ACD and ACD/Na2EDTA. In blood collected in Na2EDTA, K3EDTA, or 11.9% ACD, there was an increase in MPV in the first two hours, after which the MPVs remained stable up to eight hours. Sodium citrate and heparin proved unreliable for the measurement of platelet volume. Platelet counts were stable (less than 5% variation) in all anticoagulants except heparin, which had 16% variation for the eight hours of study. Simultaneously, RBC counts and mean corpuscular volume (MCV) measurements were stable in all seven anticoagulants, with sodium citrate producing the most variation. A negative correlation was observed between MCV and pH of the anticoagulated blood. WBC counts showed less than 3% variation in all anticoagulants except sodium citrate and heparin. Separate experiments demonstrated that electrolyte composition, pH, tonicity, and method of calcium chelation all influenced the stability of the MPV. Of the anticoagulants studied, ACD/Na2 EDTA appeared to provide the best conditions of anticoagulation for both routine clinical and research laboratory measurement of the MPV. It inhibited platelet activation but left the platelets in their normal discoid shape. Platelets could be removed from the anticoagulant and studied in functional assays for up to eight hours after blood drawing. Both platelet counts and MPVs remained stable in blood collected in ACD/Na2 EDTA anticoagulant for up to eight hours at room temperature. In 52 volunteers studied, an inverse correlation (r = -0.72, P less than 0.001) was observed between platelet count and MPV, suggesting that the circulating platelet mass may be a more important indicator of platelet homeostasis than either the platelet count or the mean platelet volume alone.
Neurilemmomas (schwannomas) are solitary neurogenic tumors that arise from cells of the neural sheath. They are slow growing and represent a proliferation of Schwann cells. Extracranial neurogenic tumors of the head and neck are uncommon, with benign tumors occurring with greater frequency than malignant tumors. These tumors often mimic primary or metastatic disease in the head and neck. Schwannoma of the salivary gland is a particularly rare form of an extracranial neurogenic tumor, with most presenting in the parotid gland originating from a peripheral branch of the facial nerve. An unusual case of neurilemmoma of the submandibular gland is presented, and the literature concerning this subject is reviewed. We believe this tumor originated in an autonomic nerve of the submandibular gland. The mass was discrete and well demonstrated on CT scan. Total excision of the gland resulted in complete resolution of symptoms with no cranial nerve deficits.
Recent advances in electrical cell sizing have made mean platelet volume (MPV) routinely available in most clinical laboratories. To study the importance of anticoagulation on platelet size stability, blood was collected in 7 different anticoagulants and stored at room temperature for up to 8 hours. Platelet counts and platelet sizing were performed using whole blood on a Coulter S+ and using platelet-rich plasma on a Coulter H4 Channelyzer. The results suggest that both calcium chelation and acidification were required to inhibit platelet shape change and aggregation. Electrolyte composition, pH, and tonicity of the anticoagulant all influenced the stability of the MPV. As a result of these studies, an anticoagulant combining ACD and Na2EDTA at a pH of 5.0 and an osmotic strength of 308 m0sm/1 was used to study platelet volume and counts in whole blood on a Coulter S+ used in the hematology laboratory of our hospital. Platelet counts with ACD-Na2EDTA anticoagulant were no different from routine Na2EDTA platelet counts and exhibited 2.9% error in reproducibility and a 4.4% variability over the 8 hours of storage. Mean platelet volumes were reproducible to within 3% and had less than 1% variability over the 8 hours of storage. Platelets anticoagulated with ACD-Na2EDTA remained discoid in shape and could be shown to undergo a shape change on stimulation with ADP up to at least 8 hours after collection, when the pH was adjusted to 7.4 and the Ca++ concentration restored.These data demonstrate that platelet count and platelet volumes remained stable in blood collected in ACD-Na2EDTA anticoagulant for up to 8 hours at room temperature. In 52 volunteers studied, an inverse correlation (r=.72, p<0.001) was observed between platelet count and MPV, suggesting that the circulating platelet mass may be a more important indicator of platelet homeostasis than either the platelet count or the mean platelet volume alone.
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