Relationships between platelet counts, platelet volumes and reticulated platelets in patients with ITP: evidence for significant platelet count inaccuracies with conventional instrument methods.

The platelet count has a primary role in the diagnosis and treatment of idiopathic thrombocytopenic purpura (ITP). This study analysed the accuracy of ITP patient platelet counts determined by Abbott CD-Sapphire (impedance/optical) and Bayer Advia 120 (optical) analyses, compared with a reference immunoplatelet method. Instrument platelet estimates showed broad equivalence in the higher range of observed values, but significant discrepancies against the immunoplatelet count were seen when platelet counts were <10 x 10(9)/l. CD-Sapphire mean platelet volume (MPV) results revealed increased (>12 fl) platelet volumes in eight of eight ITP patients with counts of <20 x 10(9)/l compared with 6/6 and 5/13 patients with platelet counts of 20-50 and >50 x 10(9)/l. In contrast, Bayer Advia MPV values showed no relationship with the platelet count. Increased reticulated platelets were associated with an increasing CD-Sapphire MPV (R(2) = 0.61) and a decreasing platelet count. High (>40%) reticulated platelet values were seen in 9/9 patients with immunoplatelet counts of <20 x 10(9)/l compared with 0/19 patients with platelet counts above 20 x 10(9)/l. There may be a need for caution in the interpretation of platelet counts in ITP patients obtained with conventional instrument methods, and therapeutic decisions should ideally be validated by reference immunoplatelet procedures.

Observation of Laser-induced Explosion of Solid Materials and Correlation with Theory.

A high speed framing camera was used to record the sequential steps of the start, development, and cessation of a highly energetic plume of matter caused by a ruby laser pulse of intensity of the order of 10(7) W/cm(2) on alumina ceramic and copper materials. The results of the experiments have established that the laser intensity and a normalized absorption coefficient are the two most important factors to be considered for any material removal process such as hole drilling. This study has provided the experimental support of a theoretical analysis on laser-induced vaporization and explosion of solid material, developed and published previously.