Utility of the PFA-100 as a screening test of platelet function: an audit of haemostasis laboratories in Australia and New Zealand.

The PFA-100 is a relatively new laboratory instrument, first described in 1995. There have since been numerous studies assessing its utility as a screening tool for platelet dysfunction and/or von Willebrand's disease (VWD). The PFA-100 displays variable sensitivity to different types of platelet disorders, as well as to antiplatelet medication (e.g. aspirin), with similar caveats for monitoring of primary haemostasis-promoting therapies in platelet dysfunction. There is therefore considerable uncertainty regarding its utility within this context, and we have accordingly performed an audit of usage among participants of the Royal College of Pathologists of Australasia Quality Assurance Program. Of 105 laboratories surveyed, 40 responded that they performed platelet function testing, with 26 (65%) further indicating they utilized the PFA-100. We report a wide variety of laboratory usage among these users, including numbers of tests performed [annual median (range) = 270 (15-6000)], sources of requests (clinical sources and localities), testing criteria and follow-up action. Most tests were completed within 4 h of collection, as recommended by the manufacturer, and most tests were performed as a replacement, or as a preliminary screen of platelet function (i.e. classical aggregation). Most abnormal findings, however, were attributed to antiplatelet medication such as aspirin.     

Acute leriche syndrome due to paradoxical embolism.

Paradoxical embolism, describing the passage of venous or right-sided cardiac thrombus into the arterial or systemic circulation through patent foramen ovale, is an uncommon cause of acute arterial occlusion. Here, we report acute Leriche syndrome in a young woman attributable to paradoxical embolism. Ischaemia, patent foramen ovale, and venous thrombosis were the triad of evidence for paradoxical embolism.     

The high prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma

BACKGROUND: Although many histopathologic factors in squamous cell carcinoma of the tongue predict the prognosis, the major predictive factors have not been identified clearly. This study analyzed the prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma. METHODS: The clinicopathologic features of 124 consecutive patients seen between January 1985 and December 1999 with previously untreated squamous cell carcinoma of the tongue were reviewed. Their mean age was 58.5 years (range: 23-90) and the male-female ratio was 1.8: 1 (79 men and 45 women). There were 41, 40, 30, and 13 cases at stage I to stage IV, respectively. The clinicopathologic factors, especially the histologic grade at the deep invasive front (invasive front grade, IFG), were analyzed to determine factors predicting prognosis. RESULTS: The 5-year disease-free survival rate of the patients treated with curative aim only was 66.7%. Clinicopathologic factors significantly associated with the prognosis were T classification, tumor size, stage classification, tumor depth, macroscopic appearance, cervical lymph node metastasis (nodal metastasis), microvascular invasion, and IFG. In a multivariate analysis, patients with tumor depth >/=4 mm, IFG >/=8 points, and nodal metastasis had a reduced disease-free survival and IFG >/=11 points had a predictive value for nodal metastasis (odds ratio: 7.34; P = 0.0019). CONCLUSION: This study found that a high IFG malignancy score had a high prognostic value for squamous cell carcinoma of the tongue.     

A reaction route graph analysis of the electrochemical hydrogen oxidation and evolution reactions

The reaction route (RR) graph approach recently developed by us for complex, non-linear kinetic mechanisms is applied to the hydrogen oxidation and evolution reactions. A corresponding RR graph is constructed and translated into an equivalent electrical circuit network by associating each elementary step with a characteristic resistance for the steady-state case and considering the overall reaction as a power source. It is further shown that the steady-state kinetics of the reaction can be investigated employing the conventional methods of the electrical network theory. Using a set of rate constants for the hydrogen evolution reaction (her) in alkaline solutions from the literature, the dominant RRs are identified and simplified mechanisms and kinetics derived.