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Two cross-sectional and one longitudinal study of patients with rheumatoid arthritis showed that platelet number correlated with both clinical and laboratory parameters of disease activity, including erythrocyte sedimentation rate, zeta sedimentation ratio, viscosity of plasma and blood, white cell count, liver enzymes, rheumatoid factor, and several acute-phase proteins. There was also an inverse relationship between platelet number and the haemoglobin and serum albumin levels. III Indium-labelled platelet survival was reduced in 4 patients with active rheumatoid arthritis despite a raised platelet count, with labelled platelets being localised to inflamed joints in the 2 patients studied. Platelet aggregation was normal. We suggest that the raised platelet count of active rheumatoid arthritis may be a useful index of disease activity and may represent a bone marrow stress (syndrome) response to shortened platelet survival, with platelet sequestration occurring in areas of synovial inflammation. [ABSTRACT FROM PUBLISHER]

Indium 111-labeled platelet scintigraphy was performed to evaluate platelet deposition in response to different levels of Nd:YAG laser/thermal energy. A dose-related increase in platelet deposition was observed. In clinical studies after laser-assisted balloon angioplasty, intense platelet deposition was observed in 2 patients who subsequently developed clinical arterial thrombosis. The pathogenesis of reocclusion appears, however, to be more complicated and ill under- stood. The authors suggest further extensive studies incorporating several parameters in the evaluation of the pathogenic factors involved in reocclusion after laser angioplasty. Such studies should also consider the role of arterial in- jury produced by the balloon catheter after laser-assisted balloon angioplasty. [ABSTRACT FROM AUTHOR]

The properties of fibrinogen extracted by a precipitation method using glycine at ambient temperatures near neutral pH are described. The simple and reproducible method gives a 73% yield of high purity plasminogen-free fibrinogen in 45 minutes from small volumes of plasma. The protein extract was labelled with 125I using chloramine-T under conditions optimal for fibrinogen stability. The extraction procedure, radio-iodination, desalting, and sterilization take only 70 minutes for completion from the time donor blood is received in the laboratory. The methods, using a specially developed extraction vessel and desalting/sterilizing column, can be used in a small hospital laboratory. Autologous fibrinogen can thus be extracted from patients' blood, eliminating the risk of transmitting hepatitis when it is re-administered. The autologous material, which is 97% clottable and contains less than 0-05% free iodide, is being routinely used as a diagnostic tool in the detection of deep vein thrombosis. The high purity of the preparation facilitates metabolic studies and in vitro experimental work. In vivo results show a mean half-life in three normal volunteers of 3-95 days and a catabolic rate of 25-23% per day with the extravascular space estimated as 24-86%. In 30 surgical patients an expected reduced half-life in plasma was determined with a mean of 3-1 days. [ABSTRACT FROM PUBLISHER]