A B S T R A C T In a previous paper, we showed that the abnormality of ristocetin-induced platelet aggregation in platelet-rich plasma in 10 patients with von Willebrand's disease could be corrected by a factor in normal plasma that was present in the same fractions as factor VIII procoagulant activity (antihemophilic factor, AHF, VIIIAHF) when prepared by chromatography on BioGel 5 M (Bio-Rad Laboratories, Richmond, Calif.). This observation suggests that patients with this disorder are deficient in a plasma factor, associated with the factor VIII molecule, that is necessary for normal platelet function. In the present paper, we describe, an assay for this factor, the von Willebrand factor (VIIIvwF), based on the observation that a log-log relationship exists between the amount of ristocetin-induced aggregation of washed, normal platelets and the concentration of normal plasma present in the test system. We assayed the activity of VIIIvwF as well as antihemophilic factor procoagulant activity (VIIIAHF) and factor VIII antigen (VIIIAGN)
To investigate the association between chondrocalcinosis (CC) and osteoarthritis (OA), 338 joint specimens were examined histologically (55 knees and 84 hips surgically resected because of idiopathic OA, 106 control knees obtained postmortem, and 93 fractured hips). The risk for CC in the OA knees was sixfold that of the ageand sex-adjusted control sections. CC occurred much less frequently in the hip than in the knee; the association with OA was less clear-cut. It was not possible to resolve by statistical analysis which of the two pathological processes was the horse and which was the cart.Many published reports address the coexistence of chondrocalcinosis (CC) and osteoarthritis (OA), but there is much controversy about the frequency and significance of the association (1-8). Determining the relationship between the two processes is complicated by the fact that each lesion occurs with a certain frequency in the absence of the other, and both are related to age. The principal calcinotic deposits found are those of calcium pyrophosphate dihydrate (CPPD) crystals. Various concepts about the association of CC and OA can be resolved into 5 categories, as follows: 1) There is no relationship between CC and OA (2,3,9); 2) CPPD crystal deposi-
Holding onto the front handrail during treadmill testing significantly increases total treadmill time (TT) and predicted VO2max when compared with tests without front handrail support. By limiting the amount of handrail support to the tips of two fingers of one hand, the difference in TT can be substantially reduced. In the present study, the difference in TT between tests with and without handrail support for healthy men was not significantly different. However, this was not true for healthy women and for male patients with coronary artery disease and myocardial infarction.
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