A cost-effectiveness analysis of alternative approaches for long-term treatment of proximal venous thrombosis

Recent data from randomized trials have provided a clear understanding of the effectiveness and safety of differing long-term anticoagulant therapies for proximal vein thrombosis. An issue that has not been addressed is their cost-effectiveness. We have performed a cost-effectiveness analysis to rank alternative approaches for long-term therapy. Less intense oral anticoagulant therapy using warfarin sodium is the most cost-effective approach and is preferred in the majority of patients.     

Heparin clearance and ex vivo recovery in newborn piglets and adult pigs

The newborn infant requires more heparin per kg body weight than the adult to achieve similar heparin plasma levels. Possible mechanisms include altered heparin pharmacokinetics and/or a decreased expression of anticoagulant activity of heparin in newborn plasma because of low levels of antithrombin III (AT-III). We measured the pharmacokinetics and the anticoagulant activity of heparin in the pig (AT-III level:100%), in the piglet (levels of AT-III: 50% of adult) and the piglet given exogenous porcine AT-III. All pigs were bolused with ¹²⁵I-heparin (25 or 100 units/kg) and blood samples collected for the measurement of ¹²⁵I-radioactivity, and antifactor Xa activity. The half-life of ¹²⁵I-heparin was dose-dependent and similar in pigs and piglets; however, the volume of distribution was greater in the newborn resulting in an increased total clearance compared to the pig. The anti-factor Xa activity disappeared earlier in the piglet than in the pig. Both the kinetics and the absolute recovery of anti-factor Xa activity were normalized to pig values (after correction for different volumes of distribution) when the piglets were infused with exogenous AT-III. Thus apparent heparin resistance of the newborn is due to both an increased volume of distribution and the low AT-III level which limits the measurement of the anticoagulant activity of heparin in conventional anti-factor Xa assays.     

The effect of reduced temperature on the inhibitory action of adenosine and magnesium ion at frog motor nerve terminals.

1. A study was made to exclude the notion that adenosine receptor agonists exert a direct physical blockade of the depolarization-secretion process. Reduced temperature was employed as a tool for distinguishing between physico-chemical processes (such as those which mediate evoked transmitter release) and biochemical mechanisms (such as those which involve second messenger substances) in the action of adenosine. Adenosine and 2-chloroadenosine were used as agonists in this electrophysiological study of the release of acetylcholine (ACh) from frog motor nerve terminals. 2. The ability of these two adenosine receptor activators to reduce neurally-evoked ACh release was prevented or greatly attenuated by maintaining the preparation at temperatures between 5 and 10 degrees C. Such low temperatures inhibit the activation of receptors coupled to second messengers via guanine nucleotide binding proteins (e.g. adenylate cyclase). Low temperature alone did not substantially alter evoked ACh secretion under the conditions of these experiments. 3. Inhibition of evoked ACh release by the extracellular Ca antagonist Mg, which acts directly to block Ca channels, was not affected by low temperature. 4. The results are consistent with the hypothesis that a temperature-sensitive second messenger system controls the intracellular events linked to extracellular adenosine receptor activation.     

Smoking cessation: The psychological costs

To assess the psychological effects of smoking cessation, 21 subjects in a smoking treatment program were evaluated at the beginning of therapy and 4 months later. No differences were observed in reported affect, use of mental health facilities, psychotropic medications, or alcohol. A statistically but not clinically significant weight increase was observed. It is concluded that within some contexts smoking cessation need not be as stressful as popularly depicted.