Abrupt withdrawal of atenolol in patients with severe angina. Comparison with the effects of treatment.

The effects of abrupt withdrawal of atenolol, a long acting cardioselective beta blocker, were studied in 20 patients with severe stable angina pectoris admitted to hospital for coronary arteriography. During the 144 hour postwithdrawal period no serious coronary events occurred. Mean and maximal daily heart rates rose steadily for at least 120 hours. No important arrhythmias were noted on ambulatory electrocardiographic monitoring. Treadmill exercise testing at 120 hours showed little reduction in the times to angina, ST depression, and maximal exercise when compared with those recorded at 24 hours. This deterioration was small when contrasted with the improvements in these indices produced by atenolol treatment in a similar group of patients not admitted to hospital. No change in catecholamine concentrations or acceleration of the heart rate response to exercise occurred after atenolol withdrawal, suggesting that rebound adrenergic stimulation or hypersensitivity was absent or insignificant. Catastrophic coronary events after beta blockade withdrawal (the beta blockade withdrawal syndrome) have occurred almost exclusively in patients taking propranolol, many of whom had unstable angina at the time of withdrawal. This study showed that in patients with stable angina, even when severe, the abrupt withdrawal of atenolol can be expected to result in only minor clinical consequences. The risk to any patient of so called rebound events after withdrawal of beta blockade seems to be related to both the clinical setting and the agent being used.

Effect of total dose infusion of iron dextran on the storage iron content of the human placenta.

In a series of pregnant women with iron deficiency anaemia treated by a total dose infusion of iron dextran, the non-haem iron content of the placenta at term was studied histochemically and by chemical analysis. Within a few days of the infusion the Prussian blue reaction on the placenta was very strong, but was negative by ten days after the infusion. Chemical analysis showed that both the water-insoluble fraction (haemosiderin) and the water-soluble fraction (ferritin) of the non-haem iron were increased soon after the infusion, but three weeks after the infusion they were almost the same as in untreated controls. Pinocytosis of iron dextran by the trophoblast and increased transport of transferrin-bound iron to the placenta are considered as possible causes for this large uptake of iron by the placenta.

Cigarette smoking: acute main and small vessel hemodynamic responses in patients with arterial disease.

While cigarette smoking is a major risk factor in lower limb ischemia, not all smokers develop symptomatic lesions, which suggests an individual susceptibility. Using Doppler probes the acute main vessel response to smoking was quantified in terms of the pulse transit time delay. Patients with occlusive arterial disease had a significant shortening in the transit time delay, suggesting a stiffening in the main vessels in response to smoking not seen in control subjects without disease. In patients with occlusive disease the digital pulse volume recorder amplitude decreased significantly in response to both low and high nicotine cigarettes, and these patients tended to self-titrate their nicotine intake, suggesting that little is to be gained by switching from high to low nicotine cigarettes: rather, cessation of smoking should be considered. These preliminary results suggest that patients with atherosclerotic occlusive disease are more susceptible to cigarette smoking and that Doppler or pulse volume recorder testing may help identify those habitual smokers who are at risk.

Micro method for manual analysis of true glucose in plasma without deproteinization.

A sensitive micro method for the manual estimation of true glucose in 10 mul plasma by an enzymatic technique is described. Protein precipitation is avoided. The method is simple to perform, accurate and precise. Agreement with a glucose oxidase autoanalyzer method is excellent, even with haemolysed and icteric specimens.