Measurement of pulmonary erythromycin concentration in patients with lobar pneumonia by means of positron tomography

The concentration achieved in the infected tissue is of fundamental importance in the use of antibiotics. Erythromycin labelled with the positron-emitting nuclide carbon-11 and positron tomography were used to compare local concentrations of this antibiotic in the pneumonic and unaffected lungs of five patients with lobar pneumonia. The time course of uptake of erythromycin into the extravascular compartment (i.e., the intracellular, interstitial, and alveolar compartments) of the pneumonic lung was measured. The mean extravascular concentrations obtained during the first hour after an intravenous injection of 270 mg erythromycin lactobionate were similar in the pneumonic lung and the unaffected lung (5.5 +/- 2.2 and 6.6 +/- 2.2 micrograms/g, respectively). An effective concentration of erythromycin was reached in the pneumonic lung within 10 min of the injection and was maintained throughout the period of measurement (60 min).

The synergistic effect of weight loss and changes in dietary lipids on the serum cholesterol of obese men with hypercholesterolaemia: implications for prevention of coronary heart disease

The hypolipidaemic effect of a low-fat, low-cholesterol diet, alone and in combination with weight reduction, has been evaluated in two groups of obese men with hypercholesterolaemia. In 41 men who lost 10.3 kg over 11 months and maintained their lower weight for 23.5 months serum cholesterol fell by 1.68 mmol/l and remained steady at lower weight. In 20 similar men, the controls, whose weight fell by 0.8 kg over 39.5 months, serum cholesterol fell by 0.80 mmol/l. There was a significant linear correlation between change in weight and change in serum cholesterol. The change in serum cholesterol in the weight losers was greater than could be accounted for by change in dietary lipids. Weight reduction and low-fat, low-cholesterol diets appear to have a synergistic effect in reducing serum cholesterol.

Type-IV hyperlipidaemia and weight-gain after maturity

Twenty men with mild to moderate type-IV hypertriglyceridaemia were compared with normal men of the same age in the Busselton population survey. The type-IV men were not heavier but they were 3-2 cm. shorter and relatively hyperuricaemic. When gives a reducing diet, mean weight declined from 76-8 kg. to 68-7 kg. over 4-4 months and was kept steady over the next 10 months at 67-6 kg. Before, immediately after, and in the 10 months after weight reduction serum-triglycerides were 273, 112, and 126 mg. per 100 ml. and serum-cholesterol was 245, 227, and 226 mg. per 100 ml., respectively. On entry the mean daily calorie intake was 3165 and the contribution of the various nutrients were characteristic of the Australian diet. At lower weight, daily caloric intake was 2335. Protein intake was unchanged, but intake of fat and especially carbohydrate declined significantly. The findings support the view that type-IV hyperlipidaemia is the expression of a metabolic defect brought to light by weight-gain after maturity. In susceptible subjects "normal" weight-gain may be sufficient to induce hyperlipidaemia. Since type-IV and type-IIb hypertriglyceridaemias appear to increase the risk of coronary heart-disease, it is concluded that ideally no weight should be gained after reaching maturity. Avoidance of weight-gain should materially reduce the incidence of coronary disease in affluent western communities. Reduction to truly ideal weight gives much more impressive therapeutic results than drug therapy.

Diet and atherosclerosis

Diet and atherosclerosis are closely linked, both aetiologically and therapeutically. The aetiological association can be demonstrated most satisfactorily in animal experiments. In human beings the evidence must necessarily be more indirect and is largely based on dietary trials and epidemiological surveys linking the intake of cholesterol and saturated fat with morbidity and mortality from coronary disease. A modifying influence which has gained increasing recognition over recent years is the individual response to a given diet. This variability appears to be largely genetically determined, certainly in the defined primary hyperlipidaemic states, and possibly within the normal ranges of serum cholesterol levels. A change in food habits should be fully utilized therapeutically in any form of hyperlipidaemia, whether as a primary preventive measure before clinical diseases of atherosclerotic origin become manifest or in secondary prevention to delay further morbidity and mortality. With good dietary adherence, lipid levels may return to normal and there may be additional favourable effects on intravascular thrombosis. Many problems remain to be solved on the public health issue of advising changes in the national diet. A number of countries in which an atherogenic diet is habitually eaten have decided in favour of such a recommendation. Public education, identification of persons at risk and provision of readily available skilled medical and dietary counselling should constitute a national health project with rewarding long-term results.

Use of 18F labelled fluorocarbon-11 to investigate the fate of inhaled fluorocarbons in man and in the rat

Williams, Faith M., Draffan, G. H., Dollery, C. T., Clark, J. C., Palmer, A. J., and Vernon, P. (1974).Thorax, 29, 99-103. Use of ¹⁸F labelled fluorocarbon-11 to investigate the fate of inhaled fluorocarbons in man and in the rat. The distribution and elimination of ¹⁸F labelled fluorocarbon-11 has been followed in a group of rats killed after air breathing following six minutes' exposure to ¹⁸F fluorocarbon-11. Whole body and individual organ count rates were measured. In four volunteers the fate of ¹⁸F labelled fluorocarbon-11 was followed by both whole body counting and gamma camera measurement of the activity in the lung and mouth region after inhalation from a specially loaded aerosol dispenser.

In the rat there was a high initial level in high blood flow organs and in the adrenals and fat: the level in blood and high blood flow organs fell rapidly. Elimination from fat was slow but the adrenal level had fallen within one hour. The fall in whole body count rate was similar to that in fat.

In man, the fall in lung concentration was consistent with rapid uptake into tissues followed by slow elimination; the whole body count rate curve also indicated slow elimination. There was no evidence of deposition of droplets of fluorocarbon in the mouth region after use of the aerosol.