In this retrospective study, the computed tomography (CT) archives of paranasal sinus examinations were reviewed and three cases of antroliths are presented. The archivesof paranasal sinus CT studies of 1957 patients (1023 females, 934 males, mean age 36.5 years) were surveyed. CT studies were performed using 3 mm collimation and interval in the coronal, axial or both coronal and axial planes.

Three out of 1957 patients demonstrated antroliths, all in the left maxillary sinus. Associated sinusitis was detected in all three patients. Only one patient was operated. The chemical analysis of the antrolith revealed it to be a calcium oxalate stone. All the relevant literatureis reviewed and only 25 other cases of true antrolithiasis were encountered. The clinical and radiological features of antroliths,as well as differential diagnosis were discussed.

Antrolithiasis should be considered in any case of sinusitis, that does not respond to appropriate medical therapy.

Urinary Mg is suggested to be an effective inhibitor of the formation and growth of calcium oxalate stones. In order to examine the influence of variations in dietary Mg on urinary Mg excretion, ten healthy male subjects were kept on two different standard diets for 5 d each. In the course of the test period, 24 h urine samples were collected. Diets 1 and 2 were calculated according to the dietary recommendations of the German Society of Nutrition (Deutsche Gesellschaft für Ernährung, 1986). Diet 1 was established as a model of a balanced mixed diet, whereas diet 2 represented an ovo-lacto-vegetarian meal plan. Diets 1 and 2 were isoenergetic with equal amounts of the main nutrients, estimated from food tables, and a constant fluid intake. In contrast to the content of Mg (336 mg) and dietary fibre (28 g) of diet 1, diet 2 was rich in Mg (553 mg) and dietary fibre (52 g). On the ingestion of diet 1, renal Mg excretion was 5·09 (SEM 0·35) mmol on the control day and increased slightly but not significantly to 5·40 (SEM 0·52) mmol on the corresponding day on diet 2. Urinary Mg excretion as a percentage of estimated dietary intake was about double on the balanced mixed diet (37%) than on the Mg-rich vegetarian diet (24%). As both diets contained equal amounts of most nutrients, these results indicate a lower excretion rate of Mg from the vegetarian diet than from the mixed diet. This would appear to be primarily due to the higher Mg and fibre contents and to the lower Mg utilization, that are important factors in decreasing Mg absorption and consequently urinary excretion rate.

By using the isotopic equilibrium method in the young male Syrian hamster, the rates of cholesterol turnover processes, i.e. dietary cholesterol absorption, cholesterol synthesis, cholesterol excretion in the faeces and urine and cholesterol transformation into bile acids, were determined in the hamster receiving a control (C) or a lithogenic diet (L) for 7 weeks. At the end of this period the gall bladder of all animals in group L contained cholesterol gallstones. The coefficient of dietary cholesterol absorption was reduced by 26 %, cholesterol synthesis and cholesterol faecal excretion were twofold higher in group L than in group C. Bile acid content in the small intestine was diminished in group L, but bile acid composition was similar in the two groups. The increase in cholesterogenesis in lithiasic animals essentially took place in the liver. Bile acid biosynthesis did not significantly differ in the two groups, but represented only 35 % of total cholesterol input (dietary absorption + internal secretion) in group L ν. 52% in group C. Thus, in the lithiasic hamster, hepatic synthesis of cholesterol and bile acids are not coupled. The molar percentage of cholesterol in bile was twofold higher in group L than in group C but those of bile acids and of phospholipids were not modified. In the lithiasic hamster the specific activity of biliary cholesterol was similar to that in plasma and liver. Consequently, biliary cholesterol does not derive directly from cholesterol newly synthesized in the liver but from hepatic cholesterol rapidly exchangeable with plasma cholesterol.