Studies were carried out on multiple urine samples from eight patients with recurrent idiopathic calcium oxalate stone formation and eight normal persons to define an index of the risk of forming calcium oxalate stones. Under the same conditions of dietary and fluid intake the urine samples of the patients with stone formation were more supersaturated with calcium oxalate (P less than 0.001) and had lower concentrations of protective inhibitors of crystallization (P less than 0.001) than those of the controls. However, the best separation between the groups was defined by a discriminant line relating inhibitory activity and urine saturation. A measure of the risk of forming large crystals, the saturation-inhibition index, was defined as the distance of each urine from the discriminant line. The patients with stone formation had a significantly higher mean saturation-inhibition index than the controls (P less than 0.001). Both the percentage of large calcium oxalate crystals excreted (P less than 0.001) and the stone episode rate (P less than 0.005) were significantly correlated with the saturation-inhibition index.

Analysis of human horizontal saccadic eye movements can provide measurements of central nervous system depression and stimulation. Effects on saccadic eye movements have been observed in normal volunteers with barbiturates, benzodiazepines, opiates and related compounds, carbamazepine, amphetamine and ethanol. A suite of programmes have been developed to allow the generation, collection and analysis of saccadic eye movements using a CBM 3032, 8032 or BBC B microcomputer. The system allows almost continuous sampling and rapid analysis of movements.

A massive disc herniation can pursue a favourable clinical course. If early progress is shown, the long-term prognosis is very good and even massive disc herniations can be treated conservatively.

1.The short-term effects of different intakes of calcium and oxalic acid on the urinary excretion of these substances was studied in eight normal men and eight men with a history of calcium-containing renal stones.2. The effect of dietary oxalate on urine oxalate depended partly upon the calcium intake. Thus, on a normal calcium intake an increase in oxalate intake caused an increase in oxalate excretion that corresponded to 3.6% of the additional dietary oxalate; on a low calcium diet, however, the increase corresponded to 8.1%.3. A decrease in daily calcium intake from lo00 to 250 mg caused a fall in calcium excretion averaging 150 mg/day in the patients and 60 mg/day in the controls but this was accompanied by average rises of 10 and 7 mg/day respectively in oxalate excretion, with the result that the calcium oxalate activity products remained almost unchanged. 4.A decrease in oxalate as well as calcium intake resulted in a fall in calcium excretion that was not accompanied by a rise in oxalate excretion, and there was a statistically significant fall in the calcium oxalate activity product in both the patients and normal subjects.Key words: urinary calcium, urinary oxalic acid, renal stones, dietary calcium, dietary oxalic acid. & Nordin (1968, 1971) have shown that both normal and stone-forming urines are commonly supersaturated with respect to calcium oxalate but the mean level of supersaturation is significantly higher in patients with frequently-recurring calcium stones than in normal subjects. These results support the view that calcium stone formation is due primarily to oversaturation of urine with calcium oxalate. Robertson, PeacockThe higher degree of saturation of stone-forming urines is due primarily to higher concentrations of total and ionized calcium (Robertson et al.,