We studied retrospectively 38 children who presented with urolithiasis between 1970 and 1977. The sex ratio was 1:1 and the mean age was 9.4 years. A positive family history was found in 36 per cent. Urinary tract abnormalities predisposing to infective urolithiasis was found in 7 children (18 per cent) but required voiding cystography for detection in 5. Hypercalcemia was found in 3 of 32 (8 per cent), while 28 of the 38 patients (74 per cent) had idiopathic urolithiasis. Idiopathic hypercalciuria was found in 5 of 13 patients (38 per cent) with idiopathic urolithiasis. Investigation of urolithiasis in children should include voiding cystography and measurement of urine calcium, as well as oxalate and uric acid, under home diet conditions.

Six subjects with normal renal jimction (NRF) and 6 patients with minimal renal function (MRF) on 3 times weekly hemodialysis received 150 jJ-Ci :lH-digoxin-120' orally. Serial urine collections were made for jive days or more. Digoxin and metabolites were separated using diethylaminoethyl Sephadex LH-20 column chromatography. Mean cumulative percentages of the ingested radioactivity excreted over jive days in NRF and MRF groups were: digoxin, 54.5% and 14.7%; bis-digilOxoside of digoxigenin, 2.0% and 0.50%; mono-digitoxoside, 0.8% and 0.19%; digoxigenin, 0.25% and 0.03%; and dihydrodigoxin, 0.3% and 0.03%. Haif~lives based on the mean rates of disappearance from urine comparing NRF and MRF groups were: for digoxin, 40 hr and 120 hr; for bis-digitoxoside, 11.5 hr and 46 hr;for mono-digitoxoside, 8.5 hr and 12 hr; for digoxigenin, 2 hr and 7.5 hr; and for dihydrodigoxin, 1.2 hr and 7.0 hr. Considering the relationships of the jive-day cumulative excretion and half-lives of digoxin and metabolites in the NRF and MRF groups, it appears unlikely that there is a major alteration in the biotransformation of digoxin in advanced renal failure It'hen There appears to be a shijt from renal to slower hiliary excretion.

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It is difficult for rats to learn to go to an arm of a T-maze to receive food that is dependent on the time of day, unless the amount of food in each daily session is different. In the same task, rats show evidence of time-place discriminations if they are required to press levers in the arms of the T-maze, but learning is only evident when the first lever press is considered, and not the first arm visited. These data suggest that rats struggle to use time as a discriminative stimulus unless the rewards/events differ in some dimension, or unless the goal locations can be visited prior to making a response. If both of these conditions are met in the same task, it might be possible to compare time-place learning in two different measures that essentially indicate performance before and after entering the arms of the T-maze. In the present study, we investigated time-place learning in rats with a levered T-maze task in which the amounts of food varied depending on the time of day. The first arm choices and first lever presses both indicated that the rats had acquired time-place discriminations, and both of these measures became significantly different from chance during the same block. However, there were subtle differences between the two measures, which suggest that time-place discrimination is aided by visiting the goal locations.

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