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I . The extent of liberation of radioactive cobalamin in rabbit tissues incubated with acid and pepsin was evaluated by bag dialysis.2. Between a half and two-thirds of the cobalamin-probably hydroxocobalamin-was dialysable after acid pepsin treatment and this process may be a factor in the absorption of cobalamins from foods.3. Studies of pure cobalamin solutions at different concentrations gave apparently anomalous results, which may have been due to the adherence of cobalamin to the dialysis membrane. Measurement of the amount adherent to the membrane is an important factor in dialysis studies with cobalamins.?' he absorption by man of cobalamins from food is believed to be mediated by the intrinsic factor mechanism. Cobalamins in foodstuffs are not free, but are bound to protein; it is probable that the first stage of absorption involves rupture of the cobalamin-food protein bond and binding of the freed cobalamin to intrinsic factor. As intrinsic factor is secreted in the gastric juice, these processes probably take place in the stomach. The mechanisms, however, are not clear. Observations on the in vitro liberation of tissue-bound cobalamins by acid and pepsin, which we report here, may have a bearing on these mechanisms. In addition we record relevant observations on free cyanocobalamin and hydroxocobalamin. E X P E R I M E N T A LHealthy Dutch rabbits weighing about 3 kg were obtained from the Veterinary School, University of Glasgow, and given a diet of pellets containing white fish meal 10 yo, grass 20 %, bran 40 %, ground oats 12 % and middlings 18 %, water ad lib. and supplements of greens and hay. The animals were given a single subcutaneous dose of 4-6 pg (40-60 pc) [57Co]hydroxocobalamin and 5-6 weeks later were killed by injection of air into the heart. The skeletal muscle, liver and kidneys were removed, weighed and stored at -2 0 ' . Thawed, sliced tissues were homogenized with distilled water in a Waring Blendor at approximately 15000 rev./min for 20 min. About half of each homogenate was dispensed in 4 m l portions in plastic tubes and stored at -2 0 ' . The remainder was divided into 20 ml portions in glass screw-capped bottles and heated at 15 lb/in2 for 20 min; after cooling, the cooked tissues were pooled, homogenized without the addition of water and dispensed in 4 ml portions in plastic tubes and stored at -20'.

Renal Function after Leptospirosis-Simpson et al. MEDICAL JOURNAL 473 instances six, serotypes. In only two were the maximum titres against the serotypes responsible for the original infection. DiscussionOur results suggest that the long-term prognosis after the acute renal lesion of leptospirosis is good. Thus in the British patients all the results of renal function tests were normal except for a slightly reduced creatinine clearance in one man; as the serum creatinine level and other results in him were normal the significance of this isolated finding is doubtful. Another man developed hypertension, but renal damage did not appear to be the cause. One group of Gurkha patients had normal creatinine clearances but all did not concentrate urine adequately, while in the others these findings were reversed; since each abnormality was confined to one group it seems likely that these discrepancies reflect incomplete dehydration and incomplete urine collection respectively.As intravenous pyelograms were performed in only four patients, and renal biopsy in none, we

The serum vitamin B₁₂ level was estimated in 100 patients with jaundice due to various causes. The overall incidence of abnormally high values, when compared with values from 100 control subjects, was 16% and there was little difference between the proportion of abnormally high values in the main diagnostic categories. No diagnostic or prognostic value could be attached to an abnormally high result or to a normal result.

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