Dose-response characteristics of galactose-induced cataract in the rat

The onset and progression of cataract was investigated in weanling Sprague-Dawley rats fed 10, 15, 20 and 30% dietary galactose (groups 1-4) for 45-226 days. Cataracts were graded on a 0-5 scale. After 226 days, 9% of the rats fed 10% galactose developed lesions beyond the very early stage of cataractogenesis (grade 1). After 154 days 50% of the rats fed 15% galactose developed subcortical cataract (grade 3) with no nuclear cataract. In the rats fed 20% galactose, an initial rapid development by 31 days of a grade 3 cataract was observed in 50% of the eyes. Advancement to grade 4 and grade 5 cataract proceeded more slowly; by 207 days, 45% of the eyes had grade 5 cataract. In rats fed 30% galactose, rapid vacuolization and development of nuclear cataracts (grade 5) were observed by day 44. Dietary galactose at levels of 20 and 30% was associated with a significant reduction in weight gain at the early stage of dietary treatment. These observations demonstrate that 10-30% dietary galactose induces cataract in rat lens in a dose- and time-dependent fashion. These data serve to further establish this animal model as a useful model for studying the sequelae of cataractogenesis.

Ascorbic acid-selenite interactions in humans studied with an oral dose of 74SeO3(2-)

The interaction between dietary ascorbic acid at extremes of ascorbic acid intake and selenium in young adult male humans was investigated with a stable-isotope approach using 74Se-selenite. Measurements were made of 74Se in plasma, urine, and feces with neutron-activation analysis after oral administration of 74SeO3(2-). Urine excretion and total body retention of isotope and the selenite-exchangeable metabolic pool (Se-EMP) were calculated. Limiting dietary ascorbic acid to about 20 mg/d appeared to reduce the time-related retention of absorbed selenite and the size of Se-EMP. Compared with a diet providing 1 g ascorbic acid/d the low ascorbic acid intake was associated with a lower fractional absorption of the isotope, a reduced retention of the label, and a smaller Se-EMP. These data and those previously obtained in subjects with more usual ascorbic acid intakes point to a possible important role for ascorbic acid in the maintenance of Se homeostasis.

Propranolol treatment of essential tremor

Propranolol treatment of patients with essential tremor, selected for chronic, nonresting tremor of hands and head causing functional impairment, benefited only one of nine patients during a double-blind study (320 mg per day). No serious cardiorespiratory complications occurred in this screened patient group, but an elderly man became agitated and depressed. We conclude that propranolol does not benefit all patients with essential tremor and that this disorder may be caused by several biochemical mechanisms.