Biomedical subjects
Publications and source records attributed to H H Samson.
A new principle is described which eliminates the need for expiratory valves in anaesthetic circuits. Scavenging of waste anaesthetic gases is also achieved. The innovations are simple, allow easy cleaning and sterilization, and can be regarded as disposable if necessary. The advantages of low circuit pressure and ease of operation are described.
Infant rat pups, fed through intragastric cannulas from postnatal day 4 through day 18, showed a 19 percent reduction in total brain weight when ethanol was included in their diet on days 4 through 7. This reduction in brain weight occurred even though body growth in the experimental rats was equal to that of their littermate controls. The ethanol-exposed animals were markedly hypoactive during the period of drug administration, then displayed gross body tremors for 3 to 5 days. Throughout the study, the animals treated with ethanol had poor motor coordination and were hyperresponsive. These brain and behavioral effects appear similar to those seen in fetal alcohol syndrome.
Rats were maintained in cages with automatic food dispensers that provided a 24 hr feeding regimen known to produce schedule-induced ethanol polydipsia. For ten days water was the only available fluid; then for 17 days either 5% or 10% ethanol replaced water. The ethanol concentrations were then switched between groups for a final 13 days. Ethanol intake increased for both groups over the first seven days and then reached asymptote. The daily intake (ml) of 5% ethanol was two times that of 10%, resulting in no difference between groups in g/kg ethanol consumed. When the concentrations were switched, g/kg/day dropped, but returned to previous levels within seven days. Again intake (ml) of 5% was two times that of 10% but groups did not differ in g/kg/day. Mean blood ethanol concentration at 9:30 hr was 75.0 mg/100 ml with 5% ethanol and 127.8% mg/100 ml with 10% ethanol.
Desalivate and control rats were tested for ethanol versus water preference (5%, 10% and 20% (v/v) ethanol solutions). Each concentration of ethanol was presented for six days in an ascending, descending, or mixed presentation schedule. Following preference tests, intakes of first 10% (15 days), then 5% (15 days), and finally 10% (5 days) ethanol as the only available fluid were determined. Blood ethanol concentrations were measured (22:00 hr, 24:00 hr, 02:00 hr) during the final 10% ethanol intake test. Desalivate and control rat showed similar aversions to ethanol at all concentrations with relative ethanol intake being a negative function of concentration. During ethanol and water intake for both groups intake of 10% ethanol was reduced significantly from water baseline levels. Although desalivates consumed as much ethanol as controls, their blood ethanol concentrations at all times tested were slightly lower than controls. During the ethanol intake test desalivate rats lost body weight, while control rats gained body weight.
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Ethanol elimination rates were determined in rats using an intravenous route of ethanol administration after several experimental manipulations. Twenty-four hr food deprivation resulted in a 30% reduction to 35 mg/100ml blood/hr in elimination rate from a non-deprived rate of 50 mg/100 ml blood/hr. After 2 months of ethanol drinking (5% v/v), 24 hr starvation resulted in only a 10% reduction in elimination rate (45 mg/100 ml blood/hr), and did not increase the non-food-deprived rate (49.2 mg/100 ml blood/hr) over that obtained in the above animals' drinking water rather than 5% ethanol. Animals which chronically overdrank ethanol or water for 3 months on a schedule-induced polydipsia procedure, known to result in ethanol physical dependence, showed a decreased rate of ethanol elimination (37.9 mg/100 ml blood/hr for water drinkers) in the non-food-deprived condition. By providing 750 mg of liver powder daily as a food supplement in the ethanol overdrinking regimen, the ethanol elimination rate remained at a rate comparable to the normal animal (48.4 mg/100 ml blood/hr).
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Rats maintained on an intermittent food schedule with an available ethanol solution drink to excess (13.1 grams of ethanol per kilogram of body weight, daily). Removal of ethanol produces symptoms of physical dependence including death from tonic-clonic seizures. Overindulgence in oral self-administration of an aqueous ethanol solution, resulting in unequivocal physical dependence, approximates a model of human alcoholism.
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