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Biomedical subjects

K Krafft

Publications and source records attributed to K Krafft.

8 recordsLinked to original sources
PubMed1990

A survey of the attitudes of physician specialists toward capitation-based health plans with primary care gatekeepers.

A survey of 414 Washington state physicians board certified in one of seven non-primary care specialties (gastroenterology, cardiology, dermatology, otolaryngology, orthopedics, psychiatry, and general surgery) assessed physician attitudes towards capitation-based health plans with primary care gatekeepers. Responses indicated significant differences in attitude according to specialty. Negative attitudes were more prevalent among physicians in solo practices and those practicing in smaller communities and were related to quality of care provided, lack of information regarding benefits, loss of physician autonomy, and heavy administrative demands in these plans. Although most respondents disapproved of capitation-based health plans, a significant number agreed that gatekeeper-based plans serve to increase public awareness about health care costs as well as to control health care costs.

Attitude of Health Personnel↗
PubMed1983

Discriminative stimulus properties of phenytoin in the pigeon.

Pigeons trained under a two-key drug discrimination procedure eventually learned to discriminate 5 mg/kg phenytoin from saline injections. When 1.25-20 mg/kg doses of phenytoin were substituted for the training dose, the percentage of responses directed to the phenytoin-appropriate key varied directly with dose. Chlorpromazine, d-amphetamine, diazepam, and phenobarbital failed to produce phenytoin-like patterns of responding.

Animals↗
PubMed1982

Effects of phenytoin on schedule-controlled performance of rats.

The present study examined the effects of acute administrations of phenytoin on the lever pressing of rats maintained under fixed-ratio, fixed-interval, and interresponse-time-greater-than-T schedules of food delivery. The drug typically produced dose-dependent decreases in response rates under fixed-ratio and fixed-interval schedules, while response rates under the interresponse-time-greater-than-T schedule were affected little by the drug. These findings indicate that phenytoin effects on schedule-controlled responding differ from those of other anticonvulsants.

Animals↗
PubMed1980

Water intake induced by spaced deliveries of salted and sweetened liquid food.

The water intake of food-deprived rats was evaluated under conditions where liquid food was presented occasionally. In the first experiment, when soybean milk alone was presented every 30 sec, little water was consumed. However, when sodium chloride was added to the soybean milk, water intake increased directly with salt concentration from 0.9 to 14.4%. At salt concentrations of 7.2 and 14.4%, the drinking induced by soybean milk resembled in several respects the adjunctive drinking educed by spaced presentations of dry food. In a second experiment, adulterating soybean milk with sugar in concentrations of 7 to 56% did not affect water intake significantly when the food was delivered every 30 seconds. These findings extend the range of conditions known to generate schedule-induced drinking, and point out a previously unknown constraint on the phenomenon.

Animals↗
PubMed1980

d-Amphetamine, operant history, and variable-interval performance.

The effects of d-amphetamine on the bar-pressing of rats maintained under a variable-interval schedule of water reinforcement were examined as a function of the operant history of the subjects. One group of rats initially received 51 sessions of exposure to a fixed-ratio 20 schedule, while a second group received equivalent exposure to an interresponse-time-greater-than-12-sec schedule. Mean group response rate when stable was over ten times as high under the fixed-ratio schedule as under the interresponse-time-greater-than-12-sec schedule. Response rates of the two groups largely converged across 47 sessions of exposure to a variable-interval 60-second schedule, at which time response rates for both groups appeared stable. Acute administration of d-amphetamine sulfate similary affected mean response rates of both groups: A 0.25 mg/kg dose did not obviously affect rate, while doses of 0.5, 1.0, and 2.0 mg/kg produced dose-dependent rate decreases. These results indicate that the efficacy of operant history as a determinant of drug effects may be limited to circumstances where current contingencies do not exercise powerful and direct control over behavior.

Animals↗
PubMed1980

Polydipsia induced by intermittent delivery of salted liquid foods.

Food-deprived rats given constant access to water were exposed to fixed-time presentations of soybean milk and diluted sweetened condensed cows' milk. In some conditions these liquid foods were adulterated with varying amounts of sodium chloride. Under a fixed-time 30-sec schedule of food delivery, little water was consumed when the food was soybean milk alone, or soybean milk with sodium chloride added in concentrations of .9, 1.8, or 3.6%. However, schedule-induced polydipsia appeared when soybean milk adulterated with 7.2 or 14.4% sodium chloride was delivered under this schedule. When soybean milk containing 7.2% sodium chloride was presented under fixed-time 15-, 30-, 60-, 120-, and 240-sec schedules, schedule-induced drinking increased with the fixed-time value from 15 to 120 seconds, and decreased at 240 seconds. Like soybean milk, diluted sweetened condensed milk delivered under fixed-time schedules of 30, 60, and 120 seconds failed to evoke schedule-induced polydipsia, but did so when adulterated with 7.2% sodium chloride. Drinking induced by salted liquid foods resembled the polydipsia engendered by spaced dry-food presentations in several ways, including temporal relation to food delivery, persistence within and across sections, sensitivity to interfood interval, and magnitude relative to intake evoked by bulk-food presentation.

Animals↗