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Biomedical subjects

G Ainslie

Publications and source records attributed to G Ainslie.

10 recordsLinked to original sources
PubMed1999

Beyond discounting: possible experimental models of impulse control.

Animal studies of impulsivity have typically used one of three models: a delay of reward procedure, a differential reinforcement for low rate responding (DRL) procedure, or an autoshaping procedure. In each of these paradigms, we argue, measurement of impulsivity is implicitly or explicitly equated with the effect delay has on the value of reward. The steepness by which delay diminishes value (the temporal discount function) is treated as an index of impulsivity. In order to provide a better analog of human impulsivity, this model needs to be expanded to include the converse of impulsivity - self-control. Through mechanisms such as committing to long range interests before the onset of temptation, or through bundling individual choices into classes of choices that are made at once, human decision-making can often look far less myopic than single trial experiments predict. For people, impulsive behavior may be more often the result of the breakdown of self-control mechanisms than of steep discount functions. Existing animal models of self-control are discussed, and future directions are suggested for psychopharmacological research.

Animals↗
PubMed1993

IgE specific immune responses to an African grass (Kikuyu, Pennisetum clandestinum)

Kikuyu grass (Pennisetum clandestinum) is widely used as a grazing pasture in Africa and, although it is extensively cultivated as a lawn for sports fields and domestic gardens, its allergenicity has never been studied in vitro. Using an extract of Kikuyu grass pollen, polyacrylamide gel electrophoresis, Western blotting and a monoclonal anti-human IgE antibody, the specific IgE binding, in the serum of 160 allergic and non-allergic patients in the Cape Town area, to a Kikuyu grass extract was studied. IgE in the sera of 43/104 known grass-allergic individuals bound to Kikuyu grass on the Western blots. In addition, 4/28 'non-allergic' control subjects were found to have Kikuyu grass-specific IgE. Five different profiles of specific IgE reactivity to Kikuyu grass antigens were observed. In 29/43 patients, IgE bound to two dominant 48 and 70 kD allergens in the Kikuyu extract. Although a degree of cross-reactivity with Bermuda grass (Cynodon dactylis) was found in immunoabsorption studies, the 48 and 70 kD allergens appear to be unique to Kikuyu grass. Exposure of heparinized blood from Kikuyu grass-positive patients to the Kikuyu extract stimulated the release of histamine from their basophils in vitro. Kikuyu grass pollen is thus identified as an important aero-allergen in South Africa.

Allergens↗
PubMed1990

Routine antenatal ultrasonography in a base population.

The use of diagnostic ultrasonography has profoundly enhanced the practice of obstetrics. Its use on a routine basis in pregnancy, though, is still debated. We evaluated a policy of routine second trimester ultrasonography in our base population to determine if it improved obstetrical care. In comparison to a historical control group, our study group had fewer patients going beyond 42 weeks and a significantly lower Cesarean section rate for those requiring an induction for post dates. The use of routine antenatal ultrasonography improved obstetrical care in our population.

Adult↗
PubMed1987

Self-reported tactics of impulse control.

Recent behavioral research has suggested that delayed incentives are discounted in a highly concave curve, which should produce temporary preference for the poorer of two alternatives when that alternative is available earlier than the better one. Unlike the psychoanalytic model of impulsiveness, the temporary preference model implies a rational need for people to forestall impulses by committing their choices in advance. A questionnaire elicited college students' and prisoners' self-reports of approval of four basic kinds of precommitting tactics as applied to 14 commonplace temptations. Endorsement of private rules as a precommitting device was correlated with self-reported compulsive personality traits and negatively correlated with endorsement of extra-psychic (social or physical) devices; the latter endorsement was correlated with self-reported oral/paranoid traits. Female subjects endorsed attention control as a precommitting device more than males, and male subjects endorsed extrapsychic devices more than females. The ego psychology of conflict may be practical at the conscious level.

Adolescent↗
PubMed1982

Glycoprotein hormone alpha-subunit secretion in patients with pituitary adenomas: influence of TRH, LRH and bromocriptine.

Twelve patients with pituitary adenomas and increased serum concentration of the glycoprotein hormone alpha-subunit were studied. Eight patients were acromegalic and one had a FSH producing tumour. The adenomas in 9 patients had undergone subtotal operative removal and/or external irradiation but no patient was studied within 3 months of these treatments. Many of the acromegalic patients, with moderately elevated alpha-levels, showed marked increases in alpha-concentration after TRH and/or LRH, compared with controls. The non-acromegalic patients, with the highest alpha-levels, showed poor responses to releasing hormones. These results suggest that excessive alpha-subunit secretion in acromegalic patients is often under hypothalamic control whereas in non-acromegalic patients it is often autonomous. Seven patients, 4 with acromegaly, were then given oral bromocriptine, 5 mg over 3 h. There was a significant fall in log mean alpha-level at 4 and 5 h (P less than 0.02). Six patients took bromocriptine for 1--2 months. Log mean alpha-concentration was significantly reduced at the end of treatment (P less than 0.02) and then recovered to basal levels after stopping treatment for one week. alpha-Subunit hypersecretion in some patients with pituitary adenomas is therefore modulated by dopaminergic control mechanisms.

Acromegaly↗