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Biomedical subjects

S E Hampson

Publications and source records attributed to S E Hampson.

15 recordsLinked to original sources
PubMed1992

Improving self-care among older patients with type II diabetes: the "Sixty Something..." Study.

A 10-session, self-management training program was designed specifically for persons over 60 years of age having Type II diabetes. It targeted social learning variables, especially problem-solving skills and self-efficacy, found to be related to diabetes self-care in earlier correlational research. One hundred two adults were randomized to immediate or delayed intervention conditions. At posttest, subjects in the immediate intervention condition showed significantly greater reductions in caloric intake and percent of calories from fat than control subjects. The intervention also produced greater weight reductions and increases in the frequency of glucose testing than did the control condition. Improvements among immediate intervention subjects were generally maintained at a 6-month follow-up. Intervention results from subjects receiving delayed intervention closely replicated those for immediate intervention subjects. We conclude that a relatively short-term program can improve self-management skills of older diabetic adults, and that there is an important need for such interventions.

Aged↗
PubMed1991

The basic level in personality-trait hierarchies: studies of trait use and accessibility in different contexts.

A person's behavior and experiences can be described at different levels of abstraction. For example, a person might be described as charitable, as generous, as kind, or as good. Is there a level in such a trait hierarchy that is particularly useful in personality descriptions? The present 4 studies show that there is indeed a general preference for a particular level; the size of this preference depends on the familiarity and likability of the target people, which included various others and the self. These findings suggest that in trait hierarchies, people prefer the highest level of abstraction that is still descriptive of behavior (e.g., kind) over more descriptive subordinate levels (e.g., charitable and generous) and over an even broader level devoid of descriptive meaning (e.g., good). This level is basic in that it represents the optimal resolution of the trade-off between bandwidth and fidelity that characterizes all hierarchies.

Adult↗
PubMed1990

Forming impressions from incongruent traits.

The factors that affect the ease with which impressions are formed from incongruent trait pairs are investigated. In Experiments 1 and 2, trait pairs that were both descriptively and evaluatively congruent, as well as ones that were only evaluatively congruent, were found to be more imaginable and to be perceived as more frequently co-occurring than incongruent trait pairs. In Experiment 3, response latency provided a converging measure of ease of imaginability. Experiment 4 examined written descriptions of targets described by these trait pairs, and found more attempts to integrate the congruent than the incongruent pairs. These findings are discussed in terms of the relation between laypersons' impressions of personality and formal personality assessment.

Adult↗
PubMed1990

Personal models of diabetes and their relations to self-care activities.

Investigated the personal models of diabetes held by 46 female outpatients with non-insulin-dependent diabetes mellitus. The subjects' mean age was 64 years (range = 46 to 79 years), and 24 subjects were taking insulin. Their personal models were explored by using a comprehensive interview including questions on beliefs and emotions about cause, symptoms, course, treatment, and consequences of their diabetes. Two weeks after their interview, patients provided information about their levels of self-care activities, including exercise, diet, and glucose testing. The interview provided multiple indicators of the personal-model constructs from which four composites were formed assessing cause, symptoms, treatment, and seriousness (a combination of course and consequences). In hierarchical multiple-regression analyses, these dimensions significantly improved the prediction of diet level and marginally improved the prediction of exercise after accounting for the effects of age and insulin taking. The results are discussed in terms of variations in personal models across different patient groups and diseases and the role of personal models in determining self-care behaviors.

Adaptation, Psychological↗
PubMed1990

Pharmacological profile of duodenal alkaline secretion.

Stimulation of mucosal alkaline secretion represents an opportunity for discovering novel drugs of potential benefit in maintenance therapy of duodenal ulcer disease. We screened over 200 agents representing the full spectrum of pharmacological categories in order to characterize stimulatory pathways and identify mechanistic leads. A variety of eicosanoids, phospho-diesterase inhibitors and adrenoreceptor agonists together with forskolin, 6-hydroxy-dopamine, 2-chloroadenosine, diazepam, testosterone, dipyridamole and dihydropyridazinone caused a reproducible increase in the metabolism-dependent component of alkaline secretion in bullfrog proximal duodenum. PGE2 (ED50 0.02 microgram/ml) was the most potent agent in vitro and was also the most effective stimulant of duodenal alkalinization in vivo in an anaesthetized cat preparation. Agents without effect on spontaneous alkaline secretion by amphibian duodenum included agonists and antagonists of histamine, 5-hydroxy-tryptamine, gamma-aminobutyric acid, dopamine, muscarinic and nicotinic receptors, inhibitors of amine uptake, monoamine oxidase and cholinesterase, plus various corticoids, diuretics, oestrogens, chemotherapeutic (anticancer) and antimicrobial agents. The major mechanism of stimulating alkaline secretion in the isolated duodenum is by increasing intracellular cyclic AMP levels. This may occur by either inhibiting metabolism of the nucleotide or by stimulating its formation. Additionally, many stimulants appear to act indirectly via liberation of endogenous prostaglandins as judged from the marked attenuation of responses in the presence of indomethacin to all agonists apart from exogenous PGE2, forskolin, ICI 63197 (PDE inhibitor), 2-chloroadenosine and diazepam. Whether purinergic agonists and benzodiazepines act directly on the enterocyte or by releasing other paracrine mediators is unknown.

Alkalies↗
PubMed1990

Identification of agonists of duodenal alkaline secretion.

This report describes approaches for accurate determination of the comparative activities of stimulants of duodenal alkaline secretion. We screened about 200 standard pharmacological agents using a bullfrog-isolated mucosal preparation in order to characterize fully the mechanisms of duodenal alkaline secretion. A variety of eicosanoids, phosphodiesterase (PDE) inhibitors, adrenoreceptor agonists and benzodiazepines, together with forskolin, 6-hydroxydopamine, 2-chloroadenosine, dipyridamole, dihydropyridazinone and testosterone, caused a reproducible increase in the metabolism-dependent component of duodenal alkaline secretion. Prostaglandin E2 (ED50 of 0.02 micrograms ml-1 in vitro) was the most potent and efficacious stimulant in the isolated mucosa and in the perfused cat duodenum in vivo. In the isolated duodenum, the predominant mechanism for stimulating alkaline secretion appears to be via elevation of intracellular cAMP levels, but in vivo indirect effects, for example on mucosal blood flow, may determine the overall influence of agents on duodenal alkalinization.

Acid-Base Equilibrium↗
PubMed1990

Absence of a gastrin inhibitory factor in the IgG fraction of serum from patients with pernicious anaemia.

Patients with Addisonian pernicious anaemia are alleged to generate antibodies directed against the gastrin receptor. We purified IgG from 15 patients with pernicious anaemia and 15 healthy controls in an effort to show attenuation of gastrin specific binding in vitro and inhibition of gastrin stimulated acid secretion in vivo. Binding of the IgG fraction was determined in a radioreceptor assay utilising the rat pancreatic carcinoma cell line AR42J which expresses high affinity gastrin binding sites (Kd = 5 x 10(-10)). In comparison with control serum, there was no significant displacement (p = 0.10) of human gastrin-17 binding by pernicious anemia samples at either 0.3 mg protein/ml (control (mean (SEM)) 1489 (131) cpm; patients 1858 (174) cpm) or 3 mg protein/ml (control 1930 (110); patients 2195 (107) cpm). The effect of intravenous and intragastric IgG on acid secretion in the anaesthetised rat was determined over a 60 minute period after stimulation with 1 microgram/kg human gastrin-17. A bolus injection of IgG (60-200 mg/kg) had no significant effect (p = 0.50) on gastrin stimulated acid output (29.21 (1.28) mumol H+/h) compared with control (27.48 (4.70) mumol H+/h). Similarly, instillation of 800 mg/kg IgG directly into the stomach for 90 minutes also failed to influence gastrin stimulated acid output (29.69 (3.22) mumol H+/h). Thus, we have been unable to confirm previous reports of an IgG from patients with pernicious anaemia capable of blocking gastrin receptor binding or gastrin stimulated acid secretion.

Adult↗
PubMed1987

Disjunctive models of Boolean category learning.

Four connectionistic/neural models which are capable of learning arbitrary Boolean functions are presented. Three are probably convergent, but of differing generalization power. The fourth is not necessarily convergent, but its empirical behavior is quite good. The time and space characteristics of the four models are compared over a diverse range of functions and testing conditions. These include the ability to learn specific instances, to effectively generalize, and to deal with irrelevant or redundant information. Trade-offs between time and space are demonstrated by the various approaches.

Brain↗
PubMed1987

Learning and using specific instances.

A biologically plausible method for rapidly learning specific instances is described. It is contrasted with a formal model of classical conditioning (Rescorla-Wagner learning/perception training), which is shown to be relatively good for learning generalizations, but correspondingly poor for learning specific instances. A number of behaviorally relevant applications of specific instance learning are considered. For category learning, various combinations of specific instance learning and generalization are described and analyzed. Two general approaches are considered: the simple inclusion of Specific Instance Detectors (SIDs) as additional features during perception training, and specialized treatment in which SID-based categorization takes precedence over generalization-based categorization. Using the first approach, analysis and empirical results demonstrate a potential problem in representing feature presence and absence in a symmetric fashion when the frequencies of feature presence and absence are very different. However, it is shown that by using the proper representation, the addition of SIDs can only improve the convergence rate of perceptron training, the greatest improvement being achieved when SIDs are preferentially allocated for peripheral positive and negative instances. Some further improvement is possible if SIDs are treated in a specialized manner.

Animals↗
PubMed1986

Linear function neurons: structure and training.

Three different representations for a thresholded linear equation are developed. For binary input they are shown to be representationally equivalent though their training characteristics differ. A training algorithm for linear equations is discussed. The similarities between its simplest mathematical representation (perceptron training), a formal model of animal learning (Rescorla-Wagner learning), and one mechanism of neural learning (Aplysia gill withdrawal) are pointed out. For d input features, perceptron training is shown to have a lower bound of 2d and an upper bound of dd adjusts. It is possible that the true upper bound is 4d, though this has not been proved. Average performance is shown to have a lower bound of 1.4d. Learning time is shown to increase linearly with the number of irrelevant or replicated features. The (X of N) function (a subset of linearly separable functions containing OR and AND) is shown to be learnable in d3 time. A method of utilizing conditional probability to accelerate learning is proposed. This reduces the observed growth rate from 4d to the theoretical minimum (for unmodified version) of 2d. A different version reduces the growth rate to about 1.7d. The linear effect of irrelevant features can also be eliminated. Whether such an approach can be made probably convergent is not known.

Animals↗
PubMed1986

Connectionistic models of Boolean category representation.

Several distinct connectionistic/neural representations capable of computing arbitrary Boolean functions are described and discussed in terms of possible tradeoffs between time, space, and expressive clarity. It is suggested that the ability of a threshold logic unit (TLU) to represent prototypical groupings has significant advantages for representing real world categories. Upper and lower bounds on the number of nodes needed for Boolean completeness are demonstrated. The necessary number of nodes is shown to increase exponentially with the number of input features, the exact rate of increase depending on the representation scheme. In addition, in non-recurrent networks, connection weights are shown to increase exponentially with a linear reduction in the number of nodes below approximately 2d. This result suggests that optimum memory efficiency may require unacceptable learning time. Finally, two possible extensions to deal with non-Boolean values are considered.

Artificial Intelligence↗
PubMed1985

Endogenous E-type prostaglandins in regulation of basal alkaline secretion by amphibian duodenum in vitro.

Segments of proximal duodenum from Rana catesbeiana, stripped of external muscle and mounted as a tube in a glass chamber, alkalinized the luminal-side bathing solution at a rate of 1.70 +/- 0.16 microEq/cm . h (n = 18, gross surface area approximately 1.5 cm2/cm). A single change of the serosal-side bathing solution for fresh solution reduced the rate of titratable alkaline secretion, which achieved a new steady state after 45 min amounting to 66% +/- 2% of the initial rate; transmucosal potential difference (lumen negative) fell from 10.6 +/- 1.2 to 8.8 +/- 1.1 mV. Concentrations of E-type prostaglandins in the serosal-side solution measured by radioimmunoassay were 8.5 nM (3 ng/ml) before, 0.17 nM 5 min after, and 1.7 nM 90 min after the solution change (n = 8). Reapplication of the original bathing solution 90 min after the initial change reestablished original secretory rate and potential difference. The increases in alkaline secretion and potential difference were comparable in magnitude and profile to those induced by serosal administration of 10 nM prostaglandin E2. Addition of the metabolic inhibitor 2,4-dinitrophenol (100 microM, serosal side) reduced basal alkaline secretion to 30% +/- 7% of the initial rate and abolished the potential difference (n = 8). These data demonstrate that endogenous prostaglandin E production by an isolated preparation of amphibian duodenum accounts for a proportion of alkaline secretion that is equivalent to 50% of metabolism-dependent basal secretion.

2,4-Dinitrophenol↗
PubMedDate not supplied

Participation in outpatient diabetes education programs: how many patients take part and how representative are they?

Little research has been conducted on the role of participation in programs that teach diabetes self-management skills. This paper reviews recent studies on diabetes educational programs to determine what is known about participation, and then reports our experience in recruiting patients for a program that teaches diabetes self-care skills to persons age 60 and older. Few studies have reported data on participation rates in such programs, and only one study provided information on characteristics of patients who participated versus those who did not. In our study, patients over age 70, and those with whom we initiated contact by means of a letter from their health care provider, were less likely to participate than were younger patients and those who initiated contact with us. It is recommended that future research include information on the percentage and representativeness of patients who participate in diabetes education programs. Studies should also describe their target population, procedures used to recruit participants, and program characteristics that might affect participation.

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