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Biomedical subjects

S T Elder

Publications and source records attributed to S T Elder.

At least 19 recordsLinked to original sources
PubMed1993

18F-labeled benzamides for studying the dopamine D2 receptor with positron emission tomography.

Two series of (N-benzylpiperidin-4-yl)- and (9-azabicyclo[3.3.1]nonan- 3 beta-yl)benzamides were prepared, and in vitro binding assays were used to measure the affinity of these compounds for dopamine D2, dopamine D3, serotonin 5-HT2, and alpha 2-adrenergic receptors. The results of these studies indicated compounds 23, 26b, and 34 have the selectivity needed for in vivo studies of the D2 (and possibly D3) receptors. 18F-Labeled analogues of 23, 26b and 34 were prepared by N-alkylation of the corresponding desbenzyl precursors with [18F]-4-fluorobenzyl iodide. Preliminary in vivo studies demonstrated that [18F]-23 and [18F]-26b are suitable candidates for further evaluation in positron emission tomography imaging studies. The slow rate of washout of [18F]-34 from nondopaminergic regions and its comparatively high lipophilicity indicates that this compound may not be suitable for imaging studies because of a high level of nonspecific binding.

Animals↗
PubMed1993

The use of [18F]4-fluorobenzyl iodide (FBI) in PET radiotracer synthesis: model alkylation studies and its application in the design of dopamine D1 and D2 receptor-based imaging agents.

[18F]4-Fluorobenzyl iodide ([18F]FBI) was prepared, and a series of model alkylation studies were conducted to determine its chemical reactivity toward nitrogen and sulfur nucleophiles of varying nucleophilicities. [18F]FBI was found to react rapidly with secondary amines and anilines to give the corresponding N-[18F]4-fluorobenzyl analogue in high yield. Amides and thiol groups required the use of a base catalyst. The utility of [18F]FBI was documented by investigation of dopamine D1 and D2 receptor-based radiotracers.

Alkylation↗
PubMed1990

Conditioned diastolic blood pressure: the effects of magnitude of acquired response and feedback schedules on resistance to extinction.

The purpose of this experiment was to examine the effects of: (a) training to two different response magnitude criteria, and (b) three different feedback schedules on the acquisition and subsequent extinction of diastolic blood pressure changes. Subjects were 20 male and female normotensive volunteer college students, ages 18-36 years. A 3 x 2 design was used in which 3 schedules of reinforcement (0, 50 and 100%) were factorially compared with two response magnitude training criteria (10% and 20% of resting basal diastolic blood pressure). The results indicated that while the partial reinforcement effect appears to hold for the acquisition of bidirectional diastolic blood pressure changes, different response magnitude training criteria seemed to have a greater influence in producing significant differences in acquisition rate during the training of diastolic blood pressure decreases. Resistance to extinction was notably weak across all conditions, with most subjects failing to exhibit previously acquired bidirectional diastolic blood pressure performance after the end of the first extinction session.

Adolescent↗
PubMed1989

Cigarette smoking, alcohol, and oral contraceptive use by type A adolescent--the Bogalusa Heart Study.

Type A behavior pattern (TABP) is an independent risk factor for cardiovascular (CV) disease and is characterized by hostile, aggressive, competitive behavior. TABP characteristics and CV risk factors have been found in children and adolescents. TABP has been correlated with adult alcohol consumption, but studies associating Type A and smoking are mixed. The purpose of this study is to investigate the smoking, alcohol use, and oral contraceptive use of Type A children and adolescents. The Hunter-Wolf Type A scale and a health habits questionnaire were evaluated for 2092 children, ages 8-17 years, within the context of a comprehensive biracial epidemiological CV screening in Bogalusa, Louisiana. Global Type A and factor components were evaluated: hostility, eagergy, desire for control, drive, and competitiveness. Correlation coefficients reflected the strongest associations between hostility and smoking and between hostility and drinking for white males. The age at menarche appeared to be correlated with the drive component.

Adolescent↗
PubMed1987

Recent improvements in the UNO BP monitor/conditioner.

A number of modifications and improvements have been made in the UNO system for monitoring and conditioning blood pressure, which have increased its accuracy and versatility. The purpose of this report, therefore, is to enumerate and describe the major changes in the present generation of the system.

Blood Pressure Determination↗
PubMed1987

A comparison of two methods of training resistance to visually-induced motion sickness.

This report concerns the use of two methods of training subjects to tolerate visually-induced motion sickness (VMS). Sixteen subjects were selected on the basis of their response to a motion sickness history questionnaire and assigned to one of four groups on the basis of their ability to tolerate visually-induced motion (VM). One group received 10 sessions of confidence building and desensitization training (BT); a second group received 10 sessions of EMG and temperature biofeedback (FB); a third group received 10 sessions of BT and 10 sessions of FB (BTFB); and a fourth group received no treatment (C). The results indicated that the BT and BTFB groups exhibited significant increases in tolerance to VM when pretreatment measures were compared to posttreatment measures, while no significant differences in pre-post measures were observed in the FB or C groups. A similar pattern emerged from the symptomatology data.

Behavior Therapy↗
PubMed1984

The menstrual cycle from a bio-behavioral approach: a comparison of oral contraceptive and non-contraceptive users.

The purpose of the present study was to clarify the effects of the menstrual cycle on: (1) accuracy and simple reaction time in a problem-solving situation; (2) academic performance; (3) identify corresponding cyclic changes in a set of psychophysiological measures during rest/test conditions; and (4) to compare oral contraceptive with non-oral contraceptive users. Eight volunteer females, 4 normally cyclic and 4 oral contraceptive users, reported once weekly throughout two menstrual cycles during which changes in blood pressure, heart rate, skin temperature, finger pulse amplitude, and verbal reaction time were monitored. Differences in verbal reaction time were found between oral contraceptive users and non-users over phases of the cycle, the users being significantly slower during menstrual and premenstrual phases. It was also observed that all subjects reacted slower in the menstrual and ovulatory phases during cycle one, although no differences were found during cycle two. Skin temperature changes between groups occurred during the postovulatory phase of cycle two, the control group having shown a much greater increase than oral contraceptive users. These results indicated a suppressive influence of oral contraceptives which appeared to affect cognitive rather than motor responses, and that these effects were residual when no pills were taken menstrually and premenstrually. Also indicated was the finding that although a 28-day cycle of menstrual events exists, periodicity of these events may be reflected in a much larger cycle non-currently defined.

Achievement↗
PubMed1983

Multimodal biofeedback in the treatment of migraine.

The purpose of this study was twofold: (a) to compare the effects of three behavioral strategies for the relief of migraine, and (b) to examine different combinations of the treatments to assess the effectiveness of multimodal biofeedback with this problem. Twenty-four volunteer migraine sufferers not on medication, and with at least weekly occurrence of headaches, participated in the study. Results indicated that (a) subjects who learned temporal cooling, frontalis relaxation, and progressive muscular relaxation exhibited the best success with headache relief; (b) control subjects, who did not show the same psychophysiological changes as experimental subjects, reported no headache relief; and (c) subjects in the group with only relaxation exercises performed similarly to control subjects and reported no headache relief.

Biofeedback, Psychology↗
PubMed1982

A factorial comparison of schedule and bilateral locus of diastolic blood pressure-contingent feedback.

The purpose of this study was twofold: (a) to compare and determine the effects of a partial and a continuous schedule of feedback on the acquisition and subsequent extinction of bidirectional diastolic blood pressure changes in human subjects; and (b) to examine the result of the administration of response-contingent feedback at specific sites on the bilateral axis between left and right arms on diastolic blood pressure changes at those sites. Subjects were 36 normotensive volunteer college students, ages 18-40 years. A 3 X 3 design was used in which three schedules of feedback (0, 25, and 50%) were factorially compared with three sites of feedback (left arm, both arms, and right arm). The results indicated that varying schedules of feedback differentially affected the acquisition and extinction of diastolic blood pressure response changes. The data also suggested that diastolic blood pressure changes could be produced at specific sites on the bilateral axis, although not completely independent of changes at other sites. Extinction was observed to be rapid in most cases, although a number of subjects with partial feedback schedules showed a somewhat greater resistance to extinction.

Adult↗
PubMed1979

Conditioned diastolic blood pressure.

Four groups of normotensive subjects were used in an experiment designed to: (a) replicate earlier data, (b) determine whether heart rate and respiration rate changes accompanied the development of acquired bi-directional diastolic blood pressure responses, and (c) investigate whether males and females acquired diastolic blood pressure responses at differential rates. Observations were carried out over one baseline and eight consecutive one-hour training sessions. Analyses of the blood pressure scores revealed subjects were able to acquire a bi-directional response, thereby confirming earlier reports. From subsequent analysis of the heart rate and respiration rate scores and from intercorrelations between diastolic blood pressure, heart rate, and respiration rate, no consistent relationships or patterns emerged. Comparisons of male and female blood pressure performance failed to yield evidence of reliable sex differences.

Adolescent↗
PubMed1979

Absence of ocular pathology after repeated exposure of unanesthetized monkeys to 9.3-GHz microwaves.

Unfettered monkeys (Macaca mulatta) have been trained to expose the face and eyes to pulsed microwave radiation at a frequency of 9.31 GHz and an average power density of 150 mW/cm2. Performance of an operant response required the monkeys to maintain the head within the field of the radiation source. Twelve monkeys were individually irradiated during 30 to 40 sessions and then were observed for a period of one year. No deleterious effects such as cataracts have been observed.

Animals↗
PubMed1977

The effects of caffeine on reaction time in hyperkinetic and normal children.

Using a double-blind design, the authors investigated 1) caffeine's effect in hyperkinetic children on a choice reaction time task, 2) whether caffeine has different effects on simple reaction time and choice reaction time, and 3) whether its effects in the hyperkinetic compared with the normal group of children are best described by the law of initial values or as a "paradoxical effect." The results indicate that caffeine produced an increase in the accuracy of stimulus identification and processing and a decrease in lapses of attention for the hyperkinetic group. The law of initial values best represented the phenomena observed.

Attention↗