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Biomedical subjects

D Elliott

Publications and source records attributed to D Elliott.

At least 145 records · Page 8Linked to original sources
PubMed1988

Manual localization of lateralized visual targets.

The effects of visual field, responding limb and extrapersonal space on the ability to localize visual targets using slow positioning movements of the arm were examined. Special contact lenses were used to lateralize visual information and to make comparisons with localization under monocular control conditions. Subjects made slow positioning movements to place a cursor directly beneath target lights. They saw target lights but not the moving limb during the trial. For directional error, results indicated that subjects were more accurate localizing targets lateralized to the right hemisphere than targets lateralized to the left hemisphere, indicating right hemisphere superiority for localization of visual targets in grasping space. Localization performance was significantly better with the right hand than the left hand. the left hand demonstrated a directional bias to the right of the targets. Responding hand and visual field did not interact. Finally, contrary to subjects' awareness and verbal reports, target localization was not less accurate in lens than in monocular control conditions. This was true for both amplitude and directional error. This is consistent with other studies where visual information about limb position is not available.

Journal Article↗
PubMed1988

14 beta-Hydroxyprogesterone binds to the digitalis receptor, inhibits the sodium pump and enhances cardiac contractility.

1. Certain derivatives of progesterone are potent inhibitors of high affinity, specific binding of 3H-cardiac glycosides. The steroids interact at the cardiac glycoside site on Na,K-ATPase and inhibit the enzyme (the sodium pump) in cardiac and other tissues. However, the active congeners identified previously have been, unlike the cardiac glycosides, predominantly cardiodepressant. 2. Because a 14 beta-hydroxy substituent is an important determinant of activity of the cardiotonic cardiac glycosides, we synthesized 14 beta-hydroxyprogesterone. This derivative has about one-tenth the potency of the aglycone, ouabagenin, in a [3H]-ouabain binding assay. 3. Like ouabagenin, but in contrast to the cardiodepressant congeners of progesterone, 14 beta-hydroxyprogesterone consistently elicited positive inotropy in isolated cardiac muscle and enhanced both the magnitude and frequency of fluctuations in scattered light (an index of oscillatory intracellular release of calcium). 4. Thus, at least one hydroxylated derivative (and putative endogenous metabolite) of progesterone, mimics the cardiac effects of cardiac glycosides including enhanced contractility.

Adult↗
PubMed1987

Pedal asymmetry in the reproduction of spatial locations.

Roy and MacKenzie (1978) showed that the left thumb is superior to the right thumb in reproducing a spatial location. This study replicated and extended their findings to the reproduction of spatial locations by the feet. We attribute the left foot advantage in this study to the superiority of the right hemisphere in processing spatial information.

Adult↗
PubMed1987

Progesterone derivatives that bind to the digitalis receptor: synthesis of 14 beta-hydroxyprogesterone. A novel steroid with positive inotropic activity.

The synthesis of 14-hydroxy-14 beta-pregn-4-ene-3,20-dione (14 beta-hydroxyprogesterone) is described. This novel steroid is about 10 times more potent than progesterone and one-tenth as potent as ouabagenin in an [3H]ouabain radioligand binding assay and is the first in a series of progesterone congeners that interact at the cardiac glycoside receptor both to possess the C/D cis ring junction and to enhance contractility of isolated cardiac tissue.

Animals↗
PubMed1987

The influence of walking speed and prior practice on locomotor distance estimation.

In an attempt to reconcile discrepant findings in the literature (Elliott, 1986; Thomson, 1983), walking speed, prior practice, and walking delay were manipulated to determine if they had an impact on locomotor distance estimation. Contrary to suggestions by Thomson (1986), walking variability in the direction of locomotion depended only on a subject' initial distance from the targets.

Journal Article↗
PubMed1987

A psychotherapeutic group for men.

Little has been written on group therapy designed to treat a group of all male patients. A group of male outpatients followed in individual psychotherapy were identified who shared several personality traits and faced similar psychosocial problems. These patients were 20 to 40 years old, unmarried, the majority unemployed and lacking heterosexual relationships. This report examines characteristics of these patients, themes arising during group sessions, aspects of group composition, techniques used in therapy and the outcome of various patients after six months of therapy.

Adult↗
PubMed1987

Visual feature integration in learning disabled children.

This study examined the ability of 7 learning disabled children to detect and integrate visual features in a complex display. While the learning disabled children performed more poorly over-all than 6 control children, differences between the two groups were most pronounced when subjects were required to conjoin or integrate visual features to make a decision about the presence of a target item. This finding is discussed with reference to automatic and attention-demanding components of visual perception.

Attention↗
PubMed1987

Modulation of the murine immune response to human IgG by complexing with monoclonal antibodies. I. Antibody responses to determinants on the constant region of light chains and gamma chains.

Complexing a human IgG lambda paraprotein with a monoclonal antibody (McAb) to a lambda-chain determinant markedly depressed the anti-lambda response of immunized mice. No anti-lambda was found in the serum after two or four injections of the complex, whereas high titres of anti-lambda chain antibody were found in the sera of mice immunized with the IgG paraprotein complexed with any single anti-gamma chain McAb or with a pool of anti-gamma chain McAbs. Responses to the highly immunogenic Fc gamma portion of the molecule were not suppressed by complexing with a single anti-gamma chain McAb and were only slightly suppressed after complexing with a pool of anti-gamma chain McAbs. Some anti-Fc gamma antibody was produced by all animals receiving a single injection of the immunogen complexed to any McAb, but free immunogen did not generate a primary response. Complexing the IgG with an anti-Fc gamma McAb enhanced the response to to the poorly immunogenic C gamma 1 domain but no anti-C-gamma 1 was produced by mice receiving the IgG complexed with an anti-C-gamma 1 McAb. In immunizations with 'free' (Bence-Jones) lambda chain, all the antibody produced was directed against 'free'-specific determinants. Complexing the Bence-Jones protein with McAbs to 'free' or 'general' determinants on the lambda chain did not enhance or suppress the response. It is concluded that the response to weakly or moderately immunogenic, but not to strongly immunogenic, regions of the molecule may be suppressed by complexing the immunogen with a McAb of appropriate specificity. Possible reasons for this result are discussed.

Animals↗
PubMed1987

Cerebral specialization in young adults with Down syndrome.

Adults with and without Down syndrome performed a rapid unimanual finger-tapping task alone and while sound-shadowing high frequency words. For male subjects, the concurrent speech disrupted right-hand, but not left-hand performance. Females suffered finger-tapping decrements in both hands in the dual-task situation. These results provide no evidence for reverse (right hemisphere) lateralization of speech in individuals with Down syndrome.

Adolescent↗
PubMed1987

Cerebral specialization in individuals with Down syndrome.

Recent research in which investigators examined cerebral specialization in individuals with Down syndrome was reviewed. Although dichotic listening studies seem to indicate that individuals with Down syndrome are more likely than those without Down syndrome to display a left ear/right hemisphere advantage for speech sounds, evidence from other experimental paradigms makes a simple model of reversed cerebral specialization for individuals with Down syndrome untenable. We proposed a model of cerebral specialization that has as its main feature the biological dissociation between speech perception and the production of speech and other complex movements. In light of this feature, possible directions for future research were discussed.

Dominance, Cerebral↗
PubMed1987

Modulation of the murine immune response to human IgG by complexing with monoclonal antibodies. II. Antibody responses to idiotopes of the human IgG paraprotein and of the mouse monoclonal antibodies.

Anti-idiotope antibodies produced by mice immunized with a human IgG paraprotein complexed with various mouse monoclonal antibodies (McAbs) have been measured. All animals receiving more than one injection of the paraprotein (free or complexed with a mouse McAb) produced antibodies to the idiotypes of the paraprotein. Complexing with a McAb, especially an anti-Fc-gamma McAb, enhanced the response. Antibodies to the idiotopes of mouse McAbs were more difficult to produce and their production was very dependent on the mode and schedule of the immunization. The best antisera were produced by mice receiving a course of injections of pre-formed complexes of the IgG paraprotein and McAbs. Four of five mice produced antibodies to the idiotopes of an anti-light chain McAb (C4) after a course of immunization (one primary plus four boosts) of an IgG-C4 complex. Two of the six mice receiving a similar course of injections of the paraprotein complexed with an anti-gamma McAb (A55) produced high titres of antibodies to A55 idiotypes. Responses were enhanced when complexes were prepared with a pool of McAbs. It is probable that the formation of large multi-cross-linked complexes containing the McAb under study is important in generating the response. Once a response is initiated, very high titres may be achieved.

Animals↗
PubMed1986

Dual-task interference between speaking and listening and a unipedal force production task.

Twenty-four male right-handed adults performed a force production task with their right and left feet alone, and while sound-shadowing or listening to high frequency words. Overall, subjects performed better with their left foot than their right foot. Further, sound-shadowing, but not listening disrupted right foot performance. The concurrent language tasks had no effect on left foot performance.

Dominance, Cerebral↗
PubMed1986

Continuous visual information may be important after all: a failure to replicate Thomson (1983).

The purpose of the two experiments reported here was to replicate previous research (Thomson, 1983) which suggests that visual information useful in the control of movement persists for up to 8 s after visual occlusion. Contrary to other findings (Thomson, 1980, 1983), little evidence was found for an 8-s visual representation of the environmental layout, indicating there is no substitute for continuous visual information in the control of movement. Methodological and statistical problems with Thomson's work are discussed.

Feedback↗
PubMed1986

Lateral asymmetries in finger-tapping by adolescents and young adults with Down syndrome.

Lateral asymmetries in finger-tapping were compared in right-handed adolescents and young adults with and without Down syndrome in order to examine cerebral specialization in the Down syndrome group. Finger-tapping data revealed that subjects with Down syndrome performed more slowly than did control subjects and failed to show a right-hand tapping advantage. Although the latter finding suggests that individuals with Down syndrome are less lateralized for sequential processing, they exhibited the same pattern of tapping variability as did control subjects; i.e., they were more variable when finger-tapping with their left hands.

Adolescent↗