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Biomedical subjects

L A Thompson

Publications and source records attributed to L A Thompson.

At least 19 recordsLinked to original sources
PubMed1992

Involvement of the nigrotectal and nigrothalamic pathways in kappa opioid-induced circling.

The relationship between kappa opioid-induced movement and output stations of the substantia nigra pars reticulata (SNpr) was examined using the rodent circling model. Contralateral rotation produced by intranigral microinjection of the kappa opiate U50,488 was lower in animals with ibotenic acid lesions of either the ipsilateral ventromedial thalamus or superior colliculus than in control animals without lesions. These results suggest that endogenous kappa opioids in the SNpr may influence movement through actions on the nigrothalamic and nigrotectal pathways. In contrast, animals with ipsilateral lesions of the striatum showed an increase in circling relative to controls, possibly due to kappa receptor supersensitivity in the SNpr.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1992

Comparison of glutamine synthetases from brains of genetically epilepsy prone and genetically epilepsy resistant rats.

Since glutamine synthetase (GS) has been proposed as the primary enzyme in the regulation of glutamate metabolism in the central nervous system and since inhibition of the activity of this enzyme in vivo leads to seizures, it has been proposed that an abnormality in the structure or function of this enzyme could be responsible for the induction of seizures in epilepsy prone rats. To test this hypothesis the glutamine synthetases were purified from the brains of both genetically epilepsy prone rats (GEPR) and their progenitors, genetically epilepsy resistant rats (GERR). The enzymes were compared using both SDS-PAGE and isoelectric focusing. The immunoreactivities of equal amounts of protein were determined using the ELISA technique, and the regulation of the glutamine synthetase activities by Mn2+/Mg2+ ratios were compared. The only difference found between the glutamine synthetases from the two strains was a slightly lower specific activity of the enzyme from the epilepsy prone animals.

Animals↗
PubMed1992

A study of developmental speech and language disorders in twins.

Fifty-seven same-sex twin sets (32 monozygotic and 25 dizygotic) were examined for concordance of speech and language disorders. Results showed monozygotic twins to have higher concordance than dizygotic twins. In addition, monozygotic twins were more similar in the types of disorders they presented than dizygotic twins. Positive family histories for speech, language, and learning disorders were reported in the nuclear families of the twins.

Child↗
PubMed1992

The leukocytic reaction of the human uterine cervix.

PROBLEM: Sperm interaction with the immune system of the human cervix is poorly understood. METHOD: The leukocytic response of the human cervix to sperm was examined in a closely monitored patient population (N = 10), using monoclonal antibody cell identification techniques. Baseline data were collected from both cervical mucus and smears sampled before treatment by donor insemination. Donor insemination was timed to coincide with ovulation by monitoring plasma LH concentrations twice daily. Following insemination the numbers of leukocytes were recorded in cervical mucus and smear samples taken over a 24-h period relative to the time of treatment. Controls treated with "pure sperm," seminal plasma, cryopreservative, and cervical smearing alone were also included in the study. RESULTS: Only those women treated with sperm cells exhibited substantial elevations in leukocyte numbers following inseminations. Additionally, serial cervical smearing induced an inflammatory response of the cervix. In all the women, the neutrophil was the predominant leukocyte of the cervix both during the baseline and treatment periods (median values ranged from 77 to 86%). Macrophages, T-helper lymphocytes, and T-suppressor lymphocytes were also detected, but only in low numbers (2-10.6%). Two patients and one control ("pure sperm") became pregnant during their study cycle. CONCLUSIONS: We conclude that the leukocytic reaction is a physiological response of the cervix to sperm, the function of which remains to be established.

Cell Movement↗
PubMed1991

Evidence for intrinsic expression of enkephalin-like immunoreactivity and opioid binding sites in cat superior colliculus.

We have investigated the cellular localization of opioid peptides and binding sites in the cat's superior colliculus by testing the effects of retinal deafferentation and intracollicular excitotoxin lesions on patterns of enkephalin-like immunostaining and opiate receptor ligand binding. In normal cats, enkephalin-like immunoreactivity marks a thin tier in the most dorsal stratum griseum superficiale, small neurons of the stratum griseum superficiale, and patches of fibers in the intermediate and deeper gray layers. Eliminating crossed retinotectal afferents by contralateral eye enucleation had little immediate effect on this pattern, although chronic eye enucleation from birth did reduce immunoreactivity in the superficial layers. By contrast, fiber-sparing destruction of collicular neurons by the excitotoxins N-methyl-D-aspartate and ibotenic acid virtually eliminated enkephalin-like immunoreactivity in the neuropil of the upper stratum griseum superficiale, presumably by killing enkephalinergic cells of the superficial layers. Such lesions did not eliminate the patches of enkephalin-like immunoreactivity in the deeper layers. In normal cats, opiate receptor ligand binding is dense in the stratum griseum superficiale, particularly in its upper tier, and moderately dense in the intermediate gray layer. Contralateral eye removal had no detectable effect on the binding pattern, but excitotoxin lesions of the colliculus dramatically reduced binding in both superficial and deep layers. Some ligand binding, including part of that in the upper stratum griseum superficiale, apparently survived such lesions. Similar effects were observed in the lateral geniculate nucleus: enucleation produced no change in binding, whereas excitotoxin lesions greatly reduced specific opiate binding. We conclude that in the superficial collicular layers, both enkephalin-like opioid peptides and their membrane receptors are largely expressed by neurons of intrinsic collicular origin. The close correspondence between the location of these intrinsic opioid elements and the tier of retinal afferents terminating in the upper stratum griseum superficiale further suggests that opiatergic interneurons may modulate retinotectal transmission postsynaptically.

Animals↗
PubMed1991

Adult age effects of plausibility on memory: the role of time constraints during encoding.

We investigated the role of training-induced knowledge schemas and encoding time on adult age differences in recall. High-plausible (schema coherent) words were recalled better than low-plausible (schema discrepant) words in both age groups. This difference was larger for old adults than for young adults for presentation times ranging from 3 s to 11 s per word. After equating participants in overall recall (i.e., at 50% correct) by dynamic adjustment of presentation time, old adults again showed a stronger plausibility effect than young adults when recall was above criterion. In a second experiment with self-paced encoding, old adults used more time than young adults only for low-plausible pairs, yet they still remembered fewer of them. In a third experiment, both age groups preferred to imagine high- rather than low-plausible words, but this effect was more pronounced in old adults. The results indicate that, compared with young adults, old adults find it particularly difficult to form elaborative mental images of schema-discrepant information under a wide variety of time constraints during encoding. Results are discussed in relation to explanations based on age-related mental slowing.

Adult↗
PubMed1991

Positive immunoselection--a method of isolating leukocytes from leukocytic reacted human cervical mucus samples.

In this brief communication we report a simple and accurate method of isolating and quantifying specific leukocytes from midcycle human cervical mucus, using monoclonal antibody-coated magnetic beads. Cervical mucus samples (pre- and postinsemination) were broken down enzymatically and incubated with a series of these beads. This method of positive immunoselection consistently retrieved representative levels of leukocytes (means = 73.8% +/- 1.59%; mean leukocyte retrieval rate +/- S.E.) from the cervical mucus samples. Significantly more leukocytes (P less than 0.0001) were isolated from the postinsemination samples, the predominant leukocyte of which was the neutrophil, which comprised 83% of the leukocyte population. These results reaffirm that a leukocytic influx is initiated across the human uterine cervix following the introduction of semen samples, the function of which is possibly phagocytic clearance of the nonfertilizing population of sperm.

Antibodies, Monoclonal↗
PubMed1991

Longitudinal prediction of specific cognitive abilities from infant novelty preference.

A test of visual novelty preference, the Fagan Test of Infant Intelligence, was administered to a group of 113 full-term infants from the Colorado Adoption Project at 5 and 7 months of age. The infants were followed longitudinally and the Bayley scales were administered at 12 and 24 months, the Sequenced Inventory of Communication Development at 24 and 36 months, and the Stanford-Binet and the Colorado Specific Cognitive Abilities Test at 36 months. 1 novelty preference score was obtained for each infant by averaging across the 2 test ages. Novelty preference correlated significantly with 36-month Binet IQ, the first unrotated principle component from the cognitive battery, and the 24-month Bayley MDI score. Novelty preference was also compared to specific abilities at all 3 follow-up ages; all of the specific abilities were significantly related to novelty preference, with the exceptions of 12- and 24-month Imitation and 36-month Perceptual Speed. Partial correlations suggest that novelty preference predicts language and memory independent of IQ. Overall, the results indicate that novelty preference during the first year of life not only predicts later IQ but may also reflect specific cognitive processes.

Attention↗
PubMed1991

Critical nursing behaviors in care for the dying.

A beginning list of seven critical nursing behaviors in care for the dying was identified in a qualitative study. Ten experienced palliative care nurses and 10 nurse educators were asked to describe situations in which a student or graduate nurse had displayed very positive or very negative attitudes to care for the dying. Behaviors identified after content analysis of transcribed interviews were responding during death scene, providing comfort, responding to anger, enhancing personal growth, responding to colleagues, enhancing quality of life during dying, and responding to the family. Three of these behaviors were not well described in the nursing literature.

Attitude to Death↗
PubMed1990

Inhibitory effects of the kappa opiate U50,488 in the substantia nigra pars reticulata.

The effect of the selective kappa opiate agonist U50,488 on the firing rate of neurons of the substantia nigra pars reticulata (SNR) was investigated in a series of extracellular single unit recording experiments in rats. Intravenous administration of U50,488 produced a dose-related decrease in the spontaneous firing rate of SNR neurons, an effect that was reversed by naloxone in most cases. Iontophoretic application of the kappa agonist also inhibited the firing of SNR neurons, indicating a direct action of U50,488 in the SNR. U50,488 was particularly effective in inhibiting a local group of SNR neurons that exhibit increased firing in response to mechanical pressure. In separate experiments, it was determined that these pressure sensitive neurons (1) include nigrotectal and nigrothalamic cells, (2) are responsive to mild as well as painful levels of pressure, and (3) are not responsive to light flashes. This group of neurons may be a primary target of naturally occurring kappa selective opioids of the prodynorphinergic striatonigral pathway.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1990

Differences in heritability across groups differing in ability.

Differences in heritability and environmentality were assessed for 54 DZ and 86 MZ same-sex twin pairs between 6 and 12 years of age from the Western Reserve Twin Project. A principal-component score composed of the subtests of the WISC-R, PPVT, WRAT, and MAT represented each twin's cognitive ability. Using a modification of a regression technique developed by DeFries and Fulker (1985), it was possible to assess differential heritability and environmentality across ability level. A number of variants of this procedure were used and all yielded the same result: lower ability subjects show higher heritabilities and lower shared environmentality. This result is attributable to larger differences between DZ twins at low ability levels and to differences between MZ twins, which are either the same across ability level or are smaller at low ability levels. A possible explanation for this effect is a genotype-environment correlation in which higher-ability persons seek out better environments. The results from this study should be regarded as tentative but the methods used can be applied to other twins studies. Investigators should be aware of the importance of representing the low end of the distribution in their samples.

Achievement↗
PubMed1989

Before you see it, you see its parts: evidence for feature encoding and integration in preschool children and adults.

Preschool children and adults were compared in two experiments examining the basic issue of whether perceptual representations of objects are built-up from independent features along the dimensions of size and brightness. Experiment 1 was a visual search experiment. Subjects searched for targets which differed from distractors either by a single feature or by a conjunction of features. Results from preschoolers were comparable to those from adults, and were consistent with Treisman and Gelade's (1980, Cognitive Psychology, 12, 97-136) feature-integration theory of attention. Their theory states that independent features are encoded in parallel and are later combined with a spatial attention mechanism. However, children's significantly steeper conjunctive search slope indicated a slower speed of feature integration. In Experiment 2, four mathematical models of pattern recognition were tested against classification task data. The findings from both age groups were again consistent with a model assuming that size and brightness features are initially registered, and then integrated. Moreover, the data from Experiment 2 imply that perceptual growth entails small changes in the discriminability of featural representations; however, both experiments show that the operations performed on these representations are the same developmentally.

Adult↗
PubMed1988

Distribution of opiate receptors within visual structures of the cat brain.

The distributions of mu, delta, and kappa opiate receptors within visual regions in the cat cortex, thalamus and midbrain were determined by in vitro autoradiography. The overall distribution of receptors was examined using [3H]-etorphine, a ligand that nonselectively labels all types of opiate receptors. [3H]-[D-Ala2, N-Me-Phe4,Gly(ol)5]-enkephalin (DAGO) was used to selectively label mu receptors, [3H]-[D-Pen2, 5]-enkephalin (DPDPE) for delta receptors, and [3H]-bremazocine for kappa receptors. Each of the areas examined showed clear opiate receptor binding with [3H]-etorphine and a differential distribution of mu, delta, and kappa receptors. Compared to other cortical regions, opiate binding in layers 3 and 4 of areas 17 and 18 was sparse. In the adjacent areas a more uniform distribution across layers was observed. The density of kappa opiate receptors was greater in cortex than in subcortical structures, whereas the reverse was the case for mu receptors. Nevertheless, all three types of opiate receptors were found in the ventral and dorsal subdivisions of the lateral geniculate (LGN), the pulvinar complex, and the suprageniculate nucleus. In the midbrain, the superficial layers of the superior colliculus were heavily labelled with the mu receptor ligand, and modestly with the kappa ligand. Compared with other midbrain and diencephalic areas, delta binding was low in the superior colliculus. These results suggest that the diverse effects of opiates on visual perception are mediated by the unique distributions of opiate receptor types throughout the visual areas in the brain.

Animals↗
PubMed1987

Opposite effects of mu and kappa opiates on the firing-rate of dopamine cells in the substantia nigra of the rat.

Single unit extracellular recording was carried out in rats to compare the actions of a mu receptor agonist (morphine) to a kappa receptor agonist (U50,488) in the substantia nigra pars compacta (SNC). Intravenously administered morphine and U50,488 exhibited opposite effects: morphine excited SNC dopamine cells, and U50,488 inhibited them. Both effects were blocked by naloxone, although significantly more naloxone was necessary to block the effect of the kappa agonist. Local administration of U50,488 in the caudate also inhibited the firing of SNC dopamine cells. These results are discussed in terms of the natural functions of the prodynorphinergic straiatonigral projection.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1986

Evaluation and integration of speech and pointing gestures during referential understanding.

Two experiments investigated the relative influence of speech and pointing gesture information in the interpretation of referential acts. Children averaging 3 and 5 years of age and adults viewed a videotape containing the independent manipulation of speech and gestural forms of reference. A man instructed the subjects to choose a ball or a doll by vocally labeling the referent and/or pointing to it. A synthetic speech continuum between two alternatives was crossed with the pointing gesture in a factorial design. Based on research in other domains, it was predicted that all age groups would utilize gestural information, although both speech and gestures were predicted to influence children less than adults. The main effects and interactions of speech and gesture in combination with quantitative models of performance showed the following similarities in information processing between preschoolers and adults: (1) referential evaluation of gestures occurs independently of the evaluation of linguistic reference; (2) speech and gesture are continuous, rather than discrete, sources of information; (3) 5-year-olds and adults combine the two types of information in such a way that the least ambiguous source has the most impact on the judgment. Greater discriminability of both speech and gesture information for adults compared to preschoolers indicated small quantitative progressions with development in the ability to extract and utilize referential signals.

Adult↗