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C J Clayton

Publications and source records attributed to C J Clayton.

8 recordsLinked to original sources
PubMed1994

Ethanol, monoamines, and affect.

Evidence suggests that ethanol self-administration is directly related to central norepinephrine (NE) activity and inversely related to central serotonin (5-HT) activity. Normal male volunteers participated in a placebo controlled crossover design to assess the effects of 1-tyrosine (TY) and 1-tryptophan (TP) (precursors of catecholamines and 5-HT, respectively) in combination with ethanol, on several neurobehavioral measures. Ethanol by itself produced negative effects on several dimensions of mood. Dysphoria was potentiated by TP in combination with ethanol and either unchanged or attenuated by the combination of TY and ethanol. Ethanol impaired verbal recall, and neither TP nor TY in combination with ethanol altered that impairment. The results are consistent with the hypothesis that 5-HT mediates some of the negative mood effects produced by ethanol or antagonizes some of its positive effects, while NE at least partly mediates ethanol's positive effects on mood. Ethanol's impairment of verbal memory appears to be mediated by mechanisms outside the monoamine systems.

Adult↗
PubMed1991

Behavioral and endocrine interactions between thyrotropin-releasing hormone and ethanol in normal human subjects.

Thyrotropin-releasing hormone (TRH) has been shown to antagonize the depressant effects of ethanol in animals, but conflicting findings have been reported in humans. To test whether TRH counteracts any of a variety of ethanol-sensitive behavioral measures in normal human subjects and for an effect of ethanol on TRH-induced thyrotropin (TSH) and prolactin (PRL) response, we administered TRH (500 micrograms) or placebo over 1 min intravenously, 30 min after subjects had ingested 0.8 g/kg of ethanol or a placebo drink. Blood samples for TSH and PRL were drawn prior to and 15 and 30 min after injection. Eight male subjects were studied in a balanced, crossover design with each subject receiving placebo-placebo, TRH-placebo, placebo-ethanol, and TRH-ethanol. Whereas ethanol had significant and expected effects on subjective measures, memory, disinhibition, reaction time and time perception, TRH failed to counteract any ethanol effect, except for a small effect in one memory task. Similarly, no effect of ethanol on TRH-induced TSH or PRL response was found. Though the behavioral findings could be interpreted to indicate that TRH does not alter ethanol sensitive behaviors in humans it will be necessary to utilize higher dosages of TRH and/or TRH analogues before firmly drawing this conclusion.

Adult↗
PubMed1989

Differential psychopharmacology of methylphenidate and the neuropsychology of childhood hyperactivity.

The principle of rate-dependency has been proposed to explain the therapeutic effects of stimulant drugs in hyperactive children (HAC). This paper is a critical discussion of the salience of rate-dependency to childhood hyperactivity, on mathematical, theoretical and clinical levels. The results of a stimulant drug trial in 55 HAC are presented; the data are analyzed using analysis of variance to describe main drug effects, and these are compared to results derived from a traditional rate dependency analysis. The latter are found to have little salience to the actual clinical effects of stimulant drugs on a wide variety of behavioral, physiological and laboratory measures. The weakness of the rate dependency hypothesis, however, is not necessarily fatal to the idea that the state of the organism prior to drug administration influences the response profile of the drug. The heterogeneity of stimulant effects, and the relationship between stimulant effects and the predrug state of the organism, especially in electrophysiological paradigms, are clear. A hypothesis is presented to suggest that HAC may be characterized by a trait of excessive variability. Homeostatic stimulant effects in reducing response variability may be central to the therapeutic action of the drug. A neural substrate for the abnormal oscillations which characterize HAC, the correction of which is germane to therapeutic stimulant effects, is presented in terms of the regulatory functions of the frontal lobe. A neuroanatomic locus of childhood hyperactivity is proposed in terms of disorder or dysmaturation of frontal striatal systems.

Adolescent↗
PubMed1984

The development of mammotroph adenomas in pituitaries of aging female C57BL/6J mice.

The development of pituitary adenomas in female C57BL/6J mice was studied over the lifespan. Mammotrophs and somatotrophs, identified by immunocytochemical staining, appeared normal in 3-4 month old animals, with the exception of an occasional hypertrophic mammotroph and, in one gland, a nest of such cells. At 15 months, hypertrophic mammotrophs, somatotrophs and unstained cells occurred singly or in areas of hyperplasia; a mammotrophic adenoma was present in one gland. At 22 months, pituitaries contained mammotroph adenomas or adenomalike mammotroph clusters within hypertrophic, hyperplastic areas as seen in 15 month old glands. Pituitaries from all 28-30 month old mice contained mammotroph adenomas; nests of hypertrophic cells were present in 5 of 8 glands studied. These results suggest that mammotrophic adenomas may arise from hypertrophic mammotrophs, which are often found in nests with other hypertrophic pituitary cell types. However, this study does not exclude the possibility that mammotroph adenomas and hypertrophic mammotrophs occur independently.

Adenoma↗
PubMed1981

A comparison of neuropeptide immunocytochemistry in fluid-fixed and freeze-dried brains.

Immunocytochemical staining of luteinizing hormone-releasing hormone (LHRH), somatostatin, and neurophysin was compared in rat brains fixed with 1) formalin, 2) Bouin's solution, 3) freeze-dried (FD), or 4) freeze-dried + paraformaldehyde vapor perfused (FDV). The distribution of LHRH fibers was similar in all preparations; however, beads of granular reaction product often appeared finer and more numerous in the median eminence of FD- and FDV brains. Positively stained LHRH perikarya were not observed in any of the preparations. In contrast, somatostatin-immunoreactive perikarya were present in the fluid-fixed and FD brains, although few were observed in FDV brains. Somatostatin-immunoreactive fibers were present in all preparations, but appeared most numerous in the median eminence of FD brains. Staining of neurophysin-containing perikarya and fibers was similar in all preparations. These observations suggest that the FD brain can provide a suitable tissue substrate for immunocytochemistry, demonstrating staining comparable to or surpassing that of more conventional preparations. However, staining of antigens in FD brain was not uniformly successful and may depend on stereochemical characteristics of each antigen as well as properties of the primary antisera used in the staining procedure.

Animals↗
PubMed1979

Immunocytochemical evidence for anti-LHRH and anti-ACTH activity in the "F" antiserum.

An antiserum which has previously been thought to be specific for LHRH-like immunoreactive material was shown to contain two populations of antibodies, one demonstrating anti-LHRH activity and the other anti-ACTH(1-24) activity. In rat and mouse, ACTH(1-24)-like immunoreactive substance is present in perikarya within the basal hypothalamus and in fibers in arcuate, periventricular and dorsomedial nuclei. LHRH-like immunoreactivity is present in fibers within the median eminence and arcuate nucleus, in a few fibers running along the ventral border of the hypothalamus, and in a small number of cell bodies within the medial basal hypothalamus.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

An intra-oral access device.

Using developments from the science of electropalatography, an intra-oral access device is being developed which increases the range and sensitivity of control available to the severely physically disabled individual. The system provides the user with a consistent positional relationship between the tongue and sensor in contrast to extra-oral mounted tongue switches. The system allows the tongue to function within the oral cavity where it has maximum speed, agility and mobility and gives the user a chance to increase accuracy through practice. A major benefit of this system is its versatility. By covering the surface area of the plate with a large number of sensors, the groups of sensors that are programmed to act as switches can take any size, shape, position and number to match the user's needs and abilities. As with any developing system, a number of problems have been encountered in practical use.

Adolescent↗