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Biomedical subjects

D A Smith

Publications and source records attributed to D A Smith.

At least 361 records · Page 20Linked to original sources
PubMed1981

Problems in data management when studying chronic illness.

Chronic illness is characterized by a long response time during which many external influences can modify the system. Accurate characterization of such a system may require a large number of attributes. Such "data" complexity, in both the time and the feature domain, introduces a number of operational difficulties into the methodology for the scientific investigation of such systems. One such problem is the investigator's changing viewpoint and understanding of the system during the course of a study. Research data bases with a static attribute content are in conflict with this learning process and are of limited use when incorporated in investigation of chronic illness. Data element refinement is a tool for dealing with this problem, by providing a means for modifying an attribute's definition during the temporal life of a data base. We have been investigating means for supporting refinement of data elements in a large data base for coronary artery disease. For certain data types, we have developed a means of introducing "refined" views of particular data elements into a data base such that programs written prior to the refinement execute properly without modification during the lifetime of the data base. We will describe a data structure we have found suitable for capturing the information base from a broad range of clinical investigations, and our approach to the problem of data element refinement. Examples from ongoing clinical studies will be used to illustrate these ideas.

Chronic Disease↗
PubMed1981

How psychiatrists use vocational rehabilitation resources.

Little information is available in the literature on the extent to which psychiatrists use vocational rehabilitation resources for their patients and the kind of services they use. A survey of 174 members of a regional psychiatric society on their use of vocational rehabilitation services showed that psychiatrists referred few patients, that younger patients were referred more often than older ones, and that men were more often referred than women. Seriously disturbed patients were more often referred than less seriously ill patients. The state vocational rehabilitation agency was the one most often used by the referring psychiatrists. The authors suggest improvements in psychiatric residency training and the establishment of information programs to increase the use of vocational rehabilitation referrals by psychiatrists.

Age Factors↗
PubMed1981

Methods for the estimation of the excretion of proxicromil and its metabolites in the milk of nursing rat mothers.

1. The excretion of proxicromil and its metabolites into the milk of nursing rat mothers and its ingestion by rat pups have been investigated. 2. The methodology employed, hand-milking of the mothers and analysis of suckling rat pups or their stomach contents, has been developed from a review of the scientific literature. The most dependable of the methods used was the analysis of the stomachs of suckling rat pups. This method provided a useful index of radioactivity excreted into milk and allowed calculation of neonate exposure. 3. At a maternal dose level of 20 mg/kg a significant proportion of the dose (1-2%) was excreted into the milk. Analysis of milk taken from rat pup stomachs indicated that both proxicromil (63%) and its hydroxylated metabolites (37%) were present in the milk.

Animals↗
PubMed1981

Device for monitoring 14CO2 in the expired air from beagle dogs: its use in the study of aminopyrine demethylation.

1. A device for serial collection of samples for determination of 14CO2 in the expired air of the beagle dog is described. 2. The device has been evaluated using [14C]aminopyrine as a model compound. The rate of 14C excretion in the expired air initially correlated with the plasma concentrations of aminopyrine rather than the plasma concentrations of 14C. 3. The dog demethylated aminopyrine at the slower rate than the rat. Both species demethylate the unchanged drug more readily than subsequent metabolites.

Aminopyrine↗
PubMed1981

An improved method for the injection of crystalline horseradish peroxidase in neuroanatomical studies.

A simple, inexpensive method for the injection of crystalline horseradish peroxidase is described that uses glass micropipettes. The horseradish peroxidase is expelled from the pipette by a fine wire inserted to the end of the pipette. A clay plug prevents diffusion of HRP during the needle's descent. The technique enables the investigator to reliably produce small, densely labeled injection sites with minimal diffusion. Both the retrograde and anterograde transport seen using this method compare favorably with that seen using iontophoretic or pressure injection methods.

Animals↗
PubMed1980

Afferent projections to quiet attack sites in cat hypothalamus.

Quiet biting attack by a cat on a rat was elicited by electrical stimulation of sites in the cat's lateral hypothalamus. Horseradish peroxidase was deposited at the attack sites. Cells containing reaction products were found in gyrus proreus, anterior and central medial amygdaloid nuclei, lateral and medial preoptic areas, substantia innominata, the bed nuclei of stria terminalis, and anterior commissure. The dorsomedial area of the hypothalamus, paraventricular nucleus, supramammillary region, and posterior hypothalamic area also contained reactive cells. In the midbrain the ventral tegmental area of Tsai, the dorsal and superior central nuclei of the raphe, central gray matter and interpeduncular nucleus were regions with reactive cells. In the pontine region, the locus coeruleus, parabrachial nuclei, nucleus of the lateral lemniscus, and the dorsal tegmental nucleus of Gudden all had reactive cells. There are many structures which send afferent projections to quiet attack sites located in the hypothalamus and the pontine tegmentum. The commonality of afferents to attack sites lends credence to the notion that a complex, distributed, interactive network underlies the neural basis of attack behavior.

Afferent Pathways↗
PubMed1980

Afferent projections to affective attack sites in cat hypothalamus.

Horseradish peroxidase was deposited at sites at which affective attack was elicited by electrical stimulation. Cells containing reaction products were found in the nucleus accumbens, subiculum and presubiculum, the medial nucleus of the amygdala, the lateral and to a lesser extent the medial septal nuclei. In the thalamus cells were found in the paraventricular nucleus and nucleus reuniens. The bed nucleus of the stria terminalis and anterior commissure contained a small number of reactive cells. The lateral and medial preoptic areas were well represented, as was the anterior hypothalamic area. There were numerous cells in a large number of the hypothalamic regions, namely, the lateral hypothalamus particularly the dorsal part, the periventricular area, the dorsal part of the paraventricular nucleus, ventromedial nucleus, the arcuate nucleus, the perifornical region, and even the supraoptic nucleus. The posterior hypothalamic and supramammillary regions also had reactive cells. In the midbrain such cells were found in the ventral, lateral and dorsal central gray matter and in the superior central nucleus of the raphe. In the pontine region, the locus coeruleus, the parabrachial nuclei and the dorsal tegmental nucleus of the Gudden had cells with reaction products. Several of these regions also contained cells after HRP injections at quiet attack sites.

Afferent Pathways↗
PubMed1980

Erythrosine (Red No. 3) and its nonspecific biochemical actions: what relation to behavioral changes?

Biochemical studies have shown that the ability of erythrosine to inhibit dopamine uptake into brain synaptosomal preparations is dependent on the concentration of tissue present in the assay mixture. Thus, the finding that erythrosine inhibits dopamine uptake (which, if true, would provide a plausible explanation of the Feingold hypothesis of childhood hyperactivity) may simply be an artifact that results from nonspecific interactions with brain membranes. In addition, although erythrosine given parenterally (50 milligrams per kilogram) did not alter locomotor activity of control of 6-hydroxydopamine-treated rats, erythrosine (50 to 300 milligrams per kilogram) attenuated the effect of punishment in a "conflict" paradigm.

Animals↗