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Biomedical subjects

L Dickson

Publications and source records attributed to L Dickson.

26 records · Page 2Linked to original sources

Isolation and characterization of the human fibrillar collagen genes.

In order to elucidate some of the mechanisms leading to the pathological expression of the human fibrillar collagens, as well as to understand the evolution of these loci, specific cDNA and genomic clones have been isolated. The primary structure of the COOH-terminal propeptide of the four collagen chains and either part or the entire exon/intron arrangement of the genes have been determined. Interspecies and pairwise comparison revealed that the four loci have evolved at slightly different rates, maintaining, however, remarkably similar exon/intron arrangement. The fibrillar genes, albeit sharing the same elaborate structure, exhibit different sizes that correlate with the average length of their intron sequences, possibly because of their different chromosomal origin.

Animals↗

Non-organic failure to thrive: a developmental perspective.

Like other segments of the child's development, eating behavior follows a sequential pattern. To understand the infant's or child's feeding problems which can lead to failure to thrive or dwarfism we propose that a child's progression be studied through three stages of development: homeostasis, attachment and separation-individuation. Specific feeding problems can arise at each of these stages of development and consequently impede the child's weight gain. During the period of homeostasis the infant learns to regulate himself, to suck, to swallow and to time the onset and termination of feedings by giving signals of hunger and fullness. If he is unable to master these, he cannot be fed effectively. Failure to master these basic feeding skills interferes with the next developmental task of attachment and also impedes development of motor skills, language and affective engagement. During the period of attachment, the infant establishes distinct interactional patterns with his caretakers. Lack of engagement between mother and infant leads to lack of pleasure and lack of appetite or even to severe dysfunctional feeding patterns like vomiting and rumination. Feeding problems in the third developmental stage of separation and individuation can arise because of maladaption in the attachment phase or because of new difficulties which center around issues of autonomy vs. dependency. At this stage, the infant learns means-end differentiation and begins to understand that his actions elicit certain consequences. If the infant's struggle between autonomy and dependency gets caught in the feeding situation, the infant's emotional needs can dictate his eating behavior. The infant refuses to eat either to have his emotional hunger for mother's attention met or to assert his autonomy and to express his anger toward her. In order for the infant to learn to differentiate between his physiological feelings of hunger and his emotional need states, the caregiver needs to give contingent responses by offering food when the infant is hungry and comfort when the infant is distressed. Feeding problems which can create, co-exist with, or result from a growth problem must be considered within a developmental context. As the infant progresses through the developmental stages of homeostasis, attachment, and separation, he masters phase-appropriate feeding skills which help him to progress from reflex sucking to autonomous feeding. Early identification of maladaptive feeding behavior will assist the pediatrician in making timely interventions.

Child↗

Determination of the von Willebrand's disease antigen (factor VIII-related antigen) in plasma by quantitative immunoelectrophoresis.

Measurement of the von Willebrand's disease antigen (factor viii-related antigen) has become an increasingly useful tool in the differential diagnosis of those disorders of hemostasis characterized by an abnormality of factor viii procoagulant activity. Optimal conditions for assay of the von Willebrand's disease antigen in plasma by the quantitive immunoelectrophoretic technique are described. Potential sources ofsystematic error have been evaluated and a dilution effect has been identified.

Animals↗

Inhibition of growth of subcutaneous xenografts and metastasis of human breast carcinoma by swainsonine: modulation of tumor cell HLA class I antigens and host immune effector mechanisms.

Swainsonine, an indolizidine alkaloid, can decrease the organ colonization potential of metastatic murine tumor cells by augmentation of host immune effector mechanisms. In this report the above findings were extended by the demonstration that systemic administration of swainsonine strongly suppressed the growth of human breast carcinoma subcutaneous xenografts and experimentally induced lung metastases. This inhibition was not due to a direct effect of swainsonine on cell growth. However swainsonine treatment of tumor cells resulted in enhanced expression of HLA Class I antigens, and HLA class I mRNA. Swainsonine was a potent immunodulator as evidenced by the increased (a) cytotoxicity of splenocytes and macrophages, and, (b) proliferative potential of splenocytes and bone marrow cells. These data suggest that swainsonine-induced inhibition of tumor growth and metastases may be mediated via activation of host effector cells and/or alteration of tumor cell antigenicity.

Alkaloids↗

What the SHO saw.

As discussions about junior doctors' training and duty hours continue, we have looked at the actual 'on take' case load and case mix of a medical senior house officer (SHO) in a district general hospital (DGH) over a six-month period. In our DGH, on a one in four rota, exposure to a few common conditions is high and exceeds the minimum requirements for a post to be approved for general professional training. Limited but useful experience may also be gained in the management of many other conditions. The benefits in terms of structured training and lifestyle resulting from the implementation of the Calman report and the junior doctors' hours initiative need to be set against a possible reduction in patient exposure and in the associated opportunities to learn that may occur with a decrease in SHOs' 'front line' exposure.

Education, Medical, Graduate↗