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Biomedical subjects

K Dickson

Publications and source records attributed to K Dickson.

24 records · Page 2Linked to original sources
PubMed1992

Determining the prognosis for limb salvage in major vascular injuries with associated open tibial fractures.

Nineteen patients with open tibial fractures and associated arterial injuries were reviewed. Vascular injuries were documented by either arteriography (74%) or clinical examination and direct visualization of injuries intraoperatively. Arterial injuries were divided into those proximal to and those distal to the trifurcation. Proximal injuries involved the popliteal artery in all cases, whereas distal injuries involved the anterior tibial artery, posterior tibial artery, peroneal artery, or combinations of these arteries. All patients' limbs were initially considered salvageable. The eventual amputation rate was 58%. The Mangle Extremity Severity Scores ranged from 4 to 9, and Gustilo's open fracture classification system included 21% Type IIIB and 79% Type IIIC injuries. An isolated anterior tibial artery or peroneal artery injury had a good prognosis. A poor outcome was correlated with posterior tibial artery and popliteal artery injuries and injuries involving all three major distal trifurcation arteries simultaneously. These findings were statistically significant (P less than .05). Traditional criteria for primary amputation are reviewed, and the relevance of a varied prognosis with specific vascular injuries is discussed.

Adolescent↗
PubMed1991

Localization of epidermal growth factor receptors in cells of the enamel organ of the rat incisor.

Epidermal growth factor (EGF) is a peptide shown to effect precocious incisor tooth eruption in rat pups. Binding sites for EGF were visualized in the continuously erupting adult rat incisor by light and electron microscope radioautography after in vivo injection of 125I-EGF. These binding sites represented EGF receptors because of (i) competition between 125I-EGF binding at 2 min after injection and a coinjected excess of unlabeled EGF; (ii) the receptor-mediated endocytosis of 125I-EGF at 15 and 30 min after injection; and (iii) the demonstration of EGF receptor kinase activation in vivo. The stem and the mitotic cells in the epithelial odontogenic organ at the growing end of the tooth develop into two nondividing layers of the enamel organ: (i) ameloblasts which secrete enamel and are subsequently involved in the enamel maturation process, and (ii) papillary layer cells situated between the blood supply and the ameloblasts. Although few EGF receptors were present at the mitotic end, receptor density was highest at the mature end of the enamel organ. High levels of 125I-EGF binding were found on papillary layer cells and ruffle-ended, but not smooth-ended, ameloblasts. This implies a cyclical exteriorization and internalization of receptors during modulations between the two cell types. These data suggest that the EGF receptor mediates a major function of the enamel organ in the formation of enamel.

Animals↗
PubMed1991

Growth retardation and the development of the respiratory system in fetal sheep.

In an experimental model of fetal growth retardation which involves the reduction of placental mass in ewes, we have investigated the effects of intrauterine deprivation on aspects of structural development of the trachea and lungs of fetal sheep (140 days gestation). We have also measured the volume of luminal liquid aspirated from the lungs and the phospholipid content of this liquid as an index of pulmonary surfactant production. The effects of growth retardation are evident in the trachea where the structural development of the mucosal and submucosal layers has been affected. Abnormal aspects of development include the frequent lack of a ciliated border on epithelial cells in the mucosal layer and the reduction in the extent of the folds usually characteristic of this layer in near term fetal sheep. Although the fetal lungs are smaller in growth retardation (P less than 0.01) they are appropriate for fetal weight and their structural development does not appear to have been retarded. In contrast, lung liquid volume is significantly reduced in relation to lung weight in growth retarded fetuses and the concentration of phospholipids in lung liquids is also reduced (P less than 0.01).

Animals↗
PubMed1985

Induction of acrosome reactions by chondroitin sulfates in vitro corresponds to nonreturn rates of dairy bulls.

This study was designed to relate nonreturn rates to induction of acrosome reactions by the glycosaminoglycan chondroitin sulfate. Semen samples were obtained from four bulls above and four bulls below 65% nonreturn. Washed sperm from four ejaculates from each bull were incubated for 9 h with 0, 1, 10, or 50 micrograms/ml chondroitin sulfate. Acrosome reactions were evaluated by microscopy with Nomarski optics. Sperm from the higher fertility bulls exhibited significantly higher percentages of acrosome reactions to 10 and 50 micrograms/ml of chondroitin sulfate, and the slope of their dose-response regression line was significantly greater.

Acrosome↗
PubMedDate not supplied

Biological hazards.

This article outlines the biological hazards that nurses may face in their workplace. It hopes to inform nurses how they can reduce such hazards at work and contribute to a safer working environment.

Hazardous Substances↗