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Biomedical subjects

E Yoder

Publications and source records attributed to E Yoder.

7 recordsLinked to original sources
PubMed1995

Patellofemoral pain in female ballet dancers: correlation with iliotibial band tightness and tibial external rotation.

Review of the literature reveals that ballet dancers have a high incidence of idiopathic patellofemoral pain. Twenty-four female ballet dancers were subjects in a study of the relationship between: 1) iliotibial band (ITB) tightness and patellofemoral pain, and 2) ITB tightness and degrees of tibial external rotation used in the dance demi-plie. Dancers were initially assessed by questionnaire to determine if any had knee pain. Twelve subjects met the study criteria for patellofemoral pain, and 12 dancers without knee pain served as controls for the study, Iliotibial band tightness was measured (Ober test), and degrees of tibial external rotation used during knee flexion (demi-plie) in standing were measured in both legs of all 24 subjects (48 legs). Chi-square analysis of the collected data revealed that there was an association between ITB tightness and patellofemoral pain in the dancers. Data analysis using the Wilcoxon Rank Sum test revealed that the degree of tibial external rotation used by dancers with iliotibial band tightness was significantly greater than those without ITB tightness. This study confirms the assumption that ITB tightness in dancers may be a contributing factor to patellofemoral pain. Follow-up study is indicated to determine if the preservation or restoration of functional ITB length is effective in the prevention and/or treatment of patellofemoral pain in ballet dancers.

Adult↗
PubMed1995

Docosahexaenoic acid synthesis in human skin fibroblasts involves peroxisomal retroconversion of tetracosahexaenoic acid.

The purpose of this study was to determine whether the formation of docosahexaenoic acid in human cells occurs through a pathway that involves 24-carbon n-3 fatty acid intermediates and retroconversion. Normal human skin fibroblasts synthesized radiolabeled docosahexaenoic acid from [1-(14)C]18:3n-3, [3-(14)C]22:5n-3, [3-(14)C]24:5n-3, and [3-(14)C]24:6n-3. The amount of docosahexaenoate formed was reduced in fibroblasts defective in peroxisomal biogenesis, by 90-100% in Zellweger's syndrome and by 50-75% in infantile Refsum's disease. Fatty acid elongation and desaturation were intact in these mutant cells. No decrease in radiolabeled docosahexaenoic acid production occurred in mutant fibroblasts defective in peroxisomal alpha-oxidation or mitochondrial beta-oxidation, or in normal fibroblasts treated with methyl palmoxirate to inhibit mitochondrial beta-oxidation. Therefore, the retroconversion step in docosahexaenoic acid formation occurs through peroxisomal beta-oxidation in normal human cells. These results demonstrate that the pathway for docosahexaenoic acid synthesis in human cells involves 24-carbon intermediates. The limited ability to synthesize docosahexaenoic acid may underlie some of the pathology that occurs in genetic diseases involving peroxisomal beta-oxidation.

Cells, Cultured↗
PubMed1991

Astrocytes, not neurons, produce docosahexaenoic acid (22:6 omega-3) and arachidonic acid (20:4 omega-6).

Elongated, highly polyunsaturated derivatives of linoleic acid (18:2 omega-6) and linolenic acid (18:3 omega-3) accumulate in brain, but their sites of synthesis are not fully characterized. To investigate whether neurons themselves are capable of essential fatty acid elongation and desaturation or are dependent upon the support of other brain cells, primary cultures of rat neurons and astrocytes were incubated with [1-14C] 18:2 omega-6, [1-14C]20:4 omega-6, [1-14C]18:3 omega-3, or [1-14C]20:5 omega-3 and their elongation/desaturation products determined. Neuronal cultures were routinely incapable of producing significant amounts of delta 4-desaturase products. They desaturated fatty acids very poorly at every step of the pathway, producing primarily elongation products of the 18- and 20-carbon precursors. In contrast, astrocytes actively elongated and desaturated the 18- and 20-carbon precursors. The major metabolite of 18:2 omega-6 was 20:4 omega-6, whereas the primary products from 18:3 omega-3 were 20:5 omega-3, 22:5 omega-3, and 22:6 omega-3. The majority of the long-chain fatty acids formed by astrocyte cultures, particularly 20:4 omega-6 and 22:6 omega-3, was released into the extracellular fluid. Although incapable of producing 20:4 omega-6 and 22:6 omega-3 from precursor fatty acids, neuronal cultures readily took up these fatty acids from the medium. These findings suggest that astrocytes play an important supportive role in the brain by elongating and desaturating omega-6 and omega-3 essential fatty acid precursors to 20:4 omega-6 and 22:6 omega-3, then releasing the long-chain polyunsaturated fatty acids for uptake by neurons.

Animals↗
PubMed1990

Role of the blood-brain barrier in the formation of long-chain omega-3 and omega-6 fatty acids from essential fatty acid precursors.

Elongated, more highly polyunsaturated derivatives of linoleic acid (18:2 omega-6) and linolenic acid (18:3 omega-3) accumulate in brain, but their sites of synthesis and mechanism of entry are not well characterized. To investigate the role of the blood-brain barrier in this process, cultured murine cerebromicrovascular endothelia were incubated with [1-14C]18:2 omega-6 or [1-14C]18:3 omega-3 and their elongation/desaturation products determined. The major metabolite of 18:2 omega-6 was 20:4 omega-6, whereas the primary product from 18:3 omega-3 was 20:5 omega-3. Although these products were found primarily in cell lipids, they were also released from the cells and gradually accumulated in the extracellular fluid. Eicosanoid production was observed from the 20:4 omega-6 and 20:5 omega-3 that were formed. No 22:5 omega-6 or 22:6 omega-3 fatty acids were detected, suggesting that these endothelial cells are not the site of the final desaturation step. Although the uptake of 18:3 omega-3 and 18:2 omega-6 was nearly identical, 18:3 omega-3 was more extensively elongated and desaturated. Competition experiments demonstrated a preference for 18:3 omega-3 by the elongation/desaturation pathway. These findings suggest that the blood-brain barrier can play an important role in the elongation and desaturation of omega-3 and omega-6 essential fatty acids during their transfer from the circulation into the brain.

Acetyltransferases↗
PubMed1976

Evidence for an ester bond between thrombin and heparin cofactor.

Heparin cofactor, a thrombin inhibitor, is purified from human plasma by affinity chromatography on heparin-agarose. The nature of the binding between thrombin and the inhibitor is studied by treatment of the complex with 6 M guanidinium chloride, hydroxylamine, and dilute alkali. The complex is not dissociated during gel chromatography in 6 M guanidinium chloride. This result supports an earlier proposal that formation of the complex includes the formation of a covalent bond. Treatment of dodecyl sulfate-denatured complex with hydroxylamine results in dissociation of the complex to yield free thrombin and heparin cofactor. Hydroxylamine does not dissociate the complex unless it is denatured. The complex is also dissociated in dilute sodium hydroxide (pH 12) solutions. These results indicate that the covalent bond between thrombin and the inhibitor is a carboxylic ester.

Alkalies↗