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Biomedical subjects

L M Wakefield

Publications and source records attributed to L M Wakefield.

68 records · Page 4Linked to original sources
PubMed1985

Increased secretion of type beta transforming growth factor accompanies viral transformation of cells.

Cells transformed by Harvey or Moloney sarcoma virus secrete at least 40 times as much type beta transforming growth factor as their respective untransformed control cells. The transformed cells bind only 20 to 50% as much type beta transforming growth factor as the control cells, suggesting that transformation causes down-regulation of the type beta transforming growth factor receptor.

Biological Assay↗
PubMed1985

Nutrient intake of institutionalized developmentally disabled individuals: impact of the nutrition knowledge of paraprofessionals.

The role of the caretaker in enhancing nutrient intake of developmentally disabled individuals living in an institutional setting was examined. Eighty developmentally disabled residents living at the Western Carolina Center, Morganton, NC, were assessed for anthropometric measurements and for dietary intake, with a 3-day plate waste study. Seventy paraprofessionals/feeders working at the same center were assessed for knowledge of nutrition and food practices and participated in a series of inservice programs on nutrition. Pretest and post-test scores for knowledge of nutrition and food practices were determined. For the paraprofessionals/feeders, inservice programs on nutrition resulted in increased knowledge of nutrition but did not increase the nutritional quality of their own diets. However, statistically significant differences were noted in residents' diets for calories (p less than .05), iron (p less than .05), and niacin (p less than .05) attributable to the inservice programs on nutrition.

Adolescent↗
PubMed1984

Characterization of a membrane receptor for transforming growth factor-beta in normal rat kidney fibroblasts.

A procedure has been developed for the iodination of human transforming growth factor-beta (TGF-beta) with full retention of biological activity. Using the iodinated peptide, saturable receptors have been found for TGF-beta on normal rat kidney fibroblasts, a cell line that will grow in soft agar in the presence of TGFs but not in their absence. Scatchard analysis of the binding data showed a high affinity binding site (dissociation constant equal to 25 to 30 pM with approximately 17,000 receptors per cell). The receptor was specific for TGF-beta with epidermal growth factor, insulin, insulin-like growth factors I and II, platelet-derived growth factor, and TGF-alpha being unable to compete for the binding of 125I-TGF-beta to the receptor. The binding of TGF-beta was a time- and temperature-dependent process. At 37 degrees C, maximal binding was attained within 45 to 60 min after addition of 125I-TGF-beta followed by a rapid decline in cell-associated radioactivity due to degradation of the 125I-TGF-beta. As demonstrated using ammonium acetate, a compound known to inhibit lysosomal enzymes, this degradation was most likely due to the action of proteolytic enzymes found in the lysosome. At 0 degrees C, binding reached a plateau within 2 to 3 h and maintained this level with no apparent drop during the 4-h incubation period. The receptor could be down-regulated by TGF-beta, but not by epidermal growth factor, to approximately 50% of the level initially observed.

Binding, Competitive↗
PubMed1984

Isolation of a membrane protein by chromatofocusing: cytochrome b-561 of the adrenal chromaffin granule.

Chromatofocusing, a form of ion-exchange chromatography in which proteins are separated on the basis of their differing isoelectric points, has been adapted for use with membrane proteins, solubilized by the non-ionic detergent Nonidet P-40. Using a two-step detergent extraction followed by chromatofocusing under high pressure, the highly hydrophobic protein cytochrome b-561 was isolated from chromaffin granule membranes and purified to near homogeneity in a functionally active form, in less than 5 h. Chromatofocusing conditions were optimized empirically since the behaviour of the chromaffin granule membrane proteins conformed less to the theory than that of soluble proteins, and the various factors affecting yield and resolution are discussed. The speed, high resolution and focusing effect could make this method particularly suitable for rapid isolation in a functionally active form of the many membrane proteins that are unstable in dilute solution and when removed from their lipid environment.

Chromaffin Granules↗
PubMed1981

The role of phospholipids in the modulation of enzyme activities in the chromaffin granule membrane.

(1) 93% of protein of chromaffin granule membranes can be solubilized by 1.3% (w/v) sodium cholate. The solubilized material can be substantially delipidated by ammonium sulphate precipitation. After three such cycles less than 2% of the endogenous phospholipids remain. (2) The chromaffin granule membrane Mg2+-ATPase depends on the presence of phospholipids for retention of its full activity. Soybean and extracted chromaffin granule phospholipids fully reactivate the delipidated enzyme provided only one delipidation step is used. (3) Successive ammonium sulphate precipitation steps result in a delipidated, and deactivated ATPase preparation which can be only partially reactivated on re-addition of phospholipids. (4) The phospholipid specificity for reactivation of the Mg2+-ATPase is broad. Although acidic phospholipids allow higher activities than neutral phospholipids, the main requirement appears to be the hydrophobic environment provided by the phospholipid hydrocarbon chains. (5) Correlations between changes in slope in the Arrhenius plot of the Mg2+-ATPase, and phase transitions in the phospholipid used for reactivation suggest that the 'fluidity' of the hydrocarbon chains modulates the activity of the enzyme.

Adenosine Triphosphatases↗
PubMed1975

Food choices of women. Personal, attitudinal, and motivational factors.

Responses of 591 women showed that they purchased and prepared the meals in nine of ten households. Although half preserved a limited amount of food, few had gardens or raised or received livestock for their families' use. Most women ate three meals plus one or two snacks a day. The dominant occupation of the women was homemaker; more men had professional or managerial occupations than other work. More than half the adults had completed more than twelve grades in school. Average gross income per household exceeded $11,000 yearly. The husband would exert the strongest influence on most of the women to try a new food, although most would try a new food if urged to by a doctor, nurse, or nutritionist. The majority were motivated to eat a particular food because of personal or family preferences, which were the dominant motivational factors in eating each food category. Advertising was the least influential.

Adolescent↗
PubMed1975

Food choices of institutionalized vs. independent-living elderly.

Data on food intake of ninety-nine nursing home residents and of ninety-eight independent-living elderly persons with respect to twenty-two food groups were obtained by questionnaire interview. Nutrient intake was calculated by computer and compared with the 1968 Recommended Dietary Allowances. Fewer than half of the respondents in both groups had intakes providing 67 per cent or more the allowances for eight nutrients, and 35 per cent fell below this level for two or more nutrients. There were no significant differences in nutrient intake due to type of living arrangement. However, the nursing home residents had made more changes in eating habits than the independent-living participants, and changes correlated negatively with nutritional scores. Nursing homes might improve residents' nutrient intakes by adjusting menus and food preparation to conform more closely with residents' food preferences.

Aged↗