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PubMed1999

Quantifying aggregation of IgE-FcepsilonRI by multivalent antigen.

Aggregation of cell surface receptors by multivalent ligand can trigger a variety of cellular responses. A well-studied receptor that responds to aggregation is the high affinity receptor for IgE (FcepsilonRI), which is responsible for initiating allergic reactions. To quantify antigen-induced aggregation of IgE-FcepsilonRI complexes, we have developed a method based on multiparameter flow cytometry to monitor both occupancy of surface IgE combining sites and association of antigen with the cell surface. The number of bound IgE combining sites in excess of the number of bound antigens, the number of bridges between receptors, provides a quantitative measure of IgE-FcepsilonRI aggregation. We demonstrate our method by using it to study the equilibrium binding of a haptenated fluorescent protein, 2,4-dinitrophenol-coupled B-phycoerythrin (DNP25-PE), to fluorescein isothiocyanate-labeled anti-DNP IgE on the surface of rat basophilic leukemia cells. The results, which we analyze with the aid of a mathematical model, indicate how IgE-FcepsilonRI aggregation depends on the total concentrations of DNP25-PE and surface IgE. As expected, we find that maximal aggregation occurs at an optimal antigen concentration. We also find that aggregation varies qualitatively with the total concentration of surface IgE as predicted by an earlier theoretical analysis.

2,4-Dinitrophenol↗

PubMedDate not supplied

Unconventional therapy use among children with cancer in Saskatchewan.

The study aimed to estimate the prevalence of unconventional therapy use among children with cancer in Saskatchewan, including identification of the most commonly used therapies, and to describe families' expectations and experiences in doing so. Researchers used a cross-sectional survey design with semi-structured telephone interviews to suit the descriptive and exploratory inquiry and the population focus. The personal telephone interviews occurred during the fall and winter of 1996 to 1997, with the parents coming from a wide range of geographic areas in the province of Saskatchewan. Parents of all children who were aged 14 years or younger when diagnosed with cancer during 1994 and 1995 in Saskatchewan and still living at the time of the study were identified through the provincial cancer registry with the assistance of the Saskatchewan Cancer Agency. Of the 44 families participating (92% of those eligible), 36% reported using unconventional therapy for their child's cancer; another 21% considered it. Reasons included complementing medical treatment, coping with side effects; making the child stronger; and stopping the cancer. Experiences were generally positive. Reasons for not using unconventional therapies included the child doing well and parents placing confidence in the medical system. Parents identified a need for better quality information about unconventional therapies. Unconventional therapies play a substantial complementary role in cancer care for children. Families need support to identify safe and potentially helpful therapies when they choose that route. This requires: more research about therapies' effectiveness; more accessible, quality information; and more training for health professionals in understanding and discussing unconventional therapies. There is considerable research showing that use of unconventional therapies, also known as complementary or alternative therapies, is high among adult cancer patients. Although it is likely reasonable to assume this may also be true for children, there is almost no research on children's use of unconventional therapies for cancer. Knowing the extent of children's use of unconventional therapies and whether those experiences have been beneficial or harmful is essential for parents and health professionals making quality care decisions for children.

Adolescent↗