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The concept of an immunopathogenesis in the establishment and progression of the recurrent aphthous stomatitis (RAS) lesion is well accepted. In this study the expression of Class I and Class II major histocompatibility complex (MHC) antigens on the epithelial cells in the preulcerative, ulcerative and healing phases of RAS lesions was investigated using monoclonal antibodies in an immunohistological technique. Both Class I and Class II MHC antigens were found on the basal cells in preulcerative lesions. As the lesions progressed to the ulcerative phase, antigen expression occurred on the cell membranes throughout the entire thickness of the epithelium. With healing, the expression of both Class I and Class II MHC antigens on epithelial cells declined to a stage where there was little or no detectable antigen on the cell membranes. Although cytotoxity of epithelial cells in RAS lesions is accepted the role of MHC antigen expression on these cells is uncertain and remains to be ascertained. Nevertheless, the results of the present study indicate that MHC antigens are expressed by epithelial cells in RAS and their expression follows a defined sequence.

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Published qualitative studies have not focused on nurses who solely care for children with special health care needs. The purpose of this study was to explore and describe (a) the work of school nurses who care exclusively for these children, (b) nurses' interaction with parents, staff, or providers, and (c) the challenges, benefits, and support for their role. Data from on-site observation and in-depth interviews with experienced, long-term employed nurses (n = 13) were analyzed using qualitative descriptive inquiry. Performing a personally satisfying clinical role, school nurses adapted to a "teachers world" by working alone, feeling responsible; begging, bartering, and subsidizing; and embracing school as family. They bridged home and school by doing for children, building relationships with parents, and knowing the child. Nurses need to be supported through peer supervision and adequate resources to provide family-centered care to students in a setting dominated by education professionals.

Calcitonin-containing cells (C cells) were identified in male Wistar white rats using an immunoperoxidase technique. They occupied a central position within the thyroid; very few were found peripherally, inferiorly, and superiorly; and none were present in the isthmus. The number of calcitonin-containing cells present per gram of body weight increased with age up to 70 days and had declined by 100 days. Determining the true total C-cell count through the entire thyroid is a very laborious procedure. However, a simple estimate of this total count can be made; the total number of C cells in every tenth section (6 microns) of thyroid was found to be highly correlated with the weight of the animal expressed as an allometric function. A better estimate can be derived from counts of just three sections: the tenth, twentieth, and thirtieth after the section of greatest cross sectional area.

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Twenty-four rats were divided into groups that received cumulative doses of 500, 750, and lo00 rads of fractionated megavoltage X-irradiation. The animals sacrificed after three days showed acinar atrophy with isolated areas containing both severely and lethally damaged cells. The cells were undergoing apoptosis or showed the intracellular accumulation of vacuoles that coalesced and led to lysis. The pattern and severity of damage was dose-related. The animals sacrificed after 14 days had achieved a remarkable degree of recovery as judged morphologically. The group that received the highest cumulative dosage also showed the greatest degree of recovery with an almost totally normal architecture and morphology restored within 14 days.