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D Ellison

Publications and source records attributed to D Ellison.

62 records · Page 4Linked to original sources
PubMedDate not supplied

Immunocytochemical studies of pituitary hormones with PAP, ABC, and immunogold techniques: evolution of technology to best fit the antigen.

The immunocytochemical technology in our laboratory has evolved in response to specific needs for more efficient, refined stains for each antigen. The rationale for the application of each of the immunocytochemical techniques used today is described, and detailed methods are given. In the early 1970s, it was determined that the peroxidase-antiperoxidase complex (PAP) stain provided the most sensitive means of detection of adrenocorticotropin (ACTH) at the electron microscope level even in tissues prepared with conventional fixation and embedding techniques that are considered rather harsh for the maintenance of antigenicity. Application of the same PAP complex technique to the larger glycoprotein antigens, like follicle-stimulating hormone (FSH), however, proved far more difficult; and the problem was resolved partially when more gentle fixation-embedding protocols were applied. The production of an efficient, reliable stain for FSH was achieved only with the avidin-biotin peroxidase complex (ABC) stains were applied in the early 1980s. This technique also allowed more efficient reactions for all the antigens, and morphometric data could thereby be collected more rapidly. Thus, we concluded that the light microscope immunoperoxidase techniques were excellent for the morphometric analysis of pituitary cell types in both pre-embedding and postembedding stains. However, the need for a more refined stain for its quantification at the electron microscope level on individual organelles led to the development of the colloidal gold stain in 1983-1984. This technique, which is new to our laboratory, is also described and illustrated in this report. Also included is a description of our studies of the effect of fixation and embedding processes on hormone antigenicity and techniques used to control background and nonspecific reactions. It is hoped that the novice will find the description of the rationale for the evolution of technology in our laboratory useful in making choices for his or her own immunocytochemical stains.

Animals↗
PubMedDate not supplied

Radiolabeled octreotide. What lessons for antibody-mediated targeting?

Octreotide is a synthetic analog of the peptide hormone somatostatin (SMS). A wide variety of tumors express enhanced numbers of SMS receptors, notably neuroendocrine tumors and lymphomas, but also some of the more common adenocarcinomas. Octreotide contains only eight amino acids, some of which are in the (D) configuration in order to enhance the stability of the molecule in vivo. Tyrosine and DTPA-containing analogs of octreotide have been synthesized and labeled with iodine-123 and indium-111, respectively, with the intention of targeting SMS receptor-containing tumors for diagnostic purposes. Both radiopharmaceuticals demonstrate a high sensitivity and specificity for these tumors, indicating a clinical role for these agents in management of these diseases. Lessons can be learned from the success of these agents when designing improved antibody-based molecules. Tumor uptake of radiolabeled octreotide is very rapid, occurring within minutes of administration. Blood clearance is also rapid, such that tumors are soon visible even in areas of high blood background. An interesting finding has been the differences between the pharmacokinetics of the iodinated and indium-labeled species. Although the majority of 123I-Tyr3-octreotide undergoes hepatobiliary excretion, 111In-DTPAPhe1-octreotide is eliminated predominantly by the kidneys. These results suggest that the smallest possible antibody-like tracers are likely to have advantages over native immunoglobulins and conventional Fab-like fragments.

Adenocarcinoma↗
PubMedDate not supplied

p53 status has no prognostic significance in glioblastomas treated with radiotherapy.

Mutation of the tumor suppressor gene TP53 and accumulation of the p53 protein are common events in the range of cerebral astrocytic tumors, including glioblastomas, but it is uncertain whether these events are associated with prognosis. Evidence suggests that the response of various tumors to radiotherapy may be influenced by the status of p53 which is involved in control of the cell cycle and apoptosis. This study tests the hypothesis that p53 governs survival in patients (n = 62) with glioblastomas who have received radiotherapy. Analysis of TP53 and p53 immunohistochemistry were undertaken using standard methods. TP53 mutations were present in 27% tumors, while 50% were p53-immunopositive (LI > 3%). A strong correlation (p < 0.0001) was found between a high p53 LI (> 50%) and the presence of a mutation, but p53 status at the level of gene or protein was unrelated to survival. Radiation-induced apoptosis that is independent of p53, and the presence in glioblastomas of genetic abnormalities that are also involved in the cellular response to radiation, such as deletions and mutations of pRb, are possible explanations of this result.

Adult↗