Immunohistochemical visualization of wild-type p53 protein in paraffin- embedded rat liver using tyramide amplification: zonal hepatic distribution of p53 protein after N-hydroxy-2-acetylaminofluorene administration

P53 protein plays an important role in regulation of the cell cycle. Recently, a role in tumour genesis has also been suggested. The protein is induced after various forms of DNA damage. Immunohistochemical detection of p53 protein showed positive cells in human skin after UV- irradiation, in mouse skin after benzo[a]pyrene treatment and in mouse spleen, thymus and bone after gamma-irradiation. However, no staining was found in mouse and rat liver with traditional immunohistochemical staining methods due to the low amount of p53 present. This seriously hampered studies on the role of p53 in hepatocarcinogenesis. We have developed a more sensitive immunohistochemical method for staining of p53 in paraffin-embedded sections of rat liver using microwave irradiation for antigen retrieval, avidin-biotin complexing and tyramide amplification. A strong, specific fluorescence signal for p53 was found in hepatocytes of rats that had received the hepatocarcinogen N-hydroxy-2-acetylaminofluorene; in control liver no such p53 staining was observed. The fluorescence was located in the nucleus of hepatocytes in zone 1 of the liver. This agrees with the fact that N- hydroxy-2-acetylaminofluorene causes cytotoxicity in this zone.      

Enhanced responsiveness to antigen contributes more to immunological memory in CD4 T cells than increases in the number of cells

Although immunological memory is characterized by both an increase in the frequency of antigen-specific T cells and a qualitative change in the pattern of their subsequent response, it is not clear which of these components is more significant in the overall enhanced response to secondary stimulation. To address this question for the CD4+ T-cell response, T-cell receptor (TCR) Tg T cells were adoptively transferred to normal syngeneic mice that were immunized with the relevant peptide. After the initial expansion of TCR Tg T cells, the size of the subsequent memory population of T cells was approximately the same as the size of the starting population, independent of the number of TCR Tg cells initially transferred. This result was not caused by redistribution of memory cells into non-lymphoid tissues, although the relative frequency of antigen-specific T cells in these sites was increased after immunization. The fraction of the antigen specific TCR Tg cells that responded by production of either interleukin-2 or interferon-gammain vitro was substantially higher after immunization. Thus, the increased frequency of functionally responsive T cells was primarily caused by a higher fraction of responding T cells, rather than a substantial increase in the absolute number of antigen specific CD4+ TCR Tg T cells.     

P-selectin glycoprotein ligand-1 is broadly expressed in cells of myeloid, lymphoid, and dendritic lineage and in some nonhematopoietic cells

P-selectin glycoprotein ligand-1 (PSGL-1) is a muclin-like glycoportein ligand for P- and E-selectin on myeloid cells and a subset of lymphocytes. We used flow cytometry and immunohistochemistry to examine expression of PSGL-1 on minor leukocyte populations, differentiating hematopoletic cells, and nonhematopoietic tissues using two monoclonal antibodies to distinct protein epitopes on PSGL-1. In the bone marrow, PSGL-1 was expressed on myeloid cells from the myeloblast stage to the segmented neutrophil, but was not detected on erythroblasts or megakaryocytes. All types of circulating myeloid cells expressed PSGL- 1, and PSGL-1 was retained after extravasation of myetoid cells into tissues. PSGL-1 was also expressed on circulating dendritic cells, monocyte-derived dendritic cells, dendritic cells in lymphoid tissues and epidermis, and follicular dendritic cells. All types of lymphoid cells examined expressed PSGK-1, including immature and mature thymocytes, naive and memory T cells, gamma/delta T cells, netural killer cells, B cells and CD34+ progenitor cells. However, PSGL-1 levels were substantially lower on tonsillar lymphocytes than on circulating lymphocytes, suggesting that PSGL-1 expression is down regulated during or after entry of lymphocytes into secondary lymphoid tissue. Although PSGL-1 antigen was detected primarily on hamatopoietic cells, it was also present on time epithelium of the fallopian tube. Furthermore, PSGL-1 antigen gen was detected sporadically on microvascular endothelium in some pathologic tissues. This suggests that PSGL-1 may have functions other than mediating leukocyte adhersion.     

Phacotrabeculectomy Versus Conventional Combined Technique in Coexisting Glaucoma and Cataract

Background

To evaluate and compare efficacy and outcome after single site phacotrabeculectomy and conventional combined surgery in cases of coexisting primary open angle glaucoma and cataract.

Methods

This prospective study on fifty patients of concurrent primary open angle glaucoma and cataract, who had undergone combined surgery as single site phacotrabeculectomy or conventional single site trabeculectomy with extracapsular lens extraction with IOL implantation in 25 cases each. Evaluation was based on operative and postoperative complications, control of IOP and visual outcome. The follow up period ranged between twelve months to eighteen months.

Results

The mean medically controlled preoperative intraocular pressure was 22 mm of Hg (Range 18 to 35 mm of Hg) by applanation method of tonometry. The range of postoperative intra-ocular pressure after one year was 11 to 22 mm of Hg in first and 14 to 26 mm Hg in second group. Failure to maintain optimum postoperative IOP without Beta-blocker was more frequent after conventional combined procedure. There was no significant difference in incidence and pattern of postoperative complications.

Conclusion

Phacotrabeculectomy provides effective and sustained visual recovery and adequate control of intraocular pressure as compare to conventional combined procedure.Key Words: Phacotrabeculectomy, Comparison with conventional combined procedure