Collagenous Colitis

A middle-aged female with chronic, watery diarrhea was diagnosed after extensive evaluation as having collagenous colitis. The clinical, histological, and pathological findings of our case and those previously reported are reviewed. The diagnostic importance of total colonoscopy with biopsy in a normal-appearing colon in a patient with chronic, undiagnosed, watery diarrhea is discussed.     

Incomplete antigenic cross-reactivity between platelets and megakaryocytes: relevance to ITP

Immune thrombocytopenias are usually associated with normal or increased numbers of megakaryocytes in the marrow. Therefore, the mechanism(s) responsible for the destruction of circulating platelets may not affect megakaryocytes in the same way. One of the possibilities which could account for the differential effect on the cells would be the development of antibodies to components of platelet membranes which are not exposed on the surface of all megakaryocytes. To investigate this possibility, a rabbit antiserum specific for mouse platelets was tested against fresh and cultured mouse megakaryocytes by indirect immunofluorescence. This antiserum cross-reacted with 46% of fresh murine megakaryocytes and 54% of cultured megakaryocytes. Phase- contrast microscopy revealed the reacting megakaryocytes to be fully granulated with irregular contours and in the process of releasing platelets. Nonreactive megakaryocytes demonstrated smooth contours and lacked morphological evidence of thrombocytopoiesis. Electron microscopy showed that only in megakaryocytes (MK) with an irregular contour had the demarcation membrane system (DMS) reached continuity with the plasma membrane. Ultrastructural analysis of megakaryocytes from patients with ITP showed approximately 25% to 50% of megakaryocytes without evidence of injury, whereas 50% to 75% had extensive damage. In undamaged cells, platelet territories had not yet reached the peripheral zone. The DMS of damaged megakaryocytes opened to the exterior elaborating platelets. The observations suggested that some platelet antibodies react only with megakaryocytes which have reached the stage of thrombocytopoiesis. Relevant target antigens may not be exposed on all megakaryocytes before cytoplasmic fragmentation occurs.     

肾上腺髓质素的分子生物学意义及对肾脏损伤的影响

0 引言 肾上腺髓质素(adrenomedullin,ADM)是一种从人嗜铬细胞瘤组织中分离纯化出的多肽,它在正常肾上腺髓质及源于肾上腺髓质的嗜铬细胞瘤中含量丰富.近年来发现ADM在肾脏功能调节方面起着重要作用,现对ADM的生物学特性、生物学作用及其对肾脏的作用进行概述.     

Partial chimerism after T-cell-depleted allogeneic bone marrow transplantation in leukemic HLA-matched patients: a cytogenetic documentation

We evaluated serially by cytogenetics the blood and marrow chimerism of 38 leukemic recipients of HLA-matched bone marrow transplants (BMT) who were prepared by high doses of alkylating agents and fractionated total- body irradiation (2.2 Gy X 5). Donor or host mitoses were identified by examination of sex chromosomes in 32 patients or by evaluation of the polymorphism of other chromosomes after specific banding in six patients. Twenty-four patients were recipients of untreated BMT, and 14 were recipients of T-cell-depleted BMT. In the 24 patients who received untreated BMT, all showed successful engraftment, and only three had a transient mixed chimera. In the 14 recipients of T-cell-depleted BMTs, four rejected their grafts, and seven had mixed chimeras; these mixed chimeras were more frequent in blood lymphocytes than in marrow cells and could be detected up to 26 months after BMT. This high frequency of partial chimerism after T-cell-depleted BMT by comparison with a control group suggests that the donor's T cells play an important role in the eradication of host residual hematopoiesis after allogeneic BMT.