雷公藤三萜酸C的分离与结构鉴定

雷公藤总甙系雷公藤(Tripterygium wilfordii Hook.f)去皮根心经提取后得到的有效组分,它具有很强的抗炎免疫抑制作用。作者从雷公藤总甙中分离出5个三萜类化合物T_1,T_2,T_3,T_6,T_(28)。本文报道T_(28)化合物的分子结构,其他待另文发表。T_(28)是一个新的乌     

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.