Leukocytes, Platelets, and Surface Microstructure of Spontaneously Degenerated Porcine Bioprosthetic Valves

The microstructure of 33 spontaneously degenerated porcine bioprosthetic valves was assessed by scanning electron microscopy in order to gather insight regarding the degenerative process. Twenty-four mitral and 9 aortic valves were removed from 32 patients. The duration of insertion was 7.7 +/- 2.4 years (mean +/- SD). All valves showed denudation of endothelial cells and exposure of the subendothelial fibrous tissue. Fibroblastlike cells were occasionally seen. Platelet deposits were observed on 22 of 33 valves (67%). Leukocytes were observed on the surface of 27 of 33 valves (82%). Mononuclear leukocytes were the most common category of cells (66%). Crystalline material was present on the surface of some leukocytes, suggesting that they may serve as a nidus for calcification. Transmission electron microscopy showed leukocytes in the process of phagocytizing collagen fibers. Macrophages, by exerting their scavenger function seem to contribute to destruction of the collagen framework of the valves. Whether the observed lymphocytes and plasma cells reflect an immunological involvement is unclear.     

Induction of delayed hypersensitivity to nitrogen mustard in the guinea-pig

The acquisition of allergic contact dermatitis limits the therapeutic usefulness of topical nitrogen mustard in man. A reproducible experimental model for this syndrome has been provided in the guinea-pig. Guinea-pigs were sensitized to nitrogen mustard (HN₂) by means of the repeated epicutaneous administration of sensitizer to a skin site, and the injection into that site of complete Freund's adjuvant. Application of dimethyl sulphoxide before HN₂ to the sensitization or challenge site facilitated the sensitization and challenge procedures. Positive challenge could be elicited by the intradermal injection of a non-toxic amount of HN₂. The methodology extends to the study of a variety of other sensitizers and potential sensitizers.     

In vitro production of erythropoietin by mouse fetal liver

Mouse fetal liver tissue has been cultured and shown to produce and release into the culture medium an erythropoietically active substance for up to 30 days of culture. Since this substance can be completely neutralized by an antiserum to erythropoietin and shows a dose-- response relationship in the plethoric mouse assay, it is suggested that the culture medium contains erythropoietin, a hormone important in the regulation of erythropoiesis. Using this procedure, we have obtained the equivalent of about 20.7 unites of erythropoietin from five T-flasks (75 sq cm) over the 30-day culture period.     

用四阶导数光谱法测定A-OT-Fu小鼠代谢物的血药浓度

本文采用四阶导数光谱测定了小鼠口服A-OT-Fu淀粉液后的主要代谢产物TFu和5-Fu的血药浓度—时间曲线。当TFu和5-Fu浓度为5～50μg/ml时,浓度与252nm和289 nm对零轴间的振幅有良好的线性关系。在本测试条件下TFu和5-Fu的回收率约95%以上,实验结果表明,TFu和5-Fu达到最高血药浓度的时间分别为1和2 h。     

Malignant Tumors Associated with Granulomatous Enterocolitis

Three cases of malignant tumor associated with Crohn's disease of the large intestine are reported.
The reasons for a low incidence of carcinoma associated with Crohn's disease have been postulated.