Inhibition of Bacterial Translocation from the Gastrointestinal Tract of Mice Injected with Cyclophosphamide

Effects of intraperitoneal injection of cyclophosphamide, an immunosuppressant, on the degree of bacterial translocation and morphological changes of Peyer's patches (PP) in the intestine were investigated with antibiotic-decontaminated SPF mice and germfree mice monoassociated with Escherichia coli C25. It has been reported that treatment with cyclophosphamide induces bacterial translocation. Cyclophosphamide treatment in this study, however, significantly decreased E. coli C25 translocation from the gastrointestinal tract to the mesenteric lymph nodes (MLN), although the numbers of lymphoid cells, especially B cells, in the PP, MLN, and spleen were remarkably reduced. Four injections of cyclophosphamide at a dose of 100 mg/kg inhibited bacterial translocation more than one injection at a dose of 200 mg/kg in SPF mice. Germfree mice, however, treated with one dose of 200 mg/kg showed the same inhibition of bacterial translocation as those given 100 mg/kg four times. In cyclophosphamide-treated mice, lymph follicles in the PP were obviously smaller than those in control mice, M-cells were similar in appearance to absorption epithelial cells except for short microvilli, and immune cells among the M-cells had disappeared. These data suggested that inhibition of bacterial translocation in mice treated with cyclophosphamide may be the result of morphological and physiological changes of epithelial cells in the gastrointestinal tract, especially M-cells, as a point of entry of invading bacteria, independent of the changes in immunological function. Received: 16 November 1995 / Accepted: 12 December 1995     

Similarity of rocky intertidal assemblages along the Pacific coast of Japan: effects of spatial scales and geographic distance

Factors and processes affecting community structures operate at various spatial and temporal scales. We analyzed how similarities of rocky intertidal assemblages vary at different spatial scales using a nested, hierarchical sampling design. Intertidal assemblages consisting of algae, sessile animals, and mobile animals were censused on five rock walls at each of five shores chosen within each of six regions along the Pacific coast of Japan, encompassing 1,800 km of coastlines. Based on this sampling design, similarities in assemblages were calculated using both qualitative (presence/absence) and quantitative (percent cover and density) data, and compared at three spatial levels: (1) rock level (the finest spatial scale, encompassing several to hundreds of meters), (2) shore level (the intermediate spatial scale, encompassing several to tens of kilometers), and (3) region level (the broadest spatial scale, encompassing hundreds to thousands of kilometers). Cluster analysis showed that assemblages were categorized into distinct regional groups except for the two southern regions, but they did not separate clearly from each shore. A nested analysis of similarities revealed significant variation in similarities among regions and among shores within each region, with the former showing greater variation. Similarity was negatively correlated with geographic distance at the regional level but not at the shore or the rock levels. At the regional level, similarity decreased more rapidly with distance for mobile animals than sessile organisms. The analyses highlighted the importance of broad-scale abiotic/biotic factors such as oceanic current conditions and biogeographic factors in determining observed patterns in similarity of rocky intertidal assemblages.     

Ecological studies on the timberline of Mt. Fuji

To compare the nutrient economy of woody plants at timberline of Mt. Fuji, seasonal changes in nitrogen content in leaves were examined. There was remarkable difference in seasonal changes in leaf nitrogen content betweenAlnus maximowiczii and other deciduous trees at same habitat.A. maximowiczii scarcely withdrew the leaf nitrogen to woody part during the shedding period, while the other species withdrew about half of the leaf nitrogen to woody part.     

Angioarchitecture of primary oral malignant melanomas.

Angiogenesis is an essential process in the progression of malignant tumors. However, little is known of the angioarchitecture in primary oral malignant melanoma. We sought to determine this by the use of periodic acid-Schiff (PAS) stain, endothelial markers (CD34, CD105) and laminin, and by transmission electron microscopy in two cases. The results demonstrated that endothelium-lined vessels dominated the tumor microvasculature and these stained positively for PAS, laminin, and endothelial markers. Mosaic and tumor-lined vessels were infrequently encountered. Most PAS-positive patterned networks and loops ultrastructurally represented intratumor microhemorrhages that probably arose secondary to tumor vessel leakiness. Vascular channels of the vasculogenic mimicry type were rare. They stained for laminin but not for endothelial markers.