Histological and immunohistochemical evaluation of sarcoma 180 in mice after treatment with and alfa-D-glucan from the lichen Ramalia celastri

The antitumoral activity of an alfa-D-glucan from the lichen Ramalia celastri was investigated using the tumor Sarcoma 180 (S-180). Mice were inoculated with the tumor and 24 h later received a single dose of alfa-D-glucan (200 mg/kg). Thirty-five days after inoculation the mice were sacrificed and the tumors were examined histopathologically. Morphological analyses showed that the tumor was invasive and that it produced typical and atypical mitoses, neovascularization and an infiltration of inflammatory cells. In treated mice, inflammatory cells were more frequent and the presence of nuclear fragments suggested tumor cell death by apoptosis. The tumors of control and alfa-D-glucan treated mice were negative for laminin but expressed fibronectin, the intensity and distribution of which varied in the connective tissue surrounding the tumor mass, in treated mice than in control mice, but in tumor cells, the expression was greater in control mice. The results indicate that alfa-D-glucan can inhibit tumor growth and affect host defense cell responses. The differences in fibronectin distribution between the control and alfa-D-glucan treated mice, suggest that this protein may play an important role in limiting the invasiveness of malignant cells.

Acid phosphatase activity in ungerminated conidia from Colletotrichum graminicola as determined by spectrophotometric and cytochemical methods

The acid phosphatase in ungerminated conidia from Colletotrichum graminicola, a corn pathogen, was investigated using spectrophotometric and cytochemical methods. Acid phosphatase activity was studied in a homogenate obtained by fragmentation of ungerminated conidia. With p-nitrophenylphosphate as substrate, the apparent Vmax and Km were 1.000 nmol p-nitrophenol/mg of protein/min and 0.631 mM, respectively. The pH and temperature optima were 5.5 and 60 graus Celsius, respectively. A cytochemical ultrastructural assay showed deposition of the reaction product inside vacuoles but not extracellularly on the cell surface. The permeabilization of conidia with Triton X-100 increased acid phosphatase activity eight fold. Compared to other procedures, our method was fast, easy to perform and gave consistent results.