Thermal analysis of platelet aggregation assessed by differential scanning calorimetry.

Calorimetry is an analytical method that measures heat flow between a heat source and sample. The sample gains or losses heat based on physical or chemical composition. Differential scanning calorimetry (DSC) compares the results of heating a sample to those for heating a reference material. DSC then measures internal energy or a sample's calorific capacity. The aim of this study was to examine the thermal characteristics of platelet activation. Blood was obtained from human volunteers by venipuncture and collected in 5 ml siliconised and citronated vacutainer tubes. Platelet counts were measured using a hemocytometer. Platelet-rich (PRP) or platelet-poor plasma (PPP) was obtained by centrifugation. Ten microliters of PRP or PPP were placed into aluminum pans for DSC with or without activation by epinephrine (5.0 microM) or CaCl2 (50 microM). To avoid a spontaneous activation of platelets samples were kept frozen, after a 5 min period of stabilization, 5 microl of aggregation-inducing agent was added. Scans were initiated at a -12 degrees C after stabilization, with an increase of a 5 degrees C/min to a maximum of 60 degrees C. The experiments were performed on a TA Differential Scanning Calorimeter (New Castle, DE, USA). The difference in heat evolved between the PRP and PPP during the process of platelet activation was 253 J/g. The difference of heat flow in the activation of PRP versus PPP may correspond to an exothermic process involved in platelet aggregation.

Cytotoxic activity of four Mexican medicinal plants.

Ibervillea sonorae Greene, Cucurbita ficifolia Bouché, Tagetes lucida Cav and Justicia spicigera Scheltdd are Mexican native plants used in the treatment of different illnesses. The ethanolic extract of J. spicigera and T. lucida as well as aqueous extracts from I. sonorae, C. ficifolia, T. lucida and J. spicigera were investigated using sulforhodamine B assay. These extracts were assessed using two cell line: T47D (Human Breast cancer) and HeLa (Human cervix cancer). Colchicine was used as the positive control. Data are presented as the dose that inhibited 50% control growth (ED50). All of the assessed extracts were cytotoxic (ED50 < 20 microg/ml) against T47D cell line, meanwhile only the aqueous extract from T. lucida and the ethanolic extract from J. spicigera were cytotoxic to HeLa cell line. Ethanolic extract from J. spicigera presented the best cytotoxic effect. The cytotoxic activity of J. spicigera correlated with one of the popular uses, the treatment of cancer.

Hematopoietic activity of Smilax aristolochiaefolia (zarzaparrilla) in mice with aplastic anemia.

Smilax aristolochiaefolia (Liliaceae) has been used in Mexican traditional medicine for the treatment of tumors, leprosy, anemia and as a tonic for skin infections and anemia. Aplastic anemia (AA) was induced in CD1 mice 8-12 weeks old distributed 10 animals each in Groups VSC, AA, AASa and AAr. Groups AA, AASa and AAr received benzene (2 ml/kg diluted v/v with corn oil) subcutaneously every three days until 20 dosages had been administered. The vehicular solution control group (VSC) received corn oil and the HC group (healthy control) received saline solution. Two days after the last benzene inoculation, groups AA and HC were bled and sacrificed to count blood and bone marrow cells. Group AASa received an aqueous S. aristolochiaefolia (0.4 g/kg) solution orally on days 3, 5 and 7 after the last dosage of benzene, meanwhile group AAr received no treatment after induction of AA (self recovery). On day 9 these groups were bled and sacrificed to count blood and bone marrow cells. Mice with aplastic anemia treated with S. aristolochiaefolia extract, recovered normal platelet levels and nucleated bone marrow cells as compared with the control, but the counts of erythrocytes and leukocyte were lower than controls (p<0.005). The aqueous extract of S. aristolochiaefolia (zarzaparrilla) restores hematopoeisis in the bone marrow of mice with aplastic anemia.

Detection of cytotoxic activity of Psacalium palladium on normal mouse spleen cells and transformed human cells.

A decoction from roots and rhizomes of Psacalium palladium is used in Mexico for the treatment of tumors and for control of diabetes mellitus, among other ailments. Although hypoglycemic activity has been demonstrated in various experimental models and some compounds have been detected in the roots and rhizomes, such as alkaloids, glycosides and tannins, toxicity studies have not yet been performed. Moreover, since various species taxonomically related to P. palladium have pyrrolizidine alkaloids (hepatotoxic, carcinogenic and mutagenic agents) it is possible that these species also contain potentially toxic substances, which represents a risk for users. The aim of this investigation was study the cytotoxicity of P. palladium on mouse hematopoietic cells and transformed human cells, evaluating the cell proliferation by the technique of sulforhodamine B. An aqueous fraction (AS) reduced population of both types of cells by over 50%; meanwhile the other extracts did not alter cell number. Fraction AP was cytotoxic for DU-145 cells at 10 microg/mL, whereas the remaining extracts acted like cytostatic agents.