The histamine releasing properties of glucose (mannose)-specific lectins isolated from Brazilian beans was examined. The Canavalia brasiliensis, Dioclea rostrata, and Dioclea virgata lectins induced histamine release in rat peritoneal mast cells similar to concanavalin A. Less potency and efficacy was observed for Canavalia maritima, Dioclea guianensis, and Dioclea violacea while very low activities were seen for the lectins from Dioclea grandiflora, Canavalia bonariensis, and Cratylia floribunda. The histamine releasing effect was quenched by higher doses of D. virgata lectin similar to what was reported for concanavalin A. This effect was abrogated by increasing the concentration of calcium in the incubating medium. As these above proteins have sites that bind calcium, higher doses of the lectins might withdraw the calcium which is essential for the mast cell secretion.

ObjectiveTo evaluate the efficacy of platelet-rich plasma regarding healing, pain and hemostasis after total knee arthroplasty, by means of a blinded randomized controlled and blinded clinical study.MethodsForty patients who were going to undergo implantation of a total knee prosthesis were selected and randomized. In 20 of these patients, platelet-rich plasma was applied before the joint capsule was closed. The hemoglobin (mg/dL) and hematocrit (%) levels were assayed before the operation and 24 and 48 h afterwards. The Womac questionnaire and a verbal pain scale were applied and knee range of motion measurements were made up to the second postoperative month. The statistical analysis compared the results with the aim of determining whether there were any differences between the groups at each of the evaluation times.ResultsThe hemoglobin (mg/dL) and hematocrit (%) measurements made before the operation and 24 and 48 h afterwards did not show any significant differences between the groups (p > 0.05). The Womac questionnaire and the range of motion measured before the operation and up to the first two months also did not show any statistical differences between the groups (p > 0.05). The pain evaluation using the verbal scale showed that there was an advantage for the group that received platelet-rich plasma, 24 h, 48 h, one week, three weeks and two months after the operation (p < 0.05).ConclusionsIn the manner in which the platelet-rich plasma was used, it was not shown to be effective for reducing bleeding or improving knee function after arthroplasty, in comparison with the controls. There was an advantage on the postoperative verbal pain scale.

BackgroundVenous ulcers represent 70% of the lower limb ulcers. They are difficult to heal, requiring a correct diagnostic and therapeutic approach. Many products have been developed to healing, such as homologous platelet gel obtained from the platelet concentrate exceeding from blood transfusion.ObjectiveTo evaluate the safety and efficacy of homologous platelet gel in venous ulcers compared with hydrocolloid dressing.MethodA pilot randomized clinical trial in patients with venous ulcers. Randomized groups (homologous platelet gel and hydrocolloid groups) were followed for 90 days and were assessed through the evolution of ulcerated area, qualitative analysis of vascularization and adverse events. Both groups used elastic compression.ResultsWe included 16 participants, with a total of 21 venous ulcers. Both treatments promoted a reduction of the areas of the ulcers in 90 days (mean 69%), there was significant difference between the groups concerning the gradual reduction of the ulcers areas, favorably to the hydrocolloid (70% vs 64%; p <0.01). There were some mild adverse events in both groups.Study limitationsSingle-center study with a small number of patients, preventing more accurate assessment of the effects of platelet gel.ConclusionThe homologous platelet gel associated with the elastic compression can be an alternative to the venous ulcer treatment and is safe due to the occurrence of a few mild local adverse events and no serious adverse events. Clinical trials with larger numbers of patients must be performed to maintain the indication of this treatment for venous ulcer.

We have characterized the histamine releasing effects of lectins extracted from Brazilian beans, in comparison to concanavalin A, in hamster cheek pouch cell suspensions containing mast cells. The lectins from Dioclea virgata, Canavalia brasiliensis, and Dioclea rostrata induce histamine release in a similar manner to concanavalin A, but appear to differ in potency and efficacy. The effects depended on the temperature, pH, and metabolic energy, demonstrating the non-cytotoxic nature of the histamine release. It is suggested that the lectins studied act by the same mechanism as concanavalin A (interacting with sugars in the antibodies bound to the mast cells), since high concentrations of glucose inhibit the histamine release. The lectins at high concentrations quench the histamine release. This suppression is reversed by increasing calcium concentration, suggesting that the lectins bind to the calcium that is essential for the secretion, thereby confirming and extending our previous data using the lectin from Dioclea virgata in rat peritoneal mast cells.

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