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Objective To investigate the in vivo effect of short-term, moderate dosage synthetic dl-α-tocopherol acetate supplementation on platelet aggregation, coagulation profile, and simulated bleeding time in healthy individuals. α-tocopherol is the most biologically active isomer of Vitamin E, traditionally promoted as an antioxidant and therapeutic agent in cardiovascular disease. In vitro studies have suggested that α-tocopherol plays a role in the inhibition of platelet aggregation. However, further investigations into the effect of α-tocopherol on bleeding in vivo have not duplicated these findings. Materials and methods A total of 42 healthy volunteers complied with a 2-week abstinence period from the use of anti-platelet agents followed by determination of baseline platelet aggregation properties and coagulation studies using citrated whole blood. Moderate dosage Vitamin E (800 IU of dl-α-tocopherol acetate) was then self-administered for 14 days with reevaluation of platelet aggregation and coagulation profile, and simulated bleeding time after 14 days of Vitamin E supplementation. Results Forty subjects completed the 4-week study period. All 40 subjects demonstrated normal baseline coagulation studies and all had collagen-stimulated platelet aggregation assessment performed in triplicate. After Vitamin E supplementation, no significant difference was demonstrated in any study parameter. Conclusions Dietary supplementation with moderate dosage synthetic dl-α-tocopherol acetate did not significantly prolong bleeding or platelet aggregation in vivo . The affect of Vitamin E on platelet aggregation in vitro does not appear to be reproducible in vivo . Therefore, peri-operative discontinuation of Vitamin E may not be necessary.

INTRODUCTION Activation of Vbeta8+ T cells with superantigen staphylococcal enterotoxin B (SEB) and use of an antitumor, anti-CD3 bispecific antibody (BsAb) leads to tumor protective immunity. We hypothesize that Vbeta8+ T-cell activation in combination with BsAb is crucial for tumor protective immunity in this model. METHODS Adolescent C3H/HeN mice were intravenously injected with syngeneic CL62 melanoma to establish pulmonary metastasis. Three days after establishing pulmonary metastasis, predominantly Vbeta8+ T cells are activated with 50 mug of intraperitoneal superantigen SEB. T cells were depleted at different time points in relation to SEB administration to assess the effect on protective immunity against a second tumor challenge. RESULTS Protective immunity is significantly (P < 0.008) decreased when Vbeta8+ depletion occurs 6 h after SEB injection, as growth of rechallenged CL62 melanoma occurred in 43%. Protective immunity is present at all other time points when mice survive Vbeta8+ T-cell depletion. Survival of animals treated with SEB/BsAb (82%) is significantly better (P < 0.002) than with SEB alone (60%) or nontreated control (0%). Survival when Vbeta8+ T-cell depletion occurred at 6 h and 48 h post-SEB is 72% and 77%, respectfully, and is statistically indistinguishable (P < 0.232 and P < 0.602). If T-cell depletion was conducted before SEB administration, however, the combination of SEB and BsAb did not result in significant protective immunity. T-cell depletion before the use of SEB alone, without BsAb, failed to result in significant protective immunity. CONCLUSIONS Depletion of Vbeta8+ T cells 6 h after activation disrupts the development of protective immunity.

Purpose Sildenafil is an oral phosphodiesterase type 5 inhibitor that is a vasodilator used in the treatment of erectile dysfunction. Cyclic nucleotide-dependent vasorelaxation is associated with increases in the phosphorylation of the heat shock related protein 20 (HSP20). The purpose of this study was to determine if sildenafil-induced vasorelaxation is associated with increases in the phosphorylation of HSP20. Materials and methods Peptides containing an 11 amino acid enhanced protein transduction domain (PTD) and the functional 13 amino acid sequence of HSP20 with a phosphoserine (PTD-pHSP20) were synthesized using F-MOC technology. Rings of porcine coronary artery were suspended in a muscle bath and sub-maximally contracted with serotonin. Increasing concentrations of sodium nitroprusside (SNP; 0.01–10 μ m ), sildenafil (0.01–100 μ m ), or PTD-pHSP20 (0.1–1.0 m m ) were added to the baths and the percent relaxation was recorded. To determine if sildenafil-induced vasorelaxation was associated with increases in the phosphorylation of HSP20, rings of porcine coronary artery were untreated (control) or treated with SNP (10 μ m ) or sildenafil (100 μ m ) for 2, 5, and 10 min and then snap frozen. Extracted proteins were then separated using two-dimensional SDS-PAGE, transferred to a membrane, and probed for HSP20. Results Sildenafil induced vasorelaxation of pre-contracted coronary artery in a dose-dependent manner. Sildenafil-induced vasorelaxation was associated with an increase in the phosphorylation of HSP20. Transduction of peptide analogues of pHSP20 led to a dose-dependent relaxation of pre-contracted porcine coronary artery. Conclusions These findings suggest that sildenafil-induced vasorelaxation is associated with increases in the phosphorylation of HSP20 and that transduction of phosphopeptide analogues of HSP20 is sufficient for relaxation of vascular smooth muscle.