No abstract

This study was undertaken to evaluate the effects of 5 months of α-tocopherol supplementation on physical performance during aerobic exercise training in 30 top-class cyclists. Antioxidative effects of supplementation were also studied. Plasma α-tocopherol concentration increased significantly in the vitamin E-supplemented group, whereas the placebo group showed a trend toward decrease. Physical performance did not improve in the α-tocopherol-supplemented group compared to the placebo group. Heart rates were also not significantly different. Lactate concentrations at the aerobic threshold and the anaerobic threshold were identical. Thus, there was no performance improvement in the α-tocopherol-supplemented group. However there was a significant reduction in CK in serum of the E-supplemented group. A trend toward decrease in GOT, GPT, and LDH was observed with α-tocopherol supplementation. Moreover, significantly reduced malondialdehyde serum levels were measured in the E-supplemented group. The findings indicate a protective effect of α-tocopherol supplementation against oxidative stress induced by strenuous exercise.

No abstract

Hemolytic-uremic syndrome (HUS) is a life-threatening disorder characterized by hemolytic anemia, thrombocytopenia, and renal insufficiency. It is caused mainly by infections with enterohemorrhagic Escherichia coli (EHEC). Recently, Shiga toxin 2, the best-studied virulence factor of EHEC, was reported to interact with complement, implying that complement may be involved in the pathogenesis of EHEC-induced HUS. The aim of the present study was to investigate whether or not the serine protease EspP, an important virulence factor of EHEC, interacts with complement proteins. EspP did not have any effect on the integrity of factor H or factor I. However, EspP was shown to cleave purified C3/C3b and C5. Cleavage of the respective complement proteins also occurred in normal human serum (NHS) as a source of C3/C3b or C5 or when purified complement proteins were added to the supernatant of an EspP-producing wild-type strain. Edman degradation allowed unequivocal mapping of all three main C3b fragments but not of the three main C5 fragments. Complement activation was significantly downregulated in all three pathways for C5-depleted serum to which C5, preincubated with EspP, was added (whereas C5 preincubated with an EspP mutant was able to fully reconstitute complement activation). This indicates that EspP markedly destroyed the functional activity, as measured by a commercial total complement enzyme-linked immunosorbent assay (Wieslab). Downregulation of complement by EspP in vivo may influence the colonization of EHEC bacteria in the gut or the disease severity of HUS.Hemolytic-uremic syndrome (HUS) is the most frequent cause of acute renal failure in children. This disorder is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal insufficiency (26). HUS may be caused by different etiological agents; infections with enterohemorrhagic Escherichia coli (EHEC) are, however, the leading cause of HUS in childhood worldwide (13). EHEC produces several virulence factors, among which Shiga toxins (Stxs) 1 and 2 are probably the best characterized.The complement system is an important part of innate immunity and consists of more than 30 proteins in plasma and on host cells (25). Complement is activated by three different pathways-the classical pathway (CP), the mannan-binding lectin (MBL) pathway, and the alternative pathway (AP)-based on different recognition mechanisms. Finally, all three pathways converge in the generation of C3 convertases, which cleave the central component C3, creating C3a and C3b. Nascent C3b has the transient ability to form a covalent ester bond with a variety of target surfaces and finally becomes an essential subunit of both the CP and AP C5-cleaving enzymes.C3b is further cleaved to iC3b by factor I (FI) in the presence of factor H (FH), CR1, or membrane cofactor protein. FI cleavage of C3b to iC3b inactivates and prevents C3b from functioning in the C3 or C5 convertase enzymes. Further cleavage of iC3b by FI in the presence of CR1 results in the formation of C3c. When C3b ...

Ten untrained subjects and nine trained cyclists were examined during graduated ergometric exercise in the supine position. The levels of epinephrine and norepinephrine in the blood as well as the heart rate and oxygen intake were determined. At submaximum levels, epinephrine, norepinephrine, lactate, and the heart rate are lower in tthe trained than in the untrained subjects; the relative oxygen intake shows no significant difference. The ergometric work capacity is approximately 30% higher in the trained cyclists. During maximum ergometric exercise, the plasma catecholamines, lactate, and the heart rate show no differences between the two groups; the oxygen intake is approximately 30% higher in the trained than in the untrained subjects. A direct relationship exists between catecholamine levels and lactate; however, this relationship becomes less exact during higher exercise intensities: In reference to the same catecholamine concentration, the lactate levels as well as the submaximum heart rates are higher in the trained than in the untrained subjects, the cause of which could be an increased beta-adrenoceptor sensitivity in the trained subjects.