Social media and e-learning use among European exercise science students.

With the rise of digital technologies, electronic learning and communication tools are becoming a firm part of academia to promote knowledge of health sciences. This study sought to analyse the attitude of students regarding social media and digital learning for study purposes in sport and exercise science. A survey was carried out with a questionnaire (20 main items) in six sport science faculties, equally spread across Germany (G), Italy (I) and the United Kingdom (UK) between February and October 2017. The focus areas were students' usage of social media (Facebook, Google+, Instagram, LinkedIn, Skype, Twitter, WhatsApp, YouTube) for academic purposes and their use of e-learning. Data were analysed by quantitative and qualitative methods. 229 students participated in the study (G: 68, I: 121, UK: 40). While YouTube was mostly used for receiving knowledge, WhatsApp and Facebook showed additional preferences for peer contacts for learning purposes and knowledge discussions. Preferred online data sources were PubMed (77%), free access journals (67%), YouTube (66%) and Wikipedia (63%). Often used digital learning materials were own universities' PowerPoints (77%), scripts (59%) and scientific articles (53%). However, some preferences showed national differences. The evaluated participants showed an overall high use of social media and e-learning tools for their studies. Students would like more digital learning sources made available to them by their institutions. However, some differences in preferences of digital learning or communication tools may exist and this should be considered for international approaches to promote health knowledge among students.

Increased sclerostin and preadipocyte factor-1 levels in prepubertal rhythmic gymnasts: associations with bone mineral density, body composition, and adipocytokine values.

SUMMARY: Rhythmic gymnastics as high-impact bone loading sport has positive effects on bone mineralization in prepubertal years. Sclerostin and preadipocyte factor-1 (Pref-1) are hormones that inhibit bone formation. The present study demonstrates that these hormones are higher in gymnasts, and gymnasts present higher bone mineral density (BMD) as compared to controls. INTRODUCTION: Rhythmic gymnasts (RG) start their heavy trainings already in prepuberty and despite of low body fat mass (FM) and hypoleptinemia, their BMD is higher than in non-trained normal girls. The specific role of sclerostin and Pref-1, which are the inhibitors of bone formation, in bone development is not well understood. The impact of sclerostin and Pref-1 levels on BMD, body composition, and adipocytokine values was studied in prepubertal RG and untrained controls (UC). METHODS: Sixty-four 9-10-year-old girls were divided into RG (n = 32) and UC (n = 32) groups. Bone mineral and body composition values were measured by dual-energy X-ray absorptiometry and bone age by X-ray. Sclerostin, Pref-1, leptin, and adiponectin levels were measured from fasting blood samples. RESULTS: Sclerostin (RG 19.8 ± 6.3 pmol/l; UC 15.8 ± 5.4 pmol/l) and Pref-1 (RG 1.6 ± 1.0 ng/ml; UC 1.1 ± 0.5 ng/ml) were higher (p < 0.05) in RG compared with UC. Sclerostin was related to adiponectin (r = 0.41; p < 0.05) in UC. No relationship was found between sclerostin and Pref-1 with BMD values in prepubertal RG and age-matched UC groups. CONCLUSIONS: Sclerostin and Pref-1 levels are higher in RG compared to UC girls. Specific physical activity pattern seen in prepubertal RG has a beneficial effect on bone mineralization despite increased levels of hormones that inhibit bone formation.

p53-dependent and p53-independent anticancer activity of a new indole derivative in human osteosarcoma cells.

Osteosarcoma (OS) is the most common primary malignant tumor of bone, occurring most frequently in children and adolescents. The mechanism of formation and development of OS have been studied for a long time. Tumor suppressor pathway governed by p53 gene are known to be involved in the pathogenesis of osteosarcoma. Moreover, loss of wild-type p53 activity is thought to be a major predictor of failure to respond to chemotherapy in various human cancers. In previous studies, we described the activity of a new indole derivative, NSC743420, belonging to the tubulin inhibitors family, capable to induce apoptosis and arrest of the cell cycle in the G2/M phase of various cancer cell lines. However, this molecule has never been tested on OS cell line. Here we address the activity of NSC743420 by examine whether differences in the p53 status could influence its effects on cell proliferation and death of OS cells. In particular, we compared the effect of the tested molecule on p53-wild type and p53-silenced U2OS cells, and on SaOS2 cell line, which is null for p53. Our results demonstrated that NSC743420 reduces OS cell proliferation by p53-dependent and p53-independent mechanisms. In particular, the molecule induces proliferative arrest that culminate to apoptosis in SaOS2 p53-null cells, while it brings a cytostatic and differentiating effect in U2OS cells, characterized by the cell cycle arrest in G0/G1 phase and increased alkaline phosphatase activity.

Adipocytokines and bone mineral density in adolescent female athletes.

AIM: To evaluate the relationships of visfatin, adiponectin and leptin with bone mineral density (BMD) and bone mineral content (BMC) in adolescent female athletes with different training patterns. METHODS: This study involved 170 healthy 13-15-year-old girls divided into six groups based on activity: sport games (i.e. basketball, volleyball, badminton) (n=49), track sprint (n=24), rhythmic gymnastics (n=23), swimming (n=24), cross-country skiing (n=17) and sedentary controls (n=33). BMD and BMC at femoral neck and lumbar spine (L2-L4) were measured using dual-energy X-ray absorptiometry. Visfatin, adiponectin, leptin, insulin and glucose were measured, and the insulin resistance index was calculated using homeostasis model assessment. RESULTS: There were no relationships found between visfatin concentrations and bone mineral parameters in adolescent female athletes or controls. Adiponectin was inversely correlated to BMD and BMC of femoral neck and lumbar spine (r=-0.47-0.62) in the swimmer group only, but after adjustments for age, height and body mass these associations disappeared. Leptin concentrations correlated with bone mineral parameters even after adjusting for age, height and body mass (r=0.42-0.63) in the gymnast group only. CONCLUSION: We may conclude that after adjustment, leptin is the only adipokine of those measured that correlates to femoral neck and lumbar spine BMD and femoral neck BMC in the rhythmic gymnast group.

Inhibition of autoxidation of egg yolk phosphatidylcholine in homogenous solution and in liposomes by oxidized ubiquinone.

The aim of this study was to obtain a quantification of the antioxidant activity of ubiquinone. To this purpose the oxidation of egg yolk phosphatidylcholine both in solvent and in liposomes initiated by an azocompound has been studied either in the absence or in the presence of ubiquinone-3, using alpha-tocopherol as a reference antioxidant. The two experimental systems gave similar results. In the presence of ubiquinone-3 the oxidation rate was reduced with respect to control experiments but was faster than that in the presence of alpha-tocopherol. The amount of ubiquinone required to decrease the autoxidation rate was so high as to prevent detection of the induction period. The stoichiometric factor was greater than 2 and the rate constant of inhibition was two orders of magnitude lower than that of alpha-tocopherol. It is concluded that high concentrations of ubiquinone are required to exhibit significant antioxidant activity. A possible mechanism compatible with the stoichiometric factor larger than 2 for the inhibiting effect of ubiquinone is also suggested.

Effects of dexamethasone on spermidine N1-acetyltransferase and ornithine activities in rat spleen.

Treatment of rats with the glucocorticoid dexamethasone causes an increase in the activity of cytosolic spermidine N1-acetyltransferase both in the spleen and thymus, but not, however, in liver, kidney or lung. The induced spermidine N1-acetyltransferase activity in the spleen catalyses acetylation of spermidine as well as spermine and sym-norspermidine, but not of diamines and histones. The enzyme induction depends on the dose of dexamethasone, and is suppressed by cycloheximide, which suggests that de novo protein synthesis is required for the action of this glucocorticoid. N1-acetylspermidine accumulates in the spleen after dexamethasone treatment, while spermidine progressively decreases and is partly converted into putrescine, the content of which transiently increases. In accordance with previous reports, dexamethasone was found to cause a rapid and large fall in the activity of spleen ornithine decarboxylase which was effected via the appearance of an inhibitor of the enzyme. Glucocorticoids exert large catabolic effects on lymphoid tissues, and further selectively affect the activities of spermidine N1-acetyltransferase and ornithine decarboxylase in the thymus and spleen. These latter selective responses may represent an important early event in lymphoid tissue response to glucocorticoid hormones.

Modulation of ornithine decarboxylase activity and ornithine decarboxylase-antizyme complex in rat heart by hormone and putrescine treatment.

Ornithine decarboxylase was present in a cryptic, complexed form in an amount approximately equivalent to that of free ornithine decarboxylase activity in adult rat heart. Addition of isoproterenol (10 mg/kg) caused a notable rise in ornithine decarboxylase activity and a simultaneous decrease in the amount of the complexed enzyme. During the period of ornithine decarboxylase decay, when cardiac putrescine content had reached high values, the level of the complex increased above that of the control. Administration of putrescine (1.5 mmol/kg, twice) or dexamethasone (4 mg/kg) produced a decrease of heart ornithine decarboxylase activity, while it did not remarkably affect the level of complexed ornithine decarboxylase, therefore raising significantly the ratio of bound to total ornithine decarboxylase. Putrescine also elicited the appearance of free antizyme, concomitantly with the disappearance of free ornithine decarboxylase activity after 3-4 h of treatment. These results indicate that a significant amount of ornithine decarboxylase occurs in an inactive form in the heart under physiological conditions and that its absolute and relative levels may vary following stimuli which affect heart ornithine decarboxylase activity.

Inhibition of the expression of ornithine decarboxylase by some kappa-opioidergic receptor ligands in difluoromethylornithine-resistant L1210 cells.

In difluoromethylornithine resistant L1210 cells stimulated to growth from quiescence, the selective kappa-opioidergic agonist trans-(+/-)-3,4-dichloro-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneaceta mid e (U-50488H) caused a dose dependent inhibition of the induction of ODC activity, with a half-maximal effect at about 1 microM. U-50488H also provoked reduction of ODC mRNA level and increase of ODC turnover, as well as inhibition of cell growth. U-69593, another kappa-selective agonist, was only slightly effective. The action of U-50488H on ODC induction was not blocked by naloxone, beta-chlornaltrexamine or by the kappa-selective opioid antagonists Mr1452 and nor-binaltorphimine (nBNI). Actually Mr1452 and nBNI exerted some inhibitory effect. Furthermore, the separated enantiomers (+) and (-) of U-50488H were similarly effective. The (-)cis-(1S,2R)-U50488 stereoisomer, exhibiting low affinity for kappa and high affinity for sigma receptors and carbetapentane, another sigma ligand, also inhibited ODC induction, although less effectively than U-50488H. None of several other opioid ligands tested had significant effects on ODC induction. In conclusion, the inhibition of ODC expression by U-50488H does not involve classical, enantiospecific opioid receptors; rather, these results suggest the involvement of a distinct site of action linked to inhibition of lymphoid cell proliferation.

Nitric oxide can function as either a killer molecule or an antiapoptotic effector in cardiomyocytes.

Caspase enzymes are a family of cysteine proteases that play a central role in apoptosis. Recently, it has been demonstrated that caspases can be S-nitrosylated and inhibited by nitric oxide (NO). The present report shows that in chick embryo heart cells (CEHC), NO donor molecules such as S-nitroso-N-acetylpenicillamine (SNAP), S-nitrosoglutathione, spermine-NO or sodium nitroprusside inhibit caspase activity in both basal and staurosporine-treated cells. However, the inhibitory effect of NO donors on caspase activity is accompanied by a parallel cytotoxic effect, that precludes NO to exert its antiapoptotic capability. N-Acetylcysteine (NAC) at a concentration of 10 mM blocks depletion of cellular glutathione and cell death in SNAP-treated CEHC, but it poorly affects the ability of SNAP to inhibit caspase activity. Consequently, in the presence of NAC, SNAP attenuates not only caspase activity but also cell death of staurosporine-treated CEHC. These data show that changes in the redox environment may inhibit NO-mediated toxicity, without affecting the antiapoptotic capability of NO, mediated by inhibition of caspase enzymes. NO may thus be transformed from a killer molecule into an antiapoptotic agent.

Activation of acetyl-CoA carboxylase by a glutamate- and magnesium-sensitive protein phosphatase in the islet beta-cell.

Acetyl-CoA carboxylase (ACC) catalyzes the formation of malonyl-CoA, a precursor in the biosynthesis of long-chain fatty acids, which have been implicated in physiological insulin secretion. The catalytic function of ACC is regulated by phosphorylation (inactive)-dephosphorylation (active). In this study we investigated whether similar regulatory mechanisms exist for ACC in the pancreatic islet beta-cell. ACC was quantitated in normal rat islets, human islets, and clonal beta-cells (HIT-15 or INS-1) using a [(14)C]bicarbonate fixation assay. In the beta-cell lysates, ACC was stimulated by magnesium in a concentration-dependent manner. Of all the dicarboxylic acids tested, only glutamate, albeit ineffective by itself, significantly potentiated magnesium-activated ACC in a concentration-dependent manner. ACC stimulation by glutamate and magnesium was maximally demonstrable in the cytosolic fraction; it was markedly reduced by okadaic acid (OKA) in concentrations (<50 nmol/l) that inhibited protein phosphatase 2A (PP2A). Furthermore, pretreatment of the cytosolic fraction with anti-PP2A serum attenuated the glutamate- and magnesium-mediated activation of ACC, thereby suggesting that ACC may be regulated by an OKA-sensitive PP2A-like enzyme. Streptavidin-agarose chromatography studies have indicated that glutamate- and magnesium-mediated effects on ACC are attributable to activation of ACC's dephosphorylation; this suggests that the stimulatory effects of glutamate and magnesium on ACC might involve activation of an OKA-sensitive PP2A-like enzyme that dephosphorylates and activates ACC. In our study, 5-amino-imidazolecarboxamide (AICA) riboside, a stimulator of AMP kinase, significantly inhibited glucose-mediated activation of ACC and insulin secretion from isolated beta-cells. Together, our data provide evidence for a unique regulatory mechanism for the activation of ACC in the pancreatic beta-cell, leading to the generation of physiological signals that may be relevant for physiological insulin secretion.

Polyamines, NO and cGMP mediate stimulation of DNA synthesis by tumor necrosis factor and lipopolysaccharide in chick embryo cardiomyocytes.

OBJECTIVE: We have recently shown that tumor necrosis factor-alpha (TNFalpha) and lipopolysaccharide (LPS) stimulate DNA synthesis in chick embryo cardiomyocytes (CMs). The aim of the present research was to investigate the pathways involved in this mitogenic response. METHODS: CMs were isolated from 10-day-old chick embryos and grown to confluence. After 20 h of serum starvation the cells were treated with TNFalpha and LPS, and/or specific agonists and antagonists to manipulate the levels of polyamines, NO, cGMP and their biosynthetic enzymes ornithine decarboxylase (ODC), nitric oxide synthase (NOS) and soluble guanylate cyclase (sGC). ODC, NOS, sGC activities and cGMP contents were determined by radiochemical procedures. DNA synthesis was determined by incorporation of [3H]-thymidine. RESULTS: Treatment of CMs with TNFalpha and LPS increased cell number and [3H]-thymidine incorporation. Addition of TNFalpha and LPS provoked an induction of ODC, with consequent polyamine accumulation, and a more delayed enhancement of NOS activity, which appeared to be independent of the activation of the ODC-polyamine system. TNFalpha and LPS treatment also enhanced cGMP level in CMs and both polyamine and NO biosyntheses appeared to be required. Experiments with specific inhibitors of ODC and NOS, as well as with inhibitors of sGC and cGMP-dependent protein kinase (PKG), showed that polyamine-, NO- and cGMP-dependent pathways are required for the mitogenic action of TNFalpha and LPS. Moreover, addition of exogenous polyamines to untreated cells raised the cGMP level in a NO-dependent fashion, and enhanced [3H]-thymidine incorporation. The latter effect was inhibited by sGC or PKG inhibitors. Treatment of quiescent cells with NO donors, 8-bromo-cGMP or YC-1, an sGC activator, also promoted DNA synthesis. Furthermore, putrescine and NO donor can additively activate sGC in cell-free extracts. CONCLUSION: TNFalpha and LPS stimulate DNA synthesis in chick embryo CMs and this effect is mediated by polyamines, NO and intracellular cGMP.

Spermine triggers the activation of caspase-3 in a cell-free model of apoptosis.

Polyamines are ubiquitous organic cations required for cell proliferation. However, some evidence suggested that their excessive accumulation can induce apoptosis. We show here that, in a post-nuclear extract from U937 cells, the addition of spermine triggers the death program, represented by cytochrome c exit from mitochondria, the dATP-dependent processing of pro-caspase-3 and the onset of caspase activity. Spermine is more effective than spermidine, whereas putrescine has no effect. Polyamine acetylation abolishes their pro-apoptotic power. These data demonstrate a direct mechanism responsible for polyamine toxicity and also suggest that an excessive elevation of free polyamines could be involved in the transduction of a death signal.

Spermine causes caspase activation in leukaemia cells.

Exposure of several leukaemia cell types to the polyamine spermine triggered caspase activation. In HL60 cells, the onset of caspase activity correlated with the accumulation of spermine, and was accompanied by the processing of the caspase-3 precursor and the digestion of the substrate proteins PARP and gelsolin. Spermine also induced the accumulation of cytochrome c in the cytosol. Caspase activation triggered by spermine was not blocked by antioxidants or inhibition of polyamine oxidase. The deregulation of polyamine uptake strongly sensitised the cells to spermine-induced caspase activation. These data show that an excessive intracellular level of spermine triggers caspase activation that is not mediated by oxidative mechanisms, and suggest a model where elevated free cytosolic polyamines may act as transducers of a death message.

Age-dependent differences of ATP breakdown and ATP-catabolite release in ischemic and reperfused hearts.

The hearts of young (6 months) and aged (24 months) rats, paced at a frequency of 300 bpm, were perfused by the Langendorff technique and subjected to: 20 min of equilibration perfusion, 30 min of global ischemia (95% reduction of the coronary flow) and 20 min of reperfusion. The control group was equilibrated for 20 min and then aerobically perfused for 50 min. After 20 min of stabilization, ATP and ADP levels and the adenine nucleotide pool were significantly higher in young than aged hearts (15% increase), but no modifications were found between the two age groups after 50 min of aerobic perfusion. Even the energy charge did not change under aerobic conditions. At the end of the ischemic period the levels of ATP and ADP decreased to a similar extent in young and aged hearts. After 20 min of reperfusion the myocardial level of ATP remained lower in comparison to the preischemic and control values in both age groups. At the end of the reperfusion there was a decrease in energy charge and creatine phosphate levels in the aged group in respect to the young group. The concentrations of adenosine, hypoxanthine and xanthine in coronary effluents did not change during ischemia and reperfusion irrespective of the age of the animals. On the contrary, the release of uric acid during ischemia and reperfusion was greater in aged than young hearts (90% increase). Moreover, the level of inosine in perfusates during the ischemic period was significantly lower in the 24-month-old group (30% decrease). These results are in accordance with the increased purine nucleoside phosphorylase activity and the decreased hypoxanthine phosphorybosyl-transferase activity found in the myocardium of the aged vs. young rats at the end of the reperfusion period. These data indicate that in the aged rat hearts, when exposed to ischemic and reperfusion conditions, there is a modification of purine breakdown which leads to a greater production of uric acid in respect to that found in young hearts.

Signaling pathways leading to the induction of ornithine decarboxylase: opposite effects of p44/42 mitogen-activated protein kinase (MAPK) and p38 MAPK inhibitors.

Treatment of serum-starved, human ECV304 cells with histamine or ATP elicited a transient induction of ornithine decarboxylase (ODC), a key enzyme in polyamine synthesis, to an extent similar to that provoked by phorbol myristate acetate or serum re-addition. All these agents also provoked an increase in active phosphorylated p44/42 mitogen-activated protein kinase (MAPK) and p38 MAPK. The involvement of p44/42 MAPK and p38 MAPK in the induction of ODC was investigated by using selective inhibitors. U0126 and PD98059, two specific p44/42 MAPK kinase inhibitors, prevented the induction of ODC elicited by any stimulus employed, whereas SB203580 and SB202190, which are widely used as p38 MAPK inhibitors, enhanced ODC induction in a way that appeared dependent on p44/42 MAPK activation. By using inhibitors of other key signaling proteins that may lead to activation of p44/42 MAPK, we provide evidence that protein kinase C, but not phosphoinositide 3-kinase, is involved in histamine-stimulated ODC induction. These results show that the p44/42 MAPK pathway, but not p38 MAPK, is essential for ODC induction stimulated either by agonists of G-protein-coupled receptors, phorbol esters, or serum, and suggest that the inhibition of ODC induction may be an important event in the antiproliferative response to p44/42 MAPK pathway inhibitors.

Control of survival of proliferating L1210 cells by soluble guanylate cyclase and p44/42 mitogen-activated protein kinase modulators.

Intracellular signaling pathways involved in the survival of proliferating L1210 leukemia cells were investigated by using specific modulators. Among the various inhibitors tested, only 1H-[1,2,4]oxadiazole [4,3-a]quinoxalin-1-one (ODQ), a soluble guanylate cyclase (sGC) inhibitor, was found to induce a marked increase in caspase activity, which was associated with a loss of cell viability and a reduction in cGMP content. ODQ also provoked the processing of caspases-3 and -9, release of cytochrome c and, as early events, reduction of Bcl-2 content and dephosphorylation of Bad at Ser 112. Furthermore, YC-1, an sGC activator, and 8-Br-cGMP, a cell-permeant analogue of cGMP, exerted some protection against various apoptotic stimuli, such as serum deprivation or spermine accumulation. Although PD98059 (2'-amino-3'-methoxyflavone), an inhibitor of the p44/42 mitogen-activated protein kinase (MAPK) pathway, did not increase basal caspase activity, and ODQ did not affect p44/42 MAPK phosphorylation significantly, phorbol myristate acetate stimulated p44/42 MAPK and reduced caspase activation induced by ODQ, serum deprivation, and spermine in a p44/42-dependent manner. SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfonylphenyl)-5-(4-pyridyl)1H-imidazole), a p38 MAPK inhibitor, also partially protected against ODQ-induced apoptosis by increasing p44/42 MAPK phosphorylation. In conclusion, these results suggest that sGC may be relevant both for survival of L1210 cells under basal growing conditions and for protection against various apoptotic stimuli. p44/42 MAPK activation may also confer some protection from apoptosis, but apparently through a pathway largely independent of cGMP.

Inhibition of the expression of ornithine decarboxylase by haloperidol in difluoromethylornithine-resistant leukemia cells.

In difluoromethylornithine-resistant L1210 cells stimulated to grow from quiescence, haloperidol caused an early and dose-dependent inhibition of the induction of ornithine decarboxylase (ODC) activity, with an IC50 of 3.5 microM. This effect was accompanied by a reduction in the ODC mRNA level and inhibition of cell growth. Other sigma ligands of different chemical classes inhibited the induction of ODC activity, whereas sulpiride, a dopamine antagonist devoid of sigma-binding affinity, was ineffective. These results indicate that the inhibition of ODC expression may be an early event involved in the antiproliferative response of leukemia cells to haloperidol.

Purified protein derivative anergy in Kawasaki disease.

It was previously reported from Italy that all patients with Kawasaki disease had a positive tuberculin intradermal test. In this study from Seattle, WA, nine patients with Kawasaki disease showed no reaction to intradermal tuberculin. The difference in results might be caused by the different tuberculin products.

A case for routine screening of coronary artery origins during echocardiography: fortuitous discovery of a life-threatening coronary anomaly.

Anomalous origin of the left main coronary artery from the right sinus of Valsalva with retropulmonary course is a rare congenital abnormality. It is associated with a high incidence of sudden cardiac death, particularly among young, athletic individuals. Many of these individuals do not have symptoms before sudden death, and the diagnosis is usually made at postmortem examination. We present a case of a 15-year-old boy who was evaluated for a systolic click with routine 2-dimensional echocardiography. The anomalous coronary artery was serendipitously identified, allowing surgical intervention. Coronary artery origin and proximal course should be visualized on routine echocardiography in the pediatric population.

The antioxidant activity of ubiquinol-3 in homogeneous solution and in liposomes.

With a view to determining the antioxidant effectiveness of ubiquinol, the autoxidation of egg phosphatidylcholine initiated by an azocompound was studied both in homogeneous solution and in liposomes, either in the presence or in the absence of ubiquinol-3. The results show that ubiquinol behaves as a chain-breaking antioxidant by trapping lipid peroxyl radicals, its inhibition rate constant being about one half of that of alpha-tocopherol in both systems under investigation. In organic solvents the stoichiometric factor was found approx. 2 and in liposomes approx. 0.5, i.e. one fourth of that of alpha-tocopherol. We suggest that the lower value found in model membranes is due to autoxidation of the quinol itself by a radical chain reaction taking place at the polar interface. Ubiquinol-3 exhibits a sparing effect toward alpha-tocopherol, both in liposomes and in tert-butanol. It is suggested, on a thermodynamic basis, that the regeneration of vitamin E from the corresponding radical is more likely to occur by reaction with the ubisemiquinone rather than with the ubiquinol. Although these results, obtained in in vitro systems, can not be directly extrapolated to an in vivo system, they may be useful to clarify the antioxidant role of ubiquinol in biomembranes.