107 research outputs found
Sunscreens - Which and what for?
It is well established that sun exposure is the main cause for the development of skin cancer. Chronic continuous UV radiation is believed to induce malignant melanoma, whereas intermittent high-dose UV exposure contributes to the occurrence of actinic keratosis as precursor lesions of squamous cell carcinoma as well as basal cell carcinoma. Not only photocarcinogenesis but also the mechanisms of photoaging have recently become apparent. In this respect the use of sunscreens seemed to prove to be more and more important and popular within the last decades. However, there is still inconsistency about the usefulness of sunscreens. Several studies show that inadequate use and incomplete UV spectrum efficacy may compromise protection more than previously expected. The sunscreen market is crowded by numerous products. Inorganic sunscreens such as zinc oxide and titanium oxide have a wide spectral range of activity compared to most of the organic sunscreen products. It is not uncommon for organic sunscreens to cause photocontact allergy, but their cosmetic acceptability is still superior to the one given by inorganic sunscreens. Recently, modern galenic approaches such as micronization and encapsulation allow the development of high-quality inorganic sunscreens. The potential systemic toxicity of organic sunscreens has lately primarily been discussed controversially in public, and several studies show contradictory results. Although a matter of debate, at present the sun protection factor (SPF) is the most reliable information for the consumer as a measure of sunscreen filter efficacy. In this context additional tests have been introduced for the evaluation of not only the protective effect against erythema but also protection against UV-induced immunological and mutational effects. Recently, combinations of UV filters with agents active in DNA repair have been introduced in order to improve photoprotection. This article reviews the efficacy of sunscreens in the prevention of epithelial and nonepithelial skin cancer, the effect on immunosuppression and the value of the SPF as well as new developments on the sunscreen market. Copyright (C) 2005 S. Karger AG, Basel
Hadronically decaying color-adjoint scalars at the LHC
We study the phenomenology of the pair-production of scalar color-octet
electroweak singlet states at the LHC. Such states appear in many extensions of
the Standard Model. They can be pair-produced copiously at the LHC and will
signal themselves as resonances in multijet final states. Beyond the QCD
pair-production process we consider a vectorlike confinement scenario with an
additional color-octet vector state. These vector particles can be produced in
the s-channel and through their decay contribute to the scalar pair production.
We point out the differences between the two hypotheses and device a strategy
to distinguish them.Comment: 15 pages, 10 figure
Genotoxicity and carcinogenicity of the light emitted by artificial illumination systems
Composite Octet Searches with Jet Substructure
Many new physics models with strongly interacting sectors predict a mass
hierarchy between the lightest vector meson and the lightest pseudoscalar
mesons. We examine the power of jet substructure tools to extend the 7 TeV LHC
sensitivity to these new states for the case of QCD octet mesons, considering
both two gluon and two b-jet decay modes for the pseudoscalar mesons. We
develop both a simple dijet search using only the jet mass and a more
sophisticated jet substructure analysis, both of which can discover the
composite octets in a dijet-like signature. The reach depends on the mass
hierarchy between the vector and pseudoscalar mesons. We find that for the
pseudoscalar-to-vector meson mass ratio below approximately 0.2 the simple jet
mass analysis provides the best discovery limit; for a ratio between 0.2 and
the QCD-like value of 0.3, the sophisticated jet substructure analysis has the
best discovery potential; for a ratio above approximately 0.3, the standard
four-jet analysis is more suitable.Comment: 21 pages, 8 figure
Insulin Degrading Enzyme Induces a Conformational Change in Varicella-Zoster Virus gE, and Enhances Virus Infectivity and Stability
Varicella-zoster virus (VZV) glycoprotein E (gE) is essential for virus infectivity and binds to a cellular receptor, insulin-degrading enzyme (IDE), through its unique amino terminal extracellular domain. Previous work has shown IDE plays an important role in VZV infection and virus cell-to-cell spread, which is the sole route for VZV spread in vitro. Here we report that a recombinant soluble IDE (rIDE) enhances VZV infectivity at an early step of infection associated with an increase in virus internalization, and increases cell-to-cell spread. VZV mutants lacking the IDE binding domain of gE were impaired for syncytia formation and membrane fusion. Pre-treatment of cell-free VZV with rIDE markedly enhanced the stability of the virus over a range of conditions. rIDE interacted with gE to elicit a conformational change in gE and rendered it more susceptible to proteolysis. Co-incubation of rIDE with gE modified the size of gE. We propose that the conformational change in gE elicited by IDE enhances infectivity and stability of the virus and leads to increased fusogenicity during VZV infection. The ability of rIDE to enhance infectivity of cell-free VZV over a wide range of incubation times and temperatures suggests that rIDE may be useful for increasing the stability of varicella or zoster vaccines
Long Term Running Biphasically Improves Methylglyoxal-Related Metabolism, Redox Homeostasis and Neurotrophic Support within Adult Mouse Brain Cortex
Oxidative stress and neurotrophic support decline seem to be crucially involved in brain aging. Emerging evidences indicate the pro-oxidant methylglyoxal (MG) as a key player in the age-related dicarbonyl stress and molecular damage within the central nervous system. Although exercise promotes the overproduction of reactive oxygen species, habitual exercise may retard cellular aging and reduce the age-dependent cognitive decline through hormetic adaptations, yet molecular mechanisms underlying beneficial effects of exercise are still largely unclear. In particular, whereas adaptive responses induced by exercise initiated in youth have been broadly investigated, the effects of chronic and moderate exercise begun in adult age on biochemical hallmarks of very early senescence in mammal brains have not been extensively studied. This research investigated whether a long-term, forced and moderate running initiated in adult age may affect the interplay between the redox-related profile and the oxidative-/MG-dependent molecular damage patterns in CD1 female mice cortices; as well, we investigated possible exercise-induced effects on the activity of the brain derived neurotrophic factor (BDNF)-dependent pathway. Our findings suggested that after a transient imbalance in almost all parameters investigated, the lately-initiated exercise regimen strongly reduced molecular damage profiles in brains of adult mice, by enhancing activities of the main ROS- and MG-targeting scavenging systems, as well as by preserving the BDNF-dependent signaling through the transition from adult to middle age
Age Related Changes in NAD+ Metabolism Oxidative Stress and Sirt1 Activity in Wistar Rats
The cofactor nicotinamide adenine dinucleotide (NAD+) has emerged as a key
regulator of metabolism, stress resistance and longevity. Apart from its role as
an important redox carrier, NAD+ also serves as the sole substrate for
NAD-dependent enzymes, including poly(ADP-ribose) polymerase (PARP), an
important DNA nick sensor, and NAD-dependent histone deacetylases, Sirtuins
which play an important role in a wide variety of processes, including
senescence, apoptosis, differentiation, and aging. We examined the effect of
aging on intracellular NAD+ metabolism in the whole heart, lung, liver and
kidney of female wistar rats. Our results are the first to show a significant
decline in intracellular NAD+ levels and NAD∶NADH ratio in all organs
by middle age (i.e.12 months) compared to young (i.e. 3 month old) rats. These
changes in [NAD(H)] occurred in parallel with an increase in lipid
peroxidation and protein carbonyls (o- and m- tyrosine) formation and decline in
total antioxidant capacity in these organs. An age dependent increase in DNA
damage (phosphorylated H2AX) was also observed in these same organs. Decreased
Sirt1 activity and increased acetylated p53 were observed in organ tissues in
parallel with the drop in NAD+ and moderate over-expression of Sirt1
protein. Reduced mitochondrial activity of complex I–IV was also observed
in aging animals, impacting both redox status and ATP production. The strong
positive correlation observed between DNA damage associated NAD+ depletion
and Sirt1 activity suggests that adequate NAD+ concentrations may be an
important longevity assurance factor
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
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