10 research outputs found
Experimental study of vertical stress profiles of a confined granular bed under static and dynamic conditions
Transepidermal UV radiation of scalp skin ex vivo induces hair follicle damage that is alleviated by the topical treatment with caffeine
Objectives
Although the effect of ultraviolet radiation (UVR) on human skin has been extensively studied, very little is known on how UVR impacts on hair follicle (HF) homeostasis. Here, we investigated how solar spectrum UVR that hits the human skin surface impacts on HF biology, and whether any detrimental effects can be mitigated by a widely used cosmetic and nutraceutical ingredient, caffeine.
Methods
Human scalp skin with terminal HFs was irradiated transepidermally ex vivo using either 10 J/cm2 UVA (340â440 nm) + 20 mJ/cm2 UVB (290â320 nm) (low dose) or 50 J/cm2 UVA + 50 mJ/cm2 UVB (high dose) and organâcultured under serumâfree conditions for 1 or 3 days. 0.1% caffeine (5.15 mmol/L) was topically applied for 3 days prior to UV exposure with 40 J/cm2 UVA + 40 mJ/cm2 UVB and for 3 days after UVR. The effects on various toxicity and vitality readâout parameters were measured in defined skin and HF compartments.
Results
Consistent with previous results, transepidermal UVR exerted skin cytotoxicity and epidermal damage. Treatment with high and/or low UVA+UVB doses also induced oxidative DNA damage and cytotoxicity in human HFs. In addition, it decreased proliferation and promoted apoptosis of HF outer root sheath (ORS) and hair matrix (HM) keratinocytes, stimulated catagen development, differentially regulated the expression of HF growth factors, and induced perifollicular mast cell degranulation. UVRâmediated HF damage was more severe after irradiation with high UVR dose and reached also proximal HF compartments. The topical application of 0.1% caffeine did not induce skin or HF cytotoxicity and stimulated the expression of IGFâ1 in the proximal HF ORS. However, it promoted keratinocyte apoptosis in selected HF compartments. Moreover, caffeine provided protection towards UVRâmediated HF cytotoxicity and dystrophy, keratinocyte apoptosis, and tendential upâregulation of the catagenâpromoting growth factor.
Conclusion
Our study highlights the clinical relevance of our scalp UV irradiation ex vivo assay and provides the first evidence that transepidermal UV radiation negatively affects important human HF functions. This suggests that it is a sensible prophylactic strategy to integrate agents such as caffeine that can act as HF photoprotectants into sunâprotective cosmeceutical and nutraceutical formulations.
We show here that solar UVA+UVB radiation impacting on the skin surface negatively affects HF functions, namely it triggers HF cytotoxicity, dystrophy, oxidative DNA damage, decrease in keratinocyte proliferation and increase in their apoptosis, stimulation of the production of transforming growth factor (TGF)âÎČ2 and decrease in insulin growth factor (IGF)â1 expression in ORS keratinocytes, premature catagen development, and perifollicular mast cell degranulation. UVâmediated damage is present throughout the HF length, but is more prominent in the upper layers of the skin (distal HF), as compared to the lower HF (central and proximal). Our study also shows that the topical application of 0.1% caffeine protects HFs from UVRâmediated damaged, namely it alleviated UVâmediated HF cytotoxicity and dystrophy, keratinocyte apoptosis in the distal and central ORS, and increased expression of TGFâÎČ2 in the proximal ORS.
Résumé
Objectifs
Alors que l'effet de rayons ultraviolets (RUV) sur la peau humaine a Ă©tĂ© largement Ă©tudiĂ©, on sait trĂšs peu de choses de l'impact des UV sur l'homĂ©ostasie du follicule pileux (FP). Ici, nous avons Ă©tudiĂ© l'effet du spectre des RUV solaires qui atteignent la surface de la peau humaine sur la biologie du FP, et si tout effet nocif peut ĂȘtre attĂ©nuĂ© par de la cafĂ©ine, un ingrĂ©dient cosmĂ©tique et neutraceutique largement utilisĂ©.
MĂthodes
Une peau de cuir chevelu humain avec ses FP terminaux a Ă©tĂ© irradiĂ©e ex vivo via lâĂ©piderme soit par 10 J/cm2 dâUVA (340â440 nm) + 20 mJ/cm2 dâUVB (290â320 nm) (dose faible) soit par 50 J/cm2 dâUVA + 50 mJ/cm2 dâUVB (dose Ă©levĂ©e) et placĂ©e en culture sans sĂ©rum pendant 1 ou 3 jours. 0,1% (5,15 mM) de cafĂ©ine a Ă©tĂ© appliquĂ©e par voie topique pendant 3 jours avant l'exposition aux UV Ă raison de 40 J/cm2 dâUVA + 40 mJ/cm2 UVB et pendant 3 jours aprĂšs l'exposition aux RUV. Les effets sur divers paramĂštres de toxicitĂ© et de vitalitĂ© ont Ă©tĂ© mesurĂ©s au niveau de compartiments dĂ©finis de la peau et des FP.
RĂsultats
CohĂ©rent avec les rĂ©sultats prĂ©cĂ©dents, les RUV transĂ©pidermique ont exercĂ© une cytotoxicitĂ© au niveau de la peau et des lĂ©sions Ă©pidermiques. Le traitement par des doses Ă©levĂ©es et/ou faibles dâUVA+UVB a Ă©galement induit des lĂ©sions oxydatives de lâADN et une cytotoxicitĂ© au niveau des FP humains. En outre, il a diminuĂ© la prolifĂ©ration et favorisĂ© l'apoptose de la gaine externe de la racine (ORS) du FP et des kĂ©ratinocytes de la matrice des cheveux (MC), a stimulĂ© le dĂ©veloppement de la phase catagĂšne, a rĂ©gulĂ© de maniĂšre diffĂ©rentielle l'expression des facteurs de croissance des FP, et induit une dĂ©granulation pĂ©rifolliculaire des mastocytes. Les lĂ©sions du FP mĂ©diĂ©es par les RUV Ă©taient plus graves aprĂšs une irradiation par dose Ă©levĂ©e de RUV et atteignaient Ă©galement les compartiments proximaux du FP. L'application topique de 0,1 % de cafĂ©ine n'a pas induit de cytotoxicitĂ© de la peau ou du FP et a stimulĂ© l'expression dâIGFâ1 dans la partie proximale de lâORS du FP. Cependant, elle a promu l'apoptose des kĂ©ratinocytes dans certains compartiments de FP. En outre, la cafĂ©ine a fourni une protection des FP contre la cytotoxicitĂ© et la dystrophie mĂ©diĂ©es par les RUV, l'apoptose des kĂ©ratinocytes et une rĂ©gulation Ă tendance positive de l'effet catagĂšne induit par le facteur de croissance.
Conclusion
Notre étude souligne la pertinence clinique de notre dosage d'irradiation UV ex vivo du cuir chevelu et fournit la premiÚre preuve que le rayonnement UV transépidermique affecte négativement d'importantes fonctions du FP chez l'homme. Cela suggÚre que l'intégration d'agents photoprotecteurs des FP tels que la caféine dans les formulations cosmétiques et nutraceutiques des écrans solaires pourrait constituer une stratégie prophylactique sensée
Jets and QCD: A Historical Review of the Discovery of the Quark and Gluon Jets and its Impact on QCD
The observation of quark and gluon jets has played a crucial role in establishing Quantum Chromodynamics [QCD] as the theory of the strong interactions within the Standard Model of particle physics. The jets, narrowly collimated bundles of hadrons, reflect configurations of quarks and gluons at short distances. Thus, by analysing energy and angular distributions of the jets experimentally, the properties of the basic constituents of matter and the strong forces acting between them can be explored. In this review, which is primarily a description of the discovery of the quark and gluon jets and the impact of their observation on Quantum Chromodynamics, we elaborate, in particular, the role of the gluons as the carriers of the strong force. Focusing on these basic points, jets in e+eâ collisions will be in the foreground of the discussion and we will concentrate on the theory that was contemporary with the relevant experiments at the electron-positron colliders. In addition we will delineate the role of jets as tools for exploring other particle aspects in ep and \hbox{} collisions  â quark and gluon densities in protons, measurements of the QCD coupling, fundamental 2-2 quark/gluon scattering processes, but also the impact of jet decays of top quarks, and W ± , Z bosons on the electroweak sector. The presentation to a large extent is formulated in a non-technical language with the intent to recall the significant steps historically and convey the significance of this field also to communities beyond high energy physics
Tobacco Smoking: Risk to Develop Addiction, Chronic Obstructive Pulmonary Disease, and Lung Cancer
The Influence of Vitamin D on Neurodegeneration and Neurological Disorders: A Rationale for its Physio-pathological Actions
International audienc
The Large HadronâElectron Collider at the HL-LHC
The Large HadronâElectron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy-recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High-Luminosity Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electronâproton and protonâproton operations. This report represents an update to the LHeC's conceptual design report (CDR), published in 2012. It comprises new results on the parton structure of the proton and heavier nuclei, QCD dynamics, and electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics by extending the accessible kinematic range of leptonânucleus scattering by several orders of magnitude. Due to its enhanced luminosity and large energy and the cleanliness of the final hadronic states, the LHeC has a strong Higgs physics programme and its own discovery potential for new physics. Building on the 2012 CDR, this report contains a detailed updated design for the energy-recovery electron linac (ERL), including a new lattice, magnet and superconducting radio-frequency technology, and further components. Challenges of energy recovery are described, and the lower-energy, high-current, three-turn ERL facility, PERLE at Orsay, is presented, which uses the LHeC characteristics serving as a development facility for the design and operation of the LHeC. An updated detector design is presented corresponding to the acceptance, resolution, and calibration goals that arise from the Higgs and parton-density-function physics programmes. This paper also presents novel results for the Future Circular Collider in electronâhadron (FCC-eh) mode, which utilises the same ERL technology to further extend the reach of DIS to even higher centre-of-mass energies