UV Radiation and the Skin

UV radiation (UV) is classified as a complete carcinogen because it is both a mutagen and a non-specific damaging agent and has properties of both a tumor initiator and a tumor promoter. In environmental abundance, UV is the most important modifiable risk factor for skin cancer and many other environmentally-influenced skin disorders. However, UV also benefits human health by mediating natural synthesis of vitamin D and endorphins in the skin, therefore UV has complex and mixed effects on human health. Nonetheless, excessive exposure to UV carries profound health risks, including atrophy, pigmentary changes, wrinkling and malignancy. UV is epidemiologically and molecularly linked to the three most common types of skin cancer, basal cell carcinoma, squamous cell carcinoma and malignant melanoma, which together affect more than a million Americans annually. Genetic factors also influence risk of UV-mediated skin disease. Polymorphisms of the melanocortin 1 receptor (MC1R) gene, in particular, correlate with fairness of skin, UV sensitivity, and enhanced cancer risk. We are interested in developing UV-protective approaches based on a detailed understanding of molecular events that occur after UV exposure, focusing particularly on epidermal melanization and the role of the MC1R in genome maintenance

Divergence of cAMP Signalling Pathways Mediating Augmented Nucleotide Excision Repair and Pigment Induction in Melanocytes

Loss‐of‐function melanocortin 1 receptor (MC1R) polymorphisms are common in UV‐sensitive fair‐skinned individuals and are associated with blunted cAMP second messenger signalling and higher lifetime risk of melanoma because of diminished ability of melanocytes to cope with UV damage. cAMP signalling positions melanocytes to resist UV injury by upregulating synthesis of UV‐blocking eumelanin pigment and by enhancing the repair of UV‐induced DNA damage. cAMP enhances melanocyte nucleotide excision repair (NER), the genome maintenance pathway responsible for the removal of mutagenic UV photolesions, through cAMP‐activated protein kinase (protein kinase A)‐mediated phosphorylation of the ataxia telangiectasia‐mutated and Rad3‐related (ATR) protein on the S435 residue. We investigated the interdependence of cAMP‐mediated melanin upregulation and cAMP‐enhanced DNA repair in primary human melanocytes and a melanoma cell line. We observed that the ATR‐dependent molecular pathway linking cAMP signalling to the NER pathway is independent of MITF activation. Similarly, cAMP‐mediated upregulation of pigment synthesis is independent of ATR, suggesting that the key molecular events driving MC1R‐mediated enhancement of genome maintenance (eg PKA‐mediated phosphorylation of ATR) and MC1R‐induced pigment induction (eg MITF activation) are distinct

Melatonin and Its Metabolites Protect Human Melanocytes Against UVB-Induced Damage: Involvement of NRF2-Mediated Pathways

Ultraviolet light (UV) is an inducer of reactive oxygen species (ROS) as well as 6-4-photoproducts and cyclobutane pyrimidine dimers (CPD) in the skin, which further cause damage to the skin cells. Irradiation of cultured human melanocytes with UVB stimulated ROS production, which was reduced in cells treated with melatonin or its metabolites: 6-hydroxymelatonin (6-OHM), N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), N-acetylserotonin (NAS), and 5-methoxytryptamine (5-MT). Melatonin and its derivatives also stimulated the expression of NRF2 (nuclear factor erythroid 2 [NF-E2]-related factor 2) and its target enzymes and proteins that play an important role in cell protection from different damaging factors including UVB. Silencing of NRF2 using siRNA diminished the protective effects of melatonin, while the membrane melatonin receptors (MT1 or MT2) did not change the activities of either melatonin or its derivatives. Melatonin and its metabolites enhanced the DNA repair in melanocytes exposed to UVB and stimulated expression of p53 phosphorylated at Ser-15. In conclusion, melatonin and its metabolites protect melanocytes from UVB-induced DNA damage and oxidative stress through activation of NRF2-dependent pathways; these actions are independent of an effect on the classic membrane melatonin receptors. Thus, melatonin and its derivatives can serve as excellent protectors of melanocytes against UVB-induced pathology

Protective Effects of Novel Derivatives of Vitamin D\u3csub\u3e3\u3c/sub\u3e and Lumisterol Against UVB-Induced Damage in Human Keratinocytes Involve Activation of Nrf2 and p53 Defense Mechanisms

We tested whether novel CYP11A1-derived vitamin D3- and lumisterol-hydroxyderivatives, including 1,25(OH)2D3, 20(OH)D3, 1,20(OH)2D3, 20,23(OH)2D3, 1,20,23(OH)3D3, lumisterol, 20(OH)L3, 22(OH)L3, 20,22(OH)2L3, and 24(OH)L3, can protect against UVB-induced damage in human epidermal keratinocytes. Cells were treated with above compounds for 24 h, then subjected to UVB irradiation at UVB doses of 25, 50, 75, or 200 mJ/cm2, and then examined for oxidant formation, proliferation, DNA damage, and the expression of genes at the mRNA and protein levels. Oxidant formation and proliferation were determined by the DCFA-DA and MTS assays, respectively. DNA damage was assessed using the comet assay. Expression of antioxidative genes was evaluated by real-time RT-PCR analysis. Nuclear expression of CPD, phospho-p53, and Nrf2 as well as its target proteins including HO-1, CAT, and MnSOD, were assayed by immunofluorescence and western blotting. Treatment of cells with the above compounds at concentrations of 1 or 100 nM showed a dose-dependent reduction in oxidant formation. At 100 nM they inhibited the proliferation of cultured keratinocytes. When keratinocytes were irradiated with 50–200 mJ/cm2 of UVB they also protected against DNA damage, and/or induced DNA repair by enhancing the repair of 6-4PP and attenuating CPD levels and the tail moment of comets. Treatment with test compounds increased expression of Nrf2-target genes involved in the antioxidant response including GR, HO-1, CAT, SOD1, and SOD2, with increased protein expression for HO-1, CAT, and MnSOD. The treatment also stimulated the phosphorylation of p53 at Ser-15, increased its concentration in the nucleus and enhanced Nrf2 translocation into the nucleus. In conclusion, pretreatment of keratinocytes with 1,25(OH)2D3 or CYP11A1-derived vitamin D3- or lumisterol hydroxy-derivatives, protected them against UVB-induced damage via activation of the Nrf2-dependent antioxidant response and p53-phosphorylation, as well as by the induction of the DNA repair system. Thus, the new vitamin D3 and lumisterol hydroxy-derivatives represent promising anti-photodamaging agents

Synthesis, Characterisation, and Preliminary Anti-Cancer Photodynamic Therapeutic \u3ci\u3eIn Vitro\u3c/i\u3e Studies of Mixed-Metal Binuclear Ruthenium(II)-Vanadium(IV) Complexes

We report the synthesis and characterisation of mixed-metal binuclear ruthenium(II)-vanadium(IV) complexes, which were used as potential photodynamic therapeutic agents for melanoma cell growth inhibition. The novel complexes, [Ru(pbt)2(phen2DTT)](PF6)2•1.5H2O 1 (where phen2DTT = 1,4-bis(1,10-phenanthrolin-5-ylsulfanyl)butane-2,3-diol and pbt = 2-(2\u27-pyridyl)benzothiazole) and [Ru(pbt)2(tpphz)](PF6)2•3H2O 2 (where tpphz = tetrapyrido[3,2-a:2′,3′-c:3″,2″-h:2‴,3‴-j]phenazine) were synthesised and characterised. Compound 1 was reacted with [VO(sal-L-tryp)(H2O)] (where sal-L-tryp = N-salicylidene-L-tryptophanate) to produce [Ru(pbt)2(phen2DTT)VO(sal-L-tryp)](PF6)2•5H2O 4; while [VO(sal-L-tryp)(H2O)] was reacted with compound 2 to produce [Ru(pbt)2(tpphz)VO(sal-L-tryp)](PF6)2•6H2O 3. All complexes were characterised by elemental analysis, HRMS, ESI MS, UV-visible absorption, ESR spectroscopy, and cyclic voltammetry, where appropriate. In vitro cell toxicity studies (with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay) via dark and light reaction conditions were carried out with sodium diaqua-4,4\u27,4”,4”\u27tetrasulfophthalocyaninecobaltate(II) (Na4[Co(tspc)(H2O)2]), [VO(sal-L-tryp)(phen)]•H2O, and the chloride salts of complexes 3 and 4. Such studies involved A431, human epidermoid carcinoma cells; human amelanotic malignant melanoma cells; and HFF, non-cancerous human skin fibroblast cells. Both chloride salts of complexes 3 and 4 were found to be more toxic to melanoma cells than to non-cancerous fibroblast cells, and preferentially led to apoptosis of the melanoma cells over non-cancerous skin cells. The anti-cancer property of the chloride salts of complexes 3 and 4 was further enhanced when treated cells were exposed to light, while no such effect was observed on non-cancerous skin fibroblast cells. ESR and 51V NMR spectroscopic studies were also used to assess the stability of the chloride salts of complexes 3 and 4 in aqueous media at pH 7.19. This research illustrates the potential for using mixed-metal binuclear ruthenium(II)-vanadium(IV) complexes fighting skin cancer

Effect of obesity on the population pharmacokinetics of fluconazole in critically Ill patients

Our objective was to describe the population pharmacokinetics of fluconazole in a cohort of critically ill nonobese, obese, and morbidly obese patients. Critically ill patients prescribed fluconazole were recruited into three body mass index (BMI) cohorts, nonobese (18.5 to 29.9 kg/m(2)), obese (30.0 to 39.9 kg/m(2)), and morbidly obese (>= 40 kg/m(2)). Serial fluconazole concentrations were determined using a validated chromatographic method. Population pharmacokinetic analysis and Monte Carlo dosing simulations were undertaken with Pmetrics. Twenty-one critically ill patients (11 male) were enrolled, including obese (n = 6) and morbidly obese (n = 4) patients. The patients mean +/- standard deviation (SD) age, weight, and BMI were 54 +/- 15 years, 90 +/- 24 kg, and 31 +/- 9 kg/m(2), respectively. A two-compartment linear model described the data adequately. The mean +/- SD population pharmacokinetic parameter estimates were clearance (CL) of 0.95 +/- 0.48 liter/h, volume of distribution of the central compartment (V-c) of 15.10 +/- 11.78 liter, intercompartmental clearance from the central to peripheral compartment of 5.41 +/- 2.28 liter/h, and intercompartmental clearance from the peripheral to central compartment of 2.92 +/- 4.95 liter/h. A fluconazole dose of 200 mg daily was insufficient to achieve an area under the concentration-time curve for the free, unbound drug fraction/MIC ratio of 100 for pathogens with MICs of >= 2 mg/liter in patients with BMI of >30 kg/m(2). A fluconazole loading dose of 12 mg/kg and maintenance dose of 6 mg/kg/day achieved pharmacodynamic targets for higher MICs. A weight-based loading dose of 12 mg/kg followed by a daily maintenance dose of 6 mg/kg, according to renal function, is required in critically ill patients for pathogens with a MIC of 2 mg/liter

Internal branding in universities and the lessons learnt from the past: the significance of employee brand support and transformational leadership

The paper reviews the literature on the concept of internal branding and its effects in the service sector in general, as well as in UK universities. In addition, the concept of employee brand support is reviewed, discussing the influence of leadership characteristics on internal branding in universities. Employee brand support is a crucial element to successful internal branding activities. A great concern is that the knowledge of internal branding and employee brand support in higher education institutions is based on knowledge imported from the business sector, and more practices should thus be adapted and implemented. It is found that transformation leadership, despite being little researched in the internal branding context, remains the pivotal element to the successful implementation of internal branding, as transformational leadership provides space for intellectual stimulation and consideration of individuals that are present at universities. Potential future research areas for internal branding studies are identified and discussed

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Evaluating the Effects of SARS-CoV-2 Spike Mutation D614G on Transmissibility and Pathogenicity.

Global dispersal and increasing frequency of the SARS-CoV-2 spike protein variant D614G are suggestive of a selective advantage but may also be due to a random founder effect. We investigate the hypothesis for positive selection of spike D614G in the United Kingdom using more than 25,000 whole genome SARS-CoV-2 sequences. Despite the availability of a large dataset, well represented by both spike 614 variants, not all approaches showed a conclusive signal of positive selection. Population genetic analysis indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage. We do not find any indication that patients infected with the spike 614G variant have higher COVID-19 mortality or clinical severity, but 614G is associated with higher viral load and younger age of patients. Significant differences in growth and size of 614G phylogenetic clusters indicate a need for continued study of this variant