High Protection Factor Research Articles

Treatment of patients with chemotherapy-induced PPE using a prevention ointment containing high concentrations of antioxidants.

e19558 Background: The palmar-plantar erythrodysesthesia syndrome (PPE) is a cutaneous side effect often observed in patients under chemotherapy, e.g., with pegylated liposomal doxorubicin. This side effect entails a reduction in the antioxidative potential of the skin due to intensive radical formation. Recently, it was demonstrated that topical treatment of patients with an ointment containing high concentrations of antioxidants is an efficient prevention strategy against PPE when applied before the beginning of chemotherapy. In a 5-year observation period at the Department of Dermatology of the Charité we selected patients, who had developed a PPE during treatment with a variety of chemotherapeutics. The aim of the present study was to investigate whether the antioxidant containing ointment is also suited to treat PPE, which occurred during treatment of 13 types of cancer with chemotherapeutics besides doxorubicin. Methods: In 5 years, 68 patients having developed PPE during treatment with 12 different chemotherapeutics, including pegylated liposomal doxorubicin, capecitabin and sorafenib applied an ointment containing antioxidants with a high radical protection factor (RPF). 46 patients exhibited PPE grade III and 22 patients PPE grade II. All patients were treated with the antioxidant-containing ointment, which was applied at least twice daily in the palmar and plantar regions. Results: Treatment with the antioxidant-containing ointment resulted in a distinct regression or disappearance of PPE. After 4 weeks of treatment the PPE grade III originally diagnosed in 46 patients had reduced to grade II in 6 and to grade I in 33 patients. In 7 patients the PPE had completely disappeared. The PPE grade II diagnosed in 22 patients had alleviated to grade I in 7, and completely disappeared in 15 patients. Conclusions: Obviously, cutaneous side effects entailing radical formation processes are also induced by other types of chemotherapeutics. An antioxidant containing ointment with high RPF is not only suited to prevent PPE in patients under doxorubicin therapy, but is also effective in treating PPE caused by other chemotherapeutics.

Evaluation of antioxidant activity of carotenoid extract from shrimp processing byproducts by in vitro assays and in membrane model system

Abstract Carotenoid extracts from shrimp processing discards were evaluated for antioxidant activity. Crude extract and fractions rich in astaxanthin showed strong antioxidant activity as indicated by radical scavenging, reducing activity and metal chelating activity, comparable to that of the known antioxidants α-tocopherol and TBHQ. Singlet oxygen quenching activity of crude extract and its fractions was higher than that of α-tocopherol. Nitric oxide scavenging activity was also higher than α-tocopherol. The ability of the astaxanthin-rich fraction to inhibit the thermal oxidation of phospholipid liposomes, with a protection factor of 22.6 ± 1.7 units, was better than that of α-tocopherol (8.5 ± 1.5 units). The higher antioxidant activity of the astaxanthin-rich fraction was also indicated by a higher protection factor (14.1 ± 3.2 units) compared to α-tocopherol (6.2 ± 0.1 units) against singlet oxygen mediated oxidation of liposomes. The results indicate the potential of shrimp carotenoid extract as a natural antioxidant for possible use in food and biomedical applications.

15NH/D-SOLEXSY experiment for accurate measurement of amide solvent exchange rates: application to denatured drkN SH3

Amide solvent exchange rates are regarded as a valuable source of information on structure/dynamics of unfolded (disordered) proteins. Proton-based saturation transfer experiments, normally used to measure solvent exchange, are known to meet some serious difficulties. The problems mainly arise from the need to (1) manipulate water magnetization and (2) discriminate between multiple magnetization transfer pathways that occur within the proton pool. Some of these issues are specific to unfolded proteins. For example, the compensation scheme used to cancel the Overhauser effect in the popular CLEANEX experiment is not designed for use with unfolded proteins. In this report we describe an alternative experimental strategy, where amide (15)N is used as a probe of solvent exchange. The experiment is performed in 50% H(2)O-50% D(2)O solvent and is based on the (HACACO)NH pulse sequence. The resulting spectral map is fully equivalent to the conventional HSQC. To fulfill its purpose, the experiment monitors the conversion of deuterated species, (15)N(D), into protonated species, (15)N(H), as effected by the solvent exchange. Conceptually, this experiment is similar to EXSY which prompted the name of (15)N(H/D)-SOLEXSY (SOLvent EXchange SpectroscopY). Of note, our experimental scheme, which relies on nitrogen rather than proton to monitor solvent exchange, is free of the complications described above. The developed pulse sequence was used to measure solvent exchange rates in the chemically denatured state of the drkN SH3 domain. The results were found to correlate well with the CLEANEX-PM data, r = 0.97, thus providing a measure of validation for both techniques. When the experimentally measured exchange rates are converted into protection factors, most of the values fall in the range 0.5-2, consistent with random-coil behavior. However, elevated values, ca. 5, are obtained for residues R38 and A39, as well as the side-chain indole of W36. This is surprising, given that high protection factors imply hydrogen bonding or hydrophobic burial not expected to occur in a chemically denatured state of a protein. We, therefore, hypothesized that elevated protection factors are an artefact arising from the calculation of the reference (random-coil) exchange rates. To confirm this hypothesis, we prepared samples of several short peptides derived from the sequence of the drkN SH3 domain; these samples were used to directly measure the reference exchange rates. The revised protection factors obtained in this manner proved to be close to 1.0. These results also have implications for the more compact unfolded state of drkN SH3, which appears to be fully permeable to water as well, with no manifestations of hydrophobic burial.

Nano-cotton Fabrics with High Ultraviolet Protection

Ultraviolet resistant cotton fabrics were developed by coating with ZnO and TiO2 nanoparticles. The ZnO nanoparticles applied on cotton yarns were found to withstand the knitting operation. Meanwhile, the TiO 2 nanoparticles applied on the bleached as well as reactive dyed cotton fabrics by the sol-gel and linking agent methods were found to be intact after various cycles of domestic washing. Knitted fabrics containing ZnO nanoparticles showed moderate to high ultraviolet protection factor (UPF) values, whereas 50+ UPF values were measured for the TiO2-coated samples. Further it was found that the rutile phase was better than anatase phase in blocking UV rays. The developed process can be easily adapted to the existing textile machinery, making it industrially viable.

Computer-delivered, parent-involvement intervention to prevent substance use among adolescent girls

Objective To test a computer-delivered program for preventing substance use among adolescent girls. Methods Randomly, 916 girls aged 12.76 ± 1.0 years and their mothers were assigned to an intervention arm or to a test-only control arm. Intervention-arm dyads engaged in exercises to improve the mother–daughter relationship, build girls' substance use prevention skills, and reduce associated risk factors. Study outcomes were girls' and mothers' substance use and mediator variables related to girls' substance use risk and protective factors. The study was conducted between September 2006 and February 2009 with participants from greater New York City, including southern Connecticut and eastern New Jersey. Results At 2-year follow-up and relative to control-arm girls, intervention-arm girls reported lower relevant risk factors and higher protective factors as well as less past 30-day use of alcohol ( p < 0.006), marijuana ( p < 0.016), illicit prescription drugs ( p < 0.03), and inhalants ( p < 0.024). Intervention-arm mothers showed more positive 2-year outcomes than control-arm mothers on variables linked with reduced risks of substance use among their daughters, and mothers reported lower rates of weekly alcohol consumption ( p < 0.0001). Conclusions A computer-delivered prevention program for adolescent girls and their mothers was effective in changing girls' risk and protective factors and girls' and mothers' substance use behavior.

Influence of Microparticles on the Homogeneity of Distribution of Topically Applied Substances

The uppermost layer of the skin – the stratum corneum – represents a barrier of the human organism to the environment. It prevents the penetration of substances coming into contact with the skin into the human body. In cases of strong exposure, the skin has to be protected additionally by barrier creams. In the present study, the influence of microparticles on the homogeneity of distribution of the protection cream on the skin was investigated by laser scanning microscopy. The protection cream contained antioxidant substances with a high radical protection factor for the prevention of palmar-plantar erythema often occurring during chemotherapy with doxorubicin. In this case, the chemotherapeutic substance comes out with the sweat onto the skin surface, from which it penetrates into the skin like topically applied. It was found that particles increase the homogeneity of distribution and, thus, the protection efficacy is significantly increased. The obtained results are important, not only for the prevention of side effects during chemotherapy, but also for the development and application of sunscreens and all types of topically applied drugs and cosmetics, which should form an efficient protection film on the skin.

Hydrogen−Deuterium Exchange in Free and Prodomain-Complexed Subtilisin

Residue-specific exchange rates of 223 amide protons in free and prodomain-complexed subtilisin were determined in order to understand how the prodomain binding affects the energetics of subtilisin folding. In free subtilisin, amide protons can be categorized according to exchange rate: 74 fast exchangers (rates > or = 1 h(-1)); 52 medium exchangers (rates between 1 h(-1) and 1 day(-1)); 31 slow exchangers (rates between 1 day(-1) and 0.001 day(-1)). The remaining 66 amide proteins did not exchange detectibly over 9 months (k(obs) < year(-1)) and were denoted as core protons. Core residues occur throughout the main structural elements of subtilisin. Prodomain binding results in high protection factors (100-1000) in the central beta-sheet, particularly in the vicinity of beta-strands S5, S6, and S7 and the connecting loops between them. These connecting loops provide the ligands to the cation at metal site B. Overall, prodomain binding seems to facilitate the organization of the entire central beta-sheet and alpha-helix C in the left-handed crossover connection between beta-strands two and three. It also appears to facilitate the isomerization of multiple prolines late in folding, allowing the formation of metal site B. The gain of stability region around site B comes at the cost of stability in regions more distal to prodomain binding: the C-terminal alpha-helix H and the N-terminal alpha-helices A and B. The acceleration of exchange in these regions by prodomain binding reveals an antagonism between the folding intermediate and the full native structure. This antagonism helps to explain why the prodomain is needed to stabilize the folding intermediate as well as why the unfolding of free subtilisin seldom occurs via this intermediate.

Social influences and self‐efficacy as predictors of youth smoking initiation and cessation: a 3‐year longitudinal study of vocational high school students in Taiwan

This 3-year longitudinal study examined changes in patterns of risk factors and protective factors of smoking initiation and cessation among vocational high school students in Taipei, Taiwan. In 2000, a total of 2151 10th grade students from 16 vocational high schools were assessed and followed up in the 11th and 12th grades. Self-administered questionnaires were collected in each year to assess the pattern of changes in smoking behaviors, and risk and protective factors. Of the 1654 non-smokers in the 10th grade, 227 students initiated smoking by the 12th grade. Higher risk factors such as peer smoking, peers offering cigarettes, alcohol use and lower protective factors, such as refusal self-efficacy, antismoking attitude and belief in the 10th grade predicted youth initiation by grade 12. Increases in risk factors and decreases in protective factors during the years from 10th to 12th grades were associated significantly with youth smoking initiation. Of the 494 smokers in the 10th grade, 76 students quit smoking by the 12th grade. Lower risk factors and higher protective factors in 10th grade smokers predict youth smoking cessation by grade 12. Decreases in risk factors and increases in protective factors were associated significantly with youth smoking cessation. The risk factors (i.e. social influences) and protective factors (i.e. self-efficacy) examined in this study predict both youth smoking initiation and youth smoking cessation.

In vivo persistent pigment darkening method: a demonstration of the reproducibility of the UVA protection factors results at several testing laboratories

The aims of the present studies were to check that persistent pigment darkening (PPD) method can produce accurate and reproducible results for high UVA protection factors (UVAPF) and to provide data on the variability between laboratories and on the influence of skin types. The Japanese Cosmetic Industry Association (JCIA) PPD method was used to determine the UVAPF in different laboratories of different sunscreen formulations with increasing UVAPF. Two formulations were tested at seven independent laboratories and five products within two laboratories. The influence of skin types on the UVAPF of two products was tested within one laboratory on two panels of volunteers. All laboratories complied with the JCIA method specifications. Reproducible results have been obtained between the different labs and a low and satisfactory variability was achieved with a panel size of 10 subjects. Furthermore, skin type was demonstrated to have no influence within the defined selection criteria. From this multiple center testing, the PPD method has been shown to be appropriate for testing sunscreen formulations with UVAPFs above 20. It is reasonable to expect that test results will be consistent if an identical protocol is used between laboratories.

Modulation of ultraviolet (UV) transmission by emollients: relevance to narrowband UVB phototherapy and psoralen plus UVA photochemotherapy

Patients with psoriasis undergoing or about to undergo ultraviolet (UV) phototherapy and photochemotherapy often have thick scale on their plaques which can prevent the penetration of UV radiation. Emollients are used to moisturize the skin and to prevent or reduce some of the milder side-effects ('dryness', itching) sometimes experienced during UV therapy. However, emollients can alter the UV transmission of skin and thus may alter the clinical effects of phototherapy and photochemotherapy. We tested 30 of the topical emollients in the British National Formulary (BNF) using a standard in vitro technique used to test sunscreens. We also surveyed U.K. phototherapy units to establish routine practice for emollient use in phototherapy and photochemotherapy. We used a standard in vitro technique to measure the monochromatic protection factors (MPFs) of 30 non-bath emollients from the BNF. An application rate of 2 mg cm-2 was used. For the assessment of effects during narrowband UVB (TL-01) phototherapy, the mean of the protection factors at 310 and 315 nm was calculated; for psoralen plus UVA photochemotherapy the mean UVA protection factor was used. A questionnaire survey was used to assess routine practice concerning emollient use prior to phototherapies in phototherapy units throughout the U.K. In the UVA range, 17 of the 30 emollients gave protection factors of 1.2 or above. In the UVB range, 23 of 30 had an MPF of 1.2 or above. Yellow soft paraffin had the highest protection factor in the UVB range. Of 78 centres surveyed, 57 returned completed questionnaires (73%). Seventeen of 57 (30%) centres routinely used emollients immediately prior to administering phototherapy treatments. The remaining 40 of 57 (70%) did not. Forty-five (79%) responding centres recommended the use of emollients after phototherapy. This study has revealed considerable variability in the practice of emollient use before phototherapy treatments. Although the majority of centres included in this study did not routinely use emollients, almost one third did. Our in vitro measurement of 30 emollients revealed marked variation in UV transmission, with many emollients blocking sufficient UV to affect the response to therapy.

Rue(Ruta graveolens L.) 추출물의 Helicobacter pylori에 대한 항균활성과 생리활성효과

Water and ethanol extracts from Rue were prepared, and their growth inhibiting activity against Helicobacter pylori and other biological activities were examined. Total phenolic compounds in the water and ethanol extracts were present at the concentration of 16.39 mg/g, and 17.07 mg/g, respectively. At the concentration of of phenolic compounds concentration, water extract produced 12 mm inhibition zone while ethanol extract produced 13 mm. The ABTS [2,2`-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] radical decolorization and antioxidant protection factor (PF) were determined for extracts from Rue. Water extracts showed inhibition rate on ABTS, but ethanol extracts showed higher PF (1.2) than water extracts (0.8). Water extracts had higher electron donation ability on DPPH than ethanol extracts. But ethanol extracts had higher ACE (angiotensin converting enzyme) and xanthine oxidase inhibitory activities than water extracts. Rosemarinic acid and quercetin were the most abundant phenolic compounds as analyzed by HPLC.

Native-like β-hairpin retained in the cold-denatured state of bovine β-lactoglobulin

Bovine β-lactoglobulin is denatured by increased temperature (heat denaturation) and by decreased temperature (cold-denaturation) in the presence of 4 M urea at pH 2.5. We characterized the structure of the cold-denatured state of β-lactoglobulin using circular dichroism (CD), small-angle X-ray scattering (SAXS) and heteronuclear nuclear magnetic resonance (NMR). CD and SAXS indicated that the cold-denatured state, in comparison with the highly denatured state induced by urea, is rather compact, retaining some secondary structure, but no tertiary structure. The location of the residual structures in the cold-denatured state and their stability were characterized by 1H/ 2H exchange combined with heteronuclear NMR. The results indicated that the residues adjacent to the disulfide bond (C106-C119) connecting β-strands G and H had markedly high protection factors, suggesting the presence of a native-like β-hairpin stabilized by the disulfide bond. Since this β-hairpin is conserved between different conformational states, including the kinetic refolding intermediate, it should be of paramount importance for the folding and stability of β-lactoglobulin. On the other hand, the non-native α-helix suggested for the folding intermediate was not detected in the cold-denatured state. The 1H/ 2H exchange experiments showed that the protection factors of a mixture of the native and cold-denatured states is strongly biased by that of the labile cold-denatured state, consistent with a two-process model of the exchange.

Antioxidant activity of sage extracts in rapeseed oil irradiated with UV-rays.

The antioxidant activities of sage acetone oleoresin and its methanol-water fractions were tested in rapeseed oil at 0.1% concentrations and 80 degrees C temperature after irradiation with UV-rays (exposition 0.5 h). It was determined that even little doses of UV irradiation induce oxidation process in rapeseed oil samples both with additives and without them. The antioxidant activity of a synthetic antioxidant BHT was much lower than that of the sage fractions at 80 degrees C and forced air oven conditions. This finding proves the advantage of sage extracts in comparison with BHT at high temperatures. It was also found that methanol-water fraction separated from acetone oleoresin had the highest antioxidant activity in terms of the formation of primary and secondary oxidation products. Oil sample with this additive had the highest protection factor (PF = 4.53) when the oil was not irradiated with UV rays. The data obtained showed that all sage extracts had very strong antioxidant activity (PF > 3).

Sunscreens and cutaneous malignant melanoma: an Italian case-control study.

The possible relation between use of sunscreens and the risk of cutaneous malignant melanoma (CMM) was investigated in a case-control study conducted in 27 Italian centres on 542 incident, histologically confirmed cases and 538 controls admitted for acute, other than neoplastic or dermatologic conditions. Compared with subjects reporting never sunscreen use, the multivariate odds ratios (OR), after allowance for age, sex, geographic area, education, skin, eye and hair colour, freckles, number of naevi, history of sunburns, tanning pattern and duration of sunny vacations, were 0.97 (95% confidence interval [CI] 0.69 to 1.35) for those reporting "sometimes" and 0.80 (95% CI 0.54 to 1.17) for those reporting "often " sunscreen use. With reference to type of product most frequently used, the ORs were 0.96 (95% CI 0.52 to 1.77) for minimal, 0.90 (95% CI 0.63 to 1.28) for moderate and 1.41 (95% CI 0.85 to 2. 35) for high sunburn protection factor. With reference to duration of use, the OR was 0.86 (95% CI 0.58 to 1.29) for use started since >/=20 years. None of the corresponding trends in risks were significant. The ORs for sunscreen use were similar across strata of major identified covariates and, if anything, tended to decline after multivariate analysis. The present findings confirm that sunscreen use, as currently adopted in Italy, is not appreciably related to subsequent CMM risk.

State of the art sunscreens for prevention of photodermatoses

The prevention of photodermatoses implies that the exposure to ultraviolet (UV) light of photosensitive patients is reduced to levels below the threshold of induction of light reactions. The four principal measures of prevention are the following: “ avoidance of sun exposure around midday; “ UV-protective clothes; “ hats; “ use of sunscreen products. Protection of photosensitive patients by sunscreen products play an important role. This is particularly true for the prevention of photodermatoses, which are elicited by UVA. About 50% of the exposure to UVA occurs in the shade, i.e. in the absence of direct sunlight. The amount of UVA in sunlight is high from sunrise to sunset, whereas the intensity of UVB peaks more sharply at midday. Whereas window and car glass materials offer an effective shield against UVB, they are transparent for UVA. Moreover, due to the presence of subclinical and/or apparent eczema in already affected skin areas, the natural protective capacity of the horny layer may be reduced or lost, which will further increase the light sensitivity of the afflicted skin. Which are the ideal properties of state-of-theart sun protection products? Such compounds should be: (i) well tolerated; (ii) cosmetically pleasant; (iii) non-toxic; (iv) equally effective against UVA and UVB; (v) photostable; (vi) water resistant; (vii) with a high ‘Sun Protection Factor’. These criteria should be briefly commented on (adverse properties listed under (i)–(iii) are exclusion criteria). (i) Good tolerance is of primary importance, since such products are often applied under stress conditions to sensitive skin. Skin tolerance requires careful testing and optimisation, since preparations with high protection factors contain relatively large amounts of UV filter substances (see later). Many promising filter substances are rejected at an early stage of development due to their irritant, photoirritant or photoallergic potential. * Corresponding author. Tel.: +33-1-47567701; fax: +331-47567630.

Effects of organic solvents on protein structures: observation of a structured helical core in hen egg-white lysozyme in aqueous dimethylsulfoxide.

A partly folded state of hen egg-white lysozyme has been characterized in 50% DMSO. Low concentrations of DMSO (< 10%) have little effect on the overall folded conformation of lysozyme as seen from 1H NMR chemical shift dispersion. At increasing DMSO concentrations (> 10%) a cooperative transition of the structure to a new, partially folded state is observed. This transition is essentially complete by approximately 50% DMSO. NMR studies show an overall decrease in chemical shift dispersion with marked broadening of many resonances. A substantial number of backbone and side chain-side chain NOEs suggests the presence of secondary and tertiary interactions in the intermediate state. Tertiary organization of the aromatic residues is also demonstrated by enhanced near-UV circular dichroism and limited exposure of tryptophans as monitored by iodide quenching of fluorescence. The intermediate state exhibits enhanced binding to hydrophobic dyes. Further, the structural transition from this state to a largely unfolded conformation is cooperative. H/D exchange rates of several amide protons and four indole protons of tryptophans (W28, W108, W111, and W123), measured by refolding from 50% DMSO at different time intervals reveal that protection factors are high for the helical domain, whereas NH groups in the triple stranded antiparallel beta-sheet domain are largely solvent-exposed. An ordered hydrophobic core in the intermediate state comprising of helix A, helix B, and helix D is consistent with the high protection factors observed. The structured intermediate in 50% DMSO resembles the early kinetic intermediate observed in the refolding of hen egg white lysozyme, as well as a molten globule state of equine lysozyme at low pH. The results demonstrate the potential use of non-aqueous structure perturbing solvents like DMSO to stabilize partially folded conformations of proteins.

NMR Study of Rapidly Exchanging Backbone Amide Protons in Staphylococcal Nuclease and the Correlation with Structural and Dynamic Properties

Exchange rates of rapidly exchanging (>1.0 s-1) backbone amide protons with solvent water in staphylococcal nuclease (SN) were measured at pH 6.03−7.03 with a 2D heteronuclear water exchange filter sequence (WEX II-FHSQC). Comparison of the exchange data with crystal structure data reveals the following: (1) Non-hydrogen-bonding and exposed residues have protection factors (predicted exchange rate in random coil/measured exchange rate) of less than 15 for non-hydrophobic residues and 10 or higher for hydrophobic residues. Among non-hydrophobic residues, Gly tends to have a higher protection factor (10−15), whereas other residues are below 10. (2) Protection factors for buried and non-hydrogen-bonded protons vary over a wide range (6−104). Low protection factors (<25) may indicate fluctuations in structure resulting in substantial solvent exposure. (3) Some hydrogen-bonded and buried protons show rapid exchange, and the protection factors are 25−400. This indicates kinetically labile hydrogen bonds and so...

Measurement of water–amide proton exchange rates in the denatured state of staphylococcal nuclease by a magnetization transfer technique

The rates of hydrogen exchange were measured in a "physiological" denatured state of staphylococcal nuclease using a NMR magnetization transfer experiment suitable for the measurement of exchange rates faster than 0.5 s-1. The results are compared with predicted exchange rates (kex) for the random coil state (Bai et al., Proteins 17:75-86, 1993). No protection factors (= predicted rate/measured rate) larger than 2.4 were observed, consistent with other NMR data which strongly suggest only small amounts of residual secondary structure in this denatured state. Systematically low protection factors (0.51 +/- 0.23) were found for Asp and Glu residues, while high protection factors were observed for Gly (1.60 +/- 0.60). We conclude that the predicted exchange rates (kex) may have an uncertainty of 2- to 3-fold. Thus, for denatured proteins only protection factors with a value of 5 or larger can be assigned structural significance. These results also demonstrate that multidimensional magnetization transfer NMR techniques are powerful tools in this research field due to its ability to measure rapidly exchanging protons (> 05 s-1) with high accuracy.

Phenolic Compounds in Virgin Olive Oils: Fractionation by Solid Phase Extraction and Antioxidant Activity Assessment

The polar fraction of virgin olive oil was separated into two main parts (A and B) using solid phase extraction. Analysis of individual components by RP-HPLC indicated that the part (A) contained only simple phenols and phenolic acids. Part (B) had a complex nature. The two parts tested for their antioxidant activity showed relatively high protection factors in safflower oil stored at 80°C. Part B was found to contribute more than part A to the stability of the oil. The antioxidant activity of both fractions was related to their content of total polyphenols and o-diphenols. Acidic and alkaline hydrolysis showed significant quantitative changes in the HPLC profiles indicating the presence of ether and ester bonds while high-performance anion exchange chromatography of sugars after hydrolysis gave evidence for the presence of only traces of glycosides. A first attempt to identify a characteristic chromatographic peak of part B by HPLC fractionation and mass spectrometry showed the presence of an ester of tyrosol most probably with a dicarboxylic acid. © 1997 SCI.

Melanoma and sunscreen use

Experiments in rodents and humans have shown the ability of sunscreens to prevent UVB-induced skin cancers. Sunscreen use has thus become part of the panoply for melanoma prevention. However, results from epidemiological investigations indicate that sunscreen use could be a risk rather than a protective factor for melanoma. This article discusses possible explanations for discrepancies between experimental and observational results, suggesting that experiments did not reproduce usual human behaviours towards the sunlight. Also, marketing of sunscreens fosters unconsidered exposure to sunlight through associating sunscreen use to the acquisition of a 'safe suntan', or to the possibility to let children go naked into the sunlight without incurring sunburns. It has therefore been hypothesized that, because it prevents sunburn, sunscreen use allows prolonged exposure to sunlight. If this hypothesis holds, modern sunscreens with high protection factor could also represent a threat if their use is motivated by the desire of unrestricted exposure to sunlight. To explore this hypothesis, the design of a retrospective cohort study is presented, including children 5-7 years old, with the total body naevi count as principal endpoint. This study will have the opportunity to examine the qualities of modern sunscreens among young children.