MSM research for skin:
MSM improves rosacea: Combined effects of silymarin and methylsulfonylmethane in the management of rosacea: clinical and instrumental evaluation.
J Cosmet Dermatol. 2008 Mar;7(1):8-14. doi: 10.1111/j.1473-2165.2008.00355.x.
This study aims to evaluate a topical treatment based on silymarin/methylsulfonilmethane (S-MSM) to improve erythematous-telangiectactic rosacea.
Forty-six patients affected by stage I-III rosacea entered this double-blind, placebo-controlled study. Subjects were treated for 1 month. Clinical and instrumental evaluations were done at baseline, after 10 and 20 days, and at the end of the study. Itching, stinging, erythema, and papules were investigated clinically as well as hydration and erythema instrumentally with capacitance and color measurements.
A statistically significant improvement was observed in many clinical and instrumental parameters investigated (P < 0.001). In particular, improvement of skin redness, papules, itching, hydration, and skin color occurred.
The combination of silymarin and S-MSM can be useful in managing symptoms and condition of rosacea skin, especially in the rosacea subtype 1 erythemato-telangiectatic phase. The action can be considered multicentric and multiphase because of the direct modulating action on cytokines and angiokines normally involved and up-regulated in the case of such skin condition.
Clinical and instrumental evaluation of skin improvement after treatment with a new 50% pyruvic acid peel.
Dermatol Surg. 2006 Apr;32(4):526-31.
Pyruvic acid is an alpha-keto acid that presents keratolytic, antimicrobial, and sebostatic properties as well as the ability to stimulate new collagen production and elastic fibers formation. Because of its low pKa and its small dimension, it penetrates rapidly and deeply through the skin, so far as to be considered a potent chemical peel agent. It has proven its efficacy for the treatment of many dermatological conditions such as acne, superficial scarring, photodamage, and pigmentary disorders. Pyruvic acid application usually induces intense burning, and the postpeeling period is characterized by erythema, desquamation, and, sometimes, crusting.
The aim of the study is to assess the efficacy and tolerability of 50% pyruvic acid in a new non-erythematogenic formulation (pyruvic acid 50%, dimethyl isosorbide, propylene glycol, ethyl alcohol, dimethyl sulfone, ethyl lactate, water) for the treatment of photodamage, superficial scarring, and melasma.
MATERIALS AND METHODS:
Twenty subjects affected by photodamage, superficial scarring, and melasma, but otherwise healthy, entered the study. Four peeling sessions were performed once every 2 weeks. The patients were evaluated clinically and by means of several noninvasive methods in order to monitor the following parameters: hydration, color (erythema and pigmentation), elasticity, skin smoothness, skin roughness, scaliness, and wrinkles.
The patients did not report any discomfort either during the peeling session or during the postpeeling period, without any impact on their social life. We did not observe any case of persistent erythema as well as any case of postinflammatory hyperpigmentation. Instrumental evaluations showed a significant reduction in the degree of pigmentation in patients with melasma, a significant increase in skin elasticity, and an improvement of the degree of wrinkling in all the patients.
This innovative formulation of 50% pyruvic acid peel has been shown to be safe and effective to treat photodamage, melasma, and superficial scarring, allowing the patients to carry out regularly their working life as well as their social life. Furthermore, the results have been evaluated by means of noninvasive devices, which have permitted one to quantify the improvements.
PARABENS USED AS PRESERVATIVES IN COSMETICS CONTRIBUTE TO BREAST CANCER:
Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase and human exposure, and discussion of potential human health risks.
J Appl Toxicol. 2008 Jul;28(5):561-78. doi: 10.1002/jat.1358.
This toxicology update reviews research over the past four years since publication in 2004 of the first measurement of intact esters of p-hydroxybenzoic acid (parabens) in human breast cancer tissues, and the suggestion that their presence in the human body might originate from topical application of bodycare cosmetics. The presence of intact paraben esters in human body tissues has now been confirmed by independent measurements in human urine, and the ability of parabens to penetrate human skin intact without breakdown by esterases and to be absorbed systemically has been demonstrated through studies not only in vitro but also in vivo using healthy human subjects. Using a wide variety of assay systems in vitro and in vivo, the oestrogen agonist properties of parabens together with their common metabolite (p-hydroxybenzoic acid) have been extensively documented, and, in addition, the parabens have now also been shown to possess androgen antagonist activity, to act as inhibitors of sulfotransferase enzymes and to possess genotoxic activity. With the continued use of parabens in the majority of bodycare cosmetics, there is a need to carry out detailed evaluation of the potential for parabens, together with other oestrogenic and genotoxic co-formulants of bodycare cosmetics, to increase female breast cancer incidence, to interfere with male reproductive functions and to
influence development of malignant melanoma which has also recently been shown to be influenced by oestrogenic stimulation.
Significance of the detection of esters of p-hydroxybenzoic acid (parabens) in humanbreast tumours.
J Appl Toxicol. 2004 Jan-Feb;24(1):1-4.
This issue of Journal of Applied Toxicology publishes the paper Concentrations of Parabens in Human Breast Tumours by Darbre et al. (2004), which reports that esters of p-hydroxybenzoic acid (parabens) can be detected in samples of tissue from human breast tumours. Breast tumour samples were supplied from 20 patients, in collaboration with the Edinburgh Breast Unit Research Group, and analysed by high-pressure liquid chromatography and tandem mass spectrometry. The parabens are used as antimicrobial preservatives in underarm deodorants and antiperspirants and in a wide range of other consumer products. The parabens also have inherent oestrogenic and other hormone related activity (increased progesterone receptor gene expression). As oestrogen is a major aetiological factor in the growth and development of the majority of human breast cancers, it has been previously suggested by Darbre that parabens and other chemicals in underarm cosmetics may contribute to the rising incidence of breast cancer. The significance of the finding of parabens in tumour samples is discussed here in terms of 1). Darbre et al's study design, 2). what can be inferred from this type of data (and what can not, such as the cause of these tumours), 3). the toxicology of these compounds and 4). the limitations of the existing toxicology database and the need to consider data that is appropriate to human exposures.
Concentrations of parabens in human breast tumours.
J Appl Toxicol. 2004 Jan-Feb;24(1):5-13.
Parabens are used as preservatives in many thousands of cosmetic, food and pharmaceutical products to which thehuman population is exposed. Although recent reports of the oestrogenic properties of parabens have challenged current concepts of their toxicity in these consumer products, the question remains as to whether any of the parabens can accumulate intact in the body from the long-term, low-dose levels to which humans are exposed. Initial studies reported here show that parabens can be extracted from human breast tissue and detected by thin-layer chromatography. More detailed studies enabled identification and measurement of mean concentrations of individual parabens in samples of 20 human breast tumours by high-pressure liquid chromatography followed by tandem mass spectrometry. The mean concentration of parabens in these 20 human breast tumours was found to be 20.6 +/- 4.2 ng x g(-1) tissue. Comparison of individual parabens showed that methylparaben was present at the highest level (with a mean value of 12.8 +/- 2.2 ng x g(-1) tissue) and represents 62% of the total paraben recovered in the extractions. These studies demonstrate that parabens can be found intact in the human breast and this should open the way technically for more detailed information to be obtained on body burdens of parabens and in particular whether body burdens are different in cancer from those in normal tissues.
Endocrine disrupters and human health: could oestrogenic chemicals in body care cosmetics adversely affect breast cancer incidence in women?
J Appl Toxicol. 2004 May-Jun;24(3):167-76.
In the decade that has elapsed since the suggestion that exposure of the foetal/developing male to environmental oestrogens could be the cause of subsequent reproductive and developmental effects in men, there has been little definitive research to provide conclusions to the hypothesis. Issues of exposure and low potency of environmental oestrogens may have reduced concerns. However, the hypothesis that chemicals applied in body care cosmetics (including moisturizers, creams, sprays or
lotions applied to axilla or chest or breast areas) may be affecting breast cancer incidence in women presents a different case scenario, not least in the consideration of the exposure issues. The specific cosmetic type is not relevant but the chemical ingredients in the formulations and the application to the skin is important. The most common group of body care cosmetic formulation excipients, namely p-hydroxybenzoic acid esters or parabens, have been shown recently to be oestrogenic in vitro and in vivo and now have been detected inhuman breast tumour tissue, indicating absorption (route and causal associations have yet to be confirmed). The hypothesis for a link between oestrogenic ingredients in underarm and body care cosmetics and breast cancer is forwarded and reviewed here in terms of: data on exposure to body care cosmetics and parabens, including dermal absorption; paraben oestrogenicity; the role of oestrogen in breast cancer; detection of parabens in breast tumours; recent epidemiology studies of underarm cosmetics use and breast cancer; the toxicology database; the current regulatory status of parabens and regulatory toxicology data uncertainties. Notwithstanding the major public health issue of the causes of the rising incidence of breast cancer in women, this call for further research may provide the first evidence that environmental factors may be adversely affecting human health by endocrine disruption, becauseexposure to oestrogenic chemicals through application of body care products (unlike diffuse environmental chemical exposures) should be amenable to evaluation, quantification and control. The exposure issues are clear and the exposed population is large, and these factors should provide the necessary impetus to investigate this potential issue of public health.
Parabens, oestrogenicity, underarm cosmetics and breast cancer: a perspective on a hypothesis.
J Appl Toxicol. 2003 Sep-Oct;23(5):285-8.
A recent review by Darbre (2003) published in this journal (J. Appi. Toxicol. 23: 89-95) has attracted public and scientific interest that requires perspective, particularly on the use of esters of p-hydroxybenzoic acid (parabens) as preservatives in underarm cosmetics. Although parabens are generally regarded as safe, recent reports suggest
that they are oestrogenic in a variety of in vitro (including MCF7 and ZR-75-1 human breast cancer cell lines) and in vivo tests for oestrogenicity (uterotrophic assays in both rat and mouse). There are also recent reports of adverse reproductive and developmental outcomes in rodent toxicity studies. Of interest is the lack of activity by the oral route but clear activity by the subcutaneous and topical routes, which is of some relevance to the use of underarm cosmetics. There would seem to be a case now to supplement these emerging toxicity data with longer-term regulatory standard tests examining other oestrogenic endpoints and at least to consider these findings in more up-to-date risk assessments specific for cosmetic use. Further, there are few data on the use of underarm cosmetics and the risk of breast cancer, and although one recent retrospective interview-based study found no association there is a need for more thorough investigation taking into account the type of chemicals used. Darbre has forwarded a hypothesis and called for further work to establish whether or not the use of underarm cosmetics (particularly containing oestrogenic formulants) contributes to the rising incidence of breast cancer. It would seem prudent to conduct this work because the current database is sparse and the effects of long-term low-level exposures to weakly oestrogenic chemicals on humanhealth, particularly their application to the underarm and the risks of breast cancer, are unknown. The role of oestrogens in breast cancer, however, is undisputed.
Retinol lotion reduces the fine wrinkles from natural aging of skin, University of Michigan study finds.
One of the researchers is Cho with the Seoul National University in South Korea. In addition to Kang and Voorhees, authors of the study were lead author Reza Kafi, M.D.; Heh Shin Kwak, M.D.; Wendy E. Schumacher, B.S.; Soyun Cho, M.D., Ph.D.; Valerie N. Hanft, M.D.; Ted A. Hamilton, M.S.; Anya L. King, M.S.; Jacqueline D. Neal, B.S.E.; James Varani, Ph.D.; and Gary J. Fisher, Ph.D. All of the authors were at the University of Michigan Department of Dermatology when they participated in the study. Kafi and Kwak now are at Stanford Medical School, and Cho is with the Seoul National University in South Korea.
“In the past, it was everyone believed that retinoids would treat only photoaging, or damage from exposure to sun. This is the first systematic, double-blind study showing that it improves any kind of aging – photoaging as well as natural aging,” says co-author John J. Voorhees, M.D., the Duncan and Ella Poth Distinguished Professor and chair of the Department of Dermatology at the U-M Medical School. “You can rub it anywhere, and it will help to treat the signs of aging.” RETINOL (retinoids) IS THE REASON AMG EYE SERUM IS SO POPULAR.
Improvement of naturally aged skin with vitamin A (retinol).
Kafi R1, Kwak HS, Schumacher WE, Cho S, Hanft VN, Hamilton TA, King AL, Neal JD, Varani J, Fisher GJ, Voorhees JJ, Kang S.
Arch Dermatol. 2007 May;143(5):606-12.
To evaluate the effectiveness of topical retinol (vitamin A) in improving the clinical signs of naturally aged skin.
Randomized, double-blind, vehicle-controlled, left and right arm comparison study.
Academic referral center.
The study population comprised 36 elderly subjects (mean age, 87 years), residing in 2 senior citizen facilities.
Topical 0.4% retinol lotion or its vehicle was applied at each visit by study personnel to either the right or the left arm, up to 3 times a week for 24 weeks.
MAIN OUTCOME MEASURES:
Clinical assessment using a semiquantitative scale (0, none; 9, most severe) and biochemical measurements from skin biopsy specimens obtained from treated areas.
After 24 weeks, an intent-to-treat analysis using the last-observation-carried-forward method revealed that there were significant differences between retinol-treated and vehicle-treated skin for changes in fine wrinkling scores (-1.64 [95% CI, -2.06 to -1.22] vs -0.08 [95% CI, -0.17 to 0.01]; P<.001). As measured in a subgroup, retinol treatment significantly increased glycosaminoglycan expression (P = .02 [n = 6]) and procollagen I immunostaining (P = .049 [n = 4]) compared with vehicle.
Topical retinol improves fine wrinkles associated with natural aging. Significant induction of glycosaminoglycan, which is known to retain substantial water, and increased collagen production are most likely responsible for wrinkle effacement. With greater skin matrix synthesis, retinol-treated aged skin is more likely to withstand skin injury and ulcer formation along with improved appearance.
Triple nanoemulsion potentiates the effects of topical treatments with microencapsulatedretinol and modulates biological processes related to skin aging.
Afornali A1, Vecchi Rd1, Stuart RM2, Dieamant G3, Oliveira LL4, Brohem CA5, Feferman IH6, Fabrício LH7, Lorencini M8.
An Bras Dermatol. 2013 Nov-Dec;88(6):930-6. doi: 10.1590/abd1806-4841.20132208.
The sum of environmental and genetic factors affects the appearance and function of the skin as it ages. The identification of molecular changes that take place during skin aging provides biomarkers and possible targets for therapeutic intervention. Retinoic acid in different formulations has emerged as an alternative to prevent and repair age-related skin damage.
To understand the effects of different retinoid formulations on the expression of genes associated with biological processes that undergo changes during skin aging.
Ex-vivo skin samples were treated topically with different retinoid formulations. The modulation of biological processes associated with skin aging was measured by Reverse Transcription quantitative PCR (RT-qPCR).
A formulation containing microencapsulated retinol and a blend of active ingredients prepared as a triple nanoemulsion provided the best results for the modulation of biological, process-related genes that are usually affected during skin aging.
This association proved to be therapeutically more effective than tretinoin or microencapsulated retinol used singly.
N-retinoyl-D-glucosamine, a new retinoic acid agonist, mediates topical retinoid efficacy with no irritation on photoaged skin.
Kambayashi H1, Odake Y, Takada K, Funasaka Y, Ichihashi M, Kato S.
r J Dermatol. 2005 Dec;153 Suppl 2:30-6.
Chronic ultraviolet (UV) radiation from sunlight induces wrinkle formation. Retinoic acid (RA) can markedly improve wrinkles, although RA does have some side-effects, such as skin irritation. As the efficacy and cytotoxicity of RA has been traced to its free carboxylic acid, we synthesized a new molecule, N-retinoyl-D-glucosamine (GRA), in which a glucosamine has been attached to the polar end group of all-trans retinoic acid.
To analyse the effect of topical GRA in wrinkle repair and anti-irritation in photoaged mice compared with topical RA, as well as to determine retinoic acid receptor (RAR) and retinoid X receptor (RXR) transactivation activity in vitro.
Hairless mice were irradiated with 60 mJ cm-2 of UVB for 10 weeks, and then topically treated with 0.05% GRA or 0.05% RA for 8 weeks. An in vitro transcriptional assay was performed and the activity of GRA in 293 cells transfected with RAR-alpha or RXR-alpha expression plasmid and luciferase reporter plasmid then determined.
Topical GRA and RA brought about almost complete disappearance of the wrinkles caused by UVB irradiation. The two ligands promoted both a wide repair zone histologically, and the expression of type 1 collagen in the skin. In contrast, topical GRA treatment did not produce irritation such as erythema or roughness, or alteration of transepidermal water loss values, compared with RA. In the in vitro luciferase assay, GRA resulted in significant dose-dependent RAR transactivation activity in a 100 times higher concentration range than RA. GRA did not mediate RXR transactivation activity at all.
Topical GRA appears to be able to repair photoaged skin damage without any of the irritation caused by topical RA, probably via RAR transactivation activity.
Marked improvement induced in photoaged skin of hairless mouse by ER36009, a novel RARgamma-specific retinoid, but not by ER35794, an RXR-selective agonist.
Sakuta T1, Kanayama T.
Int J Dermatol. 2006 Nov;45(11):1288-95.
Photoaging (premature skin aging) results largely from repeated exposure of the skin to ultraviolet (UV) radiation from the sun. Topical all-trans retinoic acid (RA), the only agent that has been approved for the treatment of photoaging, has been shown to reverse this process. In this study, we evaluated the pharmacologic effects of novel synthetic retinoids, ER36009 and ER35794, on murine wrinkles induced by UVB. ER36009 is a specific agonist of retinoic acid receptor (RAR)gamma, the most abundant RAR subtype in the skin, while ER35794 is a potent retinoid X receptor (RXR)-selective agonist.
After a 10-week exposure to escalating doses of UVB irradiation, the animals were treated three times per week with ER36009 (0.0001%, 0.00025%, 0.0005%), ER35794 (0.025%, 0.05%, 0.1%), RA (0.05%) or acetone (control) for 3 weeks.
ER36009 exerted a dose-dependent wrinkle-effacing effect, and 0.0005% ER36009-treated skin was significantly different from the control. ER36009 also significantly and dose-dependently increased both epidermal thickness and the area of the dermal repair zone defined by newly synthesized collagen. The effect of 0.0005% ER36009 on photodamaged skin was superior to that of 0.05% RA. In contrast, ER35794 was inactive in this model, though this compound exhibited lower local toxicity than other retinoids.
These data indicate that RARgamma, but not RXR, plays an important role in the improvement of the signs of photoaging, and so a specific RARgamma agonist might be superior to an RAR pan-agonist for clinical treatment. We conclude that ER36009 is a candidate for a potent anti-skin-aging agent.
ROSEHIP SEED RESEARCH:
Composition and content of biologically active substances in rose hips
The paper studies the chemical composition of the powders obtained from the pulp with the skins and seeds of fruits of wild rose hips. Research results have shown that the main fraction of the powder is dietary fiber, powder of seeds of insoluble fiber in 1,6 and 2,3 higher than in the powder of the fruit with a thin skin and pulp, respectively. The greatest amount of carbohydrates and protein found in powders and pulp of the fruit with a thin skin, and lipids predominate in the powder from the seeds. Found that the lipid powder rosehip richest in oleic, linoleic and linolenic acids, the share of oleic acid has 6,4-19,2%, linoleic and linolenic 19,7-45,8 and 23,3-33,9% of the amount of fatty acids. Lipids powders of hips and seeds of rose have higher levels of essential linoleic acid and powder from the pulp with the skins - linolenic acid. In the study established the presence of sterols 7 fractions, the predominant of which is the beta-sitosterol. In the powder from the pulp with the skins found the greatest amount of ascorbic acid, carotenoids, and the powder of seeds - vitamin E. Carotenoids in powders are beta-carotene and lycopene.
The high content of ascorbic acid, vitamin E and carotenoids in powder from wild rose hips makes them a good source of antioxidants. Therefore, we studied the possibility of using vegetable powders obtained from hips of wild rose, to enrich biologically active substances such as vitamins C, E and carotenoids, food supply, particularly of health care use. Rosehip powder from the pulp with the skins had the highest antioxidant activity, antioxidant activity of hips powders was 74% of the activity of powder from the pulp with the skins, and the lowest antioxidant activity was observed in the powder from the wild rose seeds. That's way, based on the analysis of the chemical composition of rose hip powder found high levels they ascorbic acid, carotenoids, flavonoids, found their high antioxidant activity. It allows recommending powders produced from the hips, as a source of physiologically functional ingredients for the production of fortified food products, especially medical and prophylactic purposes. The use of such additives will fill the gap in the body of P-active substances, vitamins C and E, beta-carotene, pectin substances.
Fatty acid composition of developing sea buckthorn (Hippophae rhamnoides L.) berry and the transcriptome of the mature seed.
PLoS One. 2012;7(4):e34099. doi: 10.1371/journal.pone.0034099. Epub 2012 Apr 27.
Sea buckthorn (Hippophae rhamnoides L.) is a hardy, fruit-producing plant known historically for its medicinal and nutraceutical properties. The most recognized product of sea buckthorn is its fruit oil, composed of seed oil that is rich in essential fatty acids, linoleic (18:2 ω-6) and α-linolenic (18:3 ω-3) acids, and pulp oil that contains high levels of monounsaturated palmitoleic acid (16:1 ω-7). Sea buckthorn is fast gaining popularity as a source of functional food and nutraceuticals, but currently has few genomic resources; therefore, we explored the fatty acid composition of Canadian-grown cultivars (ssp. mongolica) and the sea buckthorn seed transcriptome using the 454 GS FLX sequencing technology.
GC-MS profiling of fatty acids in seeds and pulp of berries indicated that the seed oil contained linoleic and α-linolenic acids at 33-36% and 30-36%, respectively, while the pulp oil contained palmitoleic acid at 32-42%. 454 sequencing of sea buckthorn cDNA collections from mature seeds yielded 500,392 sequence reads, which identified 89,141 putative unigenes represented by 37,482 contigs and 51,659 singletons. Functional annotation by Gene Ontology and computational prediction of metabolic pathways indicated that primary metabolism (protein>nucleic acid>carbohydrate>lipid) and fatty acid and lipid biosynthesis pathways were highly represented categories. Sea buckthorn sequences related to fattyacid biosynthesis genes in Arabidopsis were identified, and a subset of these was examined for transcript expression at four developing stages of the berry.
This study provides the first comprehensive genomic resources represented by expressed sequences for sea buckthorn, and demonstrates that the seed oil of Canadian-grown sea buckthorn cultivars contains high levels of linoleic acid and α-linolenic acid in a close to 1:1 ratio, which is beneficial for human health. These data provide the foundation for further studies on sea buckthorn oil, the enzymes involved in its biosynthesis, and the genes involved in the general hardiness of sea buckthorn against environmental conditions.
Adv Exp Med Biol. 2014;810:429-63.
Sunscreens have become since more than 40 years the most popular means of protection against UV radiation (UVR) in Western countries. Organic and inorganic filters with different absorption spectrum exist. They filter or scatter UVR. Protection from UVB is quantified as a minimal erythema dose-based sun protection factor. UVA protection testing is less standardized: Persistent pigment darkening and critical wavelength are currently used methods. Marketing and labeling of sunscreens underlay national regulation, which explains major differences between the European and the US sunscreen market. Sunscreens are most performing in sunburn prevention. Broad-spectrum UVB and UVA protection and regular application in sufficient amounts are essential for prevention of skin cancers, UV-induced immunosuppression, and skin aging. A significant benefit from regular sunscreen use has not yet been demonstrated for primary prevention of basal cell carcinoma and melanoma. Concerning the prevention of actinic keratoses, squamous cell carcinomas, and skin aging, the effect of sunscreens is significant, but it remains incomplete.
Some organic UV filters (PABA derivatives, cinnamates, benzophenones, and octocrylene) have been described to cause photoallergy. Percutaneous absorption and endocrine disrupting activity of small-sized organic and nano-sized inorganic UV filters have been reported. On lesional skin and in pediatric settings, these products should be used with caution. Cutaneous vitamin D synthesis depending on skin-carcinogenic UVB radiation, the potential risk of vitamin D deficiency by sunscreen use has become a major subject of public health debate. Sunscreens indeed impair vitamin D synthesis if they are used in the recommended amount of 2 mg/cm2, but not in lesser thickness below 1.5 mg/cm2 that corresponds better to what users apply in real life conditions. Large molecular last generation UVB-UVA broad-spectrum sunscreens have a better benefit-risk ratio than former organic filters: They offer better protection in the UVA band, they are non toxic and non allergenic. A better outcome of sunscreen efficacy especially in primary skin cancer prevention may be achieved with these molecules.
Sun protection factors: worldwide confusion.
Br J Dermatol. 2009 Nov;161 Suppl 3:13-24. doi: 10.1111/j.1365-2133.2009.09506.x.
The Sun Protection Factor (SPF) is a very popular instrument in the marketing of sunscreens. Unfortunately it is often not understood how sunscreens work and where the limitations of the SPF are. A lot of aspects of the SPF are confusing, e.g. the race for higher and higher numbers, the effect on SPF when less sunscreen is applied and if sunscreen should be used at all because they may block the Vitamin D synthesis. All this has a negative impact on compliance by the consumer or patient who is the most important influence factor in sun protection. This paper explains how sunscreens work, how the SPF is determined and where the limitations of the current methods exist. The dynamic view of 'UV radiation applied' and the 'UV dose transmitted' through the sunscreen onto the skin as well as onto a substrate in vitro help in the understanding and are also promising approaches in the in vitro assessment. A variation of the in vitro assessment of a sunscreen is the in silico calculation based on the absorption spectrum of the UV filters and an assumption about the irregular sunscreen film on the skin. The sunscreen simulator program can be used to determine how the SPF is affected by applying smaller amounts of sunscreen. Besides the SPF, UVA protection is also discussed. The degree of UVA protection determines the quality of the overall UV protection, whereas the SPF is an indication of the quantity of protection. Furthermore other protection factors such as IPF, iSPF, RSF and p53, and the inhibition of the Vitamin D3 synthesis by sunscreens are also discussed. In conclusion it is shown that the accuracy and robustness of the SPF and other Protection Factors will improve significantly with the availability of true broad-spectrum sunscreens rather than conventional UVB-biased sunscreens, because uniform protection profiles lead to protection independent of the action spectrum of the endpoint and the UV-radiation source.
ZEATIN CYTOKININS RESEARCH:
Principal component analysis of hormone profiling data suggests an important role for cytokinins in regulating leaf growth and senescence of salinized tomato.
Plant Signal Behav. 2010 Jan;5(1):45-8.
High throughput analytical methods allow phytohormonal profiling, but the magnitude of the data generated makes it difficult to draw firm conclusions about the physiological roles of different compounds. Principal component analysis (PCA) was used as a mathematical tool to evaluate relationships between physiological and hormonal variables in two experiments with salinised tomato. When tomato plants (cv Boludo F1) were grafted onto a recombinant inbred line (RIL) population derived from a Solanum lycopersicum x S. cheesmaniae cross and grown under moderate salinity (75 mM NaCl) for 100 days under greenhouse conditions, PCA revealed an important role for leaf xylem cytokinins (CKs) in controlling leaf growth and photosystem II efficiency (Fv/Fm) and thus crop productivity under salinity. PCA analysis from a similar experiment, with ungrafted tomato grown under highly saline (100 mM NaCl) conditions, that evaluated the temporal sequence of leaf growth (as relative growth rate, LRGR) and senescence and hormone concentrations, revealed a similar influence of CKs on both processes, since Fv/Fm and LRGR were strongly loaded along the two principal components and placed in the same cluster as leaf trans-zeatin and/or related to other CK-related parameters. The conservative behaviour of the eigen vectors for Fv/Fm and the analyzed phytohormones in different compartments (xylem, leaf and root) between different experiments suggests an important role for CKs in regulating leaf senescence, while CKs and other hormones seem to regulate leaf growth under salinity.
Rejuvenation Res. 2005 Spring;8(1):46-57.
Our studies have shown that zeatin, (6-[4-hydroxy-3-methyl-but-2-enylamino]adenine), a cytokinin plant growth factor, has gerontomodulatory, youth preserving and anti-aging effects on serially passaged human adult skin fibroblasts undergoing aging in vitro. There were no immediate negative or toxic effects in terms of cell attachment, cell proliferation, cell survival, cytoskeletal organization, and cellular growth by treatment with zeatinconcentrations between 1 and 200 microM. During long-term treatment, cells could be maintained throughout their replicative lifespan in the presence of 40, 80, and 200 microM zeatin, but the optimal concentration of zeatin's anti-aging and youth preserving effects was found to be 80 microM. Life-long serial passaging of human skin fibroblasts in the presence of zeatin resulted in the prevention of cell enlargement, reduction of intracellular debris, prevention of actin polymerization, and enhancement of cellular ability to decompose hydrogen peroxide and to cope with ethanol and oxidative stresses. Most importantly, anti-aging and beneficial effects of zeatin were observed without any induction of additional cell proliferation or an increase in the maximum proliferative capacity, thus ruling out any potentially harmful and carcinogenic effects.