Sodium lauryl sulfate-induced irritation in the human face: regional and age-related differences

Novel human skin surface antimicrobial peptide quantification method using a skin patch test chamber: A pilot study

INTRODUCTION

Antimicrobial peptides (AMPs) on the skin surface are related to the innate immunity of the skin in preventing external infection. Skin rinsing and tape stripping (TS) are acceptable methods for analyzing AMPs on the skin surface but have limitations, such as causing skin damage. In this study, we proposed a noninvasive method to measure AMPs on the skin surface with minimal skin damage.

METHODS

Using the patch test assay, we aimed to analyze the skin surface human β-defensin (hBDs) levels without damaging the skin barrier. The concentrations of hBDs on the skin surface were evaluated through the skin patch testing of 13 healthy subjects, and hBD-1 concentrations were compared with those obtained using the TS method in this proof-of-concept study. In addition, changes in skin physiology and concentration of hBDs under 1% sodium lauryl sulfate stimulation were monitored in 14 healthy subjects (8 young and 6 elderly subjects) for 150 h.

RESULTS

The correlation between the two methods had a Pearson's coefficient of 0.640, and skin patch analysis led to a relatively less impaired barrier with no significant increase in transepidermal water loss after analysis. Age-specific comparisons suggested that higher skin surface hBD-2 concentrations were present in the young group as compared with the elderly group. Skin surface expression of hBD-2 after skin barrier disruption was also higher in the young group.

CONCLUSION

Our findings show that skin patch analysis is a convenient method to analyze hBDs on the skin surface. hBDs are factors of innate immunity that can be used as an index to predict a decreased chemical immune response of skin due to aging.

Potential cosmeceutical lamellar liquid crystals containing black longan (Dimocarpus longan Lour.) seed extract for MMP-1 and hyaluronidase inhibition

The aims of this study were to evaluate the biological activities of black Dimocarpus longan Lour. seed extracts and develop a lamellar liquid crystal (LLC). Different solvents, including petroleum ether, ethyl acetate, and 95% v/v ethanol, were used in the maceration of black D. longan seeds. The inhibitory activities on matrix metalloproteinase-1 (MMP-1) and hyaluronidase were evaluated. The irritating potency of D. longan seed extracts was determined using the hen's egg chorioallantoic membrane test. The extract with the strongest anti-ageing activities and no irritant impact was examined for its chemical contents using high-performance liquid chromatography and incorporated into the LLC. Various factors affecting the LLC formulations, including surfactant types and amounts, thickening agent types and amounts, and various oil types, were investigated. The results demonstrated that the ethyl acetate extract (EtOAc) was the most potent inhibitor of MMP-1 (IC₅₀ = 21.7 ± 5.4 µg/mL) and hyaluronidase (oleanolic acid equivalent = 0.44 ± 0.03 g per g extract). Interestingly, its MMP-1 inhibition was equivalent to that of oleanolic acid, corilagin, and gallic acid. Furthermore, its hyaluronidase inhibition was equivalent to that of gallic acid and ellagic acid. Gallic acid, which was the most abundant compound (15.6% ± 0.06% w/w) was suggested as the compound responsible for the biological activities of EtOAc extract. Considering its potential anti-skin ageing properties with no irritation of EtOAc extract, it was incorporated into the most suitable LLC, which was composed of 5% w/w Lexfeel® D5 oil, 0.5% w/w Carbopol® U21, 2% w/w Liquid Crystal Cream Maker, and 92.5% w/w DI water. The LLC containing EtOAc extract presented birefringence under a polarizing light microscope, indicating its crystallinity. The formulation had good stability after heating-cooling cycles in terms of external appearance, crystallinity, viscosity, and pH (5.5). As a result, it is recommended as a potential cosmeceutical formulation for anti-skin wrinkling. It is proposed that more research be conducted on the safety and efficacy of the treatment on human volunteers.

General characteristics of the influence of surfactants on the bacteriolytic activity of lysozyme based on the example of enzymatic lysis of Lactobacillus plantarum cells in the presence of Tween 21 and SDS

The general characteristics of the effect of surfactants on the activity of lysozyme were demonstrated. The kinetics of bacterial cell lysis is consistent with the Michaelis-Menten equation and the presence of surfactants does not shift the pH-optimum of activity. Surfactants do not change the Km value but instead, affect the Vmax value. The experimental dependencies are well described by theoretical equations, which assume three surfactant binding sites on the lysozyme molecule. The dependencies of the activity of lysozyme on the surfactant concentration are either a step type (i.e., a higher plateau becomes a lower plateau), or a dependency with a maximum and continuation of the curve in the form of a plateau but with an increase in the surfactant concentration. It can be assumed that there is a mechanism for the regulation of lysozyme activity by an unknown natural factor that has a suitable hydrophobic radical capable of binding to the surface of lysozyme.

Genome-wide identification for genes involved in sodium dodecyl sulfate toxicity in Saccharomyces cerevisiae

Background

Sodium dodecyl sulfate (SDS) is one of the most widely used anionic alkyl sulfate surfactants. Toxicological information on SDS is accumulating, however, mechanisms of SDS toxicity regulation remain poorly understood. In this study, the relationship between the SDS-sensitive mutants and their intracellular ROS levels has been investigated.

Results

Through a genome-scale screen, we have identified 108 yeast single-gene deletion mutants that are sensitive to 0.03% SDS. These genes were predominantly related to the cellular processes of metabolism, cell cycle and DNA processing, cellular transport, transport facilities and transport routes, transcription and the protein with binding function or cofactor requirement (structural or catalytic). Measurement of the intracellular ROS (reactive oxygen species) levels of these SDS-sensitive mutants showed that about 79% of SDS-sensitive mutants accumulated significantly higher intracellular ROS levels than the wild-type cells under SDS stress. Moreover, SDS could generate oxidative damage and up-regulate several antioxidant defenses genes, and some of the SDS-sensitive genes were involved in this process.

Conclusion

This study provides insight on yeast genes involved in SDS tolerance and the elevated intracellular ROS caused by SDS stress, which is a potential way to understand the detoxification mechanisms of SDS by yeast cells.

Pollutant Absorption as a Possible End-Of-Life Solution for Polyphenolic Polymers

Tannin- and lignin-furanic foams are natural porous materials that have attracted high interest in the scientific and industrial communities for their high thermal and fire-resistant properties. However, no interesting solutions have been proposed for the management of their end-life as yet. In this study, the phenolic-furanic powders derived from the foams were analyzed for their capacity to remove different pollutants like neutral, cationic, and anionic organic molecules from wastewater. It was observed that the macromolecules produced from initially bigger fractions were more suitable to remove methylene blue and sodium dodecyl sulfate (SDS) while contained absorptions were observed for riboflavin. Acidified tannin powders were also prepared to understand the role of the flavonoid in the absorption mechanism. The latter showed outstanding absorption capacity against all of the tested pollutants, highlighting the key-role of the flavonoid fraction and suggesting the limited contribution of the furanic part. All adsorbents were investigated through FT-IR and solid state ¹³C-NMR. Finally, the powders were successfully regenerated by simple ethanol washing, showing almost complete absorption recovery.

The Scourge of the Spurge Family-An Imitator of Rhus Dermatitis

The Euphorbiaceae family (commonly known as "spurge") is a large, diverse, and widely distributed family of plants that encompass around 300 genera and more than 8000 species. Their attractiveness and hearty nature have made them popular for both indoor ornamentation and outdoor landscaping. Despite their ubiquity, the potential to cause irritant contact dermatitis (ICD) is often overlooked in favor of more notorious causes of phytodermatitis, namely, Toxicodendron species and nettles. We examined case reports spanning 40 years and discovered that spurge-induced ICD tends to befall children and middle-aged adults who unwittingly encounter the plant through play or horticulture, respectively. Clinical presentation is pleomorphic. Erythema, edema, burning, vesicles, and pruritus of acute onset and rapid resolution are frequently observed. We present a classic case of ICD in a 12-year-old girl after exposure to Euphorbia myrsinites and review the literature on phytodermatitis caused by members of the Euphorbiaceae family.

Comparison of solubilization capacity of resveratrol in sodium 3α, 12α -dihydroxy-7-oxo-5 β-cholanoate and sodium dodecyl sulfate

In this study we investigated resveratrol (trans-3,5,4'-trihydroxystilbene) solubilization with sodium 3α,12 α-dihydroxy-7-oxo-5 β-cholanoate (S7-OD) and sodium dodecyl sulfate (SDS). The investigation was aimed at determining whether large spherical micelles (SDS) or small longitudinal micelles (S7-OD) are more convenient for incorporation of resveratrol. Also, we studied resveratrol behavior in mixed micelles with mentioned surfactants using spectroflourimetric method as well as the effects of sodium chloride and urea on resveratrol solubilization capacity in the applied surfactants. Resveratrol solubilization curve was different in the investigated surfactants. Resveratrol solubilization curve for sodium 3α,12 α-dihydroxy-7-oxo-5 β-cholanoate at concentration 0.9 CMC reached saturation level of 60% dissolved resveratrol. The curve for sodium dodecyl sulfate was linear within the whole range of the investigated concentration; resveratrol solubilization rate reached 13% at 2 CMC. In S7-OD, NaCl increased capacity of resveratrol solubilization up to 1.4 CMC surfactant concentration, whilst maximum level of dissolved resveratrol (90%) was observed at 0.9 CMC. In SDS, NaCl decreased resveratrol solubilization capacity. Urea reduced resveratrol solubilization rate in sodium 3α ,12 α-dihydroxy-7-oxo-5 β-cholanoate, whereas it had inverse effect in sodium dodecyl sulfate. The obtained results strongly suggest that structure, that is, shape, of the surfactant micelles significantly affects their capacity of resveratrol solubilization. Also, presence of NaCl and urea influences solubilization capacities of investigated surfactants.

Human skin organ culture for assessment of chemically induced skin damage

The move away from animal models for skin safety testing is inevitable. It is a question of when, not if. As skin safety studies move away from traditional animal-based approaches, a number of replacement technologies are becoming available. Human skin in organ culture is one such technology. Organ-cultured skin has several features that distinguish it from other technologies. First and foremost, organ-cultured skin is real skin. Almost by definition, therefore, it approximates the intact skin better than other alternative models. Organ culture is an easy-to-use and relatively inexpensive approach to preclinical safety assessment. Although organ culture is not likely to replace high-throughput enzyme assays or monolayer culture/skin equivalent cultures for initial compound assessment, organ culture should find use when the list of compounds to be evaluated is small and when simpler models have narrowed the dose range. Organ-cultured skin also provides a platform for mechanistic studies.

Evaluation of biosurfactant obtained from Lactobacillus pentosus as foaming agent in froth flotation

This study analyzes the kinetics of sediment sorption on two chemical surfactants (Tween 20 and SDS) and a biotechnologically produced surfactant (obtained from Lactobacillus pentosus). Biosurfactants were produced by fermentation of hemicellulosic sugars from vineyard pruning waste supplied as a substrate to L. pentosus. Results obtained showed that almost no SDS was adsorbed onto the sediments, whereas Tween 20 and biosurfactants from L. pentosus were absorbed after a few minutes. Kinetic models revealed that adsorption of surfactant onto riverbed sediments is governed not only by an intra-particle diffusion model (evaluated by the Weber and Morris model), but also by surface reaction models (evaluated by first, second, third order equations and Elovich equation), showing the best fit when employing the Elovich model. The adsorption properties showed by biosurfactant from L. pentosus onto sediments present it as a potential foaming agent in froth flotation.

Partial characterization of biosurfactant from Lactobacillus pentosus and comparison with sodium dodecyl sulphate for the bioremediation of hydrocarbon contaminated soil

The capability of a cell bound biosurfactant produced by Lactobacillus pentosus, to accelerate the bioremediation of a hydrocarbon-contaminated soil, was compared with a synthetic anionic surfactant (sodium dodecyl sulphate SDS-). The biosurfactant produced by the bacteria was analyzed by Fourier transform infrared spectroscopy (FTIR) that clearly indicates the presence of OH and NH groups, C=O stretching of carbonyl groups and NH nebding (peptide linkage), as well as CH₂–CH₃ and C–O stretching, with similar FTIR spectra than other biosurfactants obtained from lactic acid bacteria. After the characterization of biosurfactant by FTIR, soil contaminated with 7,000 mg Kg⁻¹ of octane was treated with biosurfactant from L. pentosus or SDS. Treatment of soil for 15 days with the biosurfactant produced by L. pentosus led to a 65.1% reduction in the hydrocarbon concentration, whereas SDS reduced the octane concentration to 37.2% compared with a 2.2% reduction in the soil contaminated with octane in absence of biosurfactant used as control. Besides, after 30 days of incubation soil with SDS or biosurfactant gave percentages of bioremediation around 90% in both cases. Thus, it can be concluded that biosurfactant produced by L. pentosus accelerates the bioremediation of octane-contaminated soil by improving the solubilisation of octane in the water phase of soil, achieving even better results than those reached with SDS after 15-day treatment.

Dermatoprotective effects of some plant extracts (genus Ficus) against experimentally induced toxicological insults in rabbits

Aim:

Present study was conducted to evaluate the dermatoprotective effects of plant extracts ( Ficus religiosa, Ficus benghalensis, and Ficus racemosa) against known irritants such as sodium dodecyl sulfate (SDS), atrazine, and petrol.

Methods:

The study was conducted in adult male rabbits. Ethanol extracts of plants were obtained through Soxhlet. All irritants and Ficus extracts were topically applied to the backs of rabbits daily for 4 days, while pure ethanol served as control. Skin was examined after 24, 48, and 96 h for erythema. Skin biopsies were taken on 5th day for microscopic examination.

Results:

Erythema produced by irritants reduced significantly with the simultaneous application of Ficus extracts. The mean ± SEM epidermal thickness (micrometer) with SDS was 45.40 ± 1.89, F. religiosa + SDS was 18.60 ± 0.51, F. benghalensis + SDS was 18.40 ± 0.25, F. racemosa + SDS was 18.80 ± 0.37, and mixture of three Ficus species + SDS was 16.80 ± 0.37. Similar findings were revealed after using plant extracts with atrazine and petrol. The mean ± SEM epidermal layer count for SDS was 3.60 ± 0.25, atrazine was 3.40 ± 0.25, petrol was 3.40 ± 0.25, and ethanol (control) was 1.00 ± 0.20. This count reduced to 1.20 ± 0.20 for three Ficus species + SDS, 1.40 ± 0.25 for Ficus species + atrazine, and 1.40 ± 0.25 for Ficus species + petrol.

Conclusion:

Ficus species demonstrated the potential to block the dermatotoxic effects of topical irritants and could be used successfully to prevent skin toxicity.

REMOVING EXTRACTABLE PROTEINS IN NATURAL RUBBER LATEX BY CALCIUM CHLORIDE FROM CHICKEN EGGSHELLS

Controlling the level of the extractable protein contents in a natural rubber latex is important to the sensitization of natural rubber latex products users. Allergies caused by latex products cause a serious problem in which the sweat removes proteins and allowing a skin contact causing allergic reactions. Calcium oxide from calcined chicken eggshells at 900 °C for 1 h was dissolved in 2M HCl (CaCl2) and used as the thickening agent in which it can modify the protein structure. The eggshells were characterized by the particle size analysis, the impedance analysis, simultaneous thermal analysis (STA), x-ray diffraction (XRD), and Fourier transform infrared spectra (FTIR). Calcium chloride (CaCl2) interacts with the protein molecules and the solvent ions through the hydrogen bonding and the electrostatic interactions driving the extractable protein toward the film surface. Sodium dodecyl sulphate was used as the stabilizer in the natural rubber latex film formation. The extractable protein contents were measured and determined by the modified Lowry method. The concentrated latex samples were further characterized by FTIR, scanning electron microscope, and XRD and the results were reported here. Moreover, near infrared was used to measure the extractable protein spectra of the concentrated latex compounds in the region of 1100–2500 nm.

Irritant contact dermatitis: effect of age

Knowledge on age-relationship to irritant contact dermatitis (ICD) remains of interest. We searched for articles and textbooks on age-relationship to ICD and evaluated relevant data. Irritant response may be enhanced in children and decline with increasing age. In general, older skin reacts more slowly and with less intensity to irritants when compared with young skin. Such age-related changes may depend: (i) on differences in percutaneous penetration in old and young skin, and/or on (ii) differences in the microcirculatory efficiency, which serves as the route by which inflammatory cells make their way to the site of inflammation. Additionally, stratum corneum turnover time increases with age which means that an irritant remains longer on the skin; a compromised cutaneous blood vessel network with ageing may lead to a decreased inflammatory response, decreased absorption and decreased clearance. In conclusion, age-related differences of ICD are present despite some conflicting data. Investigations elucidating this interesting subject may benefit in prevention and intervention strategies.

Contact dermatitis in older adults: a review of the literature

Contact dermatitis is a significant health problem affecting the elderly. Impaired epidermal barrier function and delayed cutaneous recovery after insult enhances susceptibility to both irritants and allergens. Exposure to more numerous potential sensitizers and for greater durations influences the rate of allergic contact dermatitis in this population. Medical co-morbidities, including stasis dermatitis and venous ulcerations, further exacerbate this clinical picture. However, while these factors tend to increase the degree of sensitization in the elderly, waning immunity can actually decrease such a propensity. This interplay of both intrinsic and extrinsic factors makes a generalization on trends for contact dermatitis in older adults challenging. The literature has varying reports on the overall incidence of allergic contact dermatitis with advancing age. Nevertheless, it does clearly show that sensitivity to topical medicaments increases with age. Irritant contact dermatitis studies are more consistent, with less reactivity (to irritants) in older compared with younger skin. Diagnosis of both irritant and allergic contact dermatitis is based on a thorough history, complete skin examination, and comprehensive patch testing. The mainstay of therapy is avoidance of the offending chemical substances and the use of topical along with systemic therapies, depending on the severity of the condition.

Mapping the human face: biophysical properties

BACKGROUND

Facial skin exhibits unique biophysical properties that are distinct from skin belonging to other areas of the body. Small to large regional differences in biophysical properties between facial sites are observed. Technological advances in dermatological research allow a quantitative study of the biophysical qualities of the face and its relation to skin elsewhere. However, comprehensive studies examining inter-regional variations using each of the six standard biophysical parameters have been few. We summarize findings on the biophysical parameters used to explore the human face as well as regional differences in skin reactivity to chemical irritants.

METHODS

We performed a literature search using Pubmed, Embase, Science Citations Index, and the UCSF's dermatological library on biophysical parameters and skin physiology pertaining to the human face.

RESULTS

Distinct regional differences in transepidermal water loss (TEWL), capacitance, blood flow, sebum, pH, and temperature were demonstrated in facial skin. However, studies cannot be compared with each other because each uses different anatomical sites, skin conditions, and measurement techniques. Intraregional differences in TEWL, sebum, and temperatures were observed on the cheeks and appeared to follow characteristic distribution patterns. Higher blood flow levels and skin temperatures were generally observed in areas with dense networks of blood vessels such as the nose and perioral region. Areas such as the forehead, nose, and chin consistently showed higher sebum casual levels, but variability in sebum levels between sites was also observed. The susceptibility of the face to hexyl nicotinate, sodium lauryl sulfate, and benzoic acid differed depending on location and age.

CONCLUSION

Establishing a standardized biophysical profile of the human face will help to improve therapeutics, and further our understanding of differences in chemical reactivity and disease distribution. Future research necessitates standardization of the anatomical sites studied, sample size, and experimental protocols.

Percutaneous absorption and exposure assessment of pesticides

Dermal exposure to a diverse range of chemicals may result from various uses. In order to assess exposure and estimate potential risks, accurate quantitative data on absorption are required. Various factors will influence the final results and interpretations of studies designed to assess the ability of compounds to penetrate the skin. This overview will discuss skin penetration by pesticides, emphasizing key parameters to be considered from the perspective of exposure assessment.

Skin irritation and sensitization: mechanisms and new approaches for risk assessment. 1. Skin irritation

Cutaneous irritation presents a major health problem with serious social and occupational impact. The interaction between an irritant and the human skin depends on multiple factors: the intrinsic properties and the nature of the irritant itself, and specific individual- and environment-related variables. The main pathological mechanisms of irritancy include skin barrier disruption, induction of a cytokine cascade and involvement of the oxidative stress network; all of them resulting in a visible or subclinical inflammatory reaction. In vivo, different non-invasive parameters for the evaluation of skin irritation and irritant potential of compounds and their specific formulations have been introduced, such as epidermal barrier function, skin hydration, surface pH, lipid composition, skin colour and skin blood flow. The diverse physiological changes caused by irritating agents require implementation of a multiparametric approach in the evaluation of cutaneous irritancy.

Human skin in organ culture and human skin cells (keratinocytes and fibroblasts) in monolayer culture for assessment of chemically induced skin damage

Human skin cells (epidermal keratinocytes and dermal fibroblasts) in monolayer culture and human skin in organ culture were exposed to agents that are known to produce irritation (redness, dryness, edema and scaly crusts) when applied topically to skin. Among the agents used were three well accepted contact irritants (i.e., all-trans retinoic acid [RA], sodium lauryl sulfate [SLS] and benzalkonium chloride) as well as the corrosive organic mercury compound, aminophenyl mercuric acetate (APMA), and 5 contact sensitizers (oxazolone, nickel sulfate, eugenol, isoeugenol and ethylene glycol dimethacrylate [EGDM]). As a group, the contact irritants (including the corrosive mercuric compound) were cytotoxic for keratinocytes and fibroblasts and suppressed growth at lower concentrations than the contact sensitizers. The contact irritants also produced histological changes (hyperplasia, incomplete keratinization, loss of the granular layer, acantholysis and necrosis) in organ-cultured skin at dose levels at which the contact sensitizers appeared to be inert. Finally, the profile of secreted molecules from organ-cultured skin was different in the presence of contact irritants versus contact sensitizers. Taken together, these data suggest that the use of organ-cultured skin in conjunction with cells derived from the skin in monolayer culture may provide an initial approach to screening agents for deleterious changes in skin.

Site variations in susceptibility to SLS

According to the European Society of Contact Dermatitis (ESCD) guidelines on the sodium lauryl sulfate (SLS) exposure test 'the flexor side of forearm skin with cubital fossa and wrist excluded is the preferred study site'. In this study we analysed the exact anatomic region within the suggested test area in respect to the outcome of the SLS exposure test. 3 test areas at the volar forearm were chosen: 'distal' with a 5-cm distance to the wrist, exact 'midvolar' and 'proximal' with a 5-cm distance to the cubital fossa. 25 healthy volunteers were irritated for 24 hr with 1% SLS. Transepidermal water loss (TEWL) measurements were taken before and 1 and 24 hr after removal of Finn Chambers((R)). Median baseline TEWL showed no significant differences in the 3 test sites. However, postexposure TEWL proximal was significantly (P < 0.01) higher than midvolar and distal. The distal volar forearm showed the lowest TEWL 24 h after the irritation. The differences were in comparison to midvolar (P < 0.01) and proximal (P < 0.001) significant. The results show that it is essential to point out the exact position of the test area at the volar forearm in study reports and to randomize the irritation areas at the volar forearm if different treatments are to be compared.