Search

This paper reports the results of tests performed to evaluate the effects of key parameters on the effectiveness of several wet decontamination processes for removal of 60Co, 137Cs and 241Am from pig skin. Parameters tested included decontamination reagent composition, radionuclide deposition solution composition, the time between contamination and decontamination, and skin thickness and moisture content. Gamma-spectroscopy was used to determine the percentage activity removed and to quantify radionuclide permeation. The composition of the solution used for radionuclide deposition affected radionuclide removal, especially 241Am. Radionuclide permeation showed a strong effect of skin hydration; 137Cs permeated quickly through the samples while 241Am showed no permeation. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (Au NPs) are a promising target for research due to their small size and the resulting plasmonic properties, which depend, among other things, on the chosen reducer. This is important because removing excess substrate from the reaction mixture is problematic. However, Au NPs are an excellent component of various materials, enriching them with their unique features. One example is hydrogels, which provide a good, easily modifiable base for multiple applications such as cosmetics. For this purpose, various compounds, including hyaluronic acid (HA) and its derivatives, are distinguished by their high water-binding capacity and many characteristics resulting from their natural origin in organisms, including biocompatibility, biodegradability, and tissue regeneration. In this work Au NPs were synthesized using a green chemistry method, either by using onion extract as a reductant or chemically reducing them with sodium citrate. A complete characterization of the nanoparticles was carried out using the following methods: Fourier-Transform Infrared Spectroscopy (FT-IR), Electrophoretic (ELS), and Dynamic Light Scattering (DLS) as well as Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM). Their antioxidant activity was also tested using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The results showed that the synthesized nanoparticles enrich the hydrogels with antioxidant properties and new surface properties (depending on the reducing agent, they can be more hydrophilic or hydrophobic). Preliminary observations indicated low cytotoxicity of the nanomaterials in both liquid form and as a hydrogel component, as well as their lack of penetration through pig skin. The cosmetic properties of hydrogel masks were also confirmed, such as increasing skin hydration. [ABSTRACT FROM AUTHOR]

Exposure to high acute doses of ionizing radiation (IR) can induce cutaneous radiation syndrome. Weeks after such radiation insults, keratinocyte nuclei of the epidermis exhibit persisting genomic lesions that present as focal accumulations of DNA double-strand break (DSB) damage marker proteins. Knowledge about the nanostructure of these genomic lesions is scarce. Here, we compared the chromatin nano-architecture with respect to DNA damage response (DDR) factors in persistent genomic DNA damage regions and healthy chromatin in epidermis sections of two minipigs 28 days after lumbar irradiation with ~50 Gy γ-rays, using single-molecule localization microscopy (SMLM) combined with geometric and topological mathematical analyses. SMLM analysis of fluorochrome-stained paraffin sections revealed, within keratinocyte nuclei with perisitent DNA damage, the nano-arrangements of pATM, 53BP1 and Mre11 DDR proteins in γ-H2AX-positive focal chromatin areas (termed macro-foci). It was found that persistent macro-foci contained on average ~70% of 53BP1, ~23% of MRE11 and ~25% of pATM single molecule signals of a nucleus. MRE11 and pATM fluorescent tags were organized in focal nanoclusters peaking at about 40 nm diameter, while 53BP1 tags formed nanoclusters that made up super-foci of about 300 nm in size. Relative to undamaged nuclear chromatin, the enrichment of DDR protein signal tags in γ-H2AX macro-foci was on average 8.7-fold (±3) for 53BP1, 3.4-fold (±1.3) for MRE11 and 3.6-fold (±1.8) for pATM. The persistent macro-foci of minipig epidermis displayed a ~2-fold enrichment of DDR proteins, relative to DSB foci of lymphoblastoid control cells 30 min after 0.5 Gy X-ray exposure. A lasting accumulation of damage signaling and sensing molecules such as pATM and 53BP1, as well as the DSB end-processing protein MRE11 in the persistent macro-foci suggests the presence of diverse DNA damages which pose an insurmountable problem for DSB repair. [ABSTRACT FROM AUTHOR]

Postmortem interval (PMI) estimation, a parameter critical for solving criminal cases, remains a challenge. It has been suggested that elasticity of decomposing tissue may show a relationship to PMI. We measured elasticity of excised porcine skin at regular intervals for 17 days using a novel ultrasound device. Kruskal-Wallis test followed by Dunn’s pair-wise comparison test was performed on the elastic modulus values from each time-point. We found statistically significant differences (p < 0.0001) between the elastic modulus values. Pair-wise comparison showed that tissue measured with a PMI of 1–4, 6–9, 10–14, and 16–17 days can be distinguished from each other based on elastic modulus values. An overall trend of increasing elastic modulus values with time was also observed. Histology and H&E staining of skin samples at PMI of 1, 5, 8, and 12 days showed increasingly prominent fibre bundles which may explain the observed trend. The results of our study suggest that estimation of PMI using an ultrasound device is promising and should be explored further. [ABSTRACT FROM AUTHOR]

Purpose: In wound ballistics, skin has obvious blocking effect in the biological target penetration of projectiles. An analytical description of skin mechanical properties under compression can set the basis for the numerical simulation and the evaluation of blocking effect. Methods: In this study, an improved three-parameter solid visco-elastic model was proposed to describe the skin creep phenomenon. And then combined with Maxwell and Ogden model, a new nonlinear skin constitutive model, consisting of hyper-elastic unit, creep unit and relaxation unit in parallel, was established. Here, we examine the material properties of freshly harvested porcine skin in compression at strain rates from 0.01/s to 4000/s. Results: The model is verified by comparison with the experimental results by our test and that in the literature at different strain rates. Conclusions: It shows that calculated results of the constitutive model agree well with the experiment data at extremely low to high strain rates, which is useful for the description of the heterogeneous, nonlinear viscoelastic, relaxation and creep mechanical response of skin under compression. [ABSTRACT FROM AUTHOR]

Transdermal delivery of drugs represents a non-invasive alternative treatment used not only for skin diseases. As one of the possible penetration enhancing agents, various types of nanoparticles (NPs) could be used. Silver NPs (AgNPs) could be used for some medical purposes considering their antibacterial and antiinflammatory properties. We demonstrate a novel method of quantification of permeated AgNPs, detection of AgNPs dissolving while passing the skin, and examination of interactions between skin and systems with AgNPs. Several AgNPs (exhibiting defined mean diameters of 20, 40, 60, and 100 nm) were added individually to the pure solvents commonly used in pharmaceuticals, namely ethanol, methanol, dimethyl sulfoxide, and demineralized water. AgNP dispersions in different solvents were applied to untreated samples of the skin. Attenuated total reflection technique was used for monitoring the kinetic series of infrared spectra to elucidate the time-dependent changes in the uppermost layer of the skin. The depth profiling spectra series were measured using confocal Raman microspectrometer. All recorded vibrational spectra were evaluated by multivariate statistical methods. A strong influence of AgNP size on the structural changes of the skin surface was evident. The largest changes of the skin structure were caused by the 20-nm and 40-nm AgNPs. Permeation of used AgNPs was studied on vertical Franz diffusion cells with detection of permeated AgNPs by new method based on single-particle inductively coupled plasma mass spectrometry. [ABSTRACT FROM AUTHOR]

[Display omitted] Wound healing is a natural physiological reaction to tissue injury. Hydrogels show attractive advantages in wound healing not only due to their biodegradability, biocompatibility and permeability but also because provide an excellent environment for cell migration and proliferation. The main objective of the present study was the design and characterization of a hydrogel loaded with human mesenchymal stromal cells (hMSCs) for use in would healing of superficial skin injures. Poloxamer 407® was used as biocompatible biomaterial to embed hMSCs. The developed hydrogel containing 20 % (w/w) of polymer resulted in the best formulation with respect to physical, mechanical, morphological and biological properties. Its high swelling capacity confirmed the hydrogel's capacity to absorb wounds' exudate. LIVE/DEAD® assay confirm that hMSCs remained viable for at least 48 h when loaded into the hydrogels. Adding increasing concentrations of hMSCs-loaded hydrogel to the epithelium did not affect keratinocytes' viability and healing capacity and all wound area was closed in less than one day. Our study opens opportunities to exploit poloxamer hydrogels as cell carriers for the treatment of skin superficial wound. [ABSTRACT FROM AUTHOR]

The effects of the mixture of pig skin (PS) and coconut powder (CP) on the gelling and rheological properties of composite gel prepared with squid myofibrillar protein (MP) and lard were studied. The addition of PS and CP gel had significantly improved the water-holding capacity (WHC) and gelling properties of MP-Lard composite gel. Besides, composite gels with an adequate amount of PS and CP gel had a better texture and higher whiteness. The SDS-PAGE results showed that the presence of PS and CP gel did not affect the coagulated proteins in composite gels. The three-dimensional network structures of composite gels containing PS and CP gel were more compact and homogeneous. In general, the mixture of PS and CP could enhance the gel quality of MP-Lard composite gel and it could be used as a fat substitute in surimi products. [ABSTRACT FROM AUTHOR]

The functionality and structural properties of pig skin hydrolysates with different degrees of hydrolysis (DH, 10% and 20%) and microfluidisation (120 MPa), prepared by pepsin and Alcalase® have been investigated in this study. Extensive hydrolysis can significantly improve the absolute value of the zeta potential and surface hydrophobicity. The particle distribution of hydrolysates decreased with increasing DH. The numbers of free sulfhydryl (SH) and disulfide bonds (SS) were significantly increased with increasing DH ( p < 0.05). Hydrolysates with a lower DH showed a better emulsifying property than those with a higher DH. Microfluidisation led to the transformation of structural and interfacial properties of the hydrolysates and increased the value of the zeta potential, S 0 , and gel strength. Microfluidisation results in limited breakage of chemical bonds, the number of SS and SH bonds unchanged in the treatment. These results reflect the functionality and structural properties of collagen-rich pig skin hydrolysates. [ABSTRACT FROM AUTHOR]

Skin contamination is one of the most probable risks following major nuclear or radiological incidents. However, accidents involving skin contamination with radionuclides may occur in the nuclear industry, in research laboratories and in nuclear medicine departments. This work aims to measure the penetration of the radiological contaminant Americium ( 241 Am) in fresh and frozen skin and to evaluate the distribution of the contamination in the skin. Decontamination tests were performed using water, Fuller’s earth and diethylene triamine pentaacetic acid (DTPA), which is the recommended treatment in case of skin contamination with actinides such as plutonium or americium. To assess these parameters, we used the Franz cell diffusion system with full-thickness skin obtained from pigs’ ears, representative of human skin. Solutions of 241 Am were deposited on the skin samples. The radioactivity content in each compartment and skin layers was measured after 24 h by liquid scintillation counting and alpha spectrophotometry. The Am cutaneous penetration to the receiver compartment is almost negligible in fresh and frozen skin. Multiple washings with water and DTPA recovered about 90 % of the initial activity. The rest remains fixed mainly in the stratum corneum. Traces of activity were detected within the epidermis and dermis which is fixed and not accessible to the decontamination. [ABSTRACT FROM AUTHOR]

In this work, diclofenac was encapsulated, as sodium salt, in glycerosomes containing 10, 20 or 30% of glycerol in the water phase with the aim to ameliorate its topical efficacy. Taking into account previous findings, glycerosome formulation was modified, in terms of economic suitability, using a cheap and commercially available mixture of hydrogenated soy phosphatidylcholine (P90H). P90H glycerosomes were spherical and multilamellar; photon correlation spectroscopy showed that obtained vesicles were ∼131 nm, slightly larger and more polydispersed than those made with dipalmitoylphosphatidylcholine (DPPC) but, surprisingly, they were able to ameliorate the local delivery of diclofenac, which was improved with respect to previous findings, in particular using glycerosomes containing high amount of glycerol (20 and 30%). Finally, this drug delivery system showed a high in vitro biocompatibility toward human keratinocytes. [ABSTRACT FROM AUTHOR]

Allantoin is traditionally employed in the treatment of skin ulcers and hypertrophic scars. In the present work, to improve its local deposition in the skin and deeper tissues, allantoin was incorporated in conventional liposomes and in new argan oil enriched liposomes. In both cases, obtained vesicles were unilamellar, as confirmed by cryo-TEM observation, but the addition of argan oil allowed a slight increase of the mean diameter (∼130 nm versus ∼85 nm). The formulations, especially those containing argan oil, favoured the allantoin accumulation in the skin, in particular in the dermis (∼8.7 μg/cm 2 ), and its permeation through the skin (∼33 μg/cm 2 ). The performances of vesicles as skin delivery systems were compared with those obtained by water dispersion of allantoin and the commercial gel, Sameplast ® . Moreover, in this work, for the first time, the elastic and viscous moduli of the skin were measured, underlining the different hydrating/moisturizing effects of the formulations. The application of ARG liposomes seems to provide a softening and relaxing effect on the skin, thus facilitating the drug accumulation and passage into and trough it. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the destruction of clinically-relevant bacteria within biofilms via the sustained release of the antibiotic tetracycline from zein-based electrospun polymeric fibrous matrices and to demonstrate the compatibility of such wound dressing matrices with human skin cells. Methods: Zein/PCL triple layered fibrous dressings with entrapped tetracycline were electrospun. The successful entrapment of tetracycline in these dressings was validated. The successful release of bioactive tetracycline, the destruction of preformed biofilms, and the viability of fibroblast (FEK4) cells were investigated. Results: The sustained release of tetracycline from these matrices led to the efficient destruction of preformed biofilms from Staphylococcus aureus MRSA252 in vitro, and of MRSA252 and ATCC 25923 bacteria in an ex vivo pig skin model using 1 × 1 cm square matrices containing tetracycline (30 μg). Human FEK4 cells grew normally in the presence of these matrices. Conclusions: The ability of the zein-based matrices to destroy bacteria within increasingly complex in vitro biofilm models was clearly established. An ex vivo pig skin assay showed that these matrices, with entrapped tetracycline, efficiently kill bacteria and this, combined with their compatibility with a human skin cell line suggest these matrices are well suited for applications in wound healing and infection control. [ABSTRACT FROM AUTHOR]

Background: Elderly people are often affected by age-related knee osteoarthritis (KOA). The development of sensors for measuring and diagnostic devices used in preventive healthcare of that illness therefore constitutes an urgent issue.Objective: After developing a bone joint acoustic sensor (BJAS) that receives signals of mechanical vibrations in the knee joints during bending and stretching motions, we tested it and compared responses with those of an acceleration sensor used as a reference.Methods: For six examinees in their 20 s, using an acceleration sensor as a reference for comparison with BJAS, we conducted two frequency-response tests of impact excitation and knee bending and stretching. For impact excitation tests, two transmission systems of hard materials and soft materials were applied. We examined the cross spectral density, coherence function, Fourier transform and quantified signal.Results: Although BJAS detected signals of 0.5-15.0 kHz in impact excitation tests, considerably strong damping was found for soft specimens at higher frequencies. Therefore, acceleration sensors showed superiority over BJAS for impact excitation. However, for knee bending and stretching, BJAS detected signal frequencies of 0.5-8.0 kHz for all six examinees. BJAS demonstrated marked superiority over the acceleration sensor. Furthermore, we were able to quantify the signal intensity for each frequency for comparison.Conclusions: The BJAS frequency response was superior to that of the acceleration sensor for capturing signals from knee bending and stretching. This superiority suggests its promise for application to clarify mechanical signals from knees. [ABSTRACT FROM AUTHOR]

The aim of this work was to formulate Santolina insularis essential oil-loaded nanocarriers, namely Penetration Enhancer containing Vesicles (PEVs), evaluate the physico-chemical features and stability, and gain insights into their ability to deliver the oil to the skin. S. insularis essential oil was obtained by steam distillation, and was predominantly composed of terpenes, the most abundant being β-phellandrene (22.6%), myrcene (11.4%) and curcumenes (12.1%). Vesicles were prepared using phosphatidylcholine, and ethylene or propylene glycol were added to the water phase (10% (v/v)) to improve vesicle performances as delivery systems. Vesicles were deeply characterized by light scattering, cryogenic transmission electron microscopy and small/wide-angle X-ray scattering, the results showing polyhedral, faceted, unilamellar vesicles of ∼115 nm in size. The presence of the glycols improved vesicle stability under accelerated ageing conditions, without changes in size or migration phenomena (e.g. sedimentation and creaming). Confocal laser scanning microscopy images of pig skin treated with S. insularis formulations displayed a penetration ability of PEVs greater than that of control liposomes. Moreover, all formulations showed a marked in vitro biocompatibility in human keratinocytes. These findings suggest that the nanoformulation may be of value in enhancing the delivery of S. insularis essential oil to the skin, where it can exert its biological activities. [ABSTRACT FROM AUTHOR]

Purpose: Solid-lipid microparticles loaded with high amounts of the sunscreen UV filter benzophenone-3 were prepared by spray congealing with the objective of decreasing its skin penetration and evaluate whether the sunscreen's photoprotection were impaired by the microencapsulation process. Methods: The microparticles were produced using the natural lipids carnauba wax or bees wax and three different concentrations of benzophenone-3 (30, 50 and 70%) using spray congealing technique. Results: The microparticles presented properties suitable for topical application, such as spherical morphology, high encapsulation efficiency (95.53-102.2%), average particle sizes between 28.5 and 60.0 µm with polydispersivities from 1.2 to 2.5. In studies of in vitro skin penetration and preliminary stability, formulations of gel cream containing carnauba wax solid lipid microparticles and 70% benzophenone-3 when compared to the formulation added of bees wax solid-lipid microparticles containing 70% benzophenone-3, was stable considering the several parameters evaluated and were able to decrease the penetration of the UV filter into pig skin. Moreover, the formulations containing solid lipid microparticles with 70% benzophenone-3 increased the photoprotective capacity of benzophenone-3 under UV irradiation. Conclusion: The results show that spray-congealed microparticles are interesting solid forms to decrease the penetration solar filters in the skin without compromising their photoprotection. [ABSTRACT FROM AUTHOR]

Abstract: Several topical products contain nanometric TiO2 (nano-TiO2), which is a useful and safe component that absorbs UV light and does not cross skin barrier. However, nano-TiO2 may impregnate the first layer of the skin (stratum corneum, SC) and generate free radicals, even under low UV irradiation. These properties, largely dependent on TiO2 surface chemistry, may modulate the transdermal drug permeation. To investigate how TiO2 surface properties affect drug permeation, amphotericin in two different media, in the presence of three differently coated samples, was applied on skin and the flux measured. The naked, but not the coated, nano-TiO2 showed enhancer property, with a fourfold increase of the drug flux. Only the positively-charged, naked TiO2 strongly adhered to and altered the SC structure. The oxidative potential towards formate anion and linoleic acid was assessed and a molecular mechanism to elucidate increased skin permeability proposed. To enhance the drug permeation, both a surface charge-driven adhesion and an oxidative disorganization of the SC lipids are required. By modulating TiO2 surface charge (coating) and its oxidative potential (crystalline phase), the enhancer effect of nano-TiO2 may be tuned and turned up or down when transdermal penetration of drug has to be favored or impaired. [Copyright &y& Elsevier]

The skin is a metabolically active organ expressing biotransformation enzymes able to metabolize both endogenous molecules and xenobiotics. We investigated the impact of metabolism on the delivery of testosterone through the skin with an ex vivo pig ear skin system as an alternative model for human skin. Penetration, absorption and metabolic capabilities were investigated up to 72 h after application of [14C]-testosterone doses of 50-800 nmol on either fresh or frozen skin, with the latter model being metabolically inactive. Testosterone absorption and metabolite production were monitored by radio-HPLC and gas chromatography-mass spectrometry. Testosterone absorption through frozen skin was much lower, irrespective of the dose of testosterone applied, compared to fresh skin. Using fresh skin samples, >95% of the radioactivity recovered in culture media, as well as the skin itself, corresponded to metabolites. These results were compared with the metabolic data obtained from other in vitro systems (liver and skin microsomes). The present work leads to the conclusion that most of the enzymatic activities expressed in liver fractions are also expressed in pig and human skin. The metabolic activity of the skin can modulate the biological activity of pharmaceuticals (and xenobiotics). Consequently, it can also greatly affect transdermal drug delivery. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: This research studies the effects of external parameters on the friction of porcine skin. A tribometer was used to evaluate the frictional behavior of the same. The effects of DI water and body oil on porcine skin against steel and glass balls were evaluated in terms of coefficient of friction (COF). The COF dropped rapidly when DI water/body oil was introduced into the sliding system and remained stable when the volume of the liquid exceeded a certain value. The COF increased with increasing sliding speed under dry conditions and decreased in wet. Under an increasing normal force, the COF decreased regardless of the presence of liquid. The ratio of the real contact area to the nominal contact area of the skin with the steel/glass ball was found to increase with a power law as the applied force was increased. These results reveal basic tribological properties of the skin in contact with a hard slider. These properties could be used as reference for the design and development of artificial skin in prosthetic applications. [Copyright &y& Elsevier]

Abstract: It is of interest to develop a synthetic skin that can be used for research and assessment of tribological properties of hair and skin care products. In this paper, a systematic study is carried out of the surface, nanomechanical and nanotribological properties of two synthetic skins with and without skin cream treatment using a scanning electron microscope (SEM), a nanoindenter and an atomic force microscope (AFM). The hardness, elastic modulus, surface roughness, contact angle, coefficient of friction, adhesive force, and film thickness of the two synthetic skins are compared with that of virgin and damaged rat and pig skin. The data of the two synthetic skins are comparable to the rat and pig skin, which shows that the two synthetic skins are good simulations of animal skins for tribological study. [Copyright &y& Elsevier]

Abstract: Pig skin and wheat fiber mixture (PSFM) were assessed as fat replacers in frankfurter-type sausages. The addition of PSFM increased the moisture and protein content in the sausage because of the water binding capacity in wheat fiber and protein content in pig skin. The sausage sample containing 20% PSFM had 50% less fat, 32% fewer calories, and showed 39.5% less cooking loss than those of the control (p <0.05). High PSFM content resulted in more stable meat emulsions and increased hardness, cohesiveness, gumminess, and chewiness. No significant differences were observed in color, flavor, tenderness, juiciness, warm-off flavor, and overall acceptability between the control and sausage sample with PSFM by the sensory panel. Therefore, PSFM could be used as fat replacers to obtain lower calories, and higher moisture, protein contents, and emulsion stability than in low-fat frankfurter-type sausages without PSFM. [Copyright &y& Elsevier]

Abstract: The percutaneous absorption of tritiated water (3H2O) through sulfur mustard (SM) exposed abdominal pig skin was measured using in vitro Franz-type static diffusion cells. The barrier function to water permeation following exposure to liquid SM for 8min and excision 3h later did not change significantly. A small, but statistically significant difference (P <0.05) in steady state penetration (Jss), permeability coefficient (Kp) and lag time (t L) of 3H2O was observed between fresh skin and skin stored frozen (−20°C) for up to two weeks. Steady-state penetration and Kp values were significantly higher (P <0.05) in skin stored frozen compared with fresh skin. Fresh naïve skin had an average Kp of 1.65×10−3 cmh−1, whereas frozen naïve skin was 2.04×10−3 cmh−1. Fresh SM exposed skin had a mean Kp of 1.72×10−3 cmh−1, whereas frozen SM exposed skin was 2.31×10−3 cmh−1. Lag times were also shorter (P <0.05) in skin that had been stored frozen. Frozen, SM-exposed porcine abdominal skin may be used for in vitro penetration studies, but effects of treatment and storage on the barrier layer should be taken into account. [Copyright &y& Elsevier]

Pig skin has been studied as administration site of drug for its systemic effects, since systemic therapeutic agents can be delivered for long time with a controlled ratio, escaping from the first pass effect by liver through the transdermal delivery, which can decrease the drug dose. The low permeability of drug molecules through stratum corneum(SC) has been the limiting factor for developing transdermal delivery system of therapeutic agents. The aim of the present work is to study the enhancement of drug absorption by the skin using stimulating alternating current (AC).In our study stimulated voltage over range 6.5 V to 200 V had been used to enhancement the absorption of methylene blue (MB) with pig's skin. Our results showed that the highest MB concentration in tissue was (0.239± 0.011) mg/g and lowest ohmic resistances (kΩ/cm) (3.15±0.223) for skin were obtained after skin stimulation with 12.5 V; these results had been confirmed using histochemistry study. Dielectric properties of skin in the range of 10 Hz- 100 KHz revealed change in the dielectric dispersion curves immediately after skin stimulation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the percutaneous permeation of topical hydroxy-(29 H,31 H-phthalocyaninato)aluminum (PcAlOH) on pig ear skin employing photoacoustic (PA) measurements. The PcAlOH was incorporated in an emulsion with assessed stability parameters of pH and short- and long-term stability tests. Pig skin was prepared through a heat separation technique, and the outer skin of the cartilage was removed with a scalpel. Skin samples were then cut and treated with sodium bromide 2 mol . L for 6 h at 37 °C. The epidermis layer was washed with purified water, dried, and stored under reduced pressure until use. The skin permeation kinetics were determined by PA measurements as a function of time, performed with an open PA cell developed at Universidade do Vale do Paraíba. Short- and long-term stability tests showed no phase separation. A significant difference was found between the typical times for percutaneous permeation of the emulsion base and the emulsion + PcAlOH. The study showed two absorption transients due to the physical diffusion of molecules in the skin sample. The first is attributed to the penetration of molecules that promptly passed through the lipid barrier, while the second is related to the molecules that had greater difficulty of passing through. This slower component in the absorption curves is attributed to the penetration of PcAlOH, a planar molecule whose percutaneous penetration is more difficult. The study indicates that the formulations containing PcAlOH have stable characteristics and show promising results in absorption into the skin. The presence of the photosensitive agent in the formulation contributed significantly to the larger time constant observed. PA measurements allowed the evaluation of the penetration kinetics of PcAlOH in pig ear skin; the methodology employed may be used in the determination of the percutaneous permeation of phthalocyanines in further studies. [ABSTRACT FROM AUTHOR]

Misuse of various chemicals, such as chemical warfare agents, industrial chemicals or pesticides during warfare or terrorists attacks requires adequate protection. Thus, development and evaluation of novel decontamination dispositives and techniques are needed. In this study, in vitro permeation and decontamination of a potentially hazardous compound paraoxon, an active metabolite of organophosphorus pesticide parathion, was investigated. Skin permeation and decontamination experiments were carried out in modified Franz diffusion cells. Pig skin was used as a human skin model. Commercially produced detergent-based washing solutions FloraFree™ and ArgosTM were used as decontamination means. The experiments were done under 'warm', 'cold', 'dry' and 'wet' skin conditions in order to determine an effect of various physical conditions on skin permeation of paraoxon and on a subsequent decontamination process. There was no significant difference in skin permeation of paraoxon under warm, cold and dry conditions, whereas wet conditions provided significantly higher permeation rates. In the selected conditions, decontamination treatments performed 1 h after a skin exposure did not decrease the agent volume that permeated through the skin. An exception were wet skin conditions with non-significant decontamination efficacy 18 and 28% for the FloraFree™ and Argos™ treatment, respectively. In contrast, the skin permeation of paraoxon under warm, cold and dry conditions increased up to 60-290% following decontamination compared to non-decontaminated controls. This has previously been described as a skin wash-in effect. [ABSTRACT FROM AUTHOR]

Abstract: Deformable liposomes have been developed and evaluated as a novel topical and transdermal delivery system. Their mechanism of drug transport into and through the skin has been investigated but remains a much debated question. The present study concerns ex vivo diffusion experiments using pig ear skin in order to explain the penetration mechanism of classical and deformable liposomes. Classical and deformable vesicles containing betamethasone in the aqueous compartment through the use of cyclodextrin inclusion complexes were compared to vesicles encapsulating betamethasone in their lipid bilayer. Deformable liposomes contained sodium deoxycholate as the edge activator. Liposomes were characterised by their diameter, encapsulation efficiency, deformability, stability (in terms of change in diameter) and release of encapsulated drug. Ex vivo diffusion studies using Franz diffusion cells were performed. Confocal microscopy was performed to visualise the penetration of fluorescently labelled liposomes into the skin. This study showed that liposomes do not stay intact when they penetrate the deepest layers of the skin. Betamethasone is released from the vesicles after which free drug molecules can diffuse through the stratum corneum and partition into the viable skin tissue. [Copyright &y& Elsevier]

Abstract: The photodegradation of flumethasone (FM) and fluocinolone acetonide (FC) was studied in solution and in the pig skin. Both glucocorticosteroids applied to the pig skin were unstable under UVB light. The photoproducts formed in the skin were the lumi-, photolumi- and andro-derivatives for FM, the same found in vitro. Instead, FC hydroperoxide formed in solution was not found in the skin: the reactivity and oxidative ability of this photoproduct towards biological substrates (lipids, proteins) seems the reason of the lack of its detection in the ex vivo model. In fact, it demonstrated to quickly oxidize amino acids and peptides, and to react with BSA both in the dark and under irradiation. Moreover, the presence in the irradiated pig skin of the FC andro-derivative, which usually forms in H-donating environment, seems consistent with the mechanism of Norrish I fragmentation followed by H-abstraction, likely from the surrounding biological substrates. These findings indicate that photoreactivity of these compounds may take place in the skin of patients exposing themselves to sunlight and is a warning about possible skin damage as a result of that. Furthermore, photolability of these drugs in the skin might cause loss of their therapeutic activity. [Copyright &y& Elsevier]

Abstract: Biotransformation of chemicals by the skin is a critical determinant of systemic exposure in humans following dermal absorption. Pig ear skin potentially represents a valuable alternative model since it closely resembles to human skin. We developed an ex vivo pig ear skin system which absorption, diffusion and metabolic capabilities were investigated using benzo(a)pyrene [B(a)P] as a model molecule. The potential of the ex vivo pig ear skin model to biotransform xenobiotics was compared with metabolic data obtained using dermal and hepatic microsomes from human and pig. 14C-B(a)P [50–800nmol] was applied on the surface of skin models. The diffusion and the production of B(a)P metabolites were quantified by radio-HPLC, LC–MS/MS and NMR. B(a)P was extensively metabolized by pig ear skin explants, the major metabolites being B(a)P-glucuronide and sulfate conjugates. B(a)P-OHs, B(a)P-diols, B(a)P-catechols and B(a)P-diones were also identified. In the pig ear skin model developed, skin diffusion was maintained over 72h and both phase I and phase II activities were expressed, with the formation of similar metabolites as produced in incubations with liver and skin microsomal fractions. This ex vivo model, which combines a functional skin barrier and active biotransformation capabilities, appears to represent a valuable alternative tool in transdermal exposure studies. [ABSTRACT FROM AUTHOR]

Abstract: The biotransformation of chemicals by the skin can be a critical determinant of systemic exposure in humans following dermal absorption. Pig ear skin, which closely resembles human skin, is a candidate ex vivo alternative model for the investigation of xenobiotics penetration and metabolism. We developed an ex vivo pig ear skin model and explored its absorption, diffusion and metabolic capabilities using the model compound 14C-ethoxycoumarin (7-EC). Experimentations were undertaken on pig ear skin explants after application of various 14C-EC doses. Diffusion was quantified as well as the production of 7-EC metabolites resulting from phases I and II enzyme activities, using radio-HPLC. After 48h, most of the radioactivity was absorbed and was recovered in culture media (70%) or in the skin itself (10%). 7-EC metabolites were identified as 7-hydroxycoumarin (OH–C) and the corresponding sulfate (S–O–C) and glucuronide (G–O–C) conjugates. Their formation followed Michaelis–Menten kinetics with saturation reached around 100μM of 7-EC. Results demonstrate that dermal absorption as well as phases I and II enzymatic activities of pig skin are both functional. This model should represent a valuable alternative for the study of the transdermal exposure to chemicals, combining a functional dermal barrier and active biotransformation capabilities. [Copyright &y& Elsevier]

Abstract: The stability of the synthetic glucocorticosteroid betamethasone under UVB light was studied both in vitro (water and methanol solution and in topical and injectable commercial formulations) and ex vivo (pig skin). From irradiated methanol solutions three main photoproducts were isolated by HPLC and TLC and characterized by NMR/MS analyses. The modifications involve parts of the molecule peculiar for the therapeutic activity, that is, rearrangement of ring A (“lumi”- and “photolumiderivatives”), and Norrish Type I fragmentation of the ketolic chain (“androderivative”). Two clinically used esters of betamethasone were also studied, namely the 17-valerate and 21-phosphate, and their photoproducts identified. The HPLC method developed for the photolysis studies in solution was also applied to the analysis of commercial formulations. In a cream and a solution for parenteral use, betamethasone highly decomposed under UVB irradiation, even in the presence of the bactericidal agents chlorocresol and phenol, which are able to absorb part of the incoming radiation. As a model for the UV exposed skin to which the drug is applied, ex vivo pig skin was used; not only the yield of photodegradation was evaluated, but the photoproducts were also identified. A test on THP-1 cells demonstrated the loss of anti-inflammatory activity of betamethasone, when modified by UVB light. [Copyright &y& Elsevier]

Abstract: Against highly toxic chemicals that are quickly absorbed in the skin, topical formulations could adequately complement specific protective suits and equipments. In this work, we evaluated in vitro and compared the skin protection efficacy against the nerve agent VX of four different topical formulations: oil-in-water and water-in-oil emulsions, a perfluorinated-based cream and a hydrogel. Semi-permeable silicone membrane, pig-ear and human abdominal split-thickness skin samples mounted in diffusion cells were compared as in vitro permeation tests. The results showed that silicone membrane could be used instead of skin samples to screen for potentially effective formulations. However, the results indicated that due to potentially significant interactions between formulations and skin, relevant ranking of formulations according to their protective efficacy could require tests with skin samples. The main phase of emulsions, water or oil, was not found to be critical for skin protective efficacy against VX. Instead, specific film-forming ingredients such as perfluorinated-based polymers and silicones could significantly affect the skin protective efficacy of formulations. We showed that a hydrogel containing specific hydrophilic polymers was by far the most effective of the formulations evaluated against VX skin permeation in vitro. [Copyright &y& Elsevier]

Abstract: Prevention of exposure to the neurotoxic organophosphorus compounds (OP) is a major concern both for pesticide users and soldiers. Skin barrier creams are being developed to complement or replace uncomfortable chemical protective suits. Quick evaluation of formulations efficacy mainly relies on in vitro tests which lead to consistent, complementary and relevant results. The objectives of this work were to determine the consistency of results from in vitro tests and importance of the formulation composition in the skin protective efficacy. The efficacy of three formulations, i.e. oil-in-water and water-in-oil emulsions and perfluorinated compounds-based cream, was evaluated against the OP paraoxon in vitro. Our results indicated that the least effective formulations could be quickly identified by performing in vitro permeation tests with silicone membrane and by evaluating interfacial interactions between formulations and OP. Among the tested formulations, the perfluorinated compounds-based cream could have a broader spectrum of efficacy than emulsions against OP and other toxic chemicals. [Copyright &y& Elsevier]

Abstract: In this work we have characterized the architecture and physical properties of pig skin epidermis including its permeability to different liposome formulations. Autofluorescence images show that cells in the epidermis, from the basal layer to the stratum corneum, are organized in clusters that are in turn separated by particular structures we named “canyons”. These canyons start in the surface as a wrinkle, eventually closing and going all the way inside the epidermis as a distinct structure that reaches the stratum basale. This structure, described previously in the epidermis of mouse skin as “intercluster pathway”, was suggested to be filled with an unknown material and offer low resistance to vesicle penetration. Analysis of LAURDAN Generalized Polarization images of pig skin show that the canyons are filled with a non-polar poorly hydrated material, similar to that observed in pig skin stratum corneum. These results together with the data obtained from skin autofluorescence images suggest that these canyons are invaginations/extension of SC material. Fluorescently labeled lipids incorporated into very flexible liposomes are able to penetrate into the skin, eventually reaching the basal layer and the dermis plane. The presence of charged lipids in the liposomes enhances size stability and thus the efficiency of penetration. [Copyright &y& Elsevier]

Abstract: The influence of liposome composition, size, lamellarity and charge on the (trans)dermal delivery of tretinoin (TRA) was studied. For this purpose we studied both multilamellar (MLV) or unilamellar (UV) liposomes. Positively or negatively charged liposomes were obtained using either hydrogenated (Phospholipon®90H) or non-hydrogenated soy phosphatidylcholine (Phospholipon®90) and cholesterol, in combination with stearylamine or dicetylphosphate. Liposomal formulations were characterized by transmission electron microscopy (TEM) and optical and light polarized microscopy for vesicle formation and morphology, and by dynamic laser light scattering for size distribution. In order to obtain more information about the stability and the thermodynamic activity of the liposomal tretinoin, TRA diffusion through a lipophilic membrane was investigated. The effect of the vesicular incorporation of tretinoin on its accumulation into the newborn pig skin was also studied. The experiments were performed in vitro using Franz cells in occlusive conditions and were compared to three different controls. The tretinoin amount delivered through and accumulated in the several skin layers was detected by HPLC. Furthermore, TEM in combination with osmium tetroxide was used to visualize the skin structure after the liposomal administration. Overall obtained results showed that liposomes may be an interesting carrier for tretinoin in skin disease treatment, when appropriate formulations are used. In particular, negatively charged liposomes strongly improved newborn pig skin hydration and TRA retention, though no evidence of intact vesicle penetration was found. [Copyright &y& Elsevier]

We evaluated the potential of human organotypic skin explant cultures (hOSECs) for screening skin irritants. Test chemicals were applied to the epidermis of the skin explants which were incubated for 4, 24 or 48 h in tissue culture medium. A decrease in epidermal RNA staining, visualised in frozen sections using a modified methyl-green pyronine (MGP) staining procedure, was used as a marker of irritancy. A decrease in epidermal RNA after a 4-, 24- or 48-h exposure to a certain concentration of a test chemical equated to a MGP score of 3, 2 or 1, respectively. The MGP score was 0 if there was no keratinocyte cytotoxicity after a 48-h exposure. A minimum of three donors were used per chemical and the average MGP score was used to classify the chemical as irritant or not. Chemicals with an average MGP score &ges;1.5 were classified as irritants (R38), at that concentration. Chemicals with a MGP score <1.5 were not classified (NC), at that concentration. The results obtained using human skin in vitro were compared with published data obtained using cultured porcine skin, the cutaneous Draize test (from this point referred to as the “rabbit skin irritation test”) and volunteer studies. There was an excellent correlation between the classification of a chemical, as R38 or NC, based on hOSEC and results of volunteer studies. The hOSEC model predicted perfectly the irritation hazard of the 22 chemicals for which volunteer data were available. The porcine OSEC correctly predicted the classification of 21 of 22 (95%) chemicals and the rabbit skin irritation test correctly predicted the classification of 14 of 15 chemicals (93%) for which data were available. In conclusion, MGP staining of human skin explant cultures can be used to predicted human skin irritancy in vivo. In addition, the data validate the use of porcine skin as an alternative to human skin for screening for dermal irritants in vitro. [ABSTRACT FROM AUTHOR]

A procedure for the extraction of protein and production of peptides by enzymic hydrolysis from bone and skin wastes containing collagen was developed. Fat and inorganic components were first removed in a pretreatment step and a high molecular weight protein extracted under acidic conditions (pH 3) using a 1 h reaction time at 60 °C. The molecular weight of extract from pig skin was greater than 100 kDa. The extract had a high water retention capacity, was beneficial for repair of rough skin, had no odor problem and was demonstrated to be safe in skin patch tests. It was thus considered acceptable for use in cosmetic materials. Pretreated fish bone and pig skin were hydrolyzed with a commercial enzyme. The hydrolysates had a high anti-radical activity (IPOX50, 0.18 and 0.45 mg ml−1) and a high potential for decreasing blood pressure (IC50, 0.16 and 0.41 mg ml−1), suggesting the hydrolysates could be a useful additive in food materials. [Copyright &y& Elsevier]

Pure phenol is colorless and used in the manufacture of phenolic resins, plastics, explosives, fertilizers, paints, rubber, textiles, adhesives, pharmaceuticals, paper, soap, and wood preservatives. The purpose of this study was to compare the efficacy of several phenol decontamination strategies following dermal exposure using the pig as a model for human exposure, and then assess the effect of the two best treatments on phenol absorption in the isolated perfused porcine skin flap (IPPSF). Six anesthetized Yorkshire pigs were exposed to 89% aqueous phenol for 1 min using Hilltop chambers (10 skin sites/pig; 400 μl/site). Exposure to phenol was followed by one of 10 different decontamination procedures: 1-, 5-, 15-, and 30-min water wash; Ivory[sup ®] soap solution; polyethylene glycol (PEG 400); PEG 400/industrial methylated spirits (IMS); PEG 400/ethanol (EtOH); polyvinyl pyrrolidone (PVP)/70% isopropanol (IPA); and 70% IPA. For each of the last five strategies, 1-min treatment washes were repeatedly alternated with 1-min water washes for a total of 15 min. Evaluation was based on scoring of erythema, edema, and histological parameters such as intracellular and intercellular epidermal edema, papillary dermal edema, perivascular infiltrates, pyknotic stratum basale cells, and epidermal–dermal separation. It was concluded that PEG 400 and 70% IPA were superior to the other treatments investigated and equally efficacious in the reduction of phenol-induced skin damage. In addition, phenol absorption was assessed utilizing the two most effective in vivo treatments in the IPPSF. The assessment of percutaneous absorption of phenol found the PEG 400, 70% IPA, and 15-min water treatments significantly (P <0.05) reduced phenol absorption relative to no treatment. [ABSTRACT FROM AUTHOR]

Absorption through the skin of topically applied chemicals is relevant for both formulation development and safety assessment, especially in the early stages of development. However, the supply of human skin is limited, and the traditional in vitro methods are of low throughput. As an alternative, an artificial membrane-based Skin Parallel Artificial Membrane Permeability Assay (Skin-PAMPA) has been developed to mimic the permeability through the stratum corneum. In this study, this assay was used to measure the permeability of a model compound, 4-phenylethyl-resorcinol (PER), dissolved in 13 different solvents that are commonly used in cosmetic formulation development. The study was performed at concentrations close to the saturated solution of PER in each solvent to investigate the maximum thermodynamic potential of the solvents. The permeability of PER in selected solvents was also measured on ex vivo pig skin for comparison. Pig ear skin is an accepted alternative model of human skin. The permeability coefficient, which is independent of the concentration of the applied solution, showed a good correlation (R2 = 0.844) between the Skin-PAMPA and the pig skin permeation data. Our results support the use of the Skin-PAMPA to screen the suitability of different solvents for non-polar compounds at an early stage of formulation development. [ABSTRACT FROM AUTHOR]

Transdermal drug delivery of lidocaine is a good choice for local anesthetic delivery. Microemulsions have shown great effectiveness for the transdermal transport of lidocaine. Oil-in-water nanoemulsions are particularly suitable for encapsulation of lipophilic molecules because of their ability to form stable and transparent delivery systems with good skin permeation. However, fabrication of nanoemulsions containing lidocaine to provide an extended local anesthetic effect is challenging. Hence, the aim of this study was to address this issue by employing alginate-based o/w nanocarriers using nanoemulsion template that is prepared by combined approaches of ultrasound and phase inversion temperature (PIT). In this study, the influence of system composition such as oil type, oil and surfactant concentration on the particle size, in vitro release and skin permeation of lidocaine nanoemulsions was investigated. Structural characterization of lidocaine nanoemulsions as a function of water dilution was done using DSC. Nanoemulsions with small droplet diameters (d < 150 nm) were obtained as demonstrated by dynamic light scattering (DLS) and cryo-TEM. These nanoemulsions were also able to release 90% of their content within 24-h through PDMS and pig skin and able to the drug release over a 48-h. This extended-release profile is highly favorable in transdermal drug delivery and shows the great potential of this nanoemulsion as delivery system. [ABSTRACT FROM AUTHOR]