Pretreatment Of Skin Research Articles

The effects of chemical and physical penetration enhancers on the percutaneous permeation of lidocaine through equine skin.

BackgroundThe effect of physical and chemical permeation enhancers on in vitro transdermal permeation of lidocaine was investigated in the horse.Therefore, the effect of six vehicles (phosphate-buffered saline (PBS), 50% ethanol, 50% propylene glycol, 50% isopropylalcohol, 50% isopropylalcohol/isopropylmyristate and 50% dimethylsulfoxide) was examined as well as the effect of microneedle pretreatment with different needle lengths on transdermal drug delivery of lidocaine.The skin was obtained from the thorax of six Warmblood horses and was stored up to two weeks at - 20°C. Franz-type diffusion cells were used to study the transdermal permeation through split skin (600 μm thickness). The amount of lidocaine in the receptor fluid was determined by UV–VIS high-performance liquid chromatography.ResultsAll investigated vehicle supplementations diminished the transdermal flux of lidocaine through equine skin in comparison to pure PBS except dimethylsulfoxide, which resulted in comparable permeation rates to PBS. The maximum flux (Jmax) was 1.6-1.8 fold lower for lidocaine applied in 50% ethanol, propylene glycol, isopropylalcohol and isopropylalcohol/isopropylmyristate. A significant higher Jmax of lidocaine was observed when lidocaine was applied in PBS onto microneedle pretreated skin with similar permeation rates in both needle lengths. After 6 hours, 1.7 fold higher recovery rates were observed in the microneedle pretreated skin samples than in the untreated control samples. The lagtimes were reduced to 20–50% in the microneedle pretreated skin samples.ConclusionMicroneedles represent a promising tool for transdermal lidocaine application in the horse with a rapid systemic bioavailability.

Sulforaphane and phenylethyl isothiocyanate protect human skin against UVR-induced oxidative stress and apoptosis: Role of Nrf2-dependent gene expression and antioxidant enzymes

Chronic UVR-exposure may impair the stress response and antioxidant defense mechanisms of human skin. The transcription factor nuclear factor erythroid-2 related factor 2 (Nrf2) orchestrates the expression of genes coding for the stress response and antioxidant proteins. Here, we tested sulforaphane (SFN) and phenylethyl isothiocyanate (PEITC) for their ability to counteract UVR-induced oxidative stress and apoptosis in ex vivo human full-thickness skin combined with in vitro HaCaT keratinocytes. Investigation of Nrf2 transactivation and induction of genes coding for Nrf2-dependent phase II antioxidative enzymes (γ-glutamylcysteine-synthetase (γGCS), heme oxygenase 1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1)) was performed in HaCaT keratinocytes. Comparative investigations in human ex vivo skin were conducted for analysis of gene expression of above mentioned phase II enzymes and catalase (CAT) as well as hematoxylin/eosin (H&E) and immunofluorescence (catalase, cleaved Casp-3). UVR exposure of human skin (300mJ/cm2) resulted in a significant time-dependent increase of the number of sunburn cells and caspase-3 activation as biomarkers of apoptosis for up to 48h (p<0.001) and induced a significant decrease of the antioxidant enzyme catalase (p<0.001). This was significantly counteracted by the pre-treatment of human skin with SFN and PEITC (5μM and 10μM). Mechanistic cell culture studies revealed SFN and PEITC to increase Nrf2 activity and Nrf2-dependent gene expression (γGCS, HO-1, NQO1); this was paralleled in human full skin mRNA. In conclusion, the induction of Nrf2-dependent antioxidant pathways seems to be a potential mechanism by which SFN and PEITC protect against UVR-induced oxidative stress and apoptosis in human skin.

Percutaneous absorption of salicylic Acid after administration of trolamine salicylate cream in rats with transcutol(®) and eucalyptus oil pre-treated skin.

This study was conducted to assess the effect of skin pre-treatment with Transcutol(®) and eucalyptus oil on systemic absorption of topical trolamine salicylate in rat. Pharmacokinetic parameters of salicylic acid following administration of trolamine salicylate on rat skin pre-treated with either Transcutol(®) or eucalyptus oil were determined using both non-compartmental and non-linear mixed effect modeling approaches and compared with those of control group. Median (% of interquartile range/median) of salicylic acid AUC0-8hr (ng/mL/hr) values in Transcutol(®) or eucalyptus oil treated rats were 2522(139%) and 58976(141%), respectively as compared to the 3023(327%) of the control group. Skin pre-treatment with eucalyptus oil could significantly decrease extravascular volume of distribution (V/F) and elimination rate constant (k) of salicylic acid. Unlike Transcutol(®), eucalyptus oil lead to enhanced transdermal absorption of trolamine salicylate through rat skin.

Thymoquinone inhibits phorbol ester-induced activation of NF-κB and expression of COX-2, and induces expression of cytoprotective enzymes in mouse skin in vivo

Thymoquinone (TQ), the active ingredient of Nigella sativa, has been reported to possess anti-inflammatory and chemopreventive properties. The present study was aimed at elucidating the molecular mechanisms of anti-inflammatory and antioxidative activities of thymoquinone in mouse skin. Pretreatment of female HR-1 hairless mouse skin with TQ attenuated 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced expression of cyclooxygenase-2 (COX-2). TQ diminished nuclear translocation and the DNA binding of nuclear factor-kappaB (NF-κB) via the blockade of phosphorylation and subsequent degradation of IκBα in TPA-treated mouse skin. Pretreatment with TQ attenuated the phosphorylation of Akt, c-Jun-N-terminal kinase and p38 mitogen-activated protein kinase, but not that of extracellular signal-regulated kinase-1/2. Moreover, topical application of TQ induced the expression of heme oxygenase-1, NAD(P)H-quinoneoxidoreductase-1, glutathione-S-transferase and glutamate cysteine ligase in mouse skin. Taken together, the inhibitory effects of TQ on TPA-induced COX-2 expression and NF-κB activation, and its ability to induce the expression of cytoprotective proteins provide a mechanistic basis of anti-inflammatory and antioxidative effects of TQ in hairless mouse skin.

Effect of different pretreatments on functional properties of African catfish (Clarias gariepinus) skin gelatin.

Pretreatments with different types of alkali and acid were compared to determine their effects on gelatin extraction from African catfish (Clarias gariepinus) skin. The study was divided into three parts. In the first part, the skins were only treated with alkaline (Ca(OH)2 or NaOH) solution or pretreated with acetic acid solution. For second part, combination of alkali and acid pretreatment was carried out. For the third part, the skins were first treated with NaOH solution, followed by the treatment with acetic acid, citric acid or sulfuric acid solution. Functional properties including the yield of protein recovery, gel strength, viscosity, pH and viscoelastic properties were determined on gelatins obtained with different pretreatment conditions. Pretreatment with alkali removed noncollagenous proteins effectively, whilst acid pretreatment induced some loss of collagenous proteins. Combination of alkali and acid pretreatment not only removed the noncollagenous proteins and caused a significant amount of swelling, but also provided the proper pH condition for extraction, during which some cross-linkages could be further destroyed but with less breakage of intramolecular peptide chains. Pretreatment of catfish skins with 0.2N NaOH followed by 0.05M acetic acid improved yield of protein recovery, gel strength, viscosity, melting temperature and gelling temperature of gelatin extract.

Skin pretreatment with microneedles prior to pilocarpine iontophoresis increases sweat production

Collection of sweat via pilocarpine iontophoresis is commonly used to diagnose cystic fibrosis (CF), with thousands of tests performed each day. The main source of resistance to the passage of pilocarpine ions to the sweat glands is the electrical resistance of the stratum corneum. It was hypothesized that pretreating the skin with 0·5mm-long microneedles would significantly decrease this resistance, thus increasing pilocarpine's permeation into the skin. Improved permeation should result in significantly reduced time to sweat initiation, time to collection of a clinically meaningful amount of sweat, and increased total amount of sweat produced in 15min. Subjects (n=12) had two 5cm(2) areas on the forearm measured, marked and randomized to experimental (microneedles+iontophoresis) or control (iontophoresis alone). Microneedle pretreatment was conducted using a 35-needle microneedle stamp in a manner that 20 applications completely covered the 5cm(2) treatment area. This was repeated five times for a total of 100 applications. Both experimental and control sites were placed under iontophoresis (1·5mA) for 5min. Microneedle pretreatment significantly decreased mean skin resistance (260±27 kΩ versus 160±19 kΩ, P=0·006), while significantly increasing mean sweat rate (0·76±0·35 versus 0·54±0·19μl cm(2) min(-1) , P=0·007). No significant difference was found concerning pain (P=0·059), number of active sweat glands (P=0·627) or the osmolality of the collected sweat (P=0·636). The results of this study suggest that microneedle pretreatment prior to pilocarpine iontophoresis significantly increases sweat production. Such results have the potential to improve the methodology currently used to diagnose cystic fibrosis and, more broadly, to administer drugs via the skin.

Microwave-Osmotic Dehydration of Cranberries under Continuous Flow Medium Spray Conditions

Microwave-osmotic dehydration of cranberries was evaluated under continuous flow medium spray (MWODS) conditions after some pretreatments. A central composite rotatable design was used with three input variables at five levels (temperature, 33°C–67°C; sucrose concentration, 33°B–67°B; and contact time, 5–55 min). Responses were moisture loss (ML), solids gain (SG), and weight reduction (WR) as well as color and texture parameters. The responses were related to process variables using response surface methodology and statistical analysis: each model was tested for lack of fit to assure nonsignificance (P&gt;0.05) and each process variable was tested for significance (P&lt;0.05 or P&lt;0.0001). Temperature was found to have the most prominent effect as it was significant with all drying (ML, SG, and WR) and quality (hardness and chewiness) parameters, while contact time was found to be significant with ML and WR. Concentration wasn’t found to be significant for any response. Increasing skin pretreatment severity generally promoted SG but had little effect on ML. The exception was chemical peeling, which favored ML but had no effect on SG. Overall, MWODS enables food dehydration in a much faster period of time than conventional osmotic dehydration (COD), while specifically promoting moisture loss over solids gain.

Synthesis of PLGA nanoparticles of tea polyphenols and their strong in vivo protective effect against chemically induced DNA damage

In spite of proficient results of several phytochemicals in preclinical settings, the conversion rate from bench to bedside is not very encouraging. Many reasons are attributed to this limited success, including inefficient systemic delivery and bioavailability under in vivo conditions. To achieve improved efficacy, polyphenolic constituents of black (theaflavin [TF]) and green (epigallocatechin-3-gallate [EGCG]) tea in poly(lactide-co-glycolide) nanoparticles (PLGA-NPs) were entrapped with entrapment efficacy of ~18% and 26%, respectively. Further, their preventive potential against 7,12-dimethylbenzanthracene (DMBA)-induced DNA damage in mouse skin using DNA alkaline unwinding assay was evaluated. Pretreatment (topically) of mouse skin with either TF or EGCG (100 μg/mouse) doses exhibits protection of 45.34% and 28.32%, respectively, against DMBA-induced DNA damage. However, pretreatment with TF-loaded PLGA-NPs protects against DNA damage 64.41% by 1/20th dose of bulk, 71.79% by 1/10th dose of bulk, and 72.46% by 1/5th dose of bulk. Similarly, 51.28% (1/20th of bulk), 57.63% (1/10th of bulk), and 63.14% (1/5th of bulk) prevention was noted using EGCG-loaded PLGA-NP doses. These results showed that tea polyphenol-loaded PLGA-NPs have ~30-fold dose-advantage than bulk TF or EGCG doses. Additionally, TF- or EGCG-loaded PLGA-NPs showed significant potential for induction of DNA repair genes (XRCC1, XRCC3, and ERCC3) and suppression of DNA damage responsive genes (p53, p21, MDM2, GADD45α, and COX-2) as compared with respective bulk TF or EGCG doses. Taken together, TF- or EGCG-loaded PLGA-NPs showed a superior ability to prevent DMBA-induced DNA damage at much lower concentrations, thus opening a new dimension in chemoprevention research.

Evaluation of Percutaneous Absorption of Esculetin: Effect of Chemical Enhancers

Percutaneous transdermal absorption of esculetin (6,7-dihydroxycoumarin), an oxidative damage inhibitor, was evaluated by means of in vitro permeation studies in which vertical Franz-type diffusion cells and pig ear skin were employed. To determine the absorption of esculetin, we validated a simple, accurate, precise, and rapid HPLC-UV method. Additionally, the effects of several percutaneous enhancers were studied. Pretreatment of porcine skin was performed with ethanol (control vehicle), decenoic acid, oleic acid, R-(+)-limonene, and laurocapram (Azone®) (5% in ethanol, w/w, respectively). Pretreatment of skin with oleic acid or laurocapram led to statistically significant differences in the transdermal flux of esculetin with respect to controls. Of the two enhancers, laurocapram showed the greatest capacity to enhance the flux of esculetin across pig skin.

Fractional laser‐assisted delivery of methyl aminolevulinate: Impact of laser channel depth and incubation time

Pretreatment of skin with ablative fractional lasers (AFXL) enhances the uptake of topical photosensitizers used in photodynamic therapy (PDT). Distribution of photosensitizer into skin layers may depend on depth of laser channels and incubation time. This study evaluates whether depth of intradermal laser channels and incubation time may affect AFXL-assisted delivery of methyl aminolevulinate (MAL). Yorkshire swine were treated with CO2 AFXL at energy levels of 37, 190, and 380 mJ/laser channel and subsequent application of MAL cream (Metvix) for 30, 60, 120, and 180 minutes incubation time. Fluorescence photography and fluorescence microscopy quantified MAL-induced porphyrin fluorescence (PpIX) at the skin surface and at five specific skin depths (120, 500, 1,000, 1,500, and 1,800 µm). Laser channels penetrated into superficial (∼300 µm), mid (∼1,400 µm), and deep dermis/upper subcutaneous fat layer (∼2,100 µm). Similar fluorescence intensities were induced at the skin surface and throughout skin layers independent of laser channel depth (180 minutes; P < 0.19). AFXL accelerated PpIX fluorescence from skin surface to deep dermis. After laser exposure and 60 minutes MAL incubation, surface fluorescence was significantly higher compared to intact, not laser-exposed skin at 180 minutes (AFXL-MAL 60 minutes vs. MAL 180 minutes, 69.16 a.u. vs. 23.49 a.u.; P < 0.01). Through all skin layers (120-1,800 µm), laser exposure and 120 minutes MAL incubation induced significantly higher fluorescence intensities in HF and dermis than non-laser exposed sites at 180 minutes (1,800 µm, AFXL-MAL 120 minutes vs. MAL 180 minutes, HF 14.76 a.u. vs. 6.69 a.u. and dermis 6.98 a.u. vs. 5.87 a.u.; P < 0.01). AFXL pretreatment accelerates PpIX accumulation, but intradermal depth of laser channels does not affect porphyrin accumulation. Further studies are required to examine these findings in clinical trials.

Acoustic emission measurement of rubbing and tapping contacts of skin and tongue surfaces in relation to tactile perception

The application of acoustic emission measurement (“acoustic tribology”) is explored for in vivo characterization of rubbing and tapping contacts of the biological tissues of skin and tongue. This acoustic signal originates from physical processes that are closely related to the rapid force fluctuations that are sensed by the rapidly-adapting mechanoreceptors involved in the sensation of touch. Demonstrated is the recording and analysis of sound produced by rubbing and tapping the skin against various surface textures of common materials and by rubbing the tongue against the palate or against food material in the mouth for 1 individual. The technique is shown to be sensitive to skin pre-treatment and pre-meals, and is also shown to discriminate between various surface textures and food materials in a way that relates to perception. The main advantages of the technique are its time-resolution, ease of operation and the fact that it is a direct in vivo measurement of processes that are closely related to texture perception.

Molecular and functional properties of gelatin from the skin of unicorn leatherjacket as affected by extracting temperatures

Gelatins extracted from the skin of unicorn leatherjacket at different temperatures (45, 55, 65 and 75°C) in the presence and the absence of soybean trypsin inhibitor (SBTI; 100units/g pretreated skin) for 12h were characterised. In general, the addition of SBTI resulted in the lower yield, regardless of extraction temperature. Higher yield was obtained when higher extraction temperature was used (P<0.05). Gelatin from skin extracted at 75°C in the absence of SBTI showed the highest yield (10.66±0.41%) (based on dry weight). The highest α-amino group content was observed in gelatin extracted at 55°C without SBTI incorporated. The band intensity of β-chain and α-chains increased as the extraction temperature increased, particularly above 55°C. Gelatin extracted at 65°C with and without SBTI incorporation exhibited the highest gel strength (178.00±7.50g and 170.47±1.30g, respectively). FTIR spectra indicated that a greater loss of molecular order of triple helix with a higher degradation was found in gelatin extracted at 55°C in the absence SBTI. Gelatin extracted at 65°C, either with or without SBTI, had the highest EAI and ESI with high foam expansion and stability. Thus, the extraction of gelatin from the skin of unicorn leatherjacket at temperature sufficiently high could render the gelatin with less degradation.

Microneedle pretreatment enhances the percutaneous permeation of hydrophilic compounds with high melting points

BackgroundTwo commercially available microneedle rollers with a needle length of 200 μm and 300 μm were selected to examine the influence of microneedle pretreatment on the percutaneous permeation of four non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen, paracetamol) with different physicochemical drug characteristics in Franz-type diffusion cells. Samples of the receptor fluids were taken at predefined times over 6 hours and were analysed by UV–VIS high-performance liquid-chromatography. Histological examinations after methylene blue application were additionally performed to gather information about barrier disruption.ResultsDespite no visible pores in the stratum corneum, the microneedle pretreatment resulted in a twofold (200 μm) and threefold higher (300 μm) flux through the pretreated skin samples compared to untreated skin samples for ibuprofen and ketoprofen (LogKow > 3, melting point < 100°C). The flux of the hydrophilic compounds diclofenac and paracetamol (logKow < 1, melting point > 100°C) increased their amount by four (200 μm) to eight (300 μm), respectively.ConclusionCommercially available microneedle rollers with 200–300 μm long needles enhance the drug delivery of topically applied non-steroidal anti-inflammatory drugs and represent a valuable tool for percutaneous permeation enhancement particularly for substances with poor permeability due to a hydrophilic nature and high melting points.

An Interstitial Fluid Transdermal Extraction System for Continuous Glucose Monitoring

A novel microfluidic system which is fabricated with five polydimethylsiloxane layers for interstitial fluid (ISF) extraction, collection, and measurement toward the application of continuous and real-time glucose monitoring is presented in this paper. The system consists of a micro vacuum generator for ISF transdermal extraction and fluid manipulation, micro chambers for the collection of ISF, micro pneumatic valves for fluid management, and a micro flow sensor for ISF volume measurement. Sequentially controlled by the pneumatic valves, the ISF extraction, collection, and volumetric measurement functions of the system were demonstrated using the stable vacuum generated by the integrated vacuum generator. Through low-frequency ultrasound pretreated full-thickness pig skin, the normal saline solution with different glucose concentrations was transdermally extracted, collected, and measured. The absolute error in the volume measurement of the transdermally extracted “ISF analog” was less than 0.05 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{L}$</tex></formula> . The microfluidic system makes it possible to realize the clinical application of continuous glucose monitoring based on ISF transdermal extraction technology. <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hfill$</tex></formula> [2011-0329]

Differences in peripheral endocannabinoid modulation of scratching behavior in facial vs. spinally-innervated skin

Cannabinoids suppress nocifensive behaviors in rodents. We presently investigated peripheral endocannabinoid modulation of itch- and pain-related behaviors elicited from facial vs. spinally-innervated skin of rats. Intradermal (id) injection of the pruritogen serotonin (5-HT) elicited significantly more hindlimb scratch bouts, and longer cumulative time scratching, when injected in the rostral back compared to the cheek. Pretreatment of skin with inhibitors of degrading enzymes for the endocannabinoids anandamide (URB597) or 2-arachidonoylglycerol (JZL184) significantly reduced scratching elicited by 5-HT in the rostral back. These effects were prevented by co-treatment with antagonists of the CB1 (AM251) or CB2 receptor (AM630), implicating both receptor subtypes in endocannabinoid suppression of scratching in spinally-innervated skin. Conversely, pretreatment with either enzyme inhibitor, or with AM630 alone, increased the number of scratch bouts elicited by id 5-HT injection in the cheek. Moreover, pretreatment with JZL184 also significantly increased pain-related forelimb wipes directed to the cheek following id injection of the algogen, allyl isothiocyanate (AITC; mustard oil). Thus, peripheral endocannabinoids have opposite effects on itch-related scratching behaviors in trigeminally- vs. spinally-innervated skin. These results suggest that increasing peripheral endocannabinoid levels represents a promising therapeutic approach to treat itch arising from the lower body, but caution that such treatment may not relieve, and may even exacerbate, itch and pain arising from trigeminally-innervated skin of the face or scalp.

Skin presenting a higher level of caspase-14 is better protected from UVB irradiation according to in vitro and in vivo studies

Caspase-14, a cysteine endoproteinase belonging to the conserved family of aspartate-specific proteinases, was shown to play an important role in the terminal differentiation of keratinocytes and barrier function of the skin. In the present study, we developed a biofunctional compound that we described as a modulator of caspase-14 expression. Using normal human keratinocytes (NHK) in culture and human skin biopsies, this compound was shown to increase caspase-14 expression and partially reverse the effect of caspase-14-specific siRNA on NHK. Moreover, the increase in filaggrin expression visualized on skin biopsies and the recovery of the barrier structure after tape-stripping indicated that this compound could exhibit a beneficial effect on the skin barrier function. Considering the possible link between caspase-14 and the barrier function, a UVB irradiation on NHK and skin biopsies previously treated with the caspase-14 inducer, was performed. Results indicated that pretreated skin biopsies exhibited less signs of UV damage such as active caspase-3 and cyclobutane pyrimidine dimers (CPDs). Likewise, pretreated NHK were protected from UV-induced genomic DNA damage, as revealed by the Comet Assay. Finally, a clinical test showed a reduction of transepidermal water loss (TEWL) on the treated skin compared with placebo, under UV stress condition, confirming a protecting effect. Taken together, these results strongly suggest that, by increasing caspase-14 expression, the biofunctional compound could exhibit a protective effect on the skin barrier function, especially in case of barrier damage and UV irradiation.

Challenges and Strategies in Developing Microneedle Patches for Transdermal Delivery of Protein and Peptide Therapeutics

The birth of microneedles, an array of needles sufficiently long to penetrate epidermis but small enough to do not cause skin injury and pain feeling, has offered a highly promising solution for non-invasive delivery of protein and peptide drugs, a long-cherished desire over eighty years. However, the attempts to develop clinically feasible microneedle transdermal delivery methods encountered series of difficulties, for which a decade research efforts have yet to result in a single product. Microneedles may be incorporated into devices as skin pre-treatment tools, skin microinjectors as well as transdermal patches by their functions in drug delivery. They may also be categorized to insoluble solid microneedles, hollow microneedles, soluble/degradable solid microneedles and phase-transition microneedles by their structure and forming materials. This review article is aimed to update the progress and discuss the technical challenges raised in developing protein/peptide loaded microneedle patches.

Abstract 1587: AMPK-mTOR axis as key target for chemoprevention of UV-induced skin cancer by the bioflavonoid apigenin

Abstract Over two million new cases of UV-induced non-melanoma skin cancer are diagnosed yearly in the USA, making it the most common form of cancer in this country. Apigenin, a nonmutagenic, naturally occurring flavonoid found in a variety of fruits and leafy vegetables, inhibits UV-induced skin cancer in mice. Our laboratory and others have shown that apigenin treatment of cells results in a wide variety of antitumorigenic and chemopreventive actions, including suppression of COX-2 expression, enhancement of p53 expression, and induction of cell cycle arrest and apoptosis. However, the primary target(s) responsible for apigenin's chemopreventive function remains elusive. For the first time, we have demonstrated that apigenin activated AMP-activated protein kinase (AMPK) in keratinocytes (mouse and human keratinocyte cell lines, primary normal human epidermal keratinocytes (NHEKs) and mouse epidermis in vivo). The activation of AMPK resulted in inhibition of mTOR signaling, which relieved the block to the autophagy pathway, further inducing autophagy in human keratinocytes. At early stages of tumorigenesis, autophagy acts as a tumor suppressor by removing damaged organelles, proteins, reducing chromosome instability, and inducing type II programmed cell death. Therefore, pharmacological induction of autophagy provides a new strategy for cancer chemoprevention. We have further demonstrated that UV radiation also induced moderate AMPK activation, suggesting that there is a protective cellular response after UV radiation alone, providing limited protection through modest AMPK activation. More intriguingly, pretreatment of keratinocytes or skin with apigenin prior to UV radiation induced AMPK activation dramatically (both in vitro and in vivo). In addition, UV markedly increased mTOR phosphorylation in SKH-1 mice epidermis, and apigenin completely inhibited UV-mediated mTOR activation. Taken together, our results demonstrate that the AMPK/mTOR axis is involved in chemoprevention of UV-induced skin cancer by apigenin, and mechanistically the activation of AMPK further induces autophagy to suppress UV-induced tumorigenesis. Identifying AMPK-mTOR axis as a key target of apigenin and targeting the autophagy pathway for cancer chemoprevention would provide a new target and strategy for the development of better treatment and prevention of skin cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1587. doi:1538-7445.AM2012-1587

Can fractional lasers enhance transdermal absorption of topical lidocaine in an in vivo animal model?

It has been shown in vitro that pretreatment of skin with fractional lasers enhances transdermal delivery of drugs. The aim of this study is to demonstrate in vivo firstly that laser enhances transdermal drug absorption and secondly that this can be manipulated by altering laser settings. Four pigs were used in the IACUC approved animal study. On day 0, 5 g of 4% topical lidocaine was applied under occlusion for 60 minutes to a 400 cm(2) area on the abdomen. Blood was drawn at 0, 60, 90, 120, 180, and 240 minutes. On day 7, the Er:YAG laser was used at 500, 250, 50, and 25 µm ablative depth, respectively, over a 400 cm(2) area on the abdomen. Five grams of 4% topical lidocaine was applied immediately with occlusion for 60 minutes, and then removed. Blood was drawn at 0, 60, 90, 120, 180, and 240 minutes. The serum was extracted and analyzed for lidocaine and its metabolite monoethylglycinexylidide (MEGX). Serum levels of lidocaine and MEGX were undetectable in untreated skin. Following laser treatment both lidocaine and MEGX were detectable. Peak levels of lidocaine were significantly higher (P = 0.0002) at 250 µm (0.62 mg/L), compared to 500 µm (0.45 mg/L), 50 µm (0.48 mg/L), and 25 µm (0.3 mg/L). Peak levels of MEGX were significantly higher (P ≤ 0.0001) at 250 µm (0.048 mg/L), compared to 500 µm (0.018 mg/L), 50 µm (0.036 mg/L), and 25 µm (0.0144 mg/L). This study demonstrates that laser pretreatment significantly increases absorption of topical lidocaine so that it is detectable in the blood and that manipulating laser settings can affect drug absorption. Future work will look at translating this effect into clinical benefit.

Effects of Carbon Dioxide (CO2) Laser Perforation as Skin Pretreatment to Improve Sugar Infusion Process of Frozen Blueberries

Sugar infusion is a widely used osmotic treatment for fruit preservation, but the process is inherently slow and the waxy skins of some fruits hinder mass transfer during the process. This work examined the utility of perforation by a carbon dioxide (CO(2)) laser as a novel skin treatment to improve the infusion process. In 2 experiments, individually quick frozen (IQF) blueberries were subjected to varying degrees of laser perforation (3 levels of perforation density × 3 levels of perforation depth), and then infused stepwise with high fructose corn syrup (HFCS) to a final °Brix of 70 using varying solution concentration increment (5, 10, 20, and 30 °Brix/d). At each concentration, increasing perforation density and depth promoted solute migration into the fruit with increased fruit weight (P < 0.05; up to 24.15%, 37.23%, 52.89%, 65.34% wt. increase at 5, 10, 20, and 30 °Brix/d compared to the controls). Laser-treated blueberries maintained the original shape without excessive shrinkage and texture hardening due to enhanced solute incorporation, while the controls and mechanically treated samples were ruptured and wrinkled at the end of the process. Increasing solution concentrations shortened the process duration but decreased final fruit weight due to greater osmotic gradients. However, negative effects of using higher solution concentrations on final fruit weight were significantly alleviated with moderate-to-high doses of laser perforation (P < 0.001). Overall, the results demonstrate that laser perforation can be a viable skin pretreatment technique, offering marked improvement on final process yield, process efficiency, and product quality. CO(2) laser perforation as a novel skin pretreatment for sugar infusion of individually quick frozen (IQF) blueberries is presented. The technique markedly improves the product yield and quality. Although further investigation is needed, the method may potentially be used for other waxy skin fruits such as cranberries and cherries.