Skin Penetration of Epigallocatechin-3-Gallate and Quercetin from Green Tea and Ginkgo biloba Extracts Vehiculated in Cosmetic Formulations

Green tea (Camellia sinensis) and Ginkgo biloba extracts in cosmetic formulations have been suggested to protect the skin against UV-induced damage and skin ageing. Thus, it is very important to assess the human skin penetration of their major flavonoids to verify if they penetrate and remain in the skin to exert their proposed effects. The aim of this study was to evaluate the human skin penetration of epigallocatechin-3-gallate (EGCG) and quercetin from green tea and G. biloba extracts vehiculated in cosmetic formulations. This study was conducted with fresh dermatomed human Caucasian skin from abdominal surgery mounted on static Franz diffusion cells. Skin samples were mounted between two diffusion half-cells and 10 mg/cm(2) of formulations supplemented with 6% of green tea or G. biloba extract were applied on the skin surface. The receptor fluid was removed after 6 and 24 h and analyzed by high-performance liquid chromatography for the quantification of the flavonoids. The stratum corneum was removed by tape stripping and immersed in methanol and the epidermis was mechanically separated from the dermis and triturated in methanol to extract EGCG and quercetin. The results showed that the flavonoids under study penetrated into the skin, without reaching the receptor fluid. The majority of EGCG was quantified in the stratum corneum (0.87 mu g/cm(2)), which was statistically higher than the EGCG concentrations found in viable epidermis (0.54 mu g/cm(2)) and in the dermis (0.38 mu g/cm(2)). The majority of quercetin was quantified in the viable epidermis (0.23 mu g/cm(2)), which was statistically higher than the EGCG concentration found in the stratum corneum layer (0.17 mu g/cm(2)). Finally, it can be concluded that EGCG and quercetin from green tea and G. biloba extracts vehiculated in cosmetic formulations presented good skin penetration and retention, which can favor their skin effects. Copyright (C) 2009 S. Karger AG, Basel

Development and validation of HPLC method for imiquimod determination in skin penetration studies

A simple, rapid and sensitive analytical procedure for the measurement of imiquimod in skin samples after in vitro penetration studies has been developed and validated. In vitro penetration studies were carried out in Franz diffusion cells with porcine skin. Tape stripping technique was used to separate the stratum corneum (SC) from the viable epidermis and dermis. Imiquimod was extracted from skin samples using a 7:3 (v/v) methanol:acetate buffer (100 mm, pH 4.0) solution and ultrasonication. Imiquimod was analyzed by H-PLC using C(8) column and UV detection at 242 ran. The mobile phase used was acetonitrile:acetate buffer (pH 4.0, 100 mM):diethylamine (30:69.85:0.15, v/v) with flow rate 1 mL/min. Imiquimod eluted at 4.1 min and the running time was limited to 6.0 min. The procedure was linear across the following concentration ranges: 100-2500 ng/mL for both SC and tape-stripped skin and 20-800 ng/mL for receptor solution. Intra-day and inter-day accuracy and precision values were lower than 20% at the limit of quantitation. The recovery values ranged from 80 to 100%. The method is adequate to assay imiquimod from skin samples, enabling the determination of the cutaneous penetration profile of uniquimod by in vitro studies. Copyright (C) 2008 John Wiley & Sons, Ltd.

Quercetin in w/o microemulsion: In vitro and in vivo skin penetration and efficacy against UVB-induced skin damages evaluated in vivo

The present study evaluated the potential of a w/o microemulsion as a topical carrier system for delivery of the antioxidant quercetin. Topical and transdermal delivery of quercetin were evaluated in vitro Using porcine car skin mounted on a Franz diffusion cell and in vivo on hairless-skin mice. Skin irritation by topical application of the microemulsion containing quercetin, and the protective effect of the formulation on UVB-induced decrease of endogenous reduced glutathione levels and increase of cutaneous proteinase secretion/activity were also investigated. The w/o microemulsion increased the penetration of quercetin into the stratum corneum and epidermis plus dermis at 3, 6. 9 and 12 h post-application in vitro and in vivo at 6 h post-application. No transdermal delivery of quercetin Occurred. By evaluating established endpoints of skin irritation (erythema formation, epidermis thickening and infiltration of inflammatory cells), the Study demonstrated that the daily application of the w/o microemulsion for up to 2 days did not cause skin irritation. W/o microemulsion containing quercetin significantly prevented the UVB irradiation-induced GSH depletion and secretion/activity of metalloproteinases. (C) 2008 Elsevier B.V. All rights reserved.

Enhanced skin penetration of P20 phosphopeptide using protein transduction domains

Protein transduction domains (PTDs) were recently demonstrated to increase the penetration of the model peptide P20 when the PTD and P20 were covalently attached. Here, we evaluated whether non-covalently linked PTDs were capable of increasing the skin penetration of P20. Two different PTDs were studied: YARA and WLR. Porcine ear skin mounted in a Franz diffusion cell was used to assess the penetration of P20 in the stratum corneum (SC) and viable skin (VS); VS consists of dermis and epidermis without SC. The transdermal delivery of P20 was also assessed. At 1 mM, YARA promoted a 2.33-fold increase in the retention of P20 in the SC but did not significantly increase the amount of P20 that reached VS. WLR significantly increased (2.88-fold) the penetration of P20 in VS. Compared to the non-attached form, the covalently linked WLR fragment was two times more effective in promoting the penetration of P20 into VS. None of the PTDs promoted transdermal delivery of P20 at 4 h post-application. It was concluded that selected non-covalently linked PTDs can be used as a penetration enhancer, but greater skin penetration efficiency can be achieved by covalently binding the PTD to the therapeutic agent. (c) 2007 Elsevier B.V. All rights reserved.

The influence of positive or negative charges in the passive and iontophoretic skin penetration of porphyrins used in photodynamic therapy

Meso-tetra-(N-methylpiridinium-4-yl)-porphyrin (TMPyP) and meso-tetra-(4-sulfonatophenyl)-porphyrin (TPPS(4)) are photosensitizing drugs (PS) used in photodynamic therapy (PDT). Based on the fact that these compounds present similar chemical structures but opposite charges at pH levels near physiological conditions, this work aims to evaluate the in vitro and in vivo influence of these electrical charges on the iontophoretic delivery of TMPyP and TPPS4, attempting to achieve maximum accumulation of PS in skin tissue. The iontophoretic transport of these drugs from a hydrophilic gel was investigated in vitro using porcine ear skin and vertical, flow-through diffusion cells. In vivo experiments using rats were also carried out, and the penetration of the PSs was analyzed by fluorescence microscopy to visualize the manner of how these compounds were distributed in the skin after a short period of iontophoresis application. In vitro, both passive and iontophoretic delivery of the positively charged TMPyP were much greater (20-fold and 67-fold, respectively) than those of the negatively charged TPPS(4). TPPS(4) iontophoresis in vivo increased the fluorescence of the skin only in the very superficial layers. On the other hand, iontophoresis of the positively charged drug expressively increased the rat epidermis and dermis fluorescence, indicating high amounts of this drug throughout the skin layers. Moreover, TMPyP was homogeneously distributed around and into the nuclei of the skin cells, suggesting its potential use in topical PDT. (C) 2010 Elsevier B.V. All rights reserved.

Characterization and stability study of a water-in-oil microemulsion incorporating quercetin

Background: The effectiveness of a water/oil (w/o) microemulsion containing quercetin against ultraviolet B radiation (UVB) induced damage was recently demonstrated by our group. However, during the development of new pharmaceutical products, the evaluation of percutaneous absorption and in vivo effectiveness should be accompanied by evaluation of stability parameters as an integral part of the process. Objective: The aim was to investigate the stability of the final microemulsion formulation considering the temperature ranges of storage and application. Methods: The physical, chemical, and functional stability of this formulation under different conditions of storage during 12 months and the photostability of quercetin incorporated into this system over UVB exposure for 7 days were evaluated. Results: Although the results indicated a notable physical stability of the w/o microemulsions during the experimental period under all employed conditions, in both, the chemical and functional studies, a significant loss of quercetin content and antioxidant activity was found after 6 months of storage at 30 degrees C/70% relative humidity and after 2 months at 40 degrees C/70% relative humidity. The photostability study results demonstrated that the incorporation of quercetin into the w/o microemulsion maintained the previously demonstrated photostability of this flavonoid under forced exposure to UVB irradiation. Conclusion: Thus, this work demonstrates that special storage conditions (at 4 +/- 2 degrees C) are necessary to maintain the functionality of the w/o microemulsion containing quercetin and mainly emphasizes the importance of studying physical, chemical, and functional parameters at the same time during stability evaluation of active principles.

Topical Delivery of Lycopene Using Microemulsions: Enhanced Skin Penetration and Tissue Antioxidant Activity

Topical delivery of lycopene is a convenient way to supplement cutaneous levels of antioxidants. In this study, lycopene was incorporated (0.05%, w/w) in two microemulsions containing BRIJ-propylene glycol (2:1, w/w, surfactant blend) but different oil phases: mono/diglycerides of capric and caprylic acids (MG) or triglycerides of the same fatty acids (TG). Microemulsions containing MG and TG were isotropic, fluid, and clear, with internal phase diameters of 27 and 52 nm, respectively. Both MG- or TG-containing microemulsions markedly increased lycopene penetration in the stratum corneum, (6- and 3.6-fold, respectively) and in viable layers of porcine ear skin 2 (from undetected to 172.6 +/- 41.1 and 103.1 +/- 7.2 ng/cm(2), respectively) compared to a control solution. To assure that lycopene delivered to the skin was active, the antioxidant activity of skin treated with MG-containing microemulsion was determined by CUPRAC assay, and found to be 10-fold higher than untreated skin. The cytotoxicity of MG-containing microemulsion in cultured fibroblasts was similar to propylene glycol (considered safe) and significantly less than of sodium lauryl sulfate (a moderate-to-severe irritant) at 1-50 mu g/mL. These results demonstrate that the MG-containing microemulsion is an efficient and safe system to increase lycopene delivery to the skin and the antioxidant activity in the tissue. (C) 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:1346-1357, 2010

On the relationship between the critical temperature and the London penetration depth in layered organic superconductors

We present an analysis of previously published measurements of the London penetration depth of layered organic superconductors. The predictions of the BCS theory of superconductivity are shown to disagree with the measured zero temperature, in plane, London penetration depth by up to two orders of magnitude. We find that fluctuations in the phase of the superconducting order parameter do not determine the superconducting critical temperature as the critical temperature predicted for a Kosterlitz–Thouless transition is more than an order of magnitude greater than is found experimentally for some materials. This places constraints on theories of superconductivity in these materials.

Enzyme immobilization in porous solid supports - penetration of immobilized enzyme

The process of enzyme immobilization under the diffusion-controlled regime (i.e., fast attachment of enzyme compared to its diffusion) is modeled and theoretically solved in this article. Simple and compact solutions for the penetration depth of immobilized enzyme and the bulk enzyme concentration versus time are presented. Furthermore, the conditions for the validity of our solutions are also given in this article so that researchers can discover when the theoretical solutions can be applied to their systems.

Usefulness of Proteinuria as a Prognostic Marker of Mortality and Cardiovascular Events Among Patients Undergoing Percutaneous Coronary Intervention (Data from the Evaluation of Oral Xemilofiban in Controlling Thrombotic Events [EXCITE] Trial)

Proteinuria was associated with cardiovascular events and mortality in community-based cohorts. The association of proteinuria with mortality and cardiovascular events in patients undergoing percutaneous coronary intervention (PCI) was unknown. The association of urinary dipstick proteinuria with mortality and cardiovascular events (composite of death, myocardial infarction, or nonhemorrhagic stroke) in 5,835 subjects of the EXCITE trial was evaluated. Dipstick urinalysis was performed before PCI, and proteinuria was defined as trace or greater. Subjects were followed up for 210 days/7 months after enrollment for the occurrence of events. Multivariate Cox regression analysis evaluated the independent association of proteinuria with each outcome. Mean age was 59 years, 21% were women, 18% had diabetes mellitus, and mean estimated glomerular filtration rate was 90 ml/min/1.73 m(2). Proteinuria was present in 750 patients (13%). During follow-up, 22 subjects (2.9%) with proteinuria and 54 subjects (1.1%) without proteinuria died (adjusted hazard ratio 2.83, 95% confidence interval [CI] 1.65 to 4.84, p <0.001). The severity of proteinuria attenuated the strength of the association with mortality after PCI (low-grade proteinuria, hazard ratio 2.67, 95% CI 1.50 to 4.75; high-grade proteinuria, hazard ratio 3.76, 95% CI 1.24 to 11.37). No significant association was present for cardiovascular events during the relatively short follow-up, but high-grade proteinuria tended toward increased risk of cardiovascular events (hazard ratio 1.45, 95% CI 0.81 to 2.61). In conclusion, proteinuria was strongly and independently associated with mortality in patients undergoing PCI. These data suggest that such a relatively simple and clinically easy to use tool as urinary dipstick may be useful to identify and treat patients at high risk of mortality at the time of PCI. (C) 2008 Elsevier Inc. All rights reserved. (Am J Cardiol 2008;102:1151-1155)

Long-term safety and efficacy of percutaneous coronary intervention with stenting and coronary artery bypass surgery for multivessel coronary artery disease - A meta-analysis with 5-year patient-level data from the ARTS, ERACI-II, MASS-II, and SoS trials

Background-Randomized trials that studied clinical outcomes after percutaneous coronary intervention (PCI) with bare metal stenting versus coronary artery bypass grafting (CABG) are underpowered to properly assess safety end points like death, stroke, and myocardial infarction. Pooling data from randomized controlled trials increases the statistical power and allows better assessment of the treatment effect in high-risk subgroups. Methods and Results-We performed a pooled analysis of 3051 patients in 4 randomized trials evaluating the relative safety and efficacy of PCI with stenting and CABG at 5 years for the treatment of multivessel coronary artery disease. The primary end point was the composite end point of death, stroke, or myocardial infarction. The secondary end point was the occurrence of major adverse cardiac and cerebrovascular accidents, death, stroke, myocardial infarction, and repeat revascularization. We tested for heterogeneities in treatment effect in patient subgroups. At 5 years, the cumulative incidence of death, myocardial infarction, and stroke was similar in patients randomized to PCI with stenting versus CABG (16.7% versus 16.9%, respectively; hazard ratio, 1.04, 95% confidence interval, 0.86 to 1.27; P = 0.69). Repeat revascularization, however, occurred significantly more frequently after PCI than CABG (29.0% versus 7.9%, respectively; hazard ratio, 0.23; 95% confidence interval, 0.18 to 0.29; P<0.001). Major adverse cardiac and cerebrovascular events were significantly higher in the PCI than the CABG group (39.2% versus 23.0%, respectively; hazard ratio, 0.53; 95% confidence interval, 0.45 to 0.61; P<0.001). No heterogeneity of treatment effect was found in the subgroups, including diabetic patients and those presenting with 3-vessel disease. Conclusions-In this pooled analysis of 4 randomized trials, PCI with stenting was associated with a long-term safety profile similar to that of CABG. However, as a result of persistently lower repeat revascularization rates in the CABG patients, overall major adverse cardiac and cerebrovascular event rates were significantly lower in the CABG group at 5 years.

Percutaneous central venous catheterization through the external jugular vein in children: improved success rate with body maneuvers and fluoroscopy assistance

Background/Purpose: Central venous catheterization is among the most common procedures performed by pediatric surgeons. Significant morbidity and even mortality can ensue from the widespread approach to the deep veins of the neck and femoral region. The external jugular vein (EJV) is a low-morbidity alternative for percutaneous catheterization in children, but it has yielded a low success rate in previous reports The authors show an improved success rate with this option. Methods: We performed an analysis of 33 patients` charts in which central venous catheterization using Seldinger technique through the EJV was attempted in 2005. Age, diagnosis, maneuvers used for success, fluoroscopy usefulness, and types of inserted catheters were evaluated. Results: The procedure was successful in 26 (78.8%) patients without complications. Diagnosis was neoplasia in almost half of the patients (42%). In half of the successful cases, body maneuvers were used, namely, twisting the head of the patient to the side of the vein and stretching the ipsilateral arm and shoulder. All but one procedure were completed under fluoroscopic guidance. In 6 (23%) patients, a long-term catheter was inserted. Conclusions: The EJV is an excellent option for central venous catheterization in children. The execution of simple maneuvers along with fluoroscopic assistance might allow for an improved success rate not only for short-term but also for long-term catheter insertion. (C) 2008 Elsevier Inc. All rights reserved.

Penetration of cefuroxime in subcutaneous tissue during coronary artery bypass grafting surgery

A sensitive and rapid HPLC assay for determining cefuroxime penetration in the subcutaneous tissue near to surgical incision of patients submitted to coronary artery bypass grafting (CABC) with or without cardiopulmonary bypass (CPB) was performed. Blood and subcutaneous tissue samples were collected from 14 patients. in four periods during surgery. The analytical method presented linearity from 0.5 to 100 mu g/g. LOQ = 0.50 mu g/g, LOD = 0.25 mu g/g. intra- and interday precision (%CV) ranged from 4.9 to 8.9% and 6.4 to 9.9%, respectively, and intra-and interday accuracy expressed as % of the nominal concentration ranged from 87.1 to 104.6% and 94.8 to 103.8%, respectively (mean of three concentrations). Relative recovery was 98.4%. Tissue/plasma ratios obtained for CPB and non-CPB were, respectively: 14.6% vs 19.0% (0.6 h); 15.7% vs 15.7% (2.1 h); 22.5% vs 19.9% (3.6 h); 15.7% vs 18.8% (4.5 h). Data obtained indicate that tissue/plasma ratio remains unchanged in CPB and non-CPB patients during all period of surgery and the CPB does not affect the penetration of cefuroxime in tissues close to the surgical wound. (C) 2009 Elsevier B.V. All rights reserved.

Supersaturated solutions evaluated with an in vitro stratum corneum tape stripping technique

The flux of a compound across a membrane from any formulation, whether it contains penetration enhancers or not, is limited by its saturated solubility in the vehicle. Under such conditions the concentration of the permeant in the outer layers of the stratum corneum is also saturated. Consequently, when the permeation of a drug from a supersaturated solution leads to enhanced penetration, the concentration of the drug in the outer layers of the membrane is also supersaturated. Therefore, the stratum corneum may possess antinucleant properties which inhibit or retard the crystallisation process. In this study, the enhanced in vitro permeation of supersaturated solutions of piroxicam across human skin in diffusion cells was demonstrated. The amount of permeant in the stratum corneum was determined using a tape stripping technique. Supersaturated solutions up to four degrees of saturation were investigated which produced a linear relationship between the degree of saturation and the amount of piroxicam in the stratum corneum (R-2 = 0.970). Furthermore, the amount of piroxicam in the viable layers of the skin also increased with increasing degree of saturation. An analysis of the results suggested that enhanced penetration across human skin from supersaturated solutions of piroxicam may occur as a result of the antinucleating ability of the intercellular lipids of the stratum corneum. (C) 1997 Elsevier Science B.V.

Pressure-Frequency Sensing Subxiphoid Access System for Use in Percutaneous Cardiac Electrophysiology: Prototype Design and Pilot Study Results

We have designed, built, and tested an early prototype of a novel subxiphoid access system intended to facilitate epicardial electrophysiology, but with possible applications elsewhere in the body. The present version of the system consists of a commercially available insertion needle, a miniature pressure sensor and interconnect tubing, read-out electronics to monitor the pressures measured during the access procedure, and a host computer with user-interface software. The nominal resolution of the system is <0.1 mmHg, and it has deviations from linearity of <1%. During a pilot series of human clinical studies with this system, as well as in an auxiliary study done with an independent method, we observed that the pericardial space contained pressure-frequency components related to both the heart rate and respiratory rate, while the thorax contained components related only to the respiratory rate, a previously unobserved finding that could facilitate access to the pericardial space. We present and discuss the design principles, details of construction, and performance characteristics of this system.