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At least 307 records · Page 17Linked to original sources
PubMed1993

Measuring the uptake of Azone into excised human stratum corneum from thin polymer films.

The extent of uptake of Azone into excised human stratum corneum from thin polymer films has been measured using a sandwich model. With poly(dimethyl)siloxane, an Azone loading of the stratum corneum of 6-7% w/w was achieved. With Eudragit NE30D, a loading of less than 1% was reached. The extent of uptake into the stratum corneum and acceptor layers of the sandwich model depended on the Azone content of the films. The resulting enhanced uptake and flux of diazepam through the stratum corneum membrane into a polymeric acceptor layer corresponded closely to the amounts of Azone taken up and their known enhancing effects. The uptake of diazepam from the poly(dimethyl)siloxane films was ten times larger than that from Eudragit NE30D films. The extent of uptake is, therefore, controlled by the rate of release from the polymer and partitioning at the interface.

Acrylic Resins↗
PubMed1983

Orally administered ketoconazole: route of delivery to the human stratum corneum.

Delivery of ketoconazole to human stratum corneum was studied. Thirteen healthy volunteers, three patients with chronic fungal disease and one patient with palmar-plantar hyperhidrosis were given 400 mg of ketoconazole daily for various lengths of time. The ketoconazole content of palmar stratum corneum, eccrine sweat, sebum, and serum was measured by high-pressure liquid chromatography (sensitivity, 0.005 to 0.010 microgram/ml). Palmar stratum corneum obtained after 7 and 14 days of daily administration contained up to 14 micrograms of ketoconazole per g. Ketoconazole was not found in sebum after 7 or 14 days of daily ingestion of the antimycotic agent. Sebum from three patients with chronic fungal infection treated for greater than 9 months contained ketoconazole (means, 4.7 micrograms/g). Thermogenic whole body eccrine sweat contained a mean of 0.059 microgram/ml on day 7 and 0.084 microgram/ml on day 14 of daily administration. Ketoconazole appeared in thermogenic whole body eccrine sweat and palmar hyperhidrotic sweat within 1 h after a single oral dose. Partition studies of ketoconazole containing eccrine sweat demonstrated a 10-fold greater concentration in the sediment phase (desquamated keratinocytes) compared with the clear supernatant phase. In vitro studies with [3H]ketoconazole-supplemented supernatant sweat revealed preferential binding to stratum corneum, hair, and nails and its partitioning to lipid-rich sebum. We conclude that eccrine sweat rapidly transports ketoconazole across the blood-skin barrier, where it may bind or partition to keratinocytes and surface lipids.

Administration, Oral↗
PubMed1994

In vivo pharmacokinetics and pharmacodynamics of topical ketoconazole and miconazole in human stratum corneum.

A direct study evaluating whether differential drug uptake of topical 2% miconazole and 2% ketoconazole from cream formulations into human stratum corneum correlated with differential pharmacological activity against Candida albicans was investigated in healthy human subjects. A single 24-h topical dose of 2% ketoconazole cream or 2% miconazole cream was applied unoccluded, at the same dose (2.6 mg of formulation per cm2 of surface area), at four skin sites on both ventral forearms of six human subjects. At the end of the treatment, residual drug was removed with a tissue from all sites and the treated site was tape stripped 11 times, either 1, 4, 8, or 24 h later. The first tape disc was discarded. The remaining tape discs, 2 through 11, were combined and extracted for drug quantification by high-performance liquid chromatography and bioactivity against C. albicans growth in vitro. Topical 2% ketoconazole produced 14-, 10-, and 7-fold greater drug concentrations in stratum corneum than 2% miconazole at 1, 4, and 8 h after a single topical dose. Ketoconazole and miconazole concentrations in the stratum corneum were similar 24 h after drug removal. Tape disc extracts from 2% ketoconazole-treated skin sites demonstrated significantly greater bioactivity in the bioassay than 2% miconazole. The increased efficacy of 2% ketoconazole compared with that of 2% miconazole in vitro reflects their differential uptake into the stratum corneum and inherent pharmacological activity. Tape stripping the drug-treated site in conjunction with a bioassay is therefore a useful approach in the determination of bioavailability of topical antifungal agents.

Administration, Topical↗
PubMed1995

Mechanisms of selective long-term potentiation of excitatory synapses in stratum oriens/alveus interneurons of rat hippocampal slices.

1. We investigated long-term potentiation (LTP) of synaptic transmission in different populations of interneurons in the CA1 region of rat hippocampal slices using whole cell recordings. We elicited excitatory postsynaptic currents (EPSCs) in interneurons located in stratum oriens near the alveus (O/A) or in stratum lacunosum-moleculare near the stratum radiatum border (L-M) by electrical stimulation of nearby axons in stratum oriens and radiatum, respectively. 2. High-frequency stimulation (100 Hz, 1 s) of axons in conjunction with postsynaptic depolarization (to -20 mV) increased the peak amplitude of test EPSCs elicited at -80 mV in O/A interneurons. The mean peak amplitude of EPSCs was significantly potentiated relative to the control period at 10 min (39 +/- 7% increase, mean +/- SE; n = 11 cells) and 30 min (30 +/- 1% increase; n = 5 cells) after tetanization. Similar stimulation did not produce potentiation of EPSCs in L-M interneurons (n = 7 cells). 3. This selective LTP in O/A interneurons was reversibly blocked by the N-methyl-D-aspartate receptor antagonist (+/-)2-amino-5-phosphonopentanoic acid (AP-5). Tetanization in the presence of 25 microM AP-5 did not increase the amplitude of EPSCs (8 cells). After washout of AP-5 (4 cells), a second tetanization resulted in long-term potentiation of EPSCs. 4. LTP was dependent on the activation of metabotropic glutamate receptors. The peak amplitude of EPSCs was not increased 5-10 or 15-20 min after tetanization during bath application of the metabotropic glutamate receptor antagonist (RS)-alpha-methyl-4-carboxyphenylglycine (500 microM) (n = 5 cells). 5. Inclusion of the Ca2+ chelator 1,2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA; 25 mM) in the patch pipette blocked LTP in O/A interneurons. In five cells recorded with BAPTA-containing electrodes, the mean peak amplitude was not significantly increased after tetanization. Thus a rise in postsynaptic intracellular Ca2+ appeared necessary for the induction of LTP in these interneurons. 6. Incubation of slices with the inhibitor of nitric oxide synthase N omega-nitro-L-arginine methyl ester (100 microM) before and throughout the recording session also blocked the increase in EPSC amplitude at 5-10 min (5 cells) and 15-20 min (3 cells) after tetanization. NO synthesis may therefore be necessary for LTP in O/A interneurons. 7. These results suggest that LTP of excitatory synapses is selectively produced in O/A but not L-M interneurons, and that this LTP shares similar characteristics with LTP in hippocampal CA1 pyramidal cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1998

Modulation of human stratum corneum properties by salicylic acid and all-trans-retinoic acid.

Topical all-trans-retinoic acid (RA) has been reported to decrease the in vivo skin response to sodium lauryl sulfate (SLS). The converse was also shown with a synergistic effect of RA following prior applications of SLS. The reason for such effects is not clear. We employed measures of transepidermal water loss (TEWL), squamometry and sequential corneosurfametry to explore the protective activity of a 0.05% RA cream at the level of the stratum corneum. Nonionic oil-in-water emulsions with or without 5% salicylic acid (SA) served as test product references. Data indicated that the RA formulation was responsible for a stochastic impairment in the TEWL and for an increased intercorneocyte cohesion. SA and the unmedicated emulsion did not lead to similar TEWL changes. The squamometry test proved to be very sensitive to disclose the effects of SA and RA without, however, allowing to distinguish the difference in the physiological processes involved. The corneosurfametry bioassay did not show any protection or synergistic effect between RA or SA and SLS challenge on the stratum corneum. This is in contrast to a previous work showing a positive protective effect afforded by retinol against SLS. The combined effects of irritant compounds affecting the stratum corneum are complex. The precise reason for some of their biological consequences remains a conundrum. On balance, products such as SA and RA do not appear to afford protection or impairment to a surfactant challenge at the level of the stratum corneum.

Adult↗
PubMed2001

Facts and myths about electrical measurement of stratum corneum hydration state.

Some of the views presented in the chapter on 'Examination of stratum corneum hydration state by electrical methods' in Skin Bioengineering - Techniques and Applications in Dermatology and Cosmetology (Karger, 1998) are in strong disagreement with the results from basic research that has been conducted on skin impedance measurement over the last decades. This research has e.g. non-ambiguously shown that the frequency response of the stratum corneum does not obey the Cole equation and that measurement depth is strongly dependent on measurement frequency. One consequence of these findings is that multifrequency electrical measurements on stratum corneum are impossible to achieve in vivo with any electrode system known today. Hence, electrical measurements of stratum corneum hydration must be conducted at one single, low frequency.

Body Water↗
PubMed2003

Lipid composition of outer stratum corneum in hereditary palmoplantar keratodermas.

BACKGROUND: The analysis of lipid composition of the outer stratum corneum is a promising approach to study the pathophysiology of inherited disorders of keratinization. OBJECTIVE: The purpose of the study was the search for biochemical alterations of stratum corneum lipids in hereditary palmoplantar keratoderma (PPK). METHODS: Using high-performance thin-layer chromatography, we performed an analysis of all major stratum corneum lipid classes in scales of 29 patients with 8 different types of hereditary PPK. RESULTS: In comparison to the controls, slight differences in the lipid pattern were found in all keratodermas. Reduced amounts of total ceramides and increased levels of free fatty acids were noted in nearly all types. CONCLUSIONS: The study indicates that the abnormal composition of stratum corneum lipids in PPK is probably not caused by genetic defects of the epidermal lipid metabolism, but it appears to represent an epiphenomenon of a disturbed cornification.

Adolescent↗
PubMed1985

Demonstration of allospecific differences in human stratum corneum autoantibodies by blocking immunofluorescence.

Stratum corneum antibody titers of six normal human sera were determined by indirect immunofluorescence on three different epidermal substrates with and without preincubation of the substrates with one monkey serum. In three out of six human sera the reaction of stratum corneum antibodies was inhibited on all three substrates, in one serum the inhibition was noted on two out of three substrates and no effect was observed in two sera. These findings provide further evidence for the existence of allospecific stratum corneum antibodies in human sera and for the presence of both species-specific and species-nonspecific glycoprotein stratum corneum antigens in human epidermis.

Animals↗
PubMed1996

Effects of systemic treatment with statins on skin barrier function and stratum corneum water-holding capacity.

BACKGROUND: Topical application of inhibitors of HMGCoA reductase, the rate-limiting enzyme of cholesterol synthesis, has been shown to induce impairment of barrier function. OBJECTIVE: Assessing whether oral administration of statins used for reducing blood levels of cholesterol induces functional changes in stratum corneum barrier. MATERIALS AND METHODS: 69 subjects of both sexes under-going treatment for hypercholesterolemia (mean age 48 +/- 11 years) entered the study; 43 had been treated with simvastatin and 11 with pravastatin for 6 months; 15 only on dietary regimen served as controls. Efficiency of stratum corneum water barrier was evaluated by transepidermal water loss (TEWL) measurement using an evaporimeter; water-holding capacity of the stratum corneum was assessed by the sorption-desorption test measured by capacitance. Statistical analysis was performed using ANOVA. RESULTS: No differences were found between the groups (simvastatin, pravastatin, diet) concerning both basal TEWL and the dynamic of water binding in the stratum corneum. CONCLUSIONS: Prolonged treatment with cholesterol-lowering drugs based on inhibition of HMGCoA reductase does not alter the permeability barrier of the skin.

Administration, Oral↗
PubMed1983

Comparative investigations on the water content of the stratum corneum using different methods of measurement.

Measurements of the water content of the stratum corneum were made on the flexor side of the forearm in healthy male volunteers using direct current resistance and alternating current (1.5 and 15 kHz) electric impedance measurements, capacity measurements and measurements of transepidermal water loss. In addition, infrared-spectroscopic investigations were made using a Frustrated Multiple Internal Reflection device on unstripped skin, then on the same skin area after five and ten strippings with adhesive tape. The tests showed (except for the measurements of transepidermal water loss) all of the aforementioned test methods led to relevant measurement values. While the direct current electrical resistance measurement yielded data on the water content of the most superficial layer of the stratum corneum, it was found that the capacitor measurements gave results from the deep layers of the stratum corneum. With the alternating current impedance measurement method, both superficial and deep layers of the stratum corneum were taken into account. Comparative measurements of direct current resistance and infrared absorption after occlusion treatment revealed that under certain circumstances using both methods can lead to contradictory results.

Adult↗
PubMed1999

Changes in the skin's capacitance after damage to the stratum corneum in humans.

BACKGROUND: Wound healing is a complex process to study, especially in humans, because the endpoint(s) of wound-induction and healing are subjective and, therefore, difficult to quantitate. Experiments were performed to establish quantifiable endpoints during the wound-induction process in 15 humans (11 women, 4 men). OBJECTIVE: Measurement of the skin's capacitance was used as a marker for the three stages of wound healing: 1) establishment of a wound, 2) the healing process, and 3) complete re-epithelialization. METHODS: Superficial wounds in the epidermis were generated by tape stripping the skin on the arm of 15 healthy volunteers. The skin's capacitance was measured before tape stripping, at various time points during the induction of the wound, immediately after glistening of the epidermis was achieved, and when the wound had healed according to clinical assessment. RESULTS: The values of the skin's capacitance at the point of removal of the stratum corneum varied from one individual to the next. Furthermore, the number of adhesive cellophane-tape strips needed to remove the stratum corneum and achieve glistening, due to accumulation of moisture, differed greatly from one volunteer to the next. These experiments suggest that the number of tape strips needed to remove the stratum corneum varies with age, sex, and possibly ethnicity of the subject. By contrast, during the wound healing process when a scab could be visualized, the skin's capacitance measured -122 picofarads (pF). Moreover, when the scab had disappeared, the skin's capacitance returned to baseline values (0 pF). CONCLUSION: Measurement of the skin's capacitance is a useful tool to determine two endpoints in the wounding and healing processes. The presence of a scab and the re-establishment of an intact stratum corneum can be quantitated easily. Less amenable to quantitation is the exact pF value that correlates to a specific type of wound.

Adult↗
PubMed2006

Levels of retinyl palmitate and retinol in stratum corneum, epidermis and dermis of SKH-1 mice.

Vitamin A (retinol) regulates many biological functions, including epidermal cell growth. Retinyl palmitate (RP) is the major esterified form of retinol and the predominant component of retinoids in the skin; however, how endogenous levels of RP and retinol in the skin are affected by the age of the animal remains unknown. Furthermore, the levels of retinol and RP in the various skin layers - the stratum corneum, epidermis and dermis of skin - have not been reported. In this paper, we report the development of a convenient method for separation of the skin from SKH-1 female mice into the stratum corneum, epidermis, and dermis and the determination of the levels of RP and retinol in the three fractions by HPLC analysis. The total quantities of RP and retinol from the stratum corneum, epidermis, and dermis are comparable to those extracted from the same amount of intact skin from the same mouse. There was an age-related effect on the levels of RP and retinol in the skin and liver of female mice. An age-related effect was also observed in the stratum corneum, epidermis, and dermis. The levels of RP and retinol were highest in the epidermis of 20-week-old mice, and decreased when the age increased to 60- and 68-weeks. The total amount of RP at 20 weeks of age was found to be 1.52 ng/mg skin, and decreased about 4-fold at 60- and 68-weeks of age. A similar trend was found for the effects of age on the levels of retinol.

Age Factors↗
PubMed1996

Relationship between the amount of propranolol permeating through the stratum corneum of guinea pig skin after application of propranolol adhesive patches and skin irritation.

In the present study we evaluated the relationship between the cumulative amount of propranolol permeating through the stratum corneum and the formation of erythema, a skin irritation reaction, after transdermal application of adhesive patches containing propranolol to the skin of guinea pigs. The intensity of erythema was expressed in terms of a* values measured with a chromameter. The a* values increased in guinea pigs after application of the adhesive patches containing 0.4 mg/cm2 of propranolol to the skin. Since the adhesive patches showed good adhesion to the skin (propranolol content is less than the saturated concentration in the adhesive base) and the cumulative amount of propranolol permeating through the stratum corneum is small, the development of erythema was considered to be mainly due to physical factors such as peeling. Even in adhesive patches containing 0.8 mg/cm2 or 1.2 mg/cm2 of propranolol, a* values increased, although adhesion to the skin is low because of crystallization of propranolol in the adhesive base. On the other hand, in these two adhesive patches, the cumulative amount of propranolol permeating through the stratum corneum increased up to 24 h after application. These findings suggest that the skin irritation reaction is due to propranolol mainly absorbed transdermally, because there is a high correlation between the cumulative amount of propranolol permeating through the stratum corneum and the a* values (r = 0.928).

Administration, Cutaneous↗
PubMed1999

Improvement in the turnover rate of the stratum corneum in false aged model rats by the administration of geniposidic acid in Eucommia ulmoides Oliver Leaf.

We earlier reported that collagen synthesis in false aged model rats was stimulated by the administration of a methanol extract from the leaves of Eucommia ulmoides OLIVER. When the methanol extract was fractionated to n-hexane, ethyl acetate, acetone and methanol fractions by silica gel chromatography, we discovered that geniposidic acid and aucubin, contained in the acetone fraction, were the active ingredients. In the current study, we set out to examine if active compounds found in the Eucommia ulmoides OLIVER leaf (EUOL) improved the low turnover rate in the stratum corneum of false aged model rats. The turnover rate in the stratum corneum in rats was measured as 50% dansyl chloride clearance day. In the first experiment, administration of a 2.4% water soluble methanol extract (WSME) of EUOL, along with an 11% protein diet, led to a 20% higher turnover rate in the stratum corneum (p<0.05, Mann-Whitney) than the control value. The WSME mainly contained iridoid mono-glycosides such as geniposidic acid. In the second experiment, treatment with geniposidic acid similarly caused a higher turnover rate in the stratum corneum, increasing turnover by 23% (p<0.05, Mann-Whitney) compared to the control value. In this paper we reveal that the WSME contains compounds effective against aging, and one of them is geniposidic acid.

Aging↗
PubMed1993

Effects of oleic acid/propylene glycol on rat abdominal stratum corneum: lipid extraction and appearance of propylene glycol in the dermis measured by Fourier transform infrared/attenuated total reflectance (FT-IR/ATR) spectroscopy.

Fourie transform infrared/attenuated total reflection analysis demonstrated that the absorbance intensity of C = O stretching bands, which reflect the amounts of lipids in the stratum corneum, decreased with an increase in the duration of skin treatment with 0.15 M oleic acid/propylene glycol (PG) system, suggesting that the oleic acid/PG system induced the lipid extraction, which was followed by a reorganization of the stratum corneum structures. The spectral peaks which originated from the PG molecule were detected in dermal tissues after 30 min of treatment of the stratum corneum with the same system. This observation suggested that the reorganization of the lipid domains due to the lipid extraction by the oleic acid/PG system helped the PG molecules enter the dermal tissues. It was also suggested that an effective volume within the stratum corneum for solutes and/or solvents which could penetrate through the inter-, and/or intracellular routes could be altered in conjunction with the structural changes of the lipids.

Animals↗
PubMed2005

Effect of microdermabrasion on barrier capacity of stratum corneum.

A new microdermabrasion system is used for peeling the stratum corneum in a controlled manner. The system uses inert corundum powders under various degrees of vacuum. The fine corundum powders ejected by suction power, being quickly in contact with the skin surface, abrade and remove a tiny fragment of stratum corneum. The fraction of the stratum corneum removed by microdermabrasion can be controlled by the operating conditions; the duration of application (L) and the degree of vacuum setting (V). The stratum corneum barrier function with respect to the rate of skin penetration is well correlated by the product of the square of the degree of the vacuum and the duration of the probe setting.

Animals↗
PubMed2000

Topical application of 5-aminolevulinic acid hexyl ester and 5-aminolevulinic acid to normal nude mouse skin: differences in protoporphyrin IX fluorescence kinetics and the role of the stratum corneum.

An important limitation of topical 5-aminolevulinic acid (ALA)-based photodetection and photodynamic therapy is that the amount of the fluorescing and photosensitizing product protoporphyrin IX (PpIX) formed is limited. The reason for this is probably the limited diffusion of ALA through the stratum corneum. A solution to this problem might be found in the use of ALA derivatives, as these compounds are more lipophilic and therefore might have better penetration properties than ALA itself. Previous studies have shown that ALA hexyl ester (ALAHE) is more successful than ALA for photodetection of early (pre)malignant lesions in the bladder. However, ALA pentyl ester slightly increased the in vivo PpIX fluorescence in early (pre)malignant lesions in hairless mouse skin compared to ALA. The increased PpIX fluorescence is located in the stratum corneum and not in the dysplastic epidermal layer. In the present study, ALA- and ALAHE-induced PpIX fluorescence kinetics are compared in the normal nude mouse skin, of which the permeability properties differ from the bladder. Application times and ALA(HE) concentrations were varied, the effect of a penetration enhancer and the effect of tape stripping the skin before or after application were investigated. Only during application for 24 h, did ALAHE induce slightly more PpIX fluorescence than ALA. After application times ranging from 1 to 60 min, ALA-induced PpIX fluorescence was higher than ALAHE-induced PpIX fluorescence. ALA also induced higher PpIX production than ALAHE after 10 min of application with concentrations ranging from 0.5 to 40%. The results of experiments with the penetration enhancer and tape stripping indicated that the stratum corneum acts a barrier against ALA and ALAHE. Use of penetration enhancer or tape stripping enhanced the PpIX production more in the case of ALAHE application than in the case of ALA application. This, together with the results from the different application times and concentrations indicates that ALAHE diffuses more slowly across the stratum corneum than ALA.

Aminolevulinic Acid↗
PubMed1989

A light and electron microscopy study of normal human stratum corneum with particular reference to the intercellular space.

Intercellular and skin-surface substances, and exfoliating corneocytes, were clearly visualized by both light and electron microscopy. The intercellular space constituted an essential part of the normal human stratum corneum, in the basal and middle zones of which this space was filled with substances producing a compact appearance. The intercellular constituents were a nonhomogeneous substance, intact, single and "compound" lamellar granules and an intensely stained, membrane-like material that in some parts, but not in others, had a lamellar pattern. The artifacts produced by ultrathin sectioning for electron microscopy were too small to provide sufficient explanation for the porous appearance of the superficial zone. More important factors seemed to be enlargement of the intercellular space with decrease in the number of desmosomes and alterations of the intercellular substances, with decrease in the amount of nonhomogeneous substance and transformation of the single and "compound" lamellar granules into single and "compound" vesicular bodies. The hypothesis is advanced that the single and "compound" vesicular bodies together with the decreased amount of nonhomogeneous substance may contribute to maintain the patency of the intercellular space in the superficial zone (stratum disjunctum), thereby facilitating absorption of surface-applied agents into the stratum corneum by some shunt mechanism, while the content of the intercellular space in the basal and middle zones (stratum compactum) forms the principal barrier to free diffusion.

Adult↗