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Results for “Skin Absorption”

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At least 361 records · Page 20Linked to original sources
PubMed1989

Effects of long-term hydration leading to the development of polar channels in hairless mouse stratum corneum.

Dramatic increases in in vitro permeability coefficients have been observed following the long-term hydration (days) of hairless mouse skin. The effect is greatest for extremely polar or ionized solutes. Differential scanning calorimetry has been utilize in complementary studies in an attempt to assess if the altered permeability may be due to the irreversible alteration of lipid fluidity or keratin structure. The melting range of the lipid endotherms appears to be unaffected when stratum corneum is subjected to hydration conditions similar to those in the permeability experiments. Endotherms attributed to keratin appear to be altered by long-term hydration. However, no quantitative correlation was found between the keratin endotherm area and the permeabilities. The permeability data fit a model where the total permeability coefficient at a given time is the sum of the permeability coefficients associated with the lipid route and the polar route. Permeation increases with hydration time due primarily to alteration of the polar route. Based on molecular weight, no limitation of diffusion in the polar pathway was detected.

Animals↗
PubMed1995

Quantification of sodium lauryl sulfate penetration into the skin and underlying tissue after topical application--pharmacological and toxicological implications.

Sodium lauryl sulfate (SLS) is known to penetrate skin and cause cutaneous irritation. Some of these effects have been well-defined using bioengineering techniques. In this study, the ability of SLS to penetrate skin was quantified in a hairless rat model. In addition, local deep tissue penetration and systemic exposure to SLS were also evaluated to assess the toxic potential of topically applied SLS. SLS was observed to penetrate directly to a depth of about 5-6 mm below the applied site. Systemic redistribution was predominantly responsible in determining concentrations of SLS in tissues deeper than 5-6 mm. Epidermal concentrations of SLS after application of 1% (34 mM) aqueous SLS solution for 24 h were above the threshold levels which are known to evoke typical skin irritation responses. Deeper underlying tissues including dermis, subcutaneous, and muscle may also be exposed to high levels of SLS. Topically applied SLS was also observed in blood and contralateral tissues but the observed levels were not likely to elicit any systemic side effects at these doses. Traces of SLS were observed in tissues 7 days after single 24 h application of SLS, which supports the prolonged barrier disruption data generated using conventional bioengineering techniques. Cumulative treatment of SLS significantly increased the concentration of this compound in the underlying epidermis. The known preferential affinity of SLS for skin lipids and proteins was further confirmed by both in vitro and in vivo results. However, in vitro studies failed to predict the underlying tissue toxicity of SLS under the patch site when compared to the in vivo results. Such quantitative pharmacokinetic-pharmacodynamic correlations may be useful predictors for effective use of surfactants as penetration enhancers in cosmetic, pharmaceutical, and industrial applications.

Administration, Topical↗
PubMed2005

Determination of chemical agent optical clearing potential using in vitro human skin.

BACKGROUND AND OBJECTIVES: Optical clearing is a method that temporarily reduces the optical scattering of biological tissues. STUDY DESIGN/MATERIALS AND METHODS: To determine the optical clearing potential (OCP) of various chemical agents, we examined the change in reduced scattering coefficients of in vitro human skin after application directly to the dermal side. RESULTS/CONCLUSIONS: We found that the mean agent OCP did not correlate with refractive index or osmolality. Lipophilic hyperosmotic agents had a mean OCP less than unity, indicating increased optical scattering.

Culture Techniques↗
PubMed2006

Advances in MR imaging of the skin.

MR imaging of the skin is challenging because of the small size of the structures to be visualized. By increasing the gradient amplitude and/or duration, skin layers can be visualized with a voxel size of the order of 20 microm, clearly the smallest obtained for in vivo images in a whole-body imager. Currently, the gradient strength of most commercial systems enables acquisition of such a small voxel size, and the main difficulty has thus become to achieve sufficient detection sensitivity. The signal-to-noise ratio (SNR) can be increased either by increasing the magnetic field strength or by minimizing noise with small coils; cooling copper coils or superconducting coils can enhance the SNR by a factor of 3 or more. MR imaging, because of the large number of parameters it is able to measure, can provide more than the microscopic architecture of the skin: physical parameters such as relaxation times, magnetization transfer or diffusion, and chemical parameters such as the water and fat contents or phosphorus metabolism. In spite of the amount of information they have provided to date, MR imaging and spectroscopy have had limited clinical applications, mainly because cutaneous pathologies are easily accessible to the naked eye and surgery. However, MR technologies indeed represent powerful research tools to study normal and diseased skin.

Animals↗
PubMed1994

Improvement of epidermal differentiation and barrier function in reconstructed human skin after grafting onto athymic nude mice.

To determine whether epidermis reconstructed in vitro at the air-liquid interface on de-epidermized dermis has the capacity to normalize the expression of differentiation-specific markers, its lipid composition and stratum corneum barrier properties, human skin equivalents were transplanted onto athymic nude mice and investigated at different stages ranging from 1 to 4 months after grafting. Indirect immunofluorescence with species- or non-species-specific antibodies revealed that as early as 1 month after transplantation keratinization, and involucrin, loricrin and transglutaminase patterns were normalized. Human melanocytes were observed in the basal layer of the pigmented graft. As revealed by high-performance thin-layer chromatography and transmission electron microscopy after ruthenium tetroxide fixation, the lipid profile and the intracellular lamellar organization were similar to those found in natural epidermis. Transepidermal water loss measurements and penetration studies showed that the barrier properties of the reconstructed epidermis after transplantation were comparable to those of normal human skin.

Animals↗
PubMed1981

Nitroglycol concentrations in blood and urine of workers engaged in dynamite production.

Nitroglycol (Ng) concentrations in blood and urine of dynamite production workers were measured. Measurement of Ng concentration in blood of 16 workers revealed undetectable levels prior to work in all of them. The amounts of Ng detected after work were 0-145 ng/ml, high levels being noted in workers who had frequent exposure to skin absorption. Measurement of changes in blood Ng concentrations and the Ng excretion in urine in three workers during a week revealed no persistent trend in blood Ng concentrations but a tendency to higher Ng concentration in urine was found in the afternoon and in the morning with a higher concentration in the latter half of the week than during the first half. These results suggest the usefulness of the measurement of Ng urinary concentration excretion in the assessment of Ng absorption by the body. The relationship between the blood Ng concentrations in workers engaged in a dynamite factory and the experimental condition in dogs described in the previous report was assessed, and a valuable suggestion concerning further research in the study of chronic exposure to Ng at low concentrations was obtained.

Adolescent↗
PubMed1995

Carbon disulphide. II. Investigations on the uptake of CS2 and the excretion of its metabolite 2-thiothiazolidine-4-carboxylic acid after occupational exposure.

The reported investigations on the uptake of carbon disulphide (CS2) and the excretion of its metabolite 2-thiothiazolidine-4-carboxylic acid (TTCA) were based on results from 403 personal air samples (352 passive and 51 active samples) and 362 TTCA determinations in biological material measured during a field study on the adverse effects due to CS2 exposure. The external exposure ranged from below the detection limit (0.2 ppm) to 66 ppm and the urinary TTCA excretion from below the detection limit (0.16 mg./l) to 33.4 mg/l. The excretion of TTCA in postshift urine related to creatinine and volume showed a linear correlation to the CS2 air concentration. On the basis of these results the influence on the internal exposure of physical work load, dermal exposure and individual parameters (age, Brocaindex, disturbed skin barrier) was evaluated. Correlations between the TTCA values in the postshift urine and the individually measured CS2 concentrations were carried out separately for individual departments and persons with and without indications of a disturbed skin barrier. In order to be able to judge the individual internal exposure related to external exposure, a personal quotient was formed from the TTCA level in the urine and the CS2 air concentration measured on the same day (relative internal exposure RIE index = TTCA mg/g creatinine/CS2 in ppm). On investigating interindividual differences, higher relative internal exposures were found in persons with a heavy physical work load and more intensive skin contact. It could be shown for a large group of persons exposed to CS2 that a pathological skin condition leads to an increase in the dermal penetration rate of hazardous substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Impaired water barrier function in acne vulgaris.

In acne vulgaris, abnormal follicular keratinization is important for comedo formation, yet the precise mechanisms of comedogenesis are not known. The present study examined the interrelationship between sebum secretion rate (SSR), lipid content and water barrier function (WBF) of the stratum corneum (SC) in 36 acne patients and 29 control subjects. All major SC lipid classes were separated and quantified by thin-layer chromatography/photodensitometry. WBF was evaluated by measuring transepidermal water loss (TEWL), and the hygroscopic properties and waterholding capacity of the SC. The SSR over a period of 3 h was significantly higher in patients with moderate acne than in control subjects, but no significant difference was noticed between patients with mild acne and control subjects. Significant differences between patients with both moderate and mild acne and control subjects were noted in the amount of sphingolipids (ceramides and free sphingosine), but not for any other lipid classes. Furthermore in acne patients, lower amounts of sphingolipids were observed corresponding with a diminished WBF. These results suggest that an impaired WBF caused by decreased amounts of ceramides may be responsible for comedo formation, since barrier dysfunction is accompanied by hyperkeratosis of the follicular epithelium.

Acne Vulgaris↗
PubMed1993

When applied to facial skin, does estrogen ointment have systemic effects?

We examined cytological vaginal smears of 17 women before and after three months of dermal estrogen (1 g of 0.01% estradiol ointment or 0.3% estriol ointment once daily), applied to the face for dermatological indications. The mean age was 57.1 +/- 7.6 years (range from 46 to 66). Seven women had estrogenic smears (more than 10% superficial cells) before therapy. Nine women were treated with 0.01% estradiol ointment and 8 were treated with 0.3% estriol ointment. Both groups had gynecological examinations including cervical and vaginal smears before and after treatment and also monthly measurements of serum follicle-stimulating hormone, prolactin and estradiol levels. Serum hormone levels and the appearance of vaginal smears showed no significant change during treatment.

Aged↗