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PubMedDate not supplied

Variables associated with skin dryness in the elderly.

This study investigated whether sebum secretion and other external variables were associated with the occurrence of dry skin in the elderly. The sample consisted of 76 elderly white individuals ranging in age from 65 to 97 years who resided in retirement homes. Dry skin was measured through verbal report and verified by observation. Sebum was collected on dacron mesh disks and measured by quantitative thin layer chromatography. Other variables pertinent to the occurrence of dry skin were measured through structured interview. Dry skin was found in 59% of the subjects. Mean sebum secretion rate was .534 mg/10 sq cm/3 hr. Although sebum secretion rate was significantly lower in females than in males, p less than .001, sebum levels did not differ significantly as a function of dry skin for either sex. A significant association was found between severity of skin dryness and age, p less than .02. The findings refute the widely held, though untested belief, that the decreased sebaceous gland activity that accompanies aging is responsible for skin dryness in the elderly.

Age Factors↗
PubMed1982

The response of the sebaceous glands of female rats ovariectomized at birth to testosterone.

Newborn Sprague-Dawley rats were ovariectomized within 24 h of birth and control animals were sham-operated. Immediately, one-half of the rats in each group received a single injection of 500 micrograms testosterone propionate. The other half acted as a vehicle control. Normal male and female rats were also included for comparison. The secretion rate of sebum was measured at the age of 80 days from the amount of skin-surface lipids that could be extracted with acetone and which had been produced during 2 days. Male rats secreted more sebum than female rats. In female rats, irrespective the presence or absence of ovaries, when treated with a single injection of testosterone propionate at birth, although secreted significantly more sebum than vehicle control groups, the increase was still far below the level normally found in the male. On the other hand, implantation of testosterone pellet at the age of 4 weeks in neonatally ovariectomized-androgenized female rats greatly increased sebum secretion to an extent far exceeding that of the normal male rats. It is concluded that testosterone can directly increase sebum secretion in the female rats irrespective the presence or absence of ovaries when given at birth and reinforcement at about puberty produces a full effect of secretion.

Animals↗
PubMed2006

[Sebaceous glands as transporters of vitamin E].

Human sebum is produced by sebaceous glands and reaches the skin surface via secretion through the hair shaft. There is experimental evidence that the sebaceous glands and sebum serve as a transport mechanism taking the lipophilic antioxidant vitamin E from the blood to the skin surface. The highest levels of vitamin E are found in the sebum and in the skin lipid film in sebum-rich areas such as facial skin. Recent studies indicate that daily oral supplementation of moderate doses of alpha-tocopherol for at least 3 weeks leads to significant increases of vitamin E levels in human skin sites with a high density of sebaceous glands, such as the face. Thus, the potential photoprotective and antioxidants effects of oral vitamin E, as well as possibly other antioxidants, are site-dependent. These findings should be considered when designing clinical studies to assess the efficacy of oral antioxidants against oxidative stress in the skin.

Acne Vulgaris↗
PubMed1996

Body fat distribution, peripheral indicators of androgenic activity, and blood pressure in women.

This report analyzes the association between blood pressure and three indicators of peripheral androgenic activity (PIAAs): body fat distribution, hirsutism, and sebum production. Furthermore, it analyzes the associations among these PIAAs to understand whether they are indicators of the same androgenic pattern. The study was conducted among 314 healthy women, aged 35-69 years, participating in the baseline examination of the Study of Hormones and Diet in the Etiology of Breast Cancer (ORDET), an Italian cohort study of breast cancer. Body fat distribution was measured as the ratio of waist-to-hip circumference (waist-to-hip ratio). Three hirsutism scores were developed by use of factor analysis after nine areas of androgen-sensitive, pilo-sebaceum units of the body were examined. Sebum production was measured by a sebumeter. Results indicated a positive correlation between the waist-to-hip ratio and the lip hirsutism score (r = 0.157). Conversely, sebum production correlated negatively with both the lip hirsutism score (r = -0.154) and the waist-to-hip ratio (r = -0.153). By use of multiple regression and with adjustment for age and body mass index, the waist-to-hip ratio was found to be positively and significantly related to both diastolic and systolic blood pressure, whereas sebum production was inversely and significantly related to both diastolic and systolic blood pressure. The facial hirsutism score was positively related to systolic blood pressure, while the limb hirsutism score was inversely and significantly related to diastolic blood pressure. Finally, interrelationships among these markers of androgenic activity were found to be weak, suggesting that these markers may be under the influence of local metabolism of the androgenic steroids. Further hormonal analyses are needed to determine whether PIAA measures obtained in epidemiological settings are useful in study of androgenic patterns and blood pressure.

Adult↗
PubMed2006

Dissolution of materials in artificial skin surface film liquids.

The dissolution of chemical constituents from jewelry, textiles, cosmetics, drugs, industrial chemicals, and particles in direct and prolonged contact with human skin is often assessed in vitro using artificial skin surface film liquids (SSFL). To provide meaningful results, the composition of artificial SSFL should accurately mimic human sweat and sebum, and the conditions of the in vitro test system should accurately reflect in vivo skin conditions. We summarized the reported composition of human SSFL and compared it to 45 different formulations of artificial sweat and 18 formulations of artificial sebum (studies published from 1940 to 2005). Conditions of in vitro dissolution test systems were reviewed and compared to in vivo skin conditions. The concentrations of individual constituents and pH of artificial sweat and concentrations of artificial sebum constituents are not always within ranges reported for human SSFL. Nearly all artificial SSFL lack many of the constituents in human SSFL. To develop a comprehensive model SSFL, we propose a standard SSFL, modified from the two best published sweat and sebum formulations. Little is known concerning the influence of test system conditions on dissolution, including SSFL temperature, container material composition, agitation, and physicochemical properties of the test article on dissolution. Thus, both a need and an opportunity exist for standardizing the composition of artificial SSFL and in vitro dissolution test methodologies. To standardize in vitro dissolution test systems, we recommend: maintaining artificial SSFL at a biologically relevant temperature appropriate to the human activity being modeled, carefully selecting test and sample storage containers to avoid bias in dissolution measurements, accounting for friction between a test article and skin in a biologically plausible manner, and physicochemical characterization of the test article or material to better understand mechanisms of dissolution and potential mechanisms of toxic action of dissolved material. More accurate modeling and better understanding of chemical dissolution from articles in contact with the skin will ultimately improve risk decision making, thereby protecting even the most susceptible persons from adverse health effects resulting from skin exposure.

Animals↗
PubMed2000

Physical properties of a silicone prosthetic elastomer stored in simulated skin secretions.

STATEMENT OF PROBLEM: Facial prostheses worn over an extended time are exposed to various environmental factors, including sebaceous oils (sebum) and perspiration. PURPOSE: This study investigated the physical properties of tensile strength and modulus, elongation, tear strength, hardness, weight, and color change, of a silicone facial elastomer after immersion for 6 months in simulated sebum and perspiration at 37 degrees C. MATERIAL AND METHODS: Specimens made of Episil silicone elastomer were immersed in simulated alkaline or acidic perspiration as well as in sebum. Tensile and tear tests were conducted according to ISO specifications no. 37 and 39, respectively, in a Monsanto testing machine. Shore A hardness measurements were run according to ASTM D 2240. Weight changes were followed at 5, 15, 30, and 180 days, and color changes were determined in the CIE LAB system using a tristimulus colorimeter. RESULTS: An improvement of mechanical properties for specimens immersed in acidic perspiration was attributed to facilitation of the propagation of cross-linking reaction during aging of the silicone samples. Some weight increase was observed for the specimens immersed into the aqueous solution, whereas for those immersed in sebum, weight loss was recorded, probably because of extraction of some compounds. In this latter case, the color change was lower than that corresponding to simulated perspiration. CONCLUSION: The silicone specimens aged for a period, which simulates 1.5 years of clinical service, showed minimal changes with respect to the properties studied.

Absorption↗
PubMed1986

Essential fatty acids and acne.

Acne is characterized by hyperkeratosis of the follicular epithelium, leading to horny impactions that may lie dormant as open or closed comedones or may cause inflammation of the follicle. Although persons with acne have consistently been observed to have elevated levels of sebum secretion, no mechanism relating sebum secretion rates to comedogenesis is known. Acne patients have also been shown to have low levels of linoleic acid in their skin surface lipids. To explain this observation, the hypothesis is advanced that the linoleate concentration in human sebum depends on the quantity of linoleic acid present in each sebaceous cell at the commencement of its differentiation and on the extent to which this initial charge is diluted by subsequent endogenous lipid synthesis in each sebaceous cell. A corollary hypothesis holds that low concentrations of linoleate in sebum impose a state of essential fatty acid deficiency on the cells of the follicular epithelium and induce the characteristic response of hyperkeratosis. Both hypotheses could hold, without there being a systemic deficiency of linoleic acid, simply as the result of elevated lipogenesis in individual sebaceous cells.

Acne Vulgaris↗
PubMed2003

Skin biophysical properties of a population living in Valais, Switzerland.

BACKGROUND/PURPOSE: Switzerland has one of the highest rates of skin diseases and particularly skin cancer, in Europe. Skin elastosis, roughness and atopy are also frequent. High UV exposure and prevalence of light skin individuals could be the cause. Valais, in Southern Switzerland, is a mountain region with elevated sun irradiation and low air humidity, an ideal location to study the effect of the environment and life style on skin biophysical characteristics. The purpose of the study was to measure skin biophysical parameters non-invasively on healthy subjects living in Valais, and to correlate the measures with their life style. METHODS: One hundred and ten women were examined between October 2001 and February 2002. Measures of skin hydration, sebum content, pH and visco-elasticity were taken in a closed environment with constant temperature and controlled air humidity, utilizing commercially available non-invasive devices. Subjects were interviewed using a questionnaire and data on personal traits and life style were collected. Correlations between subject's skin parameters and life style were statistically examined. RESULTS: On average we observed low values of skin capacitance that identify subjects with dry skin. Measures of skin visco-elasticity ratios were also particularly low, while skin pH and sebum content were in the normal range. Age was correlated with a decrease of skin elasticity and sebum content, but there was no correlation with hydration or pH. CONCLUSIONS: We confirm, as reported in other studies, the effect of age on skin elasticity and sebum content and we identify, for the first time, a region with a population characterized by particularly low levels of skin hydration and skin visco-elasticity. Although people examined were free of skin diseases, we believe that protection from the sun and treatment of skin with hydrating products need to be emphasized as a prevention strategy, in regions such as Valais, with high sun irradiation and low humidity.

Adolescent↗
PubMed1985

Proportions of various straight and branched fatty acid chain types in the sebaceous wax esters of young children.

The fatty acid composition of sebaceous wax esters was examined in 20 children, ages 6-8, using quartz capillary gas chromatography. The results were compared with a previously reported study of wax ester composition in 10 adults, in which the same analytical techniques were used. The children's wax esters showed more variability in the proportions of all fatty acid chain types than was found in adults. The most striking difference between the 2 age groups was in the proportions of iso-branched fatty acids with odd numbers of carbon atoms. These ranged from 1-26% of fatty acids in the children's wax esters but were not more than 3% of fatty acids in the adults' wax esters. Some of the variability in wax ester fatty acid composition in children seemed to be related to variation in rates of sebum production. The highest percentages of terminally branched (iso-even, iso-odd, and anteiso) and the lowest percentages of internally branched fatty acids were found in the children with the lowest rates of sebum secretion. However, even in children with similar rates of sebum secretion there were considerable differences in wax ester fatty acid composition, especially with respect to iso-even fatty acids. The results suggest that sebum fatty acid composition is influenced both by genetic factors and by limitations on the supply of precursors for terminally branched, but not internally branched, fatty acids.

Adult↗
PubMed2004

Topical aminolaevulinic acid-photodynamic therapy for the treatment of acne vulgaris: a study of clinical efficacy and mechanism of action.

BACKGROUND: Acne affects 83-95% of 16-year-olds of both sexes, and many seek help from a clinician. Emerging problems with conventional acne treatments, specifically antibiotic resistance of Propionibacterium acnes and fears over the safety and tolerance of oral isotretinoin, create a demand for novel treatment modalities in acne. OBJECTIVES: To study the efficacy of aminolaevulinic acid-photodynamic therapy (ALA-PDT) in the treatment of acne and to identify the mode of action, looking specifically at the effects on surface numbers of P. acnes and on sebum excretion. METHODS: Ten patients (nine men and one woman, age range 16-40 years) with mild to moderate acne on their backs were recruited. Each patient's back was marked with four 30-cm2 areas of equal acne severity. Each site was then randomly allocated to either ALA-PDT treatment, light alone, ALA alone or an untreated control site. At baseline, numbers of inflammatory and noninflammatory acne lesions were counted, sebum excretion measured by Sebutapes (CuDerm, Dallas, TX, U.S.A.) and surface P. acnes swabs performed. ALA cream (20% in Unguentum Merck) was applied under occlusion to the ALA-PDT and ALA alone sites for 3 h. Red light from a diode laser was then delivered to the ALA-PDT and light alone sites (635 nm, 25 mW cm(-2), 15 J cm(-2)). Each patient was treated weekly for 3 weeks. At each visit acne lesion counts were performed and 3 weeks following the last treatment sebum excretion rates and P. acnes swabs were repeated. RESULTS: There was a statistically significant reduction in inflammatory acne lesion counts from baseline after the second treatment at the ALA-PDT site but not at any of the other sites. No statistically significant reduction in P. acnes numbers or sebum excretion was demonstrated at any sites including the ALA-PDT site. CONCLUSIONS: ALA-PDT is capable of clinically improving acne. An alternative mode of action for ALA-PDT other than direct damage to sebaceous glands or photodynamic killing of P. acnes is suggested from the results of this study.

Acne Vulgaris↗
PubMed1994

Effects of castration and testosterone on Fel dI production by sebaceous glands of male cats: I--Immunological assessment.

Fel dI is produced by salivary and sebaceous glands. Hormonal control of sebum production is clearly established. The influence of cat castration and supplementary treatment with testosterone on the production of sebum and Fel dI in cat skin have been researched in this study. On day 1, 12 male cats were anaesthetized and three skin areas carefully shaven. Then the level of lipids on skin surface was measured by means of a photometric method. Finally, the three areas of skin were washed with 5ml of distilled water through a plastic cylinder. Fel dI collected in the washes was measured with a two-site monoclonal antibody based ELISA. On day 2, six cats were castrated, the other six were used as a control group. Two and 4 weeks later, the levels of lipids and Fel dI in skin washes were measured again in all cats. On day 30, the six castrated cats were injected intramuscularly with prolonged-action testosterone. Two weeks later, quantification of lipids and Fel dI in all animals was repeated. Sebum and Fel dI levels decreased in all castrated animals. Injecting the castrated cats with testosterone led to a significant increase in sebum and Fel dI production. Our findings indicate that Fel dI production is influenced by the production of hormones.

Allergens↗
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↗
PubMed1988

Concentrations of isotretinoin and the arotinoid Ro 15-0778 in plasma and tissues of hamsters and rats.

The arotinoid Ro 15-0778 is a potent inhibitor of sebum secretion in rodents but not in humans, while isotretinoin (13-cis-retinoic acid, Accutane) inhibits sebum secretion in rodents and humans. The concentrations of Ro 15-0778 and isotretinoin were determined in plasma and target tissues of castrated, testosterone-stimulated hamsters after oral and topical dosing and in castrated, testosterone-stimulated rats after oral dosing. Comparison of this concentration data to that obtained in the plasma and sebum of humans after dosing with Ro 15-0778 and with isotretinoin did not explain why Ro 15-0778 was a potent inhibitor of sebum production in rodents but not in humans.

Administration, Oral↗
PubMed1977

Effect of sex and age at gonadectomy on the sebaceous response to progesterone.

The effect of progesterone on the rate of sebum secretion was examined in intact and gonadectomized rats. In intact, adult, male rats, progesterone administered for 3 weeks decreased sebum secretion; after castration of adult males, progesterone increased sebum secretion and an even greater response occurred in male castrated at 21 days of age. In intact, adult, female rats progesterone slightly increased sebum production. As in the male, the response was affected by the time of gonadectomy, a greater response occurring after spaying at 21 days compared with 10 weeks of age. Thus, the response to progesterone in the adult rat differs in intact males and females and is affected by changes in the endocrine environment induced by gonadectomy, especially near the time of puberty.

Age Factors↗
PubMed1993

Circadian variations in the number of actively secreting sebaceous follicles and androgen circadian rhythms.

Sebum excretion has been shown to demonstrate a circadian rhythm using a gravimetric method (cigarette paper). With the newly introduced method of Sebutape, we confirmed this periodicity and showed that the elevation in sebum excretion is correlated with an increase in the number of secreting follicles. We found, furthermore, that the number of secreting follicles on the forehead showed a distinct and statistically significant circadian rhythmicity, in contrast to those of the chest, which remained almost constant. The quantification in plasma levels of cortisol, melatonin, delta-4-androstenedione, dehydroepiandrosterone sulphate, and free testosterone showed no correlation with sebum excretion at either site. These observations suggest that local factors are involved in control of sebum secretion.

Adult↗
PubMed1992

Sebaceous gland lipids.

Human sebum contains squalene, wax esters, triglycerides, cholesterol esters, and possibly free cholesterol. The fatty acids of the ester lipids include species with chain branching or with unusual double-bond positions. The alcohol moieties of the wax esters contain unusual chain types similar to those of the fatty acids. Genetic and hormonal factors cause individual differences in sebaceous lipid composition. Genetic factors seem to influence the proportions of the various types of branched-chain fatty acids. Androgenic stimulation of the glands causes an increase in lipid synthesis, and therefore in the ratio of endogenously synthesized lipid to exogenous lipid. Because the endogenously synthesized lipids tend to be different from lipids that are derived exogenously, the overall composition of the secretion changes. Differences in sebum composition are particularly evident when the sebum of prepubertal children is compared with that of young adults. One difference that may be of clinical significance is the different concentrations of linoleate. Higher concentrations of sebum linoleate may protect young children from comedonal acne by preventing an essential fatty acid deficiency from developing in the follicular epithelium.

Fatty Acids↗
PubMed1978

Effect of progesterone on the sebaceous glands.

The effect of progesterone on the rate of sebum secretion was examined in intact and gonadectomized male and female rats. In intact adult male rats, progesterone administered for 3 weeks decreased sebum secretion, whereas in intact adult female rats, progesterone slightly increased sebum production. In castrated adults progesterone increased sebum secretion in both sexes, a greater response occurring after castration at 21 days of age than after castration at 10 weeks. Thus, the response to progesterone in the adult rat differs in intact males and females and is affected by changes in the endocrine environment induced by gonadectomy, especially near the time of puberty.

Animals↗
PubMedDate not supplied

Effects of donor age and contamination level of dioxins and related chemicals on frequency of sister chromatid exchanges in human lymphocytes cultured in vitro.

Frequencies of sister chromatid exchanges (SCEs) of human lymphocytes in control (DMSO treated) and 7,8-benzoflavone (ANF) treated cultures were measured in 39 healthy Japanese people and examined in connection with donor age. Both the control (baseline) and ANF induced SCE rates were significantly enhanced with age and highly positive correlation was observed between them. Therefore, in vivo aging seemed to have some effects on the frequencies of SCEs in human lymphocytes cultured in vitro. Concentrations of PCDDs, PCDFs and Co-PCBs in the blood and sebum of face were determined in the same Japanese subjects. Significantly positive correlation was observed between the blood and sebum in their total TEQ levels. Hence, PCDDs, PCDFs and Co-PCBs, which have been contaminating human bodies, are considered proportionally excreted from the sebum of face or body. Their total TEQ concentrations were also meaningfully increased with donor age in the sebum of face as well as in the blood. Either the baseline or ANF induced SCE frequencies was not enhanced with the total TEQ levels in the blood. Therefore, background levels of their contamination seem not to affect the SCE rates of the lymphocytes in the control and ANF treated cultures.

Adult↗