Degree Of Skin Pigmentation Research Articles

A comparative study of an advanced skin imaging system in diagnosing facial pigmentary and inflammatory conditions

Visual assessment, while the primary method for pigmentation and erythema evaluation in clinical practice, is subjective, time-consuming, and may lead to variability in observations among clinicians. Objective and quantitative techniques are required for a precise evaluation of the disease's severity and the treatment's efficacy. This research examines the precision and utility of a newly developed skin imaging system in assessing pigmentation and erythema. Sixty participants were recruited, and their facial images were analyzed with the new OBSERV 520 x skin imaging system, compared to DERMACATCH for regional analysis and VISIA for full-face examination. The degree of skin pigmentation was clinically graded using the MASI scores evaluated by dermatologists. The data revealed positive correlations between the novel skin imaging system and the two conventional instruments in quantifying pigmentation and erythema, whether in regional or full-face analysis. Furthermore, the new skin imaging system positively correlated with the clinical MASI scores (r = 0.4314, P < 0.01). In contrast, our study found no significant correlation between the traditional system and clinical assessment, indicating a more substantial capacity for hyperpigmentation assessment in the new system. Our study validates the innovative skin imaging system's accuracy in evaluating pigmentation and erythema, demonstrating its feasibility for quantitative evaluation in both clinical and research purposes.

Comprehensive analysis and novel insights into the efficacy of polymyxin B sulfate in the treatment of sepsis caused by carbapenem-resistant gram-negative bacteria.

To investigate and analyze the clinical efficacy and safety of polymyxin B sulfate in the treatment of carbapenem-resistant gram-negative bacteria (CR-GNB) in sepsis; in order to provide reference for the clinical diagnosis, treatment and prognosis evaluation of sepsis. The clinical data of 76 patients with CR-GNB sepsis treated with polymyxin B sulfate combined with an anti-infection regimen in the First Affiliated Hospital of Gannan Medical University from January 2020 to February 2024 were retrospectively studied. To analyze and discuss the clinical characteristics, results of the bacterial culture and drug sensitivity, clinical efficacy and prognosis of CR-GNB patients, efficacy comparison of different doses of polymyxin B sulfate treatment regimens, efficacy comparison of different combination regimens based on polymyxin B sulfate, changes in clinical indexes before and after treatment of polymyxin B sulfate, adverse drug reactions and adverse events of polymyxin B sulfate were investigated. A total of 76 patients with CR-GNB sepsis were included in this study, with 55 males and 21 females, with an average age of 59.86 years old, 44 of which were (57.89%) were > 60 years old. All patients included in this study were treated with polymyxin B based combination therapy, 49 cases (64.47%) received the two-drug combination regimen, 27 cases (35.53%) received the three-drug or more combination regimen, and all the patients had the above treatment followed by systematic symptomatic supportive treatment. Patients in this study received polymyxin B for an average of (8.6±4.3) days, there were 60 (78.95%) patients with effective clinical treatment, and 49 patients (64.47%) achieved pathogen (bacterial) clearance of infection. Twenty-two cases (28.95%) died within 28 days, 31 cases (40.79%) died within 90 days, and the remaining 23 cases (30.26%) survived. There were statistically significant differences in the therapeutic effective rates and bacterial clearance rates among different courses of treatment or different initial doses of polymyxin B (all P < 0.05). Moreover, there were significant differences in APACHE II score, WBC, NE, HGB, platelet count, albumin, NT-proBNP and CRP before and after polymyxin B treatment (all P < 0.001). In this study, 7 cases (9.21%) developed drug-related kidney injury, which recovered or decreased below the pre-medication level after discontinuation or dose adjustment and infection control. Skin darkening (melanin deposition) occurred in 5 cases (6.58%), and the above patients basically returned to normal several months after withdrawal of the drug, but there was still a certain degree of skin pigmentation. Meanwhile, 3 cases (3.95%) had neurotoxic reactions, mainly manifested as numbness at the extremities, and the neurotoxic symptoms were improved after reducing the dosage. Accordingly, there was no statistically significant difference in the prognosis of CR-GNB sepsis patients between different age and gender groups (all P > 0.05), while the treatment course and dosage of polymyxin B had statistically significant effects on the prognosis of CR-GNB sepsis patients (all P < 0.05). A Polymyxin B sulfate based combination regimen is an effective choice for CR-GNB sepsis, which can maximize the survival and prognosis benefits of sepsis patients.

Predicting alternate light absorption in areas of trauma based on degree of skin pigmentation: Not all wavelengths are equal

Detection and documentation of bruises on survivors of intimate partner violence (IPV) can provide valuable evidence to support investigation and subsequent prosecution of these crimes. Detection of bruises in persons with darker skin tones is often difficult, contributing to disparities in health and criminal justice responses to IPV. The purpose of this secondary data analysis was to determine whether use of an alternate light source (ALS) increased the predictive probability of successfully detecting bruises on diverse skin tones following a history of physical trauma. In this study, data were analyzed from a convenience sample of 157 subjects inclusive of six skin tones (very light, light, intermediate, tan, brown, dark) with induced bruises. Bruises were assessed under white light and an ALS 21 times over four weeks using 10 different ALS wavelength and goggle color combinations. Data analyzed included 31,841 skin observations obtained over 2897 participant assessments. Multilevel modeling was used to account for the correlation among the repeated measurements for each bruise. Across all categories of skin pigmentation, ALS wavelengths 415 nm and 450 nm viewed through a yellow filter had the most frequent detections of bruises (415 nm: n = 2777, 11.2%; 450 nm: n = 2747, 11.1%) and greater predictive probability of a positive finding (415 nm: 0.90–0.99; 450 nm: 0.85–0.99) than white light (n = 2487; 10%; 0.81–0.90). These two ALS wavelengths were the only combinations that provided greater probability of detection than white light on groups with darker skin (brown or dark), whereas additional ALS wavelengths/filters worked equally well on groups with lighter skin. Findings suggest use of an ALS in clinical assessments of patients of color who report IPV may help reduce health and criminal justice-related disparities.

A local rapid temperature rise model for analyzing the effects of irradiation on human skin in laser treatments

In laser treatments, the difference in patient's degree of skin pigmentation is an important factor that can lead to medical accidents. However, the conventional heat transfer model is not available to analyze the effect of degree of pigmentation on the laser treatments. Therefore, we propose a new microscopic radiation heat transfer model that takes into account the point heat sources for the laser treatments. In the proposed model, skin considered as a bulk medium consisting of two layers, namely normal and pigmentation layers with the latter containing a larger number of melanosomes having a specific volume fraction (fv,mel) as the degree of pigmentation. Using the proposed model, it was found that the distribution of the absorbed laser energy and temperature rise of the skin tissue is affected by the degree of pigmentation. When fv,mel is high, the absorbed energy per single melanosome and thus the temperature rise of the pigmentation layer is lower than that in the deeper skin tissue. It was also shown that depending on fv,mel, the distance between melanosomes decreases. When fv,mel is high, the temperature of skin tissue between melanosomes increases.

The First Human Clinical Trial on the Skin Depigmentation Efficacy of Glycinamide Hydrochloride

A previous study identified certain low molecular anti-melanogenic peptides that share a common sequence with α-melanocyte stimulating hormone (MSH) and end with a glycinamide moiety. Glycinamide itself also showed anti-melanogenic activity in cell-based assays, but neither glycine nor acetyl glycinamide were active, which indicated a special structure and activity relationship. The aim of this study was to examine the skin depigmentation efficacy of glycinamide hydrochloride in human subjects. The primary skin irritation potential of glycinamide hydrochloride was evaluated by patch testing in 30 human subjects. The skin depigmentation efficacy of glycinamide hydrochloride was evaluated in a double-blinded clinical test in 21 human subjects. The test product and a control product were applied to designated sites on the right or left side of the face twice daily for eight weeks. Skin color parameters, i.e., the melanin index, the L* value (representing skin lightness), a* value (redness), and b* value (yellowness) were measured using instruments. The individual topology angle (ITAo, representing skin color) was calculated from L* and b values. The degree of skin pigmentation was visually assessed by two testers. The primary skin irritation test showed that a solution containing glycinamide hydrochloride up to 10% did not induce any adverse skin responses. In the efficacy test, the test product significantly reduced the melanin index, and increased L* value and ITAo after two weeks of application relative to the baseline value at the start of the test. It also significantly lowered the degree of pigmentation after 6 weeks of application, relative to the baseline value. Differences in the melanin index, L* value, ITAo and the degree of pigmentation between the test and control groups became statistically significant after six weeks or eight weeks of application. No signs of skin irritation were observed during the efficacy test. The present study suggests that glycinamide hydrochloride has great potential to be used in the control of skin hyperpigmentation.

Mathematical Models to Predict Maternal Vitamin D (VitD) Status During Pregnancy and Lactation

Abstract Objectives VitD status is important during pregnancy and lactation as maternal status is linked with fetal and neonatal outcomes: Maternal vitD status during pregnancy predicts neonatal vitD status; similarly, maternal vitD status during lactation predicts infant vitD status as mother is the sole source of vitD to the unsupplemented lactating infant. The best indicator of vitD status is measurement of circulating 25(OH)D concentration; however, results may be delayed and add to health care costs. A prediction model taking into account certain factors would assist health care providers in identifying those individuals most at risk for vitD deficiency. OBJ: Develop and test a prediction model for vitD status that utilizes information readily available to any health care provider in the primary care setting. Methods Three existing datasets (2 pregnancy, n = 405; and 1 lactation, n = 451; total n = 856 women) were combined for development of this prediction model. Variables included in the linear regression models to predict maternal total circulating 25(OH)D at baseline were maternal race/ethnicity, location/study site, maternal age, degree of skin pigmentation (forehead, forearm, inner arm, stomach and knee), body mass index (BMI), season (April-October and November-March) and vitD intake. To test the data, each woman was randomized to either the training dataset (80%) or to the testing dataset (20%). The fitted model was used to predict circulating 25(OH)D concentration in the testing dataset. Results In the full linear regression model, race, season, center, and age were significant predictors of the log transformed 25(OH)D (P-value &amp;lt; 0.05) and the prediction error was 12.97%. When only the significant predictors of the full model were applied in a submodel, the prediction error rose to 15.92%. The best model for prediction of 25(OHD) in this study was the full model. Conclusions The ability to predict vitD status from readily available sociodemographic and clinical parameters is possible with an accuracy of 87%. When only significant factors were utilized to predict vitD status, the accuracy fell slightly. Mathematical prediction models as shown in this example allow accurate prediction of particular health risk factors and will likely play a role in advancing nutritional and medical therapies. Funding Sources NCATS/NIH #UL1 TR001450

Frequency of folate-related polymorphisms varies by skin pigmentation.

Folate-mediated 1-carbon transfer processes are vital in human health but are susceptible to independent and interactive influences of genetic variance and environmental exposures. Evidence suggests folate levels may be impacted by genetic variance and environmental UVR, with the effect of UVR levels influenced in part by degree of skin pigmentation. Folate-related genes are also influenced by UVR levels; however, the potential relationship between key folate-related genes and skin pigmentation has not yet been explored. The purpose of this study was to examine potential associations between frequencies of key folate variants and degree of skin pigmentation. Association between population prevalence of 17 variants in 9 folate-related genes (MTRR, MTR, MTHFR, CBS, SHMT1, MTHFD1, RFC1, BHMT, TYMS) and the Fitzpatrick skin phototype of populations was assessed via collation of genotypic data from ALFRED (Allele Frequency Database) and 1000 Genomes databases. A significant association between variant frequency and Fitzpatrick phototype was observed for 16 of 17 examined variants (P < .0029 Bonferroni corrected significance threshold in all cases). These findings demonstrate novel relationships between skin color and folate-related genes, with trends suggesting folate genotypes are selected to maintain homeostasis in the folate system under differing UVR conditions.

Laser acupuncture improves skin color deformation by cupping: A pilot study.

Negative pressure of cupping induces skin deformation such as ecchymosis and purpura in a circular shape. Thus, there is a desire to treat skin before depigmentation and scarring occurs. Therefore, we introduce laser therapy, a widely used technique treat pigmentation in dermatology. Various parameters of laser therapy can be applied, so to determine the optimal exposure parameters that do not damage the surrounding tissues, the subjects were divided into four groups: a non-stimulation group and three laser groups (4 J/cm2 group, 6 J/cm2 group, and 8 J/cm2 group). We selected the wavelength and output of laser as follows: 660nm and 50mW. The 40 were divided into four groups of 10. In the first experiment, we measured skin temperature using Digital infrared thermography in order to observe whether the laser could cause heat damage. In the second experiment, each group received the assigned laser therapy protocol every 24 hours for 72 hours. We obtained a skin image using a cross polarization technique. Previous studies have shown that a*and E.I (erythema index) represent the degree of skin erythema (hemoglobin content). M.I (melanin index) indicates the degree of skin pigmentation (melanin content). Hence, skin color information was analyzed with the a*, erythema index (E.I), and melanin index (M.I) for 72 hours. None of the laser exposure parameters led to skin damage by heating or energy dissipation. The results of a*, E.I, and M.I of all groups showed the different recovery rates towards the normal skin color information before cupping. As energy density increases, the result of a* and E.I showed the fast recovery rate. There was no significant different between M.I at non-stimulation group and M.I at 4 J/cm². Therefore, the least energy density as 6 J/cm² is need for the recovery of melanin content. The a*, E.I, and M.I at 8 J/cm² group rather than other groups were significantly recovered to normal skin color. In conclusion, the laser therapy (energy density: 8 J/cm²) has a significant recovery of the skin erythema and skin pigmentation except to skin damage.

The Influence of Pigment Transfer on the Risk of Developing Melanoma: The Significance of the Melanocyte ‘Amputation Cycle’

It has been shown that cancer incidence is not only a function of the size of the population at risk but is strongly associated with the turnover rate of the tissue concerned. There is a strong negative correlation between melanoma incidence and the degree of skin pigmentation, and yet the melanocyte density is the same for all races. The proposal advanced in this communication is that the probability of undergoing malignant change is critically dependent on the melanocyte turnover and that this is regulated by the pigmentation process. In melanocytes, the division rate is influenced by the process of pigment donation, probably by a mechanism whereby the continual cytoplasmic loss due to cytocrine transfer of melanosomes (termed the ‚Amputation Cycle‚) inhibits replication. Consequently the turnover of melanocyte stem cells in heavily pigmented epidermis will be diminished, and this is held to account for the strong negative correlation between the degree of skin pigmentation and melanoma incidence.

Protective effects of adipose-derived stem cells against UVB-induced skin pigmentation

Background: Hyperpigmentation, mainly following UV-irradiation, can cause major cosmetic concerns. Human adipose tissue-derived stem cells (ASCs) have been reported to serve as whitening agents through a paracrine effect. However, there have been few reports on the direct effects of ASCs on skin pigmentation following UVB-irradiation.Methods: To evaluate the effect of ASCs on UVB-irradiated mouse skin, UVB-irradiation alone was applied to one side of the backs of mice (melanin-processing hairless mouse, HRM-2) as a control, and UVB-irradiation plus injection of ASCs was applied to the contralateral side. Skin pigmentation and histology were evaluated and the number of DOPA-positive melanocytes in the mouse skin was counted. The absolute value of ΔL* via a colorimeter was measured to evaluate the degree of skin pigmentation. The effects of ASCs on the melanogenic activities of mouse skin were examined by measuring the tyrosinase activity and the melanin contents in the epidermis of the mouse skin.Results: Skin pigmentation was suppressed in the ASC-injected side. Moreover, the change in skin thickness following UVB irradiation was reduced in the ASC-injected side. The number of DOPA-positive melanocytes in the ASC-injected side (139 ± 18 cells/mm2) was significantly lower than that in the control side (239 ± 48 cells/mm2). The tyrosinase activity (67.4 ± 9.8% of that of the control side) and melanin content (63.4 ± 5.7% of that of the control side) of the ASC-injected side were also significantly reduced.Conclusions: Collectively, these results suggest that ASCs injected subcutaneously into the backs of mice can attenuate tanning following UVB-irradiation, through suppression of tyrosinase activity.

Liquid Crystal Gel Reduces Age Spots by Promoting Skin Turnover

Studies have shown that liquid crystals structurally resembling the intercellular lipids in the stratum corneum can beneficially affect the skin when applied topically by stimulating the skin’s natural regenerative functions and accelerating epidermal turnover. In the present study, the effects of applying low concentrations of a liquid crystal gel of our own creation were evaluated using epidermal thickening in mouse skin as an assay for effective stimulation of epidermal turnover. A liquid crystal gel was also applied topically to human facial skin, and analysis was conducted using before-and-after photographs of age spots, measurements of L* values that reflect degree of skin pigmentation, single-layer samples of the stratum corneum obtained via tape-stripping, and measurements of trans-epidermal water loss that reflect the status of the skin’s barrier function. The results suggested that cost-effective creams containing as low as 5% liquid crystal gel might be effective and safely sold as skin care products targeting age spots and other problems relating to uneven skin pigmentation.

Spectrometer for fluorescence–reflection biomedical research

A fluorescence–reflection multichannel fiber spectrometer has been developed that makes it possible to carry out a wide range of biomedical research, including estimating the concentration of glycation end-products in the skin and the oxidation–reduction state of various tissues. It has the feature of being able to simultaneously record diffuse reflection spectra and fluorescence emission. The fluorescence is excited by an LED that emits at 365 nm. The fluorescence spectra are recorded in the 400–750 nm region, while the reflection spectra are recorded in the 350–750 nm region. The convergence of the results of the measurements is 1.6%. A technique is proposed for correcting the autofluorescence index of the skin that makes it possible to sharply reduce its dependence on the degree of skin pigmentation. The possibilities of the device are illustrated by examples of biomedical research.

Effects of sunlight on behavior and 25-hydroxyvitamin D levels in two species of Old World fruit bats

It has long been accepted that most vertebrate animals meet their vitamin D requirements from exposure of skin to UV-B (UV-B) radiation. Many factors affect this endogenous synthesis of vitamin D, including season, latitude, time of day, age, presence of hair, and degree of skin pigmentation. Most bats roost in dark places by day and forage at night, and thus have little or no potential for sunlight exposure. Notwithstanding, some tropical species are diurnal and are known to roost in the canopy of trees where they may be exposed to sunlight for up to 12 h each day. In this study, two species of captive tropical bats (both species are active at night but one, Rousettus aegyptiacus, roosts in caves, tombs, and buildings, whereas the other, Pteropus hypomelanus, roosts in trees) were evaluated for their ability to endogenously synthesize vitamin D. Following timed periods of sunlight exposure, blood plasma was analyzed using a competitive protein binding assay (CPBA) to determine concentrations of 25-hydroxyvitamin D [25(OH)D], the major circulating vitamin D metabolite. The ability to photoconvert provitamin D (7-dehydrocholesterol, 7-DHC) in the sub-tropical winter was determined using sunlight exposed borosilicate samples of 7-DHC in hourly increments. Finally, both species were evaluated in their preference for a roost site by the release of individuals into sunlight or shade in timed trials. Our results support the hypotheses: (1) when exposed to natural sunlight, both species exhibited an ability to endogenously synthesize vitamin D, although significant differences were found between the two, (2) photoconversion of 7-DHC to previtamin D3 is possible during the mid-day hours of a sub-tropical winter day and (3) captive, cave roosting R. aegyptiacus will choose shaded roost sites while captive P. hypomelanus will show no preference for either shade or sun.

Dose-effect relationship between Q-switch ruby laser and skin pigmentation in Guinea pigs

Objective To investigate the dose-effect relationship between Q-switch ruby laser and skin pigmentation in Guinea pigs. Methods Ten Guinea pigs were included in this study, and the back of each pig was divided into 5 areas, negative control area receiving no UVB irradiation or laser treatment, positive control area receiving UVB irradiation but no laser treatment, low-, middle- and high-dose areas receiving UVB irradiation followed by the treatment with laser at an energy density of 1.5, 3.0 and 6.0 J/cm2 for 4, 2, and 1 session, respectively, with an interval of 1 week. Melanin content index (MCI) was determined, and confocal laser scanning microscopy (CLSM) and histopathology were performed to observe melanin granules and melanocytes in the skin tissue from Guinea pigs before the initial laser treatment, 2 and 4 weeks after the final laser treatment. Results The best response was observed in the low-dose areas, and there was a complete clearance of hyperpigmentation in these areas, which maintained 8 weeks without recurrence, while different degrees of skin pigmentation recurred in the middle- and high-dose areas. Moreover, the low-dose areas showed a significantly lower melanin content index (MCI) compared with the middle- and high-dose areas (F = 4.2,P < 0.05), together with a marked reduction in the extent of pigment deposition, melanin granules, melanocyte number and density. Conclusions The efficacy of Q-switched ruby laser on skin pigmentation in Guinea pigs is correlated with the energy density and treatment frequency, and, low intensity and high frequency are often associated with a better treatment outcome. Key words: Lasers; Skin pigmentation; Dose-response relationship, radiation; Guinea pigs

Acral Melanocytic Nevi: Prevalence and Distribution of Gross Morphologic Features in White and Black Adults

To determine prevalence and morphologic features of acral melanocytic nevi in white and black adults. Point prevalence survey. Outpatient dermatology clinic. Convenience sample of subjects 18 years or older. Prevalence and morphologic features based on ethnicity, sex, and age. Palmar or plantar nevi were detected in 42.0% of blacks (50 of 119) vs 23.0% of whites (79 of 343) (P < .001). Palmar or plantar nevi of 6-mm diameter or larger were detected in 3.4% of blacks (4 of 119) vs 0.6% of whites (2 of 343) (P = .04). Diffusely black acral nevi were uncommon in whites (0 of 343) and blacks (1 of 119). The prevalence of palmar or plantar nevi increased directly with degree of skin pigmentation (P < .001). In whites, this prevalence was greater in women (27.1%, 51 of 188) than in men (18.1%, 28 of 155) (P = .047); in subjects younger than 50 years (30.8%, 57 of 185) than in those 50 years or older (13.9%, 22 of 158) (P < .001); in subjects with a history of atypical nevus removal than in those without (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.9-6.9); in those with at least 1 extant atypical nevus than in those without (OR, 3.2; 95% CI, 1.7-6.0); and in those with at least 20 nevi of 2-mm diameter or larger than in those without (OR, 3.0; 95% CI, 1.6-5.6). Acral nevi appear to be associated with ethnicity, pigmentation, age, and cutaneous melanoma (CM) risk factors. While relatively large and/or very darkly pigmented acral nevi appear to be more common in blacks than in whites, diffusely black acral nevi are uncommon in both groups. These findings are relevant to the assessment of pigmented lesions in the differential diagnosis of acral CM.

Serum 25-hydroxyvitamin D status of vegetarians, partial vegetarians, and nonvegetarians: the Adventist Health Study-2

BackgroundVegans and other vegetarians who limit their intake of animal products may be at greater risk of vitamin D deficiency than nonvegetarians, because foods providing the highest amount of vitamin D per gram naturally are all from animal sources, and fortification with vitamin D currently occurs in few foods. Objective:We assessed serum 25-hydroxyvitamin D [s25(OH)D] concentrations and factors affecting them in vegetarians, partial vegetarians, and nonvegetarians in a sample of calibration study subjects from the Adventist Health Study-2. Design:Food-frequency questionnaires and sun-exposure data were obtained from 199 black and 229 non-Hispanic white adults. We compared s25(OH)D concentration, dietary and supplemental vitamin D intake, and sun exposure in the different dietary groups. Results:We found no significant difference in s25(OH)D by vegetarian status for either white or black subjects. Among whites, dietary vitamin D intake and sun behavior were different between vegetarian groups, but there was no difference in skin type distribution. Among blacks, no significant differences were observed for any of these variables between vegetarian groups. The mean (±SD) s25(OH)D was higher in whites (77.1 ± 10.33 nmol/L) than in blacks (50.7 ± 27.4 nmol/L) (P < 0.0001). Conclusions:s25(OH)D concentrations were not associated with vegetarian status. Other factors, such as vitamin D supplementation, degree of skin pigmentation, and amount and intensity of sun exposure have greater influence on s25(OH)D than does diet.

Racial/ethnic considerations in making recommendations for vitamin D for adult and elderly men and women

Vitamin D is acquired through diet and skin exposure to ultraviolet B light. Skin production is determined by length of exposure, latitude, season, and degree of skin pigmentation. Blacks produce less vitamin D3 than do whites in response to usual levels of sun exposure and have lower 25-hydroxyvitamin D [25(OH)D] concentrations in winter and summer. Blacks in the United States also use dietary supplements less frequently than do whites. However, blacks and whites appear to have similar capacities to absorb vitamin D and to produce vitamin D after repeated high doses of ultraviolet B light. There is a growing consensus that serum 25(OH)D concentrations of at least 75-80 nmol/L are needed for optimal bone health, on the basis of studies of older white subjects living in Europe and the United States. The studies show that increasing serum 25(OH)D concentrations to this level decreases parathyroid hormone (PTH) concentrations, decreases rates of bone loss, and reduces rates of fractures. Among US blacks, low 25(OH)D concentrations are associated with higher concentrations of PTH, which are associated with lower bone mineral density. Vitamin D supplements decrease PTH and bone turnover marker concentrations among blacks. These findings suggest that improving vitamin D status would benefit blacks as well as whites. On the basis of studies conducted in the temperate zone, the intake of vitamin D3 needed to maintain a group average 25(OH)D concentration of 80 nmol/L in winter is approximately 1000 IU/d. Broad-based vitamin D supplementation is needed to remove vitamin D insufficiency as a contributing cause of osteoporosis.

Disturbed melanin synthesis and chronic oxidative stress in dysplastic naevi

Dysplastic naevi (DN) are a known risk factor for malignant melanoma. Their occurrence is closely connected with the degree of skin pigmentation. People with a light complexion are more likely to develop DN than dark-skinned individuals. We examined the proposition that DN exhibit altered melanin formation, which may be involved in their malignant transformation. X-ray microanalysis was used to study the composition of melanosomes from DN and to compare the results with those obtained from melanomas, banal (dermal) naevi and normal cutaneous melanocytes. We analysed sulphur (an indicator of phaeomelanin) and two metals, iron and calcium, involved in oxidative stress. FACS analysis of dihydrorhodamine-123-labelled cells was employed to quantify differences in the production of radical oxygen species in DN cells and normal skin melanocytes. A significantly higher sulphur content was found in melanosomes from DN cells and melanoma cells when compared with normal melanocytes and naevus cells from banal naevi. In addition, melanosomes of DN cells and melanoma cells contained higher amounts of iron and calcium. In the case of calcium, this was associated with a significantly elevated cytoplasmic concentration. FACS analysis showed that DN cells exhibited higher concentrations of radical oxygen species than normal skin melanocytes from the same individuals. We propose that increased phaeomelanogenesis in DN cells is connected with oxidative imbalance, which is reflected by increased intracellular concentrations of reactive oxygen species and raised calcium and iron concentrations. We show that the metabolic alterations in DN cells resemble those found in melanoma cells. Our findings provide support for the idea that DN cells are true precursor lesions of melanoma.

Determination of keratin protein in a tape-stripped skin sample from jet fuel exposed skin.

Chemical contaminants or their metabolites may bind to and react with keratin proteins in the stratum corneum of the skin. Here, we present a tape-stripping method for the removal and quantification of keratin from the stratum corneum for normalization of extracted concentrations of naphthalene (as a marker for jet fuel exposure) from 12 human volunteers before and after exposure to jet fuel (JP-8). Due to the potential for removal of variable amounts of squamous tissue from each tape-strip sample, keratin was extracted and quantified using a modified Bradford method. Confirmation of the extraction of keratin was verified by western blotting using a monoclonal mouse anti-human cytokeratin antibody. Naphthalene was quantified in the sequential tape strips collected from the skin between 10 and 25 min after a single dose of JP-8 was initially applied. The penetration of jet fuel into the stratum corneum was demonstrated by the fact that the average mass of naphthalene recovered by a tape strip decreased with increased exposure time and subsequent tape strips and that the evaporation of naphthalene was observed to be negligible. There were no significant differences in the amount of keratin or naphthalene removed by tape strips between males and females, between age groups, races or degrees of skin pigmentation. We conclude that (i) the amount of keratin removed with tape strips was not affected by up to a 25 min exposure to JP-8 and (ii) there was a substantial decrease in the amount of keratin removed with consecutive tape strips from the same site, thus, adjusting the amount of naphthalene by the amount of keratin measured in a tape-strip sample should improve the interpretation of the amount of this analyte using this sampling approach. Although we found that normalization of the naphthalene to the amount of keratin in the tape-strip samples did not affect the ability of this method to quantify the dermal exposure to JP-8 under these laboratory conditions, the actual concentration of naphthalene (as a marker for JP-8 exposure) per unit of keratin in a tape-strip sample can be determined using this method and may prove to be required when measuring occupational exposures under field conditions.

Risk assessment of side effects from copper vapor and argon laser treatment: the importance of skin pigmentation.

Epidermal melanin is a limiting factor for obtaining beneficial results in dermatological treatment of vascular malformations. The aim of our study was to predict the highest laser intensity and energy fluence which can be applied to skin with different degrees of pigmentation before side effects are induced. Thirteen human volunteers with different degrees of skin pigmentation were laser-treated on the inside of the brachium with an argon laser (AL, 488 nm and 514.5 nm) and a copper vapor laser (CVL, 578 nm), both connected to a Hexascan. Three input intensities were used. 0.7, 1.0, and 1.3 W. Pulse duration was kept constant at 200 msec, resulting in hexascan fluences of 14.1, 20.2, and 26.2 J/cm2. At the 6-month assessment it was noted whether pigmentary changes or scarring were clinically absent or present. The results were analysed by logistic regression. We found that pretreatment pigmentation percentage and laser intensity were significant risk factors of inducing side effects (P < .001), whereas it was without significant importance whether the AL or the CVL was used (P > .05). Contour lines of 1, 2.5, 5, 10, 25, and 50% risk levels of inducing clinically recognizable pigmentary changes and scarring were calculated. Pigmentary changes occurred at a significantly lower intensity level than skin texture changes (P = .006). On basis of our results, we recommend assessment of skin pigmentation prior to laser treatment with the CVL and the AL, and we recommend that the illustrated risk levels are taken into consideration.