Hand eczema in children referred for patch testing: North American Contact Dermatitis Group Data, 2000-2016

BACKGROUND

Little is known about the aetiologies and relevant allergens in paediatric patients with hand eczema (HE).

OBJECTIVES

To characterize the aetiologies and determine the proportion of positive and currently relevant allergens in children/adolescents (age < 18 years) with HE referred for patch testing.

METHODS

A retrospective analysis (2000-2016) of North American Contact Dermatitis Group data was performed.

RESULTS

Of 1634 paediatric patients, 237 (14·5%) had involvement of the hands. Final physician diagnoses included allergic contact dermatitis (49·4%), atopic dermatitis (37·1%) and irritant contact dermatitis (16·9%). In multivariable logistic regression models, employment was the only association with increased odds of any HE or primary HE. Children with HE vs. those without HE had similar proportions of positive patch tests (56·1% vs. 61·7%; χ² -test, P = 0·11). The five most common currently relevant allergens were nickel, methylisothiazolinone, propylene glycol, decyl glucoside and lanolin. In multivariable logistic regression models of the top 20 relevant allergens, HE was associated with significantly higher odds of currently relevant reactions to lanolin, quaternium-15, Compositae mix, thiuram mix, 2-mercaptobenzathiazole and colophony. The allergens with the highest mean significance-prevalence index number were methylisothiazolinone, carba mix, thiuram mix, nickel and methylchloroisothiazolinone/methylisothiazolinone.

CONCLUSIONS

Children with HE who were referred for patch testing had a high proportion of positive patch tests, which was similar to the proportion found in children without HE. Children with HE had a distinct and fairly narrow profile of currently relevant allergens.

Inhibition of MMPs Cat G and downregulates the signaling of TGF-β/Smad in chronic photodamaged human fibroblasts

OBJECTIVE

To understand the action of Cathepsin G (Cat G) and matrix metalloproteases (MMPs) on the β/Smad pathway of transforming growth factor β (TGF-β) in chronically photodamaged human fibroblasts. Cat G plays a significant role in the process of skin photoaging and in collagen synthesis and degradation which is induced by UV irradiation it could interact with TGF-β/Smad signaling. No available studies have thoroughly explored its molecular mechanisms of photoaging regulation.

PATIENTS AND METHODS

Fibroblasts were divided into 4 groups: (1) control, (2) UVA irradiation of 25 J/cm2, (3) UVA irradiation of 25 J/cm2 + MMPs inhibitor, and (4) 25 J/cm2 UVA irradiation + Cat G inhibitor. All treatments were repeated daily for 21 days. Western blot and ELISA was employed to detect Protein levels for Cat G, MMPs, and several smads.

RESULTS

Compared to UVA-irradiated cells, the addition of MMPs inhibitor downregulated the expression of smad2, smad3, and smad4 as well as TGF-β. The addition of Cat G inhibitor downregulated the expression of smad2, smad3, and smad4 as well as TGF-β. These data suggest that TGF-β/Smad signaling was decreased by inhibition of MMPs and Cat G decreased in chronically human fibroblasts which are photo-damaged.

CONCLUSIONS

These results may help expand our knowledge of mechanisms mediating photoaging and is possibly instrumental to the exploration of novel anti-photoaging treatments.

The three moments of skin cream application: an evidence-based proposal for use of skin creams in the prevention of irritant contact dermatitis in the workplace

Contact dermatitis is one of the most common occupational diseases, with serious impact on quality of life, lost days at work and a condition that may be chronically relapsing. Regular prophylactic skin cream application is widely acknowledged to be an effective prevention strategy against occupational contact dermatitis; however, compliance rates remain low. To present a simple programme for skin cream application in the workplace with focus on implementation to drive down the rate of occupational irritant contact dermatitis, an expert panel of eight international dermatologists combined personal experience with extensive literature review. The recommendations are based on clinical experience as supported by evidence-based data from interventional studies. The authors identified three moments for skin cream application in the work place: (i) before starting a work period; (ii) after washing hands; and (iii) after work. Affecting behaviour change requires systematic communications, monitoring and reporting, which is proposed through Kotter's principles of organizational change management. Measurement tools are provided in the appendix. Interventional data based on application of this proposal is required to demonstrate its effectiveness.

Effect of ultrasound and heat on percutaneous absorption of l-ascorbic acid: human in vitro studies on Franz cell and Petri dish systems

OBJECTIVE

Percutaneous absorption of l-ascorbic acid (LAA) is limited due to its high hydrophilicity and low stability. Here, we investigated the effect of post-dosing sonophoresis (329 kHz, 20 mW cm^-2 ) and heat (36°C) on transdermal delivery of LAA.

METHODS

Ultrasound/heat, heat and control treatments were applied on skin surface for 2 and 5 min after topical application of C14-labelled LAA aqueous solution. After 15 min post-exposure, radioactivity was measured in tape-striped stratum corneum (TS-SC), epidermis, dermis and receptor fluid. As Franz diffusion cell model may have different acoustic response than in vivo human tissues, a novel Petri dish model was developed and compared with Franz cell model on the effects of ultrasound/heat treatment on the skin permeability.

RESULTS

Five-min ultrasound/heat treatment significantly accelerated skin absorption/penetration of LAA; 2-min treatment showed no enhancement effect on Franz diffusion cell model at the end of experiment. The use of Petri dish model significantly increased LAA concentrations in epidermis after 5 min of ultrasound/heat treatment, compared to the results of Franz cell model.

CONCLUSION

Combination of ultrasound (329 kHz, 20 mW cm^-2 ) and heat (36°C) significantly enhanced LAA transdermal penetration, when the time of treatment was sufficient (5 min). As Petri dish model was designed to simulate acoustic respond of dense human tissue to ultrasound, the difference between Franz cell and Petri dish models suggests that the enhancement effect of ultrasound/heat on skin penetration in vivo may be greater than that determined on in vitro Franz cell model.

Pharmacodynamic measurements of methyl nicotinate percutaneous absorption

The local kinetics of percutaneous absorption provide information of relevance to the treatment of skin diseases and to the potential efficacy of transdermally delivered chemotherapy for systemic effect. This paper describes two non-invasive procedures (laser Doppler velocimetry and photopulse plethysmography) which permit pharmacodynamic measurements of methyl nicotinate skin penetration to be made in vivo in man. The methods are sensitive to the local vasodilative action elicited by the nicotinic acid ester. Dose-response behavior as a function of time has been monitored (1) over the concentration range 5-100 mM, and (2) by variation of drug application time and administration area. At the higher concentrations used, the magnitude of the erythemal response is saturable, and the effect is then progressively prolonged by further increasing the applied dose. Analysis of the data permits assessment of (a) the kinetics of drug delivery to and depletion from the site of action, and (b) the hypothetical level of steady state drug input necessary to sustain 50 % of the maximum detected response. Measurements of the type described here may prove useful, therefore, for elucidating otherwise inaccessible aspects of transcutaneous kinetics in vivo.

Skin benefits with a novel emollient-treated menstrual pad

Manufacturers of consumer products consistently seek to improve marketed products in terms of both safety and efficacy. The desire for continued improvement is seen even in well-established products such as catamenial products which have existed in some form for thousands of years. A recent innovation in the design of menstrual pads is the addition of a surface finish of emollient for the purpose of increasing comfort during wear. The present paper presents different evaluations of such an emollient-treated menstrual pad with a novel absorbent core. These investigations demonstrated product tolerability, defined the optimal formulation and concentration of the emollient-containing finish, and demonstrated successful transfer of the emollient to the relevant skin surface. In addition, enhancement of skin moisturization, associated with exposure to the emollient-treated pad, was demonstrated by several technologies: assessment of skin moisturization by Corneometer®, skin friction testing, and skin capacitance.

Nail apparatus melanoma: is trauma a coincidence? Is this peculiar tumor a real acral melanoma?

Nail Apparatus Melanoma (NAM) is rare, particularly in Caucasians. Understanding its pathogenesis and collecting epidemiologic data may be difficult due to its location and the exiguity of the case series of this cancer. Cutaneous melanoma has been thought related to UV radiation, and NAM is considered an acral variant of melanoma, even if the nail presents a specific anatomy. Little is reported about pathogenesis, except reports suggesting traumatic injuries as a causal factor. UV exposure is debated in nail melanoma because of its structure. The nail is, in fact, a unique structure with sun-exposed and non exposed melanocytes. NAM arises from the nail melanocytes, located in the nail matrix, which is the germinative part of the nail and composed of a proximal and distal portion. The proximal nail matrix lays under the proximal nail fold that covers it and is non-sun exposed, while the distant nail matrix, clinically visible as the lunula, is sun-exposed, though lying underneath the nail plate. According to these anatomical data, NAM is a distinct melanoma type, and studies need to classify it as acral melanoma or as a particular type of melanoma with its own pathogenesis and prognostic criteria. This study investigates potential risk factors of NAM, emphasizing (i) trauma and (ii) UV exposure among our NAM patients.

Age-related percutaneous penetration part 2: effect of age on dermatopharmacokinetics and overview of transdermal products

Transdermal drug delivery allows for a constant rate of drug administration and prolonged action, which can be beneficial to elderly patients who are often polymedicated. Several studies have compared dermatopharmacokinetics in the young and elderly with conflicting results. Despite the potential limitations of age-related changes in skin factors and cutaneous metabolism, marketed transdermal products generally do not report age-related differences in pharmacokinetics. This overview discusses the current data, summarizes marketed product findings and highlights the importance of further studies to evaluate age-related dermatopharmacokinetics.

Age-related percutaneous penetration part 1: skin factors

Changes in the skin that occur in the elderly may put them at increased risk for altered percutaneous penetration from pharmacotherapy along with potential adverse effects. Skin factors that may have a role in age-related percutaneous penetration include blood flow, pH, skin thickness, hair and pore density, and the content and structure of proteins, glycosaminoglycans (GAGs), water, and lipids. Each factor is examined as a function of increasing age along with its potential impact on percutaneous penetration. Additionally, topical drugs that successfully overcome the barrier function of the skin can still fall victim to cutaneous metabolism, thereby producing metabolites that may have increased or decreased activity. This overview discusses the current data and highlights the importance of further studies to evaluate the impact of skin factors in age-related percutaneous penetration.

Evaluation of incidental thyroid nodules in patients with primary melanoma

AIM

Literature data have suggested an increase of incidental thyroid nodules in patients with malignancies, including melanoma.

METHODS

The ultrasound findings of 168 consecutive melanoma patients were revisited in order to evaluate the presence of incidental thyroid nodules and the results were compared with clinical features, Breslow thickness and the rate of malignancy of incidental thyroid nodules.

RESULTS

We observed that: 1) incidental thyroid nodules are more frequent in patients affected by melanoma (60.6%) than in the healthy population; 2) no statistically significant difference were found in thyroid involvement on the basis of gender and age; 3) incidental thyroid nodules frequency is increased in patients with thinner melanoma and this increase is more evident if we consider melanoma in situ and female patients; 4) it was not detected malignant incidental thyroid nodules.

CONCLUSION

The data revealed a high frequency of incidental thyroid nodules in patients with melanoma, suggesting that it is necessary to study this association in a larger group of patients, also including age/gender matched controls.

Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects. Current knowledge assembled at an international workshop at BfR, Germany

Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German ‘Federal Institute for Risk Assessment’ hosted an ‘International Workshop on Contact Dermatitis’. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15–20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed.

Pragmatic approach to the clinical work-up of patients with putative allergic disease to metallic orthopaedic implants before and after surgery

Allergic complications following insertion of metallic orthopaedic implants include allergic dermatitis reactions but also extracutaneous complications. As metal-allergic patients and/or surgeons may ask dermatologists and allergologists for advice prior to planned orthopaedic implant surgery, and as surgeons may refer patients with complications following total joint arthroplasty for diagnostic work-up, there is a continuous need for updated guidelines. This review presents published evidence for patch testing prior to surgery and proposes tentative diagnostic criteria which clinicians can rely on in the work-up of patients with putative allergic complications following surgery. Few studies have investigated whether subjects with metal contact allergy have increased risk of developing complications following orthopaedic implant insertion. Metal allergy might in a minority increase the risk of complications caused by a delayed-type hypersensitivity reaction. At present, we do not know how to identify the subgroups of metal contact allergic patients with a potentially increased risk of complications following insertion of a metal implant. We recommend that clinicians should refrain from routine patch testing prior to surgery unless the patient has already had implant surgery with complications suspected to be allergic or has a history of clinical metal intolerance of sufficient magnitude to be of concern to the patient or a health provider. The clinical work-up of a patient suspected of having an allergic reaction to a metal implant should include patch testing and possibly in vitro testing. We propose diagnostic criteria for allergic dermatitis reactions as well as noneczematous complications caused by metal implants.

Transdermal estradiol and testosterone transfer in man: existence, models, and strategies for prevention

BACKGROUND

Transdermal hormone application allows delivery of a clinically relevant hormone dose often with fewer systemic side effects than oral formulations. However, transdermal hormone transfer from a dosed individual to naïve interpersonal contact occurs and may cause significant hormone imbalance and adverse effects.

METHODS

We reviewed PubMed, Medline, and Scopus articles from the years 1950 to 2010 for articles related to transdermal hormone transfer in the setting of in vivo and in vitro human and animal models. We used the following key words: transfer, transdermal, absorption, cutaneous, hormone, estradiol, and testosterone. Unpublished trials were reviewed on the US Food and Drug Administration (FDA) website for product approval.

RESULTS

Data reflecting in vivo transfer of transdermal estradiol and testosterone in man is available from case reports, clinical trials, and FDA product information. While results clearly show that transfer can occur, methods for measuring the effect are not standardized and are thus difficult to compare among positive and negative studies. No in vitro human studies or animal models have been developed to specifically examine transfer potential of transdermal estradiol or testosterone.

CONCLUSION

It is necessary to consider the mechanism behind transdermal hormone transfer and consider ways to enhance clinical benefits to the dosed individual while minimizing transfer to a naïve interpersonal contact. A detailed discussion of trial comparisons and future optimization methods may help enhance our understanding of the potential for transdermal hormone transfer and encourage development of newer formulations and/or application methods to minimize its occurrence.

Expression of cathepsins in human skin photoaging

Cathepsins are involved in regulatory mechanisms in human skin, but their role in photoaged skin remains unknown. This study investigates the role of cathepsin B, D, K, and G in skin photoaging in vivo and in vitro. Cathepsin-induced changes in skin as a result of chronic UV irradiation were detected by immunohistochemistry methods. Protein cathepsin expressions in UVA-induced premature senescence in fibroblasts in vitro were detected by Western blot technique. Cathepsin mRNA expression in photoaged skin and fibroblasts was detected by real-time reverse transcription-polymerase chain reaction. Immunohistochemistry and Western blot show lower protein expression of cathepsin B, D, and K in photoaged skin and fibroblasts, while cathepsin G was higher. The mRNA expression of cathepsin B, D, and K of the photoaged skin in vivo decreased to 20 ± 0.5, 25 ± 1.6 and 22 ± 0.8%, while cathepsin G mRNA increased to 2.24 ± 0.09 times that of control. In photoaged fibroblasts, cathepsin B, D, and K mRNA was downregulated to 64 ± 2.9, 24 ± 2.1 and 9 ± 0.5% while cathepsin G mRNA was upregulated to 1.42 ± 0.06 times that of control fibroblasts. These experiments suggest that cathepsin B, D, K, and G may act as biomarkers in photoaged human skin.

Elastic vesicles as topical/transdermal drug delivery systems

Skin acts a major target as well as a principle barrier for topical/transdermal drug delivery. Despite the many advantages of this system, the major obstacle is the low diffusion rate of drugs across the stratum corneum. Several methods have been assessed to increase the permeation rate of drugs temporarily. One simple and convenient approach is application of drugs in formulation with elastic vesicles or skin enhancers. Elastic vesicles are classified with phospholipid (Transfersomes((R)) and ethosomes) and detergent-based types. Elastic vesicles were more efficient at delivering a low and high molecular weight drug to the skin in terms of quantity and depth. Their effectiveness strongly depends on their physicochemical properties: composition, duration and application volume, and entrapment efficiency and application methods. This review focuses on the effect of elastic liposomes for enhancing the drug penetration and defines the action mechanism of penetration into deeper skin.

Chondrodermatitis nodularis chronica helicis in monozygotic twins

Chondrodermatitis nodularis chronica helicis (CNCH) is a benign inflammatory nodule of the helix. Patients report severe tenderness upon pressure. Commonly seen in middle-aged men, there are no reports of this disease in twins. We report middle-aged male monozygotic twins who simultaneously developed CNCH. This suggests, but does not prove, the possibility of a hereditary factor in the pathogenesis of CNCH.

Many common drugs in dermatology are light, temperature, or moisture-sensitive

Photosensitivity is defined as responsiveness to light exposure. For many common dermatologic drugs, proper storage conditions are essential for maintaining drug activity. Degradation and loss of activity can occur with exposure to light, temperature, and/ or moisture. For example, ketoconazole degrades after 24 hours of light exposure. In this article storage guidelines for common dermatology drugs are provided. We suspect that drug degradation is common due to improper storage and that improved patient instruction regarding storage will reduce degradation and alleviate some of the danger associated with improper storage and usage patterns.

Tape stripping on a human nail: quantification of removal

BACKGROUND/PURPOSE

Tape stripping is commonly used to investigate the stratum corneum (SC). This study assesses if protein quantitative tape stripping method was suitable for human nails.

METHOD

We used a colorimetric method to quantify proteins removed by the tape. Water barrier functions as a result of tape stripping were also observed by changes in transonychial water loss (TOWL) from the baseline.

RESULTS

Using tape stripping, we observed no difference between nails in the protein quantity removed by tape stripping (P=0.39). The mean TOWL before and after tape stripping were 6.9 and 9.3 g/m2/h, respectively; this was significantly increased in tape stripped nails (P<0.0001).

CONCLUSION

Tape stripping seems to be an effective method to extract proteins from human nail plate and may aid the study of nail structure and function. Further studies are needed to extend our results in terms of age, gender, ethnicity and disease.

Drug-Induced Psoriasis: An Evidence-Based Overview and the Introduction of Psoriatic Drug Eruption Probability Score

Psoriasis is a common skin disorder that needs a long-term management, not only because, of its prevalence but also because of the profound impact it can have on patients quality of life. Drugs may result in exacerbation of a preexisting psoriasis, in induction of psoriatic lesions on clinically uninvolved skin in patients with psoriasis, or in precipitation of the disease in persons without family history of psoriasis or in predisposed individuals. The knowledge of the drugs that may induce, trigger, or exacerbate the disease is of primary importance in clinical practice. By reviewing the literature, there are many reports on drug-induced psoriasis, but the data are not univocal. We propose, when possible, the use of a probability score from the authors to obtain a better classification and further understanding of drug-induced psoriasis.

Skin decontamination of glyphosate from human skin in vitro

This study compared three model decontaminant solutions (tap water, isotonic saline, and hypertonic saline) for their ability to remove a model herbicide (glyphosate) from an in vitro human skin model. Human cadaver skin was dosed (approximately 375microg) of [14C]-glyphosate on 3cm2 per skin. After each exposure time (1, 3, and 30min post-dosing, respectively), the surface skin was washed three times (4ml per time) with each solution. After washing, the skin was stripped twice with tape discs. Lastly, the wash solutions, strippings, receptor fluid, and remainder of skin were liquid scintillation analyzer counted to determine the amount of glyphosate. There were no statistical differences among these groups at any time points. The total mass balance recovery at three time exposure points was between 94.8% and 102.4%. The wash off rates (glyphosate in wash solutions) at three different exposure times is 79-101.2%. Thus the three tested decontaminants possess similar effectiveness in removing glyphosate from skin. This in vitro model is not only economic and rapid, but also provides quantitative data that may aid screening for optimal decontaminants.

Intrinsic and extrinsic factors in skin ageing: a review

As the proportion of the ageing population in industrialized countries continues to increase, the dermatological concerns of the aged grow in medical importance. Intrinsic structural changes occur as a natural consequence of ageing and are genetically determined. The rate of ageing is significantly different among different populations, as well as among different anatomical sites even within a single individual. The intrinsic rate of skin ageing in any individual can also be dramatically influenced by personal and environmental factors, particularly the amount of exposure to ultraviolet light. Photodamage, which considerably accelerates the visible ageing of skin, also greatly increases the risk of cutaneous neoplasms. As the population ages, dermatological focus must shift from ameliorating the cosmetic consequences of skin ageing to decreasing the genuine morbidity associated with problems of the ageing skin. A better understanding of both the intrinsic and extrinsic influences on the ageing of the skin, as well as distinguishing the retractable aspects of cutaneous ageing (primarily hormonal and lifestyle influences) from the irretractable (primarily intrinsic ageing), is crucial to this endeavour.

Percutaneous Penetration Enhancers: An Overview

Transdermal drug delivery is the controlled release of drugs through the skin to obtain therapeutic levels systematically. Several technological advances have been made in the recent decades to enhance percutaneous drug penetration. This overview focuses on the physical, biochemical, and chemical means of penetration enhancement, as well as the classification and mechanisms of chemical penetration enhancers, their application in transdermal drug delivery, and trends and development in penetration enhancement.

How irritant is alcohol?

BACKGROUND

Alcohol-based hand rubs are used worldwide to prevent transmission of nosocomial pathogens.

OBJECTIVES

To investigate skin irritation caused by alcohols alone and in combination with detergent washing.

METHODS

Single and repetitive patch testing with 60-100% alcohols [ethanol, 1-propanol, 2-propanol (synonyms: isopropyl alcohol, isopropanol)], a positive control [0.5% sodium lauryl sulphate (SLS)] and negative controls (empty chamber and water) were performed. Wash tests were performed with 80% ethanol and 0.5% SLS on the forearms with each agent alone and with both agents in a tandem design. Skin hydration, erythema and barrier disruption [measured as transepidermal water loss (TEWL)] were evaluated (always 15 volunteers).

RESULTS

We found no significant change in skin barrier or erythema induced by the alcohols in the patch tests, whereas skin hydration decreased significantly. Application of alcohols to previously irritated skin did not show a stronger skin barrier disruption than application of SLS alone. Wash tests demonstrated that alcohol application caused significantly less skin irritation than washing with a detergent (TEWL, P < 0.001; skin hydration, P < 0.05; erythema, P < 0.05). Even on previously irritated skin, ethanol did not enhance irritation. By contrast, a protective effect of ethanol used after skin washing was observed (TEWL, P < 0.05; skin hydration, P < 0.05; erythema, P < 0.05).

CONCLUSIONS

Alcohol-based hand rubs cause less skin irritation than hand washing and are therefore preferred for hand hygiene from the dermatological point of view. An alcohol-based hand rub may even decrease rather than increase skin irritation after a hand wash due to a mechanical partial elimination of the detergent.

In vitro model for decontamination of human skin: Formaldehyde

Decontamination of a chemical from skin is often an emergency measure. This study utilized an in vitro model to compare the decontamination capacity of three model decontaminant solutions (tap water, isotonic saline, and hypertonic saline). Human cadaver skin was dosed (approximately 0.25 microg on 3 cm(2) per skin) with radio-labeled [(14)C]-formaldehyde. After a defined exposure time (1, 3, and 30 min post-dosing, respectively), the surface skin was washed three times (4ml per time) with each solution. After washing, the skin was stripped with tape discs twice. Lastly, the wash solutions, strippings, receptor fluid, and remainder of skin were liquid scintillation analyzer counted to determine the amounts of formaldehyde. Additionally, an evaporation test at different exposure times (1min, 3min, 15min, 30min, and 60min, respectively) was conducted to monitor formaldehyde % evaporation. There were no statistical differences among these groups except isotonic saline, at 3min post-exposure (in wash solutions), showed a significantly difference (p<0.05) when compared to tap water. Formaldehyde % evaporation increased linearly with extending application times, and were 7.7%, 13.6%, 19.7%, 24.4%, and 35.9% (1min, 3min, 15min, 30min, and 60min, respectively). This data suggests that isotonic saline may be effective in removing formaldehyde from skin. However, results from this model need validation in vivo. The model may provide a facile and robust method of accelerating knowledge of decontamination mechanism and lead to enhanced efficacy.

Gender Differences of Enzymatic Activity and Distribution of 17β-Hydroxysteroid Dehydrogenase in Human Skin in vitro

The interconversion of estrone (E1) and 17beta-estradiol (E2) is catalyzed by 17beta-hydroxysteroid dehydrogenase (17beta-HSD) in peripheral steroidogenic organs such as the skin. To investigate gender differences of activity and skin distribution of 17beta-HSD in human skin, enzymatic activity was measured in skin homogenates and skin horizontally sliced by 10 microm thickness in vitro. Reductive 17beta-HSD (E2 formation from E1) in female skin has a lower substrate affinity than in male skin; Km (Michaelis-Menten constant) of female and male skin is 11.8 +/- 6.5 and 2.0 +/- 2.0 microM, respectively. Female skin had a tendency to activate estrogen; Vmax (maximum rate) for E2 formation, 5.8 +/- 4.0 pmol/min/mg protein, is 1.7 times larger than E1 formation, 3.5 +/- 1.5 pmol/min/mg protein, and, on the other hand, male skin tends to deactivate estrogen; Vmax for E1 and E2 is 10.5 +/- 6.1 and 4.2 +/- 3.7 pmol/min/mg protein, respectively. The concentration of metabolite had a peak value at 80-120 microm from the skin surface. Therefore, these in vitro results suggest that the enzymatic activities of 17beta-HSDs have a gender difference in estrogen formation/metabolism and are distributed around the basement layer of the epidermis irrespective of sex. 17Beta-HSDs distributed around the basement epidermis may be effectively supplied with circulating estrogen from the papillary plexus to maintain the estrogen level in skin. This distribution pattern having a peak surrounding 100 microm from the skin surface indicates the importance for defense from noxae (e.g. detoxication) and maintenance of the internal environment (e.g. biosynthesis of hormones). Future studies should increase sample size and confirm these results by stricter statistical analysis.

Environmental factors and psoriasis

Psoriasis is a chronic relapsing disease characterized by variable clinical features. Several factors may exacerbate its manifestations, or even trigger the disease, such as traumatic injury to the skin, physical and psychological stress, cold weather, excessive alcohol intake, and drugs such as lithium and Beta-blockers. We describe the most common features of psoriasis and the exogenous factors that may induce, trigger or exacerbate the disease.