bluuebunny/crossref_metadata_2025 huggingface dataset:
Skin surface profile technique and its applications
Authors: HATZIS J.
Published: May 2007

Synopsis

In this study the ‘skin surface profile’(SSP) technique and its applications are described. With this technique the SSP is replicated by means of silicone impression materials. The SSP preparations were studied by a stereomicroscope or microscopic projector. Some applications of SSP technique are as follows: a. measurement of the stratum corneum hydration, b. study of the profile of primary crests and lines, c. measurement of the primary crests reservoir available for extension, and d. estimation of the true area of the skin surface in a body region.
In vivo evaluation in man by two noninvasive methods of the stratum corneum barrier function after physical and chemical modifications
Authors: KOMPAORE F. , DUPONT Ch. , MARTY J.P.
Published: May 2007

Synopsis

This study investigated the effect of different treatments on skin permeability, in vivo in man, by two noninvasive methods: transepidermal water loss (TEWL) determination measured with an evaporimeter, and Laser Doppler velocimetry (LDV) to measure the lag time before the vasodilatation induced by application of methyl and hexyl nicotinates.

Different treatments were performed on forearms of volunteers: 1. removal of the stratum corneum by stripping, 2. occlusion and hydration of the stratum corneum, 3. application of three surfactants in aqueous solution (Tween 60, sodium dodecyl sulphate and cetyl trimethylammonium bromide).

Increase in TEWL and decrease in lag time before the vasodilating effects of nicotinates measured with LDV after all treatments confirmed the modifications in skin permeability. The variations observed were more or less significant depending on the treatment, the investigative method, and the molecule used for the penetration study. With methyl (hydrophilic) nicotinate, the more TEWL increased, the more lag time decreased. A significant decrease in lag time after hexyl (lipophilic) nicotinate application was observed when there was a very high increase in TEWL. The lipophilic nature of the stratum corneum barrier was confirmed in vivo. Use of these two complementary methods, TEWL and LDV, allows the evaluation in vivo of the effect of different treatments on skin permeability in man.
The replacement of animal testing: ethical issues and practical realities
Authors: BALLS M.
Published: May 2007

Synopsis

Increasing expectation that products and materials of many kinds should be ‘safe’ is leading to demands for more toxicity testing. At the same time, there is mounting pressure to reduce, refine and replace laboratory animal experimentation. The testing of cosmetics is particularly controversial. The only way out of this dilemma is the development, validation, acceptance and use of non‐animal test procedures, i.e. replacement alternative methods. Given realism and determination, more funding, better science and good strategic planning, the future for replacement alternatives, and thus for human and animal welfare, could be a very bright one.
Dental plaque – associated infections and antibacterial oral hygiene products
Authors: VERRAN J.
Published: May 2007

Synopsis

Dental plaque accumulates on hard non‐shedding surfaces such as teeth, dentures and orthodontic appliances. This accumulation is facilitated by the absence of adequate oral hygiene procedures.

The term ‘plaque’ describes a mass of microorganisms embedded in an organic matrix of host and microbial origin. In addition to the aesthetic desirability of ‘clean teeth, healthy gums and fresh breath’ associated with the absence of plaque, obvious consequences of the presence of plaque include tooth decay (dental caries), gingivitis and periodontal (gum) disease and denture associated problems.

Thus the prevention of plaque formation, the reduction of plaque accumulation and the effective removal of plaque are considerations of the cosmetic and health professions alike.

There are many oral hygiene products available to the general public – toothpastes, mouthwashes, denture cleaners, and, more recently, chewing gums and novel mouthwashes. Several of these products have antimicrobial components.

This paper reviews the microbiology of plaque and plaque associated problems, and surveys the type of products currently available for maintenance of good oral hygiene. Potential areas for future development are also explored.
Viscosity regulation by surfactants
Authors: DAHMS G.
Published: May 2007

Synopsis

The viscosity of cosmetic emulsions is of great practical importance and related to their skin feel. To achieve a desirable and constant viscosity is not an easy task because numerous factors must be considered. Based on theoretical considerations a new surfactant, steareth‐5‐stearate, has been developed. It can be shown that its use, together with a second more hydrophilic surfactant, results in flowable emulsions, the viscosity of which remain stable under normal conditions.
Skin lipids
Authors: BROOKS G. , IDSON B.
Published: May 2007

Synopsis

Concepts regarding the structure and function of the stratum corneum (SC) have changed from that of a tough film of loosely adherent cells to that of a two‐compartment system of protein‐enriched cells embedded in intercellular lipids. The two‐compartment arrangement enlarged the role of epidermal lipids from that of the plasticizing component of the SC to that of the epidermal barrier governing water‐holding properties as well as take‐up of water, the differences in permeability of topically applied lipophilic and hydrophilic agents as well as cohesion and desquamation of the SC. Barrier properties of SC are dependent largely on the intactness of the lipid lamellae that surround the corneocytes. The pliability of the SC depends on a correct balance of lipids, hygroscopic water‐soluble substances and water.

Mammalian differentiation involves characteristic changes in lipid composition consistent with the requirements for waterproofing. There is a progressive depletion of phospholipids and glycosphingolipids with enrichment in ceramides, cholesterol, free fatty acids, and small amounts of other polar (e.g. cholesterol sulphate) and non‐polar species (e.g. hydrocarbons, cholesterol esters, triglycerides). The sphingolipids account for the most lipid by weight and are presumed to be of major importance for the water‐retaining properties of the epidermal barrier. Decrease of sphingolipid content occurs in aged skin. Deficiency of essential fatty acids leads to enhanced transdermal water transport in addition to dryness and scaliness of the skin. A mixture of both saturated and unsaturated fatty acids produces the optimal barrier to water loss from the SC. The balance between solid crystal and liquid crystalline phases in epidermal lipids is determined by the degree of fatty acid unsaturation and the amount of water.
Changes in glutathione content in human hair follicle keratinocytes as a function of age of donor: relation with glutathione dependent enzymes
Authors: PRUCHE F. , KERMICI M. , PRUNIERAS M.
Published: May 2007

Synopsis

Glutathione (GSH) plays an important role in cellular protection during ageing. The hair plucking technique is a non‐invasive method for the direct biochemical study of keratinocytes. Hair was taken from the suboccipital area of 63 volunteers (men and women whose ages ranged from 13 to 103 years). The results show a diminution in the glutathione content as a function of age. We compare two groups of population: group A (less than 80) and group B (more than 80). A remarkable fact is observed: group B displays a weak dispersion of the values as compared to A. The glutathione content (nmol 10−3 mg DNA) is 5.42 ± 0.60 for A and 1.86 ± 0.35 for B. A reduction of 88% was observed in glutathione reductase activity and of 78% in the activity of glutathione‐S‐transferase from group A to group B. The glutathione peroxidase activity remains relatively constant. The decrease in the GSH concentration and the constancy of the glutathione peroxidase suggest that the capacity of the cell to protect itself from peroxides remains unchanged but that the GSH concentration may become the limiting factor.
Propriétés antiélastasiques des propionylaminoacides
Authors: LAFFORGUE Ch. , CROUTE F. , NICOLAS J.F. , HARTMANN D.J. , DELAPORTE E. , COTTE J. , MARTINI M.C.
Published: May 2007

Synopsis

Antielastase activity of derivatives like ‘propionylaminoacid’(C3 prolin, C3 hydroxyprolin, C3 collagen) was examined for pancreatic elastase, and fibroblastic elastase production. Essential metabolic variations of normal dermal fibroblasts were evaluated: adhesion, proliferation capacity, total protein biosynthesis and collagen type I and type III production. Possible other factors such as cellular nutrients were examined by oxygen consumption evaluation.

Propionylaminoacid derivatives have antielastase activities. Pancreatic elastase showed dose related inhibition (20% to 50% inhibition for concentration from 5 to 80 mg ml−1.

Moreover, fibroblastic elastase production was inhibited, cellular respiration was enhanced. A very good tolerance in vitro was observed for concentration 0–1 mg ml−1 range: adhesion, proliferation capacity and collagen (type I and type III) production were not altered, and oxygen consumption was enhanced.
Fine details on the surface of human hair
Authors: SWIFT J.A.
Published: May 2007

Synopsis

Some previously unreported fine variations in the form of normal hairs are described as they are observed in the scanning electron microscope (SEM). They all arise in the course of surface frictional wear and the chipping away of the hair surface scale edges and include remanent surface impressions of cuticle scale edges, ‘false’ scale edges, granular surface remnants and highly irregular (chevron) scale patterns. Mechanisms are proposed for the way in which each of these different fine features arise.

The paper also contains deliberations on the conditions for operating the SEM consistent with obtaining the best information about the architecture of hair surfaces. The correctness of viewing orientation of scanning electron micrographs is also emphasized to avoid misinterpretation of features on the hair surface.
Novel quaternary ammonium salts derived from triglycerides and their application in skin and hair products
Authors: BAYDAR AHMET , JOHNSTON RICHARD
Published: May 2007

Synopsis

An investigation has been carried out into the synthesis of quaternary ammonium salts of triglycerides. The aim of this work was to produce such compounds without breaking the triglyceride skeleton. The reaction of chloracetyl chloride with the triglyceride of ricinoleic acid which is the major constituent (88–90%) of castor oil gave an intermediate derivative with pendant chloro groups. Quaternization with stearyl dimethylamine gave a 98% yield of a quaternary ammonium salt containing three quaternary groups per molecule. This reaction sequence overcame the steric hindrance problems encountered in unsuccessful attempts to quaternize halogen groups attached directly to the main chain. Using the same procedure, a quaternary salt was prepared from castor oil.

In skin care studies this quaternary was used at a low level in a moisturizing lotion. Subjective assessment of the ease of application of the test lotion versus control was significantly in favour of the test. Viscoelastic measurements of the skin were made using two techniques before and after application of the lotion. Both showed an advantage to the test lotion. No difference between the test and control lotions was found when sebum levels and transepidermal water loss measurements were measured. A C‐12 quaternary synthesized from dimethyl‐dodecylamine exhibited antimicrobial activity. An aqueous dispersion of the C‐18 quaternary when applied to bleached hair in order to improve combing, gave excellent results showing superiority to four other commercially available quaternary ammonium salts.
Skin colour typology and suntanning pathways
Authors: CHARDON A. , CRETOIS I. , HOURSEAU C.
Published: May 2007

Synopsis

The evaluation of sun‐product efficacy, with laboratory solar simulators or in actual sun, implicates clinical and subjective assessment of the various skin responses in terms of wavelengths constitutive of solar light. These photobiological responses vary according to skin types and particularly to basic skin melanic content, i.e. with skin colour. Now, the instrumental measurement of live skin colour has become easier to perform, fast and reliable. Based on the standard CIE‐L*a*b* colour system and correlated with the human eye, this technique was used to define the skin colour domain of the caucasian population, to propose a skin colour classification, and then to objectively follow, over a three week period, the dynamics and kinetics of tanning induced by UVB, UVA and UVB ± A multi‐exposures on the three skin categories. The specific directions in the three‐dimensional L*a*b* colour space of the tanning components, i.e. erythema, immediate pigmentation and constitutional melanization, as well as the resulting tanning pathways, were analysed and defined in the three‐dimensional colour space, using a vectorial method. The UVB, UVA and UVB ± A tannings were differentiated by their intensity, their hue and especially their lasting capacity: UVA tanning clearly appeared more lasting than UVB. In addition, the UVA*UVB interaction on tanning intensity was not found to be significant. With the skin colour classification and the tanning models, this comprehensive study supplies a basic tool for the colorimetric interpretation of the skin phenomena involved, provided that this interpretation is always considered in the three dimensions of the colour space. It also suggests some useful practical applications for sun product formulation and evaluation.
The role of primary alkanolamines in cosmetic formulation
Authors: BREMECKER K.‐D. , NATONSKI J.L. , EACHUS A.C.
Published: May 2007

Synopsis

Alkaline products are commonly used in cosmetic preparations as neutralizing agents for acid‐functional raw materials. Primary alkanolamines can provide positive attributes in such cases. The properties of nitroparaffin‐derived primary alkanolamines are compared here with the general requirements for cosmetic‐type acid‐neutralizing materials.

Acid‐functional copolymers, used as hair fixatives in both aerosol and non‐aerosol products, are efficiently solubilized by neutralization with 2‐amino‐2‐methyl‐1‐propanol (amino‐methylpropanol) in a variety of aqueous and non‐aqueous systems. The effects of such neutralization on resultant film properties which influence product performance are discussed in detail.

Upon neutralization, crosslinked acrylic‐acid polymers of varying molecular weights (carbomers) provide significant benefits when used as thickeners, gellants or emulsifiers in cosmetic products. New data are added to previous knowledge on the use of tris(hydroxymethyl)aminomethane (tromethamine) as a neutralizing agent for three resins, especially in gelled formulations. Alcohol compatibility, pH behaviour, and viscosity characteristics of such formulations are described. In addition, toxicological considerations of primary alkanolamines are addressed.

Further to the above applications, nitroparaffin‐derived primary alkanolamines can be effectively used as cosmetic emulsifiers (in the form of their fatty‐acid soaps), dispersants or co‐dispersants for particulate‐containing products, and pH buffers/stabilizers.
The determination of the antiperspirant activity of aluminium‐chlorhydrate by digital image‐analysis
Authors: SAUERMANN G. , HOPPE U. , KLIGMAN A.M.
Published: May 2007

Synopsis

The method of Minor to visualize by iodine–starch–reaction the activity of sweat glands was used in combination with image‐analysis to quantify sweat‐secretion. Aqueous aluminium chlorohydrate solutions (ACH) (1, 2, 4, 8, 16%) were applied twice daily for 6 days to defined areas of the lower volar forearms. After 3 and 6 days of treatment perspiration was induced by thermal stress. The dark blue spots on top of active glands which are formed by iodine–starch–complexes were counted and their projection area was measured by an image analysing system. Increasing concentrations of ACH lower the number of active sweat glands, while the size of the dark spots is not dependent on the concentration of the active ingredient.
Non‐saponifiable fraction of cocoa shell butter: effect on rat and human skin fibroblasts
Authors: WAROCQUIER‐CLEROUT R. , SIGOT M. , OURAGHI M. , CHAVERON H.
Published: May 2007

Synopsis

Non‐saponifiable lipid fraction (ICSB) extracted from cocoa shell butter was solubilized in dimethylformamide (DMF) and analysed for its biological activity on growth of rat and human fibroblasts. Non‐saponifiables (10 μg ml−1) partially protected cells from toxicity of DMF (1%) and allowed the growth of fibroblasts cultivated in optimal conditions (10% fetal calf serum‐FCS, 37°C) or improved the survival of cells maintained in altered conditions (2.5% FCS, 35°C). At higher concentration (ICSB 50 μg ml−1, DMF 1%), the protective effect was suppressed. ICSB was fractionated by chromatography into four compounds: sterols, terpenic alcohols, tocopherols and hydrocarbons ± carotenoids. We found that biological activity of ICSB was mostly due to the major fraction containing sterols.
Les enzymes de l'espace extra‐cellulaire du stratum corneum
Authors: FORESTIER J.P.
Published: May 2007

Synopsis

Bien que le stratum corneum soit composé de cellules ‘mortes’, il est le siège d'une activité métabolique très importante. Mais, contrairement à la plupart d'autres tissus, cette activité a la particularité d'étre extra‐cellulaire. Elle est due à des enzymes excrétées par les Corps d'Odland avec les bicouches céramidiques.

Ces enzymes sont des hydrolases, elles sont identiques ou très proches de celles des lysosomes. Les principales activités observées correspondent à une (ou des) glycosidase(s), une phospholipase, une sphingomyélinase, une phosphatase, une (ou des) estérase(s), des sulfatases, des protéases. Comme les hydrolases des lysosomes, elles semblent peu spécifiques.

Ce pool enzymatique pourrait jouer plusieurs rôles fondamentaux, notamment:

1. La transformation des bicouches gluco‐céramidiques en bicouches ceramidiques plus lipophiles;

2. L'élimination de la membrane plasmique, dont certains produits du catabolisme, comme les acides gras et les céramides, peuvent être intégrés aux bicouches céramidiques;

3. La diminution de la cohésion entre les cornéocytes;

4. La protection contre l'intrusion de corps étrangers.

Comme tout système enzymatique, les hydrolases extra‐cellulaires, sont certainement soumises à des régulations. Plusieurs de ces régulations sont envisagées.

A partir de considérations d'enzymologie, le pH de la base du stratum corneum peut être estiméà environ 5.

En cosmétologie, les enzymes du stratum corneum sont mises à contribution pour rendre actifs des précurseurs.

L'étude des conséquences des modifications de l'activité enzymatique sur l'état de la peau pourrait constituer une future voie de recherche extrêmement prometteuse.
Physico—chemical modifications of liposome structures through interaction with surfactantsy‡
Authors: RIBOSA I. , GARCIA M.T. , PARRA J.L. , de la MAZA A. , SANCHEZ‐LEAL J. , TRULLAS C. , TSI A. , BALAGUER F. , PELEJERO C.
Published: May 2007

Synopsis

The liposome‐surfactant interaction has been studied in this paper through the disrupting effect caused by surfactant molecules on large unilamellar vesicles prepared by reverse‐phase evaporation. This process leads, in the end, to the rupture of such structures and to the solubilization of the phospholipidic components, via mixed surfactant‐phospholipid micelle formation. This phenomenon is described by a three‐stage model and characterized by two parameters: the highest surfactant/phospholipid ratio that can exist in a vesicle (Re sat) and the lowest surfactant/phospholipid ratio required to keep the lipid and surfactant in the form of mixed micelles (Re sat). These parameters have been determined by spectrophotometry and 31P NMR spectroscopy, obtaining results in a good agreement with both techniques. The surfactants tested have been: sodium dodecyl sulfate (SDS), sodium laurylether sulfate (SLES), N‐hexadecyl‐trimethylammonium bromide (HTAB), octylphenol series (8–20 EO) and alkylbetaines(C‐10, C‐12 and C‐14). Different Re sat and Re sol values have been obtained for each of the surfactants. This has permitted a study of the solubilizing capacity versus the phospholipidic bilayer of the different surfactants as a function of their structure.
Comparison of percutaneous penetration in vitro using clofibric acid esters and amides as novel enhancers in two species: mouse and guinea pig
Authors: MICHNIAK B.B. , CHAPMAN J.M.
Published: May 2007

Synopsis

A series of clofibric acid esters and amides has been assessed as dermal penetration enhancers towards hydrocortisone‐21‐acetate, a model drug. In vitro percutaneous absorption experiments on three skin sources (athymic nude mouse, hairless mouse, and hairless guinea pig) showed several compounds to be effective penetration enhancers, the octyl amide providing an approximately 20‐fold increase in 24 h diffusion cell receptor drug concentration and 5.7 fold in total steroid skin retention in nude mouse. Azone produced significantly higher (p <0.05) permeation rates than the octyl amide enhancer, but there was a smaller increase in 24 h receptor concentrations, and Azone steroid skin concentrations were significantly less (p < 0.05) than those for the amide. There was no significant difference (p < 0.05) between enhancement in hairless and athymic nude mouse, however, hairless guinea pig skin showed decreased enhancer effectiveness.
New gelification method for vegetable oils I: cosmetic application
Authors: AIACHE J.‐M. , GAUTHIER P. , AIACHE S.
Published: May 2007

Synopsis

A new gelification process of vegetable oils was developed using a cellulose derivative in order to obtain transparent oleogels (anhydrous gels based on fatty components) of different consistencies. The study of their structure has been carried out by infra‐red spectroscopy, differential thermal analysis and X‐ray diffractometry. All these physical tests have demonstrated the gel structure of the formulations. Finally, a rheological study was run to elucidate their specific properties and their stability during storage.
Studies on the stability of selected viruses in cosmetics
Authors: von RHEINBABEN F. , HEINZEL M.
Published: May 2007

Synopsis

Information concerning the risks emerging from the use of cosmetics contaminated with viruses is rarely reported. Therefore, we investigated the stability of viruses within different types of cosmetics. Test products were artificially contaminated with different viruses, which, due to the application of the products, have hygienic relevance. Virus persistence was observed by determining the reisolation rate. With this knowledge we were able to estimate the initial contamination of finished products and raw materials.

Viruses with hygienic relevance could neither be detected in finished products nor in raw materials. We can conclude from this that cosmetics seem to be safe with regard to initial contamination. However, our results clearly showed that secondary contamination with viruses can have a persistence which is high enough to pose a hygienic risk through cross contamination.
In vitro cultured human skin cells as alternatives to animals for skin irritancy screening
Authors: PONEC MARIA
Published: May 2007

Synopsis

In the last few years a lot of attention has been paid to the development of the in vitro models which would substitute for animals in cutaneous irritancy studies. These models explore either organ or explant cultures using freshly excised skin or serial cultures of isolated skin cells (epidermal keratinocytes or dermal fibroblasts). The organ or explant models are suitable only for short exposures of skin samples to the compounds tested and the use of it will always be restricted by the limited availability of fresh human skin. The model that uses submerged cultures of keratinocytes or fibroblasts permits the production of a large number of cells, and permits large scale toxicity screening tests with many substances, that can be applied in a broad concentration range. Since the stratum corneum is absent in conventional (submerged) keratinocyte culture systems, this model is mainly suited for testing of water soluble compounds and it is less suitable for poorly soluble compounds and for topical products consisting of complex formulations which are made of active ingredients and their vehicles. This shortcoming can be overcome by using ‘organotypic cultures’in which keratinocytes are grown at the air‐liquid interface on a suitable dermal substrate. Under these conditions, the culture forms a multilayered epidermis showing an overall structure which resembles that of a native epidermis. The presence of a coherent stratum corneum layer in these cultures permits the application of potential irritants at concentrations and in formulations as applied in vivo. For the evaluation of toxicity a number of tests have already been developed: assessment of cell viability, changes in cell morphology, modulation of cell proliferation and differentiation, monitoring of membrane damage, the measurements of the uptake or incorporation of radioactive precursors, establishment of the modulation of cell metabolism, determination of the release of inflammatory mediators, etc. All these in vitro techniques are still in a state of validation as far as their predictive value for in vivo skin irritancy is concerned.
Prediction of the percutaneous penetration of ultra‐violet filters used in sunscreen formulations
Authors: WATKINSON A.C. , BRAIN K.R. , WALTERS K.A. , HADGRAFT J.
Published: May 2007

Synopsis

The application of a mathematical model to estimate the extent of transdermal absorption of UV‐filters commonly used in sunscreen formulations is described. Percutaneous penetration is not a factor that has been properly addressed in the literature and the penetration/time profiles generated here suggest that significant amounts of certain of these compounds may penetrate the skin and enter the systemic circulation. The results presented indicate that further research in this area is necessary and the authors suggest that in vitro experiments with human skin are conducted with both current and new UV filters to quantify the degree of dermal penetration of these substances.
In‐use tolerability of two new syndet bars with sodium cocoyl isethionate, disodium lauryl sulfosuccinate and wheat starch as major ingredients in differing relations: results of a cross‐over trial
Authors: KORTING H.C. , LUKACS A. , HAMM D. , STANZL K. , BRAUN‐FALCO O.
Published: May 2007

Synopsis

In a cross‐over trial two different new syndet bars differing in their content of sodium cocoyl isethionate, disodium lauryl sulfosuccinate and wheat starch as major components were compared in the cleansing of hand skin of 72 healthy volunteers. The preparation designated ‘T’containing a higher amount of wheat starch turned out to be less irritant as judged from the parameters itching and erythema (p < 0.05, Wilcoxon's test for matched pairs). The present trial design looks appropriate to differentiate the irritancy potential of two chemically similar syndet bar preparations.
Influence of different oils on penetration of human hair by fungi
Authors: BAHUGUNA S. , KUSHWAHA R.K.S.
Published: May 2007

Synopsis

The hair perforating ability of Microsporum gypseum and Trichophyton vanbreuseghemii was tested in presence of seventeen oils. Clove, olive and turpentine oils were found to be fully inhibitory for hair penetration by both fungi. Hair segments smeared with cantheridine oil and keocarpin hair vitalizer failed to reveal any perforation by T. vanbreuseghemii whereas arnica and shikakai oils showed little perforation by this fungus.
A simple and specific high performance liquid chromatography method for the assay of a series of novel dermal penetration enhancers
Authors: MICHNIAK B. B. , SEYDA K. L.
Published: May 2007

Synopsis

A series of clofibric acid amides has been synthesized and previously reported by the authors as possessing enhancer activity in vitro in athymic nude mouse skin against model drugs, hydrocortisone‐21‐acetate and β‐methasone‐17‐valerate. An assay was required for each of these enhancers however, which would be specific for each compound and would also separate model drugs and their metabolite peaks. This study reports reverse phase high performance liquid chromatography assays for clofibric acid amide and seven derivatives (Ia–Ig). All enhancers showed maximum absorption at 232 nm, betamethasone (BM) and its valerate (BMV) at 238 nm, and hydrocortisone (HC) and its acetate (HCA) at 242 nm. Practical units of detection for the amides were 0.46–2.8 μg ml‐1 and peaks were sharp and well‐separated from steroid peaks in three vehicles – methanol alone. Franz diffusion cell receptor phase samples (isotonic phosphate buffer), and full‐thickness athymic nude mouse skin extracts in methanol.

Mobile phases consisted of various proportions of acetonitrile and water, some with 2‐propanol. The octyl amide for example, with mobile phase CH3CN: H2O (85:15) at 1 ml min‐1 had a retention time (tR) of 7.9 mins. Under the same conditions, retention times for the steroids were HC, tR= 3.3 mins; HCA, tR= 4.3 mins; BM, tR= 3.4 mins; BMV, tR= 4.6 mins.
A cell suspension agar diffusion test using Neutral Red release to assess the relative irritancy potential of cosmetic ingredients and formulations
Authors: BUTLER N.J. , LANGLEY G.R. , WINWOOD J.
Published: May 2007

Synopsis

An established cytotoxicity test for plastic materials in medical devices has been adapted and used to assess the relative potential irritancy of cosmetic ingredients and formulations during product development. Serum‐free medium containing a novel protein supplement supported growth in suspension of LS mouse fibroblast cells. Release of the vital dye Neutral Red from pre‐loaded cells suspended in agar was the endpoint. Test substances and reference standards were applied to a central well cut into the agar, a sensitive method which allowed accurate dose application and yielded consistent results. Relative irritancy potential was measured quantitatively by comparing the diameters of the clear zones of damaged cells which surround the central well. The test has been used with raw materials such as surfactants, preservatives and herbal extracts, as well as finished products ranging from shampoos and conditioners to creams, lotions and coloured cosmetics. The method is practical, versatile, reproducible and economic to use.
UV filters for hair protection
Authors: BERNHARDT P. , GIESEN M. , HOLLENBERG D. , HUBBUCH M. , KALHÖFER V. , MAIER H.E. , MARTIN V. , MÜNZING H.‐P. , OELSCHLÄGER T. , SCHWAN A. , SPERLING K. , TENNIGKEIT J.
Published: May 2007

Synopsis

Hair damage, caused by sunlight, and the possibility to protect hair against sunlight by means of cosmetic formulations was studied. For this, five UV‐filters were tested: benzophenone‐3 (UV‐A/UV‐B); benzophenone‐4 (UV‐A/UV‐B); phenylbenzimidazole sulfonic acid (UV‐B); butylmethoxydibenzoylmethane (UV‐A); octyl dimethyl PABA (UV‐B). The stability of the UV‐filters was tested as pure substances as well as in two cosmetic formulations: a setting lotion and a shine spray. The degree of decolouration and stress strain behaviour were determined. The benzophenones had the best protection ability both on colour and on morphology. Stability data and UV‐spectra are discussed.
Skin mechanics measured in vivo using torsion: a new and accurate model more sensitive to age, sex and moisturizing treatment
Authors: SALTER D.C. , McARTHUR H.C. , CROSSE J.E. , DICKENS A.D.
Published: May 2007

Measurements of skin mechanics are required to understand better cracking and flaking of the epidermis and loss of ‘elasticity’with age in the dermis. Improvements in torsional testing are described here. The resulting data was fitted to algebraic models, the parameters of which can serve both as a concise description of the responses and as a means of relating them to skin structure and physiology. This investigation looks into the suitability of seven such algebraic models. Five of the models examined here appear to be new.

Using the commercially available Dia‐Stron DTM Torque Meter with our own software, model parameters were studied as indicators of the effects of age and sex in 41 people, and of skin moisturizing treatments in a further 10 people. The two models in the literature were both found to be substantially less accurate and sensitive representations of experimental data than one of the new models proposed here based on the Weibull distribution. This ‘WB model’was consistently the one best able to distinguish differences and detect changes which were statistically significant. The WB model appears to be the most powerful and efficient available. Use of this model makes it possible to demonstrate in vivo a statistically significant mechanical difference between male and pre‐menopausal female skin using only one parameter (p= 0.0163, with 18 males and 19 females) and to demonstrate a statistically significant mechanical difference between successive decades of age in female skin using only one parameter (p= 0.0124, n= 24). The two parameters of the model most sensitive to skin structure, function and treatment have been combined to form the axes of a ‘Skin condition chart’. Any person can be located on this chart at a point indicating their overall skin condition in mechanical terms and any changes in that condition can be clearly demonstrated by movement across the plot.
Moisturization processes in living human skin studied by magnetic resonance imaging microscopy
Authors: SALTER D.C. , HODGSON R.J. , HALL L.D. , CARPENTER T.A. , ABLETT S.
Published: May 2007

Magnetic resonance imaging is a non‐invasive, non‐destructive and chemically specific imaging method widely used in medicine to reveal information about both tissue structure and function. It can measure water in tissue, but it has been difficult to achieve the necessary sensitivity and resolution when applying it to studies of the dry, thin stratum corneum. In this paper the use of magnetic resonance imaging to image the outer layers of the skin with a resolution of 0.06 mm is reported. Configuring the magnetic resonance imaging method in this way has made it possible for the first time to actually ‘see’directly the moisturization in the stratum corneum. It is no longer necessary to rely upon methods which can only show side‐effects of moisturization, such as changes in the appearance of the skin cells. As magnetic resonance imaging is harmless, it can be used repeatedly on the same skin and so produce a series of stills, or a time‐lapse video, clearly showing the actual process of moisturization and related phenomena. The behaviour of skin has been observed during both hydration and dehydration; the two processes follow different time courses. Two layers have been observed in the stratum corneum, which appear to be different when the skin is hydrated.

For the first time the actual surface of normal skin has been revealed on magnetic resonance images.
4. Regression with Missing Ys: An Improved Strategy for Analyzing Multiply Imputed Data
Authors: von Hippel Paul T.
Published: May 2007

When fitting a generalized linear model—such as linear regression, logistic regression, or hierarchical linear modeling—analysts often wonder how to handle missing values of the dependent variable Y. If missing values have been filled in using multiple imputation, the usual advice is to use the imputed Y values in analysis. We show, however, that using imputed Ys can add needless noise to the estimates. Better estimates can usually be obtained using a modified strategy that we call multiple imputation, then deletion (MID). Under MID, all cases are used for imputation but, following imputation, cases with imputed Y values are excluded from the analysis. When there is something wrong with the imputed Y values, MID protects the estimates from the problematic imputations. And when the imputed Y values are acceptable, MID usually offers somewhat more efficient estimates than an ordinary MI strategy.
2. Average Predictive Comparisons for Models with Nonlinearity, Interactions, and Variance Components
Authors: Gelman Andrew , Pardoe Iain
Published: May 2007

In a predictive model, what is the expected difference in the outcome associated with a unit difference in one of the inputs? In a linear regression model without interactions, this average predictive comparison is simply a regression coefficient (with associated uncertainty). In a model with nonlinearity or interactions, however, the average predictive comparison in general depends on the values of the predictors. We consider various definitions based on averages over a population distribution of the predictors, and we compute standard errors based on uncertainty in model parameters. We illustrate with a study of criminal justice data for urban counties in the United States. The outcome of interest measures whether a convicted felon received a prison sentence rather than a jail or non-custodial sentence, with predictors available at both individual and county levels. We fit three models: (1) a hierarchical logistic regression with varying coefficients for the within-county intercepts as well as for each individual predictor; (2) a hierarchical model with varying intercepts only; and (3) a nonhierarchical model that ignores the multilevel nature of the data. The regression coefficients have different interpretations for the different models; in contrast, the models can be compared directly using predictive comparisons. Furthermore, predictive comparisons clarify the interplay between the individual and county predictors for the hierarchical models and also illustrate the relative size of varying county effects.
3. Multilevel Covariance Structure Analysis by Fitting Multiple Single-Level Models
Authors: Yuan Ke-Hai , Bentler Peter M.
Published: May 2007

Data in social and behavioral sciences are often hierarchically organized. Multilevel statistical procedures have been developed to analyze such data while taking into account the dependence of observations. When simultaneously evaluating models at all levels, a significant statistic provides no information on the level at which the model is misspecified. Model misspecification can exist at one or several levels simultaneously. When one level is misspecified, the other levels may be affected even when they are correctly specified. Motivated by these observations, we propose to separate a multilevel covariance structure into multiple single-level covariance structure models and to fit these single-level models as in conventional covariance structure analysis. A procedure for segregating the multilevel model into single-level models is developed. Five test statistics for evaluating a model at each level are provided. Standard error formulas for the separate estimators are also provided, and their efficiency is compared to simultaneous estimators. Empirical and Monte Carlo results demonstrate the advantages of the segregated procedure over the simultaneous procedure. Computer programs that will allow the developed procedure to be used in practice are also presented.
8. Permutation Models for Relational Data
Authors: Butts Carter T.
Published: May 2007

A common problem in sociology, psychology, biology, geography, and management science is the comparison of dyadic relational structures (i.e., graphs). Where these structures are formed on a common set of elements, a natural question that arises is whether there is a tendency for elements that are strongly connected in one set of structures to be more—or less—strongly connected within another set. We may ask, for instance, whether there is a correspondence between golf games and business deals, trade and warfare, or spatial proximity and genetic similarity. In each case, the data for such comparisons may be continuous or discrete, and multiple relations may be involved simultaneously (e.g., when comparing multiple measures of international trade volume with multiple types of political interactions). We propose here an exponential family of permutation models that is suitable for inferring the direction and strength of association among dyadic relational structures. A linear-time algorithm is shown for MCMC simulation of model draws, as is the use of simulated draws for maximum likelihood estimation (MCMC-MLE) and/or estimation of Monte Carlo standard errors. We also provide an easily performed maximum pseudo-likelihood estimation procedure for the permutation model family, which provides a reasonable means of generating seed models for the MCMC-MLE procedure. Use of the modeling framework is demonstrated via an application involving relationships among managers in a high-tech firm.
Using Population Segmentation to Provide Better Health Care for All: The “Bridges to Health” Model
Authors: LYNN JOANNE , STRAUBE BARRY M. , BELL KAREN M. , JENCKS STEPHEN F. , KAMBIC ROBERT T.
Published: May 2007

The model discussed in this article divides the population into eight groups: people in good health, in maternal/infant situations, with an acute illness, with stable chronic conditions, with a serious but stable disability, with failing health near death, with advanced organ system failure, and with long‐term frailty. Each group has its own definitions of optimal health and its own priorities among services. Interpreting these population‐focused priorities in the context of the Institute of Medicine's six goals for quality yields a framework that could shape planning for resources, care arrangements, and service delivery, thus ensuring that each person's health needs can be met effectively and efficiently. Since this framework would guide each population segment across the institute's “Quality Chasm,” it is called the “Bridges to Health” model.
Commentary on the “Bridges to Health” Model
Authors: SCHOENBAUM STEPHEN C. , GAUTHIER ANNE K. , KOREN MARY JANE
Published: May 2007

The complex U.S. health system is currently organized around the needs and interests of providers. The “Bridges to Health” model offers a way to think about developing programs for segments of the population that meet patients' needs for coordinated, integrated care. When these programs are aggregated, they should improve the quality and efficiency of care for the entire population. Three examples are given to illustrate the possibility of conceptualizing integrated care and its advantages.
Reliability testing of a sun exposure questionnaire for the Northern Ireland population
Authors: McMullen EA , Dolan OM , McCarron P , Kee F
Published: May 2007

Background  Sunbathing and other types of exposure to ultraviolet radiation are the major preventable risk factors for skin cancer. Due to the continued increase in incidence of melanoma in Northern Ireland, we have conducted a questionnaire survey in an attempt to gather information about sunbathing habits and other forms of ultraviolet light exposure amongst the Northern Ireland population.

Aim  The aim of this study was to examine the test–retest reliability of a questionnaire used in a large‐scale cross‐sectional population survey pertaining to sunbathing habits, use of sun screen, skin types, and frequencies of sunburn and to assess the responses given by the subjects to determine the nature of their sun‐related behaviour.

Methods  Thirty control subjects were randomly selected from a population control sample participating in a large case–control study investigating melanoma in the Northern Ireland population. All participants completed the interview questionnaire on two occasions, with a median of 15 days (range, 12–42 days) between interviews. We randomly chose control subjects who had been visited by the same research nurse, thus ruling out interobserver bias in the analyses. We used the test–retest method. Kappa statistics were used to calculate the association between test and retest scores of all the individual items. If the items contained within the questionnaire are reliable, then repeated measurement after a fairly short period of time should result in high within‐subject repeatability.

Results  Questions pertaining to hours spent in the sun and sun bed usage showed high reliability (kappa > 0.7). Questions about sunscreen usage showed moderately high reliability (kappa > 0.6) in all but one of the 10‐year age bands and complete agreement (kappa = 1) in one age category (>50 years).

Conclusion  This questionnaire is a reliable method of assessing sun‐associated behaviour identifying high‐risk sun‐related behaviour and misconceptions about tanning, which can be targeted for improvement in public health.
Hippocratic messages for modern medicine (the vindication of Hippocrates)
Authors: Katsambas A , Marketos SG
Published: May 2007

Medicine feels the need to combine more than ever the traditional concepts of Hippocrates in perfect balance with the enormous power of modern biotechnology. In our times, the old message ‘go back to Hippocrates’ sounds like a utopian vision. On the other hand, technological progress tends to remove modern medicine from its anthropocentric mission. The realistic message for tomorrow's physicians must be ‘to go forward’ together with his perennial humanistic values and clinical messages, combining the recent advances of biotechnology with the Hippocratic rationalism, which is based on logical reasoning, on careful clinical examination, and on a whole humane approach to the patient and his environment. Today's physician can still learn from the Hippocratic heritage and will need to be an expert Hippocratic physician, ever more humane and competent to use all new methods and facilities of basic dermatological research.
Trigeminal trophic syndrome
Authors: Rashid RM , Khachemoune A
Published: May 2007

Trigeminal trophic syndrome (TTS) is a rare cause of facial ulceration, which is believed to develop after insult to the trigeminal ganglia or other parts of the peripheral/central nervous system in the trigeminal pathway. The pathogenesis of TTS is poorly understood. Developing a better understanding of TTS will allow early recognition and improved treatment. Although the ulcers develop predominantly on the ala nasi, the literature on ulcer locations is limited. In this article, we review the epidemiologic aspects of TTS, expand on our knowledge of the anatomic location of the ulcers, and discuss current theories for its aetiology and briefly review the approaches to its management.
Prevalence of pityriasis versicolor in a group of Italian pregnant women
Authors: Zampino MR , Osti F , Corazza M , Virgili A
Published: May 2007

Background  Although a predisposing role of pregnancy to Malassezia infections is referred, data on the prevalence of pityriasis versicolor (PV) in pregnant women are not available in literature.

Objective  To investigate the frequency of PV during pregnancy, 60 pregnant women were clinically and microscopically investigated during and after pregnancy.

Results  Fifty‐two women completed all visits; three women were affected by PV at first or third trimester of pregnancy, and none at 6 months after delivery. Colonization due to Malassezia yeasts was very significantly (P < 0.01) or significantly increased (P < 0.05) at the third trimester and 6 months after delivery, respectively. No variation was observed between the end of pregnancy and the postpartum (P > 0.05).

Conclusion  Frequency of PV during pregnancy (5.7%) does not seem different from that reported in general population living in temperate climates (2–5%). However, higher degree of colonization by Malassezia resulted at the end of pregnancy and postpartum.