Some thoughts about Anthony V. Rawlings and hydration and barrier function of the skin.

Anthony V. Rawlings has had 30+ years of experience in the general area of skin science. He has many scientific publications, and his work has been highly cited.

Linoleate-Containing Acylglucosylceramide, Acylceramide, and Events Associated with Formation of the Epidermal Permeability Barrier.

Background: Linoleate-containing acylglucosylceramide (GLC-CER[EOx], where x = sphingosine [S], dihydrosphingosine [dS], phytosphingosine (P), or 6-hydroxysphingosine [H]) in the viable epidermis serve as the precursors to the linoleate-containing acylceramides (CER[EOx]) in the stratum corneum (SC) and the corneocyte lipid envelope (CLE), both of which are essential for the barrier function of the skin.

Summary: CLE formation and envelope maturation take place across the SC. Hypoxic conditions in the epidermis and anaerobic glycolysis with the production of lactic acid are important in proper SC barrier formation.

Synopsis of Barrier Function of Skin and Mucosa-Volume 2.

This is an attempt to briefly summarize the contributions to this second Special Issue of the on the barrier function of the skin and the oral mucosa [...

Protective Barriers Provided by the Epidermis.

The skin is the largest organ of the body and consists of an epidermis, dermis and subcutaneous adipose tissue. The skin surface area is often stated to be about 1.8 to 2 m and represents our interface with the environment; however, when one considers that microorganisms live in the hair follicles and can enter sweat ducts, the area that interacts with this aspect of the environment becomes about 25-30 m.

Time Frame Analysis of Potassium Nitrate and Hydrogen Peroxide Diffusion into the Pulp Chamber.

Objectives: The primary objective of this study was to evaluate the effect of an innovative double-layer, single-application desensitizing/whitening technique of potassium nitrate (PN) and hydrogen peroxide (HP) diffusion at different time points.

Methods And Materials: Specimens were prepared from extracted caries-free human molars (n=90). Teeth were randomly assigned into four groups: Group A (HP CTRL) treated with 25% HP for 45 minutes, group B (PN CTRL) received a single-layer treatment of 5% PN for 45 minutes, group C received the double-layer treatment of 5% PN and 25% HP for 45 minutes, and group D received a 3% PN incorporated in a 40% HP gel for 45 minutes.

Effects of golden tomato extract on skin appearance-outlook into gene expression in cultured dermal fibroblasts and on trans-epidermal water loss and skin barrier in human subjects.

Scope: Two experiments were performed to test the effects of rich tomato extract (Golden Tomato Extract, GTE) on human skin. In one experiment, the effects of this extract on gene expression in cultured human dermal fibroblasts were examined. In a second experiment, human subjects consumed the extract and trans-epidermal water loss (TEWL), and aspects of skin appearance were monitored.

Synopsis of Barrier Function of Skin and Oral Mucosa-Volume 1.

This is an attempt to make readers of the second edition of Special Issue on the Barrier Function of Skin and Oral Mucosa aware of the content of the first edition on this same topic [...

Roles of Lipids in the Permeability Barriers of Skin and Oral Mucosa.

PubMed searches reveal much literature regarding lipids in barrier function of skin and less literature on lipids in barrier function of the oral mucosa. In terrestrial mammals, birds, and reptiles, the skin's permeability barrier is provided by ceramides, fatty acids, and cholesterol in the outermost layers of the epidermis, the stratum corneum. This layer consists of about 10-20 layers of cornified cells embedded in a lipid matrix.

Lipid Metabolic Events Underlying the Formation of the Corneocyte Lipid Envelope.

Cornified cells of the stratum corneum have a monolayer of an unusual lipid covalently attached to the outer surface. This is referred to as the corneocyte lipid envelope (CLE). It consists of a monolayer of ω-hydroxyceramides covalently attached to the outer surface of the cornified envelope.

Innate Antimicrobial Defense of Skin and Oral Mucosa.

This special issue intends to review and update our understanding of the antimicrobial defense mechanisms of the skin and oral cavity. These two environments are quite different in terms of water, pH, and nutrient availability, but have some common antimicrobial factors. The skin surface supports the growth of a limited range of microorganisms but provides a hostile environment for others.

Lipids and the Permeability and Antimicrobial Barriers of the Skin.

The primary purpose of the epidermis of terrestrial vertebrates is to produce the stratum corneum, which serves as the interface between the organism and the environment. As such, the stratum corneum provides a permeability barrier which both limits water loss through the skin and provides a relatively tough permeability barrier. This provides for a degree of resistance to mechanical trauma and prevents or limits penetration of potentially harmful substances from the environment.

Epidermal Lamellar Granules.

In the mid-1950s and 1960s, transmission electron microscopes became widely available, leading to many studies of the ultrastructure of various tissues including the epidermis. Most of these studies involved tissue fixation with formaldehyde and postfixation with osmium tetroxide. A few studies employed freeze-fracture electron microscopy.

Naturally occurring ω-Hydroxyacids.

ω-Hydroxyacids are fatty acids bearing a hydroxyl group on the terminal carbon. They are found in mammals and higher plants and are often involved in providing a permeability barrier, the primary purpose of which is to reduce water loss. Some ω-hydroxyacid derivatives may be involved in waterproofing and signalling.

The Effect of Delivery System and Light Activation on Tooth Whitening Efficacy and Hydrogen Peroxide Penetration.

Purpose: To evaluate the whitening efficacy of a new two-layer technology in-office system compared to a conventional gel-type system and determine hydrogen peroxide penetration (HPP) into the pulp cavity.

Materials And Methods: Extracted molars (n = 60) were assigned to group NC: glycerol gel; group QPRO: 20% HP varnish (Zoom Quick Pro, Philips Oral Healthcare); group ZOOM_NL: 25% HP gel (Zoom Chairside Whitening); and group ZOOM_WL: 25% HP gel (Zoom Chairside Whitening) with light-activation. HPP levels were estimated with leucocrystal-violet and horseradish-peroxidase.

Time Course of Potassium Nitrate Penetration into the Pulp Cavity and the Effect of Penetration Levels on Tooth Whitening Efficacy.

Objectives: To establish time-course of potassium nitrate (PN) penetration into the pulp cavity, and determine whether PN pretreatment would affect whitening efficacy.

Materials And Methods: Extracted teeth (n = 100) were randomized into five groups of 20 specimens each. Relief ACP (Philips Oral Healthcare, Los Angeles, CA, USA) was applied for 0, 5, 15, 30, and 60 minutes for groups 15, respectively.

Differential cytotoxicity of long-chain bases for human oral gingival epithelial keratinocytes, oral fibroblasts, and dendritic cells.

Long-chain bases, found in the oral cavity, have potent antimicrobial activity against oral pathogens. In an article associated with this dataset, Poulson and colleagues determined the cytotoxicities of long-chain bases (sphingosine, dihydrosphingosine, and phytosphingosine) for human oral gingival epithelial (GE) keratinocytes, oral gingival fibroblasts (GF), dendritic cells (DC), and squamous cell carcinoma (SCC) cell lines [1]. Poulson and colleagues found that GE keratinocytes were more resistant to long-chain bases as compared to GF, DC, and SCC cell lines [1].

Protein Analysis of Sapienic Acid-Treated Porphyromonas gingivalis Suggests Differential Regulation of Multiple Metabolic Pathways.

Unlabelled: Lipids endogenous to skin and mucosal surfaces exhibit potent antimicrobial activity against Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. Our previous work demonstrated the antimicrobial activity of the fatty acid sapienic acid (C(16:1Δ6)) against P. gingivalis and found that sapienic acid treatment alters both protein and lipid composition from those in controls.

Spectrophotometric Evaluation of Potassium Nitrate Penetration Into the Pulp Cavity.

Objectives: The aim of this study was to evaluate the penetration level of potassium nitrate-containing desensitizers or whitening materials into the pulp cavity with regard to the concentration and viscosity of the formulation.

Methods And Materials: Fifty extracted human molar teeth were prepared and randomized into five groups of 10 specimens each. The control received a 30-minute treatment without any treatment material; the other four groups corresponded to treatment with DayWhite, a 14% hydrogen peroxide whitening material containing potassium nitrate; PreviDent 5000 Sensitive, a desensitizing toothpaste; Relief ACP, a desensitizing gel; or UltraEZ, a desensitizing gel.

Differential cytotoxicity of long-chain bases for human oral gingival epithelial keratinocytes, oral fibroblasts, and dendritic cells.

Long-chain bases are present in the oral cavity. Previously we determined that sphingosine, dihydrosphingosine, and phytosphingosine have potent antimicrobial activity against oral pathogens. Here, we determined the cytotoxicities of long-chain bases for oral cells, an important step in considering their potential as antimicrobial agents for oral infections.

Review of the Mechanism of Tooth Whitening.

Purpose: This review integrated the current literature on diffusion of whitening agents, their interactions with stain molecules, and changes to the surface, with the aim of establishing a better understanding of the mechanism underlying tooth whitening.

Materials And Methods: An electronic PubMed database search, with combinations of the following terms was performed: Tooth Bleaching, Tooth Bleaching Agent, Hydrogen Peroxide, Pharmacokinetics, Tooth Permeability, Oxidation-Reduction, Tooth Demineralization, and Color.

Results: Tooth whitening is a dynamic process that involves diffusion of the whitening material to interact with stain molecules and also involves micromorphologic alterations on the surface and changes within the tooth that affect its optical properties.

The roles of cutaneous lipids in host defense.

Lauric acid (C12:0) and sapienic acid (C16:1Δ6) derived from human sebaceous triglycerides are potent antimicrobials found at the human skin surface. Long-chain bases (sphingosine, dihydrosphingosine and 6-hydroxysphingosine) are also potent and broad-acting antimicrobials normally present at the skin surface. These antimicrobials are generated through the action of ceramidases on ceramides from the stratum corneum.

Current understanding of skin biology pertinent to skin penetration: skin biochemistry.

The purpose of this review is to summarize some of the biochemical or chemical findings that have contributed most significantly to our current understanding of the permeability barrier of the skin. This literature survey covers the period from the 1970s up to the present. This seems appropriate since earlier progress was comprehensively covered in a 1978 review by Bob Scheuplein entitled 'Permeability of the skin: a review of major concepts' and in the earlier review by Scheuplein and Blank entitled 'Permeability of the skin'.

Oral mucosal lipids are antibacterial against Porphyromonas gingivalis, induce ultrastructural damage, and alter bacterial lipid and protein compositions.

Oral mucosal and salivary lipids exhibit potent antimicrobial activity for a variety of Gram-positive and Gram-negative bacteria; however, little is known about their spectrum of antimicrobial activity or mechanisms of action against oral bacteria. In this study, we examine the activity of two fatty acids and three sphingoid bases against Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. Minimal inhibitory concentrations, minimal bactericidal concentrations, and kill kinetics revealed variable, but potent, activity of oral mucosal and salivary lipids against P.

Organization, barrier function and antimicrobial lipids of the oral mucosa.

As one moves from the skin across the vermilion region of the lip and into the oral cavity, the oral mucosa is encountered. The oral mucosa consists of connective tissue known as the lamina propria covered by a stratified squamous epithelium. In the regions of the hard palate and gingiva, the epithelium is keratinized like the epidermis.

Sphingoid bases are taken up by Escherichia coli and Staphylococcus aureus and induce ultrastructural damage.

Sphingoid bases found in the outer layers of the skin exhibit antimicrobial activity against gram-positive and gram-negative bacteria. We investigated the uptake of several sphingoid bases by Escherichia coli and Staphylococcus aureus, and assessed subsequent ultrastructural damage. E.