The fibrous proteins of stratum corneum

The proteins of cow snout stratum corneum can be extracted in part with Tris buffer, pH 9.0, containing 6 M urea. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis shows that about half the extracted material migrates as prekeratin when the extract is treated with both SDS and mercaptoethanol; only trace amounts of the proteins migrating as prekeratin are seen when SDS alone is used. The urea extract gives precipitin lines to an antibody against prekeratin. After exhaustive extraction with the Tris-urea buffer an additional amount of protein is solubilized by extraction with buffer containing mercaptoethanol. This extract shows an electrophoretic pattern similar but not identical to prekeratin. These results suggest that the stratum corneum contains fibrous proteins with different degrees of cross-linking. An analogous system has also been observed in human stratum corneum.     

Defects generated in human stratum corneum specimens by ultrasound

Over the last two decades, ultrasound (US) has been applied to enhance transdermal drug delivery. This method is called sonophoresis. The physical mechanism of the enhancement is far from being fully understood. It has been shown in our study that 168-kHz continuous US of spatially averaged pressure amplitude of 1.9 x 10(5) Pa induced a new structural state and generated defects (entrapped air pockets) in human stratum corneum specimens. The dimensions of the defects were found to be about 20 microns, large enough to allow the transdermal passage of high-molecular-weight drug molecules that normally elude the unenhanced transdermal drug delivery.     

Influence of vitamin E acetate on stratum corneum hydration

The influence of vitamin E (tocopherol, CAS 10191-41-0) on stratum corneum hydration was tested in O/W and W/O emulsions. Additionally, the O/W emulsion was used in an in vivo/in vitro method to gravimetrically obtain evidence concerning the water-binding capacity of the stratum corneum. In the W/O emulsion, 2.5%, 5%, and 7.5% vitamin E were compared. With both types of emulsions, vitamin E increased the stratum corneum hydration statistically significantly (p = 0.0002). In addition, we could provide evidence of an enhanced water-binding capacity after treatment with vitamin E (p = 0.05). For the hydrating effect of vitamin E. its concentration is of importance. The optimum concentration turned out to be 5%.     

A proton magnetic resonance study of water in human stratum corneum

Proton magnetic resonance spectroscopy has been used to study the nature of water in human stratum corneum. For a single planar sheet of stratum corneum mounted at a specific orientation to the applied magnetic fild, three distinct absorptions may be seen having different chemical shifts and spin-lattice relaxation times (T1). All T1 values for these resonances are smaller than that for normal liquid water. One absorption is unusual in that the resonance position is dependent upon the orientation of the sample within the field.     

Expression of cell membrane complement regulatory glycoproteins along the normal and diseased human gastrointestinal tract

The viral coat of the HIV-1 virus, gp120, has been shown to cross the blood-brain barrier (BBB) in lectin-like fashion by inducing adsorptive endocytosis (AE), a vesicular mechanism that could provide pathways into and across brain endothelial cells for virus and infected immune cells. Here, we extended those findings to show that gp120 slowly crossed the BBB with about 0.15% of an intravenously injected dose entering the brain after about 2 hr. The plant lectin glycoprotein wheat germ agglutinin (WGA) greatly enhanced gp120 crossing without disrupting the BBB. WGA enhanced the uptake of gp120 into all peripheral tissues studied, but the greatest percent increase occurred for brain, whereas another barrier tissue, the testis, had the least increase. Five other plant lectins tested had little or no effect on gp120 uptake by brain, suggesting a key role for sialic acid and N-acetyl-beta-D-glucosaminyl acid, the sugars to which WGA binds, in the uptake of gp120 by brain endothelial cells. WGA did not enhance the uptake of nonglycosylated gp120 and the uptake of gp120 was not self-inhibitable or altered by pretreatment of mice with aluminum. In conclusion, these studies show that gp120 crosses the BBB by a lectin-like mechanism resembling AE that is likely mediated by binding to specific sugar moieties and is rather selective for brain.     

Modulation of human stratum corneum properties by salicylic acid and all-trans-retinoic acid

Topical all-trans-retinoic acid (RA) has been reported to decrease the in vivo skin response to sodium lauryl sulfate (SLS). The converse was also shown with a synergistic effect of RA following prior applications of SLS. The reason for such effects is not clear. We employed measures of transepidermal water loss (TEWL), squamometry and sequential corneosurfametry to explore the protective activity of a 0.05% RA cream at the level of the stratum corneum. Nonionic oil-in-water emulsions with or without 5% salicylic acid (SA) served as test product references. Data indicated that the RA formulation was responsible for a stochastic impairment in the TEWL and for an increased intercorneocyte cohesion. SA and the unmedicated emulsion did not lead to similar TEWL changes. The squamometry test proved to be very sensitive to disclose the effects of SA and RA without, however, allowing to distinguish the difference in the physiological processes involved. The corneosurfametry bioassay did not show any protection or synergistic effect between RA or SA and SLS challenge on the stratum corneum. This is in contrast to a previous work showing a positive protective effect afforded by retinol against SLS. The combined effects of irritant compounds affecting the stratum corneum are complex. The precise reason for some of their biological consequences remains a conundrum. On balance, products such as SA and RA do not appear to afford protection or impairment to a surfactant challenge at the level of the stratum corneum.     

Loss of water from the stratum corneum induces epidermal DNA synthesis in hairless mice

Many clinical studies have shown that low humidity has a deleterious effect on skin, but the mechanisms involved are poorly understood. To clarify the changes that occur in skin, we examined epidermal cell proliferation in mice kept in a dry (relative humidity < 10%) or a moist (relative humidity > 90%) environment. In animals exposed to low humidity, epidermal DNA synthesis started to increase within 12 h, reaching twice the original level, and the increased level was maintained for up to 5 days. The transepidermal water loss (TEWL) of mice kept for 12 h in the dry environment was the same as that of mice kept in the moist environment, but the skin conductance was lower. The increase in epidermal DNA synthesis following exposure to the dry environment was inhibited by topical application of petrolatum. It is concluded that loss of water from the stratum corneum induces epidermal cell proliferation within 12 h, and this change occurs in the absence of apparent cutaneous barrier dysfunction.     

Imaging regions of transport across human stratum corneum during high-voltage and low-voltage exposures

Scanning confocal fluorescence microscopy was used to image localized regions of calcein transport across human stratum corneum during constant low-voltage (iontophoresis) and pulsed high-voltage exposures. Following an electrical protocol, imaging revealed regions of fluorescence which were interpreted as sites where transport of a fluorescent probe (calcein) into the stratum corneum had taken place. Electrically-assisted transport of calcein, whether enhanced by iontophoresis or high-voltage pulsing, appears to occur through intercellular and, to some extent, transcellular pathways into localized regions of stratum corneum that are not associated with appendages. Uniquely associated with the highest voltage pulses used (300 V across the skin) was the appearance of small, brightly fluorescent areas containing nonfluorescent interiors, i.e., fluorescent rings. We present evidence which suggests that the dark interiors represent sites through which transport occurred during pulsing, but where calcein was no longer present at the time of imaging. Transport of charged microspheres into the stratum corneum was also observed.     

Differences in stratum corneum pH gradient when comparing white Caucasian and black African-American skin

This study assessed pH gradient changes in relation to stratum corneum (SC) depth and possible differences between white caucasian and black African-American skin. Ten white and eight black people entered the study. SC was progressively removed by cellophane tape stripping on the volar forearm and weighed with a microbalance. Transepidermal water loss (TEWL) and SC pH were measured every three tape strippings. Significantly increased TEWL and decreased pH values were found with increasing SC depth in both races. Significantly increased TEWL in black people was found after three and six tape strippings (P < 0.05 and 0.03, respectively); pH was significantly decreased in black people after three tape strippings (P < 0.005). No differences were found between the races after nine, 12 and 15 strippings, i.e. in the deeper SC layers. The data confirm that pH in the superficial SC layers decreases with SC depth; only total SC removal results in increased pH values. In the superficial layers, there are significant differences in both water evaporation and skin pH, possibly explaining the contradictory literature.     

Compartmentation of the granular layer of the cerebellum

Numerous studies have demonstrated that the cerebellum is highly compartmentalized. In most cases, compartmentation involves the Purkinje cells and the molecular layer, but there is also substantial evidence that the granular layer is subdivided into a large number of highly reproducible modules. We first review the evidence for a modular granular layer. Compartmentation of the granular layer has been revealed both functionally and structurally. First, tactile receptive field mapping has revealed numerous discrete functional modules within the granular layer. The molecular correlates of the receptive fields may be the compartments revealed by histological staining of the cerebellum for several enzymes and antigens. The structural substrate of the receptive fields is the mossy fiber afferent projection map, and anterograde tracing of various mossy fiber projections shows afferent terminals in parasagittal bands within the granular layer that are topographically aligned with the Purkinje cell compartments. Based on this evidence we argue that the cerebellum consists of many hundreds of reproducible structural/functional modules, and that a modular organization is a prerequisite for the efficient parallel processing of information during motor control. The complex organization of the adult granular layer implies elaborate developmental mechanisms. In the second part of the review we consider five developmental models to generate the modular organization of the adult granular layer: 1) the external granular layer is heterogeneous, and its topography translates directly into a modular granular layer; 2) granular layer modules are clones, derived from single external granular layer precursors; 3) modules in the granular layers are a secondary epigenetic response to the compartmentation of the Purkinje cells; 4) modules are secondary to the compartmentation of the afferent terminal fields; 5) modules are sculpted by activity-dependent processes.     

Regional differences in stratum corneum reactivity to surfactants. Quantitative assessment using the corneosurfametry bioassay

A highly sensitive and specific chemiluminescent immunoassay (CLIA) was developed for quantification of growth hormone (GH) in salmonid species. The CLIA for salmon GH was performed using the sandwich method with anti-GH IgG as the first antibody and chemiluminescent acridinium ester-labelled specific anti-GH F(ab')2 as the second antibody. The measurable range of salmon GH in the CLIA was 39-1250 pg/mL using a short assay (1 day) protocol and 3.9-125 pg/mL in a longer (2-day) assay. The dilution curve in the CLIA of serum from masu salmon (Oncorhynchus masou) was parallel to the standard curve of recombinant chum salmon (Oncorhynchus keta) GH. Seasonal changes of serum GH levels were measured in 1 year-old masu salmon cultivated in a pond from March to November. Their serum GH levels increased during smoltification from March to April, achieved a maximum level of 21 ng/mL in August, and then declined gradually to 11 ng/mL in October.     

Levels of terbinafine in plasma, stratum corneum, dermis-epidermis (without stratum corneum), sebum, hair and nails during and after 250 mg terbinafine orally once per day for four weeks

The paper uses the stimulus of a personal reflection to explore how the concept of reflective practice can be facilitated. The thoughts on facilitation combine the use of recognised knowledge, experience and reflection to offer a way of reducing the risk of rejection of reflective practice. In setting the context for such an exploration, reflective practice is defined and its potential contribution to nursing considered.     

Insulin-like growth factor-I expression in normal and diseased endometrium

While the role of steroid hormones in the regulation of endometrial proliferation and differentiation is well established, the effects of growth factors and their receptors in normal and neoplastic endometrium remain a matter of debate. Previous studies have documented the positive effects of insulin-like growth factor-I (IGF-I) on epithelial cell proliferation and the active production of this growth factor in endometrial tissues. In view of decreased expression of transforming growth factor-beta1 (TGF-beta1), an antagonist of IGF-I, in endometrial carcinoma, we investigated the expression of IGF-I, at both the mRNA and protein levels, and the immunoreactivity for type I IGF-I receptor in 30 formalin-fixed, paraffin-embedded tissue samples of normal and neoplastic endometrium, in order to possibly clarify the role of IGF-I in endometrial proliferation and differentiation. Our results demonstrate a reduced expression of IGF-I mRNA in endometrial carcinomas compared with non-neoplastic tissues, despite equivalent immunohistochemical expression of IGF-I and IGF-I receptor. Our data suggest that IGF-I and its corresponding receptor may not be directly involved in endometrial cancer cell proliferation and differentiation in vivo, though other components of the IGF-I system (e.g., IGF binding proteins) may affect endometrial malignant transformation and tumor progression.     

Entropy-driven binding/partition of amino acids/dipeptides to stratum corneum lipid vesicles

This study employed large unilamillar vesicles composed of purchased stratum corneum lipids to investigate the binding/partition of amino acids/dipeptides to stratum corneum lipid vesicles. The partition coefficients of amino acids/dipeptides between the stratum corneum lipid vesicles and the acetate buffer were determined by HPLC. In addition, the binding/partition enthalpy of amino acids/dipeptides with the stratum corneum lipid vesicles was derived by directly measuring the binding/partition heat with isothermal titration calorimetry. According to the binding/petition Gibbs free energy and the binding/partition enthalpy, all the binding/partition of amino acids/dipeptides with the stratum corneum lipid vesicles is endothermic, implying an entropy-driven binding/partition. Also, the equilibrium binding/partition results demonstrate that the partition coefficients of amino acids/dipeptides do not correlate with the transdermal permeability. This finding suggests that either the interaction between the penetrants and the lipid bilayer between corneocytes may not be a determining step or that the paracellular path is not a dominant route of transdermal penetration.     

Expression of mu-opiate receptor in human epidermis and keratinocytes

Chronic wasting disease (CWD), a member of the transmissible spongiform encephalopathies (TSEs), was first identified in captive mule and black-tail deer in 1967. Due to the failure to transmit CWD to rodents, we investigated the use of ferrets (Mustela putorius furo) as a small animal model of CWD. The inoculation of CWD into ferrets resulted in an incubation period of 17-21 months on primary passage that shortened to 5 months by the third ferret passage. The brain tissue of animals inoculated with ferret-passaged CWD exhibited spongiform degeneration and reactive astrocytosis. Western blot analysis of ferret-passaged CWD demonstrated the presence of PrP-res. Unlike mule deer CWD, ferret-passaged CWD was transmissible to Syrian golden hamsters (Mesocricetus auratus). Increasing the passage number of CWD in ferrets increased the pathogenicity of the agent for hamsters. This increase in host range of a field isolate on interspecies transmission emphasizes the need for caution when assessing the potential risk of transmission of TSEs, such as bovine spongiform encephalopathy, to new host species.     

Identification and activity of cytosol creatine phosphokinase enzymes in normal and diseased skin

Phosphocreatine molecules (PCR) in skin regenerate adenosine triphosphate and help cutaneous tissue survive ischemia associated with skin flaps, grafts, and hair transplantation procedures. In addition, PCR concentration in psoriasis is elevated many times above normal, indicating either overproduction of PCR by mitochondrial creatine phosphokinase (CPK) enzymes or a defect in cytosol CPK enzymatic activity. Skin CPK isoenzymes, before this study, have not been identified. Herein, for the first time, cytosol CPK enzymatic activity was measured in normal and psoriatic, involved and uninvolved skin, skin tumors, and mouse skin and keratinocyte cell cultures. Creatine phosphokinase MM is the major isoenzyme in normal, uninvolved psoriatic and mouse skin. Total CPK enzymatic activity was increased in psoriasis and skin tumors. These data clearly indicate that increased PCR concentration in a psoriatic skin is not a result of decreased cytosol CPK enzymatic activity.