Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “stratum”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2000

Stratum corneum tryptic enzyme in normal epidermis: a missing link in the desquamation process?

Stratum corneum chymotryptic enzyme may be important in desquamation. It has also been suggested that other proteases, especially stratum corneum tryptic enzyme, may be involved. Stratum corneum tryptic enzyme has been purified and its cDNA has been cloned. Results from expression analyses indicate that stratum corneum tryptic enzyme is as skin specific as stratum corneum chymotryptic enzyme. In this work we have produced and characterized antibodies specific for stratum corneum tryptic enzyme. We have also by means of biochemical, immunochemical, and immunohistochemical methods performed studies on stratum corneum tryptic enzyme in normal human epidermis. Antibodies against bacterial recombinant stratum corneum tryptic enzyme were produced and purified by affinity chromatography. Two types of antibodies were obtained: one reacting only with pro-stratum corneum tryptic enzyme and one specific for the catalytically active part of stratum corneum tryptic enzyme. Immunohistochemistry with the antibodies reacting with pro-stratum corneum tryptic enzyme showed a staining pattern similar to stratum corneum chymotryptic enzyme-specific antibodies, i.e., the expression was confined to cornifying epithelia with a need of desquamation-like processes. Extracts of tape strips with superficial human stratum corneum were found to contain precursors as well as active forms of stratum corneum tryptic enzyme and stratum corneum chymotryptic enzyme. The enzymes had maximal activity at pH 8, but both had considerable activity also at pH 5.5. The results were compatible for a role of stratum corneum tryptic enzyme in desquamation. Stratum corneum tryptic enzyme may act in concert with stratum corneum chymotryptic enzyme and/or function as a stratum corneum chymotryptic enzyme-activating enzyme. The presence in normal superficial stratum corneum of precursors as well as of active forms of stratum corneum chymotryptic enzyme and stratum corneum tryptic enzyme, and the activity of both enzymes over a broad range of pH-values, suggest some possible ways by which the desquamation may be regulated.

Epidermis↗
PubMed1991

Stratum corneum lipids serve as a bound-water modulator.

Stratum corneum lipids have been found to be an important determinant involved in the water-holding function of the stratum corneum. In order to further elucidate the significance of stratum corneum lipids in the water-holding properties, the hydration behavior of the stratum corneum following depletion and replenishment of the lipids has been studied, using an isolated human forearm stratum corneum sheet, by differential scanning calorimetry parallel to ultrastructural changes of intercellular lipids in the stratum corneum. Extraction of the stratum corneum sheet with acetone/ether (1/1) decreased the bound-water content from 33.3% to 19.7%, where the melting temperature of ice remained constant. Further extraction with water, which released a large amount of water-soluble materials such as amino acids, did not change the bound-water content, but definitely raised the melting temperature of ice. The application of the stratum corneum lipids, which were solubilized in squalane containing 1% alpha-monomethyl heptadecyl glyceryl ether to the lipid-depleted stratum corneum sheet, caused a significant recovery of bound-water content to the previous, almost normal level. In accordance with the hydration behavior, electron microscopic analysis of the acetone/ether-treated stratum corneum sheet revealed selective depletion of lipids from the intercellular spaces, accompanied by a marked disruption of multiple lamellar structures. In contrast, the application of stratum corneum lipids into the lipid-depleted stratum corneum sheet resulted in the restoration of the lamellar structure between the stratum corneum cells. These findings strongly suggest that stratum corneum lipids serve a water-holding function through the formation of lamellar structures within the stratum corneum.

Adult↗
PubMed2001

Generation of free fatty acids from phospholipids regulates stratum corneum acidification and integrity.

There is evidence that the "acid mantle" of the stratum corneum is important for both permeability barrier formation and cutaneous antimicrobial defense. The origin of the acidic pH of the stratum corneum remains conjectural, however. Both passive (e.g., eccrine/sebaceous secretions, proteolytic) and active (e.g., proton pumps) mechanisms have been proposed. We assessed here whether the free fatty acid pool, which is derived from phospholipase-mediated hydrolysis of phospholipids during cornification, contributes to stratum corneum acidification and function. Topical applications of two chemically unrelated secretory phospholipase sPLA2 inhibitors, bromphenacylbromide and 1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol, for 3 d produced an increase in the pH of murine skin surface that was paralleled not only by a permeability barrier abnormality but also altered stratum corneum integrity (number of strippings required to break the barrier) and decreased stratum corneum cohesion (protein weight removed per stripping). Not only stratum corneum pH but also all of the functional abnormalities normalized when either palmitic, stearic, or linoleic acids were coapplied with the inhibitors. Moreover, exposure of intact murine stratum corneum to a neutral pH for as little as 3 h produced comparable abnormalities in stratum corneum integrity and cohesion, and further amplified the inhibitor-induced functional alterations. Furthermore, short-term applications of an acidic pH buffer to inhibitor-treated skin also reversed the abnormalities in stratum corneum integrity and cohesion, despite the ongoing decrease in free fatty acid levels. Finally, the secretory-phospholipase-inhibitor-induced alterations in integrity/cohesion were in accordance with premature dissolution of desmosomes, demonstrated both by electron microscopy and by reduced desmoglein 1 levels in the stratum corneum (shown by immunofluorescence staining and visualized by confocal microscopy). Together, these results demonstrate: (i) the importance of phospholipid-to-free-fatty-acid processing for normal stratum corneum acidification; and (ii) the potentially important role of this pathway not only for barrier homeostasis but also for the dual functions of stratum corneum integrity and cohesion.

Acetophenones↗
PubMed1984

Stratum corneum lipids in disorders of cornification. Steroid sulfatase and cholesterol sulfate in normal desquamation and the pathogenesis of recessive X-linked ichthyosis.

The pathological scaling in recessive x-linked ichthyosis is associated with accumulation of abnormal quantities of cholesterol sulfate in stratum corneum (J. Clin. Invest. 68:1404-1410, 1981). To determine whether or not cholesterol sulfate accumulates in recessive x-linked ichthyosis as a direct result of the missing enzyme, steroid sulfatase, we quantitated both steroid sulfatase and its substrate, we quantitated both steroid sulfatase and its substrate, cholesterol sulfate, in different epidermal strata, as well as within stratum corneum subcellular fractions obtained from normal human and neonatal mouse epidermis and from patients with recessive x-linked ichthyosis. In normal human and mouse epidermis, steroid sulfatase activity peaked in the stratum granulosum and stratum corneum, and negligible activity was detectable in lower epidermal layers. In contrast, in recessive x-linked ichthyosis epidermis, enzyme levels were virtually undetectable at all levels. In normal human stratum corneum, up to 10 times more steroid sulfatase activity was present in purified peripheral membrane preparations than in the whole tissue. Whereas in normal human epidermis cholesterol sulfate levels were lowest in the basal/spinous layer, and highest in the stratum granulosum, in recessive x-linked ichthyosis the levels were only slightly higher in the lower epidermis, but continued to climb in the stratum corneum. In both normal and in recessive x-linked ichthyosis stratum corneum, cholesterol sulfate appeared primarily within membrane domains, paralleling the pattern of steroid sulfatase localization. Finally, the role of excess cholesterol sulfate in the pathogenesis of recessive x-linked ichthyosis was directly tested by topical applications of this substance, which produced visible scaling in hairless mice in parallel to an increased cholesterol sulfate content of the stratum corneum. These results demonstrate an intimate relationship between steroid sulfatase and cholesterol sulfate in normal epidermis: both are concentrated in the outer epidermis (stratum corneum and stratum granulosum), and both are localized to membrane domains. Presumably, as a result of this distribution pattern, continued enzymatic degradation of substrate occurs in normal epidermis, thereby preventing excessive accumulation of cholesterol sulfate. In contrast, in recessive x-linked ichthyosis, degradation of cholesterol sulfate does not occur and cholesterol sulfate accumulates specifically in the stratum corneum, where it produces visible scale.

Administration, Topical↗
PubMed1997

Interneurons in the stratum lucidum of the rat hippocampus: an anatomical and electrophysiological characterization.

The anatomical and electrophysiological properties of neurons in the stratum lucidum of the CA3 subfield of the hippocampus were examined by using patch-pipette recordings combined with biocytin staining. This method facilitated the analysis of the morphological features and passive and active properties of a recently described class of spiny neurons in the stratum lucidum, as well as aspiny neurons in this region. Some, but not all, synaptic inputs of both types of neurons were found to arise from the mossy fiber system. The axons of spiny neurons in the stratum lucidum were heavily collateralized, terminating primarily in the stratum lucidum and stratum radiatum of CA3, and to a lesser extent in the stratum pyramidale and stratum oriens. Only a few axonal projections were found that extended beyond the CA3 region into CA1 and the hilus. Aspiny neurons fell into two classes: those projecting axons to the stratum lucidum and stratum radiatum of CA3 and those with axon terminations mainly in the stratum pyramidale and stratum oriens. The electrophysiological properties of spiny and aspiny neurons in the stratum lucidum were similar, but on average, the aspiny neurons had significantly higher maximal firing rates and narrower action potential half-widths. The results demonstrate that a diverse population of neurons exists in the region of mossy fiber termination in area CA3. These neurons may be involved in local-circuit feedback, or feed-forward systems controlling the flow of information through the hippocampus.

Animals↗
PubMed1987

Measurement of the stratum corneum drug reservoir to predict the therapeutic efficacy of topical iododeoxyuridine for herpes simplex virus infection.

A rapid, in vivo measurement of the penetration of antiviral compounds into the skin would improve our ability to predict the therapeutic efficacy of topical treatments for herpes simplex virus (HSV) infection. We have studied the concentration of iododeoxyuridine (IDU) in the stratum corneum of guinea pig skin by tape stripping at different time points after single and multiple topical doses of the drug. These results were correlated with the efficacy of topical IDU against an experimental cutaneous HSV infection. Ten adhesive tape strippings were performed on depilated guinea pig dorsum in vivo at serial intervals after a single topical dose of [3H]IDU. Iododeoxyuridine levels in the stratum corneum peaked at 1-3 h (67-70 mg/g of tissue) and then gradually declined over the next 3-24 h. We hypothesized that the peak IDU stratum corneum concentration would correlate with therapeutic efficacy. Accordingly, we determined the quantity of IDU in guinea pig stratum corneum 2 h after a topical application of seven different concentrations of IDU in dimethylsulfoxide (DMSO) and examined the in vivo efficacy of these formulations in an experimental dorsal cutaneous HSV-1 infection in guinea pigs. The results showed an excellent correlation between the quantity of IDU in the stratum corneum and reduction in lesion severity (r = 0.95-0.97). Fifteen percent IDU in DMSO provided the highest therapeutic efficacy (90-94%). We also studied the relationship between the clinical efficacy of different dosing frequencies and the amount of IDU in the stratum corneum. Serial IDU stratum corneum concentrations were measured over 24 h following 1, 2, 3, or 4 applications per day of 1, 3, and 15% IDU in DMSO treatments and parallel efficacy studies of the different regimens were conducted in the animal model. Within each dosing frequency, the cumulative amount of drug in the stratum corneum correlated with the strength of the test formulation and with efficacy in the animal model. For each of the three formulations, increasing the number of daily doses from one up to three led to progressive increases in cumulative stratum corneum IDU levels and clinical efficacy. An increase in the number of daily applications to four had little effect on drug efficacy and was associated with a plateau in stratum corneum IDU levels. Stratum corneum IDU concentrations were rapid and easy to determine and correlated well with clinical events.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Topical↗