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C J Skerrow

Publications and source records attributed to C J Skerrow.

18 recordsLinked to original sources
PubMed1989

Type IV collagen and laminin staining patterns in benign and malignant cutaneous lesions.

The presence of both laminin and type IV collagen was sought at the dermo-epidermal junction and in the dermis adjacent to benign melanocytic naevi of the junctional, compound, and intradermal types; dysplastic naevi; and both primary and secondary melanoma. In all, 154 lesions were studied, using antibodies to laminin and type IV collagen and an indirect immunoperoxidase technique. The staining patterns seen with the two antibodies were virtually identical, although that of laminin was generally fainter. Breaks in and thinning of the normally continuous line of type IV collagen and laminin at the dermo-epidermal junction were seen in association with the junctional activity of benign naevi, and in malignant melanomas in association with invasive tumour cells. Both benign and malignant cells of the melanocyte series showed relatively light pericellular staining around individual cells and clusters of cells in the papillary dermis. This staining pattern was much stronger in the deeper reticular dermis. It is concluded that the pattern of staining of these two antibodies and in particular the presence of breaks in type IV collagen and laminin at the dermo-epidermal junction are not specific for either benign or malignant melanocytic lesions and cannot be used as a diagnostic marker of invasive malignancy.

Collagen↗
PubMed1989

Changes to desmosomal antigens and lectin-binding sites during differentiation in normal human epidermis: a quantitative ultrastructural study.

During epidermal differentiation, desmosomes undergo a series of changes in their abundance, structure and properties, which has previously been defined by conventional electron microscopy and the use of antibodies to desmosomal proteins at the light-microscope level. Such changes in a major adhesive organelle would be expected to have a significant role in the maintenance of epidermal organization, and therefore require more detailed characterization. In the present study, modifications to certain desmosomal components in normal human epidermis have been located and quantified by immunogold electron microscopy. Antibodies to desmosomal protein dp3 and glycoprotein dg1 were used to label the cytoplasmic regions of the junctions and lectins concanavalin A (ConA) and wheat germ agglutinin (WGA) to probe the extracellular glycosylated material. Binding was measured at histologically defined levels and expressed as gold particles per microns of desmosome length (linear particle density: LPD). In addition, desmosome frequency, expressed as the percentage of the cell membrane length occupied by desmosomes, was measured. Highly significant changes in desmosome frequency, diameter and LPD were observed between epidermal strata and, in basal and upper horny cells, between different regions of the same cell surface. These parameters rose to a maximum in the spinous or granular layers: their subsequent decrease continued without interruption across the interface between the living and terminally differentiated horny layers. Remaining reactivity with antibodies, but not lectins, was almost completely abolished immediately before the final disintegration of the desmosome structure in the lower horny layer. In contrast, numerous large, highly immunoreactive desmosomes were retained up to the outer surface in the grossly thickened horny layer found in callus. Though the overall pattern of a rise followed by a fall was similar for all parameters measured, differences were observed between probes. Thus, the extent of the rise in available antigen between the lateral and apical surfaces of the basal cell was greater for dg1 than for dp3; the subsequent decrease in dp3 antigens in upper epidermal layers was more rapid than that for dg1, and changes to both antigens preceded those to lectin-binding sites. These results show that differences in desmosome frequency and in the size and antibody-binding characteristics of individual junctions underlie the heterogeneous distribution of desmosomal components within epidermis that is found by light-microscope immunocytochemistry. They further suggest that the disintegration of desmosomes within normal horny layer, which is an essential preliminary to desquamation, is the culmination of a sequence of events that begins in the upper living tissue and initially involves cytoplasmic components.(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens↗
PubMed1987

Epidermal alpha-keratin is neutral-buffer-soluble and forms intermediate filaments under physiological conditions in vitro.

Undenatured bovine epidermal alpha-keratin has been solubilized in a low-ionic-strength buffer at physiological pH (5 mM Tris-HCl/25 mM 2-mercaptoethanol (pH 7.5). The particles in this buffer were multimeric, retaining their characteristic polypeptide chain composition and alpha-helical coiled-coil structure. They were shown by sucrose density gradient centrifugation to be in true solution and to have a narrow size distribution. Upon the addition to this solution of monovalent or divalent cations up to physiological concentrations, the alpha-keratin rapidly assembled into intermediate filaments which showed a high tendency to aggregate laterally and disassembled if returned to low-ionic-strength conditions. This behaviour closely resembles that of other intermediate filament proteins, but it is the first time that alpha-keratins have been shown to be neutral-buffer-soluble and to assemble from such solutions into intermediate filaments under physiological conditions in vitro. This is in direct contrast to the reported properties of alpha-keratins after urea denaturation and the system appears to be appropriate for studying aspects of alpha-keratin intermediate filament formation.

Animals↗
PubMed1987

Dissection of the bovine epidermal desmosome into cytoplasmic protein and membrane glycoprotein domains.

Epidermal desmosomes contain two main regions. The core consists of a pair of membranes, one on either side of a cross-striated intercellular space bisected by a denser midline. The cytoplasmic compartment comprises a dense plaque deposited on the cytoplasmic surface of each membrane and a diffuse layer occupying the zone between the plaque and attached alpha-keratin filaments. Analysis of isolated desmosomes by SDS-PAGE has shown the presence of four major protein (dpl-4) and three major glycoprotein (dgl-3) bands, which have been allocated to the cytoplasmic and core compartments, respectively. In the present paper, we report the use of urea to fractionate this complex structure, both in situ and following isolation with citrate buffer, pH2.6. Extraction of the living layers of bovine epidermis with 9M-urea, pH7.5, resulted in rapid removal of the dense desmosomal plaques, followed by separation and vesiculation of desmosomal membranes. The resistance of the plaque to urea increased abruptly at the transition between living epidermis and dead, dehydrated horny layer. A similar sequence of morphological changes accompanied the extraction of isolated desmosomes with urea. Analysis of residues and extracts of isolated desmosomes by SDS-PAGE confirmed the selectivity of 9 M-urea, pH7.5, for the cytoplasmic compartment. The four major desmosomal proteins, dpl-4 (Mr240, 215, 90 and 83 (X 10(3)), respectively) predominated in the extracts. Desmosomal membranes, both paired and vesiculated, consisted almost entirely of the three desmosomal glycoproteins dgl-3 (Mr150, 120 and 110 (X 10(3)), respectively). These results provide evidence that all three desmosomal glycoproteins are integral membrane proteins. The separation of desmosomal membranes by urea, which is not accompanied by additional loss of proteins, further suggests that desmosomal adhesion is based on interactions between membrane components with no separate extracellular molecules being involved. The dissection of the desmosome by urea into two topographically and biochemically distinct domains should facilitate further studies on the molecular basis of desmosomal adhesion and alpha-keratin filament binding.

Animals↗
PubMed1985

Lectin binding to psoriatic epidermis.

The lectin-binding properties of psoriatic epidermis were assessed using a wide range of lectins. Changes in these properties were found at all levels of differentiation in lesional tissue. There was no clear evidence for an expansion in the population of basal-type cells. Binding of some lectins demonstrated a normal basal-suprabasal boundary. Others bound closer to the dermal-epidermal junction than in normal tissue, and expression of certain normal suprabasal characteristics was found in the basal layer in psoriasis. These findings suggest that the detected changes in psoriatic glycoconjugates reflect a programme of differentiation which is altered rather than incomplete.

Adult↗
PubMed1984

Factors affecting the binding of lectins to normal human skin.

Factors affecting the binding of a wide range of lectins to normal human skin were examined in order to evaluate current discrepancies in the literature. The profile of specific binding characteristic for each lectin was found to be variously influenced by the source of conjugate, tissue-processing method, the effectiveness of saccharide inhibitors, and by individual and minor body site variations. Most significantly, the use of routine histological processing not only greatly reduced binding intensity overall but also altered the binding pattern.

Arachis↗
PubMed1983

Tonofilament differentiation in human epidermis, isolation and polypeptide chain composition of keratinocyte subpopulations.

Epidermal tonofilaments are intermediate filaments with an unusually complex polypeptide chain composition which undergoes profound changes during differentiation. Assessment of the possible functional significance of these changes requires their correlation with defined stages of keratinocyte differentiation. Methods have, therefore, been developed for the isolation of the four keratinocyte subpopulations from human epidermis in high yield and purity without detectable damage to tonofilament chains. Trypsinization at 4 degrees C yielded sheets of granular and horny layers and a suspension of basal and spinous cells. Granular cells were removed from the horny layer sheets by mechanical action and basal cells separated from spinous cells by selective attachment to collagen. The living cell fractions were representative, by morphological and ultrastructural criteria, of their counterparts in situ. Analysis of the keratinocyte subpopulations by SDS-PAGE revealed directly their tonofilament chain composition. Basal cells contain two quantitatively major tonofilament chains (Mr 58000 and 50000). A third major chain (Mr 70000) is only synthesised suprabasally when the cells lose their ability to divide. The Mr 50000 chain is removed before the granular cell stage and several minor chains are present in the spinous and granular cells. Two chains appearing for the first time in horny cells probably result from processing during the terminal stages of differentiation. It is suggested that synthesis of the Mr 70000 chain in suprabasal keratinocytes is normally linked with their loss of mitotic ability. This may be significant in the skin disease psoriasis in which synthesis of the Mr 70000 chain is defective and the epidermis hyperproliferates.

Cell Differentiation↗
PubMed1982

Epidermolysis bullosa in association with aplasia cutis congenita and pyloric atresia.

A female infant born to a mother who had an elevated serum alpha-fetoprotein during early pregnancy, presented a combination of epidermolysis bullosa and aplasia cutis congenita. She developed evidence of upper gastrointestinal obstruction and died at the age of 43 hours. Post-mortem examination showed the presence of pyloric atresia and electron microscopy of skin biopsies showed epidermolysis bullosa simplex. Examination of the placenta revealed a unique abnormality of the membranes, indicating the existence of two sacs. This case and the previously reported cases, which are reviewed, suggest an autosomal recessive inheritance. Serum alphafetoprotein estimation, ultrasonography and fetoscopy with skin biopsy are suggested as a means of pre-natal diagnosis in future pregnancies.

Abnormalities, Multiple↗
PubMed1981

Melanin pigmentation of the skin in primary biliary cirrhosis.

A histological and ultrastructural study has demonstrated that cutaneous pigmentation in primary biliary cirrhosis (PBC) is due to the presence of increased amounts of melanin, widely dispersed throughout both epidermis and dermis. No deposits of stainable iron were observed. Compared with skin from matched sites from control patients with alcoholic cirrhosis and no pigmentation, the melanocyte: keratinocyte ratio was not significantly higher in PBC. However, in PBC, melanosomes persisted to unusually high levels in the epidermis and were packaged in larger membrane-bound clusters than was the case in the controls. Whether excess melanin results from increased melanogenesis or defective melanin degradation remains unclear, although there is some evidence favouring the latter mechanism. No hormonal (beta-MSH and ACTH) or chemical (bile salt irritation) stimuli to increase melanogenesis were demonstrated.

Adrenocorticotropic Hormone↗
PubMed1980

The experimental production of high-level intraepidermal splits.

The effects of trypsin at 37 degrees C and 4 degrees C on adhesion between keratinocytes in normal human epidermis were assessed by light and electron microscopy. The results provide evidence for the contribution of both extracellular and intracellular factors to keratinocyte adhesion and for changes in the nature of adhesion in the granular layer. Trypsinization at 4 degrees C produced a high-level intraepidermal split identical in location and intercellular route to that observed in the staphylococcal scalded skin syndrome.

Cell Adhesion↗
PubMed1979

Selective extraction of desmosomal proteins by low ionic strength media.

Desmosomes, isolated using an acidic buffer, have been subjected to extraction at low ionic strength. This treatment removes more than 35% of their protein in the form of two polypeptide chains of molecular weight 210 000 and 230 000, but the desmosomes show only subtle changes in ultrastructure. It is concluded that the use of low ionic strength media for desmosome isolation yields residual structures specifically depleted in high molecular weight proteins.

Animals↗
PubMed1974

Isolation of epidermal desmosomes.

A method is reported for the isolation of desmosomes in a high yield and of a purity suitable for biochemical analysis. The procedure utilizes the selective solubilizing action of citric acid-sodium citrate (CASC) buffer, pH 2.6, on the non-cornified layers of cow nose epidermis, followed by discontinuous sucrose density gradient centrifugation. Electron microscopy with both thin sections of pellets and unfixed spread preparations reveals that after centrifugation, desmosomes are located mainly at the 55-60% sucrose interface. In the desmosome preparation thus obtained, the characteristic desmosome structure is well preserved, showing the midline, unit membranes, and dense plaques. Furthermore, removal of the epidermal filament bundles by the solubilizing action of CASC buffer has revealed a finely filamentous layer on the cytoplasmic surface of the plaques. The dimensions, location, and appearance of this layer correspond with those of the "connecting component" which has been previously suggested as being responsible for the attachment of epidermal filament bundles to the desmosome.

Animals↗
PubMed1974

Chemical characterization of isolated epidermal desmosomes.

Desmosomes, isolated from cow nose epidermis by a method utilizing citrate buffer pH 2.6 and density gradient centrifugation, have been analyzed and found to contain approximately 76% protein, 17% carbohydrate, and 10% lipid. Nonpolar amino acids predominate in desmosomal protein, representing 456 residues per 1,000. The sialic acid content is 5 nM/mg of protein. The lipid fraction is composed of approximately 40% cholesterol and 60% phospholipids. Desmosomes are completely solubilized by incubation with 2% sodium dodecyl sulphate and 1% beta-mercaptoethanol. Gel electrophoresis of the denatured desmosomal proteins reveals 24 bands, with mobilities corresponding to a molecular weight range of 15,000-230,000 daltons. Seven of these are considered to be major bands, together constituting 81% of the desmosomal protein. Bands 1 and 2, of molecular weights 230,000 and 210,000 daltons, together comprise 28% by weight of the desmosome. It is suggested that these protein chains are located in the desmosomal plaque. Bands 3 and 4 are PAS-positive, constitute 23% of the desmosomal protein, and have apparent molecular weights of 140,000 and 120,000 daltons, respectively. At least part of this material must originate from the carbohydrate-containing layer which is demonstrated, by histochemistry, to be present in the desmosomal interspace. The possible nature and origin of the remaining major bands, of molecular weights 90,000, 75,000, and 60,000 daltons, are discussed.

Amino Acids↗
PubMedDate not supplied

Intercellular adhesion and its role in epidermal differentiation.

The differentiation of epidermal keratinocytes is accompanied by a regular sequence of changes in the nature of their adhesive interactions. The basis of these changes is discussed with reference to the more detailed studies of intercellular adhesion of other tissue types. In the early stages, desmosome formation predominates. A sequence of molecular events which may underlie desmosome formation and junctional stability is constructed. At the later stages of differentiation, adhesive interactions between non-junctional membranes are of increasing importance, and cells undergo pronounced flattening. The involvement of the cytoskeleton in these processes is considered. Possibilities for further studies on keratinocyte adhesion in normal and pathological epidermis are suggested.

Cell Adhesion↗