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Biomedical subjects

R A Eady

Publications and source records attributed to R A Eady.

At least 91 records · Page 5Linked to original sources
PubMed1995

Altered laminin 5 expression due to mutations in the gene encoding the beta 3 chain (LAMB3) in generalized atrophic benign epidermolysis bullosa.

The anchoring filament component laminin 5 (kalinin/nicein) is a candidate protein for mutations in some hereditary blistering skin disorders. In this study, laminin 5 expression was assessed in a family with generalized atrophic benign epidermolysis bullosa, a non-lethal variant of the junctional form of epidermolysis bullosa. Immunofluorescence microscopy of the skin basement-membrane zone with a monoclonal antibody (GB3) revealed reduced anti-laminin 5 staining compared to normal controls. The labeling, when examined by immunoelectron microscopy, was present within the lower lamina lucida, immediately below the plane of blister formation. Numerous hemidesmosomes and well-formed anchoring filaments were seen on transmission electron microscopy. Polymerase chain reaction amplification of genomic DNA encoding the beta 3 subunit (LAMB3) of laminin 5, heteroduplex analysis of the polymerase chain reaction products, and nucleotide sequencing of the heteroduplexes revealed two putative mutations within the LAMB3 gene; these consisted of a premature termination codon in exon 3 and a missense mutation in exon 7. Exons 3 and 7 encode part of domain VI of the laminin 5 beta 3 chain short arm. This globular domain of the protein has been postulated to have an important function in the interaction of laminin 5 with other structural components of the basement membrane zone, such as laminin 6 (K-laminin). Thus the mutations delineated in this family may have a critical pathogenetic significance in reducing adhesion between the epidermis and the dermis.

Base Sequence↗
PubMed1995

Ultrastructural changes resulting from keratin-9 gene mutations in two families with epidermolytic palmoplantar keratoderma.

Palmoplantar keratoderma of Voerner type (or epidermolytic palmoplantar keratoderma) is an autosomal dominant inherited disorder of keratinization with histologic features of epidermolytic hyperkeratosis. We studied members of two large unrelated kindreds with epidermolytic palmoplantar keratoderma, and biopsy specimens of lesional palmar skin from both families confirmed the histologic changes of epidermolytic hyperkeratosis. Whorls of abnormally aggregated keratin filaments were seen ultrastructurally to be associated with signs of cellular disintegration in spinous and granular cells. Direct sequencing of genomic DNA samples obtained from several members of each family established the substitution of a highly conserved arginine by tryptophan (R162W) in the 1A region of the alpha-helical rod domain of keratin 9. This arginine residue in a highly conserved region of keratins 1 and 10 is affected by disruptive missense point mutations in many patients with bullous ichthyosiform erythroderma. An equivalent position in the sole and palm restricted keratin 9 appears to be the mutation hot spot in epidermolytic palmoplantar keratoderma. To date, R162W is the most prevalent genetic defect reported in this genodermatosis.

Base Composition↗
PubMed1995

The first report of familial adult T-cell leukaemia lymphoma in the United Kingdom.

We describe two siblings who developed adult T-cell leukaemia lymphoma (ATLL) within 4 years. Both were black of Afro-Caribbean extraction, but one had been born in the United Kingdom and had visited the Caribbean only once. Both patients were HTLV-1 seropositive, as was their mother; their father and brother were negative. The older sibling had the lymphoma form of ATLL, whilst the younger had chronic ATLL. The former was unresponsive to chemotherapy and died of progressive disease; the latter experienced transient responses to various treatments and is alive 5 years after presentation. Immunophenotyping showed a CD4+, CD25+ phenotype; Southern blot demonstrated a monoclonal integration of HTLV-I in the tissues involved. This report, of the first familial ATLL in the U.K., supports the suggestion of transmission of HTLV-I from mother to child and documents the development of ATLL in second-generation Caribbean immigrants.

Adult↗
PubMed1995

The use of Michel's transport medium for immunofluorescence and immunoelectron microscopy in autoimmune bullous diseases.

We report the use of Michel's solution, already a well established transport medium, in the combined use of direct immunofluorescence (IMF) and pre-embedding immunoelectron microscopy in 3 subepidermal bullous diseases--bullous pemphigoid (BP), epidermolysis bullosa acquisita (EBA) and dermal binding linear IgA disease (LABD). Our studies demonstrated that electron microscopy of normal skin maintained in Michel's medium for up to 28 days showed remarkable preservation of all components of the basement membrane zone, including the ultrastructure of the basal keratinocytes, dermoepidermal junction and papillary dermis. However, epidermal cell cytolysis occurred after just 48 hours. Immunoelectron microscopy using a gold probe has enabled us to localise the immunoreactants in bullous pemphigoid, epidermolysis bullosa acquisita and dermal-binding linear IgA bullous dermatoses. Our findings are comparable to and as equally reliable as those on immunoelectron microscopy of fresh skin biopsies with no loss of antigen deposition, and demonstrate an effective new use of a well established transport medium.

Epidermolysis Bullosa Acquisita↗
PubMed1995

Use of type VII collagen gene (COL7A1) markers in prenatal diagnosis of recessive dystrophic epidermolysis bullosa.

Generalised recessive dystrophic epidermolysis bullosa (EB) is a severe inherited disease in which patients suffer from blistering and scarring of the skin and mucous membranes after minor mechanical trauma. Tight genetic linkage has been established to the type VII collagen gene (COL7A1) at 3p21, with no evidence of locus heterogeneity. Several COL7A1 mutations have now been identified in recessive dystrophic EB patients. Prenatal diagnosis has been performed by examination of a fetal skin biopsy taken at about 16 weeks' gestation, and relies on identification of characteristic ultrastructural and immunohistochemical changes. We have now achieved a first trimester prenatal diagnosis using intragenic and flanking COL7A1 markers in a pregnancy at risk for recessive dystrophic EB. Segregation of the informative markers predicted the baby would be an unaffected carrier. The pregnancy continued to term and a healthy baby was born, confirming this result.

Collagen↗
PubMed1994

A functional "knockout" of human keratin 14.

The importance of keratins and other intermediate filaments in the maintenance of tissue structure is emphasized by the discovery that many hereditary skin-blistering diseases are caused by mutations in keratin genes. Here, we describe a situation in which keratin 14 (K14) is missing altogether in the epidermis: A homozygous 2-nucleotide deletion in exon I of the K14 gene causes premature termination of the mRNA transcripts upstream from the start of the rod domain and results in a K14 null phenotype. In this individual no keratin intermediate filaments are visible in basal epidermal cells, although filaments are present in the upper layers of the epidermis. No compensating keratin expression is detected in vivo, and K14 mRNA is down-regulated. The individual, diagnosed as Köbner (generalized) EBS, suffers from severe widespread keratinocyte fragility and blistering at many body sites, but although the phenotype is severe, it is not lethal. This K14-/- phenotype confirms that only one K14 gene is expressed in human epidermis and provides an important model system for examining the interdependence of different keratin filament systems and their associated structures in the skin.

Amino Acid Sequence↗
PubMed1994

Epidermolysis bullosa: hereditary skin fragility diseases as paradigms in cell biology.

Recent research into the molecular basis of epidermolysis bullosa has provided a unique insight into a variety of mechanisms in normal cell biology, such as cell-matrix interactions, and has uncovered an excellent model for studies on keratin intermediate filaments. The simplex forms of epidermolysis bullosa are caused by mutations in the genes for the basal epidermal keratins, K5 and K14. Most mutations affect highly conserved parts of the molecules, illustrating their importance in normal keratin filament assembly and integrity. Mutations in corresponding regions of the differentiation-associated keratins, K1 and K10 can also occur in epidermolytic ichthyosis. Both recessive and dominant forms of dystrophic epidermolysis bullosa result from mutations in an anchoring fibril collagen gene, COL7A1. Junctional epidermolysis bullosa is caused by mutations in the genes encoding different chains of the novel laminin isoform, nicein/kalinin, also known as laminin 5, which is associated with the anchoring filament-hemidesmosome complex of the basement membrane zone. These recent findings strengthen the evidence for the role of nicein/kalinin and type VII collagen in adherence and stabilization of the dermo-epidermal junction.

Animals↗
PubMed1994

Mutations in the rod 1A domain of keratins 1 and 10 in bullous congenital ichthyosiform erythroderma (BCIE).

Bullous congenital ichthyosiform erythroderma is a human hereditary skin disorder in which suprabasal keratinocytes rupture. Recent reports have implicated keratins K1 and K10 in this disease. Here we describe four diverse keratin mutations that are all significantly associated with this disease. Two of these are in the helix 1A subdomain of the type II keratin 1, giving a serine-to-proline substitution in codon 185 and an asparagine-to-serine substitution in codon 187. In the analogous region of type I keratin 10, an arginine-to-proline and an arginine-to-serine transition in codon 156 have been identified. All four mutations create restriction fragment length polymorphisms that were used exclude the mutations from 120 normal chromosomes. Insertional polymorphism (in the V2 subdomains of the non-helical tails of K1 and K10) was excluded as the cause of the phenotypic heterogeneity observed within one family.

Amino Acid Sequence↗
PubMed1994

Ichthyosis bullosa of Siemens--a disease involving keratin 2e.

Ichthyosis bullosa of Siemens (IBS) is a congenital bullous ichthyosis without erythroderma. In contrast to bullous congenital ichthyosiform erythroderma (BCIE), there is a relatively mild involvement of the skin and epidermolytic hyperkeratosis (EHK) is restricted to the upper suprabasal layers of the epidermis. Tonofilament aggregation was observed by EM in suprabasal cells from affected patients in the two families under study, indicative of a keratin abnormality. Keratin 2e is a differentiation specific type II keratin expressed suprabasally in the epidermis. Part of the K2e gene was amplified by polymerase chain reaction using genomic DNA from affected and unaffected individuals from two IBS families. Direct sequencing of polymerase chain reaction products revealed a point mutation in the highly conserved helix termination motif, producing the protein sequence change LLEGEE-LLEGKE. This mutation was found in all affected members of a five-generation kindred and also in a sporadic case in a second unrelated family. No mutation was seen in unaffected individuals. The mutation destroys a MnlI restriction site, which allowed exclusion of the mutation from a population of 50 unaffected unrelated individuals by restriction fragment analysis of K2e PCR products. This is the sixth keratin gene found to be involved in an inherited epidermal disorder.

Base Sequence↗
PubMed1994

Ultrastructural clues to genetic disorders of skin: the dermal-epidermal junction.

The candidate gene approach in tracking the underlying cause of a number of genetic skin disorders has proved remarkably effective over the past few years. Electron microscopy has had a unique role in identifying morphologic abnormalities of various fibers, fibrils, and filaments, and helping to localize biochemical constituents to these structures. Nowhere is this approach more strongly demonstrated than in its application to different forms of epidermolysis bullosa, of which two major forms, junctional and dystrophic epidermolysis bullosa, are caused by mutations of genes encoding structural proteins in the dermal-epidermal junction.

Cell Adhesion Molecules↗
PubMed1994

Fibrillin immunoreactivity is associated with normal or fragmented elastic microfibrils at the dermal-epidermal junction in recessive dystrophic epidermolysis bullosa.

Elastic microfibrils containing fibrillin are a part of the fibroreticular network of normal epidermal basement membrane. In dystrophic epidermolysis bullosa (DEB) at least one other fibroreticular component, anchoring fibrils, which contain type VII collagen, is known to be abnormal. We therefore questioned whether elastic microfibrils and fibrillin expression might also be abnormal in DEB. By indirect immunofluorescence, and pre-embedding immunogold electron microscopy using a monoclonal antifibrillin antibody, we found no difference from control samples in either the quantity of the labelling or in the ultrastructural appearances of the immunolabelled fibrils in intact DEB skin. In areas of dermal-epidermal separation, however, we observed a number of thin, fragmented sublamina densa wisp-like structures, which still labelled for fibrillin despite lacking the typical ultrastructural features of normal elastic microfibril bundles. As a consequence of blistering in DEB, elastic microfibril bundles are disrupted, and fragmented microfibrils may still remain attached to the blister roofs. Many of these elastic microfibrils cannot be distinguished from rudimentary or altered anchoring fibrils on morphology alone, and might therefore account for misinterpretation of ultrastructural disorders of the dermal-epidermal junction. We postulate that, in intact skin, elastic microfibrils might contribute to dermal-epidermal adherence, in the absence of normal-functioning anchoring fibrils.

Adolescent↗
PubMed1994

Filaggrin expression in epidermolytic ichthyosis (epidermolytic hyperkeratosis).

To evaluate the role of filaggrin in keratin filament aggregation in epidermolytic ichthyosis (epidermolytic hyperkeratosis, EH), we studied EH skin by light and electron microscopic immunohistochemistry, and biochemical analysis using sodium dodecylsulphate-polyacrylamide gel electrophoresis and immunoblotting. Immunohistochemical staining showed an increased number of filaggrin-immunoreactive cell layers, but the reaction was still confined to the mid- and upper epidermal layers, whereas an abnormal granular pattern of staining for K10 began in the lower suprabasal cell layers. This suggests that the aggregation of keratin filaments precedes, and occurs independently of, profilaggrin synthesis during epidermal differentiation. Although keratohyalin granules were frequently associated with clumped filaments, immunoelectron microscopy showed that K10 labelling was confined to keratin filaments (including clumped filaments), and that antifilaggrin antibodies stained only keratohyalin granules, at least in the living cells. Certain keratin aggregates in the cornified cells were still devoid of filaggrin staining. However, in some cells which appeared partially cornified, filaggrin immunoreactivity occurred over the aggregated keratin filaments. Immunoblotting showed a clear increase of filaggrin/profilaggrin expression, without evidence for a qualitative abnormality. It seems unlikely, therefore, that filaggrin is primarily involved in the keratin filament clumping in EH, but that in some EH cases it interacts with keratins in a defective manner, possibly due to premature cell death and profilaggrin processing and/or altered keratin filament structure involving the interaction points of keratin with filaggrin.

Adolescent↗
PubMed1994

Epidermolysis bullosa pruriginosa: dystrophic epidermolysis bullosa with distinctive clinicopathological features.

We report a study of eight unrelated adult patients with a highly distinctive phenotype of dystrophic epidermolysis bullosa. It is characterized clinically by pruritus, lichenified or nodular prurigo-like lesions, violaceous linear scarring, occasional trauma-induced blistering, excoriations, milia, nail dystrophy and, in some cases, albopapuloid lesions on the trunk. The scarring is most evident on the limbs, particularly on the shins, with relative sparing elsewhere. Intact blisters are rarely seen. Physical signs were present at birth in three patients, but in the others skin manifestations were first noticed between 6 months and 10 years of age. Five cases are sporadic, but three of the eight patients have a history of familial involvement, with autosomal dominant inheritance in two cases and recessive transmission in the other case. Studies of the dermal-epidermal junction showed alterations in the number and ultrastructure of anchoring fibrils in lesional, perilesional and non-lesional skin, consistent with a diagnosis of dominant or localized recessive dystrophic epidermolysis bullosa. These patients represent an unusual, poorly recognized form or expression of dystrophic epidermolysis bullosa which has features in common with a variety of acquired inflammatory dermatoses.

Adolescent↗
PubMed1994

Genetic linkage to the type VII collagen gene (COL7A1) in 26 families with generalised recessive dystrophic epidermolysis bullosa and anchoring fibril abnormalities.

To strengthen the evidence for genetic linkage to COL7A1, we have studied 26 generalised recessive dystrophic epidermolysis bullosa (EB) families of British, Italian, Irish, and South African origin. We chose two linkage markers, a COL7A1 PvuII intragenic polymorphism and a highly informative anonymous microsatellite marker, D3S1100, which maps close to the COL7A1 locus at 3p21.1-3. Diagnosis was established by family history, clinical examination, immunofluorescence, and ultrastructural studies. The PvuII marker was informative in 16 families with a maximum lod score (Zmax) of 3.51 at recombination fraction (theta) = 0. The D3S1100 microsatellite was informative in 24 out of 25 families with Zmax = 6.8 at theta = 0.05 (Z = 4.94 at theta = 0) and no obligatory recombination events. These data strongly suggest that COL7A1 mutations cause EB in these families and, combined with previous studies, indicate locus homogeneity. The importance of anchoring fibrils for dermal-epidermal adhesion is further underlined. D3S1100 may later prove useful in prenatal diagnosis of this disease, if used in combination with other markers.

Base Sequence↗
PubMed1994

The hemidesmosome: a target in auto-immune bullous disease.

Hemidesmosomes are subcellular structures that are involved in the attachment of a variety of epithelial cells, including basal epidermal keratinocytes, to the extracellular matrix. Like desmosomes, they provide a link between the intracytoplasmic keratin intermediate filaments and the plasma membrane. Major hemidesmosome plaque components include the bullous pemphigoid antigens of 230 and 180 kD and the alpha 6 beta 4-integrin. These transmembrane proteins may associate extracellularly with anchoring filament components including the 19-DEJ-1 proteoglycan and the polymeric proteins nicein/kalinin and epiligrin. Several of these hemidesmosome-related components have been implicated as targets for circulating auto-antibodies in immuno bullous disorders.

Antigen-Antibody Reactions↗
PubMed1994

Immunoelectron microscopy of skin basement membrane zone antigens: a pre-embedding method using 1-nm immunogold with silver enhancement.

There is no single immunoelectron microscopical method for invariably effective localization of both intracellular and extracellular antigens. We describe a simple and practicable immunogold technique that can be used to localize various skin basement membrane zone antigens at the ultrastructural level. Small pieces of skin were incubated with primary antibodies recognizing epitopes on a range of basement membrane zone-related antigens (two different lamina lucida-associated antigens, laminin, type VII collagen, fibrillin and keratin 14). This was followed by incubation with 1-nm colloidal gold-conjugated secondary antibody and subsequent silver intensification. The specimens were then processed for transmission electron microscopy. Precise immunolocalization with good ultrastructural preservation was achieved for all basement membrane zone antibodies tested. The results of basal cell keratin immunostaining showed that this microscopic approach could also be applied to some extent in the characterization of intracellular antigens. This immunoelectron microscopy technique provides a useful approach to the study of macromolecules at the basement membrane zone.

Antigens↗