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Biomedical subjects

D Atherton

Publications and source records attributed to D Atherton.

At least 19 recordsLinked to original sources
PubMed2006

Bone mineralization in children with epidermolysis bullosa.

BACKGROUND: Various factors may have deleterious effects on bone health in patients with epidermolysis bullosa (EB). OBJECTIVES: In a retrospective notes review, to assess bone mineralization in children with EB and to identify the relative contributions of nutrition, activity and disease severity to low bone mass. METHODS: Thirty-nine children with EB [32 recessive dystrophic EB (RDEB), four Dowling-Meara EB simplex (DMEBS) and three junctional EB (JEB)] had lumbar spine bone mass measured using dual X-ray absorptiometry (GE Lunar Prodigy; GE Healthcare, Chalfont St Giles, U.K.). Seventy-six healthy children were also studied. Weight and height were recorded and mobility was rated. RESULTS: Children with RDEB and JEB, but not those with DMEBS, had lower bone mineral density SD scores than controls; differences remained after adjusting for the smaller body size of the patients. Bone mass was best predicted by mobility rating. CONCLUSIONS: Children with RDEB and JEB have low bone mass after adjusting for their smaller size, which may put them at risk for fragility fractures. Low bone mass was best predicted by the level of mobility, raising the hypothesis that improving activity or bone loading may be a potential preventive intervention in these children. However, as low bone mass may be multifactorial in these children, more detailed investigation of potential aetiological factors is required before interventions are planned.

Absorptiometry, Photon↗
PubMed2002

A retrospective evaluation of azathioprine in severe childhood atopic eczema, using thiopurine methyltransferase levels to exclude patients at high risk of myelosuppression.

BACKGROUND: Atopic eczema is a chronic inflammatory skin disease, which in most children can be adequately controlled using topical therapy. However, in a small number of children it is necessary to use systemic treatments to gain an acceptable level of disease control. OBJECTIVES: To evaluate azathioprine as a treatment for severe atopic eczema in children, and the value of pretreatment thiopurine methyltransferase (TPMT) levels in the identification of patients at high risk of myelosuppression. METHODS: Between January 1997 and May 2000, 91 children had erythrocyte TPMT assays with the intention of treating their atopic eczema with azathioprine. This study is based on retrospective examination of data taken from the hospital notes of these children, who had attended Great Ormond Street Hospital for Children and St John's Institute of Dermatology, London. RESULTS: The distribution of TPMT values corresponded closely to that previously described in adults. Forty-eight children were commenced on treatment with azathioprine. Twenty-eight had an excellent response to treatment, 13 had a good response and seven had a poor response. No patient developed neutropenia. CONCLUSIONS: Azathioprine may prove a very valuable treatment for severe atopic eczema in children. We consider its short-term adverse effect profile in children with normal TPMT activity to have been entirely acceptable with our treatment protocol. As result, we now feel confident to initiate therapy at dose levels of 2.5-3.5 mg kg(-1) in those with a normal TPMT level, and to reduce the frequency with which we undertake tests of bone marrow and liver function.

Azathioprine↗
PubMed2002

Juvenile-onset localized scleroderma activity detection by infrared thermography.

OBJECTIVE: The aim of this study was to define the clinical utility of infrared thermography in disease activity detection in localized scleroderma (LS). METHODS: We retrospectively reviewed 130 thermal images of 40 children with LS and calculated the sensitivity and specificity of thermography, comparing clinical descriptions of the lesions and contemporary thermographs. The reproducibility of thermography was calculated by using the weighted kappa coefficient to determine the level of agreement between two clinicians who reviewed the thermographs independently. RESULTS: The sensitivity of thermography was 92% and specificity was 68%. Full concordance between the two clinicians was observed in 91% of lesions, with a kappa score of 0.82, implying very high reproducibility of this technique. CONCLUSION: Our results demonstrate that thermography is a promising diagnostic tool when associated with clinical examination in discriminating disease activity, as long as it is applied to lesions without severe atrophy of the skin and subcutaneous fat. Further evaluation is needed to determine whether thermography can predict the future progression of lesions.

Age of Onset↗
PubMed2000

Oculo-ectodermal syndrome: report of two further cases.

We describe the clinical findings in two previously unreported, unrelated cases with aplasia cutis congenita and epibulbar dermoids, similar to the cases reported by Toriello et al. [1993]. In addition, one patient had bladder exstrophy with epispadias. These cases provide further evidence for the identification of the oculo-ectodermal syndrome as a distinct entity.

Bladder Exstrophy↗
PubMed2000

Radial aplasia, poikiloderma and auto-immune enterocolitis--new syndrome or severe form of Rothmund-Thomson syndrome?

A syndrome is described in three isolated patients in whom the main features are bilateral radial aplasia, short stature, an inflammatory based 'elastic' pyloric stenosis, a pan-enteric inflammatory gut disorder that appears to be due to an autoimmune process, and poikiloderma. Other features in individual cases include cleft palate, micrognathia, anal atresia, patellar aplasia/hypoplasia and sensorineural deafness. This combination may represent a severe form of Rothmund-Thomson syndrome or possibly a previously unrecognized condition.

Abnormalities, Multiple↗
PubMed2000

Dilated cardiomyopathy in dystrophic epidermolysis bullosa.

BACKGROUND: Dystrophic epidermolysis bullosa (DEB) is an uncommon genetic disorder of the skin and mucosae. In 1996, we reported the occurrence of lethal dilated cardiomyopathy (DCM) in two affected children. METHODS: In the past seven years we have routinely screened patients with severe DEB who have been under the care of this hospital by yearly clinical review, echocardiography, and quantification of plasma selenium and carnitine concentrations, as deficiency of these micronutrients is known to be associated with the development of DCM. RESULTS: Six of 61 children have developed DCM over the seven year period of this study, four of whom have not been previously reported, and three of whom have since died. We compared the concentrations of selenium and free and total carnitine in the children who developed DCM to concentrations in those with severe DEB who did not. The concentrations of free and total carnitine when first measured were significantly lower in the children with DCM, but the selenium concentrations were not. CONCLUSIONS: We now believe that DCM is a not infrequent complication of severe recessive DEB, and may be related in part to carnitine concentrations, though the exact mechanism remains unclear. We therefore recommend that patients with this condition should undergo regular cardiac review including echocardiography.

Biomarkers↗
PubMed1999

The eye in epidermolysis bullosa.

AIMS: To describe the ophthalmic findings in a large cohort of epidermolysis bullosa (EB) patients managed in one large specialist centre. METHODS: A case note review of consecutive patients seen at Great Ormond Street Children's Hospital. Data on the dermatological disease, ophthalmic history, and examination were collected and coded onto a data sheet. RESULTS: 181 patients: 50 (28%) simplex EB; 15 (8%) junctional EB; 28 (15%) autosomal dominant dystrophic EB; 72 (40%) autosomal recessive dystrophic EB; nine patients (5%) with dystrophic EB whose inheritance could not be ascertained; and seven cases (4%) of EB that could not be classified. Ocular problems were found in 12% (n = 6) of simplex patients and 40% (n = 6) of those with junctional disease. One patient (of 28) in the autosomal dominant dystrophic group had ocular involvement and 51% (37/72) of patients in the autosomal recessive dystrophic group had ophthalmic complications: corneal (25/72), lid ectropions (3/72), lid blisters (5/72), and symblepharon (3/72). CONCLUSION: Ophthalmic complications are common in EB overall but the incidence varies widely with subtype. Ophthalmic complications are the most severe in the dystrophic recessive and junctional subtypes where there is a need for extra vigilance. The major treatment modality was use of ocular lubricants.

Adolescent↗
PubMed1996

Childhood-onset scleroderma: is it different from adult-onset disease.

OBJECTIVE: To distinguish childhood-onset scleroderma from adult-onset disease. METHODS: The clinical and serologic features of 58 patients with childhood-onset scleroderma (11 patients with diffuse cutaneous systemic sclerosis [SSc], 16 with linear SSc, 14 with linear morphea, and 17 with morphea) were examined in the largest cohort of such patients studied to date. These parameters were compared with data obtained from patients with adult-onset disease. RESULTS: Childhood-onset scleroderma resembled adult-onset disease with regard to the heterogeneity of clinical expression and subsets of disease, but it also differed from adult-onset disease in a number of clinical and laboratory parameters. The predominant childhood-onset disease presentation was the localized form of the disease, with limited and diffuse SSc being less notable. There was a significant association of trauma with childhood-onset scleroderma (P < 0.0001), which was not noted in adult-onset disease. Furthermore, in contrast to adult disease, patients with childhood-onset disease had normal levels of parameters of vascular activation (von Willebrand factor, angiotensin-converting enzyme, E-selectin, and endothelin-1), T cell activation (soluble interleukin-2 receptors), and collagen synthesis (carboxy-terminal type I and amino-terminal type III), a notable lack of anticentromere antibodies, and abnormal coagulation indices. CONCLUSION: A number of features distinguish childhood-onset scleroderma from adult-onset disease.

Adolescent↗
PubMed1996

Fatal cardiomyopathy in dystrophic epidermolysis bullosa.

Two unrelated children with autosomal recessive dystrophic epidermolysis bullosa (RDEB) developed fatal dilated cardiomyopathy. Both were malnourished and had severe growth problems. We believe that the most likely cause for the cardiomyopathy is a micronutrient deficiency, most probably selenium deficiency, since the serum selenium level was found to be reduced in the case in whom we measured this, and in 14 of 25 other children with dystrophic epidermolysis bullosa. Echocardiographic screening of 18 other patients revealed no evidence of cardiomyopathy. We recommend careful attention to nutrition, with prospective monitoring of vitamins and micronutrients including selenium and carnitine, and regular echocardiographic screening of patients with severe RDEB.

Adolescent↗
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

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↗
PubMed1993

Identification of cysteine residues at the 10-pmol level by carboxamidomethylation of protein bound to sequencer membrane supports.

A procedure is described for the in situ carboxamidomethylation of cystine/cysteine residues in protein samples of as little as 10 pmol, prior to automated protein sequence analysis. Previous in situ methods for the modification of cysteines are limited to proteins available in quantities greater than 100 pmol due to contaminants which interfere with HPLC identification of phenylthiohydantoin amino acids, and cannot be performed on polyvinylidenedifluoride (PVDF)-bound samples. In our procedure, protein samples, immobilized on either PVDF- or polybrene-treated glass filters, are reduced with tributylphosphine followed by alkylation with iodoacetamide prior to automated sequence analysis. Carboxamidomethylcysteine is formed in high yield with no discernable side reactions in standard proteins (insulin, human transferrin, lysozyme) or experimental samples. Both initial and repetitive yields of carboxamidomethylated proteins were either comparable to or better than nonalkylated proteins. No apparent increase in background nor any sequence preview due to partial amino-terminal alkylation was observed. The carboxamidomethylation procedure described here successfully overcomes the limitations of available methods for reduction and alkylation of less than 100 pmol of protein directly on sequencer membrane supports.

Alkylation↗
PubMed1992

Exclusion mapping of the X-linked dominant chondrodysplasia punctata/ichthyosis/cataract/short stature (Happle) syndrome: possible involvement of an unstable pre-mutation.

Homology with the mouse bare patches mutant suggests that the gene for the X-linked dominant chondrodysplasia punctata/ichthyosis/cataract/short stature syndrome (Happle syndrome) is located in the human Xq28 region. To test this hypothesis, we performed a linkage study in three families comprising a total of 12 informative meioses. Multiple recombinations appear to exclude the Xq28 region as the site of the gene. Surprisingly, multiple crossovers were also found with 26 other markers spread along the rest of the X chromosome. Two-point linkage analysis and analysis of recombination chromosomes seem to exclude the gene from the entire X chromosome. Three different mechanisms are discussed that could explain the apparent exclusion of an X-linked gene from the X chromosome by linkage analysis: (a) different mutations on the X chromosome disturbing X inactivation, (b) metabolic interference, i.e. allele incompatibility of an X-linked gene, and (c) an unstable pre-mutation that can become silent in males. We favour the last explanation, as it would account for the unexpected sex ratio (M:F) of 1.2:1 among surviving siblings, and for the striking clinical variability of the phenotype, including stepwise increases in disease expression in successive generations.

Body Height↗
PubMed1992

Internal protein sequence analysis: enzymatic digestion for less than 10 micrograms of protein bound to polyvinylidene difluoride or nitrocellulose membranes.

A procedure for the generation and isolation of internal peptide fragments for less than 10 micrograms of protein bound to either polyvinylidene difluoride (PVDF) or nitrocellulose membranes after electrophoretic transfer from sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE) is presented. This technique has produced internal sequence data for 120 peptides, with an average initial yield of 20 pmol. Membrane-bound proteins were enzymatically digested with either trypsin or endoproteinase Lys-C in the presence of 1% hydrogenated Triton X-100/10% acetonitrile/100 mM Tris-HCl, pH 8.0, for 24 h at 37 degrees C. The eluted peptides were then directly isolated by microbore HPLC for subsequent sequence analysis. One percent hydrogenated Triton X-100 did not inhibit enzymatic activity, distort HPLC resolution of peptides, or contain uv-absorbing contaminants that could interfere with peptide identification. Reproducible peptide maps and consistent recoveries are presented for standard proteins (3.5-8.0 micrograms) bound to either membrane, with higher recoveries for PVDF-bound proteins. Ninety percent of the proteins analyzed by this technique have produced results; representative peptide maps and sequence data are presented. This technique has a wide range of applications, particularly for proteins with blocked amino termini or those that can only be purified by SDS-PAGE or 2D isoelectric focusing SDS-PAGE.

Collodion↗
PubMed1988

The size, operation, and technical capabilities of protein and nucleic acid core facilities.

A survey of 40 protein and nucleic acid chemistry facilities has provided data about the capabilities of core facilities and the cost of the services they provide. Approximately 43% of the +158,000 average annual operating budget for a typical university facility is derived from service charges. After correcting for the various degrees of subsidization of the different facilities, it was found that it costs a typical university facility +65 to carry out an acid hydrolysis and amino acid analysis on a protein. A 25-residue peptide can be synthesized and cleaved for +2078, whereas sequencing the same peptide costs +874. A 25-residue oligonucleotide can be synthesized for +258. The total work output per month of an average facility corresponds to 65 amino acid analyses, 15 amino acid sequencing runs, three peptide syntheses, and 16 oligonucleotide syntheses. Depending on the approach used, from 85 to nearly 200 pmol of protein are required to obtain an accurate amino acid composition. To sequence the first 15 amino acids in a protein typically requires 150 pmol compared with 1.2 nmol of protein required to first carry out a tryptic digest and then isolate and sequence the first 15 residues in one of the resulting tryptic peptides.

Amino Acid Sequence↗