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Biomedical subjects

B Winchester

Publications and source records attributed to B Winchester.

At least 19 recordsLinked to original sources
PubMed2006

Autophagic vacuolar myopathy in twin girls.

Hereditary autophagic vacuolar myopathy (AVM) may occur in several diseases including the rimmed vacuolar myopathies, acid maltase deficiency, Danon disease, infantile autophagic vacuolar myopathy and X-linked myopathy with excessive autophagy (XMEA). In the latter three conditions the vacuoles are lined by membranes with sarcolemmal features. We present two unusual cases of autophagic vacuolar myopathy in twin girls born at term with no family history of neurological disease. After initial normal developmental milestones they developed progressive leg weakness and wasting with contractures from the age of 12 years. Investigations showed raised CK, normal female karyotype, normal acid maltase activity, normal nerve conduction and myopathic EMG features. Frozen sections of skeletal muscle were stained using routine tinctorial and histochemical methods. Immunohistochemical staining for spectrin, merosin, dystrophin, complement membrane attack complex and sarcoglycans was performed and ultrastructural examination undertaken. Direct sequence analysis of the lamp-2 gene using genomic DNA extracted from lymphocytes was performed. Histological analysis of the muscle biopsies demonstrated myofibres with vacuoles lacking glycogen and lipid many of which were delineated using immunohistochemistry for merosin, dystrophin and sarcoglycans. Ultrastructural examination showed duplication of the myofibre basal lamina with associated autophagic material. Vacuoles within myofibres were either membrane bound containing autophagic material or lined by plasma membrane and basal lamina. Intermyofibrillar glycogen was increased. Sequence analysis of the coding region and intron/exon boundaries of the lamp-2 gene was normal. This is the first report of female cases of AVM with sarcolemmal features. We suggest that these patients may represent manifesting carriers of XMEA, or alternatively, a new form of disease with a similar phenotype having autosomal recessive inheritance.

Adolescent↗
PubMed2005

Measurement of urinary CDH and CTH by tandem mass spectrometry in patients hemizygous and heterozygous for Fabry disease.

Fabry disease is an X-linked disorder of glycosphingolipid metabolism resulting from a deficiency of the lysosomal enzyme alpha-galactosidase A. This deficiency leads to the progressive accumulation, in lysosomes of visceral tissues and in body fluids of hemizygotes, of the glycosphingolipids globotriaosylceramide (CTH, Gb(3) or GL-3) and galabiosylceramide (CDH) and to a lesser extent the blood group AB and B related glycolipids. Elevated levels of the glycosphingolipids are found in the urine of hemizygous males with the classic phenotype, but it is not known whether all symptomatic or asymptomatic heterozygotes have elevated levels. We have therefore measured CTH and CDH quantitatively in a multiplex assay using tandem mass spectrometry in urine from a large cohort (44) of genetically proven or obligate heterozygotes including four with the N215S mutation, from classic hemizygotes (28), from cardiac variant hemizygotes with the N215S mutation (6) and from normal controls. The levels of CTH and CDH were related to both creatinine and sphingomyelin. Urinary CTH was elevated in all 28 classic hemizygotes but only in 4/6 of the cardiac variants. The level was within or just above the normal reference range in the four individuals heterozygous for the N215S mutation but was elevated in 38/40 of the other heterozygotes. Similar results were obtained for CDH, except that only 34/40 heterozygotes had an elevated level. The level of CDH was not elevated in the four heterozygotes and 4/6 of the hemizygotes for the N215S mutation. Combining the levels of CTH and CDH did not improve the discrimination of heterozygotes from controls. The ratio of CDH to CTH was higher in heterozygotes than in hemizygotes. Measurement of urinary CTH gave the best discrimination of heterozygotes from controls.

Chromatography, Liquid↗
PubMed2005

Is globotriaosylceramide a useful biomarker in Fabry disease?

AIM: The aim of this study was to determine whether globotriaosylceramide (Gb3) is a useful biomarker in Fabry disease. METHODS: The levels of Gb3 were measured in plasma and urine by tandem mass spectrometry in untreated hemizygotes and heterozygotes with Fabry disease and in healthy controls, and the levels were monitored in patients on treatment with enzyme replacement therapy (ERT). RESULTS: Hemizygotes with classic Fabry disease showed elevated levels of Gb3 in both plasma and urine and could readily be distinguished from normal controls. Male patients with the N215S mutation had normal levels in their plasma but 50% had marginally elevated levels in their urine. Thirty-three percent of proven heterozygotes had elevated Gb3 concentrations in plasma but 97% of those without the N215S mutation (36/37) had an elevated level in urine. The four heterozygotes with the N215S mutation had normal Gb3 levels in urine. The level of Gb3 in plasma initially fell following the start of ERT in all patients who had an elevated level before treatment. However, in a few patients the level subsequently rose. Similar results were found for the levels of Gb3 in urine. CONCLUSION: Gb3 is not an ideal marker of Fabry disease or the response to treatment in all patients. Plasma and urine levels of Gb3 cannot be used as a marker of Fabry disease in patients with the N215S mutation and many heterozygotes do not have elevated Gb3 levels in plasma. The urine concentration is more informative in heterozygotes and can be used as a measure of the response to therapy. The fall in Gb3 levels in patients receiving ERT was not sustained in some patients, despite a clinical improvement. Additionally, Gb3 cannot be used to monitor the response to treatment in patients who initially have normal plasma and urine concentrations of this glycolipid.

Biomarkers↗
PubMed2004

Sanfilippo B syndrome: molecular defects in Greek patients.

Sanfilippo syndrome type B [mucopolysaccharidosis IIIB (MPS IIIB] is the most prevalent type of MPS III in Greece, accounting for 81% of all MPS III cases diagnosed at the Institute of Child Health (Athens) over the last 20 years. The majority of the patients originated from East Central/Central Greece, Thessaly, and Macedonia. We present the results of mutation analysis in 21 Greek patients from 18 different families, all of whom had the severe form of the disorder. Patients were initially screened for five previously known mutations by restriction enzyme digestion of polymerase chain reaction products. Unknown mutations were identified by single-strand conformation polymorphism analysis and DNA sequencing and were confirmed by restriction enzyme analysis. Seven previously described mutations (Y140C, R626X, 503-512del, H414R, G292R, 334del25, and E452K) and four novel mutations (P516L, L242P, E446K, and R482Q) were identified. Expression of the latter and H414R showed that they were all null activity mutations. Considerable genetic heterogeneity has been described in MPS IIIB patients of different origins. In our population, Y140C, H414R, and R626X account for approximately 70% of the studied alleles. Our findings, especially in combination with the origin of individual patients, can improve carrier detection and genetic counseling in affected families.

Adolescent↗
PubMed2001

Congenital disorders of glycosylation type I leads to altered processing of N-linked glycans, as well as underglycosylation.

The N-linked glycans on transferrin and alpha(1)-antitrypsin from patients with congenital disorders of glycosylation type I have increased fucosylation and branching relative to normal controls. The elevated levels of monofucosylated biantennary glycans are probably due to increased alpha-(1-->6) fucosylation. The presence of bi- and trifucosylated triantennary and tetra-antennary glycans indicated that peripheral alpha-(1-->3), as well as core alpha-(1-->6), fucosylation is increased. Altered processing was observed on both the fully and underglycosylated glycoforms.

Amidohydrolases↗
PubMed2001

Respiratory virus surveillance. FluWatch project, 2000-2001. End of season update.

The 2000-2001 season was a relatively mild season worldwide. In Canada, lower than usual activity was reported for all national indicators of influenza activity, including the rate of influenza-like illness (ILI), the percentage of laboratory-confirmed cases of influenza and provincial/territorial influenza activity levels. However, there were a number of interesting characteristics of this year's influenza season. In contrast to the predominance of influenza A, and in particular the A/Sydney/5/97 (H3N2)-like virus over the past 3 years, influenza B predominated overall this season. Influenza A (H3N2) accounted for < 1% of all characterized isolates (H1N1 accounted for 49% of isolates). Increased laboratory-confirmed influenza activity began in the West (Yukon, prairie provinces and British Columbia) in mid-December, followed by the Atlantic provinces in mid- to late January and Ontario and Quebec in mid- February and March.

Adolescent↗
PubMed2001

Fabry disease: 20 novel GLA mutations in 35 families.

Thirty two mutations have been found in 35 unrelated patients of European origin with Fabry disease, including 8 females. Twenty of the mutations are novel and comprise of 13 missense: H46Y, W47G, R49P, C94S, F113S, G258R, P259R, Q279H, Q280H, R363H, A377D, P409A, P409T; 1 nonsense: L294X; 5 small deletions: 154delT, 520delT, 909-918del10, 1152-1153delCA, 1235-1236delCT and 1 splice site mutation: IVS5+2t-->c. The remaining 12 mutations have all been reported previously. All patients with deletions had the classic form of the disease but it was not possible to predict the phenotype from the missense mutations.

DNA Mutational Analysis↗
PubMed2001

Are there useful biochemical markers of disease activity in lysosomal storage diseases?

The primary biochemical consequence of a defect in a gene encoding a functional component of the lysosomal system is disruption of the catabolism or processing of macromolecules in the lumen of the lysosome. Transport of the resulting digestion products through the lysosomal membrane may also be affected. This leads to the accumulation of specific metabolites within the lysosomes of affected cells. The nature of these storage products depends upon the functional protein affected and the cell type. The accumulation of storage products is progressive and leads to hypertrophy of the lysosomal system, the hallmark of lysosomal storage diseases (LSDs). Subsequent cell necrosis or, possibly, exocytosis results in the appearance in body fluids of the storage products and components of the lysosomes at much higher concentrations than seen in normal unaffected individuals. Measurement of these increased levels of metabolites and proteins provides disease-specific and generic biochemical markers for LSDs. Secondary changes in metabolism and cellular function may also produce characteristic changes in the levels of metabolites or proteins, which can also be used as markers of the disease process. Although the rate of appearance of these biochemical markers in an individual will depend upon the underlying mutation in the gene and on other genetic and environmental factors, it provides a good indicator of the progression of the disease. As the novel forms of treatment being developed may reverse the hypertrophy of the lysosomal system, biochemical markers could also be used to monitor the reversal of pathology and the efficacy of treatment.

Animals↗
PubMed2001

Anderson-Fabry disease: clinical manifestations of disease in female heterozygotes.

Anderson-Fabry disease is a rare, X-chromosomal lipid storage disorder caused by a deficiency of lysosomal alpha-galactosidase A. Clinical manifestations of Anderson-Fabry disease include excruciating pain in the extremities (acroparaesthesia), skin vessel ectasia (angiokeratoma), corneal and lenticular opacity, cardiovascular disease, stroke and renal failure, only renal failure being a frequent cause of death. Heterozygote female carriers have often been reported as being asymptomatic or having an attenuated form of the disease. To evaluate the spectrum of clinical signs in heterozygotes, a comprehensive clinical examination was performed on 20 carriers of Anderson-Fabry disease. This revealed that, in addition to the skin manifestation, various other clinical manifestations of the disease are present, including acroparaesthesia, kidney dysfunction, cerebrovascular disease, and gastrointestinal and heart problems. It therefore appears that Anderson-Fabry disease affects both hemizygotes and heterozyotes and therefore should be considered to be an X-linked dominant disease.

Adolescent↗
PubMed2000

Genomic organization of the human phosphomannose isomerase (MPI) gene and mutation analysis in patients with congenital disorders of glycosylation type Ib (CDG-Ib).

CDG-Ib is the "gastro-intestinal" type of the congenital disorders of glycosylation (CDG) and a potentially treatable disorder. It has been described in patients presenting with congenital hepatic fibrosis and protein losing enteropathy. The symptoms result from hypoglycosylation of serum- and other glycoproteins. CDG-Ib is caused by a deficiency of mannose-6-phosphate isomerase (synonym: phosphomannose isomerase, EC 5.3.1.8), due to mutations in the MPI gene. We determined the genomic structure of the MPI gene in order to simplify mutation detection. The gene is composed of 8 exons and spans only 5 kb. Eight (7 novel) different mutations were found in seven patients with a confirmed phosphomannose isomerase deficiency, analyzed in the context of this study: six missense mutations, a splice mutation and one insertion. In the last, the mutation resulted in an unstable transcript, and was hardly detectable at the mRNA level. This emphasizes the importance of mutation analysis at the genomic DNA level.

Congenital Disorders of Glycosylation↗
PubMed2000

Mutations in PMM2 that cause congenital disorders of glycosylation, type Ia (CDG-Ia).

The PMM2 gene, which is defective in CDG-Ia, was cloned three years ago [Matthijs et al., 1997b]. Several publications list PMM2 mutations [Matthijs et al., 1997b, 1998; Kjaergaard et al., 1998, 1999; Bjursell et al., 1998, 2000; Imtiaz et al., 2000] and a few mutations have appeared in case reports or abstracts [Crosby et al., 1999; Kondo et al., 1999; Krasnewich et al., 1999; Mizugishi et al., 1999; Vuillaumier-Barrot et al., 1999, 2000b]. However, the number of molecularly characterized cases is steadily increasing and many new mutations may never make it to the literature. Therefore, we decided to collate data from six research and diagnostic laboratories that have committed themselves to a systematic search for PMM2 mutations. In total we list 58 different mutations found in 249 patients from 23 countries. We have also collected demographic data and registered the number of deceased patients. The documentation of the genotype-phenotype correlation is certainly valuable, but is out of the scope of this molecular update. The list of mutations will also be available online (URL: http://www.kuleuven. ac.be/med/cdg) and investigators are invited to submit new data to this PMM2 mutation database.

Adolescent↗
PubMed2000

Reduced heparan sulfate accumulation in enterocytes contributes to protein-losing enteropathy in a congenital disorder of glycosylation.

Intestinal biopsy in a boy with gastroenteritis-induced protein-losing enteropathy (PLE) showed loss of heparan sulfate (HS) and syndecan-1 core protein from the basolateral surface of the enterocytes, which improved after PLE subsided. Isoelectric focusing analysis of serum transferrin indicated a congenital disorder of glycosylation (CDG) and subsequent analysis showed three point mutations in the ALG6 gene encoding an alpha1,3-glucosyltransferase needed for the addition of the first glucose to the dolichol-linked oligosaccharide. The maternal mutation, C998T, causing an A333V substitution, has been shown to cause CDG-Ic, whereas the two paternal mutations, T391C (Y131H) and C924A (S308R) have not previously been reported. The mutations were tested for their ability to rescue faulty N:-linked glycosylation of carboxypeptidase Y in an ALG6-deficient Saccharomyces cerevisiae strain. Normal human ALG6 rescues glycosylation and A333V partially rescues, whereas the combined paternal mutations (Y131H and S308R) are ineffective. Underglycosylation resulting from each of these mutations is much more severe in rapidly dividing yeast. Similarly, incomplete protein glycosylation in the patient is most severe in rapidly dividing enterocytes during gastroenteritis-induced stress. Incomplete N:-linked glycosylation of an HS core protein and/or other biosynthetic enzymes may explain the selective localized loss of HS and PLE.

Biopsy↗