How to detect fluctuating order in the high-temperature superconductors

We discuss fluctuating order in a quantum disordered phase proximate to a quantum critical point, with particular emphasis on fluctuating stripe order. Optimal strategies for extracting information concerning such local order from experiments are derived with emphasis on neutron scattering and scanning tunneling microscopy. These ideas are tested by application to two model systems - the exactly solvable one dimensional electron gas with an impurity, and a weakly-interacting 2D electron gas. We extensively review experiments on the cuprate high-temperature superconductors which can be analyzed using these strategies. We adduce evidence that stripe correlations are widespread in the cuprates. Finally, we compare and contrast the advantages of two limiting perspectives on the high-temperature superconductor: weak coupling, in which correlation effects are treated as a perturbation on an underlying metallic (although renormalized) Fermi liquid state, and strong coupling, in which the magnetism is associated with well defined localized spins, and stripes are viewed as a form of micro-phase separation. We present quantitative indicators that the latter view better accounts for the observed stripe phenomena in the cuprates.Comment: 43 pages, 11 figures, submitted to RMP; extensively revised and greatly improved text; one new figure, one new section, two new appendices and more reference

Saposins A,B,C, and D in plasma of patients with lysosomal storage disorders

BackgroundEarly diagnosis of lysosomal storage disorders (LSDs), before the onset of irreversible pathology, will be critical for maximum efficacy of many current and proposed therapies. To search for potential markers of LSDs, we measured saposins A, B, C, and D in patients with these disorders.MethodsFour time-delayed fluorescence immunoquantification assays were used to measure each of the saposins in plasma from 111 unaffected individuals and 334 LSD-affected individuals, representing 28 different disorders.ResultsSaposin A was increased above the 95th centile of the control population in 59% of LSD patients; saposins B, C, and D were increased in 25%, 61%, and 57%, respectively. Saposins were increased in patients from several LSD groups that in previous studies did not show an increase of lysosome-associated membrane protein-1 (LAMP-1).ConclusionSaposins may be useful markers for LSDs when used in conjunction with LAMP-1.Chang, Melissa H. Y. ; Bindloss, Colleen A. ; Grabowski, Gregory A. ; Qi, Xiaoyang ; Winchester, Bryan ; Hopwood, John J. ; Meikle, Peter J

Development of a two-dimensional gel electrophoresis database of human lysosomal proteins

Two-dimensional gel electrophoresis databases have been generated for a range of tissue cell and fluid types, from a number of species. A major difficulty in the development of such databases is the large number of proteins present in even a single cell type (> 10,000) and the low levels of many of these proteins. One approach to overcome these difficulties is to fractionate the cell into its organelles and generate individual databases for each subcellular component. This has the added advantage of assigning a cellular location to each protein identified. Here we report the development of a two-dimensional gel electrophoresis database of lysosomal proteins.Timothy K. Chataway, Alison M. Whittle, Martin D. Lewis, Colleen A. Bindloss, Robert L. Moritz, Richard J. Simpson, John J. Hopwood and Dr. Peter J. Meikl

Determination of oligosaccharides and glycolipids in amniotic fluid by electrospray ionisation tandem mass spectrometry: in utero indicators of lysosomal storage diseases

Prenatal diagnosis is available for many lysosomal storage disorders (LSD) using chorionic villus samples or amniocytes. Such diagnoses can be problematical if sample transport and culture are required prior to analysis. The purpose of this study was to identify useful biochemical markers for the diagnosis of lysosomal storage disorders from amniotic fluid. Amniotic fluid samples from control (n=49) and LSD affected (n=36) pregnancies were analysed for the protein markers LAMP-1 and saposin C by ELISA, and for oligosaccharide and lipid metabolite markers by electrospray ionisation-tandem mass spectrometry. Lysosomal storage disorder samples include; aspartylglucosaminuria, galactosialidosis, Gaucher disease, GM1 gangliosidosis, mucopolysaccharidosis types I, II, IIIC, IVA, VI, and VII, mucolipidosis type II, multiple sulfatase deficiency, and sialidosis type II. Each disorder produced a unique signature metabolic profile of protein, oligosaccharide, and glycolipid markers. Some metabolite elevations directly related to the disorder whilst others appeared unrelated to the primary defect. Many lysosomal storage disorders were clearly distinguishable from control populations by the second trimester and in one case in the first trimester. Samples from GM1 gangliosidosis and mucopolysaccharidosis type VII displayed a correlation between gestational age and amount of stored metabolite. These preliminary results provide proof of principal for the use of biomarkers contained in amniotic fluid as clinical tests for some of the more frequent lysosomal storage disorders causal for hydrops fetalis

Determination of acid a-glucosidase protein: evaluation as a screening marker for pompe disease and other lysosomal storage disorders

BackgroundIn recent years, there have been significant advances in the development of enzyme replacement and other therapies for lysosomal storage disorders (LSDs). Early diagnosis, before the onset of irreversible pathology, has been demonstrated to be critical for maximum efficacy of current and proposed therapies. In the absence of a family history, the presymptomatic detection of these disorders ideally can be achieved through a newborn screening program. One approach to the development of such a program is the identification of suitable screening markers. In this study, the acid alpha-glucosidase protein was evaluated as a marker protein for Pompe disease and potentially for other LSDs.MethodsTwo sensitive immunoquantification assays for the measurement of total (precursor and mature) and mature forms of acid alpha-glucosidase protein were used to determine the concentrations in plasma and dried blood spots from control and LSD-affected individuals.ResultsIn the majority of LSDs, no significant increases above control values were observed. However, individuals with Pompe disease showed a marked decrease in acid alpha-glucosidase protein in both plasma and whole blood compared with unaffected controls. For plasma samples, this assay gave a sensitivity of 95% with a specificity of 100%. For blood spot samples, the sensitivity was 82% with a specificity of 100%.ConclusionsThis study demonstrates that it is possible to screen for Pompe disease by screening the concentration of total acid alpha-glucosidase in plasma or dried blood spots

Two site-directed mutations abrogate enzyme activity but have different effects on the conformation and cellular content of the N-acetylgalactosamine 4-sulphatase protein.

The sulphatase family of enzymes have regions of sequence similarity, but relatively little is known about either the structure-function relationships of sulphatases, or the role of highly conserved amino acids. The sequence of amino acids CTPSR at position 91-95 of 4-sulphatase has been shown to be highly conserved in all of the sequenced sulphatase enzymes. The cysteine at amino acid 91 of 4-sulphatase was selected for mutation analysis due to its potential role in either the active site, substrate-binding site or part of a key structural domain of 4-sulphatase and due to the absence of naturally occurring mutations in this residue in mucopolysaccharidosis type VI (MPS VI) patients. Two mutations, C91S and C91T, altering amino acid 91 of 4-sulphatase were generated and expressed in Chinese hamster ovary cells. Biochemical analysis of protein from a C91S cell line demonstrated no detectable 4-sulphatase enzyme activity but a relatively normal level of 4-sulphatase polypeptide (180% of the wild-type control protein level). Epitope detection, using a panel of ten monoclonal antibodies, demonstrated that the C91S polypeptide had a similar immunoreactivity to wild-type 4-sulphatase, suggesting that the C91S substitution does not induce a major structural change in the protein. Reduced catalytic activity associated with normal levels of 4-sulphatase protein have not been observed in any of the MPS VI patients tested and all show evidence of structural modification of 4-sulphatase protein with the same panel of antibodies [Brooks, McCourt, Gibson, Ashton, Shutter and Hopwood (1991) Am. J. Hum. Genet. 48, 710-719]. The loss of enzyme activity without a detectable protein conformation change suggests that Cys-91 may be a critical residue in the catalytic process. In contrast, analysis of protein from a C91T cell line revealed low levels of catalytically inactive 4-sulphatase polypeptide (0.37% of the wild-type control protein level) which had missing or masked epitopes, suggesting an altered protein structure or conformation. Subcellular fractionation studies of the C91T cell line demonstrated a high proportion of 4-sulphatase polypeptide content in organelles characteristic of microsomes. The aberrant intracellular localization and the reduced cellular content of 4-sulphatase polypeptide was consistent with the observed structural modification leading to retention and degradation of the protein within an early vacuolar compartment

Correlation among genotype, phenotype, and biochemical markers in Gaucher disease: Implications for the prediction of disease severity

Gaucher disease is a lysosomal storage disorder characterized by a deficiency of the enzyme acid beta-glucosidase. The clinical manifestations of Gaucher disease are highly variable, and although certain genotypes are often associated with mild or severe symptoms, a defined correlation between genotype and phenotype does not exist. Identification of biochemical markers characteristic of pathology may be of use in predicting the progression of the disease state. In this study the relationship among genotype, glycolipid substrates, lysosomal proteins, and the clinical manifestations of Gaucher disease has been evaluated. Plasma glycolipids were analyzed using electrospray ionization-tandem mass spectrometry. Lysosomal-associated membrane protein-1 (LAMP-1) and saposin C were determined by immunoquantification. Patients with Gaucher disease were shown to have an increased 16:0-glucosylceramide/16:0-lactosylceramide ratio and elevated concentrations of LAMP-1 and saposin C in plasma. A general relationship was found to exist among the 16:0-glucosylceramide/16:0-lactosylceramide ratio, LAMP-1 and saposin C levels, and patient phenotype, providing a refinement of the genotype-phenotype correlation. These findings have major implications for the diagnosis, prediction of disease severity, and monitoring of therapy in patients with Gaucher disease.Whitfield, Phillip D. ; Nelson, Paul ; Sharp, Peter C. ; Bindloss, Colleen A. ; Dean, Caroline ; Ravenscroft, Elaine M. ; Fong, Beverley A. ; Fietz, Michael J. ; Hopwood, John J. ; Meikle, Peter J