Diagnosing idiopathic learning disability: a cost-effectiveness analysis of microarray technology in the National Health Service of the United Kingdom

Array based comparative genomic hybridisation (aCGH) is a powerful technique for detecting clinically relevant genome imbalance and can offer 40 to > 1000 times the resolution of karyotyping. Indeed, idiopathic learning disability (ILD) studies suggest that a genome-wide aCGH approach makes 10–15% more diagnoses involving genome imbalance than karyotyping. Despite this, aCGH has yet to be implemented as a routine NHS service. One significant obstacle is the perception that the technology is prohibitively expensive for most standard NHS clinical cytogenetics laboratories. To address this, we investigated the cost-effectiveness of aCGH versus standard cytogenetic analysis for diagnosing idiopathic learning disability (ILD) in the NHS. Cost data from four participating genetics centres were collected and analysed. In a single test comparison, the average cost of aCGH was ￡442 and the average cost of karyotyping was ￡117 with array costs contributing most to the cost difference. This difference was not a key barrier when the context of follow up diagnostic tests was considered. Indeed, in a hypothetical cohort of 100 ILD children, aCGH was found to cost less per diagnosis (￡3,118) than a karyotyping and multi-telomere FISH approach (￡4,957). We conclude that testing for genomic imbalances in ILD using microarray technology is likely to be cost-effective because long-term savings can be made regardless of a positive (diagnosis) or negative result. Earlier diagnoses save costs of additional diagnostic tests. Negative results are cost-effective in minimising follow-up test choice. The use of aCGH in routine clinical practice warrants serious consideration by healthcare providers. Copyright statement The Corresponding Author has the right to grant on behalf of all authors and does grant on behalf of all authors, an exclusive licence (or non exclusive for government employees) on a worldwide basis to the BMJ Publishing Group Ltd, and its Licensees to permit this article (if accepted) to be published in BMJ editions and any other BMJPGL products and to exploit all subsidiary rights, as set out in our licence (bmj.com/advice/copyright.shtml). Authorship The authors included on this paper fulfil the criteria of authorship and no one who fulfils the criteria has been excluded from authorship. The authors made a substantial contribution to the conception, design, analysis and interpretation of data. They were involved in drafting the article or revising it critically for important intellectual content and approving the version to be published. Contributorship Sarah Wordsworth (Guarantor): Planning, conducting and reporting work, interpretation of data, drafting and revising article. James Buchanan: Conducting and reporting work, interpretation of data, revising article. Regina Regan: Completing costing questionnaire, providing protocol details, other costing information, interpretation of data, information about learning disability and genome imbalance and revising article. Val Davison: Completing costing questionnaire, providing protocol details, sharing overall laboratory experience and drafting article. Kim Smith: Completing costing questionnaire, providing protocol details, drafting article. Sara Dyer: Completing costing questionnaire and providing protocol details. Carolyn Campbell: Completing costing questionnaire and providing protocol details. Edward Blair: Critical appraisal of article for clinical content and revising article. Eddy Maher: Completing costing questionnaire, providing protocol details, sharing overall laboratory experience and drafting article. Jenny Taylor: Planning and facilitating work between centres. Drafting and revising article. Samantha JL Knight: Completing costing questionnaire, providing protocol details, other costing information, interpretation of data, providing information about learning disability and genome imbalance, drafting and revising article. Jenny Taylor and Samantha JL Knight contributed equally to the work presented.     

Central Charged Residues in DIIIS4 Regulate Deactivation Gating in Skeletal Muscle Sodium Channels

Summary 1. Mutations in the S4 segment of domain III in the voltage gated skeletal muscle sodium channel hNa_V1.4 were constructed to test the roles of each charged residue in deactivation gating. Mutations comprised charge reversals at K1-R6, charge neutralization, and substitution at R4 and R5. 2. Charge-reversing mutations at R4 and R5 produced the greatest alteration of activation parameters compared to hNa_V1.4. Effects included depolarization of the conductance/voltage (g/V) curve, decreased valence and slowing of kinetics. 3. Reversal of charge at R2 to R4 hyperpolarized, and reversal at R5 or R6 depolarized the h _∞ curve. Most DIIIS4 mutations slowed inactivation from the open state. R4E slowed closed state fast inactivation and R5E inhibited its completion. 4. Deactivation from the open and/or inactivated state was prolonged in mutations reversing charge at R2 to R4 but accelerated by reversal of charge at R5 or R6. Effects were most pronounced at central charges R4 and R5. 5. Charge and structure each contribute to effects of mutations at R4 and R5 on channel gating. Effects of mutations on activation and deactivation at R4 and, to a lesser extent R5, were primarily owing to charge alteration, whereas effects on fast inactivation were charge independent.     

Dynamic analysis of GS-NS0 cells producing a recombinant monoclonal antibody during fed-batch culture

In this study we have analyzed the dynamic covariation of the mammalian cell proteome with respect to functional phenotype during fed-batch culture of NS0 murine myeloma cells producing a recombinant IgG(4) monoclonal antibody. GS-NS0 cells were cultured in duplicate 10 L bioreactors (36.5 degrees C, 15% DOT, pH 7.0) for 335 h and supplemented with a continuous feed stream after 120 h. Cell-specific growth rate declined continuously after 72 h of culture. Cell-specific recombinant monoclonal antibody production rate (qP) varied sixfold through culture. Whilst qP correlated with relative recombinant heavy chain mRNA abundance up to 216 h, qP subsequently declined, independent of recombinant heavy chain or light chain mRNA abundance. GS-NS0 cultures were sampled at 48 h intervals between 24 and 264 h of culture for proteomic analyses. Total protein abundance and nascent polypeptide synthesis was determined by 2D PAGE of unlabeled proteins visualized by SYPRO Ruby and autoradiography of (35)S-labeled polypeptides, respectively. Covariation of nascent polypeptide synthesis and abundance with biomass-specific cell growth, glucose and glutamate consumption, lactate and Mab production rates were then examined using two partial least squares regression models. Most changes in polypeptide synthesis or abundance for proteins previously identified by mass spectrometry were positively correlated with biomass-specific growth rate. We conclude that the substantial transitions in cell physiology and qP that occur during culture utilize a relatively constant complement of the most abundant host cell machines that vary primarily with respect to induced changes in cell growth rate.     

Does the importance of the C-terminal residues in the maturation of RgpB from Porphyromonas gingivalis reveal a novel mechanism for protein export in a subgroup of Gram-Negative bacteria?

The mature 507-residue RgpB protein belongs to an important class of extracellular outer membrane-associated proteases, the gingipains, from the oral pathogen Porphyromonas gingivalis that has been shown to play a central role in the virulence of the organism. The C termini of these gingipains along with other outer membrane proteins from the organism share homologous sequences and have been suggested to function in attachment of these proteins to the outer membrane. In this report, we have created a series of truncated and site-directed mutants of the C terminus from a representative member of this class, the RgpB protease, to investigate its role in the maturation of these proteins. Truncation of the last two residues (valyl-lysine) from the C terminus is sufficient to create an inactive version of the protein that lacks the posttranslational glycosylation seen in the wild type, and the protein remains trapped behind the outer membrane. Alanine scanning of the last five residues revealed the importance of the C-terminal motif in mediating correct posttranslational modification of the protein. This result may have a wider implication in a novel secretory pathway in distinct members of the Cytophaga-Flavobacterium-Bacteroidetes phylum.     

Centrin1 is required for organelle segregation and cytokinesis in Trypanosoma brucei

Centrin is a calcium-binding centrosome/basal body-associated protein involved in duplication and segregation of these organelles in eukaryotes. We had shown that disruption of one of the centrin genes (centrin1) in Leishmania amastigotes resulted in failure of both basal body duplication and cytokinesis. Here, we undertook to define the role of centrin1 (TbCen1) in the duplication and segregation of basal body and its associated organelles kinetoplast and Golgi, as well as its role in cytokinesis of the procyclic form of Trypanosoma brucei by depleting its protein using RNA inhibition methodology. TbCen1-depleted cells showed significant reduction in growth compared with control cells. Morphological analysis of these cells showed they were large and pleomorphic with multiple detached flagella. Both immunofluorescence assays using organelle-specific antibodies and electron microscopic analysis showed that TbCen1-deficient cells contained multiple basal bodies, kinetoplasts, Golgi, and nuclei. These multiple organelles were, however, closely clustered together, indicating duplication without segregation in the absence of centrin. This failure in organelle segregation may be the likely cause of inhibition of cytokinesis, suggesting for the first time a new and unique role for centrin in the segregation of organelles without affecting their multiplication in the procyclic form of T. brucei.     

Biological consequences of dosage dependent gene regulatory systems

Chromatin and gene regulatory molecules tend to operate in multisubunit complexes in the process of controlling gene expression. Accumulating evidence suggests that varying the amount of any one member of such complexes will affect the function of the whole via the kinetics of assembly and other actions. In effect, they exhibit a "balance" among themselves in terms of the activity of the whole. When this fact is coupled with genetic and biological observations stretching back a century, a synthesis emerges that helps explain at least some aspects of a variety of phenomena including aneuploid syndromes, dosage compensation, quantitative trait genetics, regulatory gene evolution following polyploidization, the emergence of complexity in multicellular organisms, the genetic basis of evolutionary gradualism and potential implications for heterosis and co-evolving genes complexes involved with speciation. In this article we will summarize the evidence for this potential synthesis.     

Diverse subtypes and developmental origins of trophoblast giant cells in the mouse placenta

Trophoblast giant cells (TGCs) are the first terminally differentiated subtype to form in the trophoblast cell lineage in rodents. In addition to mediating implantation, they are the main endocrine cells of the placenta, producing several hormones which regulate the maternal endocrine and immune systems and promote maternal blood flow to the implantation site. Generally considered a homogeneous population, TGCs have been identified by their expression of genes encoding placental lactogen 1 or proliferin. In the present study, we have identified a number of TGC subtypes, based on morphology and molecular criteria and demonstrated a previously underappreciated diversity of TGCs. In addition to TGCs that surround the implantation site and form the interface with the maternal deciduas, we demonstrate at least three other unique TGC subtypes: spiral artery-associated TGCs, maternal blood canal-associated TGCs and a TGC within the sinusoidal spaces of the labyrinth layer of the placenta. All four TGC subtypes could be identified based on the expression patterns of four genes: Pl1, Pl2, Plf (encoded by genes of the prolactin/prolactin-like protein/placental lactogen gene locus), and Ctsq (from a placental-specific cathepsin gene locus). Each of these subtypes was detected in differentiated trophoblast stem cell cultures and can be differentially regulated; treatment with retinoic acid induces Pl1/Plf+ TGCs preferentially. Furthermore, cell lineage tracing studies indicated unique origins for different TGC subtypes, in contrast with previous suggestions that secondary TGCs all arise from Tpbpa+ ectoplacental cone precursors.     

Oocyte CD9 is enriched on the microvillar membrane and required for normal microvillar shape and distribution

Microvilli are found on the surface of many cell types, including the mammalian oocyte, where they are thought to act in initial contact of sperm and oocyte plasma membranes. CD9 is currently the only oocyte protein known to be required for sperm-oocyte fusion. We found CD9 is localized to the oocyte microvillar membrane using transmission electron microscopy (TEM). Scanning electron microscopy (SEM) showed that CD9 null oocytes, which are unable to fuse with sperm, have an altered length, thickness and density of their microvilli. One aspect of this change in morphology was quantified using TEM by measuring the radius of curvature at the microvillar tips. A small radius of curvature is thought to promote fusibility and the radius of curvature of microvillar tips on CD9 wild-type oocytes was found to be half that of the CD9 null oocytes. We found that oocyte CD9 co-immunoprecipitates with two Ig superfamily cis partners, EWI-2 and EWI-F, which could have a role in linking CD9 to the oocyte microvillar actin core. We also examined latrunculin B-treated oocytes, which are known to have reduced fusion ability, and found altered microvillar morphology by SEM and TEM. Our data suggest that microvilli may participate in sperm-oocyte fusion. Microvilli could act as a platform to concentrate adhesion/fusion proteins and/or provide a membrane protrusion with a low radius of curvature. They may also have a dynamic interaction with the sperm that serves to capture the sperm cell and bring it into close contact with the oocyte plasma membrane.     

Conformationally restricted homotryptamines 3. Indole tetrahydropyridines and cyclohexenylamines as selective serotonin reuptake inhibitors

A series of indole tetrahydropyridine and indole cyclohexenylamines was prepared, and their binding affinities at the human serotonin transporter (SERT) were determined. In particular, a nitrile substituent at the C5 position of the indole ring gave potent SERT activity. The stereochemistry of the N,N-dimethylamine substituent was determined for the most potent indole cyclohexenylamine, 6a. The enantiomers of 6a were energy minimized and compared to other conformationally restricted SSRIs. Compound 6a was found to give a dose-response similar to the SSRI fluoxetine in microdialysis studies in rats.