GSTS Pathology

London, United Kingdom

GSTS Pathology

London, United Kingdom
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Levene M.,St George's, University of London | Coleman D.G.,Huntingdon Life science | Kilpatrick H.C.,Huntingdon Life science | Fairbanks L.D.,GSTS Pathology | And 3 more authors.
Toxicological Sciences | Year: 2013

Erythrocyte-encapsulated thymidine phosphorylase (EE-TP) is currently under development as an enzyme replacement therapy for mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), an autosomal recessive disorder caused by a deficiency of thymidine phosphorylase. The rationale for the development of EE-TP is based on the pathologically elevated metabolites (thymidine and deoxyuridine) being able to freely diffuse across the erythrocyte membrane where the encapsulated enzyme catalyses their metabolism to the normal products. The systemic toxic potential of EE-TP was assessed when administered intermittently by iv bolus injection to BALB/c mice and Beagle dogs for 4 weeks. The studies consisted of one control group receiving sham-loaded erythrocytes twice weekly and two treated groups, one dosed once every 2 weeks and the other dosed twice per week. The administration of EE-TP to BALB/c mice resulted in thrombi/emboli in the lungs and spleen enlargement. These findings were also seen in the control group, and there was no relationship to the number of doses administered. In the dog, transient clinical signs were associated with EE-TP administration, suggestive of an immune-based reaction. Specific antithymidine phosphorylase antibodies were detected in two dogs and in a greater proportion of mice treated once every 2 weeks. Nonspecific antibodies were detected in all EE-TP-treated animals. In conclusion, these studies do not reveal serious toxicities that would preclude a clinical trial of EE-TP in patients with MNGIE, but caution should be taken for infusion-related reactions that may be related to the production of nonspecific antibodies or a cell-based immune response. © The Author 2012. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved.

Goldenberg S.D.,Guys And St Thomas Nhs Foundation Trust | Goldenberg S.D.,King's College London | Gumban M.,GSTS Pathology | Hall A.,GSTS Pathology | And 3 more authors.
Diagnostic Microbiology and Infectious Disease | Year: 2011

Glutamate dehydrogenase (GDH) is popular as a preliminary test for the detection of Clostridium difficile. Recent work has suggested that GDH sensitivity may vary according to ribotype and may be lower for ribotypes 002, 027, and 106 compared with polymerase chain reaction (PCR). We investigated this effect using a dilution series of 64 isolates tested by GDH and Cepheid GeneXpert PCR. PCR was significantly more sensitive than GDH overall; however, there was no difference in detection according to specific ribotype. © 2011.

Barnett A.N.R.,Guys Hospital | Barnett A.N.R.,King's College London | Hudson A.,National Health Service Blood and Transplant | Hadjianastassiou V.G.,Guys Hospital | And 8 more authors.
Transplantation | Year: 2012

BACKGROUND: Blood group-incompatible transplantation is one strategy used when a potential recipient does not have a compatible living donor. Current practice includes desensitization strategies to reduce antibody titers. However, when antibodies are low, in cardiac transplantation in neonates for example, no desensitization is required. This study is the first to examine the distribution of ABO blood group antibody titers in a population of pediatric patients on the deceased-donor renal transplantation waiting list. METHODS: All patients from two pediatric nephrology centers active on the national deceased-donor waiting list had antibody titers (total immunoglobulin load) measured. A simulation modeling the effect of allocating blood group-incompatible deceased-donor kidneys to those patients with titers of 16 or lower was developed. RESULTS: Twenty-four children were screened; eight (33.3%) had titers of either anti-A or anti-B antibodies of 8 or lower. A further three (12.5%) had either an anti-A or anti-B antibody titer of 16. Blood group A or B patients had lower antibody levels than blood group O patients. In blood group O patients, levels of anti-A antibodies were higher than anti-B antibodies (Wilcoxon signed rank test, P=0.028). The simulation model showed that a change in organ allocation policy would increase pediatric transplant activity by 2.2% and reduce the median waiting time for a transplant. CONCLUSION: This allocation strategy may be of particular benefit to those pediatric patients who have been on the deceased-donor waiting list for a long time or those with a high calculated reaction frequency. Copyright © 2012 by Lippincott Williams &Wilkins.

Goldenberg S.D.,King's College London | Finn J.,Guys And St Thomas Nhs Foundation Trust | Sedudzi E.,GSTS Pathology | White J.A.,Foundation Medicine | Tonga C.Y.W.,King's College London
Journal of Clinical Microbiology | Year: 2012

There are currently no commercially available molecular assays for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in rectal swabs with regulatory approval. We compared the Cepheid GeneXpert CT/NG assay with the GenProbe Aptima Combo2 assay, using 409 rectal swabs. Using Aptima as the gold standard, the sensitivity, specificity, and positive and negative predictive values of GeneXpert for the detection of C. trachomatis and N. gonorrhoeae were 86%, 99.2%, 92.5%, and 98.4% and 91.1%, 100%, 100%, and 98.6%, respectively. Despite significant dilution of samples prior to GeneXpert testing, the assay performed well with excellent specificity. Copyright © 2012, American Society for Microbiology. All Rights Reserved.

Lauinger I.L.,King's College London | Lauinger I.L.,Guys And St Thomas Nhs Foundation Trust | Bible J.M.,GSTS Pathology | Halligan E.P.,GSTS Pathology | And 7 more authors.
Journal of Clinical Virology | Year: 2013

Background: It is increasingly recognized that human rhinoviruses (HRV) can be associated with severe infections. However, conflicting results have been reported on the relative prevalence and severity of the three HRV species. Objectives: The relative prevalence and clinical characteristics of HRV-A, B and C, in children attending a South London teaching hospital were investigated retrospectively. Study design: Children aged <16 years with episodes of respiratory tract infections and detectable entero/rhinovirus RNA in respiratory samples between November 2009 and December 2010 were investigated. Retrospective case review was performed and patients' characteristics recorded. Results: Entero/rhinoviruses were the commonest viral pathogens (498/2316; 21.5%). Amongst 204 infection episodes associated with entero/rhinovirus, 167 were typed HRV, HRV-C was the most prevalent (99/167, 59.3%) followed by HRV-A (60/167; 35.9%) and HRV-B (8/167, 4.8%). The severity spectrum of HRV-A and HRV-C infections were similar and affected all parts of the respiratory tract. Co-pathogens were observed in 54 (26.5%) episodes. Severity was increased in patients with non-viral co-pathogens and those with an underlying respiratory condition. Univariate and multiple regression analyses of potential prognostic variables including age, co-pathogens and underlying respiratory illnesses showed that mono-infection with HRV-C, as compared with other HRV species, was associated with more severe disease in young children <3 years. Conclusions: HRV-C was the most prevalent species and on its own was associated with severe disease in children <3 years. The association between infection with HRV species and clinical presentation is complex and affected by many confounding factors. © 2013 Elsevier B.V.

Ahn J.W.,Guys and St Thomas NHS Foundation Trust | Mann K.,GSTS Pathology | Walsh S.,GSTS Pathology | Shehab M.,National Research Center of Egypt | And 4 more authors.
Molecular Cytogenetics | Year: 2010

Background. Several studies have demonstrated that array comparative genomic hybridisation (CGH) for genome-wide imbalance provides a substantial increase in diagnostic yield for patients traditionally referred for karyotyping by G-banded chromosome analysis. The purpose of this study was to demonstrate the feasibility of and strategies for, the use of array CGH in place of karyotyping for genome imbalance, and to report on the results of the implementation of this approach. Results. Following a validation period, an oligoarray platform was chosen. In order to minimise costs and increase efficiency, a patient/patient hybridisation strategy was used, and analysis criteria were set to optimise detection of pathogenic imbalance. A customised database application with direct links to a number of online resources was developed to allow efficient management and tracking of patient samples and facilitate interpretation of results. Following introduction into our routine diagnostic service for patients with suspected genome imbalance, array CGH as a follow-on test for patients with normal karyotypes (n = 1245) and as a first-line test (n = 1169) gave imbalance detection rates of 26% and 22% respectively (excluding common, benign variants). At least 89% of the abnormalities detected by first line testing would not have been detected by standard karyotype analysis. The average reporting time for first-line tests was 25 days from receipt of sample. Conclusions. Array CGH can be used in a diagnostic service setting in place of G-banded chromosome analysis, providing a more comprehensive and objective test for patients with suspected genome imbalance. The increase in consumable costs can be minimised by employing appropriate hybridisation strategies; the use of robotics and a customised database application to process multiple samples reduces staffing costs and streamlines analysis, interpretation and reporting of results. Array CGH provides a substantially higher diagnostic yield than G-banded chromosome analysis, thereby alleviating the burden of further clinical investigations. © 2010 Ahn et al; licensee BioMed Central Ltd.

Hills A.,GSTS Pathology | Ahn J.W.,Guys and St Thomas NHS Foundation Trust | Donaghue C.,GSTS Pathology | Thomas H.,GSTS Pathology | And 2 more authors.
Molecular Cytogenetics | Year: 2010

Background. Array CGH has recently been introduced into our laboratory in place of karyotype analysis for patients with suspected genomic imbalance. Results require confirmation to check sample identity, and analysis of parental samples to determine inheritance and thus assess the clinical significance of the abnormality. Here we describe an MLPA-based strategy for the follow-up of abnormal aCGH results. Results. In the first 17 months of our MLPA-based aCGH follow-up service, 317 different custom MLPA probes for novel aCGH-detected abnormalities were developed for inheritance studies in 164 families. In addition, 110 samples were tested for confirmation of aCGH-detected abnormalities in common syndromic or subtelomeric regions using commercial MLPA kits. Overall, a total of 1215 samples have been tested by MLPA. A total of 72 de novo abnormalities were confirmed. Conclusions. Confirmation of aCGH-detected abnormalities and inheritance of these abnormalities are essential for accurate diagnosis and interpretation of aCGH results. The development of a new service utilising custom made MLPA probes and commercial MLPA kits for follow-up studies of array CGH results has been found to be efficient and flexible in our laboratory. © 2010 Hills et al; licensee BioMed Central Ltd.

Scriven P.N.,GSTS Pathology
Journal of visualized experiments : JoVE | Year: 2011

Pre-implantation genetic diagnosis (PGD) is an established alternative to pre-natal diagnosis, and involves selecting pre-implantation embryos from a cohort generated by assisted reproduction technology (ART). This selection may be required because of familial monogenic disease (e.g. cystic fibrosis), or because one partner carries a chromosome rearrangement (e.g. a two-way reciprocal translocation). PGD is available for couples who have had previous affected children, and/or in the case of chromosome rearrangements, recurrent miscarriages, or infertility. Oocytes aspirated following ovarian stimulation are fertilized by in vitro immersion in semen (IVF) or by intracytoplasmic injection of an individual spermatozoon (ICSI). Pre-implantation cleavage-stage embryos are biopsied, usually by the removal of a single cell on day 3 post-fertilization, and the biopsied cell is tested to establish the genetic status of the embryo. Fluorescence in situ hybridization (FISH) on the fixed nuclei of biopsied cells with target-specific DNA probes is the technique of choice to detect chromosome imbalance associated with chromosome rearrangements, and to select female embryos in families with X-linked disease for which there is no mutation-specific test. FISH has also been used to screen embryos for spontaneous chromosome aneuploidy (also known as PGS or PGD-AS) in order to try and improve the efficiency of assisted reproduction; however, the predictive value of this test using the spreading and FISH technique described here is likely to be unacceptably low in most people's hands and it is not recommended for routine clinical use. We describe the selection of suitable probes for single-cell FISH, spreading techniques for blastomere nuclei, and in situ hybridization and signal scoring, applied to PGD in a clinical setting.

Ahn J.W.,Guys and St Thomas NHS Foundation Trust | Bint S.,GSTS Pathology | Bergbaum A.,GSTS Pathology | Mann K.,GSTS Pathology | And 2 more authors.
Molecular Cytogenetics | Year: 2013

Background: Array CGH is widely used in cytogenetics centres for postnatal constitutional genome analysis, and is now recommended as a first line test in place of G-banded chromosome analysis. At our centre, first line testing by oligonucleotide array CGH for all constitutional referrals for genome imbalance has been in place since June 2008, using a patient vs patient hybridisation strategy to minimise costs. Findings. Out of a total of 13,412 patients tested with array CGH, 8,794 (66%) had array CGH as the first line test. Referral indications for this first line group ranged from neonatal congenital anomalies through to adult neurodisabilities; 25% of these patients had CNVs either in known pathogenic regions or in other regions where imbalances have not been reported in the normal population. Of these CNVs, 46% were deletions or nullisomy, 53% were duplications or triplications, and mosaic imbalances made up the remainder; 87% were <5Mb and would likely not be detected by G-banded chromosome analysis. For cases with completed inheritance studies, 20% of imbalances were de novo. Conclusions: Array CGH is a robust and cost-effective alternative to traditional cytogenetic methodology; it provides a higher diagnostic detection rate than G-banded chromosome analysis, and adds to the sum of information and understanding of the role of genomic imbalance in disease. Use of novel hybridisation strategies can reduce costs, allowing more widespread testing. © 2013 Ahn et al.; licensee BioMed Central Ltd.

Hoang S.,GSTS Pathology | Ahn J.,Guys and St Thomas NHS Foundation Trust | Mann K.,GSTS Pathology | Bint S.,GSTS Pathology | And 4 more authors.
European Journal of Medical Genetics | Year: 2011

Mosaicism for chromosome imbalance has traditionally been detected by karyotype analysis. The introduction of array CGH into clinical diagnostic laboratories and routine clinical practice has raised concerns as to the ability of this new test to detect the presence of more than one cell line. We present our validation data on the detection of chromosome mosaicism by oligonucleotide array CGH, and the cases detected in a cohort of 3042 clinical referrals. Using an artificial mosaicism series, we found that oligonucleotide array CGH using specific analysis parameters could accurately measure levels of mosaicism down to 10% and that the degree of mosaicism could be predicted from fluorescence ratios. We detected 12 cases of mosaicism in our clinical cohort, in 9 of which there was no previous indication of mosaicism. In two cases, G-banded chromosome analysis had been carried out previously, and had failed to detect the abnormal cell line. Three cases had mosaicism for the X chromosome and 9 involved autosomes, of which 4 were mosaic for whole chromosome trisomies, one for whole chromosome monosomy, and four were mosaic for segmental imbalances. We conclude that oligonucleotide array CGH has the power to detect a range of mosaic abnormalities in clinical diagnostic samples. © 2010 Elsevier Masson SAS.

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