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Biomedical subjects

E Gray

Publications and source records attributed to E Gray.

At least 19 recordsLinked to original sources
PubMed2026

Longitudinal ctDNA tracking in early and recurrent breast cancer using an ultrasensitive structural variant-based assay: an extended analysis from the TRACER study.

BACKGROUND: Detection of circulating tumor DNA (ctDNA) following curative-intent therapy is prognostic of disease recurrence in early-stage breast cancer (EBC). An ultrasensitive structural variant (SV)-based ctDNA assay was evaluated previously in a 100-patient EBC cohort treated with neoadjuvant therapy, demonstrating high sensitivity, specificity, and a long lead-time to relapse. The stability of primary tumor-specific SVs at and after metastatic recurrence and their utility for longer-term ctDNA monitoring had not been established. PATIENTS AND METHODS: An updated retrospective analysis of ctDNA dynamics was conducted in an expanded cohort of 121 patients with EBC treated with neoadjuvant therapy. Plasma samples were collected at key clinical timepoints and serially in several patients who experienced metastatic recurrence. Clinical variables were abstracted from medical records. Associations between ctDNA detection, dynamics, and clinical outcomes were evaluated in the early-stage and metastatic settings. RESULTS: Thirty of 121 patients experienced clinical recurrence (28 distant, 2 local) over a median follow-up of 4.2 years (range 0.5-8.8; 25 ctDNA evaluable with adjuvant timepoints). All patients with detectable ctDNA in the adjuvant setting developed metastatic recurrence (22/22). Median lead time from ctDNA detection to metastatic recurrence was 346 days (range 0-1937). Among recurrent cases, 79% of primary tumor-specific SVs (n = 17 patients, tumor fraction ≥0.1%) remained detectable in plasma [range 7% (1/14 SV)-100% (15/15); median: 92%]. ctDNA dynamics in the recurrent metastatic setting demonstrated a strong relationship with radiographic outcomes in evaluable patients (n = 9). CONCLUSION: This SV-based digital PCR assay provided ultrasensitive ctDNA detection in an expanded EBC cohort, maintaining 100% positive predictive value for metastatic recurrence. In patients with recurrence, ctDNA dynamics were concordant with radiographic outcomes. Prospective studies evaluating the clinical utility of longitudinal ctDNA monitoring are warranted.

MRD↗
PubMed2005

Barostat testing of rectal sensation and compliance in humans: comparison of results across two centres and overall reproducibility.

We assessed reproducibility of measurements of rectal compliance and sensation in health in studies conducted at two centres. We estimated samples size necessary to show clinically meaningful changes in future studies. We performed rectal barostat tests three times (day 1, day 1 after 4 h and 14-17 days later) in 34 healthy participants. We measured compliance and pressure thresholds for first sensation, urgency, discomfort and pain using ascending method of limits and symptom ratings for gas, urgency, discomfort and pain during four phasic distensions (12, 24, 36 and 48 mmHg) in random order. Results obtained at the two centres differed minimally. Reproducibility of sensory end points varies with type of sensation, pressure level and method of distension. Pressure threshold for pain and sensory ratings for non-painful sensations at 36 and 48 mmHg distension were most reproducible in the two centres. Sample size calculations suggested that crossover design is preferable in therapeutic trials: for each dose of medication tested, a sample of 21 should be sufficient to demonstrate 30% changes in all sensory thresholds and almost all sensory ratings. We conclude that reproducibility varies with sensation type, pressure level and distension method, but in a two-centre study, differences in observed results of sensation are minimal and pressure threshold for pain and sensory ratings at 36-48 mmHg of distension are reproducible.

Adult↗
PubMed2004

Characterization of the cell-surface procoagulant activity of T-lymphoblastoid cell lines.

The procoagulant activity (PCA) of four T-lymphoblastoid cell lines (CEM-CCRF, Jurkat, Molt-4 and A3.01) at different stages of differentiation has been characterized and compared with that of a monocytoid cell line (THP-1). Four assay systems were employed; the activated partial thromboplastin time (APTT); prothrombin time/tissue factor (TF) activity; a purified factor (F)Xa generation system and cancer procoagulant. High levels of TF activity were seen only with the monocytic cells. However the more differentiated of the T-lymphoblastoid cells (Molt-4 and A3.01) were more active than monocytic cells in supporting FXa generation. This pattern was not repeated for the APTT assay, which was related to cell-surface TF activity, since it was partially inhibited by antiTF antibody. Annexin V totally inhibited the activity observed in all three assay systems, indicating that the PCA of T-lymphoblastoid cells is primarily due to expression of negatively charged phospholipids. However, antiphosphatidylserine antibody even at a high concentration gave only partial inhibition of the activity observed in the APTT and FXa generation systems for the cells compared with almost total inhibition for the phospholipid standard, suggesting either that cellular phosphatidylserine (PS) is less accessible to the antibody, or that PS is not the sole negatively charged phospholipid responsible for this activity. Flow cytometry studies using propidium iodide and annexin V showed that the PCA, although linked to PS exposure, was not the result of apoptosis.

Apoptosis↗
PubMed2004

Collaborative study to establish the Low-molecular-mass heparin for assay--European Pharmacopoeia Biological Reference Preparation.

Thirty laboratories participated in a collaborative study to calibrate replacements for the 1st International Standard for Low Molecular Weight Heparin and the European Pharmacopoeia Low-molecular-mass heparin for assay Biological Reference Preparation. Two freeze-dried materials and one liquid preparation were included in the study. All three samples gave excellent intra- and inter-laboratory variations (majority of mean % geometric coefficient of variation < 10 %) when assayed against the 1st International Standard by both anti-Xa and anti-IIa assays. There were no major differences found between potency estimates using all methods and that obtained using European Pharmacopoeia method only. Overall, this study showed that the differences between the candidates are marginal. Based on the results of the study Sample B, 01/608 was established as the 2nd International Standard for Low Molecular Weight Heparin. Sample A, 01/592 and sample C, the liquid preparation, were established as replacements for the European Pharmacopoeia 'Low-molecular-mass heparin for assay' Biological Reference Preparation.

Calibration↗
PubMed2002

Sacrococcygeal teratomas: the UK Children's Cancer Study Group's experience. I. Neonatal.

The aim of this study was to review the United Kingdom Children's Cancer Study Group (UKCCSG) experience of sacrococcygeal teratomas (SCT) including histological presentation, response to surgery and chemotherapy, and long term effects of the tumour and treatment. This paper presents the results for those children diagnosed during the neonatal period. Children aged up to 4 weeks with biopsy proven localised or metastatic sacrococcygeal germ cell tumours were eligible. From 1st January 1989 to 31st December 1997 (9 years), 15 UKCCSG centres registered 51 neonates with SCT into GC 8901. Surgery alone was performed in all and the prognosis was good - except for 1 baby who died from massive haemorrhage at the initial operation and 1 who died from the complications of prematurity. Seven of the 51 children (14%) who had teratomas in the neonatal period (5 mature, two immature) had yolk sac tumour (YST) recurrence at: 4, 12, 15, 20, 20, 28 and 32 months of age. These children received chemotherapy in the form of etoposide/bleomycin/carboplatin (JEB) and are alive and well at review. These results emphasise the need for oncological follow-up of SCT and the good response to JEB chemotherapy of malignant teratomas and YST.

Female↗
PubMed2002

Co-ordinated Ca(2+)-signalling within pancreatic islets: does beta-cell entrainment require a secreted messenger.

Isolated beta-cells are heterogeneous in sensory, biosynthetic and secretory capabilities, however, to enable efficient and appropriate secretion, cellular activity within the intact islet is synchronised. Historically, the entrainment of activity to a common pattern has been attributed to gap-junction mediated cell-to-cell communication. Although clearly influential, the possibility remains for other local synchronising mechanisms. In this study, we have used small clusters of insulin-secreting MIN6 cells to assess how contact-dependent, homotypic interactions between cells influences nutrient- and non-nutrient- evoked Ca(2+)-handling and insulin secretion, and to determine whether a secreted product plays a role in the synchronisation of oscillatory activity. Tolbutamide evoked a concentration-dependent recruitment of active cells within cell clusters, both in terms of numbers of cells and amplitude of the evoked Ca(2+)-response. The change in [Ca(2+)](i) was characteristically oscillatory above a mean elevated plateau, and was in phase between member cells of an individual cluster. Even at maximal concentrations (100 microM) some cells within a cluster responded before their immediate neighbours. Subsequent oscillatory behaviour then became entrained between member cells within that cluster. Inhibiting exocytosis using the microtubule inhibitors vincristine and nocodazole, or the adrenergic agent noradrenaline, did not prevent tolbutamide-evoked oscillatory changes in [Ca(2+)](i) but did reduce the probability of obtaining synchronous activity within an individual cluster. Above a threshold glucose concentration, the number of cells secreting insulin increased, without a commensurate change in secretory efficiency. This recruitment of cells secreting insulin mirrored Ca(2+) data that showed a glucose-dependent increase in cell number, without a change in the mean basal-to-peak change in [Ca(2+)](i). Together these data suggest that synchronised behaviour in MIN6 cells is dependent, in part, on a secreted factor that acts in a local paracrine fashion to recruit heterogeneous individual cellular activity into an organised group response.

Animals↗
PubMed2002

Antithrombin: a new look at the actions of a serine protease inhibitor.

Antithrombin (AT) is a plasma-derived, single-chain glycoprotein with a molecular weight of 58 kDa. It is a serine protease inhibitor (serpin), sharing about 30% homology in amino acid sequence with other serpins. AT is a complex molecule with multiple biologically important properties. It is a potent anticoagulant that has been demonstrated to provide benefit in animal models and small cohorts of patients with coagulation disorders. AT also has remarkable anti-inflammatory properties, several of which result from its actions in the coagulation cascade. Activated coagulation proteases like activated factor X and thrombin contribute to inflammation; for instance, by the release of pro-inflammatory mediators. Inhibition of these proteases by AT prevents their specific interaction with cells and subsequent reactions. Anti-inflammatory properties of AT independent of coagulation involve direct interactions with cells leading to the release of, for instance, prostacyclin. Binding of AT to a recently identified cellular receptor, syndecan-4, leads to the interference with the intracellular signal induced by mediators like lipopolysaccharides and, thereby, to a down-modulation of the inflammatory response. AT has been shown to be effective in prospective and well-controlled small-scale studies of patients with inflammatory conditions, including sepsis. Although AT did not decrease overall patient mortality in a double-blind, placebo-controlled, phase III trial of patients with sepsis, it is important to note that AT improved the survival of individuals in this study not receiving heparin as a prophylactic regimen, which can be explained by the impaired interaction of AT with its cellular receptor in the presence of heparin, resulting in the reduction of the anti-inflammatory properties. Accordingly, the supplementation of AT without concomitant heparin may be beneficial in disorders with inflammatory characteristics, which has to be demonstrated in further clinical studies. Finally, recent results suggest that latent AT can induce apoptosis of endothelial cells by disrupting cell-matrix interactions. Further investigations will have to demonstrate whether latent and/or cleaved AT are physiological means to control angiogenesis. A potential prophylactic or therapeutic use as an anti-angiogenic and antitumor agent merits further exploration, including whether the growth of vessels in tumor tissues or close to tumors can be controlled by latent AT without affecting the formation of blood vessels during wound healing processes.

Animals↗
PubMed2001

Structural and functional characterization of B-domain deleted recombinant factor VIII.

A new high-purity recombinant factor VIII preparation has been developed for the treatment of hemophilia A. Structurally, this factor VIII preparation, B-domain deleted recombinant factor VIII (BDDrFVIII), differs from other recombinant and plasma-derived factor VIII preparations in that most of the B-domain has been deleted. To ensure that BDDrFVIII contains the requisite structural and functional features, it has been subjected to detailed biochemical and biophysical characterization in comparison to the plasma-derived form of factor VIII. Laboratory studies have shown that the primary, secondary, and tertiary structures of BDDrFVIII and the posttranslational modifications are similar to those of the [80 + 90]-kd form of plasma-derived factor VIII. In addition, BDDrFVIII has full biologic activity compared with full-length factor VIII preparations.

Amino Acid Sequence↗
PubMed2001

Antithrombin inhibits lipopolysaccharide-induced tissue factor and interleukin-6 production by mononuclear cells, human umbilical vein endothelial cells, and whole blood.

OBJECTIVE: To investigate the effects of antithrombin on lipopolysaccharide (LPS)-induced tissue factor and interleukin-6 (IL-6) production in three different in vitro cellular systems: whole blood, human umbilical vein endothelial cells, and mononuclear cells. DESIGN AND SETTING: Laboratory in vitro study of the effects of antithrombin on procoagulant activity and cytokine release by LPS-stimulated endothelial and peripheral blood cells. SUBJECTS: In vitro whole blood, isolated human umbilical vein endothelial cell, and mononuclear cell cultures. INTERVENTIONS: Addition of antithrombin to LPS-treated whole blood, human umbilical vein endothelial cells, and mononuclear cells. MEASUREMENT AND MAIN RESULTS: Citrated whole blood, isolated human umbilical vein endothelial cells, or mononuclear cells were stimulated with LPS for 4-6 hrs in the presence or absence of antithrombin. Tissue factor activity was estimated by a tissue factor-dependent clotting or chromogenic assay and IL-6 was measured by specific ELISA. Antithrombin was found to inhibit tissue factor and IL-6 production in all three systems in a dose-dependent manner (0-40 IU/mL). Flow-through fractions of immunoadsorbed antithrombin concentrate were found to be ineffective. Five different batches of the same antithrombin concentrate were tested and the inhibitory activity was found to be consistent throughout all batches. Up to 40 microM of recombinant hirudin, a specific thrombin inhibitor, did not inhibit the production of tissue factor or IL-6 in either of the three cell systems, suggesting that the observed inhibition by antithrombin was not due solely to its ability to inhibit thrombin. CONCLUSIONS: Apart from the inhibition of thrombin and other activated clotting factors, antithrombin may also down-regulate the cellular expression of proinflammatory cytokines. Consequently, antithrombin concentrates may have value in the treatment of sepsis-induced disseminated intravascular coagulation.

Antithrombins↗
PubMed2001

Structural and functional characteristics of the B-domain-deleted recombinant factor VIII protein, r-VIII SQ.

Recombinant factor VIII SQ (r-VIII SQ), ReFacto, is a recombinant factor VIII product similar to the smallest active factor VIII protein found in plasma-derived factor VIII (p-VIII) concentrates. The protein comprises two polypeptide chains of 80 and 90 kDa and lacks the major part of the heavily glycosylated B-domain i.e. amino acids Gln744 to Ser1637. r-VIII SQ retains six potential glycosylation sites for N-linked oligosaccharides at asparagine residues 41, 239, 582, 1685, 1810 and 2118. We describe a thorough comparison of the characteristics of r-VIII SQ with those of p-VIII. The primary and secondary structures of r-VIII SQ were in good agreement with that of B-domain-deleted p-VIII (p-VIII-LMW) as shown by SDS-PAGE, Western blotting with antifactor VIII antibodies, tryptic mapping, amino acid sequence analysis and circular dichroism spectroscopy. A few divergences also existed. Thus r-VIII SQ was shown to contain a small amount of the single chain primary translation product of 170 kDa and also the product specific sequence of 14 amino acids, the SQ-link, in the C-terminal end of the 90 kDa chain. It was shown that r-VIII SQ had a high specific activity of about 14,000 IU VIII:C/mg as determined by use of a chromogenic substrate assay. The r-VIII SQ protein was comparable to p-VIII forms with a retained B-domain, in terms of potency measured by a chromogenic substrate or a two-stage clotting assay, in interactions with thrombin, and with activated protein C (APC) in combination with Protein S. The ability of r-VIII SQ to participate as a cofactor in factor Xa generation in a mixture of factors IXa and X, phospholipid and calcium was in conformity with that of p-VIII. Furthermore r-VIII SQ had a good binding capacity for phospholipid vesicles and von Willebrand factor (vWF) as shown in gel filtration studies. The same kinetics in binding to von Willebrand factor was found for r-VIII SQ and p-VIII as determined by real-time biospecific interaction analysis (BIA) with use of the BIAcore instrument. The apparent association rate constant was 4 x 10(6) M(-1)s(-1). Two dissociation rate constants were found, 1 X 10(-2)s(-1) and 4 x 10(-4)s(-1). The results extend the present knowledge that the factor VIII B-domain is dispensable for the factor VIII cofactor function in hemostasis.

Binding Sites↗
PubMed2000

The United Kingdom Children's Cancer Study Group's second germ cell tumor study: carboplatin, etoposide, and bleomycin are effective treatment for children with malignant extracranial germ cell tumors, with acceptable toxicity.

PURPOSE: To evaluate carboplatin, etoposide, and bleomycin (JEB) in children with malignant extracranial germ cell tumors (GCTs). PATIENTS AND METHODS: Malignant GCTs in children aged 0 to 16 years were excised without major morbidity or otherwise biopsied. Stage I testicular and some ovarian GCTs were resected and monitored with alpha-fetoprotein (AFP) ("watch-and-wait" approach). Patients with recurrent stage I disease and all other patients received JEB (etoposide 120 mg/m(2) on days 1 through 3, carboplatin 600 mg/m(2) on day 2, and bleomycin 15 mg/m(2) on day 3). Courses were administered every 3 to 4 weeks until remission, and then two more courses were given. Chemotherapy toxicities were assessed using World Health Organization or Brock grading. RESULTS: Between January 1989 and December 1997, 192 patients were registered. Eight were excluded because either there was no histologic diagnosis (n = 3) or chemotherapy was given off-study (n = 5). The remaining 184 patients had germinoma (n = 20), malignant teratoma (n = 55), embryonal carcinoma (n = 1), yolk sac tumor (n = 107), or choriocarcinoma (n = 1). Forty-seven patients were treated with surgery alone, and 137 patients received JEB. The 5-year survival rate in March 1999 for all 184 patients was 93.2% (95% confidence interval [CI], 87.9% to 96.3%); for the 137 JEB-treated patients, it was 90.9% (95% CI, 83.9% to 95.0%), with an event-free survival rate of 87.8% (95% CI, 81.1% to 92.4%). The median follow-up after JEB treatment was 53 months (range, 0 to 109 months); the median number of courses was five (range, three to eight). Site, stage, and AFP level had prognostic significance. Nonfatal hematologic toxicity was common, but deafness and pulmonary and renal toxicities were rare. One child died of a thoracic tumor and bronchopulmonary dysplasia, and another died of acute myeloid leukemia. CONCLUSION: Conservative surgery, a watch-and-wait approach after complete excision, and JEB for those requiring chemotherapy produced high cure rates and few serious complications.

Adolescent↗
PubMed2000

Chronic liver allograft rejection in a population treated primarily with tacrolimus as baseline immunosuppression: long-term follow-up and evaluation of features for histopathological staging.

BACKGROUND: Predisposing factors, long-term occurrence, and histopathological changes associated with recovery or progression to allograft failure from chronic rejection (CR) were studied in adult patients treated primarily with tacrolimus. METHODS: CR cases were identified using stringent criteria applied to a retrospective review of computerized clinicopathological data and slides. RESULTS: After 1973 days median follow-up, 35 (3.3%) of 1049 primary liver allograft recipients first developed CR between 16 and 2532 (median 242) days. The most significant risk factors for CR were the number (P<0.001) and histological severity (P<0.005) of acute rejection episodes and donor age >40 years (P<0.03). Other demographic and matching parameters were not associated with CR in this cohort. Ten patients died with, but not of, CR. Eight required retransplantation because of CR at a median of 268 days. Ten resolved either histologically or by normalization of liver injury tests over a median of 548 days. CR persisted for 340 to 2116 days in the remaining seven patients. More extensive bile duct loss (P<0.01), smallarterial loss (P<0.03), foam cell clusters (P<0.01) and higher total bilirubin (P<0.02) and aspartate aminotransferase (P<0.03) were associated with allograft failure from CR. CONCLUSIONS: Early chronic liver allograft rejection is potentially reversible and a combination of histological, clinical, and laboratory data can be used to stage CR. Unique immunological and regenerative properties of liver allografts, which lead to a low incidence and reversibility of early CR, can provide insights into transplantation biology.

Adolescent↗
PubMed2000

Structure/function studies of anticoagulant sulphated polysaccharides using NMR.

Sulphated polysaccharides have many biological functions, which depend on binding of highly specific carbohydrate structures to proteins. NMR spectroscopy is a technique capable of detailed structural elucidation of these polysaccharides, and can be used in applications ranging from routine analysis to research into covalent and conformational aspects of polysaccharide structure. This technique can be used to characterise sequence variations in heparin samples. The NMR-determined solution conformation of heparin has been used to predict binding sites on the surface of heparin-binding proteins. Sulphation patterns for dermatan sulphates of marine invertebrates have been determined. Their anticoagulant effects depend on an exact pattern of sulphate substitution. A small alteration in dermatan sulphate structure, from 4-O-sulphated to 6-O-sulphated galactosamine, leads to almost complete loss of anticoagulant activity in spite of an overall high level of sulphation. A fucosylated chondroitin sulphate isolated from sea cucumber has anticoagulant and antithrombotic activity depending on its sulphated fucose branches. The anticoagulant activity of algal fucans has been compared with that of regular, linear sulphated fucans from marine echinoderms; again high activity appears to correlate with the presence of sulphated fucose branches.

Animals↗
PubMed2000

Empirical analysis of the selective attention and associated behavior checklists of the Aggregate neurobehavioral student health and educational review.

For 111 referred children, the Behavior Observation (BO) and the Selective Attention (SA) components of the Aggregate Neurobehavioral Student Health and Educational Review (ANSER) were completed by mothers and teachers and the Pediatric Examination of Educational Readiness at Middle Childhood was completed by the pediatrician. Smaller samples were used to study concurrent validity. The questionnaires presented high internal reliability. Factor analyses of the BO questionnaires resulted in a common primary factor of "Aggressiveness" for ratings by mothers and teachers. For the SA, "Hyperactivity" (mothers) and "Inattention" (teachers) accounted for the majority of variance. There were modest correlations between teachers and mothers. The correlation between the pediatrician and teachers reached the highest value. The BO-Teachers form was significantly related to the Teacher Report Form and the Conners Teacher Rating Scale. The authors concluded that the ANSER presents concurrent validity for teacher ratings, items predictive of atypical behavior, and a unique pool for defining a subgroup of children with attentional disorders. The limited relationship between mothers and teachers may be ascribed to different interpretations of the same items.

Attention Deficit Disorder with Hyperactivity↗