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David J Perry

Publications and source records attributed to David J Perry.

12 recordsLinked to original sources
PubMed2004

Distinguishing modes of cell death using the ImageStream multispectral imaging flow cytometer.

BACKGROUND: Here we demonstrate the ability of the ImageStream 100 Multispectral Imaging Cytometer to discriminate between live, necrotic, and early and late apoptotic cells, using unique combinations of photometric and morphometric features. METHODS: Live, necrotic, and early and late apoptotic cells were prepared and analyzed by immunofluorescence microscopy, conventional flow cytometry, and imaging flow cytometry, both as single populations and as a heterogeneous mixture of cells. RESULTS: Live (annexin V(-), 7-AAD(-)) and early apoptotic (annexin V(+), 7-AAD(-)) cells were readily identifiable using either conventional or ImageStream based flow cytometric methods. However, inspection of multispectral images of cells demonstrated that the annexin V(+), 7-AAD(+) population contained both necrotic and late-stage apoptotic cells. Although these cells could not be distinguished using conventional flow cytometric techniques, they were separable using unique combinations of photometric and morphometric measures available using ImageStream technologies. CONCLUSIONS: Using multispectral imagery, morphologically distinct cell populations can be distinguished using features not available with conventional flow cytometers. In particular, the ability to couple morphometric with photometric measures makes it possible to distinguish live cells from cells in the early phases of apoptosis, as well as late apoptotic cells from necrotic cells.

Cell Death↗
PubMed2004

Role of the Thrombelastograph as an adjunctive test in thrombophilia screening.

The Thrombelastograph (TEG) provides a global assessment of haemostatic function. We have investigated the potential role of TEG in thrombophilia testing by studying 87 consecutive patients (all with personal or family history of thrombosis). For each patient, routine thrombophilia screening tests and TEG were performed in parallel. In keeping with previous reports, at least one thrombophilic trait was identified in 34% of the patients. Among those patients with previous thrombosis, the yield from screening was higher (54% with prothrombotic trait). Overall, a hypercoaguable TEG was demonstrated in 45% of patients. However, TEG and standard thrombophilia testing did not necessarily identify the same subset of individuals. Of 39 patients with hypercoaguable TEG, only 17 had a demonstrable thrombophilic trait. Conversely, of 30 patients with proven thrombophilia, 17 also had a hypercoaguable TEG. We conclude that TEG cannot be used as a sole initial screening test in patients referred for thrombophilia testing, as it fails to identify 43% of underlying thrombophilic traits. However, TEG may be a useful adjunctive test, particularly in patients in whom the regular thrombophilia screen proves unremarkable. Prospective studies are warranted to determine whether a hypercoaguable TEG can be used to predict a subset of patients at increased risk for recurrent thrombotic events.

Adolescent↗
PubMed2003

Veno-occlusive disease: cytokines, genetics, and haemostasis.

Hepatic veno-occlusive disease (VOD) is a major cause of morbidity and mortality following high dose cytotoxic therapy for stem cell transplantation (SCT). Pre-existing liver damage, SCT-related therapy, and genetic polymorphisms all appear to increase the risk of developing VOD. Studies of biological markers during SCT suggest that cytokines, haemostasis, and hepatic drug metabolism via the glutathione pathway are all involved in the pathogenesis of VOD. Until recently, treatment options were limited and experimental therapies directed at the pathogenesis of the disease were mostly unsuccessful. However, Defibrotide, a relatively new agent that has modulatory effects on vascular endothelium, cytokine release, and haemostasis, has been used with some success in the management and prophylaxis of VOD. In the future, a better understanding of genetic polymorphisms and biological markers which may be important in the pathogenesis of VOD, may enable us to predict which patients are most likely to be affected.

Animals↗
PubMed2003

Recombinant FVIIa in the management of uncontrolled hemorrhage.

BACKGROUND: Recombinant FVIIa (rFVIIa/NovoSeven) is a novel hemostatic agent originally developed to treat patients with hemophilia who had developed inhibitors. Several case reports have suggested that rFVIIa may be effective in treating patients without a pre-existing bleeding disorder who have uncontrolled bleeding. STUDY DESIGN AND METHODS: Data on the efficacy and safety of rFVIIa in the treatment of massive hemorrhage were obtained retrospectively from the NovoSeven extended-use data collection system. RESULTS: A total of 40 patients received rFVIIa for uncontrolled bleeding, and in these patients, bleeding stopped or decreased in 32 (80%). Blood product usage was significantly decreased after rFVIIa administration. Thromboembolic events occurred in three patients with additional risk factors for thrombosis. Of 40 patients, 23 (57.5%) died. Bleeding was the direct cause of death in seven cases (all within 24 hr of administration of rFVIIa). The remaining 16 deaths were the result of sepsis, multi-organ failure, or the underlying disease. CONCLUSIONS: In this retrospective study of data voluntarily submitted to a web-based drug surveillance program, we present preliminary results on the use of rFVIIa in nonhemophilia patients with bleeding. Although some efficacy is suggested, there was a high mortality rate from nonhemorrhagic causes. Randomized controlled trials are needed to properly assess the role of rFVIIa in the management of hemorrhage.

Adult↗
PubMed2003

Analysis and results of the recombinant factor VIIa extended-use registry.

This paper describes the analysis of recombinant factor VIIa (rFVIIa; NovoSeven; Novo Nordisk, Bagsvaerd, Denmark) use in 40 patients with intractable bleeding in the UK. All cases were reported on the 'rFVIIa extended use database' (Traumanet) between its launch in February 1999 and 12 March 2002. Twenty-one other cases reporting rFVIIa use in different circumstances were excluded from the analysis. Recombinant FVIIa was effective in stopping or markedly reducing blood loss in 80% of patients; 20% of patients did not respond to treatment. Non-responders tended to have more deranged coagulation and lower platelet counts compared with responders. Despite a wide range of underlying illnesses, including malignancy and sepsis, few patients suffered adverse events. Thrombotic events occurred in three of 40 (7.5%) patients and these patients were considered as already at risk of thrombosis from other causes. The data suggest that rFVIIa is safe and effective therapy in patients with uncontrollable haemorrhage.

Adult↗
PubMed2003

Factor VII deficiency.

As yet, there have been neither systematic reviews nor reports of randomized, controlled trials involving factor VII (FVII) deficiency. Hence, a picture of this disorder can only be drawn by reviewing and summarizing the data that is available. This article provides an overview of the understanding of this rare, inherited disorder of coagulation. In particular, the status of current knowledge of the disorder's prevalence, clinical presentation, diagnostic characteristics and molecular genetics is reviewed, followed by a summary of currently available options for its treatment and management.

Blood Coagulation Factors↗
PubMed2002

Simple shifts in redox/thiol balance that perturb blood coagulation.

The biological chemistry that underlies and regulates the blood coagulation cascade is not fully understood. To begin to understand this, we performed clotting assays under various redox conditions. By varying the amount of oxidant and/or antioxidant in these assays, we observed that both the intrinsic/tenase complex and the extrinsic pathways were susceptible to shifts in the thiol/redox balance. We established a dichotomy where blood clotting via the intrinsic pathway was sensitive to oxidation whereas the tissue factor or extrinsic pathway was more sensitive to reduction. These differential inhibitory effects present a conceptual mechanism for selective modulation of the activities of clotting factors specific for the respective pathways. These data also suggest that blood clotting may be influenced by unidentified redox or thiol equilibria.

Blood Coagulation↗
PubMed2002

Immediate reconstruction after mastectomy for breast cancer does not prolong the time to starting adjuvant chemotherapy.

BACKGROUND: Immediate breast reconstruction is often performed after mastectomy for breast cancer. There has been concern that this will result in a delay in initiating chemotherapy and, as a consequence, may adversely impact survival. In this study we sought to determine whether immediate breast reconstruction affects the interval between surgery and adjuvant chemotherapy. METHODS: A single institution retrospective analysis was made using the institutional tumor registry and chart reviews. RESULTS: Forty-nine patients were identified who had undergone mastectomy with immediate reconstruction followed by adjuvant chemotherapy. They were compared with 308 patients undergoing mastectomy without reconstruction. Patients who underwent reconstruction were overall younger (46 versus 55, P <0.001), and had more advanced disease. The time to chemotherapy was significantly longer in the group receiving no reconstruction: 53 versus 41 days (P = 0.039). The type of reconstruction did not affect the time to chemotherapy. CONCLUSIONS: Immediate reconstruction after mastectomy does not increase the time to chemotherapy compared with mastectomy alone.

Abdominal Muscles↗
PubMed2002

Gene mutations and three-dimensional structural analysis in 13 families with severe factor X deficiency.

Factor X (FX) deficiency is a rare autosomal recessive disorder. The phenotype and genotype of 15 Iranian patients with FX deficiency from 13 unrelated families with a high frequency of consanguinity were analysed. Five different assays identified four patients from three families with a discrepancy between low-FX coagulant activity (FX:C) and higher-FX antigen (FX:Ag) (a type II deficiency). The remaining 11 patients had parallel reductions of FX:C and FX:Ag (a type I deficiency). Nine different homozygous candidate mutations were identified, of which eight were novel. The four type II cases were associated with an Arg(-1)Thr missense mutation in the prepropeptide: Arg(-1) is highly conserved in all vitamin K-dependent proteins. Four type I mutations (Gly78Asp, Cys81Tyr, Gly94Arg and Asp95Glu) were localized to the EGF-1 and EGF-2 domains, for which molecular views showed that the protein folding would be disrupted. The type I mutation Gly222Asp was localized in the catalytic domain of FX, and is sufficiently close to the Asp-His-Ser catalytic triad to disrupt its correct protein folding. The two type I splice site mutations were IVS1+3, A-->T and IVS2-3, T-->G. These novel homozygous FX mutations were consistent with their phenotypes and agree with experimental data from knockout mice, indicating that FX is an essential protein for survival.

Adolescent↗
PubMed2002

Factor X deficiency.

Factor X is one of the vitamin K-dependent serine proteases. It plays a crucial role in the coagulation cascade, as the first enzyme in the common pathway of thrombus formation. The gene for factor X maps to the long arm of chromosome 13, approximately 2.8 kb downstream of the factor VII gene. The gene consists of eight exons, each of which encodes a specific functional domain within the protein. Both the gene structure and the amino acid sequence show homology to other vitamin K-dependent clotting factors, suggesting their origin in a common ancestral protein. Factor X deficiency is one of the rarest of the inherited coagulation disorders. Inheritance is in an autosomal recessive manner. The clinical phenotype is of a variable bleeding tendency. Homozygous factor X deficiency has an incidence of 1:1,000,000 in the general population. Heterozygotes are often clinically asymptomatic. Acquired factor X deficiency is rare, but when it occurs it is usually in association with amyloidosis. Treatment of factor X deficiency involves replacement of the protein with either fresh frozen plasma or prothrombin complex concentrates, although the latter should be used with caution as infusion may be associated with an increased risk of thrombosis.

Amyloidosis↗
PubMed2002

Pharmacotherapy of hyperhomocysteinaemia in patients with thrombophilia.

Hyperhomocysteinaemia is often the result of inherited abnormalities of the enzymes involved in homocysteine metabolism or vitamin deficiencies (vitamins B12, B6 or folate) and is present in approximately 5% of the general population. High homocysteine levels in these individuals are associated with a significant increase in relative risk for both arterial and venous thromboembolic disease. Consequently, effective homocysteine-lowering therapeutic strategies have been extensively investigated. Folic acid represents the cornerstone of treatment. In daily doses of at least 0.4 mg, it effectively reduces homocysteine levels, even in non-folate-deficient patients. The addition of vitamins B12 and/or B6, to folic acid supplementation may provide a small further reduction in homocysteine levels in certain groups of patients. Renal impairment is an important cause of hyperhomocysteinaemia. Individuals with hyperhomocysteinaemia secondary to renal disease commonly require significantly higher doses of folic acid (5-40 mg) to achieve maximal therapeutic effect. The important question of whether effective homocysteine-lowering therapy translates into a reduction in vascular disease remains unknown but is being addressed in a series of ongoing prospective trials.

Folic Acid↗