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Biomedical subjects

S Murphy

Publications and source records attributed to S Murphy.

At least 127 records · Page 7Linked to original sources
PubMed1998

A multi-laboratory evaluation of in vitro platelet assays: the tests for extent of shape change and response to hypotonic shock. Biomedical Excellence for Safer Transfusion Working Party of the International Society of Blood Transfusion.

BACKGROUND: There is no consensus regarding the use of specific in vitro tests for the assessment of the quality of platelet components. A literature review found that the platelet discoid shape as measured photometrically by the extent of shape change (ESC) and hypotonic shock response (HSR) correlated well with in vivo viability. The purpose of this study was to determine whether multiple research laboratories can perform the ESC and HSR assays in an accurate, reproducible manner, with acceptable sensitivity and comparable results. STUDY DESIGN AND METHODS: Eleven laboratories conducted five identical experiments, each with a different unit of platelet-rich plasma (PRP). For each experiment, 2 half-units of PRP were prepared and stored overnight: 1 half-unit at 20 to 24 degrees C in CPD (CPD-PRP) and the other at 1 to 6 degrees C with 2 mg per mL of EDTA (cold EDTA-PRP) added to produce spherical platelets with reduced HSR. Platelet suspensions having different proportions of the two PRPs were prepared and evaluated in duplicate by ESC and HSR assays, and morphologically scored by microscopy. One-way ANOVA and Duncan multiple-range tests were performed to determine significant differences in assay results for suspensions having different proportions of CPD-PRP. RESULTS: Comparable ESC (mean range: 20-28% for CPD-PRP and 1-6% for cold EDTA-PRP) and HSR (mean range: 58-81% for CPD-PRP and 12-31% for cold EDTA-PRP) measurements were obtained by nine laboratories. Duplicate testing showed high reproducibility of ESR and HSR results /in all laboratories. A 25-percent difference in the proportion of CPD-PRP (indicative of a difference of approximately 25% in the proportions of discoid and spherical platelets) was detected with a sample size of five (p<0.05) for both the ESC and HSR assays. A high correlation was found for the ESC assay and morphology score (r = 0.93, n = 345). CONCLUSION: Multiple laboratories were able to obtain comparable results with the ESC and HSR tests. They were able to show that the tests can be performed in an accurate, reproducible manner and with acceptable sensitivity.

Blood Platelets↗
PubMed1998

Evaluation of the Amicus Separator in the collection of apheresis platelets.

BACKGROUND: A new apheresis instrument, the Amicus Separator with software versions 2.13 and 2.34, was evaluated for component yields, collection efficiency, and incidence of donor and transfusion recipient reactions. The Amicus was also compared to the Spectra Leukocyte Reduction System (LRS) with version 5 software. STUDY DESIGN AND METHODS: Single and double apheresis platelets (APs) were collected at two locations. The targeted platelet yields were 4.0 x 10(11) for single APs and 6.8 x 10(11) for double APs. One location used a double-needle procedure, and the other used a single-needle procedure. Along with 28 of the Amicus procedures (14 at each of two locations), the same donors underwent single or double AP collections on the Spectra LRS. APs were tested for platelet yields and residual white cells. APs were transfused in three hospitals. Donor and transfusion recipient reactions and technical problems were documented. RESULTS: The Amicus Separator efficiently collected single APs (n = 59) and double APs (n = 62) with mean platelet yields of 4.2 x 10(11) and 6.5 x 10(11), respectively. When inlet line alarms occurred in single-needle procedures, platelet yields were lower and collection times were longer. All APs were white cell-reduced below 5.0 x 10(6), and all but one AP were white cell-reduced below 1.0 x 10(6) without filtration. Component yields from the paired Amicus and Spectra LRS procedures were comparable. Collection times (excluding reinfusion/rinseback) were 20 to 23 minutes faster on the Amicus Separator. No serious donor or transfusion recipient reactions occurred. CONCLUSION: The Amicus Separator provided satisfactory platelet yields and collection efficiency, with shorter collection times than did the Spectra LRS, and it white cell-reduced components without filtration.

Blood Donors↗
PubMed1998

High incidence of the Cys 282 Tyr mutation in the HFE gene in the Irish population--implications for haemochromatosis.

A simple PCR-SSOP approach based on a single PCR product has been developed to screen the HFE gene for the haemochromatosis-associated mutations Cys 282 Tyr and His 63 Asp. Using this approach the prevalence of these mutations in a cohort (30) of haemochromatosis patients and normal controls (404) was determined. Ninety percent of the haemochromatosis patients were homozygous for the Cys 282 Tyr mutation. In the normal population we found an increased incidence of the Cys 282 Tyr mutation (17.3%; 95% confidence limits 0.136-0.209) which was also reflected in the higher frequency of Cys 282 Tyr homozygotes (1.24%; 95% confidence limits 0.0016-0.0232). Linkage disequilibrium analysis confirmed the association between A*03 and Cys 282 Tyr. However, strong linkage disequilibrium occurred with the HLA-A*03-associated allele HLA-B*14 but not the HLA-A*03-associated allele HLA-B*07. The His 63 Asp was found to be in linkage disequilibrium with HLA-A*29.

Cysteine↗
PubMed1998

Does new technology increase or decrease health care costs? The treatment of peptic ulceration.

OBJECTIVES: To determine whether new technology increases or decreases formal health care costs, with reference to the diagnosis and treatment of peptic ulcers. METHODS: A costing method has been devised which is designed to investigate directly the way in which the costs to formal health services of diagnosing and treating an individual illness have changed with changes in technology. RESULTS: The cost of diagnosis has increased almost entirely as a result of the high cost of endoscopy compared with X-ray examination. The introduction of H2-receptor antagonist drugs increased the cost of treatment compared with the earlier phases of surgical treatment. Subsequently, Helicobacter pylori eradication treatment has reduced the cost of treatment compared with all earlier phases of technology. CONCLUSIONS: A method has been devised that allows the impact of changes in medical technology on formal health care costs to be investigated for individual illnesses. In the treatment of peptic ulceration, the current technology, H. pylori eradication, has lower treatment costs than all previous technologies. The evidence from previous studies and this study is insufficient to support the assertion that new technology in general leads either to an increase or to a decrease in health care costs.

Anti-Infective Agents↗
PubMed1998

Sexually transmitted disease rates before and after HIV testing.

The aim of the study was to evaluate the effect of having an HIV-positive or negative test result on sexual risk behaviour before and after the test. Longitudinal retrospective case-note survey identifying new episodes of sexually transmitted disease (STD) infections in 114 subjects testing HIV positive and 114 matched negatives were examined at the Genitourinary Medicine Department, St Mary's Hospital, Paddington, London. Across the whole sample in the year after HIV testing the number of cases of new STD infections was 40% of the number of cases in the year prior to HIV testing. There was no association between serostatus and incidence of STD infections before and after HIV testing. Of those testing negative, 5.3% were identified as having a new infection in the year after the HIV test, while amongst those testing positive there was a rate of new STDs of 2.6%. In conclusion, there was no evidence that having a negative test result increased the risk of acquisition of new STDs. Rates of new STD infections amongst seropositives in the year after HIV testing were low.

Adult↗
PubMed1998

Complement-binding anti-Jka not detectable by DiaMed gels.

BACKGROUND: An anti-Jka was not detectable by the DiaMed-ID Micro Typing System but was strongly reactive when tested using other indirect antiglobulin test (IAT) methods. However, it was detectable in the DiaMed-ID system when the recommended diluent ID-Diluent 2, was replaced by other low ionic Strength saline (LISS) solutions. This led us to believe that the problem lay with the ID-Diluent 2. METHODS: The anti-Jka was investigated using various low ionic strength diluents in the IAT against both polyspecific and monospecific antiglobulin reagents. We tested the ID-Diluent 2 for its ability to inhibit complement activation, and bind calcium. RESULTS: The anti-Jka was shown to be a 'complement-only' binding antibody that reacted in all IATs performed except when tested with ID-Diluent 2. The ID-Diluent was shown to prevent haemolysis of ABO lytic antibodies, and further testing shows that it binds calcium. CONCLUSION: The use of a diluent which prevents haemolysis and binds calcium in an IAT system that contains anti-complement as well as anti-IgG must be questioned.

Aged↗
PubMed1998

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Colonialism↗
PubMed1997

Differential in vivo activation of the class II and class III snRNA genes by the POU-specific domain of Oct-1.

Many snRNA genes contain binding sites for the ubiquitous transcription factor Oct-1. In vitro studies have shown that this factor potentiates binding of an essential transcription factor (PTF) to the proximal sequence element (PSE) of snRNA genes, and activates transcription. Using Gal4 fusion proteins, I show here that the POU-specific region of the DNA-binding domain of Oct-1 is sufficient both to potentiate PTF binding in vitro and to transactivate pol II- and pol III-dependent snRNA genes in vivo . A single amino acid change in this domain abrogates both activation and interaction with PTF. The N- and C-terminal regions of Oct-1 also activate transcription of both classes of snRNA genes. Wild-type levels of Pol II-dependent U2 expression require all activation domains, whereas efficient activation of the pol III-dependent 7SK and U6 genes is effected by the POU-specific domain alone. These results indicate that contacts between PTF and amino acids in the POU-specific domain of Oct-1 are critical for efficient transactivation of snRNA genes in vivo. The POU-specific domain of Oct-2A also activates these genes, but the N- and C-terminal domains are relatively inactive.

Binding Sites↗
PubMed1997

HIV-induced T cell syncytia are self-perpetuating and the primary cause of T cell death in culture.

Prior studies suggested that induced fusion in T cell cultures infected with syncytium-inducing HIV was not the primary cause of T cell death. However, these studies failed to assess the contribution of fusion in terms of syncytium volume, rather than syncytium frequency. This question has been reassessed by monitoring the frequency, volume, rate of growth, longevity, p24 production, viral budding, and self-propagating ability of syncytia in HIV-infected SUP-T1 cell cultures and individually isolated syncytia seeded in uninfected SUP-T1 cell cultures. The results demonstrate that in these cultures syncytium formation is the principal mechanism of T cell death, syncytia are the main source of virus production, and both virus production and syncytium longevity are independent of syncytium size, but dependent on syncytium age, suggesting that both are programmed events.

Cell Death↗
PubMed1997

Megakaryocytic progenitors can be generated ex vivo and safely administered to autologous peripheral blood progenitor cell transplant recipients.

We evaluated different culture conditions to obtain a lineage-selected proliferation of clonogenic megakaryocytic progenitors (MP). In low-density (LD) or CD34+ cell cultures, the best results were obtained in serum-free medium in the presence of megakaryocyte growth and development factor, stem cell factor, interleukin-3 (IL-3), IL-6, IL-11, FLT-ligand, and macrophage inflammatory protein-1alpha. In paired studies, expansion of LD cells was less effective than expansion of CD34+ cells, and pre-enrichment of CD34+ cells using negative depletion of lineage-positive cells produced significantly larger quantities of MP than pre-enrichment using positive selection. MP proliferation peaked on day 7 in culture, and an 8- +/- 5-fold expansion of CD34+/CD61+ cells, a 17- +/- 5-fold expansion of colony-forming units-megakaryocytes, and a 58- +/- 14-fold expansion of the total number of CD61+ cells was obtained. In a feasibility clinical study, 10 cancer patients (8 with breast cancer and 2 with non-Hodgkin's lymphoma) undergoing autologous peripheral blood progenitor cell (PBPC) transplant received MP generated ex vivo (range, 1 to 21 x 10(5)/kg CD61 cells) together with unmanipulated PBPC. Eight patients received a single allogeneic platelet transfusion, whereas platelet transfusion support was not needed in 2 of the 4 patients receiving the highest doses of cultured MP. This result compares favorably with a retrospective control group of 14 patients, all requiring platelet transfusion support. Adverse reactions or bacterial contamination of cell cultures have not been observed. In conclusion, MP can be expanded ex vivo and safely administered to autologous transplant recipients. Further clinical trials will indicate the reinfusion schedule able to consistently abrogate the need for allogeneic platelet transfusion support in autologous transplantation.

Cells, Cultured↗
PubMed1997

Nitric oxide regulates nitric oxide synthase-2 gene expression by inhibiting NF-kappaB binding to DNA.

Treatment of astroglial cells with interleukin 1beta and interferon gamma transcriptionally activates the nitric oxide synthase (NOS)-2 gene. The duration of mRNA expression is brief because of transcript instability. In addition, NO donors reduce the expression of NOS-2 mRNA dramatically by reducing the rate of transcription. In this study we observed that the NO donor, spermine NONOate did not inhibit the activation and translocation of NF-kappaB, a key transcription factor in the induction of NOS-2, but inhibited formation of the NF-kappaB-DNA complex. This effect was reversed by methaemoglobin (acting as an NO trap) and by the reducing agent dithiothreitol. Formation of the interferon-regulatory factor-DNA complex was unaffected by NO. These results suggest that NO can modulate its own production by interfering with NF-kappaB interaction with the promoter region of the NOS gene, a negative feedback effect that may be important for limiting NO production in vivo.

Animals↗
PubMed1997

Serum erythropoietin levels in children with leukemia.

OBJECTIVE: Our aim was to test the hypothesis that, in leukemic children, serum erythropoietin (EPO) levels vary inversely with hemoglobin. DESIGN: Twenty-four children (15 males, nine females) with an age range of 1-16 years (mean, 7.7 years) diagnosed with acute leukemia (22 acute lymphocytic, two acute myeloid) were studied over 4 months. Serum EPO and hemoglobin were measured simultaneously at multiple time points in the course of their disease, and a multiple regression analysis was performed to describe the EPO-hemoglobin relationship. RESULTS: In a model adjusted for individual subject, there was a significant correlation between hemoglobin and logEPO in these leukemic children (r = -0.55, P < .01, n = 100). When measurements at hemoglobins less than 10.0 were analyzed the correlation increased significantly (r = -0.88, P < .01, n = 21). However, approximately 20% of the observations fell into one of two groups: an inappropriately low EPO for hemoglobin or an inappropriately elevated EPO for hemoglobin. The clinical characteristics of the children at each of these determinations were not different in any manner from the determinations which fell within the 95% confidence intervals for predicted mean EPO value: each of the outlying points came from a patient who at other times had an appropriate EPO for hemoglobin. CONCLUSIONS: There existed a significant inverse relationship between hemoglobin and EPO, suggesting that the feedback mechanism for EPO is intact. Reasons for inappropriately high or low EPO, for level of hemoglobin, are not clear and may be reflective of other aspects of bone marrow or EPO metabolism.

Acute Disease↗
PubMed1997

Activated astrocytes induce nitric oxide synthase-2 in cerebral endothelium via tumor necrosis factor alpha.

Astrocytes under pathological conditions become activated and produce a variety of cytokines and low molecular weight signal molecules. Previously we demonstrated that activated astrocytes release nitric oxide which can downregulate the expression of nitric oxide synthase (NOS)-2 in co-cultured cerebral endothelium, and also release a transcriptionally regulated factor that can induce NOS-2 expression in endothelium (Borgerding and Murphy: J Neurochem 65:1342, 1995). The activity of this NOS-2-inducing factor was impeded by inhibitors of tyrosine kinases and NF-kappaB activation. Tumor necrosis factor (TNF alpha) alone, or in combination with IL-6, induced NOS-2 expression in endothelial cells. A neutralizing antibody against TNF alpha attenuated the NOS-2 expression in endothelial cells exposed to activated astrocytes. These results imply that cytokine-activated astrocytes release TNF alpha which can induce NOS-2 expression in endothelium and suggest that activated astrocytes within the CNS may induce expression of NOS-2 in cells of the adjacent microvasculature. The ensuing alterations in blood-brain barrier properties may be either beneficial or detrimental.

Animals↗