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Biomedical subjects

C Pickard

Publications and source records attributed to C Pickard.

16 recordsLinked to original sources
PubMed2003

Diagnostic role of tests for T cell receptor (TCR) genes.

Rapid advances in molecular biological techniques have made it possible to study disease pathogenesis at a genomic level. T cell receptor (TCR) gene rearrangement is an important event in T cell ontogeny that enables T cells to recognise antigens specifically, and any dysregulation in this complex yet highly regulated process may result in disease. Using techniques such as Southern blot hybridisation, polymerase chain reaction, and flow cytometry it has been possible to characterise T cell proliferations in malignancy and in diseases where T cells have been implicated in the pathogenesis. The main aim of this article is to discuss briefly the process of TCR gene rearrangement and highlight the disorders in which expansions or clonal proliferations of T cells have been recognised. It will also describe various methods that are currently used to study T cell populations in body fluids and tissue, their diagnostic role, and current limitations of the methodology.

Blotting, Southern↗
PubMed2002

TCR usage and cytokine expression in peripheral blood and BAL T cells.

T cells are thought to play an important regulatory role in atopic asthma. We hypothesized that human blood and BAL T cell subsets bearing various TCR-Vbeta genes might show selective differences in their cytokine profile. Peripheral blood (PB) and bronchoalveolar lavage (BAL) T cells from seven atopic asthmatic and six non-atopic non-asthmatic subjects were stimulated with PMA and ionomycin in the presence of monensin and analysed for TCR-Vbeta expression and production of cytokines at the single cell level. The percentage of IFN-gamma- and IL-2-producing BAL T cells was elevated compared with PB T cells from both the asthmatic subjects and the non-atopic, non-asthmatic controls. A small percentage of PB and BAL T cells produced IL-4 and IL-5, in asthmatic and normal subjects. In peripheral blood, the percentage of T cells expressing each cytokine was similar in the various TCR-Vbeta subsets and in total CD3+ T cells in all normal and six of seven asthmatic subjects. However, there was a substantial degree of heterogeneity in the cytokine profile of BAL TCR-Vbeta subsets compared with the total CD3+ T cells. This was more obvious in the asthmatic subjects with a reduction in the percentage of IFN-gamma- and IL-2-expressing T cells (five of seven asthmatic subjects) and an increase in the percentage of IL-4- and IL-5-expressing T cells (two of seven asthmatic subjects). These data confirm previous findings of an elevated proportion of IFN-gamma- and IL-2-producing BAL T cells while only a small proportion of PB and BAL T cells produce IL-4 and IL-5. Moreover, subsets of BAL T cells, defined by their TCR-Vbeta usage, may differ in their cytokine profile compared with the total CD3+ T cells, implying that T cells expressing different Vbeta elements may play different roles in regulating the airway inflammation in asthma.

Asthma↗
PubMed2002

Simultaneous analysis of T cell clonality and cytokine production in rheumatoid arthritis using three-colour flow cytometry.

In this study we examined the cytokine production by T cells and TCRVbeta subsets in peripheral blood (PB) and synovial fluid (SF) from six RA patients and PB from 10 normal subjects, using three-colour flow cytometry. In two RA subjects we assessed T cell clonality by RT PCR using TCRBV family-specific primers and analysed the CDR3 (complementarity determining region 3) length by GeneScan analysis. A high percentage of IFN-gamma- and IL-2- producing cells was observed among the PB T cells in both the RA patients and normal controls and among the SF T cells in RA patients. In contrast, the percentage of T cells producing IL-4 and IL-5 was small among PB T cells in both RA patients and normal controls and among SF T cells in RA patients. There was no significant difference in the production of IFN-gamma, IL-2 and IL-5 between the two compartments (PB and SF); however, there were significantly more IL-4-producing cells in SF. Molecular analysis revealed clonal expansions of four TCRBV families in SF of two of the RA patients studied: TCRBV6.7, TCRBV13.1 and TCRBV22 in one and TCRBV6.7, TCRBV21.3 and TCRBV22 in the second. These expansions demonstrated cytokine expression profiles that differed from total CD3+ cells, implying that T cell subsets bearing various TCR-Vbeta families may have the potential to modulate the immune response in RA patients.

Adult↗
PubMed2000

Transfusion to blood group A and O patients of group B RBCs that have been enzymatically converted to group O.

BACKGROUND: The transfusion of ABO-incompatible RBCs is the leading cause of fatal transfusion reactions. Group O RBCs, lacking terminal immunodominant A and B sugars to which humans are immunized, are safe for transfusion to persons of any ABO blood group. With the use of a recombinant alpha-galactosidase to remove terminal galactose from group B RBCs, the safety and efficacy of enzyme-converted group-B-to-group-O (ECO) RBC components were studied in transfusion-dependent patients. STUDY DESIGN AND METHODS: Twenty-four patients (blood groups A and O) were randomly assigned to receive transfusion(s) of either ECO or control group O RBCs. If a second transfusion was given, the other blood component was administered. RESULTS: Twenty-one patients were given ECO RBCs; 18 also underwent control transfusions. One patient received only a small aliquot for RBC survival studies, instead of a full-unit transfusion, because his serum was incompatible with ECO RBCs. No adverse events occurred. Both ECO and control transfusions resulted in appropriate Hb increments and comparable (51)Cr-labeled RBC survival studies. One patient developed a transient, weak-positive DAT, without hemolysis. Two weeks after transfusion, 5 of 19 evaluable ECO RBC recipients had increases in anti-B titers. CONCLUSION: ECO RBCs were comparable to group O cells for safety and efficacy in this study. The clinical significance of the increase in anti-B and of occasional serologic incompatibilities with ECO RBCs is unclear. If strategies can be developed to remove A epitopes, enzymatic conversion could be used to create a universal (group O) donor blood supply.

ABO Blood-Group System↗
PubMed2000

Persistence of clonal T-cell expansions following high-dose chemotherapy and autologous peripheral blood progenitor cell rescue.

Analysing the regeneration of T lymphocytes after high-dose chemotherapy with autologous peripheral blood progenitor cell rescue (PBPCR) may help elucidate the mechanisms of immune recovery. The T-cell receptor variable beta chain (TCRBV) repertoire of adult patients undergoing high-dose chemotherapy was analysed by flow cytometry, before and after treatment. Four patients were found to have a stable expansion present (TCRBV3, 17, 21 and 22) ranging from 8% to 42% of the CD4(+) or CD8(+) repertoire. We demonstrated that, in these patients, following high-dose chemotherapy and autologous stem cell transplantation, the clonal expansions reappeared in peripheral blood and returned to pretransplant levels. Three expansions (CD3(+)CD8(+)TCRBV3(+), CD3(+)CD4(+)TCRBV21(+) and CD3(+)CD8(+)TCRBV22(+)) were further defined by sequence analysis of the complementarity-determining region (CDR)3 portion within the TCR rearrangements. These were shown to be predominantly clonal, with the same sequences being identified in peripheral blood before and after PBPCR, providing evidence that the overwhelming majority of T cells in these expansions arise from mature lymphocytes. This study demonstrated that patients undergoing autologous PBPCR for high-dose chemotherapy regenerate clonal expansions, consistent with pretreatment levels. They also regenerate T-cell repertoires with each TCRBV family represented to a similar level as that prior to high-dose chemotherapy.

Amino Acid Sequence↗
PubMed1999

Interleukin-10 (IL10) promoter polymorphisms and multiple sclerosis.

Interleukin-10 (IL10) is an anti-inflammatory cytokine which may modulate disease expression in multiple sclerosis (MS). Three dimorphic polymorphisms within the IL10 promoter region at positions - 1082, -819 and -519 have previously been identified. The - 1082*A allele has been associated with low and the - 1082*G allele with high in vitro IL10 production. We have genotyped 185 Caucasian MS patients and 211 ethnically matched controls for each of these three dimorphisms. MS patients were stratified for severity of disease outcome. No associations were found for any IL10 promoter polymorphisms when the MS cases were compared with controls or with disease outcome with regards to disability. IL10 polymorphism does not appear to be associated with MS or to influence disease progression.

Adult↗
PubMed1998

Removal of methylene blue from plasma via an adsorbent filter.

OBJECTIVE: To evaluate adsorbent filtration of methylene blue (MB) and leukocytes from plasma. METHODS: Plasma (750 ml) from apheresis of 10 normal subjects was split into three aliquots: control (A), filtration (B) and MB addition (to 1 microM), phototreatment and filtration (C). Biochemical and coagulation tests were performed: units A and B were reinfused. RESULTS: Filtration reduced MB to undetectable (< 0.05 microM) levels and leukocytes by 3 log10. Biochemical analytes were unchanged. The partial thromboplastin time was prolonged with MB addition (11 +/- 13%) or filtration (26 +/- 12%, p < 0.05), but the effects were not additive. Autologous transfusion was well tolerated. CONCLUSION: Adsorbent filtration can reduce residual MB to undetectable levels and yields a component suitable for transfusion.

Adsorption↗
PubMed1997

Evaluation of a new prestorage leukoreduction filter for red blood cell units.

BACKGROUND AND OBJECTIVES: Prestorage leukoreduction offers a variety of potential benefits and is becoming more commonly practiced. The LeukoNet prestorage leukoreduction filtration system is intended for leukoreduction of red blood cells and uses a vent to allow automatic drainage of red cells from the filter. MATERIALS AND METHODS: We studied the functional characteristics and the in-vivo and in-vitro properties of leukoreduced AS-1 Red Blood Cells prepared with this new system. Units of AS-1 Red Blood Cells were filtered at 4 degrees C through the LeukoNet filter 24-48 h after collection and stored under usual conditions for 42 days. Residual leukocytes were enumerated using a Nageotte chamber or with a polymerase chain reaction (PCR) technique. In the clinical trial (phase one), 21 donors had units stored with and without leukoreduction for 42 days; biochemical assays were done before and after storage, and 51Cr/99mTc red cell recovery studies at the end of the storage period. RESULTS: Leukocyte content after filtration was 3.2 +/- 2.6 x 10(4)/unit (n = 21), and all units had < 1 x 10(5) leukocytes (median: 3.8 x 10(4)). In-vivo paired studies showed no difference in 24-hour recovery (control: 82.1 +/- 5.8%; test: 82.9 +/- 6.0%). Hemolysis was halved with leuko-reduction (0.59 +/- 0.30 vs. 0.29 +/- 0.11%; p < 0.05), and glucose consumption was reduced by 5% compared to control units (p = < 0.05). Other biochemical parameters showed no differences. In the practical trial (phase two), filtration time was 41 +/- 23 min. With a residual leukocyte content of 6.6 +/- 4.9 x 10(4)/unit and 14 +/- 3% red cell loss (n = 84). Six additional units underwent leukocyte enumeration by PCR and had 2.6 +/- 1.1 x 10(4) residual leukocytes. CONCLUSIONS: Under the conditions studied, the LeukoNet leukoreduction filtration system produces about 4-5 log10 leukocyte content reduction.

Erythrocyte Transfusion↗
PubMed1995

Sterility of plastic tubing welds in components stored at room temperature.

BACKGROUND: The ability of a sterile connecting device to maintain sterility when being used to weld tubing of a blood component to be stored at room temperature, such as a platelet unit, has not been adequately documented, nor has it been determined when the tubing to be welded is filled with liquid. STUDY DESIGN AND METHODS: The sterility of sterile connecting device welds of polyvinylchloride tubing were challenged after intentional contamination of the exterior of the tubing with both gram-positive and gram-negative organisms (4 x 10(4) to 3 x 10(6) colony-forming units/mL). Welding (n = 244) was performed with the contaminated area either being wet or having been allowed to dry. At the time of the welding, the tubing segments were either empty or filled with liquid (either aliquots of white cell-reduced apheresis platelets or bacteriologic growth medium). After the welding, the liquid was passed across the weld and held in the attached transfer pack for 5 to 7 days at room temperature. RESULTS: Two welds were found to be incomplete and leaky, and both of the units involved had positive cultures. One transfer pack had inadvertently been contaminated at the time of its initial, postweld culture by a bacterium other than the one used in the experiment. Aside from these three nonevaluable units, all of the welds were sterile when cultured after the packs were held for 5 to 7 days. CONCLUSION: This study documents the ability of the sterile connecting device to maintain a closed system in the welding of blood component units to be maintained at room temperature. All welds should be closely inspected at the time of completion to detect leaks that may lead to contamination.

Bacteria↗
PubMed1994

Effects of white cell reduction on the resistance of blood components to bacterial multiplication.

BACKGROUND: While prestorage white cell (WBC) reduction by filtration may improve platelet and red cell quality, it also may remove an important anti-bacterial defense mechanism, especially if blood is WBC-reduced shortly after collection. STUDY DESIGN AND METHODS: The question of whether WBC reduction of platelet concentrates and red cells altered bacterial proliferation kinetics in components prepared from deliberately contaminated, freshly collected blood was investigated. Two-unit pools of whole blood were inoculated, at a concentration of approximately one colony-forming unit per mL, with one of 17 bacterial species reported to have caused septicemia in transfusion recipients. Each pool was divided after inoculation, and components were prepared from the 2 units after a 7-hour room-temperature holding period. One unit of each AS-1 red cell or platelet pair was WBC-reduced, and the pairs were then stored for 42 days at 4 degrees C (red cells) or for 10 days at 22 degrees C (platelets). Quantitative bacterial cultures were performed at periodic intervals. RESULTS: In red cells, clinically significant bacterial proliferation occurred in only one instance (Serratia marcescens), and growth was less rapid in the WBC-reduced unit than in the control. Three patterns of growth were seen in platelet concentrates. In four cases, there was rapid proliferation in both test and control units, while on 13 occasions there was minimal replication in either pair. On six occasions, substantial growth was noted in control units, while few or no bacteria could be found in the WBC-reduced units. There was no evidence in either red cells or platelets that bacteria proliferated more rapidly in units that had been WBC-reduced before storage than they did in units in which WBCs were retained. CONCLUSION: Rather than increasing the risk of bacterial proliferation through removal of active phagocytic cells, WBC reduction by filtration before blood storage may act to reduce the likelihood of significant bacterial proliferation, possibly by removal of microorganisms along with WBCs.

Bacteria↗
PubMed1992

Removal of Yersinia enterocolitica from AS-1 red cells.

The growth of Yersinia enterocolitica in AS-1 red cells was investigated so as to study the organism's proliferation kinetics and to evaluate the effect of prestorage white cell (WBC) reduction on bacterial multiplication. Twenty-four 2-unit pools of ABO-compatible whole blood were prepared and inoculated with Y. enterocolitica to final concentrations ranging from 0.3 to 132 organisms per mL. After inoculation, pools were split equally, AS-1 red cells were prepared, and 1 unit of each pair (test unit) was WBC-reduced with a WBC-reduction filter. Quantitative bacterial cultures of both WBC-reduced and control units were performed at several points throughout preparation and storage. Less than 10 percent of the inoculated organisms was recovered from blood samples taken after a 7-hour room-temperature holding period. By the end of 42 days of storage, Y. enterocolitica was recovered from unfiltered red cells in 2 of the 6 units inoculated at the lowest levels (0.3 and 0.7 organism/mL), from 8 of the 12 units inoculated at the intermediate levels (2.8, 5.2, 30.7, and 43 organisms/mL) and from 6 of the 6 units inoculated at the highest levels (98.8 and 132 organisms/mL). Positive cultures were seen as early as Day 7. In contrast, filtered units inoculated at all levels less than or equal to 98.8 organisms per mL (21/21 units) were sterile at the end of the 42-day storage period, while 2 units (2/3) inoculated at 132 organisms per mL showed growth despite filtration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Cutaneous signs of systemic disease.

In this article we have discussed briefly some of the important diseases in which a thorough skin examination is of help in evaluation and diagnosis of patients in an emergency department. Changes in the skin, for instance, may be the first clue of an internal malignancy. Disorders associated with gastrointestinal bleeding, endocrine abnormalities, and/or epilepsy can have prominent cutaneous manifestations. Thus, an awareness of the unusual findings is of value to the emergency medicine physician.

Diagnosis, Differential↗
PubMed1984

Influence of phospholipase C on muscarinic acetylcholine receptor binding in rat brain.

Treatment of neural membranes from rat cerebral cortex with phospholipase C (phosphatidylcholine cholinephosphohydrolase) inhibited the binding of radiolabelled antagonists to muscarinic acetylcholine receptors. This inhibition was incomplete, was not competitive, and did not appear to be related to the production of inhibitory products. The affinity of carbamylcholine for cortex muscarinic receptors was increased by phospholipase C action. The distribution of receptors between states of high and low affinity was not affected by phospholipase C; rather, the affinity for carbamylcholine of the lowest affinity receptors was selectively increased. This suggests that membrane lipids influence the interaction of the receptor binding subunit with other structures in the synaptic membrane.

Animals↗