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J P Aubuchon

Publications and source records attributed to J P Aubuchon.

13 recordsLinked to original sources
PubMed2005

Interruption of agitation of platelet concentrates: effects on in vitro parameters.

BACKGROUND AND OBJECTIVES: When platelet concentrates (PCs) are shipped from one centre to another, they may remain unagitated for a considerable period of time. It was therefore our aim to study the effects of interruption of agitation on the in vitro parameters of PCs stored in platelet additive solutions. MATERIALS AND METHODS: In this multicentre study, PCs were prepared either by apheresis or from pooled buffy coats, paired to minimize donor-dependent differences, and aliquoted into 3 units with a 'low concentration' (approximately 1 x 10(9) platelets/ml; groups A, B and C) and 3 units with a 'high concentration' (approximately 2 x 10(9) platelets/ml; groups D, E and F). The final composition of the storage medium was 30% plasma and 70% additive solution in all PCs. Either PASIIIM or Composol was used as the additive solution. Agitation was interrupted for 2 days (between days 3 and 5, groups A and D), or for 4 days (between days 1 and 5, groups B and E), and continuous agitation served as the reference (groups C and F). A number of in vitro parameters were used for testing on days 1, 5 and 7. RESULTS: On day 7, reference units C and F in PASIIIM had significantly higher pH values than the study units in PASIIIM, but all retained a pH of > 6.5 at 37 degrees C. Hypotonic shock response (HSR) results were significantly lower in the high concentration/4-day interruption group (E) than in the other groups. The low-concentration groups in PASIIIM, with agitation interrupted for either 2 days (group A) or 4 days (group B), did not have HSR values significantly different from the respective references. Study groups A, B, D and E in Composol, a solution lacking phosphate, had a pH of approximately 6.5 on day 7, which was significantly lower than that of the references and of the corresponding units in PASIIIM. The pH values were > 7.0 in reference groups C and F in Composol, not significantly different from those in PASIIIM. HSR values were also significantly lower in the Composol study groups. On the other hand, the reference Composol groups showed results similar to units in PASIIIM. CONCLUSIONS: PCs in PASIIIM additive solution with a platelet concentration of approximately 1 x 10(9)/ml can sustain 4 days without agitation. Phosphate may be of importance in maintaining good in vitro characteristics during interruption of agitation.

Blood Platelets↗
PubMed2003

False reactivity in GTI Pak Plus ELISA kits due to the presence of anti-mouse antibody in patients' samples.

The development of commercially available ELISA kits (GTI, Inc., Waukesha, WI) that use antigens adhered to microtiter plate wells by the use of mouse monoclonal antibodies made it possible for hospital transfusion service laboratories to test for platelet- and/or HLA-specific antibodies without reliance on reference laboratories. However, human anti-mouse antibodies (HAMAs) may cause false reactions in ELISAs. We designed a study to determine the impact of HAMAs on these ELISAs. Samples from 210 patients were evaluated from January 1995 to April 2002; 79 (38%) were found to be positive for HLA- and/or platelet-specific antibodies. Thirty (38%) of these positive samples,as well as ten negative samples that served as controls, underwent HAMA neutralization/inhibition procedures before being retested by ELISA. One (10%) of the control samples was reactive after treatment. When the samples that were positive in routine testing were treated to neutralize/inhibit HAMAs, reactivity was unchanged in 20 (67%); reactivity was eliminated in eight (27%) of the samples tested. All of the specimens that showed a reduction or elimination of their reactivity after neutralization/inhibition had an initial optical density (OD) ratio < 3.0 whereas those that remained unchanged in reactivity had an OD ratio > 7.0 (p < 0.05). Reactivity present only in the treated samples was observed in three (10%) of the positive samples tested;one was additionally reactive with HLA antigen only and two with glycoprotein Ia/IIa. The presence of HAMAs should be considered when antibodies against more than one platelet-specific glycoprotein are detected and if the optical density ratio is < 3.0.

Journal Article↗
PubMed2001

Development of anti-Bw6 reactivity in patients receiving r-GCSF: a preliminary report.

Recombinant granulocyte colony-stimulating factor (r-GCSF) is used in autologous bone marrow/peripheral blood progenitor cell transplantation (ABMT/PBPC) to shorten the period of neutropenia. As these patients require platelet transfusions, their sera may be monitored for the presence of platelet/human leukocyte antigen (HLA) antibodies. Sera of some patients on r-GCSF (16 microg/kg/day) became difficult to evaluate in vitro for the presence of HLA and platelet antibodies because of apparently anomalous reactions in solid phase red cell adherence (SPRCA) assays. SPRCA tests were positive only when platelets were adhered to the polystyrene plates in the presence of glucose; when other simple sugars were used, the patients' sera failed to react. HLA Bw6-positive platelets were more likely than HLA Bw6-negative platelets to be reactive (p <.001). The transfusion of HLA Bw6-positive platelets to patients displaying this in vitro reactivity (positive patients) resulted in a 50 percent lower corrected count increment (CCI) than those given to patients without it (negative patients; p = <.001). When all transfusions were considered, the CCI for those of the positive patients was decreased 73 percent when compared to the control patients (p =.0005). The presence of the antibody also was associated with a twofold increase in the number of platelet transfusions given (p =.0005). ABMT/PBPC patients receiving r-GCSF may develop unexpected reactions on SPRCA antibody screens and poor responses to transfusion of Bw-6-positive platelets.

Journal Article↗
PubMed1999

Frequency of thrombocytopenia associated with gentamicin therapy.

Many drugs, including antibiotics such as gentamicin, have been associated with the development of a drug-induced thrombocytopenia. Serologic methods for detection of drug-dependent platelet antibodies (DDPAs) are not routinely performed, and the incidence of such antibody-mediated thrombocytopenia is not known. As we routinely perform solid-phase red cell adherence assays for the detection of DDPAs, a study was designed to determine the incidence of gentamicin- associated platelet antibodies (GAPAs) in our institution. Adult patients who received gentamicin from 1/1/98 to 7/31/98 were evaluated for inclusion in the study. Testing for the presence of GAPAs was performed if the patient had a decrease in platelet count while receiving gentamicin or if the platelet count increased or decreased within 3 days of the last gentamicin therapy. Patients receiving gentamicin without development of thrombocytopenia were tested as controls. During the study period, 926 patients received gentamicin, with 324 (35%) being evaluated for the presence of GAPAs; GAPAs were identified in 25 of 659 patients (4%) eligible for the study. All control samples were found to lack GAPAs. If only patients exhibiting changes in platelet counts are considered, the incidence increases to 7.7 percent, with females apparently being almost twice as likely to develop GAPAs than are males. Gentamicin-associated thrombocytopenia is not an infrequent occurrence in hospitalized patients.

Journal Article↗
PubMed1995

Detection of drug-dependent platelet antibodies by use of solid-phase red cell adherence techniques.

Many drugs have been reported to cause drug-dependent thrombocytopenia, either by the immune complex or by hapten mechanisms. Testing for the presence of these platelet antibodies has not been considered feasible for transfusion services because their presence was thought to be rare, and their detection involved complex and costly methods. We have developed a new technique for detection of these antibodies that can be performed without the need for specialized and expensive instrumentation. A solid-phase red cell adherence assay was used to detect drug-dependent platelet antibodies active by either the immune complex or the hapten mechanism. Three cases were evaluated for the presence of drug-dependent platelet antibodies. Two patients presented with thrombocytopenia that could not be attributed to other causes. The third case was evaluated for the presence of drug-dependent antibodies after poor responses to platelet transfusions. In these three cases, discontinuation of the implicated drugs, i.e., porcine heparin, quinine sulfate, amoxicillin, Bactrim, and albuterol, was followed by a correction of thrombocytopenia or improved platelet transfusion response within 72 hours. This test methodology and protocol has proven very useful in avoiding transfusions with little likelihood of benefit, and in identifying drugs interfering with platelet recovery or survival. Further investigations with this technique may expand our knowledge of the capability of this technique and of the observed frequency of drug-related immunologic platelet destruction.

Journal Article↗
PubMed1990

Abnormal membrane physical properties of red cells in McLeod syndrome.

McLeod red cells (RBCs) lack Kx antigens and have weak expression of the Kell antigens. Individuals who carry the McLeod phenotype have acanthocytic RBCs and a compensated hemolytic state. To elucidate the role of the protein on which the Kx antigens reside in maintaining membrane deformability, the rheologic properties of McLeod RBCs were determined by ektacytometry. RBCs were obtained from normal individuals and from four patients with McLeod syndrome. Osmotic gradient deformability profiles of McLeod RBCs showed decreased whole cell deformability. Resealed ghosts from McLeod RBCs also showed decreased deformability, partly because of the decreased cell surface area and partly because of an intrinsic membrane stiffness in this syndrome. For the measurement of membrane mechanical stability, resealed ghosts were subjected to constant high shear stress in the ektacytomer, and deformability was recorded continuously as the deformable ghosts fragmented into rigid spherical vesicles. Membranes from McLeod RBCs showed a noticeable increase in mechanical stability. Acquired causes of acanthocytosis, such as liver disease, did not cause the rheologic abnormalities observed in McLeod cells. Other abnormalities noted in McLeod RBCs were decreased RBC potassium content and an increased number of dense RBCs, as determined by centrifugation on a discontinuous density gradient. The data indicate that McLeod RBCs are rigid and have decreased surface area and that their membranes are intrinsically rigid with increased mechanical stability. These abnormalities may account for the reduced RBC survival observed in McLeod syndrome. The protein that carries the Kx surface antigen seems to be required for the maintenance of the normal physical function of RBC skeletal proteins.

Adult↗
PubMed1988

Acoustic microscopy of red blood cells.

We used a scanning acoustic microscope to image normal and outdated red blood cells, cells with different hemoglobin content, red cell ghosts, and cells treated with various drugs that induce echinocyte-stomatocyte transformation. Images were obtained at different planes of focus within the cells, corresponding to maxima and minima of signal intensity. Digitization and gray scale amplitude mapping were used to create axonometric plots that display signal amplitude variations within the cells. The images of red cells contain features produced by differences in topology, density, elasticity, and absorption. Both hemoglobin content and the cell cytoskeleton contribute to image features, and various deformations, characterized by the formation of blebs and vacuoles, are displayed in cells undergoing echinocyte-stomatocyte transformation. These preliminary findings, although mainly descriptive, indicate that acoustic microscopy may be a useful new method for evaluating red cell deformation and associated changes in mechanical properties.

Erythrocyte Aging↗
PubMed1984

Late recurrences of histiocytic lymphoma after treatment.

Disease-free intervals of 2 to 3 years after treatment of histiocytic lymphoma are generally thought to represent cures; flat survival curves beyond 3 years in several studies support this notion. Four case reports of histiocytic lymphoma recurrences 25, 10, 9 and 6 years, respectively, after the initial diagnosis are presented. Histologic confirmation comparing primary and recurrent disease is presented. The potential biological significance of such patient reports is discussed.

Adult↗
PubMed1983

Acute cerebellar dysfunction with high-dose ARA-C therapy.

The authors report a patient with clinical and morphologic evidence of acute cerebellar toxicity after receiving high-dose cytosine arabinoside (ARA-C) (3000 mg/m2/12 hours) for refractory AML. Damage of Purkinje cells and dentate nucleus was demonstrated. Reversible cerebellar toxicity has previously been noted in patients on an identical regimen. Signs of cerebellar dysfunction mandate immediate cessation of high-dose ARA-C therapy.

Aged↗
PubMed1983

Whole body hyperthermia with a microwave regional boost: unexpected toxicity in the pig.

An animal model was used to investigate the potential for delivering a regional temperature boost using microwave energy after whole body hyperthermia had been induced in a pig using low density, radiant heat. Thermal profiles and an unexpected toxicity in the region of the microwave energy deposition, which included the heart and liver, are reported.

Animals↗
PubMedDate not supplied

Transfusion problems in renal allograft recipients. Anti-lymphocyte globulin showing Lutheran system specificity.

Heterologous anti-lymphocyte globulin (ALG) is known to contain panagglutination activity and may cause a positive direct antiglobulin test in a renal allograft recipient. Three patients are reported in whom the passively acquired antibody showed apparent specificity in the Lutheran blood group system. The sera of these patients and eluates from their red cells displayed reactivity consistent with a Lutheran-related antibody. While the neat ALG acted as a panagglutinin, the Lutheran system specificity appeared only following dilution of the ALG. This specificity did not appear to represent a separate, distinguishable antibody in the ALG product. Before considering the utilization of units of the rare Lu(a-b-) phenotype for transfusing a renal allograft patient who has a Lutheran-related antibody, investigation of ALG as a source of that antibody should be conducted.

Adult↗