Hema Quebec

Montréal, Canada

Hema Quebec

Montréal, Canada

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Godin G.,Laval University | Germain M.,Hema Quebec | Conner M.,University of Leeds | Delage G.,Hema Quebec | Sheeran P.,University of Sheffield
Health Psychology | Year: 2014

Objective: This study tested key variations in the question- behavior effect against a control condition or an implementation intention condition on returning to give blood among lapsed donors (individuals who had not given blood in the past 2 years). Design: At baseline, 7,000 lapsed donors were randomized to 1 of 6 experimental conditions or to a control condition. Participants in the experimental conditions were asked to complete a 6-item postal questionnaire assessing intentions only, interrogative intention, moral norm plus intention, anticipated regret plus intention, positive self-image plus intention, or implementation intentions. Objective measures of behavior were obtained 6 and 15 months later. The frequency of registrations to give blood over the next 6 and 15 months was measured. Results: Intention-to-treat analysis of the frequency of registrations (GENMOD procedure, Poisson distribution) indicated main effects for condition (experimental vs. control) at both 6 months, χ2(1) = 4.64, p < .05, and 15 months, Χ2(1) = 5.88, p < .05. Positive self-image and implementation intention interventions outperformed the control condition at 6 months. At 15 months, standard intention, interrogative intention, and regret plus intention conditions showed more frequent registrations compared with control and were just as effective as implementation intention formation. Moderation analysis showed that the moral norm and positive self-image conditions were significant for first-time (1 previous donation) but not repeat (2 or more previous donations) donors. Conclusion: The question- behavior effect can be used to reinvigorate blood donation among lapsed donors, and can be as effective as forming implementation intentions. © 2013 American Psychological Association.

Conner M.,University of Leeds | Godin G.,Laval University | Sheeran P.,University of Sheffield | Germain M.,Hema Quebec
Health Psychology | Year: 2013

Objective: The present research assessed the simultaneous effects of four attitude variables (cognitive attitudes, affective attitudes, anticipated negative affective reactions, and anticipated positive affective reactions) in the context of the theory of planned behavior (TPB) on blood-donation intentions and behavior. Methods: Experienced blood donors (N = 1108) completed questionnaires measuring attitude variables plus components of the TPB and a measure of attitudinal ambivalence in relation to giving blood again in the next six months. Records were used to assess whether participants subsequently donated blood again in the six months after completing the questionnaire. The main outcome measures were objectively assessed blood donation and intentions to make an additional donation of blood. Results: Confirmatory factor analysis supported a distinction between cognitive attitudes about giving blood, affective attitudes about giving blood, anticipated negative affective reactions about not giving blood, and anticipated positive affective reactions about giving blood. Multiple regression analyses indicated that perceived behavioral control, anticipated negative affective reactions, cognitive attitude, anticipated positive affective reactions and subjective norms were significant simultaneous predictors of intentions to donate blood. Logistic regression analyses indicated that intentions, perceived behavioral control, and anticipated positive affective reactions were significant, simultaneous predictors of blood donation. Attitudinal ambivalence significantly moderated the effects of cognitive attitudes on intentions, and the effects of anticipated negative affective reactions on both intentions and donation behavior. Conclusion: The findings point to the value of considering different types of attitudes, and anticipated negative affective reaction in particular, for predicting health behaviors. © 2012 American Psychological Association.

Aubin E.,Hema Quebec | Aubin E.,Laval University | Lemieux R.,Hema Quebec | Lemieux R.,Laval University | And 2 more authors.
Blood | Year: 2010

Several clinical studies done with intravenous immunoglobulin (IVIg)-treated autoimmune patients as well as several in vitro studies have revealed that IVIg can reduce polyclonal T-cell activation and modify their cytokine secretion pattern. However, their effect on (auto)antigen-specific T-cell responses has never been addressed directly. In the present work, we used an in vivo model of induction of antigen-specific T-cell responses and an in vitro antigen presentation system to study the effects of IVIg on T-cell responses. The results obtained showed that IVIg inhibited both the in vivo and in vitro antigen-specific T-cell responses but that this effect was the indirect consequence of a reduction in the antigen presentation ability of antigen-presenting cells. The inhibitory effect of IVIg was FcγRIIb- independent, suggesting that IVIg must interfere with activating FcγRs expressed on antigen-presenting cells to reduce their ability to present antigens. Such inhibition of T-cell responses by reducing antigen presentation may therefore contribute to the well-known anti-inflammatory effects of IVIg in autoimmune diseases. © 2010 by The American Society of Hematology.

Robert A.,Hema Quebec | Boyer L.,Hema Quebec | Pineault N.,Hema Quebec | Pineault N.,Laval University
Stem Cells and Development | Year: 2011

The development of culture processes for hematopoietic progenitors could lead to the development of a complementary source of platelets for therapeutic purposes. However, functional characterization of culture-derived platelets remains limited, which raises some uncertainties about the quality of platelets produced in vitro. The aim of this study was to define the proportion of functional platelets produced in cord blood CD34+ cell cultures. Toward this, the morphological and functional properties of culture-derived platelet-like particles (PLPs) were critically compared to that of blood platelets. Flow cytometry combined with transmission electron microscopy analyses revealed that PLPs formed a more heterogeneous population of platelets at a different stage of maturation than blood platelets. The majority of PLPs harbored the fibrinogen receptor αIIbβ3, but a significant proportion failed to maintain glycoprotein (GP)Ibα surface expression, a component of the vWF receptor essential for platelet functions. Importantly, GPIbα extracellular expression correlated closely with platelet function, as the GPIIb+ GPIbα+ PLP subfraction responded normally to agonist stimulation as evidenced by α-granule release, adhesion, spreading, and aggregation. In contrast, the GPIIb+ GPIbα- subfraction was unresponsive in most functional assays and appeared to be metabolically inactive. The present study confirms that functional platelets can be generated in cord blood CD34+ cell cultures, though these are highly susceptible to ectodomain shedding of receptors associated with loss of function. Optimization of culture conditions to prevent these deleterious effects and to homogenize PLPs is necessary to improve the quality and yields of culture-derived platelets before they can be recognized as a suitable complementary source for therapeutic purposes. © 2011, Mary Ann Liebert, Inc.

Leysi-Derilou Y.,Laval University | Duchesne C.,Laval University | Garnier A.,Laval University | Pineault N.,Hema Quebec
Differentiation | Year: 2012

Several fundamental questions regarding cell growth and development can be answered by recording and analyzing the history of cells and their progeny. Herein, long-term and large-field live cell imaging was used to study the process of megakaryopoiesis at the single cell level (n=9300) from human CD34 + cord blood (CB) in the presence of thrombopoietin (TPO) or the cytokine cocktail BS1 with or without nicotinamide (NIC). Comparative analyses revealed that the cocktail BS1 increased the mitotic and proplatelet rate of diploid and polyploid cells, respectively. Conversely, only NIC treatment increased the endomitotic rate of megakaryocytes (MKs) leading to the formation of CB-MKs with ploidy level frequently observed with BM-MKs. However, NIC failed to enhance platelet production. Rather, a 7- and 31-fold reduction in proplatelet formation was observed in tetraploid and octaploid CB-MKs, respectively, and ex vivo platelet production output was reduced by half due to a reduction in MK output in NIC cultures. Unexpectedly, a significant fraction of di- and polyploid CB-MKs were seen to undergo complete proplatelet regression. Though rare (<0.6%), proplatelet reversal led to the formation of regular round cells that could at times resume normal development. The cell tracking data was then used to investigate the impact of "developmental fate" and ploidy on cell cycling time, and to identify potential developmental patterns. These analyses revealed that cell fate and ploidy level have major impacts on the cell cycling time of the cells, and that four recurrent cell lineage patterns could be identified for CD34 + cells undergoing MK differentiation. © 2012 International Society of Differentiation.

Simard C.,Hema Quebec | Cloutier M.,Hema Quebec | Neron S.,Hema Quebec | Neron S.,Laval University
Cytometry Part B - Clinical Cytometry | Year: 2014

Background Multiple myeloma (MM) is an incurable cancer accounting for about 2% of cancer deaths. Its diagnosis is based on a combination of criteria, which are not always easily measurable. Flow cytometry now allows multiplex analysis of intracellular signaling at the single cell level. We investigated the feasibility of using intracellular protein phosphorylation analysis by flow cytometry on primary plasma cells from bone marrow and its usefulness in MM diagnosis. Methods Cells from frozen bone marrow of five MM patients and four normal donors were stimulated with LPS, IL-6, IL-21, IFNα and TNFα. Cells were stained by fluorescent cell barcoding to allow multiplex analysis. Staining with antibodies against phosphorylated NFkB-p65, Stat1, Stat3, and p38 were used to identify cellular responses following stimulation. Results Activation profiles of MM and normal plasma cells have been established. MM cells showed heterogeneous response profiles while normal cells responses were homogeneous between donors. We also noticed that many MM samples seemed to show elevated basal level of Stat3 phosphorylation. These results suggest that different response profiles in primary MM cells might correspond to different subtypes of the disease. Thus, we provide an example of how these results may be used as a criterion for MM subtypes classification. Conclusions We demonstrate that flow cytometry can be used to study signaling pathways in primary MM cells. The heterogeneity observed in MM cells from different patients can prove valuable for MM characterization and represents an interesting avenue for future research in MM diagnosis. © 2013 International Clinical Cytometry Society © 2013 Clinical Cytometry Society.

Tremblay T.,Laval University | Pare I.,Laval University | Bazin R.,Hema Quebec
Transfusion | Year: 2013

Background: Several mechanisms have been proposed to explain the therapeutic effects of intravenous immunoglobulin (IVIG) in immune thrombocytopenia (ITP). Noteworthy, a major role has been attributed to immunoglobulin (Ig)G dimers present in IVIG. It has also been suggested that immune complexes formed between IVIG and the patient's proteins after infusion could contribute to the therapeutic effect of IVIG in several autoimmune disorders. We recently observed that in-house preparations of polyclonal human IgG derived from small pools of plasma and devoid of IgG dimers were as efficient as IVIG in a mouse model of thrombocytopenia. In this work, we revisited the role of IgG dimers in the therapeutic effects of IVIG in ITP. Study design and methods: We used the passive mouse model of ITP to determine the therapeutic efficacy of human IgG preparations devoid of IgG dimers and of dimer-enriched and -depleted commercial IVIG. Immune complex formation between IVIG and mouse plasma proteins was evaluated using a combination of chromatography and immunoprecipitation procedures. Results: All preparations tested showed the same efficacy to alleviate ITP, regardless of their dimer contents. Significant amounts of immune complexes formed between IVIG and mouse plasma proteins were detected. However, the amount of immune complexes detected using the in-house preparation of human polyclonal IgG and mouse plasma was significantly lower, although the in-house preparation exhibited the same therapeutic efficacy as commercial IVIG. Conclusion: IgG dimers and immune complexes are dispensable to prevent thrombocytopenia in a mouse model of the disease. © 2012 American Association of Blood Banks.

Padet L.,Hema Quebec | Padet L.,Laval University | Bazin R.,Hema Quebec | Bazin R.,Laval University
Immunology Letters | Year: 2013

Clinical observations in patients treated with IVIg revealed significant modulations in T cell populations and functions. However, it is unclear whether IVIg acts directly on activated T cells to suppress their functions. To clarify the exact mechanism of IVIg action, we studied its effect on T cells activated using anti-CD3/CD28 microbeads to mimic stimulatory signals provided by accessory cells. We report here that IVIg reduces T cell proliferation and cytokine secretion by interfering with the ability of anti-CD3/CD28 microbeads to deliver activating signals to T cells. We further show that the interference occurs between IVIg and anti-CD3/CD28 microbeads and does not involve T cells. In conclusion, our work suggests that T cells are not a direct target of IVIg and that the modulation of T cell populations and functions observed in treated patients is the indirect consequence of a direct effect of IVIg on accessory cells. © 2013 Elsevier B.V.

Neron S.,Hema Quebec | Neron S.,Laval University | Roy A.,Hema Quebec | Dumont N.,Hema Quebec
PLoS ONE | Year: 2012

Polyclonal preparations of therapeutic immunoglobulins, namely intravenous immunoglobulins (IVIg), are essential in the treatment of immunodeficiency and are increasingly used for the treatment of autoimmune and inflammatory diseases. Currently, patients' accessibility to IVIg depends exclusively upon volunteer blood donations followed by the fractionation of pooled human plasma obtained from thousands of individuals. Presently, there are no in vitro cell culture procedures allowing the preparation of polyclonal human antibodies. All in vitro human therapeutic antibodies that are currently generated are based on monoclonal antibodies, which are mostly issued from genetic engineering or single cell antibody technologies. Here, we describe an in vitro cell culture system, using CD40-CD154 interactions, that leads to a 1×106-fold expansion of switched memory B lymphocytes in approximately 50 days. These expanded cells secrete polyclonal IgG, which distribution into IgG1, IgG2, IgG3 and IgG4 is similar to that of normal human serum. Such in vitro generated IgG showed relatively low self-reactivity since they interacted moderately with only 24 human antigens among a total of 9484 targets. Furthermore, up to one liter of IgG secreting cells can be produced in about 40 days. This experimental model, providing large-scale expansion of human B lymphocytes, represents a critical step toward the in vitro production of polyclonal human IgG and a new method for the ex vivo expansion of B cells for therapeutic purposes. © 2012 Néron et al.

Germain M.,Hema Quebec | Robillard P.,Hema Quebec | Delage G.,Hema Quebec | Goldman M.,Canadian Blood Services
Vox Sanguinis | Year: 2014

Canada now allows donations from men who had sex with men (MSM) if their last sexual contact with a man was more than 5 years ago. We modelled the impact of this policy on supply and safety. Approximately 4500 new donors will be added and assuming compliance to the new policy remains unchanged, the worst-case scenario predicts the introduction of one HIV-contaminated unit in the inventory every 1072 years. This change will entail negligible additional HIV risk to recipients. A five-year deferral will also protect recipients against the theoretical concern that MSM may represent a group at higher risk of sexually transmitted, emerging blood borne pathogens. © 2013 International Society of Blood Transfusion.

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