Current practice of autologous hematopoietic progenitor cell mobilization in adult patients with multiple myeloma and lymphoma: The results of a survey from Turkish hematology research and education group (ThREG).

Autologous hematopoietic cell transplantation (AHCT) is an established treatment option for adult patients presenting with multiple myeloma (MM), Hodgkin lymphoma (HL) and various subtypes of non-Hodgkin lymphoma (NHL) in upfront and/or relapsed/refractory disease settings. Although there are recently published consensus guidelines addressing critical issues regarding autologous hematopoietic progenitor cell mobilization (HPCM), mobilization strategies of transplant centers show high variability in terms of routine practice. In order to understand the current institutional policies regarding HPCM in Turkey and to obtain the required basic data for preparation of a national positional statement on this issue, Turkish Hematology Research and Education Group (ThREG) conducted a web-based HPCM survey. The survey was designed to include multiple-choice questions regarding institutional practice of HPCM in adults presenting MM, HL, and NHL. The representatives of 27 adult HCT centers participated to the study. Here we report the results of this survey shedding light on the real-world experience in Turkey in terms of autologous HPCM mobilization strategies in patients presenting with MM and lymphoma.

Methylation of SOCS3 in Myeloproliferative Neoplasms and Secondary Erythrocytosis/Thrombocythemia.

OBJECTIVE: Myeloproliferative neoplasms (MPNs) like essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) are acquired clonal hematopoietic stem cell disorders and originate from a multipotent hematopoietic stem cell. The SOCS1 and SOCS3 genes are negative regulators of the JAK/STAT signal pathway. In this study we investigate the promoter methylation of these genes in the pathogenesis of MPNs and secondary erythrocytosis/thrombocythemia. MATERIALS AND METHODS: Promoter methylation of SOCS1 and SOCS3 genes was analyzed with methylation-specific PCR. PCR products were analyzed by agarose gel electrophoresis. RESULTS: No disease-specific CpG island methylation of SOCS1 was observed. Hypermethylation of the SOCS3 promoter was identified in 5 out of 19 (26.3%) PV cases, 2 out of 21 (9.5%) ET cases, 1 out of 5 (20%) PMF cases, and 9 out of 42 (21.4%) cases of secondary erythrocytosis/thrombocythemia. CONCLUSION: The results revealed that promoter methylation of the SOCS3 gene suggests a possible role for SOCS3 methylation in the pathogenesis of MPNs and secondary erythrocytosis/thrombocythemia. CONFLICT OF INTEREST: None declared.

Immunosuppressive effects of multipotent mesenchymal stromal cells on graft-versus-host disease in rats following allogeneic bone marrow transplantation.

OBJECTIVE: Graft-versus-host disease (GVHD) is a major obstacle to successful allogeneic bone marrow transplantation (allo-BMT). While multipotent mesenchymal stromal cells (MSCs) demonstrate alloresponse in vitro and in vivo, they also have clinical applications toward prevention or treatment of GVHD. The aim of this study was to investigate the ability of MSCs to prevent or treat GVHD in a rat BMT model. MATERIALS AND METHODS: The GVHD model was established by transplantation of Sprague Dawley rats' bone marrow and spleen cells into lethally irradiated (950 cGy) SDxWistar rat recipients. A total of 49 rats were randomly assigned to 4 study and 3 control groups administered different GVHD prophylactic regimens including MSCs. After transplantation, clinical GVHD scores and survival status were monitored. RESULTS: All irradiated and untreated control mice with GVHD died. MSCs inhibited lethal GVHD as efficiently as the standard GVHD prophylactic regimen. The gross and histopathological findings of GVHD and the ratio of CD4/CD8 expression decreased. The subgroup given MSCs displayed higher in vivo proportions of CD25+ T cells and plasma interleukin-2 levels as compared to conventional GVHD treatment after allo-BMT. CONCLUSION: Our results suggest that clinical use of MSCs in both prophylaxis against and treatment of established GVHD is effective. This study supports the use of MSCs in the prophylaxis and treatment of GVHD after allo-BMT; however, large scale studies are needed. CONFLICT OF INTEREST: None declared.

Effects of bortezomib on platelet aggregation and ATP release in human platelets, in vitro.

INTRODUCTION: Proteasome inhibitor bortezomib (PS-341) has been the first proteasome inhibitor that has entered clinical trials with its antiproliferative and proapoptotic effects in patients with multiple myeloma. Recent studies indicate that proteasome inhibitors can be useful in prevention of experimental arterial thrombosis in renovascular hypertensive rat models. The aim of the present study is to investigate the effect of bortezomib on in vitro platelet aggregation and adenosine triphosphate (ATP) release of human platelets. MATERIALS AND METHODS: For this purpose, platelet aggregation was induced in the platelet-rich plasma (PRP) using 3 microg ml(-1) collagen, 5 microM adenosine diphosphate (ADP), 10 microM epinephrine and 1 U ml(-1) thrombin and ATP release was induced by collagen. RESULTS AND CONCLUSIONS: Bortezomib showed an inhibitory effect on platelet aggregation induced by ADP in human PRP in a dose- and time-dependent manner, whereas it had no effect on collagen-, epinephrin and thrombin-induced aggregation. ATP-release reaction induced by collagen was inhibited dose- and time-dependently by bortezomib, even though collagen-induced platelet aggregation was apparently not affected in human PRP. These findings indicate that bortezomib may be an antiaggregating agent and its' effects may be related to adenine nucleotide receptor dependent regulatory proteins which are important for physiological and pathophysiological cellular processes. However, our in vitro studies suggest that this hypothesis is inadequate to explain the observations completely. This phenomenon and its clinical implication justify further clinical investigations.

Association of plasma adiponectin concentrations with chronic lymphocytic leukemia and myeloproliferative diseases.

Adiponectin, an adipocyte-secreted hormone, is an important negative regulator in the immune system and hematopoiesis. In this study, we investigated the association of adiponectin levels with chronic lymphocytic leukemia (CLL) and myeloproliferative diseases (MPDs). We measured adiponectin levels in 19 patients with CLL and 30 patients with MPD (chronic myelogenous leukemia, 15; polycythemia vera, 9; myelofibrosis, 4; essential thrombocythemia, 2). The data were (chronic myelogenous leukemia, 15; polycythemia vera, 9; myelofibrosis, 4; essential thrombocythemia, 2). The data were compared with results from a control group of healthy volunteers who were matched according to age, sex, and body mass index. The adiponectin levels in patients with CLL were lower than in the controls (4.71 +/- 1.33 microg/mL versus 16.61 +/- 3.91 microg/mL; P <.001). They were also significantly lower in patients with MPD than in the controls (8.95 +/- 1.33 microg/mL versus 16.16 +/- 4.77 microg/mL; P <.001). In addition, we compared the adiponectin levels of MPD patients who were treated with interferon (IFN) to the levels of patients who were not treated with IFN. Adipnectin levels were significantly higher in IFN-treated patients (11.03 +/- 1.39 microg/mL versus 6.87 +/- 1.79 microg/mL; P <.001). These results suggest that lymphopoiesis and myelopoiesis negatively influence adiponectin levels. Adiponectin may be related to inflammatory cytokine release. IFN therapy appears to have a positive influence on adiponectin secretion by suppressing inflammatory cytokines. Future studies are needed to prove causality and to provide insight about this hormone's mechanism of action and its potential role regarding the etiology and progression of CLL and MPD.

The Role of Azacitidine in the Treatment of Elderly Patients with Acute Myeloid Leukemia: Results of a Retrospective Multicenter Study.

OBJECTIVE: In this study, we aimed to investigate the efficacy and safety of azacitidine (AZA) in elderly patients with acute myeloid leukemia (AML), including patients with >30% bone marrow (BM) blasts. MATERIALS AND METHODS: In this retrospective multicenter study, 130 patients of ≥60 years old who were ineligible for intensive chemotherapy or had progressed despite conventional treatment were included. RESULTS: The median age was 73 years and 61.5% of patients had >30% BM blasts. Patients received AZA for a median of four cycles (range: 1-21). Initial overall response [including complete remission (CR)/CR with incomplete recovery/partial remission] was 36.2%. Hematologic improvement (HI) of any kind was documented in 37.7% of all patients. HI was also documented in 27.1% of patients who were unresponsive to treatment. Median overall survival (OS) was 18 months for responders and 12 months for nonresponders (p=0.005). In the unresponsive patient group, any HI improved OS compared to patients without any HI (median OS was 14 months versus 10 months, p=0.068). Eastern Cooperative Oncology Group performance status of <2, increasing number of AZA cycles (≥5 courses), and any HI predicted better OS. Age, AML type, and BM blast percentage had no impact. CONCLUSION: We conclude that AZA is effective and well tolerated in elderly comorbid AML patients, irrespective of BM blast count, and HI should be considered a sufficient response to continue treatment with AZA.

Evaluation of platelet parameters in healthy apheresis donors using the ADVIA 120.

Platelet apheresis is accepted as a safe procedure and no clinically important change is observed after apheresis. The ADVIA 120 provides both an accurate platelet count and parameters describing platelet morphology and function. We studied the changes in platelet parameters of 35 healthy apheresis donors using the ADVIA 120. The mean platelet component value did not change after apheresis but the value of the platelet count was low and this reduction could be due to activation of platelets. We conclude that no remarkable changes were noted except the reduction in platelet numbers and plateletcrit which were expected to return to normal values in a few days.

Leucopenia and thrombocytopenia possibly associated with lamotrigine use in a patient.

Haematological side effects are rather exceptional with lamotrigine. We report the case of a 25-year-old woman with epilepsy who developed combined leucopenia and thrombocytopenia eight weeks after starting lamotrigine. Within weeks after lamotrigine was discontinued, all of the haematopoietic abnormalities had disappeared. To our knowledge, this is the first report of combined leucopenia and thrombocytopenia associated with lamotrigine treatment suggesting, in our patient, a causal reaction.

Identification of XRCC1 Arg399Gln and XRCC3 Thr241Met Polymorphisms in a Turkish Population and Their Association with the Risk of Chronic Lymphocytic Leukemia.

DNA repair systems are essential for cellular functions. Defects due to sequence variations in DNA repair genes can lead severe failure of cell functions and causing many cancer types including leukemia. The aim of this study was to investigate the relationship between XRCC1 Arg399Gln and XRCC3 Thr241Met polymorphisms and susceptibility to chronic lymphocytic leukemia (CLL) in Turkish patients. In addition, genotype distribution of these polymorphisms was compared with other populations. The frequencies of Arg399Gln and Thr241Met single nucleotide polymorphisms were studied in 25 CLL patients and 30 healthy individuals. Single nucleotide polymorphisms were genotyped by PCR-RFLP method. The genotype and allele frequencies of Arg399Gln and Thr241Met polymorphisms were not statistically different between the CLL patients and control group. The allelic frequency similarities were found between Turkish and Brazilian populations for Arg399Gln polymorphism. On the other hand, similarities were found between Turkish and other Caucasian populations for Thr241Met polymorphism. Marked differences were observed between American African versus Turkish and Chinese versus Turkish populations for Arg399Gln and Thr241Met polymorphisms respectively. These results indicate that Arg399Gln and Thr241Met polymorphisms were not associated with the development of CLL in Turkish population and ethnic differences is one of the most important factor for allele frequency differences.

The bisphosphonate zoledronic acid induces cytotoxicity in human myeloma cell lines with enhancing effects of dexamethasone and thalidomide.

Bisphosphonates have recently been introduced in the therapeutic armamentarium for long-term treatment of patients with multiple myeloma. These pyrophosphate analogs not only reduce the occurrence of skeletal events but also provide clinical benefit to patients and improve the survival of some of them. The existence of these capabilities raises the possibility that these compounds may have a direct antiproliferative effect on tumor cells. To investigate whether these drugs exert a direct antitumor effect, we exposed human myeloma cell lines ARH-77 and RPMI-8226 to increasing concentrations of zoledronic acid (ZOL) in vitro. A concentration- but not time-dependent cytotoxic effect was detected with drug treatment of ARH-77 and RPMI-8226 cell lines (30% and 60% at 48 hours and 38% and 62% at 72 hours, respectively, for 50 microM of ZOL). Cytotoxicity was not due to ZOL-induced chelation of extracellular calcium as shown by control experiments with the calcium chelator ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid. Addition of the competitive inhibitor of the nitric oxide synthase N omega-nitro-L-arginine methyl ester did not modulate ZOL-induced cytotoxicity. However, a decrease in the number of apoptotic cells was detected when protein kinase C was inhibited by addition of staurosporine to ZOL-containing cultures. Cytotoxicity also was increased by addition of dexamethasone (Dex) and thalidomide (Thal) to ARH-77 and RPMI-8226 cultures. We demonstrated that exposing myeloma cell lines ARH-77 and RPMI-8226 to ZOL inhibits cell growth in a dose-dependent but not a time-dependent manner and that combination of Dex and Thal with ZOL induces apoptotic cell death, providing a rationale for potential applications in vivo.

Effect of plateletpheresis on complete blood count values using three different cell separator systems in healthy donors.

The aim of this study is to investigate changes of CBC values after plateletpheresis in healthy and volunteer donors by using three different cell separator systems. The platelets were collected from 95 donors using the COBE Spectra, from 87 donors using the Fenwal CS-3000 Plus, and from 83 donors using the Fresenius AS-204. After plateletpheresis, white blood cells (WBC), hemoglobin (HGB), hematocrit (HCT), and platelets (PLT) were decreased significantly. When we used the COBE Spectra, the drop in the values of HGB and HCT was significantly less than for the other devices. It is recommended that hematological parameters should be monitored carefully in donors who are supposed to undergo long-term regular apheresis, and to prevent the occurrence of an artificial anemia, which is likely to happen. Selection of cell separator systems should be based on this possibility.

Outer hair cell activity of the cochlea in patients with iron deficiency anemia.

OBJECTIVE: Iron deficiency anemia is a common disorder, which has been reported to affect the auditory system. However, there are some conflicting points related with the pattern of hearing impairment. The aim of this study is to analyze the outer hair cell activity of the cochlea in patients with iron deficiency anemia. METHOD: Pure-tone audiometry (PTA) (250-6000 Hz) and distortion product otoacoustic emission (DPOAE) results of 42 patients with iron deficiency anemia and 22 healthy, age and sex matched subjects for the control group were compared. Cubic DPOAEs (2f1-f2) were obtained at 65 and 55 dB sound pressure level (SPL). DP grams were plotted as a function of f2 and signal-to-noise ratio (SNR) was specified as the difference in decibels SPL between DPOAE amplitude and the ambient noise level at a given f2. In DP grams, DP amplitudes and noise levels obtained from the baseline measurements were presented as the upper and lower limits of DP amplitude and noise level that were the 10th and 90th percentiles calculated by adding and subtracting standard deviations and from mean baseline DP amplitude and noise level. Independent-samples t-test is used for comparison of the groups. RESULTS: Pure-tone audiometry was normal in patients with iron deficiency anemia and control subjects and there was no significant difference in comparison of DPOAE in both groups and both sides and the results were between two percentiles (P > 0.05). CONCLUSION: The results of the present study did not support a casual relationship between the iron deficiency anemia and the auditory dysfunction on the basis of DPOAE.

In vitro effect of dexmedetomidine on platelet aggregation.

BACKGROUND AND OBJECTIVES: Dexmedetomidine is a selective α(2)-agonist. There are 250-300 α(2)-adrenoceptor on the surface of each human platelet and ephedrine induces platelet aggregation by binding these receptors. This study was designed to study platelet function after incubation with therapeutic concentrations of dexmedetomidine. METHODS: The study was carried out on 18 healthy, non-smoking males, ages ranging 25 to 35 years old. Because of the recommended therapeutic concentration range of dexmedetomidine obtained by intravenous infusion is 0.4-1.2 ng.mL(-1), dexmedetomidine solutions were prepared in three different concentrations. The calculated value of dexmedetomidine solution and diluent without dexmedetomidine as control were added to the blood sample. Thus, we obtained 0, 0.4, 0.8 and 1.2 ng.mL(-1) dexmedetomidine concentrations of plasma. Each concentration of dexmedetomidine was incubated with whole blood at 37°C during 15 minutes. Then blood samples were centrifugated to prepare platelet-rich plasma and platelet-poor plasma. The platelet-rich plasma was diluted with the platelet-poor plasma to yield test platelet-rich plasma with a fi nal platelet count of 250 ± 50 X 10(9).L(-1). RESULTS: The platelet aggregation amplitudes and slopes were statistically similar among all groups by the aggregation test, which were performed with ADP, collagen or epinephrine. CONCLUSION: Therapeutic concentrations of dexmedetomidine had no effect on the platelet functions in healthy individuals in vitro.

Isolated relapse of a lymphoblastic leukemia T cell precursor in the epididymis.

A 41-year-old man who had otherwise asymptomatic right scrotal swelling presented to our urology clinic. He had been diagnosed with T cell precursor lymphoblastic leukemia/lymphoma 2 years previously. On examination, his right epididymis was enlarged. A regular, homogeneous, slightly hypoechoic solid mass was observed at the right caput epididymis. This testicular mass measured approximately 7×11×12 mm. Leukemia and lymphoma appear in a variety of locations throughout the body, but an isolated relapse involving the epididymis is rare. Epididymectomy was performed which naturally removed the patient's right-sided sperm duct system. Especially in the younger age group epididymal masses can lead to fertility problems.

A methemoglobinemia case who was previously diagnosed and treated as asthma.

Methemoglobinemia, one of the rare causes of cyanosis and hypoxemia, may occur in congenital and acquired forms. Coexistence of cyanosis and hypoxemia suggests an etiology associated with an underlying cardiac disease firstly, but if any cardiac pathology exists pulmonary diseases are investigated generally. Considering bronchial asthma in a young patient with shortness of breath is usual. On the other hand, evaluating all the signs and symptoms together with laboratory results is important in diagnosis of rare diseases such as methemoglobinemia. In this paper we present a congenital methemoglobinemia case who was treated with bronchodilator therapy for a period of nearly five years because of misdiagnosis of asthma.

Plasmapheresis in a patient with "refractory" urticarial vasculitis.

Immune complexes are found in the circulation of 30%-75% of patients with urticarial vasculitis and much evidence supports the role of these immune complexes in the pathogenesis of urticarial vasculitis. Plasmapheresis is effective for removing these immune complexes; however, there are few reports on the use of plasmapheresis in the treatment of urticarial vasculitis. We describe a case of "refractory" urticarial vasculitis in which the symptoms improved after plasmapheresis treatment. We suggest that plasmapheresis be considered as an option in patients with severe or treatment-resistant urticarial vasculitis.

The similarity between aspirin treatment and the lack of response to epinephrine and the frequency of aspirin resistance in healthy males.

OBJECTIVES: The lack of response of platelets against epinephrine has been discovered with a frequency of 14% to 40% in previous studies. There are studies that have demonstrated the effect of aspirin on platelets may resemble the lack of response to epinephrine. In this study, the extent of the effects of aspirin treatment on aggregation and secretion in healthy males with a lack of response to epinephrine and the frequency of aspirin resistance were investigated. METHODS: Blood samples were collected at the beginning and at the end of a 10-day aspirin usage in 52 healthy males. Epinephrine, adenosine diphosphate (ADP), collagen, arachidonic acid (AA) and thrombin aggregations, and adenosine triphosphate (ATP) secretion were studied. Participants were assigned to nonresponder (<20%), semiresponder (20%-60%), and responder (>60%) groups, depending on their maximum aggregation responses to epinephrine. Participants who displayed an aggregation to AA at the end of the aspirin treatment were accepted to be aspirin resistant. RESULTS: Of the 52 participants, 4 were found to be nonresponders and 3 of 52 of the participants were found to be semiresponders. Although the lack of response to epinephrine and aspirin treatment displayed similarities in aggregations using epinephrine, ADP, collagen, and thrombin, they differed in aggregations using AA and for ATP secretion. The ratio of aspirin resistance was determined to be 4:52. CONCLUSIONS: The observation of AA aggregation in the participants with a lack of response to epinephrine demonstrates that epinephrine nonresponse cannot substitute aspirin treatment. The fact that aspirin resistance is observed in healthy males supports the view that aspirin resistance exists even before the first usage.

Platelet aggregation in children with Helicobacter pylori infection.

This study was performed to investigate the platelet aggregation alterations in platelet-rich plasma (PRP) samples of children with Helicobacter pylori (H pylori) infection. Platelet aggregation induced by adenosine diphosphate (ADP), collagen, ristocetin, or epinephrine was studied with photometric aggregometry in 30 patients before and after eradication therapy and in a control group including 15 children. The pretreatment mean maximum aggregation values and slope were significantly lower (P < .0001) in the study group at 10 µmol/L concentrations of ADP (ADP-like defect). The maximum aggregation values and slope revealed no significant differences (P > 0.05) between the study group after therapy and the control group. We concluded that H pylori infection may cause dysfunction of platelets in children and can be reversed by H pylori eradication therapy. Further studies should be carried out to determine the mechanisms of platelet dysfunction in children with H pylori infection.

A rare initial manifestation of acute lymphocytic leukemia: bilaterally enlarged kidneys and liver.

A case with early presentation of acute lymphocytic leukemia with bilaterally enlarged kidneys and liver is presented. Both hepatic and renal infiltration with leukemic cells is a rare manifestation of acute lymphocytic leukemia.

Efeito in vitro de dexmedetomidina na agregação plaquetária / In vitro effect of dexmedetomidine on platelet aggregation / Efecto in vitro de la dexmedetomidina en la agregación plaquetaria

JUSTIFICATIVA E OBJETIVOS: Dexmedetomidina é um α2-agonista seletivo. Há 250-300 receptores α2-adrenérgicos na superfície de cada uma das plaquetas humanas e a efedrina induz a agregação das plaquetas por ligação desses receptores. Este estudo foi desenvolvido para estudar a função plaquetária após incubação com concentrações terapêuticas de dexmedetomidina. MÉTODOS: O estudo foi conduzido com 18 homens saudáveis, não fumantes, com idades entre 25 e 35 anos. Porque o intervalo recomendado de concentração terapêutica de dexmedetomidina, obtido por infusão intravenosa, é de 0,4-1,2 ng.mL-1, as soluções de dexmedetomidina foram preparadas em três concentrações diferentes. Os valores calculados da solução de dexmedetomidina e do diluente sem dexmedetomidina (controle) foram adicionados a uma amostra de sangue. Assim, 0; 0,4; 0,8 e 1,2 ng.mL-1 de concentrações plasmáticas de dexmedetomidina foram obtidas. Cada concentração de dexmedetomidina foi incubada com sangue total a 37ºC durante 15 minutos. Em seguida, as amostras de sangue foram centrifugadas para preparar o plasma rico em plaquetas e o plasma pobre em plaquetas. O plasma rico em plaquetas foi diluído com o plasma pobre em plaquetas para gerar o teste de plasma rico em plaquetas com uma contagem final de plaquetas de 250 ± 50 x 10(9).L-1. RESULTADOS: As amplitudes e os declives da agregação plaquetária foram estatisticamente semelhantes entre todos os grupos nos testes de agregação feitos com ADP, colágeno ou adrenalina. CONCLUSÃO:As concentrações terapêuticas de dexmedetomidina não tiveram efeito in vitro nas funções plaquetárias de indivíduos saudáveis.

BACKGROUND AND OBJECTIVES: Dexmedetomidine is a selective α2-agonist. There are 250-300 α2-adrenoceptor on the surface of each human platelet and ephedrine induces platelet aggregation by binding these receptors. This study was designed to study platelet function after incubation with therapeutic concentrations of dexmedetomidine. METHODS: The study was carried out on 18 healthy, non-smoking males, ages ranging 25 to 35 years old. Because of the recommended therapeutic concentration range of dexmedetomidine obtained by intravenous infusion is 0.4-1.2 ng.mL-1, dexmedetomidine solutions were prepared in three different concentrations. The calculated value of dexmedetomidine solution and diluent without dexmedetomidine as control were added to the blood sample. Thus, we obtained 0, 0.4, 0.8 and 1.2 ng.mL-1 dexmedetomidine concentrations of plasma. Each concentration of dexmedetomidine was incubated with whole blood at 37ºC during 15 minutes. Then blood samples were centrifugated to prepare platelet-rich plasma and platelet-poor plasma. The platelet-rich plasma was diluted with the platelet-poor plasma to yield test platelet-rich plasma with a final platelet count of 250 ± 50 X 10(9).L-1. RESULTS: The platelet aggregation amplitudes and slopes were statistically similar among all groups by the aggregation test, which were performed with ADP, collagen or epinephrine. CONCLUSION: Therapeutic concentrations of dexmedetomidine had no effect on the platelet functions in healthy individuals in vitro.

JUSTIFICATIVA Y OBJETIVOS: La Dexmedetomidina es un α2-agonista selectivo. Hay 250-300 receptores α2-adrenérgicos en la superficie de cada una de las plaquetas humanas y la efedrina induce a la agregación de las plaquetas por el vínculo con esos receptores. Este estudio tuvo el objetivo de estudiar la función plaquetaria después de la incubación con concentraciones terapéuticas de dexmedetomidina. MÉTODOS: El estudio fue llevado a cabo con 18 hombres sanos, no fumadores, con edades entre los 25 y los 35 años. Como el intervalo recomendado de concentración terapéutica de dexmedetomidina obtenido por infusión intravenosa es de 0,4-1,2 ng/mL, las soluciones de dexmedetomidina fueron preparadas en tres concentraciones diferentes. Los valores calculados de la solución de dexmedetomidina y del diluyente sin dexmedetomidina (control), fueron adicionados a una muestra de sangre. Así se obtuvieron 0; 0,4; 0,8 y 1,2 ng.mL-1 de concentraciones plasmáticas de dexmedetomidina. Cada concentración de dexmedetomidina fue incubada con sangre total a 37ºC durante 15 minutos. A continuación se centrifugaron las muestras de sangre para preparar el plasma rico en plaquetas y el plasma pobre en plaquetas. El plasma rico en plaquetas se diluyó con el plasma pobre en plaquetas para generar el test de plasma rico en plaquetas con un conteo final de plaquetas de 250 ± 50 x 10(9).L-1. RESULTADOS: Las amplitudes y los declives de la agregación plaquetaria fueron estadísticamente similares entre todos los grupos en los test de agregación hechos con ADP, colágeno o adrenalina. CONCLUSIÓN: Las concentraciones terapéuticas de dexmedetomidina no tuvieron efecto in vitro en las funciones plaquetarias de individuos sanos.