RESUMEN
BACKGROUND: Clot waveform analysis (CWA) reportedly enhances the interpretation of clotting time measurement. This study aimed to compare CWA between prothrombin time (PT) and activated partial thromboplastin time (APTT) assays for better understanding how to apply CWA for assessing effects of direct oral anticoagulants (DOACs). METHODS: Samples were prepared by spiking plasma with rivaroxaban, apixaban, edoxaban, or dabigatran. To compensate the influence of fibrinogen, CWA parameters were adjusted by unifying maximum changes in transmittance in clotting reaction curves detected by the optical system. RESULTS: Non-adjusted PT-CWA parameters unexpectedly rose at low drug concentrations but declined at high drug concentrations while adjusted PT-CWA parameters exhibited dose-dependent decrease. Both non-adjusted and adjusted APTT-CWA parameters showed dose-dependent decrease. Adjusted CWA parameters were applicable to Hill plot analysis. All DOACs exhibited Hill coefficients indicating positively cooperative effects regarding most adjusted PT-CWA parameters. Regarding adjusted APTT-CWA parameters, rivaroxaban, apixaban, and edoxaban exhibited Hill coefficients indicating no or negatively cooperative effects. The observed differences between PT-CWA and APTT-CWA suggested the implication of thrombin positive feedback in DOAC effects. CONCLUSION: The results revealed distinct features of DOAC effects in extrinsic and intrinsic pathways. To ascertain the clinical implication, further studies using clinical samples are needed.
Asunto(s)
Anticoagulantes , Tiempo de Protrombina , Humanos , Tiempo de Tromboplastina Parcial , Anticoagulantes/farmacología , Administración Oral , Coagulación Sanguínea/efectos de los fármacosRESUMEN
How to optimize perioperative factor VIII (FVIII) replacement through hemostatic monitoring is critically important to manage hemophilia A patients. The bispecific antibody emicizumab binds activated FIX (FIXa) and FX to functionally mimic FVIIIa. While being used for hemostatic control in hemophilia A, this therapeutic antibody inconveniently interferes with coagulation tests using human FIXa and FX, such as activated partial thromboplastin time (APTT) and FVIII activity measurement based on one-stage clotting assays. Clot waveform analysis (CWA) extends the interpretation of measurement curves for coagulation time to provide global information. We performed APTT-CWA to monitor perioperative hemostasis in a hemophilia A patient on emicizumab undergoing liver transplantation. Plasma samples were treated with anti-idiotype monoclonal antibodies against emicizumab to enable accurate coagulation assays. Kinetics of maximum coagulation velocity and acceleration mimicked that of FVIII activity. These CWA parameters better correlated with FVIII activity than APTT. The plateaus of them were observed at FVIII activity of 100% or more, supporting the protocol for perioperative FVIII replacement. Thus, CWA may measure coagulation potential in hemophilia A patients undergoing liver transplantation, aiding in optimizing perioperative hemostasis.
Asunto(s)
Anticuerpos Biespecíficos , Hemofilia A , Hemostáticos , Trasplante de Hígado , Trombosis , Humanos , Hemofilia A/tratamiento farmacológico , Hemostasis , Anticuerpos Biespecíficos/uso terapéutico , Trombosis/tratamiento farmacológicoRESUMEN
AIMS: While antithrombin (AT)-independent inhibitors targeting thrombin or activated factor X have been assessed through clot waveform (CWA), there are no reports on assessment with respect to AT-dependent anticoagulants. The present study aims to characterise AT-dependent anticoagulants through CWA to distinguish them from AT-independent inhibitors. METHODS: CWA was applied to the activated partial thromboplastin time (APTT) assay of plasma samples spiked with each of AT-dependent drugs (unfractionated heparin, enoxaparin and fondaparinux) and AT-independent drugs (rivaroxaban, apixaban, edoxaban, dabigatran, argatroban, hirudin and bivalirudin), which was performed using the CS-5100 or CN-6000 (Sysmex). The APTT-CWA data were automatically gained by the analyser program. The positive mode of clotting reaction curves was defined as the direction towards fibrin generation. RESULTS: Regarding dose-response curves in AT-dependent anticoagulants, the maximum positive values of the first and secondary derivatives (Max1 and Maxp2, respectively) and the maximum negative values of the secondary derivative (Maxn2) seemed to drop to zero without making an asymptotic line, consistent with the irreversibility. Such a feature was observed also in hirudin, as reported previously. Notably, the symmetric property of Max1 peaks in the waveforms was distorted dose dependently in AT independent but not AT-dependent drugs. A plot of Maxp2 logarithm versus Maxn2 logarithm was linear. The slope was about 1 in AT-dependent drugs while that was more than 1 in AT-independent drugs. These features made it possible to distinguish AT-dependent and AT-independent drugs. CONCLUSIONS: The results aid in further understanding of the pharmacological aspects of anticoagulation and in screening of candidates for novel anticoagulants.
Asunto(s)
Anticoagulantes/farmacología , Antitrombinas/farmacología , Coagulación Sanguínea/efectos de los fármacos , Retracción del Coagulo , Tiempo de Tromboplastina Parcial , Relación Dosis-Respuesta a Droga , Inhibidores del Factor Xa/farmacología , Humanos , Valor Predictivo de las PruebasRESUMEN
Monosomy 7 and interstitial deletion of 7q (-7/7q-) are well-recognized nonrandom chromosomal abnormalities frequently found among patients with myelodysplastic syndromes (MDSs) and myeloid leukemias. We previously identified candidate myeloid tumor suppressor genes (SAMD9, SAMD9-like = SAMD9L, and Miki) in the 7q21.3 subband. We established SAMD9L-deficient mice and found that SAMD9L(+/-) mice as well as SAMD9L(-/-) mice develop myeloid diseases resembling human diseases associated with -7/7q-. SAMD9L-deficient hematopoietic stem cells showed enhanced colony formation potential and in vivo reconstitution ability. SAMD9L localizes in early endosomes. SAMD9L-deficient cells showed delays in homotypic endosome fusion, resulting in persistence of ligand-bound cytokine receptors. These findings suggest that haploinsufficiency of SAMD9L and/or SAMD9 gene(s) contributes to myeloid transformation.
Asunto(s)
Deleción Cromosómica , Haploinsuficiencia , Leucemia Mieloide/genética , Síndromes Mielodisplásicos/genética , Proteínas Supresoras de Tumor/genética , Animales , Cromosomas Humanos Par 7 , Endosomas/metabolismo , Endosomas/patología , Orden Génico , Marcación de Gen , Células Madre Hematopoyéticas/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intracelular , Leucemia Experimental , Leucemia Mieloide/diagnóstico , Leucemia Mieloide/mortalidad , Ratones , Ratones Noqueados , Virus de la Leucemia Murina de Moloney/patogenicidad , Síndromes Mielodisplásicos/diagnóstico , Síndromes Mielodisplásicos/mortalidad , Proteínas/genética , Proteínas/metabolismo , Infecciones por Retroviridae/genética , Proteínas Supresoras de Tumor/deficiencia , Infecciones Tumorales por Virus/genéticaRESUMEN
During prometaphase, dense microtubule nucleation sites at centrosomes form robust spindles that align chromosomes promptly. Failure of centrosome maturation leaves chromosomes scattered, as seen routinely in cancer cells, including myelodysplastic syndrome (MDS). We previously reported that the Miki (LOC253012) gene is frequently deleted in MDS patients, and that low levels of Miki are associated with abnormal mitosis. Here we demonstrate that Miki localizes to the Golgi apparatus and is poly(ADP-ribosyl)ated by tankyrase-1 during late G2 and prophase. PARsylated Miki then translocates to mitotic centrosomes and anchors CG-NAP, a large scaffold protein of the γ-tubulin ring complex. Due to impairment of microtubule aster formation, cells in which tankyrase-1, Miki, or CG-NAP expression is downregulated all show prometaphase disturbances, including scattered and lagging chromosomes. Our data suggest that PARsylation of Miki by tankyrase-1 is a key initial event promoting prometaphase.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Centrosoma/metabolismo , Poli Adenosina Difosfato Ribosa/metabolismo , Proteínas/metabolismo , Tanquirasas/metabolismo , Proteínas de Ciclo Celular/química , Células Cultivadas , Centrosoma/química , Aparato de Golgi/química , Aparato de Golgi/metabolismo , Células HEK293 , Células HeLa , Humanos , Huso Acromático/química , Huso Acromático/metabolismoRESUMEN
The dynactin complex is required for activation of the dynein motor complex, which plays a critical role in various cell functions including mitosis. During metaphase, the dynein-dynactin complex removes spindle checkpoint proteins from kinetochores to facilitate the transition to anaphase. Three components (p150(Glued), dynamitin, and p24) compose a key portion of the dynactin complex, termed the projecting arm. To investigate the roles of the dynactin complex in mitosis, we used RNA interference to down-regulate p24 and p150(Glued) in human cells. In response to p24 down-regulation, we observed cells with delayed metaphase in which chromosomes frequently align abnormally to resemble a "figure eight," resulting in cell death. We attribute the figure eight chromosome alignment to impaired metaphasic centrosomes that lack spindle tension. Like p24, RNA interference of p150(Glued) also induces prometaphase and metaphase delays; however, most of these cells eventually enter anaphase and complete mitosis. Our findings suggest that although both p24 and p150(Glued) components of the dynactin complex contribute to mitotic progression, p24 also appears to play a role in metaphase centrosome integrity, helping to ensure the transition to anaphase.
Asunto(s)
Anafase/fisiología , Centrosoma/metabolismo , Cromosomas Humanos/metabolismo , Metafase/fisiología , Proteínas Asociadas a Microtúbulos/metabolismo , Inestabilidad Cromosómica/fisiología , Cromosomas Humanos/genética , Complejo Dinactina , Células HEK293 , Células HeLa , Humanos , Proteínas Asociadas a Microtúbulos/genética , Interferencia de ARNRESUMEN
Monosomy 7 and interstitial deletions in the long arm of chromosome 7 (-7/7q-) is a common nonrandom chromosomal abnormality found frequently in myeloid disorders including acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and juvenile myelomonocytic leukemia (JMML). Using a short probe-based microarray comparative genomic hybridization (mCGH) technology, we identified a common microdeletion cluster in 7q21.3 subband, which is adjacent to 'hot deletion region' thus far identified by conventional methods. This common microdeletion cluster contains three poorly characterized genes; Samd9, Samd9L, and a putative gene LOC253012, which we named Miki. Gene copy number assessment of three genes by real-time PCR revealed heterozygous deletion of these three genes in adult patients with AML and MDS at high frequency, in addition to JMML patients. Miki locates to mitotic spindles and centrosomes and downregulation of Miki by RNA interference induced abnormalities in mitosis and nuclear morphology, similar to myelodysplasia. In addition, a recent report indicated Samd9 as a tumor suppressor. These findings indicate the usefulness of the short probe-based CGH to detect microdeletions. The three genes located to 7q21.3 would be candidates for myeloid tumor-suppressor genes on 7q.