ALBERT

Description: Introduction: Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal stem cell disorders characterized by ineffective hematopoesis, associated with cytopenias and high risk of leukemic transformations with common morbidity. MDS are hematological malignancies of unclear etiology where oxidative/nitrative stress may contribute to the pathogenesis1. The posttranslational oxidative modifications of proteins and low molecular weight compounds are induced, revealing dysbalance of redox systems in vivo. Nitration of tyrosine either in free form or bound in proteins is important marker of nitric oxide synthase (NOS) activity shift in the presence of oxidative stress in favour of superoxide formation. The aim of this work was to assess whether 3-nitrotyrosine (3-NT) serum concentrations are enhanced also in MDS patients. Methods: Serum samples were obtained using blood of either MDS patients or healthy donors. All tested individuals agreed to the study at the time of blood collection. We proposed HPLC-MS/MS method to estimate 3-NT concentration in serum samples using QTRAP 4000 mass spectrometer (ABSciex, Prague, Czech Republic). Serum proteins were precipitated using ethanol, supernatants were evaporated, reconstituted in 0.1% HCOOH/2% methanol and injected onto HALO C18 microcolumn 100x0.5 mm (ABSciex, Prague, Czech Republic). Oxidative stress in MDS patients and controls was assessed by serum malondialdehyde concentrations measured by HPLC of 2-thiobarbituric acid MDA derivative using UV detection. Results: The sensitivity of method proposed for analysis of 3-NT in sera was sufficient for estimation of differences of 3-NT in patients and control samples. We have found enhanced concentrations of both MDA and 3-nitrotyrosine in serum of MDS patients as compared with healthy donors. Discussion: Enhanced MDA concentrations in MDS patients confirmed the presence of oxidative stress in MDS patients. The reactive oxygen species may oxidize tetrahydrobiopterin, important cofactor of NOS, resulting into nitric oxide synthase uncoupling with enhanced superoxide and consequently peroxynitrite production2. It is known that methylarginines, naturally occurring inhibitors of NOS, can profoundly increase superoxide generation from uncoupled NOS. Recently, we have found significantly enhanced concentration of asymmetric dimethylarginine in a serum of middle age patients with myelodysplastic syndrome3. The observed increased concentrations of 3-NT in MDS patients correspond with assumed enhanced peroxynitrite formation as compared with controls. 3-nitrotyrosine concentrations thus could serve as a new criterion of NOS changed activity in MDS patients. Literature: 1. Farquhar MJ, Bowen DT. Oxidative stress and the myelodysplastic syndromes. Int J Hematol. 2003;77:342-350. 2. Pacher P, Beckman JS, Liaudet L. Nitric oxide and peroxynitrite in health and disease. Physiol Rev. 2007;87:315-424. 3. Štikarová J, Suttnar J, Pimková K, Chrastinová-Mášová L, Čermák J, Dyr JE. Enhanced levels of asymmetric dimethylarginine in a serum of middle age patients with myelodysplastic syndrome. Journal of Hematology & Oncology. 2013;6:58. Disclosures No relevant conflicts of interest to declare.

Description: Introduction MicroRNAs (miRNAs) are involved in the control of hematopoiesis, their deregulation also appears to play role in the pathogenesis of several hematopoietic diseases. Multiple miRNAs have been reported to be abnormally expressed in hematologic cancers; moreover, specific miRNA expression profiles have been proposed as diagnostic and prognostic markers in various hematologic malignancies, including Myelodysplastic Syndromes (MDS). MDS are a heterogeneous family of clonal disorders of hematopoietic stem cells. They are characterized by ineffective hematopoiesis and frequent leukemic progression. It has been shown that the mature erythrocytes are rich in diverse miRNAs species, even though they lack ribosomal and other large-size RNAs. miRNAs are expressed during erythrocyte differentiation and have an important role in erythropoiesis and mRNA degradation. Methods Four miRNAs, i.e. miR-16, miR-181, miR-34a, and miR-125b were selected as a model set of potential MDS biomarkers and evaluated using a surface plasmon resonance imaging (SPRi) biosensor and real-time PCR. The sensor calibration curves were measured with miRNAs spiked in a complex erythrocyte lysate. The total RNA was extracted from erythrocyte lysate using the acid guanidinium-thiocyanate-phenol-chloroform method. The levels of selected miRNAs were measured in all samples by quantitative reverse transcription - real-time polymerase chain reaction. Results A high-capacity array SPRi system for rapid simultaneous detection of multiple miRNAs in erythrocyte lysate was developed and demonstrated at the Institute of Photonics and Electronics. The ultra-low fouling functionalizable poly(carboxybetaine acrylamide) (pCBAA) brushes-coated gold surfaces of the SPR sensor were shown to reduce the non-specific interaction between surface of the sensor and sample. A two-step miRNA detection assay for multiplexed miRNA detection in erythrocyte lysate was demonstrated in which hybridization of probe-functionalized pCBAA with target miRNA bound to biotinylated oligonucleotide probes was followed with capture of streptavidin-functionalized gold nanoparticles to biotinylated probes. In preliminary experiments, the array was shown to be capable of detecting multiple miRNAs spiked in erythrocyte lysate without the need for complex lysate sample pretreatment at concentrations as low as 0.5 pM in less than 45 minutes. Conclusions Using the newly developed high-capacity array SPRi system we have found significantly increased levels of miR-16 in erythrocyte lysate samples (at the concentration range of ~10-100 pM) compared to other miRNAs tested within this study. The results were confirmed by a reference real-time polymerase chain reaction method. In addition, our results indicate an over-expression of miR-16 in erythrocyte lysate samples of MDS patients with both Refractory Cytopenia with Multilineage Dysplasia (RCMD)and Refractory Anemia with Excess Blasts (RAEB) diagnosis. This clearly demonstrates the potential of SPRi array technology for clinical applications. Disclosures No relevant conflicts of interest to declare.

Description: Introduction The protein microarrays are becoming the leading technology in proteomic research area. They enable to implement both features of proteins that can be altered in disease as quantitative proteomics (levels in biological samples) as well as functional proteomics (determination of their selective interactions with other biomolecules). Protein microarray techniques such as sandwich immunoassays, antigen capture immunoassay and direct immunoassays use labeling and antibodies. However, these labels can interfere with the analyte binding site and thus affect protein activity. Using antibodies requires a prior knowledge of the studied proteins which is in the case of a heterogeneous disease with little knowledge in its proteomic field a huge disadvantage. Surface plasmon resonance (SPR) is a label-free and direct method allowing quantification as well as monitoring of protein-protein interactions simultaneously and in real time. Myelodysplastic syndrome (MDS) is a heterogeneous group of hematological malignancies. It affects pluripotent hematopoietic stem cell and is manifested by variety of clinical symptoms according to predominant involvement of development lineage. The high risk of MDS to transform into acute myeloid leukemia makes it a suitable model for study of biological processes leading to leukemia development. In this work, we use SPR imaging for simultaneous screening of blood plasma of MDS patients followed by mass spectrometry (MS) for identification of interacting partners and analysis of protein network properties. Proteins, whose levels are either elevated during MDS disease or interaction with their receptors/ligands is a part of signaling pathway, were employed. Method SPR imaging system with polarization contrast and internal referencing was combined with dispersionless microfluidics for parallel screening of blood plasma samples. Proteins involved in pathogenesis of MDS and their physiological counterparts were immobilized under flow to create 6x6 sensing spots. Specifically, these include integrin αMβ2 (LFA1), intercellular adhesion molecule 1 (ICAM1), integrin α4β1 (VLA4), vascular cell adhesion protein 1 (VCAM1) and cytotoxic T-lymphocyte protein 4 (CTLA4). The sensor surface functionalization was optimized with respect to its ability to provide a low-fouling sensing surface with biologically active receptors. Plasma samples of controls and MDS patients were flowed along the functionalized surface and differences in individual interactions were evaluated. Selected interacting partners were further identified using 2D-HPLC/ESI-MS/MS. Identified proteins were analyzed by String Networks and Power Graph Analysis. Results and Conclusion Significant differences in the protein profiles among different MDS groups of patients as well as relative to control healthy donors were observed using SPR imaging; tens of interacting proteins were identified by mass spectrometry. Protein interaction networks were explored through clustering of proteins into groups that share the same biological function, are similarly localized in the cell, or are known to be a part of a complex. Identified proteins are involved in several processes; regulation of immune system, ubiquitinylation and protein degradation, cell signaling, hemostasis, protein synthesis, cell adhesion, metastasis, and inhibition of blood coagulation. Using of Power Graphs, a novel representation of (protein) networks, provided valuable insight into the existence of protein complexes, their internal organization, and their relationships. Interaction networks also indicated possible pathways involved in MDS pathogenesis (especially Src tyrosine kinases). The results showed that SPR biosensors are a promising tool for the diagnosis and follow-up efficiency treatment in complex heterogeneous malignancies. Disclosures No relevant conflicts of interest to declare.

Description: Introduction Hemostasis in childhood differs from that of adults; and the hemostatic system is still developing during childhood. These differences offer a protective advantage to children with hemorrhagic and thrombotic complications. Plasma levels of coagulation factors (except for fibrinogen, factor V and factor VIII), as well as plasma levels of protein C, protein S and antithrombin are reduced. Hereditary dysfibrinogenemia is a rare disorder wherein an inherited abnormality in fibrinogen structure may result in defective fibrin function and/or structure. Clinical symptoms may vary from asymptomatic to life-threatening bleeding complications. Venous or arterial thrombotic complications occur extremely rarely during childhood. Fibrinogen, a key component in hemostasis, is a 340-kDa glycoprotein. The molecule consists of three different pairs of polypeptide chains (Aα, Bβ, and γ) each encoded by a distinct gene (FGA, FGB, and FGG). N-terminal parts of the Aα chain - fibrinopeptides A and the Bβ chain - fibrinopeptides B are situated in the central part of the molecule and block polymerization of the molecules. Conversion of fibrinogen to fibrin occurs after the cleavage of N-terminal fibrinopeptides by the serine protease thrombin. Correct conformation of fibrinopeptides is important for the cleavage by thrombin. Methods Routine coagulation tests were performed with citrated plasma samples on a STA-R coagulation analyzer. The functional fibrinogen level was measured by the Clauss method. Total fibrinogen level was determined by an immunoturbidimetric assay performed on a UV-2401PC spectrophotometer. Fibrin polymerization induced by either thrombin or reptilase and fibrinolysis experiments were obtained by the turbidimetrical method. Fibrinopeptide release was measured as a function of time; and the fibrinopeptides were determined by the reversed-phase, high-performance liquid chromatography (RP-HPLC) method. The purified genomic DNA was amplified by polymerase chain reaction, using specific primers; and dideoxysequencing was performed with Dye Terminator Cycle Sequencing with a Quick Start kit and a CEQ 8000 genetic analysis system). Results We have examined two unrelated boys aged 4 (boy 1) and 14 (boy 2) for susp. dysfibrinogenemia. Routine coagulation tests revealed prolonged thrombin and reptilase time in both boys and also showed decreased functional fibrinogen levels in both kids (Tab. 1). Boy 1 presented with bleeding manifestation – easy bruising, epistaxis, and bleeding after tooth extraction. His 26-year-old mother presented with similar coagulation findings and with mild bleeding complications. Boy 2 was asymptomatic. Fibrin polymerization experiments carried out on plasma samples showed prolonged lag time and significantly reduced final turbidity in both cases. Measurement of kinetics of fibrinopeptide release showed a decreased amount of the released fibrinopeptide A in both patients. DNA sequencing of boy 1 revealed a point mutation in exon 2 of the FGA gene at the position 3456 G/A, which causes the substitution of Aα 16 Arg to His (fibrinogen Praha V). The boy was found to be heterozygous for the mutation as well as his mother. DNA analysis of boy 2 revealed the same point mutation in the FGAgene, causing the same substitution of Aα 16 Arg to His (fibrinogen Kralupy nad Vltavou). Conclusion In this study we report two cases of congenital defects in the fibrinogen Aα Arg16-Gly17 bond found during childhood. It has been described earlier that the replacement of Aα 16 arginine by histidine decelerates thrombin catalyzed fibrinopeptide A release. Although both kids presented with the same genetic defect and with similar coagulation results, they have different clinical manifestation of the disease. Acknowledgment This work was supported by the project of the Ministry of Health of the Czech Republic for conceptual development of the research organization 00023736, by Grant from the Academy of Sciences, Czech Republic (P205/12/G118), and by ERDF OPPK CZ.2.16/3.1.00/28007. Table 1: Routine coagulation test results Boy 1 Boy 1's mother Boy 2 Normal APTT 40.1 s 34.6 s 35.3 s 27.5 - 36.1 s Prothrombin time 17.5 s 14.4 s 16.9 s 11.7 - 15.1 s Thrombin time 40.9 s 36.2 s 44.8 s 17.6 - 21.6 s Reptilase time 58.3 s 51.6 s 55.7 s 16.0 - 20.0 s Fibrinogen (Clauss) 0.51 g/l 1.12 g/l 0.58 g/l 2.00 - 4.20 g/l Fibrinogen (Immuno) 2.47 g/l 2.68 g/l 2.31 g/l 2.00 - 4.20 g/l Age 4 26 14 - Disclosures No relevant conflicts of interest to declare.

Description: Congenital afibrinogenemia is very rare inherited bleeding disorder, caused by absence of fibrinogen in plasma. Serious spontaneous bleeding including intracranial haemorrhage may occur at any age. We present a case report of a boy with afibrinogenemia caused by novel mutation – homozygous deletion Aα 6477A. Diagnosis was set after bleeding post cleft lip and palate plastic surgery. Spontaneous intracranial haematoma in occipital region occurred when the boy was 11 month old. Replacement therapy with plasma derived fibrinogen concentrate successfully covered neurosurgical evacuation of hematoma. The patient was then commenced on regular prophylaxis with fibrinogen concentrate two times a week. No further bleeding episodes occurred until present time. Spontaneous intracranial bleeding in patients with inherited bleeding disorders is often life threatening. Immediate replacement therapy is crucial, together with diagnostics and surgery, when necessary. Prophylactic substitution therapy after a severe bleeding episode is recommended. Disclosures No relevant conflicts of interest to declare.

Description: Fibrinogen is one of the plasma proteins most susceptible to oxidative modification. It has been suggested that modification of fibrinogen may cause thrombotic/bleeding complications associated with many pathophysiological states of organism. We exposed fibrinogen molecules to three different modification reagents—malondialdehyde, sodium hypochlorite, and peroxynitrite—that are presented to various degrees in different stages of oxidative stress. We studied the changes in fibrin network formation and platelet interactions with modified fibrinogens under flow conditions. The fastest modification of fibrinogen was caused by hypochlorite. Fibers from fibrinogen modified with either reagent were thinner in comparison with control fibers. We found that platelet dynamic adhesion was significantly lower on fibrinogen modified with malondialdehyde and significantly higher on fibrinogen modified either with hypochlorite or peroxynitrite reflecting different prothrombotic/antithrombotic properties of oxidatively modified fibrinogens. It seems that, in the complex reactions ongoing in living organisms at conditions of oxidation stress, hypochlorite modifies proteins (e.g., fibrinogen) faster and more preferentially than malondialdehyde. It suggests that the prothrombotic effects of prior fibrinogen modifications may outweigh the antithrombotic effect of malondialdehyde-modified fibrinogen in real living systems.