Emanuel Nečas - Profile on Academia.edu (original) (raw)

Papers by Emanuel Nečas

Second bone marrow transplantation into regenerating hematopoiesis enhances reconstitution of immune system

Frontiers in immunology, Jun 14, 2024

Resuscitation, Apr 1, 2011

Introduction: Several previous studies have focused on establishing the cause of cardiac arrest (... more Introduction: Several previous studies have focused on establishing the cause of cardiac arrest (CA) during cardiopulmonary resuscitation (CPR) provided in an out-of-hospital setting. Objectives: To analyze the ability of professional advanced life support providers to correctly establish the aetiology of cardiac arrest during out-of-hospital CPR. Study design: A retrospective cohort study analysing 211 cases of out-of-hospital cardiac arrest. Method: The aetiology assumed by out-of-hospital physicians was compared with the diagnosis that was later established by clinicians or pathologists. Results: Cases were sorted into five diagnostic groups and the overall diagnostic concordance was 74.4% (157 of 211 cases). The cardiac aetiology was presumed in 132 out of 211 patients and confirmed in 135 out of 211 patients. However, an analysis of individual cases of the cardiac causes of cardiac arrest revealed diagnostic matches in only 112 cases. Acute myocardial infarction (AMI) or pulmonary embolism (PE), both of which represent cases that can be potentially influenced by thrombolytic therapy, were presumed in 74 (53 + 21) and confirmed in 97 (77 + 20) cases, however with individual diagnostic matches in only 55 cases. This study demonstrates the importance of analysing concordance in presumed and definitive diagnosis of individual cases, since an overall comparison in a cohort of cases may be highly misleading. It introduces the method of the crosscheck table for visualization and comparison of presumed and final diagnoses. The two alternative approaches of inclusion rule for applying the thrombolytic therapy in out-of-hospital care were discussed with regard to the recent TROICA study.

Folia Biologica

). The stroma microenvironmental support of haematopoiesis is normal in UBC-GFP mice . Therefore,... more ). The stroma microenvironmental support of haematopoiesis is normal in UBC-GFP mice . Therefore, the lymphoid-primed HSCs preferentially engraft in UBC-GFP mice and outcompete the host HSCs. Transplanted bone marrow of WT mice to UBC-GFP mice provides robust long-term production of T cells, which can be transplanted to secondary and tertiary recipients . The determination of how the particular insertion site of UBC-GFP transgene next to the MHC locus on chromosome 17 compromises the lymphoid function of HSCs could enlighten the gene control of the myeloid-lymphoid potential of pluripotent HSCs.

The onset of hemoglobin synthesis in spleens of irradiated mice after bone marrow transplantation

VIIIth Symposium Structure and Function of Erythrocytes, Part I

Messenger RNA (mRNA) for globin was isolated from spleens of irradiated mice in which erythroid d... more Messenger RNA (mRNA) for globin was isolated from spleens of irradiated mice in which erythroid differentiation was induced by a bone marrow graft. The globin mRNA was isolated either by means of sucrose gradients of reticulocyte polysomal RNA or by affinity chromatography of total spleen RNA on poly (U)-sepharose. The globin mRNA was tested in a wheat embryo cell-free system. The appearance of mRNA in the spleen erythroid colonies was correlated with other parameters of erythroid differentiation such as globin synthesis, activity of delta-aminolevulinic acid synthetase and iron uptake. Poly(A) containing mRNA did appear already on the 3rd day after grafting. However, significant translational activity of globin mRNA could be demonstrated only one day later together with the increase in globin synthesis and delta-aminolevulinic acid synthetase and enhanced iron uptake. In the second part of this study mouse spleen cells rich in erythroid elements were incubated with a specific heme synthesis inhibitor (isonicotinic acid hydrazide, INH) and the synthesis of 9 S RNA was estimated. It was found that a 40-minute incubation with INH reduced uridine incorporation into 9 S RNA fraction by about 40%.

Proceedings of the National Academy of Sciences, 1993

Self-renewal implies maintenance of all attributes of the original in the offspring and is consid... more Self-renewal implies maintenance of all attributes of the original in the offspring and is considered characteristic of the hemopoietic stem cells. Yet, it has been questioned whether one of the most primitive hemopoietic stem cells, the long-term repopulating cell (LTRC), has that capacity. The present experiments demonstrate that single LTRCs can repopulate the lymphohemopoietic system of a lethally irradiated mouse and that the progeny of a single LTRC in a primary recipient again contains LTRCs capable of repopulating lethally irradiated secondary recipients. The transfusion of very small numbers of marrow cells (10,000-20,000 cells containing one or no LTRCs) unexpectedly provided insight into competitive marrow repopulation. At these low levels of stem cells, irradiated host stem cells or their progeny competed successfully with unirradiated donor cells. This parallels the known reemergence and marrow repopulation by host cells when the number of nonirradiated donor stem cells...

Leukemia, 2000

We identified a subset of genes involved in chromatin remodeling whose mRNA expression changes in... more We identified a subset of genes involved in chromatin remodeling whose mRNA expression changes in differentiating mouse erythroleukemia (MEL) cells. We furthermore tested their mRNA expression patterns in normal and malignant CD34 + bone marrow cells. SMARCA5, imitation switch gene homologue, was rapidly silenced during in vitro erythroid differentiation of MEL cells whereas it was up-regulated in CD34 + hematopoietic progenitors of acute myeloid leukemia (AML) patients. Moreover, SMARCA5 mRNA levels decreased in AML CD34 + progenitors after the patients achieved complete hematologic remission. We detected high levels of SMARCA5 mRNA in murine bone marrow and spleen and monitored its expression in these hematopoietic tissues during accelerated hematopoiesis following hemolytic anemia induced by phenylhydrazine. SMARCA5 expression levels decreased after the onset of accelerated erythropoiesis. Our data suggest that both in vitro and in vivo induction of differentiation is followed by down-regulation of SMARCA5 expression. In CD34 + AML progenitors over-expression of SMARCA5 may thus dysregulate the genetic program required for normal differentiation. Leukemia (2000Leukemia ( ) 14, 1247Leukemia ( -1252. .

Folia Microbiologica, 1998

The nu gene has been mapped to a 9-cM region of chromosome 11; it encodes a winged helix transcri... more The nu gene has been mapped to a 9-cM region of chromosome 11; it encodes a winged helix transcription factor, expressed in the skin and thymus (Reth 1995). The resulting block in T cell development can be alleviated by IL-7 (Rich and Leder 1995). The thymic dysgenesis is influenced also by the lack ofmesenchymal invasion of the anlage in the fetal stage (Groscurth and Kistler 1975) and we assume that a mesenchymal defect is not secondary to the thymic epithelial defect . This is shown by the present study on nu/+ hybrids which have, compared to +/+ homozygotes, a much smaller thymus, albeit with a normally differentiated lymphoid cortex and medulla.

erythropoietin modulated by development and inflammation, but not by iron status or , the murine ortholog of hemojuvelin gene, is Rgmc Expression of

Annals of Hematology, 1992

Normal as well as hypertransfused BDF1 mice were exposed to 300 ppm of benzene, 6 h/day, 5 days p... more Normal as well as hypertransfused BDF1 mice were exposed to 300 ppm of benzene, 6 h/day, 5 days per week for 2, 4, and 6 weeks respectively. Erythroid-committed hematopoietic progenitor cells CFU-E were determined in the bone marrow, and 59Fe incorporation was measured in the peripheral blood 48 h after its injection, as an indicator of active erythroid cell production. CFU-E numbers were reduced in benzene-exposed mice at all intervals, as was SgFe incorporation in the peripheral blood after 2 weeks of exposure. In hypertransfused mice the CFU-E suppression, caused primarily by the hypertransfusion, was aggravated by benzene. After injection of 1 IU Ep 4 days before killing the CFU-E numbers and the 59Fe incorporation increased in controls as well as in benzene-exposed animals, but the difference persisted. After nine consecutive Ep injections the difference concerning the femur disappeared after 2 and 6 weeks of benzene exposure but was still present in the peripheral blood. These results suggest that chronic benzene exposure has a negative effect on early erythroidcommitted, Ep-responsive hematopoietic cells.

STEM CELLS, 1998

Murine hematopoiesis has been analyzed by many authors, and available data allow for quantitative... more Murine hematopoiesis has been analyzed by many authors, and available data allow for quantitative evaluation of this dynamic process. In this study, the capacity of several populations of the bone marrow clonogenic cells (progenitors) to produce blood cells was compared with their actual production. The cell cycle progression rate was directly measured in the following types of hematopoietic progenitors: day 8 colony-forming units-spleen, GMcolony-forming cells, BFU-E, and CFU-E in normal mice. The cell cycle progression rates of the individual progenitors, together with their numbers in the whole hematopoietic tissue, were used to calculate the absolute numbers produced daily in each population. The data reviewed from literature were analyzed in parallel. The capacity of the progenitors to produce mature blood cells was derived from the daily production of progenitors multiplied by their clonogenic potential. This theoretical capacity to produce blood cells was compared to the actual blood cell production determined from the turnover of circulating blood elements. The comparison strongly suggested an intensive cell death rate occurring at the early stages of differentiation and its decline as the hematopoietic cells become more differentiated and mature.

Haemopoietic stem cells: spleen colony-forming cells are normally actively proliferating

Cell Proliferation, 1990

The haemopoietic stem cells forming spleen colonies (CFU-S) had on average 30 to 40% of cells eng... more The haemopoietic stem cells forming spleen colonies (CFU-S) had on average 30 to 40% of cells engaged in the DNA synthesis in normal mice continuously over 4 years. A majority of experiments aimed at the suppression of the CFU-S proliferation, which included suppression of the T-lymphocytes by means of cyclosporin A or by adult thymectomy, administration of antibacterial and antifungal agents and maintainance of mice in a sterile environment, suppression of antibody-producing cells by a successive administration of the bacterial lipopolysaccharide and cyclophosphamide and attempts to increase the total number of CFU-S in the body through massive transfusions of bone marrow cells or by grafting plugs of the bone marrow under the kidney capsulae, have not been sufficiently effective. A transient suppression of CFU-S proliferation occurred during recovery of the haemopoietic tissue from damage caused by cyclophosphamide. The results support the view that changes in CFU-S numbers and in the proportion of them in DNA synthesis may be positively correlated when CFU-S numbers fluctuate physiologically about their normal values. The failure to manipulate the CFU-S proliferation rate easily suggests that proliferation of these cells may not be under a strong 'switch on - switch off' control.

Estimation of the Pluripotential Stem Cells in Bone Marrow After Hydroxyurea

Haematology and Blood Transfusion / Hämatologie und Bluttransfusion, 1979

The method available at present for the measurement of the pluripotential stem cells (CFUs) is ba... more The method available at present for the measurement of the pluripotential stem cells (CFUs) is based on the formation of the macroscopically visible colonies on the spleen surface of the lethally irradiated mice recipients of the bone marrow cell suspension [9]. This method demonstrates a fraction of the pluripotential stem cells injected [7].

Erytropoietin u nemocných s chronickou respirační insuficiencí ::patogeneze potlačení sekundární polycytemie

Red Blood Cell Degradation Products Modify Responsiveness of Erythropoietin Gene to Hypoxia

Advances in Experimental Medicine and Biology, 1999

The oxygen sensors monitor oxygen tension in the organism and trigger appropriate feedback respon... more The oxygen sensors monitor oxygen tension in the organism and trigger appropriate feedback responses when the tension declines. Peripheral chemoreceptors in the carotid and aortic bodies, and erythropoietin (Epo) producing cells in the kidney are the most notoriously known oxygen sensors.

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[Culture of GM-CFC mouse bone marrow in semisolid agar]

Ceskoslovenská fysiologie / Ústrední ústav biologický, 1980

Erythroid gene expression requires chromatin remodeling gene SNF2h

Cytokine Gene Expression in Regenerating Haematopoietic Tissues of Mice after Cyclophosphamide Treatment

Acta Haematologica, 2003

The goal of the study was to investigate changes in expression of selected growth factors tentati... more The goal of the study was to investigate changes in expression of selected growth factors tentatively involved in regeneration of haematopoietic tissues (bone marrow and spleen) following cyclophosphamide (CY) damage in the mouse. The bone marrow (BM) and spleen were examined separately, since the regenerating pattern for haematopoietic progenitor cells (HPC) markedly differs in these two haematopoietically active organs after CY. Cytokines assumed to have a stimulatory effect on HPC – stem cell factor (SCF), fetal liver tyrosine kinase 3-ligand (flt3-ligand), thrombopoietin (TPO), stromal cell-derived factor 1 (SDF-1), oncostatin M (OSM) –, a suppressive effect on HPC proliferation – macrophage inflammatory protein-1α (MIP-1α), transforming growth factor-β1 (TGFβ1), tumour necrosis factor-α (TNFα) – and to be involved in migration of HPC (SCF, flt3-ligand, MIP1α, SDF-1) were examined at the level of mRNA expression by means of real-time RT-PCR. The expression of a particular cytoki...

Biology of Blood and Marrow Transplantation, 2013

Significant controversy exists regarding the impact of hematopoietic stroma damage by irradiation... more Significant controversy exists regarding the impact of hematopoietic stroma damage by irradiation on the efficiency of engraftment of intravenously transplanted stem cells. It was previously demonstrated that in normal syngenic mice, all intravenously transplanted donor stem cells, present in the bone marrow, compete equally with those of the host. In this study, we comprehensively compared the blood cell production derived from transplanted donor stem cells with that from the host stem cells surviving various doses of submyeloablative irradiation. We compared the partial chimerism resulting from transplantation with theoretical estimates that assumed transplantation efficiencies ranging from 100% to 20%. The highest level of consensus between the experimental and the theoretical results was 100% for homing and engraftment (ie, the utilization of all transplanted stem cells). These results point to a very potent mechanism through which intravenously administered hematopoietic stem cells are captured from circulation, engraft in the hematopoietic tissue, and contribute to blood cell production in irradiated recipients. The damage done to hematopoietic stroma and to the trabecular bone by submyeloablative doses of ionizing radiation does not negatively affect the homing and engraftment mechanisms of intravenously transplanted hematopoietic progenitor and stem cells.

Cell cycle and differentiation of Sca-1⁺ and Sca-1⁻ hematopoietic stem and progenitor cells

Hematopoietic stem and progenitor cells (HSPCs) are crucial for lifelong blood cell production. W... more Hematopoietic stem and progenitor cells (HSPCs) are crucial for lifelong blood cell production. We analyzed the cell cycle and cell production rate in HSPCs in murine hematopoiesis. The labeling of DNA-synthesizing cells by two thymidine analogues, optimized for in-vivo use, enabled determination of the cell cycle flow rate into G2-phase, the duration of S-phase and the average cell cycle time in Sca-1+ and Sca-1− HSPCs. Determination of cells with 2n DNA content labeled in preceding S-phase was then used to establish the cell flow rates in G1-phase. Our measurements revealed a significant difference in how Sca-1+ and Sca-1− myeloid progenitors self-renew and differentiate. Division of the Sca-1+ progenitors led to loss of the Sca-1 marker in about half of newly produced cells, corresponding to asymmetric cell division. Sca-1− c...

International Journal of Molecular Sciences

Erythropoietin (EPO) downregulates hepcidin expression to increase the availability of iron; the ... more Erythropoietin (EPO) downregulates hepcidin expression to increase the availability of iron; the downregulation of hepcidin is mediated by erythroferrone (ERFE) secreted by erythroblasts. Erythroblasts also express transferrin receptor 2 (TFR2); however, the possible role of TFR2 in hepcidin downregulation is unclear. The purpose of the study was to correlate liver expression of hepcidin with the expression of ERFE and TFR2 in murine bone marrow and spleen at 4, 16, 24, 48, 72 and 96 h following administration of a single dose of EPO. Splenic Fam132b expression increased 4 h after EPO injection; liver hepcidin mRNA was decreased at 16 h. In the spleen, expression of TFR2 and transferrin receptor (TFR1) proteins increased by an order of magnitude at 48 and 72 h after EPO treatment. The EPO-induced increase in splenic TFR2 and TFR1 was associated with an increase in the number of Tfr2- and Tfr1-expressing erythroblasts. Plasma exosomes prepared from EPO-treated mice displayed increase...