Broadly tunable laser based on novel metallic resonant leaky-mode diffraction grating

We present a fibre laser broadly tunable in a wavelength range from 1058 nm to 1640 nm based on a new type of metallic resonant leaky-mode diffraction grating and three fibre-pigtailed semiconductor optical amplifiers. For TM polarization in Littrow configuration, the grating has experimentally measured diffraction efficiency into the -1^st reflected order of more than 90 % over a spectral range of 1417 nm to 1700 nm. The laser covered a spectral range of 331 nm within a tuning band of 558 nm without any adjustment of optics and its tuning range was limited by amplification bands of available semiconductor optical amplifiers.

KRAS pathway expression changes in pancreatic cancer models by conventional and experimental taxanes

The KRAS signalling pathway is pivotal for pancreatic ductal adenocarcinoma (PDAC) development. After the failure of most conventional cytotoxic and targeted therapeutics tested so far, the combination of taxane nab-paclitaxel (Abraxane) with gemcitabine recently demonstrated promising improvements in the survival of PDAC patients. This study aimed to explore interactions of conventional paclitaxel and experimental taxane SB-T-1216 with the KRAS signalling pathway expression in in vivo and in vitro PDAC models in order to decipher potential predictive biomarkers or targets for future individualised therapy. Mouse PDAC PaCa-44 xenograft model was used for evaluation of changes in transcript and protein levels of the KRAS signalling pathway caused by administration of experimental taxane SB-T-1216 in vivo. Subsequently, KRAS wild-type (BxPc-3) and mutated (MiaPaCa-2 and PaCa-44) cell line models were treated with paclitaxel to verify dysregulation of the KRAS signalling pathway gene expression profile in vitro and investigate the role of KRAS mutation status. By comparing the gene expression profiles, this study observed for the first time that in vitro cell models differ in the basal transcriptional profile of the KRAS signalling pathway, but there were no differences between KRAS mutated and wild-type cells in sensitivity to taxanes. Generally, the taxane administration caused a downregulation of the KRAS signalling pathway both in vitro and in vivo, but this effect was not dependent on the KRAS mutation status. In conclusion, putative biomarkers for prediction of taxane activity or targets for stimulation of taxane anticancer effects were not discovered by the KRAS signalling pathway profiling in various PDAC models.

Precise determination of primary cytogenetic abnormalities provides added value for stratification of chronic lymphocytic leukemia patients

Cytogenetic analysis has become a standard procedure in the management of newly diagnosed chronic lymphocytic leukemia patients. Prognostic information is reported based on the presence of certain abnormalities and karyotype complexity after conventional karyotyping and/or fluorescence in situ hybridization (FISH). The information on cytogenetic abnormalities occurring in isolation is robust; however, the performance of patients with two or more cytogenetic abnormalities is heterogeneous and information is scarce. This retrospective study analyzed whether information on the precise determination of primary cytogenetic abnormalities can have some added value in terms of risk stratification in chronic lymphocytic leukemia (CLL) patients. The study cohort was 121 patients without the need to start treatment for CLL immediately after diagnosis but had completed initial cytogenetic analysis. Results from conventional karyotyping after stimulation of CLL cells and FISH analysis were combined. Risk stratification based purely on the determination of primary cytogenetic abnormalities was effective in CLL patients, with comparable results in stratification based on the presence of certain abnormalities and karyotype complexity. It is recommended that information on suspected primary abnormalities is included in cytogenetic reports, especially in patients with two or more abnormalities, because this can provide valuable additional information.

Primary retroperitoneal Ewings sarcoma

The Ewings sarcoma (EWS) family tumors are small, round, cell tumors with different degrees of neuroectodermal differentiation with a peak incidence in children and young adults. About 10-20% of cases are extraskeletal EWS.

Gamma Radiation Reduced Toxicity of Azoxystrobin Tested on Artemia franciscana

Fungicide azoxystrobin toxicity was monitored by means of a 96-h biotest with Artemia franciscana nauplius stages after exposure to solutions with concentrations of 0.2, 0.4, 0.6 and 0.8 mg L(-1) irradiated with (60)Co gamma radiation with doses of 1, 2.5, 5 and 10 kGy. The effects of ionization radiation on azoxystrobin toxicity were mainly manifested by a statistically significant reduction of lethality after 72- and 96-h exposure. A maximum reduction of lethality of 72 % was achieved using doses of 1-5 kGy for an azoxystrobin initial concentration of 0.4 mg L(-1) and after 72 h of exposure. At a 96-h exposure, a difference of lethal effects reached up to 70 % for a dose of 10 kGy. The observed effect of gamma ionizing radiation on azoxystrobin toxicity suggest that this approach can be applied as an alternative for a reduction of azoxystrobin residua in food.

Discontinuation of tyrosine kinase inhibitors in chronic myeloid leukemia patients - worldwide battlefield

Advances in understanding the pathogenesis of chronic myeloid leukemia (CML) and implementation of the therapy with tyrosine kinase inhibitors (TKI) could be considered as a prototype of successful fight against cancer. However, for an optimally responding patient it is recommended to follow the TKI therapy indefinitely. The question about the possibility of safe TKI treatment discontinuation in certain clinical situations was raised and is currently under close investigation worldwide. Currently, imatinib discontinuation trails have shown that about 60% of eligible patients experienced molecular recurrence within 6 months of treatment discontinuation, while the remaining 40% remained in defined deep molecular response throughout the duration of mostly two years follow-up. Interestingly, retreatment with the same TKI or another TKI was successful in the vast majority of patients demonstrating molecular recurrence of the disease. These findings support the concept of safe TKI treatment discontinuation and its usefulness for a specific subset of CML patients. However, recent data are not sufficient for TKI discontinuation attempts outside clinical trials yet. Because of the high risk of potentially problematic molecular recurrences of the pathological clones, the key question is to find the right predictive marker of TKI discontinuation success, however it stays unsolved yet. This minireview brings a concise summary of this hot topic with a realistic view from clinical routine.

KEYWORDS

tyrosine kinase inhibitors, imatinib, discontinuation, chronic myeloid leukemia.

Allogeneic stem cell transplantation can improve outcome of AML patients without complete cytogenetic response after induction and consolidation treatment

Our retrospective analysis was performed on 376 consecutive patients diagnosed with AML. A total of 256 (68%) were treated with standard "7+3" induction and high-dose cytarabine and mitoxantrone containing "4+3" consolidation/intensification regimens. Our study focused on patients with presumably very poor prognosis - patients, who did not achieve complete cytogenetic remission (CRc). Twenty-five AML patients without CRc were further analysed for clinical and laboratory parameters. Firstly, the subgroups with or without morphologic CR were compared. Similar cytogenetic abnormalities were observed in both with myelodysplasia related changes being the most common. Complex karyotype with deletion of 5q constituted approximately a third of all karyotypes in both subgroups. There were 1 patient with intermediate risk cytogenetics in the subgroup without morphologic CR and 5 patients in the subgroup with morphologic CR. Interestingly, in 4/25 patients subclones were diminished by the chemotherapy treatment, however cytogenetically less advanced clones proliferated. Secondly, transplanted or nontransplanted patients were analysed. Allogeneic stem cell transplantation (allo-SCT) was found to be the only curative treatment for patients without CRc after 7+3 and 4+3 regimens. In our cohort, 40% of the patients, who underwent allo-SCT, are alive. Importantly, 67% of the patients, who died after allo-SCT, died of causes unrelated to progression of AML. Nonrelapse mortality is therefore one of the fields where survival could be further improved.

KEYWORDS

acute myeloid leukaemia, complete cytogenetic remission, cytogenetic abnormalities, stem cell transplantation, nonrelapse mortality.

Proteomic profiling of human embryonic stem cell-derived microvesicles reveals a risk of transfer of proteins of bovine and mouse origin

BACKGROUND AIMS

Microvesicles (MV) shed from the plasma membrane of eukaryotic cells, including human embryonic stem cells (hESC), contain proteins, lipids and RNA and serve as mediators of cell-to-cell communication. However, they may also contain immunogenic membrane domains and infectious particles acquired from xenogenic components of the culture milieu. Therefore, MV represent a potential risk for clinical application of cell therapy.

METHODS

We tested the ability of hESC and their most commonly used feeder cells, mouse embryonic fibroblasts (MEF), to produce MV. We found that hESC are potent producers of MV, whereas mitotically inactivated MEF do not produce any detectable MV. We therefore employed a combined proteomic approach to identify the molecules that constitute the major components of MV from hESC maintained in a standard culture setting with xenogenic feeder cells.

RESULTS

In purified MV fractions, we identified a total of 22 proteins, including five unique protein species that are known to be highly expressed in invasive cancers and participate in cellular activation, metastasis and inhibition of apoptosis. Moreover, we found that hESC-derived MV contained the immunogenic agents apolipoprotein and transferrin, a source of Neu5Gc, as well as mouse retroviral Gag protein.

CONCLUSIONS

These findings indicate that MV represent a mechanism by which hESC communicate; however, they also serve as potential carriers of immunogenic and pathogenic compounds acquired from environment. Our results highlight a potential danger regarding the use of hESC that have previously been exposed to animal proteins and cells.

Embryonic stem cell-derived microvesicles reprogram hematopoietic progenitors: evidence for horizontal transfer of mRNA and protein delivery

Membrane-derived vesicles (MV) are released from the surface of activated eucaryotic cells and exert pleiotropic effects on surrounding cells. Since the maintenance of pluripotency and undifferentiated propagation of embryonic stem (ES) cells in vitro requires tight cell to cell contacts and effective intercellular signaling, we hypothesize that MV derived from ES cells (ES-MV) express stem cell-specific molecules that may also support self-renewal and expansion of adult stem cells. To address this hypothesis, we employed expansion of hematopoietic progenitor cells (HPC) as a model. We found that ES-MV (10 microg/ml) isolated from murine ES cells (ES-D3) in serum-free cultures significantly (i) enhanced survival and improved expansion of murine HPC, (ii) upregulated the expression of early pluripotent (Oct-4, Nanog and Rex-1) and early hematopoietic stem cells (Scl, HoxB4 and GATA 2) markers in these cells, and (iii) induced phosphorylation of MAPK p42/44 and serine-threonine kinase AKT. Furthermore, molecular analysis revealed that ES-MV express Wnt-3 protein and are selectively highly enriched in mRNA for several pluripotent transcription factors as compared to parental ES cells. More important, this mRNA could be delivered by ES-MV to target cells and translated into the corresponding proteins. The biological effects of ES-MV were inhibited after heat inactivation or pretreatment with RNAse, indicating a major involvement of protein and mRNA components of ES-MV in the observed phenomena. We postulate that ES-MV may efficiently expand HPC by stimulating them with ES-MV expressed ligands (e.g., Wnt-3) as well as increase their pluripotency after horizontal transfer of ES-derived mRNA.

Increased expression of fibroblast growth factor receptor 3 in CD34+ BCR-ABL+ cells from patients with chronic myeloid leukemia

Previously, we showed that expression of myeloma-associated (proto)oncogene fibroblast growth factor receptor 3 (FGFR-3) is increased in white blood cells from patients with chronic myeloid leukemia (CML). The abnormal expression was returned back to the normal levels as soon as these patients reconstituted their hematopoiesis following transplantation of allogeneic peripheral blood stem cells. The aims of this study were: (1) to define population(s) of cells overexpressing FGFR-3, and (2) to determine the expression of FGFR-3 during the clinical course of the disease. We show that the vast majority of FGFR-3 transcripts as well as FGFR-3 protein arise from CD34+ BCR-ABL+ cells. Although increased levels of FGFR-3 were found in majority of late chronic phase patients treated with interferon alpha or hydroxyurea, the expression of FGFR-3 was always lowered following treatment with BCR-ABL tyrosine kinase inhibitor STI571. Compared to unstimulated cells, high levels of FGFR-3 were also identified in CD34+ cells from granulocyte colony-stimulating factor-mobilized blood stem cell harvests from healthy donors, suggesting a potential growth factor-dependent basis for elevated expression of FGFR-3 in CML. These findings have implications for the involvement of FGFR-3 in malignant hematopoiesis and depict FGFR-3 tyrosine kinase in CD34+ leukemic cells as a possible target for tyrosine kinase inhibitors.

Temperature dependence of polymer-gel dosimeter nuclear magnetic resonance response

The purpose of this study was to find a physical-mathematical description capable to correct a polymer-gel dosimeter relaxation rate R2-dose response for different temperatures. Four different modifications of polymer-gel dosimeters were used in this study. Samples with polymer-gel dosimeter in glass test vessels were homogeneously irradiated by 60Co gamma photons. A multi-echo sequence with 16 equidistant echoes was used for evaluation of irradiated polymer-gel dosimeters. The sequence parameters were as follows: TR 2000 ms, TE 22.5-360.0 ms, slice thickness 5 mm, FOV 255 mm, one acquisition. The proposed description recommends to subtract R2 response of the nonirradiated dosimeter from the total R2-dose response. The relaxation rate for the irradiated dosimeter can be expressed as a function of temperature and dose. The temperature dependence has an exponential behavior in the measured range. The proposed description allows to correct the measured NMR R2-dose responses for different temperatures.

Energy and dose rate dependence of BANG-2 polymer-gel dosimeter

The purpose of this study was to evaluate dependence of BANG-2 polymer-gel dosimeter sensitivity on different photon and electron energies as well as on different mean dose rates expressed as repetition rates for a standard clinically used linear accelerator. The sensitivity of the dosimeter was represented by the slope of calibration curve in the linear region measured for each modality. A calibration curve (in the linear region) based on five dosimeters (four irradiated and one background) was obtained for each photon and electron energy and different repetition rates. Dosimeter sensitivity dependence on energy was studied for 4, 6, and 18 MV x-ray photons and for nominal electron energies 9, 12, 16, and 20 MeV. Dosimeter sensitivity dependence on mean dose rate was separately studied for electron and photon beams with the use of repetition rates 80, 160, 240, 320, and 400 MU min(-1). Evaluation of dosimeters was performed on Siemens MAGNETOM EXPERT 1T scanner in the head coil. A multiecho sequence with 16 equidistant echoes was used for the evaluation of irradiated polymer-gel dosimeters. The parameters of the sequence were as follows: TR 2000 ms, TE 22.5-360.0 ms, slice thickness 5 mm, FOV 255 mm, one acquisition. There was observed a trend in polymer-gel dosimeter sensitivity dependence on the quality index of high energy x-ray beams used and on mean electron energy absorbed in the center of the dosimeter. Polymer-gel dosimeter sensitivity was decreasing with increasing photon or electron energy. There was observed no trend in polymer-gel dosimeter sensitivity dependence on mean dose rate expressed as a repetition rate for both photon and electron beams.

Changes in the expression of FGFR3 in patients with chronic myeloid leukaemia receiving transplants of allogeneic peripheral blood stem cells

Fibroblast growth factor receptors (FGFR1-4) are implicated in various cellular events, including cell growth and transformation. Here, we showed that patients suffering from chronic myeloid leukaemia (CML) express high levels of FGFR3 mRNA in white blood cells (WBCs). After stem cell transplantation and reconstitution of haematopoiesis, the expression of FGFR3 decreased and was maintained at low levels that are typical of healthy individuals. However, FGFR3 expression became upregulated again in those patients that had accelerated BCR/ABL rearrangement and underwent relapse of leukaemia. Our findings suggest that, in CML, the changing levels of FGFR3 transcripts in WBCs may have prognostic significance.

Modulation of protein synthesis in rabbit inner cell mass-derived cells by FGF-2

Gastrulation is a critical step in vertebrate development, that depends on synergistic effects of several signalling molecules, including fibroblast growth factor-2 (FGF-2). To follow this phenomenon in vitro we isolated rabbit inner cell masses (ICMs) at embryonic day 4 and we exposed ICM-derived cells to FGF-2. Then, we analysed the quantitative differences in rates of protein synthesis from day 3 to day 5 of culture by two-dimensional (2D) gel electrophoresis. Here we show that both up- and down-regulation of protein synthesis took place in ICM-derived cells upon their exposure to FGF-2. The effect of FGF-2 was most pronounced at day 4 of culture, when the changes were very much in favour of a set of down-regulated proteins. To test the significance of this period of time for FGF-2-mediated regulation of protein synthesis, cells were grown without FGF-2 and then they were pulse-treated with FGF-2 at the end of day 4. When compared to the continuous culture with FGF-2, the FGF-2 pulse resulted in a quite indistinguishable pattern of up- and down-regulated proteins. Thus, the readiness of ICM-derived cells to accept and respond to the FGF-2 signals may be of limited duration.

O-linked carbohydrates are required for FGF-2-mediated proliferation of mouse embryonic cells

During development, fibroblast growth factors (FGFs) serve highly specific functions that are mediated through high-affinity transmembrane receptors and modulated by membrane-bound proteoglycans. Proteoglycans, in an embryonic environment called embryoglycans, contain numerous carbohydrate ectodomains, the structure of which undergoes rearrangement. Since they can be lost from the cell surface, they are sometimes found in extracellular space where they may also serve some regulatory function. Here we address the potential roles of three naturally occurring isoforms of Lewis X (LeX) in FGF-2-mediated proliferation of embryonic stem (ES) cells. We have found that the addition of sulfated LeX to ES cells at a concentration of 17 nM promotes FGF-2 mitogenic activity while a 10-fold higher concentration leads to a reduction of FGF-2-mediated proliferation. Notably, this dose-dependent modulation operated only for sulfated LeX. Other fucosylated motifs, basic LeX trisaccharide and sialylated LeX, also affected ES cell proliferation but the mechanism cannot be clearly correlated with the presence or absence of FGF-2. The suppression of biosynthesis of O-linked carbohydrates including LeX reduced basal proliferation of ES cells and interfered with the mitogenic effect of FGF-2. However, in inhibitor-treated cells, the stimulatory activity of FGF-2 can be reestablished to its original level by exogenous LeX oligosaccharides. Our results show that (A) O-linked LeX oligosaccharides can regulate mitogenic activity of FGF-2 in embryonic cells, (B) and this ability varies with subtle modifications in their structure. Importantly, our data represent the first insight into the mechanism of how growth factor activities might be modulated by shedded embryoglycan ectodomains.

Management of health services in the Czech Republic

During the 1990s, following political transformation, the Czech Republic's health care system has been experiencing profound changes. This article examines how health care institutions, hospitals, in particular, have found themselves having to undergo a transformation from budgetary organizations to free market enterprises. In addition to their daily professional tasks, medical institutions are being forced to adjust to a new environment, to work actively on solutions to their numerous economic problems, and, above all, to generate adequate financial means to support themselves. This article focuses on the challenges faced by public hospitals in the Czech Republic, including an excess of acute beds, financing system and pharmaceutical costs, and the need for effective health management to deal with these challenges.

Cell mixing during the early development of mouse aggregation chimera

Two different inbred strain combinations of mouse aggregation chimeras - C3H/HeN (H-2k) x C57BL/6N (H-2b) and C3H/HeN x BALB/cA (H-2d) were used for cell mixing analysis at two points in time - 24 h after aggregation (just prior to transplantation into foster mothers) and 7.5 days post coitum (p.c.). The cell proportion of two H-2 haplotypes at the blastocyst stage was studied using a fluorescence-labeled monoclonal antibody recognizing a C3H-specific alloantigen - CSA (C3H strain-specific antigen) and laser scanning confocal microscopy. The 7.5-day-old chimeras were sectioned and subsequently processed by sensitive biotinylated antibody - avidin peroxidase immunohistochemical technique. Our results showed that 24 h after aggregation (blastocyst stage), there was equal cell mixing and no mouse strain used in the present study was dominant at this time. In 7.5-day-old C3H/HeN x BALB/cA chimeras, cells of both genotypes were intermingled, but the C3H/HeN strain was dominant in all cases. In contrast, the combination C3H/HeN x C57BL/6N clearly showed reduced numbers of C3H/HeN cells (CSA-positive) in 83% of the chimeras evaluated. Generally, CSA positive cells were found only in randomly distributed small distinct areas representing less than 20% of embryonal cells. Surprisingly, the extraembryonal ectoplacental cone was uniformly CSA positive in some C3H/HeN x C57BL/6N chimeras. Furthermore, in 36% of normally implanted chimeras of both strain combinations progressive degeneration was observed. We suggest that the cell mixing pattern as well as the absolute number of cells derived from each strain in the aggregation chimera can be affected by specific immune interactions involving H-2 haplotype combinations of the allogeneic fetus and the fully immunocompetent host organism, at later points in development.

Expression of paternal and maternal mitochondrial HSP70 family, hsc74, in preimplantation mouse embryos

We have investigated the regulation of gene expression of a novel mitochondrial HSP70 family, hsc74 in preimplantation mouse embryos. We used a monoclonal antibody, anti-CSA, which reacts with only one of strain variants of the hsc74. By immunostaining with anti-CSA antibody, the hsc74 protein was constitutively detected in C3H embryos from 1-cell to blastocyst stage, but no signals were detectable in C57BL/6 embryos. To know the timing of paternal genome expression, we examined the expression of hsc74 in (C57BL/6 x C3H)F1 embryos. No positive signals were detectable in embryos before 8-cell stage. In early 8-cell stage weakly positive signals appeared in the peripheral region of the blastomeres. From late 8-cell stage, the protein was intensively detectable and was persistently expressed in all types of cells. We have also applied a sensitive methodology to distinguish genetic variants of hsc74 from C3H and C57BL/6 by reverse transcription polymerase chain reaction followed by single strand conformation polymorphism analysis. In (C57BL/6 x C3H)F1 embryos, the paternal transcripts were first detected in 4-cell embryos, while the maternal transcripts were constantly detectable. These results indicate that the transcripts and proteins of hsc74 were derived only from the maternal gene from 1-cell to 4-cell stages, and that from 4-cell stage the paternal gene is also transcribed, and the significant increase of the paternally derived protein occurred around late 8-cell stage.