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J Bartos

Publications and source records attributed to J Bartos.

At least 19 recordsLinked to original sources
PubMed2006

Positronium annihilation lifetimes and dielectric spectroscopy studies on diethyl phthalate: phenomenological correlations and microscopic analyses in terms of the extended free volume model by Cohen-Grest.

A combined positronium annihilation lifetime spectroscopy (PALS) and dielectric spectroscopy (DS) study on a typical van der Waals glass-former diethyl phthalate (DEP) was performed and the results were compared. From phenomenological point of view, the mutual relationships between the characteristic PALS temperatures, the glass temperature TgPALS, and the crossover temperatures Tb1L and Tb2L on the ortho-positronium (o-Ps) lifetime versus the temperature plot, have been discussed with respect to the characteristic DS temperatures, the glass temperature TgDS and the dynamic crossover temperature TBST, concerning the crossover behavior of primary alpha-relaxation times. Next, simultaneous application of the extended free volume (EFV) model by Cohen-Grest on the temperature dependence of both the mean free volume hole size data as extracted from PALS and the dielectric alpha-relaxation time revealed a good agreement between the experimental Tb1L and the characteristic EFV temperatures T0DS and T0PALS at which a free volume percolation should occur. These results indicate the important role of free volume in control of the primary (alpha) dynamics of supercooled DEP.

Journal Article↗
PubMed2006

[Laparoscopy-assisted exenteration of the pelvis in a locally advanced rectal carcinoma].

INTRODUCTION: In this pilot study, based on three case-reviews, the authors report on their initial experience with the laparoscopy-assisted total exenteration of the pelvis, conducted in patients with locally advanced rectal carcinomas. METHODS: In two patients with histologically confirmed rectal carcinomas, the neoadjuvant radiochemotherapy was initiated, due to the locally advanced tumor finding, aiming to downstage and locally control the disorder. The pelvic exenteration was indicated, based on the control findings of the imagining methods. In one patient, due to repetitive enterorrhagies, the primary surgical management was indicated. RESULTS: The surgical procedures were multidisciplinary, assisted by urologists. In all three cases, the laparoscopic resections, followed by planned conversions and constructions of the ileouretheral conduit and the terminal sigmoidostomies (resp. with their maintenance), were completed. Prior to the procedures, in all the three patients, the presence of distant metastases was excluded. No peroperative complications were recorded in the case-reviews. In one case, postoperative re-suturing of the wound was inevitable, due to its dehiscence. In this patient, the enzymatic acute MI, without the ECG correlate, was diagnosed. CONCLUSION: The laparoscopy-assisted pelvic exenteration may be a suitable modification of the classical surgical procedure in selected patient groups with locally advanced colorectal carcinomas. Good visualisation and exact orientation in the region of the small pelvis, as well as other generally accepted advantages of miniinvasive procedures, are the pros of the method.

History, 17th Century↗
PubMed2006

[Causes of recurrencies following procedures for varicose veins of the lower extremities].

AIM: The aim of the study is to analyze causative factors of recurrencies following varicose veins procedures, and to propose procedures aimed at reduction of the relapse rates. MATERIAL AND METHODOLOGY: During the period of 1993-2005, 2034 extremities in 1756 patients were operated. 24% of the cases were reoperations, 85% of the operated were sclerotized pre- or post-operatively. Total anaesthesia was used in 1350 subjects, 406 patients underwent procedures under local anaesthesia. Complete crossectomy was completed, mostly including invagination stripping of the femoral part of the VSM. When necessary, the saphenopopliteal junction and perforators were resected. RESULTS: No deaths were recorded. The complication rate was 3.8%, all were managed without hospitalization and included the wounds healing complications. 91% of patients were discharged on the day of the procedure. Over 50% of patients were not out of work. 420 procedures were reoperations (24%). None or incomplete crossectomy was analyzed as the relaps cause in 65% of the cases. None or misconduct resection of the saphenopopliteal junction and perforators resulted in relapses in 35% of the cases. In all cases, it could be concluded, that badly managed, or not at all managed, reflux was the cause of the reoperations. Following completion or either primary operation or reoperation by our team, 404 operated were lost from our evidence, 1352 patients were followed up regulary. 16 patients (1.2%) were indicated for another surgical procedure, 14 of them were indicated for the saphenopopliteal junction incompetence and 2 for its reincompetence. No new reflux in the groin region was recorded. CONCLUSION: Badly managed, or not at all managed, saphenofemoral or saphenopopliteal reflux was the cause of significant recurrencies resulting in reoperations. Neoanginogenesis was not recorded and the authors refuse to accept it as a cause of the relapses of the varicose veins. Exact diagnosis, correct indication and sufficient radicality of the procedure prevent recurrencies of the disorder.

Female↗
PubMed2006

[Colorectal cancer--short time results of laparoscopic resection in 350 patients].

BACKGROUND: Laparoscopic resection of the colon with its results is fully acceptable method of choice in patients with colorectal cancer. Authors present their own experiences. METHODS AND RESULTS: A retrospective study of 350 patients who undergone laparoscopic resection because of colorectal carcinoma (curative or palliative) from January 1, 2002 to December 31, 2005. From these patients 50.8 % were operated in the 1. and II. grade of the disease, it means without detectable metastases of the lymphatic nodes. Patients with the carcinoma localised in rectosigma and rectum - 61.1 % dominate in our study. The conversion of the laparoscopic operation was necessary in 9.1%, in 13.1% there were surgery postoperative complications and postoperative mortality was 1.4%. Normal eating was allowed to patients in average 4.1 days after the operation and the average hospitalisation time was 8.3 days. We mentioned also the time of operation in various types of resection, size of resection express by the number of detectable lymph nodes and necessity of the postoperative analgesic therapy. CONCLUSIONS: Laparoscopic resection of the colorectal cancer is today method of choice, which is safe for patient and with the same morbidity and mortality as in open surgery, provides advantages of mini-invasive approach.

Adult↗
PubMed2005

Free-volume dynamics in glasses and supercooled liquids.

A free-volume theory is developed based on the defect diffusion model (DDM). In addition, positronium annihilation lifetime spectroscopy (PALS) ortho-positronium free-volume and intensity data are presented for poly(propylene glycol) with a molecular weight of 4000 (PPG 4000) in both the glassy and liquid states and dielectric relaxation and electrical conductivity data are reported for PPG 4000 in the liquid state. The DDM is used to interpret all of the data for PPG 4000 and previously reported PALS and dielectric relaxation data for glycerol. It is shown that while the PPG 4000 data exhibit a preference for the three-halves power law, the data for glycerol favor the first power (standard Vogel-Fulcher-Tammann) law. Good agreement between the DDM and the experimental results is found for all of the electrical data and the PALS free-volume data. While reasonable agreement is also found for the PALS intensity data for PPG 4000, a discrepancy exists between the experimental PALS intensity data and theory for glycerol. For the electrical conductivity for PPG 4000, a transition is observed at the same temperature (about 1.4 T(g) where T(g) is the glass transition temperature) where the PALS free volume changes from steeply rising with temperature to approximately independent of temperature. The same behavior is observed at about 1.5 T(g) for previously reported dielectric relaxation and PALS data for glycerol. Model parameters are presented that show the dominance of mobile single defects above (1.4-1.5) T(g) and the dominance of immobile clustered single defects below T(g) . Finally, a coherent picture of glasses and glass-forming liquids is presented based on the theory and results of the experiments.

Journal Article↗
PubMed2005

Genetic variability in the three genomes of Nasonia: nuclear, mitochondrial and Wolbachia.

Nasonia consists of three closely related species of parasitoid wasps that are all infected with the endosymbiotic bacteria Wolbachia, a reproductive parasite common in arthropods. This situation presents the opportunity to compare patterns of variation in three associated genomes, Wolbachia and the nuclear and mitochondrial genomes of its host. Furthermore, although Nasonia wasps are emerging as a model for evolutionary and genetic studies, little is known about their genetic variability. Using amplified fragment length polymorphisms (AFLPs), all three species present a relatively high level of nuclear polymorphism and have different patterns of variation, with one of the species, Nasonia giraulti, being divided into two divergent subgroups. In each species, the mitochondrial pattern of variation is different from the nuclear pattern, possibly due to genetic hitchhiking of the mitochondria during (cytoplasmically inherited) Wolbachia sweeps. Mitochondria in Nasonia show a synonymous substitution rate approximately 10-15-fold higher than nuclear genes, probably reflecting an elevated mitochondrial mutation rate that is among the highest found in insects. Finally, all three species are doubly infected with their own strains of Wolbachia, one each from the two major supergroups (A and B). Sequence analysis reveals that each of the three Nasonia species acquired their A and B bacteria independently by horizontal transfer events from other insects with the exception of B type Wolbachia in N. longicornis and N. giraulti, which were acquired prior to speciation and then codiverged with the host. This represents one of the few clear-cut examples of codivergence of Wolbachia during host speciation.

Animals↗
PubMed2005

Nuclear genome size and genomic distribution of ribosomal DNA in Musa and Ensete (Musaceae): taxonomic implications.

Nuclear DNA content and genomic distributions of 5S and 45S rDNA were examined in nineteen diploid accessions of the genus Musa representing its four sections Eumusa, Rhodochlamys, Callimusa and Australimusa, and in Ensete gilletii, which was the outgroup in this study. In the Eumusa (x = 11), 2C DNA content ranged from 1.130 to 1.377 pg, M. balbisiana having the lowest DNA content of all sections. M. beccarii (x = 9), a representative of Callimusa, had the highest 2C nuclear DNA content (1.561 pg). Species belonging to Rhodochlamys (x = 11) and Australimusa (x = 10) had 2C DNA contents ranging from 1.191 to 1.299 pg and from 1.435 to 1.547 pg, respectively. E. gilletii (x = 9) had 2C DNA content of 1.210 pg. The number of 5S rDNA loci in Musa varied from 4 to 8 per diploid cell. While different numbers of 5S rDNA loci were observed within Eumusa and Rhodochlamys, four 5S rDNA loci were observed in all accessions of Australimusa. M. beccarii (Callimusa) and E. gilletii contained 5S rRNA gene clusters on five and six chromosomes, respectively. The number of 45S rDNA loci was conserved within individual sections. Hierarchical cluster analysis of genome size, number of chromosomes and 45S rDNA sites suggested a close relationship between Rhodochlamys and Eumusa; Australimusa was clearly separated as were M. beccarii and E. gilletii. Within the Eumusa-Rhodochlamys group, M. balbisiana, M. schizocarpa and M. ornata formed distinct subgroups, clearly separated from the accessions of M. acuminata, M. mannii, M. laterita and M. velutina, which formed a tight subgroup. The results expand the knowledge of genome size and genomic distribution of ribosomal DNA in Musa and Ensete. They aid in clarification of the taxonomical classification of Musa and show a need to supplement the analyses on the DNA sequence level with cytogenetic studies.

Cell Nucleus↗
PubMed2005

Peroxisome proliferator-activated receptors (PPAR) agonists affect cell viability, apoptosis and expression of cell cycle related proteins in cell lines of glial brain tumors.

The nuclear receptors PPARs (peroxisome proliferator-activated receptors) are transcription factors activated by specific ligands. PPARs play an important role in carcinogenesis, inflammation, atherosclerosis, lipid metabolism and diabetes. There is evidence that activation of PPARs by specific ligands is able to suppress the growth of different types of human cancer by mechanisms including the growth arrest, apoptosis and induction of differentiation, although the detailed signalling pathways have not been completely elucidated to date. The aim of our study was to determine whether synthetic ligands of PPARalpha and PPARgamma could affect the viability, proliferation, differentiation, apoptosis and expression of some cell cycle related proteins in glial tumor cell lines. The study was performed on human glioblastoma cell lines U-87 MG, T98G, A172 and U-118 MG. Cell lines were treated by ligands of PPARalpha (bezafibrate, gemfibrozil) and PPARgamma (ciglitazone). MTT, flow cytometry, TUNEL assay and immunoblotting were used for detection of changes in cell viability, proliferation, differentiation and apoptosis. Bezafibrate, ciglitazone and gemfibrozil inhibited viability of glioblastoma cell lines. The synthetic ligands significantly reduced or induced the expression of cyclins, p27Kip1, p21Waf1/Cip1, MDM-2, Bcl-2, Bax, PARP, Caspase 3, androgen receptors, etc. and did not affect the expression of the differentiation marker GFAP. Flow cytometry confirmed arrest of the cell cycle although the detection of apoptosis was controversial. Apart from hypolipidemic and hypoglycaemic effects, PPAR ligands may also have significant cytostatic effects of potential use in anticancer treatment.

Apoptosis↗
PubMed2004

High-resolution FISH on super-stretched flow-sorted plant chromosomes.

A novel high-resolution fluorescence in situ hybridisation (FISH) strategy, using super-stretched flow-sorted plant chromosomes as targets, is described. The technique that allows longitudinal extension of chromosomes of more than 100 times their original metaphase size is especially attractive for plant species with large chromosomes, whose pachytene chromosomes are generally too long and heterochromatin patterns too complex for FISH analysis. The protocol involves flow cytometric sorting of metaphase chromosomes, mild proteinase-K digestion of air-dried chromosomes on microscopic slides, followed by stretching with ethanol:acetic acid (3 : 1). Stretching ratios were assessed in a number of FISH experiments with super-stretched chromosomes from barley, wheat, rye and chickpea, hybridised with 45S and 5S ribosomal DNAs and the [GAA]n microsatellite, the [TTTAGGG]n telomeric repeat and a bacterial artificial chromosome (BAC) clone as probes. FISH signals on stretched chromosomes were brighter than those on the untreated control, resulting from better accessibility of the stretched chromatin and maximum observed sensitivity of 1 kbp. Spatial resolution of neighbouring loci was improved down to 70 kbp as compared to 5-10 Mbp after FISH on mitotic chromosomes, revealing details of adjacent DNA sequences hitherto not obtained with any other method. Stretched chromosomes are advantageous over extended DNA fibres from interphase nuclei as targets for FISH studies because they still retain chromosomal integrity. Although the method is confined to species for which chromosome flow sorting has been developed, it provides a unique system for controlling stretching degree of mitotic chromosomes and high-resolution bar-code FISH.

Chromosomes, Artificial, Bacterial↗
PubMed2003

Wolbachia and genetic variability in the birdnest blowfly Protocalliphora sialia.

Wolbachia are widespread cytoplasmically inherited bacteria that induce various reproductive alterations in host arthropods, including cytoplasmic incompatibility (CI), an incompatibility between sperm and egg that typically results in embryonic death. CI has been invoked as a possible mechanism for reproductive isolation and speciation in arthropods, by restricting gene flow and promoting maintenance (and evolution) of genetic divergence between populations. Here we investigate patterns of Wolbachia infection and nuclear and mitochondrial differentiation in geographical populations of the birdnest blowfly Protocalliphora sialia. Blowflies in western North America are infected with two A-group Wolbachia, with some individuals singly and others doubly infected. Individuals in eastern North America mostly show single infections with a B-group Wolbachia. Populations in the Midwest are polymorphic for infections and show A- or B-group infection. There is a low level of mitochondrial divergence and perfect concordance of mitochondrial haplotype with infection type, suggesting that two Wolbachia-associated selective sweeps of the mitochondrion have occurred in this species. Amplified fragment length polymorphism analysis of nuclear genetic variation shows genetic differentiation between the eastern-Midwestern and western populations. Both Midwestern and eastern flies infected with A-Wolbachia show eastern nuclear genetic profiles. Current results therefore suggest that Wolbachia has not acted as a major barrier to gene flow between western and eastern-Midwestern populations, although some genetic differentiation between A-Wolbachia infected and B-Wolbachia infected individuals in eastern-Midwestern populations cannot be ruled out.

Animals↗
PubMed2002

[Personal experience with the Barron method of treatment of hemorrhoidal nodules].

The authors present their experience with the treatment of haemorrhoidal nodes by Barron's method, having used this method for 2.5 years at the surgical department of the Vítkov hospital. By this method in 1999-2001 122 patients with clinical manifestations of grade I-III haemorrhoids were treated. In the described group six relapses were recorded.

Aged↗
PubMed2001

Expression of ob gene coding the production of the hormone leptin in hepatocytes of liver with steatosis.

Leptin is a circulating pleiotropic hormone that play an important role in appetite control, fat metabolism, regulation of body weight, fetus growth, growth and aging of adults and hematopoiesis. It is expressed abundantly and specifically in the adipose tissue. A liver cell with developed steatosis represents a cell metabolism similar to metabolism of cells of adipose tissue. Analyses of serum leptin and free leptin receptor in the serum of patients with steatosis showed significant variations from reference limits of normal values. However in liver tissue with verified steatosis detection of mRNA gene for leptin was not proven. Such expression of ob gene for leptin was not found even in the liver tissue without steatosis. With respect to the absence of ob gene expression, the direct effect of ob gene expression on other parameters of leptin metabolism could not be evaluated. The RT-PCR method with verified specificity and satisfying sensitivity was developed. The results obtained from analysis of serum leptin and free leptin receptor in the serum are presented and evaluated. The used methods were verified and reference limits for Czech population were defined in dependence on age and other clinical parameters.

Fatty Liver↗
PubMed1999

Microscopic basis of free-volume concept as studied by quasielastic neutron scattering and positron annihilation lifetime spectroscopy.

We have reexamined the free-volume concept presented by Cohen and Turnbull on the basis of two microscopic quantities: the excess mean-square displacement (f) and the total free volume V(PA,t), of poly- butadiene evaluated from the quasielastic neutron scattering and the positron annihilation lifetime spectroscopy (PALS) data, respectively. Comparing with the viscosity eta we found two relations, eta=eta(0) exp u( 2)(0)/ (f) and eta=eta(0) exp V(*)(PA,0)/V(PA,t)=eta(0) exp V(*)(PA,0)/v(PA,f), where u(2)(0), V(*)(PA,0) and v(*)(PA,0) are the critical values for the mean-square displacement, the total PALS free volume, and the PALS free volume per molecule, respectively, and further v(*)(PA,0)=V(*)(PA,0)/N, N being the total number of molecules or segments. On the basis of these relations, we discuss the microscopic basis of the free-volume theory. The experimentally evaluated critical values u(2)(0) and v(*)(PA,0) are much larger than the average values of (f) and v(PA,f) calculated from the distributions. This has been explained from the low probability of escaping motions from a molecular cage. The free volume per monomer and the free-volume fraction were calculated from the excess mean-square displacement (f). The former was compared with the free-volume hole obtained by PALS, suggesting that 22 monomers are required for one PALS free-volume hole. The free-volume fraction obtained from the excess mean-square displacement was found to be 6.4% at 250 K, which is in reasonable agreement with that evaluated from the rheological data (9.0%).

Journal Article↗
PubMed1999

[New methods of surgery on the arteries supplying the brain].

INTRODUCTION: Brain ischaemia as a sequelae of atherosclerosis involving the brain-supplying arteries is one of the commonest causes of death in the industrialized nations. MATERIAL AND METHODS: A total of 236 procedures on the internal and common carotid arteries in 227 patients with a mean age of 67 years were performed. General anaesthesia was used in 18.5% of patients, cervical block in 81.5%. RESULTS: The hospitalization morbidity of our group of patients was 8.9%, hospitalization mortality was zero. No association between the technique of anaesthesia and morbidity was found. However, cervical block allowed a marked shortening of postoperative hospitalization time from 5.5 days to 2 days. CONCLUSION: The results obtained justify surgical procedures on the internal and common carotid arteries even in asymptomatic stenoses, and are especially useful before a scheduled cardiac surgical or vascular surgical procedure.

Aged↗
PubMed1992

[Ecotoxicologic relations on a large pig-fattening farm located in a lignite mining area and near and solid-fuel electical power plant].

Major contaminants identified in 1983-1984 on a pig fattening farm with an output of 60,000 pigs per annum, located in a lignite mining area and near a solid fuel power plant, were mercury, cadmium, lead, chromium and aflatoxin B1 (Tab. I, II, III, IV). Feed samples were collected from througs to assess the contamination load at feed uptake. Permissible concentrations of mercury, chromium, cadmium, aflatoxin B1, lead and atrazin in the feed were exceeded in 56, 50, 31, 19, 6 and 6% samples, respectively (Tab. I). Stable dust deposits, in which the contaminants concentrate, (Tab. I) proved to be a suitable material for assessing the type and level of environmental contamination. Permissible concentrations of mercury, cadmium and lead in porcine muscles were exceeded in 65, 51 and 24% samples, respectively (Tab. III). Corresponding values of mercury, cadmium, lead and aflatoxin B1 in the liver were 27, 27, 16 and 3%, respectively (Tab. III) and those of mercury, lead and chromium in kidneys 24, 22 and 5%, respectively (Tab. III). Rather surprisingly, elevated pancreatic concentrations of aflatoxin B1 were found (Tab. IV). Pigs fattened in the contaminated environment (i.e. fed contaminated feed mixtures, inspiring contaminated dust and absorbing percutaneously contaminants form dust deposits on the body surface) showed: 1) Impairment of the genetic apparatus (percentage of aberrant peripheral leucocytes elevated to 6.2%); 2) a certain degree of immunosuppression (concentrations of IgG, IgM and IgA reduced by 16.9, 45.1 and 45.0%, respectively); 3) higher feed consumption per 1 kg weight gain (4 kg) and lower average daily weight gain (0.57 kg); 4) increased incidence of health disorders (dermatitis in 25%, pancreatopathy in 13%, liver dystrophy in 8% and femoral fracture in 6% of the pigs). Unfortunately, the authors were not allowed to analyse ash and solid emissions from the power plant. Therefore the share of the emissions in the overall environmental contamination on the fattening farm could not be quantified. The personnel, working in the contaminated environment for a prolonged period, is endangered most of all by stable dust, being exposed to its mechanical, chemical, allergic and infectious effects (Tab. I). In addition to the chemical contaminants, 21 mould genera and species, six mite species and numerous saprophytic and some pathogenic bacteria were demonstrated in stable dust samples in our earlier experiments. Consumption of meat and organs from pigs fattened in a contaminated environment is associated with the risk of an increased uptake of various contaminants.(ABSTRACT TRUNCATED AT 400 WORDS)

Animal Husbandry↗