Showing papers by "Charles University in Prague published in 1997"

Double-blind comparison of an oral Escherichia coli preparation and mesalazine in maintaining remission of ulcerative colitis.

Abstract: Background Aminosalicylates are used as standard treatment for maintaining remission in ulcerative colitis. As yet, there is no other existing alternative with proven efficacy. In light of the hypothesis that the intestinal environment may contribute to the pathophysiology of ulcerative colitis, a trial was conducted to test the effects of probiotic treatment with an oral preparation of non-pathogenic E. coli. Methods A total of 120 patients with inactive ulcerative colitis were included in a double-blind, double-dummy study comparing mesalazine 500 mg t.d.s. to an oral preparation of viable E. coli strain Nissle (Serotype 06: K5: H1) for 12 weeks with regard to their efficacy in preventing a relapse of the disease. Study objectives were to assess the equivalence of the clinical activity index (CAI) under the two treatment modalities and to compare relapse rates, relapse-free times and global assessment. Results The start and end scores of the CAI demonstrated no significant difference (P=0.12) between the two treatment groups. Relapse rates were 11.3% under mesalazine and 16.0% under E. coli Nissle 1917 (N.S.). Life table analysis showed a relapse-free time of 103±4 days for mesalazine and 106±5 days for E. coli Nissle 1917 (N.S.). Global assessment was similar for both groups. Tolerability to the treatment was excellent and did not differ. No serious adverse events were reported. Conclusions From the results of this preliminary study, probiotic treatment appears to offer another option for maintenance therapy of ulcerative colitis. Additional support is provided for the hypothesis of a pathophysiological role for the intestinal environment in ulcerative colitis.

Transcranial Magnetic Stimulation during Positron Emission Tomography: A New Method for Studying Connectivity of the Human Cerebral Cortex

Abstract: We describe a new technique permitting the mapping of neural connections in the living human brain. The method combines two well established tools of brain research: transcranial magnetic stimulation (TMS) and positron emission tomography (PET). We use TMS to stimulate directly a selected cortical area while simultaneously measuring changes in brain activity, indexed by cerebral blood flow (CBF), with PET. The exact location of the stimulation site is achieved by means of frameless stereotaxy. In the first study using this technique, we found significant positive correlations between CBF and the number of TMS pulse trains at the stimulation site, namely the left frontal eye field (FEF) and, most importantly, in the visual cortex of the superior parietal and medial parieto-occipital regions. The pattern of these distal effects was consistent with the known anatomic connectivity of the monkey FEF. We suggest that the combined TMS/PET technique offers an objective tool for assessing the state of functional connectivity without requiring the subject to engage in any specific behavior.

Three-Dimensional Organization of Smooth Endoplasmic Reticulum in Hippocampal CA1 Dendrites and Dendritic Spines of the Immature and Mature Rat

Abstract: Recent studies have shown high levels of calcium in activated dendritic spines, where the smooth endoplasmic reticulum (SER) is likely to be important for regulating calcium. Here, the dimensions and organization of the SER in hippocampal spines and dendrites were measured through serial electron microscopy and three-dimensional analysis. SER of some form was found in 58% of the immature spines and in 48% of the adult spines. Less than 50% of the small spines at either age contained SER, suggesting that other mechanisms, such as cytoplasmic buffers, regulate ion fluxes within their small volumes. In contrast, >80% of the large mushroom spines of the adult had a spine apparatus, an organelle containing stacks of SER and dense-staining plates. Reconstructed SER occupied 0.001–0.022 μm3, which was only 2–3.5% of the total spine volume; however, the convoluted SER membranes had surface areas of 0.12–2.19 μm2, which were 12 to 40% of the spine surface area. Coated vesicles and multivesicular bodies occurred in some spines, suggesting local endocytotic activity. Smooth vesicles and tubules of SER were found in continuity with the spine plasma membrane and margins of the postsynaptic density (PSD), respectively, suggesting a role for the SER in the addition and recycling of spine membranes and synapses. The amount of SER in the parent dendrites was proportional to the number of spines and synapses originating along their lengths. These measurements support the hypothesis that the SER regulates the ionic and structural milieu of some, but not all, hippocampal dendritic spines.

Fine Regularity of Solutions of Elliptic Partial Differential Equations

Abstract: Preliminaries Potential theory Quasilinear equations Fine regularity theory Variational inequalities--Regularity Existence theory References Index Notation index.

Search for neutral heavy leptons produced in Z decays

Abstract: Weak isosinglet Neutral Heavy Leptons (m) have been searched for using data collected by the DELPHI detector corresponding to 3:3 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived m production giving monojet or acollinear jet topologies, and for long-lived m giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 ! m) of about 1:310−6 at 95% confidence level for m masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the m mass. The results are also interpreted in terms of limits for the single production of excited neutrinos.

Asymptotic structure of symmetry reduced general relativity

Abstract: Gravitational waves with a space-translation Killing field are considered. Because of the symmetry, the four-dimensional Einstein vacuum equations are equivalent to the three-dimensional Einstein equations with certain matter sources. This interplay between four- and three-dimensional general relativity can be exploited effectively to analyze issues pertaining to four dimensions in terms of the three-dimensional structures. An example is provided by the asymptotic structure at null infinity: While these space-times fail to be asymptotically flat in four dimensions, they can admit a regular completion at null infinity in three dimensions. This completion is used to analyze the asymptotic symmetries, introduce the analogue of the four-dimensional Bondi energy momentum, and write down a flux formula. The analysis is also of interest from a purely three-dimensional perspective because it pertains to a diffeomorphism-invariant three-dimensional field theory with local degrees of freedom, i.e., to a midisuperspace. Furthermore, because of certain peculiarities of three dimensions, the description of null infinity has a number of features that are quite surprising because they do not arise in the Bondi-Penrose description in four dimensions.

Languages, equicontinuity and attractors in cellular automata

Abstract: We consider three related classifications of cellular automata: the first is based on the complexity of languages generated by clopen partitions of the state space, i.e. on the complexity of the factor subshifts; the second is based on the concept of equicontinuity and it is a modification of the classification introduced by Gilman [9]. The third one is based on the concept of attractors and it refines the classification introduced by Hurley [16]. We show relations between these classifications and give examples of cellular automata in the intersection classes. In particular, we show that every positively expansive cellular automaton is conjugate to a one-sided subshift of finite type and that every topologically transitive cellular automaton is sensitive to initial conditions. We also construct a cellular automaton with minimal quasi-attractor, whose basin has measure zero, answering a question raised in Hurley [16].

Cytokinin-Derived Cyclin-Dependent Kinase Inhibitors: Synthesis and cdc2 Inhibitory Activity of Olomoucine and Related Compounds

Abstract: Cyclin-dependent kinases (cdk) have recently raised considerable interest in view of their essential role in the regulation of the cell division cycle. The structure−activity relationships of cdk inhibition showed that the 1, 3, and 7 positions of the purine ring must remain free, probably for a direct interaction, in which it behaves as a hydrogen bond acceptor. Olomoucine (6-(benzylamino)-2-[(2-hydroxyethyl)amino]-9-methylpurine, OC), roscovitine (6-(benzylamino)-2(R)-[[1-(hydroxymethyl)propyl]amino]-9-isopropylpurine), and other N6,2,9-trisubstituted adenines were found to exert a strong inhibitory effect on the p34cdc2/cyclin B kinase. Removal or change of the side chain at position 2 or the hydrophobic group at position 9 dramatically decreased the inhibitory activity of olomoucine or roscovitine. Inhibition of cdk with OC and related compounds clearly arrests cell proliferation of many tumor cell lines at G1/S and G2/M transitions and also triggers apoptosis in the target tumor cells in vitro and in...

Ammonia mediates communication between yeast colonies

Abstract: Under certain growth conditions unicellular organisms behave as highly organized multicellular structures For example, the fruiting bodies of myxobacteria1 and of the slime mould Dictyostelium discoideum2 form structures composed of non-dividing motile cells Although non-motile, yeasts can create organized structures, colonies in which cells communicate and act in a coordinated fashion Colony morphologies are characteristic for different species and strains Here we describe that, in addition to short-range intracolony cell–cell communication, yeasts exhibit long-distance signals between neighbouring colonies The volatile alkaline compound ammonia, transmitted by yeast colonies in pulses, has been identified as a substance mediating the intercolony signal The first alkaline pulse produced by neighbouring colonies is non-directed and is followed by acidification of the medium The second pulse seems to be enhanced and is oriented towards the neighbour colony Ammonia signalling results in growth inhibition of the facing parts of both colonies This phenomenon is observed in different yeast genera The presence of amino acids in the medium is required for ammonia production Colonies derived from the yeast Saccharomyces cerevisiae shr3 mutant, defective in localization of amino-acid permeases3, do not produce detectable amounts of ammonia and do not exhibit asymmetric growth inhibition

Distinctive molecular abnormalities in benign and malignant skin lesions: studies by Raman spectroscopy.

Abstract: — Near-infrared Fourier transform Raman spectroscopy is an analytical, nondestructive technique that provides information about the molecular structure of the investigated sample. The molecular structure of proteins and lipids differs between neoplastic and normal tissues and therefore Raman spectroscopy has been considered promising for the diagnosis of cancer. We aimed to compare the molecular structure of normal skin, benign and malignant skin lesions by the near-infrared Fourier transform Raman spectroscopy. Biopsies were obtained from the following skin lesions: skin tag, dermatofibroma, seborrhoeic keratosis, actinic keratosis, keratoacan-thoma, basal cell carcinoma, squamous cell carcinoma, nevus intradermal, nevus compositus, dysplastic nevus and lentigo maligna. Control skin was harvested from the vicinity of these lesions. In the Raman spectra, the secondary structure of the proteins was reflected by the amide vibrations of peptide bonds. The principal lipid vibrations were twisting and wagging (CH2) and CH stretching vibrations. Histologically distinguishable lesions showed specific combinations of band changes indicating alterations in the protein conformation and in the molecular structure of the lipids. Histogenetically related lesions (actinic keratosis and sqamous cell carcinoma) produced similar but not identical patterns of spectral changes. Because the examined skin lesions produced reproducible and unique spectra, we suggest that Raman spectroscopy will be useful for diagnosis of skin lesions.

The tracking calorimeter and muon detectors of the H1 experiment at Hera

Abstract: Technical aspects of the three major components of the H1 detector at the electron-proton storage ring HERA are described. This paper covers the detector status up to the end of 1994 when a major upgrading of some of its elements was undertaken. A description of the other elements of the detector and some performance figures from luminosity runs at HERA during 1993 and 1994 are given in a paper previously published in this journal.

The H1 lead/scintillating-fibre calorimeter

Abstract: The backward region of the H1 detector has been upgraded in order to provide improved measurement of the scattered electron in deep inelastic scattering events. The centerpiece of the upgrade is a high-resolution lead/scintillating-fibre calorimeter. The main design goals of the calorimeter are: good coverage of the region close to the beam pipe, high angular resolution and energy resolution of better than 2% for 30 GeV electrons. The calorimeter should be capable of providing coarse hadronic energy measurement and precise time information to suppress out-of-time background events at the first trigger level. It must be compact due to space restrictions. These requirements were fulfilled by constructing two separate calorimeter sections. The inner electromagnetic section is made of 0.5 mm scintillating plastic fibres embedded in a lead matrix. Its lead-to-fibre ratio is 2.3:1 by volume. The outer hadronic section consists of 1.0 mm diameter fibres with a lead-to-fibre ratio of 3.4:1. The mechanical construction of the new calorimeter and its assembly in the H1 detector are described.

Quantitative trait loci for cellular defects in glucose and fatty acid metabolism in hypertensive rats.

Abstract: Coronary heart disease, hypertension, non-insulin-dependent diabetes and obesity are major causes of ill health in industrial societies. Disturbances of carbohydrate and lipid metabolism are a common feature of these disorders1–9. The bases for these disturbances and their roles in disease pathogenesis are poorly understood. The spontaneously hypertensive rat (SHR), a widely used animal model of essential hypertension10, has a global defect in insulin action on glucose metabolism and shows reduced catecholamine action on lipolysis in fat cells11–14. In our study we used cellular defects in carbohydrate and lipid metabolism to dissect the genetics of defective insulin and catecholamine action in the SHR strain. In a genome screen for loci linked to insulin and catecholamine action, we identified two quantitative trait loci (QTLs) for defective insulin action, on chromosomes 4 and 12. We found that the major (and perhaps only) genetic determinant of defective control of lipolysis in SHR maps to the same region of chromosome 4. These linkage results were ascertained in at least two independent crosses. As the SHR strain manifests many of the defining features of human metabolic Syndrome X, in which hypertension associates with insulin resistance, dyslipidaemia and abdominal obesity, the identification of genes for defective insulin and catecholamine action in SHR may facilitate gene identification in this syndrome and in related human conditions, such as type-2 diabetes and familial combined hyperlipidaemia.

On embedding expanders into ℓp spaces

Abstract: In this note we show that the minimum distortion required to embed alln-point metric spaces into the Banach space lp is between (c1/p) logn and (c2/p) logn, wherec2>c1>0 are absolute constants and 1≤p

Human Escherichia coli O157:H7 infection associated with the consumption of unpasteurized goat's milk.

Abstract: A cluster of four cases of haemolytic uraemic syndrome in children occurred in Northern Bohemia, Czech Republic, between 15 June and 7 July, 1995. All the cases had significantly elevated titres of anti-O157 lipopolysaccharide (LPS) antibodies as detected by the indirect haemagglutination assay. All but one of them had drunk unpasteurized goat's milk from the same farm within the week before the disease. Evidence of E. coli O157 infection was subsequently found in 5 of 15 regular drinkers of the farm's raw goat's milk; four of them were asymptomatic, 1 had mild diarrhoea at the end of June. Verocytotoxin 2-producing E. coli O157:H7 strains of phage type 2 and of identical pulsed-field gel electrophoresis patterns were isolated from 1 of 2 farm goats and from 1 of the asymptomatic goat's milk drinkers. The frequency of anti-O157 LPS antibodies found among regular drinkers of the farm's raw goat's milk (33%; 5 of 15) was significantly higher than that found in control population (0%; none of 45) (P = 0.0005; Fisher's exact test). Our findings indicate that goats may be a reservoir of E. coli O157:H7 and a source of the infection for humans; raw goat's milk may serve as a vehicle of the pathogen transmission.

Refined technique for susceptibility resolution into ferromagnetic and paramagnetic components based on susceptibility temperature-variation measurement

Abstract: SUMMARY The measurement of the temperature variation of magnetic susceptibility can be used for the separation of ferromagnetic and paramagnetic susceptibility components. The method suggested by Hrouda (1994) assumes a hyperbolic dependence of paramagnetic, susceptibility and constant ferromagnetic susceptibility in the temperature interval used for the separation. Our new method works with a paramagnetic hyperbola again, but assumes that the ferromagnetic susceptibility temperature variation is represented by a linear relationship in the resolution interval, as indicated by the investigation of monomineralic ferromagnetic fractions.

Placental transfer of inorganic ions and water.

Abstract: There are great interspecies differences in placental structure as well as in permeability properties of the placenta. In all species, however, the placenta behaves like a low-permeability barrier containing specific mechanisms of transcellular transport for minerals and other substrates for fetal growth and metabolism. The minerals that are contained in plasma in low concentrations and that are mainly intracellular or sequestered in bones (K+, Mg2+, Ca2+, phosphate) are transported to the fetus actively. The transfer of the main extracellular ions, Na+ and Cl-, exhibit great interspecies differences. In the sheep, the transfer rates of Na+ and Cl- to the fetus are consistent with passive transfer mechanisms. In the rat, Na+ is transported to the fetus actively and the transfer of Cl- is facilitated by a carrier and/or a channel. Transfer of minerals to the fetus is controlled by a variety of mechanisms ranging from very simple ones depending on intrinsic properties of the transport systems to complex mechanisms of hormonal control. Water is presumed to move across the placenta passively. The transfer may be facilitated by the 28-kDa water channel-forming integral protein (CHIP28), which is expressed in the trophoblast syncytium.

Radiometric dating of granitic rocks from the Central Bohemian Plutonic Complex (Czech Republic): constraints on the chronology of thermal and tectonic events along the Moldanubian-Barrandian boundary

Abstract: Single-zircon dating by step-wise evaporation has established that successive granitic intrusions were emplaced in the Central Bohemian Plutonic Complex (CBPC) during a short time span of about 10 Ma. In agreement with field data, the Požary trondhjemite, emplaced early at 351 ±11 Ma and subcontemporaneously with the Sazava granodiorite dated at 349 ±12 Ma, was followed by the Blatna granodiorite at 346 ±10 Ma. The magnesium-potassium-rich units (durbachites) indicate younger ages both for the Certovo Břemeno melagranite at 343 ±6 Ma (within the CPBC) and for durbachite from the Třebic Massif (south-east of the CPBC) at 340 ±8 Ma. These data provide evidence that the sequence of intrusion and the age of the emplacement of the CBPC are comparable with those of other western Variscan batholiths (i.e. the Vosges or the French Massif Central) in similar structural environment.

The molecular basis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency in compound heterozygous patients: is there correlation between genotype and phenotype?

Abstract: Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most commonly recognized defect of mitochondrial beta-oxidation. It is potentially fatal, but shows a wide clinical spectrum. The aim of the present study was to investigate whether any correlation exists between MCAD genotype and disease phenotype. We determined the prevalence of the 14 known and seven previously unknown non-G985 mutations in 52 families with MCAD deficiency not caused by homozygosity for the prevalent G985 mutation. This showed that none of the non-G985 mutations are prevalent, and led to the identification of both disease-causing mutations in 14 families in whom both mutations had not previously been reported. We then evaluated the severity of the mutations identified in these 14 families. Using expression of mutant MCAD in Escherichia coli with or without co-overexpression of the molecular chaperonins GroESL we showed that five of the missense mutations affect the folding and/or stability of the protein, and that the residual enzyme activity of some of them could be modulated to a different extent depending on the amounts of available chaperonins. Thus, some of the missense mutations may result in relatively high levels of residual enzyme activity, whereas the mutations leading to premature stop codons will result in no residual enzyme activity. By correlating the observed types of mutations identified to the clinical/biochemical data in the 14 patients in whom we identified both disease-causing mutations, we show that a genotype/phenotype correlation in MCAD deficiency is not straightforward. Different mutations may contribute with different susceptibilities for disease precipitation, when the patient is subjected to metabolic stress, but other genetic and environmental factors may play an equally important role.

Chapter IV – Research methods for entomopathogenic Protozoa

Abstract: Publisher Summary This chapter discusses research methods for entomopathogenic protozoa. Bioassays are used to test the presence, viability, or the quantity of infective forms of a protozoan. To conduct a quantitative bioassay, spores must be counted and a dilution series made so that a known concentration of spores can be fed to the host. To calculate a dosage or concentration for any bioassay, the spores, or other infectious stages must be accurately counted. Viability can be assessed without infecting host animals. Viable microsporidian spores must be capable of germination. Spores can be fed to the host on artificial diet or their natural food. Experimentation is necessary in order to find the optimum dosage for best spore production. Nosema and Endoreticulatus spp. in Lepidoptera develop more slowly than Vairimorpha necatrix, dictating that infections be initiated earlier in larval life than was recommended for V. necatrix. Purity facilitates counting and measuring of spores and is also essential for obtaining pure extracts for biochemical studies. It is found that freeing the spores of host tissues and microbial contaminants is often necessary for storage.

Evolution of anisotropic diffusion in the developing rat corpus callosum

Abstract: Vořisek, Ivan and Eva Sykova. Evolution of anisotropic diffusion in the developing rat corpus callosum. J. Neurophysiol. 78: 912–919, 1997. Diffusion anisotropy was investigated in the developing ...

Extrusion tectonics and elevation of lower crustal metamorphic rocks in convergent orogens

Abstract: In the proposed model, weak zones of rheologically homogeneous crust, continually compressed between rigid lithospheric indenting plates, can be exhumed upward by extrusion. The rate of exhumation is governed by the rate of convergence of approaching plates and by the width of the weak deformable zone. Modeled extrusion results in near-isothermal decompression during the rapid elevation history in narrow orogenic belts for realistic plate velocities. Such pressure-temperature-time paths exhibit distinct collapsed geochronologies and record maximum metamorphic temperatures ( T max ) at the maximum burial depth ( P max ).

Peak broadening in capillary zone electrophoresis

Abstract: A review on peak broadening in capillary zone electrophoresis in free solutions is given which covers a selection of the literature published on this topic over the period mainly between 1992 and the beginning of 1997 (consisting of 71 publications). The contributions to peak dispersion from extracolumn effects (e.g. due to the finite length of the injection zone, or the aperture of the detector), from longitudinal diffusion, Joule heating, electromigration dispersion (concentration overload), a different path length of the solute ions, wall adsorption, laminar flow and the (longitudinally) homogeneous or nonhomogeneous electroosmotic flow are described. The latter may also occur when a longitudinally nonhomogeneous radial electric field is applied. Peak dispersion is depicted either by the plate-height model, or the concentration of the solute as a function of space and time is calculated either analytically or numerically by solving the equation of continuity with appropriate initial and boundary conditions and possibly completed by equations governing further quantities.

Premature Ejaculation: A psychophysiological review

Abstract: This review examines the most common male sexual dysfunction, premature ejaculation (PE). The prevalence, classification, neurophysiology, neuropharmacology, and psychological studies that offer evidence useful for understanding and clinically evaluating PE are reviewed. It is proposed that there are two basic kinds of PE: biogenic and psychogenic. Studies reporting pharmacological aspects of ejaculation offer some suggestions regarding the mechanisms of ejaculation as well as possible pharmacologic aid for some premature ejaculators. The traditional assumption among sex therapists that PE is almost universally caused by psychological features, and easily treated with sex therapy behavioral techniques, is drawn into question. Based on the limited available results from systematic investigations, behavioral treatments for PE remain beneficial to only a minority of men three years after treatment ends, suggesting that this male dysfunction is difficult to treat effectively. The mediocre results reported in treatment outcome studies may be due, in part, to reports on heterogeneous groups of premature ejaculators, for whom treatment has been generalized rather than targeted to the specific type of PE. We propose a biological and psychological etiology. With more discriminating assessment and more specific diagnosis of PE, and with treatment designed to address the particular type of PE, long-term outcome should improve for this common sexual dysfunction.