Showing papers by "Charles University in Prague published in 1979"

Studies on dipeptidyl(amino)peptidase IV (glycyl-proline naphthylamidase). II. Blood vessels.

Abstract: The activity of dipeptidyl(amino)peptidase IV (DAP IV, glycylproline naphthylamidase) was discovered in the endothelial cells of the venous part of capillary bed and of small venules of many organs of the rat, mini-pig, rabbit, cock as well as man. In aortae, large arteries and veins only a portion of vase vasorum displays a positive reaction. Glycyl-proline-4-methoxy-2-naphthylamide (Gly-Pro-MNA) is the substrate of choice both from the viewpoint of enzyme kinetics as well as localization. Phenylalanyl-proline-4-methoxy-2-naphthylamide (Phe-Pro-MNA) is cleaved less easily, however, it enables a good localization. 1- and 2-naphthylamine derivatives of glycylproline display better kinetic properties than Phe-Pro-MNA, however they enable a satisfactory localization under special conditions only.

Sister-chromatid exchanges and chromosal breakage in patients treated with cytostatics.

Abstract: The frequency of structural chromosomal rearrangements and sister-chromatid exchanges (SCEs) was investigated in short-term phytohemagglutinin-stimulated lymphocyte cultures by means of bromodeoxyuridine substitution and fluorescence plus Giemsa (FPG) staining technique. Both these parameters were significantly increased in patients treated with comparatively low doses of cyclophosphamide, busulphan and adriamycin. The increased SCE rate was proportional to the number of chromosome breaks, the ratio of SCE to breaks being about 100:1. The increase in the SCE number was maintained for several months after the termination of cytostatic therapy, when the conventional analysis of chromosome breaks yielded normal results. Normal SCE values were obtained in two patients treated with low doses of fluorouracil.

Effective iron chelation following oral administration of an isoniazid-pyridoxal hydrazone.

Abstract: When isoniazid and pyridoxal are mixed in equimolar quantities a hydrazone is formed which is able to complex with iron. The oral administration of this compound to rats in single doses of 25--100 mg/kg leads to an increase in faecal iron excretion up to 8 times the normal level. In tissue culture the compound is able to remove iron from Chang cells. The results suggest that this compound may be of potential value for the oral therapy of iron overload.

A reduct-and-closure algorithm for graphs

Abstract: The transitive closure of (V,E) is the graph Clos(V,E) = (V,C) where (x,y) £C iff there is a path p:x-~y in (V,E) with ILpil>0. The transitive reduct Red(V,E) of an acyclic graph (V,E) is the least graph (V,R) with Clos(V,R) = Clos(V,E) . The number o f e l emen t s o f a f i n i t e s e t X w i l l be denoted t h r o u ghout by IX1 . If Alg is an algorithm processing graphs, Time (Alg(V,E)) denotes the number of steps taken by Alg to process (V,E) . We write Time(Alg(V,E)) ~ 0(f(V,E)) , for a function f:K -~ N from some class of graphs to the non-negative integers N , if there exists ceN such that the inequality Time(Alg(V,E)) ~ c.f(V,E) holds for all (V,E)~ K . We then also say that Alg needs O(f(V,E)) time to process a member (V,E) of K , or that Alg has the time complexity O(f) on K . The main objective of the present note is to describe an algorithm Recl computing simultaneously both Red(V,E) and Clos(V,E) , for (V,E) acyclic, with the time complexity Time(Recl(V,E)) ~ O(IV I .~R~+ +lE l ) comparing f a v o r a b l y wi th the a l g o r i t h m s d e s c r i b e d i n [1~ , [2J , [ 5S , [6]. We also describe some useful modifications of this basic algorithm.

Density of states of substoichiometric TiC1-x

Abstract: The electronic states of substoichiometric TiN1−x are studied by the CPA method and both the partial and total densities of states (DOS) are calculated. The results reveal that with increasing vacancy concentrationx the Fermi levelEF moves to higher energies and the DOS atEF,g(EF), increases linearly. The calculated LII, IIIX-ray spectra of Ti compare well with experiment.

Changes in ATPase and SDH reactions of the rat extrafusal and intrafusal muscle fibres after preincubations at different pH.

Abstract: The dependence of adenosine-triphosphatase (ATPase) and succinic dehydrogenase (SDH) histochemical reactions on the pH of the preincubation medium was studied in serial cross sections of 1- to 6-month-old rat extensor digitorum longus (EDL) and soleus (SOL) muscles. The use of a wide spectrum of pH values confirmed the previous results showing that: (1) according to their ATPase and SDH reactions 3 types of extrafusal muscle fibres, i.e., fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG) and slow-twitch oxidative (SO) and 3 types of intrafusal muscle fibres, i.e. typical and intermediate nuclear bag fibres and nuclear chain fibres were observed; (2) only acid preincubation (pH 4.35) is necessary to demonstrate the reversal of the ATPase reaction; while (3) alkali preincubation (pH 10.4) does not provide any new important information as compared with ATPase without preincubation. Furthermore, it was shown that: (4) fast-twitch muscle fibres exhibited high ATPase activity on preincubations at pH 4.9 to 10.4, slow-twitch fibres had very high ATPase activity on preincubation at pH 4.3 and 4.5; (5) after preincubation at pH 4.5 two types of FOG fibres were observed, differing in their ATPase activity; (6) in both muscles there were fibres with intermediate ATPase activity both after acid and/or alkali preincubations; (7) the intrafusal muscle fibres exhibited some specific characteristics when compared with extrafusal fibres. In contrast to the ATPase reactions, SDH activity was decreased equally, in both extra- and intrafusal fibres, with increasing acidity and alkality of the preincubation medium.

Ray amplitudes of seismic body waves in laterally inhomogeneous media

Abstract: Summary. The most complicated part in the computation of ray amplitudes of seismic body waves in laterally inhomogeneous media with curved interfaces lies in the evaluation of the geometrical spreading. Geometrical spreading can be simply expressed in terms of the Jacobian J of the transformation from the Cartesian into ray coordinates. Several systems of ordinary differential equations to compute the function J are suggested. For general three-dimensional media, in which the velocity changes with all the three spatial coordinates, a system of three non-linear ordinary differential equations of the first order is derived. If the velocity does not depend on one coordinate, the system of equations reduces to only one non-linear differential equation. The initial conditions for these differential equations at point (or line) source and at points of intersection of the ray with curved interfaces are presented.

On the theories of the interacting perturbations of the Reissner-Nordström black hole

Abstract: A complete account of the Hamiltonian approach to the coupled perturbations of the Reissner-Nordstrom black hole, initiated by Moncrief, is given. All Hamiltonian equations are expressed explicitly in suitable forms; the metric and electromagnetic field perturbations are found in terms of Moncrief's gauge invariant canonical variables in the Regge-Wheeler gauge. The basic (both tetrad and coordinate) gauge invariant scalars occurring in the perturbation studies based on the Newman-Penrose formalism are then related to Moncrief's variables. The strikingly simple relations obtained enable us to show that the fundamental pair of decoupled equations, derived recently within the Newman-Penrose formalism by Chandrasekhar, can be cast into gauge invariant form, and that it can be obtained from Moncrief's formalism.

Klinefelter's syndrome: Sexual development and activity

Abstract: Determination of plasma testosterone in 105 patients with Klinefelter's syndrome 16–45 years of age revealed that at each 5-year age interval values of male hormone were lower than in a control group of 25 normal adolescents and 85 fertile and potent men Analysis of heterosexual development by means of the HTDM Questionnaire in 110 patients with Klinefelter's syndrome age 21–40 years, who were examined mainly for sterility and signs of imperfect somatosexual development, revealed a distinct retardation of sociosexual development compared to that of 325 normozoospermic men from sterile marriages For eight out of 12 items on the HTDM Questionnaire the differences were statistically significant Examination by means of the SAM Questionnaire in these two groups revealed that the sexual activity of examinees with Klinefelter's syndrome was significantly weaker than that of fertile and potent men For 15 out of 18 items on the SAM Questionnaire the differences were statistically significant

Ontogeny of active avoidance in the rat: Learning and memory

Abstract: Ontogenetic development of active avoidance learning, extinction and retention was studied in rats. The learning of a 1-way active avoidance was most rapid between Weeks 4 and 6, although some slight gender-related differences were evident. No such unambiguous development was detected in forced extinction. The 24-hr retention of avoidance peaked at the age of 4 weeks whereas 1-month retention was best in animals trained at the age of 8 weeks. The retrieval of memory trace also had best values at these ages. Retention of forced extinction was found to peak in 6-week animals. The existence of developmental "critical periods" must be considered cautiously as various functions have different time courses depending upon the chosen parameters in assessment.

Ultrastructural evidence of myofibroblasts in pseudomalignant myositis ossificans.

Abstract: Seven cases of pseudomalignant ossifying myositis with a typical clinical symptomatology have been reported. None of the cases had experienced an injury. All the lesions were intramuscular and all of them showed a zonal arrangement. Electron microscopy in three cases allowed the demonstration of cells showing morphological features of myofibroblasts and monocytic cells of the macrophage type. These previously unreported features together with the zonal pattern of the lesions indicate their reparative nature.

The histochemical demonstration of brush border endopeptidase.

Abstract: A histochemical method for the demonstration of a brush border endopeptidase is described based on results of biochemical and histochemical experiments. The substrate of choice is Glut-Ala-Ala-Ala-MNA which displays a very good localization ability and suitable kinetic properties. Km estimated in rat kidney homogenate amounts to 2.35×10−4 M. pH optimum of this endopeptidase associated with the brush border membrane is in the alkaline range. The activity is dependent on the buffer used. In phosphate and cacodylate buffers of pH 7.2 about 30% lower activity in rat kidney and about 25% lower activity in rat small intestine than in Tris-HCl buffer of the same pH was found. The most suitable diazonium salt for the detection “in situ” is Fast Blue B. It inhibits the endopeptidase activity of rat kidney by about 85% at pH 7.2 and by about 55% at pH 6.0. The best results are obtained in cryostat sections adherent to semipermeable membranes treated with chloroform-acetone before the incubation. A microdensitometric evaluation of the reaction product is possible and results are in good agreement with those of the biochemical determination. When Suc-Ala-Ala-Ala-INA is used as substrate hexazonium-p-rosaniline is the most suitable coupling agent although it inhibits more than Fast Blue B. The reaction using acylated trialanyl naphthylamides as substrates runs in two steps. Endopeptidase sets free Ala-NA which is attacked by aminopeptidase M. Aminopeptidase M is not reaction rate or localization limiting factor because its activity in the brush border is very high and the enzyme is anchored to the cell membrane very closely to endopeptidase. In homogenates of rat kidney and jejunal mucosa the endopeptidase activity was inhibited by EDTA (2×10−3M) by 75% in the kidney and by 68% in the jejunum, by DFP (10−3M) by 41% in the kidney and by 35% in the intestine, by Mn2+ (5×10−3M) by 25% in the kidney and by 30% in the intestine. No inhibition was exerted by E 600. In sections the results were similar. 1,10-phenanthroline (10−2M) caused a substantial inhibition.

Computer-aided numerical identification of gram negative fermentative rods on a desk-top computer.

Abstract: One hundred and sixty-three strains of Gram negative fermentative rods isolated from humans and 60 isolated from diseased snails were identified by a conventional method and by numerical identification on a desk-top computer. The two methods gave the same identities with 133 ‘human strains’ and 33 ‘snail strains’. The possible sources of the differences in identifications are discussed. The study showed that numerical identification done on a desk-top computer can be a useful method for routine medical microbiological laboratories.

Regional distribution of membrane-bound gamma-glutamyl transpeptidase activity in mouse brain. Comparison with rabbit brain.

Abstract: Activity of membrane-bound gamma-glutamyl transpeptidase (gamma-GTP) was examined in various regions of mouse brain, in capillaries of the cerebral cortex and in telencephalic choroid plexuses. The level of activity in the capillaries was double and that of the choroid plexus nine times that of the gamma-GTP activity found in the brain, septum, hippocampus, hypothalamus, thalamus, cerebellum, frontal cortex, pons, medulla oblongata, and amygdala. Histochemically the gamma-GTP activity was demonstrated in the surface membranes of choroidal cells and in the endothelium of small capillaries. The activities of gamma-GTP of cerebral cortex, choroid plexus, and capillaries from rabbit were 5--17 times greater than those from corresponding areas of mouse brain. While 30 mM methionine stimulated (in vitro) the enzyme from mouse brain, no such effect was observed with the enzyme activity from rabbit brain. The gamma-GTP activity from the capillaries of cerebral cortex of both mouse and rabbit was not affected by the presence of methionine. These findings suggest existence of differences in the specificity of gamma-GTP activity in these two species.

From finite to infinite crystals: Some electronic properties of BCC clusters

Abstract: Using results obtained within the framework of the tight binding nearest neighbour approximation (Bilek O.,Skala L., Czech. J. Phys.B 28 (1978), 1003) the analytical formulae for the band width, binding energy per atom, charge orders and bond orders of bcc clusters having a rectangular parallelepiped geometry are given. Numerical results for the number of atoms in the cluster in the range 9-2×106 illustrate the convergence of these properties. The asymptotical form of the formulae yields further detailed information. The band width and bond orders converge more quickly than the binding energy while the charge orders are equal to unity independently of the size of the cluster.