Showing papers by "Charles University in Prague published in 1980"

Study on aminopeptidase A

Abstract: A comparative biochemical and histochemical investigation of aminopeptidase A (APA, E.C. 3.4.11.7) was carried out. α-Glu-1NA, α-Glu-2NA, α-Glu-MNA and Asp-2NA were used as substrates, Fast Blue B (FBB), hexazotized new fuchsin (HNF) and hexazonium-p-rosaniline (HPR) as coupling agents. Biochemical determination of APA activity was performed in whole homogenates as well as in homogenized freeze-dried cryostat sections of many rat, guinea-pig and human organs. α-Glu-2NA proved to be the best substrate for the biochemical determination of APA activity. It displays favourable kinetic properties and abilities for spectrophotometric as well as fluorometric measurements.K m of rat kidney enzyme amounts to 0.15–0.43 mM, of rat jejunum enzyme 0.35 mM, of myocardial enzyme 0.2 mM and of rat brain enzyme 0.25 mM. The enzyme is activated by Ca2+ and inhibited by EDTA (1 mM) and 1,10-phenanthroline (1 mM). E600, DFP and PCMB (1 mM) did not influence APA activity. The activity was detected in every organ examined. Great organ and species differences were demonstrated. The highest APA activity resides in the kidney and in the small intestinal mucosa. The structural association of APA is not absolutely firm and up to 30% (depending on the organ and eventual pretreatment of sections with chloroform-acetone which impedes the leakage to some extent) escapes into the aqueous incubation solution. The highest values were recorded in phosphate and cacodylate buffers followed by citrate phosphate, citrate, Tris-HCl and acetate buffers. There were no great differences in activities measured at pH 6.5 and 7.2. For the histochemical demonstration of APA activity α-Glu-MNA is the substrate of choice.K m estimated biochemically amounts to 0.3–0.43 mM for the kidney enzyme, 0.35 mM for the rat jejunal enzyme and 0.5 mM for rat brain enzyme.K m estimated by microdensitometric measurements of the reaction product in the brush border of cells of proximal tubules and of jejunal enterocytes at the sites of villi amount to 0.6 and 0.4 mM respectively. The best results were obtained using 2–4 mM concentration of α-Glu-MNA, and satisfactory results using 0.36–0.72 mM concentration. FBB appears to be the best coupling agent in the routine. The most sensitive way to depict APA in sites with low and moderate activity is to use chloroform-acetone pretreated cryostat sections adherent to semipermeable membranes. Sites with high enzyme activity are best revealed upon incubation of chloroform-acetone pretreated cryostat sections adherent to slides. Of the unsubstituted naphthylamine derivative of α-Glu or Asp α-Glu-2NA is superior to α-Glu-1NA or Asp-2NA. In this case HPR or HNF are to be used as coupling agents in cryostat sections adherent to slides. Due to a higher decomposition rate and higher inhibitory influence of diazonium salts on APA activity in the alkaline pH range it is advisable to carry out the reaction at pH 6.5–7. The most important binding sites of APA are: The functional significance of APA is discussed in relation to the degradation of angiotensin II (endothelium, kidney) and to other brush border peptidases releasing amino acids which are absorbed (enterocytes). The histochemical demonstration is indispensable for a correct interpretation of biochemical data.

Biliary Iron Excretion in Rats following Pyridoxal Isonicotinoyl Hydrazone

Abstract: Biliary excretion of iron after administration of pyridoxal isonicotinoyl hydrazone (PIH), a recently identified effective iron-chelating agent, was investigated in rats. PIH administered both intraperitoneally and orally was shown to increase significantly 59Fe excretion into bile of rats which had previously been injected with 59Fe-transferrin to label hepatic parenchymal cells. 59Fe-PIH appears in bile as early as 15 min after chelator administration and the peak of 59Fe-radioactivity in bile is seen 1--5 h following intraperitoneal PIH injection. PIH, administered intraperitoneally, 125--250 mg/kg, increased 24 h biliary radioiron excretion about 35 times and in addition increased urinary and faecal iron excretion. When PIH was given immediately before 59Fe-transferrin, 24 h cumulative biliary 59Fe excretion was even higher. PIH was also demonstrated to increase biliary excretion of radioiron released from 59Fe-haemoglobin catabolysed in reticuloendothelial cells. The effect of PIH was confirmed by estimation of biliary iron concentration using the method of atomic absorption spectrophotometry. Repeated PIH administration to rats decreased 59Fe radioactivity in liver and kidney and increased urinary and faecal iron excretion.

Fish as a Factor Controlling Water Quality in Ponds

Abstract: Plankton of the fish pond Velký Palenec reveals a two-year periodicity, which is induced by the two year cycle of fishery management. During the two years of each cycle the biomass of carp increases considerably, while their numbers decrease. Whitefish are grown with the carp. In the first year of each cycle transparency and light penetration are high, chlorophyll and primary production of phytoplankton are low, large Daphnia are abundant and small zooplankton is scarce. In the second year of each cycle the reverse is true. Implications for regulation of water quality in shallow eutrophic bodies of water are discussed.

Study on dipeptidylpeptidase II (DPP II)

Abstract: The activity of dipeptidylpeptidase II (DPP II; E.C. 3.4.14.2) was investigated by biochemical and histochemical methods in rat, mouse and guinea-pig organs as well as in human enterobiopsies. Lys-Pro-MNA and Ala-Pro-MNA showed the most favorable kinetic properties (K m , V max) and proved to be the most sensitive substrates for biochemical and histochemical studies of DPP II. Lys-Ala-MNA is more specific and is to be preferred due to its relatively low hydrolysis by DPP IV. Lys-Ala-2NA is suitable for the biochemical determination of DPP II activity. Lys-Ala-1NA, Leu-Ala-2NA, Phe-Pro-2NA and Phe-Pro-MNA are inferior. The pH optimum of DPP II amounts to 5.5. Cacodylate, phosphate, citric acid phosphate and succinate buffers deliver similar hydrolysis rates; with citrate and acetate buffers the recorded activities are lower. The reaction can be inhibited by 1 mM DFP, 50 mM Tris and 10 mM puromycin. In the ileum of suckling rats and in human enterobiopsies similar data (K m , pH optimum, optimal substrate concentration) were obtained by biochemical determination and by quantitative histochemistry (microdensitometry) with Lys-Ala-MNA. For the histochemical demonstration of DPP II freeze-dried celloidin-coated cryostat sections are very suitable. Frozen sections of formaldehyde and glutaraldehyde fixed tissue blocks are inferior due to a higher inhibition of DPP II and less precise localization of the azo-dye. K m values and optimal pH are identical in fresh and fixed material. Fast Blue B is the best coupling agent for light microscopical localization. DPP II is present in all organs and tissues investigated. Conspicious organ and species differences exist. In adult rats the highest DPP II activity resides in the kidney, epididymis and spleen; in guinea-pigs the epididymis and testis are the most active organs. In the majority of guinea-pig organs the DPP II activity is lower than in rats. The histochemical demonstration of DPP II shows, in addition, cell-dependent differences of DPP II activity. In most cells the enzyme activity is depicted in lysosomes. Highly active are lysosomes of cells of proximal renal tubules, macrophages, thyroid cells, clear and principal cells of the epididymis of adult animals and of enterocytes of suckling rats. Lysosomes of endocrine cells of adenohypophysis, pancreaas, stomach, small intestine and nerve cells display moderate activity. In lysosomes of smooth muscle cells (intestine, myometrium), myocardial cells, and fibers of striated muscle the enzyme is also present. Spermatids and sperms of guinea-pigs are highly active. In some cases secretion granules of endocrine and exocrine gland cells display a positive reaction. Possibly the Golgi apparatus and the endoplasmic reticulum also show a positive staining in the principle cells of the rat and mouse epididymis. Furthermore, DPP II seems to be secreted into the lumen of several organs.

Interaction cross sections and negative pion multiplicities in nucleus-nucleus collisions at 4.2 GeV/c per nucleon

Abstract: Scanning results ofp, d, he, and12C interactions on Ta plates and in propane are presented. Inelastic cross sections are determined. They agree with geometrical models. General characteristics of pion multiplicity distributions are analyzed and compared with results from nucleon-nucleon interactions. Average multiplicities of negative pions are found to depend on the number of interacting beam nucleons.

A dynamometric comparison of maximum eccentric, concentric, and isometric contractions using emg and energy expenditure measurements

Abstract: In fourteen subjects we compared maximum voluntary eccentric, concentric, and isometric contractions. The maximum voluntary forces by the subjects on a weight-lifting rod when changing from standing to squatting and from squatting to standing, and during a halfway knee-bend, were measured. The rod was placed on a special stand and moved up and down at a constant speed of 8.5 m/s by a motor. Energy expenditure was measured by the indirect method and EMG activity was measured in the quadriceps femoris. It was found that the force which the muscles generated was greatest during eccentric contraction, lower during isometric and lowest during concentric contraction. Energy expenditure was slightly greater during concentric than eccentric contraction. The level of difference in EMG activity of the quadriceps femoris was statistically insignificant. An energy comparison with isometric contractions was not undertaken in view of the very complex nature of these relationships.

Nature and significance of beerbachites in the Ballantrae ophiolite, SW Scotland

Abstract: Metamorphosed abyssal ocean-floor tholeiitiic rocks, little affected by crustal contamination and probably formed at a spreading ridge, occur as a dyke complex in banded gabbros with oceanic affinities and as small tectonic lenses in serpentinised peridotite. Igneous textures and mineral assemblages have been partly or completely replaced in both dykes and gabbros. Metamorphic development of clinopyroxene and very Ti-rich hornblende at 900-1000°C was followed by a low temperature actinolite-chlorite assemblage and then by pectolite-bearing veins. Geochemical variations resulting from magmatic and metasomatic processes have been distinguished and plots of major and trace elements used to establish tectonic environment. The very high temperature metamorphic mineral growth associated with beerbachite formation indicates that the dyke rocks were in a high heat-flow environment for a considerable time, presumably in the vicinity of a spreading ridge. Obduction of a very hot slab of oceanic lithosphere accounts for the superimposed mineral assemblages.Spatially associated pillow lavas have been affected by crustal contamination and are not comagmatic with the dykes. There are petrochemical characters indicating that some of the lavas are ocean-floor basalts. For other lavas, features suggesting emplacement in a continental or an island-arc environment could also be consistent with development in a marginal basin. However, there is so much variation in composition of pillows from margin to centre, from small to large and from metasomatic activity, that their compositional fields cannot be used for discrimination of basaltic type with the same confidence as for the dykes. Accordingly, it is suggested that the petrochemistry of sheeted dyke complexes, rather than of pillow lavas, be used for this purpose in the study of ophiolites.

Density of states of substoichiometric TiN1−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 levelE F moves to higher energies and the DOS atE F,g(E F), increases linearly. The calculated LII, III X-ray spectra of Ti compare well with experiment.

Hornblende-garnet metapyroxenite beneath serpentinite in the Ballantrae complex of SW Scotland and its bearing on the depth provenance of obducted oceanic lithosphere

Abstract: Minimum T and P conditions for the crystallisation of banded amphibole (tschermakitic pargasite)-bearing garnet metapyroxenites that occur beneath and within a tectonically emplaced unit of serpentinite are 900±70°C and 10–11 (possibly 14–15) kb. This indicates both a depth provenance of at least 35–45 km for the obducted oceanic lithosphre which forms part of the ophiolite assemblage of the Ballantrae complex and also a palaeoheat-flow of at least 20°C/km. The metapyroxenites are interpreted as representing the products of subsolidus recrystallisation of a mantle accumulate pyroxenite. Together with associated amphibolites and epidote-rich mylonites formed at higher levels, they constitute a thin, transported and telescoped aureole made up of tectonic pieces of successively-formed metamorphic rocks that welded on to the base of an upward-moving and progressively-cooling peridotite slab.Estimates of temperature of recrystallisation of the metapyroxenites were obtained using the garnet-pyroxene and garnet-amphibole exchange reactions as geothermometers. Estimates of pressure were obtained from assessments of the stability fields of the amphiboles, clinopyroxenes and garnets present and of the mineral assemblages in relation to published studies on the eclogite-granulite-amphibolite facies system.

Genetic definition of a further gene region and identification of at least three different histocompatibility genes in the rat major histocompatibility system.

Abstract: Two new recombinant haplotypes of the rat major histocompatibility system,RT1, have been detected in [LEW.1A (RT1 a ) ×LEW.1W (RT1 u )] × LEW 1N(RT1 n ) segregating hybrids. Recombinantr3 carries theRTL1. A region (determining classical transplantation antigens) and theRT1.B region (determining strong mixed lymphocyte reactivity and genetic control of antipolypeptide immune responsiveness) of the RT1a parent, bur rejects RT1a skin grafts. Recombinantr4 carries theA andB regions of the RT1u parent, but rejects RT1u skin grafts. The two histocompatibility genes detected are allelic to each other. The relevant locus, designated asH-C, maps to theB-region side of theRT1 system and appears to mark a thirdRT1 gene region,RT1.C. Availability of haplotypes r3 andr4 allowed the definition of a histocompatibility locus in theB region,H-B. The products ofH-C, H-B and of the previously describedH-A gene vary in antigenic strength.

The Dirichlet Problem for Harmonic Functions

Abstract: (1980). The Dirichlet Problem for Harmonic Functions. The American Mathematical Monthly: Vol. 87, No. 8, pp. 621-628.

Niemann-Pick disease. Analysis of liver tissue in sphingomyelinase-deficient patients.

Abstract: The results of a complex analysis of liver tissue are presented (four biopsy and two autopsy samples) obtained from six patients with Niemann-Pick disease (NPD) with a gross deficiency of sphingomyelinase (SMase) accompanied by a typical increase in sphingomyelin (SM). There were five cases of NPD type A (four of them with an atypical, prolonged course) and one case of type B. By means of lipid histochemistry it was possible to demonstrate SM storage both in hepatocytes and in the reticuloendothelial system (RES) of the liver (Kupffer cells and portal macrophages) and to show in two siblings with NPD type A a so-far undescribed centrilobular storage pattern. Enzyme histochemistry revealed a secondary deficit of nonspecific esterase activity and acid β-galactosidase in liver storage macrophages and varying degrees of suppression of hepatocytic enzyme activities as a reaction to lipid storage of sudden onset. Ultrastructurally, it was possible to demonstrate cholesterol in lysosomes by using digitonin fixation, the involvement of Ito cells in lipid storage, the aggregation of storage lysosomes with certain other organelles and their occasional connections with the endoplasmic reticulum. The problems of possible lipid extraction during processing were considered as a cause of pronounced lysosomal electron-lucidity and of the ultrastructural identification of the participating lipopigment. The significance of the findings is discussed in relation to the existing classification and, particularly, to the stored lipid dilemma of cases of NPD type C.

Asymptotic representation of M-estimators of location

Abstract: Let T n be an M-estimator of location parameter ϑ generated by a function ψ. It is shown, under some assumptions on ψ and on the underlying distribution F, that theren exists a constant in the case of absolutely continuous ψ while it is of the order if ψ has some jumps; both orders are exact. The asvmntotic representations follow from invariance principles which are proved for some processes related to T n ; these invariance principles are applicable to more problems.

Duality in interval linear programming

Abstract: Publisher Summary This chapter presents a duality theorem for interval linear programming and also presents various forms of optimality criteria. It also presents a proof of the duality theorem for the problems (P) and (D). It is found that if both (P) and (D) are feasible, then they both have optimal solutions and have a common optimal value. If one of the problems (P) or (D) is infeasible, then the second one is either infeasible or unbounded. It is found that if (P) is infeasible, then so is (Po), and the duality theorem states that (Do) is infeasible or unbounded. A Parkas-type theorem can be derived directly from the duality theorem.

On Stochastic Models of the Excitation Transfer in Molecular Crystals The Lineshape of the Phononless Exciton Band

Abstract: In the Sumi model describing the effect of the exciton—phonon coupling on excitons in molecular crystals by a stochastic Markoff-Gauss process with a site-diagonal potential with a time-dependent exponentially decaying correlation function, the phononless exciton lineshape is investigated. It is proved that in general, cumulants of all even orders contribute to the optical lineshape function due to non-commutativity of relevant operators at different times. So the recent result by Blumen and Silbey is shown to be just an approximation neglecting all but second-order cumulants. The fourth-order correction is calculated and it is proved that starting from this order of approximation, the free-exciton density of states does not give a sufficient information necessary to deduce the optical lineshape function. Mit dem Sumi-Modell, das den Einflus der Exziton—Phonon-Kopplung auf Exzitonen in Molekulkristallen durch einen stochastischen Markoff-Gaus-Prozes beschreibt mit einem platzdiagonalen Potential und einer zeitabhangigen, exponentiell abfallenden Korrelationsfunktion, wird die Null-Phonon-Exzitonenlinienform untersucht. Es wird bestatigt, das im allgemeinen alle Terme von gerader Ordnung zur optischen Linienformfunktion infolge der Nichtkommutativitat der relevanten Operatoren zu verschiedenen Zeiten beitragen. So wird gezeigt, das neuere Ergebnisse von Blumen und Silbey gerade eine Naherung darstellen, die alle Terme bis auf die zweiter Ordnung vernachlassigt. Die Korrektur vierter Ordnung wird berechnet und es wird gefunden, das ausgehend von dieser Naherungsordnung, die Zustandsdichte der freien Exzitonen nicht genugend Informationen liefert, die notwendig sind, um die optische Linienformfunktion abzuleiten.