Showing papers by "Academy of Sciences of the Czech Republic published in 1975"

On the determination of χ l ,η +−0 AND η 000 from bubble chamber measurements

Abstract: Formulae for time distribution of neutral kaon decay in material medium are derived and discussed. Essential effects of the medium are emphasized which should be taken into account in the discussion of the bubble chamber experiments in which theΔS=ΔQ rule and CP-violation are studied.

The development of various generations of nephrons during postnatal ontogenesis in the rat.

Abstract: The structural development of individual nephrons has been investigated in the kidneys of young rats by microdissection. Superficial, intercortical and juxtamedullary nephrons in Wistar-Konarovice rats aged 2 to 60 days have been followed. At two and five days of age the superficial nephrons were in an early stage of anatomical development. At this time intercortical and juxtamedullary nephrons were more developed, and basically resembled similar structures in adult animals with the exception that the loops of Henle did not have a thin ascending limb. At ten days of age all three types of nephrons were differentiated with the exception that the intercortical nephrons did not possess a thin ascending limb of Henle's loop. At selected stages of development there appears to be a direct relation between the length of the superficial nephrons and the weight of the kidney. Since individual segments of these nephrons do not grow at the same proportional rate, this relationship does not hold when compared to kidney weight.

Regional and Systemic Haemodynamic Effects of Some Vasopressins: Structural Features of the Hormone which Prolong Activity

Abstract: . Cardiac output and regional blood flows to myocardium, gut, uterus and kidney were determined in anaesthetised female rats by a single injection of 86RbCl. The haemodynamic responses were measured at various time intervals up to 2 h after single I. V. injections of lysine-vasopressin and the following of its analogues: a) with extended peptide chains at the N-terminal (including “hormonogens”) Na-glycyl-glycyl-glycyl-lysine-vasopressin, Na-glycyl-glycyl-glycyl-arginine-vasopressin and Na-D-valyl-lysine-vasopressin, b) “carba” modifications desamino-carba6-arginine-vasopressin, desamino-carba6-D-arginine8-vasopressin, desamino-carba6-ornithine8-vasopressin, desamino-dicarba-arginine-vasopressin and c) other steric alterations - desamino-D-arginine8-vasopressin and desamino-N-methylarginine8-vasopressin. Sub-pressor doses of lysine-vasopressin were followed by marked reductions in gut and uterus blood flows which reached a peak at 10 min. and had completely receded by 60 min. The presence of steric alterations in the C-terminal tripeptide of the molecule- D-arginine or N-methylarginine in sequence position 8- practically completely eliminated vascular activity. The same was true for Na-D-valyl-lysine-vasopressin. None of the latter three analogues showed any inhibitor properties to the action of lysine-vasopressin. The two hormonogens (triglycyl N-terminal extensions) had to be given in doses 10 times greater to obtain a vasoconstrictor effect in gut and uterus equivalent in amplitude to that of lysine-vasopressin, but this effect was still present to the same degree 2 h later with the hormonogen of lysine-vasopressin, and was only starting to return to baseline values at the same time with the arginine-vasopressin hormonogen. The vascular potency of both mono-carba L-analogues was higher than that of lysine-vasopressin, and the effect was as prolonged as with the hormonogens. The dicarba analogue also showed a prolonged action, but with much reduced potency. No significant changes in renal or myocardial blood flows were observed at all. Molecular features of vasopressin smooth muscle activity were discussed, and a receptor model was proposed. It was suggested that the -S-S-, -SCH2 and -CH2CH2-bridges in the above analogues are not directly bound in the peptide-receptor complex and constitute the limiting factor determining complex duration, or persistence of the active peptide in the “receptor compartment”. These results provide an experimental basis for possible clinical application of triglycyl-vasopressin and carba-vasopressin in bleeding from both gut and uterus and for induction of menstruation.

Theory of strengthening of alpha titanium by interstitial solutes

Abstract: It is assumed that the core structure of screw dislocations in the h.c.p. lattice of α-Ti can be described by a sessile splitting on the prism plane and on the first order pyramidal plane simultaneously and that slip can proceed after its transformation into a glissile configuration on the prism plane. The strengthening by interstitial solutes O, N, C is explained by their impeding role in these sessile-glissile transformations. A good agreement between the theoretical temperature dependences of the effective stress for different interstitial content and the experimental values can be reached if the effect of impurities on the stacking fault energies is also taken into account. The similarity between the role of screw dislocations in the low temperature deformation of h.c.p. metals with more slip systems operating and of b.c.c. metals is stressed.

NMR study of organosilicon compounds. III—Silicon-29, nitrogen-14, carbon-13 and proton NMR spectra of silylakylamines†

Abstract: 29Si, 14N 13C and 1H NMR data are presented for a series of homologous (methylethoxysilyl)alkylamines of the type (CH3)3−n(C2H5O)nSi(CH2)mNH2(n=o to 3; m = 1 to 4). The measured 13C and 1H chemical shifts correlate with the total net charges QA on the corressponding atoms, estimated by the Del Re method. 14N and 29Si chemical shifts which do not show simple linear relationships to the charges are found to correlate with the relative basicities of the compounds. The influence of the remote substituent (NH2 and others) on the 29Si chemical shifts is shown to depend on the number and nature of substituents directly on the silicon atom. Argyments for d-orbital participation in the SiO bounds are given. The chemical shifts of 29Si, 14N and 13C nuclei are not consistent with the fromation of intramolecular ‘long bonds’ between the solicon and nitrogen atoms in aliphatic silymethylamines.

Lattice Defects in Manganese-Doped Sb2Te3 Crystals

Abstract: On Sb2Te3 crystals, both pure and doped with manganese, the IR reflectivity, the temperature dependence of the magnetic susceptibility, and the EPR spectrum at 77 K were investigated. The shift of the reflectivity minimum towards shorter wavelengths for samples with increasing concentration of Mn atoms shows that the introduction of Mn atoms into the Sb2Te3 lattice results in an increase of the hole concentration, with approximately one hole per one Mn atom. The temperature dependence of the magnetic susceptibility and the EPR spectrum lead to the conclusion that each Mn atom corresponds to an unpaired electron. Hence, one can argue that the d-orbits of a Mn atom in the octahedral field of six tellurium atoms are split into a triply degenerate t2g-orbit and a doubly degenerate eg-orbit, and occupied in such a way that the d-electrons of Mn realize a low-spin arrangement (t2g)5 (eg)0. The discussion, based on a bonding model due to Krebs, revealed that the most probable defects in Sb2Te3 lattice are the substitutional defects, where manganese atoms occupy vacant antimony sites. This defect is evidently accompanied by a single negative charge which is compensated by a hole. Die Reflektivitat im IR-Bereich, die Temperaturabhangigkeit der magnetischen Suszeptibilitat und das EPR-Spektrum bei 77 K wurden an reinen Sb2Te3-Einkristallen und an Einkristallen mit Mn-Beimischungen gemessen. Die Verschiebung des Reflektivitats-minimums zu kurzeren Wellenlangen zeigt. das der Einbau von Mn-Atomen in das Gitter eine Erhohung der Locherkonzentration verursacht und das jedem eingebauten Mn-Atom ein Loch entspricht. Die magnetischen Messungen zeigen, das das eingebaute Mn-Atom ein nichtgepaartes Elektron tragt. Daraus kann man schliesen, das die d-Orbitale des Mn-Atoms im oktaedrischen Felde der umgebenden Te-Atome in ein dreifach entartetes t2g-Orbital und in ein zweifach entartetes eg-Orbital aufgespalten sind und das die Spinanordnung durch (t2g)5 (eg)0 gegeben ist. Zur weiteren Diskussion wird das von Krebs ent-worfene Modell der Bindungen zwischen Atomen benutzt. Es zeigt sich, das die wahrschein-lichsten Fehlstellen im Sb2Te3-Gitter Substitutionsfehlstellen sind, d. h. ein Mn-Atom wird von einem Sb-Atom substituiert. Eine solche Fehlstelle hat eine negative Ladung, die durch das dabei entstandene Loch kompensiert wird.

Activated human retinal microglia under pathological conditions.

Abstract: Six pathological human retinas were studied in order to establish changes, migration, and other reactions of retinal microglia. The different morphological features of other retinal macrophages are also described. Hortega silver carbonate stain was used for this study. This investigation aided in answering some questions on the active movements of microglia elements and other details under discussion.

Die Wirkung von Triglycyl-Lysin-Vasopressin auf Kontrollpersonen und Patienten mit Blutungen des oberen Gastrointestinaltraktes

Abstract: Nα-glycyl-glycyl-glycyl-(8-Lysin)-Vasopressin ist ein Hormonanalog mit prolongierter pharmakologischer Wirkung aufgrund der Tatsache, das in vivo das aktive Nonapeptid nur langsam durch enzymatische Spaltung freigesetzt wird. Es wurde bei 5 Kontrollpersonen und 14 im oberen Gastrointestinaltrakt blutenden Patienten angewandt. Die Kontrollpersonen zeigten bei einer Dosierung von 100 µg/kg Korpergewicht fur langere Zeit einen erhohten Blutdruck, begleitet von einem vergroserten Herzminutenvolumen, ohne EKG-Hinweis auf Myocardtoxizitat. 13 der 14 blutenden Patienten zeigten nicht nur eine pressorische Wirkung sowie eine hamodynamische und klinische Besserung nach 20–100 µg/kg, sondern auch deutliche Zeichen von Blutstillung sowohl bei peptischen Ulcera als auch Oesophagusvaricen.

Ionization waves (moving striations) in a low pressure helium discharge — results of measurements compared with a direct solution of the electron Boltzmann equation

Abstract: The Boltzmann equation expanded in the angular dependence in the velocity space is solved numerically in one-dimensional approximation to obtain the perturbed distribution function. This perturbed distribution is integrated to construct the rate coefficients entering the atomic ion and the metastable continuity equations. From these balance equations the dispersion equations of the fast as well as slow ionization wave varieties are recovered. The space resonances of the electron gas described earlier give rise to the fast s and slow s' wave varieties observed in the positive column of the low current helium DC discharge. The existence regions of these waves are numerically evaluated and compared with experiment. Furthermore, the results on the wave phase velocities and dependence of the characteristic potential on the electric field are confronted with the experimental data. The theory, which involves no free or adjustable parameters, renders a resonable agreement in some points. Possible reasons for the observed discrepancies are also discussed.

Cephalic and digital vasomotor orienting responses: the effect of stimulus intensity and rise time.

Abstract: This study evaluated the effects of rise-decay time and intensity (70dB; 90dB| of pure tones on cephalic and finger vascular responses. Cephalic dilation responses similar to those reported by Sokolov were obtained, as well as cephalic dilation response*, which were interpreted as attributable to startle. Cephalic constriction responses were observed at 90dB only and occurred more frequently for slow rise than for fast rise tunes which were conducive to the production of startle. The negative results with respect to (he cephalic vasomotor response, reported by most American investigators, can be rationalized from the results of the present study.

FMR in surface oxidized iron single crystals

Abstract: Ferromagnetic resonance absorption has been observed at room temperature in iron single crystals of whisker type (grown along [100] direction). The surface of the samples has been oxidized in air at 760 Torr at approx. 350 °C for periods up to 240 min. With the increasing degree of oxidation the resonance linewidth broadens and the resonance field shifts to lower values. Moreover, in oxidized samples an additional resonance peak situated above, the main resonance occurs, with intensity, position and linewidth depending on the period of oxidation. The ferrimagnetic resonance absorption in the iron oxide surface layer could be responsible for the occurence of this peak.

On the disaccommodation of the complex susceptibility in an alternating magnetic field

Abstract: Neel's theory is used to derive the expression describing the disaccommodation of the complex initial susceptibility in an alternating field in dependence on temperature, frequency of the field and concentration of relaxators. In addition to the disaccommodation of the real part the relaxation of the imaginary part of the initial susceptibility and that of the loss angle are predicted. The physical meaning of derived expressions have been discussed and the phenomena which can influence the aftereffect measurements have been mentioned.

Further studies on the genetic basis of the generation of cml in mice

Abstract: SUMMARY Twenty-six combinations of C57BL/10 congenic mice involving incompatibilities in the I region and the H-2K or H-2D regions of the major histocompatibility complex were studied in a cell-mediated lympholysis assay (CML). All combinations were positive; however, six were unidirectional. Three of these were consistent with the mapping of an effector cell stimulating locus (ECS) between the IB and IC sub-regions. Possible reasons are given for the negativity of CML in I/H-2K or H-2D region incompatible combinations. A statistical method used to analyse the data is described.

On the establishment of adsorption equilibrium in n-butylamine titrations of the surface acidity

Abstract: Using benzeneazodiphenylamine and Dimethyl Yellow as indicators, the difficulties associated with the establishment of an adsorption equlibrium between n-butylamine, the indicator and the acid centers of the catalyst in their titration by the Benesi method are demonstrated. The concentration of the amine affects the experimental values of surface acidity.

Magnetic surface anisotropy and surface states of a semiinfinite crystal of ferromagnetic transition metals

Abstract: The main aim of the present paper is to estimate the magnitude of the magnetic surface anisotropy of a semiinfinite intinerant ferromagnet by calculating the contribution of surface states to the surface energy. Surface states are investigated without and with the consideration of the spin-orbit interaction (which causes the dependence of the sample energy on the magnetization direction). Different more or less realistic estimates of the surface parameters are used. Only threeT2g 3d-bands described in the tight-binding approximation are used to represent a 3d transition metal. Numerical calculation was performed for the (100) Ni surface. For this case the presence of the axial magnetic surface anisotropy was confirmed. The surface anisotropy constant corresponding to the surface-state contribution is estimated to be −0·2 to −0·3 erg/cm2.

The amino-terminal sequence of the VHIII subgroup of pooled porcine IgG.

Abstract: Pig gamma-chains contain a significant fraction of the unblocked VHIII variable region subgroup. The amino terminal sequence (30 residues) was found to be uniform and more than 90% homologous with the prototype sequence of the human VHIII subgroup. An additional VHIII phylogenetically associated residue, glutamic acid in position 2 was identified in these porcine heavy chains.

Neurophysin binding and natriuretic peptides from the posterior pituitary

Abstract: A qualitative technique of gel filtration on Sephadex@ G-25 has been used to study binding of variously altered vasopressin (VP) and oxytocin (OT) peptide molecules to highly purified bovine neurophysin I1 (Np II).1*2 The basic technique (FIGURE 1) consists of using calibrated columns with known fractional elution positions of Np I1 alone and the small peptides alone. Binding experiments involved subjecting equimolar mixtures of Np I1 and the small peptides at a binding pH of 5.8 in pyridine-acetate buffer (selected so that subsequent freeze-drying of eluted fractions would eliminate solvent contamination) to gel filtration in the same buffer. Np I1 fractions and known fractions for the small peptide alone were pooled separately, and criteria of binding were the following : (1) ODmo to estimate peptide content in the two fraction pools; (2) dansylation analysis of the N-terminal residue in each fraction; (3) assay of biological activity (usually pressor, also uterotonic) in each fraction after freeze-drying and redissolving in water; (4) dissolving of the freeze-dried Np I1 fractions in 0.1 M HCOOH-dissociation conditions-followed by gel filtration on the same calibrated column, this time in 0.1 M HCOOH, and retesting of the same fractional positions as above to criteria 1-3. Of course, if the small peptide had a very low biological activity, criterion 3 was of little value. These experiments dealt with the following categories of structural alteration in the neurohypophyseal hormones: (a) hormonogen forms, in which the lysine-vasopressin (LVP) chain was extended by 1-3 additional residues (Leu, Phe Gly, Gly-Gly, Gly-Gly-Gly) a t the N-terminal, the new analogs all having an Nh-amino group present; (b) LVP shortened at the C-terminal: des-[9dycine amidel, des-[84ysine]des-[ g-glycine amidel, and pressinamide, or des-(Pro-Lys-Gly-NH2 ] with C-terminal Cys in amide form; (c) alterations in the disulfide bridge: l-monocarba (CH2 S), 6-monocarba (SCH21, dicarba (CH2CH2) and opening of the SS bond by conversion (with 13-mercaptoethanol and CH31) to SCH3 groups on both 1and 6-Cys; (d) variations in the p-position of the aromatic ring in residue 2: instead of the OH of Tyr, p-methoxy and pethoxy groups, and Phe with only a proton at this position. Sources, and details of the preparation of both the analogs and hormone fragments, have been presented e l ~ e w h e r e . ~ ~

An analytical approach to the distribution function of electrons in the molecular oxygen discharge

Abstract: Analytical expressions for the electron distribution function and the kinetic coefficients in the molecular oxygen glow discharge are given. The relative importance of the various collisional processes in evaluation of some experimentally measured quantities is discussed as well as the validity of the present results.