Showing papers by "Jožef Stefan Institute published in 1980"

Study on the Hydration of Oriented DNA by the Neutron Scattering Technique

Abstract: Three different experimental methods of neutron scattering have been employed in order to study the hydration problem in various forms of oriented DNA fibrils. It is found that the water of hydration forms an internal structure in the samples and that this structure is not very strongly coupled to the macromolecular surface. The existence of hydrogen bonds between water molecules is clearly demonstrated. Qualitative agreement between calculated structure factors and measured "elastic" diffraction patterns for a dry DNA sample is obtained. In order to reproduce the measured diffraction pattern for a wet sample it is not enough to include only the water molecules within the first hydration shell in a structure factor calculation. It is concluded that by employing the high resolution "elastic" diffraction technique it should be possible to obtain detailed information on the problem of hydration in DNA.

Intracellular neutral proteinases and their inhibitors

Abstract: Elastases and two types of chymotrypsin-like neutral proteinases were isolated from bovine spleen. The elastase isoenzymes have molecular weights of 27 000 and 22 000. These enzymes hydrolyze a synthetic substrate of elastase N-Boc-L-Ala-ONp (Km 0.19 mM) and protein substrates. Current experiments on spleen chymotrypsin-like neutral proteinases-histonases indicate that bovine spleen contains two different types of these enzymes. Histonase 1 has a molecular weight of about 30 000 and histonase 2 of about 15 000. The former degrades a synthetic substrate of chymotrypsin Bz-Tyr-OEt (Km 1.92 mM) and protein substrates, and is very similar to cathepsin G, whereas the latter enzyme degrades only protein substrates. Proteinase inhibitors were isolated from the peripheral leucocytes of pig blood. Three different types of these inhibitors differ in molecular weight; I 1 - 15 000, I 2 - 40 000, I 3 - 65 000, in isoelectric point (from 4.4 to 5.6), immunologically and their inhibition ability against tested proteinases. Inhibitor 1 inhibits chymotrypsin-like neutral proteinases of both types and thiol proteinases (cathepsin B, H, papain); inhibitor 2 is a specific inhibitor of elastases (leucocyte and spleen) and also inhibits both types of chymotrypsin-like neutral proteinases. Inhibitor 3 is a specific inhibitor of the plasminogen activator - urokinase. The purified inhibitors are stable in acid, as well as in neutral pH, but it was found that inhibitor 2 and 3 might be inactivated by the action of cathepsin D.

Critical dynamics and stability of elastically coupled systems at marginal dimensionalities

Abstract: Static and dynamic behavior of an-component classical model atd=4 has been investigated assuming a coupling to a fluctuating lattice displacement field. Solutions of renormalization-group (RG) equations are given for elastically isotropic and anisotropic systems, and the temperature dependences of elastic constants and of the corresponding damping coefficients are calculated. For isotropic and weakly anisotropic systems it is found that forn ts, and a compressible regimet

Immunological studies of intracellular leukocyte proteinase inhibitor by granular extract and cathepsin D.

Abstract: There are many reports in the literature (1) on the purification and properties of plasma proteinase inhibitors (i.e. alpha 1-antitrypsin, alpha 2-macroglobulin) and on attempts to make antisera, but so far there have been very few adequate reports on the isolation of intracellular leukocyte proteinase inhibitors and there have been no adequate reports on a specific anti-(LNPI) serum.

Dielectric Dispersion in Dobambc

Abstract: From the low frequency order parameter fluctuation spectrum of chiral DOBAMBC at the ferroelectric smectic A to C transition, studied by dielectric relaxation spectroscopy, the frequency and dielectric strength of the Golds tone mode for q = 0 in the ferroelectric phase have been determined. The frequency is approximately temperature independent, decreasing slightly when approaching Tc from below, while the intensity decreases for an order of magnitude and goes to zero at Tc.

Alpha Ionisation for Continuous Computerized Cardiorespiratory Monitoring during Mechanical Ventilation

Abstract: Alpha ionisation pneumotachography (1) has been shown to be suitable for measuring respiratory flows in patients on mechanical ventilators. It is based on the following principles: Americium (Am241), an alpha source, is used to ionise gas molecules passing through a measuring tube-sensor. The concentration of ions above the alpha source depends on the recombination coefficient. These ions are carried away by the gas flow. Downstream from the alpha source there is an electrode. The resulting collector current from the electrode is in linear proportion to the flow (Figure 1).

Trace elements in water and biological samples determined by x-ray spectroscopy

Abstract: Trace element concentrations were measured in water and biological samples using the method of detection of characteristic X-rays X-ray emission spectroscopy allows simultaneous determination of the concentrations of all biologically essential trace elements Characteristic X-rays from samples were excited using X-rays from Mo-tube, radiation from Fe-55 and Cd-109 radioactive sources and 18 MeV protons from the Van de Graaff accelerator Sensitivities of all three methods for the determination of trace element concentrations in light element matrix were determined Applications of these methods of the problems involving trace element analysis of seawater, drinking water and different biological materials are discussed in some details