[The role of color doppler sonography in the diagnosis of atherosclerotic changes in arteries of the lower extremities]. / Uloga obojene doplerske sonografije u dijagnostici aterosklerotskih promjena arterija donjih udova.

In this study doppler ultrasound methods were evaluated from the point diagnostical values, and were compared with the standard X-ray methods (angiography). One of the basic question was, whether noninvasive doppler ultrasonic methods could replace the invasive contrast angiography i. e. in what relations and volume. The investigations were done by CW Doppler and angiodynography, and the results obtained, were compared with the ones of angiography that was taken as the referent method. The 264 segments of blood vessels of lower extremities arterial three were analyzed, and then ranged into the advance defined categories, on the basis of the degree of obstruction. The evaluation of the data obtained was statistically accomplished by the means of "decision matrix" test, and results were displayed by positive predictive values. Positive predictive value for the CW Doppler was 94.07 (in groups varied from 93.10-100) and for angiodynography was 97.35 (in groups varied from 93.15 to 100). From the data obtained, it could be concluded that Doppler's methods are very accurate in a way of diagnostical interpretation (96.03%). The advantages of the Doppler's methods against the conventional standard radiological researches reflect in the following facts: they enable dynamic indicators in real time, they are noninvasive, very exact, and the possibility of verification of stenosis is enabling us to apply the adequate diagnosic (angiography) and therapeutic methods in time.

Interaction of some metals between marine-origin humic acids and aqueous solutions.

The interaction of metal ions (carrier-free form) in aquatic medium with humic acids is a complicated process depending on the properties of humic acids (elementary, chemical, and trace element composition), metals studied (valence, charge, chemical form, concentration), and medium used (pH, ionic strength). The use of radionuclides was found to be very suitable for a rapid and precise determination of the distribution coefficient Kd (ratio of the concentration of a certain trace metal association with a gram of humic acid over the concentration of the same trace metal per milliliter of solution) of the investigated system. Isolated humic acids from offshore sediments from the North Adriatic (Lim channel, near Rovinj, Yugoslavia) were characterized according to their elementary composition, the amount of products of hydrolysis, and the trace elements bound. All experiments were carried out between pH 3 and 5. It was found that conditions usually present at the site where humic acid interacts with metal ions (anaerobic conditions, H2S) in brackish (21% S) and standard seawater (38% S) are determined in the pH range 3 to 5. The results of the pick-up (uptake) and replacement (release) experiments are presented as a distribution coefficient (Kd), as a function of contact time. Processes of pick-up and replacement of a number of metals under various physicochemical conditions were investigated and special attention was paid to the influence of salinity. With the increase in NaCl concentration and pH in the system, the fixation of ruthenium, zinc, cobalt, and mercury by humic acids decreased. The liberation and fixation of metal ions along the coastal seawater are important for the marine ecosystem.

Trace metals in humic acids and their hydrolysis products.

The role of humic acids in the transport of trace elements in the Sava river biocycle (near Zagreb, Yugloslavia) has been investigated by means of neutron activation analysis. Humic acids can accumulate certain trace elements, but little is known about their selectivity under certain physicochemical conditions. Humic acids isolated from Sava river sediments were hydrolized to their main components, namely to amino acids (proteins), phenols (and phenolic acids), carbohydrates, polycyclic aromatics, and metals. Degradation of humic acids in the environment occurs by the action of microorganisms, and during this step, certain trace metals become available to Sava river animals through standard physiological processes. In this work neutron activation analysis was applied to the quantitative and qualitative determination of trace metals in humic acids of Sava river origin, and in their hydrolysis products. The trace metals measured were Ag, Fe, Co, Cs, Eu, Sb, Sc, Se, and Sr. The concentrations obtained ranged from 0.05 to 2730 micrograms of a certain microconstituent per gram of sample. The experimental data are compared with the laboratory experiments on the determination of stability constants for metal complexes of humic acids and their hydrolysis product. From these data it is possible to suggest the ecological importance of trace metals bonded to humic acids in a certain region. The results concerning the role of humic acids in the cycle of trace elements in Sava river biocycle are discussed.