Complex formation and liquid-liquid extraction have been studied for ternary complexes of vanadium(IV) with 4-(2-pyridylazo)-resorcinol (PAR) and ditetrazolium chlorides (DTC) in a water-chloroform medium. The specific ditetrazolium compounds investigated were i) 3,3′-(4,4′-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Neotetrazolium chloride, NTC); ii) 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Blue Tetrazolium chloride, BTC); and iii) 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)-bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium] chloride (Nitro Blue Tetrazolium chloride, NBT). Molar absorptivity coefficients and the composition of the complexes have been calculated. Association constants (β) have also been obtained for the interactions between the vanadium(IV) — PAR anionic chelates [VO(PAR)2]2− (I) and [VO(OH)2(PAR)2]4− (II), and ditetrazolium cations (DT2+). Some special features of NBT as an extraction-spectrophotometric reagent for vanadium(IV) have been discussed. Unlike NTC and BTC which form complexes with both I and II, NBT associates only with II. The pH interval for complete extraction of (NBT2+)2[VO(OH)2(PAR)2] is broader and allows work at lower pH values the other ion-associates of V(IV,V)-PAR that were studied. NBT is -therefore the appropriate reagent both for direct V(IV) determination and for V(IV)/V(V) separation. Some additional characteristics for the V(IV)-PAR-NBT-water-chloroform system have been determined: extraction constant, distribution constant, recovery factor, limit of detection and limit of quantification. Beer’s law is valid up to 1.4 μg mL−1 vanadium(IV) with molar absorptivity coefficient of 3.55×104 L mol−1 cm−1 at λmax=559 nm.
Frostbite causes injury to the tissue by direct ice-crystal formation at the cellular level with cellular dehydration and microvascular occlusion. Muscle that initially appears viable on reperfusion may subsequently become necrotic because of microcirculatory collapse. Since muscle is a sensitive tissue in frostbite injury, we used technetium-99m-sestamibi limb scintigraphy to assess tissue viability in an experimental rabbit model. Twelve rabbits were used for this investigation. The right hind limb of the rabbits was immersed to the ankle joint in a container filled with 90% ethanol at -25 degrees C for 10 min. Frostbitten limbs were allowed to thaw in air at room temperature. Imaging and pathological examination of the affected limbs were performed 2 h, 24 h, 48 h and 72 h after freezing. In 2-h images, initial hypoperfusion was seen that corresponded to circulatory collapse. In 24-h images, there was hyperperfusion (so-called period of temporary reperfusion), corresponding to circulatory restoration. In 48-h images, a second hypoperfusion corresponded to viable but ischaemic tissue. In 72-h images, there was non-perfusion of the limb that correlated with the pathologically determined diagnosis of necrosis. All scintigraphic patterns correlated with pathological findings. We suggest that these scintigraphic patterns in soft tissue may be helpful in distinguishing between frank infarction and reversible ischemia and therefore may be useful in selecting early therapeutic or surgical interventions to salvage bone and soft tissue. Further studies are needed to show the usefulness of 99mTc sestamibi scintigraphy in clinical frostbite cases.
Here we report that superficial siderosis is a common MR imaging finding in the first year of life of patients with a history of germinal matrix hemorrhage, but it dissolves and has a low prevalence thereafter. A prospective analysis of its initial severity and speed of dissolution during this first year might add to our understanding of the pathophysiology of neurodevelopmental impairment after germinal matrix hemorrhages.
Four newly synthesized imidazolium salts were characterized by nuclear magnetic resonance, vibrational spectra, and mass spectra. Then, the density functional theory calculations were performed to obtain the molecular configurations on which the theoretical nuclear magnetic resonance and infrared spectra were consequently obtained. The comparison of calculated spectra with the experimental spectra for each molecule leads to the conclusion that the theoretical results can be assumed to be a good approach to their molecular configurations. The in vitro biological activities of the salts on the selected bacteria and cancer cell lines were determined by using the broth dilution method according to Clinical and Laboratory Standards Institute guidelines. The 1,3-bis(2-hydroxyethyl) imidazolidinium bromide and 3-(2-ethoxy-2-oxoethly)-1-(3-aminopropyl)-1H-imidazol-3-ium bromide showed efficiency on Bacillus cereus ATCC 11778. The 3-bis(2-carboxyethyl)-4-methyl-1-H-imidazol-3-ium bromide was effective on HeLa while a similar effect was observed on Hep G2 with 3-(2-carboxyethyl)-1-(3-aminopropyl)-1H-imidazol-3-ium bromide.
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