Decrease in dysbaric osteonecrosis severity as a result of 45-minute oxygen pre-breathe

Sudden decompression can result in bubble formation as the result of nitrogen gas (N2) dissolved in tissue during disabled submarine escape (DISSUB). This may cause dysbaric osteonecrosis (DON), a condition in long bones where bubbles in fatty marrow result in ischemia and necrosis. Previous research has shown that oxygen (O2) pre-breathe of two hours resulted in a reduction of DON; however, effects of shorter O2 pre-breathe remain uncertain. This study’s aim was to understand the effect of shorter lengths of O2 pre-breathe. Eight adult Suffolk ewes (89.5± 11.5 kg) were exposed to 33 feet of seawater (fsw) for 24 hours. They were placed randomly into four groups and exposed to either 45, 30 or 15 minutes of O2 (91-88%) pre-breathe; the controls received none. They were then rapidly decompressed. Alizarin complexone was later injected intravenously to visualize the extent of DON in the right and left long bones (radii, tibiae, femur and humeri). The 30- and 15-minute pre-breathe groups saw the greatest deposition. There was significant decrease of variance in the 45-minute group when compared with all other treatments, suggesting that 45 minutes of O2 pre-breathe is required to effectively increase confidence in the reduction of DON. Similar confidence was not reflected in the 30-minute and 15-minute groups: 45 minutes of pre-breathe was the minimum amount needed to effectively prevent against DON in DISSUB escape at 33 fsw. However, future research is needed to determine how to calculate effective dosages of O2 pre-breathe to prevent DON in any given scenario.

STUDY OF PROTOLYTIC EQUILIBRIA IN SOLUTIONS OF HYDROXYANTHRAQUINONE DYES BY CHEMICAL CHROMATICITY METHOD

In this paper, the acid-base properties of hydroxyanthraquinone dyes-alizarin, alizarin red S and alizarin-complexone- were studied in aqueous solutions by chemical chromaticity and spectrophotometry methods. The advantages of chemical chromaticity method over UV-VIS spectrophotometry method were shown in the protolytic equilibria study in dyes solutions. The chemical chromaticity method, unlike spectrophotometry, can determine the deprotonation constant of sulfo group of alizarin red S. Using the chromaticity functions data it is possible to determine all ionization constant of these hydroxyanthraquinone dyes. The overlay of tautomeric equilibria on alizarin-complexone ionization process does not interfere for pK determination of their functional groups by the chemical chromaticity method. A quantitative color description of objects of different nature by calculating their color coordinates by spectrophotometric data allows distinguishing spectrally similar substances and obtaining new data on them. Using the values of chromaticity functions of ion-molecule forms of the hydroxyanthraquinone dyes as an analytical signal allows to get a complete picture of the existing acid-base equilibria in a wide range of medium acidity. A probable acid-base equilibria schemes were theoretically determined for alizarin, alizarin red S and alizarin-complexone using CNDO calculations. The diagrams of the ion-molecular forms distribution of hydroxyanthraquinone were built.For citation:Chebotarev A.N., Snigur D.V., Bevziuk K.V. Study of protolytic equilibria in solutions of hydroxyanthraquinone dyes by chemical chromaticity method. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 3. P. 22-28.