189,144 research outputs found
Recensione di: “P. Olen and C. Sachs, Pragmatism in Transition: Contemporary Perspectives on C.I. Lewis (Palgrave Macmillan 2017)”,
No full textRecensione di “P. Olen and C. Sachs, Pragmatism in Transition: Contemporary Perspectives on C.I. Lewis (Palgrave Macmillan 2017)
Low Dose Sarin Leads to Murine Cardiac Dysfunction
No full textIt has been reported that low dose sarin is associated with long-term pathology in the brain and heart; however, the effects of sarin on the heart have yet to be determined. In addition, sarin has been implicated as an etiological agent in Gulf War Illness. Thus, the role of sarin in producing illness has important military consequences. This study used echocardiography, electrocardiography, and histology to determine sarin’s effect on the murine cardiovascular system. C57BL/6J mice were injected with sarin at 0.4 LD50, 0.5 LD50, or saline on two consecutive days and studied for 10 weeks post exposure. The sarin animals had marked increases in heart weight to body weight ratios (p = 0.026), and the left ventricular lumen size was significantly decreased (p = 0.0014). In addition, cardiomyocytes were significantly larger in the sarin mice (p = 0.025) and atrial/brain natriuretic peptide levels were increased (p = 0.028 and 0.010, respectively). Results of the electrocardiograms show significant ST/T-wave changes in the sarin groups (p = 0.0015 and 0.032, respectively). Similarly, echocardiograms showed significantly decreased performance of the left ventricle in the sarin animals. This study indicates that sarin plays a role in cardiac remodeling and reducing cardiac performance
KINETICS OF THE ENZYMATIC HYDROLYSIS OF SARIN
No full text The enzymatic hydrolysis of sarin is apparently a single first-order reaction. There is no evidence of different reaction rates for the two possible optical isomers of sarin. During both the enzymatic and the non-enzymatic hydrolyses, sarin appears to be detoxified somewhat more rapidly than the manometric results would indicate. However, the detoxification parallels the manometric results sufficiently to stand in contrast to results obtained using tabun. </jats:p
DFT calculations, microsynthesis and characterization of isopropyl methylphosphonoselenofluoridate [sarin-Se]
No full textIsopropyl methylphosphonoselenofluoridate (sarin-Se) was synthesized in order to determine its analytical data and to compare them as well as its reactivity parameters with those of sarin. After synthesis, sarin-Se was characterized using 1H, 13 C and 31P NMR spectroscopy and high resolution mass spectrometry (HRMS). 1H and 13 C NMR chemical shifts were also calculated using density functional theory (DFT) and compared with experimental data, showing a close agreement. Electrophilicity indices of sarin and sarin-Se were calculated at B3LYP/6-31++G (2d, 2p) level of theory. HOMO-LUMO analysis provides a basis to explain electrophilic nature of sarin-Se and sarin, which are almost similar. Based on calculated data, 31P NMR chemical shift and the reactivity of sarin-Se towards some enzymes such as acetylcholinesterase and albumin were explained.</p
Diisopropyl Methylphosphonate and Sarin Decomposition on Pristine vs. Hydroxylated Alumina Surfaces: Mechanistic Predictions from Ab Initio Molecular Dynamics
No full textUnderstanding the reactivity of chemical warfare agents on material surfaces is essential for mitigating and controlling their chemical/biological activity. Using \textit{ab initio} molecular dynamics, we compare the adsorption and decomposition of sarin and its simulant, diisopropyl methylphosphonate (DIMP), on both pristine and hydroxylated alumina surfaces at various temperatures. Our extensive calculations confirm that DIMP is a suitable simulant for sarin experimental studies on pristine alumina surfaces due to their similar adsorption configurations and reaction dynamics. Moreover, our ab initio molecular dynamics simulations predict C--O bond cleavage to be the initial decomposition step for both DIMP and sarin on the pristine surface. We also identify an additional potential decomposition route for sarin via cleavage of the P--F bond. While similarities exist on the pristine surface, differences between sarin and DIMP emerge on the hydroxylated surface at elevated temperatures. This work provides detailed insights into these atomistic decomposition mechanisms and highlights the utility of predictive quantum dynamics simulations for evaluating the suitability of simulants to guide future experimental investigations of these hazardous compounds
Recensione di “S. Bowden, S. Bignall and P. Patton (eds.), Deleuze and Pragmatism (Routledge 2015)”
No full textSynthesis of 14C Sarin
No full textSynthetic routes for the synthesis of [14C] sarin and related nerve agents are described. Triethyl phosphite and [14C] methyl iodide are reacted in the Michaelis-Arbusov reaction to produce diethyl methyl phosphonate which is converted to methylphosphonic acid by hydrolysis. After chlorination and subsequent fluorination the final product is formed by reaction with the appropriate alcohol.</p
HYPERDYNAMIC CIRCULATION IN A CHRONIC MURINE SCHISTOSOMIASIS MODEL OF PORTAL-HYPERTENSION
No full textChronic murine schistosomiasis is a natural disease model of portal hypertension closely mimicking the clinical and histological features of human hepatic schistosomiasis. We studied the splanchnic and systemic hemodynamics in the murine model of schistosomiasis by radioactive microsphere technique. Mice infected with 60 cercariae of Schistosoma mansoni (n = 8) were studied hemodynamically 11 wk age-matched infection and were compared with age-matched healthy controls (n = 11). Mean portal venous inflow in the infected mice (3.82 +/- 0.32 ml/min) was 61% higher than in the healthy animals (2.37 +/- 0.25 ml/min; p < 0.01). A twofold increase in hepatic arterial flow was also seen in mice with schistosomiasis (0.47 +/- 0.14 ml/min) as compared with controls (0.16 +/- 0.03 ml/min; p < 0.05), whereas splanchnic arteriolar resistance (60.91 +/- 7.64 vs. 101.21 +/- 11.06 mm Hg.min.ml-1. gm; p < 0.01) were reduced. There was a significant increase in cardiac index (752 +/- 99 vs. 453 +/- 55 ml.min-1. kg body weight-1; p < 0.05) and reduction in mean arterial pressure (81.37 +/- 3.09 vs. 101.45 +/- 5.85 mm Hg; p < 0.05) in the infected animals compared with controls. These observations clearly demonstrate the existence of a hyperdynamic circulatory state in this model of portal hypertension
OXIME MIXTURES AND ATROPINE IN THE PROTECTION OF MICE AND RATS FROM SARIN POISONING
No full text The protection provided by oral administration of mixtures of oximes prophylactically in conjunction with intramuscular atropine given therapeutically against sarin poisoning in the rat and mouse is reported. N-Methylpyridinium-2-aldoxime methane sulphonate (P-2-S) in combination with diacetylmonoxime (DAM) demonstrated a synergistic action in protecting rats from sarin which raised the protection to double the value obtained from DAM alone. A similar synergism was found for P-2-S and monoisonitrosoacetone in the rat. This combination raised the protection obtainable from either partner by a factor of 8. Both oxime mixtures were less effective in the mouse than in the rat. </jats:p
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