Parenchymal hyperdensity on C-arm CT images after endovascular therapy for acute ischaemic stroke predicts a poor prognosis.

AIM: To investigate whether hyperdense areas (HDAs) observed after endovascular treatment on multisection computed tomography (CT) are related to outcome. MATERIALS AND METHODS: Data on 82 patients with acute anterior circulation ischaemic stroke resulting from intracranial large artery occlusion were analysed retrospectively All patients underwent mechanical thrombectomy and/or emergency angioplasty, and partial or complete recanalisation was successfully achieved. C-arm CT was performed immediately after endovascular treatment for all patients. Clinical and radiological data were compared between patients with and those without HDA and between patients with good and those with poor outcomes. RESULTS: Compared with non-HDA patients, HDA patients were more likely to present with severe neurological deficits (admission National Institutes of Health Stroke Scale [NIHSS] score: 18 versus 16, p=0.037) and had a higher number of stent retriever passes performed (2.9±1.3 versus 1.4±1, p<0.001), longer onset-to-presentation times (229±78 versus 171±90 minutes; p=0.002), longer onset-to-recanalisation times (418±94 versus 331±105 minutes; p<0.001), and longer puncture-to-recanalisation times (103±47 versus 69±42 minutes; p=0.001). Fewer HDA patients had a good prognosis (35.7% versus 70%, p<0.001). Multivariate analysis showed the presence of HDAs was an independent negative prognostic factor (OR=0.208; p=0.002). CONCLUSION: HDAs on C-arm CT appear to be common in patients with acute ischaemic stroke who underwent successful endovascular treatment. HDA presence suggests a poor prognosis despite successful reperfusion.

Reversed phase ion-pair liquid chromatographic determination of nicotine in commercial tobacco products. 1. Moist snuff.

The official methods for the determination of nicotine in commercial tobacco products (AOAC, CORESTA) are based on approaches that are not selective for nicotine (colorimetric measurement, steam distillation, perchloric acid titration), and the availability of published methods based on state-of-the-art chromatographic methods is limited. Reversed phase ion-pair liquid chromatography has been established as a viable alternative for the analysis of basic analytes. A reversed phase ion-pair liquid chromatographic method for the determination of nicotine in commercial tobacco products was developed and optimized in separate experiments (Ciolino, L. A.; Turner, J. A.; McCauley, H. A.; Smallwood, A. W.; Yi, T. Y. J. Chromatogr. 1999a, 852 (2), 451-463). An extensive within-laboratory performance study of the optimized method was subsequently conducted, and results are presented here for the determination of nicotine in commercial moist snuff. Results for the determination of nicotine in commercial cigarettes are presented in a subsequent paper.

Reversed phase ion-pair liquid chromatographic determination of nicotine in commercial tobacco products. 2. Cigarettes.

A reversed phase ion-pair liquid chromatographic method for the determination of nicotine in commercial tobacco products was previously developed and optimized (Ciolino, L. A.; Turner, J. A.; McCauley, H. A.; Smallwood, A. W.; Yi, T. Y. J. Chromatogr. 1999a, 852 (2), 451-463) and provided reliable results for the determination of nicotine in commercial moist snuff (Ciolino, L. A.; McCauley, H. A.; Fraser, D. B.; Barnett, D. Y.; Yi, T. Y.; Turner, J. A. J. Agric. Food Chem. 1999b, 47, 3706-3712). The method uses an aqueous-based sample extraction and provides rapid separation of nicotine from the minor tobacco alkaloids and other commercial tobacco components. In the present work, the method is evaluated for the determination of nicotine in commercial cigarettes and compared to both an official AOAC method for total alkaloids in tobacco (AOAC, AOAC Official Methods of Analysis of AOAC International, 16th ed.; AOAC International: Gaithersburg, MD, 1995; pp 30-31), and a published GC method (Lyerly, L. A.; Greene, G. H. Beitr. Tabakforsch. 1976, 8 (6), 359-361). Good agreement was obtained between the ion-pair LC method and the GC method with relative differences in determined nicotine contents of 0.6 to 5% for a series of commercial and reference cigarettes.

Optimization study for the reversed-phase ion-pair liquid chromatographic determination of nicotine in commercial tobacco products.

The availability of published methods for the determination of nicotine in commercial tobacco products based on state-of-the-art chromatographic methods is limited. Nicotine is a diprotic base with pKa's of 3.12 (pyridine ring) and 8.02 (pyrrolidine ring). Other monoprotic and diprotic bases are also present in commercial tobacco including anatabine, nornicotine, anabasine, and cotinine. In this paper, the chromatography of nicotine and the minor tobacco alkaloids under reversed-phase ion-pairing conditions is thoroughly studied. The results of this study are used to understand the retention mechanisms of the tobacco alkaloids, to examine their observed elution order with respect to fundamental analyte properties (size, functionality, and acid-base strength), and to select optimum chromatographic conditions for the determination of nicotine in commercial tobacco products.