Identification,structure elucidation and origin of a common pyridinium-thiocyanate intermediate in electrospray mass spectrometry among the benziamidazole-class proton pump inhibitors / 药物分析学报

During the analysis of benziamidazole-class irreversible proton pump inhibitors,an unusual mass spectral response with the mass-to-charge ratio at[M+10]+intrigued us,as it couldn't be assigned to any literature known relevant structure,intermediate or adduct ion.Moreover,this mysterious mass pattern of[M+10]+has been gradually observed by series of marketed proton pump inhibitors,viz.omeprazole,pantoprazole,lansoprazole and rabeprazole.All the previous attempts to isolate the corresponding component were unsuccessful.The investigation of present work addresses this kind of signal to a pyridinium thiocyanate mass spectral intermediate(10),which is the common fragment ion of series of labile aggregates.The origin of such aggregates can be traced to the reactive intermediates formed by acid-promoted degradation.These reactive intermediates tend to react with each other and give raise series of complicated aggregates systematically in a water/acetonitrile solution by electrospray ioniza-tion.The structure of the corresponding pyridinium thiocyanate species of omeprazole(10a)has been eventually characterized with the help of synthetic specimen(10a').Our structural proposal as well as its origin was supported by in situ nuclear magnetic resonance,chemical derivatization and colorimetric experiments.

Cerebrovascular reserve capacity of patients with ischemic cerebral white matter lesions / 实用医学杂志

Objective To investigate the changes of cerebrovascular reserve capacity (CVR) in patients with ischemic white matter lesions (WML). Methods 126 patients with WML were divided into mild lesion, moderate lesion, severe WML groups and a normal control group by brain MRI. Blood pressure, blood sugar, blood fat were measured and past medical histories were recorded in details. All the patients were routinely examined using TCD to evaluate CVR. Hypercapnia was induced by inhaling the CO2 they breathed themselves and hypocapnia was done by voluntary hyperventilation. Results Age, hypertension, diabetes mellitus and Apo-A were the independent risk factors for WML. Compared with the controls , CVR decreased significantly in the severe and moderate WML groups (P < 0.05). The extent of WML negatively correlated to the cerebrovascular reserve capacity (rs = -0.273, -0.392). Conclusions Age, hypertension, diabetes mellitus and Apo-A are the independent risk factors for WML. CVR is significantly decreased in the WML.