Oxidized phospholipids and lipoprotein-associated phospholipase A_2 as important determinants of Lp(a) functionality and pathophysiological role

Lipoprotein（a） [Lp（a）] is composed of a low density lipoprotein（LDL）-like particle to which apolipoprotein（a）[apo（a）] is linked by a single disulfide bridge. Lp（a） is considered a causal risk factor for ischemic cardiovascular disease（CVD） and calcific aortic valve stenosis（CAVS）. The evidence for a causal role of Lp（a） in CVD and CAVS is based on data from large epidemiological databases, mendelian randomization studies, and genome-wide association studies. Despite the well-established role of Lp（a） as a causal risk factor for CVD and CAVS, the underlying mechanisms are not well understood. A key role in the Lp（a） functionality may be played by its oxidized phospholipids（OxPL） content. Importantly, most of circulating OxPL are associated with Lp（a）; however, the underlying mechanisms leading to this preferential sequestration of OxPL on Lp（a） over the other lipoproteins,are mostly unknown. Several studies support the hypothesis that the risk of Lp（a） is primarily driven by its OxPL content.An important role in Lp（a） functionality may be played by the lipoprotein-associated phospholipase A_2（Lp-PLA_2）,an enzyme that catalyzes the degradation of OxPL and is bound to plasma lipoproteins including Lp（a）. The present review article discusses new data on the pathophysiological role of Lp（a） and particularly focuses on the functional role of OxPL and Lp-PLA_2 associated with Lp（a）.

Application of transesophageal echocardiography to aortic embolic stroke

s To determine the relative value of transesophageal echocardiography (TEE) and tr ansthoracic echocardiography (TTE) in exploring the potential embolic source (PE S) in heart and aortic arch and to study the clinical significance of aortic arc h athersclerosis (AAA) Methods Forty nine patients with cerebral embolism were included in this study TEE an d TTE were used to evaluate the potential source of emboli in aortic arch, heart and duplex in the carotid artery An atherosclerotic lesion of the aortic arch was defined as normal, mild plaque, moderate plaque, and protruding plaque or m obile plaque Results Of the 49 patients, 31(63%) patients showed evidence of AAA: 7 (14 1%) patients were mild, 9 (18 4%) were moderate and 15 (30 6%) were severe In those 15 p atients, 11 had neither severe ICAA nor heart disease Thirty three patients h ad internal carotid arterial atherosclerosis (ICAA) The potential sources of e mbolization of heart and aortic arch is 48 98% by TEE, but only 18 4% by TTE; 9 patients had heart disease Age and ICAA were significantly correlated with A AA Conclusion At present, TEE is a better method for exploring atherosclerotic lesions in the thoracic aorta AAA is an important potential source of cerebral embolic stroke