The link between abnormalities of calcium handling proteins and catecholaminergic polymorphic ventricular tachycardia.

Catecholaminergic polymorphic ventricular tachycardia (CPVT), a rare autosomal dominant or recessive disease, usually results in syncope or sudden cardiac death. Most CPVT patients do not show abnormal cardiac structure and electrocardiogram features and symptoms, usually onset during adrenergically mediated physiological conditions. CPVT tends to occur at a younger age and is not easy to be diagnosed and managed. The main cause of CPVT is associated with mishandling Ca2+ in cardiomyocytes. Intracellular Ca2+ is strictly controlled by a protein located in the sarcoplasm reticulum (SR), such as ryanodine receptor, histidine-rich Ca2+-binding protein, triadin, and junctin. Mutation in these proteins results in misfolding or malfunction of these proteins, thereby affecting their Ca2+-binding affinity, and subsequently disturbs Ca2+ homeostasis during excitation-contraction coupling (E-C coupling). Furthermore, transient disturbance of Ca2+ homeostasis increases membrane potential and causes Ca2+ store overload-induced Ca2+ release, which in turn leads to delayed after depolarization and arrhythmia. Previous studies have focused on the interaction between ryanodine receptors and protein kinase or phosphatase in the cytosol. However, recent studies showed the regulation signaling for ryanodine receptor not only from the cytosol but also within the SR. The changing of Ca2+ concentration is critical for protein interaction inside the SR which changes protein conformation to regulate the open probability of ryanodine receptors. Thus, it influences the threshold of Ca2+ released from the SR, making it easier to release Ca2+ during E-C coupling. In this review, we briefly discuss how Ca2+ handling protein variations affect the Ca2+ handling in CPVT.

Exposure to carcinogenic PAHs for the vendors of broiled food.

Three types of popular vendors, including meat and non-meat food (e.g, fishballs), vendor group (I), rice sausage sandwiches vendor group (II), and roasted corn on-the-cob vendor group (III), from the night markets of Taiwan were chosen for this research. The average concentrations of carcinogenic polycyclic aromatic hydrocarbons (car-PAHs) were 2445 ng/m3 for vendor (II), 2276 ng/m3 for vendor (II), and 133 ng/m3 for vendor (III). Vendors groups (I) and (II) had exposure levels of Benzo(a)pyrene (BaP)-equivalent doses (BaPeq) approximately 16 and 13 times higher than those for vendor group (III). The daily exposure doses of BaPeq in working duration for vendor group (II) and (II) were 2.80 and 2.28 microg/day, respectively. The employees of five offices on campus were chosen as a control group. The daily exposure doses of BaPeq during working hours for vendor group (II) and (II) were about 22 times and 18 times, respectively, higher than those for control group. This exposure dose for vendors group (III) (0.18 microg/day) was comparable with the dose for control group (0.13 microg/day). The whole-day exposure doses of t-PAHs, car-PAHs, BaP, and BaPeq for vendor groups (I) and (II) were very close to those during daily working hours. However, the daily exposure doses of BaPeq during working hours for vendor group (III) occurred only in a proportion of 62% of the whole-day exposure doses.