RESUMO
A novel membrane contactor method was used to produce size-controlled poly(ethylene glycol)-b-polycaprolactone (PEG-PCL) copolymer micelles composed of diblock copolymers with different average molecular weights, Mn (9200 or 10,400 Da) and hydrophilic fractions, f (0.67 or 0.59). By injecting 570 L m(-2) h(-1) of the organic phase (a 1 mg mL(-1) solution of PEG-PCL in tetrahydrofuran) through a microengineered nickel membrane with a hexagonal pore array and 200 µm pore spacing into deionized water agitated at 700 rpm, the micelle size linearly increased from 92 nm for a 5-µm pore size to 165 nm for a 40-µm pore size. The micelle size was finely tuned by the agitation rate, transmembrane flux and aqueous to organic phase ratio. An encapsulation efficiency of 89% and a drug loading of ~75% (w/w) were achieved when a hydrophobic drug (vitamin E) was entrapped within the micelles, as determined by ultracentrifugation method. The drug-loaded micelles had a mean size of 146 ± 7 nm, a polydispersity index of 0.09 ± 0.01, and a ζ potential of -19.5 ± 0.2 mV. When drug-loaded micelles where stored for 50 h, a pH sensitive drug release was achieved and a maximum amount of vitamin E (23%) was released at the pH of 1.9. When a pH-sensitive hydrazone bond was incorporated between PEG and PCL blocks, no significant change in micelle size was observed at the same micellization conditions.
RESUMO
BACKGROUND: Metabolic syndrome is a constellation of disorders that produces a high risk of atherosclerosis. The prevalence of metabolic syndrome clearly varies depending on ethnicity. The aim of this study was to investigate the prevalence of metabolic syndrome and its relationship with significant coronary stenosis (SCS) in a Tunisian population. METHODS: Metabolic syndrome was diagnosed according to the International Diabetes Federation criteria. SCS was defined as a luminal narrowing of more or equal to 50% in at least 1 major coronary artery, as judged by coronary angiography. A total of 192 subjects documented by coronary angiography were recruited from the cardiology department. RESULTS: In all, 54.2% (n = 104) of patients presented with metabolic syndrome, with a higher prevalence among women (65.9% vs. 45.5%; P = 0.004). In the subjects with metabolic syndrome, the fasting hyperglycemia was the most common metabolic disorder (86.5%). The risk of SCS increased approximately 3-fold in the presence of metabolic syndrome [odds ratio (OR) = 3.38, P = 0.004]. In addition, SCS risk was increased according to the increase in the number of metabolic syndrome components. The most atherogenic profile was that which assembled five metabolic syndorme components (OR = 4.18, P = 0.001). There was a significant relationship between the homeostasis model of insulin resistance (HOMA-IR) and the risk of SCS in the presence of metabolic syndrome. In fact, the OR of SCS associated with metabolic syndrome was (4.96, P = 0.001) in participants in the highest quartile of HOMA-IR. CONCLUSIONS: This study suggests that metabolic syndrome is a risk factor for SCS. The detection, prevention, and treatment of the underlying risk factors of metabolic syndrome should become an important approach for reduction of the cardiovascular disease burden in our study population.