ABSTRACT
The coupled effects of temperature variation and pre-sustained loading on the bond between basalt fiber reinforced polymer (BFRP) sheets and a concrete substrate were studied. Single lap-shear test specimens were exposed to temperatures of 15, 30, 40, 50, and 60 °C for 3 h with pre-sustained loading at 35% of the ultimate load capacity (Fu). Compared with the case of 15 °C, the interfacial fracture energy of the specimens at 30 and 40 °C increased by 46% and 11%, respectively, whereas those reduced by 73% and 77% at 50 and 60 °C, respectively. The coupled effects of temperature and pre-sustained loading on the effective bond length are insignificant for the specimens at both 15 and 30 °C and the effective bond length increased to 300 mm when the temperature exceeded 40 °C. The failure crack still occurred in the concrete substrate at the temperatures of 15 and 30 °C, and changed to the debonding of the adhesive layer from the concrete substrate at the temperature above 30 °C.
ABSTRACT
Chitosan and capsaicin are compounds extracted from natural products and have been indicated to lower body weight and prevent fatty liver. However, their applications are limited by poor oral bioavailability, low compliance and some serious side effects. To solve these problems, we successfully prepared chitosan microspheres (CTMS) and chitosan-capsaicin microspheres (CCMS) in previous study. Therefore, in the present study, we evaluated the ability of CTMS and CCMS to eliminate lipid accumulation in hepatocytesand also characterized their pharmacokinetic parameters after administration. The results showed that the two microspheres could significantly reduce intracellular lipid accumulation and dose-dependently improve the triglyceride (TG) content in HepG2 cells. A pharmacokinetic study indicated that CTMS and CCMS were distributed in almost all of the measured tissues, especially liver and kidney, and that their absorption was better than those of chitosan and capsaicin. Simultaneously, the prolonged circulating half-lives, the lower clearance and higher plasma concentration of CTMS and CCMS showed that their bioavailability was effectively enhanced. All of the results indicated that the lipid accumulation inhibition of CTMS and CCMS was better than that of chitosan and capsaicin, and that these microspheres can be developed as preventive agents for fatty liver or obesity.
ABSTRACT
Chitosan (CTS) and capsaicin (CAP) are two kinds of effective ingredients for antiobesity, which are extracted from crab shells and Capsicum annuum. However, the strong taste of CAP makes it difficult to consume, and the antiobesity ability of CTS is limited. In this study, we prepared capsaicin-chitosan microspheres (CCMSs) by ion-cross-linking and spray drying and examined the antiobesity ability of CCMSs in obese rats. The effects of CCMSs on body weight, Lee's index, body fat, and serum lipids were investigated. The mRNA expression of PPARα, PPARγ, leptin, UCP2, GPR120, FTO, and adiponectin in the liver was determined by quantitative real-time PCR, and the protein expression of adiponectin, leptin, PPARα, UCP2, and hepatic lipase in serum was evaluated by enzyme-linked immunosorbent assay. CCMSs were prepared with 85.17% entrapment efficiency and 8.87% mean drug loading. Compared with chitosan microspheres, CAP, and Orlistat, the CCMSs showed better ability to control body weight, body mass index, organ index, body fat, proportion of fat to body weight, and serum lipids. The CCMSs upregulated the expressions of PPARα, PPARγ, UCP2, and adiponectin and downregulated the expression of leptin. CCMSs may thus be considered novel, safe, effective, and natural weight loss substances, and there is an additive effect between CTMS and capsaicin.
Subject(s)
Anti-Obesity Agents/administration & dosage , Brachyura/chemistry , Capsaicin/administration & dosage , Capsicum/chemistry , Chitosan/administration & dosage , Dietary Fats/metabolism , Obesity/drug therapy , Adiponectin/genetics , Adiponectin/metabolism , Animals , Anti-Obesity Agents/chemistry , Capsaicin/chemistry , Chitosan/chemistry , Diet, High-Fat/adverse effects , Dietary Fats/adverse effects , Humans , Insulin/metabolism , Lipid Metabolism , Liver/drug effects , Liver/metabolism , Male , Microspheres , Obesity/genetics , Obesity/metabolism , PPAR alpha/genetics , PPAR alpha/metabolism , PPAR gamma/genetics , PPAR gamma/metabolism , Rats , Rats, Sprague-Dawley , Triglycerides/metabolismABSTRACT
This study aimed to research the preparation and content determination of capsaicin-chitosan microspheres (CCMS) enteric coated tablets. The core tablets were prepared with the method of wet granulation. Nine formulae were designed to determine the optimal formula of the core tablet. Eudragit L100 was used to prepare the CCMS enteric-coated tablets. The effect of enteric coated formulation variables such as content of talc (10%, 25% and 40%), plasticisers (TEC and DBS), dosage of plasticiser (10%, 20% and 30%) and coating weight (2%, 3% and 5%) were evaluated for drug release characteristics. The in vitro release was studied using 0.1 N HCl and pH 6.8 phosphate buffer. Enteric coated tablets without ruptures or swelling behaviour over 2 h in 0.1 N HCl indicated that these tablets showed acid resistance. The accumulated release rate in phosphate buffer (pH 6.8) revealed that the prepared tablets were able to sustain drug release into the intestine and a first-order release was obtained for capsaicin. This research is the first report of the preparation and content determination of CCMS enteric coated tablets. The sustained release behavior of enteric coated formulations in pH 6.8 phosphate buffer demonstrated that it would be a potential drug delivery platform for sustained delivery of gastric irritant drugs.