http://hdl.handle.net/10400.18/8 2013-05-30T17:06:07Z http://hdl.handle.net/10400.18/1306 Title: Validation and clinical application of an UHPLC method for simultaneous analysis of total homocysteine and cysteine in human plasma Authors: Valente, A.; Bronze, M.R.; Bicho, M.; Duarte, R.; Costa, H.S. Abstract: Several studies indicate that high levels of homocysteine (Hcy) and L-cysteine (L-Cys) are independent risk factors for cardiovascular disease. The validation and clinical application of an ultra HPLC method for analysis ofHcy and L-Cys is described. The reported method is simple, sensitive, rapid, precise, and less aggressive than other previously reported methods. The effect of the derivatization reaction time, pH, and organic solvent contents in the mobile phase are described and discussed. Optimized conditions resulted in excellent peak shapes. Results of method validation showed a good linearity (r2 ≥ 0.993) over the investigated concentration ranges and were observed for both compounds. The LOD and LOQ were 0.05 M and 0.15 M for Hcy and 0.24 M and 0.80 M for L-Cys, respectively. Validation results proved that the method precision was good and the accuracy was satisfactory. This validated method was successfully applied in an epidemiological study to measure and compare the prevalence of Hcy and L-Cys high levels in plasma of Portuguese type 2 diabetic patients with and without angiopathy. The study results showed that prevalence of hyperhomocysteinemia and hypercysteinemia were at least two times higher in diabetic patients with angiopathy compared to diabetics without angiopathy. 2012-12-01T00:00:00Z http://hdl.handle.net/10400.18/1289 Title: Astaxanthin from shrimp by-products for active packaging Authors: Sanches-Silva, A.; Ribeiro, T.; Albuquerque, T.G.; Paseiro, P.; Sendón, R.; Bernaldo de Quirós, A.; López-Cervantes, J.; Sánchez-Machado, D.; Soto Valdez, H.; Angulo, I.; Pardo Aurrekoetxea, G.; Costa, H.S. 2012-03-07T00:00:00Z http://hdl.handle.net/10400.18/1288 Title: Ultra-high pressure LC for astaxanthin determination in shrimp by-products and active food packaging Authors: Sanches-Silva, A.; Ribeiro, T.; Albuquerque, T.G.; Paseiro, P.; Sendón, R.; Bernaldo de Quirós, A.; López-Cervantes, J.; Sánchez-Machado, D.; Soto Valdez, H.; Angulo, I.; Pardo Aurrekoetxea, G.; Costa, H.S. Abstract: Nowadays, there is increasing interest in natural antioxidants from food by-products. Astaxanthin is a potent antioxidant and one of the major carotenoids in crustaceans and salmonids. An ultra-high pressure liquid chromatographic method was developed and validated for the determination of astaxanthin in shrimp by-products, and its migration from new packaging materials to food simulants was also studied. The method uses an UPLCW BEH guard-column (2.1 x 5 mm, 1.7mm particle size) and an UPLCW BEH analytical column (2.1 x 50 mm, 1.7mm particle size). Chromatographic separation was achieved using a programmed gradient mobile phase consisting of (A) acetonitrile–methanol (containing 0.05 M ammonium acetate)–dichloromethane (75:20:5, v/v/v) and (B) ultrapure water. This method was evaluated with respect to validation parameters such as linearity, precision, limit of detection, limit of quantification and recovery. Low-density polyethylene films were prepared with different amounts of the lipid fraction of fermented shrimp waste by extrusion, and migration was evaluated into food simulants (isooctane and ethanol 95%, v/v). Migration was not detected under the tested conditions. 2012-12-07T00:00:00Z http://hdl.handle.net/10400.18/1111 Title: WHO European Childhood Obesity Surveillance Initiative 2008: weight, height and body mass index in 6–9-year-old children Authors: Wijnhoven, T.M.A.; van Raaij, J.M.A.; Spinelli, A; Rito, A.I.; Hovengen, R.; Kunesova, M.; Starc, G.; Rutter, H; Sjoberg, A; Petrauskiene, A.; O'Dwyer, U.; Petrova, S.; Farrugia Sant'Angelo, V.; Wauters, M; Yngve, A.; Rubana, I.M.; Breda, J Abstract: Background: Nutritional surveillance in school-age children, using measured weight and height, is not common in the European Region of the World Health Organization (WHO). The WHO Regional Office for Europe has therefore initiated the WHO European Childhood Obesity Surveillance Initiative. Objective: To present the anthropometric results of data collected in 2007/2008 and to investigate whether there exist differences across countries and between the sexes. Methods: Weight and height were measured in 6–9-year-old children in 12 countries. Prevalence of overweight, obesity, stunting, thinness and underweight as well as mean Z-scores of anthropometric indices of height, weight and body mass index were calculated. Results: A total of 168 832 children were included in the analyses and a school participation rate of more than 95% was obtained in 8 out of 12 countries. Stunting, underweight and thinness were rarely prevalent. However, 19.3-49.0% of boys and 18.4-42.5% of girls were overweight (including obesity and based on the 2007 WHO growth reference).The prevalence of obesity ranged from 6.0 to 26.6% among boys and from 4.6 to 17.3% among girls. Multi-country comparisons suggest the presence of a north–south gradient with the highest level of overweight found in southern European countries. Conclusions: Overweight among 6–9-year-old children is a serious public health concern and its variation across the European Region highly depends on the country. Comparable monitoring of child growth is possible across Europe and should be emphasized in national policies and implemented as part of action plans. 2012-01-01T00:00:00Z