Analysis of underivatizated patulin by a GC-MS technique

An alternative approach based on the use of gas chromatography-mass spectrometry (GC-MS) is used to confirm the presence of patulin in apple juice. In the gas chromatography (GC) methods previously described, derivatization of patulin was always necessary in order to achieve good chromatographic detection. The use of electronic pressure control (EPC) and on-column injection avoids the need for patulin derivatization and allows a sensitive analysis of patulin. A detection limit of 4 microg/liter in apple juice can be attributed to the method.     

Impact of oxygen therapy on antioxidant status in newborns. Relationship with infection risk

Newborns requiring intensive clinical care are susceptible to a wide range of excessive oxygen free radical production-related problems. In utero, fetal organs, particularly lungs, are exposed to relatively hypoxic tensions which rise abruptly after birth and this transition may cause oxidative injury in the neonate. The aims of this study were to determine oxygen free radical activity in neonates at the first 24 h, examine the role of immaturity and infection risk and compare the degree of oxidant stress in newborns treated with different oxygen concentrations. Plasma selenium levels in neonates with high infection risk (IR) were significantly lower than in healthy neonates. Comparative study of selenium in preterm, term and young infants showed age-related increases and differences were significant. Plasma selenium values were lower when oxygen therapy was administered. Vitamin E levels were significantly decreased in IR compared with healthy newborns. The results suggest that selenium and vitamin E deficiencies predispose to neonatal infection and that supplementary oxygen contributes significantly to decreasing the antioxidant defence system.     

Lipid profile in Venezuelan preschoolers by socioeconomic status

Epidemiological studies have shown that unfavorable serum lipids levels in childhood are predictors of development of atherosclerosis lesions in adulthood. We assessed the lipid profile of 297 Venezuelan preschool children (4-7 years old) from two socioeconomic levels in order to compare them by this characteristic. Their social level was determined according to modified Graffar method, and two groups were obtained: high socioeconomic status (HSES, n=103) and low socioeconomic status (LSES, n=194). Nutritional anthropometric evaluation was performed by weight to height, and NCHS/OMS cut-off point was used. Lipid profile was determined by colorimetric biochemical methods and atherogenic risks factors were calculated. Underweight for HSES was 5.8% and for LSES: 14.9%, while normal status was 78.6% and 70.1%, and overweight was 15.5% and 14.9%, respectively. Mean values for triglycerides were 0.66 +/- 0.27and 0.76 +/- 0.31 mmol/L, total cholesterol (TC): 3.61 +/- 0.65 and 2.98 +/- 0.71 mmol/L, HDL-C: 1.04 +/- 0.18 and 0.62 +/- 0.16 mmol/L, LDL-C: 2.27 +/- 0.61 and 2.01 +/- 0.71 mmol/L, TC/HDL-C: 3.5 +/- 0.78 and 5.0 +/- 1.5; LDL-C/HDL-C: 2.0 +/- 0.71 and 3.4 +/- 1.4 with significant differences between HSES and LSES as shown respectively. A significant association was found (p < 0.01) between lipid values and socioeconomic status, being the LSES preschoolers those with the higher atherogenic risk. Its pattern was of lower HDL-C levels, and higher TC/HDL-C and LDL-C/HDL-C ratio. Comparisons of lipid profile by nutritional status or gender did not show significant differences. Findings indicate that children from low socioeconomic status are at a higher risk for cardiovascular disease and atherosclerosis than children from high socioeconomic status.     

Lymphocyte subpopulations in preschool Venezuelan children of high socioeconomic status

Nutrition is a critical determinant of immune response being the most common cause of immunodeficiency in the world. 104 preschool children, apparently healthy, from a private school were chosen to determine lymphocyte subpopulations and to evaluate its relationship to the anthropometric nutritional status and serum zinc. Nutritional status was measured by the indicator weight for height, lymphocyte subpopulations by flow cytometry and serum zinc by atomic absorption spectrophotometry A high percentage of the population (87.5%) belonged to socioeconomic level II (Graffar). Nutritional deficit was present in 9.5 percent of the studied children, while 16.2% were overweight. Values for lymphocytes subpopulations and serum zinc were within reference ranges, similar to other reports and there were no significant differences by sex, age or nutritional status. Low concentrations of serum zinc were present in 6.7% of children. There was a tendency to lower values of the T lymphocyte populations in hypozincemic children but it did not reach statistical significance. As there are not reference values for lymphocyte subpopulation in Venezuelan children, these results could be used as reference for future investigations. Continuity of research is needed to understand relationship of micronutrients levels and immune response.     

New methodology for surface potential decay measurements: application to study charge injection dynamics on polypropylene films

Our work shows, through measurements on polypropylene films, the validity of surface potential measurements as a technique for dielectric properties analysis. We propose a representation of the decay and potential return curves that separates different components of dielectric response, by using tdv/dt vs log t plots. Using this transformation, and varying some experimental conditions we have identified different contributions to the potential decay. From our experimental observations we suggest a qualitative interpretation of the initial seconds of potential decay for negative corona charged samples that uses a model controlled by surface trap emission and charge exchanges between corona discharge and the insulator surface.     

New property of vitamin A and beta-carotene on human iron absorption: effect on phytate and polyphenols as inhibitors of iron absorption

One hundred and seventy four human subjects were studied to find out the interaction of vitamin A or beta-carotene with the inhibitors of iron absorption, from a basal breakfast containing bread from either 100 g of precooked corn flour or 100 g of white wheat flour, 50 g of cheese and 10 g of margarine. Bread was labeled with either 55Fe or 59Fe. This bread was made from commercially flours fortified with iron as ferrous fumarate and vitamins. It was noticed that the percentage of iron absorption from the breakfast prepared with precooked corn flour given alone and with different concentrations of coffee was practically the same, while the iron absorption from the breakfast prepared from wheat flour decreased from 6% when the breakfast was given alone, to less than 2% when it was given with different concentrations of coffee. The only ingredient present in precooked corn flour and not in wheat flour was vitamin A. This difference encouraged the authors to perform further experiments using precooked corn and wheat flours fortified only with ferrous fumarate. These studies demonstrated that vitamin A inhibits the effect of the polyphenol and partially inhibits the effect phytate on iron absorption. HPLC and spectrophotometric studies demonstrated an interaction between vitamin A and iron. Other experiments, which included 100 volunteers, were performed to test the effect of vitamin A and beta-carotene on iron absorption from corn, wheat and rice. The presence of vitamin A increased iron absorption up to 3 times for rice, 2.4 times for wheat and 1.8 times for corn. beta-carotene increased absorption almost 3 times for the three cereals tested, showing that both compounds were capable of preventing the inhibitory effect of phytates on iron absorption. This information suggest that vitamin A and beta-carotene form a complex with iron keeping it soluble in the intestinal lumen and preventing the inhibitory effect of phytates and polyphenols on iron absorption.     

Serum leptin in eutrophic and overweight Venezuelan children and adolescents

Leptin is closely related to obesity and its complications. In order to determine serum levels of this hormone in children and adolescents, and its associations to age, gender, socioeconomic status, nutritional anthropometrical status and dietary intake, 166 children and adolescents (91 normal and 75 obese, aged 2 to 15 years), from low socioeconomic status were assessed. A socioeconomic evaluation (Grafffar-Mendez C method), dietary intake (24 hour recalls), anthropometrical assessment and leptin by ELISA were performed. Normal or eutrophic was defined as weight for height (W/H) or Body mass index (BMI) and fatty area between 10th and 90th percentile. Obesity when indicators were over 90th percentile. Leptin was significantly higher in obese than in normal, without differences by gender or age. Leptin percentile distribution showed 11.53 microg/L and 24.29 microg/L as 90th percentile for normal and obese children, respectively. There was a tendency to inverse correlation among leptin, fat dietary intake and waist-thigh ratio. Excessive fat intake was associated to lower serum leptin. Results suggest that obese children had leptin resistance, independently of age and gender. It is recommended to develop nutritional education programs regarding obesity and dietary intake in order to prevent and control infantile obesity.     

Design and performance of energy-efficient solar residential house in Andorra

This paper describes the design and building technology details of a three-storey single family house located in the Pyrenees, in Andorra. The house is owned by the first author, and has been occupied since 2004. A combination of active and passive solar energy systems and night-time electricity are used to supply the heating and cooling demands. The main goal of this paper is to provide detailed design information and an evaluation of performance. Data provided includes site information and climate, basic design options and decisions, energy saving strategies and energy end use data. The house has been in use since 2003. This allows adequate performance data to be presented and evaluated. Some general results and initial design problems are discussed.