Amparo Alegría

Lipid peroxidation and antioxidant enzyme activities in patients with type 1 diabetes mellitus.

To evaluate oxidative stress in type I diabetes mellitus, two antioxidant enzymes in erythrocytes, copper-zinc superoxide dismutase (SOD EC 1.15.1.1.) and seleno-dependent glutathione peroxidase (GSH-Px; EC 1.11.19), and two indexes of peroxidation in plasma, thiobarbituric acid reactive substances (TBARS) and organic hydroperoxides (OHP), were measured in 118 patients with insulin-dependent diabetes mellitus (IDDM), classified in accordance with the presence or absence of vascular complications and the degree of metabolic control established by the HbA1c level. Ninety healthy subjects made up the control group. According to our results, plasmatic TBARS and OHP concentrations are significantly higher in diabetics than in controls, and these differences are accentuated in diabetic people with vascular disorders. The GSH-Px activity was significantly reduced in diabetic patients with poor and medium metabolic control in relation to the control group, regardless of the existence or absence of vascular disorders. No differences in SOD activity between diabetic and control groups were found. A significant positive correlation between TBARS and HPO (r=0.683, p<0.001) was found in both the control and diabetic groups. Among the lipid parameters studied, there were only significantly positive correlations between TBARS and total cholesterol; TBARS and triglycerides; OHP and total cholesterol and OHP and triglycerides. Positive correlations between TBARS and HbA1c and between OHP and and HbA1c, and negative correlations between GSH-Px and HbA1c and between SOD and HbA1c were also found. The multiple regression analysis shows that TBARS and HPO correlate negatively with GSH-Px. There was no significant correlation with SOD.

High-performance liquid chromatographic determination of furfural compounds in infant formulas. Changes during heat treatment and storage.

Furfural contents in adapted and follow-up infant formulas were measured by RP-HPLC. The evolution of furfural compound contents during storage (a year at 20 and 37 degrees C) was studied. 2-Furylmethylketone and 5-methyl-2-furaldehyde were not detectable in analysed samples. The differences in the furfural compounds at point zero between both infant formulas has to be ascribed to the differences in protein and iron contents. An increase in free 5-hydroxymethyl-2-furfuraldehyde (HMF), 2-furaldehyde (F) and HMF+F contents was observed in all samples, although the differences were not statistically significant. The storage temperature affected the total HMF content and the storage time affected the total HMF and F contents.

Mind the gap—deficits in our knowledge of aspects impacting the bioavailability of phytochemicals and their metabolites—a position paper focusing on carotenoids and polyphenols

Various secondary plant metabolites or phytochemicals, including polyphenols and carotenoids, have been associated with a variety of health benefits, such as reduced incidence of type 2 diabetes, cardiovascular diseases, and several types of cancer, most likely due to their involvement in ameliorating inflammation and oxidative stress. However, discrepancies exist between their putative effects when comparing observational and intervention studies, especially when using pure compounds. These discrepancies may in part be explained by differences in intake levels and their bioavailability. Prior to exerting their bioactivity, these compounds must be made bioavailable, and considerable differences may arise due to their matrix release, changes during digestion, uptake, metabolism, and biodistribution, even before considering dose‐ and host‐related factors. Though many insights have been gained on factors affecting secondary plant metabolite bioavailability, many gaps still exist in our knowledge. In this position paper, we highlight several major gaps in our understanding of phytochemical bioavailability, including effects of food processing, changes during digestion, involvement of cellular transporters in influx/efflux through the gastrointestinal epithelium, changes during colonic fermentation, and their phase I and phase II metabolism following absorption.

Selenium, zinc and copper in plasma of patients with type 1 diabetes mellitus in different metabolic control states

The Studies of selenium (Se), zinc (Zn) and copper (Cu) levels in diabetic patients have led to contradictory findings as the possible relationship between the degree of diabetic control and the changes in mineral contents. In the present study the plasma Cu, Se, and Zn contents of diabetic patients and healthy people were measured and the relationship between these contents and diabetic metabolic control, as determined by glycosylated hemoglobin (HbA1c), was studied. The mean plasma Se content in diabetic patients was significantly lower than in controls (p < 0.01) and a negative correlation between the plasma contents of Se and HbA1c was found. No statistically significant differences in plasma Zn contents, either between patients with type 1 diabetes mellitus and control, were found. A statistically significant sex difference in plasma Cu contents was observed in the control population. In females, statistically significant differences were found in plasma Cu contents between the control subjects and the diabetic patients with medium or poor metabolic control, as well as between diabetic patients with good and poor metabolic control. In males, the only statistically significant differences were between the control subjects and diabetic patients with poor metabolic control. The correlation between plasma contents of Cu and HbA1c is not significant.

Bioaccessibility of tocopherols, carotenoids, and ascorbic acid from milk- and soy-based fruit beverages: influence of food matrix and processing.

A study was made of the effect of high-pressure processing (HPP) and thermal treatment (TT) on plant bioactive compounds (tocopherols, carotenoids, and ascorbic acid) in 12 fruit juice-milk beverages and of how the food matrix [whole milk (JW), skimmed milk (JS), and soy milk (JSy)] modulates their bioaccessibility (%). HPP (400 MPa/40 °C/5 min) produced a significant decrease in carotenoid and ascorbic acid bioaccessibility in all three beverages and maintained the bioaccessibility of tocopherols in JW and JS while decreasing it in JSy. TT (90 °C/30 s) produced a significant decrease in tocopherol and carotenoid bioaccessibility in all three beverages and increased the bioaccessibility of ascorbic acid. With regard to the food matrix, α-tocopherol and ascorbic acid bioaccessibility was greatest in JW beverages and lowest in JSy beverages, whereas no significant differences were found among the three beverages in terms of carotenoid bioaccessibility. HPP-treated samples showed higher tocopherol and carotenoid bioaccessibility than TT-treated samples, thus indicating that HPP combined with a milk matrix positively modulates the bioaccessibility of certain types of bioactive components of food, mainly those of a lipophilic nature.

High-performance liquid chromatographic determination of Maillard compounds in store-brand and name-brand ultra-high-temperature-treated cows’ milk

Furosine and furfural products of the Maillard reaction are used as specific indicators of the effect of heating treatments on milk quality. Their contents were measured in representative samples of store- and name-brand ultra-high-temperature-treated milks using RP-HPLC with UV detection. Furosine contents ranged from 40.32 to 50.67 and from 65.48 to 310.58 mg/100 g protein in name- and store-brand milks, respectively. Of the furfurals, only hydroxymethylfurfural was detected. The free hydroxymethylfurfural contents of store-brand milks ranged from 0.22 to 1.70 mg/100 g protein. Total hydroxymethylfurfural contents ranged from 0.29 to 0.41 and from 0.72 to 2.21 mg/100 g protein, for name- and store-brands, respectively.

Determination of sialic acid and gangliosides in biological samples and dairy products: a review.

Gangliosides are sphingolipids containing one or more moieties of sialic acid in their structure. Both gangliosides and sialic acid are bioactive compounds related to animal physiology. Due to their biological relevance, analytical methods adapted to each type of matrix have been developed over time. The present study reviews the main methods applied to the analysis of sialic acid and gangliosides in biological samples and dairy products.

Environmental cadmium, lead and nickel contamination: possible relationship between soil and vegetable content

SummaryThe cadmium, lead and nickel content of soils of four agricultural areas exposed to different degrees of environmental pollution and vegetables grown there were measured by Atomic Absorption Spectrophotometry (AAS). In order to ascertain the possible relationship between the heavy metal content of soils (total and extractable) and of vegetables grown in them, the correlation between the two was calculated. The highest correlation values between metal content of soil and vegetables are these corresponding to nickel: the total metal content in soils and leaves-stems are linear (p<0.01). The extractable metal content of soils and leaves-stems are linear (p<0.1). Therefore, soil seems to be the main contributor to nickel content of plants (leaves-stems). In the case of cadmium a statistically significant linear correlation (p<0.01) was observed between total metal content in soil and in leaves-stems and a negative one between extractable metal content of soils and that of roots-bulbs. For lead a negative correlation was found between extractable metal content of soils and leaves-stems. In any case, the lead content of soils is not the main factor that influences the lead content of vegetables. Anthropogenic and environmental factors play a more important role than the lead in soils in the lead content of vegetables.

Methylmercury and inorganic mercury determination in fish by cold vapour generation atomic absorption spectrometry

Abstract Given that organic mercury is more dangerous than the inorganic form and that it is converted into methylmercury by biological methylation, we have studied and optimized a simple method for measuring both organic and inorganic mercury contents in fish, using a spectroscopic vapour generation technique, with a sequential reduction of the digested sample with stannous chloride and sodium tetrahydroborate. Prior to applying the method the sample was subjected to alkaline wet digestion. Due to the matrix interferences calibration curves with matrix addition were needed for mercury determinations. The analytical parameters of the method were: linearity from 10 to 200 ng of Hg in the reduction vessel; detection limit: 125 and 183 ng/g fresh sample for inorganic mercury and methylmercury, respectively; precision (RSD%): 9.8 and 10.1 for inorganic mercury and methylmercury, respectively; accuracy: reference material (Dorm-2-NRC-CNRC) for methylmercury; value found 4504±272 ng/g; certified value 4470±320 ng/g. The method offers the advantage of not requiring special equipment to measure inorganic and organic mercury simultaneously in a sample. To evaluate its usefulness it was applied to nine different types of fish and mussels.

Whole blood selenium content in pregnant women

The selenium content in the blood of pregnant women in the Valencian Community, Spain was determined until the end of gestation in order to assess its evolution and detect possible differences in relation to the values corresponding to non-pregnant women of fertile age. A total of 158 blood samples were obtained from 137 pregnant women. Samples were classified as: (a) first; (b) second; and (c) third trimester. Selenium was determined by a flow injection hydride atomic absorption spectrometric method (Seronorm whole blood was used as a quality control check). The selenium values obtained for the three trimesters followed a Gaussian distribution. The intervals for mean found were: (a) 75.7-85.5 micrograms/l; (b) 72.6-81.4 micrograms/l; and (c) 69.9-77.5 micrograms/l. Although a tendency to decrease was observed, no statistical significant differences between the three trimesters of the gestational period were observed. When we compare the values obtained with the blood selenium content of women of fertile age in the Valencian community (87.8-98.8 micrograms/l) by using an ANOVA test, statistically significant differences are found between the selenium values of women of fertile age and those corresponding to pregnant women. The differences, however, are very small and can be partially explained by the level of hemodilution during pregnancy, however, reference values of blood selenium contents in pregnant women should be taken into account.