Determination of total plasma hydroperoxides using a diphenyl-1-pyrenylphosphine fluorescent probe

Plasma hydroperoxides (HPs) are widely accepted to be good indicators of oxidative stress. By means of the method proposed here, which uses diphenyl-1-pyrenylphosphine (DPPP) as a fluorescent probe, all types of plasma HP were determined. The limits of detection and quantification of the method were 0.08 and 0.25 nmol of cumene hydroperoxide (CHP) equivalents in 40 μl of plasma, respectively. The method is satisfactory in terms of precision (5.3% for 14.5 μM CHP eq., n=8), and the recoveries were 91% and 92% after standard additions of 26 and 52 μM CHP, respectively. The selectivity of the proposed method is higher than 96%. Moreover, optimization of the reaction conditions and the addition of ethylenediaminetetraacetic acid (EDTA) disodium salt and 2,6-di-tert-butyl-4-methylphenol (BHT) prevented the formation of HP artifacts during the analysis. Therefore, the proposed method is useful for simple and quantitative determination of total plasma HPs

High-throughput analysis of lipid hydroperoxides in edible oils and fats using the fluorescent reagent diphenyl-1-pyrenylphosphine

A fluorometric method for the determination of hydroperoxides (HP) in edible oils and fats using the reagent diphenyl-1-pyrenylphosphine (DPPP) was developed and validated. Two solvent media containing 100% butanol or a mixture of chloroform/methanol (2:1, v/v) can be used to solubilize lipid samples. Regardless of the solvent used to solubilize the sample, the DPPP method was precise, accurate, sensitive and easy to perform. The HP content of 43 oil and fat samples was determined and the results were compared with those obtained by means of the AOCS Official Method for the determination of peroxide value (PV) and the ferrous oxidation-xylenol orange (FOX) method. The proposed method not only correlates well with the PV and FOX methods, but also presents some advantages such as requiring low sample and solvent amounts and being suitable for high-throughput sample analysis

Estudio de la capacidad fat-binding selectiva de fibras alimentarias y su repercusión sobre el metabolismo lipídico

[spa] Las enfermedades cardiovasculares son la principal causa de mortalidad a nivel mundial. Aunque su origen es multifactorial, entre los factores de riesgo más destacables se encuentran el sobrepeso y la obesidad, así como niveles elevados de lípidos en sangre (dislipemias), cuyas causas más frecuentes son la inactividad física y los malos hábitos alimentarios. Más concretamente, las dietas malsanas suelen caracterizarse por un elevado consumo de calorías, sobre todo en forma de hidratos de carbono y grasa, y un bajo consumo de frutas y verduras. En consecuencia, existe un amplio consenso en torno a la importancia de reducir el consumo de alimentos con un alto contenido en grasa, especialmente en forma de grasas saturadas, trans y colesterol, ya que tienen un efecto hipercolesterolémico; y aumentar el consumo de frutas y verduras, debido a que son una buena fuente de micronutrientes esenciales y fibra. Sin embargo, las estadísticas demuestran que en la mayoría de países industrializados el consumo real de estos alimentos se aleja preocupantemente de las cantidades recomendadas. El consumo de dietas con una elevada presencia de fibra alimentaria se ha correlacionado con un descenso en la incidencia de las enfermedades cardiovasculares. Esto es debido a que su consumo está asociado a numerosos efectos beneficiosos, como la capacidad de reducir la absorción de grasa y los niveles de lípidos plasmáticos. No obstante, es importante tener en cuenta que no todas las fibras presentan las mismas propiedades beneficiosas y que el efecto sobre el metabolismo lipídico que tienen los ácidos grasos, principales constituyentes de la grasa de la dieta, puede diferir considerablemente. En base a estos antecedentes, en la presente Tesis Doctoral se estudió y comparó la capacidad de reducir de manera selectiva la absorción de grasa de fibras con diferentes características fisicoquímicas. Más concretamente, se estudió en cobayas el efecto de la goma guar parcialmente hidrolizada, la maltodextrina resistente a la digestión y el quitosano. Para ello, se determinó el efecto de estas fibras sobre la excreción de lípidos, haciendo especial énfasis en la excreción de esteroles neutros, ácidos biliares y, sobretodo, ácidos grasos. Adicionalmente, se evaluó su repercusión sobre el perfil lipídico de muestras biológicas como el plasma o el hígado. Los resultados demuestran que todas las fibras estudiadas presentan capacidad hipolipidémica, aunque ésta puede ser atribuible a diferentes mecanismos. De las fibras estudiadas sólo la fibra quitosano presenta capacidad fat-binding (ligando de grasa) selectiva, ya que muestra menor afinidad por los ácidos grasos saturados de cadenas largas en comparación con aquellos de cadenas más cortas o a los ácidos grasos insaturados. Como resultado de la capacidad fat-binding selectiva del quitosano se observan cambios en el perfil de ácidos grasos del hígado, y sobre todo del plasma, debido a que puede alterar la relación entre ácidos grasos poliinsaturados n-6 y n-3. En conclusión, la presente Tesis Doctoral permite obtener un mayor conocimiento sobre la capacidad hipolipidémica y los mecanismos de acción de fibras de gran interés en la industria alimentaria debido a su posible incorporación en alimentos o a su uso como complementos alimenticios[eng] Study of the selective fat-binding capacity of dietary fibers and its repercussion on lipid metabolism. Cardiovascular diseases are the leading cause of death in the world. Although its aetiology is multifactorial, high intakes of calories and fats, especially cholesterol-rich fats as well as saturated and trans fatty acids, are widely accepted as major contributing factors. Evidence shows that dietary fiber may play an important role in the prevention of CHD due to its capacity to lower plasma lipid concentrations. In general terms, this effect has mainly been associated with the capacity of dietary fiber to reduce carbohydrate absorption, fat digestibility and bile acid circulation. However, it is widely known that fatty acids, the main constituents of dietary fat, elicit different lipid metabolism responses. Moreover, the beneficial effect of dietary fiber depends on its physicochemical properties. The main aim of this Thesis was to compare the hypolipidemic effect and selective fat-binding capacity of different dietary fibers, namely partially hydrolyzed guar gum, digestion-resistant maltodextrin and chitosan. For this purpose, the effect of these fibers on fatty acid absorption and on neutral sterols and bile acid excretion was determined in guinea pigs. The repercussion of these fibers on the lipid profile of plasma and liver was also evaluated. All the dietary fibers in the study were able to increase lipid excretion, and thus reduce plasma lipids. However, only chitosan was able to selectively reduce fat absorption as its effect on fatty acid excretion was dependent on the chain length and unsaturation degree of the fatty acid. Consequently, chitosan was able to modify the fatty acid profile of liver and plasma, due to changes in the ratio of n-6 and n-3 polyunsaturated fatty acids. In conclusion, these results confirm that dietary fiber can exert different effects on lipid absorption and metabolism, and provide new insight into the hypolipidemic mechanisms of partially hydrolyzed guar gum, digestion-resistant maltodextrin and chitosa

Onion, a natural alternative to artificial food preservatives. Review

Consumer demand of minimally processed foods without synthetic preservatives has led to a growing interest in their replacement for more natural alternatives. Onion is widely used as a food ingredient and it is known as a good source of bioactive compounds, such as sulphur-containing compounds and flavonoids with well known health beneficial effects, antioxidant and antimicrobial capacities. Consequently, onion has been proposed as a promising and safer source of food preservatives. The overall aim of the present review is to analyze its potential use as a food ingredient by reporting evidence of onion antioxidant and antimicrobial activities, as well as discussing some concerns in relation to its stability and effectiveness as a food preservative.Postprint (published version

Onion, a natural alternative to artificial food preservatives. Review

Consumer demand of minimally processed foods without synthetic preservatives has led to a growing interest in their replacement for more natural alternatives. Onion is widely used as a food ingredient and it is known as a good source of bioactive compounds, such as sulphur-containing compounds and flavonoids with well known health beneficial effects, antioxidant and antimicrobial capacities. Consequently, onion has been proposed as a promising and safer source of food preservatives. The overall aim of the present review is to analyze its potential use as a food ingredient by reporting evidence of onion antioxidant and antimicrobial activities, as well as discussing some concerns in relation to its stability and effectiveness as a food preservative

Determination of total plasma hydroperoxides using a diphenyl-1-pyrenylphosphine fluorescent probe

Plasma hydroperoxides (HPs) are widely accepted to be good indicators of oxidative stress. By means of the method proposed here, which uses diphenyl-1-pyrenylphosphine (DPPP) as a fluorescent probe, all types of plasma HP were determined. The limits of detection and quantification of the method were 0.08 and 0.25 nmol of cumene hydroperoxide (CHP) equivalents in 40 μl of plasma, respectively. The method is satisfactory in terms of precision (5.3% for 14.5 μM CHP eq., n=8), and the recoveries were 91% and 92% after standard additions of 26 and 52 μM CHP, respectively. The selectivity of the proposed method is higher than 96%. Moreover, optimization of the reaction conditions and the addition of ethylenediaminetetraacetic acid (EDTA) disodium salt and 2,6-di-tert-butyl-4-methylphenol (BHT) prevented the formation of HP artifacts during the analysis. Therefore, the proposed method is useful for simple and quantitative determination of total plasma HPs

Head and neck cancer surgery during the COVID-19 pandemic: An international, multicenter, observational cohort study

Background: The aims of this study were to provide data on the safety of head and neck cancer surgery currently being undertaken during the coronavirus disease 2019 (COVID-19) pandemic. Methods: This international, observational cohort study comprised 1137 consecutive patients with head and neck cancer undergoing primary surgery with curative intent in 26 countries. Factors associated with severe pulmonary complications in COVID-19–positive patients and infections in the surgical team were determined by univariate analysis. Results: Among the 1137 patients, the commonest sites were the oral cavity (38%) and the thyroid (21%). For oropharynx and larynx tumors, nonsurgical therapy was favored in most cases. There was evidence of surgical de-escalation of neck management and reconstruction. Overall 30-day mortality was 1.2%. Twenty-nine patients (3%) tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within 30 days of surgery; 13 of these patients (44.8%) developed severe respiratory complications, and 3.51 (10.3%) died. There were significant correlations with an advanced tumor stage and admission to critical care. Members of the surgical team tested positive within 30 days of surgery in 40 cases (3%). There were significant associations with operations in which the patients also tested positive for SARS-CoV-2 within 30 days, with a high community incidence of SARS-CoV-2, with screened patients, with oral tumor sites, and with tracheostomy. Conclusions: Head and neck cancer surgery in the COVID-19 era appears safe even when surgery is prolonged and complex. The overlap in COVID-19 between patients and members of the surgical team raises the suspicion of failures in cross-infection measures or the use of personal protective equipment. Lay Summary: Head and neck surgery is safe for patients during the coronavirus disease 2019 pandemic even when it is lengthy and complex. This is significant because concerns over patient safety raised in many guidelines appear not to be reflected by outcomes, even for those who have other serious illnesses or require complex reconstructions. Patients subjected to suboptimal or nonstandard treatments should be carefully followed up to optimize their cancer outcomes. The overlap between patients and surgeons testing positive for severe acute respiratory syndrome coronavirus 2 is notable and emphasizes the need for fastidious cross-infection controls and effective personal protective equipment