Vitamin D3 levels in women and factors contributing to explain metabolic variations

The elucidated metabolism of vitamin D₃ in humans has been the support to explain the high involvement of this liposoluble vitamin in physiological functions. Clinical studies have associated levels of vitamin D₃ metabolites with several disorders. Despite this knowledge, there is a controversy regarding the estimation of deficiency and the physiological and supraphysiological levels of vitamin D₃ metabolites. The association between serum concentrations of vitamin D₃ metabolites and several potentially influential factors (namely, age and anthropometric, seasonal, spatial and metabolic factors) is analyzed in this study. For this purpose, 558 women were recruited and interviewed in several Spanish provinces before blood sampling. Serum vitamin D₃ and its metabolites were determined using an SPE-LC-MS/MS platform. The concentration range for vitamin D₃ was 1.7-21.1 nmol/L and was influenced by body mass index (BMI), waist-to-hip ratio (WHR) and seasonal period. 25-hydroxyvitamin D₃ levels were within 4.8-147.2 nmol/L and were related to WHR, season, latitude and calcium intake. The range of 24,25-dihydroxyvitamin D₃, 0.3-15.0 nmol/L, was associated to BMI, WHR, season, latitude and calcium intake. Finally, energy intake influenced the vitamin D 25-hydroxylase through the 25-hydroxyvitamin D₃/vitamin D₃ ratio, which regulates the synthesis of the circulating form. According to these results, it is worth emphasizing the relevance of all these factors to explain the variability in serum levels of vitamin D₃ and its metabolites. All these factors should be considered in future studies assessing the alteration of vitamin D₃ metabolism.

Profiling analysis of phospholipid fatty acids in serum as a complement to the comprehensive fatty acids method

Fatty acids (FAs) are mostly found in blood as triglycerides, phospholipids (PLs) and cholesteryl esters. Determination of FAs is typically carried out in serum or plasma by a comprehensive method (known as the classical FAMEs method since FAs are determined as Fatty Acids Methyl Esters), which is based on liquid-liquid extraction, derivatization by transesterification, and determination by gas chromatography (GC) coupled to a suited detection technique. However, this method does not favor the determination of FAs that are chemically conjugated in PLs due to kinetics impediment. For this reason, we have developed a selective method to determine the FAs profile of PLs in serum based on solid-phase extraction (SPE) for isolation of PLs and determination of the FAME derivatives by GC-mass spectrometry (GC-MS). The method was applied to serum samples collected from twenty-five individuals to compare the FAs profile versus that provided by the non-selective protocol based on liquid-liquid extraction of lipid families. Statistical analysis revealed compositional changes in the FAs profile with special emphasis on the content of saturated (SFAs) and monounsaturated FAs (MUFAs). Thus, SFAs passed from 34.0% with the classical method to 49.3% in PLs while MUFAs went from 24.4% to 11.4%. This study proves that the proposed method provides complementary results to the comprehensive method and, therefore, both methods can be combined to evaluate the effect of intervention diets and their connection to metabolic diseases.

Determination of glycerophospholipids in vegetable edible oils: Proof of concept to discriminate olive oil categories

Glycerophospholipids (GPLs) constitute a chemical family within the saponifiable fraction of vegetable oils. GPLs have been scarcely studied in edible oils owing to the lack of sensitive and selective analytical methods. We have developed a method for identification, confirmation and relative quantitation of GPLs in vegetable oils. The method is based on solid-phase extraction (SPE) for isolation of GPLs and determination by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). As proof of concept, the approach has been applied to characterize GPLs in different olive oil categories, thus revealing compositional changes, which could be explained by factors such as the quality of fruits and the extraction process. Families such as glycerophosphatidic acids and phosphatidylglycerides are remarkable because of their capability to discriminate virgin olive oils from the rest of categories. These results open a door to additional studies targeted at the identification of olive oil quality by monitoring these lipids.

Serum 25-hydroxyvitamin D and mammographic density in premenopausal Spanish women

The role of vitamin D in mammographic density is still unclear. This study examines the association between serum 25-hydroxyvitamin D (25(OH)D) and mammographic density, overall and by specific women characteristics. DDM-Madrid is a cross-sectional study that recruited 1403 premenopausal women in a breast radiodiagnosis unit of Madrid City Council. Information was collected with a questionnaire and plasma 25(OH)D was measured by solid-phase extraction on-line coupled to liquid chromatography-tandem mass spectrometry. Percent mammographic density was assessed using a semi-automated computer tool (DM-Scan). Multivariable linear regression models were used to quantify the associations, categorizing 25(OH)D levels (nmol/L) into 3 groups according to the cut-offs established by the US Endocrine Society. Models were adjusted for age, education, body mass index, age at menarche, parity, previous breast biopsies, family history of breast cancer, physical activity, energy intake, use of corticoids, hypercholesterolemia and day of sample extraction. Mean serum 25(OH)D level was 49.4 + 18.9 nmol/L. Women with sufficient concentrations of 25(OH)D showed a slight decrease in mammographic density (β _>75nmol/L=-3.40; p = 0.037). No differences were observed according to women characteristics except for parity, where the protective effect of 25(OH)D was only seen among nulliparous (β _>75nmol/L=-13.00; p-heterogeneity = 0.006). In light of the protective effect of vitamin D on mammographic density and the high prevalence of vitamin D insufficiency in our population, improving these levels could be an effective measure for the prevention of health problems related to the lack of this essential vitamin.

Serum 25-hydroxyvitamin D and breast cancer risk by pathological subtype (MCC-Spain)

Epidemiologic evidence on the association between vitamin D and breast cancer is still inconclusive. This study analyzes the association between serum 25-hydroxyvitamin D (25(OH)D) and breast cancer risk by pathologic subtype, stage at diagnosis and specific breast cancer risk factors. We conducted a population-based multicase-control study where 546 histologically-confirmed breast cancer cases and 558 population controls, frequently matched by geographic area, age and body mass index, were recruited in 12 Spanish provinces (MCC-Spain). Information was collected by a questionnaire and plasma 25(OH)D was measured by solid-phase extraction on-line coupled to liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS). Odds ratios and 95% confidence intervals were calculated using logistic and multinomial mixed regression models. We found a clear protective effect between 25(OH)D levels and breast cancer risk, with a significant dose-response trend (OR per 10 nmol/L = 0.88; 95%CI = 0.82-0.94). While no differences were observed between pre and postmenopausal women, stage at diagnosis, or across strata of the main breast cancer risk factors, the protection was more pronounced for triple negative tumors (OR per 10 nmol/L = 0.64; p-heterogeneity = 0.038). Similar results were observed when only cases sampled in the first month after diagnosis were considered. The protective effect of vitamin D on breast cancer risk may be subtype specific, being stronger for more aggressive tumors, which provides a new approach to prevent this disease.

Oleocanthalic Acid, a Chemical Marker of Olive Oil Aging and Exposure to a High Storage Temperature with Potential Neuroprotective Activity

The investigation of olive oils stored for a period of 24 months under appropriate conditions (25 °C, dark place, and airtight container) led to the identification of a new major phenolic ingredient, which was named oleocanthalic acid. The structure of the new compound was elucidated using one- and two-dimensional nuclear magnetic resonance in combination with tandem mass spectrometry. The new compound is an oxidation product of oleocanthal and is found in fresh oils in very low concentrations. The concentration of oleocanthalic acid increased with storage time, while the oleocanthal concentration decreased. A similar increase of the oleocanthalic acid/oleocanthal ratio was achieved after exposure of olive oil to 60 °C for 14 days. Although the presence of an oxidized derivative of decarboxymethylated ligstroside aglycon had been reported, it is the first time that its structure is characterized. The isolated compound could induce the expression of amyloid-β major transport proteins as well as tight junctions expressed at the blood-brain barrier, suggesting that oleocanthalic acid could be beneficial against Alzheimer's disease.

Cultivar influence on variability in olive oil phenolic profiles determined through an extensive germplasm survey

Despite the evident influence of the cultivar on olive oil composition, few studies have been devoted to exploring the variability of phenols in a representative number of monovarietal olive oils. In this study, oil samples from 80 cultivars selected for their impact on worldwide oil production were analyzed to compare their phenolic composition by using a method based on LC-MS/MS. Secoiridoid derivatives were the most concentrated phenols in virgin olive oil, showing high variability that was significantly due to the cultivar. Multivariate analysis allowed discrimination between four groups of cultivars through their phenolic profiles: (i) richer in aglycon isomers of oleuropein and ligstroside; (ii) richer in oleocanthal and oleacein; (iii) richer in flavonoids; and (iv) oils with balanced but reduced phenolic concentrations. Additionally, correlation analysis showed no linkage among aglycon isomers and oleocanthal/oleacein, which can be explained by the enzymatic pathways involved in the metabolism of both oleuropein and ligstroside.

Abstract P3-09-01: Withdrawn

This abstract was withdrawn by the authors.

Pharmacokinetics and pharmacodynamics of ramipril and ramiprilat after intravenous and oral doses of ramipril in healthy horses

The pharmacokinetics and pharmacodynamics (PK/PD) of the angiotensin-converting enzyme inhibitor (ACEI) ramiprilat after intravenous (IV) and oral (PO) administration of ramipril have not been evaluated in horses. This study was designed to establish PK profiles for ramipril and ramiprilat as well as to determine the effects of ramiprilat on serum angiotensin converting enzyme (ACE) and to select the most appropriate ramipril dose that suppresses ACE activity. Six healthy horses in a cross-over design received IV ramipril 0.050 mg/kg, PO at a dose of 0 (placebo), and 0.050, 0.10, 0.20, 0.40 and 0.80 mg/kg ramipril. Blood pressures were measured and blood samples obtained at different times. Serum ramipril and ramiprilat concentrations and serum ACE activity were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and spectrophotometry, respectively. Systemic bioavailability of ramiprilat after PO ramipril was 6-9%. Percentages of maximum ACE inhibitions from baseline were 98.88 (IV ramipril), 5.31 (placebo) and 27.68, 39.27, 46.67, 76.13 and 84.27 (the five doses of PO ramipril). Blood pressure did not change during the experiments. Although oral availability of ramiprilat was low, ramipril has sufficient enteral absorption and bioconversion to ramiprilat to induce serum ACE inhibitions of almost 85% after a dose of 0.80 mg/kg ramipril. Additional research on ramipril administration in equine patients is indicated.

Study of blood collection and sample preparation for analysis of vitamin D and its metabolites by liquid chromatography-tandem mass spectrometry

The analysis of vitamin D status, with special emphasis on 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, is gaining interest in clinical studies due to the classical and non-classical effects attributed to this prohormone. In this research, the influence of the two steps preceding determination (viz. sample collection and preparation) on the quantitative analysis of vitamin D and its more important metabolites has been studied. Two preparation approaches, deproteination and solid-phase extraction (SPE), have been evaluated in terms of sensitivity to delimit their application, thus establishing that detection of 1,25-dihydroxyvitamin D cannot be addressed by protein precipitation. Concerning sample collection, serum and plasma reported high accuracy (above 83.3%) for vitamin D and metabolites, while precision, expressed as relative standard deviation, was below 12.9% for all analytes in both samples. Statistical analysis revealed that serum and plasma provided similar physiological levels for vitamin D3, 24,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3, while significantly different levels were obtained for 1,25-dihydroxyvitamin D3, always higher in plasma than in serum. Sample collection and treatment have proved to be significant in the analysis of vitamin D and its relevant metabolites.