Micronutrientes antioxidantes en leche materna madura de dos grupos indígenas venezolanos / Antioxidant minerals in mature breast milk of two groups ethnic from Venezuela

Fundamento: La leche materna por su contenido de micronutrientes representa el alimento ideal para el neonato en las defensas del organismo contra los radicales libres. Nuestro objetivo fue determinar el contenido de micronutrientes antioxidantes en leche materna madura de mujeres perteneciente a dos grupos indígenas de la región zuliana. Materiales y métodos: Se colectaron 68 muestras de leche materna Barí y 65 muestras de Wayuú. Con propósitos comparativos se tomaron 76 muestras de leche de mujeres no indígenas. Las concentraciones totales de cobre y zinc fueron determinadas mediante espectrometría de absorción atómica. La vitamina C se cuantificó por el método del ácido fosfotúngstico. Los datos fueron analizados mediante las pruebas de ANOVA y Tukey (SPSS 12.0). Resultados: Los resultados obtenidos mostraron variaciones significativas entre los grupos (p<0,05). Los valores de cobre fueron más bajos en leche materna Barí (0,12±0,02 mg/L), cuando se comparó con las no indígenas (0,34±0,04 mg/L) (p<0,05), pero fue estadísticamente similar al grupo Wayuú (0,21±0,03 mg/L). El zinc se encontró a concentraciones más bajas en las Barí (0,66±0,07 mg/L) en comparación con las leches de Wayuú (2,63±0,43 mg/L) y no indígenas (2,17±0,34 mg/L) (p<0,05). El contenido de vitamina C fue significativamente más bajo en las Barí (5,81±1,62 mg/L) y Wayuú (5,83±3,24 mg/L) vs. el grupo control (35,66±15,94 mg/L) (p<0,05). Conclusiones: Se observó una importante disminución de los micronutrientes analizados en las muestras de leche materna madura Barí y Wayuú, lo que pudiera causar deficiencia de estos antioxidantes en los niños que reciben lactancia materna exclusiva (AU)

Background: Breast milk micronutrient content represents the ideal food for the baby in the body?s defenses against free radicals. Our objective was to determine the micronutrient content of antioxidants in mature breast milk of women belonging to two indigenous groups in the Zulia region. Materials and methods: We collected 68 samples of breast milk and 65 samples Bari Wayuú. For comparative purposes were taken 76 samples of milk from non-indigenous women. The total concentrations of copper and zinc were determined by atomic absorption spectrometry. Vitamin C was quantified by phosphotungstic acid method. The data were analyzed using the ANOVA and Tukey tests (SPSS 12.0). Results: The results showed significant variations between groups (p <0.05). Copper values were lower in breast milk Bari (0.12 ± 0.02 mg / L), when compared with non-indigenous (0.34 ± 0.04 mg / L) (p <0.05) but was statistically similar to Wayuú group (0.21 ± 0.03 mg/ L). Zinc is found at lower concentrations in Bari (0.66± 0.07 mg / L) compared with Wayuú milks (2.63 ± 0.43 mg / L) and non-indigenous (2.17 ± 0.34 mg / L) (p <0.05). The content of vitamin C was significantly lower in Bari (5.81 ± 1.62 mg / L) and Wayuu (5.83 ± 3.24 mg / L) vs. the control group (35.66 ± 15.94 mg / L) (p <0.05). Conclusions: We observed a significant reduction in micronutrients analyzed in mature breast milk samples and Wayuú Bari, which could cause a deficiency of these antioxidants in children who are exclusively breastfed (AU)

Rapid phenotypic characterization of Vibrio isolates by pyrolysis metastable atom bombardment mass spectrometry.

Pyrolysis mass spectrometry was investigated for rapid characterization of food-borne bacterial pathogens. Nine isolates of Vibrio parahaemolyticus and one isolate each of Vibrio fluvialis, Vibrio hollisae, and Vibrio vulnificus were analyzed. Pyrolysis mass spectra, generated via an alternative ionization method, metastable atom bombardment, were subject to principal component-discriminant analysis. The spectral patterns were used to distinguish Vibrio isolates differing in species, serotype and expression of the thermostable direct hemolysin gene. The patterns of similarity and dissimilarity amongst spectra in the Vibrio test set generally reflected those associated with species, serotype or hemolysin-producing genes, though the combined influence of these and other variables in the multi-dimensional data did not produce a simple clustering with respect to any one of these characteristics. These results suggested that with enough examples to model the most common combinations, the method should be able to characterize Vibrio isolates according to their phenotypic characteristics. Pyrolysis-mass spectrometry with metastable atom bombardment and pattern recognition appeared suitable for rapid infraspecific comparison of Vibrio isolates. This integrated analytical, pattern-recognition system should be examined further for potential utility in clinical and public health diagnostic contexts.

'Bubble chamber model' of fast atom bombardment induced processes.

A hypothesis concerning FAB mechanisms, referred to as a 'bubble chamber FAB model', is proposed. This model can provide an answer to the long-standing question as to how fragile biomolecules and weakly bound clusters can survive under high-energy particle impact on liquids. The basis of this model is a simple estimation of saturated vapour pressure over the surface of liquids, which shows that all liquids ever tested by fast atom bombardment (FAB) and liquid secondary ion mass spectrometry (SIMS) were in the superheated state under the experimental conditions applied. The result of the interaction of the energetic particles with superheated liquids is known to be qualitatively different from that with equilibrium liquids. It consists of initiation of local boiling, i.e., in formation of vapour bubbles along the track of the energetic particle. This phenomenon has been extensively studied in the framework of nuclear physics and provides the basis for construction of the well-known bubble chamber detectors. The possibility of occurrence of similar processes under FAB of superheated liquids substantiates a conceptual model of emission of secondary ions suggested by Vestal in 1983, which assumes formation of bubbles beneath the liquid surface, followed by their bursting accompanied by release of microdroplets and clusters as a necessary intermediate step for the creation of molecular ions. The main distinctive feature of the bubble chamber FAB model, proposed here, is that the bubbles are formed not in the space and time-restricted impact-excited zone, but in the nearby liquid as a 'normal' boiling event, which implies that the temperature both within the bubble and in the droplets emerging on its burst is practically the same as that of the bulk liquid sample. This concept can resolve the paradox of survival of intact biomolecules under FAB, since the part of the sample participating in the liquid-gas transition via the bubble mechanism has an ambient temperature which is not destructive for biomolecules. Another important feature of the model is that the timescale of bubble growth is no longer limited by the relaxation time of the excited zone ( approximately 10(-12) s), but rather resembles the timescale characteristic of common boiling, sufficient for multiple interactions of gas molecules and formation of clusters. Further, when the bubbles burst, microdroplets are released, which implies that FAB processes are similar to those in spraying techniques. Thus, two processes contribute to the ion production, namely, release of volatile solvent clusters from bubbles and of non-volatile solute from sputtered droplets. This view reconciles contradictory views on the dominance of either gas-phase or liquid-phase effects in FAB. Some other effects, such as suppression of all other ions by surface-active compounds, are consistent with the suggested model.

(26)Al investigations at the AMS-laboratory in Lund.

At the accelerator mass spectrometry (AMS) laboratory in Lund, a facility for (26)Al analysis is under development. The sensitivity is expected to be several orders of magnitude higher than with standard mass spectrometry. The planned biomedical program includes studies of aluminium uptake, distribution and retention in man. The initial work has been concentrated on the construction and testing of a new dedicated injector for the accelerator and on the preparation of biological samples for aluminium analysis. The current quality of the facility is presented and the first experimental results reported.

Laser desorption fast gas chromatography-mass spectrometry in supersonic molecular beams.

A novel method for fast analysis is presented. It is based on laser desorption injection followed by fast gas chromatography-mass spectrometry (GC-MS) in supersonic molecular beams. The sample was placed in an open air or purged laser desorption compartment, held at atmospheric pressure and near room temperature conditions. Desorption was performed with a XeCl Excimer pulsed laser with pulse energy of typically 3 mJ on the surface. About 20 pulses at 50 Hz were applied for sample injection, resulting in about 0.4 s injection time and one or a few micrograms sample vapor or small particles. The laser desorbed sample was further thermally vaporized at a heated frit glass filter located at the fast GC inlet. Ultrafast GC separation and quantification was achieved with a 50-cm-long megabore column operated with a high carrier gas flow rate of up to 240 mL/min. The high carrier gas flow rate provided effective and efficient entrainment of the laser desorbed species in the sweeping gas. Following the fast GC separation, the sample was analyzed by mass spectrometry in supersonic molecular beams. Both electron ionization and hyperthermal surface ionization were employed for enhanced selectivity and sensitivity. Typical laser desorption analysis time was under 10 s. The laser desorption fast GC-MS was studied and demonstrated with the following sample/matrices combinations, all without sample preparation or extraction: (a) traces of dioctylphthalate plasticizer oil on stainless steel surface and the efficiency of its cleaning; (b) the detection of methylparathion and aldicarb pesticides on orange leaves; (c) water surface analysis for the presence of methylparathion pesticide; (d) caffeine analysis in regular and decaffeinated coffee powder; (e) paracetamol and codeine drug analysis in pain relieving drug tablets; (f) caffeine trace analysis in raw urine; (g) blood analysis for the presence of 1 ppm lidocaine drug. The features and advantages of the laser desorption fast GC-MS are demonstrated and discussed.

A new strategy for MALDI on magnetic sector mass spectrometers with point detectors.

We have developed a new strategy to perform matrix-assisted laser desorption/ionization (MALDI) on magnetic sector instruments equipped with nonintegrating point detectors. This approach is based on using liquid matrices to provide very long-lasting analyte ion currents and to overcome the inability of these instruments to simultaneously detect ions over a range of mass-to-charge values. Here, we demonstrate some of the capabilities of MALDI on a magnetic sector for analyzing biological samples. These capabilities include the ability to perform MS/MS experiments, to attain resolutions over 8000 (full width at half-maximum), and to determine relative molecular masses with < 20 ppm error for a single measurement and < 2 ppm error for the average of five measurements. All three of these experiments can be performed on the same 10 pmol sample loading. We also compare the results of MALDI on a magnetic sector instrument with point detection with the reported capabilities of MALDI on time-of-flight-based mass analyzers and with fast atom bombardment on sector-based instruments. This work demonstrates that researchers with magnetic sector-based instruments can perform MALDI experiments with a relatively simple and inexpensive upgrade to their existing equipment.

Coaxial continuous-flow fast-atom bombardment vs electrospray ionization: a sensitivity comparison on a magnetic sector instrument.

The performance of an electrospray (ESI) source was evaluated and compared to that of a coaxial continuous-flow fast-atom bombardment source on a magnetic mass spectrometer using ten different peptides over the mass range of 400 to 3500 Da and using a variety of scanning modes. Results show that sensitivities using the two ionization techniques are similar, with limits-of-detection in the attomole to low femtomole range. In addition, proteins can be routinely detected using ESI at femtomole levels. The observance of the noncovalent complex of RNase A and cytidine 2'-monophosphate yields evidence that these complexes can be studied using instruments that operate at high accelerating voltages.

Analytical instruments for stable isotopic tracers in mineral metabolism.

Thermal ionization mass spectrometry (TIMS) is the best of four currently used techniques for obtaining results of high accuracy and precision in studies of metal metabolism. TIMS is also the most general technique because it allows measurements of all the metallic elements of interest. The highest absolute sensitivity as well as the ability to determine multiple elements are simultaneously obtained with inductively coupled plasma mass spectrometry (ICP-MS). Current results with this technique show that, although element quantification may be done with acceptable accuracy and precision, use of ICP-MS in metabolic studies at low levels of isotopic labels may be limited. The most favorable elements for study using ICP-MS in metabolic studies appear to be Mg, Zn and possibly Fe. Use of this technique is limited further by isobaric interferences from plasma jet ion molecule reactions, and metabolic studies of Ca are particularly limited. Acceptable levels of accuracy and precision have been obtained from fast atom bombardment-secondary ion mass spectrometry (FAB-SIMS), which has allowed these approaches to be used in metabolic studies of ZN, Fe and Ca, but the approaches are ultimately limited by hydride isobaric interferences. Both FAB-SIMS and gas chromatography-mass spectrometry of metal chelates have the advantage of using widely available instrumentation. GC-MS of metal chelates has been shown to be useful in studies of Cr and Se metabolism and for the determination of a number of other metals. Values of accuracy and precision from use of this approach have been satisfactory.

Semi-quantitative analysis of cefaclor in human serum by capillary high performance liquid chromatography/fast atom bombardment mass spectrometry.

Capillary high performance liquid chromatography (HPLC) was combined with frit fast atom bombardment (FAB) mass spectrometry (MS) and a detailed procedure has been established for on-line analysis of cefaclor in human serum. The capillary column (0.3 mm i.d.) enabled the introduction of entire effluent to the frit interface for FAB-MS; and a special column switching device for injection and concentration enabled the injection of as large as a 500-microliters volume sample. These conditions gave much higher sensitivity than that of previous HPLC/MS system. Thus, low levels of cefaclor could be successfully identified in sera by its mass spectral measurements 2 h after its single oral administration of a 250-mg capsule in two subjects.

Direct interfacing of high-speed countercurrent chromatography to frit electron ionization, chemical ionization, and fast atom bombardment mass spectrometry.

Direct interfacing of analytical high-speed countercurrent chromatography (HSCCC) to mass spectrometry (MS) was demonstrated for the first time, and its performance was evaluated in terms of chromatography and mass spectrometry. HSCCC/MS interface was based upon Frit electron ionization (EI), chemical ionization (CI), and fast atom bombardment (FAB). Separations were conducted by newly developed HSCCC-4000 with a 2.5-cm revolutional radius and 0.3 mm or 0.55 mm i.d. multilayer coiled column which is capable of operating at a maximum speed of 4000 rpm. To demonstrate the potential capability of HSCCC/frit MS, three indole auxin mixtures, two mycinamicin (macrolide antibiotics) mixtures, and a colistin complex (peptide antibiotics) were analyzed under HSCCC/frit EI, CI, and FABMS conditions, respectively. The data obtained indicated that interfacing to frit/MS does not adversely affect the chromatographic resolution and mass spectra provide structural information. The HSCCC system interfaced with a frit-equipped mass spectrometer will offer a new dimension in the separation of biologically important substances.

Biomedical applications of high-performance liquid chromatography-mass spectrometry with continuous-flow fast atom bombardment.

This report describes the application of high-performance liquid chromatography combined with continuous-flow fast atom bombardment mass spectrometry to analytical problems in the biomedical laboratory. Applications include the compound-specific detection of diagnostic acylcarnitines in human urine, the separation and analysis of acyl-coenzyme A thioesters, and qualitative studies on complex mixtures of modified peptides (dansyl and dinitrophenyl derivatives). For each of these applications standard analytical columns (3.9 mm I.D.) and 1 ml/min flow-rates were employed with post-column stream splitting (1:100) before mass spectrometry. Various mobile phase compositions and solvent gradients were employed. The addition of 1-5% glycerol to the mobile phase was shown to have little effect on the chromatography. For all compounds studied (acylcarnitines, acyl-coenzyme A thioesters, and derivatized peptides) molecular weight information was obtained and sufficient sensitivity was achieved to allow unambiguous identification of trace components in complex mixtures.

Capillary zone electrophoresis-mass spectrometry using a coaxial continuous-flow fast atom bombardment interface.

Mixtures of peptides have been analyzed by capillary zone electrophoresis in conjunction with mass spectrometry (MS) using an on-line coaxial continuous-flow fast atom bombardment interface. MS and MS-MS spectra have been acquired in electrophoretic real time from femtomole levels of the peptides, while maintaining separation efficiencies in excess of 100,000 theoretical plates.