A.R. Rodríguez

Effects of dietary fiber and phytic acid on mineral availability

In general, it has been shown that dietary fiber may bind metallic cations in both in vitro and in vivo studies. However, there clearly are many unresolved questions on the effects of high-fiber diets on mineral availability. On one side, the effects of fiber on the utilization of nutrients vary greatly with the amount and type of fiber. In addition, there are many agents in both food and the digestive tract that may affect the mineral binding to fiber: some agents may inhibit binding, while others will enhance it. Also, there are several major difficulties in drawing conclusions from the in vitro and in vivo studies due to the different experimental conditions, methods used to follow the mineral balance, etc. Finally, it must be borne in mind that fiber and phytic acid occur together in fiber-rich diets and, thus, it is difficult to separate the effects of fiber and phytate in the utilization of most essential polyvalent metallic ions. The studies summarized in this review show that the recommendation for increasing dietary fiber in Western communities would not be expected to have any adverse effect on mineral absorption if we increase not only the intake of fiber, but also the dietary intake of other food components such as protein (both vegetable and animal protein) and ascorbic, citric, and oxalic acids (in fruits and vegetables). The adequate intake of minerals, fat, and simple sugars are maintained with this type of diet. The recommendations should be best interpreted in such a way as to prevent the consumption of excessive amounts of phytate, particularly for those whose mineral needs are great. Further studies are still needed in this field in order to understand the conflicting results published in the literature regarding the effects of fiber on the utilization of minerals; however, the studies reviewed in this article may give us an idea of the complexity of mineral availability in fiber-rich, phytate-rich diets.

Antibiotic Prescription for Community-Acquired Pneumonia in the Intensive Care Unit: Impact of Adherence to Infectious Diseases Society of America Guidelines on Survival

BACKGROUND The purpose of our study was to analyze prognostic factors associated with mortality for patients with severe community-acquired pneumonia (CAP). METHODS We conducted a prospective multicenter study including all patients with CAP admitted to the intensive care unit during a 15-month period in 33 Spanish hospitals. Admission data and data on the evolution of the disease were recorded. Multivariate analysis was performed using the SPSS statistical package (SPSS). RESULTS A total of 529 patients with severe CAP were enrolled; the mean age (+/-SD) was 59.9+/-16.1 years, and the mean Acute Physiology and Chronic Health Evaluation (APACHE) II score (+/-SD) was 18.9+/-7.4. Overall mortality among patients in the intensive case unit was 27.9% (148 patients). The rate of adherence to Infectious Diseases Society of America (IDSA) guidelines was 57.8%. Significantly higher mortality was documented among patients with nonadherence to treatment (33.2% vs. 24.2%). Multivariate analysis identified age (odds ratio [OR], 1.7), APACHE II score (OR, 4.1), nonadherence to IDSA guidelines (OR, 1.6), and immunocompromise (OR, 1.9) as the variables present at admission to the intensive care unit that were independently associated with death in the intensive care unit. In 15 (75%) of 20 cases of Pseudomonas aeruginosa infection, the antimicrobial treatment at admission was inadequate (including 8 of 15 cases involving patients with adherence to IDSA guidelines). Chronic obstructive pulmonary disease (OR, 17.9), malignancy (OR, 11.0), previous antibiotic exposure (OR, 6.2), and radiographic findings demonstrating rapid spread of disease (OR, 3.9) were associated with P. aeruginosa pneumonia. CONCLUSIONS Better adherence to IDSA guidelines would help to improve survival among patients with severe CAP. Pseudomonas coverage should be considered for patients with chronic obstructive pulmonary disease, malignancy, or recent antibiotic exposure.

Implications of COPD in patients admitted to the intensive care unit by community- acquired pneumonia

The mortality rate of chronic obstructive pulmonary disease (COPD) patients with community-acquired pneumonia (CAP) is reported to be low. However, studies carried out to date have included <20% of critically ill patients. The current authors performed a secondary analysis of a prospective study evaluating 428 immunocompetent patients admitted to the intensive care unit (ICU) for severe CAP. In total, 176 COPD patients were compared with 252 non-COPD patients. In COPD patients, ICU mortality (odds ratio (OR) 1.58; 95% confidence interval (CI) 1.01–1.43) and mechanical ventilation (OR 2.78; 95% CI 1.63–4.74) rates were higher than in non-COPD patients. The ICU mortality was 39% for COPD patients initially intubated and 50% for those who failed noninvasive ventilation. The proportion of patients who were males, aged ≥70 yrs, smokers and who had chronic heart disease or Pseudomonas aeruginosa were higher in COPD patients. Inappropriate empirical antibiotic therapy was associated with higher mortality (OR 3.8; 95% CI 1.19–12.6). ICU mortality in COPD patients with adequate therapy was associated with bilateral pneumonia (OR 2.32; 95% CI 1.18–4.53) and shock (OR 3.53; 95% CI 1.31–9.71). In conclusion, chronic obstructive pulmonary disease patients hospitalised with community-acquired pneumonia in the intensive care unit had higher mortality and need of mechanical ventilation when compared with patients without chronic obstructive pulmonary disease.

Interactions of Fe(II), Ca(II) and Fe(III) with high dietary fibre materials: A physicochemical approach

Abstract Interactions of Fe(II), Ca(II), and Fe(III) with five natural food materials, which should be used as fibre sources in the diet, such as pomaces from the production of white wine, cider and olive oil, and lemon peel and pulp, were investigated in vitro. The extent of mineral binding by these concentrates of fibre depended both on the nature and chemical composition of the sample used and on the type of mineral element studied; however, the majority of these samples exhibited a higher capacity to bind Fe(II) than Ca(II) and Fe(III). Two graphic methods have been used to provide basic information on the mineral binding mechanisms for the interactions of these cations with the high-fibre samples: the Scatchard plot, for examining binding by complex formation, and the equation of Langmuir, to predict cation retention by physical adsorption.

Determination of vanadium, nickel, iron, copper, and lead in petroleum fractions by atomic absorption spectrophotometry with a graphite furnace

Abstract Vanadium, nickel, iron, copper, and lead contents in several samples of petroleum and its by-products having an organic matrix with a different composition have been determined by atomic absorption Spectrophotometry with a graphite furnace. Different parameters, in particular, drying, charring, and atomization temperatures, have been studied. Analytical characteristics, such as sensitivity, detection limit, linearity domain, precision, and accuracy, have also been studied. The last study has been carried out using organometallic standards and NBS reference standards samples.

Retention of organic ligands on anionic and nonionic resins: Application to the separation and preconcentration of metal ions

Abstract Complexing resins obtained by retention of an organic compound on anionic and nonionic conventional exchangers have been reviewed. The influence of different parameters—nature of fixed ligand, kind and chemical form of the conventional resin, and pH of the aqueous solution—on characteristics and applications of this type of resin has been discussed. Results from the literature have been tabulated to simplify their presentation.

Spectrophotometric and potentiometric study of the complexes originated by the trisodium salt of 2-(p-sulfophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (SPADNS) and several metal ions

A study of the complexes originated by U(VI), Cu(II), Pb(II), Ni(II), Co(II), Zn(II), Cd(II), Mn(II), Ca(II), Mg(II), Ba(II), and Sr(II), and SPADNS (trisodium salt of 2-(p-sulfophenylazo)-1, 8-dihydroxynaphthalene-3,6-disulfonic acid) has been made by means of spectrophotometric and potentiometric methods. The dissociation constants of the ligand and the formation constants of the metal ion-SPADNS complexes have been determined at 25 ± 0.1 °C and ionic strength 0.1 (NaClO4).

Preconcentration of metal ions from natural water samples on an ion-exchange resin loaded with SPADNS

Abstract An ion-exchange resin loaded with SPADNS has been used for preconcentration of metal ions from synthetic and natural samples. Copper and iron at nanogram per milliliter levels in drinking waters have been determined satisfactorily.

Study of analytical methods for iron determination in complex organic liquids by atomic absorption spectrometry

Abstract In the determination of iron in complex organic liquids by atomic absorption spectrometry (A. A. S.), methods of sample preparation, such as dilution with an organic solvent and sample pretreatment to destroy organic material, are investigated. Moreover, methods of analysis using calibration curve and standard additions are presented. The possible cause of error associated with iron determination in organic samples by flame (F-A. A. S.) and graphite furnace (GF-A. A. S.) atomic absorption spectrometry are discussed. From all of these studies, the use of graphite furnace atomic absorption spectrometry after sample dilution with methyl isobutyl ketone, and the use of the method of standard additions are advised for iron determination.

Study of SPADNS as mobile-phase complexing agent for metal ion separation in reversed-phase high-performance liquid chromatography

Abstract The possibility of employing SPADNS as a mobile-phase complexing agent in RP-HPLC determination of metal ions has been investigated. Separation of Fe(II), Cu(II), and SPADNS has been performed using a 50:50 ( v v ) methanol-water mixture 0.02 M in TBA and 10−5 M in SPADNS as mobile phase. Sensitivity was very poor with this mobile phase. When the SPADNS concentration in the solution was increased to 10−3 M, sensitivity improved and detection limits of 2.1 and 1.7 ppm for Fe(III) and Cu(II), respectively, were obtained. However, no selectivity was obtained under these conditions.