Newborn Exposure to Polycyclic Aromatic Hydrocarbons Through Parenteral Nutrition.

BACKGROUND AND OBJECTIVES: Parenteral nutrition (PN) administered to newborns (NB) may be contaminated with polycyclic aromatic hydrocarbons (PAHs) and may therefore increase the contact with these toxicants in very early life stages. The aim of the study is to determine to what extent, if any, commercial products for PN are contaminated with PAHs and to determine whether these contaminants, when present in the bag content, are delivered to NB and whether 1-hydroxypyrene (1-HP), the pyrene metabolite, can be detected in the urine of exposed NB. METHODS: Commercial products and the bags administered to 10 NB during their period in the NICU were analyzed for the 16 priority US Environmental Protection Agency PAHs. Urine samples were collected and analyzed for their 1-HP content. Urine samples of a control group composed of 8 breastfed NB were also analyzed for the determination of 1-HP. RESULTS: From 9 different commercial products used to compound PN bags, 6 were contaminated with PAHs, with total concentrations varying from 0.02 to 10.56 mg/L. In the bags administered to the NB, this sum varied from 0.01 to 6.30 mg/L with a mean of 2.62 mg/L. Therefore, for each 100 mL PN, an average load of 0.26 mg PAHs was observed. The majority of the urine samples taken from NB in the study group (80%) contained 1-HP, but it was not detected in the urine of any baby in the control group. CONCLUSIONS: The contamination of PN with PAHs poses a critical toxicological risk. The elevated contaminant concentrations and the parenteral way of administration make this source of PAHs considerably worse than any other, including maternal exposure to environmental pollution or tobacco.

Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 µg/L for nitrated and from 0.1 to 6.6 µg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6-191 µg/L for nitrated and 0.3-8.9 µg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2-nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected.

Determination of polycyclic aromatic hydrocarbons in fractions in asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

An analytical method using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization for the determination of polycyclic aromatic hydrocarbons in asphalt fractions has been developed. The 14 compounds determined, characterized by having two or more condensed aromatic rings, are expected to be present in asphalt and are considered carcinogenic and mutagenic. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all of the compounds. The limits of detection ranged from 0.5 to 346.5 µg/L and the limits of quantification ranged from 1.7 to 1550 µg/L. The method was validated against a diesel particulate extract standard reference material (NIST SRM 1975), and the obtained concentrations agreed with the certified values. The method was applied to asphalt samples after its fractionation according to ASTM D4124 and the method of Green. The concentrations of the seven polycyclic aromatic hydrocarbons quantified in the sample ranged from 0.86 mg/kg for benzo[ghi]perylene to 98.32 mg/kg for fluorene.

Methionine stimulates motor impairment and cerebellar mercury deposition in methylmercury-exposed mice.

Methylmercury (MeHg) is a highly toxic environmental contaminant that produces neurological and developmental impairments in animals and humans. Although its neurotoxic properties have been widely reported, the molecular mechanisms by which MeHg enters the cells and exerts toxicity are not yet completely understood. Taking into account that MeHg is found mostly bound to sulfhydryl-containing molecules such as cysteine in the environment and based on the fact that the MeHg-cysteine complex (MeHg-S-Cys) can be transported via the L-type neutral amino acid carrier transport (LAT) system, the potential beneficial effects of L-methionine (L-Met, a well known LAT substrate) against MeHg (administrated as MeHg-S-Cys)-induced neurotoxicity in mice were investigated. Mice were exposed to MeHg (daily subcutaneous injections of MeHg-S-Cys, 10 mg Hg/kg) and/or L-Met (daily intraperitoneal injections, 250 mg/kg) for 10 consecutive days. After treatments, the measured hallmarks of toxicity were mostly based on behavioral parameters related to motor performance, as well as biochemical parameters related to the cerebellar antioxidant glutathione (GSH) system. MeHg significantly decreased motor activity (open-field test) and impaired motor performance (rota-rod task) compared with controls, as well as producing disturbances in the cerebellar antioxidant GSH system. Interestingly, L-Met administration did not protect against MeHg-induced behavioral and cerebellar changes, but rather increased motor impairments in animals exposed to MeHg. In agreement with this observation, cerebellar levels of mercury (Hg) were higher in animals exposed to MeHg plus L-Met compared to those only exposed to MeHg. However, this event was not observed in kidney and liver. These results are the first to demonstrate that L-Met enhances cerebellar deposition of Hg in mice exposed to MeHg and that this higher deposition may be responsible for the greater motor impairment observed in mice simultaneously exposed to MeHg and L-Met.

Aluminum in erythropoietin formulations: lyophilized versus liquid forms.

BACKGROUND: Erythropoietin (EPO) formulations may comprise aluminum (Al) as a contaminant. Due to the toxicity of Al in chronic kidney disease patients, possible sources of Al were investigated. Since EPO formulations are stored in container-closure systems made of glass and rubber, and both contain Al, formulation ingredients may enable its leaching into the solution during shelf-life. METHODS: Individual solutions of formulation ingredients were stored in new glass vials and in contact with the rubber stopper and kept at 4 ± 2 °C. For 12 months, aliquots of each solution were collected for analysis. Fifteen commercial samples of EPO were analyzed for their Al content. Aluminum was determined by atomic absorption spectrometry. RESULTS: Glass and rubber are sources of Al for EPO formulations. Storage assay showed that citrate and phosphate (used as buffers) extracted high amounts of Al from the container/closure parts. The most important difference, however, was found when comparing liquid and lyophilized samples. While in liquid forms the Al level reached 943 µg/L, in lyophilized forms the level did not exceed 20 µg/L. The container system was also confirmed as a source of Al in reconstituted lyophilized samples. Al in reconstituted samples stored in their own vials increased 19-fold in 12 months. Lyophilized powders stored for 2 years in glass vials contained less Al than in 1 month after dissolution. CONCLUSION: The difference in the Al measured in liquid forms of EPO and in lyophilized powders suggests that the latter would be the best pharmaceutical form for CKD patients.

Interference of Parenteral Nutrition Components in Silicon-Mediated Protection Against Aluminum Bioaccumulation.

Aluminum and silicon are contaminants found in formulations used to prepare parenteral nutrition. Both elements are leached from glass containers, mainly during the heating cycle for sterilization. Insoluble and biologically inactive species of hydroxyaluminosilicates have been shown to form in solutions containing Al and Si. Therefore, this interaction may play an important role in protecting the body against Al toxicity. In this study, the bioavailability of Al in the presence of Si, calcium gluconate (Gluc.), and potassium phosphate (Phosf.) was investigated in rats. The rats were divided into 10 groups of 5 animals each: control, Al, Si, Al + Si, Gluc, Gluc + Al, Gluc + Al + Si, Phosf, Phosf + Al, and Phosf + Al + Si. The doses, consisting of 0.5 mg/kg/day Al and 2 mg/kg/day Si in the presence or absence of Gluc. or Phosf., were intraperitoneally administered for 3 months. Tissues were analyzed for Al and Si content. Al accumulated in the liver, kidneys, and bones, and the simultaneous administration of Si decreased Al accumulation in these tissues. The presence of Si reduced the amount of Al present by 72% in the liver, by 45% in the kidneys, and by 16% in bone. This effect was lees pronounced in the presence of parenteral nutrition compounds though. Si tissue accumulation was also observed, mainly when administered together with phosphate. These results suggest that Si may act as a protector against Al toxicity, by either reducing Al absorption or increasing its excretion, probably through hydroxyaluminosilicates formation. The presence of calcium gluconate and potassium phosphate decreases or inhibits this effect.

Modulation of methylmercury uptake by methionine: prevention of mitochondrial dysfunction in rat liver slices by a mimicry mechanism.

Methylmercury (MeHg) is an ubiquitous environmental pollutant which is transported into the mammalian cells when present as the methylmercury-cysteine conjugate (MeHg-Cys). With special emphasis on hepatic cells, due to their particular propensity to accumulate an appreciable amount of Hg after exposure to MeHg, this study was performed to evaluate the effects of methionine (Met) on Hg uptake, reactive species (RS) formation, oxygen consumption and mitochondrial function/cellular viability in both liver slices and mitochondria isolated from these slices, after exposure to MeHg or the MeHg-Cys complex. The liver slices were pre-treated with Met (250 µM) 15 min before being exposed to MeHg (25 µM) or MeHg-Cys (25 µM each) for 30 min at 37 °C. The treatment with MeHg caused a significant increase in the Hg concentration in both liver slices and mitochondria isolated from liver slices. Moreover, the Hg uptake was higher in the group exposed to the MeHg-Cys complex. In the DCF (dichlorofluorescein) assay, the exposure to MeHg and MeHg-Cys produced a significant increase in DFC reactive species (DFC-RS) formation only in the mitochondria isolated from liver slices. As observed with Hg uptake, DFC-RS levels were significantly higher in the mitochondria treated with the MeHg-Cys complex compared to MeHg alone. MeHg exposure also caused a marked decrease in the oxygen consumption of liver slices when compared to the control group, and this effect was more pronounced in the liver slices treated with the MeHg-Cys complex. Similarly, the loss of mitochondrial activity/cell viability was greater in liver slices exposed to the MeHg-Cys complex when compared to slices treated only with MeHg. In all studied parameters, Met pre-treatment was effective in preventing the MeHg- and/or MeHg-Cys-induced toxicity in both liver slices and mitochondria. Part of the protection afforded by Met against MeHg may be related to a direct interaction with MeHg or to the competition of Met with the complex formed between MeHg and endogenous cysteine. In summary, our results show that Met pre-treatment produces pronounced protection against the toxic effects induced by MeHg and/or the MeHg-Cys complex on mitochondrial function and cell viability. Consequently, this amino acid offers considerable promise as a potential agent for treating acute MeHg exposure.

Simultaneous determination of Ba, Co, Fe, and Ni in nuts by high-resolution continuum source atomic absorption spectrometry after extraction induced by solid-oil-water emulsion breaking.

This paper describes the simultaneous determination of Ba, Co, Fe, and Ni in nuts by high-resolution continuum source atomic absorption spectrometry after extraction induced by solid-oil-water emulsion breaking. Extraction yields ranged from 94.9 for Ba to 109.8% for Fe. Simultaneous measurements were carried out at secondary lines of Ba, Co, Fe, and Ni. The limits of detection and quantification were, respectively, 3.819 and 1.146 mg L-1 for Ba, 2.274 and 7.421 µg L-1 for Co, 0.095 and 0.285 mg L-1 for Fe, and 2.138 and 6.614 µg L-1 for Ni. The precision ranged from 3.1 to 4.2%, 1.5 to 8.0%, 1.6 to 6.6%, and 0.4 to 6.1% for Ba, Co, Fe and Ni, respectively. The method accuracy was assessed by recovery tests and comparison of the results obtained by the proposed extraction method with those obtained after acid digestion. Recoveries ranged from 93.5 for Ni to 104.5% for Co.

Extraction induced by emulsion breaking to assay Cr, Cu and Mn in asphalt samples by high-resolution continuum source atomic absorption spectrometry and its comparison with other sample preparation methods.

This paper reports the development of a method based on the extraction induced by emulsion breaking (EIEB) for the determination of Cr, Cu and Mn in asphalt by high-resolution continuum source atomic absorption spectrometry. In optimized conditions, the extraction efficiency ranged from 88.6 for Cu to 104.5% for Mn. Measurements were carried out at the primary lines of the three analytes. The limits of detection were 0.02 µg g-1 for Cr, 0.01 µg g-1 for Cu and 7.11 ng g-1 for Mn. The precision, expressed as the relative standard deviation, ranged from 1.0 for Cu to 9.1% for Cr. The performance of the proposed method was compared to previously reported sample preparation procedures, including microwave-assisted acid digestion (MW-AD), ultrasound-assisted acid extraction (USE), emulsification (E), and direct dilution in organic solvent (DD). The parameters evaluated were matrix effects, limits of detection and quantification, characteristic mass, precision, accuracy, sample stability and applicability for routine analysis. The methods most suitable for Cu determination were EIEB, MW-AD, USE and E. For Cr and Mn, the best results were obtained by EIEB, MW-AD and DD procedures.

Aluminum loading in preterm neonates revisited.

Preterm neonates receiving parenteral nutrition are at risk of aluminum (Al) overload because of the presence of Al as a contaminant in parenteral formulations. Despite US Food and Drug Administration regulation, commercial products continue to present Al contamination. To reassess Al exposure in the premature neonatal population, the present study evaluated the Al balance (intake vs urinary excretion) in a group of preterm neonates during the period in which they stayed in the intensive care unit (NICU) under total parenteral nutrition. For the 10 patients selected, daily infusion solutions (nutrition and medication) were collected and the level of Al contamination was measured. From the urine collected daily, an aliquot was taken for Al determination. Blood was also collected for Al determination on the first and last day in the NICU. The measurements were carried out by atomic absorption spectrometry. The difference between Al administered and excreted revealed that 56.2% +/- 22.7% of the Al intake was not eliminated. The mean serum Al levels from the first to the last day decreased from 41.2 +/- 23.3 to 23.5 +/- 11.2 microg/L. The resulting mean Al daily intake of the 10 patients was 15.2 +/- 8.0 microg x kg(-1) x day(-1). Because Al intake was higher than that excreted and Al in serum decreased to practically half during the period in the NICU (+/-7.3 days), some amount of Al deposition occurred. Moreover, premature neonates were receiving, on average, 3 times the amount of 5 microg x kg(-1) x day(-1), considered by the Food and Drug Administration as a safe limit.

Presence of other rare earth metals in gadolinium-based contrast agents.

Gadolinium-based contrast agents (GBCA) are widely used to enhance tissue contrast during magnetic resonance imaging (MRI) procedures. However, free Gadolinium (Gd) is undesirable as a drug substance, due to its high toxicity. Consequently, a coordinating ligand is required to keep it in solution and to increase tolerance. In order to achieve an adequate performance, GBCA must be administered in relatively large amounts. Chelate amounts are around 13-20 g and for Gd alone, this may amount to 3.3 g. Taking into account the route of administration, impurities in GBCA may be significant. Gadolinium occurs in nature along with 16 other elements known collectively as rare earth metals (RE), which are found throughout the earth's crust in minerals such as monazite. Gadolinium oxide corresponds to 0.7-4.0% of the RE present in minerals, and the sum concentration of RE in minerals is around 4%. Rare earth metals are difficult to separate, as the chemical and physical properties of one RE are significantly similar to those of others. In this study, the presence of other RE in GBCA formulations was investigated. Different lots of Magnevist®, Viewgam®, OptiMARK®, Omniscan®, Dotarem®, and Gadovist® were analyzed. Inductively-coupled plasma mass spectrometry and atomic absorption spectrometry were used for RE determination. Procedure optimization included sample decomposition and method validation for element determination. The results showed that Sc, Y, La, Ce, Pr, Nd, Eu, Tb, Tm, Dy, Ho, and Er were present in the 22 samples analyzed. Terbium, Thulium, Europium, and Lanthanum were, on average, found in the highest amounts, which were 0.42 mg/L, 0.17 mg/L, 0.17 mg/L, and 0.16 mg/L, respectively. These results could be attributed to the similarity among Europium, Gadolinium, and Terbium. They are in sequence in the periodic table and therefore present very close ionic radii, restricting their separation. Considering the sum of all RE, Viewgam® was the most contaminated formulation (mean of 2.16 mg/L) and Magnevist® the least (mean of 0.64 mg/L). Although the RE are chemically similar, the other RE do not perform as Gd as a contrast agent; therefore, their presence in formulations may be a matter of concern.

Role of medication in the level of aluminium in the blood of chronic haemodialysis patients.

BACKGROUND: Although dialysis facilities provide high-quality water, abnormal aluminium levels among patients on haemodialysis have still been reported. Since patients with chronic kidney disease are often on multiple medications, medicines may be an extra source of aluminium for them. The degree to which ingesting contaminated medication influenced the level of aluminium in the patients' blood was investigated. METHODS: All medications consumed by a group of patients on regular dialysis treatment were analysed and the total aluminium ingested by each patient was calculated. At the same time, the patients' blood was collected and aluminium was measured. The analyses were carried out by atomic absorption spectrometry. RESULTS: For all drugs consumed, the amount of aluminium ingested versus the blood aluminium level presented no correlation. Since a high level of contamination was presented by injectable iron, insulin and erythropoietin (EPO), another group of patients that received a reduced amount of oral medication was selected. Among them, eight did not receive any injectable drug, five received only EPO and seven injectable iron, EPO and insulin. With these restricted groups, it was possible to show that the injectable administration of contaminated medication increased the Al level in the patients' blood, mainly in relation to iron formulations. CONCLUSION: Among the medications investigated, the injectables are the most significant source of aluminium for patients with renal insufficiency. This extra aluminium intake is reflected in higher aluminium levels in the patients' blood.

Performance of polymeric materials for solid phase extraction prior to chromatographic analysis.

Synthetic polymeric materials such as polyethylene and polyurethane (PU) were compared to conventional adsorbents for solid phase extraction for cleaning up biological samples. Efficiency in eliminating proteins and other components usually present in biological samples, such as serum, urine, and tissues extracts, was evaluated. The assays consisted of measuring the remaining protein content in serum and tissue homogenates (liver) and collecting the spectra in the UV region for urine samples. Since the analysis of many endogenous and exogenous species in these matrices usually involves chromatographic separation, the efficiency of the clean-up procedures was also evaluated by injecting cleaned samples into a C-18 chromatographic column with UV detection. Among the investigated polymers, polytetrafluorethylene, high density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE) presented the best performance in retaining serum proteins. Proteic components of the liver homogenate were completely retained on polyurethane and polybutadiene (PB). Urine samples were cleaned by crossing columns of polytetrafluorethylene, ultra-high molecular weight polyethylene, high density polyethylene, polyurethane, and polyethylene co-butyl acrylate co-anhydride maleic (PEco), since the spectra collected after column percolation presented no peaks in the region between 190 and 390 nm. SPE cartridges showed different behavior, but along the lines of their usual performance; neither serum proteins nor urine components were retained on the phases and the liver components, though partially retained, were not desorbed with either water or methanol washes, with the exception of SAX. Chromatograms of samples cleaned with high density polyethylene showed that polymeric materials can be satisfactorily used as adsorbent for biological matrix components.

High-resolution continuum source graphite furnace atomic absorption spectrometry for screening elemental impurities in drugs to adhere to the new international guidelines.

New guidelines for the limits of elemental impurities in drug products were introduced by the International Council for Harmonization in 2014. While the guidelines define a limit for each element, the complete quantification of the 24 elements included is, in fact, unnecessary. An accurate "pass/fail" test to determine whether the threshold was exceeded or not could be valuable in this context. In this study, a screening procedure using the features of high-resolution continuum source graphite furnace atomic absorption spectrometry for the evaluation of 12 elements in three different drugs was developed. The three-dimensional absorbance spectrum including time and wavelength in the vicinity of the main line of the element allows for a pass/fail decision related to the presence or absence of the element in the sample. Additionally, the bi-dimensional absorbance-wavelength spectrum defines the elements captured in the window when additional peaks are seen in the spectrum. The analysis of the selected drugs included sample digestion, the definition of pyrolysis and atomization temperatures, determination of the limit of detection and other validation parameters for each element. The evaluation of the spectra, both three- and bi-dimensional, revealed that only three elements, Cr, Ni, and Cu, were present in the samples in amounts above the LOD and therefore "fail" in the test. Nevertheless, they were quantified, and the analysis revealed that their levels were below the permitted daily exposure, which are at least 6 times higher than the LOD of the selected elements. Operating in a routine mode, the proposed method is a good option for the evaluation of elemental impurities in drug active ingredients or drug final products.

Extraction/Leaching of Metal-Containing Additives from Polyvinyl Chloride, Ethyl Vinyl Acetate, and Polypropylene Bags and Infusion Sets into Infusion Solutions.

Flexible medical devices are primarily made of plasticized polyvinyl chloride (PVC). In recent times, to avoid undesired migration of the PVC plasticizers, ethyl vinyl acetate (EVA) and polypropylene (PP) has replaced PVC. Nevertheless, other additives are necessary to generate useful polymeric materials. Metallic species present in such additives can also leach out into the infusion solutions. The migration of barium (Ba), cadmium (Cd), lead (Pb), tin (Sn), and zinc (Zn) from devices made from PVC, EVA, and PP was evaluated. Bags and infusion sets were decomposed and their metallic contents analyzed. Glucose, NaCl, and Tween 80 were assessed as extraction media. These solutions were stored in PVC, EVA, and PP bags, heat-sterilized, and stored for 8 months at room temperature. Aliquots were taken before and after sterilization and then once per month to determine the contents of the metals. Commercial glucose and NaCl infusions were analyzed by taking aliquots of the solutions from the bags and from the administration set after their administration to patients. The three polymers contained the five metals. Ba was found in the highest concentration in all samples, with a mean of 8.0 mg/kg in PVC, 4.2 mg/kg in EVA, and 4.7 mg/kg in PP samples. Despite this, the only element that migrated into the glucose, NaCl, and Tween 80 solutions was Zn. The same result was found for the commercial glucose and NaCl infusions. Moreover, the Zn concentration in the administration sets was on average 52% higher than that found in the bags.LAY ABSTRACT: Flexible medical devices for infusions and artificial nutrition are made of plastics, such as polyvinyl chloride (PVC), ethyl vinyl acetate (EVA), and polypropylene (PP). These polymers contain additives necessary to generate useful materials. Metallic species present in these additives can leach out into the infusion solutions and come into contact with patients. To assess the risk of patient exposure to these metals, we evaluated the migration behavior of barium (Ba), cadmium (Cd), lead (Pb), tin (Sn), and zinc (Zn) from devices made from PVC, EVA, and PP. Bags and infusion sets were analyzed. Glucose, NaCl, and Tween 80 were investigated as extraction media. The three polymers contained the five metals. Ba was found in the highest concentration in all samples. Despite this, the only element that migrated into the glucose, NaCl, and Tween 80 solutions was Zn.

Simultaneous determination of iron and nickel as contaminants in multimineral and multivitamin supplements by solid sampling HR-CS GF AAS.

A methodology to assay simultaneously iron and nickel present as contaminants in multimineral and multivitamin supplements was investigated. High-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis were used. Measurements were done with the secondary lines of Fe (352.604 nm) and Ni (352.454 nm) to avoid spectral interferences. The best temperatures for pyrolysis and atomization for Fe and Ni were 1000 and 2700 °C, respectively. Chemical modifiers were not necessary and no matrix effects were observed. Aqueous standard solutions were used for calibration. The limit of detection was 0.517 µg g-1 for Fe and 0.011 µg g-1 for Ni. The precision ranged from 4.3% to 17% and 4.4-20% for Fe and Ni, respectively. The method accuracy was confirmed by comparing statistically the results obtained by solid sampling with those of sample acid digestion. The proposed methodology was successfully applied to determine both metals in different multimineral and multivitamin supplements.

Tissue digestion for aluminum determination in experimental animal studies.

Four different procedures for the determination of aluminum in tissues by atomic absorption spectrometry (AAS) were investigated. They consisted of conventional acid digestion carried out before and after sample drying, associated or not with fat extraction. Drying was carried out in a conventional oven at 65 degrees C for 24 h. For fat extraction, different solvents and solvent mixtures were investigated considering both extraction yield and sample adequacy for further AAS measurement. Acid digestion was carried out with pure HNO3 or with its mixture with HClO4. After digestion, aluminum was measured by graphite furnace atomic absorption spectrometry. Tissues were collected from Al-exposed and nonexposed mice. The results indicated that drying the sample prior to digestion is advantageous as the amount of acid necessary can be significantly reduced. This procedure does not contribute to increase the aluminum level in the samples providing that careful measures to avoid contamination are taken, as the same procedures carried out without taking any precautions to avoid contamination produced imprecise results. Finally, aluminum was not found in the fatty fraction of any sample, even in exposed mice, demonstrating that aluminum does not accumulate in this part of the tissues.

Cyclooxygenase-2/PGE2 pathway facilitates pentylenetetrazol-induced seizures.

Cyclooxygenases (COXs) are rate-limiting enzymes in the metabolic pathways in which arachidonic acid is converted to prostaglandins. COX-2 is the isoform induced at injury/inflammation sites and expressed constitutively in a few tissues, such as the central nervous system, and plays a role in neurodegenerative diseases associated with increased excitatory activity. However, the role of COX-2 and its main product, prostaglandin E(2) (PGE(2)), in the convulsive states is not fully established. In this study we showed that the selective COX-2 inhibitor, celecoxib (at the dose of 2mg/kg, but not at the doses of 0.2 or 20mg/kg, p.o.), protects against the seizures induced by pentylenetetrazol (PTZ, 60 mg/kg, i.p.). The role of PGE(2) in the convulsions induced by PTZ was further investigated by administering anti-PGE(2) antibodies (4 microg/2 microl, i.c.v.), and assessing electroencephalographic changes induced by PTZ (PTZ, 60 mg/kg, i.p.). Anti-PGE(2) antibodies attenuated PTZ-induced seizures in rats. In addition, combining PGE(2) (100 ng/2 microl, i.c.v.) with a subconvulsant dose of PTZ (20mg/kg, i.p.) caused seizures, further supporting a role for this prostaglandin in the convulsions induced by PTZ. Finally, we showed that the anticonvulsant action of celecoxib (2mg/kg, p.o.) was reversed by the intracerebroventricular administration of PGE(2) (10 ng/2 microl, i.c.v.). These data constitute strong converging pharmacological evidence supporting a facilitatory role for the COX-2/PGE(2) pathway in the seizures induced by PTZ. However, whether selective COX-2 inhibitors are safer anti-inflammatory drugs for epileptic patients than nonspecific inhibitors remains to be determined.

Silicate release from glass for pharmaceutical preparations.

Glass is made of polymeric silica and other minor components, which are necessary for turning the silica into a material more easily moldable and resistant to temperature changes. Glass containers for pharmaceutical usage are classified according to their resistance to a chemical attack, a test carried out in the presence of water and heat. The test is designed to show the released alkalinity, a variable dependent on the amount of sodium oxide, one of the minor components added to the glass mass. In this work, the release of silica from glass by action of constituents from pharmaceutical formulations was investigated. The study included products used in large volumes and usually stored in glass containers. Solutions of amino acids, electrolytes, glucose, oligoelements and others such as heparin and sodium bicarbonate were individually stored in glass containers and heated at 121 degrees C for 30min, as in the water attack test. The test was also carried out only with water, where the pH varied from 2 to 12. The released silicate was measured either by photometry or atomic absorption spectrometry, depending on the nature of the sample. The results showed that silicate is released during the heating cycle even if the contact is with pure water only. The pH exerts a considerable influence on the release, being that the higher the pH, the higher the silica dissolved. An elevated pH, however, is not the only factor responsible for silica dissolution. While in the solutions of NaCl, KCl, Mg Cl2 and ZnSO4 and in most of the amino acids, the concentration of silicate was as high as in pure water (0.1-1.0mg Si/L). In the solutions of sodium acetate, bicarbonate and gluconate, its concentration was much higher, over 30mg Si/L. These results were confirmed by the analysis of commercial products, where in solutions of amino acids the level of silicate ranged from 0.14 to 0.19mg Si/L. On the other hand, calcium gluconate, sodium bicarbonate and potassium phosphate presented silicate levels from 1 to 4mg/L. Although silica is not considered a toxic substance for humans, it is necessary to be aware of its presence in solutions for parenteral nutrition due to the direct introduction into the bloodstream and the large volume usually administrated, even to pre-term infants.

Human erythrocyte delta-aminolevulinate dehydratase activity and oxidative stress in hemodialysis patients.

BACKGROUND: Oxidative stress is a complicating factor in chronic renal failure, especially in hemodialysis (HD) patients. Also, aluminum intoxication may occur during hemodialysis treatment. Aluminum has been shown to inhibit the sulfhydryl-containing enzyme delta-aminolevulinate dehydratase (ALA-D). Thus, the involvement of -SH oxidation in ALA-D inhibition and its relationship with serum Al levels and lipid peroxidation in HD patients were evaluated. METHODS: Blood ALA-D activity, plasma thiobarbituric acid reactive substances (TBARS), and serum aluminum levels were measured in HD patients (n=37) and healthy controls (n=20). RESULTS: TBARS and Al levels were higher in HD patients than in controls (p<0.01), while ALA-D activity was lower (p<0.05). The sulfhydryl-reducing agent dithiothreitol (DTT) reactivated ALA-D of HD patients, but activity was still lower than that of controls. ALA-D activity was negatively correlated with TBARS (r=-0.63, p<0.01) and aluminum levels (r=-0.31, p<0.05). CONCLUSIONS: Reduced ALA-D activity in HD patients was found to be related to the oxidation of -SH groups essential for enzyme activity. Our results suggest that increased oxidative stress may have contributed to enzyme inhibition in HD patients.