Pharmacokinetic study of enrofloxacin in Nile tilapia (Oreochromis niloticus) after a single oral administration in medicated feed.

The objective of this study was to evaluate the disposition kinetics of enrofloxacin (ENR) in the plasma and its distribution in the muscle tissue of Nile tilapia (Oreochromis niloticus) after a single oral dose of 10 mg/kg body weight via medicated feed. The fish were kept at a temperature between 28 and 30 °C. The collection period was between 30 min and 120 h after administration of the drug. The samples were analyzed by high-performance liquid chromatography with a fluorescence detector (HPLC-FLD). The ENR was slowly absorbed and eliminated from the plasma (Cmax = 1.24 ± 0.37 µg/mL; Tmax = 8 h; T1/2Ke  = 19.36 h). ENR was efficiently distributed in the muscle tissue and reached maximum values (2.17 ± 0.74 µg/g) after 8 h. Its metabolite, ciprofloxacin (CIP), was detected and quantified in the plasma (0.004 ± 0.005 µg/mL) and muscle (0.01 ± 0.011 µg/g) for up to 48 h. After oral administration, the mean concentration of ENR in the plasma was well above the minimum inhibitory concentrations (MIC50 ) for most bacteria already isolated from fish except for Streptococcus spp. This way the dose used in this study allowed for concentrations in the blood to treat the diseases of tilapia.

Depletion study and estimation of the withdrawal period for enrofloxacin in pacu (Piaractus mesopotamicus).

Defining the pharmacokinetic parameters and depletion intervals for antimicrobials used in fish will help in the development of important guidelines for future regulations by Brazilian agencies on the use of these substances in fish farming. This paper presents a depletion study for enrofloxacin (ENR) and its main metabolite, ciprofloxacin (CIP), in pacu (Piaractus mesopotamicus) fillets. The depletion study was carried out under monitored environmental conditions, with the temperature controlled at 27 °C to mimic the fish farming conditions in Brazil. ENR was administered orally via medicated feed for 10 consecutive days at daily dosages of 10 mg/kg body weight (b.w.). The fish were slaughtered at 6, 12, and 24 h and 2, 3, 5, 8, 12, 17, and 24 days after the medication period. Considering a maximum residue limit of 100 µg/kg for the sum of the ENR and CIP residues in the fillet, the results obtained in the depletion study allowed the estimation of a half-life for ENR of 2.75 days and a withdrawal period of 23 days. The results obtained in this study are important for the farming of pacu in tropical regions.

Depletion study and estimation of the withdrawal period for oxytetracycline in tilapia cultured in Brazil.

Defining pharmacokinetic parameters and depletion intervals for antimicrobials used in fish represents important guidelines for future regulation by Brazilian agencies of the use of these substances in fish farming. This article presents a depletion study for oxytetracycline (OTC) in tilapias (Orechromis niloticus) farmed under tropical conditions during the winter season. High performance liquid chromatography, with fluorescence detection for the quantitation of OTC in tilapia fillets and medicated feed, was developed and validated. The depletion study with fish was carried out under monitored environmental conditions. OTC was administered in the feed for five consecutive days at daily dosages of 80 mg/kg body weight. Groups of ten fish were slaughtered at 1, 2, 3, 4, 5, 8, 10, 15, 20, and 25 days after medication. After the 8th day posttreatment, OTC concentrations in the tilapia fillets were below the limit of quantitation (13 ng/g) of the method. Linear regression of the mathematical model of data analysis presented a coefficient of 0.9962. The elimination half-life for OTC in tilapia fillet and the withdrawal period were 1.65 and 6 days, respectively, considering a percentile of 99% with 95% of confidence and a maximum residue limit of 100 ng/g. Even though the study was carried out in the winter under practical conditions where water temperature varied, the results obtained are similar to others from studies conducted under controlled temperature.

Comparative study of maize cultivars 30 days after pollination (30 DAP): carbohydrates and protein.

A comparative study of the carbohydrates and protein of five maize cultivars at 30 days after pollination (DAP) showed a higher protein content for the Supersweet variety, and better protein quality for the Maya Opaque-2, Nutrimaiz, the Supersweet, and the Hybrid L90 x L41, when compared to the Maya Normal. The lipid content also proved to be higher in the four genetically-modified cultivars in relation to the Maya Normal. In contrast, the Maya Normal and the Opaque-2 were higher in starch content, lower in total and reducing soluble sugars, and exhibited only very small amounts (approximately equal to 1%) of phytoglycogen, a water-soluble polysaccharide. Nutrimaiz and the Hybrid L90 x L41 had approximately half the starch of the Maya Normal cultivar, but presented an appreciable content of phytoglycogen (23-26%), which is typical for sugary maize mutants, and a higher amount of soluble sugars, mainly sucrose, in relation to Maya Normal. The Supersweet had about half the starch content and a very high (approximately equal to 24%) amount of soluble sugars, mainly sucrose, in relation to the Maya Normal cultivar. The Supersweet also had a negligible amount of phytoglycogen. Nutrimaiz and the Hybrid L90 x L41 showed a much higher proportion of grain in the ears and, as a consequence, a higher yield of dry solids at 30 DAP, when compared with the Maya Normal cultivar.

Comparative study of maize cultivars 30 days after pollination (30 DAP): characterization of starch.

Characterization of starch was comparatively studied in five maize cultivars, i.e., Maya Normal, Nutrimaiz, two hybrids (L90 x L78, L90 x L41) and Supersweet (SRR "Duro"), 30 days after pollination (30 DAP). Amylose content was found to be higher in the Maya Normal starch (31.3%) and lower (23 to 27%) in the genetically-modified cultivars. The absolute density of the isolated starches did not show significant differences among cultivars. Solubility and swelling studies suggested the presence of more homogenous forces maintaining the granular matrix on the starch from Maya Normal in relation to the other maize cultivars. The starch from the genetically-modified cultivars had a reduced solubility in dimethylsulfoxide and lower values for the gelatinization temperature range, in comparison to the Maya Normal. Information from the Brabender amylogram indicated greater resistance of the gelatinized maize starches to granule breakdown by mechanical stirring, in the new genotypes, resembling those starches modified by cross-linking.

Determination of quinolone residues in tilapias (Orechromis niloticus) by HPLC-FLD and LC-MS/MS QToF.

A method for the simultaneous determination of flumequine, oxolinic acid, sarafloxacin, danofloxacin, enrofloxacin, and ciprofloxacin in tilapia (Orechromis niloticus) fillet, using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) is presented. The quinolones were extracted from the food matrix with a solution of 10% trichloroacetic acid and methanol (80:20 v/v). Clean-up of the extract was performed using polymeric solid-phase extraction cartridges. Identification of the quinolones was confirmed by liquid chromatography-tandem mass spectrometry. The HPLC-FLD method was validated in-house and the following analytical parameters were obtained: linearity higher than 0.99 for all the quinolones; intra- and interassay precisions were lower than 3.5% and 10.9%, respectively; and recoveries ranged from 73% to 110%. The limit of quantification was below the maximum residue limit established by the Joint Expert Committee on Food Additives (JECFA), which indicates that the method is appropriate for the determination of quinolones in fish fillet.

Occurrence of ivermectin in bovine milk from the Brazilian retail market.

High-performance liquid chromatography (HPLC) with fluorescence detection was used for the quantification of ivermectin residues in bovine milk intended for human consumption. After liquid-liquid extraction of ivermectin and purification of the extract, the compound was derivatized with 1-methylimidazol in N,N-dimethyl formamide to form a fluorescent derivative, which was separated by HPLC, using reversed-phase C18, with methanol : water (96 : 4 v/v) mobile phase at a flow rate 0.7 ml min-1. The excitation and emission wavelengths of the fluorescence detector were adjusted at 360 and 470 nm, respectively. The linearity of the method was in the range 10-100 ng ivermectin ml-1. Based on a sample of 5.0 ml, the limit of detection and the limit of quantification for ivermectin in milk were 0.6 and 2 ng ml-1, respectively. The recovery rate varied from 76.4 to 87.2%, with an average of 77.9 +/- 3.2%, at four fortification levels. The inter-day precision of the method was 13% (n = 5). Of 168 samples analysed, 17.8% contained ivermectin above the limit of quantification. Nevertheless, none of the samples contained ivermectin above the maximum residue limit (10 ng ml-1) established by the Brazilian Ministry of Agriculture.

Enrofloxacin assay validation and pharmacokinetics following a single oral dose in chickens.

The pharmacokinetics of enrofloxacin (ENRO), a fluoroquinolone antimicrobial agent, was studied in male broiler chickens (Cobb) after single oral administration of 10 mg of ENRO/kg b.w. A high-performance liquid chromatography-photodiode array detector (DAD) (HPLC-DAD) method was developed and validated and used for quantitation of ENRO and its major metabolite ciprofloxacin in plasma. The HPLC analyses were carried out using a cationic-octadecyl mixed column and 0.05 mol/L phosphate buffer (pH 2.5)/acetonitrile as mobile phase. The sample preparation of plasma consisted of the precipitation of proteins followed by solid phase extraction on cationic-octadecyl mixed cartridges. The method was validated considering linear range, linearity, selectivity, sensitivity, limit of detection (LOD), limit of quantitation (LOQ), intra- and inter-day precisions and accuracy. The LOD and LOQ for both fluoroquinolones were 60 and 200 ng/mL for plasma. The plasma concentration vs. time graph was characteristic of a two-compartment open model. The maximal plasma concentration of 1.5 +/- 0.2 mg/mL was achieved at 9 +/- 2 h. The elimination half-life and the mean residence time of ENRO were 1.5 +/- 0.2 and 15.64 h, respectively. The area under the concentration-time curve was calculated as 35 +/- 4 mgxh/mL.

Plasticizers in Brazilian food-packaging materials acquired on the retail market.

Packaging materials intended for direct food contact were acquired on the Brazilian retail market and analysed for their plasticizer content. Analyses were carried out by gas chromatography with flame ionization detection. Di-2-ethyl-hexyl adipate (DEHA), di-2-ethyl-hexyl phthalate (DEHP) and di-iso-decyl phthalate (DIDP) plasticizers were identified in films and closure seals in concentrations ranging from 12 to 19% (w/w), 15 to 44% (w/w) and 10 to 11% (w/w), respectively. Brazilian regulations state that for use with foods with a fat content above 5%, the levels of DEHP and DIDP in the plastic material should be no greater than 3%. The results obtained demonstrate a lack of conformity. It would be advisable to include information on the labels of packaging materials about their restrictions of use in order to advise manufacturers and consumers about their proper usage.

Evaluation of the nitrate content in leaf vegetables produced through different agricultural systems.

The nitrate content of leafy vegetables (watercress, lettuce and arugula) produced by different agricultural systems (conventional, organic and hydroponic) was determined. The daily nitrate intake from the consumption of these crop species by the average Brazilian consumer was also estimated. Sampling was carried out between June 2001 to February 2003 in Campinas, São Paulo State, Brazil. Nitrate was extracted from the samples using the procedure recommended by the AOAC. Flow injection analysis with spectrophotometric detection at 460 nm was used for nitrate determination through the ternary complex FeSCNNO+. For lettuce and arugula, the average nitrate content varied (p < 0.05) between the three agricultural systems with the nitrate level in the crops produced by the organic system being lower than in the conventional system that, in turn, was lower than in the hydroponic system. For watercress, no difference (p < 0.05) was found between the organic and hydroponic samples, both having higher nitrate contents (p < 0.05) than conventionally cultivated samples. The nitrate content for each crop species varied among producers, between different parts of the plant and in relation to the season. The estimated daily nitrate intake, calculated from the consumption of the crops produced by the hydroponic system, represented 29% of the acceptable daily intake established for this ion.

Polarographic determination of nitrate in vegetables.

A polarographic method for the determination of nitrate in vegetables is presented. The method is based on the reduction of nitrate to nitric oxide which reacts in solution with colbalt (II) and thiocyanate ions forming an electroactive complex that is reduced at the dropping mercury electrode at -0.5 V (vs. SCE). The nitric oxide is generated outside the polarographic cell by addition of ferrous ammonium sulfate and ammonium molybdate in hydrochloric acid to the previously triturated vegetable matrices. The calibration graph was linear in the range of 2-12x10(-6) mol nitrate. The recovery of nitrate in vegetable matrices (broccoli, kale, lettuce, radish, red beet, spinach, turnip and watercress) varied from 85.4 to 107.4 % and the nitrate content, expressed as sodium nitrate, varied from 751 to 10 806 mg kg(-1) of fresh vegetable. The relative standard deviation for the proposed method is lower than 7% and considering a sample of 5.0 g, the determination limit was 39 mg of nitrate per kg fresh vegetable weight. The precision and accuracy of the polarographic method were comparable to those of the reference spectrophotometric method (official AOAC reference method for the determination of nitrate in foodstuffs).

Determination of UV stabilizers in PET bottles by high performance-size exclusion chromatography.

A Size Exclusion Chromatography-High Performance Liquid Chromatography (SECHPLC) method to determine antioxidants and UV stabilizers in PET bottles has been developed. In only a single run a synthetic mixture of the stabilizers was separated and quantified. The detection limit obtained for BHT, Tinuvin 326, Cyasorb UV 5411, and Tinuvin P was about 0.1 microgram/g and for Irgafos 168 it was 1.0 microgram. RSD values were lower than 3%. Tinuvin P was identified and quantified in PET bottle extracts. Olive oil, soybean oil and sunflower oil showed well defined separation from Tinuvin P at the same conditions of analysis. Cyclic dimers were identified in the PET extracts.

Effect of organic synthetic food colours on mitochondrial respiration.

Eleven organic synthetic dyes, currently or formerly used as food colours in Brazil, were tested to determine their effect on mitochondrial respiration in mitochondria isolated from rat liver and kidney. The compounds tested were: Erythrosine, Ponceau 4R, Allura Red, Sunset yellow, Tartrazine, Amaranth, Brilliant Blue, Blue, Fast Red E, Orange GGN and Scarlet GN. All food colours tested inhibited mitochondrial respiration (State III respiration, uncoupled) supported either by alpha-ketoglutarate or succinate. This inhibition varied largely, e.g. from 100% to 16% for Erythrosine and Tartrazine respectively, at a concentration of 0.1 mg food colour per mitochondrial protein. Both rat liver and kidney mitochondria showed similar patterns of inhibition among the food colours tested. This effect was dose related and the concentration to give 50% inhibition was determined for some of the dyes. The xanthene dye Erythrosine, which showed the strongest effect, was selected for further investigation on mitochondria in vivo.

[Use of fiber enriched biscuit in the treatment of chronic intestinal constipation]. / Uso de biscoito rico em fibras no tratamento da constipação intestinal crônica.

Fiber rich cereal brans have been used for the therapeutic treatment of intestinal constipation. To improve acceptability and routine use, cookies were produced from fresh corn pericarp containing 23.3% of dietary cookies. The therapeutic effect of such cookies on simple intestinal constipation was evaluated. 8 individuals with chronic intestinal constipation and without other gastrointestinal diseases were selected. Each individual was given two diets, each of them during a seven day period: first, "normal diet" and, second, "normal" diet supplemented with 100 g of the cookies, i.e., with an increase of 23 g of dietary fiber per day. The cookies produced an increase in the frequency of evacuation (from 0.27 to 0.81 times/day), in fecal weight (from 38.3 to 117.4 g of feces/day), in water content of the feces (from 29.1 to 91.0 g of water/day), in the dry matter of the feces (from 9.1 to 26.4 g/day), and in the fiber content of the feces (from 1.59 to 8.52 g/day). As the addition of the cookies to the diet promoted increases in all fecal parameters studied, they could be considered an option in the treatment of intestinal constipation.

Magnesium deficiency modulates the insulin signaling pathway in liver but not muscle of rats.

Altered insulin secretion and sensitivity have been observed in Mg-deficient animals. However, the effects of Mg deficiency and supplementation on intracellular signaling events triggered by insulin are unknown. Therefore, we studied the early steps of insulin action in muscle and liver of rats fed Mg-deficient (DF-6, DF-11) or control (CO-6, CO-11) diets for 6 or 11 wk, respectively, and Mg-deficient or control diets for 6 wk, followed by Mg supplementation for 5 wk (SDF and SCO groups, respectively). There were no differences in the glucose disappearance rate (K(itt)) or insulin signaling between CO-6 and DF-6 rats. Between the two groups of rats fed for 11 wk, the DF-11 group had a significantly greater K(itt). SDF and SCO rats had K(itt) that did not differ from CO-11 rats, but that were significantly lower than in DF-11 rats. In the latter rats, insulin receptor and insulin receptor substrate-1 protein and phosphorylation levels were elevated in liver and there was a greater association between the insulin receptor substrate-1 and p85 subunit of phosphatidyl-inositol 3-kinase compared with CO-11 rats. There were no differences in the early steps of insulin action in SDF and control rats. These results suggest that the normal insulin sensitivity maintained by Mg supplementation and the increased insulin sensitivity produced by a long period of Mg deprivation may result, at least in part, from alterations in or maintenance of the early molecular steps of insulin action in hepatic tissue.

Thermal stability of polyethylene terephthalate food contact materials: formation of volatiles from retain samples and implications for recycling.

PET packaging materials have been tested for volatile content after exposure to high temperatures. Samples included laminates, bottles, and roasting bags, and were heated at 120 degrees C, 150 degrees C and 230 degrees C for 50 min, according to sample type. Volatiles released from the material were trapped on Tenax, identified by GC-MS and assessed against a 10 micrograms/kg migration threshold limit. Few volatiles were found for samples composed only of PET. Volatiles from laminates varied according to the sample structure, but the main substances identified were not related to PET, but probably came from printing inks and adhesives. It is concluded that the migration potential of PET in high temperature applications is very low and that the formation of volatiles during use is unlikely to cause any special problems in polymer recovery in recycling schemes, provided that other packaging residues are removed effectively.

Magnesium deficiency improves glucose homeostasis in the rat: studies in vivo and in isolated islets in vitro.

The serum mineral levels, glucose disappearance rate (kg), total area under the glucose (DeltaG) and insulin (DeltaI) curves, and static insulin secretion were compared among rats fed a Mg-deficient diet for 6 (DF-6) or 11 (DF-11) weeks, and rats fed a control diet for the same periods (CO-6 and CO-11 groups). No change in glucose homeostasis was observed among DF-6, CO-6 and CO-11 rats. DF-11 rats showed an elevated kg and a reduced DeltaG and DeltaI. For evaluating the effect of supplementation, rats fed a control or Mg-deficient diet for 6 weeks were then fed a Mg- supplemented diet for 5 weeks (SCO and SDF groups respectively). The serum Mg levels in SDF rats were similar to those in CO-11 and SCO rats, but higher than in the DF-11 group. SDF rats showed similar kg, DeltaG and DeltaI compared with the CO-11 and SCO groups. However, a significantly lower kg and higher DeltaG and DeltaI were observed in SDF compared with DF-11 rats. Basal and 8.3 mmol glucose/l-stimulated insulin secretion by islets from DF-11 rats were higher than by islets from CO-11 rats. These results indicate that moderate Mg depletion for a long period may increase the secretion and sensitivity to insulin, while Mg supplementation in formerly Mg-deficient rats may prevent the increase in sensitivity and secretion of insulin.

International safety assessment of pesticides: dithiocarbamate pesticides, ETU, and PTU--a review and update.

For the last 30 years the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) has carried out toxicological evaluations and safety assessments of dithiocarbamate pesticides, continuously adjusting previous appraisals in the light of new data and advances in the understanding of the principles and mechanisms of toxic action of these compounds. The historical narrative of the evaluative process is followed by an account of the present international safety assessment status of the dithiocarbamate pesticides so far examined by the JMPR. They are ferbam, mancozeb, maneb, metiram, nabam, propineb, thiram, zineb, ziram, and the associated substances, ethylenethiourea (ETU) and propylenethiourea (PTU).

Determinação de tetraciclinas em medicamentos veterinários utilizando análise por injeção em fluxo (FIA) / Determination of tetracyclines in veterinarian medicines by flow injection analysis (FIA)

Foi desenvolvido um método de análise por injeção em fluxo (FIA) com detector de fluorescência para determinação de oxitetraciclina (OTC), doxiciclina (DC) e tetraciclina (TC) em medicamentos veterinários. O sistema FIA foi otimizado com relação ao carregador (NaOH 2,5 10-3 mol L-1) e vazão (0,5 mL min-1). Os comprimentos de onda de excitação e emissão do detector foram 420 e 530 nm, respectivamente. O método foi validado mediante avaliação dos seguintes parâmetros: faixa linear (0,02 a 0,15 mg mL-1), linearidade r(OTC) 0,9975; r(DC) 0,9903; e r(TC) 0,9913; precisão intra- e inter-ensaio (RSD < 1,0 por cento e < 3,0 por cento, respectivamente), detectabilidade (120 ng), exatidão (98 a 104 por cento) e freqüência de amostragem (50 injeções h-1). Na determinação de tetraciclinas em preparações farmacêuticas, disponíveis no comércio, foi verificada variação de 90 a 104 por cento, na quantidade nominal de princípio ativo presente no medicamento