Maurício Schneider Oliveira

Differential effects of atorvastatin treatment and withdrawal on pentylenetetrazol‐induced seizures

Purpose:  Statins are selective inhibitors of 3‐hydroxyl‐3‐methyl‐glutaryl coenzyme A (HMG‐CoA) reductase, the rate‐limiting enzyme of the mevalonate pathway for cholesterol biosynthesis. Increasing evidence indicates that statins, particularly atorvastatin, are neuroprotective in several conditions, including stroke, cerebral ischemia, traumatic brain injury, and excitotoxic amino acid exposure. However, only a few studies have investigated whether statins modulate seizure activity. In the current study we investigated whether atorvastatin or simvastatin alters the seizures induced by pentylenetetrazol (PTZ), a classical convulsant.

Susceptibility of Trypanosoma evansi to propolis extract in vitro and in experimentally infected rats

Current therapy of Trypanosoma evansi infections is not effective for the vast majority of animals with relapsing parasitemia and clinical signs. Recently, attention is being focused on the antiparasitic activity of propolis. This study evaluated the susceptibility of T. evansi to propolis extract in vitro and in vivo. A dose-dependent trypanocidal activity of propolis extract was observed in vitro. All trypomastigotes were killed 1 h after incubation with 10 μg mL(-1) of the extract. In vivo, the concentrations of 100, 200, 300 and 400 mg kg(-1) administered orally for 10 consecutive days showed no curative effect, and the rats died from the disease. However, rats treated with the two highest concentrations of propolis extract showed higher longevity than the other groups. Based on these data, we concluded that T. evansi is susceptible to propolis in vitro. Despite the lack of curative efficacy observed in vivo at the concentrations tested, the propolis extract can prolong life in rats infected with the protozoan.

Prevalence and levels of deoxynivalenol and zearalenone in commercial barley and wheat grain produced in Southern Brazil: an eight-year (2008 to 2015) summary

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is one of the most important diseases of barley and wheat in Brazil. The disease causes yield losses and contaminates grain with mycotoxins produced by the fungus, mainly deoxynivalenol (DON) and zearalenone (ZEA). The objective of this study was to summarize the results of 16,487 analyses of DON and ZEA in barley and wheat commercial grain produced in Brazil from 2008 to 2015 using liquid chromatography tandem-mass spectrometry. For barley, DON and ZEA were detected in 67% and 41% of the samples, respectively, but 19% and 18% were above the maximum tolerated limits (MTL = 1250 μg/kg for DON and 100 μg/kg for ZEA). For wheat, DON and ZEA were detected in 73 and 38% with 30% and 9% of the samples above the MTL (1250 μg/kg for DON and 200 μg/kg for ZEA). The overall mean concentration of DON was 737 μg/kg in barley and 660 μg/kg in wheat. The mean yearly DON levels varied less in barley (446 μg/kg to 1114 μg/kg) compared to wheat (346 μg/kg to 1274 μg/kg). For the latter, a high peak of DON was found in 2014 when 58% of the samples were above the MTL and the toxin levels averaged 1274 μg/kg across all samples. The mean yearly concentration of ZEA was 138 and 111 μg/kg for barley and wheat, respectively, with the highest prevalence and concentration reported in 2008 and 2009, for both crops. To our knowledge, this is the most comprehensive summary of DON and ZEA contamination in barley and wheat in Brazil for almost a decade of monitoring. Continuous assessment and close inspection of highly contaminated batches are essential to ensure food safety and mitigate the risk that these mycotoxins can cause to human and animal health.

Natural occurrence of tenuazonic acid and Phoma sorghina in Brazilian sorghum grains at different maturity stages

A survey of 100 samples of sorghum grains was carried out to determine Phoma spp. and tenuazonic acid (TA) contamination using molecular tools and LC-MS/MS. Sorghum samples were obtained at the following four grain maturity stages: milk (S1), soft dough (S2), hard dough (S3), and physiological maturity (S4). The results revealed a good correlation between Phoma and TA occurrence during grain development. The samples showed Phoma contamination with frequencies ranging from 2.4% (S1) to 87.4% (S4), and the molecular identification revealed P. sorghina as the only Phoma specie isolated. Tenuazonic acid was found in sorghum grains at all maturity stages. In S2, S3 and S4, 100% of the samples showed TA contamination with levels ranging from 20 to 1234µg/kg. Low levels of TA were detected in 36% of the samples collected at S1 stage. This is the first report of tenuazonic acid in Brazilian sorghum grains.

Dois planos de amostragem para análise de fumonisinas em milho

The aim of this research was to evaluate the efficiency of two sampling plans for fumonisins (B1+B2) analysis in 11 lots of maize. For sample collection the two systems used were a manual system in whole grains, using sampling spear, and an automatic system in milled grains, using the continuous flow sampling system (CFSS). For comparison purpose, two dispersion measurements were used: variance and coefficient of variation. For each sampling plan the variance associated to the three steps of fumonisins quantification (sampling, sample preparation, and analysis), and the total coefficient of variation were determined. The correlation between the average fumonisins concentration and the variances for each phase of the detection procedure was evaluated for each sampling plan using analysis of regression. At the automatic sampling plan in milled grains for fumonisins analysis in maize both sampling variance (0.0226mg kg-1)² and total coefficient of variation (6.37%) were lower (P<0.01) than in the manual sampling plan in whole grains whit (0.0685mg kg-1)² of variance and 8.94% of coefficient of variation, showing so better efficiency for fumonisin detection on maize.

Comparison of the efficiency between two sampling plans for aflatoxins analysis in maize.

Variance and performance of two sampling plans for aflatoxins quantification in maize were evaluated. Eight lots of maize were sampled using two plans: manual, using sampling spear for kernels; and automatic, using a continuous flow to collect milled maize. Total variance and sampling, preparation, and analysis variance were determined and compared between plans through multifactor analysis of variance. Four theoretical distribution models were used to compare aflatoxins quantification distributions in eight maize lots. The acceptance and rejection probabilities for a lot under certain aflatoxin concentration were determined using variance and the information on the selected distribution model to build the operational characteristic curves (OC). Sampling and total variance were lower at the automatic plan. The OC curve from the automatic plan reduced both consumer and producer risks in comparison to the manual plan. The automatic plan is more efficient than the manual one because it expresses more accurately the real aflatoxin contamination in maize.