Diagnose of the ingestion of Asclepias mellodora St. Hil. by sheep through microhistological analysis of their digestive contents

Asclepias mellodora St. Hil. is a native acute toxic species frequent in the grasslands of the Buenos Aires province, Argentina, whose toxicity had not been assessed until now. This study evaluates the minimal lethal dose of this species for sheep, and the possibility of microscopically recognizing its fragments in gastrointestinal contents as a complementary diagnostic tool in necropsies. Three Frisona sheep (average LW=55±4.5 kg) were dosed via an esophageal tube with each one of the following doses of asclepias: 8.0, 5.0, 2.0 and 0.8 g DM.kg LW-1. Sheep poisoned with the three higher doses died between 10 and 85 h after intoxication, but those receiving the lower dose did not. During necropsies we: 1) determined the dry weight of the contents of rumen+reticulum, omasum+abomasum, and large intestine, 2) estimated the percentages of asclepias fragments by microanalysis correcting for digestion effects on fragment recognition, and 3) calculated the total mass of asclepias in the digestive tract of each animal. For the three higher doses, the mass of asclepias identified in the total ingesta was 12.3±3.4% of the amount supplied, possibly because of the strong diarrhea its ingestion produced. The percentages of asclepias in rumen+reticulum did not differ from the average quantified for the entire tract. The results of this study indicate that the minimal lethal doses of asclepias for sheep is between 2.0 and 0.8g DM·kg LW-1, and that the microhistological analysis of the rumen+reticulum, the easiest region to sample, can be used to confirm the ingestion of this toxic species, although the estimated percentage will be not a good estimator of the ingested percentage.

Conditioned food aversion to Ipomoea carnea var. fistulosa induced by Baccharis coridifolia in goats

Baccharis coridifolia is a plant that induces strong conditioned food aversion in ruminants. This research aimed to induce a conditioned food aversion to Ipomoea carnea var. fistulosa in goats, using B. coridifolia as an aversive agent, and to compare the aversion induced by this plant with the aversion induced by lithium chloride (LiCl). Thirteen goats were allotted into two groups: Group 1 with six goats was averted with 175mg/kg of body weight of LiCl and Group 2 with seven goats was averted with 0,25g/kg of bw of dried B. coridifolia. All goats were averted on day 1 after the ingestion of I. carnea. The aversion procedure with LiCl or B. coridifolia in goats from Groups 1 and 2, respectively, was repeated in those goats that again consumed the plant during tests on days 2, 3, and 7. The goats of both groups were challenged in pens on 23 and 38 days after the last day of aversion and challenged in the pasture on days 11, 15, 18, 20, 22, 25, 27 and 29 after the last day of aversion. After this period goats were challenged every 15 days on pasture until the 330º day after the last day of aversion (7th day). Two goats from Group 1 ingested I. carnea on the first day of the pasture challenge, 4 days after the last day of aversive conditioning in the pen. In addition, another goat in Group 1 started to consume the plant on day 18, and other two goats ate it on day 20. One goat in Group 1 that had never eaten I. carnea died on day 155. One goat from Group 2 started to ingest I. carnea on the first day of the pasture challenge, and a second goat started to consume this plant on day 182. At the end of the experiment, on day 330, the other five goats averted with B. coridifolia remained averted. These results suggest that B. coridifolia or an active compound from the plant could be used to induce aversion to toxic plants. Using B. coridifolia would be cheaper and, particularly in flocks with large number of animals, possibly easier than using LiCl, which requires the use of oral gavage and qualified personnel for its implementation.

An Hp-Adaptive Hierarchical Formulation for the Boundary Element Method Applied to Elasticity in Two Dimensions

This paper presents an HP-Adaptive Procedure with Hierarchical formulation for the Boundary Element Method in 2-D Elasticity problems. Firstly, H, P and HP formulations are defined. Then, the hierarchical concept, which allows a substantial reduction in the dimension of equation system, is introduced. The error estimator used is based on the residual computation over each node inside an element. Finally, the HP strategy is defined and applied to two examples.

Controle de plantas daninhas com cyanazine aplicado em mistura com outros herbicidas, na cultura do algodão (Gossypium hirsutum L.)

Com a finalidade de estudar a mistura de tanque mais eficiente com cyanazine em aplicação de pré-emergência na cultura algodoeira (Gossypium hirsutum L.) , foram estudados os seguintes tratamentos: cyanazine + diuron nas doses de 0,8 + 0,8 kg i.a/ha e 1,0 + 1,0 kg i.a/ha; cyanazine+ oryzalin , nas do sés de 1,2 + 0,8 kg i.a/ha e 1,6 + 1,2 kg i.a/h a; cyanazyne + metol a chlor, nas doses de 1,4 + 2,0 kg i.a/ha e 1,75 + 2,52 kg i.a/ ha;cianazine na dose de 1,75 kg i.a /ha; oryzalin na dose de 1,12 kg i.a/ha; metol achlor na dose de 2,52 kg i.a /ha e diuron na dose de 1,6 kg i.a /ha. Para efeito de comparação, utilizou-se uma testemunha sem capina e outra com capina manual. Nenhum tratamento apresentou injúria para as plantas de algodão e não houve diferenças significativas para o "stand" inicial. Já no "stand" final, a testemunha sem capina apresentou o menor número de plantas, sendo que não houve diferenças significativas dos outros tratamentos com a testemunha capinada. Para o rendimento, a mistura cyanazine + metolachior em ambas as doses estudadas, não apresentaram diferenças significativas da testemunha capinada. Quanto à altura da planta, peso de 100 sementes, porcentagem e índice de fibras não houve diferenças significativas entre os tratamentos estudados, somente o peso do capulho foi afetado pelo oryzalin. Pela avaliação visual (EWRC 1 a 9)*, os herbicidas apres entaram um controle satisfatório somente até os 30 dias após aplicação, sendo que a mistura cyanazine + metolachlor foi efici ente quanto a testemunha capinada. No controle da Portulaca oleracea , a mistura cyanazine + oryzalin na maior dose e oryzalin apresentaram 71,4% de controle ate os 30 dias e 79,4% e 82,4%, respectivamente, até 45 dias da aplicação. Para Amaranthus sp., à exceção da cyanazine e cyanazine + diuron nas doses menores, não apresentaram nenhum controle, sendo que os outros herbicidas controlaram com eficiência superior a 70%. Para Centratherium punctatum, o cyanazine apresentou 78,2% e 73,4%, respectivamente, após 50 e 45 dias da aplicação. Para Cyperus sp e & Brachiaria plantaginea, o metolachlor sozinho ou em mistura com cyanazine, apresentou uma eficiência de 90% para Cyperus sp. e de 70% para B. plantaginea até 45 dias da aplicação. Para as espécies não dominantes (maioria dicotiledôneas), o melhor controle foi de cyanazine + metol achlor na dose maior, com 70,5% e 60,2%, respectivamente, após 30 e 45 dias da aplicação. Para o total das espécies, cyanazine + metolachlor, em ambas doses estudadas, apresentaram controle de 66,2% e 67,3%, respectivamente, após 30 dias e 63,3% e 64,3%, respectivamente, após 45 dias da aplicação. Para as análises tecnológicas da fibra, não houve diferenças significativas na maturação da fibra, uniformidade de comprimento, índice Macronaire e índice Pressley. No comprimento da fibra, a mistura de cyanazine + diuron(0,8+ 0,8 kg ia/h a), apresentou o maior comprimento (26,1 mm) e cyanazine+ metol achlor (1,75 + 2,52 kg i.a / ha),o menor comprimento (24,9 mm), sem diferenças significativas com as testemunhas.

Paraquat poisoning: an experimental model of dose-dependent acute lung injury due to surfactant dysfunction

Since the most characteristic feature of paraquat poisoning is lung damage, a prospective controlled study was performed on excised rat lungs in order to estimate the intensity of lesion after different doses. Twenty-five male, 2-3-month-old non-SPF Wistar rats, divided into 5 groups, received paraquat dichloride in a single intraperitoneal injection (0, 1, 5, 25, or 50 mg/kg body weight) 24 h before the experiment. Static pressure-volume (PV) curves were performed in air- and saline-filled lungs; an estimator of surface tension and tissue works was computed by integrating the area of both curves and reported as work/ml of volume displacement. Paraquat induced a dose-dependent increase of inspiratory surface tension work that reached a significant two-fold order of magnitude for 25 and 50 mg/kg body weight (P<0.05, ANOVA), sparing lung tissue. This kind of lesion was probably due to functional abnormalities of the surfactant system, as was shown by the increase in the hysteresis of the paraquat groups at the highest doses. Hence, paraquat poisoning provides a suitable model of acute lung injury with alveolar instability that can be easily used in experimental protocols of mechanical ventilation

Statistical analysis of event-related potential elicited by verb-complement merge in Brazilian Portuguese

An interesting fact about language cognition is that stimulation involving incongruence in the merge operation between verb and complement has often been related to a negative event-related potential (ERP) of augmented amplitude and latency of ca. 400 ms - the N400. Using an automatic ERP latency and amplitude estimator to facilitate the recognition of waves with a low signal-to-noise ratio, the objective of the present study was to study the N400 statistically in 24 volunteers. Stimulation consisted of 80 experimental sentences (40 congruous and 40 incongruous), generated in Brazilian Portuguese, involving two distinct local verb-argument combinations (nominal object and pronominal object series). For each volunteer, the EEG was simultaneously acquired at 20 derivations, topographically localized according to the 10-20 International System. A computerized routine for automatic N400-peak marking (based on the ascendant zero-cross of the first waveform derivative) was applied to the estimated individual ERP waveform for congruous and incongruous sentences in both series for all ERP topographic derivations. Peak-to-peak N400 amplitude was significantly augmented (P < 0.05; one-sided Wilcoxon signed-rank test) due to incongruence in derivations F3, T3, C3, Cz, T5, P3, Pz, and P4 for nominal object series and in P3, Pz and P4 for pronominal object series. The results also indicated high inter-individual variability in ERP waveforms, suggesting that the usual procedure of grand averaging might not be considered a generally adequate approach. Hence, signal processing statistical techniques should be applied in neurolinguistic ERP studies allowing waveform analysis with low signal-to-noise ratio.

Effect of selective β-adrenoceptor blockade and surgical resection of the celiac-superior mesenteric ganglion complex on delayed liquid gastric emptying induced by dipyrone, 4-aminoantipyrine, and antipyrine in rats

There is evidence for participation of peripheral β-adrenoceptors in delayed liquid gastric emptying (GE) induced in rats by dipyrone (Dp), 4-aminoantipyrine (AA), and antipyrine (At). The present study aimed to determine whether β-adrenoceptors are involved in delayed GE induced by phenylpyrazole derivatives and the role of the prevertebral sympathetic nervous system in this condition. Male Wistar rats weighing 220-280 g were used in the study. In the first experiment rats were intravenously pretreated with vehicle (V), atenolol 30 mg/kg (ATE, β1-adrenergic antagonist), or butoxamine 25 mg/kg (BUT, β2-adrenergic antagonist). In the second experiment, rats were pretreated with V or SR59230A 2 mg/kg (SRA, β3-adrenergic antagonist). In the third experiment, rats were subjected to surgical resection of the celiac-superior mesenteric ganglion complex or to sham surgery. The groups were intravenously treated with saline (S), 240 µmol/kg Dp, AA, or At, 15 min after pretreatment with the antagonists or V and nine days after surgery. GE was determined 10 min later by measuring the percentage of gastric retention (%GR) of saline labeled with phenol red 10 min after gavage. The %GR (means±SE, n=6) values indicated that BUT abolished the effect of Dp (BUT+Dp vs V+Dp: 35.0%±5.1% vs 56.4%±2.7%) and At (BUT+At vs V+At: 33.5%±4.7% vs 52.9%±2.6%) on GE, and significantly reduced (P<0.05) the effect of AA (BUT+AA vs V+AA: 48.0%±5.0% vs 65.2%±3.8%). ATE, SRA, and sympathectomy did not modify the effects of treatments. These results suggest that β2-adrenoceptor activation occurred in delayed liquid gastric emptying induced by the phenylpyrazole derivatives dipyrone, 4-aminoantipyrine, and antipyrine. Additionally, the released neurotransmitter did not originate in the celiac-superior mesenteric ganglion complex.

Estimating microalgae Synechococcus nidulans daily biomass concentration using neuro-fuzzy network

In this study, a neuro-fuzzy estimator was developed for the estimation of biomass concentration of the microalgae Synechococcus nidulans from initial batch concentrations, aiming to predict daily productivity. Nine replica experiments were performed. The growth was monitored daily through the culture medium optic density and kept constant up to the end of the exponential phase. The network training followed a full 3³ factorial design, in which the factors were the number of days in the entry vector (3,5 and 7 days), number of clusters (10, 30 and 50 clusters) and internal weight softening parameter (Sigma) (0.30, 0.45 and 0.60). These factors were confronted with the sum of the quadratic error in the validations. The validations had 24 (A) and 18 (B) days of culture growth. The validations demonstrated that in long-term experiments (Validation A) the use of a few clusters and high Sigma is necessary. However, in short-term experiments (Validation B), Sigma did not influence the result. The optimum point occurred within 3 days in the entry vector, 10 clusters and 0.60 Sigma and the mean determination coefficient was 0.95. The neuro-fuzzy estimator proved a credible alternative to predict the microalgae growth.