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Biomedical subjects

M C Mendez

Publications and source records attributed to M C Mendez.

14 recordsLinked to original sources
PubMed2001

Experimental intoxication by larvae of Perreyia flavipes Konow, 1899 (Hymenoptera: Pergidae) in pigs and some aspects on its biology.

Two pigs were dosed with 5 and 10g/kg bw of fresh Perreyia flavipes larvae collected at the municipality of Pelotas. Two other pigs were dosed with 0.87 and 1.7g/kg of dry P. flavipes (equivalent to 5 and 10g/kg bw of fresh larvae). Another pig was dosed with 0.17g/kg of dry larvae, daily, during 20d. Forty-eight hours after the ingestion, all pigs that ingested single doses showed clinical signs and marked rise in serum aspartate aminotransferase. Alanine aminotransferase and gamma glutamiltransferase were also slightly increased. The pig dosed with 10g/kg of fresh larvae died in 96h. The others recovered in 4-5days after ingestion. No clinical signs were observed in the pigs dosed during 20d with 0.17g/kg of dry larvae. The main lesion observed in the pig dosed whit 10g/kg of fresh larvae was a centrilobular liver necrosis. These results confirmed the toxicity of P. flavipes for swine, demonstrated that the larvae maintain the toxicity after being dried, and suggest no cumulative effect in the larval toxicity. The larvae collected in the field were conditioned in boxes containing swards of native grasses and covered with gauze to prevent the escape of adults on emergence. The larvae pupated from August 11 to September 25. Emergency of adults occurred from February 10 to March 4. Adult females and males live only for 18-36 and 24-48h, respectively. The eggs had an incubation period of 26-33d. The larval period extend from March 1 to August 24.

Animals↗
PubMed1999

Unique toxic peptides isolated from sawfly larvae in three continents.

D-Amino acid containing peptides have been found to be responsible for sawfly larvae poisoning in many parts of the world. These compounds, unique in the animal kingdom, were isolated from three different species of sawfly indigenous to Australia, Denmark and South America. The octapeptide, lophyrotomin, is the major toxin in the Australian and Danish species and is present in small amounts in the South American sawfly. Pergidin, the main toxin in the South American sawfly, is a heptapeptide containing a phosphoseryl residue. This, as far as we are aware, is the first example of such a peptide to be isolated from an animal source. Small amounts of pergidin have been found in the other two species. All available evidence suggests that both peptides are biosynthesised 'de novo' possibly as a protective device, however it cannot be excluded that microorganisms may be responsible. These compounds are stable to enzymatic breakdown because of their configuration and their strong chemical bonding and lipophilic character provide a potential for residues to remain in the host animal and cause significant changes.

Animals↗
PubMed1998

Experimental intoxication by Myoporum laetum in sheep.

Myoporum laetum was collected in the municipalities of Rio Grande and Capao do Leao in winter and in Santa Vitoria in summer, autumn, winter and spring, in the state of Rio Grande do Sul, Brazil, and in the Department of Rocha, Uruguay, in winter and spring. The fresh green plant was fed to 17 sheep. All sheep developed clinical signs, except 1 that consumed only 4 g/kg bw daily during 10 d. Five of the 9 sheep dosed with 40 g/kg died. Four sheep dosed with plants from Uruguay at 40 g/kg, 6 sheep dosed with 20 g/kg, and 1 sheep dosed with 2 daily doses of 8 g/kg survived. Clinical signs were anorexia, restlessness, ruminal stasis, jaundice and dry feces with mucus or blood. All surviving sheep had photodermatitis in the face, ears, eyes and lips. Histologic lesions were characterized by periportal liver necrosis. Serum levels of AST, GGT and bilirubin were increased. M laetum from Uruguay was less toxic, suggesting a variation in toxicity among plants from different regions.

Animals↗
PubMed1998

Intoxication by Xanthium cavanillesii in cattle and sheep in southern Brazil.

Three outbreaks of Xanthium cavanillesii intoxication occurred in the spring in the State of Rio Grande do Sul, southern Brazil. All outbreaks were observed in paddocks with sandy soils in flood plains along water streams. The paddocks had been under water, and after water withdrawal cattle were introduced to those areas which had seedlings of X cavanillesii and shortage of other forage. Mortality varied between 3 and 58%. Most animals were found dead or died a few hours after observation of clinical signs. The main lesion was a swollen liver with acute diffuse centrilobular necrosis. The disease was produced experimentally by feeding cotyledons at 0.75 and 1% bw in calves, and at 1.5 and 2% bw in sheep. Clinical signs and gross and microscopic lesions were similar to those observed in field cases. X cavanillesii in the 4-leaf stage with the attached cotyledons was also toxic for cattle and sheep, but the same plant without cotyledons lost its liver toxicity. The lethal dose of cotyledons divided in 5 daily doses was not toxic for cattle and sheep, demonstrating the non-cumulative effect of the plant.

Animals↗
PubMed1998

Experimental intoxication by Myoporum laetum in cattle.

Myoporum laetum was collected in the counties of Rio Grande and Capao do Leao in winter and in Santa Vitoria in summer, autumn, winter and spring, in the state of Rio Grande do Sul and in the Department of Rocha, Uruguay, in winter and spring. The fresh green leaves were fed to 16 calves. Two calves that ingested the plant from Capao do Leao at 40 and 44 g/kg bw did not develop clinical signs. The other 14 calves had depression, abdominal pain, ruminal atony, ocular and nasal serous discharge, and dry feces with blood and mucus. Four calves developed icterus. First signs appeared 24-72 h after ingestion, and clinical period varied from 2 to 7 d. One animal had mild photosensitization. Calves dosed with 20 g/kg of plant from Santa Vitoria and 40 g/kg of plant from Uruguay had less severe clinical signs. All cattle recovered except 1 dosed with 40 g/kg of plant collected in winter in Santa Vitoria; it died 70 h after ingestion. Histologic lesions in the liver of this animal and in biopsies obtained 48 h after dosing other calves had centrilobular necrosis, sometimes extending to the midzonal region. Clinical signs and hepatic lesions were also observed in a calf dosed with 5 daily doses at 8 g/kg. Serum AST, GGT and bilirubin were increased. M laetum from Santa Vitoria was the most toxic for cattle, and the plant from Uruguay was the least toxic, suggesting variations in toxicity among plants from different regions.

Alanine Transaminase↗
PubMed1997

Poisoning of cattle and sheep in Uruguay by sawfly (Perreyia flavipes) larvae.

From June to early October of 1993, 1994 and 1995 at least 40 outbreaks of a highly lethal disease occurred in cattle and sheep in the central region of Uruguay. During 1995 total cattle losses probably exceeded 1000 head. Mortalities were 1.6%, 7.0% and 1.3% for calves, yearlings and adults, respectively, but mortalities up to 28% occurred on some farms. Sheep were less frequently affected than cattle. Most animals were just found dead. Cattle had weakness, muscular tremors, depression, stupor and death. Others became highly excited and aggressive. Most affected cattle died within 2 d. Jaundice and mild photosensitization were observed in cattle that survived longer. Gross and microscopic lesions were severe periacinar or massive necrosis of hepatocytes with prominent edema of the gall bladder wall and its attachments. Edema, ecchymoses and petechiae on serous membranes, ascites and dry content of the omasum, colon and rectum were also observed. Invariably larval body fragments and heads of P flavipes were found in the rumen and omasum. The diagnosis of sawfly poisoning was confirmed by experimental feeding of 3 sheep and 2 calves with 9 to 40 g of P flavipes larvae/kg body weight.

Animals↗
PubMed1995

Snakebite in sheep.

Snakebite caused by Bothrops neuwiedi in sheep of southern Brazil is described. In a flock of 135 sheep, 22 were bitten and 11 died. Most cases occurred at the end of December and during January when the pastures were overgrazed due to severe drought. No more cases were observed after the end of January when abundant rainfall began. The main clinical signs were local edema followed by necrosis and sloughing of the skin.

Animals↗
PubMed1988

Livestock poisoning in South America by species of the Senecio plant.

The pyrrolizidine alkaloids retrorsine, senecionine, integerrimine, neosenkirkine and florosenine were isolated from different Senecio spp. common in southern Brazil, Uruguay and Paraguay. Structure elucidation of these compounds was mainly accomplished by two-dimensional FT NMR techniques. Detailed interpretations of 1H-1H and 1H-13C NMR correlation spectra are given. The alkaloids neosenkirkine, integerrimine and florosenine were found in Senecio leptolobus De Candolle, retrorsine accompanied by senecionine in Senecio selloi (Spreng.) DC and Senecio cisplatinus Cabrera. In Senecio heterotrichus DC. integerrimine is accompanied by retrorsine. Investigations on pathology and histopathology of Senecio envenomation in Brazil are summarized.

Alkaloids↗