Summary. Phomopsin, tbe mycotoxin produced by Phoniopsis teptosiroiniformis, was found to bave a very bigh toxicity for sbeep. When administered as a single, subcutaneous injection over the dose range 1 25 to 98 A^g/kg body weigbt, all sheep given 37 5 «g/kg or more died. Some, tboiigh not all. died following lower doses, Ihe minimum lethal dose being 10 A'g/kg. The time course of hepatic response over 21 days after phomopsin adminisiration was followed by plasma biochemical analyses including those for some enzymes (glutamate dehydrogenase, 7-glutamyl transpeptidase. aspartale aniinoiransferase and alkaline pbosphatase). total bilirubin and the determination of bromosulphopbthalein clearance rates. Hepatobiliary impairment was apparent after all dosages of 2.5 Mg/kg and above wbile 1.25 Mg/kg approximated the 'no effecl' level.
Summary. Tlii' hurst of initosJs in liver itlls after partial licpatectomy is inliiliitcd liy ct'rtain pyrrolizidine alkaloitls givoti prior to opi'nitiuii. Thus, intrapcritoneal injedion of O'{)5 aciite LD,-,,, «f lieliolrim' into rats up to 8 weeks before partial hepatet-tomy resulted in a 501 iiiliibitian of mitosis as measured 8 lir. afUT the ;)dnunislration of a (I(»se of t-olchicine.Ilt'liotrine, lasiotaniiiie and hisiocurpint; iV-oxidc Riven four weeks hffore operation prmtiiccd iniiviniat antimitotic clieet when Kiveii in a sinjilt-dose greater tlian alH)iit 0-1 a<'ute LD-,, and a nrndt-il resporiNc at lower dose levels. Ileliotrjdine, 7-anm'lyUifliotridine und platyphylline sliowed no siKiiificaiit activity.A bioiissay proc-ediire based on these findings is proposed, which is suitable for dotemiination of the specific anliniitotic activity nf compounds capable of persisteiit inliibition of liver cell division.
Samples of seed from commercial crops of Lupinus spp. in three States were tested for the presence of phomopsin, the causative agent of lupinosis. Each of 43 samples was tested in one of two laboratories using a nursling rat bioassay, and 12 of these were tested in both. Factors that could affect reproducibility of the assay were examined. There was good agreement in assessments of toxicity between laboratories. The efficiency of extraction was found to vary from about 15% at low concentrations of phomopsin to no more than 60%. Phomopsin was detected in 17 of the 43 samples, at levels ranging from < 6 �g/kg to 360 �g/kg. Phomopsis leptostromiformis infection was detected in 25 of 31 samples of seed from Western Australia, the highest infection level being 18%. The highest levels of phomopsin were found in samples with more than 8% infection.
Summary
Extracts of annual ryegrass. (Lolium rigidum) infected with Anguina sp., and Corynebacterium sp. and associated with an outbreak of annual ryegrass toxicity in sheep, were administered to 2‐week‐old rats by a single intraperitoneal injection. Rats that received a lethal dose of toxin developed neurological signs including incoordination and convulsions from the second day and most died between 2 and 7 days after injection. Histologically, the brains showed widespread lesions of focal necrosis consistent with anoxia. Peripheral circulation rate was greatly reduced after 3 days and gangrene of the tail and hind legs developed in some rats, Evidence of restricted blond How was also seen in kidneys, lungs and bruin. It was concluded that the toxin contains a long‐acting vasoconstrictor.
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