ELISA and HPLC determination of the occurrence of aflatoxin M(1) in raw cow's milk.

Raw cow's milk collected from dairy farms in the province of Leon, Spain, was examined for aflatoxin M(1) (AFM(1)). The samples were analysed with a commercial competitive enzyme-linked immunosorbent assay (ELISA) kit and high-performance liquid chromatography (HPLC). The concentrations of AFM(1) in the milk extracts were initially estimated by ELISA, with recovery rates of 74.6-109% for artificially contaminated milk at levels of 10-80 ng x l(1). Samples found to contain more than 10 ng x l(1) were further quantified with HPLC. The mean recovery for this method was 89.3%. The quantification limit was 10 ng x l(1) for both ELISA and HPLC. Although AFM(1) was confirmed in only 3.3% of the samples, the concentrations in all these cases were lower than the maximum limit applicable to these products pursuant to European Union legislation. Both methods were validated with reference material certified by the Community Bureau of Reference.

Modificaciones estructurales y ultraestructurales en la mucosa gastrointestinal por acción de radicales libres. Posible efecto protector del etanol / Estructural and ultraestructural modifications in gastrointestinal mucosa mediated by free radicals. Possible protective effect by ethanol

El objetivo de este trabajo es estudiar como se modifica la estructura de la mucosa gastrointestinal al verse expuesta a radicales libre y determinar si el etanol puede disminuir los daños producidos por estos radicales libres. Para ello hemos estudiado las alteraciones histológicas (estructurales y ultraestructurales) de la mucosa gastroduodenal de ratas tratadas con el reactivo de Fenton (generador de radicales libres) con y sin etanol. Nuestros resultados muestran que a nivel estructural, el grupo de ratas a las que se administró etanol junto con el reactivo de Fenton presentaban menos lesiones de tipo inflamatorio que el grupo de animales tratados solo con el reactivo de Fenton sin etanol, lo que indica que el etanol sí amortigua la acción de estos radicales libres. Sin embargo a nivel ultraestructural no podemos hacer diferenciaciones entre los dos grupos ya que todas las lesiones encontradas son lesiones celulares inespecíficas y aparecen con igual frecuencia en los mismos. Por lo tanto, debido a la inespecificidad de las alteraciones histológicas producidas por los radicales libres, estas solo nos pueden reflejar la intensidad del daño producido pero no su etiología (AU)

Muscle and serum changes with salbutamol administration in aerobically exercised rats.

Treatment of experimental animals subjected to 90 days physical training programme plus repeated doses of salbutamol, a beta-adrenergic agonist, administered under two different regimes: therapeutic (16 microg/kg body weight, twice a day) and doping (3 mg/kg body weight, twice a day), caused a marked increase in size of skeletal (soleus, gastrocnemius and plantaris) leg muscles. Adrenergic involvement of salbutamol-linked hypertrophy was demonstrated by co-administration of the non-specific beta-adrenergic antagonist D,L-propranolol (10 mg/kg body weight twice a day). The salbutamol-induced muscle hypertrophy was associated with an early increase in creatine phosphokinase (CK) and its myocardial isozyme (CKmb), without significant changes in lactate dehydrogenase (LDH), alanine aminotransferase (AAT) and aspartate aminotransferase (DAT). The induction of muscle-injury biomarkers was completely abolished by co-administration of propranolol, thus suggesting the adrenergic involvement of these alterations.

Preventive treatment of rabbit coccidiosis with alpha-difluoromethylornithine.

The effect of alpha-difluoromethylornithine (DFMO) administered in drinking water (0.2 and 0.5%) against liver and intestinal coccidioses in experimentally infected rabbits was studied. Zootechnical and clinical parameters were used to assess the efficacy of the compound. In both coccidioses the lower dose did not show any important effect. The higher dosage (0.5%) however, reduced the lesions induced by coccidia to an important extent. The animals infected and treated with 0.5% DFMO showed similar weight gain, food intake and relative liver weight figures to the non-infected controls. Serum transaminase levels in the rabbits infected with Eimeria stiedai and treated with 0.5% DFMO were close to those of the non-infected animals. Infected rabbits treated with this dosage also showed reductions (over 80%) in faecal oocyst output.

Effects of methylglyoxal bis(guanylhydrazone) and two phenylated analogues on S-adenosylmethionine decarboxylase activity from Eimeria stiedai (Apicomplexa).

1. Activity of S-adenosylmethionine decarboxylase, one of the rate-limiting enzymes of polyamine biosynthesis, was determined in oocysts of Eimeria stiedai, a coccidian parasite of the rabbit. 2. Several properties of the enzyme were compared to the mammalian enzyme. It showed considerably less substrate affinity than the analog enzyme from the rabbit. 3. The E. stiedai enzyme showed a low sensitivity to methylglyoxal bis(guanylhydrazone), a frequently used inhibitor of the enzyme in mammals, and two phenylated derivatives. 4. Results with the inhibitors are discussed in view of their potential use in chemotherapy.

Properties of S-adenosylmethionine decarboxylase from rabbit liver: effects of some hydrazone compounds on its activity.

S-Adenosylmethionine decarboxylase (EC 4.1.1.50) has been partially purified from rabbit liver by ammonium sulphate fractionation and gel filtration and anion exchange chromatographies. Sodium dodecylsulphate-polyacrylamide disc gel electrophoresis analysis showed an approximate dimeric subunit mol. wt of 34,000. The enzyme showed a pH optimum at 7.5 (in phosphate buffer) and did not require bivalent cations for catalysis. The enzyme showed sigmoid kinetics to S-adenosylmethionine with a Hill coefficient of 1.7, which became michaelian with Km 70 microM in the presence of 2.5 mM putrescine. Methylglyoxal bis(guanylhydrazone) was an effective inhibitor of the enzyme, but phenylated derivatives of this compound as phenylglyoxal bis(guanylhydrazone) and diphenylglyoxal bis-(guanylhydrazone) inhibited less well.