Aflatoxin B1 and Reye's syndrome

Chronic neurodegeneration by aflatoxin B1 depends on alterations of brain enzyme activity and immunoexpression of astrocyte in male rats

Aflatoxin B1 poses the greatest risk among the mycotoxins to target-organisms particularly human, however, no studies addressed the neurotoxicity of chronic exposure of aflatoxin. The oral dose level 1/600th of LD50 for 30, 60, and 90 days was used for three aflatoxin groups, respective to negative and vehicle control groups. Activity levels of brain antioxidants viz: superoxide dismutase, catalase, glutathione, and glutathione peroxidase significantly decreased in the three experimental durations in time-dependent trend, in contrast, lipid peroxidation showed a significant increase compared to controls. Significantly, chronic-dependent increase trend was noticed in the AF60 and AF90 group for acid phosphatase (16.1%, 35.2%), alkaline phosphatase (32.1%, 50.8%), aspartate aminotransferase (38.7%, 120.0%) and lactate dehydrogenase (30.6%, 42.1%) activities, respectively. However, a significant 23.7% decrease in the brain creatine kinase activity following 90 days of AFB1administration. Chronic administration of aflatoxin also causes alterations in activities of protein carbonyl with a maximum increase (twofold) after 90 days. Further, histopathological and immunohistochemical results confirmed time-related vasodilation, necrosis and astrocytes gliosis by high glial fibrillary acidic protein immunostaining in response to AFB1. These findings infer that long-term exposure to AFB1 results in several pathophysiological circumstances in a duration-dependent manner concerning neurodegeneration especially Alzheimer's disease.

Acute and reversible fatty metamorphosis of cultured rat hepatocytes

Rat hepatocyte cell line M6, B347 and J525, among which only M6 is slightly deviated from diploidy, showed marked microvesicular fatty metamorphosis in response to treatment with Tweens at concentrations of 0.05-0.025% in Eagle's minimum essential medium (MEM). Within 24 h treated cells became fatty at 100% in frequency and filled with small lipid droplets, as revealed by fat staining or at the ultrastructural level. Fatty hepatocytes, however, took again non-fatty morphology 72 h after withdrawal of Tweens from the culture medium. Growth of the cell exhibited mild retardation at the early phase of the treatment but almost similar cell density to that of control cells was achieved 24 h after the treatment. Other detergents without fatty-acid moiety, including NP-40, triton X-100, sodium deoxycholic acid and sodium cholic acid, were ineffective to induce fatty change. Oleate, a fatty-acid moiety of Tween 80 or 85, and linolate caused reversible fatty metamorphosis of the cell lines at concentrations of 1.9 x 10(4) mol/L or more and 3.8 x 10(4) mol/L or more, respectively. Ethanol induced mild steatosis of the cell lines and enhanced fatty change by linolate. Hepatic fatty acid-binding protein was not detected in the cell lines before or after the induction of fatty change. These results indicate that fatty acid itself is directly incorporated in cultured rat hepatocytes and expelled 3 days later without apparent cell degeneration.

Effect of aflatoxin B1 on brain serotonin and catecholamines in chickens

A single oral dose of aflatoxin B1 at 3 mg/kg body weight caused a significant increase in brain serotonin (5-HT) in 5-week-old chickens. Norepinephrine (NE) brain concentration significantly decreased, whereas the dopamine (DA) concentration remained unchanged. These results suggest that in modifying the concentrations of biogenic amines in the brain, aflatoxin B1 may affect brain function.

Reye's syndrome in a child on long-term salicylate medication

A case of Reye's syndrome in a four-year-old child on long-term salicylate medication for rheumatoid arthritis is reported. Severe fatty changes of the liver, lipid vacuolation in the renal proximal tubules, and severe brain oedema were the prominent postmortem findings. Symptoms of a trivial infection and vomiting just before death added to the resemblance of this case to Reye's syndrome.

Influence of trace elements and nitrogen sources on versicolorin production by a mutant strain of Aspergillus parasiticus

A mutant strain of Aspergillus parasiticus blocked in aflatoxin biosynthesis accumulates versicolorin A and versicolorin C. The effect of trace elements on the growth and versicolorin production by this strain was studied in a defined medium. The omission of manganese was slightly stimulatory to versicolorin production; when zinc was omitted from the medium, no detectable versicolorins were produced. Experiments on nitrogen sources in a high-sucrose medium indicated that fourfold to fivefold increases in versicolorin yields could be obtained by substituting 3 ml/l corn steep liquor or 0.1 M NH4NO3 for the 0.023 M (NH4)2SO3 used previously as the nitrogen source in studies on versicolorin production by this strain. These improved yields will facilitate attempts to accumulate enough versicolorin A and versicolorin C for toxicity and carcinogenicity testing. Chromatographic profiles of mycelial extracts of cultures grown in a defined medium with 0.1 M NH4NO3 as the nitrogen source revealed 2 previously unrecognized compounds. The accumulation of these new metabolites in a mutant blocked in aflatoxin production may indicate that they are biosynthetically related to aflatoxin.

Chloramphenicol and phenobarbitone--a drug interaction

Two infants with meningitis who were treated with phenobarbitone and high-dose chloramphenicol showed progressive falls in the peak blood levels of chloramphenicol. A standard chloramphenicol dose of 50 mg/kg daily would have produced subtherapeutic blood levels after only a few days. The importance of measuring serial blood chloramphenicol concentrations is stressed.