The role of bracken fern illudanes in bracken fern-induced toxicities.

Bracken fern is carcinogenic when fed to domestic and laboratory animals inducing bladder and ileal tumours and is currently classified as a possible human carcinogen by IARC. The carcinogenic illudane, ptaquiloside (PTQ) was isolated from bracken fern and is widely assumed to be the major bracken carcinogen. However, several other structurally similar illudanes are found in bracken fern, in some cases at higher levels than PTQ and so may contribute to the overall toxicity and carcinogenicity of bracken fern. In this review, we critically evaluate the role of illudanes in bracken fern induced toxicity and carcinogenicity, the mechanistic basis of these effects including the role of DNA damage, and the potential for human exposure in order to highlight deficiencies in the current literature. Critical gaps remain in our understanding of bracken fern induced carcinogenesis, a better understanding of these processes is essential to establish whether bracken fern is also a human carcinogen.

The small hydrophobic (SH) gene of North American turkey AMPV-C does not attenuate nor modify host tropism in recombinant European duck AMPV-C.

Subgroup C Avian Metapneumoviruses (AMPV-C) has two lineages, one mostly in turkeys and one mostly in ducks. To investigate the molecular basis of AMPV-C host tropism, a reverse genetics system for a duck AMPV-C virus was developed. A recombinant copy and a recombinant virus in which the SH protein had been exchanged for that of a turkey AMPV-C were rescued. No change in cytopathogenic effect or replication profile in vitro were observed for either virus compared to the wild type. In SPF Muscovy ducks the wild type and its recombinant copy were equally pathogenic. Exchanging the SH in the recombinant copy produced the same results. In SPF turkeys, neither recombinant virus was pathogenic, although both showed a low level of replication. Thus, from the current model, it appears that AMPV-C SH proteins derived from the different species are compatible and that turkey SH does not affect duck AMPV-C pathogenicity.

Efficacy of feed additives against Campylobacter in live broilers during the entire rearing period.

Poultry meat is the major source of human campylobacteriosis, the most frequently reported zoonosis in the EU. The prevalence of Campylobacter colonization in European broiler flocks is 71%. Despite considerable efforts, there is still no effective strategy available to prevent or reduce Campylobacter colonization in broilers. This study tested a wide variety of feed additives to reduce Campylobacter shedding in primary poultry production. Twelve additives containing organic or fatty acids, monoglycerides, plant extracts, prebiotics, or probiotics were tested. For each additive, broilers contaminated with Campylobacter jejuni were fed with an additive free diet (control group) or with a supplemented diet (treated group) and Campylobacter loads compared at three sampling times. No treatment was able to prevent broiler colonization by Campylobacter, and there was a high degree of variation in contamination among the birds. At 14 d of age, eight treatments significantly decreased the colonization level compared to the control group by a maximum of 2 log10 CFU/g. At 35 d of age, three of these treatments still had a significant effect with a maximum reduction of 1.88 log10 CFU/g for a probiotic. At 42 d of age, only one short-chain fatty acid was still significantly efficient with a mean reduction over 2 log10 CFU/g. In addition, a probiotic and a prebiotic-like compound significantly decreased the contamination by a maximum of 3 log10 CFU/g, only at the 42-d sampling period. This study gives promising results regarding the use of feed additives to reduce Campylobacter infection in flocks. Nevertheless, a global approach, combining intervention measures at the different steps of the broiler meat production chain could have a greater impact on the reduction of public health risk.

Transfer of melamine in some poultry products.

This study deals with the transfer of melamine from poultry feed to certain poultry products, such as eggs and meat destined for human consumption. The tested amounts were, respectively, 50 and 500 mg of melamine/kg of feed. The addition of melamine had no significant effect on feed consumption and egg production. However, melamine appeared in the eggs as early as the first day of exposure. The average concentration was reached after the third day at both levels of contamination. The amounts of melamine found in eggs and tissues were almost directly proportional to the quantities ingested. However, melamine did not appear to accumulate in the organs and tissues that were studied.

Human carcinogenesis and bracken fern: a review of the evidence.

The complex taxon embraced in the Pteridium genus, popularly known as bracken fern and notorious weeds in many parts of the world, is one of the few vascular plants known to induce cancer naturally in animals. It has been known for long to be acutely toxic to livestock and sublethal chronic oral feeding of bracken fronds leads to cancerous lesions in the urinary bladder, or bovine enzootic haematuria (BEH) and ileum of cattle. Bracken poisoning has been attributed chiefly to ptaquiloside, a norsesqui-terpene which is also a potent carcinogen inducing various malignancies in laboratory animals. It is capable of alkylating uncoiled DNAbases at key proto-oncogenes of selected organs. Some human populations also eat young bracken shoots and epidemiological studies in Japan and Brazil have shown a close association between bracken consumption and cancers of the upper alimentary tract. In addition, other studies reveal that the mere presence of bracken swards represents a greater risk to die of gastric adenocarcinoma for people who live more than 20 years in such areas or are exposed in childhood. This work reviews the bracken-cancer connections established by in vitro and in vivo experiments and epidemiological studies in various parts of the world, and provides insights into the possible bridges for bracken carcinogens to reach the human diet. Also, specific points where more research is needed are highlighted.

Possible association between gastric cancer and bracken fern in Venezuela: an epidemiologic study.

To explore a possible connection between specific environmental factors that might explain the high rates of stomach cancer in people living in the highlands of western Venezuela, an epidemiologic study was conducted in 2 regions of contrasting topography. The regions embrace 3 Andean states, Mérida, Táchira and Trujillo, and the vicinal lowland surrounding the Maracaibo lake basin of Zulia State. Statistical sanitary records from 1986 to 1996 comprising 5.5 million people in the study area indicated that age-sex-adjusted gastric cancer death rate per 100,000 people (DR) was up to 3.64 times higher in highland than lowland areas, although total cancer-related DRs were comparable in both regions. DRs of other less frequent cancers from the upper alimentary tract [esophagous (1.18/0.99) and mouth-throat (1.39/2.64)] showed comparable values in both regions as well as colorectal, breast, and uterus-cervix cancers, suggesting that the stomach cancer DRs were related to geographically determined factors. Comparison of some nutrition issues, incidence of Helicobacter pylori infection in selected areas, the discovery of the bracken carcinogen ptaquiloside in milk from bracken-fed cows, the prevalence of this plant in mountain cattle households and pasturelands and the rates of bracken-evoked bovine enzootic hematuria led us to conclude that consumption of ptaquiloside-contaminated milk may contribute to human gastric cancer in the Andean states of Venezuela.

Ptaquiloside Z, a new toxic unstable sesquiterpene glucoside from the neotropical bracken fern Pteridium aquilinum var. caudatum.

Reversed-phase HPLC fractionation, monitored by brine shrimp bioassay, led to the isolation of a new illudane-type sesquiterpene glucoside, ptaquiloside Z (2), as well as the known bracken carcinogen ptaquiloside (1), from a bioactive aqueous extract of the neotropical bracken fern Pteridium aquilinum var. caudatum (Pteridaceae). The structure of ptaquiloside Z (2) was confirmed by spectroscopic analyses and chemical degradation. Both compounds exhibited similar toxicity (LC50 62.5 micrograms/ml at 24 h and LC50 7.8 micrograms/ml at 48 h) toward brine shrimp.

A new bioassay for testing plant extracts and pure compounds using red flour beetleTribolium castaneum Herbst.

We designed a new bioassay to test plant extract activity against stored product pests. Plant compounds were added to feed disks composed of wheat flour and yeast and fed to the red flour bettle (Tribolium castaneum). By measuring insect mass, disk mass, and insect mortality over time it was possible to calculate a phagodepression index, an antifeedant index, the amount of treatment chemical ingested by the beetles, the mortality rate, and the efficiency of conversion of ingested food. The assay was performed for 60 hr to allow for possible habituation effects and to discriminate between phagodeterrency and physiological stress caused by treatments. α- and ß-Pinene, eugenol, kaurenic acid, sparteine, essential oils ofMinthostachis mollis andMelaleuca quinquenervia, and extracts ofSapindus saponaria were tested. Using this assay we detected the presence of both phagodepressant and phagostimulant compounds inS. saponaria extracts, and we quantified the pronounced effects of sparteine onT. castaneum.

Ontogenic variation of biologically active metabolites ofPteridium aquilinum (L. Kuhn) pterosins A and B, and ptaquiloside in a bracken population of the tropical andes.

A negative correlation has been found between the amounts of pterosins A and B and ptaquiloside per biomass unit, and the growth stage of the blade of bracken. Their concentration decreased progressively from the crozierto the mature frond, where it attained less than 5% of the initial value. The growth was measured following the total blade length, its height, moisture content, and time of emergence from the soil surface. Quantitation of these compounds was achieved by HPLC using a water extraction, methylene chloride treatment, and silica gel microcolumn cleanup sequence. Pterosins were unevenly distributed in the blade, whereas ptaquiloside maintained a constant concentration throughout. Rhizomes contained only minor amounts of these compounds. Their possible role as semiochemicals in bracken is discussed.