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While rising global rates of neurodegenerative disease encourage early diagnosis and therapeutic intervention to block clinical expression (secondary prevention), a more powerful approach is to identify and remove environmental factors that trigger long-latencybrain disease (primary prevention) by acting on a susceptible genotype or acting alone. The latter is illustrated by the post-World War II decline and disappearance of Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS/PDC), a prototypical often-familial neurodegenerative disease formerly present in very high incidence on the island of Guam. Lessons learned from 75 years of investigation on the etiology of ALS/PDC include: the importance of focusing field research on the disease epicenter and patients with early-onset disease; soliciting exposure history from patients, family, and community to guide multidisciplinary biomedical investigation; recognition that disease phenotype may vary with exposure history, and that familial brain disease may have a primarily environmental origin. Furthermore, removal from exposure to the environmental trigger effects primary disease prevention., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Between 1990 and 2018, 14 cases of amyotrophic lateral sclerosis (ALS) were diagnosed in residents of, and in visitors with second homes to, a mountainous hamlet in the French Alps. Systematic investigation revealed a socio-professional network that connected ALS cases. Genetic risk factors for ALS were excluded. Several known environmental factors were scrutinized and eliminated, notably lead and other chemical contaminants in soil, water or home-grown vegetation used for food, radon and electromagnetic fields. Some lifestyle-related behavioral risk factors were identified: Prior to clinical onset of motor neuron disease, some patients had a high degree of athleticism and smoked tobacco. Recent investigations on site, based on a new hypothesis, showed that all patients had ingested wild mushrooms, notably poisonous False Morels. Half of the ALS cohort reported acute illness following Gyromitra gigas mushroom consumption. This finding supports the hypothesis that genotoxins of fungal origin may induce motor neuron degeneration., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Twenty Gram-negative bacterial (GNB) strains were selected based on the biodiversity previously observed in French traditional cheeses and their safety was assessed considering various safety criteria. For the majority of tested GNB strains, only gastric stress at pH 2 (vs pH 4) resulted in low survival and no regrowth after an additional simulated gastro-intestinal stress. Presence of milk was shown to be rarely protective. The majority of strains was resistant to human serum and had a low level of adherence to Caco-2 cells. When tested for virulence in Galleria mellonella larvae, GNB strains had LD 50 values similar to that of safe controls. However, four strains, Hafnia paralvei 920, Proteus sp. (close to P. hauseri) UCMA 3780, Providencia heimbachae GR4, and Morganella morganii 3A2A were highly toxic to the larvae, which suggests the presence of potential virulent factors in these strains. Noteworthy, to our knowledge, no foodborne intoxication or outbreak has been reported so far for any of the GNB belonging to the genera/species associated with the tested strains. The role of multiple dynamic interactions between cheese microbiota and GIT barriers could be key factors explaining safe consumption of the corresponding cheeses., (Copyright © 2018. Published by Elsevier Ltd.)

For many years, microbial adjuncts have been used to supplement the diets of farm animals and humans. They have evolved since the 1990s to become known as probiotics, i.e. functional food with health benefits. After the discovery of a possible link between manipulation of gut microflora in mice and obesity, a focus on the use of these beneficial microbes that act on gut microflora in animal farming was undertaken and compared with the use of probiotics for food. Beneficial microbes added to feed are classified at a regulatory level as zootechnical additives, in the category of gut flora stabilizers for healthy animals and are regulated up to strain level in Europe. Intended effects are improvement of performance characteristics, which are strain dependent and growth enhancement is not a prerequisite. In fact, increase of body weight is not commonly reported and its frequency is around 25% of the published data examined here. However, when a Body Weight Gain (BWG) was found in the literature, it was generally moderate (lower than or close to 10%) and this over a reduced period of their short industrial life. When it was higher than 10%, it could be explained as an indirect consequence of the alleviation of the weight losses linked to stressful intensive rearing conditions or health deficiency. However, regulations on feed do not consider the health effects because animals are supposed to be healthy, so there is no requirement for reporting healthy effects in the standard European dossier. The regulations governing the addition of beneficial microorganisms to food are less stringent than for feed and no dossier is required if a species has a Qualified Presumption of Safety status. The microbial strain marketed is not submitted to any regulation and its properties (including BWG) do not need to be studied. Only claims for functional or healthy properties are regulated and again growth effect is not included. However, recent studies on probiotic effects showed that BWG could also be observed in humans, or not, according to species and strains. Determining the significance of farm animal results for extrapolation to humans, especially regarding body weight improvement, was not easy because they do not use the same microbial strains nor always the same species. Furthermore, the framework for the management of microbials added to feed or to food differ, especially with regard to goal, timescale and lifestyle. So no one can exclude the possibility that beneficial microorganisms having probiotic effects may have long-term effects in humans that cannot be seen to date in animals, where short-term use is the rule. A possible link to obesity cannot be excluded in relation to timescale, species and strain specificity. To conclude, beneficial microorganisms added in feed are key factors stringently regulated for short-term improvement of zootechnical performances in animals and their use does not entirely parallel that of human probiotics. So extrapolation of farm animal results to humans is biased and not sufficient to be conclusive regarding the existence or not of a link between probiotics and obesity. From a toxicological and nutritional point of view and considering recent findings on a link between antibiotic use in early life and excessive risk of becoming overweight, one suggestion is to study the at-risk population in Europe, pregnant women and their babies before and after birth and during early childhood, in an epidemiological long-term cohort survey., (© 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.)

Two model antilisterial microbial communities consisting of two yeasts, two Gram positive and two Gram negative bacteria, and originating from Livarot cheese smear were previously designed. They were used in the present study to analyse the impact of microbial population dynamics on growth of Listeria monocytogenes in cheese microcosm. Specific culture media and PCR primers were developed for simultaneous culture-dependent and real-time PCR quantification of strains belonging to Marinomonas sp., Paenibacillus sp., Staphylococcus equorum, Arthrobacter arilaitensis, Pseudomonas putida, Serratia liquefaciens, Candida natalensis, and Geotrichum candidum, in cheese microcosms. All strains were enumerated after 3, 5, 8 and 14 days at 15 °C. They established well at high counts in all cheese microcosms. Growth dynamics for all strains in presence of L. monocytogenes WSLC 1685 were compared to those of microbial communities obtained by omitting in turn one of the six members of the initial community. The growth of the microbial strains was neither markedly disturbed by Listeria presence nor by the removal of each strain in turn. Furthermore, these communities had a significant reducing effect on growth of L. monocytogenes independently of pH, as confirmed by mathematical modelling. A barrier effect was observed, that could be explained by specific competition for nutrients., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Starting from one undefined cheese smear consortium exhibiting anti-listerial activity (signal) at 15 °C, 50 yeasts and 39 bacteria were identified by partial rDNA sequencing. Construction of microbial communities was done either by addition or by erosion approach with the aim to obtain minimal communities having similar signal to that of the initial smear. The signal of these microbial communities was monitored in cheese microcosm for 14 days under ripening conditions. In the addition scheme, strains having significant signals were mixed step by step. Five-member communities, obtained by addition of a Gram negative bacterium to two yeasts and two Gram positive bacteria, enhanced the signal dramatically contrary to six-member communities including two Gram negative bacteria. In the erosion approach, a progressive reduction of 89 initial strains was performed. While intermediate communities (89, 44 and 22 members) exhibited a lower signal than initial smear consortium, eleven- and six-member communities gave a signal almost as efficient. It was noteworthy that the final minimal model communities obtained by erosion and addition approaches both had anti-listerial activity while consisting of different strains. In conclusion, some minimal model communities can have higher anti-listerial effectiveness than individual strains or the initial 89 micro-organisms from smear. Thus, microbial interactions are involved in the production and modulation of anti-listerial signals in cheese surface communities., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Chick poisoning induced by oral administration of toxic fish tissues or extracts gave rise to internal hypersalivation, decrease in weight and acute motor ataxia. Detoxification was low and repeated administration therefore led to toxin accumulation. Response of the chicken to liver feeding was roughly quantitative; so liver, which is the most potential toxic tissue, may be used for a preventive screening test in ciguatera-endemic areas.

Ciguatera toxins were extracted from the tissues of 36 poisonous fishes including 9 dangerous species collected in the Caribbean. Toxicity assays were carried out in mice and the distinctive symptoms of ciguatera poisoning were observed. In a single fish, ciguatoxin was found in the blood, flesh, gonads, gills, heart, skin and bones. The concentration was highest in the viscera and in particular in the liver, kidney and spleen. The ratios of the toxin concentrations of the liver or viscera to that of the flesh were high and varied with the species suggesting that the toxin is stored in different ways in different fish. Subcellular fractionation of liver cells revealed that most of the ciguatoxin was attached to cytoplasmic proteins and that some toxin was probably bound to the membranes.