Environmental toxins

Xem 1-20 trên 26 kết quả Environmental toxins
  • The importance of cyanobacterial toxins in drinking water sources has been highlighted by the adoption of a provisional drinking water “Guideline Value” for microcystin- LR, one of the most abundant toxins, by the World Health Organization (WHO). A number of nations have now legislated a guideline for microcystins into their drinking water regulations, with the consequent need for monitoring and analytical techniques. The Chemical Safety Committee of the WHO also has under consideration a Guideline Value for cylindrospermopsin, the other most damaging cyanobacterial toxin....

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  • Clostridium perfringense-toxin is produced by toxinotypes B and D strains. The toxin is the aetiological agent of dysentery in newborn lambs but is also associated with enteritis and enterotoxaemia in goats, calves and foals. It is considered to be a potential biowarfare or bioterrorism agent by the US Government Centers for Disease Control and Prevention.

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  • Pertussis toxin, produced and secreted by the whooping cough agent Bordetella pertussis, is one of the most complex soluble bacterial proteins. It is actively secreted through the B. pertussiscell envelope by the Ptl secretion system, a member of the widespread type IV secretion systems.

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  • The epsilon-toxin ofClostridium perfringensforms a heptamer in the mem-branes of Madin–Darby canine kidney cells, leading to cell death. Here, we report that it caused the vacuolation of Madin–Darby canine kidney cells. The toxin induced vacuolation in a dose-dependent and time-dependent manner.

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  • There are different glycosylated proteins in snake venoms, but no glycosylated representatives of a large family of three-fingered toxins have previously been detected. A new glycoprotein was isolated from the venom of the Thai cobra Naja kaouthia. MALDI MS of the glycoprotein contained an array of peaks in the range from 8900 to 9400 Da indicating its microheterogeneity. Carbohy-drate analysis showed the presence of mannose, galactose, N-acetylglucosamine, fucose and neuraminic acid.

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  • After creating toxic hazardous chemicals, society has followed an unsustainable course in using and disposing of toxins. More and more sites are being contaminated, cancer rates are rising, indoor air quality has declined to become often more contaminated than outdoor air, and toxic chemicals continue to be found in species as far away from civilization as the Arctic Circle. This chapter provides knowledge of hazardous chemicals: pollution and preventi.

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  • We all know only too well that our way of life, the food we eat, smoking, stress or environmental toxins infl uence our health. But we have just started to learn how these environmental factors cooperate with our hereditary genetic dispositions to determine health or the development of diseases. Moreover, we did not know until recently that all these factors may also infl uence the health of our children and grandchildren to whom we may transmit functional changes of our genes.

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  • This book aspires to be a comprehensive summary of current biofuels issues and thereby contribute to the understanding of this important topic. Readers will find themes including biofuels development efforts, their implications for the food industry, current and future biofuels crops, the successful Brazilian ethanol program, insights of the first, second, third and fourth biofuel generations, advanced biofuel production techniques, related waste treatment, emissions and environmental impacts, water consumption, produced allergens and toxins....

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  • Much of the convenience of modern life resides in sheet metal, the cowling shield of most machines and appliances. However, the load that this takes off human shoulders has to be carried elsewhere, and the Earth has borne the burden. Many of us woke up to the environmental cost when over a century of industrialization finally surpassed the capacity of nature to assimilate it. International in scope, Heavy Metals in the Environment: Using Wetlands for Their Removal discusses wetland functions and heavy metal contamination.

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  • There is a commonly held myth in our society that anything that is “natural” is good, wholesome, and healthful, whereas anything that is “synthetic” is bad, toxic, and harmful. The mere mention of the word chemical is enough to strike terror into the heart of any food faddist. This attitude is, at best, naïve and, at worst, dangerous.

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  • Environmental toxins, including exposure to lead, pesticides, and other chemicals, unquestionably affect fertility in men and women. Researchers have documented many examples, the strongest cases involving industrial and occupational exposures. These usually involve small numbers of people exposed to high levels of contamination.

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  • Asperger Syndrome (AS) has, as Dr. Suzanne Lawton so correctly reminds the reader, baffled Dr. Hans Asperger and baffles parents, children, physicians, and other health care practitioners, researchers, and others to this day. We cannot seem to agree on the cause or even, universally, on the diagnosis, much less the treatment. Auditoriums full of angry, impassioned, sometimes desperate, parents have gathered to berate the apparent lack of concern on the part of governmental institutions regarding mercury-laden vaccine preservatives.

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  • The discussion below describes the physical effects of key air pollutants on human health. This discussion is mostly based on Morgan and Jalaludin’s (2001) review. Where possible, sensitive subgroups in the population have been identified, including people with existing disease (mainly respiratory and cardiovascular), people with infections such as influenza and pneumonia, asthmatics, the elderly and children. Exposure-response estimates for the key pollutants are presented in Appendix 3.

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  • Both human activities and natural activities can change the physical, chemical, and biological characteristics of water, and will have specific ramifications for human and ecosystem health. Water quality is affected by changes in nutrients, sedimentation, temperature, pH, heavy metals, non-metallic toxins, persistent organics and pesticides, and biological factors, among many other factors (Carr and Neary 2008). Following are brief discussions of these major contaminants.

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  • Diverse human-produced organic chemicals can enter surface and groundwater through human activities, including pesticide use and industrial processes, and as breakdown products of other chemicals (Carr and Neary 2008). Many of these pollutants, including pesticides and other non-metallic toxins, are used globally, persist in the environment, and can be transported long ranges to regions where they have never been produced (UNEP 2009).

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  • Inorganic mercury is toxic when humans or wildlife are exposed to high levels for a short peri- od of time. Organic methylmercury has a greater tendency to accumulate in the body over time, eventually causing harm, even in small amounts. Methylmercury has the three properties that make substances particularly harmful to humans and other organisms — it persists, it bioaccumulates, and it is toxic to most life forms. The health effects of mercury are described in more detail in the next chapter of this primer.

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  • The Janus-faced atracotoxins are a unique family of excitatory peptide toxins that contain a rare vicinal disulfide bridge. Although lethal to a wide range of invertebrates, their molecular target has remained enigmatic for almost a decade.

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  • Because arsenic is the most prevalent environmental toxin, it is imperative that we understand the mechanisms of metalloid detoxification. In prokary-otes, arsenic detoxification is accomplished by chromosomal and plasmid-borne operon-encoded efflux systems.

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  • a-Conotoxins from marine snails are known to be selective and potent competitive antagonists of nicotinic acetylcholine receptors. Here we des-cribe the purification, structural features and activity of two novel toxins, SrIA and SrIB, isolated fromConus spuriuscollected in the Yucatan Chan-nel, Mexico.

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  • Rapid evolution driven by positive Darwinian selection appears in toxins of vipers, scorpions, and marine snails. Although the vast phylogenetic distan-ces between these animals suggest that this phenomenon is common, the recent release of the genome ofNematostella vectensis(Starlet anemone) as a collection of contigs portrays another extreme.

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