want to understand: (1) how does the scientific process helps us solve health problems? (2) what are...
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Want to understand:
(1) How does the scientific process helps us solve health problems?
(2) What are aflatoxins? Are they relevant to human and animal health?
(3) How do organisms’ interactions with each other and their environment influence disease?
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http://www.oardc.ohio-state.edu/ohiofieldcropdisease/Mycotoxins/aspergillus1.jpg
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4 spp. shown to produce toxins:
A. flavus
A. parasiticus
A. nomius
A. niger
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4 major aflatoxins
M22
metabolic products
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Aflatoxin distribution
•Exposure mainly from:– A. flavus: global distribution,
produces B classes of aflatoxins
– A. parasiticus: Africa and the Americas, produces B and G classes of aflatoxins
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Partial list of foods:• Cereals
– maize, sorghum, millet, rice, wheat
• Oil seeds – groundnut, soybean, sunflower,
cotton
• Tree nuts – pistachio, almond, walnut, coconut
• Spices – paprika, chile, black pepper,
coriander, turmeric, ginger
• Figs• Milk, cheese,
meat, eggs
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Pre-harvest risk factors:– High temperatures– Chronic drought– Heavy rains– Crop insect damage– Poor fertility– Weed competition– High crop densities
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Post-harvest risk factors:
–High temperatures
–Humidity
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Liver function
• One of the largest internal organs• Produces bile used to digest food • Metabolizes carbohydrates and lipids • Stores glycogen (for energy), key
nutrients• Breaks down toxic substances
http://digilander.libero.it/BodyMindCare/kapil/moremedi.htm
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Cytochrome P450 oxidase:• Found in high densities in liver• Oxidative enzymes that
modify and degrade toxins• Absorb light at 450 nm
http://www.biochem.ucl.ac.uk/bsm/proLig/pdbEntries/1pha/
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Bioactivation:• Enzymes can convert a chemical into
something even more reactive or toxic• Ex.: Ethanol via Alcohol dehydrogenase
Acetaldehyde
http://www.gps.caltech.edu/~fry/winter2003/winter2003.html
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Williams, J.H., T.D Phillips, P.E. Jolly, J.K Stiles and D. Agga. 2004. Human aflatoxicosis in developing countries: a review of toxicology, exposure, potential health consequences, and interventions. Am. J. Clin. Nutr.Nov;80(5):1106-1122.
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No aflatoxin
Highest dose
Rat livers
http://www.ansci.cornell.edu/plants/toxicagents/aflatoxin/image9.html
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Toxicology
• Acute aflatoxicosis– high dosage over short
time – hemorrhage– acute liver damage– edema– altered digestion,
absorption, and metabolism
– death
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Toxicology
• Chronic aflatoxicosis– impaired food
conversion– slower growth– immunity problems– cirrhosis– liver cancer
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Documented outbreaks
• 1974, rural NW India: 397 ill, 108 dead• High fever, jaundice, ascites• Preceded by same symptoms in dogs• Traced to maize w/ major A. flavus
infestation• Chronic drought, unseasonable rain,
poor storage, ignorance of dangers of moldy food
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Documented outbreaks• 1981, rural Kenya: 20
hospitalizations, 12 deaths• Abdominal discomfort, anorexia,
malaise, fever, jaundice, dark urine
• Doves died, then dogs ill, then people ill
• Contaminated maize• Heavy rains, drought, and
protein-deficient diets thought to contribute
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1) The scientific process is investigative and helps us solve health problems
(2) Aflatoxins are fungal toxins that pose serious risks to human and animal health
(3) Organisms’ interactions with each other and their environment determine whether or not disease outbreak occurs