Wednesday, February 1, 2017

Remarkable little medical mystery in the New York Times

Quite the fascinating story in the New York Times about lychee orchards and some sick children in India. 
Hypoglycin A
NEW DELHI — Three years ago, Dr. Rajesh Yadav, an investigator with the India Epidemic Intelligence Service, moved to the city of Muzaffarpur, the site of one of the country’s most mysterious outbreaks. And he waited. 
Every year in mid-May, as temperatures reached scorching heights, parents took children who had been healthy the night before to the hospital. The children awakened with a high-pitch cry in the early morning, many parents said. Then the youths began having seizures and slipping into comas. In about 40 percent of cases, they died. Every year in July, with the arrival of monsoon rains, the outbreak ended as suddenly as it began...
...A joint investigation by India’s National Center for Disease Control and the India office of the Centers for Disease Control and Prevention in Atlanta, published in the British medical journal The Lancet Global Health on Tuesday, has identified a surprising culprit: the lychee fruit itself, when eaten on an empty stomach by malnourished children. 
In 2015, as a result of the investigation, health officials began urging parents in the area to be sure to feed young children an evening meal and to limit their consumption of lychees (sometimes spelled litchi). In two seasons, the number of reported cases per year dropped to less than 50 from hundreds....
...It was in the fall of 2013, during a conference call with colleagues in Atlanta, that someone mentioned “Jamaican vomiting sickness,” an outbreak in the West Indies that for many decades caused brain swelling, convulsions and altered mental states in children. 
The outbreak turned out to be tied to hypoglycin, a toxin found in the ackee fruit that inhibits the body’s ability to synthesize glucose, leading to acute hypoglycemia, or low blood glucose levels. “It had been going on for a decade, if not a century, before people really figured out what it was,” Dr. Srikantiah said. “Now, the grandmothers and the mothers teach their kids, ‘Don’t eat the unripe ackee fruit.’ ”
By late 2014, laboratory tests confirmed that lychees also contain high levels of hypoglycin, as well as a similar toxin known as methylenecyclopropyl glycine, or MCPG....
Here's what Wikipedia has to say about MCPG toxicity mechanisms: 
MCPA is a potent inhibitor of acyl CoA dehydrogenase, thus preventing the metabolism of fatty acids. The intolerance to prolonged fasting is due to inability to switch from glucose to fatty acid oxidation, impaired ketogenesis. There is increased urinary excretion of dicarboxylic acids, due to omega oxidation that occurs in the endoplasmic reticulum.
Pretty great example how science and scientists can make the world better. Definitely worth the read. 

2 comments:

  1. by the way, related homopropargyl glycine, now popular due to click reaction, is also a remarkably toxic suicide substrate. Together with its hydroxy analog, it was recently identified as a causative toxin in fatal wild mushroom poisonings in China. It shows a degree of selectivity for heart muscle fatty acid metabolism - not a good thing.

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  2. As someone coming from India and but for the fact that the CDC of the USA was taken into confidence, this issue would have remained unsolved! In these days of hyper discussion about closing of this government agencies or that it stands to reason that lot of good comes from the US! Not Russia or China.

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