December 13, 2012
Zinc Can Be A Life-saver For Victims Of Lethal Box Jellyfish Stings
Brett Smith for redOrbit.com - Your Universe Online
Box jellyfish are known to lurk in the waters off the coast of Hawaii and a pair of researchers from the island state have found a treatment that takes some of the sting out of the invertebrate´s deadly venom, according to their study in the open access journal PLOS ONE.Angel Yanagihara and Ralph Shohet from the University of Hawaii have shown that zinc can mitigate the effects of the jellyfish´s venom, which act on a victim by quickly perforating the membranes of red blood cells.
In the study, the biologists wrote that they were inspired to use zinc gluconate as a potential treatment because of previous research that had shown both zinc and gluconate were used to prevent the cell-perforating activity of certain bacteria.
"For over 60 years researchers have sought to understand the horrifying speed and potency of the venom of the Australian box jellyfish, arguably the most venomous animal in the world,” Yanagihara said. “We have found that a previously disregarded hemolysin can cause an avalanche of reactions in cells. This includes an almost instantaneous, massive release of potassium that can cause acute cardiovascular collapse and death."
After the cells have been perforated, they begin to leak potassium into the body´s blood vessels. The heightened concentration of potassium in the blood, called hyperkalemia, causes abnormal heart rhythms and eventually cardiac arrest within five minutes.
In their study, the Hawaiian researchers developed a new method to extract venom from the jellyfish they had “recovered from beachside”. They found this method to return a much higher yield of venom than previously published methods.
The biologists then assayed the venom´s effect on red blood cells taken from human donors using an existing anti-venom and zinc gluconate. Over a range of venom concentrations, tolerable levels of zinc gluconate showed greater inhibition of cell perforation than even the highest levels of anti-venom. Zinc gluconate also inhibited the release of potassium better than the anti-venom, according to the study.
To test if a zinc treatment could increase the survivability of a venom exposure, the scientists injected a range of doses into the tail veins of mice, including some that were given zinc gluconate. Mice that received a zinc treatment more than doubled their average survival time.
The researchers were unsure of the precise mechanism that drove the beneficial results of zinc treatments, and suggested that future studies could investigate combinatorial approaches using both anti-venom and zinc compounds.
“If terminal cardiac events could be delayed in human sting victims, this might provide the opportunity for resuscitative measures that would lower potassium and prevent death,” the scientists wrote in their report. “Larger doses of zinc gluconate, or sustained treatment, might be even more effective, for example with a continuous intravenous delivery of zinc ions.”
“It is conceivable that topical application of zinc compounds, by inhibiting some of the toxin at the dermal interface, could ameliorate the morbidity of these stings as well,” they continued. “Further studies are warranted to recapitulate these findings in larger animals with cardiovascular physiology (and electrophysiology) closer to humans (such as pigs). Zinc compounds, which are inexpensive, stable and non-toxic at the required dose, could become a useful clinical treatment for potentially lethal (jellyfish) stings.”