- A tan bug, a deadly disease, jungle plants, and outer
space. The makings of a science fiction thriller? No. Science reality in
a search to stop a killer.
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- In Central and South America Chagas Disease is a bigger
threat than AIDS. It infects an estimated 18 million people in Latin America
and kills 20,000 every year. And with cases now showing up in other parts
of the world, passed through blood transfusions, it isn't a disease of
just the Latin peasant anymore.
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- The inch-long insect responsible for transmitting Chagas
is called the Kissing Bug in Central America. South Americans use the name
Vinchuca. To scientists it is Triatoma dimidiata. It is a common, secretive
rain forest bug that lives in the trees, biting birds and jungle animals.
As humans continue to cut down the forest, it is losing its natural home.
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- The Kissing Bug adapts well to substitute accommodations,
finding suitable hiding places in the cracks and crevices of typical peasant
dwellings around the rain forests. This nocturnal nemesis is an innocuous-looking
insect that sucks blood, much like a mosquito does. Its habit of defecating
and urinating immediately after eating, provides the Chagas parasite, which
lives in the bug's feces, ready access to the prospective host's blood
stream.
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- An Ancient Malady
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- Although first discovered in 1910 by a Brazilian doctor,
anthropologists have since identified evidence of its existence in Peruvian
mummies. As studies have continued, some alarming numbers concerning its
range have come to light. The disease manifests itself from southern Texas
all the way down through Central and South America. Data details cases
in all but the heart of the Amazon. According to Boletín Chileno
de Parasitología, 1989, percentages of infected people living in
areas where the Chagas parasite is found range from 3% in Uruguay and 11%
in Costa Rica, to 33% in Colombia and over 50% in areas of Bolivia.
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- The variants of Chagas, which can remain dormant or semidormant
and undetected in the host for 20 years, attack the human body in three
principal ways. In Costa Rica and most of Central America the parasite
usually lodges in the heart muscle. When it becomes active, it begins eating
the muscle. The tissue eventually becomes so thin it simply bursts from
normal vascular pressure. It is believed that in regions where the bug
lives, many of what are diagnosed as heart attacks, especially in younger
people and among the poor, are the result of Chagas. More virulent strains
in South America attack the colon and esophagus. These latter manifestations,
paradoxically, have a better chance of diagnosis and can often be corrected
by surgery to remove the affected parts.
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- Doctor Bert Kohlmann, a professor at EARTH University
in Costa Rica and lead scientist in a collaborative project to develop
a medicinal treatment, said that the disease is now spreading far beyond
Latin America through blood donated by migrating Latin Americans who unknowingly
carry the parasite. At the present time only a few South American countries
screen donated blood for Chagas. North America and Europe do not check
for this parasite.
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- Back To The Jungle
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- EARTH University opened in 1989, with the mission of
providing a university-level education "in the agricultural sciences
and natural resources, contributing to the sustainable development of the
humid tropics." Realizing that their jungle laboratory might disappear
before they could fully understand it, they felt that an ambitious curriculum
of applied research would greatly benefit the university and its students.
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- Costa Rica's astronaut, Doctor Franklin Chang, an inspiration
to Costa Ricans for many years, offered to help EARTH. Through his contacts
at various institutions, a joint project team was formed to study medicinal
uses of tropical plants. Two universities in Chile which were part of the
team, Universidad de Santiago de Chile and Universidad Católica
del Norte in Antofagasta, had been working for years to develop a cure
for the deadly Chagas disease. This was a project that fit in with the
tenets of EARTH, so scientists at the university started collecting plants
from the tropical forests surrounding the campus and began their quest.
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- The parasite and its destructive ways are known. Finding
a safe way to block its action is the problem. The scientists and students
at EARTH discovered plant extracts that would block key enzymes in the
parasite. They needed to learn exactly which agent in the extracts worked
the magic and how.
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- Working with the Center of Macromolecular Crystallography
at the University of Alabama at Birmingham, the researchers were able to
grow crystals of the parasite enzymes and attempt to map their molecular
structures. But crystals grown on earth are very small and slightly misshapen
due to gravity. This hinders the process of learning precisely how molecules
fit together, necessary knowledge in understanding how the plant protein
blocks the parasite's enzyme. Franklin Chang proposed a solution.
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- Heading For Space
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- Crystals grown in the microgravity of space are much
larger and better formed than those grown on terra firma. According to
Doctor Kohlmann, these space crystals provide scientists with 40 percent
more useful information. Thanks again to Franklin Chang, the extracts collected
and processed in Costa Rica, highly purified in Chile and prepared in Alabama,
were to be carried into space on the space shuttle where crystals would
be grown.
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- In February, 1996, the first joint US-Latin America space
experiment flew aboard mission STS-76 on the space shuttle Columbia, as
part of the Commercial Protein Crystal Growth (CPCG) experiment. Scientists
needed to know if the material from the parasite would grow crystals in
space. The results were positive and a second batch of samples flew aboard
STS-77 in May of 1996.
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- Results of the May flight indicated that, although the
crystals grew well, more time in space was needed to have sufficiently
large samples for the process of x-ray mapping. The scientists, with the
help of Doctor Chang, are seeking permission to grow the crystals aboard
the MIR space station. If this effort succeeds, it will increase to four
the number of countries directly involved in the Chagas project.
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- Researchers hope that after crystals from the plant extracts
and the parasite enzyme are mapped, the mechanics of the molecules will
be understood well enough to develop a carrier that can successfully deliver
the medicine to a patient's body. The next step, which the researchers
hope to begin in 1997, will be the clinical studies.
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- An International Effort
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- There is little doubt in the minds of the men and women
working on this project that without the cooperation of five institutions
in three countries, and the enthusiastic aid of Doctor Franklin Chang,
this research would be taking many more years. Chagas is considered a poor
man's disease, afflicting farmers and peasants living in and around the
rain forests of the Americas. Because of the relatively small numbers involved,
big pharmaceutical corporations can't rationalize getting involved. International
volunteers from institutions with a more idealistic view are close to finding
a cure for a deadly disease by using an intelligent mix of down-to-earth
natural medicine and high-flying science.
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- Progress Update
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- Since this article was first published in September of
1996 research has increased in scope. After the World Bank declared Chagas
Disease the number one parasite problem in Latin America, efforts redoubled
to find a cure for this deadly malady. Project ChagaSpace, a cooperative
effort of universities and private organizations in seven countries, is
now working full time to identify an enzyme blocker that can be used to
kill the parasite. Along with the organizations mentioned above, the distinguished
participants in ChagaSpace include Universidad Nacional and InBio, both
in Costa Rica; Universidad Nacional Autónoma de Mexico; Universidad
de Sao Paulo in Brazil; Universidad de la República in Uraguay;
and Instituto Fatala Chaben in Buenos Aires.
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- The June, 1998 flight of the space shuttle Discovery
on mission STS-91 included another enzyme crystal growing experiment for
this group to study. And again in October, 1998, STS-95, the John Glenn
Discovery Mission also included another series of crystal growing experiments
related with the Chagas research.
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- http://www.cocori.com/library/eco/chagas.htm
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- Patricia A. Doyle, PhD
- Please visit my "Emerging Diseases" message
board at: http://www.clickitnews.com/ubbthreads/postlist.php?Cat=&Board=emergingdiseases
- Zhan le Devlesa tai sastimasa
- Go with God and in Good Health
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