X-Message-Number: 16175
From: "Jan Coetzee" <>
Subject: CO helps promote the clot-dissolving process
Date: Wed, 2 May 2001 16:42:38 -0400

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Toxic gas rejuvenates lungs

        
     

Washington - The old saying that what doesn't kill you makes you stronger may 
apply -in a way - to the toxic gas carbon monoxide. 


Long feared as a dangerous and often deadly part of pollution, inhaled carbon 
monoxide has been found to benefit mice with damaged lungs. 


The result could suggest new treatments for people following heart attack and 
stroke. But the toxic gas must be administered with care, and some question 
whether the benefits are enough to justify the potential danger. 


CO, a colourless, odourless component of industrial emissions, cigarette smoke 
and exhaust has long been known to be hazardous. It starves cells of oxygen by 
replacing oxygen molecules in the blood and, in sufficient concentrations, can 
be deadly. 

But at lower doses it may have therapeutic value, the new findings indicate. 


When mice with severe lung damage resulting from a cutoff of blood flow were 
given inhaled carbon monoxide, some 70 percent survived, compared to just 10 
percent of mice who didn't get the CO, according to a paper in the May issue of 
the journal Nature Medicine. 


When blood flow is cut off, clots form in small blood vessels around the site. 
CO helps promote the clot-dissolving process, allowing blood flow to be 
re-established, explained Dr David J. Pinsky of the Columbia University College 
of Physicians and Surgeons in New York, a member of the research team. 


If, after more testing, such a treatment could be used in humans, it would 
"likely be eminently practical and relatively inexpensive," Pinsky said. 


Scenarios in which low dose carbon monoxide may be tested might include lung 
transplantation, stroke, heart attack, severe bacterial infections or before 
surgery when there might be an interruption in blood flow, such as coronary 
artery bypass grafting, he added. 


He stressed the importance of a careful monitoring system to avoid giving toxic 
levels of this potent gas. 


Christoph Thiemermann of St Bartholomew's and the Royal London School of 
Medicine and Dentistry in London was more cautious. 


"These findings, however, do not suggest that we should rush to treat patients 
with acute lung injury with CO-inhalation therapy, as the dangers of 
CO-inhalation outweigh the benefits," Thiemermann said in a commentary 
accompanying Pinsky's paper. 


The body naturally produces some carbon monoxide and Pinsky conducted his 
experiment both in normal mice and in mice genetically engineered to lack their 
own CO. 


Following the lung damage, survival of the normal mice rose from 10 percent to 
70 percent with CO treatment. Inhalation improved survival in the genetically 
altered mice from zero to 50 percent. 


Pinsky explained that when a cutoff of blood triggers the clotting process, the 
body's own clot-dissolving machinery is suppressed by a natural protein called 
PAI-1. 


"Carbon monoxide significantly reduces the body's production of this suppressor 
protein, and therefore, promotes dissolution of the clot," he said. "This 
relieves the obstruction in small blood vessels and permits blood flow to be 
re-established to the organ." 


The body's own production of carbon monoxide probably evolved to protect the 
blood flow to vital organs, and providing extra carbon monoxide by inhalation 
seems to give an added boost, Pinsky said. 




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