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Air pollution modulates artherosclerosis progression

MD-FM Thursday April 25th, 2013



 

GENERIQUE


Sarah:

MD FM, Medical News from around the world with Peter Goodwin.


P1
PETER:

Hello, and with me is Sarah Maxwell. To begin with: exposure to higher concentrations of particulate air pollution can increase the build-up of atherosclerosis, according to a study published in PLoS Medicine

 
SARAH:
Yes, nearly 6000 people in the Multi-Ethnic Study of Atherosclerosis, MESA, had one ultrasound examination at study entry and another about two and a half years later, and levels of fine particulate matter from each persons’ neighborhood was also estimated. There were greater intima-medial thickness progressions, a known indicator of atherosclerosis, in the carotid arteries of people from the same metropolitan area, exposed to higher, long-term concentrations of pollution

 
Adar-1: We found that living in an area with high air pollution increased the rate at which these folks developed atherosclerosis over time, and we also saw that people who experienced larger reductions in air pollution concentrations over time experienced slower rates of progression of atherosclerosis

 
SARAH:
That was lead study author Sara Adar, from the University of Michigan, who said it’s long been suspected that air pollution might cause heart disease, in part through this build up of atherosclerosis. The final results of the MESA study will be reported after 10-years follow up, but in the meantime:


Adar-2: I would say that this gives us stronger evidence that we should inform our patients about risks of air pollution and perhaps advise those who have illnesses like COPD or heart disease that staying indoors or using some kind of protection on higher pollution days might be in their best interest


SARAH:
Sara Adar, from Ann Arbor, Michigan.


VIRGULE MUSICALE

 
P2
PETER:
For patients at high cardiac risk, being on a beta-blocker at the time of non-cardiac, non-vascular surgery cuts their risk of dying, according to a large observational study

 
SARAH:
Yes, and these data, published in the New England Journal of Medicine, support the current treatment guidelines for patients who have some of the six revised cardiac risk index factors, such as : a history of stoke, diabetes, known heart disease or kidney problems


London-1: We found that, overall, if you didn’t have any of these revised cardiac risk index factors there appeared to be no difference in your outcome. If you did have two or more of those risk factors, then we found a statistically significant difference, suggesting that the beta-blocker was beneficial in those patients at reducing the 30-day mortality and 30-day incidence of heart attack or cardiac arrest


SARAH:
That was lead study author Dr. Martin London from the University of California in San Francisco.


PETER:
Hmmm, interesting, because although beta blockers have been used perioperatively in high-risk patients for a long time, their effectiveness and safety have been questioned recently by a few studies, even suggesting they were actually associated with a higher rate of death overall, weren’t they. And this put a bit of a damper on using them?


SARAH:
It did, but Dr. London and the team collected samples from nearly 140,000 patients, and their data support current guidelines in favor of using beta blockade. However, more research is needed:
 

London-2: My data do not give exact parameters on how much should be used, how long should it be used, how you should give it, there are a lot of questions that my data do not answer. My data were kind of a look from 100 miles up in the sky to see down on the entire United States. To get down to the lower level, to the patient level exactly, you really need to do these randomized controlled trials, particularly in the patients with maybe one or two risk factors and try and really elucidate what’s going on to prove this conclusively

 
SARAH:
Dr. Martin London, from California.


P3
PETER:
For children and adolescents infected with HIV, prolonged exposure to highly active antiretroviral therapies, HAART, appears to be cardio-protective, rather than impairing heart function. These are the results of a study, published in JAMA Pediatrics, looking at children from 14 pediatric HIV clinics in the United States. They found, “z-scores” for left ventricular fractional shortening, a measure of cardiac function, were significantly lower in HIV infected children, than historical controls, not exposed to HAART than those on therapy.
 

VIRGULE MUSICALE


P4
PETER:
A study in the New England Jounal of Medicine reports a biochemical pathway linking diet, human and gut microbial metabolism, and atherogenesis.


SARAH:
Yes, researchers showed that dietary choline (found in eggs for instance) once ingested by humans, is metabolized by gut bacteria, which release a compound ultimately detected in our blood called TMAO. This is believed to promote atherogenesis in part by promoting the formation of foam cells from macrophages. The research team examined the relationship between plasma TMAO levels and incident cardiovascular events in 4000 participants.


Hazen: Blood levels of TMAO were a very strong and independent predictor of future major adverse cardiac events and this was true both in primary prevention –meaning subjects who had no known coronary artery disease, as well as secondary prevention, people with existing coronary diseases

 
SARAH:
That was Dr. Stanley Hazen, from Cleveland, Ohio, lead author of the study. He said this raises the possibility that atherothrombogenesis could be attenuated by a variety of new strategies:


Hazen : We think that in the future, blood testing for TMAO may prove to be a very strong way of helping to further identify people who are at risk and to help better individualize or tailor dietary recommendations to the individual. The real thing we want to do is try to develop a therapy based on this information. I do not think that chronic antibiotic is going to be the way to do it –microbes develop tolerance over time. In think instead, the major therapies that will arise will be either in the form of specific drugs that inhibit a given pathway in the microbe but don’t kill it, or the use of probiotics or prebiotics


SARAH:
Stanley Hazen, from the Cleveland Clinic in Ohio.


VIRGULE MUSICALE


P5
PETER:
In older people, serum vitamin-D deficiency can predict the incidence or worsening of knee and hip pain over five years, according to findings reported in the Annals of the Rheumatic Diseases

 
SARAH:
Yes, 800 adults, randomly selected from the community, aged 50 to 80, answered questionnaires on pain and had their vitamin-D levels assessed using radioimmunoassay. Vitamin-D below 25 nmol per litre predicted change in knee pain over five years and worsening of hip pain over two and a half years. However, results in hips were not as consistent as findings in knee pain. Lead study author, Laura Laslett


Laslett-1: We’ve seen an association between low vitamin D levels and change in pain and so we think that, because we’ve looked at it prospectively, so, over time, that we can actually make some inferences about cause and effect
 

SARAH:
That was Dr Laura Laslett, from the University of Tasmania in Australia, who said possible mechanisms for this association include: inflammation in the synovial fluid of the joint, osteomalacia or secondary hyper-parathyroidism from the low levels of vitamin-D. And randomized trials are needed before any recommendations can be made:


Laslett-2: This data is not sufficient for us to be suggesting to people that they go out and have their vitamin D levels tested and to go on treatment


SARAH:
Laura Laslett, from Tasmania, whose team is currently testing the long-term effects of vitamin-D supplementation on joint pain in individuals with normal and moderately low vitamin D levels.
 

BREVE 1 Sur fond musical


PETER:
Finally, in brief:

For women younger than 50 having a hysterectomy, who’ve never used estrogen therapy, bilateral oophorectomy was associated with significantly increased mortality rates compared to ovarian conservation. This was in a study published in the journal Obstetrics and Gynecology. A survival difference has not previously been observed in studies of hormone therapy, but these data found at no age was oophorectomy associated with increased survival.


And …..


BREVE 2
For adolescents with early-stage Hodgkin’s lymphoma in complete remission following chemotherapy, radiotherapy can be omitted from treatment. These are final results of a study, published in the Journal of Clinical Oncology, showing that reducing the radiation dose from 25 to 20 Gray in patients with incomplete remission following chemotherapy, didn’t increase failure rate.

 
That's all from MDFM for now. Sarah Maxwell and I will be back with more next week, so until then from me Peter Goodwin, goodbye!

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