A New Marker?
Circulating pregnancy-associated plasma protein A (PAPP-A) appears to be a novel predictor of future ischemic events as well as the need for percutaneous intervention or coronary artery bypass graft surgery in patients who have a suspected myocardial infarction but are negative for troponin, said Finnish researchers in this week’s issue of Circulation (Circulation. 2003;108:1924–1926).
The researchers, led by Juha Lund, MD, of the University Central Hospital in Turku, Finland, described PAPP-A as a marker of atherosclerotic plaque activity. It is also a zinc-binding matrix metalloproteinase. They studied 200 consecutive hospitalized acute coronary syndrome patients, 136 of whom were troponin negative for as long as 24 hours. They measured the new marker PAPP-A when the patients were admitted, between 6 and 12 hours after admission, and after the patients had been in the hospital a day.
During the 6 months that they were monitored, 26 (19.1%) of the troponin-negative patients died from cardiovascular disease, had a second myocardial infarction, or needed revascularization. The researchers found that elevated PAPP-A was an independent predictor of an adverse outcome.
A Source for C-Reactive Protein
Human coronary artery smooth muscle cells produced the most C-reactive protein when incubated with a combination of interleukin (IL)-1β and IL-6, said researchers from the University of Texas–M.D. Anderson Cancer Center, the UT Health Science Center at Houston, and the Texas Heart Institute at St Luke’s Episcopal Hospital in Houston.
Only modest amounts of C-reactive protein were produced when the cells were incubated in the presence of only one of the interleukins, said the researchers in a report in this week’s issue of Circulation (Circulation. 2003;108:1930–1932). When the cells were incubated with tumor necrosis factor-α or lipopolysaccharide, an increase in C-reactive protein similar to that produced by the IL-1 and IL-6 combination was seen.
However, when human umbilical vein endothelial cells were incubated with the same factors, no C-reactive protein increase was seen. The researchers concluded that human coronary artery smooth muscle cells could produce C-reactive protein in the presence of inflammatory cytokines, and this protein could participate in atherogenesis.
Large Lipoprotein Molecules and Longevity
People who have lived exceptionally long lives seem to have significantly larger particles of high-density lipoprotein and low-density lipoprotein, and they share this trait with their children, said researchers in a study in the October 15, 2003, issue of The Journal of the American Medical Association.
Researchers from Albert Einstein College of Medicine New York led by Nir Barzilai, MD, analyzed a variety of data from 213 Ashkenazi Jews with an average age of 98 years. Nearly half of the study group was more than 100 years old. A total of 216 of their children were also studied. Their average age was 68.
The study participants were matched against another group of Ashkenazi Jews and subjects in the Framingham Offspring Study. Their medical histories were evaluated and their weights taken. They were also given a physical examination. Blood samples were assessed for lipids and lipoprotein subclass levels, as well as for measurement of particle sizes by protein nuclear magnetic resonance. Samples were also genotyped. The scientists were looking for variations in the cholesteryl ester transfer protein gene involved in the regulation of lipoprotein and particle sizes.
In their article, the authors wrote, “This study demonstrates to our knowledge the first time that families with exceptional longevity have markedly larger particle sizes of HDL and LDL, which are largely independent of the absolute levels of lipoproteins and apolipoproteins. This particular phenotype is associated with a lower prevalence of hypertension and CVD [cardiovascular disease] and the metabolic syndrome in their offspring compared with appropriately age-matched control groups, supporting a functional role for lipoproteins in promoting survival to very old age. Further elucidation of the genetic and biological mechanisms that determine lipoprotein particle sizes may provide key insights into preventive and therapeutic interventions for several age-related diseases that impart significant morbidity and mortality to elderly individuals.”