Biomedical subjects

Dat Do

Publications and source records attributed to Dat Do.

7 recordsLinked to original sources

PubMed2007

Statin therapy in cardiovascular diseases other than atherosclerosis.

Statins are drugs that inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, thereby blocking the synthesis of cholesterol. Since being discovered in Japan in the mid 1970s, statins have been widely used to lower low-density lipoprotein cholesterol. However, analysis of cardiovascular research has revealed other important effects beyond changes in lipid parameters, referred to as pleiotropic effects. This paper focuses on the effects of statins as anti-ischemic agents with improvement in endothelial function, along with studies on valvular aortic stenosis, atrial fibrillation, heart failure, peripheral arterial disease, and cancer. As the evolution of statin research continues, there appear to be new potential benefits from statins to be found in many facets of cardiovascular disease.

Atherosclerosis↗

PubMed2006

The good fat hormone: adiponectin and cardiovascular disease.

New treatments for heart disease continue to be of paramount importance. The newest pandemic facing us is the rise of obesity and diabetes. One new area of research in the field of metabolism is the hormone adiponectin, which is secreted by fat cells. For the most part, this compound seems more likely to be a part of basic science-oriented research; however, it deserves a much closer look. Many compounds such as high-density lipoprotein and others at first were simply markers of disease but later found to be much more important. During this short review, research from basic science to clinical cardiovascular events is discussed in relation to adiponectin.

Adipocytes↗

PubMed2003

Dicationic electrophiles from olefinic amines in superacid.

This paper describes the superacid-catalyzed chemistry of olefinic amines and related compounds. A variety of olefinic amines are found to react with benzene in CF(3)SO(3)H (triflic acid) to give addition products in good yields (75-99%), including the pharmaceutical agents fenpiprane and prozapine. A general mechanism is proposed that invokes the formation of reactive, dicationic electrophiles and the direct observation of a diprotonated species is reported from low-temperature NMR experiments. This chemistry is also used to conveniently prepare functionalized polystyrene beads having pendant amine groups.

Journal Article↗

PubMed2002

The prognostic value of exercise testing in elderly men.

PURPOSE: Our purposes were to compare the responses to exercise testing in elderly (> or =65 years of age) and younger men, and to investigate whether exercise testing has similar prognostic value in the two age groups. METHODS: We included all elderly (n = 1185) and younger (n = 2789) male veterans without established coronary heart disease who underwent routine clinical exercise testing between 1987 and 2000 at two academically affiliated Veteran's Affairs medical center laboratories. Measurements included a standardized medical history, exercise testing, and all-cause mortality. RESULTS: Compared with younger patients, elderly patients achieved a lower workload (a mean [+/- SD] of 7 +/- 3 vs. 10 +/- 4 metabolic equivalents [METs], P <0.001) and were more likely to have abnormal ST depression (27% [n = 324] vs. 16% [n = 436], P <0.001). During the mean follow-up of 6 years, annual mortality was twice as high among elderly patients as among younger patients (4% vs. 2%, P <0.001). The only exercise test variable that was associated significantly with time to death in both age groups was maximal METs achieved: each 1 MET increase in exercise capacity was associated with an 11% reduction in annual mortality. Exercise-induced ST depression was more common in those who subsequently died, but was not an independent predictor of mortality. CONCLUSION: In elderly men, exercise testing provided prognostic information incremental to clinical data. Achieved workload (in METs) was the major exercise testing variable associated with all-cause mortality. Its prognostic importance was the same in elderly as in younger men.

Age Factors↗

PubMed2002

Exercise capacity and mortality among men referred for exercise testing.

BACKGROUND: Exercise capacity is known to be an important prognostic factor in patients with cardiovascular disease, but it is uncertain whether it predicts mortality equally well among healthy persons. There is also uncertainty regarding the predictive power of exercise capacity relative to other clinical and exercise-test variables. METHODS: We studied a total of 6213 consecutive men referred for treadmill exercise testing for clinical reasons during a mean (+/-SD) of 6.2+/-3.7 years of follow-up. Subjects were classified into two groups: 3679 had an abnormal exercise-test result or a history of cardiovascular disease, or both, and 2534 had a normal exercise-test result and no history of cardiovascular disease. Overall mortality was the end point. RESULTS: There were a total of 1256 deaths during the follow-up period, resulting in an average annual mortality of 2.6 percent. Men who died were older than those who survived and had a lower maximal heart rate, lower maximal systolic and diastolic blood pressure, and lower exercise capacity. After adjustment for age, the peak exercise capacity measured in metabolic equivalents (MET) was the strongest predictor of the risk of death among both normal subjects and those with cardiovascular disease. Absolute peak exercise capacity was a stronger predictor of the risk of death than the percentage of the age-predicted value achieved, and there was no interaction between the use or nonuse of beta-blockade and the predictive power of exercise capacity. Each 1-MET increase in exercise capacity conferred a 12 percent improvement in survival. CONCLUSIONS: Exercise capacity is a more powerful predictor of mortality among men than other established risk factors for cardiovascular disease.

Adrenergic beta-Antagonists↗

PubMed2002

Comparison of treadmill scores with physician estimates of diagnosis and prognosis in patients with coronary artery disease.

OBJECTIVE: Our purpose was to compare exercise test scores and ST measurements with a physician's estimation of the probability of the presence and severity of angiographic disease and the risk of death. The American College of Cardiology/American Heart Association exercise testing guidelines provide equations to calculate treadmill scores and recommend their use to improve the predictive accuracy of the standard exercise test. However, if physicians can estimate the probability of coronary artery disease and prognosis as well as the scores, there is no reason to add this complexity to test interpretation. METHODS: A clinical exercise test was performed and an angiographic database was used to print patient summaries and treadmill reports. The clinical/treadmill test reports were sent to expert cardiologists and to 2 other groups, including randomly selected cardiologists and internists. They classified the patients summarized in the reports as having a high, low, or intermediate probability for the presence of any severe angiographic disease and estimated a numerical probability from 0% to 100%. The Social Security Death Index was used to determine survival status of the patients. RESULTS: Twenty-six percent of the patients had severe angiographic disease, and the annual mortality rate for the population was 2%. Forty-five expert cardiologists returned estimates on 473 patients, 37 randomly chosen practicing cardiologists returned estimates on 202 patients, 29 randomly chosen practicing internists returned estimates on 162 patients, 13 academic cardiologists returned estimates on 145 patients, and 27 academic internists returned estimates on 272 patients. When probability estimates for presence and severity of angiographic disease were compared, in general, the treadmill scores were superior to physicians' and ST analysis at predicting severe angiographic disease. When prognosis was estimated, treadmill prognostic scores did as well as expert cardiologists and better than most other physician groups. CONCLUSION: Estimates of the presence of clinically significant and severe angiographic coronary artery disease provided by scores were superior to physician estimates and ST analysis alone. Estimates of prognosis provided by scores were similar to the estimates made by expert cardiologists and more accurate than the estimates made by most other physician groups.

Clinical Competence↗

PubMed2002

What percent luminal stenosis should be used to define angiographic coronary artery disease for noninvasive test evaluation?

BACKGROUND: There has been controversy over what is the best angiographic luminal dimension criterion associated with ischemia for evaluating diagnostic tests. If one assumes that ST-segment depression or scores are indicators of ischemia, then whatever angiographic criteria best discriminates those with ischemic and nonischemic responses would be the best angiographic marker for ischemia. To study this, we calculated the area under the ROC curves for ST depression and scores at different angiographic cut-points in order to determine the best angiographic cut-point for defining ischemia-producing coronary disease. METHODS: Twelve hundred and seventy-six consecutive males without prior MI with a mean age of 59 +/- 11 years who had undergone exercise testing and coronary angiography were analyzed in this study. We calculated the number of patients of this population that would be considered to have coronary artery disease at different cut-points for angiographic luminal stenosis. For example, 59% of the patients had significant CAD when disease was defined as 50% or greater coronary lumen stenosis of any coronary vessel while 49% of the patients had significant CAD when disease was defined as 70% or greater coronary lumen stenosis. Cut-points were considered between 40 to 100% coronary lumen stenosis. ROC analysis was then performed comparing ST depression and treadmill scores at each of these cut-points. RESULTS: The cut-point for coronary lumen stenosis that returned the highest AUC for ST depression and scores was between 70 and 80% coronary luminal stenosis. However, the difference between the 50% and 75% luminal stenosis criteria was minimal. CONCLUSION: It appears that the best cut-point for defining significant angiographic disease when evaluating diagnostic tests of ischemia is 75% or greater coronary luminal stenosis.

Aged↗