Association between renal function and platelet reactivity during aspirin therapy in elderly patients with atherosclerotic cardiovascular disease

Hormones, age, and sex affect platelet responsiveness in vitro

BACKGROUND

Female sex confers a survival advantage following severe injury in the setting of trauma-induced coagulopathy, with female platelets having heightened responsiveness likely due to estrogen. The effects of testosterone on platelet biology are unknown, and platelets express both estradiol and androgen receptors on the plasma membrane. We hypothesize testosterone decreases platelet responses in vitro, and there are baseline differences in platelet function and metabolism stratified by sex/age.

STUDY DESIGN AND METHODS

Apheresis platelets were collected from: older males (OM) ≥45 years, younger males (YM) <45 years, older females (OF) ≥54 years, and younger females (YF) <54 years, and testosterone and estradiol were measured. Platelets were incubated with testosterone (5.31 ng/ml), estradiol (105 pg/ml) or vehicle and stimulated with buffer, adenosine diphosphate (20 μM), platelet activating factor (2 μM), or thrombin (0.3 U/ml). Aggregation, CD62P surface expression, fibrinogen receptor surface expression, and platelet mitochondrial metabolism were measured.

RESULTS

Testosterone significantly inhibited aggregation in OF and OM (p < .05), inhibited CD41a expression in YF, YM, and OM (p < .05), and affected a few of the baseline amounts of CD62P surface expression but not platelet activation to platelet-activating factor and adenosine diphosphate, and variably changed platelet metabolism.

DISCUSSION

Platelets have sex- and age-specific aggregation, receptor expression, and metabolism. Testosterone decreases platelet function dependent on the stimulus, age, and sex. Similarly, platelet metabolism has varying responses to sex hormones with baseline metabolic differences dependent upon sex and age.

Therapeutic potential of traditional Chinese medicine against atherosclerosis: Targeting trimethylamine N-oxide

BACKGROUND

Recent studies have shown that plasma trimethylamine-N-oxide (TMAO) level is highly correlated with the risk of atherosclerosis (AS), and the elevated level is significantly positively correlated with the incidence of AS.

PURPOSE

The purpose of this article is to offer a useful summary of the correlation between TMAO and AS, and the effect of herbal monomers, herbal extracts, and formulas on anti-atherosclerosis mediated by TMAO.

METHOD

The data contained in this article comes from PubMed, Web of Science, and China National Knowledge Infrastructure.

RESULTS

This review discusses the main mechanism of AS induced by TMAO, including endothelial dysfunction, macrophage foaming, platelet reactivity, and cholesterol metabolism, and summarizes 6 herb monomers, 5 herb extracts, and 2 formulas that have been tested for their anti-TMAO activity.

CONCLUSION

The current understanding of possible ways to reduce TMAO generation is discussed, with the effect and potential of herb monomers, herb extracts, and formulas highlighted.