Association between the Diabetes Drug Cost and Cardiovascular Events and Death in Korea: A National Health Insurance Service Database Analysis.

BACKGRUOUND: This study aimed to investigate the long-term effects of diabetes drug costs on cardiovascular (CV) events and death. METHODS: This retrospective observational study used data from 2009 to 2018 from the National Health Insurance in Korea. Among the patients with type 2 diabetes, those taking antidiabetic drugs and who did not have CV events until 2009 were included. Patients were divided into quartiles (Q1 [lowest]-4 [highest]) according to the 2009 diabetes drug cost. In addition, the 10-year incidences of CV events (non-fatal myocardial infarction, stroke, hospitalization for heart failure, and coronary revascularization) and CV death (death due to CV events) were analyzed. RESULTS: A total of 441,914 participants were enrolled (median age, 60 years; men, 57%). CV events and death occurred in 28.1% and 8.36% of the patients, respectively. The 10-year incidences of CV events and deaths increased from Q1 to 4. After adjusting for sex, age, income, type of diabetes drugs, comorbidities, and smoking and drinking status, the risk of CV events significantly increased according to the sequential order of the cost quartiles. In contrast, the risk of CV death showed a U-shaped pattern, which was the lowest in Q3 (hazard ratio [HR], 0.953; 95% confidence interval [CI], 0.913 to 0.995) and the highest in Q4 (HR, 1.266; 95% CI, 1.213 to 1.321). CONCLUSION: Diabetes drug expenditure affects 10-year CV events and mortality. Therefore, affording an appropriate diabetes drug cost at a similar risk of CV is an independent protective factor against CV death.

Vascular smooth muscle dysfunction and remodeling induced by ginsenoside Rg3, a bioactive component of ginseng.

Ginseng, one of most well-known herbal medicines, is widely and indiscreetly used among the patients with cardiovascular disorders, raising concern over abuse of this medicine and unwanted effects. In this study, we investigated the effects of ginsenoside Rg3 (Rg3), an active ingredient of ginseng, on vascular contractility and structural integrity to explore its potential vascular toxicity. In isolated rat aorta, Rg3 suppressed the normal agonist-induced contractile response. This suppression persisted even after a rigorous washout. In the endothelium-denuded aortic ring, impairment of vascular contractility by Rg3 was retained, suggesting that vascular smooth muscle was affected. In primary vascular smooth muscle cells, Rg3 abolished agonist-induced Ca(2+) increase, indicating that Ca(2+) regulation was disrupted. Rg3 suppressed the contraction induced by Bay K8644, an L-type Ca(2+) channel activator, whereas store-operated Ca(2+) channel or intracellular Ca(2+) store-mediated contraction was not affected, suggesting that the L-type Ca(2+) channel was selectively impaired by Rg3. These in vitro results were further confirmed in vivo where Rg3 treatment significantly attenuated the agonist-induced pressor response. More importantly, 4-week repeated treatment with Rg3 in normal animals induced eutrophic outward remodeling in the thoracic aorta, that is, it brought about an increased luminal area without changes in the wall area. These results suggest that Rg3 can induce the vascular smooth muscle dysfunction by disturbing Ca(2+) influx from the L-type Ca(2+) channel, ultimately leading to impaired vascular contractility and structural remodeling.

Low-level mercury can enhance procoagulant activity of erythrocytes: a new contributing factor for mercury-related thrombotic disease.

BACKGROUND: Associations between cardiovascular diseases and mercury have been frequently described, but underlying mechanisms are poorly understood. OBJECTIVES: We investigate the procoagulant activation of erythrocytes, an important contributor to thrombosis, by low-level mercury to explore the roles of erythrocytes in mercury-related cardiovascular diseases. METHODS: We used freshly isolated human erythrocytes and ex vivo and in vivo thrombosis models in rats to investigate mercury-induced procoagulant activity. RESULTS: Prolonged exposure to low-dose mercuric ion (Hg(2+); 0.25-5 microM for 1-48 hr) induced erythrocyte shape changes from discocytes to echinocytes to spherocytes, accompanied by microvesicle (MV) generation. These MVs and remnant erythrocytes expressed phosphatidylserine (PS), an important mediator of procoagulant activation. Hg(2+) inhibited flippase, an enzyme that recovers PS into the inner leaflet of the cell membrane, and activated scramblase, an enzyme that alters lipid asymmetry in the cell membrane. Consistent with these activity changes, Hg(2+) increased intracellular calcium and depleted ATP and protein thiol. A thiol supplement reversed Hg(2+)-induced MV generation and PS exposure and inhibited the increase in calcium ion (Ca(2+)) and depletion of ATP, indicating that free-thiol depletion was critical to Hg(2+)-mediated procoagulant activity. The procoagulant activity of Hg(2+)-treated erythrocytes was demonstrated by increased thrombin generation and endothelial cell adhesion. We further confirmed Hg(2+)-mediated procoagulant activation of erythrocytes in ex vivo and in vivo rat thrombosis models, where Hg(2+) treatment (0.5-2.5 mg/kg) increased PS exposure and thrombus formation significantly. CONCLUSION: This study demonstrated that mercury could provoke procoagulant activity in erythrocytes through protein-thiol depletion-mediated PS exposure and MV generation, ultimately leading to enhanced thrombosis.

U-shaped dose response in vasomotor tone: a mixed result of heterogenic response of multiple cells to xenobiotics.

U-shaped response has been frequently encountered in various biological areas including epidemiology, toxicology, and oncology. Despite its frequent observation, the theory of U-shaped response has been crippled by the lack of a robust mechanism underlying and incomplete in vitro and in vivo correlation. In the present study, a novel mechanism is provided for a U-shaped response, based on the findings of agonist-induced vasomotor tone change affected by menadione (MEN) (synthetic vitamin K(3)), a reactive oxygen species generator, and arsenic, an environmental pollutant, which showed typical U-shaped responses in both in vitro aortic contractile response and in vivo blood pressure. U-shaped responses by MEN and arsenic were a combined result from heterogenic susceptibilities and responses of multiple target cells composing blood vessels, that is, endothelium and smooth muscle. Notably, endothelium, a regulator of vasomotor tone, was primarily affected by low-dose stimuli, whereas smooth muscle, an effector of vascular contraction, was affected later by high-dose. The dysfunction of smooth muscle was produced by high-dose MEN-induced hydrogen peroxide, resulting in the attenuation of vascular contractile reactivity, whereas low-dose MEN-induced superoxide led to the quenching of vasodilatory nitric oxide in endothelial cells, resulting in the enhancement of vasoconstriction. This mechanistic theory, the difference in susceptibilities and responses to a common stimulus between regulator and effector components of a system, could give a new insight into the explanation of various U-shaped responses and provide a new evidence for the need of the risk assessment of toxicants with a wider dose range.

Antithrombotic activity of LB30057, a newly synthesized direct thrombin inhibitor.

An amidrazonophenylalanine derivative, LB30057, inhibits the catalytic activity of thrombin potently by interaction with the active site of thrombin, and has high water solubility. In the present study, we evaluated the effect of LB30057 on the biological activities of thrombin at various tissues, and determined whether thrombin inhibition by LB30057 could reduce the incidence of occlusive thrombosis in an in vivo animal model. Treatment with LB30057 to human plasma prolonged clotting times in a concentration-dependent manner. LB30057 suppressed significantly thrombin-induced phosphatidylserine (PS) exposure in platelets, suggesting that LB30057 could inhibit blood coagulation accelerated by PS exposure. In human platelets, soluble thrombin- and clot-induced platelet aggregation was inhibited by LB30057 potently. Consistent with this finding, LB30057 showed concentration-dependent inhibitory effects on serotonin secretion and P-selectin expression induced by thrombin in platelets. In the blood vessel isolated from the guinea pig, treatment with LB30057 resulted in a concentration-dependent inhibition of thrombin-induced vascular contraction. In vivo study revealed that LB30057 following oral administration significantly increased the time to occlusion and improved carotid arterial patency using rat carotid artery thrombosis model. All these results suggest that LB30057 is a potent inhibitor of biological activities of thrombin at various target tissues and, therefore, might be developed as an antithrombotic agent for treatment and prevention of thrombotic diseases.