Pharmacokinetic and pharmacodynamic modeling of the antiplatelet and cardiovascular effects of cilostazol in healthy humans

OBJECTIVE: Cilostazol is an antiplatelet agent with vasodilating properties. It has been used to treat patients with peripheral ischemia, such as intermittent claudication. We used a pharmacokinetic-pharmacodynamic model to analyze the relation between the plasma concentration of cilostazol, the inhibitory effect of the drug on platelet aggregation, and the cardiovascular effects of the drug on healthy humans. METHODS: A single oral dose of 100 mg cilostazol was administered to 20 healthy volunteers. Serial blood sampling and pharmacodynamic measurements were performed up to 48 hours thereafter. The effects of cilostazol on platelet aggregation, blood pressure, and heart rate were measured during the same period. The plasma concentration of cilostazol was measured with a validated HPLC method that entailed ultraviolet detection. The time courses of plasma cilostazol concentration, platelet aggregation, and cardiovascular effects were analyzed by means of pharmacokinetic-pharmacodynamic modeling with the program ADAPT II. RESULTS: The plasma concentration-time course followed a 2-compartment model. Mean peak concentration was 775 ng/ml approximately 3.65 hours after administration of cilostazol. The maximal effect on platelet aggregation was a 31.14% reduction 6.05 hours after administration. No significant difference in systolic blood pressure was found. The maximal increase in heart rate was 13.49%, whereas the maximal decrease in diastolic blood pressure was 29.51%. Both peak effects were detected approximately 6 hours after administration of the drug. Platelet aggregation and cardiovascular effects (change in diastolic blood pressure and heart rate) were analyzed with the effect-link sigmoid maximal effect model. CONCLUSION: This pharmacokinetic-pharmacodynamic model successfully described the relation between plasma concentration of cilostazol and the antiplatelet and cardiovascular effects of the drug.     

Relationship between antiapoptotic molecules and metastatic potency and the involvement of DNA-dependent protein kinase in the chemosensitization of metastatic human cancer cells by epidermal growth factor receptor blockade

The failure to treat metastatic cancer with multidrug resistance is a major problem for successful cancer therapy, and the molecular basis for the association of metastatic phenotype with resistance to therapy is still unclear. In this study, we revealed that various metastatic cancer cells showed consistently higher levels of antiapoptotic proteins, including Bcl-2, nuclear factor-kappaB, MDM2, DNA-dependent protein kinase (DNA-PK), and epidermal growth factor receptor (EGFR), and lower levels of proapoptotic proteins, including Bax and p53 than low metastatic parental cells. This was followed by chemo- and radioresistance in metastatic cancer cells compared with their parental cells. EGFR and DNA-PK activity, which are known to be associated with chemo- and radioresistance, were demonstrated to be mutually regulated by each other. Treatment with PKI166, an EGFR inhibitor, suppressed etoposide-induced activation of DNA-PK in A375SM metastatic melanoma cells. In addition, PKI166 enhanced markedly the chemosensitivities of metastatic cancer cell sublines to various anticancer drugs in comparison with those of low metastatic cancer cells. These results suggest that the activities of DNA-PK and EGFR, which is positively correlated with each other, may contribute to metastatic phenotype as well as therapy resistance, and the EGFR inhibitor enhances the effect of anticancer drugs against therapy-resistant metastatic cancer cells via suppression of stress responses, including activation of DNA-PK.     

Prostate cancer post-treatment follow-up and recurrence evaluation

Recurrent prostate cancer following primary treatment is common, and the population of men with biochemical recurrence is complex. Conventional management of recurrent prostate cancer involves nontargeted and/or systemic therapies, without defining an individual patient’s specific disease. However, recent advances in imaging enable a shift in the management of recurrent prostate cancer to targeted, patient-specific approaches. Specifically, MRI can detect and define local prostate cancer recurrence early in the course of disease, and prostate-specific PET imaging greatly improves nodal staging and can detect previously unknown distant metastases. The significant advances in the imaging of both local and distant tumor recurrences allows for specific selection of treatment options tailored to patients and their disease with less associated morbidity.     

Incidence and patterns of cardiomyopathy in carbon monoxide-poisoned patients with myocardial injury

Objectives: Sustained myocardial injury is a significant predictor of mortality in carbon monoxide (CO) poisoning. There are few reports in the literature regarding the presence of CO-induced cardiomyopathy from early stages in the emergency department (ED). We prospectively investigated the early incidence of CO-induced cardiomyopathy and its patterns in patients with cardiomyopathy. Materials and methods: During a 10-month period, transthoracic echocardiography (TTE) was performed in 43 consecutive patients with CO poisoning and myocardial injury, which was defined as elevated high-sensitive troponin I within 24?h after ED arrival. Measurements of left ventricular ejection fraction and wall motion abnormalities were performed to evaluate cardiac function. If a patient had CO-induced cardiomyopathy, we measured cardiac function at the time of patient admission, day 1, day 2, and once within seven days of hospitalization. Results: The incidence of cardiomyopathy was as high as 74.4% (32 of 43 patients) in CO-poisoned patients with myocardial injury based on initial ED results. Echocardiographic patterns included non-cardiomyopathy (25.6%), global dysfunction (51.2%), and Takotsubo-like cardiomyopathy (23.2%). Patients in the global dysfunction group had significantly more normalized cardiac dysfunction within 72?h than did those in the Takotsubo-like cardiomyopathy group (81.8% vs. 22.2%, p?=?0.001). Discussion and conclusion: Patients with CO poisoning and myocardial injury experienced cardiomyopathy, including reversible global dysfunction and a Takotsubo-like pattern. Investigation of cardiomyopathy needs to be considered in patients with CO poisoning and myocardial injury.     

Novel complex class 1 integron bearing an ISCR1 element in an Escherichia coli isolate carrying the blaCTX-M-14 gene

This work identifies an ISCR1-related bla(CTX-M-14) gene, which has never been reported before, from a clinical isolate of Escherichia coli. The bla(CTX-M-14) gene was preceded by an ISCR1 element that was followed by a class 1 integron containing three different insert gene cassettes, i.e., dfrA12, orfF, and aadA2.