Diagnostic Ultrasound-Based Investigation of Central vs. Peripheral Arterial Changes Consequent to Low-Dose Caffeine Ingestion.

Caffeine is present in various foods and medicines and is highly accessible through various routes, regardless of age. However, most studies on caffeine have focused on the effects of high-dose caffeine ingestion based on the recommended daily amount for adults. In this study, we examined the physiological changes in the central and peripheral vessels that may occur when ingesting low-dose caffeine due to its high accessibility, with the aim of creating an environment of safe caffeine ingestion. This study included 26 healthy participants in their 20s. Peak systolic velocity (PSV), heart rate (HR), and pulse wave velocity (PWV) for vascular stiffness assessment were measured at 0, 30, and 60 min after caffeine ingestion using diagnostic ultrasound to determine the physiological changes in the blood vessels, common carotid artery (CCA) and radial artery (RA). In addition, percutaneous oxygen saturation (SpO2), blood pressure (BP), and accelerated photoplethysmography (APG) were measured. In comparison with before ingestion, the HR tended to decrease and showed a significant difference at 30 and 60 min (p = 0.014 and p = 0.031, respectively). PSV significantly decreased in both vessels at 30 and 60 min (p < 0.001 and p < 0.001, respectively). APG showed a decreasing trend until 60 min after ingestion, with a significant difference at 30 and 60 min (p = 0.003 and p = 0.012, respectively). No significant difference was observed in SpO2, BP, or PWV; however, they showed a tendency to increase after ingestion. Decreased HR may occur because of the baroreflex caused by an increase in BP. The RA has many branches and a smaller diameter; therefore, the PSV was lower in the RA than that in the CCA. This effect can occur because of the difficulty in the smooth expansion of blood vessels, which leads to a decrease in blood flow. In addition, an increase in intracellular calcium concentration can prevent vasodilation and increase the propagation velocity of pulse waves. The reflected waves can increase systolic blood pressure but reduce PWV and vascular elasticity. These results suggest that even low-dose caffeine can improve blood vessel health by providing temporary stimulation to the blood vessels; however, it can also cause changes in blood flow and blood vessel elasticity, which can lead to serious diseases such as stroke and high blood pressure. Therefore, caution should be exercised when caffeine consumption is indiscriminate.

Necroptosis inhibits autophagy by regulating the formation of RIP3/p62/Keap1 complex in shikonin-induced ROS dependent cell death of human bladder cancer.

BACKGROUND: Shikonin, a natural naphthoquinone compound, has a wide range of pharmacological effects, but its anti-tumor effect and underlying mechanisms in bladder cancer remain unclear. PURPOSE: We aimed to investigate the role of shikonin in bladder cancer in vitro and in vivo in order to broaden the scope of shikonin's clinical application. STUDY DESIGN AND METHODS: We performed MTT and colony formation to detect the inhibiting effect of shikonin on bladder cancer cells. ROS staining and flow cytometry assays were performed to detect the accumulation of ROS. Western blotting, siRNA and immunoprecipitation were used to evaluate the effect of necroptosis in bladder cancer cells. Transmission electron microscopy and immunofluorescence were used to examine the effect of autophagy. Nucleoplasmic separation and other pharmacological experimental methods described were used to explore the Nrf2 signal pathway and the crosstalk with necroptosis and autophagy. We established a subcutaneously implanted tumor model and performed immunohistochemistry assays to study the effects and the underlying mechanisms of shikonin on bladder cancer cells in vivo. RESULTS: The results showed that shikonin has a selective inhibitory effect on bladder cancer cells and has no toxicity on normal bladder epithelial cells. Mechanically, shikonin induced necroptosis and impaired autophagic flux via ROS generation. The accumulation of autophagic biomarker p62 elevated p62/Keap1 complex and activated the Nrf2 signaling pathway to fight against ROS. Furthermore, crosstalk between necroptosis and autophagy was present, we found that RIP3 may be involved in autophagosomes and be degraded by autolysosomes. We found for the first time that shikonin-induced activation of RIP3 may disturb the autophagic flux, and inhibiting RIP3 and necroptosis could accelerate the conversion of autophagosome to autolysosome and further activate autophagy. Therefore, on the basis of RIP3/p62/Keap1 complex regulatory system, we further combined shikonin with late autophagy inhibitor(chloroquine) to treat bladder cancer and achieved a better inhibitory effect. CONCLUSION: In conclusion, shikonin could induce necroptosis and impaired autophagic flux through RIP3/p62/Keap1 complex regulatory system, necroptosis could inhibit the process of autophagy via RIP3. Combining shikonin with late autophagy inhibitor could further activate necroptosis via disturbing RIP3 degradation in bladder cancer in vitro and in vivo.