Mitochondrial Oxidative Stress Enhances Vasoconstriction by Altering Calcium Homeostasis in Cerebrovascular Smooth Muscle Cells under Simulated Microgravity.

OBJECTIVE: Exposure to microgravity results in postflight cardiovascular deconditioning in astronauts. Vascular oxidative stress injury and mitochondrial dysfunction have been reported during this process. To elucidate the mechanism for this condition, we investigated whether mitochondrial oxidative stress regulates calcium homeostasis and vasoconstriction in hindlimb unweighted (HU) rat cerebral arteries. METHODS: Three-week HU was used to simulate microgravity in rats. The contractile responses to vasoconstrictors, mitochondrial fission/fusion, Ca 2+ distribution, inositol 1,4,5-trisphosphate receptor (IP 3R) abundance, and the activities of voltage-gated K + channels (K V) and Ca 2+-activated K + channels (BK Ca) were examined in rat cerebral vascular smooth muscle cells (VSMCs). RESULTS: An increase of cytoplasmic Ca 2+ and a decrease of mitochondrial/sarcoplasmic reticulum (SR) Ca 2+ were observed in HU rat cerebral VSMCs. The abundance of fusion proteins (mitofusin 1/2 [MFN1/2]) and fission proteins (dynamin-related protein 1 [DRP1] and fission-mitochondrial 1 [FIS1]) was significantly downregulated and upregulated, respectively in HU rat cerebral VSMCs. The cerebrovascular contractile responses to vasoconstrictors were enhanced in HU rats compared to control rats, and IP 3R protein/mRNA levels were significantly upregulated. The current densities and open probabilities of K V and BK Ca decreased and increased, respectively. Treatment with the mitochondrial-targeted antioxidant mitoTEMPO attenuated mitochondrial fission by upregulating MFN1/2 and downregulating DRP1/FIS1. It also decreased IP 3R expression levels and restored the activities of the K V and BK Ca channels. MitoTEMPO restored the Ca 2+ distribution in VSMCs and attenuated the enhanced vasoconstriction in HU rat cerebral arteries. CONCLUSION: The present results suggest that mitochondrial oxidative stress enhances cerebral vasoconstriction by regulating calcium homeostasis during simulated microgravity.

Medicinal values and their chemical bases of Paris / 中国中药杂志

Medicinal values and their chemical bases of Paris (Trilliaceae) are reviewed. Paris plants include 40 species and varieties. Among them, 18 ones are medicinal plants with similarity in traditional uses. Fourteen species have been studied phytochemically, which led to isolation of 207 compounds including 121 steroidal saponins. These saponins are major active constituents from Paris plants, which can explain the traditional uses of the plants to treat cancer, malignant boil, bleeding, gastritis, and so on. The similarity in medicinal uses and chemical constituents of Paris plants implies the possibility of resource substitution among these species. It is worth to further investigate Paris plants in chemical constituents, pharmacological activity, biological property, and toxicology.

An epidemiological study on diabetic retinopathy among type 2 diabetic patients in Shanghai / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence and risk factors of diabetic retinopathy (DR) among type 2 diabetic patients aged over 30 in Shanghai central area.</p><p><b>METHODS</b>1039 patients diagnosed with type 2 diabetes mellitus (DM) aged over 30 were investigated by randomized cluster sampling in Shanghai central area and data from 767 of those patients were analyzed.</p><p><b>RESULTS</b>(1) Among all of the 1534 digital ocular fundus images from 767 patients, 87.6% of the images from 672 patients were gradable. (2) Among all of the 672 patients with gradable ocular fundus images, the prevalence of non-proliferative diabetic retinopathy (NPDR) was 21.6%, while proliferative diabetic retinopathy (PDR) was 1.3%. The rates of mild, moderate and severe NPDR were 8.8%, 11.2% and 1.6% respectively. (3) DR patients were characterized with elder age, higher HbA1c, urea nitrogen and serum creatinine. DM duration and the level of fasting plasma glucose were risk factors for DR.</p><p><b>CONCLUSION</b>The overall prevalence of DR in type 2 diabetic patients aged over 30 in Shanghai central area was 22.9% and the DR risk factors were found to include duration of diabetes and fasting plasma glucose level.</p>