Medical Research Council

About: Medical Research Council is a government organization based out in London, United Kingdom. It is known for research contribution in the topics: Population & Malaria. The organization has 16430 authors who have published 19150 publications receiving 1475494 citations.

Genetic architecture of artemisinin-resistant Plasmodium falciparum.

Abstract: We report a large multicenter genome-wide association study of Plasmodium falciparum resistance to artemisinin, the frontline antimalarial drug. Across 15 locations in Southeast Asia, we identified at least 20 mutations in kelch13 (PF3D7_1343700) affecting the encoded propeller and BTB/POZ domains, which were associated with a slow parasite clearance rate after treatment with artemisinin derivatives. Nonsynonymous polymorphisms in fd (ferredoxin), arps10 (apicoplast ribosomal protein S10), mdr2 (multidrug resistance protein 2) and crt (chloroquine resistance transporter) also showed strong associations with artemisinin resistance. Analysis of the fine structure of the parasite population showed that the fd, arps10, mdr2 and crt polymorphisms are markers of a genetic background on which kelch13 mutations are particularly likely to arise and that they correlate with the contemporary geographical boundaries and population frequencies of artemisinin resistance. These findings indicate that the risk of new resistance-causing mutations emerging is determined by specific predisposing genetic factors in the underlying parasite population.

Cardioprotection by S-nitrosation of a cysteine switch on mitochondrial complex I

Abstract: Oxidative damage from elevated production of reactive oxygen species (ROS) contributes to ischemia-reperfusion injury in myocardial infarction and stroke. The mechanism by which the increase in ROS occurs is not known, and it is unclear how this increase can be prevented. A wide variety of nitric oxide donors and S-nitrosating agents protect the ischemic myocardium from infarction, but the responsible mechanisms are unclear. Here we used a mitochondria-selective S-nitrosating agent, MitoSNO, to determine how mitochondrial S-nitrosation at the reperfusion phase of myocardial infarction is cardioprotective in vivo in mice. We found that protection is due to the S-nitrosation of mitochondrial complex I, which is the entry point for electrons from NADH into the respiratory chain. Reversible S-nitrosation of complex I slows the reactivation of mitochondria during the crucial first minutes of the reperfusion of ischemic tissue, thereby decreasing ROS production, oxidative damage and tissue necrosis. Inhibition of complex I is afforded by the selective S-nitrosation of Cys39 on the ND3 subunit, which becomes susceptible to modification only after ischemia. Our results identify rapid complex I reactivation as a central pathological feature of ischemia-reperfusion injury and show that preventing this reactivation by modification of a cysteine switch is a robust cardioprotective mechanism and hence a rational therapeutic strategy.

Expression of vascular endothelial growth factor and its receptors flt and KDR in ovarian carcinoma.

Abstract: Background: Two thirds of patients with ovarian carcinoma have advanced disease at diagnosis and have poor prognoses because of the presence of highly invasive carcinoma cells and rapidly accumulating ascitic fluid. Vascular endothelial growth factor (VEGF), a potent mitogen of endothelial cells, is produced in elevated amounts by many tumors, including ovarian carcinomas. The known human receptors for VEGF, flt and KDR, are both cell surface tyrosine kinases and are expressed predominantly on endothelial cells. Acting through these receptors, VEGF may stimulate angiogenesis and promote tumor progression. Purpose: We aimed to clarify the function of VEGF in tumor development by identifying the cells in ovarian carcinoma tissue that express VEGF and its receptors. Methods: VEGF, flt, and KDR expression was localized by in situ hybridization and immunohistochemistry in frozen sections of primary tumors from five patients with ovarian carcinoma and from metastases of ovarian carcinoma from three different patients. Reverse transcription followed by polymerase chain reaction (RT-PCR) and an enzyme-linked immunosorbent assay were used to analyze VEGF, flt, and KDR expression in six epithelial cell lines derived from ovarian carcinoma ascites from five additional patients. Results: Messenger RNAs (mRNAs) encoding VEGF, flt, and KDR were detected in primary ascitic cells and in three of four ovarian carcinoma cell lines examined by RT-PCR. Two novel complementary DNAs that may encode truncated, soluble forms of flt were cloned from one primary source. VEGF levels of 20-120 pM were found in culture media conditioned by the cell lines. Elevated expression of VEGF mRNA was found in all primary tumors and metastases, especially at the margins of tumor acini. VEGF immunoreactivity was concentrated in clusters of tumor cells and patches of stromal matrix. flt immunoreactivity was confined to tumor blood vessels, but flt mRNA was not detected by in situ hybridization. In contrast, KDR mRNA was detected not only in vascular endothelial cells but also in tumor cells at primary malignant sites. Conclusions: VEGF is expressed by tumor cells in primary and metastatic ovarian carcinoma and accumulates in the stromal matrix. Its receptors, flt and KDR, are expressed by some tumor blood vessels; KDR is also expressed by some tumor cells that coexpress VEGF. This is the first localization of KDR expression in nonendothelial cells. Implications: Coexpression of VEGF and KDR by tumor cells in ovarian carcinoma raises the possibility of autocrine stimulation and of therapeutic strategies targeting this receptor-ligand interaction