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Lactate dehydrogenase (LDH) is a terminal enzyme in anaerobic glycolytic pathway. It widely exists in various organisms and is in charge of converting the glycolysis product pyruvic acid to lactic acid. Most parasites, including Clonorchis sinensis, predominantly depend on glycolysis to provide energy. Bioinformatic analysis predicts that the LDHs from many species have more than one transmembrane region, suggesting that it may be a membrane protein. C. sinensis LDH (CsLDH) has been confirmed as a transmembrane protein mainly located in the tegument. The antibodies against CsLDH can inhibit the worm's energy metabolism, kill the worm, and may have the same effects on human cancer cells. In this study, we cloned and characterized human LDHA (HsLDHA), HsLDHB, and CsLDH. Semi-quantitative real-time RCP showed that HsLDHB only existed in hepatocarcinoma cell SMMC-7721. Confocal microscopy and Western blot experiments revealed that HsLDHB was localized in the plasma membrane of SMMC-7721 cells, and the antibodies against CsLDH could cross-react with it. This cross-reaction could inhibit the enzymatic activity of HsLDHB. The cancer cells co-cultured with anti-CsLDH sera showed a significant decrease in cell proliferation rate and increases in caspase 9 and reactive oxygen species (ROS) levels. Therefore, anti-CsLDH antibodies can induce the apoptosis of cancer cells SMMC-7721 and may serve as a new tool to inhibit tumor.

In this study, we compared the efficacies and adverse effects of quinine plus antibiotics and other anti-malaria drugs on treating uncomplicated falciparum malaria. By systematically searching the major databases PubMed, Embase, and the Cochrane Library, 14 randomized controlled trials (RCTs) including 1996 cases were identified. Then, we performed a systematic review and cumulative meta-analysis on these data. The primary outcome of these treatments was parasite failure at day 28. There was no significant difference between quinine plus antibiotic therapy (QACT) and artemisinin-based therapies (odds ratio (OR) 0.69, 95 % confidence interval (CI) 0.28 to 1.71) or non-artemisinin-based therapies except quinine monotherapy and chloroquine monotherapy (OR 0.56, 95 % CI 0.18 to 1.74). The secondary outcome was the adverse effects within 28 days, including nausea, dizziness, vomiting, diarrhea, abdominal pain, headache, and tinnitus. QACT significantly increased the risk of tinnitus compared with artemisinin-based therapies (OR 111.65, 95 % CI 12.63 to 986.87) and non-artemisinin-based therapies (OR 48.16, 95 % CI 16.23 to 142.92). Vomiting was more frequently reported in QACT compared with non-artemisinin-based therapies (OR 2.02, 95 % CI 1.14 to 3.56). This meta-analysis suggests that almost all regimens have equivalent treatment effect at the 28th day. However, the patients with QACT had a higher chance to suffer from vomiting and tinnitus. Therefore, QACT does not have significant advantage on treating uncomplicated falciparum malaria.