Remodeling the conformational dynamics of I-motif DNA by helicases in ATP-independent mode at acidic environment.

I-motifs are noncanonical four-stranded DNA structures formed by C-rich sequences at acidic environment with critical biofunctions. The particular pH sensitivity has inspired the development of i-motifs as pH sensors and DNA motors in nanotechnology. However, the folding and regulation mechanisms of i-motifs remain elusive. Here, using single-molecule FRET, we first show that i-motifs are more dynamic than G4s. Impressively, i-motifs display a high diversity of six folding species with slow interconversion. Further results indicate that i-motifs can be linearized by Replication protein A. More importantly, we identified a number of helicases with high specificity to i-motifs at low pH. All these helicases directly act on and efficiently resolve i-motifs into intermediates independent of ATP, although they poorly unwind G4 or duplex at low pH. Owing to the extreme sensitivity to helicases and no need for ATP, i-motif may be applied as a probe for helicase sensing both in vitro and in vivo.

Radiation Dose Reduction in Head and Neck Computed Tomography Angiography.

BACKGROUND AND AIM: The study aims to investigate the feasibility of further radiation dose reduction via the application of a high iodine delivery rate combined with automatic current modulation technology (high noise index) in head and neck computed tomography angiography. METHODS: Sixty-four patients who underwent routine head and neck computed tomographic angiography were randomly divided into two groups: a low-dose group of 32 cases and an ultra-low-dose group of 32 cases. The same image reconstruction technique was applied in both groups using the 50% adaptive statistical iterative reconstruction method. Quantitative and qualitative image quality assessment of the carotid artery, computed tomographic dose index volume, dose length product, and effective dose of the two groups were analyzed. RESULTS: The two groups were not significantly (P>0.05) different in age, gender, and body mass index. Significant (P<0.001) reduction of radiation dose was observed in all the parameters of computed tomographic dose index volume (18.12%), dose length product (19.91%), and effective dose (19.84%) in the ultra-low-dose group. Quantitative and qualitative image assessment produced similar results between the two groups, except for the higher mean vascular computed tomographic values found in the ultra-low dose group. CONCLUSION: Application of a higher iodine delivery rate combined with automatic current modulation technology (high noise index) in an existing low tube voltage protocol can further decrease the radiation dose and the total volume of contrast agent while maintaining similar image quality for patients undergoing computed tomography angiography of the head and neck, which can be recommended as the conventional scanning method.

Humic Acids Inhibit Platelet Activation to Reduce Venous Thromboembolism in Mice.

Objective: We aimed to investigate the effects of the natural product humic acids (HA) on platelet activation and development of venous thromboembolism (VTE) in mice and further explore the relevant mechanism. Methods: Eight-week C57BL/6 mice were randomly assigned to three groups: sham operation group (n = 7), VTE group (n = 8), and VTE + HA group (n = 10). Thrombi were harvested to hematoxylin-eosin staining to evaluate the thrombolysis and recanalization of the thrombus. In addition, flow cytometry was performed to detect the expression levels of protein disulfide isomerase on endothelial-derived exosomes and glycoprotein IIb/IIIa on the surface of the activated platelets surface in plasma. Furthermore, the protein expression level of glycoprotein IIb/IIIa in thrombus was determined by immunohistochemistry and immunofluorescence. Results: The length of thrombosis in the VTE + HA group was significantly shorter than that in the VTE group (P = 0.040). No significant differences were observed in thrombolysis and recanalization between the VTE + HA group and the VTE group (P > 0.05). The content of protein disulfide isomerase carried by endothelial-derived exosomes was significantly increased in the VTE group (P = 0.008) but significantly reduced by native humic acids (P = 0.012). Compared with the VTE group, the expression of glycoprotein IIb/IIIa on activated platelet surface in the VTE + HA group was significantly decreased (P = 0.002). The concentration of plasmatic P-selectin in the VTE group was significantly higher than that in the VTE + HA group (P < 0.001). Conclusion: We demonstrate that HA possess a pharmacological property that decreases venous thrombus formation in mice. The underlying mechanism is that HA could inhibit the expression of glycoprotein IIb/IIIa on the activated platelets surface by suppressing endothelial-derived exosomes carrying on protein disulfide isomerase, thereby blocking platelet activation.

Replication protein A plays multifaceted roles complementary to specialized helicases in processing G-quadruplex DNA.

G-quadruplexes (G4s) are non-canonical DNA structures with critical roles in DNA metabolisms. To resolve those structures that can cause replication fork stalling and genomic instability, single-stranded DNA-binding proteins and helicases are required. Here, we characterized the interplay between RPA and helicases on G4s using single-molecule FRET. We first discovered that human RPA efficiently prevents G4 formation by preempting ssDNA before its folding. RPA also differentially interacts with the folded G4s. However, helicases such as human BLM and yeast Pif1 have different G4 preferences from RPA mainly based on loop lengths. More importantly, both RPA and these helicases are required for the stable G4 unfolding, as RPA promotes helicase-mediated repetitive unfolding into durative linear state. Furthermore, BLM can traverse G4 obstacles temporarily disrupted by RPA and continue to unwind downstream duplex. We finally proposed the mechanisms underlying above functions of RPA in preventing, resolving, and assisting helicases to eliminate G4s.

Expression of EZH2 and P53 and their correlation in ovarian cancer tissues.

Previous researches have demonstrated that EZH2 expression is increased in many solid tumors and is closely related to the worse progression, transcriptional silence, distal metastasis, and differential inhibition of tumors. P53 can regulate many cells signaling pathways and play an important role in cell cycle, cell apoptosis, and cell senescence. However, there are few reports on the expression of EZH2 and p53 in ovarian cancer and their correlation with the ovarian cancer. The purpose is to elucidate the expression of EZH2 and p53 in ovarian cancer and to study the relationship of EZH2 and p53 with the clinical parameters of ovarian cancer. In this study, both mRNA and protein level of EZH2 in ovarian cancer group was significantly higher than that in borderline, benign, and normal group; while the mRNA and protein level of p53 was significantly lower than that in borderline, benign, and normal group. The expression of EZH2 protein was mainly located in the cytoplasm and nucleus, while mutated p53 protein was mainly located in the nucleus. Furthermore, the expression of EZH2 is closely related to the FIGO stage and histological grade of ovarian cancer. EZH2 and P53 are closely related to the occurrence of ovarian cancer. We speculate that EZH2 may promote the development of ovarian cancer by inhibiting the expression of p53, suggesting that p53 may be the target gene of EZH2.

Application value of three-dimensional arterial spin labeling perfusion imaging in investigating cerebral blood flow dynamics in normal full-term neonates.

BACKGROUND: This study aims to investigate the application value of three-dimensional arterial spin labeling (3DASL) in investigating cerebral blood flow dynamics in full-term neonates. METHODS: A total of 60 full-term neonates without known intracranial pathology were recruited for 3DASL examination. These neonates were divided into three groups: 1-3 day group, 4-7 day group, and 8-15 day group. On the cerebral blood flow (CBF) images, regions of interest (ROI) were selected from the frontal white matter, parietal white matter, basal ganglia, corona radiata, thalamus and brainstem, and the CBF values of each ROI were recorded. The CBF values of ROIs at bilaterally symmetric locations, the values of each ROI between males and females, and the values of each ROI among these three different age groups were compared. RESULTS: The difference in CBF values of the frontal white matter, parietal white matter, basal ganglia, corona radiata and thalamus at the bilateral symmetric positions were not statistically significant. There was no statistical difference in the CBF values of each brain region between the male and female groups. The CBF values at the basal ganglia region, corona radiata and parietal white matter were higher in the 8-15 day group, when compared to the 1-3 day and 4-7 day groups (P < 0.05). The CBF value at the basal ganglia region was higher in the 4-7 day group, when compared to the 1-3 day group (P < 0.05). The CBF value at the frontal white matter was lower in the 4-7 day group, when compared to the 1-3 day and 8-15 day group (P < 0.05). The CBF value at the brainstem was higher in the 4-7 day group, when compared to the 1-3 day and 8-15 day groups (P < 0.05). CONCLUSION: The 3DASL can quantitatively measure CBF, and be used to evaluate cerebral hemodynamics in neonates. The basal ganglia region and corona radiata CBF increases with the increase in neonatal diurnal age.

Optimal Monochromatic Imaging of Spectral Computed Tomography Potentially Improves the Quality of Hepatic Vascular Imaging.

Objective: To investigate the efficiency of spectral computed tomography (CT) optimal monochromatic images in improving imaging quality of liver vessels. Materials and Methods: The imaging data of 35 patients with abdominal CT angiography were retrospectively analyzed. Hepatic arteries, portal veins, and hepatic veins were reconstructed with mixed energy (quality check, QC), 70 keV and optimal monochromatic mode. Comparative parameters were analyzed including CT value, image noise (IN), contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and subjective qualitative analysis. Results: The optimal monochromatic value for assessment of the common hepatic artery, portal vein, and hepatic vein ranged between 49 keV and 53 keV, with a mean of 51 keV. There were statistically significant differences (p < 0.001) among the optimal monochromatic, 70 keV and QC images with regards to the hepatic vascular CT value, IN, CNR, SNR, and subjective qualitative score. CNR of the common hepatic artery in the optimal monochromatic, 70 keV and QC groups was 24.6 ± 10.9, 18.1 ± 8.3, and 11.6 ± 4.6, respectively (p < 0.001) with subjective scores of 4.7 ± 0.2, 4.0 ± 0.3, and 3.6 ± 0.4, respectively (p < 0.001). CNR of the hepatic portal vein was 6.9 ± 2.7, 4.3 ± 1.9, and 3.0 ± 2.1, respectively (p < 0.001) with subjective scores of 4.5 ± 0.3, 3.9 ± 0.4, and 3.3 ± 0.3, respectively (p < 0.001). CNR of the hepatic vein was 5.7 ± 2.3, 4.2 ± 1.9, and 2.7 ± 1.4, respectively with subjective scores of 4.3 ± 0.3, 3.8 ± 0.4, and 3.2 ± 0.3, respectively (p < 0.001). Conclusion: Optimal monochromatic images can lead to improvement in the imaging parameters and optimization of the image quality of the common hepatic artery, hepatic portal vein and hepatic vein compared with conventional mixed kV and with 70 keV datasets.

Activation of natural killer T cells contributes to triptolide-induced liver injury in mice.

Triptolide (TP) is the main active ingredient of Tripterygium wilfordii Hook.f, which has attracted great interest due to its promising efficacy for autoimmune diseases and tumors. However, severe adverse reactions, especially hepatotoxicity, have restricted its approval in the market. In the present study we explored the role of hepatic natural killer T (NKT) cells in the pathogenesis of TP-induced liver injury in mice. TP (600 µg/kg/day, i.g.) was administered to female mice for 1, 3, or 5 days. We found that administration of TP dose-dependently induced hepatotoxicity, evidenced by the body weight reduction, elevated serum ALT and AST levels, as well as significant histopathological changes in the livers. However, the mice were resistant to the development of TP-induced liver injury when their NKT cells were depleted by injection of anti-NK1.1 mAb (200 µg, i.p.) on days -2 and -1 before TP administration. We further revealed that TP administration activated NKT cells, dominantly releasing Th1 cytokine IFN-γ, recruiting neutrophils and macrophages, and leading to liver damage. After anti-NK1.1 injection, however, the mice mainly secreted Th2 cytokine IL-4 in the livers and exhibited a significantly lower percentage of hepatic infiltrating neutrophils and macrophages upon TP challenge. The activation of NKT cells was associated with the upregulation of Toll-like receptor (TLR) signaling pathway. Collectively, these results demonstrate a novel role of NKT cells contributing to the mechanisms of TP-induced liver injury. More importantly, the regulation of NKT cells may promote effective measures that control drug-induced liver injury.

The chemistry and pharmacology of Ligularia przewalskii: A review.

ETHNOPHARMACOLOGICAL RELEVANCE: Ligularia przewalskii (Maxim.) Diels (LP) (called zhangyetuowu in Chinese), is generally found in moist forest areas in the western regions of China. The root, leaves and flower of LP are utilized as a common traditional medicine in China. It has been utilized conventionally in herbal remedies for the remedy of haemoptysis, asthma, pulmonary phthisis, jaundice hepatitis, food poisoning, bronchitis, cough, fever, wound healing, measles, carbuncle, swelling and phlegm diseases. AIM OF THE STUDY: The review aims to provide a systematic summary of LP and to reveal the correlation between the traditional uses and pharmacological activities in order to provide updated, comprehensive and categorized information and identify the therapeutic potential for its use as a new medicine. MATERIALS AND METHODS: The relevant data were searched by using the keywords "Ligularia przewalskii" "phytochemistry", "pharmacology", "Traditional uses", and "Toxicity" in "Scopus", "Scifinder", "Springer", "Pubmed", "Wiley", "Web of Science", "China Knowledge Resource Integrated databases (CNKI)", "Ph.D." and "M.Sc. dissertations", and a hand-search was done to acquire peer-reviewed articles and reports about LP. The plant taxonomy was validated by the databases "The Plant List", "Flora Reipublicae Popularis Sinicae", "A Collection of Qinghai Economic Plants", "Inner Mongolia plant medicine Chi", Zhonghua-bencao and the Standard of Chinese herbal medicine in Gansu. RESULTS: Based on the traditional uses, the chemical nature and biological effects of LP have been the focus of research. In modern research, approximately seventy-six secondary metabolites, including thirty-eight terpenoids, nine benzofuran derivatives, seven flavonoids, ten sterols and others, were isolated from this plant. They exhibit anti-inflammatory, antioxidative, anti-bacterial and anti-tumour effects, and so on. Currently, there is no report on the toxicity of LP, but hepatotoxic pyrrolizidine alkaloids (HPA) were first detected with LC/MSn in LP, and they have potential hepatotoxicity. CONCLUSIONS: The lung-moistening, cough-relieving and phlegm-resolving actions of the root of LP are attributed to the anti-inflammatory properties of flavonoids and terpenoids. The heat-clearing, dampness-removing and gallbladder-normalizing (to cure jaundice) actions of the flowers of LP are based on the anti-inflammatory, antioxidant and hepatoprotective activity properties of terpenoids, flavonoids and sterols. The Traditional Chinese Medicine (TCM) characteristics of LP (bitter flavour) corroborate its potent anti-inflammatory effects. In addition, the remarkable anti-inflammatory and antioxidant capacities of LP contribute to its anti-tumour and antitussive activities. Many conventional uses of LP have now been validated by modernized pharmacological research. For future research, further phytochemical and biological studies need to be conducted on LP, In particular, the safety, mechanism of action and efficacy of LP could be of future research interest before beginning clinical trials. More in vivo experiments and clinical studies are encouraged to further clarify the relation between traditional uses and modern applications. Regarding the roots, leaves and flowers of LP, their chemical compositions and clinical effects should be compared. The information on LP will be helpful in providing and identifying its therapeutic potential and economic value for its use as a new medicine in the future.

A meta-analysis of high dose, intermittent vitamin D supplementation among older adults.

BACKGROUND: The effects of intermittent, high dose vitamin D treatment in older adults have not been documented. We conducted a meta-analysis to provide a quantitative assessment of the efficiency of intermittent, high dose vitamin D treatment on falls, fractures, and mortality among older adults. METHODS: Electronic databases were searched for randomized controlled trials (RCTs) on high dose, intermittent vitamin D supplementation among older adults. Two researchers independently screened the literature according to specified inclusive and exclusive criteria to extract the data. Meta-analysis was performed by using Review Manager 5.1.0 software. RESULTS: Nine trials were included in this meta-analysis. High dose, intermittent vitamin D therapy did not decrease all-cause mortality among older adults. The risk ratio (95% CI) was 1.04 (0.91-1.17). No benefit was seen in fracture or fall prevention. The risk ratio for hip fractures (95% CI) was 1.17 (0.97-1.41) while for non-vertebral fractures (95% CI) it was 1.06 (0.91-1.22), and the risk ratio for falls (95% CI) was 1.02 (0.96-1.08). Results remained robust after sensitivity analysis. CONCLUSION: Supplementation of intermittent, high dose vitamin D may not be effective in preventing overall mortality, fractures, or falls among older adults. The route of administration of vitamin D supplements may well change the physiological effects.