Chemical Constituents of the Roots of Vernonia cumingiana Benth.

To search for new and bioactive constituents from traditional Chinese medicines, a new steroidal saponin, named vernonioside G （1）, was isolated from the roots of Vernonia cumingiana Benth. （Compositae）. The structure of vernonioside G was elucidated using spectral methods, particularly two-dimensional nuclear magnetic resonance analysis. Together with the new compound, eight known compounds were also isolated and identified from the roots of V. cumingiana, among which, VE-1 （2） and 24-methylenelanost-9（11）- en-3β-ol acetate （3） were assigned NMR data for the first time and compound 3 was obtained as a natural product from a plant for the first time.     

Snapshot of HIV pathogenesis in China

Several reviews have focused on the nature of HIV infection and its spread in various geographical regions of China. In contrast, this review provides a comprehensive update on the prevalence of multiple HIV- 1 subtypes, consequent emergence of recombinant and novel forms of HIV- 1 in China, and the implications this may have on HIV diversity and the development of effective vaccines. In addition it also examines the dissemination of primary drug resistance in therapy naive patients, as well as co-infections with two other important viruses-hepatitis B and C. The main purpose of this review is to provide a current snapshot of HIV-1 pathogenesis in China and possibly shed some light on the future of HIV evolution, and potential challenges for future vaccine and anti-retroviral therapeutics against HIV strains in this area.     

Purification and characterization of cholecystokinin from the skin of salamander Tylototriton verrucosus

As a group of intestinal hormones and neurotransmitters, cholecystokinins(CCKs) regulate and affect pancreatic enzyme secretion, gastrointestinal motility, pain hypersensitivity, digestion and satiety, and generally contain a DYMGWMDFG sequence at the C-terminus. Many CCKs have been reported in mammals. However, only a few have been reported in amphibians, such as Hyla nigrovittata, Xenopus laevis, and Rana catesbeiana, with none reported in urodele amphibians like newts and salamanders. Here, a CCK called CCK-TV was identified and characterized from the skin of the salamander Tylototriton verrucosus. This CCK contained an amino acid sequence of DYMGWMDF-NH2 as seen in other CCKs. A c DNA encoding the CCK precursor containing 129 amino acid residues was cloned from the c DNA library of T. verrucosus skin. The CCK-TV had the potential to induce the contraction of smooth muscle strips isolated from porcine gallbladder, eliciting contraction at a concentration of 5.0x10-11 mol/L and inducing maximal contraction at a concentration of 2.0x10-6 mol/L. The EC50 was 13.6 nmol/L. To the best of our knowledge, this is the first report to identify the presence of a CCK in an urodele amphibian.     

Individual aortic baroreceptors are sensitive to different ranges of blood pressures

Many receptors,including thermal receptors and mechanical receptors,are only activated by stimuli within a clearly defined range of intensities.Differences in the receptive ranges enable individual receptors and their sensory centers to precisely detect the intensity of the stimulus and changes in intensity.Baroreceptors are the sensory terminals of the baroreflex.It is well understood that an increasing number of baroreceptors are recruited to produce afferent action potentials as the blood pressure increases,indicating that individual baroreceptors have different pressure thresholds.The present study revealed that individual baroreceptors could stop their afferent signals when the blood pressure exceeds a certain level,indicating that individual baroreceptors are sensitive to a specific range of blood pressure.The receptive ranges of individual baroreceptors differ in terms of the total range,the lower threshold,and the upper threshold.Of 85 baroreceptors examined in this study,the upper thresholds for about half were within the physiological blood pressure range.These results indicate that supraphysiological blood pressure is unlikely to be encoded by the recruitment of more baroreceptors.Instead,supraphysiological blood pressure levels might be signaled by an increase in the frequency of action potentials or by other mechanisms.In conclusion,our results indicate that rabbit baroreceptors are activated by blood pressure levels within specific receptive ranges.These findings should encourage further studies to examine the role of population coding of blood pressure by baroreceptors in the baroreflex.     

Biocompatibility of nano-hydroxyapatite/Mg-Zn-Ca alloy composite scaffolds to human umbilical cord mesenchymal stem cells from Wharton’s jelly in vitro

Seeding cells and scaffolds play pivotal roles in bone tissue engineering and regenerative medicine.Wharton’s jelly-derived mesenchymal stem cells(WJCs)from human umbilical cord represent attractive and promising seeding cells in tissue regeneration and engineering for treatment applications.This study was carried out to explore the biocompatibility of scaffolds to seeding cells in vitro.Rod-like nano-hydroxyapatite(RN-HA)and flake-like micro-hydroxyapatite(FM-HA)coatings were prepared on Mg-Zn-Ca alloy substrates using micro-arc oxidation and electrochemical deposition.WJCs were utilized to investigate the cellular biocompatibility of Mg-Zn-Ca alloys after different surface modifications by observing the cell adhesion,morphology,proliferation,and osteoblastic differentiation.The in vitro results indicated that the RN-HA coating group was more suitable for cell proliferation and cell osteoblastic differentiation than the FM-HA group,demonstrating better biocompatibility.Our results suggested that the RN-HA coating on Mg-Zn-Ca alloy substrates might be of great potential in bone tissue engineering.     

Field Surveys Suggest Biennial Reproduction Cycle and Competition-triggered Dispersal of the Endangered Chinese Crocodile Lizard

The endangered Chinese crocodile lizard(Shinisaurus crocodilurus) is a habitat specialist living in streams of mountain forests in southern China and northern Vietnam. Conservation efforts are increasing for recovering its wild populations. However, the growth, reproduction, and dispersal ability of crocodile lizards in the wild are largely unknown. We conducted field surveys of the crocodile lizard population in Daguishan National Nature Reserve, one of the largest extant wild populations of cr...