[Epidemic Status of Echinococcosis in Gannan Tibetan Autonomous Prefecture of Gansu Province during 2007-2011].

OBJECTIVE: To investigate the prevalence of echinococcosis in Gannan Tibetan Autonomous Prefecture of Gansu Province since the implementation of the echinococcosis control project from Sepical Funds for Central Government Subsidies to Local Public Health (2007-2011). METHODS: Eight counties of Hezuo, Lintan, Zhuoni, Luqu, Maqu, Xiahe, Zhouqu, and Diebu were selected as survey sites. The prevalence in the sampled population was investigated by B ultrasound examination. Hydatid infection in children below 12 years old was serologically investigated by ELISA. The fecal samples from dogs were determined for Echinococcus infection by double antibody sandwich ELISA method. Livestock were dissected through slaughterhouse for pathological examination. Data of echinococcosis cases of Gannan Tibetan Autonomous Prefecture from 2007 to 2011 were collected from the National Infectious Diseases Reporting System, and statistically analyzed by using SPSS 10.0 and Epi info software. RESULTS: A total of 257 823 people received type B ultrasound examination in the 5 years. Five hundred eighty-one echinococcosis cases were found with an overall prevalence of 0.2%, including 578 cases of echinococcosis granulosus and 3 cases of echinococcosis multilocularis. The annual prevalence in the population decreased year by year, from 0.4% (97/21 938) in 2007 to 0.1% (68/63 980) in 2011 (P <0.05). Three hundred and six cases were officially reported to the National Infectious Diseases Reporting System during the period. Among those, female patients accounted for 58.2% (178/306) and male patients 41.8% (128/ 306). By occupation, more infection were found in herdsmen (82.0%, 251/306), followed by farmers (7.8%; 24/306). The cases were mainly distributed in the 20-60 year-old age group, with the highest prevalence in the group of 30-39 years (23.5%, 72/306). The sero-positive rate in children was 4.7% (1 571/33 613), which was highest in 2008 (8.4%, 413/4907), and lowest in 2010 (3.2%, 223/7 021) (P < 0.05). The mean positive rate of coproantigen in dogs was 6.3% (2 511/40 179), decreased from 11.9% (335/2 819) in 2007 to 6.3% (734/11 666) in 2011 (P < 0.05), with lowest positive rate in 2009 (3.7%, 354/9 550). The mean prevalence of livestock was 4.1% (914/22 087), decreased from 8.8% (235/2 658) in 2007 to 2.0% (144/7 347) in 2011 (P < 0.05). CONCLUSION: Since the project implementation for echinococcosis control in 2007, the prevalence of hydatid desease in the population, the sero-positive rate in children, the positive rate of dog coproantigen, and the prevalence in livestock have been significantly decreased.

[Toxicity tests and their application in safety assessment of water quality].

The safety of water quality has important impacts not only on the health of ecological system, but also on the survival and development of human beings. The conventional assessment methods for water quality based on the concentration limits are not reliable. The toxicity tests can vividly reflect the whole adverse biological effects of multiple chemicals in water body, which has been regarded as a necessary supplement for conventional water quality assessment methods based on physicochemical parameters. Considering the chemical pollutants usually have various adverse biological effects, the ecotoxicity testing methods, including lethality, genotoxicity, endocrine disrupting effects, were classified according to the different toxicity types. Then, the potential applications of toxicity testing methods and corresponding evaluation indices in evaluating the toxicity characteristics of ambient water samples were discussed. Particularly, the safety assessment methods for water quality based on the toxicity tests, including potential toxicology, toxicity unit classification system, potential ecotoxic effect probe, and safety assessment of water quality based on toxicity test battery, were summarized. This paper not only systematically reviewed the progress of toxicity tests and their application in safety assessment of water quality, but also provided the scientific basis for the further development in the future.

The transcription factor Cux1 regulates dendritic morphology of cortical pyramidal neurons.

In the murine cerebral cortex, mammalian homologues of the Cux family transcription factors, Cux1 and Cux2, have been identified as restricted molecular markers for the upper layer (II-IV) pyramidal neurons. However, their functions in cortical development are largely unknown. Here we report that increasing the intracellular level of Cux1, but not Cux2, reduced the dendritic complexity of cultured cortical pyramidal neurons. Consistently, reducing the expression of Cux1 promoted the dendritic arborization in these pyramidal neurons. This effect required the existence of the DNA-binding domains, hence the transcriptional passive repression activity of Cux1. Analysis of downstream signals suggested that Cux1 regulates dendrite development primarily through suppressing the expression of the cyclin-dependent kinase inhibitor p27(Kip1), and RhoA may mediate the regulation of dendritic complexity by Cux1 and p27. Thus, Cux1 functions as a negative regulator of dendritic complexity for cortical pyramidal neurons.

PKCdelta regulates cortical radial migration by stabilizing the Cdk5 activator p35.

Cyclin-dependent kinase 5 (Cdk5) and its activator p35 are critical for radial migration and lamination of cortical neurons. However, how this kinase is regulated by extracellular and intracellular signals during cortical morphogenesis remains unclear. Here, we show that PKCdelta, a member of novel PKC expressing in cortical neurons, could stabilize p35 by direct phosphorylation. PKCdelta attenuated the degradation of p35 but not its mutant derivative, which could not be phosphorylated by PKCdelta. Down-regulation of PKCdelta by in utero electroporation of specific small interference RNA (siRNA) severely impaired the radial migration of cortical neurons. This migration defect was similar to that caused by down-regulation of p35 and could be prevented by cotransfection with the wild-type but not the mutant p35. Furthermore, PKCdelta could be activated by the promigratory factor brain-derived neurotrophic factor (BDNF) and was required for the activation of Cdk5 by BDNF. Both PKCdelta and p35 were required for the promigratory effect of BDNF on cultured newborn neurons. Thus, PKCdelta may promote cortical radial migration through maintaining the proper level of p35 in newborn neurons.

Ca2+-dependent regulation of rho GTPases triggers turning of nerve growth cones.

Cytoplasmic Ca2+ elevation and changes in Rho GTPase activity are both known to mediate axon guidance by extracellular factors, but the causal relationship between these two events has been unclear. Here we show that direct elevation of cytoplasmic Ca2+ by extracellular application of a low concentration of ryanodine, which activated Ca2+ release from intracellular stores, upregulated Cdc42/Rac, but downregulated RhoA, in cultured cerebellar granule cells and human embryonic kidney 293T cells. Chemoattractive turning of the growth cone triggered by a gradient of ryanodine was blocked by overexpression of mutant forms of Cdc42 but not of RhoA in Xenopus spinal cord neurons. Furthermore, Ca2+-induced GTPase activity correlated with activation of protein kinase C and required a basal activity of Ca2+/calmodulin-dependent protein kinase II. Thus, Rho GTPases may mediate axon guidance by linking upstream Ca2+ signals triggered by guidance factors to downstream cytoskeletal rearrangements.