Effect of estradiol and bisphenol A on human hepatoblastoma cell viability and telomerase activity

Sex hormones from environmental and physiological sources might play a major role in the pathogenesis of hepatoblastoma in children. This study investigated the effects of estradiol and bisphenol A on the proliferation and telomerase activity of human hepatoblastoma HepG2 cells. The cells were divided into 6 treatment groups: control, bisphenol A, estradiol, anti-estrogen ICI 182,780 (hereinafter ICI), bisphenol A+ICI, and estradiol+ICI. Cell proliferation was measured based on average absorbance using the Cell Counting-8 assay. The cell cycle distribution and apoptotic index were determined by flow cytometry. Telomerase activity was detected by polymerase chain reaction and a telomeric repeat amplification protocol assay. A higher cell density was observed in bisphenol A (P<0.01) and estradiol (P<0.05) groups compared with the control group. Cell numbers in S and G2/M phases after treatment for 48 h were higher (P<0.05), while the apoptotic index was lower (P<0.05) and telomerase activities at 48 and 72 h (P<0.05) were higher in these groups than in the control group. The cell density was also higher in bisphenol A+ICI (P<0.01) and estradiol+ICI (P<0.05) groups compared with the ICI group. Furthermore, cell numbers were increased in S and G2/M phases (P<0.05), while the apoptotic index was lower (P<0.05) and telomerase activities at 48 and 72 h were higher (P<0.05) in these groups than in the ICI group. Therefore, bisphenol A and estradiol promote HepG2 cell proliferation in vitro by inhibition of apoptosis and stimulation of telomerase activity via an estrogen receptor-dependent pathway.

Seroprevalence and risk factors for Toxoplasma gondii in sheep and goats in Jinzhou, Northeastern China

In the present study, serum samples from 402 sheep and 216 goats were collected from 5 counties in Jinzhou from August to October 2012 and antibodies to Toxoplasma gondii were detected by modified agglutination test (MAT). Overall, 104 (16.8%) had antibodies to T. gondii with antibody titres of 1:25 to 1:800. Seropositive samples were distributed in all the 5 counties and seroprevalences of T. gondii varied significantly with flock size, age and rearing system, but not with breed, gender and farm location. The seroprevalences in small farms (18.3%, 95/518, 95% confidence interval [CI], 15.0-21.7%) were statistically higher than that in large farms (9%, 9/100, 95% CI, 3.4-14.6%) (P < 0.05), older animals were statistically higher than that in younger animals (P < 0.01). The prevalence in extensively and semiintensively raised samples was statistically higher than that in intensively raised animals (P < 0.01). Small flock size and extensive rearing system are the potential risk factors for the prevalence of Toxoplasma infection in sheep and goats in Jinzhou. This is the first report of T. gondii infection in sheep and goats in Jinzhou, northeastern China, and of an association of seropositivity to T. gondii and the risk factors.

Biogenesis of lysosomes by endocytic flow of plasma membrane

The objective of this review is to examine the biogenesis of lysosomes during the endocytic flow of plasma membrane. Two models have been proposed to explain the formation of lysosomes by this process: the "maturational" and the "stationary" models. According to the former, pinocytotic vesicles fuse among themselves to yield endosomes, which in turn, transform first into multivesicular bodies (MVB) and then into mature lysosomes. Therefore, endosomes and lysosomes would be transient organelles. On the other hand, the "stationary" model proposes that the endocytic pathway is formed by functionally and physically distinct compartments. Cultured cells exposed to ammonium chloride (NH4Cl) and leupeptin after a pulse of cationic ferritin were recently used to freeze endosomes and lysosomes. NH4Cl produced a retention of cationic ferritin in endosomes, indicating that this agent interfered with the endosomal/lysosomal progression. Leupeptin did not affect this process. The number of lysosomes increased in cells treated with both lysosomotropic agents. Thus, NH4Cl affected the endosomal and lysosomal compartments, whereas leupeptin had a preferential effect on lysosomes. Mice mutants with defects of plasma membrane degradation, including a Tay-Sachs model, a Sandhoff disease model, as well as, mice with the inactivated prosaposin gene were used to analyze the biogenesis of lysosomes. Thin sections of mutant cells were examined under the electron microscope, and the analysis revealed a selective accumulation of MVBs and the disappearance of lysosomes, suggesting that the formation of MVBs is a required step in lysosomal maturation and that the intravesicular content of MVBs is necessary for the digestion of plasma membrane components. Taken together, these data indicate that endosomes and MVBs are preceding steps in lysosomal biogenesis and that endosomes, MVBs, and lysosomes are transient organelles

Studies on the transmission potential of surviving microfilaremias after basic control of filariasis.

After filariasis was basically controlled (the microfilarial rate was lower than 1%) in Henan Province in 1987, longitudinal observation of the disease has been carried out in all the province in order to study the regular pattern of growth and decline or the transmission potential of the disease. According to the distribution of filaria species and original microfilarial rate, 7 administrative villages in 7 counties were selected as surveillance sites. From 1988 to 1995, etiological and mosquito vector surveys were made continuously in all sites where no control measure was conducted. 10 surviving microfilaremic individuals became negative gradually over the first 6 years and no new microfilaremia was found. Since then, the microfilarial rate was zero. During the 8 years, 19 vector mosquitos were positive, with a total of 33 filarial larva. Culex pipiens pallens was the predominant mosquito species inside human dwelling in all sites. The man-biting rate of mosquitos for outdoor sleepers fluctuated greatly, the highest was 360.60 mosquitos per man per night and the lowest 7.20. The man-biting rate of mosquitos for sleepers inside mosquito-nets was approximately 1. The proportion of multiparous mosquitos also fluctuated greatly, the highest was 88.10% and the lowest 27.27%. According to the data described above, the man-biting rate of mosquitos which contained filaria L3 was less than 1 mosquito per man per transmission season. It is suggested that after the microfilarial rate was lower than 1%, the surviving microfilaremias became negative gradually in 3-5 years, and the transmission of the disease was blocked. Therefore, in the districts where filariasis was basically controlled, elimination of the disease was attainable.