[A survey of performance of public health risk assessment in emergencies of institutions for disease control and prevention at different levels in China]

Objective: To understand the performance of public health risk assessment in emergencies of institutions for disease control and prevention at different levels in China, and provide suggestions for the improvement of public health risk assessment. Methods: A self-administered survey was conducted in professionals involved in public health risk assessment in emergencies from national institution, provincial institutions and some prefectural institutions for disease control and prevention (1-2 prefectural institutions were selected using convenience sampling in each province) between March and April in 2021. Results: A total of 79 institutions for disease control and prevention were investigated, including 1 national institution, 32 provincial institutions and 46 prefectural institutions. By April 2021, all the 79 institutions surveyed had conducted risk assessment of public health emergencies, in which 61 (77.2%) had established departments responsible for the public health risk assessment, i.e. emergency management office or communicable disease prevention and control office (section), and regular risk assessment mechanisms. The main sources of information for public health risk assessment were public health surveillance systems, including the National Notifiable Diseases Reporting System (100.0%) and Public Health Emergencies Management Information System (97.5%). Compared with the provincial institutions, the prefectural institutions were more likely to use specific disease surveillance systems (84.8% vs. 62.5%; χ2=5.09, P=0.024). The risk management recommendations made by 43 institutions for disease control and prevention (54.4%) after the risk assessment were accepted by the superior health administrative departments and used in epidemic prevention and control. Conclusions: Public health risk assessment in emergencies has been widely carried out by national, provincial and prefectural institutions for disease control and prevention in China. Specialized departments and mechanisms have been established, but the information sources are still confined to public health surveillance systems and the application of the risk assessment results still needs to be further improved.

Preliminary validation of tumor cell attachment inhibition assay for developmental toxicants with mouse S180 cells

This study was designed to explore the possibility of using ascitic mouse sarcoma cell line (S180) to validate the mouse tumor cell attachment assay for developmental toxicants, and to test the inhibitory effects of various developmental toxicants. The results showed that 2 of 3 developmental toxicants under consideration, sodium pentobarbital and ethanol, significantly inhibited S180 cells attachment to Concanavalin A-coated surfaces. Inhibition was dependent on concentration, and the IC50 (the concentration that reduced attachment by 50%), of these 2 chemicals was 1.2 x 10(-3) mol/L and 1.0 mol/L, respectively. Another developmental toxicant, hydrocortisone, did not show inhibitory activity. Two non-developmental toxicants, sodium chloride and glycine were also tested and these did not decrease attachment rates. The main results reported here were generally similar to those obtained with ascitic mouse ovarian tumor cells as a model. Therefore, this study added further evidence to the conclusion that cell specificity does not limit attachment inhibition to Con A-coated surfaces, so S180 cell may serve as an alternative cell model, especially when other cell lines are unavailable. Furthermore, after optimal validation, it can be suggested that an S180 cell attachment assay may be a candidate for a series of assays to detect developmental toxicants.

Anti-activin A antibody (IgY) specifically neutralizes various activin A activities

Activin A (beta A beta A), originally isolated from ovarian follicular fluids as a follicule-stimulating hormone (FSH) secretion stimulator, has also been identified as an erythroid differentiation factor (EDF), a neuron survival factor and a mesoderm-inducing factor. Thus, activin A is a multifunctional factor, and further studies on its physiological function are important. However, it is very difficult to produce a specific antibody to neutralize the activity of activin A because of its highly conserved amino acid sequence across mammalian species. In this study, we succeeded in generating an antibody against activin A, which can neutralize several activities of activin A, such as the stimulation of FSH secretion from pituitary cells and the induction of the differentiation of erythrocytes in vitro. This antibody did not affect the activity of activin B (beta B beta B), which induces the differentiation of erythrocytes in vitro, and the activity of inhibin A (alpha beta A), which inhibits FSH secretion from pituitary in vitro, but slightly neutralized that of activin AB (beta A beta B). Western blotting analysis showed that this antibody recognized both dimeric and monomeric forms of the beta A subunit of activin and inhibin. These results suggest that this antibody recognizes the beta A subunit of activin and specifically neutralizes the activity of a dimer of the beta A subunit, activin A. Furthermore, by the addition of this antibody to the culture medium, the development of murine embryos was suppressed, suggesting that endogenous activin A plays an important role in murine development. These results indicate the usefulness of this antibody for studies of endogenous activin actions.

Developmental expression of activin/inhibin beta A, beta B, and alpha subunits, and activin receptor-IIB genes in preimplantation mouse embryos

We demonstrated previously that activin A released the two-cell block of mouse embryos cultured in vitro and stimulated early embryonic development. We then confirmed immunohistochemically the presence of the beta A, beta B, and alpha subunits in early embryos together with the oviductal epithelium facing those embryos. The results of in situ hybridization and reverse-transcription polymerase chain reaction here show the presence of mRNA transcripts for activin/inhibin beta A, beta B subunits in the ovary, oviduct, unfertilized egg, and embryo at the early preimplantation stage. However, the mRNA of the inhibin alpha subunit was not expressed in any of these. Considering our previous demonstration of the immunoreactive beta A, and beta B subunits of activin/inhibin polypeptides in the cytoplasm of 1- and 2-cell embryos, we suggest that activins appearing in the oviduct and in embryos are not only transferred from the follicular fluids, but produced by the oviduct, oocytes, and embryos themselves. Since the mRNA of the inhibin alpha subunit was absent at those stages, the beta A and beta B subunits may not exist as the inhibin molecule. The mRNA of activin receptor-IIB was detected in the ovary, in embryos at the 1-cell and the 8-cell/morula stages, and also in the unfertilized egg, although to a lesser extent, but not in the oviduct or in the 2-cell-stage embryo either in vivo or cultured in vitro. These results suggest that activin is physiologically involved in the process of early development of mouse embryos.

Inhibition of pulmonary surfactant by oleic acid: mechanisms and characteristics

The inhibitory effects of oleic acid (OA) on the surface activity of pulmonary surfactant were characterized by use of the oscillating bubble surfactometer, the Wilhelmy balance, and excised rat lungs. Oscillating bubble studies showed that OA prevented lavaged calf surfactant [0.5 mM phospholipid (PL)] from lowering surface tension below 15 mN/m at or above a molar ratio of OA/PL = 0.5. In contrast to inhibition of surfactant by plasma proteins, increasing the surfactant concentration did not eliminate inhibition by oleic acid, which occurred at OA/PL greater than 0.67 on the oscillating bubble even at surfactant concentrations of 1.5 and 12 mM PL. Studies of surfactant adsorption showed that preformed films of OA had little effect on the adsorption of pulmonary surfactant. Wilhelmy balance studies showed that OA did interfere with the ability of spread films of surfactant to reach low surface tensions during dynamic compression. Further balance experiments with binary films of OA and dipalmitoyl phosphatidylcholine showed that these compounds were miscible in surface films. Together these findings suggested that OA inhibited pulmonary surfactant activity by disrupting the rigid interfacial film responsible for the generation of very low surface tension during dynamic compression. Mechanical studies in excised rat lungs showed that instillation of OA gave altered deflation pressure-volume characteristics with decreased quasi-static compliance, indicating disruption of pulmonary surfactant function in situ. This alteration of mechanics occurred without major changes in the composition of lavaged PLs or in the tissue compliance of the lungs defined by mechanical measurements during inflation-deflation with saline.(ABSTRACT TRUNCATED AT 250 WORDS)

[Inhibition of ova fertilizability by pseudolaric acid B in hamster]

Pseudolaric acid B (PA), a diterpenoid compound isolated from the root of Pseudolarix kaempferi Gorden, was injected into hamster ovarian bursa with various concentration before ovulation. The successful rate of fertilization of ova was significantly decreased, but no effect was observed on spermatozoa activity and fertilizing ability. Hamster ova with or without cumulus were treated with PA at a concentration higher than 50 micrograms/ml in the medium, the fertilizing rate of ova was reduced markedly. At the concentration of 5 micrograms/ml, only the capacity of fertilization of the cumulus-free ova was inhibited. When PA was injected ig 20 mg/kg daily to hamsters (female) for 4 d before mating, partial antifertility effect was observed.