Three types of microscopic operations were used in this study: 1. excision of the optic vesicle alone; 2. after excising the optic vesicle, a piece of forebrain tissue taken from another donor was inserted in between presumptive lens ectoderm and forebrain wall; 3. cut down the optic vesicle and portion of forebrain tissue and replaced them back in situ by turning over 180?. The operations were carried out on Rana nigromaculata at 15 and 16 stages, in order to bring the presumptive lens ectoderm to come into contact directly with the forebrain tissue for the purpose to analyse the possibility of eye cup formation from the brain wall. The results indicate that the forebrain wall which came into contact with the presumptive lens ectoderm could be induced and differentiated into a secondary eye cup or retina. A total of 81 cases of secondary eye cups among 282 operations (28.8%) were observed. The mechanism for the induction and its significance were discussed.

Objective To explore the effects of different flushing and sealing procedures on blood pressure fluc-tuation in patients receiving norepinephrine(NE) via micro-pump. Methods A total of 40 cases of critically ill pa-tients receiving intravenous infusion of NE via micro-pump,were randomly divided into two groups(20 cases in each group) from March to September,2016. For the experimental group,the liquid medicine in central venous catheter was sucked out,followed by flushing or sealing the tube according to conventional operation method. For the control group,conventional operation method was used to flush or seal the tube. The effects of two methods on arterial blood pressure were compared. Results Overall 423 flushing and sealing events were recorded among 40 cases in this study (209 in the experimental group and 214 in the control group). The fluctuation of blood pressure was small in the experimental group,while patients in the control group had significant fluctuation of blood pressure(P<0.05). Conclusion The new method that sucking liquid medicine out of the central venous catheter before flush-ing or sealing the tube followed by flushing or sealing using conventional operation method can reduce the risk of sudden increase in blood pressure for patients receiving small dose infusion with micro-pump.

BACKGROUNDThe use of stem cells for various clinical applications is highly expected and the production of good quality stem cells is very critical for basic studies. In the bone marrow, hematopoietic and mesenchymal stem cells form a unique niche in which the oxygen tension is low. Hypoxia may have a role in maintaining stem cell fate, self renewal and multi-potency. We investigated whether low oxygen culture would be beneficial for hematopoietic stem cell stemness.METHODSBone marrow cells from 8-10 week aged mice were subjected to hypoxic conditioning by culture for 7days in 20%, 3% and 1% oxygen. For culture,1x105 cell/ml were seeded in colony forming assay in each dish. During the culturing, cell colonies were checked once every three days. Compared to normoxic cells, hypoxic cells weremorphologicallyundifferentiated and counted by Olympus IX71 microscope.RESULTSMore colonies were observed at 3% and 1% oxygen. Statistical significances were identified with granulocytes and macrophage colony (p<0.05) in hypoxic condition.CONCLUSIONSOur data suggests low physiological oxygen culture could improve the stemness of macrophage and granulocytes colony. Long term culture will be necessary to confirm whether low physiological oxygen levels also improve genomic stability.

The development of clinical practice guidelines for medical genetics and genomics specialty is a key step in translating basic and clinical genetic research into evidence-based and precision clinical services.This paper briefly expounds the principles of writing high-quality and trustworthy clinical practice guidelines.According to these principles,the management framework,writing process,review and revision procedures,and application monitoring of medical genetic specialty guidelines are described.Systematic review of relevant literature for evidence applicable to the screening,diagnosis,counseling,treatment and prevention of specific genetic diseases is summarized.Specific requirements for writing and reviewing highquality professional guidelines for medical genetics are introduced.These principles and requirements can ensure that the evidence-based methods and recommendations in the written guidelines conform to current international standards and have specific clinical purposes,scope of practice and time-tracking mechanism.Implementation of such guidelines can promote the translation of basic and clinical genetic research,promote cooperation of medical genetics and other clinical specialties and coordination of interdisciplinary clinical practice guidelines,and provide effective and safe clinical services for patients and their families.

Nanodosimetry, a new discipline developed on the basis of microdosimetry, is based on the structural characteristics of particle tracks and studies on the probability distribution of ionization pairs in a specific volume to characterize the damage degree of DNA strand. Now nanodosimetric quantities, which may be measured, gradually form the concept such as ionization cluster size, ionizing cluster size distribution and complementary cumulative probability distribution etc. This paper aims to establish and explain the relationship between nanodosimetry and DNA damage and repair. On the basis of reviewing the current measurement and calculation method of nanodosimetry, this paper summarized the development trend and application prospect of nanodosimetry, and put forward the future research direction of nanodosimetry.

Objective:To calculate the yield and relative biological effectiveness (RBE) of proton radiation-induced DNA damage to C. elegans germ cells using the Geant4-DNA toolkit in order to explore the biological effects of proton radiation on Caenorhabditis elegans. Methods:A DNA model for a 20-μm-diameter C. elegans germ cell was built using Hilbert curves within the Geant4-DNA toolkit. By simulating DNA damage induced by proton radiation at varying energy levels (100, 50, 20, 5 and 2 MeV), the correlations between DNA double-strand break yields (YDSBs) and different parameters such as physics constructors, energy threshold (ET) models, and free radical scavenging distances were explored, and the result were compared with biological experimental data (20 MeV proton). The DNA damage types from varying energy levels of protons were defined, and the relative biological effectiveness of DNA double-strand breaks (RBE DSB) values were calculated using the RBE DSB mathematical model. Results:The analysis of proton radiation-induced DNA damage under varying physics constructors, ET models, and free radical scavenging distances indicated that the proton radiation-induced YDSBs were the lowest when physics constructor 2 was utilized, while the YDSBs under physics constructors 4 and 6 differed slightly. The proton radiation-induced YDSBs gradually decreased with a rise in both the single ET and free radical scavenging distance. The comparison revealed that the simulation result were the closest to biological experimental data under physics constructor 4, a single ET model of 21.25 eV, and a radical scavenging distance of 9 nm, with disparities approximating 8.3%. Calculated RBE DSB values for protons spanned 1.02 to 1.85, with a lower proton energy corresponding to higher RBE DSB values. Conclusions:Proton radiation-induced YDSBs in C. elegans derived using Geant4-DNA simulations align well with relevant assessments using molecular biology. This study provides a vital means for understanding and predicting the biological effects stemming from proton radiation