Sequence analysis of the coat protein gene of Chinese soybean mosaic virus strain SC7 and comparison with those of SMV strains from the USA / 病毒学报

To unveil genetic variations between the predominant soybean mosaic virus (SMV) strains in China and in the USA, as well as to reveal the potential relevance between the similarity of gene sequences and the virulence of the viruses, we isolated and sequenced the coat protein (CP) gene of Chinese SMV strain SC7 by RT-PCR and compared the SC7 sequence with those of SMV strains from the USA. Analysis is showed that the CP gene of SC7 was 795 nucleotides in length and encoded 265 in amino acids'. The CP gene of SC7 and those of the strains from the USA exhibited 4%-5% nucleotide diversity and 1%-2% diversity amino acids. The conserved amino-acid sequence associated with aphid spread in the USA strains was DAG, and corresponded to DAD in SC7. The virulence of SC7 was greater than that of the SMV strains from the USA. Nevertheless, no clear relationships between sequence similarity of the CP genes from different strains and their virulence on differential hosts were found.

Survey on seroepidemiological status and vaccine coverage of hepatitis B among children in Chaoyang district of Beijing in 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore seroepidemiological status and vaccine coverage of hepatitis B in children aging under 15 years old in Chaoyang district of Beijing.</p><p><b>METHODS</b>A total of 1602 children aging under 15 years old, residents or floating population who had lived here more than six months, were randomly selected by multistage cluster sampling, from Chaoyang district of Beijing in year 2010. The demographic information and vaccine coverage of hepatitis B vaccine (HepB) were collected by self-designed questionnaire.5 ml blood was collected from each subject and the serum HBsAg, anti-HBs and anti-HBc were detected by Abbott microparticle enzyme-linked immunoassay. Those whose HBsAg was positive were then tested HBeAg and anti-HBe. The positive rate of hepatitis B indicators and coverage rate of HepB in different population were compared.</p><p><b>RESULTS</b>The positive rate of HBsAg, anti-HBs and anti-HBc were 0.56% (9/1602), 64.17% (1028/1602) and 2.12% (34/1602), respectively; while the age standardized rates were separately 0.57%, 66.36% and 1.98%; and the gender-adjusted rates were 0.56%, 64.23% and 2.12% respectively. The positive rate of anti-HBs was statistically significant (χ(2) = 165.445, P = 0.000). The positive rate of anti-HBs was up to 90.73% (235/259) among 1-2 years old children, followed by 76.22% (141/185) among 13 - 15 years old children, 67.21% (166/247) among 3 - 4 years old children, 61.22% (150/245) among 9 - 10 years old children, 60.68% (142/234) among 11 - 12 years old children, 49.05% (103/210) among 5 - 6 years old children and 40.99% (91/222) among 7 - 8 years old children. The average coverage rate of HepB was 90.44% (1371/1516), separately 93.76% (661/705) in residents and 87.55% (719/811) in floating population. The difference was statistically significant (χ(2) = 16.829, P = 0.000).</p><p><b>CONCLUSION</b>HBsAg positive rate in children under 15 years old in Chaoyang district of Beijing dropped to less than 1% and the coverage rate of HepB had reached over 90%. It is suggested that we should pay more attention to increase the coverage rate of HepB among floating children under 15 years old.</p>

Prevalence of hepatitis B in Chaoyang district, Beijing in 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the prevalence of hepatitis B infections and carrier status among general population in Chaoyang district, Beijing in 2010.</p><p><b>METHODS</b>From May to December 2010, 14 491 subjects over 12 months old were selected by multistage random cluster sampling method from residents in Chaoyang district, Beijing. Five millilitre venous blood specimens were collected from these subjects to test hepatitis B virus antigens and antibodies. Status of hepatitis B infections were analyzed in different age, sex and registered permanent residence groups.</p><p><b>RESULTS</b>The overall positive rate of surface antigen (HBsAg) was 2.66% (383/14 410). The lowest rate of 0.56% (9/1603) was found in the 1 to 14 years old group and the 35 to 44 years old group had the highest rate of 4.27% (92/2154). The rate in subjects younger than 24 years old was 1.03% (31/2986). The overall positive rate of surface antibody (anti-HBs) was 40.21% (5798/14 421). The highest positive rate of anti-HBs (80.59%, 407/505) was found in the 1 to 4 years old group. The overall positive rate of core antibody (anti-HBc) was 30.26% (4364/14 424). The overall hepatitis B virus infection rate was 30.32% (4364/14 393). For male and female groups, the positive rates of HBsAg were 2.93% (179/6108) and 2.44% (202/8287) respectively (χ² = 3.32, P > 0.05); anti-HBs were 41.93% (2563/6113) and 38.96% (3231/8293) respectively (χ² = 12.88, P < 0.01); and anti-HBc were 31.39% (1919/6114) and 29.39% (2438/8295) respectively (χ² = 6.65, P = 0.01). For local residents group and mobile population group, the positive rates of HBsAg were 2.46% (283/11 510) and 3.60% (98/2719) respectively (χ² = 11.08, P < 0.01); anti-HBs were 37.11% (4293/11 568) and 53.07% (1445/2723) respectively (χ² = 233.51, P < 0.01); and anti-HBc were 30.83% (3567/11 570), and 28.41% (774/2724) respectively (χ² = 6.08, P < 0.05).</p><p><b>CONCLUSION</b>The positive rate of HBsAg in population younger than 24 years old has reached a relatively low level. The mobile population has significantly higher positive rate of HBsAg than local residents, indicating the need for enhancing prevention and control measures for hepatitis B for the mobile population and local residents over 25 years old.</p>

Study on family aggregation and risk factors of hepatitis B virus transmission in Chaoyang district, Beijing / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the family aggregation and risk factors of hepatitis B virus (HBV) transmission in Chaoyang district of Beijing.</p><p><b>METHODS</b>A total of 5266 families were randomly selected for the multi-stage cluster sampling study in Chaoyang district of Beijing in 2010. The family members who aged between 1 and 70 years old and lived constantly in Beijing for over half a year, were recruited as subjects. There were 14 491 subjects in total, including temporary residents who did not have Beijing household account, except foreigners. 5 ml venous blood was drawn from every subject. A self-designed questionnaire was used to collect the basic information of the population and the risk factors of the hepatitis B transmission. Microparticle enzyme-linked immunoassay was applied to test five indicators of hepatitis B. Negative binomial distribution test was used among the HBsAg positive families to calculate the family aggregation rate of hepatitis B. Single factor analysis and multi-factor logistic regression model were used to analyze the risk factors of HBV transmission.</p><p><b>RESULTS</b>In all, 308 out of 5266 families had HBsAg positive members, accounting for 5.85%.383 out of 14 410 subjects were HBsAg positive, rating at 2.66%. The HBsAg positive rate among subjects under 14 years old was the lowest, at 0.56% (9/1603); and the positive rate among subjects aging between 35 and 44 years old was the highest, at 4.27% (47/1029). Negative binomial distribution test showed that the family aggregation rate of HBV infection was 7.66% (χ² = 15.10, P < 0.05). The analysis of family aggregation of HBsAg positive showed that 17.39% (8/46) of the transmission was from father to child, 13.04% (6/46) was from mother to child, 30.44% (14/46) was between couples, and another 39.13% (18/46) was between siblings or other relatives. Both single factor analysis and multi-factor logistic regression analysis showed that hepatitis B positive family members (OR = 5.40, 95%CI: 5.24 - 5.55), hepatitis B positive friends and colleagues (OR = 1.55, 95%CI: 1.11 - 1.99) and blood donation and transfusion history (OR = 1.96, 95%CI: 1.76 - 2.15) were the risk factors of HBV infection.</p><p><b>CONCLUSION</b>HBV transmission showed family aggregation in Beijing, however, the risk factors needed further studies.</p>

Ventricular synchronicity: observations comparing pulse flow and tissue Doppler assessment in a Chinese healthy adult cohort / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Mechanical asynchrony is an important parameter in predicting the response to cardiac resynchronization therapy, but detailed knowledge about cardiac timing in healthy persons is scarce. Therefore, in the current study, we sought to investigate the physiological status of interventricular synchronicity using pulse wave flow and tissue Doppler imaging in a healthy Chinese population.</p><p><b>METHODS</b>Eighty-eight healthy volunteers underwent standard flow and tissue Doppler echocardiographic examinations. Ventricular inflow and outflow pulse wave flow Doppler patterns were recorded together with annulus pulse tissue Doppler imaging. Time intervals from the beginning of the QRS complex to the onset, peak and end of each wave were measured.</p><p><b>RESULTS</b>The onsets of systole between left and right ventricles were highly synchronized by both imaging modalities. However, the left ventricle reached the peak flow ejection and peak mechanical contraction earlier than the right ventricle, (165.61 ± 26.23) ms vs. (204.3 ± 34.55) ms (P < 0.01) and (133.62 ± 26.19) ms vs. (191.25 ± 38.47) ms (P < 0.01). Time to peak early diastolic relaxation was earlier in the left ventricle than in the right heart, (500.23 ± 56.52) ms vs. (524.94 ± 47.42) ms (P < 0.01).</p><p><b>CONCLUSIONS</b>Left and right ventricles were well synchronized at the onsets of systole and diastole even though interventricular peak systolic and peak early diastolic dyssynchrony was observed in healthy people by pulse wave Doppler imaging. In addition, diastolic timing events were slightly affected by age and gender.</p>

Study on the cellular and humoral immunity effect of recombinant Chinese hamster ovary cell hepatitis B vaccine in adults / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the cellular and humoral immunity effect of 10 µg and 20 µg recombinant Chinese hamster ovary (CHO) cell hepatitis B vaccine in adults by randomized double-blind controlled trials.</p><p><b>METHOD</b>A total of 642 adults aged 18 - 45 years old, non-vaccinated against hepatitis B, and hepatitis B five blood indicators negative were selected as the study subjects. The study subjects were randomly divided into two groups and each group had 321 subjects. The subjects were given 10 µg and 20 µg recombinant CHO hepatitis B vaccination respectively by 0, 1st, 6th month schedule. Blood sample was collected from each study subject one month after the second dose vaccination. The anti-HBs level was detected by Abbott chemiluminescence detection method (I2000) to evaluate humoral immunity status. Of all the study objects, 153 cases were randomly selected by the Excel random function. Their blood samples were collected and Lymphocyte were separated to detect the IL-4 and IFN-γ levels in vitro by enzyme-linked immunospot (ELISPOT) method to evaluate the cellular immunity status.</p><p><b>RESULTS</b>The anti-HBs seroconversion rates in 10 µg and 20 µg dose group were 88.8% (285/321) and 95.3% (306/321) respectively, and 95%CI were 85.4% - 92.2% and 93.0% - 97.6% respectively. The spot forming cell (SFC) of IL-4 of the 20 µg-dose group (x(-) = 20.31) were significantly higher than the 10 µg-dose group (x(-) = 8.19, t = 3.27, P < 0.01). With the increasing of anti-HBs titer, the SFC of IL-4 also went up significantly. There was a positive correlation between SFC of IL-4 and anti-HBs (Spearman correlation coefficient = 0.538, P < 0.0001). No significant difference was found for IFN-γ SFC in two groups (10 µg group: x(-) = 1.49; 20 µg group: x(-) = 0.86; t = 1.83, P > 0.05).</p><p><b>CONCLUSION</b>The humoral and cellular immune effects of 20 µg recombinant CHO hepatitis B vaccine are better than that of the 10 µg recombinant CHO hepatitis B vaccine.20 µg recombinant CHO hepatitis B vaccine should be chosen as the adult's hepatitis B prevention vaccine.</p>

1,25-dihydroxyvitamin D₃ pretreatment enhances the efficacy of allergen immunotherapy in a mouse allergic asthma model / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Allergen-specific immunotherapy can induce immune tolerance to specific allergens by regulating immune status of individuals. However, its clinical application is limited due to individual differences in efficacy among patients and un-confirmed safety. 1,25 Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) has been shown to be involved in a variety of physiological processes, including immune response regulation. In the present study we explored the role of 1,25(OH)(2)D(3) pretreatment for immunotherapy.</p><p><b>METHODS</b>Seventy-five BALB/c mice were randomly divided into five groups (15 mice per group). The mouse allergic asthma model was established by intra-peritoneal injection of ovalbumin (OVA, 10 µg) and aluminium hydroxide (2 mg) as an adjuvant. Intra-peritoneal injection of 50 ng of 1,25(OH)(2)D(3) served as a pretreatment, subcutaneous injection of OVA (100 µg) as an immunotherapy, and 1% OVA inhalation as a challenge. Histopathological analysis was performed on four mice per group. The number of cells and their classification in bronchoalvolar lavage (BAL) fluid were assayed. Levels of serum OVA-specific immunoglobulin E (sIgE) and IFN-γ, IL-4, IL-5 and IL-10 in BAL fluid were measured by ELISA.</p><p><b>RESULTS</b>After 1,25(OH)(2)D(3) pretreatment, immunotherapy could significantly inhibit the infiltration of inflammatory cells into lung tissues and BAL fluid of mice with allergic asthma when compared with un-treated animals (eosinophils: (7.46 ± 1.34) × 10(4)/ml vs. (13.41 ± 1.67) × 10(4)/ml, P < 0.05). In addition, levels of IL-4 ((36.91 ± 7.87) pg/ml vs. (43.70 ± 6.42) pg/ml, P > 0.05) and IL-5 ((41.97 ± 7.93) pg/ml vs. (60.14 ± 8.35) pg/ml, P < 0.05) in BAL fluid and serum sIgE ((0.42 ± 0.05) vs. (0.75 ± 0.06) OD units, P < 0.05) were profoundly reduced. However, the IL-10 level in BAL fluid was significantly increased ((67.74 ± 6.57) pg/ml vs. (44.62 ± 8.81) pg/ml, P < 0.05).</p><p><b>CONCLUSIONS</b>These results indicated that 1,25(OH)(2)D(3) pretreatment enhanced the inhibitory effects of immunotherapy on allergic airway inflammation. In the treatment of allergic diseases, 1,25(OH)(2)D(3) pretreatment may be beneficial for improving the efficacy of immunotherapy.</p>

Study on the immuno-effects and influencing factors of Chinese Hamster Ovary (CHO) cell hepatitis B vaccine among adults, under different dosages / 中华流行病学杂志

Objective To evaluate the immuno-effect and related influencing factors on 10 μg and 20 μg Chinese hamster ovary (CHO) cell hepatitis B vaccine, using the randomized double-blind controlled trials in adult population. Methods A total of 642 adults aged 18-45 years old, non-vaccinated against hepatitis B, and negative on five blood indicators for hepatitis B, were selected as the study objects from four districts in Beijing. The study objects were randomly divided into two groups, and then accepted 10 tg and 20 μg recombinant CHO hepatitis B vaccination by 0-1-6 month schedule. Influencing factors were investigated by means of questionnaire. Blood samples were collected one month after the third dose of vaccination. Anti-HBs level was detected by Abott chemiluminescence detection method. For the anti-HBs negative person, fluorescent quantitative PCR method was used to find out if the person had been infected with HBV. Logistic regression analysis was used to find out the influencing factors of anti-HBs seroconversion on every studied subject. Results The anti-HBs seroconversion rates on 10 μg and 20 μg dose groups were 88.8%(95%CI: 85.4%-92.2%) and 95.3%(95%CI: 93.0%-97.6%)respectively. Taking the anti-HBs level＜100 mIU/ml as the low/non-response standard, the low response and non-response rates were 34.3% and 17.4% respectively. The geometric mean titers(GMT)of anti-HBs were 173.42 mIU/ml for the 10 μg dose group and 588.51 mIU/ml for the 20 μg dose group. Data from the Multivariate analysis showed that: diabetes, spouses infected with hepatitis B virus and old age were unfavorable factors for anti-HBs Seroconversion. 20 μg dose of the vaccine was conducive to seroconversion.Conclusion 20 μg CHO hepatitis B vaccine seemed better than 10 μg CHO hepatitis B vaccine while many factors need to be taken into account for evaluation on hepatitis B vaccines.

RT-PCR identification and genetic characterizations of VP1 region of human enterovirus 71 isolated in Beijing in 2008 / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To study the genetic characterizations of VP1 region of Human enterovirus 71 (HEV71) isolated from clinical specimens of hand, foot and mouth disease (HFMD) patients in Beijing in 2008.</p><p><b>METHODS</b>285 clinical samples were collected from HFMD patients in hospitals and day-care centers in Chaoyang district. They were performed by reverse transcription-polymerase chain reaction (RT-PCR) specific for HEV71. 10 HEV71 isolates were selected for entire VP1 coding gene amplification and sequencing.</p><p><b>RESULTS</b>129 samples were RT-PCR positive, the positive rate is 45.26%. The homology of the nucleotide and the amino acid of the 10 strains were 94.6%-99.6% and 95.9%-100%. The phylogenetic tree revealed that 10 Beijing strains clustered within the C4a evolution branch of C4 subgenotype.</p><p><b>CONCLUSIONS</b>RT-PCR played an important role in identifying HFMD outbreak in Beijing in 2008. The HEV71 strains were all belong to C4a evolution branch of C4 subgenotype with several transmission chains, and it showed that C4 subgenotype HEV71 spread in mainland China widely after 1998. The molecular epidemiology surveillance and the research of genetic characterizations of HEV71 should be strengthened in mainland China.</p>

Investigation on the source of the first human of avian influenza A (H5N1) case in Beijing / 中华流行病学杂志

Objective To investigate the source of the first human case of avian influenza A (H5N1) infection in Beijing. Methods Interviewing the relatives of the case and other key persons, collecting and detecting samples of related biological, epidemiological and environmental data of the case were conducted. Later, the infection source was thoroughly investigated. Results The case ever contacted a slaughtered duck 5 days prior to the onset of illness, and the duck was bought from a stall of a wet market in Yanjiao area of Hebei province. Ten environmental samples were collected in this stall and the neighboring stall of the market. Another 6 samples were tested positive for H5N1 virus by PCR method, with 5 virus strains isolated. The whole-genome sequencing indicated that the amino acid homology between the H5N1 virus strains from the environment and the virus isolated from the case reached 99.8%-100%. Conclusion From both epidemiological and virological evidence, it was proved that the first human case of avian influenza A (H5N1) infection in Beijing was infected by a duck that carrying H5N1 virus the case contacted 5 days proceeding the onset of illness.

Etiological analysis of enteric infectious diseases during Beijing Olympic Games / 中华预防医学杂志

<p><b>OBJECTIVE</b>To understand pathogen patterns of enteric infectious diseases and its impact on this pattern due to aggregation of a great deal of foreign visitors during Beijing Olympic Games.</p><p><b>METHODS</b>The diarrheal patient's rectal swabs and stool specimens were collected from Olympic stadium and hospitals of four districts, including Dongcheng, Xicheng, Haidian and Chaoyang. Enteric multiple pathogens were detected from the total 45 specimens. The culture method was used for the enteric bacteria, ELISA and RT-PCR for the enteric viruses. Molecular typing of Salmonella Enteritidis isolation was completed by PFGE.</p><p><b>RESULTS</b>It was found that 26 out of 45 cases were positive with 57.8 percent for pathogen detection, and 24 were identified as enteric pathogenic bacteria, including Vibrio parahaemolyticus, Salmonella, diarrheagenic Escherichia coli and Campylobacter jejuni, two as norovirus. There were mixed infections of two pathogenic bacteria for three cases. Ten kinds of pathogens were detected from foreign cases, while five kinds from Chinese cases. A total of 5 PFGE patterns were identified in 10 Salmonella Enteritidis isolates from national and foreign diarrheal cases, which were concentrative in some extent.</p><p><b>CONCLUSION</b>Vibrio parahaemolyticus, Salmonella, diarrheagenic Escherichia coli and Campylobacter jejuni were found to be the primary bacterial pathogens during the Olympic Games. Enteric virus infection existed in summer diarrhea.</p>

Observation on two kinds of recombinant hepatitis B vaccines used in populations with different immunity / 中华流行病学杂志

<p><b>OBJECTIVE</b>To evaluate the immunity status on different hepatitis B vaccines currently being used in Beijing.</p><p><b>METHODS</b>College students who had not received hepatitis B vaccine and children who had received whole-course immunization at birth, were tested HBsAg, anti-HBs and anti-HBc. All the test-negative cases were served as research subjects. 3 doses recombinant hepatitis B vaccines were given to the college students, following the 0, 1, 6 months schedule. Among which, 140 cases received recombinant beer yeast hepatitis B vaccine (BY vaccine, 10 microg, 5 microg, 5 microg), and 140 cases with recombinant hansenula polymorpha hepatitis B vaccine (HP vaccine, 10 microg, 10 microg, 10 microg). 1 dose was given for boosting immunization to 98 children, in which 49 cases with BY vaccine (5 microg) and 49 cases with HP vaccine (10 microg). Anti-HBs was tested 1 month after.</p><p><b>RESULTS</b>The total positive (> or = 10 mIU/ ml) rate was lower among BY vaccine group than HP vaccine group for the college students (93.5 %, 99.3% , P<0.05), but no statistical difference on GMT(81.2 mIU/ml, 94.6 mIU/ml, P>0.05) was found. For males, the positive rate and GMT were lower in BY vaccine group than in HP vaccine group (85.7% ,100.0%, P<0.01)(56.6 mIU/ml, 98.6 mIU/ml, P<0.01), but with no statistical difference for females (98.8%, 98.5%, P> 0.05) (103.4 mIU/ml, 90.3 mlU/ml, P> 0.05). For the same vaccine, the positive rate and GMT were lower in males than in females when using BY vaccine (85.7% , 98.8%, P<0.01)(56.6 mIU/ml,103.4 mIU/ml, P< 0.01), but no statistical difference was found on HP vaccine(100.0%, 98.5%, P>0.05)(98.6 mIU/ml, 90.3 mIU/ml, P>0.05). The positive rate of anti-HBs was decreasing along with age among the children who had received a whole-course immunization at birth (P <0.01). 98.6 % of the 70 negative cases appeared positive conversion after receiving 1 dose and the GMT raised significantly by 15 times. No statistical difference was found between the two kinds of vaccines(100.0%, 97.4%, P>0.05)(80.5 mIU/ml, 68.5 mIU/ml, P>0.05).</p><p><b>CONCLUSIONS</b>The type of vaccine and sex were related to the effects, better with HP vaccine than BY vaccine in males but was the same for females in adults receiving basic immunization according to the conventional doses. Both kinds of vaccines were ideal when children receiving boosting immunization. The immune memory was good for persons who had received primary immunization with recombinant vaccine but antibody appeared negative conversion. It was not necessary to boost immunization within 6 years after a whole-course immunization with recombinant hepatitis B vaccine in infancy.</p>

Establishment of a Huntington’s Disease in vitro Drug Screening Cell Model / 中国生物工程杂志

To develop a Huntington’s disease(HD) cell model in vitro to screen drugs targeting the aggregation of polyQ,different length of CAG repeat fragments were amplified by random primer PCR, identified by DNA sequencing and were fused to the N-terminus of CAT in the pCAR system respectively which had been constructed and identified before. Recombinant plasmids were transformed into and induced to express in the host E.coli. SDS-PAGE and chloramphenicol resistance test were done to determine the solubility of the polyQ and chloramphenicol resistance levels of the fusions. With different length of CAG repeat fragments cloned and expressed in the CAT-fusion protein reporting system, it is found that when the length of the fragments increased over 40, their encoding polyQ expressed as insoluble protein and chloramphenicol resistance levels are lower, while under 40, the polyQ expressed as soluble ones and chloramphenicol resistance levels are higher. A in vitro HD model that could minimize the pathological process of the HD thus has been developed. With which by measure the recombinant bacteria’s resistance to chloramphenicol, the polyQ’ solubility and folding state in vitro by quality and quantity could be determined. Thus this model can be used to screen drugs or bioactivity materials that can inhibit aggregation of the polyQ, which thereby shedding new light on the prevent, diagnosis and therapy of HD.

The efficiency and safety of torsional mode phacoemulsification for cataract extraction / 眼科

0.05).At post- operative 30 days and 90 days,ECD were(6.39?0.90)%,(6.54?1.24)% respectively in the torsional group and(13.17?1.78)%, (13.67?2.36)% respectively in the US group,the differences between two groups were statistically(P0.05).Conclusion The torsional mode may provide more effective lens re- moval with a lower level of phacoemulsification time and energy.It can reduce the ultrasound energy and the intraocular trauma.(Oph- thalmol CHN,2008,17:82-85)