Improved Rodent Model of Myocardial Ischemia and Reperfusion Injury.

Myocardial ischemia and reperfusion injury (MIRI), induced by coronary heart disease (CHD), causes damage to the cardiomyocytes. Furthermore, evidence suggests that thrombolytic therapy or primary percutaneous coronary intervention (PPCI) does not prevent reperfusion injury. There is still no ideal animal model for MIRI. This study aims to improve the MIRI model in rats to make surgery easier and more feasible. A unique method for establishing MIRI is developed by using a soft tube during a key step of the ischemic period. To explore this method, thirty rats were randomly divided into three groups: sham group (n = 10); experimental model group (n = 10); and existing model group (n = 10). Findings of triphenyltetrazolium chloride staining, electrocardiography, and percent survival are compared to determine the accuracies and survival rates of the operations. Based on the study results, it has been concluded that the improved surgery method is associated with a higher survival rate, elevated ST-T segment, and larger infarct size, which is expected to mimic the pathology of MIRI better.

Animal model of coronary microembolization under transthoracic echocardiographic guidance in rats.

The aim of the study was to develop a model of coronary microembolization (CME) in rats at a lower cost. We developed a novel rat model without thoracotomy and ventilation under the guidance of echocardiography. Rats were sacrificed at 3 h, 24 h and 1 month postoperatively in both the Echo-CME and Open-chest CME groups for the comparison of the modeling accuracy, mortality, cardiopulmonary circulation, pleural adhesion and ventilation-induced lung injury (VILI). Results showed that the coronary microthrombus formed at 3 h and reached its peak at 24 h postoperatively, which included platelet aggregation and fibrin web. The Echo-group increases success rates, decreased mortality, postoperative complications including pleural adhesion, cardiopulmonary dysfunction and VILI postoperatively than the Open-chest group at 1month postoperatively. The ejection fraction of the CME group decreased to 50% and obvious cardiac fibrosis formed at 3 months postoperatively. Our unique surgical method provided a platform to study molecular mechanisms and potential new pathways for CME treatment.

Novel ERCC2 variant in trichothiodystrophy infant: the first case report in China.

BACKGROUND: Trichothiodystrophy (TTD) is a rare, autosomal recessive, multisystem disorder most commonly caused by variants in ERCC2. CASE PRESENTATION: Here, we describe the first Chinese patient with a novel variant in ERCC2. A male infant, who was born to a healthy non-consanguineous couple, exhibited brittle hair, hair loss ichthyosis, eczema, retinal pigmentation and hypospadias. He carried a novel heterozygous ERCC2 variant. The maternal variant (c.2191-18_2213del) is a previous described genomic deletion that affects the splicing of intron 22. The paternal variant (c.1666-1G > A), that occurs in the splice site of intron 17 and likely alters ERCC2 gene function through aberrant splicing, has not been reported previously. CONCLUSIONS: Our case reported a novel pathogenic variant in ERCC2, which expanded the known genetic variants associated with TTD.

Central Retinal Vessel Trunk Caliber Changes After Short-term Intraocular Pressure Elevation.

PRECIS: After a short-term intraocular pressure (IOP) elevation, the central retinal vein caliber may be widened at lower IOP rise levels, while be compressed at higher IOP rise values. PURPOSE: The purpose of this study was to investigate changes in the calibers of the central retinal vein trunk (CRVT) and central retinal artery trunk (CRAT) trunk during a short-term elevation of IOP. METHODS: A prospective observational study. Acute primary angle-closure suspects underwent a dark room prone provocative test (DRPPT) for 2 hours. Before and at the end of the test, tonometry, swept-source optical coherence tomography, and nonmydriatic fundus photography were performed. The calibers of the CRVT and CRAT were measured on the fundus photos taken at baseline and at the end of the DRPPT. RESULTS: The study included 101 eyes (61 individuals; mean age: 54.8±9.3 y; range: 30 to 70 y) which showed an increase in IOP by 9.6±9.0 mm Hg (range: 2.3 to 46.7 mm Hg). From baseline to the end of the DRPPT, the mean CRVT caliber increased from 101.8±25.9 to 107.7±26.6 µm (P<0.001), while the CRAT caliber did not differ significantly (110.3±24.2 vs. 109.7±21.5 µm; P=0.54) during the test. The CRVT widening was larger in the subgroup with IOP rise of <6 mm Hg than in the subgroup with an IOP rise of 6 to 15 mm Hg, while in the subgroup with an IOP rise of >15 mm Hg the CRVT caliber did not change significantly (P=0.20) during the test. CONCLUSIONS: A physiological short-term IOP rise at lower levels of IOP elevation led to a widening of the CRVT, while at higher IOP values, the further IOP-rise may have compressed the retinal vein. Because of higher intraluminal pressure values, the retinal artery diameters were not affected by the IOP-rise.

Lamina cribrosa pore movement during acute intraocular pressure rise.

PURPOSE: To assess changes in the position of lamina cribrosa pores (LCPs) induced by acute intraocular pressure (IOP) elevation. METHODS: A prospective observational study. Acute angle-closure suspects who underwent the 2-hour dark room prone provocative test (DRPPT) were included. At baseline and within 5 min after the DRPPT end, tonometry, fundus photography and optical coherence tomography were performed. Optic disc photos taken before and after the DRPPT were aligned and moving distance of each visible LCP was measured (LCPMD). RESULTS: 38 eyes from 27 participants (age: 52.5±10.8 years) were included. The IOP rose from 16.7±3.2 mm Hg at baseline to 23.9±4.3 mm Hg at the DRPPT end. The mean lateral LCPMD was 28.1±14.6 µm (range: 5.0-77.2 µm), which increased with higher IOP rise (p=0.01) and deeper optic cup (p=0.02) in multivariate analysis. The intralamina range and SD of the LCPMD increased with younger age (p=0.01 and p=0.02, respectively) and with wider optic cup (p=0.01 and p=0.02, respectively). The LCP movements were headed to the superior direction in 12 (33%) eyes, inferior direction in 10 (28%) eyes, temporal direction in 9 (25%) eyes, and nasal direction in 5 (14%) eyes. CONCLUSIONS: IOP rise is associated with LCP movements in the frontal plane, which are more pronounced with higher IOP rise and deeper optic cup. The intralamina variability in the IOP rise-associated LCPMD increased with younger age and wider optic cup. IOP variation-associated lateral LCP movements may be of interest to elucidate glaucomatous optic nerve damage.

Transmission risk of avian influenza virus along poultry supply chains in Guangdong, China.

OBJECTIVES: Avian influenza viruses (AIVs) poise significant risk to human health and the poultry industry. We evaluated the transmission risk along the poultry supply chain. METHODS: During October 2015 and July 2016, four rounds of cross-sectional surveys were performed to characterize AIV spread in farms, transport vehicles, slaughterhouses, wholesale and retail live poultry markets (LPMs). Poultry cloacal and oral swabs, environmental swabs, bioaerosol samples and human sera were collected. Poultry and environmental samples were tested for AIVs by rRT-PCR, further subtyped by next generation sequencing. Previous human H9N2 infections were identified by hemagglutination inhibition and microneutralization tests. Logistic regression was fitted to compare AIV transmission risk in different settings. RESULTS: AIVs was detected in 23.9% (424/1771) of the poultry and environmental samples. AIV detection rates in farms, transport vehicles, wholesale and retail LPMs were 4.5%, 11.1%, 30.3% and 51.2%, respectively. 5.2%, 8.3% and 12.8% of the poultry workers were seropositive in farms, wholesale and retail LPMs, respectively. The regression analysis showed that virus detection and transmission risk to human increased progressively along the poultry supply chain. CONCLUSIONS: Strengthening control measures at every level along the poultry supply chain, using a one health approach, is crucial to control AIV circulation.

Effect of Kangshuanyihao Formula on the Inflammatory Reaction and SIRT1/TLR4/NF-κB Signaling Pathway in Endothelial Injury.

Endothelial injury plays an important role in atherosclerosis (AS). Kangshuanyihao formula uses therapeutic principles from Chinese medicine to supplement Qi, thereby promoting blood circulation, and remove blood stasis. The mechanism by which the formula inhibits endothelial injury was examined in a rat model of 1,25-dihydroxyvitamin D3 (VD3) intraperitoneal injection and high-fat-induced endothelial injury. Rats were randomly divided into the model, high-dose, middle-dose, low-dose, positive drug (rosuvastatin), and combination (positive drug + middle-dose) groups; 10 Sprague-Dawley rats served as the blank group. The aortic endothelium was stained with hematoxylin and eosin and the levels of blood lipids and inflammation markers (mRNA and protein) were measured. Endothelial injury, lipid levels, and inflammation were increased in the model. Kangshuanyihao formula reduced endothelial injury, improved lipid levels, and downregulated inflammation, as shown by significant reduction of the protein levels of SIRT1, TLR4, and NF-κB and mRNA levels of SIRT1, TLR4, NF-κB, IL-1ß, IL-6, and IL-12. Thus, we conclude that Kangshuanyihao formula can inhibit the inflammatory reaction in the rat model of high-fat-induced endothelial injury after intraperitoneal injection of VD3. This mechanism may be attributed to regulating the SIRT1/TLR4/NF-κB signaling pathway.

Intraocular pressure elevation and choroidal thinning.

PURPOSE: To evaluate changes in subfoveal choroidal thickness (SFCT) and peripapillary choroidal thickness (PPCT) after acute intraocular pressure (IOP) elevation provoked by a dark room prone provocative test (DRPPT). METHODS: The prospective cohort study included 114 eyes from 65 individuals who had an IOP elevation ≥2 mm Hg during the DRPPT. The participants stayed in a dark room for 2 h with the forehead placed on a desk. At baseline and within 5 min after the end of the DRPPT, tonometry and enhanced depth imaging by spectral-domain optical coherence tomography were carried out. RESULTS: During the DRPPT, IOP increased by 10.1±10.9 mm Hg, SFCT decreased significantly (p<0.001) from 280±80 µm to 267±76 µm and PPCT decreased significantly (p<0.001) from 177±74 to 169±70 µm. In multivariate analysis, a more marked SFCT thinning was associated with higher IOP increase (p<0.001) and shallower anterior chamber depth at baseline (p=0.01). In a similar manner, a higher PPCT change was correlated with a higher IOP increase (p<0.001), and a thicker choroidal thickness at baseline (p<0.001). CONCLUSIONS: Choroidal thickness in the subfoveal region and in the peripapillary region decreased parallel to an acute increase in IOP in individuals 2 h after a dark room test. Choroidal thickness depends on the actual IOP, which may be noted when choroidal thickness is measured.

[Terahertz Spectroscopic Study on the Property of Epoxy Resin Adhesive].

Epoxy resin is an important adhesive applied in the manufacturing processes of fiber reinforced polymer (FRP) composites. Terahertz (THz) time-domain spectroscopy (TDS) technology is an effective supplementary method for nondestructive evaluation (NDE) of FRP composites. As one of the most important parameters for epoxy resin, different curing temperature can affect the properties of epoxy resin. In this paper, we carry out systematic investigations on THz transmission properties of epoxy resin cured respectively under room temperature and high temperature with THz TDS technology. At the same time, the authors extract the refractive indices and absorption coefficients of epoxy resin, and make comparisons d. As shown in the experiments, the epoxy resin samples cured under room temperature have no bubble, whereas there are some micro-bubbles in the samples cured under high temperature, which reduce the sample density. Hence, the refractive index and absorption coefficient of epoxy resin cured under room temperature are both greater than those cured under high temperature. The difference of refractive index of different samples cured under the same condition is not significant. In addition, the difference of absorption coefficient of different samples cured under room temperature is also slight. However, the difference of absorption coefficient of different samples cured under high temperature gradually increase within the frequency from 0.6 to 1.5 THz, which is mainly due to the heterogeneous distribution of the bubbles in the different samples cured under high temperature. Moreover, the absorption coefficient of epoxy resin prepared under both curing temperatures gradually increases with the frequency, and there is no obvious absorption peak. Finally, because of the existence of Fabry-Pérot interference, the power transmission ratio of thicker epoxy resin samples may be greater than thinner samples at the resonant frequency. This research is of great significance for the THz NDE of FRP composites.

Live Bird Exposure among the General Public, Guangzhou, China, May 2013.

BACKGROUND: A novel avian-origin influenza A(H7N9) caused a major outbreak in Mainland China in early 2013. Exposure to live poultry was believed to be the major route of infection. There are limited data on how the general public changes their practices regarding live poultry exposure in response to the early outbreak of this novel influenza and the frequency of population exposure to live poultry in different areas of China. METHODOLOGY: This study investigated population exposures to live birds from various sources during the outbreak of H7N9 in Guangzhou city, China in 2013 and compared them with those observed during the 2006 influenza A(H5N1) outbreak. Adults were telephone-interviewed using two-stage sampling, stratified by three residential areas of Guangzhou: urban areas and two semi-rural areas in one of which (Zengcheng) A(H7N9) virus was detected in a chicken from wet markets. Logistic regression models were built to describe practices protecting against avian influenza, weighted by age and gender, and then compare these practices across residential areas in 2013 with those from a comparable 2006 survey. PRINCIPAL FINDINGS: Of 1196 respondents, 45% visited wet markets at least daily and 22.0% reported buying live birds from wet markets at least weekly in April-May, 2013, after the H7N9 epidemic was officially declared in late March 2013. Of those buying live birds, 32.3% reported touching birds when buying and 13.7% would slaughter the poultry at home. Although only 10.1% of the respondents reported raising backyard birds, 92.1% of those who did so had physical contact with the birds they raised. Zengcheng respondents were less likely to report buying live birds from wet markets, but more likely to buy from other sources when compared to urban respondents. Compared with the 2006 survey, the prevalence of buying live birds from wet markets, touching when buying and slaughtering birds at home had substantially declined in the 2013 survey. CONCLUSION/SIGNIFICANCE: Although population exposures to live poultry were substantially fewer in 2013 compared to 2006, wet markets and backyard poultry remained the two major sources of live bird exposures for the public in Guangzhou in 2013. Zengcheng residents seemed to have reduced buying live birds from wet markets but not from other sources in response to the detection of H7N9 virus in wet markets.

Effect of Angiotensin receptor blockers on flow-mediated vasodilation: a meta-analysis of randomized controlled trials.

BACKGROUND: In a meta-analysis, we investigated the effects of angiotensin receptor blockers (ARBs) in comparison to placebo or other classes of antihypertensive drugs on endothelial function, which was measured by brachial flow-mediated vasodilation (FMD). METHODS: We searched for randomized controlled trials that compared ARBs with placebo or other classes of antihypertensive drugs in improving FMD. A random-effect model was used to compute pooled estimates. RESULTS: In 13 trials (n = 529), ARBs were more efficacious in improving brachial FMD than placebo [pooled weighted mean change difference (WMD) 1.34%, 95% CI, 0.93-1.75%, p<0.001]. In 15 trials (n = 918), treatment with ARBs had a significant effect on brachial FMD when compared with other antihypertensive drugs (pooled WMD 0.59%, 95% CI, 0.20-0.98%, p = 0.003 with significant heterogeneity). ARBs were also more efficacious in improving brachial FMD than calcium channel blockers (CCBs; pooled WMD 1.61%, 95% CI, 0.72-2.49%, p < 0.001) but not the other classes of drugs (p ≥ 0.072). CONCLUSIONS: This meta-analysis shows that ARBs improve brachial FMD, a marker of endothelial function, and that they are superior to placebo and CCBs. There was no significant difference in the effect on brachial FMD between ARBs and the other antihypertensive drugs.

Optic nerve head changes after short-term intraocular pressure elevation in acute primary angle-closure suspects.

PURPOSE: To investigate changes in the optic nerve head morphology after acute intraocular pressure (IOP) elevation during a dark room prone provocative test (DRPPT). DESIGN: Prospective cohort study. PARTICIPANTS: Acute primary angle-closure (APAC) suspects underwent DRPPT. METHODS: Study participants stayed in a dark room for 2 hours with the forehead placed on a desk. At baseline and within 5 minutes after DRPPT, tonometry and enhanced depth imaging by spectral-domain optical coherence tomography (SD OCT) were performed. MAIN OUTCOME MEASURES: Changes in 3-dimensional optic nerve head topography. RESULTS: The study included 114 eyes of 65 participants with a mean age of 58.3±8.7 years and a mean IOP elevation of 10.1±10.9 mmHg during DRPPT. When all eyes were included, the mean value of most optic disc parameters did not change significantly, except for a decrease in the temporal minimal rim width (P = 0.005). By including only eyes with an IOP increase greater than 15 mmHg, the mean value of cup width (P = 0.001) and cup depth (P = 0.002) increased, whereas the lamina cribrosa (LC) thickness (P = 0.035), temporal minimal rim width (P = 0.001), and nasal minimal rim width (P < 0.001) decreased. The LC depth and Bruch's membrane opening (BMO) did not differ between the baseline and the end of DRPPT. An IOP increase was significantly associated with widening (P < 0.001; r = 0.46) and deepening (P < 0.001; r = 0.52) of the optic cup, thinning of the LC (P = 0.003; r = -0.35), temporal minimal rim width (P < 0.001; r = -0.34), and nasal minimal rim width (P < 0.001; r = -0.35). CONCLUSIONS: Angle-closure suspect eyes showed a widening and deepening of the optic cup, decrease in neuroretinal rim width, and thinning of the LC after a darkness-induced IOP increase of >15 mmHg. The diameter of the BMO and position of the anterior LC surface remained unchanged. This suggests that a short-term IOP increase leads to a condensation of neuroretinal rim, prelaminar tissue, and LC, without major changes in the optic disc size and position of the anterior LC surface.

Astragaloside IV stimulates angiogenesis and increases nitric oxide accumulation via JAK2/STAT3 and ERK1/2 pathway.

Astragaloside IV (AS-IV), one of the major active constituents of Astragalus membranaceus in Traditional Chinese Medicine, has been widely used to treat ischemic diseases. However, the potential mechanism is this action is unclear. In this study, we tested the hypothesis that AS-IV might promote angiogenesis through multiple signaling pathways. Our data indicate that AS-IV treatment promotes umbilical vein endothelial cells (HUVEC) proliferation, migration, and tube formation. AS-IV treatment also activates JAK2/STAT3 and ERK1/2 signaling pathways, and up-regulates endothelial nitric oxide synthase (eNOS) expression and nitric oxide (NO) production. AS-IV-induced angiogenesis in HUVECs is significantly blocked by specific kinase inhibitors. Our study indicated that AS-IV is a key regulator of NO and angiogenesis through the JAK2/STAT3 and ERK1/2 pathways, which provides a mechanistic basis for the potential use of this compound in the treatment of clinical ischemic diseases.

[Effect of clinical pathways based on integrative medicine for patients with chronic heart failure: a multi-center research].

OBJECTIVE: To assess a multi-center study effectiveness of clinical pathways based on integrative medicine (IM) for chronic heart failure (CHF) patients. METHODS: A combined method of historical control study and clinical study on concurrent control was used. After the standard management for clinical pathways was carried out in four hospitals at home, the effects on hospitalization days, medical expenses, clinical efficacy, patient satisfaction, and quality of life were assessed. RESULTS: Results of non-concurrent historical control study showed that: the hospital stay was significantly shorter in the pathways group than in the retrospective group (12.59 days vs 18.44 days), and the total cost of hospitalization was significantly reduced in the pathways group (yen 9 051.90 vs yen 11 978.40), showing statistical difference (P < 0.01). Moreover, the effect on the heart function was better in the pathways group than in the retrospective group (the markedly effective rate: 45.60% vs 21.90%; the total effective rate: 96.80% vs 86.10%), showing statistical difference (P < 0.01). Results of clinical study on concurrent control showed that the hospital stay was significantly shorter in the pathways group than in the control group (11.19 days vs 13.21 days), showing statistical difference (P < 0.05). The average total cost of hospitalization was significantly lower in the pathways group than in the control group (yen 8 656.80 vs yen 11 609.70), showing statistical difference (P < 0.01). As for clinical efficacy of Chinese medical syndrome, the total effective rate was higher in the pathways group than in the control group (97.10% vs 93.62%), showing statistical difference (P < 0.05). The markedly effective rate of heart function was better in the pathways group than in the control group, showing statistical difference (49.30% vs 38.30%, P < 0.05). The overall satisfaction was higher in the pathways group than in the conventional group (P < 0.01). There was no statistical difference in the mortality within 3 months after discharge from hospital, and the readmission rate due to heart failure between the two groups (P > 0.05). But there was statistical difference in the quality of life (P < 0.05). CONCLUSION: The pathway could shorten the hospitalization time, decrease the cost of hospitalization, improve the clinical efficacy, improve patients' quality of life and satisfaction, therefore, it could be spread nationwide.

Effects of salvianolic acid and notoginseng triterpenes on angiogenesis in EA-hy926 cells in vitro.

AIM: To investigate the different effects of salvianolic acid and notoginseng triterpenes on proliferation, angiogenesis and expression of vascular endothelial growth factor in EA-hy926 cells in vitro. METHODS: EA-hy926 cells were cultured in vitro. Salvianolic acid and notoginseng triterpenes at concentrations of 0.4, 0.8 and 1.2 mg·L(-1) were used to culture EA-hy926 cells. EA-hy926 cells in a blank control group were grown in culture solution only. Viability of cells was assessed by CCK-8, and after treated for 12 h, capillary-like structures were examined. After 24 h culture, the expression of VEGF was detected by real-time PCR. RESULTS: Salvianolic acid at 0.4, 0.8 mg·L(-1), the same as notoginseng triterpenes, increased VEGF content in EA-hy926 cells. Expression of VEGF protein in the salvianolic acid at 1.2 mg·L(-1) group, was up-regulated as compared with notoginseng triterpenes group (P < 0.05). CONCLUSION: Salvianolic acid and notoginseng triterpenes can promote EA-hy926 cell proliferation, angiogenesis and expression of VEGF protein. This analysis also provided evidence that salvianolic acid had the better effects as compared with notoginseng triterpenes.

[An epidemiological investigation on a food-born outbreak of noroviru caused by Sydney 2012 G II.4 strain].

OBJECTIVE: To identify the source of infection, route of transmission and risk factors related to a cluster of acute gastroenteritis cases in a university of Guangzhou. METHODS: Cases were identified according to the definition. Descriptive epidemiological approaches and case-control study designs were employed in the analysis. All the samples were tested for norovirus by RT-PCR. Positive samples were subjected to both nucleotide sequence and homology analysis. RESULTS: A total of 141 cases related to norovirus gastroenteritis were identified in January 8 to 21, 2013, with the attack rate as 8.5 per thousand (141/16,600). The peak in morbidity was seen on January 8 to 9. No clustering was found in different classes or dormitories. Results from the case-control study revealed that early cases were infected in Restaurant A (OR = 3.46, 95% CI: 1.07-11.16) and the cold shredded chicken set meal (OR = 17.82, 95% CI: 4.46-78.17) served at lunch (OR = 4.34, 95% CI: 1.18 -17.37) on January 7 was under suspicion. A total of 266 samples, including rectal swabs from the patients and kitchen wokers, leftover food and environmental swabs, were collected. Twenty-one samples (collected from 17 persons) were positive for norovirus by RT-PCR. About 29.6% (8/27) of the kitchen workers in the Restaurant A were tested positive for the virus. The pathogen was identified as the new norovirus genotype II.4 variant, termed Sydney 2012. The virus strains isolated from the patients among student and staff and the kitchen workers were 100% identical in their nucleotide sequence. CONCLUSION: This was the first reported acute gastroenteritis outbreak caused by the new norovirus genotype II.4 variant, Sydney 2012, which showed that the food was contaminated by the asymptomatic kitchen workers who carried the virus.

[A case-control study of an influenza A (H1N1) outbreak in a hospital].

OBJECTIVE: This study aimed to explore the epidemiological factors of an influenza A (H1N1) outbreak in a hospital. METHODS: General data were collected via face-to-face interview and telephone survey. Total 132 individuals including medical and nursing staffs (37), in-patients (39) and patients' family members (56) who were exposed to the pediatric surgery ward during August 11 - 18, 2009, were investigated. The case group included 35 cases according to the diagnostic criteria for influenza A (H1N1). The other 97 persons were grouped as control. A case-control study was then conducted to explore the epidemic factors, and layering analysis was applied to determine the interactions among these factors. RESULTS: The overall incidence in this study was 26.5% (35/132), which included 12 confirmed and 23 suspected cases, and there was no severe case. The first case was a child with the influenza-like symptoms before admission on August 11. The onsets of these cases were during August 7 - 17. The cases were distributed in 9 of 13 rooms, and there was no room aggregation in the cases distribution (χ(2) = 0.00, P > 0.05). Twelve of 25 oropharyngeal swabs were influenza A (H1N1) nucleic acid positive. The case-control study showed that exposure to the enema room accounted for 93.10% (27/29) in cases and 72.73% (48/66) in control; OR = 5.06, 95%CI = 1.01 - 34.23), long time exposure to ward was 71.43% (25/35) in cases and 44.33% (43/97) in control; OR = 3.14, 95%CI = 1.27 - 7.90), and short distance contact with the nurse LIU (76.46% (26/34) in cases and 50.52% (49/97) in control; OR = 3.18, 95%CI = 1.22 - 8.54) were the risk factors. However, keeping the window open (27.59% (8/29) in cases and 68.18% (45/66) in control; OR = 0.14, 95%CI = 0.05 - 0.39) and hand washing (25.71% (9/35) in cases and 76.29% (74/97) in control; OR = 0.11, 95%CI = 0.04 - 0.28) were the protective factors. The longer time exposure to ward had the higher risk (ratios of cases to control were 4:20 (0 - 1 day), 6:34 (2 - 4 days) and 25:43 (≥ 5 days); χ(2)(trend) = 5.737, P < 0.05). In contrast, hand washing with more frequencies (ratios of cases to control were 26:23 (0 - 1 time one day), 7:9 (2 - 3 times one day) and 2:65 (≥ 4 times one day); χ(2)(trend) = 37.136, P < 0.01) and the longer time window opening (ratios of cases to control were 21:21 (no), 4:13 (a few) and 4:32 (often); χ(2)(trend) = 13.830, P < 0.01) had the lower risk. Nevertheless, layering analysis excluded long time exposure to ward from the risk factors (for individuals with more frequent hand washing, 6.90% (2/29) exposed in cases, 7.14% (1/14) exposed in control, OR = 0.97, 95%CI = 0.06 - 29.51; for individuals keeping window open, 21.21% (7/33) exposed in cases, 8.33% (1/12) exposed in control, OR = 2.55, 95%CI = 0.26 - 60.87), indicating the main risk factors in this outbreak were exposure to the enema room and short distance contagion with the infected nurse. CONCLUSION: The influenza A (H1N1) outbreak in this hospital was induced by an inpatient infected with influenza A (H1N1) virus before admission. Infected medical staffs keeping on work and exposure to the same place, e.g.the enema room in this study might spread the influenza A (H1N1) virus, and frequent hand washing and keeping the window open are the most effective and economic methods to prevent influenza A (H1N1) infection.