OBJECTIVEThe growth and repair potential of three typical microorganisms in reclaimed water after UV disinfection was investigated to assess the effects of photo-reactivation and dark repair of microorganisms, and the microbial safety of reclaimed water following this procedure.

METHODSThe growth and repair potential of Escherichia coli, a fecal coliform strain and Bacillus subtilis in the effluent of a biological wastewater treatment plant disinfected by a low-pressure UV lamp were investigated.

RESULTSAny increase in bacterial numbers in the effluent after UV disinfection was due to damage repair. Exposure to photo-reactivating light for 8-10 h after UV irradiation with a dose of 5 mJ/cm(2), the highest percentage of photo-reactivation observed for E. coli and the fecal coliform strain was 29% and 15% respectively. B. subtilis showed little photo-reactivation under these conditions. The percentage of photo-reactivation was related to the UV dose and the photo-reactivating time, and a function was developed to forecast the final concentrations of E. coli and the fecal coliform strain after UV disinfection with possible photo-reactivation.

CONCLUSIONDifferent species of bacteria displayed different responses to UV light and different repair potentials. The repair of indigenous bacteria in wastewater needs to be investigated in future work.

Bacillus subtilis ; radiation effects ; Dose-Response Relationship, Radiation ; Escherichia coli ; radiation effects ; Time Factors ; Ultraviolet Rays ; Waste Disposal, Fluid ; Water Microbiology ; Water Purification

Objective: This study aimed to investigate the correlation between supraventricular tachycardia (SVT) and tachycardia-induced cardiomyopathy(TIC) in children and assess the risk factors for the development of TIC. Method: One hundred and eighty-three patients were recruited in four hospitals of Beijing diagnosed as SVT were divided into two groups depending on whether or not complicated with TIC. The age, gender, tachycardia type, ventricular rate during tachycardia, frequency of tachycardia episodes and duration of tachycardia were compared between the two groups and risk factors associated with TIC were analyzed. Statistical analyses were performed using t test, Mann-Whitney U and χ² test. Result: Totally 183 patients were included in this study (paroxysmal supraventricular tachycardia, PSVT, n=149; atrial tachycardia, AT, n=34). The incidence of TIC was 13.1%. There was significant difference regarding the incidence of TIC between children with AT and children with PSVT (26.5% vs. 10.1%, χ²=6.537, P=0.011). The percentage of AT in patients with TIC was significantly higher than patients without TIC (37.5% vs. 15.7%, χ²=6.537, P=0.011). Patients with TIC had a higher frequency of tachycardia episodes(2.5(1.0-4.8) beats/year vs 4.0(1.0-10.0) beats/year, Z=-2.223, P=0.026)and longer duration of tachycardia(11.0(1.1-36.0) h vs 2.5(1.0-12.0) h, Z=-2.154, P=0.031)compared with patients without TIC. Multivariate predictors of TIC was longer duration of tachycardia (OR=2.041, P=0.028). Conclusion TIC occurs in 13.1% of children with SVT. The incidence of TIC in children with AT is higher than in children with PSVT. Risk factor for the development of TIC is longer duration of tachycardia.

Objective: The study assessed the clinical characteristics and response to acute intravenous antiarrhythmic drug therapy of supraventricular tachycardia (SVT) in children. Methods: This was a multicenter prospective descriptive study including 257 children from First Hospital of Tsinghua University, Peking University First Hospital, Children's Hospital Affiliated to Capital Institute of Pediatrics and Beijing Anzhen Hospital who received intravenous antiarrhythmic drug therapy for SVT from July 2014 to February 2017. The clinical and tachycardia features, response to intravenous antiarrhythmic drug therapy of these children were characterized. Statistical analyses were performed using t test, Mann-Whitney U test, χ² test and H test. Results: The onset of SVT occurred at any age with a distribution with positive skewness, 57.6% (n=148) children<1 year, 17.5% (n=45) children1~<3 years, 10.5% (n=27) children 3~<6 years and 14.4% (n=37) children ≥ 6 years of age. The percentages of SVT types were 49.4% (n=127) for atrioventricular reentry tachycardia (AVRT), 4.3% (n=11) for atrioventricular nodal reentry tachycardia (AVNRT), 26.8% (n=69) for unclassified paroxysmal SVT and 19.5% (n=50) for atrial tachycardia (AT), respectively. Tachycardia-induced cardionyopathy (TIC) secondary to SVT developed in 30 of 225 (13.3%). Left ventricular ejection fraction (LVEF) of the 27 children attacked by TIC returned to normal after successful control of SVT (41.1%±6.3% vs. 60.3%±9.2%, t=-10.397, P=0.000). Complete termination of SVT by antiarrhythmic drugs was achieved in 164 of 257 (63.8%), partial termination rate was 18.7% (48 of 257) and failure to terminate rate was 17.5% (45 of 257). Propafenone (complete cardioversion in 98 (73.1%) of 134) and amiodarone (complete cardioversion in 23 (76.7%) of 30) showed better efficacy for SVT termination than adenosine (complete cardioversion in 26 (44.1%) 59) (χ²=20.524, P=0.000). Paroxysmal SVT had a higher termination rate on pharmacological therapy than AT (67.1% vs. 50.0%, χ²=6.337, P=0.042). Patients of different age groups had significantly different response to antiarrhythmic therapy (χ²=13.904, P=0.031). Children<1 year of age showed the least response to antiarrhythmic drug therapy with complete termination in 51 (55.4%) of 92. Adverse effects occurred in 9 patients (3.5%): Four patients had severe hypotensive shock using propafenone (n=3) and adenosine (n=1), and 3 patients had sinus arrest using adenosine. Conclusion Most (57.6%) children with SVT have their first clinical episode within 1 year of age, and AVRT is the most common type. TIC occurs in 13.3% of children with SVT. Intravenous antiarrhythmic drug therapy has a 63.8% complete termination rate for children with SVT and incidence of adverse effects is 3.5%. Propafenone and amiodarone are more effective for SVT termination in children than adenosine. Serious adverse effects may occur when using propafenone.

Objective: To investigate the impact of immediate cessation of antiviral therapy on postpartum liver function and the factors influencing postpartum abnormality in mothers with chronic hepatitis B virus infection. Methods: A retrospective cohort study was conducted. One hundred eighty-eight pregnant women with HBV DNA level > 2×106 IU/ml were enrolled from June 2014 to June 2018. Demographic information and clinical data of liver function and HBV DNA load during gravidity, intrapartum and postpartum period were collected. According to the antiviral treatment recommendations during pregnancy, the women were divided into three groups, namely, tenofovir (TDF), telbivudine (LdT) and control group. Liver function abnormalities among the three groups were compared within 6 months after delivery, and the factors influencing abnormal liver function were analyzed by unconditional logistic regression. Results: Of the 188 cases, 72 cases were in the TDF group, 80 cases in the LdT group, and 36 cases in the control group. Pregnant women in the TDF and LdT groups received oral TDF (300 mg/d) and LdT (600 mg/d) from 28 ± 4 weeks of gestation till delivery. Among the 188 patients, 30 (16.0%) had abnormal postpartum liver function abnormality. The incidence of postpartum liver function abnormality [alanine aminotransferase (ALT) > 2 × upper limit of normal (ULN)] in the TDF, LdT, and control groups was 19.4%, 12.5%, and 16.7%, respectively. The postpartum peak levels of ALT (median, range) in the three groups were 34.5 (12.0-946.0) U/L, 37.5 (12.0-733.8) U/L, and 39.0 (7.0-513.0) U/L, respectively. There was no significant difference between the two indexes among the three groups (P > 0.05). There was no statistically significant difference in the degree of postpartum liver function abnormalities between the three groups (P = 0.944). Most of the liver function abnormalities were mild to moderate (2 × ULN≤ALT < 10 × ULN), and usually resolved spontaneously or by treatment. Univariate and multivariate analysis showed that baseline ALT level during pregnancy was an independent factor associated with postpartum liver function abnormality (OR = 1.031, CI 95%: 1.005-1.058; χ² = 5.340, P = 0.021), whereas age, antiviral therapy, HBeAg-positivity, baseline HBV DNA levels, gravidity, parity, preterm delivery and delivery mode were not significantly associated with postpartum liver function abnormality. Conclusion Cessation of antiviral therapy after delivery did not significantly increase the risk of postpartum liver function abnormality in pregnant women with chronic HBV infection. The ALT level during pregnancy is a factor influencing postpartum liver function abnormality.