[A new mediation analysis method for multiple mediators].

Mediation analysis is mainly used to explore the causal mechanism between independent variable X and dependent variable Y. It determines whether mediator M plays a role and evaluate the role's degree in the causal path by decomposing the causal path between the independent variable X and the dependent variable Y. However, the classical mediation analysis is generally used for single mediator. This paper introduces a new mediation analysis method for multiple mediators.

[Application of parametric g-formula in causal analysis].

At present, traditional methods on statistics have limitations in controlling time- varying confounding. This paper introduces an analysis method, parametric g-formula, which would adjust time-varying confounding, and also exemplifies the steps of its implementation for purpose to provide a new reference for researchers to deal with long-term observational data.

[DNA methylation modification of BRMS1 in triple-negative breast cancer and its correlation with tumor metastasis].

Objective: To investigate the effect of methylation status of breast cancer metastasis suppressor gene 1 (BRMS1) on the expression of breast cancer and the biological behavior of cancer cells in triple-negative breast cancer (TNBC). Methods: The expression of BRMS1 in TNBC tissues and corresponding non-malignant tissues and its relationship with clinicopathological parameters were detected by immunohistochemistry. The mRNA and protein expression of BRMS1 in normal breast epithelial cells and TNBC cells were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. The methylation specific polymerase chain reaction (MSP) was used to detect the methylation status of BRMS1 in each cell. These cells were treated with demethylated preparations (5-Aza-dC) to re-activate BRMS1 expression. Using tumor cell invasion assay to detect influence of BRMS1 demethylation on the invasion capacity of cancer cells. The data were statistically analyzed. Results: The positive expression rate of BRMS1 protein in TNBC tissues was significantly lower than that in corresponding non-malignant tissues (χ(2)= 6.635, P<0.05). The mRNA expression level of BRMS1 in patients with lymph node metastasis was significantly lower than those with no lymph node metastasis (P=0.018). The down-regulation of BRMS1 expression was related to the methylation of DNA promoter, which was statistically significant (χ(2)=14.68, P<0.05). The mRNA and protein expression of BRMS1 was also correlated with tumor size and TNM staging (P=0.000-0.003). After using 5-Aza-dC, the number of cells with invasive capacity was significantly lower than those of the control group (t=3.262-10.72, P<0.05). Conclusions: The decrease of BRMS1 expression in TNBC cells is related to the methylation of DNA. Demethylation can inhibit the invasion of breast cancer cells.

[Analysis of clinical characteristics and factors associated with short term outcomes in early term neonates].

Objective: To investigate the clinical characteristics of early term and full term neonates, and analyze the risk factors associated with short term outcomes in early term neonates. Method: Neonates with birth weight (BW) ≥2 500 g from year 2013 were analyzed retrospectively based on American Congress of Obstericians & Gynecologists (ACOG) latest definition of term infants. According to inclusion and exclusion criteria, early term (gestational age 37-38 weeks) and full term(gestational age 39-40 weeks) neonates were included, whose morbidity constituent proportion was analyzed by χ(2) test or Fisher accuracy test or t test or Wilcoxon test. Risk factors associated with short term outcomes in early term population were analyzed by Logistic regression analysis. Result: There were 3 002 discharged term infants being investigated, among whom 1 303 cases were included(768 males and 535 females), and 37, 38, 39 and 40 weeks' gestational age newborns were 160, 324, 450 and 369 respectively. Compared with full term neonates(n=819), early term neonates (n=484) had longer length of hospital stay (LOS)(6.0(5.0, 9.0) vs. 6.0(4.0, 8.0), Z=2.830, P=0.005), higher usage rate of intravenous antibiotics(86.4%(418/484) vs. 80.1%(656/819), χ(2)=8.009, P=0.005), higher assisted ventilation rate(9.5%(46/484) vs. 2.9%(24/819), χ(2)=25.528, P<0.01), higher pulmonary surfactant administration rate(4.3%(21/484) vs. 1.1%(9/819), χ(2)=14.006, P<0.01), as well as higher hypoglycemia incidence(3.9%(19/484) vs. 1.2%(10/819), χ(2)=10.226, P=0.001). There were no statistically significant differences in 1 min Apgar score (9(9, 10)vs. 9(9, 10), Z=0.860, P=0.390), 5 min Apgar score (10(9, 10) vs. 10(9, 10), Z=0.810, P=0.418), white blood cell count (15 (11, 21) ×10(9) /L vs.15 (11, 22) ×10(9) /L, Z=0.880, P=0.379), hemoglobin count(180 (159, 205) vs. 182 (160, 204) g/L, Z=0.560, P=0.576), or platelet count(303(234, 372) ×10(9)/L vs. 301(237, 391) ×10(9)/L, Z=0.550, P=0.584). BW between 2 500 g and 2 999 g(OR 1.69, 95% CI: 1.10-2.62, χ(2) =5.614, P=0.018), wet lung(OR=2.61, 95% CI: 1.61-4.24, χ(2)=15.023, P=0.000)and pneumonia(OR 1.88, 95% CI: 1.14-3.08, χ(2)=6.192, P=0.013) were risk factors in early term neonates' short term adverse outcomes. Conclusion: Early term newborns are still at their "immature" state, and respiratory disorders are major risk factors associated with short term outcomes. Hence, early delivery during 37-38 weeks should be avoided as possible as we can.

Imaging of the female urethral diverticulum.

Female urethral diverticulum is a localized out-pouching of the urethra that is becoming increasingly prevalent, but often poses a diagnostic challenge. Traditionally, conventional voiding cystourethrography has been used to make the preoperative diagnosis. With the development of higher-resolution images acquired through ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI), the anatomy and various abnormalities of the female urethra can be better elucidated. This article focuses on the imaging features of female urethral diverticulum, with emphasis on diagnostic pearls, particularly using MRI. Female urethral diverticulum can be best identified by their location in the posterolateral urethra and by their communication with the urethral lumen. Improved imaging techniques combined with increased physician awareness of urethral diverticulum will lead to more prompt and accurate diagnosis of this entity, leading to better treatment of affected patients.

Predictors of infectious complications after burn injuries in children.

BACKGROUND: Infections are the major life-threatening complication of burn injury and occur with the greatest frequency in children. Knowledge of their occurrence and management, however, is extrapolated from studies in adults. We performed a prospective study of infectious complications in burned children. OBJECTIVE: To delineate epidemiology, risk factors and microbiology of infections in burned children where burn care and surgical interventions are optimal. METHODS: Children hospitalized for burns were entered into prospective study. Characteristics of the burn injury were assessed, and active surveillance for infections was performed. RESULTS: Seventy patients were entered [mean age, 42 months; mean total body surface area (TBSA), burn 15%]. Twenty-seven percent of patients developed 39 infections: 13 involved the burn wound (burn wound sepsis, 6; graft loss, 5; and cellulitis, 2); 13 were catheter-associated septicemia; 13 involved other sites (i.e. pneumonia, 4; urinary tract infection, 3; bacteremia, 2; endocarditis, 1; myocardial abscess, 1; toxin-mediated syndrome, 1; and otitis media, 1). Twenty-three infections were caused by a single organism, 9 infections by more than 1 organism and in 7 infections defined by CDC criteria no organism was recovered. Organisms causing infection were: Staphylococcus aureus, 19; Candida albicans, 4; Pseudomonas aeruginosa, 4; coagulase-negative Staphylococcus, 4; Enterococcus sp., 3; Escherichia coli, 1; Klebsiella oxytoca, 1; Serratia marcescens, 1; Streptococcus pneumoniae, 1; Streptococcus pyogenes, 1; Aspergillus fumigatus, 1; and Candida parapsilosis, 1. Burn mechanism (flame and inhalation), extent (TBSA >30%) and depth (full thickness) were risk factors for infection; young age and site of burn were not. CONCLUSION: The most common infections occurring in burn children are burn wound infections and catheter-associated septicemia. Characteristics of burn injury predict risk of infection. Children with flame and inhalation injury, TBSA burned >30% and full thickness burns are at high risk of infectious complications.

In vitro susceptibility testing of topical antimicrobial agents used in pediatric burn patients: comparison of two methods.

One hundred and seventy-seven bacterial isolates obtained from pediatric burn victims were tested for in vitro susceptibility against bacitracin, silver sulfadiazine, mafenide acetate, nitrofurazone, and mupirocin by two methods: standard microbroth dilution and Nathan's agar well diffusion (NAWD). Nitrofurazone had the broadest spectrum of activity. Mupirocin was the most potent agent against methicillin-susceptible Staphylococcus aureus. Silver sulfadiazine showed activity against gram-positive organisms and higher minimum inhibitory concentration (MIC) values, and smaller zone sizes were seen for methicillin-resistant S. aureus and gram-negative bacilli. Bacitracin showed activity against S. aureus and Streptococcus pyogenes by the microbroth method; activity could not be assessed by NAWD. Mafenide acetate had the highest MICs for all isolates tested. Correlation between methods for all isolates tested was best for mupirocin and nitrofurazone. NAWD was labor intensive and difficult to interpret; MIC method was easy to perform and reproducible. Clinical correlation is necessary to establish breakpoints for interpretation of test results.

Study of antibiotic prophylaxis during burn wound debridement in children.

Twenty-three children completed a randomized, prospective, partially blinded study performed to assess the need and effectiveness of antibiotic prophylaxis at the time of burn wound debridement and grafting. Patients with a total body surface area (TBSA) burn less than 35% were randomized to receive cefazolin or placebo. Patients with burns of 35% or more TBSA were randomized to receive cefazolin or targeted antibiotics based on surveillance cultures. Blood cultures were obtained at commencement, immediately after, and 24 hours after surgical debridement. Quantitative cultures and histologic examination of biopsied burn wounds were performed. Burn wound infection occurred in three patients with burns of less than 35% TBSA, two in the cefazolin group and one in the placebo group. Quantitative tissue cultures and histologic examination did not predict either infection. During the four procedures in three patients with 35% or more TBSA, three were randomized to receive cefazolin, and one targeted antibiotics. All receiving cefazolin developed burn wound infection. Quantitative tissue culture was more than 10(5) colony-forming units per gram in all, whereas histologic examination was positive in one. In our patients with less than 35% burn, cefazolin was not necessary, and in those with 35% or more burn, it was not effective.

Intravenous immunoglobulin prophylaxis of cytomegalovirus infection in pediatric renal transplant recipients.

Cytomegalovirus (CMV), the most significant infectious cause of morbidity following renal transplantation, may be a greater problem for children than for adults due to their relative lack of experience with this virus. Therefore, we prospectively gave Gammagard as prophylaxis to CMV-negative children who received CMV-positive allografts and compared the results to our experience with similar high-risk recipients transplanted prior to our use of intravenous immunoglobulin G (IvIgG). Symptomatic CMV disease developed in 17% of the IvIgG recipients as compared with 71% of the untreated patients (p = 0.01). The CMV infections that did occur in IvIgG recipients developed significantly later than in untreated children (median time of onset after transplantation 2.60 vs. 1.35 months; p < 0.05) and generally were less severe, although 1 IvIgG recipient died despite prophylaxis. IvIgG administration did not affect the frequency of rejection or graft or patient survival. We conclude that IvIgG administration to high-risk pediatric renal transplant recipients may protect against posttransplantation CMV disease and may lessen the severity of infections that do develop in patients who receive it.