[Clinical analysis of 4 children with cryptogenic organizing pneumonia]

Objective: To analyze the clinical features of children with cryptogenic organizing pneumonia (COP) confirmed by pathology. Methods: The clinical manifestations, imaging, pathology, treatment and outcome data of 4 children with COP confirmed by thoracoscopic lung biopsy were retrospectively analyzed, who were hospitalized at Respiratory Department of Shenzhen Children's Hospital from January 2004 to December 2022. Results: All of the 4 patients were male, the age ranged from 1 year 3 months to 14 years. The time from onset to diagnosis was 3 months to 3 years. The follow-up duration was 6 months to 6 years. All the 4 cases had cough, 2 cases had tachypnea and wheezing, 1 case had expectoration, 1 case had chest pain, 1 case had decreased activity tolerance and weight loss. Rales in 2 cases and hypoxemia in 1 case. Pulmonary high resolution CT showed diffuse distribution, involvement of both lungs in 3 cases, and single lung combined migration in 1 case.Three cases showed ground-glass opacity, consolidation, patchy or fibrous strips, and 1 case presented air bronchogram and "reversed halo sign". All the 4 cases were performed thoracoscopic lung biopsy, and the pathological findings showed cellulose exudate or small nodules filled with granulation tissue or fibroblasts in the alveolar cavity and small airways, and 1 case was Masson corpuscle positive. Three patients achieved remission after glucocorticoid therapy. Spontaneous remission without treatment was seen in 1 patient.Two cases were followed up for 17 months and 6 years, respectively, who had excellent outcome. Conclusions: The manifestations of COP in children include cough, expectoration and chest pain. Infants and young children may have tachypnea and wheezing. The most common chest CT findings are diffuse distribution of ground-glass opacity, patchy and consolidation in both lungs. Diagnosis should depend on pathological examination. The effect of glucocorticoid therapy is good.

[Analysis of the current status and related factors of human papillomavirus infection among community-dwelling women aged 18-24 years without a history of vaccination in Shanghai City]

Objective: To understand the status of human papillomavirus (HPV) infection among young women without a history of vaccination in Shanghai, and analyze the related factors of HPV infection in this population. Methods: A total of 2 660 women aged 18-24 years old who had made an appointment for HPV vaccine at 36 community health service centers in Shanghai from July 2022 to February 2023 were selected as the study subjects. Basic information (including demographic characteristics, previous disease history, female menstrual and reproductive history, sexual life history, etc.) was collected by a self-filling electronic questionnaire. Cervical secretions were detected by HPV nucleic acid typing. The multivariate logistic regression model was used to analyze the factors related to high-risk HPV (HR-HPV) infection in the target population. Results: The age of the subjects was (23±1) years old, and the infection rate of HPV was 14.51% (386 cases), among which the infection rates of HR-HPV and low-risk HPV were 13.53% (360 cases) and 1.84% (49 cases), respectively. The main subtypes of HR-HPV infection were HPV52, 16, 58, 39 and 66. The multivariate logistic regression model analysis showed that compared with the control group, the OR (95%CI) values for HR-HPV infection in the group of married, earned less than 2 000 yuan/month, drank alcohol occasionally, gynecological disease history, had two or more sexual partners in the past year, and did not know whether the partners had other sexual partners were 0.41 (0.25-0.66), 0.39 (0.21-0.70), 1.45 (1.13-1.86), 1.29 (1.00-1.66), 2.18-5.18 (1.02-16.05), and 1.82 (1.31-2.54), respectively. Conclusion: The infection rate of HPV among women aged 18-24 years old in Shanghai remains at a high level. The main subtypes of HR-HPV infection are HPV52, 16, 58, 39 and 66. The marital status, economic income level, drinking status, gynecological disease history and sexual life history are related to HR-HPV infection.

[To compare the efficacy and incidence of severe hematological adverse events of flumatinib and imatinib in patients newly diagnosed with chronic phase chronic myeloid leukemia]

Objective: To analyze and compare therapy responses, outcomes, and incidence of severe hematologic adverse events of flumatinib and imatinib in patients newly diagnosed with chronic phase chronic myeloid leukemia (CML) . Methods: Data of patients with chronic phase CML diagnosed between January 2006 and November 2022 from 76 centers, aged ≥18 years, and received initial flumatinib or imatinib therapy within 6 months after diagnosis in China were retrospectively interrogated. Propensity score matching (PSM) analysis was performed to reduce the bias of the initial TKI selection, and the therapy responses and outcomes of patients receiving initial flumatinib or imatinib therapy were compared. Results: A total of 4 833 adult patients with CML receiving initial imatinib (n=4 380) or flumatinib (n=453) therapy were included in the study. In the imatinib cohort, the median follow-up time was 54 [interquartile range (IQR), 31-85] months, and the 7-year cumulative incidences of CCyR, MMR, MR(4), and MR(4.5) were 95.2%, 88.4%, 78.3%, and 63.0%, respectively. The 7-year FFS, PFS, and OS rates were 71.8%, 93.0%, and 96.9%, respectively. With the median follow-up of 18 (IQR, 13-25) months in the flumatinib cohort, the 2-year cumulative incidences of CCyR, MMR, MR(4), and MR(4.5) were 95.4%, 86.5%, 58.4%, and 46.6%, respectively. The 2-year FFS, PFS, and OS rates were 80.1%, 95.0%, and 99.5%, respectively. The PSM analysis indicated that patients receiving initial flumatinib therapy had significantly higher cumulative incidences of CCyR, MMR, MR(4), and MR(4.5) and higher probabilities of FFS than those receiving the initial imatinib therapy (all P<0.001), whereas the PFS (P=0.230) and OS (P=0.268) were comparable between the two cohorts. The incidence of severe hematologic adverse events (grade≥Ⅲ) was comparable in the two cohorts. Conclusion: Patients receiving initial flumatinib therapy had higher cumulative incidences of therapy responses and higher probability of FFS than those receiving initial imatinib therapy, whereas the incidence of severe hematologic adverse events was comparable between the two cohorts.

[Association between gestational diabetes mellitus and preterm birth subtypes]

Objective: To investigate the association between gestational diabetes mellitus (GDM) and preterm birth subtypes. Methods: Based on the cohort of pregnant women in Anqing Prefectural Hospital, the pregnant women who received prenatal screening in the first or second trimesters were recruited into baseline cohorts; and followed up for them was conducted until delivery, and the information about their pregnancy status and outcomes were obtained through electronic medical record system and questionnaire surveys. The log-binomial regression model was used to explore the association between GDM and preterm birth [iatrogenic preterm birth, spontaneous preterm birth (preterm premature rupture of membranes and preterm labor)]. For multiple confounding factors, the propensity score correction model was used to compute the adjusted association. Results: Among the 2 031 pregnant women with a singleton delivery, the incidence of GDM and preterm birth were 10.0% (204 cases) and 4.4% (90 cases) respectively. The proportions of iatrogenic preterm birth and spontaneous preterm birth in the GDM group (n=204) were 1.5% and 5.9% respectively, while the proportions in non-GDM group (n=1 827) were 0.9% and 3.2% respectively, and the difference in the proportion of spontaneous preterm birth between the two groups was significant (P=0.048). Subtypes of spontaneous preterm were further analyzed, and the results showed that the proportions of preterm premature rupture of membranes and preterm labor in the GDM group were 4.9% and 1.0% respectively, while the proportions in the non-GDM group were 2.1% and 1.1% respectively. It showed that the risk of preterm premature rupture of membranes in GDM pregnant women was 2.34 times (aRR=2.34, 95%CI: 1.16-4.69) higher than that in non-GDM pregnant women. Conclusions: Our results showed that GDM might increase the risk of preterm premature rupture of membranes. No significant increase in the proportion of preterm labor in pregnant women with GDM was found.

[Clinical characteristics of acute occupational poisoning caused by carbon dioxide leakage from a cargo ship]

Carbon dioxide is a simple asphyxial gas, with low concentrations having an excitatory effect on the respiratory center, while high concentrations have an inhibitory effect on the respiratory center. Simple carbon dioxide poisoning is rarely seen clinically. This article reviews and analyzes the treatment process of 9 cases of acute inhalation carbon dioxide poisoning in a cargo ship carbon dioxide leakage accident in May 2019, summarizes clinical treatment experience, and provides timely and effective treatment for acute pulmonary edema caused by acute inhalation carbon dioxide poisoning. In particular, the application of hormones has a good prognosis, improving clinicians' understanding of the disease.

[The directionality of measurement bias: a directed acyclic graph-based structural perspective]

Measurement bias (MB) has been described in causal structures but is still not entirely clear. In practice, the correctness of substitution estimate (SE) of effect is a prerequisite for causal inference, usually based on a bidirectionally non-differential misclassification between the measured exposure and the measured outcome. Based on a directed acyclic graph (DAG), this paper proposes a structure for the single-variable measure, where its MB is derived from the choice of an imperfect, "input/output device-like" measurement system. The MB of the SE is influenced both by the measurement system itself and by factors outside the measurement system: while the independence or dependence mechanism of the measurement system still ensures that the MB of the SE is bidirectionally non-differential; however, the misclassification can be bidirectionally non-differential, unidirectionally differential, or bidirectionally differential resulted from the factors outside the measurement system. In addition, reverse causality should be defined at the level of measurement, where measured exposures can influence measured outcomes and vice versa. Combined with temporal relationships, DAGs help elucidate MB's structures, mechanisms, and directionality.

[The event of acute hepatitis of unknown etiology in children]

Recently, the cases of acute hepatitis of unknown etiology (AHUE) in children worldwide have been increasing continuously and rapidly, involving more than 396 cases in 26 countries, and global public health actions, including surveillance, health alerts, research, are being implemented. AHUE mainly affects immunocompetent children with typical acute hepatitis, which can be severe and require liver transplantation. There are few systematic studies at present; the risk factors are unknown, the etiology remains to be established, and the clinical features and pathogenesis remain elucidated. It is urgent to strengthen the monitoring and research of AHUE cases.

[Proportion and rate: connotation and understanding route]

Proportion and rate have multiple and overlapping meanings, which blur their concepts. Based on the existence of the states and the occurrence of the events and their measuring process, we first put forward the concept of "cumulative number of states in point time". Considering the general meaning of "rate" in mathematics and the units of the elements in indexes, this paper puts forward the concept of "the change of cumulative number of states in point time", which is equal to the commonly acknowledged concept "number of incident event within observation period" or "absolute rate", and further constructs relative rate and proportion. Proportions can be classified into three types: time-point (or rate-type) constitutional proportion, time-period incidence proportion and their synthesis, time-period constitutional proportion. The essential difference between relative rate and time-period proportions is whether the observation period is regarded as a one-unit-length fixed period which would be further moved to the description of the indexes. Furthermore, the sources populations of relative rate and proportions are exclusively those at the beginning of the observation period. Thus, we established a unified identification route about ratios, proportions, and rates, the basic indicators of categorical data in populations. These are applicable to both fixed and dynamic populations. The paper aims to clarify the connotation of the indexes and the feasible understanding route and provide some reference for the population researchers.

[Observation and experiment: a causal perspective]

Observation and experiment and their related connotations and concepts remain vague, which affects the correct understanding of research design and the judgment of the validity of causal inference. This article borrows the concept of phase transition in physics, combines causal thinking and causal diagrams, firstly establishes the relationships among the attribute, state, event, and phenomenon, and then identifies two ways with the opposite causal structures to acquire phenomena-human observations and human manipulated experiments. In causal inference, the ways mentioned above, intervention and assignment of exposure are affected by their own causal mechanisms. Finally, intervention is a causal concept, a core link among known phenomena, unknown phenomena available for measurement, and natural causality. Based on this, the two strategies in classifying research design are analyzed, and intervention method and non-intervention method are proposed, as is comprehensive and concise. Observations and experiments provide the basis for all scientific knowledge and should be viewed as concepts with a unified connotation. The accurate classification of research designs based on the law of causality and measurement process may be one of the best options worthy of in-depth study.

[A multicenter retrospective study on the etiology of necrotizing pneumonia in children]

Objective: To investigate the etiology of necrotizing pneumonia (NP) in children and the clinical characteristics of NP caused by different pathogens in China. Methods: A retrospective, case-control study was performed in children with NP who were admitted to 13 hospitals in China from January 2008 to December 2019. The demographic and clinical information, laboratory data, etiological and radiological findings were analyzed. The data were divided into three groups based on the following years: 2008-2011, 2012-2015 and 2016-2019, and the distribution characteristics of the pathogens in different period were compared. Meanwhile, the pathogens of pediatric NP in the southern and northern China were compared. And the clinical characteristics of the Mycoplasma pneumoniae (MP) NP and the bacterial NP were also compared. T-test or Mann-Whitney nonparametric test was used for comparison of numerical variables, and χ² test was used for categorical variables. Results: A total of 494 children with NP were enrolled, the median ages were 4.7 (0.1-15.3) years, including 272 boys and 222 girls. Among these patients, pathogens were identified in 347 cases and the pathogen was unclear in the remaining 147 cases. The main pathogens were MP (238 cases), Streptococcus pneumoniae (SP) (61 cases), Staphylococcus aureus (SA) (51 cases), Pseudomonas aeruginosa (13 cases), Haemophilus influenzae (10 cases), adenovirus (10 cases), and influenza virus A (7 cases), respectively. MP was the most common pathogen in all three periods and the proportion increased yearly. The proportion of MP in 2016-2019 was significantly higher than that in 2012-2015 (52.1% (197/378) vs. 36.8% (32/87), χ²=6.654, P=0.010), while there was no significant difference in the proportion of MP in 2012-2015 and that in 2008-2011 (36.8% (32/87) vs. 31.0% (9/29), χ²=0.314, P=0.575).Regarding the regional distribution, 342 cases were in the southern China and 152 in the northern China. Also, MP was the most common pathogen in both regions, but the proportion of MP was higher and the proportion of SP was lower in the north than those in the south (60.5% (92/152) vs. 42.7% (146/342), χ²=13.409, P<0.010; 7.9% (12/152) vs. 14.3% (49/342), χ²=4.023, P=0.045). Comparing the clinical characteristics of different pathogens, we found that fever and cough were the common symptoms in both single MP and single bacterial groups, but chest pain was more common (17.0% (34/200) vs. 6.1% (6/98), χ²=6.697, P=0.010) while shortness of breath and wheezing were less common in MP group (16.0% (32/200) vs. 60.2% (59/98), χ²=60.688, P<0.01; 4.5% (9/200) vs. 21.4% (21/98), χ²=20.819, P<0.01, respectively). The white blood cell count, C-reactive protein and procalcitonin in the bacterial group were significantly higher than those in the MP group (14.7 (1.0-67.1)×10⁹/L vs. 10.5 (2.5-32.2)×10⁹/L, 122.5 (0.5-277.3) mg/L vs. 51.4 (0.5-200.0) g/L, 2.13 (0.05-100.00) μg/L vs. 0.24 (0.01-18.85) μg/L, Z=-3.719, -5.901 and -7.765, all P<0.01). Conclusions: The prevalence of pediatric NP in China shows an increasing trend during the past years. MP, SP and SA are the main pathogens of NP, and the most common clinical symptoms are fever and cough. The WBC count, C-reactive protein and procalcitonin in bacterial NP are significantly higher than those caused by MP.

[Association analysis between extracurricular physical activity and dyslipidemia among primary, middle and high school students in Guangzhou]

Objective: To investigate the prevalence of dyslipidemia, and to explore the association between extracurricular physical activity and dyslipidemia among primary, middle and high school students in Guangzhou. Methods: This cross-sectional study selected primary and middle school students in Guangzhou by the stratified cluster sampling method from March to December 2019. Physical examination and blood lipid test were performed. Information about students' basic characteristics and extracurricular physical activity was collected by questionnaire. Multivariate logistic regression analysis was used to determine the association between extracurricular physical activity and dyslipidemia in this cohort. Results: A total of 7 797 participants (mean aged (12.2±2.9) years) were included (4 194 (53.79%) boys and 3 603 (46.21%) girls]. The detection rates of high total cholesterol, high triglycerides, low high-density lipoprotein cholesterol, high low-density lipoprotein cholesterol and dyslipidemia were 12.49% (974/7 797), 6.44% (502/7 797), 6.62% (516/7 797), 11.31% (882/7 797) and 23.83% (1 858/7 797), respectively. Dyslipidemia rate was lower in the junior school students (21.39% (675/3 156)) than in primary school students (25.96% (896/3 451)) and high-school students (24.12% (287/1 190)) (P<0.001). The dyslipidemia rates of boys and girls were similar (23.15% (971/4 194) vs. 24.62% (887/3 603), P>0.05). Dyslipidemia rate was lower in students with extracurricular physical activity than in students without extracurricular physical activity (22.50% (923/4 102) vs. 25.30% (935/3 695), P<0.05). Multivariate logistic regression analysis showed that extracurricular physical activity was associated with lower risk of dyslipidemia (OR=0.88, 95%CI=0.79-0.99, P=0.033). Among all types of extracurricular physical activities, participating in extracurricular large ball game was associated with 28% lower risk among junior school students (OR=0.72, 95%CI=0.57-0.91, P=0.006). Conclusion: The prevalence of dyslipidemia is high among primary, middle and high school students in Guangzhou. Extracurricular physical activity is associated with reduced risk of dyslipidemia in this cohort.

[Formation of study population for causal inference]

Epidemiological analysis describes and compares the characteristics of a certain number of people to make causal inferences. The formation of the study population is always the first step. In this paper, we first define the concepts of cross-sections at both individual level and population level and introduce the three assumptions needed in the measurements in observational studies, i. e. the true values of the attributes are stable with time, the attribute variables are independent and the individuals are independent during the measuring process. We also determine that the causal inference research should be unified based on the time of the occurrence or beginning of a postulated cause, or exposure, should be in. Then, based on the dual roles of the population cross-section with causal thinking, we propose that research designs can be classified into two types with different characteristics: history reconstruction research and future exploration research. Finally, we briefly analyze the research design framework and the relationship between estimated effects and different designs. The discussion of the formation of a study population from the perspective of causal thinking can make a foundation for the classification of causal inference research design with appropriate effect parameters, which needs to be further studied.

[Consistency of peripheral whole blood and venous serum procalcitonin in children: a multicenter parallel controlled study]

Objective: To explore the consistency of peripheral whole blood and venous serum procalcitonin (PCT) levels, and the value of peripheral whole blood PCT in evaluating pediatric bacterial infection. Methods: This multicenter cross-sectional parallel control study was conducted in 11 children's hospital. All the 1 898 patients older than 28 days admitted to these hospitals from March 2018 to February 2019 had their peripheral whole blood and venous serum PCT detected simultaneously with unified equipment, reagent and method. According to the venous serum PCT level, the patients were stratified to subgroups. Analysis of variance and chi-square test were used to compare the demographic characteristics among groups. And the correlation between the peripheral blood and venous serum PCT level was investigated by quantitative Pearson correlation analysis.The PCT resultes were also converted into ranked data to further test the consistency between the two sampling methods by Spearman's rank correlation test. Furthermore, the ranked data were converted into binary data to evaluate the consistency and investigate the best cut-off of peripheral blood PCT level in predicting bacterial infection. Results: A total of 1 898 valid samples were included (1 098 males, 800 females),age 27.4(12.2,56.7) months. There was a good correlation between PCT values of peripheral whole blood and venous serum (r=0.97, P<0.01). The linear regression equation was PCT_{venous serum}=0.135+0.929×PCT_{peripheral whole blood}. However, when stratified to 5 levels, PCT results showed diverse and unsatisfied consistency between the two sampling methods (r=0.51-0.92, all P<0.01). But after PCT was converted to ordinal categorical variables, the stratified analysis showed that the coincidence rate of the measured values by the two sampling methods in each boundary area was 84.9%-97.1%. The dichotomous variables also showed a good consistency (coincidence rate 96.8%-99.3%, Youden index 0.82-0.89). According to the severity of disease, the serum PCT value was classified into 4 intervals（<0.5、0.5-<2.0、2.0-<10.0、≥10.0 μg/L）, and the peripheral blood PCT value also showed a good predictive value (AUC value was 0.991 2-0.997 9). The optimal cut points of peripheral whole blood PCT value 0.5、1.0、2.0、10.0 μg/L corresponding to venous serum PCT values were 0.395, 0.595, 1.175 and 3.545 μg/L, respectively. Conclusions: There is a good correlation between peripheral whole blood PCT value and the venous serum PCT value, which means that the peripheral whole blood PCT could facilitate the identification of infection and clinical severity. Besides, the sampling of peripheral whole blood is simple and easy to repeat.

[Matching in observational research: from the directed acyclic graph perspective]

Matching is a standard method for selecting research objects regarding the observational research, which controls confounding factors and improves statistical efficiency. However, its role in controlling confounding is not consistent in different observational studies. Matching can eliminate the confounding bias of matching variables in cohort studies, but checking on itself cannot eliminate confounding bias in case-control studies. In matched case-control studies, researchers may not accurately judge whether the variable is a confounder. Sometimes the variables that are not confounders are mistakenly matched. In that case, it will result in overmatching, which will lead to the decline of statistical efficiency or the introduction of unavoidable bias or increase of workload. If the real confounding factors are omitted, it will cause confounding bias. Therefore, researchers should consider what kind of matching variable selection criteria should be formulated. A directed acyclic graph is a visual graphic language that can show the complicated causality among different epidemiological research designs. This article analyzes the role of Matching in different observational research designs from the perspective of the directed acyclic graph, formulates the selection criteria for matching variables in matched case-control studies, and provides some reference suggestions for future epidemiological research design.

[Clinical study of cell sheets containing allogeneic keratinocytes and fibroblasts for the treatment of partial-thickness burn wounds]

Objective: To evaluate the efficacy and safety of cell sheets containing allogeneic keratinocytes and fibroblasts in the treatment of partial-thickness burn wounds. Methods: The cell sheets containing allogeneic keratinocytes and fibroblasts were constructed using polyurethane biofilm as carrier. Then gross observation and histological observation were conducted. From April 2016 to December 2017, Changhai Hospital of Naval Medical University recruited patients with acute partial-thickness burn wounds that met the inclusion criteria for this prospective and positively self-controlled clinical trial. Recruitment of 40 acute partial-thickness burn wounds were planned with each selected single wound being not smaller than 10 cm×10 cm and not more than 5% total body surface area (TBSA). Each wound was equally divided into two areas, which were recruited into cell sheet group and conventional treatment group according to the random number table. The wounds in cell sheet group were covered by cell sheet and then sterile gauze as secondary dressings. Depending on the wound healing and exudation, the sterile gauze was replaced every 1 to 3 day (s) after the treatment was started, and the cell sheet was replaced every 7 days (namely dressing changing). The wounds in conventional treatment group were covered by sulfadiazine silver cream gauze and then dressed with sterile gauze, with the dressings changed every 2 to 3 days depending on wound exudation. On treatment day 5, 7, 10, and 14, the wound healing rates in the two groups were calculated. The complete wound healing time, the total number of dressing changes, and the status of wound infection during treatment were recorded. The Visual Analogue Scale was used to score the pain at the first dressing change. Scar formation of patients was followed up for 6 to 12 months after injury. Safety indicators including vital signs, laboratory examination indexes, and adverse reactions during treatment were observed. Data were statistically analysed with Wilcoxon rank sum test and Bonferroni correction. Results: (1) Each prepared cell sheet had a diameter of about 8 cm and was about 49 cm(2) in size, containing 2 or 3 layers of keratinocytes and fibroblasts. (2) A total of 43 patients were enrolled, of whom 3 patients dropped out of the study. Of the 40 patients who completed the treatment, there were 22 males and 18 females who were aged 1 to 57 year (s), with total burn area of 2% to 26% TBSA. (3) On treatment day 5, 7, 10, and 14, the wound healing rates in cell sheet group were significantly higher than those in conventional treatment group (Z=4.205, 4.258, 3.495, 2.521, P<0.05 or P<0.01). The complete wound healing time in cell sheet group was 7 (6, 8) days, which was significantly shorter than 11 (7, 14) days in conventional treatment group (Z=4.219, P<0.01). The total number of wound dressing changes in cell sheet group was 1 (1, 2) times, which was significantly less than 6 (4, 7) times in conventional treatment group (Z=5.464, P<0.01). (4) The wounds in cell sheet group in 31 patients healed before the first dressing change. The pain score of wounds in the first dressing change in cell sheet group of 9 patients was 1 (0, 1) point, while the pain score of wounds in the first dressing change in conventional treatment group of 40 patients was 2 (1, 3) points. There was no obvious infection in the wounds in both groups of 40 patients before the wound healing. Nine patients completed the follow-up after the trial. In 6 patients, no scar formation was observed in cell sheet group or conventional treatment group. The color of wounds in cell sheet group was consistent with normal skin, and there was only a small amount of pigment deposition in the wounds of conventional treatment group. Three patients developed pigment deposition only in the wounds of cell sheet group but obvious scars in conventional treatment group. (5) The abnormal fluctuations of vital signs including body temperature, blood pressure, heart rate, respiratory rate, and laboratory examination indexes of all patients during treatment were alleviated through the process of burn wound healing. No obvious adverse reactions or abnormalities related to the treatment were observed. Conclusions: The cell sheet containing allogeneic keratinocytes and fibroblasts can reduce the number of dressing changes, accelerate wound epithelialization, shorten wound healing time, reduce pain during dressing change in the treatment of partial-thickness burn wounds, and it may reduce scar hyperplasia after wound healing because of accelerating wound epithelization. Its clinical application is simple, safe, and effective.

[May cross-sectional studies provide causal inferences?]

Due to the flaws inherited in synchronicity, statistical association and survivor bias on variables under measurement, a common 'consensus' has been reached on "cross-sectiional studies (CSS) can lead to failure on causal inference". In this paper, under both causal thinking and diagram, the real and measured cross-sections are clearly defined that these two concepts only exist theoretically. In real CSS research, the temporal orders of measured variables are all non-synchronic, equivalent to the assumption that measurement variables are independent to each other, or there is no differentiated classification bias. Similar to cumulative case-control or historical cohort studies, both exposure and outcome that exist or occur before their measurements in cross-sectional studies, are actions of historical reconstruction or doing 'Archaeology'. One of the common preconditions for causal inference in such studies is that: there must be a causal relation between the measured variables and their historical counterparts. The measured variables are all agents of their corresponding real counterparts, and the temporal orders are not that important in causal inference. It is necessary to better understand the analytic role of the CSS.

[On 'Negative control methods': related principles, methods and applications]

Negative control methods (NCM) are developed based on the idea that negative controls should be tested with negative results. It also extends to the multiple comparison groups and used for specificity of association in population studies. Negative controls do not take part in studying the causal hypothesis but sharing the same potential bias structures. Under different purposes, NCM can be divided into methods on negative exposure, negative period or negative outcome controls. They are mainly used to detect and control bias, such as: selection bias, confounding bias and measurement bias, but leaving the sample size at secondary importance. Rational application of NCM can help improving the accuracy of causal inference in both experimental and observational processes.

[Analysis of CT features of 15 children with 2019 novel coronavirus infection]

Objective: To explore imaging characteristics of children with 2019 novel coronavirus (2019-nCoV) infection. Methods: A retrospective analysis was performed on clinical data and chest CT images of 15 children diagnosed with 2019-nCoV infection. They were admitted to the Third People's Hospital of Shenzhen from January 16 to February 6, 2020. The distribution and morphology of pulmonary lesions on chest CT images were analyzed. Results: Among the 15 children, 5 were males and 10 females, aged from 4 to 14 years. Five of the 15 children were febrile and 10 were asymptomatic on the first visit. The first nasal or pharyngeal swab samples in all the 15 cases were positive for 2019-nCoV nucleic acid. For their first chest CT images, 6 patients had no lesions, while 9 patients had pulmonary inflammatory lesions. Seven cases had small nodular ground glass opacities and 2 cases had speckled ground glass opacities. After 3 to 5 days of treatment, 2019-nCoV nucleic acid in a second respiratory sample turned negative in 6 cases. Among them, chest CT images showed less lesions in 2 cases, no lesion in 3 cases, and no improvement in 1 case. The remaining 9 cases were still positive in a second nucleic acid test. Six patients showed similar chest CT inflammation, while 3 patients had new lesions, which were all small nodular ground glass opacities. Conclusions: The early chest CT images of children with 2019-nCoV infection are mostly small nodular ground glass opacities. The clinical symptoms of children with 2019-nCoV infection are nonspecific. Dynamic reexamination of chest CT and nucleic acid are important.

[Status and challenges of tissue-engineered skin]

Autologous split-thickness skin grafting is still an important procedure for the repair of skin defect. However, there are some obvious limitations, such as new injury to skin donor sites and insufficient skin source, etc. It is an ideal goal to develop tissue-engineered skin to realize permanent replacement of skin defect. After decades of development, a variety of tissue-engineered skins have been put into the market for applications, but it is still a long way to achieve regenerative repair of skin defect. In this article, we summarize the status of various tissue-engineered skins, and then make a preliminary discussion on the opportunities and challenges on development of tissue-engineered skin.

[Immunodeficiency diseases with interstitial lung disease as major clinical manifestations: report of six cases]

Objective: To summarize the clinical features of immunodeficiency diseases with interstitial lung disease (ILD) as major clinical manifestations and to improve understanding etiology of ILD. Methods: The clinical features and clinical clues for diagnosis of six cases with immunodeficiency presented with ILD in Shenzhen Children's Hospital from January 2014 to December 2016 were retrospectively analyzed. Results: The patients' age ranged from 3 months to 5 years and 9 months, 5 cases were male. All cases had cough and tachypnea, 3 cases had lung infection and respiratory failure, 2 cases had chronic hypoxia and one had clubbing. Three cases had skin rashes; 5 cases had failure to thrive. Chest CT scan showed diffuse ground glass opacity in all the 6 cases, and 2 cases had cystic changes and one had "crazy-paving" pattern. Five patients were suspected to have surfactant dysfunction and genetic testing was performed before diagnosis of immunodeficiency, of which the results were negative. With human immunodeficiency virus antibody test or immunologic laboratory testing and/or immune genetic panel, acquired immune deficiency syndrome was confirmed in one case, hyper-IgM syndrome was confirmed in two cases and hyper-IgE syndrome in one case, Wiskott-Aldrich syndrome in one and STAT3 gain of function genetic mutation in another. All cases had clinical clues indicative of underlying immunocompromise. Conclusions: The clinical features of immunodeficiency diseases with ILD are cough, tachypnea or hypoxia, respiratory failure with infection, diffuse ground glass opacity in Chest CT imaging. With thorough medical history and immunology screening, there would be clinical clues indicative of underlying immunocompromise. Screening for immunodeficiency disease should be emphasized in the differential diagnosis of ILD, otherwise it may lead to misdiagnosis or unnecessary testing.

[Retracted: Clinical and epidemiological characteristics of 34 children with 2019 novel coronavirus infection in Shenzhen]

Objective: To describe the characteristics of clinical manifestations and epidemiology of children with 2019 novel coronavirus (2019-nCoV) infection. Methods: All 34 children with laboratory-confirmed 2019-nCoV infection by quantitative real-time reverse transcription-PCR through nasopharyngeal swab specimens were admitted to the Third People's Hospital of Shenzhen from January 19 to Febuary 7, 2020. Clinical data and epidemiological history of these patients were retrospectively collected and analyzed. Results: Among the 34 cases, 14 were males, and 20 were females. The median age was 8 years and 11 months. No patients had underlying diseases. There were 28 children (82%) related with a family cluster outbreak. There were 26 children (76%) with a travel or residence history in Hubei Province. These patients could be categorized into different clinical types, including 22 (65%) common cases, 9 (26%) mild cases and 3 (8.8%) asymptomatic cases. No severe or critical cases were identified. The most common symptoms were fever (17 cases, 50%) and cough (13 cases, 38% ). In the 34 cases, the white blood cell counts of 28 cases (82%) were normal. Five cases had white blood cell counts more than 10×10(9)/L. One case had white blood cell counts less than 4×10(9)/L. Neutropenia and lymphopenia was found in one case, respectively. C-reactive protein levels and erythrocyte sedimentation rates were elevated in 1 and 5 case, respectively. Elevated procalcitonin was found in 1 case and D-Dimer in 3 cases. The levels of lactic dehydrogenase (LDH) were more than 400 U/L in 10 cases. The CT images of these patients showed bilateral multiple patchy or nodular ground-glass opacities and/or infiltrating shadows in middle and outer zone of the lung or under the pleura. Twenty patients were treated with lopinavir and ritonavir. Glucocorticoids and immunoglobulin were not used in any cases. All the cases improved and were discharged from hospital. Further following up was need. Conclusions: The clinical manifestations in children with 2019-nCoV infection are non-specific and are milder than that in adults. Chest CT scanning is heplful for early diagnosis. Children's infection is mainly caused by family cluster outbreak and imported cases. Family daily prevention is the main way to prevent 2019-nCoV infection.

[Retracted: Clinical and epidemiological characteristics of 34 children with 2019 novel coronavirus infection in Shenzhen]

Objective: To describe the characteristics of clinical manifestations and epidemiology of children with 2019 novel coronavirus (2019-nCoV) infection. Methods: All 34 children with laboratory-confirmed 2019-nCoV infection by quantitative real-time reverse transcription-PCR through nasopharyngeal swab specimens were admitted to the Third People's Hospital of Shenzhen from January 19 to Febuary 7, 2020. Clinical data and epidemiological history of these patients were retrospectively collected and analyzed. Results: Among the 34 cases, 14 were males, and 20 were females. The median age was 8 years and 11 months. No patients had underlying diseases. There were 28 children (82%) related with a family cluster outbreak. There were 26 children (76%) with a travel or residence history in Hubei Province. These patients could be categorized into different clinical types, including 22 (65%) common cases, 9 (26%) mild cases and 3 (8.8%) asymptomatic cases. No severe or critical cases were identified. The most common symptoms were fever (17 cases, 50%) and cough (13 cases, 38% ). In the 34 cases, the white blood cell counts of 28 cases (82%) were normal. Five cases had white blood cell counts more than 10×10(9)/L. One case had white blood cell counts less than 4×10(9)/L. Neutropenia and lymphopenia was found in one case, respectively. C-reactive protein levels and erythrocyte sedimentation rates were elevated in 1 and 5 case, respectively. Elevated procalcitonin was found in 1 case and D-Dimer in 3 cases. The levels of lactic dehydrogenase (LDH) were more than 400 U/L in 10 cases. The CT images of these patients showed bilateral multiple patchy or nodular ground-glass opacities and/or infiltrating shadows in middle and outer zone of the lung or under the pleura. Twenty patients were treated with lopinavir and ritonavir. Glucocorticoids and immunoglobulin were not used in any cases. All the cases improved and were discharged from hospital. Further following up was need. Conclusions: The clinical manifestations in children with 2019-nCoV infection are non-specific and are milder than that in adults. Chest CT scanning is heplful for early diagnosis. Children's infection is mainly caused by family cluster outbreak and imported cases. Family daily prevention is the main way to prevent 2019-nCoV infection.

[Analysis of CT features of 15 Children with 2019 novel coronavirus infection]

Objective: To explore imaging characteristics of children with 2019 novel coronavirus (2019-nCoV) infection. Methods: A retrospective analysis was performed on clinical data and chest CT images of 15 children diagnosed with 2019-nCoV. They were admitted to the third people's Hospital of Shenzhen from January 16 to February 6, 2020. The distribution and morphology of pulmonary lesions on chest CT images were analyzed. Results: Among the 15 children, there were 5 males and 10 females, aged from 4 to 14 years old. Five of the 15 children were febrile and 10 were asymptomatic on first visit. The first nasal or pharyngeal swab samples in all the 15 cases were positive for 2019-nCoV nucleic acid. For their first chest CT images, 6 patients had no lesions, while 9 patients had pulmonary inflammation lesions. Seven cases of small nodular ground glass opacities and 2 cases of speckled ground glass opacities were found. After 3 to 5 days of treatment, 2019-nCoV nucleic acid in a second respiratory sample turned negative in 6 cases. Among them, chest CT images showed less lesions in 2 cases, no lesion in 3 cases, and no improvement in 1 case. Other 9 cases were still positive in a second nucleic acid test. Six patients showed similar chest CT inflammation, while 3 patients had new lesions, which were all small nodular ground glass opacities. Conclusions: The early chest CT images of children with 2019-nCoV infection are mostly small nodular ground glass opacities. The clinical symptoms of children with 2019-nCoV infection are nonspecific. Dynamic reexamination of chest CT and nucleic acid are important.

[Therapeutic effect of dihydroartemisinin on pulmonary fibrosis in rats with dust]

Objective: To observe the therapeutic effect of dihydroartemisinin on pulmonary fibrosis in rats exposed to dust, and compare the therapeutic effects of dihydroartemisinin and tetrandrine. Methods: Sixty male Sprague-Dawley rats were randomly divided into control group, model group, treatment group 1 and treatment group 2, with 15 rats in each group. The model group and the treatment group were stained with disposable non-exposure silica tracheal instillation method. The drug was administered on the second day after the dust was applied. The treatment group was given with dihydroartemisinin 75 mg/kg, the treatment group was given tetrahexine 22 mg/kg, model group and control group were intragastrically administered with 1 ml of normal saline per 100 g of body mass. The drug was administered for 6 days per week for 28 days. Rats were sacrificed on the 7th, 14th and 28th day after dusting, and the lung tissues of rats were taken, detection of rat lung coefficient, ELISA was used to detect transforming growth factor-1(TGF-1)and Smad 2/3 in rat lung tissues, type I collagen (Col-I) expression level, pathological changes of rat lung tissue, immunohistochemical observation of rat lung tissue TGF-1 and Col-I protein expression. Statistial analysis was proformed with SPSS 19.0. The mean cornparis between graups wad perfomed using a completely randonized one-way (ANOVA). Results: The expressions of TGF-1, Smad 2/3 and Col-I in the lung tissue of the treatment group were significantly lower than those in the model group (P< 0.05), but the difference between the treatment group 1 and the treatment group 2 Not statistically significant (P>0.05). The results of immunohistochemistry showed that the TGF-1 and Col-I proteins in the interstitial of the model group showed strong positive expression. The expression of TGF-1 and Col-I protein in the lung interstitial of the treated group was weaker than that of the model group. Conclusion: Dihydroartemisinin can down-regulate the level of inflammatory cytokines in rat lung tissue. It is possible to inhibit pulmonary fibrosis by intervening in the TGF-β1/Smad 2/3 signaling pathway, but the therapeutic effect between DHA and tetrandrine is not significantly different in a short time.

[Clinical significance and correlation of ductular reaction in hepatobiliary diseases]

Ductular reaction is a kind of repair response to biliary and hepatocellular injury, and the pathological changes include lobular bile duct hyperplasia, matrix change and inflammatory cell infiltrations. In human liver, a ductular reaction originates from the activation and proliferation of hepatic progenitor cells. The activated hepatic progenitor cells, the intermediate hepatocytes and the reactive small bile duct cells together form the cell complex of ductular reaction, which has the dual characteristics of hepatobiliary system and co-expresses the hepatocyte and cholangiocyte antigen. Ductular reaction appears in all kinds of acute and chronic hepatobiliary injury, and plays an important role in liver regeneration and repair, fibrogenesis, cirrhosis formation, and hepatobiliary cancer occurrence and development. Understanding the pathological features and pathophysiological mechanisms of ductular reaction in various clinical hepatobiliary diseases and their role in liver regeneration can provide important suggestion for further exploring new-targeted treatment approach.

[Characteristics related to maternal and child cohort studies in China: A review]

Cohort study is an irreplaceable method for studies related to maternal and child health. Compared with other countries, China's maternal and child cohort studies started relatively later but has its unique developing track. This paper summarizes the basic information and characteristics of the maternal and child cohorts with wide and great influence in China in the past 25 years.

Serum hepatitis B surface antigen correlates with fibrosis and necroinflammation: A multicentre perspective in China

The kinetics of serum hepatitis B surface antigen (HBsAg) during the natural history of hepatitis B virus (HBV) infection has been studied, but the factors affecting them remain unclear. We aimed to investigate the factors affecting HBsAg titres, using data from multicentre, large-sized clinical trials in China. The baseline data of 1795 patients in 3 multicentre trials were studied, and the patients were classified into 3 groups: hepatitis B early antigen (HBeAg)-positive chronic HBV infection (n = 588), HBeAg-positive chronic hepatitis B (n = 596), and HBeAg-negative chronic hepatitis B (n = 611). HBsAg titres in the different phases were compared, and multiple linear progression analyses were performed to investigate the implicated factors. HBsAg titres varied significantly in different phases (P = .000), with the highest (4.60 log10 IU/mL [10%-90% confidence interval: 3.52 log10 IU/mL-4.99 log10 IU/mL]) in patients with HBeAg-positive chronic HBV infection. In all phases, age and HBV DNA were correlated with serum HBsAg level. In HBeAg-positive chronic hepatitis B patients, a negative correlation between HBsAg titres and fibrosis stage was observed. Alanine amonitransferase or necroinflammatory activity was also correlated with HBsAg titres in HBeAg-negative chronic hepatitis B patients. In conclusion, decreased HBsAg titres may be associated with advancing fibrosis in HBeAg-positive chronic hepatitis B patients or increased necroinflammation in those with HBeAg-negative chronic hepatitis B. Our findings may help clinicians better understand the kinetics of HBsAg and provide useful insights into the management of this disease.

[Exposure-preceding-outcome regarding time sequence among cohort studies in real world]

One of the commonly accepted merits of cohort studies (CSs) refers to the exposure precedes outcome superior to other observational designs. We use Directed Acyclic Graphs to construct a causal graph among research populations under CSs. We notice that the substitution of research population in place of a susceptible one can be used for effect estimation. Its correctness depends on the outcome-free status of the substituted population and the performance of both screening and diagnosis regarding the outcomes under study at baseline. The temporal precedence of exposure over outcome occurs theoretically, despite the opposite happens in realities. Correct effect estimate is affected by both the suitability of population substitution and the validities of outcome identification and exclusion.

[Association and interaction of pre-pregnant body mass index and gestational weight gain of women on neonatal birthweight]

Objective: To investigate the association between maternal pre-pregnant body mass index and gestational weight gain, as well as their interaction on neonatal birthweight. Methods: We built a cohort in Anqing Municipal Hospital from January 2014 to March 2015, enrolling pregnant women who decided to give birth in this hospital. All women were asked to fill a questionnaire for basic information collection. Medical information of both pregnant women and their newborns were obtained through electronic medical record. Chi-square analysis, multinomial logistic regression, multiplicative and additive interaction methods were used to analyze the association between pre-pregnant body mass index and gestational weight gain as well as their interactions on birth weight of the neonates. Results: A total of 2 881 pregnant women were included in this study. Of the 2 881 newborns, 359 (12.46%) were small for gestational age (SGA) and 273 (9.48%) were large for gestational age (LGA). After adjusting the possible confounding factors, results from the multinomial logistic regression showed that pre-pregnancy underweight women were more possible to deliver SGA (aRR=1.33, 95%CI: 1.02-1.73). If the gestational weight gain was below the recommended criteria, the risk of SGA (aRR=1.64, 95%CI: 1.23-2.19) might increase. Pre-pregnancy overweight/obese could increase the risk of being LGA (aRR=1.86, 95%CI: 1.33-2.60). Maternal gestational weight gain above the recommendation level was associated with higher rates of LGA (aRR=2.03, 95%CI: 1.49-2.78). Results from the interaction analysis showed that there appeared no significant interaction between pre-pregnancy BMI and gestational weight on birthweight. Conclusion: Pre-pregnancy body mass index and gestational weight gain were independently associated with neonatal birthweight while pre-pregnancy BMI and gestational weight gain did not present interaction on birthweight.

[Comparison of results of two immunoassays for detection of hepatitis B surface antigen in pregnant women]

Objective: To evaluate and compare the detection consistency of hepatitis B surface antigen (HBsAg) by two immunoassays: enzyme-linked immunosorbent assay (ELISA) and electrochemiluminescent immunoassay (ECLIA). Methods: A prospective study was conducted among 2 296 pregnant women recruited consecutively from January 1, 2014 to January 31, 2015 in a hospital. Blood samples were collected from them for the detection of HBsAg by using ELISA and ECLIA, Kappa test was performed on the results. Nested polymerase chain reaction and sequencing of HBV S gene were also performed in all samples. Phylogenetic analysis was performed using Mega 6.0 software. Results: The two methods had high detection consistence of HBsAg (Kappa=0.71). There were significant differences in detection result of B genotype and adw2 serotype HBV strains between two methods. Among 123 identified HBV strains, 113 belonged to genotype B and available for further analysis. The difference in detection of substitution rates between two methods or different positive groups were not significant. Compared with ELISA single positive group, the ECLIA single positive group had completely different substitution sites. Conclusion: The two methods had high detection consistence of HBsAg, but there were still 32.4% HBV DNA positive cases in ELISA/ECLIA single positive group, and complete complementary substitution sites between ELISA single positive group and ECLIA single positive group. Our results suggested that more effective detection procedure should be considered for the possible impact of the HBV silent transmission and infection.

[A novel compound heterozygous mutation in ABCA3 gene in a child with diffuse parenchymal lung disease]

Objective: To summarize the clinical characteristics of the diffuse parenchymal lung diseases in a child caused by a novel compound heterozygous ABCA3 mutation and explore the association between the phenotype and ABCA3 mutation. Method: The clinical material of a patient diagnosed with diffuse parenchymal lung disease with ABCA3 mutation in December 2016 in Shenzhen Children's Hospital was analyzed. The information about ABCA3 gene mutation updated before April, 2017 was searched and collected from the gene databases (including 1000Genomes, HGMD, EXAC) and the literatures (including Wanfang Chinese database and Pubmed). Result: The girl was one year and nine months old. She presented with chronic cough, tachypnea, cyanosis and failure to thrive since she was one year and three months old. Her condition gradually deteriorated after she was empirically treated. Physical examination showed malnutrition, tachypnea and clubbed-fingers. Her high resolution computed tomography (HRCT) revealed diffused ground-glass opacities, thickened interlobular septum, and multiple subpleural small air-filled lung cysts. The second generation sequencing study identified a novel compound heterozygous mutation (c.1755delC+c.2890G>A) in her ABCA3 gene, which derived respectively from her parents and has not been reported in the database and the literatures mentioned above. Conclusion: c.1755delC+c.2890G>A is a new kind of compound heterozygous mutation in ABCA3, which can cause children's diffuse parenchymal lung disease. Its phenotype is related to its genotype.

[Influence of intrahepatic cholestasis during pregnancy on the incidence of preterm birth]

Objective: Intrahepatic cholestasis during pregnancy (ICP) and its relation to incidence of preterm birth (PTB) were under study. Methods: A prospective cohort study was carried out that including all the hospitalized pregnant women with live singleton births, from January 2014 to March 2015 in Anqing Municipal Hospitals. Informed consent was followed in every pregnant woman with related demographic information collected through questionnaire and hospital electronic medical record system. Both univariate and multi-variate statistical methods were used to analyze the relations between ICP and incidence of PTB. Results: A total of 2 758 pregnant women were included in this study. The incidence proportions of ICP and PTB appeared as 7.25% and 16.28% respectively. Results from the logistic regression analysis showed that ICP increased the risk of both overall PTB (RR=2.33, 95%CI: 1.67-3.25) and medically indicated PTB (RR=8.46, 95%CI: 5.45-13.12), but not the spontaneous PTB (RR=0.94, 95%CI: 0.57-1.54). Conclusion: ICP seemed to have increased the risk on medically indicated PTB but not the spontaneous PTB.

[Factors influencing antiretroviral therapy adherence among HIV-infected people on antiretroviral therapy in Ili Kazakh Autonomous Prefecture]

Objective: To analyze factors influencing antiretroviral therapy (ART) adherence among human immunodeficiency virus (HIV) patients receiving ART at the town level in Ili Kazakh Autonomous Prefecture (Ili) in May 2015 and to document enhanced ART for acquired immunodeficiency syndrome (AIDS) cases. Methods: A cross-sectional survey was conducted using one-on-one interviews and data collection from the system of AIDS follow-up management in three ART services centers at the town level of Ili. The subjects were HIV-infected individuals, aged 18 years or older, who were receiving ART during the survey. The surveys collected demographic characteristics, information related to ART and status of engaging ART, smoking and drinking behavior, depression, and quality of life. Results: A total of 412 participants completed the survey. The age was (41.1±8.0) years (range, 19-67 years). Approximately 60.9% (251) were male and 39.1% (161) were female. The survey showed that 75.0% (309) of participants were in good adherence and the P(50) (P(25), P(75)) of quality of life was 56.31 (50.55, 59.42). Females demonstrated better adherence to ART (82.6% (n=133)) than males (70.1% (n=76)) (χ(2)=8.16, P=0.005). The compliance rate of participants (78.0% (n=54)) with depression was higher than non-depressed participants (63.5% (n=255)) (χ(2)=7.52, P=0.008). Multivariate logistic regression analyses showed that the probability of good adherence to ART increased with increasing quality of life (OR=1.06, 95%CI:1.02-1.09). Moreover, participants who consumed alcohol or disclosed their HIV infection status to families were less likely to have good adherence to ART (OR=0.26, 95% CI:0.13-0.53 and OR=0.31, 95% CI:0.13-0.72, respectively). Additionally, employed participants were also less likely to have good adherence to ART compared with unemployed participants (OR=0.45, 95% CI:0.21-0.97). Conclusion: HIV/AIDS patients primarily showed good adherence to ART. Factors related to ART adherence included alcohol consumption, informing family of infection, work status, and quality of life.

[Directed acyclic graphs: languages, rules and applications]

Nearly all scientific studies explore causality, which will be met by directed acyclic graphs (DAGs). This paper systematically introduces graphic language, basic and interference rules of DAGs, and their applications into identifying research questions, understanding and undertaking research designs, guiding data analysis, classifying biases, etc. DAGs play key roles in causality studies.

[Clinical manifestations of three cases of surfactant protein C p. V39L mutation]

Objective: To investigate the clinical manifestations of surfactant protein C gene (SFTPC) exon-2 c. 115G>G/T (p.V39L). Method: Patients were screened for the entire coding sequence of SFTPC. Three cases from three children's hospital with mutation in p. V39L were reported. Result: All the three cases were females. The age of onset ranged from 2 months to 7 years. Two cases had recurrent lower respiratory tract infection and failed to thrive. One had chronic anoxia and clubbing fingers. Chest computed tomography (CT) showed diffused ground glass pattern, localized emphysema and intralobular septal thickening. In one case, early sign of cyst formation was also shown on CT. Two were lost to follow-up after alleviation of acute respiratory infection. One was treated with oral low-dose azithromycin and nebulized budesonide and terbutaline. She had recurrent lower respiratory tract infection in more than one year of follow-up. Conclusion: Mutations in SFTPC p. V39L cause interstitial lung diseases. Clinical manifestations included recurrent respiratory tract infections, chronic lung disease. Chest CT showing diffused ground glass pattern, localized emphysema, intralobular septal thickening and early sign of cyst formation. The treatment and prognosis need further study.

[Progress in research of relationship between vaginal Lactobacillus and preterm delivery]

The vaginal flora in most healthy women is dominated by Lactobacillus species. The absence of Lactobacillus species in vaginal flora might lead to a series of symptoms, especially in pregnant women causing adverse pregnancy outcomes, such as preterm delivery. This review focuses on the progress in the research of the relationship between vaginal Lactobacillus and preterm delivery, providing reference for the reduction of the incidence of preterm delivery.

Regulatory T-cell depletion in the gut caused by integrin β7 deficiency exacerbates DSS colitis by evoking aberrant innate immunity

Integrin α4β7 controls lymphocyte trafficking into the gut and has essential roles in inflammatory bowel disease (IBD). The α4β7-blocking antibody vedolizumab is approved for IBD treatment; however, high dose of vedolizumab aggravates colitis in a small percentage of patients. Herein, we show that integrin β7 deficiency results in colonic regulatory T (Treg) cell depletion and exacerbates dextran sulfate sodium (DSS) colitis by evoking aberrant innate immunity. In DSS-treated β7-deficient mice, the loss of colonic Treg cells induces excessive macrophage infiltration in the colon via upregulation of colonic epithelial intercellular adhesion molecule 1 and increases proinflammatory cytokine expression, thereby exacerbating DSS-induced colitis. Moreover, reconstitution of the colonic Treg cell population in β7-deficient mice suppresses aberrant innate immune response in the colon and attenuates DSS colitis. Thus, integrin α4β7 is essential for suppression of DSS colitis as it regulates the colonic Treg cell population and innate immunity.

Transformation bending device emulated by graded-index waveguide

We demonstrate that a transformation device can be emulated using a gradient-index waveguide. The effective index of the waveguide is spatially varied by tailoring a gradient thickness dielectric waveguide. Based on this technology, we demonstrate a transformation device guiding visible light around a sharp corner, with low scattering loss and reflection loss. The experimental results are in good agreement with the numerical results.

Coherent magnetic plasmon modes in a contacting gold nano-sphere chain on a gold slab

A coupled magnetic resonator waveguide, composed of a contacting gold nanosphere chain on a gold slab, is proposed and investigated. A broadband coherent magnetic plasmon mode can be excited in this one dimensional nanostructure. By employing the Lagrangian formalism and the Fourier transform method, the dispersion properties of the wave vector and group velocity of the magnetic plasmon mode are investigated. Small group velocity can be obtained from this system which can be applied as subwavelength slow wave waveguides.