Advances in joint species distribution models to reveal community structure and its environmental response.

Species distribution models are commonly used in basic and applied ecological research to examine the factors driving the distribution and abundance of organisms. They are employed to quantify species’ relationships with abiotic conditions, to predict species’ response to land-use and climatic change, and to identify potential conservation areas. Biotic interactions have been rarely included in traditional species distribution models, wherein joint species distribution models (JSDMs) emerge as a feasible approach to simultaneously incorporate environmental factors and interspecific interactions, making it a powerful tool for analyzing the structure and assembly of biotic communities. Generally, the JSDMs are based on species distribution models (SDMs), with the abundance or occurrence of multiple species as response variables and environmental factors, species associations and species traits being incorporated in the modeling framework. These models commonly use generalized linear regression methods (GLM) to relate multivariate response to environmental variables, and capture species associations in the form of random effects. The limitation has been overcome by the introduction of latent variable models (LVMs). Typically, the model parameters are estimated using maximum likelihood estimation or Bayesian methods implemented by Laplace Approximation and Markov Chain Monte Carlo (MCMC) simulations, respectively. In this review, the generation and theoretical basis of JSDMs were summarized. The characteristics of different types of JSDMs and their applications in modern ecology were emphatically introduced. The problems and prospects of JSDMs were discussed. With the in-depth study of the relationship between environmental factors and multi-species interactions, JSDMs would be the focus of future studies of species distribution model.

[Canopy interception characteristics of main vegetation types in Liupan Mountains of China].

Based on field observation and modeling analysis, this paper studied the canopy interception, interception capacity, and some parameters for interception modeling of main forest types in Liupan Mountains of China. For the test main forest types, the ratio of their canopy interception to precipitation ranged from 8.59% to 17.94%, throughfall was more than 80%, and stemflow ranged from 0.23% to 3.10%. The canopy interception capacity was 0.78-1.88 mm, among which, leaf interception capacity was 0.62-1.63 mm, and stem interception capacity was 0.13-0.29 mm. Conifer forest had a higher canopy interception capacity than broad-leaved forest. The modified model considering the change of leaf area index, which was used in this paper, had a higher simulating precision than the interception model used before. The simulation results for Betula albo-sinensis forest, Pinus armandii forest, Prunus shrub, and Quercus liaotungensis-Tilia paucicostata forest were good, but those for Quercus liaotungensis forest, Pinus tabulaeformis forest, and Acer tetramerum and Euonymus sanguineus shrub were bad, which might be related to the differences in canopy structure, leaf area index, and precipitation characteristics.

[Soil macropore characteristics under typical vegetations in Liupan Mountains].

The radius and density of soil macropores under eight typical vegetations in Liupan Mountains of Northwest China were studied by using water breakthrough curves and Poiseuille equation. The results indicated that the radii of soil macropores ranged from 0.4 mm to 2.3 mm, and the weighted mean radii ranged from 0.57 mm to 1.21 mm, with a mean of 0.89 mm. The density of soil macropores ranged from 57 individuals per dm2 to 1 117 individuals per dm2, with a mean of 408 individuals per dm2. The macropores with radii bigger than 1.4 mm had a lower density, accounting for only 6.86% of the total. The area proportion of soil macropores ranged from 0.76% to 31.26%, with a mean of 10.82%. In study area, the density of soil macropores was higher in broadleaf forest than in coniferous forest, but basically the same in sub-alpine meadow and in broadleaf forest, as well as in shrubs and in coniferous forest. As for the area proportion of soil macropores, it was also higher in broadleaf forest than in coniferous forest, but basically the same in shrubs and in broadleaf forest soil, as well as in sub-alpine meadow and in coniferous forest.

[Intrauterine HBV infection: risk factors and impact of HBV DNA].

OBJECTIVE: To investigate the risk factors of intrauterine hepatitis B virus (HBV) infection and the impact of HBV DNA on the infection. METHODS: The serum levels of HBsAg, HbsAb, HBeAg, HBeAb, HBcAb and HBV DNA were determined in blood samples from 230 HBsAg-positive pregnant women and their newborns by enzyme-linked immunosorbent assay (ELISA) and fluorescence quantitative PCR (FQ-PCR), respectively. The newborns acquiring HBV infection via intrauterine transmission were selected as the case group and others as the control group. The risk factors for intrauterine HBV infection were analyzed by non-conditional logistic regression model. RESULTS: Six infants were found to be HBsAg-positive, and 18 HBV DNA-positive, and 3 of them were positive for both HBsAg and HBV DNA. The rate of intrauterine HBV infection was 9.6% (22/230). The grade of HBV DNA level was identified as the only risk factor of intrauterine HBV infection by non-conditional logistic regression model, with odds ratio (OR) of 1.57 (95% confidence interval 1.12-2.21). Of the 119 pregnant women positive for HBV DNA, 18 were diagnosed as having intrauterine HBV infection, and the likeliness of the infection significantly increased for a maternal serum HBV DNA level > or =10(7) copies/ml (chi(2)=7.92, P<0.05). CONCLUSION: The grade of serum HBV DNA level is the predominant risk factor for intrauterine HBV infection in pregnant women, and for those with serum HBV DNA lever > or =10(7) copies/ml, the chance for intrauterine HBV infection can be significantly increased.

Clinical characteristics of fulminant hepatitis in pregnancy.

AIM: To investigate the clinical characteristics of fulminant hepatitis in pregnancy. METHODS: We compared and analyzed the etiology, clinical characteristics, and laboratory examinations of 25 cases of fulminant hepatitis in pregnancy and 30 cases of fulminant hepatitis not in pregnancy. RESULTS: HBV infection and chronic fulminant hepatitis were most common both in the pregnant and in the non-pregnant groups. Jaundice, digestive tract symptoms, increase of bilirubin and thrombinogen activity were the main manifestations. The incidence of hepatic encephalopathy (HE) and hepato-renal syndrome (HRS) was significantly different between the two groups. The incidence of preterm labor, dead fetus and neonatal asphyxia was high. CONCLUSION: Fulminant hepatitis is likely to occur in late pregnancy with more severe complications, which significantly influences maternity, perinatal fetus, and newborn.

Analyses of prognostic indices of chronic liver failure caused by hepatitis virus.

AIM: To analyze the related indices about the prognoses of chronic liver failure caused by hepatitis virus. METHODS: Retrospectively reviewed 320 cases of chronic liver failure caused by hepatitis viruses. An improved group and an ineffective group (IG) were made to compare and analyze their clinical manifestations, laboratory examination indices and complications. Logistic regression was also carried out. RESULTS: There were significant differences (P<0.05) between the improved group and the IG upon such indices as age, bilirubin, prothrombin time, albumin, alpha fetoprotein, the size of liver and complications (P<0.05). The regression formula was as follows: P = 1/(1+e(-y)) (y = 1.7262-0.0948X(1)+2.9846X(2)+0.6992X(3)+1.6019X(4)+ 2.0398X(5)). (Note: X(1)-Prothrombin activity; X(2)-digestive tract hemorrhage; X(3)-hepatic encephalopathy; X(4)-hepatorenal syndrome; X(5)-pulmonary infection.). CONCLUSION: Laboratory examination such as bilirubin, prothrombin time and alpha fetoprotein can be regarded as indices of the prognoses of chronic liver failure caused by hepatitis. Moreover, the regression equation can evaluate prognoses more comprehensively and direct our treatments.

Effect of hepatitis B immunoglobulin on interruption of HBV intrauterine infection.

AIM: To evaluate the efficacy of hepatitis B immunoglobulin (HBIG) in interrupting hepatitis B virus (HBV) intrauterine infection during late pregnancy. METHODS: We allocated 112 HBsAg positive pregnant women into 2 groups randomly. Fifty seven cases in the HBIG group received 200 IU (unit) HBIG intramuscularly every 4 wk from the 28 wk of gestation to the time of delivery, while 55 cases in the control group received no special treatment. HBsAg, HBeAg, HBcAb, HBeAb, HBsAb and HBV DNA levels were tested in the peripheral blood specimens from all of the mothers at 28 wk of gestation, just before delivery, and in blood from their newborns within 24 h before administration of immune prophylaxis. RESULTS: The intrauterine infection rate in HBIG group and control group were 10.5% and 27.3%, respectively, with significant difference (P<0.05). It showed ascendant trend as HBV DNA levels in the peripheral blood increased before delivery. CONCLUSION: HBIG is potent to cut down HBV intrauterine infection rate significantly when administered to pregnant women regularly during late pregnancy. The possibility of HBV intrauterine infection increases if maternal blood HBV DNA> or =10(8) copies/mL.

Pregnant woman with fulminant hepatic failure caused by hepatitis B virus infection: a case report.

AIM: To report the experience in successfully treating pregnant women with severe hepatitis. METHODS: Comprehensive medical treatments were performed under strict monitoring. RESULTS: Pregnant woman with severe hepatitis was successfully rescued. CONCLUSION: Vital measures taken in the treatment of pregnant women with severe hepatitis include termination of the pregnancy at a proper time and control of various complications, such as disseminated intravascular coagulation (DIC), hepatorenal syndrome, hepatic encephalopathy and infection.

Misoprostol in labour induction of term pregnancy: a meta-analysis.

OBJECTIVE: To evaluate the efficacy and safety of misoprostol in term labour induction. DATA SOURCES: Data from published English and Chinese literatures about misoprostol in term labour induction were identified from Medline and CBMdisk (using the search terms "misoprostol" and "labour induction") before 2001; hand searches of reference lists of original studies and reviews (including meta-analyses) and contact with investigators in this field before 2001. STUDY SELECTION: Studies were included if they had data on misoprostol and labour induction. Altogether 623 articles were found and 124 were admitted, including 19,287 cases. DATA EXTRACTION: Data were collected on efficacy and incidence of side-effects of misoprostol and oxytocin. Data were checked for consistency within the published articles and converted into a standard format for incorporation into a central database. DATA SYNTHESIS: The average successful induction rate, rates of caesarean section; incidence of tachysystole, hypertonus of uterus and precipitous labour, and rates of meconium stained amniotic fluid between the misoprostol and oxytocin groups were significantly different (P < 0.05). There were no significant differences between the two groups concerning the average interval from the administration of misoprostol and oxytocin to the onset of labour, duration of the total stage of labour, incidence rate of foetal distress, neonatal asphyxia (1-minute Apgar score < and= 7), postpartum haemorrhage or amount of blood loss in postpartum. CONCLUSIONS: Misoprostol is a superior agent over oxytocin on the induction of term labour, but its application might increase the risk of precipitous labour, abnormal uterine contractions or meconium stained amniotic fluid. Therefore, the dosages and regimens of the agent need further investigation.

Interruption of HBV intrauterine transmission: a clinical study.

AIM: To investigate the effect of hepatitis B virus (HBV) specific immunoglobin (HBIG) and lamivudine on HBV intrauterine transmission in HBsAg positive pregnant women. METHODS: Each subject in the HBIG group (56 cases) was given 200 IU HBIG intramuscularly (im.) every 4 weeks from 28-week (wk) of gestation, while each subject in the lamivudine group (43 cases) received 100 mg lamivudine orally (po.) every day from 28-wk of gestation until the 30(th) day after labor. Subjects in the control group (52 cases) received no specific treatment. Blood specimens were tested for HBsAg, HBeAg, and HBV-DNA in all maternities at 28-wk of gestation, before delivery, and in their newborns 24 hours before the administration of immune prophylaxis. RESULTS: Reductions of HBV DNA in both treatments were significant (P<0.05). The rate of neonatal intrauterine HBV infection was significantly lower in HBIG group (16.1 %) and lamivudine group (16.3 %) compared with control group (32.7 %) (P<0.05), but there was no significant difference between HBIG group and lamivudine group (P>0.05). No side effects were found in all the pregnant women or their newborns. CONCLUSION: The risk of HBV intrauterine infection can be effectively reduced by administration of HBIG or Lamivudine in the 3(rd) trimester of HBsAg positive pregnant women.