Potential of crop straw incorporation for replacing chemical fertilizer and reducing nutrient loss in Sichuan Province, China.

Sichuan Province is rich in crop straw, yet little is known about its spatial distribution pattern, potential in replacing chemical fertilizer and mitigating nutrient loss. Based on the statistical data and literature review, the spatial distribution and potential of nutrient resources in crop straw for replacing chemical fertilizers was evaluated in this study. The nutrient loss with both crop incorporation and chemical fertilizer application were examined using a nutrient release coefficient method and compared. Results showed that Chengdu Plain, Northeast and South Sichuan produced more than 95% of the total straw nutrient resources during the period of 2016-2020. The potential of crop straw to substitute potassium (K), nitrogen (N) and phosphorus (P) fertilizer were K2O 33.08-285.95 kg hm-2, N 9.52-82.32 kg hm-2 and P2O5 4.91-28.71 kg hm-2, respectively. If chemical fertilizer was substituted by all the available straw nutrient resources, N and P loss can be decreased by 55.12% and 65.84% in average in Sichuan Province. 343.93 t of N loss and 20.05 t of P loss can be reduced in plain areas, 122.88 t of N loss and 46.29 t of P loss can be reduced in mountainous and hilly areas, and 5.65 t of t N loss and 3.54 t of P loss can be reduced in plateau areas. It can be concluded that there were rich crop straw nutrient resources in Sichuan Province with obvious spatial variability, solid consideration should be put on to the proper use of crop straw nutrient resources, with the aim of chemical fertilizer reduction, nutrient loss reduction and sustainable development.

Significance of biotransformation and excretion on the enantioselective bioaccumulation of hexabromocyclododecane (HBCDD) in laying hens and developing chicken embryos.

Although (-)-α-hexabromocyclododecane (HBCDD) and (+)-γ-HBCDD are preferentially enriched in chickens, the key factors contributing to their selective bioaccumulation in hens and their potential biotransformation in developing chicken embryos remain unclear. Herein, in vivo and in ovo exposure experiments using hens and fertilized eggs were conducted to investigate the absorption, excretion, and biotransformation of HBCDDs in chickens. γ-HBCDD (76%) exhibited a higher absorption efficiency than α- (22%) and ß- (69%) HBCDDs. However, α-HBCDD was dominant in hen tissues, although γ-HBCDD accounted for >75% in the spiked feed. Moreover, chicken embryos biotransformed approximately 9.5% and 11.7% of absorbed α- and γ-HBCDDs, respectively, implying that diastereomer-selective elimination causes the predominance of α-HBCDD in hens. The concentration and enantiomer fraction (EF) of α-HBCDD in laid eggs were significantly positively correlated, suggesting enantioselective elimination. The EFs of α- and γ-HBCDDs varied between feces from the exposure and depuration periods, indicating the preferred excretion of (+)-α- and (-)-γ-HBCDDs. Furthermore, the enantioselective biotransformation of (-)-γ-HBCDD was confirmed in developing chicken embryos. These results show that excretion and biotransformation contribute to the diastereomer- and enantiomer-selective bioaccumulation of HBCDDs in chickens; The results may improve our understanding of the environmental fate and ecological risks of HBCDDs in biota.

Effects of organochlorine exposure on male reproductive disorders in an electronic waste area of South China.

Several studies suggest that organochlorine exposure can affect male reproductive functions, causing poor semen quality, endocrine disruption, or dysregulation of thyroid hormones. This study uses multiple linear regression (MLR) models to analyze the correlation between male reproductive functions and polychlorinated biphenyl (PCBs) congeners or p,p'-DDE levels in serum, semen, and indoor dust samples. Multiple comparisons were all adjusted using the false discovery rate (FDR). The results revealed that the PCB congener levels in seminal plasma were significantly associated with the quality parameters of human semen (i.e., sperm count, morphology, and motility) and thyroid hormones after adjusting for covariates, e.g., associations of the sperm concentration with levels of CB105 (ß = -0.323, 95% CI: -0.561, -0.085, p = 0.009), CB44 (ß = 0.585, 95% CI: 0.290, 0.880, p < 0.001), and CB66 (ß = -0.435, 95% CI: -0.728, -0.143, p = 0.004) in the seminal plasma were observed. Correlations between serum pollutants levels and the semen quality, reproductive hormones, or thyroid hormones were also observed. Moreover, our results demonstrate that the quantification of PCBs in seminal plasma can better describe male reproductive disorders than that in serum or dust. Organochlorine exposure measured in serum or dust, especially in seminal plasma, was associated with semen quality, as well as reproductive and thyroid hormones, thus suggesting that the impacts of persistent pollutants on male reproductive health require further investigation.

Levels and congener profiles of halogenated persistent organic pollutants in human serum and semen at an e-waste area in South China.

Typical halogenated persistent organic pollutants (Hal-POPs), including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), polychlorinated biphenyls (PCBs), and dichlorodiphenyltrichloroethane (DDT), are a group of ubiquitous organic pollutants with an endocrine disrupting effect. This study evaluated the accumulation and congener profiles of Hal-POPs in the bodies of men who live/work in areas of South China where electronic wastes are collected and managed, especially in their semen samples. The results show that the detection frequency and serum concentrations of Hal-POP congeners within the high-exposure group (HEG) were higher than those of the low-exposure group (LEG). Furthermore, an identical trend was observed for the seminal plasma concentrations of Hal-POPs. The distribution characteristics, such as their mean, median, and discrete values, of PBDE congeners in serum and semen samples from the same subjects were consistent with each other. However, the distribution characteristics of PCB congeners in serum samples were different from those in semen samples. BDE153 was one of the most abundant congeners found in the serum and semen samples; hence, it can be identified as an indicator PBDE congener. Further research is needed to explore the mechanism of Hal-POPs distribution in human semen and serum samples.

Occurrence of Maxillary Central Diastema between Tooth-supported and Implant-supported Prostheses: a 5-year Clinical Follow-up.

A 27-year-old patient with a history of maxillary anterior tooth trauma presented with a maxillary central diastema between tooth- and implant-supported prostheses that had been in use for 5 years. The all-ceramic crowns were placed in 2012 after rigorous occlusal adjustment. Evaluations were carried out at 0, 2, 3, 4 and 5 years post restoration. The central diastema between the natural teeth and the implant-supported prosthesis on teeth 11 and 12 was first observed 2 years after implantation. After 5 years, the distance was found to have increased, with anterior occlusion and esthetic changes having taken place. The following possible causes were discussed: occlusal problems, anterior traumatic effects, the possible impact of guided bone regeneration (GBR) on the adjacent natural teeth and natural movement. More predictive information should be given to patients with implant-supported prostheses and natural teeth so that they are fully informed of the impact of any necessary clinical compromise and are aware of the modifications that may occur to their natural dentition.

Associations between PBDEs exposure from house dust and human semen quality at an e-waste areas in South China-A pilot study.

Previous studies have confirmed that house dust is one of the main sources of polybrominated diphenyl ethers (PBDEs) exposure, and also indicated that PBDEs might affect human semen quality. The aim of this study was to explore the association between PBDEs concentration in house dust and the semen quality of male resident. Results showed that the semen qualities of the residents living around the e-waste dismantling workshops for a long time (3-17years) at the e-waste areas in South China significantly decreased, and the DNA damage of sperms were aggravated. The adjusted correlation analysed by multiple linear regression model showed that the sperm concentration and count both had negative correlation with BDE47 level in semen (ß = -0.295, 95%CI: -0.553∼-0.036; ß = -0.400, 95%CI: -0.708∼-0.092, respectively). In addition, the sperm progressive motility [(A+B)%] and sperm viability both had negative correlation with BDE100 level in dust (ß = -0.360, 95%CI: -0.680∼-0.040; ß = -0.114, 95% CI: -0.203∼-0.025, respectively). And there were significant linear positive correlation between PBDE congener (e.g. BDE28, 47, 153) concentrations in dust and in paired semen samples (rs = 0.367-0.547, p < 0.05). This study suggested that exposure to PBDEs from house dust might have adverse effects on human semen quality. But the results need to be confirmed in further studies with a large-scale sampling, and find out more direct and convincing evidence.

[Effect of peroxisome proliferator-activated receptor-γ on endothelial cells oxidative stress induced by Porphyromonas gingivalis].

OBJECTIVE: To detect the degree of oxidative stress in the process when Porphyromonas gingivalis (P. gingivalis) stimulates human vascular endothelium, And to investigate the effect of peroxisome proliferator-activated receptor(PPAR)γ on oxidative stress during this process. METHODS: Human vascular endothelial cells (HVECs) line EA.hy926 (American Type Culture Collection ,United States) was cultured in high glucose Dulbecco's modified eagle medium (DMEM). Four groups were designed: control group, P. gingivalis infected group, PPARγ activated group and PPARγ blocked group. In control group HVECs were cultured with only DMEM. In P. gingivalis infected group, HVECs were time-dependently stimulated by P. gingivalis W83 from 0 to 12 h. In PPARγ activated group or PPARγ blocked group, PPARγ was pre-activated or blocked by a representative PPARγ agonist(15d-PGJ2 10 µmol/L) or antagonist (GW966210 µmol/L) 30 minutes before the cells were stimulated by P. gingivalis. At 0, 0.5, 1, 1.5, 2, 4, 8, and 12 h, the culture medium was collected individually and centrifuged, and the supernatant was stored for assay. Glutathione peroxidase (GSH-PX) and malondialdehyde (MDA) were analysed by enzyme-linked immunosorbent assay. Cellular reactive oxygen species (ROS) were detected through 2',7'-dichlorofluorescin diacetate (DCFA-DA) fluorescent probe at various time points of the different groups. RESULTS: In P. gingivalis infected group, the levels of GSH-PX [(5.56±0.97) µmol/L] and MDA [(0.84±0.18) nmol/L] were significantly higher than those in control group [GSH-PX(4.71±0.64) µmol/L, MDA (0.59±0.18) nmol/L)]. The levels of GSH-PX and MDA in PPARγ activated group [GSH-PX (5.38±0.84) µmol/L, MDA (0.84±0.22) nmol/L] and in PPARγ blocked group [GSH-PX (5.37±0.76) µmol/L, MDA (0.85±0.14) nmol/L] were significantly higher than those in control group (P<0.05). In the PPARγ activated group, the levels of GSH-PX at 0.5 and 8 h were significantly higher than those from 1.5 h to 4 h (P<0.05), while no difference was observed on the MDA levels at different time points. There was no significant difference at various time points for the levels of GSH-PX and MDA in PPARγ blocked group. The level of cellular ROS detected by DCFH-DA in P. gingivalis infected group was significantly higher than that in control group (10 108.65 ± 1 805.18 vs. 6 049.06 ± 1 199.19,P<0.05). No difference was observed between PPARγ activated group (7 120.94±1 447.30) or PPARγ blocked group (6 727.35±1 483.68) and control group. CONCLUSION: Oxidative stress happens when P. gingivalis stimulates human vascular endothelium. PPARγ may involve in modulating oxidative stress during this process.

[Investigation of oral health status in freshmen of university students].

OBJECTIVE: To investigate the oral health status of freshmen of university students and to guide their oral hygiene behaviors. METHODS: 6,575 freshmen of Peking University students were investigated in this study according to the criterion issued by World Health Organization (WHO) on the basic methods of oral health investigation and China oral health epidemiology survey protocol. The inspection item included caries, gingivitis, malocclusions and impacted teeth. RESULTS: In 6,575 freshmen of university students, the prevalence rate of caries, gingivitis, malocclusions and impacted teeth were 35.47%, 60.87%, 19.70% and 24.62%, respectively. There were statistical significance between the prevalence rate of caries, gingivitis, malocclusions and impacted teeth of male and female (chi2=131.94, P<0.001: chi2=216.85, P<0.001; chi2=14.54, P<0.01; chi2=23.56, P<0.001). There were statistical significance between the prevalence rate of caries, gingivitis and impacted teeth of postgraduate and undergraduate (chi2=4.62, P<0.05: chi2=129.56, P<0.001; chi2=178.05, P<0.001), while there was no statistical significance between the prevalence rate of malocclusions of postgraduate and undergraduate (chi2=0.61, P>0.05). CONCLUSION: The oral health status of freshmen of university students are not ideal. It is necessary to strengthen the propaganda education of prevention and protect to freshmen of university students.