12 research outputs found
Decrease in excitatory neurons, astrocytes and proliferating progenitors in the cerebral cortex of mice lacking exon 3 from the Fgf2 gene
<p>Abstract</p> <p>Background</p> <p>The <it>Fgf2 </it>gene is expressed in the brain neuroepithelium during embryonic development and in astroglial cells throughout life. Previous knockout studies suggested that FGF2 plays a role in the proliferation of neural progenitors in the embryonic cerebral cortex. These studies exclusively used knockout alleles lacking the <it>Fgf2 </it>exon 1. However, the description of putative alternative exons located downstream from the canonical exon 1 raised the possibility that alternatively spliced transcripts may compensate for the lack of the canonical exon 1 in the <it>Fgf2 </it>-/- mice.</p> <p>Results</p> <p>We generated and characterized a new line of Fgf2 knockout mice lacking the expression of exon 3, which is conserved in all <it>Fgf2 </it>transcripts and contains essential heparin and receptor binding interfaces. The expression of <it>Fgf2 </it>exon 3 was prevented by inserting a transcriptional STOP cassette in the <it>Fgf2 </it>genomic locus. These mice demonstrate a phenotype in the adult neocortex characterized by decreased density and number of cortical excitatory neurons and astrocytes, which is virtually identical to that of the <it>Fgf2 </it>-/- mice lacking exon 1. In addition, we also show that the <it>Fgf2 </it>exon 3 knockout mice have decreased proliferation of precursors in the adult cerebral cortex, which had not been previously investigated in the other mutant lines.</p> <p>Conclusion</p> <p>The results demonstrate that the phenotype of two completely different <it>Fgf2 </it>KO mouse lines, lacking exon 1 or exon 3, is remarkably similar. The combined results from these KO models clearly indicate that FGF2 plays a role in cortical cell genesis during embryonic development as well as in adulthood. Thus, FGF2 may be required for the maintenance of the pool of adult cortical progenitor cells.</p
Effects of species-dominated patches on soil organic carbon and total nitrogen storage in a degraded grassland in China
Background Patchy vegetation is a very common phenomenon due to long-term overgrazing in degraded steppe grasslands, which results in substantial uncertainty associated with soil carbon (C) and nitrogen (N) dynamics because of changes in the amount of litter accumulation and nutrition input into soil. Methods We investigated soil C and N stocks beneath three types of monodominant species patches according to community dominance. Stipa krylovii patches, Artemisia frigida patches, and Potentilla acaulis patches represent better to worse vegetation conditions in a grassland in northern China. Results The results revealed that the soil C stock (0–40 cm) changed significantly, from 84.7 to 95.7 Mg ha−1, and that the soil organic carbon content (0–10 cm) and microbial biomass carbon (0–10 and 10–20 cm) varied remarkably among the different monodominant species communities (P < 0.05). However, soil total nitrogen and microbial biomass nitrogen showed no significant differences among different plant patches in the top 0–20 cm of topsoil. The soil C stocks under the P. acaulis and S. krylovii patches were greater than that under the A. frigida patch. Our study implies that accurate estimates of soil C and N storage in degenerated grassland require integrated analyses of the concurrent effects of differences in plant community composition
Surgeon Volume Trumps Specialty: Outcomes From 3596 Pediatric Cholecystectomies
SURGEON VOLUME TRUMPS SPECIALTY: OUTCOMES FROM 3,596 PEDIATRIC CHOLECYSTECTOMIES
Kesi Chen, Kevin Cheung (Department of Surgery, McMaster University, Hamilton, ON, Canada), Julie Ann Sosa. Department of Surgery, Yale University, School of Medicine, New Haven, CT.
Laparoscopic cholecystectomy is the standard surgical management of biliary disease in children, but there has been a paucity of studies addressing outcomes after pediatric cholecystectomies, particularly on a national level. This is the first study to address the effect of surgeon specialty and volume on clinical and economic outcomes after pediatric cholecystectomies on a population level.
We conducted a retrospective cross-sectional study using the Health Care Utilization Project Nationwide Inpatient Sample (HCUP-NIS). Children (17 yrs and younger) who underwent laparoscopic cholecystectomy from 2003-2007 were selected. Pediatric surgeons performed \u3e90% of their total cases in children. High-volume surgeons were in the top tertile (N\u3e37/year) of total cholecystectomies performed.
Chi-square, ANOVA, and multivariate linear and logistic regression analyses were used to assess in-hospital complications, median length of hospital stay (LOS), and total hospital costs (2007 dollars).
A total of 3,596 pediatric cholecystectomies were included. Low-volume surgeons had more complications, longer LOS, and higher costs than high-volume surgeons. After adjustment in multivariate regression, surgeon volume, but not specialty, was an independent predictor of LOS and cost.
High-volume surgeons have better outcomes after pediatric cholecystectomy than low-volume surgeons. Surgeon specialty was not predictive of outcomes. To optimize outcomes in children after cholecystectomy, surgeon volume and laparoscopic experience should be considered above surgeon specialty
A Random Parameters Ordered Probit Analysis of Injury Severity in Truck Involved Rear-End Collisions
Social and economic burdens caused by truck-involved rear-end collisions are of great concern to public health and the environment. However, few efforts focused on identifying the difference of impacting factors on injury severity between car-strike-truck and truck-strike-car in rear-end collisions. In light of the above, this study focuses on illustrating the impact of variables associated with injury severity in truck-related rear-end crashes. To this end, truck involved rear-end crashes between 2006 and 2015 in the U.S. were obtained. Three random parameters ordered probit models were developed: two separate models for the car-strike-truck crashes and the truck-strike-car crashes, respectively, and one for the combined dataset. The likelihood ratio test was conducted to evaluate the significance of the difference between the models. The results show that there is a significant difference between car-strike-truck and truck-strike-car crashes in terms of contributing factors towards injury severity. In addition, indicators reflecting male, truck, starting or stopped in the road before a crash, and other vehicles stopped in lane show a mixed impact on injury severity. Corresponding implications were discussed according to the findings to reduce the possibility of severe injury in truck-involved rear-end collisions
Reconstruction of Electronic Structure of MOF-525 via Metalloporphyrin for Enhanced Photoelectro-Fenton Process
Photoelectro-Fenton (PEF) process can continuously promote the occurrence of Fenton reaction and the generation of active species, which is an advanced oxidation technology for pollutant degradation. However, the lack of bifunctional catalysts restricts the development of PEF technology. In this study, the electronic rearrangement MOF-525 modified by metalloporphyrin (named MOF-525-Fe/Zr) was prepared, to load on the carbon felt as a novel cathode catalyst, which is used in PEF process. A series of characterization and photoelectric chemical properties tests combined with DFT calculation showed that the modification of MOF-525 could not only have the large specific surface area and multistage pore structure but also co-stimulate the metal-to-ligand charge transfer (MLCT) and ligand-to-cluster charge transfer (LCCT) by photoelectric synergy. These charge transitions provide periodic electron donor-acceptor conduction paths in MOF-525-Fe/Zr, which can improve the active species formation and transfer efficiency. Owing to their favorable pore and electronic structure as well as stability, MOF-525-Fe/Zr shows great promise for the application in the catalytic process of PEF. Sulfamethoxazole (SMX) degradation was enhanced by MOF-525-Fe/Zr with the TOC removal rate above 75% both in river water and tap water. Finally, the reasonable pathway of PEF catalytic degradation of SMX was proposed by HPLC-MS analysis. In conclusion, this study provides a new idea for reconstructing the electronic structure of MOFs catalyst and broadening the practical application of PEF technology
Effect of Biochar Application on Hydraulic Properties of Sandy Soil under Dry and Wet Conditions
Knowledge of soil hydraulic properties under dry (below permanent wilting point) and wet (from saturation to permanent wilting point) conditions is helpful for evaluating soil physical quality and modeling the movement of the substances (water and nutrients) in biochar-amended soils. To investigate the effect of biochar application on hydraulic properties of sandy soil under dry and wet conditions, water retention in wet conditions and soil drying curves from wet to dry conditions were measured under different application rates (1, 3, and 5%, w/w), particle sizes (<0.25, 0.25–0.5, 0.5–1, and 1–2 mm), and pyrolysis temperatures (300, 450, and 600°C) of wheat ( L.) straw-derived biochar. Results showed that when higher rate biochar (3 and 5%) was applied into the sandy soil, water retention became higher under dry and wet conditions. Biochar application with a larger particle size (0.5–1 and 1–2 mm) increased water retention under saturation and dry conditions but decreased water retention at field capacity. Sandy soil amended with biochar at the higher pyrolysis temperatures (450 and 600°C) had higher water retention under field capacity or dry conditions. Increasing biochar application rate, particle size, and pyrolysis temperature decreased the evaporation rate of sandy soil under dry conditions. Our findings suggested that hydraulic properties of the sand–biochar mixture were mainly determined by biochar properties under dry conditions and were highly related to the interpores between particles under wet condition
Research and Application on Design of Underground Container Logistics System Based on Autonomous Container Truck
Cell Senescence: A Nonnegligible Cell State under Survival Stress in Pathology of Intervertebral Disc Degeneration
The intervertebral disc degeneration (IDD) with increasing aging mainly manifests as low back pain (LBP) accompanied with a loss of physical ability. These pathological processes can be preliminarily interpreted as a series of changes at cellular level. In addition to cell death, disc cells enter into the stagnation with dysfunction and deteriorate tissue microenvironment in degenerative discs, which is recognized as cell senescence. During aging, many intrinsic and extrinsic factors have been proved to have strong connections with these cellular senescence phenomena. Growing evidences of these connections require us to gather up critical cues from potential risk factors to pathogenesis and relative interventions for retarding cell senescence and attenuating degenerative changes. In this paper, we try to clarify another important cell state apart from cell death in IDD and discuss senescence-associated changes in cells and extracellular microenvironment. Then, we emphasize the role of oxidative stress and epigenomic perturbations in linking risk factors to cell senescence in the onset of IDD. Further, we summarize the current interventions targeting senescent cells that may exert the benefits of antidegeneration in IDD