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81.
Background: Little is known about geographic variations in liver cancer at high incident regions. We aimed to identify spatial variation of hepatocellular carcinoma (HCC) at a high-risk area in China and determine its association with socioeconomic status (SES). Methods: Based on 2299 liver cancer cases diagnosed in Haimen from 2003 to 2006, we calculated age–sex standardized incidence ratios (SIRs) and used two spatial scan statistics to determine the geographic variations in HCC. Bayesian hierarchical model was used to explore the association between HCC incidence and SES. Results: Age and sex SIRs for HCC varied from 0.54 to 1.97 for 24 townships. The eastern region of Haimen was identified to have a significantly increased risk of HCC. Fitting of a Bayesian hierarchical model linking per-capita fiscal revenue with SIRs of HCC indicated that the area with a lower revenue had a significantly higher incidence of HCC [βlog(revenue) = ?0.179, posterior 95% Bayesian credible interval (CI) = (?0.326, ?0.04)]. Conclusions: This study demonstrated substantial geographic variation in the incidence of HCC within a high-risk region, which was associated with SES. HCC control and intervention should focus on disadvantaged areas to reduce the HCC disparities.  相似文献   
82.
Forty-five populations of Pentanema corresponding to seven species included in the Pentanema conyzae clade have been studied using AFLP fingerprinting. The results show that allopolyploidization could have been involved in the diversification of this group, specifically in species P. langeanum and P. maletii. Molecular data confirm the presence of P. britannicum in the Iberian Peninsula and key steps are provided to identify the species that are morphologically the most challenging.  相似文献   
83.
There are experimental data which suggest that the primary immune effector cell responsible for maintaining immune surveillance against the outgrowth of EBV-transformed B cells in humans is the CTL, but in vivo proof of this is lacking. In this study we perform a series of cellular and molecular assays to characterize an autologous, endogenous immune response against a transplantation-associated, monoclonal, EBV+ posttransplant lymphoproliferative disorder (PTLD). Following allogeneic bone marrow transplantation, a patient developed a monoclonal PTLD of donor B cell origin. With a decrease in immune suppression, we document the emergence of endogenous, donor-derived CD3+CD8+ CTLs, followed by regression of the PTLD. The TCR Vbeta repertoire went from a polyclonal pattern prior to the development of PTLD to a restricted TCR Vbeta pattern during the outgrowth and regression of PTLD. Donor-derived CD3+CD8+ T lymphocytes displayed MHC class I-restricted cytolytic activity against the autologous EBV+ B cells ex vivo without additional in vitro sensitization. The striking temporal relationship between the endogenous expansion of a TCR Vbeta-restricted, CD3+CD8+ population of MHC class I-restricted CTL, and the regression of an autologous monoclonal PTLD, provides direct evidence in humans that endogenous CD3+CD8+ CTLs can be responsible for effective immune surveillance against malignant transformation of EBV+ B cells.  相似文献   
84.
The final steps in the synthesis of acetyl-CoA by CO dehydrogenase (CODH) have been studied by following the exchange reaction between CoA and the CoA moiety of acetyl-CoA. This reaction had been studied earlier (Pezacka, E., and Wood, H. G. (1986) J. Biol. Chem. 261, 1609-1615 and Ramer, W. E., Raybuck, S. A., Orme-Johnson, W. H., and Walsh, C. T. (1989) Biochemistry 28, 4675-4680). The CoA/acetyl-CoA exchange activity was determined at various controlled redox potentials and was found to be activated by a one-electron reduction with half-maximum activity occurring at -486 mV. There is approximately 2000-fold stimulation of the exchange by performing the reaction at -575 mV relative to the rate at -80 mV. Binding of CoA to CODH is not sensitive to the redox potential; therefore, the reductive activation affects some step other than association/dissociation of CoA. We propose that a metal center on CODH with a midpoint reduction potential of less than or equal to -486 mV is activated by a one-electron reduction to cleave the carbonyl-sulfur bond and/or bind the acetyl group of acetyl-CoA. Based on a comparison of the redox dependence of this reaction with that for methylation of CODH (Lu, W-P., Harder, S. R., and Ragsdale, S. W. (1990) J. Biol. Chem. 265, 3124-3133) and CO2 reduction and formation of the Ni-Fe-C EPR signal (Lindahl, P. A., Münck, E., and Ragsdale, S. W. (1990) J. Biol. Chem. 265, 3873-3879), we propose that the assembly of the acetyl group of acetyl-CoA, i.e. binding the methyl group of the methylated corrinoid/iron-sulfur protein, binding CO, and methyl migration to form the acetyl-CODH intermediate, occur at the novel Ni-Fe3-4-containing site in CODH. CO has two effects on the CoA/acetyl-CoA exchange: it activates the reaction due to its reductive capacity and its acts as a noncompetitive inhibitor. We also discovered that the CoA/acetyl-CoA exchange was inhibited by nitrous oxide via an oxidative mechanism. In the presence of a low-potential electron donor, CODH becomes a nitrous oxide reductase which catalytically converts N2O to N2. This study combined with earlier results (Lu, W-P., Harder, S. R., and Ragsdale, S. W. (1990) J. Biol. Chem. 265, 3124-3133) establishes that the two-subunit form of CODH is completely active in all reactions known to be catalyzed by CODH.  相似文献   
85.
Large‐scale biodiversity maps are essential to macroecology. However, between‐region comparisons can be more useful if patterns of observed species richness are supplemented by variations in dark diversity – the absent portion of the species pool. We aim to quantify and map plant diversity across Europe by using a measure that accounts for both observed and dark diversity. To do this we need to delimit suitable species pools, and evaluate the potential and limitation of a large‐scale dataset. We used Atlas Florae Europaeae (ca 20% of European plant species mapped within 50 × 50 km grid cells) and defined for each grid cell several species pools by applying various geographical and environmental filters: geographic species pool (number of species within 500 km radius), biogeographic species pool (additionally incorporating species distribution patterns, i.e. dispersion fields), site‐specific species pool (additionally integrating environmental preferences of species based on species co‐occurrence). We integrated dark diversity and observed diversity at a relative scale to calculate the completeness of site diversity: logistic expression of observed and dark diversity. We tested whether our results are robust against regional variation in data availability. We used independent regional databases to test if Atlas Florae Europaeae is a representative subset of total species richness. Environmental filtering was the most influential determinant of species pool size with more species filtered out in southern Europe. Both observed and dark diversity adhered to the well‐known latitudinal gradient, but completeness of site diversity varied throughout Europe with no latitudinal trend. Dark diversity patterns were fairly insensitive to variations in regional sampling intensity. Atlas Florae Europaeae represented well the total variation in plant diversity. In summary, dark diversity and completeness of site diversity add valuable information to broad‐scale diversity patterns since observed diversity is expressed at a relative scale.  相似文献   
86.
1. Time perception is seldom studied in invertebrates, with the limited experimental evidence being insufficient to provide a comprehensive pattern of the capacity of invertebrates to measure time and use it in decision‐making processes. 2. In this study, it was hypothesized that insect parasitoids have evolved the capacity to measure time precisely and to use it to optimize foraging decisions related to host exploitation. To examine time perception in females of the gregarious egg parasitoid Trichogramma euproctidis, the present study used their ability to adjust their investment (number of eggs laid) in a host to the initial transit duration (interval between the first contact with the host and the following contact with the substrate). Females utilize this method to assess host egg size, as a large egg necessarily requires more time to evaluate than a small host. In this study, the initial transit duration for a given sized egg was artificially extended by suspending it. 3. For similar sized hosts, female T. euproctidis significantly increased both oviposition duration and progeny allocation following a longer initial transit duration. 4. These results demonstrate the intrinsic capacity of this parasitoid to measure time and to adjust their progeny investment accordingly. This is believed to be one of the few demonstrations of a retrospective measure of time in an invertebrate.  相似文献   
87.
近年来。笔在研究各地送鉴的大呈吉丁虫标本过程中。鉴定出一批中国新纪录种,今集中加以报道.并分别作简述如下。  相似文献   
88.
Exosomes derived from differentiated P12 cells and MSCs were proved to suppress apoptosis of neuron cells, and phosphatase and tensin homolog pseudogene 1 (PTENP1) was reported to inhibit cell proliferation. In this study, we aimed to investigate the role of PTENP1 in the process of post-spinal cord injury (SCI) recovery, so as to evaluate the therapeutic effects of exosomes derived from MSCs transfected with PTENP1 short hairpin RNA (shRNA), as a type of novel biomarkers in the treatment of SCI. Electron microscopy was used to observe the morphology of different exosomes. Real-time polymerase chain reaction and western blot, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, flow cytometry, Nissl staining, immunohistochemistry assay, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay were conducted to investigate and validate the underlying molecular signaling pathway. PTENP1-shRNA downregulated PTENP1 and PTEN while upregulating miR-21 and miR-19b. PTENP1-shRNA also accelerated cell apoptosis and reduced cell viability. In addition, PTENP1 reduced the miR-21 and miR-19b expression by directly targeting miR-21 and miR-19b. Meanwhile, both miR-21 and miR-19b reduced the expression of PTEN by directly targeting the 3′-untranslated region of PTEN. Furthermore, PTEN level and apoptosis index of neuron cells was the highest in the SCI group, while the treatment with exosomes+PTENP1-shRNA reduced the PTEN expression to a level similar to that in the sham group. Finally, PTENP1 inhibited miR-21 and miR-19b expression but upregulated PTEN expression. The upregulation of miR-21/miR-19b also suppressed the apoptosis of neuron cells by downregulating the PTEN expression. PTENP1 is involved in the recovery of SCI by regulating the expression of miR-19b and miR-21, and exosomes from PTENP1-shRNA-transfected cells may be used as a novel biomarker in SCI treatment.  相似文献   
89.
The nocturnally active weakly electric fish Gnathonemus petersii is known to employ active electrolocation for the detection of objects and for orientation in its environment. The fish emits pulse‐type electric signals with an electric organ and perceives these signals with more than 3,000 epidermal electroreceptor organs, the mormyromasts, which are distributed over the animal's skin surface. In this study, we measured the metric dimensions of the mormyromasts from different body regions to find structural and functional specialization of the various body parts. We focused on the two foveal regions of G. petersii, which are located at the elongated and movable chin (the Schnauzenorgan; SO) and at the nasal region (NR), the skin region between the mouth and the nares. These two foveal regions were compared to the dorsal part (back) of the fish, which contains typical nonfoveal mormyromasts. While the gross anatomy of the mormyromasts from all skin regions is similar, the metric dimensions of the main substructures differed. The mormyromasts at the SO are the smallest and contain the smallest receptor cells. In addition, the number of receptor cells per organ is lowest at the SO. In contrast, at the back the biggest receptor organs with the highest amount of receptor cells per organ occur. The mormyromasts at the NR are in several respects intermediate between those from the back and the SO. However, mormyromasts at the NR are longer than those at all other skin regions, the canal leading from the receptor pore to the inner chambers were the longest and the overlaying epidermal layers are the thickest. These results show that mormyromasts and the epidermis they are embedded in at both foveal regions differ specifically from those found on the rest of the body. The morphological specializations lead to functional specialization of the two foveae. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.  相似文献   
90.
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