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Find video protocols related to scientific articles indexed in Pubmed.
In vitro fracture resistance of three commercially available zirconia crowns for primary molars.
Pediatr Dent
PUBLISHED: 10-11-2014
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The purpose of this study was to measure the fracture resistance of primary mandibular first molar zirconia crowns from three different manufacturers-EZ Pedo (EZP), NuSmile (NSZ), and Kinder Krowns (KK)-and compare it with the thickness of the zirconia crowns and the measured fracture resistance of preveneered stainless steel crowns (SSCs).
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INTERCOMPARISONS FOR INTEGRATING THE RADON-THORON DETECTOR OF NIRP, CHINA WITH NIRS, JAPAN.
Radiat Prot Dosimetry
PUBLISHED: 09-18-2014
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Intercomparisons play an important role in maintaining a reasonable and accurate standard of measurement and quality. Integrating the radon-thoron detector of the National Institute for Radiological Protection (NIRP), China has continuously been a subject of four rounds of international intercomparisons organised by the National Institute of Radiological Sciences (NIRS), Japan during 2007-12. The intercomparisons were held at NIRS. The exercises included different exposures for both radon and thoron. The results of the intercomparison for the detectors of NIRP for both radon and thoron exposures were in the range of ±20 % from the reference value and were categorised as 'Category I' in the intercomparison carried out in 2011. The radon and thoron results of the LD-P detector in four rounds of intercomparison exercises were summarised, and uncertainties of all the radon and thoron results of NIRP were within the acceptable range of 30 % in environment. Radon and thoron measurement results between NIRP and NIRS were basically in agreement.
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Methylation patterns of the IFN-? gene in cervical cancer tissues.
Sci Rep
PUBLISHED: 08-08-2014
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To explore the relationship between methylation of interferon gamma (IFN-?) gene and tumorigenesis in cervical cancer tissues, the biopsy specimens of cervical cancer and cervical intraepithelial neoplasia (CIN) (I-III) patients as well as normal controls were collected and analyzed.
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Simvastatin inhibits inflammation in ischemia-reperfusion injury.
Inflammation
PUBLISHED: 06-11-2014
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Ischemia/reperfusion (I/R) is associated with leukocyte accumulation and tissue injury. The aim of this research was to investigate the protective effect of simvastatin on hind limb I/R inflammation and tissue damage. Mice were subjected to hind limb ischemic insult for 2 h and were simultaneously administered an intraperitoneal injection of simvastatin (5 mg/kg); this was followed by 36 h of reperfusion. Myeloperoxidase (MPO) levels in the muscles of the hind limb were determined. CXC chemokines and pro-inflammatory cytokines, such as macrophage inflammatory protein (MIP)-2, cytokine-induced neutrophil chemoattractant (KC), interleukin (IL)-6, tumor necrosis factor (TNF)-?, and P-selectin, were assessed using enzyme-linked immunosorbent assay (ELISA). Leukocyte rolling and adhesion in vitro was assessed to indicate leukocyte recruitment at the site of inflammation. Quantitative measurement of skeletal muscle tissue injury was performed. The fluorescent dye level in tissue and serum was used to determine hind limb vascular leakage and tissue edema after I/R. Systemic and differentiated leukocytes were also counted. Simvastatin significantly reduced MIP-2, KC, TNF-?, MPO, IL-6, and P-selectin levels compared to the sham group and I/R plus pretreatment with phosphate-buffered saline (PBS) group (P<0.05). Compared to the sham group and I/R plus PBS group, the I/R plus simvastatin group had attenuated inflammation, vascular leakage, and muscular damage (P<0.05). Simvastatin also significantly inhibited leukocyte rolling and adhesion compared to PBS (P<0.05). Our results suggest that simvastatin may be an effective protectant against tissue injury associated with I/R.
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Hepatotoxicity and nephrotoxicity of organic contaminants in wastewater-irrigated soil.
Environ Sci Pollut Res Int
PUBLISHED: 06-10-2014
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The objective of this study is to investigate the hepatotoxicity and nephrotoxicity of organic contaminants in wastewater-irrigated soil using in vivo and in vitro experiments on mice and rat. Soil samples were collected from a wastewater-irrigated area and groundwater-irrigated area, i.e. clean water-irrigated area as control group. The organic contaminants were extracted using an ultrasonic oscillator. In vivo experiment was performed by contamination of hepatocytes of rat using the organic extract, and comet assay was used to analyse the DNA damage of hepatocytes. For in vitro experiment, mice were first gavaged with extracts, and then the indicators for kidney functions, liver functions and oxidative damage of tissues were investigated. The result shows, for in vitro experiments, compared with clean water-irrigated area groups, the average DNA tailing length for the wastewater-irrigated area group is larger, and for the wastewater-irrigated area groups with extract concentration 0.6 g/ml and 0.9 g/ml, the tailing rate increases significantly (P?
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Genotoxicity and Cytotoxicity of Cadmium Sulfide Nanomaterials to Mice: Comparison Between Nanorods and Nanodots.
Environ. Eng. Sci.
PUBLISHED: 03-19-2014
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Cadmium sulfide (CdS) nanomaterials (such as CdS nanodots or nanorods) are widely used in optical, electronic, and biological applications. Large-scale production and use of these materials will likely result in accidental and incidental releases, which raise concerns about their potential environmental and human-health impacts. Most studies on toxicity of Cd-containing nanomaterials have focused on nanodots, and the relative toxicity of Cd-containing nanorods is not well understood. Here, we compared genotoxicity and cytotoxicity of CdS nanorods (30-50?nm diameter, 500-1100?nm length) and cubic CdS nanodots (3-5?nm) in mice by examining total cadmium accumulation in organs, acute toxicity, DNA damage, spermatozoon viability and abnormality, kidney and liver damage, and oxidative stress. Compared with (smaller) nanodots, nanorods resulted in relatively low bioaccumulation, acute toxicity, and damage to spermatozoa and the tested organs. Differences in toxicity between CdS nanodots and nanorods could not be fully explained by differences in their metal ion (Cd(2+)) release patterns, based on control tests with mice gavaged with dissolved CdCl2 at equivalent concentrations. This underscores that toxicity of metallic nanomaterials could not be solely predicted based either on their elemental composition or on the amount of ions released before receptor intake. Particle morphology (including size) may also need to be considered.
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Comparison of the surface hardness among 3 materials used in an experimental apexification model under moist and dry environments.
J Endod
PUBLISHED: 01-17-2014
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Procedures used in single-visit or multiple-visit approaches to apical barrier creation were used with an experimental apexification model to test the surface hardness of 3 materials. The purpose of this study was to examine the microhardness of the materials after setting in moist or dry conditions.
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[Determination of cyanamide in workplace air by high-performance liquid chromatography].
Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi
PUBLISHED: 01-17-2014
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To establish a method for determining cyanamide in workplace air by high-performance liquid chromatography (HPLC).
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Twist2 promotes self-renewal of liver cancer stem-like cells by regulating CD24.
Carcinogenesis
PUBLISHED: 11-05-2013
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Twist2 is a highly conserved basic helix-loop-helix transcription factor that plays a critical role in embryogenesis. Recent evidence has revealed that aberrant Twist2 expression contributes to tumor progression; however, the role of Twist2 in human hepatocellular carcinoma (HCC) and its underlying mechanisms remain undefined. In this report, we demonstrate that Twist2 is overexpressed in human HCC tumors. We show that ectopic expression of Twist2 induces epithelial-mesenchymal transition phenotypes, augments cell migration and invasion and colony-forming abilities in human HCC cells in vitro, and promotes tumor growth in vivo. Moreover, we found a higher percentage of CD24(+) liver cancer stem-like cells in Twist2-transduced HCC cells. Twist2-expressing cells exhibited an increased expression of stem cell markers Bmi-1, Sox2, CD24 and Nanog and an increased capacity for self-renewal. Knockdown of CD24 in HepG2/Twist2 cells decreased the levels of Sox2, pSTAT3 and Nanog, and reversed the cancer stem-like cell phenotypes induced by ectopic expression of Twist2. Furthermore, Twist2 regulated the CD24 expression by directly binding to the E-box region in CD24 promoter. Therefore, our data demonstrated that Twist2 augments liver cancer stem-like cell self-renewal in a CD24-dependent manner. Twist2-CD24-STAT3-Nanog pathway may play a critical role in regulating liver cancer stem-like cell self-renewal. The identification of the Twist2-CD24 signaling pathway provides a potential therapeutic approach to target cancer stem cells in HCCs.
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Getting a head start: high-fidelity, simulation-based operating room team training of interprofessional students.
J. Am. Coll. Surg.
PUBLISHED: 06-17-2013
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Effective teamwork in the operating room (OR) is often undermined by the "silo mentality" of the differing professions. Such thinking is formed early in ones professional experience and is fostered by undergraduate medical and nursing curricula lacking interprofessional education. We investigated the immediate impact of conducting interprofessional student OR team training using high-fidelity simulation (HFS) on students team-related attitudes and behaviors.
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Early events in lymphopoiesis: an update.
Curr. Opin. Hematol.
PUBLISHED: 04-19-2013
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Cells of the immune system are replaced in large numbers throughout life, and the underlying mechanisms have been extensively studied. Whereas the pace of discovery in this area is unprecedented, many questions remain, particularly with respect to lymphocyte formation.
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The oxidative damage and inflammatory response induced by lead sulfide nanoparticles in rat lung.
Food Chem. Toxicol.
PUBLISHED: 01-29-2013
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Lead sulfide nanoparticles (PbS NPs) are one important nanoparticle materials which is widely used in photoelectric production, but its potential health hazard to respiratory system is not clear. This study aimed to explore the possible mechanism of lung injury induced by PbS NPs. Male SD rats were treated with nanoparticles of 60 nm and 30 nm lead sulfide. The main methods were detecting the vigor of superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) and the content of malondialdehyde (MDA) in both blood and lung tissues and observing the pathological changes in lung tissue. PbS NPs suppressed the activity of SOD and T-AOC, and increased serum MDA content (P<0.05); both effects were observed together in lung tissues of 30-nm group (P<0.05) accompanied by an obviously inflammatory response. PbS NPs induced oxidative damage and inflammatory response in lung tissue, which may be an underlying mechanism for its pulmonary toxicity. Additionally, the toxicity of PbS NPs was closely related with the size of nanoparticles.
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Effect of lead sulfide nanoparticles exposure on calcium homeostasis in rat hippocampus neurons.
J. Inorg. Biochem.
PUBLISHED: 01-10-2013
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PbS nanoparticles (NPs) is an important nanomaterial for biomedical imaging in living tissues. However, concerning the high toxicity, especially neurotoxicity, of Pb element, it is crucial that the toxicity assessment of "naked" PbS NPs should be adequately studied. In the current study, we systematically explored the neurotoxicity of PbS NPs in rats by measuring the body weight and brain coefficient changes, testing memory behaviors in Y-electric maze, and studying the neuronal ultrastructure and pathology in hippocampus. Furthermore, in order to study the toxic mechanism, we performed Pb and Ca content measurements in various organs, and investigated Ca(2+)-ATPase activity and L-type calcium channel subunit expression. Our results confirmed that PbS NPs showed high neurotoxicity, while a possible mechanism was suggested to be due to the PbS NPs-induced calcium homeostasis disorder which was caused by the abnormal calcium transportation.
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RAG-1 and Ly6D independently reflect progression in the B lymphoid lineage.
PLoS ONE
PUBLISHED: 01-01-2013
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Common lymphoid progenitors (CLPs) are thought to represent major intermediates in the transition of hematopoietic stem cells (HSCs) to B lineage lymphocytes. However, it has been obvious for some time that CLPs are heterogeneous, and there has been controversy concerning their differentiation potential. We have now resolved four Flt3(+) CLP subsets that are relatively homogenous and capable of forming B cells. Differentiation potential and gene expression patterns suggest Flt3(+) CLPs lacking both Ly6D and RAG-1 are the least differentiated. In addition to B cells, they generate natural killer (NK) and dendritic cells (DCs). At the other extreme is a subset of the recently described Flt3(+) Ly6D(+) CLPs that have a history of RAG-1 expression and are B lineage restricted. These relatively abundant and potent CLPs were depleted within 48 hours of acute in vivo estrogen elevation, suggesting they descend from hormone regulated progenitors. This contrasts with the hormone insensitivity of other CLP subsets that include NK lineage progenitors. This progenitor heterogeneity and differentiation complexity may add flexibility in response to environmental changes. Expression of RAG-1 and display of Ly6D are both milestone events, but they are neither synchronized nor dependent on each other.
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Evolution of D-lactate dehydrogenase activity from glycerol dehydrogenase and its utility for D-lactate production from lignocellulose.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 11-07-2011
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Lactic acid, an attractive, renewable chemical for production of biobased plastics (polylactic acid, PLA), is currently commercially produced from food-based sources of sugar. Pure optical isomers of lactate needed for PLA are typically produced by microbial fermentation of sugars at temperatures below 40?°C. Bacillus coagulans produces L(+)-lactate as a primary fermentation product and grows optimally at 50?°C and pH 5, conditions that are optimal for activity of commercial fungal cellulases. This strain was engineered to produce D(-)-lactate by deleting the native ldh (L-lactate dehydrogenase) and alsS (acetolactate synthase) genes to impede anaerobic growth, followed by growth-based selection to isolate suppressor mutants that restored growth. One of these, strain QZ19, produced about 90 g L(-1) of optically pure D(-)-lactic acid from glucose in < 48 h. The new source of D-lactate dehydrogenase (D-LDH) activity was identified as a mutated form of glycerol dehydrogenase (GlyDH; D121N and F245S) that was produced at high levels as a result of a third mutation (insertion sequence). Although the native GlyDH had no detectable activity with pyruvate, the mutated GlyDH had a D-LDH specific activity of 0.8 ?moles min(-1) (mg protein)(-1). By using QZ19 for simultaneous saccharification and fermentation of cellulose to D-lactate (50?°C and pH 5.0), the cellulase usage could be reduced to 1/3 that required for equivalent fermentations by mesophilic lactic acid bacteria. Together, the native B. coagulans and the QZ19 derivative can be used to produce either L(+) or D(-) optical isomers of lactic acid (respectively) at high titers and yields from nonfood carbohydrates.
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Working memory in the oldest-old: evidence from output serial position curves.
Mem Cognit
PUBLISHED: 06-16-2011
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In the present study, we examined adult age differences in short-term and working memory performance in middle-aged (45-64 years), young-old (65-74 years), old-old (75-89 years), and oldest-old adults (90 years and over) in the Louisiana Healthy Aging Study. Previous research suggests that measures of working memory are more sensitive to age effects than are simple tests of short-term memory Bopp and Verhaeghen (Journal of Gerontology: Psychological Sciences 60:223-233, 2005), Myerson, Emery, White, and Hale, (Aging, Neuropsychology, and Cognition 10:20-27, 2003). To test this hypothesis, we examined output serial position curves of recall data from three span tasks: forward and backward digit span and size judgment span. Participants recall patterns in the size judgment span task revealed that the two oldest groups of adults showed the largest decreases in recall performance across output serial positions, but did not differ significantly from each other. Correlation analyses indicated the strongest negative correlation with age occurred with the size judgment span task. Implications of these findings for understanding strategic processing abilities in late life are discussed.
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Isolation, characterization and evolution of a new thermophilic Bacillus licheniformis for lactic acid production in mineral salts medium.
Bioresour. Technol.
PUBLISHED: 04-20-2011
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The high fermentation cost of lactic acid is a barrier for polylactic acid (PLA) to compete with the petrochemical derived plastics. In order to lower the cost of lactic acid, the industry needs a microorganism that can ferment various sugars at high temperature (50°C) and at the same time using low cost mineral salts (MS) medium. One such bacterium, BL1, was isolated at 50°C and identified as Bacillus licheniformis. BL1 can ferment glucose to optically pure l-lactate with a maximum specific productivity of 7.8 g/hl in LB medium and 0.7 g/hl in MS medium at 50°C. BL1 can also consume 10% and 15% glucose in 20 and 48 h, respectively. After serial transfer of BL1 and BL2 in different concentrations of xylose and MS medium respectively, the final mutant BL3 could efficiently ferment glucose and xylose with specific productivity of 1.9 g/hl and 1.2g/hl in strict MS medium.
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Assessment of polychlorinated biphenyls contamination in sediment and organism from Xiamen offshore area, China.
Bull Environ Contam Toxicol
PUBLISHED: 04-12-2011
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In Xiamen offshore area, sediment polychlorinated biphenyls (PCBs) concentrations ranged from 2.33 to 30.94 ng/g, with an average value of 8.94 ng/g. The in situ organic carbon normalized partition coefficients (log K(oc)) of the 12 co-polar congeners PCBs between sediments and porewater were from 1.50 to 2.64, and the log K(oc) decreased with increasing chlorine number. PCB congeners pattern of marine organism were characterized by 5-6 CB chlorinated compounds, and the world health organization total dioxin equivalents of PCBs in organism ranged from 1.45 to 88.26 pg/g lipid.
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Chronic exposure to a TLR ligand injures hematopoietic stem cells.
J. Immunol.
PUBLISHED: 03-25-2011
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Hematopoietic stem cells (HSC) can be harmed by disease, chemotherapy, radiation, and normal aging. We show in this study that damage also occurs in mice repeatedly treated with very low doses of LPS. Overall health of the animals was good, and there were relatively minor changes in marrow hematopoietic progenitors. However, HSC were unable to maintain quiescence, and transplantation revealed them to be myeloid skewed. Moreover, HSC from treated mice were not sustained in serial transplants and produced lymphoid progenitors with low levels of the E47 transcription factor. This phenomenon was previously seen in normal aging. Screening identified mAbs that resolve HSC subsets, and relative proportions of these HSC changed with age and/or chronic LPS treatment. For example, minor CD150(Hi)CD48(-) populations lacking CD86 or CD18 expanded. Simultaneous loss of CD150(Lo/-)CD48(-) HSC and gain of the normally rare subsets, in parallel with diminished transplantation potential, would be consistent with age- or TLR-related injury. In contrast, HSC in old mice differed from those in LPS-treated animals with respect to VCAM-1 or CD41 expression and lacked proliferation abnormalities. HSC can be exposed to endogenous and pathogen-derived TLR ligands during persistent low-grade infections. This stimulation might contribute in part to HSC senescence and ultimately compromise immunity.
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Spatial distribution, electron microscopy analysis of titanium and its correlation to heavy metals: occurrence and sources of titanium nanomaterials in surface sediments from Xiamen Bay, China.
J Environ Monit
PUBLISHED: 02-23-2011
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Titanium nanomaterials are likely to sink into sediments in substantial quantities due to their wide use in a number of applications for decades. To assess the potential environmental consequences, a better understanding is required of the occurrence and sources of titanium (Ti) nanomaterials in sediments. In this research, we provide the first report of the Ti concentrations and the morphology and composition of Ti-based solids in surface sediments from Xiamen Bay, China. Results indicated that the anthropogenic Ti concentrations in the surface sediments from Xiamen Bay reached approximately 2.74 g kg(-1). Ti nanomaterials could be found in sediments with elevated Ti concentrations, which were often aggregated to a few hundred nanometers (<300 nm) and were composed of several spherical particles, less than 50 nm in size, that were made solely of TiO(x). However, Ti particles (approx. 300-700 nm) could be also found in sediments with lower Ti concentrations, which were presumably components of the natural clay mineral kaolinite. Ti nanomaterials could be easily distributed in sediments associated with elevated levels of organic matter and preferentially attach to those sediments with elevated fine fractions. As a sentinel, or tracer, for other nanomaterials, the field-scale investigation of Ti nanomaterials would contribute to increasing our knowledge on the behavior of engineered nanomaterials in an aquatic environment.
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Functional diversity of stem and progenitor cells with B-lymphopoietic potential.
Immunol. Rev.
PUBLISHED: 08-24-2010
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Technical advances have made it possible to separate hematopoietic tissues such as the bone marrow into ever smaller populations, complicating our understanding of immune system replenishment. Patterns of surface marker expression and transcription profiles as well as results obtained with reporter mice suggest that lymphopoietic cells are not closely synchronized, and there is considerable cell to cell variation. Loss of differentiation options is gradual, and ultimate fate can be established at different stages of lineage progression. For example, individual hematopoietic stem cells can be biased such that some are very poor sources of lymphocytes as contrasted to ones with balanced outputs. Still other hematopoietic stem cells are effective at generating B and T cells but are defective with respect to expansion and difficult to distinguish from early lymphoid progenitors. That diversity carries forward to later events, and similar appearing cells in the immune system can arise from alternate differentiation pathways. In fact, new categories of lymphoid progenitors are still being discovered. Heterogeneity provides adaptability as hematopoiesis can be dramatically altered during infections, influencing numbers and types of cells that are produced.
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The density of CD10 corresponds to commitment and progression in the human B lymphoid lineage.
PLoS ONE
PUBLISHED: 06-06-2010
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Requirements for human B lymphopoiesis are still poorly understood, and that has hampered investigation of differentiation events. For example, there are few cell surface antigens that can be used as milestones of lineage progression. The CD10 ectoenzyme is one such marker and has been used to define CLP, but we found substantial tissue specific variations in CD10 levels, and there was no information about how that corresponded to differentiation options.
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Impact of small group size on neighbourhood influences in multilevel models.
J Epidemiol Community Health
PUBLISHED: 05-27-2010
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Given the growing availability of multilevel data from national surveys, researchers interested in contextual effects may find themselves with a small number of individuals per group. Although there is a growing body of literature on sample size in multilevel modelling, few have explored the impact of group sizes of less than five.
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Estrogenic compounds and estrogenicity in surface water, sediments, and organisms from Yundang Lagoon in Xiamen, China.
Arch. Environ. Contam. Toxicol.
PUBLISHED: 03-23-2010
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Seven estrogenic compounds--estrone (E1), 17?-estradiol (E2), 17?-ethynylestradiol (EE2), diethylstilbestrol (DES), nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA)--in sediments, surface water, pore water, and organisms were investigated and estrogenic activities were estimated by examining estradiol equivalent (EEQ) concentrations in Yundang Lagoon of Xiamen. The results showed that estrogenic compounds were present in all matrixes of interest: in surface water, ranging from 609.61 to 711.31 ng/l; in pore water, ranging from 562.12 to 1038.15 ng/l; in sediments, ranging from 1433.12 to 2060.41 ng/g; and in biota samples, ranging from 1373.76 to 3199.09 ng/g (lipid weight). NP was the predominant component in all collected samples and the highest concentration was 1964.80 ng/g in sediment. Total EEQ ranged from 4.56 to 13.79 ng/l in surface water, from 2.40 to 17.16 ng/l in pore water, and from 8.66 to 23.95 ng/g in sediments. However, major contributors to total EEQ concentrations were E2, E1, and DES. The EEQ concentrations in surface water samples were at a higher level in comparison to that reported in European countries. To biological sample, the highest level of total estrogenic compounds was found in the short-necked clam. Higher values of the biota-sediment accumulation factor (BSAF) were found in short-necked clam and black seabream, indicating that the living habits of organism and physical-chemical properties of estrogenic compounds might influence the bioavailability of estrogenic compounds in organisms.
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Competitive effect of Cu(II) and Zn(II) on the biosorption of lead(II) by Myriophyllum spicatum.
J. Hazard. Mater.
PUBLISHED: 02-10-2010
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Batch experiments were conducted to assess the effects of Cu(II) and Zn(II) on the biosorption of Pb(II) ions by fresh tissues of Myriophyllum spicatum. The biosorption of Pb(II) was examined for single, binary and ternary solutions at different initial concentrations and different pH values. The experimental results showed that the biosorption capacity increased with increasing pH from 2.0 to 6.0. Both Cu(II) and Zn(II) ions were found to have an adverse effect on the biosorption of Pb(II). The biosorption equilibrium data for single-metal solution were fitted to three isotherm models: Langmuir, Freundlich and Sips, and the Sips isotherm model gave the best fit for the experimental data. The maximum biosorption of Pb(II) in Pb-Cu binary system decreased with increasing concentration of copper ions, and the biosorption equilibrium data for the binary metal solution fitted the Langmuir competitive model well. Comparison between biosorption of Pb(II) and Cu(II) by M. spicatum in the binary solution could lead to the conclusion that the biosorbent (M. spicatum) has no preference of Pb(II) over Cu(II). Fourier transform infrared (FT-IR) spectroscopy was used to characterize the interaction between M. spicatum and Pb(II) ions. The results revealed that the carboxyl, hydroxyl and carbonyl groups are the main binding sites for Pb(II).
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Metabolic flux control at the pyruvate node in an anaerobic Escherichia coli strain with an active pyruvate dehydrogenase.
Appl. Environ. Microbiol.
PUBLISHED: 01-29-2010
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During anaerobic growth of Escherichia coli, pyruvate formate-lyase (PFL) and lactate dehydrogenase (LDH) channel pyruvate toward a mixture of fermentation products. We have introduced a third branch at the pyruvate node in a mutant of E. coli with a mutation in pyruvate dehydrogenase (PDH*) that renders the enzyme less sensitive to inhibition by NADH. The key starting enzymes of the three branches at the pyruvate node in such a mutant, PDH*, PFL, and LDH, have different metabolic potentials and kinetic properties. In such a mutant (strain QZ2), pyruvate flux through LDH was about 30%, with the remainder of the flux occurring through PFL, indicating that LDH is a preferred route of pyruvate conversion over PDH*. In a pfl mutant (strain YK167) with both PDH* and LDH activities, flux through PDH* was about 33% of the total, confirming the ability of LDH to outcompete the PDH pathway for pyruvate in vivo. Only in the absence of LDH (strain QZ3) was pyruvate carbon equally distributed between the PDH* and PFL pathways. A pfl mutant with LDH and PDH* activities, as well as a pfl ldh double mutant with PDH* activity, had a surprisingly low cell yield per mole of ATP (Y(ATP)) (about 7.0 g of cells per mol of ATP) compared to 10.9 g of cells per mol of ATP for the wild type. The lower Y(ATP) suggests the operation of a futile energy cycle in the absence of PFL in this strain. An understanding of the controls at the pyruvate node during anaerobic growth is expected to provide unique insights into rational metabolic engineering of E. coli and related bacteria for the production of various biobased products at high rates and yields.
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Occurrence and levels of polybrominated diphenyl ethers (PBDEs) in recent sediments and marine organisms from Xiamen offshore areas, China.
Mar. Pollut. Bull.
PUBLISHED: 01-12-2010
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Surface sediments and porewater from 12 sites within Xiamen offshore areas and organisms from a heavily contaminated site Yuandang Lagoon were sampled and analyzed for eight polybrominated diphenyl ethers (PBDEs) congeners (-28, -47, -99, -100, -153, -154, -183 and -209). The total concentrations of eight PBDEs ( summation operator(8)PBDEs) and BDE-209 in sediments ranged from 0.27 to 76.54ng/g with an average of 16.31ng/g and from 0.10 to 70.11ng/g with an average of 14.94ng/g, respectively. Concentrations of summation operator(8)PBDEs in porewater ranged from 2.5 to 34.1ng/L, with a mean value of 15.3ng/L. In this study, the partition coefficients (log K(oc)()) of PBDE congeners (without -209) were significantly correlated with their octanol-water partition coefficients (log K(OW)) (r(2)=0.74, P<0.01). summation operator(8)PBDE concentrations ranged from 0.33 to 1.26ng/g (lipid weight) in marine organisms, and PBDE congener patterns were significantly different between fish and clam, crab.
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Bis[2-meth-oxy-6-(3-pyridylmethyl-imino-meth-yl)phenolato-?N,O]copper(II).
Acta Crystallogr Sect E Struct Rep Online
PUBLISHED: 11-13-2009
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In the title complex, [Cu(C(14)H(13)N(2)O(2))(2)], the Cu(II) ion is located on a crystallographic inversion center. The complex thus adopts a square-planar trans-[CuN(2)O(2)] coordination geometry, with the Cu(II) ion coordinated by two 2-meth-oxy-6-(3-pyridylmethyl-imino-meth-yl)phenolate (Schiff base) ligands. The aryl and pyridyl rings in the Schiff base are almost perpendicular to each other, with a dihedral angle of 87.61?(6)° between the planes of the two six-membered rings. The pyridyl ring was refined using a disorder model with approximately 70% occupancy for the major component.
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Misspecification of the effect of race in fixed effects models of health inequalities.
Soc Sci Med
PUBLISHED: 10-01-2009
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The purpose of this study is to characterize the different results obtained when analyzing health inequalities data in which individuals are nested within their neighborhoods and a single level model is used to characterize risk rather than a multilevel model. The inability of single level models to characterize between neighborhood variance in risk may affect the level of risk attributed to black race if blacks are differentially distributed in high risk neighborhoods. The research replicates in Los Angeles an approach applied by a different group of researchers in Massachusetts (Subramanian, Chen, Rehkopf, Waterman, & Krieger, 2005). Single level and multilevel models were used to analyze Los Angeles County, California, US all-cause mortality data for the years 1989-1991, modeled as 29,936 cells (deaths and population denominators cross-tabulated by age, gender, and race/ethnicity) nested within 1552 census tracts. Overall blacks had 1.27 times the risk of mortality compared to whites. However, multilevel models demonstrated considerable between census tract variance in mortality for both blacks and whites which was partially explained by neighborhood poverty. Comparing the results of equivalent single level and multilevel models, the mortality odds ratio for blacks compared to the white reference group reversed itself, indicating greater risk for blacks in the single level model and lower risk in the multilevel model. Adding an area based socioeconomic measure (ABSM) to the single level model reduced but did not remove the discrepancy. Predictions of mortality risk for the interaction of race and age group demonstrate that all single level models exaggerated the mortality risk associated with black race. We conclude that characterizing health inequalities in mortality for blacks using single level models, which do not account for the cross level interaction created by the greater likelihood of black residence in neighborhoods where the risk of mortality is greater regardless of race, can exaggerate the risk of mortality attributable to the individual level effects of black race.
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Effects of titania nanoparticles on phosphorus fractions and its release in resuspended sediments under UV irradiation.
J. Hazard. Mater.
PUBLISHED: 08-19-2009
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Little is known about the effects of nano-TiO(2) on the transformation and transport of phosphorus (P) in resuspended sediments. Chemical sequential extraction was used to investigate P fractions and its release in resuspended sediments under the influence of nano-TiO(2) and UV irradiation. The results showed that the contents of sediment P in all fractions decreased with increasing nano-TiO(2) concentration in UV irradiation, while increased in the dark controls. Furthermore, P release from all fractions was greater in UV irradiation than in the controls. Elevated concentrations (10-50 mg L(-1)) of nano-TiO(2) in UV irradiation significantly facilitated the release of P from organic and Fe oxide fractions, possibly resulting from the partial photo-degradation of organic matter and photochemical transformation of Fe oxides. Apparently, nano-TiO(2) in UV irradiation did not immobilize the loosely sorbed P and reductant soluble P release from the resuspended sediments, possible because (1) some of P released from those fractions were refurnished by the P released from OM; (2) photocatalysis of nano-TiO(2) reduced binding capacity of the resuspended sediments. Our results suggest that the photocatalysis of nano-TiO(2) may offer the potential to regulate the transformation and transport of sediment P in the aquatic environment.
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Hierarchical additive modeling of nonlinear association with spatial correlations--an application to relate alcohol outlet density and neighborhood assault rates.
Stat Med
PUBLISHED: 04-30-2009
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Previous studies have suggested a link between alcohol outlets and assaults. In this paper, we explore the effects of alcohol availability on assaults at the census tract level over time. In addition, we use a natural experiment to check whether a sudden loss of alcohol outlets is associated with deeper decreasing in assault violence. Several features of the data raise statistical challenges: (1) the association between covariates (for example, the alcohol outlet density of each census tract) and the assault rates may be complex and therefore cannot be described using a linear model without covariates transformation, (2) the covariates may be highly correlated with each other, (3) there are a number of observations that have missing inputs, and (4) there is spatial association in assault rates at the census tract level. We propose a hierarchical additive model, where the nonlinear correlations and the complex interaction effects are modeled using the multiple additive regression trees and the residual spatial association in the assault rates that cannot be explained in the model are smoothed using a conditional autoregressive (CAR) method. We develop a two-stage algorithm that connects the nonparametric trees with CAR to look for important covariates associated with the assault rates, while taking into account the spatial association of assault rates in adjacent census tracts. The proposed method is applied to the Los Angeles assault data (1990-1999). To assess the efficiency of the method, the results are compared with those obtained from a hierarchical linear model.
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A differentiation pathway for B1 cells in adult bone marrow.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 03-23-2009
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The recent description of a Lin(-)AA4.1(+)CD19(+)B220(Lo/-) B1-specified progenitor (B1P) population in adult marrow adds support for the argument that these unique B cells arise from a distinct lineage. However, the origins of B1P were not investigated and their developmental relationships to conventional B2 cells remain unclear. We now report that B1P development is IL-7Ralpha-dependent, and negatively regulated by Bruton tyrosine kinase. Lymphoid characteristics of B1P were further studied with recombination activating gene (RAG)-1/GFP knock-in, RAG-1/Cre reporter, and VEX transgenic mice. Our results reveal that they are heterogeneous with respect to lymphocyte affiliation. RAG-1(+) early lymphoid progenitors and Lin(-)Sca-1(+)cKit(Lo)IL-7Ralpha(+) common lymphoid progenitors from adult marrow efficiently generated CD19(+)CD45R/B220(Lo/-) cells in vitro and in vivo. Moreover, early lymphoid progenitors and common lymphoid progenitors produced significant numbers of peritoneal CD11b(+)CD5(+) B1a and CD11b(+)CD5(-) B1b cells in vivo. Finally, 2-step transplantation experiments established a differentiation pathway between conventional lymphoid progenitors, B1P, and mature B1 lymphocytes. Thus, our findings indicate that at least some B1P can be produced in adult bone marrow from primitive B2 progenitors, and suggest a developmental relationship between the major categories of B lymphocytes.
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Levels of estrogenic compounds in Xiamen Bay sediment, China.
Mar. Pollut. Bull.
PUBLISHED: 03-12-2009
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Concentrations of seven estrogenic compounds, i.e., estrone (E1), 17beta-estradiol (E2), 17 alpha-ethynylestradiol(EE2), diethylstilbestrol (DES), nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA), were determined in sediments and pore water from Xiamen Bay in China, and their distributions and potential risks in the Bay were assessed. Total estrogenic compounds concentrations varied from 49.20 to 1230.69 ng/g dw in sediments and from 102.33 to 4376.60 ng/L in pore water. The highest levels of these compounds were found at Yundang Lagoon. The results showed that estrogenic compounds in Xiamen Bay originated mainly from municipal wastewaters. Compared with other areas, Xiamen Bay was contaminated with high levels of estrogen hormones. This contamination poses a potential threat to benthic organisms. Although a good relationship (r=0.94) was observed between the estrogenic compounds concentrations and total organic carbon (TOC) contents in sediments, which did not indicate that the sediment organic matter favors the accumulation of the detected estrogenic compounds.
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Nucleation and hysteresis of vapor-liquid phase transitions in confined spaces: effects of fluid-wall interaction.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 02-24-2009
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In this work, we propose a method to stabilize a nucleus in the framework of lattice density-functional theory (LDFT) by imposing a suitable constraint. Using this method, the shape of critical nucleus and height of the nucleation barrier can be determined without using a predefined nucleus as input. As an application of this method, we study the nucleation behavior of vapor-liquid transition in nanosquare pores with infinite length and relate the observed hysteresis loop on an adsorption isotherm to the nucleation mechanism. According to the dependence of hysteresis and the nucleation mechanism on the fluid-wall interaction, w , in this work, we have classified w into three regions ( w>0.9 , 0.1< or =w< or =0.9 , and w<0.1 ), which are denoted as strongly, moderately, and weakly attractive fluid-wall interaction, respectively. The dependence of hysteresis on the fluid-wall interaction is interpreted by the different nucleation mechanisms. Our constrained LDFT calculations also show that the different transition paths may induce different nucleation behaviors. The transition path dependence should be considered if morphological transition of nuclei exists during a nucleation process.
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Functional anergy in a subpopulation of naive B cells from healthy humans that express autoreactive immunoglobulin receptors.
J. Exp. Med.
PUBLISHED: 02-24-2009
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Self-reactive B cells not controlled by receptor editing or clonal deletion may become anergic. We report that fully mature human B cells negative for surface IgM and retaining only IgD are autoreactive and functionally attenuated (referred to as naive IgD(+)IgM(-) B cells [B(ND)]). These B(ND) cells typically make up 2.5% of B cells in the peripheral blood, have antibody variable region genes in germline (unmutated) configuration, and, by all current measures, are fully mature. Analysis of 95 recombinant antibodies expressed from the variable genes of single B(ND) cells demonstrated that they are predominantly autoreactive, binding to HEp-2 cell antigens and DNA. Upon B cell receptor cross-linkage, B(ND) cells have a reduced capacity to mobilize intracellular calcium or phosphorylate tyrosines, demonstrating that they are anergic. However, intense stimulation causes B(ND) cells to fully respond, suggesting that these cells could be the precursors of autoantibody secreting plasma cells in autoimmune diseases such as systemic lupus erythematosus or rheumatoid arthritis. This is the first identification of a distinct mature human B cell subset that is naturally autoreactive and controlled by the tolerizing mechanism of functional anergy.
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Polycyclic aromatic hydrocarbon contamination of recent sediments and marine organisms from Xiamen Bay, China.
Arch. Environ. Contam. Toxicol.
PUBLISHED: 01-05-2009
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Surface marine sediments from 12 sites within Xiamen Bay (XMB) and marine organisms (clam, crab, and fish) from a heavily polycyclic aromatic hydrocarbon (PAH)-contaminated site at Yuandang Lagoon were sampled and analyzed for 16 priority PAH content by gas chromatography/mass spectrometry. The total PAH concentrations in sediments ranged from 203.7 to 1590.5 ng/g, with an average value of 670.0 ng/g. Overall, the total PAH concentrations were relatively lower in the east coastal zone and significantly higher in Yuandang Lagoon. These concentrations were intermediate in comparison with those observed in other estuaries in China. The sources of PAH inputs to sediments in XMB were quantitatively determined by principal components analysis with multiple linear regression. The results showed that, on average, vehicle emissions, petroleum spills, and coal combustion contributed to 41, 36, and 23% of the total PAHs, respectively. Analysis of the PAH composition pattern in marine organisms showed that the total PAHs levels of fishes were lower than those of the clam and crab. The PAH burden of the crab and calm was characterized by the non-negligible occurrence of high-molecular-weight compounds, whereas the fish PAH pattern was dominated by the lower-molecular-weight compounds. In addition, the carcinogenic PAH benzo[a]pyrene was detected in all samples. Molecular indices based on isomeric PAH ratios differentiated the uptake pathway among organisms. The water soluble matter and the petroleum seemed to be the most favorable uptake pathway in fish from Yuandang Lagoon, whereas the crab and clam shared a mix uptake by the water-soluble and the particulate matter.
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Effects of lysed Enterococcus faecalis FK-23 on experimental allergic rhinitis in a murine model.
J Biomed Res
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In the current study, we sought to investigate whether lysed Enterococcus faecalis FK-23 (LFK), a heat-killed probiotic preparation, attenuated eosinophil influx into the upper airway and had immunomodulatory activity in a murine allergic rhinitis model. Eighteen BALB/c mice were divided into three groups; the ovalbumin (OVA)-sensitized/challenged group, which received saline orally for 6 weeks (OVA group), the OVA-sensitized/challenged group, which received LFK orally for 6 weeks (LFK-fed group), and the non-sensitized group, which received saline for 6 weeks (saline control group). Nasal rubbing and sneezing were monitored during the study. After the final challenge, interleukin (IL)-4, interferon (IFN)-?, and OVA-specific IgE levels in the sera and splenocyte culture supernatants were determined, eosinophilic infiltrate into the upper airway was quantified, and splenic CD4+CD25+ regulatory T cells (Tregs) were examined by flow cytometry. We found that nasal rubbing was significantly reduced in LFK-fed mice compared to the OVA group on d 27 and 35, and sneezing was significantly inhibited by LFK administration for 35 d. LFK-fed mice had significantly less eosinophil influx into the nasal mucosa than the OVA group. There were no significant differences between the LFK-fed group and OVA group in the serum and splenocyte culture supernatant levels of IL-4, IFN-?, and OVA-specific IgE. Interestingly, the LFK-fed mice had a significantly greater percentage of splenic CD4+CD25+ Tregs than OVA group. Our results indicate that oral administration of LFK may alleviate nasal symptoms, reduce nasal eosinophilia, and increase the percentage of CD4+CD25+ Tregs in experimental allergic rhinitis.
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Evaluating factors associated with unknown SEER Summary Stage 2000 derived from collaborative stage at central registry level.
J Registry Manag
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Cancer stage is critical for treatment planning and assessing disease prognosis. The percentage of unknown staged cancer cases varies considerably across state cancer registries; factors contributing to the variations in unknown stage have not been reported in the literature before. The purpose of this study was to examine whether these variations were influenced by demographic and/or clinical factors as well as the type of reporting facility.
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Global analysis of B cell selection using an immunoglobulin light chain-mediated model of autoreactivity.
J. Exp. Med.
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The important subtleties of B cell tolerance are best understood in a diverse immunoglobulin (Ig) repertoire context encoding a full spectrum of autoreactivity. To achieve this, we used mice expressing Ig? transgenes that confer varying degrees of autoreactivity within a diverse heavy chain (HC) repertoire. These transgenes, coupled with a biomarker to identify receptor-edited cells and combined with expression cloning of B cell receptors, allowed us to analyze tolerance throughout B cell development. We found that both the nature of the autoantigen and the Ig HC versus light chain (LC) contribution to autoreactivity dictate the developmental stage and mechanism of tolerance. Furthermore, although selection begins in the bone marrow, over one third of primary tolerance occurs in the periphery at the late transitional developmental stage. Notably, we demonstrate that the LC has profound effects on tolerance and can lead to exacerbated autoantibody production.
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Design, synthesis, and antibacterial activities of conformationally constrained kanamycin A derivatives.
J. Org. Chem.
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A series of conformationally constrained kanamycin A derivatives with a 2-hydroxyl group in ring I and a 5-hydroxyl group in ring II tethered by carbon chains were designed and synthesized. Pivotal 5,2-hydroxyl groups were exposed, and the kanamycin A intermediate was synthesized from 5, 2, 4?, 6?-di-O-benzylidene-protected tetraazidokanamycin A. Cyclic kanamycin A derivatives with intramolecular 8-, 9-, 10-, and 11-membered ethers were then prepared by cesium carbonate mediated Williamson ether synthesis or a ring-closing metathesis reaction. The kanamycin A derivatives were assayed against both susceptible and resistant bacterial strains. Although no derivative showed better antibacterial activities than kanamycin A, the antibacterial activities of these cyclic kanamycin A derivatives indeed varied with the length of the bridge. Moreover, different variations of activities were observed between the susceptible and resistant bacterial strains. More tightly constrained derivative 2 with a one-carbon bridge showed better activity than the others against susceptible strains, but it was much less effective for resistant bacterial strains than derivative 3 with a two-carbon bridge and derivative 6 with an unsaturated four-carbon bridge.
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Multilevel spatiotemporal change-point models for evaluating the effect of an alcohol outlet control policy on changes in neighborhood assaultive violence rates.
Spat Spatiotemporal Epidemiol
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Many previous studies have suggested a link between alcohol outlets and assaultive violence rates. In 1997 the City of New Orleans adopted a series of policies, e.g., increased license fee, additional enforcement staff, and expanded powers for the alcohol license board. The policies were specifically enacted to address the proliferation of problem alcohol outlets believed to be the source of a variety of social problems including assaultive violence. In this research, we evaluate the impact of a city level policy in New Orleans to address the problem alcohol outlets and their influence on assaultive violence. The spatial association between rates of assaultive violence at the census tract level (n=170) over a ten year period raises a challenge in statistical analysis. To meet this challenge we developed a hierarchical change-point model that controls for important covariates of assaultive violence and accounts for unexplained spatial and temporal variability. While our model is somewhat complex, its hierarchical Bayesian analysis is accessible via the WinBUGS software program. Keeping other effects fixed, the implementation of the new city level policy was associated with a decrease in the positive association between census tract level rates of assaultive violence and alcohol outlet density. Comparing several candidate change-point models using the DIC criterion, the positive association began decreasing the year of the policy implementation. The magnitude of the association continued to decrease for roughly two years and then stabilized. We also created maps of the fitted assaultive violence rates in New Orleans, as well as spatial residual maps which, together with Morans Is, suggest that the spatial variation of the data is well accounted for by our model. We reach the conclusion that the implementation of the policy is associated with a significant decrease in the positive relationship between assaultive violence and the off-sale alcohol outlet density.
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CD86 is expressed on murine hematopoietic stem cells and denotes lymphopoietic potential.
Blood
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A unique subset of CD86(-) HSCs was previously discovered in mice that were old or chronically stimulated with lipopolysaccharide. Functionally defective HSCs were also present in those animals, and we now show that CD86(-) CD150(+) CD48(-) HSCs from normal adult mice are particularly poor at restoring the adaptive immune system. Levels of the marker are high on all progenitors with lymphopoietic potential, and progressive loss helps to establish relations between progenitors corresponding to myeloid and erythroid lineages. CD86 represents an important tool for subdividing HSCs in several circumstances, identifying those unlikely to generate a full spectrum of hematopoietic cells.
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Amino acid substitutions at glutamate-354 in dihydrolipoamide dehydrogenase of Escherichia coli lower the sensitivity of pyruvate dehydrogenase to NADH.
Microbiology (Reading, Engl.)
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Pyruvate dehydrogenase (PDH) of Escherichia coli is inhibited by NADH. This inhibition is partially reversed by mutational alteration of the dihydrolipoamide dehydrogenase (LPD) component of the PDH complex (E354K or H322Y). Such a mutation in lpd led to a PDH complex that was functional in an anaerobic culture as seen by restoration of anaerobic growth of a pflB, ldhA double mutant of E. coli utilizing a PDH- and alcohol dehydrogenase-dependent homoethanol fermentation pathway. The glutamate at position 354 in LPD was systematically changed to all of the other natural amino acids to evaluate the physiological consequences. These amino acid replacements did not affect the PDH-dependent aerobic growth. With the exception of E354M, all changes also restored PDH-dependent anaerobic growth of and fermentation by an ldhA, pflB double mutant. The PDH complex with an LPD alteration E354G, E354P or E354W had an approximately 20-fold increase in the apparent K(i) for NADH compared with the native complex. The apparent K(m) for pyruvate or NAD(+) for the mutated forms of PDH was not significantly different from that of the native enzyme. A structural model of LPD suggests that the amino acid at position 354 could influence movement of NADH from its binding site to the surface. These results indicate that glutamate at position 354 plays a structural role in establishing the NADH sensitivity of LPD and the PDH complex by restricting movement of the product/substrate NADH, although this amino acid is not directly associated with NAD(H) binding.
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Replenishing B lymphocytes in health and disease.
Curr. Opin. Immunol.
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The path from hematopoietic stem cells (HSCs) to functional B lymphocytes has long been appreciated as a basic model of differentiation, but much clinically relevant information has also been obtained. It is now possible to conduct single cell studies with increasingly high resolution, revealing that individual stem and progenitor cells differ from each other with respect to differentiation potential and fates. B lymphopoiesis is now seen as a gradual and unsynchronized process where progenitors eventually become B lineage restricted. Major milestones have been identified, but a precise sequence need not be followed and oscillation between states is possible. It is not yet clear if this versatility has survival value, but information is accumulating about infections and age-related changes.
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Metabolic engineering of thermophilic Bacillus licheniformis for chiral pure D-2,3-butanediol production.
Biotechnol. Bioeng.
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2,3-Butanediol is an important compound that can be used in many areas, especially as a platform chemical and liquid fuel. But traditional 2,3-butanediol producing microorganisms, such as Klebsiella pneumonia and K. xoytoca, are pathogens and they can only ferment sugars at 37°C. Here, we reported a newly developed Bacillus licheniformis. A protoplast transformation system was developed and optimized for this organism. With this transformation method, a marker-less gene deletion protocol was successfully used to knock out the ldh gene of B. licheniformis BL1 and BL3. BL1 was isolated earlier from soil for lactate production and it was further evolved to BL3 for xylose utilization. Combined with pH and aeration control, ldh mutant BL5 and BL8 can efficiently ferment glucose and xylose to D-(-) 2,3-butanediol at 50°C, pH 5.0. For glucose and xylose, the specific 2,3-butanediol productivities are 29.4 and 26.1 mM/h, respectively. The yield is 0.73 mol/mol for BL8 in xylose and 0.9 mol/mol for BL5 and BL8 in glucose. The D-(-) 2,3-butanediol optical purity is more than 98%. As far as we know, this is the first reported high temperature butanediol producer to match the simultaneous saccharification and fermentation conditions. Therefore, it has potential to further lower butanediol producing cost with low cost lignocellulosic biomass in the near future.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.