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Biological Analyses (biological + analysis)
Selected AbstractsPicoliter-volume aqueous droplets in oil: Electrochemical detection and yeast cell electroporationELECTROPHORESIS, Issue 10 2006Chunxiong Luo Abstract An electrochemical detection method was introduced for aqueous droplet analysis in oil phase of microfluidic devices. This method is based on the electrochemical signal difference between aqueous and oil. Applying a low alternating current,(AC) voltage to a couple of Au microelectrodes, this method can offer size information and ion concentration range from 0.02,mmol/L to 1,mol/L of tens of picoliter to nanoliter aqueous droplets. Alternatively, applying a relative high AC voltage (18,Vpp) at a frequency of 1,kHz leads to electroporation of yeast cells encapsulated into picoliter droplets. We believe that this simple technique is useful for a number of aqueous droplet-based chemical and biological analyses as well as cell electroporation. [source] Droplet fusion by alternating current (AC) field electrocoalescence in microchannelsELECTROPHORESIS, Issue 19 2005Max Chabert Abstract We present a system for the electrocoalescence of microfluidic droplets immersed in an immiscible solvent, where the undeformed droplet diameters are comparable to the channel diameter. The electrodes are not in direct contact with the carrier liquid or the droplets, thereby minimizing the risk of cross-contamination between different coalescence events. Results are presented for the coalescence of buffered aqueous droplets in both quiescent and flowing fluorocarbon streams, and on-flight coalescence is demonstrated. The capillary-based system presented here is readily amenable to further miniaturization to any lab-on-a-chip application where the conductivity of the droplets is much greater than the conductivity of the stream containing them, and should aid in the further application of droplet microreactors to biological analyses. [source] Distribution of cytochrome P4501A1,inducing chemicals in sediments of the Delaware River-Bay system, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2002Daniel L. McCoy Abstract The Delaware River-Bays system, USA, was the subject of a study by the National Oceanic and Atmospheric Administration that involved chemical and biological analyses, including the use of the biomarker P450 human reporter gene system (HRGS) to document the occurrence and distribution of cytochrome P450 (CYP) 1A1-inducing compounds. Sediment extracts from 81 locations along the Delaware River, Delaware Bay and immediate coastline were tested by utilizing HRGS as an inexpensive screening test, and were also analyzed for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls, with selected stations analyzed for dioxins and furans. Benthic community degradation has been observed when benzo[a]pyrene equivalents (BaPEq) exceeded 60 ,g/g. The average levels of BaPEq for the largely industrialized upper, middle, and lower regions of the Delaware River were 107, 62, and 5 ,g/g, respectively, excluding outliers. Tributaries leading into river averaged 21 ,g/g BaPEq, whereas the central Bay and open coast had relatively low values (2.0 and 0.5 ,g/g BaPEq, respectively). The HRGS values were highly correlated with total PAHs measured in the same sediment samples (r2 = 0.81). Overall, contamination levels consistently decreased from the upper and middle river sites as collection locations progressed down through the lower river and bay to the coast. Thus, despite the relatively high contaminant load in the river system, Delaware Bay and the immediate coastline seem to have relatively low levels of contaminants, and, therefore, impacts on the benthic organisms in the bay and coast would not be expected from these findings. [source] Application of capillary electrophoresis mass spectrometry to the characterization of bacterial lipopolysaccharidesMASS SPECTROMETRY REVIEWS, Issue 1 2007Jianjun Li Abstract Capillary electrophoresis (CE) is a high-resolution technique for the separation of complex biological mixtures and has been widely applied to biological analyses. The coupling of capillary electrophoresis with mass spectrometry (MS) provides a powerful approach for rapid identification of target analytes present at trace levels in biological matrices, and for structural characterization of complex biomolecules. Here we review the analytical potential of combined capillary electrophoresis electrospray mass spectrometry (CE-MS) for the analysis of bacterial lipopolysaccharides (LPS). This hyphened methodology facilitates the determination of closely related LPS glycoform and isoform families by exploiting differences in their unique molecular conformations and ionic charge distributions by electrophoretic separation. On-line CE-MS also provides an additional avenue to improve detection limits, which has been successfully applied to directly probe oligosaccharide LPS glycoform populations of bacteria isolated from infected animal models without the need for further passage. © 2006 Wiley Periodicals, Inc., Mass Spec Rev 26:35,50, 2007 [source] Detection of serotype k Streptococcus mutans in Thai subjectsMOLECULAR ORAL MICROBIOLOGY, Issue 5 2009J. Lapirattanakul Introduction:,Streptococcus mutans, known to be a pathogen of dental caries as well as bacteremia and infective endocarditis, is classified into four serotypes, c, e, f and k, based on the structures of serotype-specific polysaccharides. Serotype k was recently designated using blood isolates from Japanese subjects and such strains are considered to be virulent in the bloodstream. The purpose of the present study was to analyse the serotype distribution of strains isolated from Thai subjects and determine whether serotype k strains were present. Methods:, A total of 250 S. mutans strains were isolated from 50 Thai subjects, and serotypes of all strains were determined. Then, molecular and biological analyses were carried out for serotype k strains. Results:, Immunodiffusion and polymerase chain reaction analyses showed that serotype c was the most prevalent (70%), followed by serotypes e (22.8%), f (4.4%) and k (2.8%), which indicated that serotype k S. mutans strains occurred in Thai individuals at a similar rate to that previously reported for Japanese and Finnish populations. Molecular analyses of the seven serotype k strains showed extremely low expression of rgpE, which is related to glucose side-chain formation in serotype-specific rhamnose-glucose polymers, similar to previous reports for those other populations. In addition, analysis of the biological properties of the seven serotype k strains demonstrated low levels of sucrose-dependent adhesion, cellular hydrophobicity, dextran-binding activity and phagocytosis susceptibility by human polymorphonuclear leukocytes, which are characteristics similar to those of serotype k strains previously isolated in Japan. Conclusion:, Our results indicate the possibility of a worldwide prevalence of serotype k strains with properties in common with those of previously reported strains. [source] An accumulative site-specific gene integration system using cre recombinase-mediated cassette exchangeBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2010Yujiro Kameyama Abstract The Cre- loxP system is frequently used for site-specific recombination in animal cells. The equilibrium and specificity of the recombination reaction can be controlled using mutated loxPs. In the present study, we designed an accumulative site-specific gene integration system using Cre recombinase and mutated loxPs in which the Cre-mediated cassette exchange reaction is infinitely repeatable for target gene integration into loxP target sites. To evaluate the feasibility and usefulness of this system, a series of integration reactions were repeated and confirmed in vitro using Cre recombinase protein and plasmids. Accumulative gene integration was also performed on the genome of Chinese hamster ovary (CHO) cells. The results indicated that the system was applicable for repeated gene integration of multiple genes to the target sites on both plasmids and CHO cell genomes. This gene integration system provides a novel strategy for gene amplification and for biological analyses of gene function through the genetic modification of cells and organisms. Biotechnol. Bioeng. 2010;105: 1106,1114. © 2009 Wiley Periodicals, Inc. [source] Acetaldehyde plasma polymer-coated PET fibers for endothelial cell patterning: Chemical, topographical, and biological analysisJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2010Afra Hadjizadeh Abstract The objective of this study was to produce fibrous biomaterials with cell adhesive and cell repulsive capabilities for biomedical applications. To this aim, the surface of 100-,m diameter polyethylene terephthalate fibers were functionalized with acetaldehyde plasma polymer deposition followed by carboxymethyl dextran grafting onto the aldehyde-coated surfaces via a polyethyleneimine interlayer. The performance of the surface modification steps were confirmed by surface chemical composition analysis using X-ray photoelectron spectroscopy, surface topography analysis by atomic force microscopy, and scanning electron microscopy. The acetaldehyde plasma polymer-coated and polyethyleneimine-grafted substrates promoted human umbilical vein endothelial cells attachment, spreading and actin filaments/focal adhesions formation. In contrast, carboxymethyl dextran-grafted substrates resisted cell adhesion. These observations demonstrate that the current surface-modified polymer fibers can be used in tissue engineering applications, such as cell patterning substrates or vascular prosthesis development. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. [source] Applications of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) in pharmaceutical and biological analysisBIOMEDICAL CHROMATOGRAPHY, Issue 10 2010Abdalla A. Elbashir Abstract Conductivity detection, which is universal in capillary electrophoresis (CE), has received considerable attention, since the introduction of the axial capacitively coupled contactless detector C4D in 1998. This detector is made of two electrodes which are placed cylindrically around the CE capillary and connected to the AC oscillator. The distance between the electrodes is the detection gap. In this review, applications of CE and MCE with C4D in pharmaceutical and biological analysis are presented. [source] Total Synthesis of the Cyclodepsipeptide Apratoxin A and Its Analogues and Assessment of Their Biological ActivitiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2006Dawei Ma Prof. Dr. Abstract A novel total synthesis of apratoxin A is described, with key steps including the assembly of its ketide segment through a D -proline-catalyzed direct aldol reaction and Oppolzer's anti aldol reaction and the preparation of its thiazoline unit in a biomimetic synthesis. An oxazoline analogue of apratoxin A has also been elaborated by a similar approach. This compound has a potency against HeLa cell proliferation only slightly lower than that of apratoxin A, whilst a C(40)-demethylated oxazoline analogue of apratoxin A displays a much lower cytotoxicity and the C(37)-epimer and C(37) demethylation product of this new analogue are inactive. These results suggest that the two methyl groups at C(37) and C(40) and the stereochemistry at C(37) are essential for the potent cellular activity of the oxazoline analogue of apratoxin A. Further biological analysis revealed that both synthetic apratoxin A and its oxazoline analogue inhibited cell proliferation by causing cell cycle arrest in the G1 phase. [source] Gene expression profiling differentiates autism case,controls and phenotypic variants of autism spectrum disorders: evidence for circadian rhythm dysfunction in severe autismAUTISM RESEARCH, Issue 2 2009Valerie W. Hu Abstract Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by delayed/abnormal language development, deficits in social interaction, repetitive behaviors and restricted interests. The heterogeneity in clinical presentation of ASD, likely due to different etiologies, complicates genetic/biological analyses of these disorders. DNA microarray analyses were conducted on 116 lymphoblastoid cell lines (LCL) from individuals with idiopathic autism who are divided into three phenotypic subgroups according to severity scores from the commonly used Autism Diagnostic Interview-Revised questionnaire and age-matched, nonautistic controls. Statistical analyses of gene expression data from control LCL against that of LCL from ASD probands identify genes for which expression levels are either quantitatively or qualitatively associated with phenotypic severity. Comparison of the significant differentially expressed genes from each subgroup relative to the control group reveals differentially expressed genes unique to each subgroup as well as genes in common across subgroups. Among the findings unique to the most severely affected ASD group are 15 genes that regulate circadian rhythm, which has been shown to have multiple effects on neurological as well as metabolic functions commonly dysregulated in autism. Among the genes common to all three subgroups of ASD are 20 novel genes mostly in putative noncoding regions, which appear to associate with androgen sensitivity and which may underlie the strong 4:1 bias toward affected males. [source] | ||||||||||||||||