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Query: UNIPROT:P30536 (PBS)
 9,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Understanding factors responsible for the fluorescence behavior of conjugated polyelectrolytes and modulation of their behavior are important for their application as functional materials. The interaction between the anionic poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}copolymer (PBS-PFP) and cationic gemini surfactants alpha,omega-(CmH2m+1N+(CH3)2)2(CH2)s(Br-)2 (m-s-m; m=12, s=2, 3, 5, 6, 10, and 12) has been studied experimentally in aqueous solution. These surfactants are chosen to see whether molecular recognition and self-assembly occurs between the oppositely charged conjugated polyelectrolyte and gemini surfactant when the spacer length on the surfactant is similar to the intercharge separation on the polymer. Without surfactants, PBS-PFP exists as aggregates. These are broken up upon addition of gemini surfactants. However, as anticipated, the behavior strongly depends upon spacer length (s). Fluorescence measurements show three surfactant concentration regimes: At low concentrations (<2x10(-6) M) quenching occurs and is most marked with the small spacer 12-2-12; at intermediate concentrations (approximately 2x10(-6)-10(-3) M), fluorescence intensity is constant, with a 12-carbon spacer 12-12-12 showing the strongest fluorescence; above the critical micelle concentration (CMC; approximately 10(-3) M) increases in emission intensity are seen in all cases and are largest with the intermediate spacers 12-5-12 and 12-6-12, where the spacer length most closely matches the distance between monomer units on the polymer. With longer spacer length surfactants, surface tension measurements for concentrations below the CMC reveal the presence of polymer-surfactant aggregates at the air-water interface, possibly reflecting increased hydrophobicity. Above the CMC, small-angle neutron scattering experiments for the 12-6-12 system show the presence of spherical aggregates, both for the pure surfactant and for polyelectrolyte/gemini mixtures. Molecular dynamics simulations help rationalize these observations and show that there is a very fine balance between electrostatic and hydrophobic interactions. With the shortest spacer 12-2-12, Coulombic interactions are dominant, while for the longest spacer 12-12-12 the driving force involves hydrophobic interactions. Qualitatively, with the intermediate 12-5-12 and 12-6-12 systems, the optimum balance is observed between Coulombic and hydrophobic interactions, explaining their strong fluorescence enhancement.
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PMID:Interplay of electrostatic and hydrophobic effects with binding of cationic gemini surfactants and a conjugated polyanion: experimental and molecular modeling studies. 1742 60

The aim of this study is to target the interference therapy of signal transduction which is a novel therapeutic strategy in laryngeal squamous cell carcinoma (LSCC). We successfully constructed recombinant adenoviruses Ad-p14ARF, and Ad-antisense EGFR using AdEasy-1 vector System. Clonogenic cell assay, western blotting assay, 3'(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, flow cytometer (FCM) assay, and immunocytochemical technique were designed to examine the inhibition of proliferation, protein expression of p14ARF and EGFR and induction of differentiation, respectively. Furthermore the synergistic effect of Ad-p14ARF and Ad-antisense EGFR on Hep-2 cell was examined. We successfully used AdEasy-1 vector system to construct recombinant adenoviruses Ad-p14ARF and Ad-antisense EGFR. The activity of proliferation of Hep-2 cells was inhibited markedly by infecting Ad-p14ARF or Ad-antisense EGFR by comparing Ad-sense EGFR (P=0.005) with vector control (Ad-Ctrl) (P=0.005) and with PBS (P=0.003). This effect, combining Ad-antisense-EGFR with Ad-p14ARF became more noticeable than alone (P=0.01, P=0.02, respectively). P14 ARF protein overexpression, EGFR protein down expression, and inhibition of proliferation were observed in Hep-2 cells infected by either Ad-p14ARF or Ad-antisense EGFR. FCM revealed that the proportion of apoptosis cells transfected by Ad-p14ARF and Ad-antisense EGFR increased more obviously than the control. The proportion of (Hep-2 cells in) G0/G1 phases was increased by up to 78.5, 77.7, and 86.9% in Ad-antisense EGFR, Ad-p14ARF, and Ad-antisense EGFR+Ad-p14ARF, respectively. Our findings demonstrated that not only EGFR but p14ARF also plays a major role on the genesis and in modulating the cell growth and differentiation of human laryngocarcinoma. They efficaciously blocked the signal transduction of human laryngocarcinoma cell, and may therefore, be an effective potential target of gene therapy to prevent human laryngocarcinoma cell proliferation.
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PMID:Signal transduction-related gene transfer leads to inhibition of proliferation and induction of differentiation in laryngeal squamous cell carcinoma in vitro. 1762 21

A thermoresponsive copolymer, trimethyl chitosan-g-poly(N-isopropylacrylamide) (TMC-g-PNIPAAm), was synthesized by coupling PNIPAAm-COOH to TMC. Their molecular structures were characterized by 1HNMR. The lower critical solution temperature (LCST) of TMC-g-PNIPAAm in PBS was measured as 32 degrees C by dynamic light scattering (DLS) and UV-vis spectroscopy, regardless of the grafting ratios. Upon mixing with DNA, TMC/DNA particles were formed, whose size and morphology were investigated by DLS and transmission electron microscopy, respectively. The particle size ranged from 200 to 900 nm depending on the N/P ratio and was less influenced by the temperature variation. The majority of the particles have spherical morphology. The zeta potentials of these particles were increased along with the N/P ratio. At a given N/P ratio, the zeta potentials were almost constant at 25 degrees C regardless of the existence of serum proteins. However, the values were significantly decreased at 37 degrees C in a solution containing serum protein. The affinity between DNA and TMC was examined by ethidium bromide competitive binding assay. TMC-g-PNIPAAm has stronger ability to combine with DNA at 40 degrees C when the PNIPAAm chain is collapsed. Gel electrophoresis results reveal that the vectors/DNA complexes can be formed regardless of the incubation temperature. HEK293 cell line was chosen as a model to study cellular uptake of the TMC-g-PNIPAAm/DNA particles, gene transfection and cytotoxicity. The grafting of PNIPAAm will not affect cellular uptake of the particles at 37 degrees C. The level of gene transfection could be thermally controlled. By using a temperature variation protocol, i.e. incubation of the cultured cells at 25 degrees C for a while, the gene transfection efficiency was significantly improved. Finally, the optimized gene transfection efficiency achieved by TMC-g-PNIPAAm is comparable to Lipofectamine 2000. No obvious cytotoxicity was detected for the TMC-g-PNIPAAm/DNA particles. These results suggest that TMC-g-PNIPAAm is an effective thermoresponsive gene carrier with minimal cytotoxicity, which has great promise for practical applications.
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PMID:The gene transfection efficiency of thermoresponsive N,N,N-trimethyl chitosan chloride-g-poly(N-isopropylacrylamide) copolymer. 1764 Jul 26

This study evaluated the performance of the DeLaval cell counter (DCC) when analyzing ovine milk with different soak times (defined as the permanence time of samples within the DCC cassette before starting the DCC counting procedure) in diluted and undiluted milk samples in 2 dairy sheep breeds. A total of 101 composite ovine milk samples (50 from Assaf ewes and 51 from Churra ewes), ranging between 50 x 10(3) and 2,200 x 10(3) cells/mL, were divided into 10 aliquots/milk to be analyzed by DCC. Four undiluted aliquots and 4 aliquots diluted 1:1 in PBS were analyzed by using soak times of 0, 1, 2, and 3 min/aliquot, and the other 2 aliquots were diluted 1:1 in propidium iodide or ethidium bromide staining solutions and analyzed by DCC. Milk samples were also analyzed by the Fossomatic method, as a reference. All analyses were carried out in duplicate. Undiluted milk samples with soak times >or=1 min showed large coefficients of regression (b = 0.96 to 0.98) and correlation (r > 0.99) when compared with the Fossomatic method. In these samples, DCC gave repeatability standard deviations (s(r) = 35 to 51 x 10(3) cells/mL) lower than other DCC analytical conditions (s(r) = 49 to 74 x 10(3) cells/mL), and their log SCC means (5.51 to 5.52) were close to the reference value (5.56). The log SCC means corresponding to samples diluted 1:1 in staining solutions (5.55) did not differ from the reference value; however, these aliquots had lower regression coefficients (b: 0.92 to 0.93). Samples diluted 1:1 in PBS and undiluted samples with a 0-min soak time showed a global accuracy similar to or lower than undiluted samples with soak times >or=1 min. Breed did not seem to affect the results. We concluded that undiluted raw milk with a soak time >or=1 min and analyzed by DCC shows suitable overall accuracy in ovine milk compared with the reference method and can be considered as the best option for on-farm use from an operational point of view.
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PMID:Short communication: Evaluation of the overall accuracy of the DeLaval cell counter for somatic cell count in ovine milk: effect of soak time in diluted and undiluted milk samples. 1865 Feb 87

In this study, cationic nanoparticles self-assembled from the amphiphilic copolymer poly(N-methyldietheneamine sebacate)-co-[(cholesteryl oxocarbonylamido ethyl) methyl bis(ethylene) ammonium bromide] sebacate) (P(MDS-co-CES) were synthesized and used to deliver Bcl-2 targeted siRNA into HepG2, HeLa and MDA-MB-231 cell lines, and downregulate Bcl-2 mRNA expression levels. Confocal microscopic studies show that the nanoparticles were able to complex with siRNA and deliver it inside the cells efficiently, but siRNA was easily dissociated from the complexes in the cytoplasm for its biological functions. Bcl-2 mRNA expression levels as low as 10% were achieved after treatment with nanoparticle/siRNA complexes. The downregulation efficiency of Bcl-2 mRNA level was similar to that mediated by Lipofectamine but higher than that induced by PEI. PEG was also conjugated to siRNA via a cleavable disulfide bond, and nanoparticle/siRNA-PEG complexes showed no significant protein adsorption as compared with 26 and 17% for blank nanoparticles and nanoparticle/siRNA complexes, respectively. The presence of serum caused slight aggregation of nanoparticle/siRNA or nanoparticle/siRNA-PEG complexes. However, the size of the complexes was still below 250 nm after being incubated in PBS containing 10% serum for 4 h. On the other hand, PEGylated siRNA delivered by the nanoparticles downregulated Bcl-2 mRNA expression level in the cells as efficiently as unmodified siRNA. Bcl-2 protein was also downregulated efficiently by nanoparticle/siRNA complexes in all cell lines tested. The downregulation of Bcl-2 mRNA or Bcl-2 protein did not show significant cell death in the tested siRNA and polymer concentration range. However, the delivery of siRNA sensitized HeLa cells to paclitaxel treatment, yielding significant improvement over the untreated cells (p<0.05). These cationic nanoparticles may be potentially employed to downregulate Bcl-2 expression and sensitize cancer cells to anticancer drugs for more efficient chemotherapy.
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PMID:Efficient delivery of Bcl-2-targeted siRNA using cationic polymer nanoparticles: downregulating mRNA expression level and sensitizing cancer cells to anticancer drug. 1907 31

The cytotoxic activity of Maillard reaction products and coffee was studied using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay and the neutral red uptake (NRU) assay. Equimolar mixtures of sugars and lysine were heated at 120 degrees C and used to stimulate bovine aorta endothelial cells for 24 h. The cytotoxic activity increased with increase in educt concentration and heating time. Mixtures containing ribose were most active, followed by lactose and glucose. Hydrogen peroxide, which was present in the Maillard mixtures in concentrations between 7 and 87 microM, was identified as one of their major cytotoxic components. H2O2-concentrations increased further up to 130 microM under cell culture conditions. Filter coffee, espresso, and green coffee extract reduced cell viability significantly to 10, 19, and 83% of PBS-treated control. The effect was largely attenuated by the addition of catalase. Nil, 33, and 41 microM H2O2 was measured in green coffee extract, filter coffee, and espresso, respectively, increasing to 13, 369, and 333 microM during cell culture conditions. No additional H2O2 formation was detected when coffee was incubated for up to 5 h without further treatment. In conclusion, hydrogen peroxide is a major product in Maillard mixtures and coffee inducing cell death in vitro.
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PMID:Identification of hydrogen peroxide as a major cytotoxic component in Maillard reaction mixtures and coffee. 1919 86

Liposomes as a lipid-based system have been shown to be an effective adjuvant formulation. In this study, the role of liposome charge in induction of a Th1 type of immune response and protection against leishmaniasis in BALB/c mice was studied. Liposomes containing rgp63 were prepared by Dehydration-Rehydration Vesicle (DRV) method. Neutral liposomes consisted of dipalmitoylphosphatidylcholine and cholesterol. Positively and negatively charged liposomes were prepared by adding dimethyldioctadecylammonium bromide (DDAB) or dicetyl phosphate (DCP) to the neutral liposome formulation, respectively. Female BALB/c mice were immunized subcutaneously with negatively, positively charged or neutral liposomes encapsulated with rgp63, rgp63 in soluble form or PBS, three times in 3week intervals. The extent of protection and type of immune response generated were studied in different groups of mice. The group of mice immunized with rgp63 encapsulated in neutral liposomes showed a significantly (P<0.01) smaller footpad swelling upon challenge with Leishmania major compared with positively or negatively charged liposomes. The mice immunized with neutral liposomes also showed a significantly (P<0.01) the lowest splenic parasite burden, the highest IgG2a/IgG1 ratio and IFN-gamma production and the lowest IL-4 level compared to the other groups. The results indicated that a Th1 type of immune response was induced in mice immunized with neutral liposomes more efficiently than positively charged liposomes and conversely negatively charged liposomes induced a Th2 type of immune response.
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PMID:The role of liposome charge on immune response generated in BALB/c mice immunized with recombinant major surface glycoprotein of Leishmania (rgp63). 1921 Oct 22

The electrochemical properties of catechin at single-walled carbon nanotubes (SWNTs)-cetylramethylammonium bromide (CTAB) modified glassy carbon electrodes (GCE) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The SWNTs-CTAB film was characterized with transmission electron microscopy (TEM). A series of parameters including pH of supporting electrolyte, accumulation potential and accumulation time were optimized. There were three peaks of catechin at SWNTs-CTAB/GCE in the potential range of -0.4-1.0 V in PBS (pH 7.0): a reversible pair of peaks and an irreversible peak of the anodic peak. The reductive peak current increased linearly with the concentration of catechin in the range from 3.72 x 10(-10) to 2.38 x 10(-9) M. The detection limit was 1.12 x 10(-10) M. The SWNTs-CTAB/GCE showed good stability and low detection limit, and could be applied to detect trace catechin.
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PMID:Electrochemical properties of catechin at a single-walled carbon nanotubes-cetylramethylammonium bromide modified electrode. 1938 71

In this work, thermoresponsive diblock copolymers, poly[2-(2-methoxyethoxy) ethyl methacrylate]-b-poly(2-hydroxyethyl methacrylate) (PMEO(2)MA-b-PHEMA) with low polydispersity were synthesized by atomic transfer radical polymerization(ATRP). Low molecular weight (LWM) polyethylenimine (PEI, 1200Da) was then grafted to 1,1'-carbonyldiimidazole (CDI)-activated PMEO(2)MA-b-PHEMA to fabricate PEI-g-(PMEO(2)MA-b-PHEMA) (PEIMH) copolymer vectors. The LCSTs of PEIMHs with 3 and 8 grafted PEI side chains, separately termed as PEIMH-1 and PEIMH-2, were 32.5 and 38.7 degrees C in PBS solution. Variable temperature agarose retardation, Zeta potential and time-resolved fluorescence assays were performed to elucidate the temperature sensitive DNA condensation. It showed that DNA was condensed more efficiently by PEIMH, and the collapse of PMEO(2)MA chains led to more exposure of surface positive charges of PEIMH-1/pDNA complexes while temperature was above LCST. Variable temperature time-resolved fluorescence measurement of lifetimes of bound and free ethidium bromide (EB) unveiled that the population of EB at different states was dependent on temperature. At a temperature above LCST, the collapsed PMEO(2)MA polymer chains squeezed the loosely bound EB out of complex to become free species; thereby DNA was more tightly packaged by PEIMH-1. Temporary cooling was shown to improve the transfection efficiency of PEIMH-1 in COS-7 and HEK293 cell lines. The variable temperature protocol is more efficient in improving gene expression level in HEK293 cells. The transfection efficiency was equivalent or superior to that of PEI25K at an optimal weight ratio of vector/DNA. Furthermore, the cytotoxicity of PEIMH-1 was considerably lower than that of control PEI25K.
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PMID:Temperature-tuned DNA condensation and gene transfection by PEI-g-(PMEO(2)MA-b-PHEMA) copolymer-based nonviral vectors. 1978 98

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which measures the reduction of MTT, is commonly used to validate the viability of metabolically active cells. This study was conducted to evaluate and validate the MTT assay to assess the spermatozoal viability of Nili-Ravi buffalo bulls and compare the efficiency of the test with the supravital staining technique (eosin and nigrosin) and the hypoosmotic swelling test. Fresh semen samples from breeding Nili-Ravi buffalo bulls (n = 25) were collected using an artificial vagina. After assessing the quality of the semen for routine variables, the MTT assay was carried out in PBS. Results revealed a correlation (r = 0.979; P < 0.001) between the viability of spermatozoa and the rate of reduction of MTT. The other proportions of same semen samples showed a poor relationship between the eosin and nigrosin test (r = -0.25), the hypoosmotic swelling test (r = -0.12), and motility (r = -0.15). However, the MTT assay was found to be superior compared with other tests because it was able to determine those spermatozoa that were more than 90% viable. In conclusion, the MTT assay is a simple, robust test that can be used to select Nili-Ravi buffalo bulls on the basis of spermatozoa quality.
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PMID:Assessment of buffalo semen with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. 2002 42


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