Polyelectrolyte complex micelles by self-assembly of polypeptide-based triblock copolymer for doxorubicin delivery

AbstractPolyelectrolyte complex micelles were prepared by self-assembly of polypeptide-based triblock copolymer as a new drug carrier for cancer chemotherapy. The triblock copolymer, poly(l-aspartic acid)-b-poly(ethylene glycol)-b-poly(l-aspartic acid) (PLD-b-PEG-b-PLD), spontaneously self-assembled with doxorubicin (DOX) via electrostatic interactions to form spherical micelles with a particle size of 60–80 nm (triblock ionomer complexes micelles, TBIC micelles). These micelles exhibited a high loading capacity of 70% (w/w) at a drug/polymer ratio of 0.5 at pH 7.0. They showed pH-responsive release patterns, with higher release at acidic pH than at physiological pH. Furthermore, DOX-loaded TBIC micelles exerted less cytotoxicity than free DOX in the A-549 human lung cancer cell line. Confocal microscopy in A-549 cells indicated that DOX-loaded TBIC micelles were transported into lysosomes via endocytosis. These micelles possessed favorable pharmacokinetic characteristics and showed sustained DOX release in rats. Overall, these findings indicate that PLD-b-PEG-b-PLD polypeptide micelles are a promising approach for anti-cancer drug delivery

MDR-1 gene expression is a minor factor in determining the multidrug resistance phenotype of MCF7/ADR and KB-V1 cells

AbstractThe relevance of MDR-1 gene expression to the multidrug resistance phenotype was investigated. Drug-resistant cells, KB-V1 and MCF7/ADR, constantly expressed mRNA of the MDR-1 gene and were more resistant to vinblastine and adriamycin than drug-sensitive cells, KB-3–1 and MCF7. The drug efflux rate of KB-V1 was the same as KB-3–1 although the MDR-1 gene was expressed in only the resistant cell. The higher intracellular drug concentration of KB-3–1 than KB-V1 was due to the large drug influx. In the case of MCF7 and MCF7/ADR, the influx and efflux of the drug had nearly the same pattern and drug efflux was not affected by verapamil. The amount of ATP, cofactor of drug pumping activity of P-glycoprotein, was not changed by the resistance. These observations suggested that drug efflux mediated by MDR-1 gene expression was not a major determining factor of drug resistance in the present cell systems, and that the drug resistance could be derived from the change in drug uptake and other mechanisms

MMP-Inhibitory Effects of Flavonoid Glycosides from Edible Medicinal Halophyte Limonium tetragonum

Limonium tetragonum has been well-known for its antioxidative properties as a halophyte. This study investigated the antimetastasis effect of solvent-partitioned L. tetragonum extracts (LTEs) and isolated compounds on HT1080 mouse melanoma cell model with a focus on matrix metalloproteinase (MMP) activity and TIMP and MAPK pathways. Upregulation and stimulation of MMPs result in elevated degradation of extracellular matrix which is part of several complications such as metastasis, cirrhosis, and arthritis. The anti-MMP capacity of LTEs was confirmed by their MMP-inhibitory effects, regulation of MMP and TIMP expression, and suppression of MAPK pathway. Among all tested LTEs, 85% aq. MeOH and n-BuOH were found to be most active fractions which later yielded two known flavonoid glycosides, myricetin 3-galactoside and quercetin 3-o-beta-galactopyranoside. Anti-MMP potential of the compounds was confirmed by their ability to regulate MMP expression through inhibited MAPK pathway activation. These results suggested that L. tetragonum might serve as a potential source of bioactive substances with effective anti-MMP properties

Generation and analysis of large-scale expressed sequence tags (ESTs) from a full-length enriched cDNA library of porcine backfat tissue

BACKGROUND: Genome research in farm animals will expand our basic knowledge of the genetic control of complex traits, and the results will be applied in the livestock industry to improve meat quality and productivity, as well as to reduce the incidence of disease. A combination of quantitative trait locus mapping and microarray analysis is a useful approach to reduce the overall effort needed to identify genes associated with quantitative traits of interest. RESULTS: We constructed a full-length enriched cDNA library from porcine backfat tissue. The estimated average size of the cDNA inserts was 1.7 kb, and the cDNA fullness ratio was 70%. In total, we deposited 16,110 high-quality sequences in the dbEST division of GenBank (accession numbers: DT319652-DT335761). For all the expressed sequence tags (ESTs), approximately 10.9 Mb of porcine sequence were generated with an average length of 674 bp per EST (range: 200–952 bp). Clustering and assembly of these ESTs resulted in a total of 5,008 unique sequences with 1,776 contigs (35.46%) and 3,232 singleton (65.54%) ESTs. From a total of 5,008 unique sequences, 3,154 (62.98%) were similar to other sequences, and 1,854 (37.02%) were identified as having no hit or low identity (<95%) and 60% coverage in The Institute for Genomic Research (TIGR) gene index of Sus scrofa. Gene ontology (GO) annotation of unique sequences showed that approximately 31.7, 32.3, and 30.8% were assigned molecular function, biological process, and cellular component GO terms, respectively. A total of 1,854 putative novel transcripts resulted after comparison and filtering with the TIGR SsGI; these included a large percentage of singletons (80.64%) and a small proportion of contigs (13.36%). CONCLUSION: The sequence data generated in this study will provide valuable information for studying expression profiles using EST-based microarrays and assist in the condensation of current pig TCs into clusters representing longer stretches of cDNA sequences. The isolation of genes expressed in backfat tissue is the first step toward a better understanding of backfat tissue on a genomic basis

Microstructural evolution induced by micro-cracking during fast lithiation of single-crystalline silicon

h i g h l i g h t s Lithiation of Si results in various microstructures depending of crystal orientation. A complex vein-like microstructure of Li x Si was observed in {100} oriented Si. Micro-cracks provide a fast path for Li diffusion and cause a non-uniform lithiation. Crystalline Li x Si plays an important role in micro-crack generation. a r t i c l e i n f o t r a c t We report observations of microstructural changes in {100} and {110} oriented silicon wafers during initial lithiation under relatively high current densities. Evolution of the microstructure during lithiation was found to depend on the crystallographic orientation of the silicon wafers. In {110} silicon wafers, the phase boundary between silicon and Li x Si remained flat and parallel to the surface. In contrast, lithiation of the {100} oriented substrate resulted in a complex vein-like microstructure of Li x Si in a crystalline silicon matrix. A simple calculation demonstrates that the formation of such structures is energetically unfavorable in the absence of defects due to the large hydrostatic stresses that develop. However, TEM observations revealed micro-cracks in the {100} silicon wafer, which can create fast diffusion paths for lithium and contribute to the formation of a complex vein-like Li x Si network. This defect-induced microstructure can significantly affect the subsequent delithiation and following cycles, resulting in degradation of the electrode

Heterogeneous distribution of Candida albicans cell-surface antigens demonstrated with an Als1-specific monoclonal antibody

Despite an abundance of data describing expression of genes in the Candida albicans ALS (agglutinin-like sequence) gene family, little is known about the production of Als proteins on individual cells, their spatial localization or stability. Als proteins are most commonly discussed with respect to function in adhesion of C. albicans to host and abiotic surfaces. Development of a mAb specific for Als1, one of the eight large glycoproteins encoded by the ALS family, provided the opportunity to detect Als1 during growth of yeast and hyphae, both in vitro and in vivo, and to demonstrate the utility of the mAb in blocking C. albicans adhesion to host cells. Although most C. albicans yeast cells in a saturated culture are Als1-negative by indirect immunofluorescence, Als1 is detected on the surface of nearly all cells shortly after transfer into fresh growth medium. Als1 covers the yeast cell surface, with the exception of bud scars. Daughters of the inoculum cells, and sometimes granddaughters, also have detectable Als1, but Als1 is not detectable on cells from subsequent generations. On germ tubes and hyphae, most Als1 is localized proximal to the mother yeast. Once deposited on yeasts or hyphae, Als1 persists long after the culture has reached saturation. Growth stage-dependent production of Als1, coupled with its persistence on the cell surface, results in a heterogeneous population of cells within a C. albicans culture. Anti-Als1 immunolabelling patterns vary depending on the source of the C. albicans cells, with obvious differences between cells recovered from culture and those from a murine model of disseminated candidiasis. Results from this work highlight the temporal parallels for ALS1 expression and Als1 production in yeasts and germ tubes, the specialized spatial localization and persistence of Als1 on the C. albicans cell surface, and the differences in Als1 localization that occur in vitro and in vivo