Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Beads

  • agarose bead
  • alginate bead
  • fluorescent bead
  • gel bead
  • glass bead
  • hydrogel bead
  • latex bead
  • magnetic bead
  • polymer bead
  • polystyrene bead
  • resin bead
  • silica bead
  • spherical bead
  • spherical glass bead
  • tio2 bead

  • Terms modified by Beads

  • bead array
  • bead array technology
  • bead size
  • bead surface

  • Selected Abstracts

    Generation of a scaffold free cartilage-like implant from a small amount of starting material

    M. J. Stoddart
    Abstract Introduction: An autologous cellular based treatment of a traumatic cartilage injury requires a procedure whereby a biopsy of healthy cartilage is removed from the patient and the cells isolated and expanded by monolayer passage. This increases the cell number to required levels but also leads to a de-differentiation of the cells. We aim to produce a scaffold-free, de-novo implant from a biopsy of cartilage. Methods: Bovine chondrocytes were isolated from a small biopsy and expanded. The chondrocytic phenotype of the monolayer expanded cells was recovered during a period of culture in alginate and the effect of factors such as IGF1, TFG,1 and dexamethasone was investigated. Results: During the alginate culture period a pre-treatment with IGF1 and dexamethasone was shown to have little effect. IGF1 however increased the glycosaminoglycan/DNA (GAG/DNA) content on day 14 to 84.95±5ng/ng compared with 37.3±1.8ng/ng in the controls (P <0.001). 35S labeling demonstrated an increased GAG synthesis in the presence of IGF1 (P < 0.001). IGF1 also induced a increase of DNA content 1383±314ng/bead compared to 512±19ng/bead in the controls (P < 0.001). The cells were released from the alginate and cultured in a silicon mould for a further 14 days to obtain a three dimensional implant. Releasing the cells from the alginate and casting in a mould produced an implant of defined shape which contained no foreign material. After 31 days of culture the implants contained 152.4±13.14ng/ng GAG/DNA and 42.93±10.23ng/ng collagen II. Discussion: We believe alginate released chondrocytes provide a real alternative to artificial scaffolds. [source]


    ARCHAEOMETRY, Issue 3 2010
    This paper reports the results of elemental analysis, using laser ablation , inductively coupled plasma , mass spectrometry (LA,ICP,MS), of 30 glass beads from an assemblage of beads excavated at medieval al-Basra, Morocco. Six chemical glass types are represented and their characteristics and geographical origins are discussed, with reference also to the techniques used to make the beads. The presence of numerous beads of lead,silica glasses is of particular interest. The morphological, technological and chemical analyses of the bead assemblage shed light on al-Basra's trade connections. [source]


    ARCHAEOMETRY, Issue 6 2009
    The Pichvnari necropolis on the Black Sea coast of Georgia lies in an area known in the late first millennium as ,Colchis', on part of the trade route leading to the Orient. The burials of the necropolis date to the late fifth century bc and frequently contain grave goods, including extremely well-preserved polychrome glass beads and core-formed vessels. This paper presents a study of these vessels both stylistically and archaeologically and using SEM,WDS and LA,ICPMS. It reveals that the vessels have compositional differences that may point to multiple manufacturing sites. One of the vessels appears stylistically unique and may exhibit one of the earliest uses of manganese as a decolorizer. Major and minor element data for the vessels suggest that they may belong to the same ,Levantine' group as many Roman glass objects, suggesting that a source of sand on the coast of the Levant could have been used in their production. The beads clearly show glass with both natron- and plant ash-based flux with distinct rare earth compositions, showing multiple sites of production, some of which were probably either in the Middle East or the Indian subcontinent. [source]

    Staphylococcus aureus enterotoxin B augments granulocyte migration and survival via airway epithelial cell activation

    ALLERGY, Issue 8 2010
    W. Huvenne
    To cite this article: Huvenne W, Callebaut I, Reekmans K, Hens G, Bobic S, Jorissen M, Bullens DMA, Ceuppens JL, Bachert C, Hellings PW. Staphylococcus aureus enterotoxin B augments granulocyte migration and survival via airway epithelial cell activation. Allergy 2010; 65: 1013,1020. Abstract Background:,Staphylococcus aureus enterotoxin B (SEB) has recently been postulated to be involved in the pathology of granulocyte-dominated disease. Studying the immunologic interaction between SEB and airway epithelial cells in immortalized cell lines or long-term epithelial cell cultures has obvious disadvantages. Methods:, We used a novel technique of freshly isolated and purified human nasal epithelial cells (HNEC) from healthy, nonallergic individuals, which were incubated for 24 h without/with SEB at different concentrations. Chemokine production was evaluated in the supernatant using Cytometric Bead Array. The chemotactic activity of the supernatant was studied in vitro using a Boyden chamber. Survival was evaluated with flow cytometry, using propidium iodide to identify dead cells. Results:,Staphylococcus aureus enterotoxin B showed a dose-dependent induction of interferon-inducible protein-10, monokine induced by interferon-,, regulated upon activation normal T cell expressed and secreted, monocyte chemoattractant protein 1 (MCP-1) and granulocyte colony stimulating factor production by epithelial cells in vitro. The supernatant of epithelial cells had chemotactic activity for granulocytes in vitro, which was enhanced in the supernatant of SEB-stimulated epithelial cells. Reduced number of propidium iodide positive granulocytes was found in the conditions where supernatant of SEB-stimulated epithelial cells was applied. Conclusion:,Staphylococcus aureus enterotoxin B exerts a direct pro-inflammatory effect on HNEC, with induction of chemokine and growth factor release, resulting in the migration and prolonged survival of granulocytes in vitro. [source]

    Heterogeneous modes of uptake for latex beads revealed through live cell imaging of phagocytes expressing a probe for phosphatidylinositol-(3,4,5)-trisphosphate and phosphatidylinositol-(3,4)-bisphosphate

    CYTOSKELETON, Issue 9 2008
    Jennifer Giorgione
    Abstract Latex beads are the preferred phagocytic substrate in biochemical studies of phagosome composition and maturation. Using living Dictyostelium cells and fluorescent probes, we compared the properties of phagosomes formed to ingest latex beads or digestible prey. Significant differences were found during the initial steps of phagocytosis. During uptake of bacteria or yeast, PHcrac-GFP, a probe that binds to membranes enriched in PI(3,4,5)P3 and PI(3,4)P2, always labeled the nascent phagosome and faded shortly after it sealed. However, labeling of bead-containing phagosomes was highly variable. Beads were engulfed by phagosomes either lacking or displaying the PHcrac-GFP label, and that label, if present, often persisted for many minutes, revealing that early trafficking steps for bead-containing phagosomes are quite heterogeneous. Later stages of the endocytic pathway appeared more similar for phagosomes containing prey and latex beads. Both types of phagosomes fused with acidic endosomes while undergoing transport along microtubules, both acquired the V-ATPase and lost it prior to exocytosis, and both bound the late endosome marker vacuolin B, which was transferred to the plasma membrane upon exocytosis. We conclude that caution is needed in extrapolating results from latex bead phagosomes to phagosomes containing physiological substances, especially in early stages of the endocytic pathway. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source]

    Synthesis of 3,-BODIPY-Labeled Active Esters of Nucleotides and a Chemical Primer Extension Assay on Beads

    Kerstin Gießler
    Abstract A solution-phase synthesis of active esters of 3,-fluorophore-labeled deoxynucleoside 5,-monophosphates was developed for thymine and cytosine as nucleobases by using two different BODIPY dyes. Starting from the respective 2,-amino-2,,3,-dideoxynucleoside-5,-monophosphate, the fluorescent oxyazabenzotriazolides can be prepared in one-pot procedures involving labeling and activation. Screening of a range of supports led to a chemical primer extension assay on beads with in situ detection of nucleobases in target DNA through optical read-out. [source]

    Synthesis, Characterization and Drug Release Behavior of pH-Responsive O-carboxymethyl Chitosan-graft-poly(N-vinylpyrrolidone) Hydrogel Beads,

    Liwei Ma
    In this work, the carboxymethyl chitosan (CMCTS) grafted poly(N-vinylpyrrolidone) (PVP) copolymers were synthesized. The hydrogel beads containing VB2 were prepared from the copolymers by an ionic crosslinked. The experimental results shown that VB2 drug release rate from those beads decreased with the increasing grafting percentage, crosslinker concentration and pH value of the medium. Besides, the beads have the better control ability for releasing of model drug than CMCTS does. [source]

    Dual-Function Scattering Layer of Submicrometer-Sized Mesoporous TiO2 Beads for High-Efficiency Dye-Sensitized Solar Cells

    Fuzhi Huang
    Abstract Submicrometer-sized (830,±,40,nm) mesoporous TiO2 beads are used to form a scattering layer on top of a transparent, 6-µm-thick, nanocrystalline TiO2 film. According to the Mie theory, the large beads scatter light in the region of 600,800,nm. In addition, the mesoporous structure offers a high surface area, 89.1,m2 g,1, which allows high dye loading. The dual functions of light scattering and electrode participation make the mesoporous TiO2 beads superior candidates for the scattering layer in dye-sensitized solar cells. A high efficiency of 8.84% was achieved with the mesoporous beads as a scattering layer, compared with an efficiency of 7.87% for the electrode with the scattering layer of 400-nm TiO2 of similar thickness. [source]

    Nanoaggregate-Embedded Beads as Novel Raman Labels for Biodetection

    Ping-Ji Huang
    Abstract Novel Raman tags called nanoaggregate-embedded beads (NAEBs) have been developed. NAEBs are silica-coated, dye-induced aggregates of a small number of metal nanoparticles. In this work, the Raman reporters used to induce aggregation of gold nanoparticles include strongly binding dyes such as XRITC, TRITC, and DTDC and weakly binding dyes such as R6G. Surface-enhanced Raman scattering (SERS) signal from a single NAEB can be detected. This study also demonstrates that these SERS-active beads can be used as Raman tags for bio-detection. [source]

    Mesoporous Anatase TiO2 Beads with High Surface Areas and Controllable Pore Sizes: A Superior Candidate for High-Performance Dye-Sensitized Solar Cells

    ADVANCED MATERIALS, Issue 21 2009
    Dehong Chen
    Mesoporous anatase TiO2 beads with high surface areas and controllable pore sizes are prepared by using a combined sol,gel and solvothermal process. Dye-sensitized solar cells made from these mesoporous beads gave a total power conversion efficiency of 7.20% under AM 1.5 sunlight, higher than that obtained using Degussa P25 films of similar thickness (5.66%). [source]

    Encoded Porous Beads for Label-Free Multiplex Detection of Tumor Markers

    ADVANCED MATERIALS, Issue 5 2009
    Yuanjin Zhao
    Inverse-opaline photonic beads are used as the elements of a suspension array for label-free multiplex immunoassays. As in the case of tumor-marker detection, specific binding of tumor markers on the pore surfaces of the beads results in a shift in the diffraction-peak position, which can be used for quantitatively estimating the amount of bound tumor marker. [source]

    Interactions between FGF and Wnt signals and Tbx3 gene expression in mammary gland initiation in mouse embryos

    JOURNAL OF ANATOMY, Issue 1 2004
    Maxwell C. Eblaghie
    Abstract Interactions between Wnts, Fgfs and Tbx genes are involved in limb initiation and the same gene families have been implicated in mammary gland development. Here we explore how these genes act together in mammary gland initiation. We compared expression of Tbx3, the gene associated with the human condition ulnar,mammary syndrome, expression of the gene encoding the dual-specificity MAPK phosphatase Pyst1/MKP3, which is an early response to FGFR1 signalling (as judged by sensitivity to the SU5402 inhibitor), and expression of Lef1, encoding a transcription factor mediating Wnt signalling and the earliest gene so far known to be expressed in mammary gland development. We found that Tbx3 is expressed earlier than Lef1 and that Pyst1 is also expressed early but only transiently. Patterns of expression of Tbx3, Pyst1 and Lef1 in different glands suggest that the order of mammary gland initiation is 3, 4, 1, 2 and 5. Consistent with expression of Pyst1 in the mammary gland, we detected expression of Fgfr1b, Fgf8 and Fgf9 in both surface ectoderm and mammary bud epithelium, and Fgf4 and Fgf17 in mammary bud epithelium. Beads soaked in FGF-8 applied to the flank of mouse embryos, at a stage just prior to mammary bud initiation, induce expression of Pyst1 and Lef1 and maintain Tbx3 expression in flank tissue surrounding the bead. Grafting beads soaked in the FGFR1 inhibitor, SU5402, abolishes Tbx3, Pyst1 and Lef1 expression, supporting the idea that FGFR1 signalling is required for early mammary gland initiation. We also showed that blocking Wnt signalling abolishes Tbx3 expression but not Pyst1 expression. These data, taken together with previous findings, suggest a model in which Tbx3 expression is induced and maintained in early gland initiation by both Wnt and Fgf signalling through FGFR1. [source]

    Release behavior of freeze-dried alginate beads containing poly(N -isopropylacrylamide) copolymers

    Jae-Hyung Choi
    Abstract Beads composed of alginate, poly(N -isopropylacrylamide) (PNIPAM), the copolymers of N -isopropylacrylamide and methacrylic acid (P(NIPAM- co -MAA)), and the copolymers of N -isopropylacrylamide, methacrylic acid, and octadecyl acrylate (P(NIPAM- co -MAA- co -ODA)), were prepared by dropping the polymer solutions into CaCl2 solution. The beads were freeze-dried and the release of blue dextran entrapped in the beads was observed in distilled water with time and pH. The degree of release was in the order of alginate bead < alginate/PNIPAM bead , alginate/P(NIPAM- co -MAA) bead < alginate/P(NIPAM- co -MAA- co -ODA) bead. On the other hand, swelling ratios reached steady state within 20 min, and the values were 200,800 depending on the bead composition. The degree of swelling showed the same order as that of release. Among the beads, only alginate/P(NIPAM- co -MAA- co -ODA) bead exhibited pH-dependent release. At acidic condition, inter- and intraelectrostatic repulsion is weak and P(NIPAM- co -MAA- co -ODA) could readily be assembled into an aggregate due to the prevailing hydrophobic interaction of ODA. Thus, it could block the pore of bead matrix, leading to a suppressed release. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Mass-transfer effects during separation of proteins in SMB by size exclusion

    AICHE JOURNAL, Issue 5 2003
    Joukje Houwing
    The chromatographic fractionation of proteins by size-exclusion chromatography in a simulated moving bed (SMB) is studied. During experimental fractionation of a mixture of bovine serum albumin (BSA) and myoglobin on Sepharose Big Beads, mass-transfer effects are shown to limit the performance of the SMB. The internal profiles, as well as the extract and raffinate compositions, are described well by a steady-state equivalent true moving-bed (TMB) model that incorporates mass-transfer effects. The selection of the particle size in SMB is a trade-off between productivity and mass transfer. Based on the equivalent TMB model, the optimum particle size and configuration of the SMB can be selected, at which preset performance criteria (purity, recovery) are met at specified flow-rate ratios, total column length, and pressure drop. For the current feed and apparatus, an optimal particle size of approximately 145 ,m is calculated for achievement of purities and overall recoveries of 95%. [source]

    Colonic delivery of ,-lactamases does not affect amoxicillin pharmacokinetics in rats

    Sandrine Bourgeois
    Abstract Pectin beads containing ,-lactamases were designed for the hydrolysis of colonic residual antibiotics responsible for the emergence of resistance. Beads were prepared by ionotropic gelation in CaCl2 and stabilized by coating with polyethylenimine (PEI) to resist disintegration in the upper GI tract. Particle characterization showed that dried beads had a diameter around 1 mm independently of the presence of PEI. Seven to ten percent (w/w) of PEI was located on bead surface forming a coating layer as observed by scanning electron microscopy. PEI improved considerably bead stability in simulated intestinal medium while affecting slightly the encapsulation efficiency of active ,-lactamases. Coated beads were able to preserve ,-lactamases from premature leakage in the upper GIT whereas, in simulated colonic medium, pectinases induced matrix degradation and reduction of ,-lactamase content especially in beads coated in a 0.8% PEI solution. Finally, the pharmacokinetics of amoxicillin in rat after oral administration was not modified by the co-administration of beads containing ,-lactamases. In conclusion, PEI-coated beads are stable in the upper GIT but remain sensitive to the action of pectinolytic enzymes allowing release of ,-lactamases in a colonic medium without modification of the absorption of a ,-lactam antibiotic when co-administered with loaded beads. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 1853,1863, 2008 [source]

    Physicochemical characterization of papain entrapped in ionotropically cross-linked kappa-carrageenan gel beads for stability improvement using Doehlert shell design

    Mayur G. Sankalia
    Abstract This work examines the influence of various process parameters on papain entrapped in cross-linked ,-carrageenan beads for improvement of its stability. A Doehlert shell design (DSD) was employed to investigate the effect of three process variables, namely ,-carrageenan concentration, KCl concentration, and hardening time, on the entrapment, time required for 50% enzyme release (T50), time required for 90% enzyme release (T90), and particle size. The beads were prepared by dropping the ,-carrageenan containing papain into a magnetically stirred KCl solution. Topographical characterization was carried out by scanning electron microscopy and entrapment was confirmed by Fourier transform infrared spectroscopy and differential scanning calorimetry. Stability testing was carried out according to the International Conference on Harmonization (ICH) guidelines for zone III and IV. A polymeric matrix was prepared with ,-carrageenan (3.5% w/v) and potassium chloride (0.5 M) using the ionotropic gelation method, with a hardening time of 20 min. Beads characterized by a spherical disc shape with a collapsed center, an absence of aggregates, an entrapment of 82.75%, a T90 value of 55.36 min, and a composite index of 88.55 were produced. The shelf-life of the enzyme-loaded beads was found to increase to 3.63 years compared with 1.01 years for the conventional formulation. It can be inferred that the proposed methodology can be used to prepare papain-loaded ,-carrageenan beads for stability improvement. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95: 1994,2013, 2006 [source]

    Development and Applications of Topologically Segregated Bilayer Beads in One-bead One-compound Combinatorial Libraries

    Ruiwu Liu
    Abstract Using a "split,mix" synthesis approach, "One-Bead One-Compound" (OBOC) combinatorial libraries can be generated such that each bead displays only one chemical entity. Tens of thousands to millions of compound-beads can be screened concurrently using a variety of biochemical and cell-based screening methods. Positive beads are then physically isolated for structure determination. Peptide beads or peptoid beads consisting of ,-amino acids and with a free N -terminus can be routinely sequenced by an automatic microsequencer using Edman chemistry. Libraries with N -terminally blocked peptides, peptides with unsequenceable building blocks, or small molecules require encoding. To fully exploit the OBOC combinatorial library methods, we have developed topologically segregated bilayer beads. Such bilayer beads allow us to prepare library compound on the outer layer of each bead and the coding tags in the bead interior. In addition, we can use these bilayer beads to prepare OBOC combinatorial libraries that are down-substituted on the bead surface but fully substituted in the bead interior. This configuration enables one to screen at a much higher stringency and yet have enough peptides or coding tags retained in the bead interior for structure determination. [source]

    Promising Diagnostic Biomarkers for Primary Biliary Cirrhosis Identified With Magnetic Beads and MALDI-TOF-MS

    Yong-Zhe Li
    Abstract (PBC) is not a rare disease worldwide. Most patients are diagnosed at the advanced stage, primarily because there are not yet any valid biomarkers available for early diagnosis. Useful biomarkers are absolutely necessary for early detection of PBC. Fortunately, the use of MALDI-TOF-MS and pattern recognition software has been successful in finding specific markers for the early detection of the disease. To screen for potential protein biomarkers in the serum for diagnosing PBC, MALDI-TOF-MS combined with magnetic beads and pattern recognition software was used to investigate 119 serum samples from 44 patients with PBC, 32 controls with other hepatic disease, and 43 healthy controls. A total of 69 discriminant m/z peaks were identified as being associated with PBC. Of them, the m/z peaks at 3445, 4260, 8133, and 16,290 were used to construct a model for the diagnosis of PBC. This diagnostic model can distinguish PBC from non-PBC controls with a sensitivity of 93.3% and a specificity of 95.1%. In our blind test, it demonstrated good sensitivity and specificity: 92.9% and 82.4%, respectively. These results indicate that useful serum biomarkers for PBC can be discovered by MALDI-TOF-MS combined with the use of magnetic beads and pattern recognition software. The pattern of multiple markers provides a powerful and reliable diagnostic method for PBC with high sensitivity and specificity. Anat Rec, 292:455,460, 2009. © 2009 Wiley-Liss, Inc. [source]

    Use of microbeads for the detection of binding sites on the human zona pellucida: a scanning electron microscopy (SEM) assay

    ANDROLOGIA, Issue 5 2001
    Prof. Dr H. W. Michelmann
    Summary One prerequisite for fertilization is the specific binding of spermatozoa to the zona pellucida. However, the factors and mechanisms involved in this gamete contact are not well understood. Gamete recognition and binding are species-specific and are controlled by oligosaccharides of the zona and their corresponding carbohydrates on the spermatozoon. By using a specific lectin we developed a technique to detect those oligosaccharides on the human zona pellucida that might be involved in the binding process. Microbeads (Ø = 2.8 ,m), used as artificial spermatozoa, were coated with lectin Con A and cultured together with 75 unfertilized oocytes (group A) remaining after intracytoplasmic sperm injection. Con A binds specifically to ,-D-mannose and ,-D-glucose. As a control, 75 unfertilized oocytes after intracytoplasmic sperm injection (group B) were also cultured together with Con A-covered microbeads, but in a medium containing a binding inhibiting sugar (,-methyl-mannopyrasosid). The number and distribution of the microbeads on human oocytes of both groups were analysed on scanning electron microscopy images. Beads on oocytes of group A had binding patterns similar to those of spermatozoa. They were distributed in an extremely heterogeneous way with various numbers of bound beads both on individual and different oocytes. Most of the group A oocytes (85%) had more than 50 beads bound to the zona, in contrast to the control oocytes of group B, where 68% had less than 10 bound beads. The use of an inhibiting sugar abolished the binding capacity of the microbeads nearly completely. This technique is a powerful tool for the detection of binding sites on the zona pellucida, i.e. those sugars that are responsible for contact between spermatozoa and the zona pellucida. [source]

    Microparticle Matrix Encoding of Beads,

    ANGEWANDTE CHEMIE, Issue 20 2010
    Morten Meldal Prof.
    Die optische Kodierung von Harzen auf Polyethylenglycol(PEG)-Basis ermöglicht eine direkte Identifizierung von Verbindungen in kombinatorischen Bibliotheken und eine Korrelation zwischen Struktur und biologischer Aktivität. Diese Mikropartikelmatrix(MPM)-Kodierung (siehe Bild) vermeidet einige Probleme, die häufig bei der kombinatorischen Chemie an der Festphase auftreten, und lässt sich zudem leicht einbauen. [source]

    Hollow Microtubes and Shells from Reactant-Loaded Polymer Beads,

    ANGEWANDTE CHEMIE, Issue 46 2009
    Rabih Makki
    Mit eigenem Antrieb: Wenn man mit Salzlösungen befüllte Agarose-Mikrokügelchen in eine Natriumsilicatlösung einbringt, so entstehen Röhren, die an einer anorganischen Schale anhaften (siehe Bild). Diese Röhren haben Innenradien von 3,,m aufwärts, können 0.5,mm lang werden und wachsen mit Geschwindigkeiten bis 50,,m,s,1. An Blasen hängende Röhren können eine gerichtete Bewegung der Kügelchen induzieren. [source]

    15 Bitumen, Blades, and Beads: Prehispanic Craft Production and the Domestic Economy

    Elizabeth M. Brumfiel
    First page of article [source]

    Intraportal Transplantation of Allogenic Pancreatic Islets Encapsulated in Barium Alginate Beads in Diabetic Rats

    ARTIFICIAL ORGANS, Issue 11 2003
    Stephan Schneider
    Abstract:, The survival of microencapsulated islets transplanted into the unmodified peritoneal cavity is limited, even if capsular overgrowth is restricted to a minimum, due to an insufficient oxygen supply to the islets. Therefore, research efforts should focus on finding or creating a transplantation site, which permits a closer contact between the encapsulated islets and the blood. For this reason, the liver could be an interesting candidate. The aim of the present study was to test the hypothesis that the intraportal transplantation of allogenic islets encapsulated in small-sized barium alginate beads is safe and succeeds to induce normoglycemia in diabetic rats. The intraportal transplantation of 1,500 islets encapsulated in barium alginate beads leads within 10 h and up to 24 h to blood sugar concentrations below 40 mg/dL, most likely due to an acute cell lysis of the graft. Afterwards, the reappearance of the diabetic state could be detected in these animals. Most likely these findings are induced by a sudden hypoxia to the islets. We believe that the occlusion of small- and medium-sized portal venules by the alginate beads is responsible for this effect. Therefore, in forthcoming studies, barium alginate beads, with a diameter below 350 µm, stabilized with medical approved additives should be used. [source]

    Sustained High-Yield Production of Recombinant Proteins in Transiently Transfected COS-7 Cells Grown on Trimethylamine-Coated (Hillex) Microcarrier Beads

    Randall N. Knibbs
    The present study shows that COS-7 cells transiently transfected and maintained on positively charged (trimethylamine-coated) microcarrier beads synthesize recombinant protein at higher levels and for longer periods of time than cells transfected and maintained on polystyrene flasks in monolayer culture. Sustained, high-level synthesis was observed with secreted chimeric proteins (murine E-selectin, and P-selectin-human IgM chimeras) and a secreted hematopoietic growth factor (granulocyte-macrophage colony-stimulating factor). Studies with green fluorescent protein indicated that the transfected cells attached more firmly to the trimethylamine-coated microcarriers than to polystyrene flasks. After 10,14 days in culture, most of the transfected cells detached from the surface of the polystyrene flasks, whereas most transfected cells remained attached to the microcarriers. The transiently transfected microcarrier cultures produced higher levels of protein per transfected cell due to this prolonged attachment. The prolonged attachment and higher output of transfected cells on microcarriers resulted in a 5-fold increase in protein production from a single transfection over two weeks. Thus, microcarrier-based transient transfection yields quantities of recombinant proteins with a significant savings of time and reagents over monolayer culture. [source]

    Swelling Induced Detachment of Chondrocytes Using RGD-Modified Poly(N -isopropylacrylamide) Hydrogel Beads

    Mee Ryang Kim
    Thermally sensitive poly( N -isopropylacrylamide, NIPAAm) hydrogel beads conjugated with a cell adhesive motif, GRGDY, were prepared and utilized as cell culture substrate for chondrocytes. They were produced to be uniform in size and distribution by using calcium alginate as a temporal mold. The RGD moieties were introduced, in a spatially selective manner, to the surface of the beads by conjugating GRGDY under the precollapsed state at a higher temperature above the lower critical solution temperature (LCST). These RGD-conjugated polyNIPAAm beads demonstrated a reversible swelling and deswelling behavior around the LCST, which enabled the chondrocytes attached on the surface of collapsed beads at 37 °C to readily detach when the temperature was shifted below 37 °C. The cell detachment percentage was largely affected by the temperature-dependent reswelling extent of the collapsed RGD-modified beads. [source]

    Immobilized Metal Affinity Chromatography without Chelating Ligands: Purification of Soybean Trypsin Inhibitor on Zinc Alginate Beads

    Munishwar N. Gupta
    Immobilized metal affinity chromatography (IMAC) is a widely used technique for bioseparation of proteins in general and recombinant proteins with polyhistidine fusion tags in particular. An expensive and critical step in this process is coupling of a chelating ligand to the chromatographic matrix. This chelating ligand coordinates metal ions such as Cu2+, Zn2+, and Ni2+, which in turn bind proteins. The toxicity of chemicals required for coupling and their slow release during the separation process are of considerable concern. This is an important issue in the context of purification of proteins/enzymes which are used in food processing or pharmaceutical purposes. In this work, a simpler IMAC design is described which should lead to a paradigm shift in the application of IMAC in separation. It is shown that zinc alginate beads (formed by chelating alginate with Zn2+ directly) can be used for IMAC. As "proof of concept", soybean trypsin inhibitor was purified 18-fold from its crude extract with 90% recovery of biological activity. The dynamic binding capacity of the packed bed was 3919 U mL -1, as determined by frontal analysis. The media could be regenerated with 8 M urea and reused five times without any appreciable loss in its binding capacity. [source]

    Dynamic Multivalent Lactosides Displayed on Cyclodextrin Beads Dangling from Polymer Strings.

    CHEMINFORM, Issue 4 2004
    Alshakim Nelson
    No abstract is available for this article. [source]

    Single-Domain Antibody-Conjugated Nanoaggregate-Embedded Beads for Targeted Detection of Pathogenic Bacteria

    Ping-Ji Huang
    Cells aglow: Nanoaggregate-embedded beads (NAEBs) linked to a pathogen-specific single-domain antibody (sdAb) are used as an ultra-bright surface-enhanced Raman scattering (SERS) tag for detection of Staphylococcus aureus bacteria by SERS microscopy. The image shows a single S. aureus cell labeled with NAEBs and its corresponding NAEB,SERS spectrum. [source]

    A Method for the Rapid Discovery of Naturally Occurring Products by Proteins Immobilized on Magnetic Beads and Reverse Affinity Chromatography

    Abstract A highly efficient screening method for naturally occurring products that bind to a specific target protein was demonstrated by using hVDR magnetic beads. The native ligand 1,,25(OH)2 VD3 (1) was selectively bound by hVDR magnetic beads when present in a mixture of natural compounds. Furthermore, this method was shown to be applicable to the identification of natural products that interact with a specific protein immobilized on the beads from an extract of a natural resource. Two new natural compounds were isolated by this method. This approach will be helpful for the discovery of novel, naturally occurring products that bind to specific target proteins. This method has the further advantages that it can identify the HPLC peak corresponding to the target compound for isolation, as well as provide important UV, CD, or MS profile information. [source]

    Nanopatterning of Biomolecules with Microscale Beads

    CHEMPHYSCHEM, Issue 5 2005
    Patrick Pammer
    Nanopatterning of biomolecules: Arrays of microscale beads can be used as stamps to print biomolecules onto a flat substrate. The simple surface-structuring method produces regular patterns of nanoscale DNA and protein spots with a diameter of 300 nm separated by an interspot distance of several micrometers (see figure). [source]