Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P30536 (PBS)
 9,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In 2 radioimmunoassays in use to detect antibodies to dsDNA, the Farr assay and the PEG assay, we observed inhibitory effects of normal human serum (NHS) on the DNA binding by SLE sera. This was found to be due by the fact that, during incubation at 37 degrees C, CO2, introduced in the incubation mixture by the serum, evaporates from the mixture. This results in increase in pH to values well above pH 8.0, which in turn leads to a decreased DNA binding by antibody. When SLE sera are tested at low dilution, this phenomenon may lead to false negative results. Proper pH control, by the use of buffers with a greater buffering capacity than PBS, completely prevented the observed inhibitory effects. However, under these conditions NHS bound significant amounts of DNA in both assays. The non-specific DNA binding by NHS was found to be heat-stable, but could be eliminated either by aerosil treatment of the sera or by addition of dextran sulphate to the incubation mixture. Lipoproteins and, to a lesser extent, the complement component C1q appear responsible for this non-specific binding. To avoid false negative results with SLE sera as well as non-specific binding by NHS, we propose the use of stronger buffers in combination with added dextran sulphate to the incubation mixture in both the Farr assay and the PEG assay.
 ...
PMID:Influence of pH on the detection of low- and high-avidity anti-dsDNA. 618 61

With the immunofluorescence technique (IFT) using Crithidia luciliae as a substrate, 14,417 sera sent to our laboratory for routine anti-dsDNA determination, were screened for the presence of antibodies to dsDNA. The 1,260 sera that were found IFT positive were then assayed with the Farr radioimmunoassay, in which 3H-labelled PM2-DNA is used as antigen. Only 470 sera (37%) were found to be Farr positive. This discrepancy is, at least partially, caused by the fact that the Farr assay does not detect anti-DNA of low avidity, whereas the Crithidia-IFT does. Sixty-eight percent of the IFT-positive/Farr negative sera were found positive with the PEG assay, a radioimmunoassay that also employs double stranded PM2-DNA as antigen, and that also detects anti-dsDNA of low avidity. The IFT performed on IFT positive/Farr negative sera was found to be rather irreproducible. It was shown that this was due to local increases of the salt concentration resulting from the way the assay was performed. The problem could be overcome by careful control of the assay conditions, i.e. never letting Crithidia slides dry up after washing with PBS. In the PEG assay, these sera sometimes showed a DNA binding that decreased with time. It could be shown that this is caused by a parallel increase in pH during the incubation as a result of CO2 evaporation from the serum.
 ...
PMID:Measurement of low avidity anti-dsDNA by the Crithidia luciliae test and the PEG assay. 675 23

The efficacy of tumor therapy using polyethylene-glycol-modified interleukin-2 (PEG-IL-2), alone or in combination with cyclophosphamide, was studied in advanced metastatic disease in the guinea pig. Line 10 (L10) tumor cells appeared in the axillary lymph node only 7 days after intradermal tumor-cell inoculation, and lymph-node leukocytes were almost completely replaced by tumor cells on day 28. Local treatment of the intradermally growing L10 hepatocarcinoma in the guinea pig with a relatively low dose of PEG-IL-2 resulted in regression of the primary tumor and prevention of lymph-node metastases. Therapy was completely curative (4 out of 5 animals) when started on day 7 or 14 after tumor-cell inoculation. When started on day 21, therapy was effective in only some (2 out of 5 cured) of the treated animals. Anti-tumor effects against the primary tumor and against lymph-node metastases were observed only after intratumoral (i.t.) administration of PEG-IL-2. Injection of the agent into or near lymph-node metastases in the absence of the primary tumor had no curative effect. In PBS/BSA-treated control animals the primary tumor and metastases grew progressively. In the treatment of far advanced metastatic disease, the combination of i.t. administration of PEG-IL-2 and i.p. injection of cyclophosphamide (Cy) resulted in improved anti-tumoral effects (5/5 guinea pigs were cured) when compared with monotherapy using either agent (one and none out of 5 animals cured, respectively). PBS/BSA heated controls showed progressive tumor-growth. We conclude that large primary tumors and lymph-node metastases can be treated effectively with PEG-IL-2. The i.t. route of administration is of major importance in the treatment of metastases, since administration of PEG-IL-2 near or into the lymph node had no therapeutic effect. Combination of PEG-IL-2 therapy with systemic injections of Cy significantly improved the curative effects of the treatment of advanced metastatic cancer.
 ...
PMID:PEG-IL-2 therapy of advanced cancer in the guinea pig. Impact of the primary tumor and beneficial effect of cyclophosphamide. 792 81

Polyrotaxanes were synthesized as novel biodegradable polymers with supramolecular assembly and their properties evaluated in vitro. The synthesis of biodegradable polyrotaxanes consists of three steps: preparation of an inclusion complex consisting of alpha-cyclodextrins (alpha-CDs) and amino-terminated poly(ethylene glycol) (PEG); introduction of L-phenylalanine (L-Phc) at each complex terminal via peptide linkages: and hydroxypropylation of alpha-CDs in the polyrotaxanes. Succinimide ester of benzyloxycarbonyl-L-Phe was condensed with the terminal amino groups of the inclusion complex. 1H-NMR and GPC results showed that alpha-CDs were threaded onto a PEG chain and L-Phe moieties were introduced at each terminal of the PEG chain. Further, the amount of threaded alpha-CDs was found to be governed by the molecular weight of PEG. The hydroxypropylation of alpha-CDs improved the solubility of the polyrotaxanes in PBS (pH 7.4). The hydroxypropylated (HP-) polyrotaxanes were characterized by terminal peptide cleavage using papain. In vitro degradation of HP-polyrotaxanes revealed that HP-alpha-CDs threaded onto a PEG chain were released only when terminal peptide linkages were cleaved. Moreover, threaded HP-alpha-CDs onto a PEG chain was found to be completely released. Kinetics of terminal peptide cleavage were also evaluated by catalytic efficiency (kcat/K(m)). The kcat/K(m) values were found to be independent of the molecular weight of HP-polyrotaxanes but to be affected by terminal hydrophobic moieties. It is proposed that our designed polyrotaxanes are feasible as novel drug carriers.
 ...
PMID:Synthesis and characterization of biodegradable polyrotaxane as a novel supramolecular-structured drug carrier. 915 Nov 92

The stabilities of two types of polymerically stabilized liposomes consisting of PEG-grafted (DSPC:CHOL:DSPE-PEG1900, 5:4:1) and physically adsorbed carboxymethylchitin (CMC) and carboxymethyl/glycolchitin (CO) are compared. The polyelectrolyte is adsorbed on positive (DSPC:CHOL:DMTAP, 5:4:1) and neutral (DSPC:CHOL, 1:1) liposomes at different molecular weights (Mw). In PBS buffer (c(s) = 154 mM, pH = 7.4) the theoretical stability ratios (W) calculated using the classical DLVO Theory, indicate that the CMC-coated vesicles and the negative liposomes (DSPC:CHOL:DMPG, 5:4:1) are highly stable (W >> 1) compared to the PEG-grafted (W = 0.9511) and CO-coated (W = 0.9550) liposomes. Meanwhile, experimentally determined values of W, prove that the PEG-grafted is the most stable suspension (W = 5.5). Computation of the theoretical values of W for liposome-red blood cell and liposome-macrophage indicates that the electrosterically stabilized suspensions and the negative liposomes are stable. Light scattering results show that the flocculation of liposomes in blood and plasma depends on polymer molecular weight, type of polyelectrolyte and surface charge of the uncoated liposome. Neutral liposomes coated with CMC of Mw = 1.01 x 10(5) and negative liposomes provide a more effective barrier to plasma macromolecular protein adsorption than the grafted PEG groups and are easy to resuspend in blood.
 ...
PMID:Comparison of polymerically stabilized PEG-grafted liposomes and physically adsorbed carboxymethylchitin and carboxymethyl/glycolchitin liposomes for biological applications. 972 Sep

Protein-loaded microparticles were produced from blends of poly(ethylene glycol) (PEG) with poly(L-lactide) (PLA) homopolymer or poly(DL-lactide co-glycolide) copolymers (PLG) using a water-in oil-in oil method. The stability of ovalbumin (OVA) associated with microparticles prepared using PEG and 50:50 PLG, 75:25 PLG and PLA, respectively, was analysed by SDS-PAGE and quantified by scanning densitometry following incubation in PBS at 37 degrees C for up to 1 month. Fragmentation and aggregation of OVA was detected with all 3 formulations. The extent of both processes correlated with the degradation rate of the lactide polymer used and decreased in the order PLA < 75:25 PLG < 50:50 PLG. Extensive degradation of the PLG/PEG microparticles also occurred over 4 weeks whereas the use of PLA/PEG blends resulted in a stable microparticle morphology and much reduced fragmentation and aggregation of the associated protein. Following a single sub-cutaneous immunisation, high levels of specific serum IgG antibody were elicited by OVA associated with the PLA/PEG particles. Injection of OVA associated with the 75:25 PLG/PEG microparticles resulted in very low levels of specific antibody. A higher response was induced by the 50:50 PLG/PEG formulation but there was very large inter-animal variation in this group. Antibody levels elicited by all 3 formulations were significantly higher than those elicited by a single injection of soluble OVA. Analysis of antigen specific IgG1 and IgG2a antibody subtype levels also revealed the greater efficacy of the PLA/PEG microparticles as an adjuvant system. The use of PLA/PEG microparticles shows improved protein loading and delivery capacity while maintaining a high level of stability of the associated protein. These results indicate a strong correlation between the stability of microencapsulated antigen and the magnitude of the immune response following sub-cutaneous immunisation.
 ...
PMID:The stability and immunogenicity of a protein antigen encapsulated in biodegradable microparticles based on blends of lactide polymers and polyethylene glycol. 1007 57

One of the possibilities for increasing the penetration rate of drugs through the skin is the use of vesicular systems. Currently, special attention is paid to the elastic properties of liquid-state vesicles, which are supposed to have superior properties compared to gel-state vesicles with respect to skin interactions. In this study, the effects of vesicles on hairless mouse skin, both in vivo and in vitro, were studied in relation to the composition of vesicles. The interactions of elastic vesicles containing the single chain surfactant octaoxyethylene laurate-ester (PEG-8-L) and sucrose laurate-ester (L-595) with hairless mouse skin were studied, in vivo, after non-occlusive application for 1, 3 and 6 h. The skin ultrastructure was examined by ruthenium tetroxide electron microscopy (TEM) and histology. The extent, to which vesicle constituents penetrated into the stratum corneum, was quantified by thin layer chromatography (TLC). The interactions of the elastic vesicles containing PEG-8-L and L-595 surfactants were compared with those observed after treatment with rigid vesicles containing the surfactant sucrose stearate-ester (Wasag-7). Furthermore, skin permeability experiments were carried out to investigate the effect of treatment with PEG-8-L micelles, elastic vesicles (containing PEG-8-L and L-595 surfactants) or rigid Wasag-7 vesicles on the 3H(2)O transport through hairless mouse skin, in vitro, after non-occlusive application. Treatment of hairless mouse skin with the elastic vesicles affected the ultrastructure of the stratum corneum: distinct regions with lamellar stacks derived from the vesicles were observed in intercellular spaces of the stratum corneum. These stacks disrupted the organization of skin bilayers leading to an increased skin permeability, whereas no changes in the ultrastructure of the underlying viable epidermis were observed. Treatment with rigid Wasag-7 vesicles did not affect the skin ultrastructure or skin permeability. TLC measurements showed that after 1 h of non-occlusive application of elastic or rigid vesicles, a six-fold increased amount of elastic vesicle material was present within the stratum corneum compared to rigid vesicle material. After 3 and 6 h of application the amount of PEG-8-L vesicle material in SC decreased to approximately three- and two-fold, respectively, compared to Wasag-7 vesicle material. Pretreatment of the hairless mouse skin with the elastic vesicles containing 70 mol% PEG-8-L increased the diffusion of 3H(2)O with an optimum application dose of 2.5 mg lipids/cm(2) compared to PBS pretreatment. No significant difference in the enhancement of the 3H(2)O-diffusion was observed between PEG-8-L micelles or elastic vesicles containing 30 or 70 mol% PEG-8-L. Pretreatment with the rigid Wasag-7 vesicles decreased the diffusion rate of 3H(2)O, most probably by the formation of a lipid layer on the skin surface. The effect of the elastic vesicles on the skin permeability is supported by the ultrastructural changes observed by TEM in the intercellular lipid domains. The elastic vesicles containing 70 mol% PEG-8-L disorganize the lipid bilayers thereby creating or modifying pathways for possible drug penetration.
 ...
PMID:Elasticity of vesicles affects hairless mouse skin structure and permeability. 1052 74

ABA-type block copolymers (abbreviated as LEL) composed of poly(L-leucine) (PLL) as the A component and poly(ethylene glycol) (PEG) as the B component were synthesized by ring-opening polymerization of L-leucine N-carboxyanhydride initiated by primary amino group located at both ends of PEG chain. A silver sulfadiazine (AgSD)-impregnated wound dressing of sponge type was prepared by the lyophilization method. Morphological structure of this wound dressing by scanning electron microscopy was observed to be composed of a dense skin layer and a porous inner layer. Equilibrium water content of LEL wound dressing increased with an increase in PEG content in the block copolymer due to the hydrophilicity of PEG. AgSD release from AgSD-impregnated wound dressing in PBS buffer (pH = 7.4) was dependent on PEG content in the block copolymer. Release of AgSD was increased in proportion to the PEG content in the copolymer. Antibacterial capacity of AgSD-impregnated wound dressing was examined in agar plate against Pseudomonas aeruginosa and Staphylococcus aureus. It was found that the suppression of bacterial proliferation in the wound dressing was dependent upon the PEG content. In cytotoxicity test, cell damage did not occur by the release of AgSD from the LEL sponge matrix of AgSD-medicated wound dressing. In in vivo test, granulous tissue formation and wound contraction for the AgSD- and dehydroepiandrosterone-impregnated LEL-2 wound dressing were faster than for any other groups.
 ...
PMID:Possibility of wound dressing using poly(L-leucine)/poly(ethylene glycol)/poly(L-leucine) triblock copolymer. 1063 95

One of the major problems raised by the microencapsulation of drugs which are sparingly soluble in water is the difficulty to achieve a controlled and total release of the drug. It was previously shown that the microencapsulation of a model water insoluble drug, namely 1-[2-(4-fluorobenzoyl)aminoethyl]-4-(7-methoxynaphthyl) piperazine hydrochloride (FAMP) with a hydrophilic additive like low molar mass poly(ethylene glycol)s (PEG) can fulfil these requirements, provided all the drug + additive matter is in contact with the surrounding liquid medium via open pores and percolating channels. In this paper, PEG was replaced by other additives, selected because of their potential ability to increase the solubility of FAMP in pH = 7.4 isosomolar phosphate buffer (PBS). The idea was that increasing the solubility locally in microparticles could allow the drug to be released, despite its poor solubility in aqueous media like body fluids, and be absorbed before recrystallization. The solubility in PBS of FAMP mixed with additive, in the form of solid dispersions, was determined for various additives, namely citric acid, dimyristoyl DL-alpha-phosphatidyl choline (DMPC), poloxamer copolymers of different compositions and poly(dodecyl L-lysine citramidate) (PLCAC12(100)), an aggregate-forming hydrophilic polyelectrolyte containing 100%, hydrophobizing ester groups which can accommodate lipophilic compounds in hydrophobic pockets present in the aggregates. PEG was taken as a reference. It was found that DMPC, some poloxamers and the hydrophobized polyelectrolyte do increase the solubility of FAMP in PBS. Investigation was made of the release of FAMP from ground microparticles, whose loads were composed of FAMP combined with these solubilization-promoting additives. It was found that the release rate of FAMP from such systems can be increased and modulated to achieve an in vitro sustained release over a 20-30 day period and secure exhaustion of the particles at the end of this period.
 ...
PMID:The use of additives to modulate the release of a sparingly water soluble drug entrapped in PLA50 microparticles. 1067 Sep 42

The entrapment of lysozyme in amphiphilic multiblock copolymer microspheres by emulsification and subsequent solvent removal processes was studied. The copolymers are composed of hydrophilic poly(ethylene glycol) (PEG) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks. Direct solvent extraction from a water-in-oil (w/o) emulsion in ethanol or methanol did not result in the formation of microspheres, due to massive polymer precipitation caused by rapid solvent extraction in these non-solvents. In a second process, microspheres were first prepared by a water-in-oil-in-water (w/o/w) emulsion system with 4% poly(vinyl alcohol) (PVA) as stabilizer in the external phase, followed by extraction of the remaining solvent. As non-solvents ethanol, methanol and mixtures of methanol and water were employed. However, the use of alcohols in the extraction medium resulted in microspheres which gave an incomplete lysozyme release at a non-constant rate. Complete lysozyme release was obtained from microspheres prepared by an emulsification-solvent evaporation method in PBS containing poly(vinyl pyrrolidone) (PVP) or PVA as stabilizer. PVA was most effective in stabilizing the w/o/w emulsion. Perfectly spherical microspheres were produced, with high protein entrapment efficiencies. These microspheres released lysozyme at an almost constant rate for approximately 28 days. The reproducibility of the w/o/w emulsion process was demonstrated by comparing particle characteristics and release profiles of three batches, prepared under similar conditions.
 ...
PMID:Microspheres for protein delivery prepared from amphiphilic multiblock copolymers. 1. Influence of preparation techniques on particle characteristics and protein delivery. 1082 57


1 2 3 4 5 6 7 8 9 10 Next >>