Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:003721 (Poly)
 11,742 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly(L-glutamic acid) (PGA) suppresses the polymerization of porcine brain microtubule proteins and induces the depolymerization in vitro in a concentration-dependent manner. The extent of inhibition increases with increasing molecular weight of the PGA tested. A 50% inhibition of the protein polymerization was observed at a PGA (molecular weight = 60,000) to microtubule protein ratio of 0.04 (w/w), and complete inhibition was obtained at a ratio of 0.07. Such an inhibition on the polymerization by PGA is greatly decreased when Mg2+ is present at a higher concentration. The addition of PGA raises the critical concentration of microtubule proteins necessary for assembly. During incubation with PGA, microtubule proteins retain the ability to assemble, i.e., substoichiometric amounts of taxol considerably relieve the inhibition of assembly by PGA. PGA interacts with microtubule-associated proteins (MAPs) preferentially, because the amount of MAPs binding to PGA-Sepharose 4B is much larger than that of tubulin. Tau proteins were observed only in adsorbed fractions, while MAP-2 was present in both unbound and adsorbed fractions.
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PMID:Inhibition of microtubule assembly by poly(L-glutamic acid) and the site of its action. 242 86

Poly(glycolic acid) or polyglycolide (PGA) is a polymer of glycolic acid. Glycolic acid is produced during normal body metabolism and is known as hydroxyacetic acid. Strong implants can be manufactured from this polymer with a self-reinforcing (SR) technique and used in the treatment of fractures and osteotomies. Since 1984, SR-PGA implants have been used routinely in our hospital for internal fixation of bone fractures. These implants were studied extensively in experimental animals and proved biocompatible. In 1.7% of human cases, sinus formation may develop after the use of these implants, which does not disturb healing. Use of these absorbable implants is justified as it obviates the need for a second operation for implant removal and avoids the risks associated with biostable implants.
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PMID:Absorbable polyglycolide devices in trauma and bone surgery. 900 89

The clinical biocompatibility and degradation of bioabsorbable interference screws of different polymer composition is described in this report for six patients who underwent repeat arthroscopy after anterior cruciate ligament (ACL) reconstruction. Bioabsorbable interference screws were used for bone plug fixation of bone--patellar tendon--bone (BPTB) autografts. Poly (L-lactide) (PLLA) interference screws were used in one case, poly (D,L-lactide-co-glycolide) (PDLLA-co-PGA) in two cases and poly (D,L-lactide) (PDLLA) in three cases. The patients either underwent removal of the femoral screw or had a biopsy taken from the screw site during re-arthroscopy. Large fragments of the PLLA screw were still present 20 months postoperatively. In one case, the PDLLA-co-PGA screw was extruded spontaneously from the tibial bone tunnel 3 weeks after the operation. In the second PDLLA-co-PGA screw case, there was no evidence left of the screw material on biopsy 12 months after implantation. The PDLLA screw in one patient was removed 6 weeks after implantation without any signs of degradation. No traces of the PDLLA screws were found in the two other patients, 10 or 14 months postoperatively. There were no clinical signs of foreign-body reactions in all cases.
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PMID:Clinical degradation and biocompatibility of different bioabsorbable interference screws: a report of six cases. 912 85

Poly(epsilon-caprolactone) (PCL) microspheres containing c. 3% bovine serum albumin (BSA) were prepared by melt encapsulation and solvent evaporation techniques. PCL, because of its low Tm, enabled the melt encapsulation of BSA at 75 degrees C thereby avoiding potentially toxic organic solvents such as dichloromethane (DCM). Unlike the solvent evaporation method, melt encapsulation led to 100% incorporation efficiency which is a key factor in the microencapsulation of water-soluble drugs. Examination of the stability of the encapsulated protein by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that protein integrity was unaffected by both methods of encapsulation. In vitro release of the protein into phosphate buffer examined at 37 degrees C from microspheres prepared by both techniques showed that the release rate from melt-encapsulated microspheres was somewhat slower compared to the release from solvent-evaporated spheres. Both released around 20% of the incorporated protein in 2 weeks amounting to approximately 6.5 micrograms mg-1 of microspheres. Although the diffusivity of macromolecules in PCL is rather low, it is shown that PCL microspheres are capable of delivering sufficient quantity of proteins by diffusion for prolonged periods to function as a carrier for many vaccines. Unlike poly(lactic acid) (PLA) and poly(glycolic acid) (PGA) polymers which generate extreme acid environments during their degradation, the delayed degradation characteristics of PCL do not generate an acid environment during protein release and, therefore, may be advantageous for sustained delivery of proteins and polypeptides.
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PMID:Protein release from poly(epsilon-caprolactone) microspheres prepared by melt encapsulation and solvent evaporation techniques: a comparative study. 915 Nov 93

Absorbable fibers of linear poly-alpha-hydroxy acids have been used successfully in providing temporary scaffolds for tissue regeneration. In some surgical applications, degradation rates for poly(glycolide) (PGA) are too high, but implants of poly(L-lactide) (PLLA) fibers may degrade too slowly for optimal function. Polymers produced by copolymerization of L-lactide with varying amounts of D-lactide may offer an alternative choice for absorbable fiber based implants. Poly(L/D-lactide) stereocopolymers with L/D lactide molar ratios of 95/5, 90/10, and 85/15 were considered. Melt-spun/hot-drawn fibers with L/D molar ratios of 90/10 and 85/15 and draw ratios ranging from 3.0 to 8.9 were further evaluated by mechanical testing, differential scanning calorimetry, birefringence, x-ray diffraction, and in vitro exposure to pH 7.4 phosphate buffered saline at 37 degrees C. Fabrication was reproducible and results indicated that tensile strength, modulus, an birefringence all increased with increasing draw ratio up to a draw ratio of 6.7 and declined thereafter; elongation to failure decreased for the entire range studied. For fibers with a draw ratio of 6.7, there was a 10% relative difference in crystallinity between the 90/10 and 85/15 lactide fibers (90/10 was higher). Wet strength retention after 12 weeks in vitro exposure was approximately 10% for the 90/10 fibers and 30% for the 85/15 fibers. The intermediate wet strength retention of lactide stereocopolymer fibers when compared to reported values for PGA and PLLA fibers, suggests these materials may be useful in absorbable surgical implants for tissue repair and regeneration.
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PMID:Processing and characterization of absorbable polylactide polymers for use in surgical implants. 1017 72

3-Alkylpyridinium polymers (poly-APS), composed of 29 or 99 N-butyl-3-butyl pyridinium units, were isolated from the marine sponge Reniera sarai. They act as potent cholinesterase inhibitors. The inhibition kinetics pattern reveals several successive phases ending in irreversible inhibition of the enzyme. To provide more information on mechanism of inhibition, interaction of poly-APS and N-butyl-3-butyl pyridinium iodide (NBPI) with soluble dimeric and monomeric insect acetylcholinesterase (AChE) was studied by using enzyme intrinsic fluorescence and light scattering, conformational probes ANS and trypsin, and SDS-PAGE. Poly-APS quenched tryptophan fluorescence emission of AChE more extensively than NBPI. Both inhibitors exhibited a pseudo-Lehrer type of quenching. Interaction of poly-APS with dimeric AChE did not induce significant changes of the enzyme conformation as assayed by using the hydrophobic probe ANS and trypsin digestion. In contrast to NBPI, titration of both monomeric and dimeric AChE with poly-APS resulted in the appearance of large complexes detected by measuring light scattering. An excess of poly-APS produced AChE precipitation as proved on SDS-PAGE. None of the effects were observed with trypsin as a control. It was concluded that AChE aggregation and precipitation rather than the enzyme conformational changes accounted for the observed irreversible component of poly-APS inhibition.
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PMID:Interaction of 3-alkylpyridinium polymers from the sea sponge Reniera sarai with insect acetylcholinesterase. 1039 43

Cell attachment to a scaffold is a precondition for the development of bioengineered valves and vascular substitutes. This attachment is generally facilitated by the use of precoating factors, but some can cause toxic or immunologic side effects. Autologous extracellular matrix (ECM) is used as a precoating factor in our study. Ascending aortic tissue was cultured to obtain human myofibroblasts. Autologous ECM was extracted from the same aortic tissue. Poly(glycolic acid) (PGA) scaffolds were precoated with autologous ECM, human serum, or poly-L-lysine; the control group was pretreated with phosphate buffered saline (PBS). Myofibroblasts were seeded onto each scaffold, and the cell attachment was assayed and compared. Compared with the control group, precoating with human serum, poly-L-lysine, and ECM increased number of attached cells by 24%, 53%, and 48%, respectively. Differences between precoating groups were significant (p < 0.01), except for ECM versus poly-L-lysine. Scanning electron microscopy also demonstrated the high degree of cell attachment to the PGA fibers on scaffolds precoated with ECM and poly-L-lysine. Precoating polymeric scaffold with autologous human extracellular matrix is a very effective method of improving cell attachment in cardiovascular tissue engineering without the potential risk of immunologic reactions.
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PMID:Scaffold precoating with human autologous extracellular matrix for improved cell attachment in cardiovascular tissue engineering. 1111 Feb 71

Poly(gamma-D-glutamic acid) (PGA)-producing strains of Bacillus species were investigated to determine their ability to contribute to reducing the amount of ammonium nitrogen in liquid manures and their ability to convert some of the ammonium into this polyamino acid as a transient depot for nitrogen. Organisms that do these things should help solve the serious environmental problems which are caused by the use of large amounts of liquid manure resulting from intensified agriculture; these problems are mainly due to the high content of ammonium nitrogen. Bacillus licheniformis ATCC 9945 and Bacillus subtilis were able to grow in liquid manure and to produce PGA in the presence of sodium gluconate. On artificial liquid manure these two strains were able to produce 0.85 and 0.79 g of PGA per liter, respectively. Under conditions that are found in intensified farming situations the ammonia content was reduced within 48 h from 1.3 to 0.75 g/liter. One mutant of B. subtilis 1551 impaired in the catabolism of PGA was obtained after nitrosoguanidine mutagenesis. This mutant produced PGA at a final concentration of 4.8 g/liter, whereas the wild type produced only 3.7 g/liter.
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PMID:Cultivation of bacteria producing polyamino acids with liquid manure as carbon and nitrogen source. 1115 24

gamma-Poly(glutamic acid) (gamma-PGA), which is produced by Bacillus subtilis, was sulfonated using 2-aminoethane-1-sulfonic acid (taurine) in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (WSC) to give sulfonated gamma-PGA (gamma-PGA-sulfonate). From (1)H NMR spectroscopy and IR spectroscopy, it was confirmed that taurine was introduced to the side chain of gamma-PGA via an amide linkage. By altering the synthetic conditions, it was possible to control the content of sulfonate in gamma-PGA-sulfonate. Anticoagulant activity was investigated in order to evaluate the biological activity of gamma-PGA-sulfonate by the Lee-White test. The clotting time was prolonged when the concentration of gamma-PGA-sulfonate on the degree of sulfonation was increased. It becomes clear that gamma-PGA-sulfonate is potentially useful for various medical applications, such as drug delivery, tissue engineering, and medical materials.
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PMID:Novel functional biodegradable polymer: synthesis and anticoagulant activity of poly(gamma-glutamic acid)sulfonate (gamma-PGA-sulfonate). 1179 75

Poly(glutamic acid) (PGA) is a water-soluble, biodegradable biopolymer that is produced by microbial fermentation. Recent research has shown that PGA can be used in drug delivery applications for the controlled release of paclitaxel (Taxol) in cancer treatment. A fundamental understanding of the key fermentation parameters is necessary to optimize the production and molecular weight characteristics of poly(glutamic acid) by Bacillus subtilis for paclitaxel and other applications of pharmaceuticals for controlled release. Because of its high molecular weight, PGA fermentation broths exhibit non-Newtonian rheology. In this article we present experimental results on the batch fermentation kinetics of PGA production, mass transfer of oxygen, specific oxygen uptake rate, broth rheology, and molecular weight characterization of the PGA biopolymer.
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PMID:Rheology, oxygen transfer, and molecular weight characteristics of poly(glutamic acid) fermentation by Bacillus subtilis. 1259 56


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