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

In a previous study, we have reported chemical synthesis of novel aliphatic poly(butylene succinate-co-cyclic carbonate) P(BS-co-CC)s bearing various functionalizable carbonate building blocks, and this work will continue to present our new studies on their enzymatic degradation and in vitro cell biocompatibility assay. First, enzymatic degradation of the novel P(BS-co-CC) film samples was investigated with two enzymes of lipase B Candida Antartic (Novozyme 435) and lipase Porcine Pancreas PPL, and it was revealed that copolymerizing linear poly(butylene succinate) PBS with a functionalizable carbonate building block could remarkably accelerate the enzymatic degradation of a synthesized product P(BS-co-CC), and its biodegradation behavior was found to strongly depend on the overall impacts of several important factors as the cyclic carbonate (CC) comonomer structure and molar content, molar mass, thermal characteristics, morphology, the enzyme-substrate specificity, and so forth. Further, the biodegraded residual film samples and water-soluble enzymatic degradation products were allowed to be analyzed by means of proton nuclear magnetic resonance (1H NMR), gel permeation chromatograph (GPC), differential scanning calorimeter (DSC), attenuated total reflection FTIR (ATR-FTIR), scanning electron microscope (SEM), and liquid chromatograph-mass spectrometry (LC-MS). On the experimental evidences, an exo-type mechanism of enzymatic chain hydrolysis preferentially occurring in the noncrystalline domains was suggested for the synthesized new P(BS-co-CC) film samples. With regard to their cell biocompatibilities, an assay with NIH 3T3 mouse fibroblast cell was conducted using the novel synthesized P(BS-co-CC) films as substrates with respect to the cell adhesion and proliferation, and these new biodegradable P(BS-co-CC) samples were found to exhibit as low cell toxicity as the PLLA control, particularly the two samples of poly(butylene succinate-co-18.7 mol % dimethyl trimethylene carbonate) P(BS-co-18.7 mol % DMTMC) and poly(butylene succinate-co-21.9 mol % 5-benzyloxy trimethylene carbonate) P(BS-co-21.9 mol % BTMC) were interestingly found to show much better cell biocompatibilities than the PLLA reference.
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PMID:Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s bearing functionalizable carbonate building blocks: II. Enzymatic biodegradation and in vitro biocompatibility assay. 1553 40

A new class of biodegradable poly-amino acid, alpha,beta-poly[(N-hydroxypropyl/aminoethyl)-DL-Aspartamide-co-L-Lysine] (PHAAL), was synthesized by ring-opening of poly[succinimide-co-lysine](PSL) with n-propanolamine and ethylene diamine after thermal copolycondensation of DL-Aspartic acid and L-lysine under reduced pressure. Different ratio feeds of PSL were obtained and characterized by 1H-NMR, Fourier transformed infrared spectroscopy, X-ray, thermogravimetric analysis and gel permeation chromatography experiments. As one of the polycationic materials, performed for gene delivery carrier, the PHAAL degradation experiment was carried out in PBS (10 mM, pH =7.4) and enzyme (papain, trypsine 1 mg/ml, 37 +/- 0.1 degree C) solution. PHAAL had lower cytotoxicity than polyethylenimine (25KDa) and poly-L-Lysine (30 KDa), in Hela, E.C.V.-304, Bcap 37 cell lines. Particle size and zeta, potential of PHAAL/DNA complexes were measured. Sizes ranged from 300-500 nm and zeta potentials were at -20 to 2,5 mV. The condensation ability of PHAAL for DNA was evaluated by agarose gel electrophoresis. The PHAAL could completely neutralize DNA at N/P ratio (w/w) 150:1.
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PMID:A new biodegradable poly-amino acid: alpha,beta-poly[(N-hydroxypropyl/aminoethyl)-DL-aspartamide-co-L-lysine], a potential nonviral vector for gene delivery. 1582 33

Bioactivity of biomaterials was a new requirement, especially in tissue engineering and drug delivery. As a traditional used biomaterial, polylactide (PLA) had no bioactivity, of course, and it still had few reactive groups to introduce some bioactive molecules in its bulk. Here, we want to introduce carboxyl groups and amino groups in the side chain of PLA to get more reactive groups for incorporating bioactive molecular later and to maintain the structure of main chain to keep its biodegradability, and to settle the acidity of PLA during hydrolysis at the same time. It was performed as follows: first, maleic anhydride was covalently grafted onto the side chain of PLA by a free radical reaction at 100 degrees C for 20 h with BPO as the initiator. Then, by amidation with a maleic anhydride group on PLA at room temperature, hexanediamine was incorporated. The resulting polymers have been characterized via GPC, (13)C NMR, DSC, and TGA. The graft ratio was tested by titration. The pH changes during hydrolysis in 0.1 M PBS with pH 7.4 of PLA, MPLA, and HPLA were investigated. All the results showed that this research has grafted maleic anhydride and then hexanediamine in the bulk of PLA. The molecular weight degradation during reaction was less than 20%. The graft ratios of were 2.68, 2.36, and 1.86%, respectively in 5, 10, and 20% raw MA in MPLA; and the anhydride groups grafted in MPLA can completely react with hexanediamine at room temperature. The pH value of HPLA remained neutral within 12 weeks' hydrolysis compared with the resulted acidity of PLA and MPLA.
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PMID:Grafting reaction of poly(D,L)lactic acid with maleic anhydride and hexanediamine to introduce more reactive groups in its bulk. 1588 45

The complex [(tacn)(6)Fe(8)(micro(3)-O)(2)(micro(2)-OH)(12)]Br(8).9H(2)O (Fe(8)) was evaluated in vitro as a new kind of possible MRI contrast agent. Relaxivities were measured at 1.41 and 9.4 T for Fe(8) and commercial Gd-DTPA dissolved in PBS. There was significant difference for r(1) and r(2) values between Fe(8) and Gd-DTPA at high field (9.4 T) and for r(1) at low field (1.4 T) (p<0.05). Phantom studies with T(1)-weighted MRI at 9.4 T suggest T(1) contrast potential for Fe(8). That is, up to 5.2 times higher intensity enhancement with respect to that of equimolar Gd-DTPA was obtained with an Fe(8) concentration, referred to the whole molecule, of 0.2 mM, for which no toxicity on C6 cells could be detected. No toxic effects on cultured C6 cells were observed up to a concentration of 1 mM Fe(8).
NMR Biomed 2005 Aug
PMID:In vitro characterization of an Fe(8) cluster as potential MRI contrast agent. 1591 77

In this study, the reactions of N-acetyl-L-methionine (AcMet) with [{trans-PtCl(NH(3))(2)}(2)-mu-H(2)N(CH(2))(6)NH(2)](NO(3))(2) (BBR3005: 1,1/t,t 1) and its cis analog [{cis-PtCl(NH(3))(2)}(2)-mu-{H(2)N(CH(2))(6)NH(2)}]Cl(2) (1,1/c,c 2) were analyzed to determine the rate and reaction profile of chloride substitution by methionine sulfur. The reactions were studied in PBS buffer at 37 degrees C by a combination of multinuclear ((195)Pt, {(1)H-(15)N} HSQC) magnetic resonance (NMR) spectroscopy and electrospray ionization time of flight mass spectrometry (ESITOFMS). The diamine linker of the 1,1/t,t trans complex was released as a result of the trans influence of the coordinated sulfur atom, producing trans-[PtCl(AcMet)(NH(3))(2)](+) (III) and trans-[Pt(AcMet)(2)(NH(3))(2)](2+) (IV). In contrast the cis geometry of the dinuclear compound maintained the diamine bridge intact and a number of novel dinuclear platinum compounds obtained by stepwise substitution of sulfur on both platinum centers were identified. These include (charges omitted for clarity): [{cis-PtCl(NH(3))(2)}-mu-NH(2)(CH(2))(6)NH(2)-{cis-Pt(AcMet)(NH(3))(2)}] (V); [{cis-Pt(AcMet)(NH(3))(2)}(2)-mu-NH(2)(CH(2))(6)NH(2)] (VI); [{cis-PtCl(NH(3))(2)}-mu-NH(2)(CH(2))(6)NH(2)-{PtCl(AcMet)NH(3)] (VII); [{PtCl(AcMet)(NH(3))}(2)-mu-NH(2)(CH(2))(6)NH(2)] (VIII); [{trans-Pt(AcMet)(2)(NH(3))}-mu-NH(2)(CH(2))(6)NH(2)-{PtCl(AcMet)(NH(3))] (IX) and the fully substituted [{trans-Pt(AcMet)(2)(NH(3))}(2)-mu-{NH(2)(CH(2))(6)NH(2)] (X). For both compounds the reactions with methionine were slower than those with glutathione (Inorg Chem 2003, 42:5498-5506). Further, the 1,1/c,c geometry resulted in slower reaction than the trans isomer, because of steric hindrance of the bridge, as observed previously in reactions with DNA and model nucleotides.
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PMID:Effects of geometric isomerism in dinuclear antitumor platinum complexes on their interactions with N-acetyl-L-methionine. 1609 34

The objective of this study was to investigate the effect of aqueous solubility of model drugs and glycolide monomer (GM) from poly(D,L-lactide-co-glycolide) (PLGA) discs on in vitro release rates and polymer degradation. 5-Fluorouracil (5-FU), a water-soluble compound, and dexamethasone in a water-insoluble base form were selected as model drugs. Glycolide monomer, that has moderate solubility in water, was a non-toxic and biodegradable additive as a derivative material of hydrolysis of PLGA in order to obtain desirable drugs release rates. PLGA discs with or without GM were formulated by means of compression molding method. The prepared polymeric discs were incubated at 37 degrees C in phosphate-buffered saline (PBS, pH 7.4) and characterized at scheduled time points for water uptake, mass loss, diameter and morphology change, molecular weight and composition change using scanning electron microscopy (SEM), gel-permeation chromatography (GPC), and H-NMR, respectively. The supernatants were taken out of the sample vials and were analyzed for drug release. The 5-FU release was found to be increasing in proportion to the drug loading amount with an initial burst for 5 days, while dexamethasone release showed inverse relationship with the increasing drug loading amount. However, the release behaviors of 5-FU and dexamethasone polymeric discs containing GM showed faster release rates than control discs (without GM) and did not show lag periods during the in vitro release test due to adding GM, which acted as a channeling agent that has moderate solubility in water. Polymer degradation was found to be affected by aqueous solubility of drugs and GM. In conclusion, we observed that drugs release rates were influenced by their aqueous solubility and loading amount and also GM plays a major role in controlling drug release rates regardless of solubility of drugs. This system appears to be promising for controlled drug delivery aimed at local therapy.
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PMID:Co-effect of aqueous solubility of drugs and glycolide monomer on in vitro release rates from poly(D,L-lactide-co-glycolide) discs and polymer degradation. 1612 33

Poly(butylene succinate-co-butylene adipate) (PBSA)-degrading bacterium, strain 1-A, was isolated from soil. Strain 1-A was identified as Bacillus pumilus on the basis of its physiological properties and partial 16S rRNA gene sequence. Strain 1-A also degraded poly(butylene succinate) (PBS) and poly(epsilon-caprolactone). On the other hand, poly(butylene adipate terephthalate) and poly(lactic acid) were minimally degraded by strain 1-A. The NMR spectra of degradation products from PBSA indicated that the adipate units were more rapidly degraded than 1,4-butanediol and succinate units. This seems to be one of the reasons why strain 1-A degraded PBSA faster than PBS.
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PMID:Isolation and characterization of poly(butylene succinate-co-butylene adipate)-degrading microorganism. 1623 4

A novel poly(epsilon-caprolactone)/calcium sulfate system was prepared and characterized in order to enhance calcium sulfate (gypsum) performance as bone graft substitute overcoming its brittleness and fast resorption rate. A poly(epsilon-caprolactone) (PCL) photo-crosslinkable derivative (PCLf) was synthesized by reaction of a low molecular weight PCL diol with methacryloyl chloride and confirmed by FT-IR and 1H NMR analyses. An injectable and easy mouldable mixture of PCLf and calcium sulfate hemi-hydrate (PCLf/CHS) was obtained. Thermal analyses and solvent extraction proved the occurrence of PCLf photo-crosslinking, even in the presence of CHS, in a time suitable for clinical applications. Swelling studies demonstrated that the encapsulation of the inorganic filler increases network hydrophilicity making it more permeable to water. Scanning electron microscopy, performed on crosslinked PCLf/CHS and on the same material after incubation in a PBS solution, showed the feasibility to obtain, in situ, gypsum entrapped into a degradable polymeric network. In vitro cytotoxicity tests, performed according to ISO 10993-5, proved that the developed system was not cytotoxic supporting its potential use in tissue engineering as a new, injectable, photocurable bone graft material. SEM micrograph of calcium sulfate di-hydrate (gypsum) entrapped in the PCL network.
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PMID:A novel injectable poly(epsilon-caprolactone)/calcium sulfate system for bone regeneration: synthesis and characterization. 1624 68

PEGylated polyamidoamine (PAMAM) dendrimers as drug carriers have been a topic of interest because of their biomedically favorable features, including minimal toxicity, reduced immunogenicity, and excellent solubility in aqueous and most organic solutions. A PEG shell on dendrimer surface may provide steric hindrance, known as stealth properties of PEG, to stabilize drug molecules to be delivered. In this article, the effects of PEG and coupling sequence of drug, PEG, and dendrimer in modulating the stability of delivered drug molecules were evaluated. N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide was chosen as a model peptide. Dendritic peptides, that is, peptide-dendrimer, peptide-PAMAM-PEG, and peptide-PEG-dendrimer, were constructed based on Starbursttrade mark G3.0 PAMAM dendrimer and characterized by (1)H-NMR spectroscopy. Hydrolysis of dendritic peptides was catalyzed by alpha-chymotrypsin in pH 7.4 PBS buffer containing 5% DMF (v/v) at room temperature. The enzymatic stability of dendritic peptides was peptide-PAMAM-PEG > peptide-PAMAM > free peptide > peptide-PEG-PAMAM. The ratio of PEG/peptide could be reduced for increasing peptide loading while maintaining the delivered peptides' relatively high enzymatic stability. The quantitative analysis of dendritic peptide/enzyme interactions provided the understandings of the molecular structure/stability relationships of dendrimer/drug for the design of an optimal PEGylated dendrimer-based drug-delivery system.
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PMID:In vitro enzymatic stability of dendritic peptides. 1627 Mar 46

A new family of heterobifunctional linkers (L1-L9) containing a terminus consisting of a tridentate donor set for coordination of the {M(CO)(3)}(+) core (M = Tc, Re), and a thiol reactive maleimide group has been prepared conveniently and in high yield under Mitsunobu reaction conditions by the coupling of an appropriate alcohol derivative with maleimide. The rhenium complexes [Re(CO)(3)(Lx)]Br (x= 1-9) were prepared in good yields from the reactions of the ligands and (NEt(4))(2)[Re(CO)(3)Br(3)] in refluxing methanol. The ligands and their Re complexes were characterized by (1)H and (13)C NMR, IR, and ESI-MS. Ligand L4 and [Re(CO)(3)(L5)]Br have been structurally characterized by X-ray crystallography. Photoexcitation of solutions of the complexes [Re(CO)(3)(Lx)]Br (x= 4-6) gives rise to intense and prolonged luminescence at room temperature (fluorescence lifetimes of ca. 16 micros). The ligands and their Re complexes react smoothly at the maleimide linker with sulfhydryl groups of peptides and proteins at room temperature in phosphate-buffered saline (PBS, pH 7.4) to form stable thioether bioconjugates. The photoluminescence properties of the labeled conjugates are similar to those of the parent complexes, but with even longer lifetimes. The ligands can also be labeled at room temperature with (99m)Tc to give chemically robust complexes. The corresponding hydrazinonicotinamide derivative N-[5-(6'-hydrazinopyridine-3'-carbonyl)aminopentyl]maleimide (L10) was also prepared. While coupling of L10 to cysteine ethylester and synthesis of the rhenium derivative [ReCl(3)(HYNIC-maleimide)(2)] were successfully accomplished, attempts to couple [ReCl(3)(HYNIC-maleimide)(2)] to glutathione or BSA yielded intractable mixtures.
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PMID:Design and synthesis of site directed maleimide bifunctional chelators for technetium and rhenium. 1631 43


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