Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0393754 (HSA)
 2,996 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comparative study of thermodynamic and kinetic aspects of Cu(II) and Ni(II) binding at the N-terminal binding site of human and bovine serum albumins (HSA and BSA, respectively) and short peptide analogues was performed using potentiometry and spectroscopic techniques. It was found that while qualitative aspects of interaction (spectra and structures of complexes, order of reactions) could be reproduced, the quantitative parameters (stability and rate constants) could not. The N-terminal site in HSA is much more similar to BSA than to short peptides reproducing the HSA sequence. A very strong influence of phosphate ions on the kinetics of Ni(II) interaction was found. This study demonstrates the limitations of short peptide modelling of Cu(II) and Ni(II) transport by albumins.
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PMID:Short peptides are not reliable models of thermodynamic and kinetic properties of the N-terminal metal binding site in serum albumin. 1185 67

Poly(ethylene glycol)s (PEGs) are potential drug carriers for improving the therapeutic index of anticancer agents. In this work, the anticancer drug methotrexate (MTX) was activated with N,N'-dicyclohexylcarbodiimide (DCC) and coupled to amino group bearing PEGs of MW 750, 2000, 5000, 10 000, 20,000, and 40,000. First, the activation process of MTX with DCC in the presence and absence of N-hydroxysuccinimide was analyzed through HPLC. Preincubation of methotrexate with DCC alone at 0 degrees C proved to be favorable with respect to the amount of activated species and the formation of byproducts. MTX-PEG conjugates were synthesized according to this procedure, isolated through size-exclusion chromatography, and characterized through analytical HPLC, MALDI-TOF spectrometry, and gel permeation chromatography. In a cell-free assay, all of the drug polymer conjugates inhibited the target enzyme of MTX, dihydrofolate reductase (DHFR), to a similar extent, but were not as active as free MTX. Additionally, incubation of the MTX-PEG40000 conjugate for 6 days at 37 degrees C in phosphate buffered saline (pH 7.4), in cell-conditioned medium, or in human serum revealed no significant release of methotrexate. These results, taken together, indicate that release of MTX from polymer conjugates is not necessary for an effective interaction with the active site of dihydrofolate reductase. Evaluation of the in vitro cytotoxicity of the MTX-PEG conjugates in two adherent and three suspension human tumor cell lines revealed that the IC(50) values of the tested compounds increased with the size of the drug-polymer conjugates. The most effective compound tested in these assays was the free drug MTX itself (IC(50) value ranging from approximately 0.01 to 0.05 microM), while the IC(50) values of the polymer conjugates were higher (IC(50) value for MTX-PEG750, 2000 and 5000: approximately 0.6-3 microM; for MTX-PEG10000 and 20000: approximately 2-7 microM; and for MTX-PEG40000: > 6 microM). Subsequently, MTX-PEG5000, MTX-PEG20000, and MTX-PEG40000 were evaluated in a human mesothelioma MSTO-211H xenograft model, and their antitumor effects were compared with free methotrexate and the albumin conjugate MTX-HSA, a conjugate that is currently in phase II clinical trials. In contrast to the in vitro results, the high molecular weight MTX-PEG conjugates exhibited the highest in vivo antitumor activity: At a dose of 40 and 80 mg/kg MTX-PEG5000 was less active than MTX at its optimal dose of 100 mg/kg; MTX-PEG20000 at a dose of 40 mg/kg showed antitumor efficacy comparable to MTX, but MTX-PEG40000 at a dose of 20 mg/kg was superior to MTX and demonstrated antitumor activity of the same order as MTX-HSA (20 mg/kg).
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PMID:Polyethylene glycol conjugates of methotrexate varying in their molecular weight from MW 750 to MW 40000: synthesis, characterization, and structure-activity relationships in vitro and in vivo. 1212 Nov 33

Safety and bioavailability of pulmonary delivered interferon-beta 1a (IFN-beta1a, AVONEX, Biogen, Inc., Cambridge, MA) was evaluated in the nonhuman primate. Pulmonary bioavailability following intratracheal (i.t.) instillation of 50 microg/kg IFN-beta1a to rhesus macaques was approximately 10%. To evaluate pulmonary safety, IFN-beta1a was administered intrabronchially to rhesus and cynomolgus macaques at a dose of 60 microg/dose one, three, or seven times per week for 4 weeks. At scheduled termination, lungs were evaluated for gross and histomorphologic changes. IFN-beta1a or vehicle (human serum albumin [HSA] in phosphate-buffered saline [PBS]) treatment resulted in minimal to mild subchronic alveolitis, located primarily near the instillation sites. These responses were considered nonspecific and consistent with either instillation of a foreign protein or minor injury associated with the instillation procedure. In one rhesus macaque treated every day for 4 weeks, IFN-beta1a induced mild to moderate eosinophilic alveolitis, considered possibly an isolated type I hypersensitivity response to HSA or IFN-beta1a. Partial resolution of pulmonary lesions was seen in all recovery animals killed 2 weeks after cessation of treatment. In conclusion, this study shows that pulmonary administration of human IFN-beta1a is safe and that the pulmonary route of administration is a possible alternate route for the systemic delivery of IFN-beta1a.
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PMID:Safety and systemic absorption of pulmonary delivered human IFN-beta1a in the nonhuman primate: comparison with subcutaneous dosing. 1216 83

A new assay for the screening of hypochlorite/hypochlorous acid (XOCl) scavengers, based on the reversed-phase high performance liquid chromatographic analysis of human serum albumin (HSA, 0.2% in 100 mM sodium phosphate, pH 7), before and after oxidation by XOCl (1.6 mM), was developed. XOCl induced a significant decrease of the area under the chromatographic peak of HSA at 280 nm due to the oxidation of the aromatic amino acids tryptophan and tyrosine, as suggested by the literature and by the chromatographic analyses and the electrochemical study performed here. The assay was validated by testing known XOCl scavengers such as ascorbic acid, cysteine, glutathione, S-methylglutathione and alpha-lipoic acid and other antioxidants such as carnosine and chlorogenic acid, which inhibited the oxidation of HSA. Quantitative activities were calculated using an original formula based on the changes of the area of the albumin peak. Electrochemical data collected here in a homogeneous medium showed that the anodic potentials of the antioxidants tested are less positive (ascorbic acid, chlorogenic acid and cysteine) or similar (alpha-lipoic acid) compared with those of the aromatic residues (tryptophan and tyrosine) of HSA oxidized by XOCl. However, as expected, carnosine, glutathione and S-methylglutathione were inactive at a glassy-carbon, gold or platinum electrode.
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PMID:Development of a new assay for the screening of hypochlorous acid scavengers based on reversed-phase high-performance liquid chromatography. 1222 98

A fluorescent biosensor assay has been developed for near real-time detection of 2,4-dinitrophenol (DNP). The assay was based on fluorescent detection principles that allow for the analysis of antibody/antigen interactions in solution using the KinExA immunoassay instrument. Our KinExA consisted of a capillary flow observation cell containing a microporous screen that maintains a compact capture antigen-coated bead bed. The bead bed was comprised of polymethylmethacrylate (PMMA) beads coated with dinitrophenol-human serum albumin (DNP-HSA) conjugate. Phosphate buffered saline (PBS) solutions, containing various concentrations of free DNP, were incubated for 30 min with mouse anti-DNP monoclonal antibody to equilibrium. Solutions containing the DNP-monoclonal antibody complex and possible excess free antibodies were then passed over DNP-HSA labeled beads. The free monoclonal anti-DNP antibody, if available, was then bound to the DNP-HSA fixed on the beads. The system was then flushed with excess PBS to remove unbound reactants in the bead bed. The beads were then subjected to brief contact with PBS solutions containing goat anti-mouse fluorescein isothiocyanate (FITC)-labeled secondary antibody, once again, followed by a short PBS flush. The fluorescence was recorded during the addition of the FITC labeled secondary antibody to the bead bed through the final PBS flushing with the KinExA. The amount of DNP detected could then be determined from the fluorescent slopes that were generated or by the remaining fluorescence that was retained on the beads after final PBS flushing of the system. This assay has been able to detect a minimum of 5 ng/ml of DNP in solution and can be adapted for other analytes of interest simply by changing the capture antigen and antibody pairs.
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PMID:Near real-time biosensor-based detection of 2,4-dinitrophenol. 1244 46

Bilirubin is a toxic substance. In order to effectively remove it from the hepatic patients' blood, two novel affinity membranes were prepared. These were prepared by chemically grafting on cellulose and immobilized with different ligands. One kind of ligand was poly-D-lysine, the other one was quaternary ammonium salt. Both affinity membranes were used for removal bilirubin from phosphate buffer and HSA solutions, and the effects of temperature, HSA concentration, adsorption time in static state experiment and flow rate in dynamic state experiment have been investigated. The results indicated that the membranes could remove over 70% bilirubin from phosphate buffer and at least 50% from low concentration HSA solutions. The results also indicated that the removal efficiency was better at higher temperature. In the static state experiment, four hours can be selected as adsorption time. In the dynamic state experiment, the flow rate can be properly increased.
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PMID:[Novel affinity membrane used for bilirubin removal]. 1254 52

2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely used broadleaf herbicide that has been associated with acute liver toxicity in exposed humans or animals. Chemically reactive metabolites of 2,4-D are proposed as mediators of 2,4-D-induced hepatotoxicity. The aim of the present study was to investigate a novel reactive metabolite of 2,4-D, namely 2,4-dichlorophenoxyacetyl-S-acyl-CoA (2,4-D-CoA), and to determine its involvement in 2,4-D covalent adduct formation. Thus, incubations of synthetic 2,4-D-CoA (106 microM) with GSH (1 mM) in phosphate buffer (pH 7.4) showed 2,4-D-CoA to be able to transacylate the cysteine sulfhydryl of GSH, resulting in the formation of 2,4-D-S-acyl-glutathione (2,4-D-SG) thioester and reaching a concentration of 65 microM after 1 h of incubation. Under similar conditions, 2,4-D-CoA was shown to covalently bind to nucleophilic groups on human serum albumin (HSA, 30 mg/ml), resulting in time-dependent 2,4-D-HSA covalent adduct formation that reached a maximum of 440 pmol/mg HSA after 1 h of incubation. In addition to these studies, incubations of [1-(14)C]2,4-D (1 mM) with rat hepatocytes showed a time-dependent covalent binding of 2,4-D to hepatocyte protein. Inhibition of acyl-CoA formation by trimethylacetic acid (2 mM) decreased the amount of covalent binding to protein in rat hepatocytes by 50%. These results indicate that 2,4-D-CoA thioester is a reactive metabolite of 2,4-D that may contribute to 2,4-D-protein adduct formation in vivo and therefore the associated hepatotoxicity.
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PMID:In vitro studies on the chemical reactivity of 2,4-dichlorophenoxyacetyl-S-acyl-CoA thioester. 1264 42

In this study, we measured the antiallergic activities of ginsenosides isolated from the root of Panax ginseng ( Araliaceae), and of their metabolites, as produced by human intestinal bacteria. Compound K, which was identified as a main metabolite, had the most potent inhibitory activity on beta-hexosaminidase release from RBL-2H3 cells and on the PCA reaction. The inhibitory activity of compound K was more potent than that of disodium cromoglycate, one of the commercial anti-allergic drugs. This compound demonstrated a membrane stabilizing action on differential scanning calorimetry. However, compound K did not inhibit the activation of hyaluronidase and did not scavenge active oxygen. These results suggest that the antiallergic action of compound K originates from its cell membrane stabilizing activity and that the ginsenosides of ginseng are prodrugs with extensive antiallergic properties. Abbreviations. compound K:20- O-beta- D-glucopyranosyl-20( S)-protopanaxadiol DNP:dinitrophenol DSCG:disodium cromoglycate DPPC:dipalmitoylphosphatidylcholine DPPH:1,1-diphenyl-2-picrylhydrazyl HSA:human serum albumin IC 50 :50% inhibitory concentration EC 50 :50% effective concentration XOD:xanthine oxidase ICR:Institute of Cancer Research PBS:phosphate buffered saline PCA:passive cutaneous anaphylaxis RAW264.7:mouse monocyte leukemiaRBL-2H3: rat basophil leukemia SD:Sprague-Dawley
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PMID:Antiallergic activity of ginseng and its ginsenosides. 1286 69

Sonic absorption spectra of solutions of human serum albumin (SA) in water and in aqueous phosphate buffer systems have been measured between 0.2 and 2000 MHz at different temperatures (15-35 degrees C), pH values (1.8-12.3), and protein concentrations (1-40 g/L). Several spectra, indicating relaxation processes in the whole frequency range, have been found. The spectra at neutral pH could be fitted well with an analytical function consisting of the asymptotic high frequency absorption and two relaxation contributions, a Debye-type relaxation term with discrete relaxation time and a term with asymmetric continuous distribution of relaxation times. Both relaxation contributions were observed in water and in buffer solutions and increased with protein concentration. The contribution represented by a Debye-type term is practically independent of temperature and was attributed to cooperative conformational changes of the polypeptide chain featuring a relaxation time of about 400 ns. The distribution of the relaxation times corresponding to the second relaxation contribution was characterized by a short time cutoff, between about 0.02 and 0.4 ns depending on temperature, and a long time tail extending to microseconds. Such relaxation behavior was interpreted in terms of solute-solvent interactions reflecting various hydration layers of HSA molecules. At acid and alkaline pH, an additional Debye-type contribution with relaxation time in the range of 30-100 ns exists. It seems to be due to proton transfer reactions of protein side-chain groups. The kinetic and thermodynamic parameters of these processes have been estimated from these first measurements to indicate the potential of acoustic spectra for the investigation of the elementary kinetics of albumin processes.
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PMID:Dynamics of human serum albumin studied by acoustic relaxation spectroscopy. 1513 89

In the present research, assays were improved for the determination of catecholamines in adrenal gland. High-performance liquid chromatography with electrochemical detection was employed for quantitative analysis. The method involved direct injection of acid extract on to a serum albumin dimethylocadecyl-silane (HSA-C18) and the utilization of phosphate buffer (pH = 3.0): methanol (97:3 v/v), 0.025 g heptanosulfonic acid and 0.0025 g EDTA as mobile phase. The detection was obtained using an electrochemical detector L-ECD-6A-Shimadzu with a potential of the 85 mV. Identification was based on retention time. Quantification was performed by automatic peak-area determination. The detection limit is equal to 0.5 ng ml(-1). The HPLC method with electrochemical detection proposed here permits good separation of catecholamines in samples of adrenal gland from rats. The method has various advantages: fast, high precision and good selectivity and do not require sample treatment. The immobilization stress during 5 min did not provoke alteration in catecholamines contains in rat adrenal gland, due to the short time of the stress exposure. This study shows that the catecholamines (norepinephrine and epinephrine) adrenal increased significantly after the acute immobilization stress during 30 min as compared to control group. This increase probably is due to the emotional component of the immobilization stress. In conclusion, our studies suggest an effective participation of the adrenal glands to maintain the homeostasis of organism to the stressful conditions.
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PMID:A simple high-performance liquid chromatography assay for on-line determination of catecholamines in adrenal gland by direct injection on an ISRP column. 1545 68


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