Showing papers on "Glutaraldehyde published in 2001"

Chemical Reactions in Cottonseed Protein Cross-Linking by Formaldehyde, Glutaraldehyde, and Glyoxal for the Formation of Protein Films with Enhanced Mechanical Properties

Abstract: Amino acids involved in cottonseed protein cross-linking by formaldehyde, glutaraldehyde, and glyoxal during protein film formation were identified by an original technique The entire HPLC amino acid profile (after acid hydrolysis) was studied, along with variations in reactive lysine contents, in films cross-linked or not with increasing quantities of formaldehyde, glutaraldehyde, and glyoxal This strategy highlighted the formation of acid-resistant lysine derivatives that a simple reactive lysine determination would not have detected The results-which agree with previously published data-enhance the overall understanding of cross-linking activities that occur in aqueous alkaline solutions during the formation of protein films made with cottonseed flour Lysine was found to have a key role in protein cross-linking by dialdehydes, with the involvement of tyrosine in the presence of formaldehyde and of arginine in the presence of glyoxal These results could provide valuable chemical tools for adjusting the mechanical properties of cottonseed protein films

Interpenetrating polymer networks based on poly(acrylic acid) and gelatin. I: Swelling and thermal behavior

Abstract: This article describes the synthesis of full and semi-interpenetrating polymer networks (IPNs) based on poly(acrylic acid) and gelatin as polymers 1 and 2, which were crosslinked sequentially using N,N′-methylene bisacrylamide (BAm) and glutaraldehyde, respectively. Various samples were prepared by taking varying amounts of acrylic acid and gelatin in the initial feed. Sequential IPNs were prepared by first polymerizing and crosslinking acrylic acid in the presence of gelatin using redox initiators (ammonium persulphate and sodium metabisulphite) and BAm as a crosslinking agent. Gelatin present in the firm gels was then crosslinked using 4% glutaraldehyde. Characterization of these gels was done by measuring their swelling behavior as a function of pH, temperature, and time. Percent swelling increased with increasing amounts of acrylic acid. The swelling ratio was also determined in the pH range of 1 to 12. Acid/alkali or buffers were used for maintaining pH. A significant increase in the percent swelling was observed when pH of distilled water was above 10. On the other hand, in the case of buffer, the swelling ratio increased with increasing the pH, and a maxima was observed at pH 8.4. A further increase in pH resulted in a decrease in the swelling ratio. Thermal and morphological characterization was done using thermogravimetric analyzer and scanning electron microscopy, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 217–227, 2001

Pseudo-outbreak of Mycobacterium chelonae and Methylobacterium mesophilicum caused by contamination of an automated endoscopy washer.

Abstract: Objective:To evaluate an unusual number of rapidly growing acid-fast bacilli, later identified as Mycobacterium chelonae, and pink bacteria, later identified as Methylo-bacterium mesophilicum, from fungal cultures obtained by bronchoscopy.Design:Outbreak investigation.Setting:An academic medical center performing approximately 500 bronchoscopies and 4,000 gastrointestinal endoscopies in 1998.Patients:Patients undergoing bronchoscopy July 21 to October 2, 1998.Methods:The infection control department reviewed patient charts and bronchoscopy logs; obtained cultures of source water, faucets, washers, unopened glutaraldehyde, glutaraldehyde from the washers, and endoscopes; observed endoscope and bronchoscope cleaning and disinfecting procedures; reviewed glutaraldehyde monitoring records; and sent M chelonae isolates for DNA fingerprinting.Results:M chelonae, M mesophilicum, gram-negative bacteria, and various molds grew from endoscopes, automated washers, and glutaraldehyde from the washers but not from unopened glutaraldehyde. The endoscopy unit regularly monitored the pH of glutaraldehyde, and the logs contained no deficiencies. The above sources remained positive for the same organisms after a glutaraldehyde cleaning cycle of the automated washers. DNA fingerprinting of the M chelonae revealed that they were clonally related.Conclusions:The automated washers were contaminated with a biofilm that rendered them resistant to decontamination. The washers then contaminated the endoscopes and bronchoscopes they were used to disinfect. Our institution purchased new endoscopes and a new paracetic acid sterilization system.

Controlled release of hepatocyte growth factor from gelatin hydrogels based on hydrogel degradation.

Abstract: This paper investigates the controlled release of hepatocyte growth factor (HGF) by biodegradable gelatin hydrogels and their HGF-induced angiogenic effect. Hydrogels of different degradabilities were prepared through chemical crosslinking gelatin with varied amounts of glutaraldehyde. When the gelatin hydrogels were radioiodinated and subcutaneously implanted into the back of mice, the remaining radioactivity of the hydrogels decreased with time. However, the remaining period became longer when the concentration of glutaraldehyde used for hydrogel preparation increased. Following implantation of gelatin hydrogels incorporating 125I-labeled HGF, the HGF radioactivity retained in the mouse subcutis for longer time periods as the glutaraldehyde concentration becomes higher. The time profile of HGF remaining in every gelatin hydrogel was in good accordance with that of hydrogel degradation, indicating HGF release as a result of hydrogel biodegradation. The gelatin hydrogel incorporating HGF histologically in...

Effects of acetone, methanol, or paraformaldehyde on cellular structure, visualized by reflection contrast microscopy and transmission and scanning electron microscopy.

Abstract: The authors recently showed variable subcellular immunoreactivity of the Bcl-2 and Bax proteins after fixation of cell monolayers with acetone, methanol, or paraformaldehyde (PF) followed by methanol (PF/methanol). Here, the authors demonstrate by reflection contrast microscopy and transmission electron microscopy that acetone or methanol fixation result in complete loss of integrity of intracellular structures in contrast with PF or glutaraldehyde fixation. Scanning electron microscopy revealed poor preservation of plasma membrane integrity after fixation in acetone or methanol. Fixation with PF before methanol reduced damage to intracellular and plasma membranes. In addition, Western blot analysis demonstrated loss of Bcl-2 and Bax protein during acetone or methanol fixation, whereas PF fixation before methanol permeabilization markedly reduced this loss. For studies on the intracellular localization of soluble or unknown types of antigen, the authors discourage the use of acetone and methanol as single fixatives.

Acetic acid dehydration by pervaporation

Abstract: In this study polyvinyl alcohol (PVA) was modified with two different agents — glutaraldehyde and formaldehyde — by a method called crosslinking and the membranes produced were used to separate mixtures of acetic acid and water. The effect of type of crosslinking agent, feed composition and feed temperature on the pervaporation characteristics were investigated.

Enhanced resolution of membranes in cultured cells by cryoimmobilization and freeze-substitution.

Abstract: Investigations of cellular processes demand immediate arresting of the process at any given time and excellent retention of cellular material and excellent visibility of membranes. To achieve this goal we used cryofixation to arrest cellular processes instantly and tested diverse freeze-substitution protocols. Madin-Darby kidney cells and Vero cells were grown on carbon-coated sapphire disks. For cryofixation the sapphire disks covered with a cell monolayer were injected with the aid of a guillotine into liquid propane or ethane or a mixture of both cooled by liquid nitrogen. Freezing of the cryogen was prevented by using a partially insulated cylinder and by vigorous stirring that results in a substantial decrement of the freezing point of the cryogen. Cell monolayers can be cryofixed successfully using the guillotine in a safety hood at ambient temperature and humidity or at 37°C and 45% humidity. The freezing unit can also be placed in a laminar flow for working under biohazard conditions. For visualizing cell membranes at high contrast and high resolution, cells were substituted in the presence of various concentrations of glutaraldehyde and osmium tetroxide and the temperature was raised to diverse final temperatures. Substitution for 4 hours at −90°C in anhydrous acetone containing 0.25% anhydrous glutaraldehyde and 0.5% osmium tetroxide followed by a temperature rise of 5°C/hour to 0°C and final incubation for 1 hour at 0°C resulted in high contrast and excellent visibility of subcellular components at the level of the membrane bilayer. The high spatial and temporal resolution makes this methodology an excellent tool for studying cell membrane-bound processes, such as virus-cell interactions. Microsc. Res. Tech. 53:313–321, 2001. © 2001 Wiley-Liss, Inc.

Pigeonpea (Cajanus cajan L.) urease immobilized on glutaraldehyde-activated chitosan beads and its analytical applications.

Abstract: Urease from pigeonpea (Cajanus cajan L.) was covalently linked to crab shell chitosan beads using glutaraldehyde. The optimum immobilization (64% activity) was observed at 4°C, with a protein concentration of 0.24 mg/bead and 3% glutaraldehyde. The immobilized enzyme stored in 0.05 M Trisacetate buffer, pH 7.3, at 4°C had a t 1/2 of 110 d. There was practically no leaching of enzyme (<3%) from the immobilized beads in 30 d. The immobilized urease was used 10 times at an interval of 24 h between each use with 80% residual activity at the end of the period. The chitosan-immobilized urease showed a significantly higher Michaelis constant (8.3 mM) compared to that of the soluble urease (3.0 mM). Its apparent optimum pH also shifted from 7.3 to 8.5. Immobilized urease showed an optimal temperature of 77°C, compared with 47°C for the soluble urease. Time-dependent kinetics of the thermal denaturation of immobilized urease was studied and found to be monophasic in nature compared to biphasic in nature for soluble enzyme. This immobilized urease was used to analyze blood urea of some of the clinical samples from the clinical pathology laboratories. The results compared favorably with those obtained by the various chemical/biochemical methods employed in the clinical pathology laboratories. A column packed with immobilized urease beads was also prepared in a syringe for the regular and continuous monitoring of serum urea concentrations.

Detection of nitric oxide in the guinea pig inner ear, using a combination of aldehyde fixative and 4,5-diaminofluorescein diacetate.

Abstract: Localization of nitric oxide (NO) production sites in the inner ear of the guinea pig was investigated using a combination of glutaraldehyde fixative and a new fluorescence NO indicator. 4,5-diaminofluorescein diacetate (DAF-2DA). The cochlea and vestibular end organs were examined to locate NO production sites. The fluorescence persisted after glutaraldehyde fixation and embedding with water-soluble resin. NO production in the cochlea was observed in the outer and inner hair cells, nerve endings, nerve fibers and supporting cells of the organ of Corti, stria vascularis, spiral ligament, ganglion cells, etc. In the vestibular end organs, both type I and type II sensory cells, nerve fibers, blood vessels and dark cells displayed fluorescence. This localization was exactly identical to that of NO synthase. Thus, detection of intracellular NO production by using a combination of glutaraldehyde fixation and DAF-2DA is useful for examining the function of NO in cells, both in situ and in vivo.

Diffusional properties of chitosan hydrogel membranes

Abstract: Chitosan membranes were prepared by a solvent evaporation technique, followed by crosslinking with glutaraldehyde and coating with BSA. The effects of crosslinking and BSA coating on the pore structure of such prepared hydrogel chitosan membranes were determined. The diffusion rates of 12 non-electrolytes ranging in molecular radius between 2.5 and 14 A through the membranes were measured, and the results were interpreted in terms of the capillary pore model and free volume model of solute diffusional transport through hydrogel membranes. Glutaraldehyde crosslinking was found to reduce the membrane water content and consequently the membrane pore size and surface porosity, whereas further BSA coating brought about the opposite effect. The latter effect lessened with an increase in glutaraldehyde pretreatment of the membranes. The optimal chitosan membrane preparation, compromising between the solute flux and membrane stability and durability was obtained when the membranes were crosslinked with glutaraldehyde at concentrations between 0.01 and 0.1% (w/w). The knowledge of transport properties and of physical strength of the membranes is of importance for the development of chitosan-based controlled release systems. © 2001 Society of Chemical Industry

A New Method of Gel-Coating Polyethyleneimine (PEI) on Organic Resin Beads. High Capacity and Fast Kinetics of PEI Gel-Coated on Polystyrene

Abstract: A new process has been developed for gel-coating a high-capacity weak-base resin, polyethyleneimine (PEI), on an inert organic support, polystyrene (PS), used as macroporous spherical beads. The process produces a thin and firm coating of PEI, cross-linked with glutaraldehyde and chemically bonded to the PS surface through carboxylic acid groups, created a priori by exposure to a chromic acid solution in glacial acetic acid for 3 h at the reflux temperature. Designated as OPS···[PEI.XG], the spherical gel-coated beads afford nearly full attainment of the theoretical proton capacity of the coated resin and exhibit significantly faster attainment of equilibrium sorption, compared to a conventional bead-form ion exchanger. Ascorbic acid and UO2SO4 have been used as test sorbates for comparing the performance of OPS···[PEI.XG] with that of a commercial weak-base resin poly(4-vinylpyridine) (PVP). In an ascorbic acid substrate solution, the gel-coat layer of OPS···[PEI.XG] exhibits a sorption capacity of 12 mm...