Showing papers on "Glutaraldehyde published in 1989"

Synthesis of Gelatin Microspheres Containing Interferon

Abstract: Gelatin microspheres with a diameter less than 2 microns were synthesized by means of cross-linking with glutaraldehyde. When the microspheres were subjected to degradation in phosphate-buffered saline solution containing collagenase, the digestion of microspheres was found to decrease with increasing cross-linking. Interferon was incorporated in the microspheres at a high trapping efficiency, and the rate of interferon release from the microspheres was regulated by the extent of cross-linking with glutaraldehyde. Gelatin microspheres incorporating interferon-alpha were readily phagocytosed by macrophages, regardless of the extent of cross-linking, and the phagocytosed microspheres were observed to be degraded gradually in the interior of macrophages, resulting in the slow release of the incorporated interferon in the cells.

Chitosan gels, 3. The formation of gels by reaction of chitosan with glutaraldehyde

Abstract: The effects of several variables on the gelation behaviour of the chitosan/glutaraldehyde system have been studied. The rate of gelation is increased by increase in concentration of either chitosan or glutaraldehyde, or by an increase in temperature, and reduced by an increase in the concentration of acetic acid. Addition of a number of neutral electrolytes also causes an increase in the rate of gelation, the increase being larger the greater the activity coefficient of the electrolyte. UV/visible and NMR spectra of glutaraldehyde, acetaldehyde and crotonaldehyde, together with those of their 2,4-dinitrophenylhydrazine derivatives, indicate that only a very small proportion (<0,15%) of the aldehyde groups have undergone an aldol condensation reaction leading to α,β-unsaturated aldehyde groups. This, together with other evidence, suggests that the cross-linking mechanism involves formation of Schiff's base structures rather than Michael-type adducts as previously postulated.

Chemical inactivation of HIV on surfaces.

Abstract: To assess whether alcohol and glutaraldehyde are effective disinfectants against dried HIV the virucidal effects of 70% alcohol (ethanol and industrial methylated spirit) and 1% and 2% alkaline glutaraldehyde were tested against cell associated and cell free HIV dried on to a surface. Virus stock (100 microliters) or 10,000 cultured C8166 T lymphocytes infected with HIV were dried onto sterile coverslips and immersed in 2% and 1% alkaline glutaraldehyde and 70% ethanol for 30 seconds and one, two, four, and 10 minutes, there being an additional time point of 20 minutes for cell free virus disinfected with 70% industrial methylated spirit. In addition, virus stock in neat serum was tested with 1% and 2% alkaline glutaraldehyde to see whether the fixative properties of glutaraldehyde impair its virucidal properties. Virus activity after disinfection was tested by incubating the coverslips (cell associated virus) or the coverslips and sonicated cell free virus with C8166 T lymphocytes. The lymphocytes were examined for the formation of syncytia and HIV antigens were assayed in the culture fluid. Both 2% and 1% alkaline glutaraldehyde inactivated cell free HIV within one minute; 2% alkaline glutaraldehyde also inactivated cell free virus in serum within two minutes, but a 1% solution was ineffective after 15 minutes' immersion. Cell associated HIV was inactivated by 2% alkaline glutaraldehyde within two minutes. Seventy per cent industrial methylated spirit failed to inactivate cell free and cell associated HIV within 20 and 15 minutes, respectively, and 70% ethanol did not inactivate cell free virus within 10 minutes. Seventy per cent industrial methylated spirit and ethanol are not suitable for surface disinfection of HIV. Fresh 2% solutions of alkaline glutaraldehyde are effective, but care should be taken that they are not too dilute or have not become stale when used for disinfecting HIV associated with organic matter.

The effect of glutaraldehyde base disinfectants on denture base resins.

Abstract: The effect of two alkaline glutaraldehyde base disinfectants on a heat-cured denture base resin was evaluated by the flexural strength, the repair flexural strength, and the surface morphology of the material that had been immersed up to 12 hours in the disinfecting solutions The flexural strength of the material was not significantly affected by either disinfectant The disinfectant with phenolic buffer caused surface pitting of the material after 10 minutes of immersion, and softening and swelling of the surface after 2 hours of immersion No apparent surface change was observed with the regular alkaline formulation, however Between the two repair resins, the autopolymerized resin yielded greater repair flexural strength than the light-cured repair resin However, the repair flexural strength of autopolymerized resin seemed to be influenced by either disinfecting solution whereas the light-cured repair resin was not affected

Effect of Polymeric Network Structure on Drug Release from Cross-Linked Poly(Vinyl Alcohol) Micromatrices

Abstract: Three types of poly(vinyl alcohol) were cross-linked by glutaraldehyde to form water-swellable materials possessing a three-dimensional, molecular network. Proxyphylline and theophylline were incorporated into the polymer networks during the cross-linking reaction. The firm hydrogels formed were dried and reduced to a particle size of 400-630 microns. The molecular structure of the gels was characterized by equilibrium swelling measurements which allowed the determination of the average distance between two cross-links and, hence, the macromolecular mesh size. The sulfate and glutaraldehyde residues contained in the purified and nonpurified cross-linked polymers were analyzed, and methods for their elimination and inactivation were developed. Drug release from the highly cross-linked gels could be controlled over more than 12 hr, as the diffusion process in these very dense macromolecular networks is rather slow. The extent of branching and entanglement of the polymeric chains appeared to have an important effect. In addition, the release rate was influenced greatly by the amount and, to a lesser extent, by the type of drug in the network.

Gelatin with hydrophilic/hydrophobic grafts and glutaraldehyde crosslinks†

Abstract: Acrylic monomers were graft copolymerized onto gelatin chains using potassium persulfate in aqueous medium. The graft copolymers were then treated with glutaraldehyde to establish crosslinks between gelatin macromolecules. This yielded a rigid water insoluble protein network sporting grafted chains at random. The chemistry of the acrylic monomer decided the hydrophilic/hydrophobic properties of the ultimate product. This paper describes the preparation and properties of such grafted, crosslinked gelatins.

Improved preservation of bacterila capsule for electron microscopy

Abstract: Conventional fixation for thin-section electron microscopy is insufficient to preserve bacterial capsular material, a highly hydrated structure which collapses during dehydration and embedding. Boyles et al. (1984, 1985) have recently introduced a modified aldehyde fixation process in which the addition of a primary amine was found to improve the preservation of actin filaments, the basement membrane material and cell surface glycocalyx of mouse tissues. To the best of our knowledge, the application of diamines to the analysis of bacterial ultrastructure has not been reported in the literature. In the present study, excellent preservation of bacterial capsular material was seen when a diamine (lysine) was used together with glutaraldehyde in conventional embedding procedures.

Antigen preservation tests for immunocytochemical detection of cytoskeletal proteins: influence of aldehyde fixatives.

Abstract: The effects of aldehyde fixatives on immunochemical detection of cytoskeletal proteins were demonstrated by applying several quantitative assays to evaluate antigen conservation. Immunologically detectable brain spectrin (240/235) was measured by dot-immunobinding and quantitative immunodot assay using a polyclonal antibody. Paraformaldehyde fixation led to a 43-66% reduction in brain spectrin (240/235) immunodetection, and increasing glutaraldehyde concentrations decreased the immunological detection even more. Quantitative cryosection immunoassay and immunocytochemical localization confirmed the aldehyde sensitivity of brain spectrin (240/235). Brain spectrin (240/235) immunoreactivity decreased with increasing protein crosslinking and was dependent on glutaraldehyde concentration and post-fixation period. The assays were also used to test for conservation of antigenicity of neurofilament proteins by two monoclonal antibodies. Neurofilament detection was abolished in brain tissue after aldehyde fixation. The described methods allow screening within 24 hr of many fixation conditions by use of purified proteins as well as brain tissue samples, and allow an estimate of fixative influence on the conservation of protein antigenicity.

Oily, free-flowing, microcapsules

Abstract: This disclosure is directed to the preparation of oily microcapsules which can be easily tray dried to a free flowing product without requiring special drying equipment. These microcapsules have a cell wall material having a first cell wall of gelatin/carboxymethylcellulose (CMC) which is prehardened (cross-linked) with a material selected from the group consisting of formaldehyde, glyoxal and glutaraldehyde to which there is grafted formaldehyde and urea. The predominant portion, viz., approximately 95% by wt. of these microcapsules have a particle size less than 1500 microns and more characteristically have a particle size ranging from about 100 to about 400 microns (microcapsular diameter). These microcapsules contain less than approximately 3 wt. % free oil and more characteristically less than about 1 wt. % free oil (non-microencapsulated oil) and have less free (unreacted) formaldehyde, which can be extracted with water, than do prior art microencapsulated oily materials. The microcapsules of this invention are granular and free-flowing when dried.

An evaluation of purified reconstituted type 1 collagen fibers.

Abstract: Collagen fibers composed of type I collagen molecules were studied for biocompatibility and mechanical properties. These fibers were crosslinked using two different processes: 1) glutaraldehyde, 2) dehydration followed by exposure to cyanamide (DHT/C); the latter method produces only urea as a by-product of the crosslinking process and is postulated to be more biocompatible. An in vitro model using rat tendon fibroblasts growing on individual fibers was used to evaluate outgrowth rates, cell/fiber interactions, and cell morphology. These studies showed an advantage with DHT/C crosslinking, relative to glutaraldehyde crosslinking, in promoting fibroblast growth. In vivo intramuscular implantation in rats showed excellent biocompatibility for both kinds of collagen implants. In addition, aligned ingrowth into the implant from the medial collateral ligament when applied in that location was demonstrated. Mechanical testing demonstrated the higher strength of dry fibers; however, upon hydration, there was a marked decrease in stress to failure. This reduction in strength was due principally to an increase in cross section due to swelling. These collagen fibers appear to be very biocompatible even in the presence of low concentrations of glutaraldehyde. They promote fibrous aligned ingrowth in a setting of ligament healing. Thus, they represent a strong candidate as a scaffold ligament or tendon prosthesis if crosslink density can be increased.

Potency of microwave irradiation during fixation for electron microscopy.

Abstract: Liver, skeletal muscle, peripheral nerves, pancreas, thyroid and adrenal cortex were prepared for electron microscopy employing microwave energy either during prefixation with glutaraldehyde or instead of prefixation. Microwave irradiation in the presence of glutaraldehyde in Na/K-phosphate or Na-cacodylate containing CaCl2 and MgCl2 led to distinct appearance of membranes, mainly plasma membrane, and membranes of SER, Golgi complex and mitochondria in liver, pancreas and muscle. The area of high quality fixation, however, was limited to the periphery of samples. On the other hand, SER was dilated in cells of the adrenal cortex, and RER markedly vacuolated in thyroid follicular cells. Microwave irradiation in the presence of Na/K-phosphate and subsequent osmication resulted in preservation of the ultrastructure in similar quality as was obtained by osmication without previous immersion in glutaraldehyde. However, the preservation of SER and Golgi complex in liver and pancreas, and of mitochondria in muscle was greatly improved. Small myelin sheaths remained intact whereas large ones showed focal disintegration. We consider that enhancement of fixation by microwave energy may greatly improve preservation of membranes in some tissues. Successful fixation depends on the use of glutaraldehyde during microwave irradiation, the type of buffer, the addition of ions to increase stabilization, the exposure time to heat, and on postosmication.

Immobilization of endo-polygalacturonase from Aspergillus niger on various types of macromolecular supports.

Abstract: Endo-polygalacturonase (endo-PG) was immobilized on a wide range of natural and synthetic macromolecular supports and their modified derivatives representing many chemical classes, including esters, amides, phenols, alkyl- and arylamines, and carboxyl derivatives. The immobilization entailed methods of adsorption alone as well as covalent bond formation using glutaraldehyde or carbodiimide or via the diazo-coupling reaction. The most promising system proved to be immobilization on trimalehylchitosan (TMC) via adsorption followed by treatment with glutaraldehyde (GA). The binding capacity of the support is on the order of 13,000 IU/g, half of which is active. Various properties of immobilized endo-PG were evaluated. The optimum pH of the enzyme shifted to the alkaline side. The relative catalytic activity was considerably high even at room temperature and remained so above 70 degrees C. The thermal stability at pH 3-4 was notably improved by immobilization, the half-time doubling. Finally, the apparent K(m) was greater for immobilized endo-PG than for native enzyme, while the V(max) was smaller for the immobilized enzyme.

Small, oily, free-flowing, silky-smooth, talc-like, dry microcapsules and aqueous formulations containing them

Abstract: This disclosure is directed to the preparation of dry microencapsulated product, having an oily core material with microcapsule cell wall materials having a first cell wall of gelatin/polyvinyl methylether maleic anhydride copolymer (PVMMA)/carboxymethylcellulose (CMC) which is prehardened (cross-linked) with a material selected from the group consisting of formaldehyde, glyoxal and glutaraldehyde to which there is grafted formaldehyde and resorcinol which is then crosslinked with formaldehyde and urea, and aqueous formulations containing them. Approximately 97% of these microcapsules have a size less than 100 and more characteristically having a particle size peak distribution of 30 to 40 microns (microcapsular diameter). These microcapsules contain less than approximately 3 wt. % free oil and more characteristically less than about 1 wt. % free oil (non-micro-encapsulated oil) and have less free (unreacted) formaldehyde which can be extracted with water, than do prior art microencapsulated emollient materials. The dry microcapsules of this invention are free-flowing and have a silky-smooth feeling similar to that of talcum powder.

Sulfide and glutaraldehyde resistant strains of Thiobacillus denitrificans

Abstract: Isolation and characterization of strains of T. denitrificans which are tolerant of both inorganic sulfide and glutaraldehyde. Effect of sulfide on the growth of wild type and strain F, on thiosulfate in liquid culture. Effect of glutaraldehyde on the growth of strain F

Contact hypersensitivity response to glutaraldehyde in guinea pigs and mice.

Abstract: Glutaraldehyde has a wide spectrum of uses which can result in dermal contact with the agent. The low number of reports of hypersensitive reactions to glutaraldehyde indicates a low incidence of sensitization. This paper describes the contact hypersensitivity response to glutaraldehyde in the guinea pig and the mouse. Female albino Hartley strain guinea pigs and female B6C3F1 mice were sensitized with 0.3, 1.0 and 3.0% glutaraldehyde and challenged with 10% glutaraldehyde. Doses of glutaraldehyde were selected from assays for primary irritancy. Guinea pigs received 100 microliters by direct dermal application, for 14 consecutive days, and mice received 20 microliters by direct dermal application, for 5 or 14 consecutive days, to sites prepared by shaving and dermabrading. Rest periods were 7 or 14 days for guinea pigs and 4 or 7 days for mice. Measurement of the contact hypersensitivity response in guinea pigs was both visual evaluation (scoring) at 24 and 48 hours following challenge and radioisotopic assay at 48 hours, and in mice by radioisotopic assay 48 hours after challenge. Both guinea pigs and mice demonstrated dose-dependent contact hypersensitivity responses to glutaraldehyde. The radioisotopic assay appeared to be more sensitive than visual evaluation in detecting contact allergic hypersensitivity to glutaraldehyde.

Development of effective cross-linking method for bioactive substance--enzyme immobilization using glutaraldehyde oligomers.

Abstract: When a 10% aqueous solution of glutaraldehyde (GA) was alkalized to pH 8.5 in borate buffer solution and heated at 60°C, the ultraviolet spectrum of GA solution showed two distinct absorption maxima. The one at 280 nm with a weak absorbance ascribable to the C=O bond in the aldehyde group shifted to near 300 nm after 50 min with a slight increase in its intensity. Another maximum at 235 nm with a strong absorbance was ascribable to the C=C bond of the α, β-unsaturated aldehyde group which was formed by aldol condensation reaction of GA monomer, and its absorbance increased markedly with increasing reaction time. The high performance liquid chromatography (HPLC) analysis with detection at 235 nm indicated that several GA oligomers were formed by the alkali treatment ad their concentrations increased. The cross-linking ability of these oligomers was examined by immobilizing enzymes (alcohol dehydrogenase (ADH), glutamate dehydrogenase (GLDH)) to an aminated polymer gel matrix by reaction with the treated GA solution. The enzyme activities increased with increasing concentration of GA oligomers. Then, the GA oligomers were isolated and used as the cross-linking agent. The activities of ADH and GLDH were 4-fold and 13-fold higher, respectively, than those obtained by using untreated GA solution, while the total amounts of immobilized enzymes were almost unchanged. These results suggest that GA oligomers may act as cross-linkers in a manner different from the generally accepted Schiff base formation reaction; a possible mechanism may involve addition reaction of an amino group to the double bond in the aldol condensate of GA. This reaction, if it does occur, seems to be effective for the enhancement of the immobilized enzyme activity.

Glutaraldehyde: its uptake by sporing and non-sporing bacteria, rubber, plastic and an endoscope.

Abstract: Uptake of glutaraldehyde to bacterial spores, germinating and outgrowing spores, vegetative cells (sporing and non-sporing bacteria), various types of rubber, plastic and an endoscope was investigated. Escherichia coli NCTC 10418 exhibited greatest uptake, followed by Bacillus subtilis NCTC 8236 vegetative cells and Staphylococcus aureus NCTC 6571. Germinated and outgrowing B. subtilis spores adsorbed more glutaraldehyde than resting spores, but less than vegetative cells. Low concentrations of alkaline and acid glutaraldehyde increased the surface hydrophobicity and inhibited the germination of bacterial spores, the alkaline solution to a greater extent in both cases. Rubbers exhibited varying degrees of uptake and are listed in decreasing order of uptake: red rubber, fluorinated rubber (Vinescol), silicone rubber (Silescol), butyl rubber (Butyl XX). Polypropylene, the only plastic examined, was found not to adsorb any glutaraldehyde. The endoscope adsorbed more glutaraldehyde (per gram) than fluorinated rubber but less than red rubber. No damage was observed.

Novel preparation of zein microspheres conjugated with PS-K available for cancer immunotherapy.

Abstract: Microspheres which entrapped PS-K were prepared using Zein as a carrier matrix by a one-step or two-step process in dimethyl sulfoxide-H2O media. Microspheres prepared by the latter process provided satisfactory recovery and uptake of PS-K. Use of a catalytic amount of dl-camphorsulfonic acid, glutaraldehyde and rapid addition of aqueous solution of polyvinylpyrrolidone into the reaction media are crucial for the preparation of fine and mono-dispersed microspheres. The release rate of PS-K could be controlled by altering the ratio of PS-K to Zein and the conditions of the medium. In the presence of actinase E, drug release was considerably increased to 70-80% after 24 h incubation. Sonication of the aggregated microspheres readily yielded a mono-dispersed preparation with a particle diameter of less than 1 μm, which would be a suitable size for phagocytosis by macrophages.

Degradation of limonin by entrappedRhodococcusfascians cells

Abstract: Limonin degradingRhodococcusfascians was immobilized by entrapment in alginate, k-carrageenan, agarose and polyacrylamide gels. Except this latter, gels were used both with and without polyethyleneimine treatment followed by glutaraldehyde crosslinking. Coated derivatives showed lower activity and stability and higher diffusional limitations that uncoated ones. Immobilized cells in k-carrageenan gave, globally, the best results.

Alkali-induced revival of Bacillus spores after inactivation by glutaraldehyde.

Abstract: Spores of Bacillus subtilis 168 were apparently fully inactivated by exposure to 2% (w/v) glutaraldehyde for 20 h but a few spores could be revived by further treatment with 10–100 mM NaOH. A similar effect was found with spores from a range of Bacillus species. A minimum concentration of 5% (w/v) glutaraldehyde was required to prevent the alkali-induced reactivation. The implications of these results for the use of glutaraldehyde as a sporidical agent are discussed.

Extraction of carbon 14-labeled compounds from plant tissue during processing for electron microscopy.

Abstract: Loss of 14C-labeled compounds from bean leaf tissue was monitored during all the stages of routine specimen preparation. No significant differences in extraction were associated with the use of acetone, ethanol, or dioxane as dehydration fluids. Fixation at low temperature increased the loss of label. Prolonged fixation in glutaraldehyde increased the loss, but fixation in osmium solutions for periods as long as 4 hr had no influence on extraction. Buffer rinses and dehydration fluids caused appreciable amounts of label to be extracted. The use of propylene oxide as transition fluid resulted in low extraction. Some embedding media caused the loss of small amounts of labeled compounds, but one of the media tested (LR-white) extracted significant amounts of label.

Formocresol and glutaraldehyde pulpotomies in primary teeth.

Abstract: The purpose of the present study was to compare clinically and radiologically the effects of formocresol and glutaraldehyde as a medicament in pulpotomized carious exposed vital human primary molars. In formocresol group 90% clinical and radiological success rate and in glutaraldehyde group 100% clinical and radiological success rate was observed. Thus it was concluded that glutaraldehyde is better fixative and less toxic agent than formocresol.

Possible mechanisms for the revival of glutaraldehyde-treated spores of Bacillus subtilis NCTC 8236.

Abstract: Spores of Bacillus subtilis NCTC 8236 were exposed to 2% alkaline glutaraldehyde and subsequently subjected to various treatments in an attempt to revive injured spores. Treatment with alkali (sodium or potassium hydroxide or, to a lesser extent, sodium bicarbonate) proved to be most successful. Some revival was achieved after thermal treatment. No revival was obtained with lysozyme or with various types of coat-removing agents. Experiments designed to distinguish between germination and outgrowth in the revival process established that sodium hydroxide (optimum concentration, 20 mmol/l) added to glutaraldehyde-treated spores increased the potential for germination. In contrast, spores which had been allowed to germinate before exposure to low concentrations of glutaraldehyde and then to sodium hydroxide were inhibited at the outgrowth phase to a much greater extent than germinated spores treated with the dialdehyde without subsequent alkali exposure. The results overall are discussed in terms of the possible mechanism and site of action of glutaraldehyde and the practical implications and significance of its use as a sporicide.

Virucidal low toxicity compositions

Abstract: Very potent, stable, odorless, and phenol-free virucidal solutions are active at high dilution when used for surface decontamination of animate and inanimate objects. The virucidal compositions described are efficacious in a matter of minutes against both the lipophilic and the more resistant hydrophilic viruses. The three active ingredients in these virucidal compositions are the glutaraldehyde monomer in equilibrium with its hydrates and polymers, hydrogen-bonded glycol molecules to eliminate aldehydes odor, and an anionic surfactant of the alkyl sulfate, alkyl sulfonate, alcohol sulfate or alkyl aryl sulfonate type. A preferred anionic surfactant would be the Sodium Dodecyl Sulfate (SDS), which exhibits strong cidal synergism against the Herpes Simplex Virus type 1 when mixed at a concentration as low as 0.0005% in diluted glutaraldehyde aqueous solutions (0.0025%). Improved virucidal killing at higher dilutions of the same formula were observed with the more resistant Coxsackie B viruses. Because of the low concentration of active ingredients, these solutions exhibit a very low toxicity, making them suitable for topical applications as antiseptics.