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PubMed1994

Polyacrylamides bearing pendant alpha-sialoside groups strongly inhibit agglutination of erythrocytes by influenza A virus: multivalency and steric stabilization of particulate biological systems.

An alpha-sialoside linked to acrylamide by a short connector (5-acetamido-2-O-(N-acryloyl-8-amino-5-oxaoctyl)-2,6-anhydro-3,5-d ideoxy-D-galacto-alpha-nonulopyranosonoic acid, 1) was prepared. Compound 1 formed high molecular weight copolymers with acrylamide, derivatives of acrylamide, and/or vinylpyrrolidone upon photochemically-initiated free radical polymerization. Those copolymers for which the substituents on the acrylamido nitrogen were small inhibited the agglutination of chicken erythrocytes induced by influenza virus (X-31 (H3N2); a recombinant strain of A/Aichi/2/68 (H3N2) and A/Puerto Rico/8/34 grown in chicken eggs). The inhibitory power of the polymers depended strongly on the conditions of polymerization and the sialic acid content of the polymer. The strongest inhibitors were copolymers (poly(1-co-acrylamide)) formed from mixtures of monomer containing [1]/([1] + [acrylamide]) approximately 0.2-0.7; these copolymers inhibited hemagglutination 10(4)-10(5) times more strongly than did similar concentrations of alpha-methyl sialoside (calculated on the basis of the total concentration of individual sialic acid groups in the solution, whether attached to polymer or present as monomers). Samples polymerized in the presence of low concentrations of cross-linking reagents (bis(acrylamido)methane, BIS, and 2,2'-bis(acrylamido)ethyl disulfide, BAC) also showed increased inhibition (10-10(3)-fold relative to monomers), but their use was limited by their poor solubility. Sterically demanding substituents on any position of the acrylamide component (substituents attached to the vinyl group or N-alkyl groups that are larger than hydroxyethyl) reduced the inhibitory power of the polymer. A 1H NMR assay and a fluorescence depolarization assay showed that poly(1-co-acrylamide) bound to a solubilized trimeric form of the viral receptor for sialic acid (bromelain cleaved hemagglutinin, BHA), less tightly than 1, on a per sialic acid basis. A similar result was also obtained with a model system comprising lactic dehydrogenase (a tetramer) and polymeric derivatives of oxamic acid: that is, poly((28, 29, 30, or 31)-co-acrylamide) had a higher inhibition constant for tetrameric lactic dehydrogenase than did the corresponding monomers (28, 29, 30, or 31) on a per oxamate basis. Poly(1-co-acrylamide) is, in principle, capable of inhibiting the agglutination of erythrocytes by several mechanisms: (1) entropically enhanced binding of the polymer (acting as a polyvalent inhibitor) to the surface of the virus; (2) steric interference of the approach of the virus to the surface of the erythrocyte by a water-swollen layer of the polymer on the surface of the virus; (3) aggregation of the virus induced by the polymer.(ABSTRACT TRUNCATED AT 400 WORDS)

Acrylic Resins↗
PubMed1990

Modulation of keratin intermediate filament distribution in vivo by induced changes in cyclic AMP-dependent phosphorylation.

Treatment of PtK1 cells with 5 mM acrylamide for 4 hr induces reversible dephosphorylation of keratin in concert with reversible aggregation of intermediate filaments (Eckert and Yeagle, Cell Motil. Cytoskeleton 11:24-30, 1988). We have examined this phenomenon by 1) in vitro phosphorylation of isolated PtK1 keratin filaments and 2) combined treatments of PtK1 cells with both acrylamide and agents which elevate intracellular cAMP levels. PtK1 keratins were incubated in gamma-32P-ATP in the presence or absence of cAMP-dependent kinase (A-kinase) and cAMP. Levels of phosphorylation were analyzed by electrophoresis and autoradiography. Phosphorylation of keratin polypeptides (56 kD, 53 kD, 45 kD, 40 kD) occurred without added kinase, suggesting the presence of an endogenous kinase which remains with intermediate filaments in residues of Triton X-100 extracted cells. Phosphorylation levels were increased by A-kinase but not by cAMP alone, indicating the presence of cAMP-dependent phosphorylation sites in addition to sites phosphorylated by the endogenous kinase. To study the possible role of cAMP-dependent phosphorylation in acrylamide-induced aggregation of keratin filaments, we treated cells with acrylamide in the presence of 8-bromo-cAMP (brcAMP), pertussis toxin (PT), isobutylmethylxanthine (IBMX), or forskolin, which increase intracellular cAMP levels. The distribution and phosphorylation levels of keratin filaments, as well as intracellular cAMP levels, were determined for each of these treatments. In addition to aggregation and dephosphorylation of keratin filaments reported previously, treatment of cells with acrylamide alone also results in reduced levels of intracellular cAMP. 8-bromo-cAMP, IBMX, and forskolin prevent acrylamide-induced aggregation of keratin filaments and result in both normal levels of keratin phosphorylation and normal intracellular cAMP levels. PT was apparently ineffective. These observations suggest that 1) PtK1 keratins are phosphorylated by cAMP-dependent kinase and an endogenous, cAMP-independent kinase and 2) alteration of levels of cAMP-dependent phosphorylation may be involved in aggregation of keratin filaments in response to acrylamide.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Accessibilities of the sulfhydryl groups of native and photooxidized lens crystallins: a fluorescence lifetime and quenching study.

Fluorescence lifetime and acrylamide quenching studies on the N-(iodoacetyl)-N'-(5-sulfo-1-naphthyl)ethylenediamine (1,5-IAEDANS)-labeled sulfhydryl groups of bovine lens alpha-, beta H-, and gamma-crystallins were carried out to characterize the microenvironment of the sulfhydryls and changes produced by singlet oxygen mediated photooxidation. For the untreated proteins, the lifetimes of the major decay component of the fluorescence-labeled crystallins were 15.2, 14.4, and 13.0 ns, and the quenching rate constant, kq, values were 16.6 x 10(7), 26.9 x 10(7), and 32.7 x 10(7) M-1 s-1 for alpha-, beta H-, and gamma-crystallins, respectively. The results indicate that as the polarity of the sulfhydryl site increased (i.e., its lifetime decreased), its accessibility to collisional quenching by acrylamide also increased. The minor decay component of the fluorescence label was not significantly quenched by acrylamide for all three classes of crystallins. When the proteins were irradiated in the presence of methylene blue, in a system generating singlet oxygen, the kq value for acrylamide quenching of the major decay component of alpha-crystallin decreased to zero, while its lifetime decreased to 6 ns. Neither the lifetime nor the kq of alpha-crystallin recovered completely in the presence of the singlet oxygen quencher sodium azide. Light-induced binding of the photosensitizer methylene blue to the crystallins was observed by absorption spectroscopy. The bound photosensitizer partially quenches the fluorescence lifetime of the N-acetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine (AEDANS) label in irradiated alpha-crystallin. Further decrease in the lifetime occurs as a result of the singlet oxygen mediated conformational change. The results suggest that the fluorescence lifetime of the AEDANS is fully quenched in the irradiated alpha-crystallin and there is no further quenching by acrylamide. An increase in the fraction of the minor component of beta H-crystallin which was inaccessible to acrylamide quenching was observed after irradiation. There was no effect of irradiation on the kq for acrylamide quenching of the major component of the decay of AEDANS bound to beta H- or gamma-crystallins. Static quenching was found to contribute significantly to the steady-state quenching plots of the polar sulfhydryl sites of irradiated alpha-crystallin and of untreated and irradiated beta H- and gamma-crystallins, but it had no detectable role in the case of untreated alpha-crystallin. Fluorescence anisotropy of the AEDANS label bound to the crystallins was higher in the irradiated crystallins as compared with the controls.

Acrylamide↗
PubMed1983

NMR analyses of the cold cataract. II. Studies on protein solutions.

Water proton relaxation studies were performed on total soluble protein (TSP) solutions and individual alpha-, beta-, and gamma-crystallin fractions derived from weanling rat lenses, 16 month, and 60- to 70-year-old normal human lenses. The effects of perturbants (temperature and acrylamide) were monitored in order to delineate further the mechanisms involved in the generation of the cold cataract phenomenon (in young lenses) and the role of acrylamide and age in preventing this phenomenon. The data demonstrate a relationship between the relative concentration of the alpha-, beta-, and gamma-crystallin fractions within the lens and the cold cataract phenomenon. It is possible that cross-linking between acrylamide and the gamma-crystallins within the lens alters one or more of the intracytoplasmic protein-water phases. The gamma-crystallin solution showed greater than 35% increase in T2 when 1% acrylamide was added; the young TSP solution T2 increased by approximately 20%. However none of the T2 values for the alpha, beta and old TSP solutions changed significantly when acrylamide was added. The unique response of gamma-crystallin in these experiments suggests a significant role for this protein fraction in the phenomenon associated with cold cataractogenesis. Our data indicate that most of the UVA radiation-induced acrylamide binding occurred with the gamma-crystallins within the lens. We have also noted that only the gamma-crystallin and the young lens TSP solutions become opaque at 4 C while the alpha, beta and "old" TSP solutions remain clear at this temperature. It is suggested that acrylamide exerts its role by cross-linking to one or more of the gamma-crystallins, thereby altering the normal protein water relationship and preventing cold opacification.

Acrylamide↗
PubMed1997

Environmental degradation of polyacrylamides. II. Effects of environmental (outdoor) exposure.

The environmental fate of a polyacrylamide thickening agent (PATA), formulated without and with a glyphosate-surfactant herbicide (GH), was examined under various environmental situations: formulation in surface water and ground water, volatility, and soil mobility. Environmental Fate of PATA in Surface Water and Ground Water: PATA was formulated at four concentrations in distilled-deionized water, three surface water samples, and two ground water samples, without and with a GH. Solutions were placed in glass bottles, covered with plastic wrap, and exposed to environmental (outdoor) conditions for 6 weeks. Acrylamide and ammonium concentration, pH, and bacterial and fungal populations were measured weekly. All solutions in this portion of the study had a homogeneous milky appearance but the conclusions of the study were nearly transparent. The results of this study suggest that polyacrylamide can degrade to acrylamide under environmental conditions. Statistically, there was no linear correlation between the various parameters measured. Volatility: PATA was formulated without and with GH. Each solution plus an acrylamide standard (positive control) was placed in a glass beaker and exposed to environmental (outdoor) conditions for 6 days. Acrylamide concentration, ammonium concentration, pH, and solution volume were measured daily. Acrylamide and ammonium concentrations increased during the study in all formulations, except when solutions evaporated to dryness. pH did not change greatly over the course of the study for these samples. Those solutions containing PATA had a homogeneous milky appearance but by the conclusions of the study were nearly transparent. This suggests a physical structural change in the polymer. Soil Mobility: PATA formulated with GH was also applied to soil columns and soil boxes containing sand, Eudora sandy loam, Eudora sandy clay, and Kohola silt loam. Acrylamide could be detected by Day 2 in all soil columns. Acrylamide could not be detected in the runoff of any of the soil boxes.

Acrylamides↗
PubMed1990

Biotin binding changes the conformation and decreases tryptophan accessibility of streptavidin.

Biotin binding reduces the tryptophan fluorescence emissions of streptavidin by 39%, blue shifts the emission peak from 333 to 329 nm, and reduces the bandwidth at half height from 53 to 46 nm. The biotin-induced emission difference spectrum resembles that of a moderately polar tryptophan. Streptavidin fluorescence can be described by two lifetime classes: 2.6 nsec (34%) and 1.3 nsec (66%). With biotin bound, lifetimes are 1.3 nsec (26%) and 0.8 nsec (74%). Biotin binding reduces the average fluorescence lifetime from 1.54 to 0.88 nsec. Biotin does not quench the fluorescence of indoles. The fluorescence changes are consistent with biotin binding causing a conformational change which moves tryptophans into proximity to portions of streptavidin which reduce the quantum yield and lifetimes. Fluorescence quenching by acrylamide revealed two classes of fluorophores. Analysis indicated a shielded component comprising 20-28% of the initial fluorescence with (KSV + V) less than or equal to 0.55 M-1. The more accessible component has a predominance of static quenching. Measurements of fluorescence lifetimes at different acrylamide concentrations confirmed the strong static quenching. Since static quenching could be due to acrylamide binding to streptavidin, a dye displacement assay for acrylamide binding was constructed. Acrylamide does bind to streptavidin (Ka = 5 M-1), and probably binds within the biotin-binding site. In the absence of biotin, none of streptavidin's fluorescence is particularly accessible to iodide. In the presence of biotin, iodide neither quenches fluorescence nor alters emission spectra, and acrylamide access is dramatically reduced. We propose that the three tryptophans which always line the biotin site are sufficiently close to the surface of the binding site to be quenched by bound acrylamide. These tryptophans are shielded from iodide, most probably due to steric or ionic hindrances against diffusion into the binding site. Most of the shielding conferred by biotin binding can be attributed to the direct shielding of these residues and of a fourth tryptophan which moves into the binding site when biotin binds, as shown by X-ray studies (Weber et al., 1989).

Acrylamides↗
PubMed2005

Model and field studies of the degradation of cross-linked polyacrylamide gels used during the revegetation of slate waste.

Cross-linked polyacrylamide gels are increasingly being used in environmental restoration schemes and horticulture as a means of enhancing water supply to plants. However, the environmental impact of cross-linked polyacrylamide gel deployment in soil remains poorly understood. This study assessed the chemical, physical and biological properties of new and field-conditioned cross-linked polyacrylamide gels. Both monomeric acrylamide (11 microg l(-1)) and acrylic acid (285 microg l(-1)) were observed in new gel; however, the levels of monomers in field-conditioned gels (1-6 years old) were very low (acrylamide <1 microg l(-1); acrylic acid <7 microg l(-1)). Generally, freeze-thaw processes and exposure to UV radiation had little effect on gel acrylic acid and acrylamide concentrations. However, elevated temperatures (35 degrees C) caused a significant release of up to 144 mug l(-1) of acrylamide and 453 microg l(-1) of acrylic acid in new gel and up to 25 microg l(-1) of acrylamide and 157 microg l(-1) of acrylic acid in field-conditioned gels. In contrast, gel water holding capacity was highly dependent upon environmental conditions (UV exposure and freeze/thaw cycles produced the greatest loss of water holding in new gels) and gel age. Optical microscopy revealed that after placement in the field the gels became increasingly colonised over time by fungi and bacteria. In enrichment cultures, we were unable, however, to demonstrate microbial growth when cross-linked polyacrylamide was used as the sole nitrogen source. In summary, under a range of conditions cross-linked polyacrylamide did not release acrylamide above legally permitted limits, with the exception of gel subjected to elevated temperatures. However, their capacity for holding water decreased sharply within 18 months. We therefore conclude that cross-linked polyacrylamide placed in soil is relatively stable with respect to the production of potentially toxic acrylamide, a species with a short half-life, which degrades to the much less toxic acrylic acid. However, the loss of water holding capacity raises questions about its long-term effectiveness in land restoration schemes as this is the main reason it is used in this role.

Acrylic Resins↗
PubMed1984

Optimization of polyacrylamide gel electrophoresis conditions used for sequencing mixed oligodeoxyribonucleotides.

We investigated two components of the polyacrylamide gel electrophoresis system used for sequencing DNA to improve the system for sequencing synthesized oligodeoxyribonucleotides containing positions of degeneracy. First, we varied the ratio of methylene-bis-acrylamide (MBA) to acrylamide from that commonly used in DNA sequencing gels (1% MBA:19% acrylamide). A moderate increase in the MBA:acrylamide ratio proves optimal when sequencing is used to confirm that a synthesized fragment contains equivalent stoichiometries of the different nucleotides at a given position of degeneracy. Such information is particularly important if the degenerate oligodeoxyribonucleotide preparation is to be employed as a hybridization probe. A further increase in the MBA:acrylamide ratio (3% MBA:19% acrylamide) produces a gel in which the sequence of an oligodeoxyribonucleotide mixture containing several positions of degeneracy can be read most easily. Increasing the MBA acrylamide ratio suppresses the effect of base composition on electrophoretic mobility of a fragment. Second, we investigated the use of a Tris-citrate buffer system in place of the standard Tris-borate system. We found the Tris-citrate system to be significantly more effective in preventing discontinuities in the banding pattern of the smaller fragments. Finally, we show that high MBA gels are also effective in resolving mixtures of oligoribonucleotides such as those produced by T1 ribonuclease digestion of small RNAs.

Base Sequence↗
PubMed2002

Development and characterization of a vitreous mimicking material for radiation force imaging.

In many medical ultrasound applications tissue-mimicking phantoms are of fundamental importance for the performance of controlled experiments. Traditionally, such phantoms have been constructed using gelatin and agar gels. Although the use of these materials has become standard, few alternative materials have not been fully explored. In this paper, we present a protocol developed in our laboratory that reliably produces very soft, acrylamide-based phantoms that can mimic both acoustical and mechanical characteristics of the vitreous body of the eye. Following the described protocol, a series of phantoms were constructed ranging in acrylamide concentration from 1.60% to 1.70%. Measurements across the series yielded attenuation coefficients of 0.067-0.140 dB/cm/MHz, depending on acrylamide concentration. Speed of sound ranged between 1499 and 1510 m/s, also depending on acrylamide concentration. Published values for the vitreous gel indicate an attenuation of 0.10 dB/cm/MHz and a speed of sound of 1510 m/s, making our phantoms an excellent analog of this tissue. One application of these acrylamide phantoms is to test the efficacy of the Kinetic Acoustic Vitreoretinal Examination (KAVE), a tool developed in our laboratory with the potential to aid in the diagnosis of vitreoretinal disorders. KAVE utilizes acoustic radiation force to generate small, localized displacements within the vitreous-mimicking gel. These localized displacements are quantified to yield maximum displacement, relative elasticity, and relative viscosity images. We present KAVE images of a set of four phantoms with different gel concentrations. Although B-mode and relative viscosity images exhibit no significant differences, maximum displacement, and relative elasticity images clearly differentiate gels of different concentrations. Maximum displacements ranged between 30 and 5 microns, depending on acrylamide concentration. The results presented in this paper show that soft gel phantoms can be produced in a range of elasticities not previously reported, and that these phantoms are useful for testing ultrasound instruments designed for evaluation of the vitreous gel. Furthermore, the use of acrylamide-based gels may also offer a valuable and attractive alternative for many other ultrasound applications.

Acrylic Resins↗
PubMed2000

[Electrophoretic study of albumins and globulins of 4 genotypes of Canavalia ensiformis].

Polyacrylamide gel electrophoresis (PAGE) and PAGE-SDS were used to study seed albumins and globulins of Canavalia ensiformis. In PAGE the concentration of acrylamide used in the upper gel was 4.0% with a pH of 6.7 and in the lower gel 7.5% and 10% of acrylamide were used with a pH of 8.9. In PAGE-SDS the concentration of acrylamide was 4.4% with a pH of 6.8 in the upper gel and 7.5% and 12.6% with a pH of 8.8 in the lower gel. The material used were the Venezuelan genotypes Tovar, Yaracuy, Original and U-02. The albumins and globulins were extracted with a 0.5 M NaCl solution and then separated by dialysis against water and lyophilized. These protein fractions represented 84.85% of the total amount of protein in seeds. The albumins were separated in PAGE with 7.5% acrylamide into five fractions and globulins into six, with similar electrophoretic patterns between genotypes. In a similar manner, the patterns obtained in PAGE with 10% acrylamide were the same for all genotypes, showing five bands for albumins and three bands for globulins. With PAGE-SDS containing 7.5% of acrylamide, albumins were separated into as many as eight components, and globulins into as many as seven bands with mobilities between 0.2981 and 0.9932, with different patterns for each genotype. Also the patterns PAGE-SDS at 12.6% of acrylamide were different for the genotypes, separating proteins into a greater number of bands. The albumins showed as many as twenty-one bands with mobilities between 0.2603 and 0.7398, and globulins as many as sixteen bands with mobilities between 0.2454 and 0.7390. The PAGE patterns of the genotypes analyzed did not show differences between them. However, with PAGE-SDS different electrophoretic patterns were obtained which varied in the number and intensity of the bands, making it possible to distinguish the genotypes studied. The molecular weight of the albumins varied between 76,000 and 12,000 daltons and of the globulins between 80,000 and 12,000 daltons.

Albumins↗
PubMed1991

Chromatin motion in neuronal interphase nuclei: changes induced by disruption of intermediate filaments.

Motion of nucleoli within interphase nuclei, known as nuclear rotation, may be used as a measure of motion of chromatin domains within the global confines of the nucleus. Mechanisms by which chromatin domains are transposed remain enigmatic. It has been established that nuclei are anchored by a network of intermediate filaments, structural proteins which share epitopes with nuclear lamins and possibly representing a constraint on nuclear rotation. It is postulated that selective removal of this constraint, by acrylamide, would result in increased chromatin motion. Mean rates of nucleolar displacement were quantified in neurons, in vitro. Nuclear rotation increased from a mean control rate of 0.102 +/- 0.002 micron/min (n = 52) to a maximum mean rate of 0.207 +/- 0.026 micron/min (n = 11), after 23 hr of exposure to 4 mM acrylamide. Despite this significant increase in motion of intranuclear domains, cytoplasmic structures in the immediate juxtanuclear area did not exhibit increases in rates of motion. Immunocytochemistry was used to visualize cytoskeletal structures and to assay selective disruption of neurofilaments by acrylamide. Increased rates of chromatin motion coincided with breakdown of the intermediate filament network. Ultrastructural analyses showed that the increase in chromatin motion induced by acrylamide was also associated with a significant (P less than 0.005) change in the thickness of the nuclear lamina, decreasing from 20.9 +/- 5.10 nm (n = 159) in controls to 18.9 +/- 3.1 nm (n = 148), to 19.5 +/- 3.6 nm (n = 240) and to 16.1 +/- 4.4 nm (n = 103) at 4, 8 and 22 hr exposure, respectively. Moreover, the number of mitochondria per unit area changed significantly (P less than 0.0001) with exposure to acrylamide, increasing from 9.1 +/- 2.2 mitochondrial profiles in controls to 16.5 +/- 5.3 profiles after 22 hr exposure to acrylamide. Distribution of other cytoskeletal components, actin and microtubules, was not altered and does not appear to play a significant role in the observed increase in rates of nuclear rotation. We conclude that the removal of the damping effects on chromatin motion normally imposed by the nuclear lamina and by intermediate filaments results in increased chromatin motion.

Acrylamide↗
PubMed1996

Two case reports of neurological disease in coal mine preparation plant workers.

Of 60 cases of neurotoxicity related to occupational exposures of workers at plants producing acrylamide monomers, cases involving neurotoxicity related to jobs using polymers with acrylamide monomer contamination have not been widely reported. In 1992, two patients were referred to the Division of Occupational and Environmental Health, Department of Family and Community Health, Marshall University School of Medicine, in Huntington, West Virginia for evaluation. The patients had worked in different coal preparation plants in southern West Virginia for over 10 years and had exposure to an acrylamide polymer flocculent contaminated with acrylamide monomer. Both patients had no instruction on proper use of, or the dangers of, acrylamide and were not given adequate safety equipment. Patient A developed Parkinsonism and Patient B peripheral neuropathies with a neurogenic bladder. These two case reports highlight the need to reemphasize the basic tenets of occupational health and safety. Many chemicals are being introduced into mining operations and awareness of potential toxic exposures and new diseases not previously reported in the mining industry must become part of the surveillance system by mine management and labor safety committees. Further studies on the extent of acrylamide neurotoxicity in the mining industry is encouraged.

Acrylamides↗