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PubMed2003

Sliding window dual gradient echo (SW-dGRE): T1 and proton resonance frequency (PRF) calibration for temperature imaging in polyacrylamide gel.

The aim of the work is to evaluate a magnetic resonance imaging (MRI) thermometry sequence suitable for targeting of focused ultrasound (FUS) when used in vascular occlusion studies. A sliding window dual gradient echo (SW-dGRE) sequence was used. This sequence has the capability of monitoring both T1 relaxation and phase changes, which vary with temperature. Preliminary work involved quantification of the changes in T1 relaxation time with temperature and obtaining the PRF shift coefficient in polyacrylamide gel as it underwent an exothermic reaction during polymerization (avoiding the use of an external heat source). Temperature changes were visualized using thermal maps acquired with the sequence. For FUS guidance a thermal imaging technique is required with a temporal resolution <5 s, a spatial resolution of approximately 1 mm and a temperature resolution of approximately 5 degrees C. The sequence was optimized to improve the CNR (contrast to noise ratio) and SNR (signal to noise ratio) in the phase and magnitude images respectively. The PRF coefficient obtained for the polyacrylamide gel was -9.98 +/- 0.24 ppb degrees C(-1), whilst deltaT1 and temperature change were related by a proportionality factor, the T1 temperature coefficient, of 102.3 +/- 2.9 ms degrees C(-1). The sequence produces an image at every 1.4 s interval. In both magnitude and phase data, the in-plane resolution is +/- 1.2 mm and the temperature resolution is approximately 2 degrees C. The advantage of this sequence is that the temperature obtained from the magnitude data can be confirmed independently using the phase data and vice versa. Thus the sequence can essentially be crosschecked.

Acrylic Resins↗
PubMed2006

Investigation of tetrakis hydroxymethyl phosphonium chloride as an antioxidant for use in x-ray computed tomography polyacrylamide gel dosimetry.

Of the antioxidants used to scavenge oxygen in polymer gel dosimeters, tetrakis (hydroxymethyl) phosphonium chloride (THPC) has been shown to hold great promise due to its rapid oxygen scavenging abilities. In this study we (a) investigate the use of THPC as an antioxidant for polyacrylamide gel (PAGAT) dosimeters used in conjunction with x-ray computed tomography (CT) and (b) work to establish the reaction mechanisms of THPC with the polymer gel constituents. We establish the dose response reproducibility of PAGAT dosimeters when imaged with CT and show that PAGAT dosimeters exhibit highly reproducible dose responses for a range of irradiation times post gel manufacture (2-6 h) and CT imaging times post gel irradiation (1-5 days). The THPC concentration within the gel leading to a maximized dose response and minimized O(2) inhibition of polymerization is found to be approximately 4.5 mM. We further assess the stability of PAGAT dosimeters by investigating the reactions of THPC with the individual gel constituents. The importance of utilizing deionized water in polymer gel manufacture is noted. We show that, while THPC remains unreactive with acrylamide and bis-acrylamide under unirradiated conditions, THPC can react with gelatin to increase the cross-linking of the gelatin matrix in unirradiated dosimeters. THPC reactions with gelatin can lead to the lower observed dose sensitivity of PAGAT (approximately 0.36 +/- 0.04 H Gy(-1)) as compared to polyacrylamide gels manufactured under anoxic conditions (approximately 0.83 +/- 0.03 H Gy(-1)). The reactions of THPC which lead to O(2) scavenging, and potential reactions of THPC with other gel constituents, are proposed.

Acrylic Resins↗
PubMed1994

Use of polyacrylamide gels in a saline-filled tank to determine the linearity of the Sheffield Mark 1 electrical impedance tomography (EIT) system in measuring impedance disturbances.

Polyacrylamide gels have been assessed as a means of producing reliable small impedance changes for EIT studies in saline-filled tanks. Test rods could be made in about 10 min from a stock solution of acrylamide monomer and bis-acrylamide, ammonium persulphate and tetramethylethylaminediamine, completed with saline. Impedance increases of about 10%-200% were produced by varying the gel concentration. The method appears to be easy to use, inexpensive and is stable over time. Its use was illustrated by acquiring EIT images with a Sheffield Mark 1 system and a tank filled with 0.2% saline. Polythene or polyacrylamide rods of varying resistivities, 10% of the tank diameter wide, were placed in one of three positions. The magnitude of the impedance increase in EIT images varied linearly with the actual impedance change in the rods for increases up to 20%, but the blurring in images was similar when polythene rods were used. This suggests that the use of highly resistive test objects gives a reasonable indication of the blurring in EIT images acquired with the system used, but measurement of the magnitude of the impedance change is more likely to be accurate for changes of a few tens of per cent.

Acrylic Resins↗
PubMed2004

Discrete film thickness in polyacrylamide-CdS nanocomposite ultrathin films.

A nanocomposite of polyacrylamide, a water soluble polymer, and nanocrystalline CdS has been prepared using a chemical route. Transmission electron microscope observation shows that the particles are attached via the polymer coils. The reduction of viscosity for the composite, despite the increase in concentration, indicates a reduction of interchain entanglement between the composite coils. Ultrathin films were prepared from the nanocomposite and pure polyacrylamide using spin coating on a Si(100) substrate in the speed range of 500 to 5000 rpm. X-ray reflectivity studies of the pure polymer and composite films were carried out in vacuum. The thickness of the composite films varies nonmonotonically with spinning speed and is found to lie in discrete "bands" of thickness separated by "forbidden regions." The power law behavior of the thickness with the spinning speed was also found to be different for the composite films in comparison to the polymer ones. A model has been proposed in terms of discrete numbers of layers composed of CdS-attached polymer coils to explain the phenomena.

Journal Article↗
PubMed1979

Identification of Cultivar Differences in Seed Polypeptide Composition of Peanuts (Arachis hypogaea L.) by Two-Dimensional Polyacrylamide Gel Electrophoresis.

Seed polypeptides from several cultivars of peanut (Arachis hypogaea L.) have been compared by means of a two-dimensional polyacrylamide gel electrophoresis. Protein was extracted from the defatted peanut meal by homogenizing in 5 millimolar K(2)CO(3)-9.5 molar urea. After addition of Nonidet P-40 (2%, v/v) and dithiothreitol (0.5%, w/v) the solution was centrifuged at 25,000 g. This procedure led to solubilization of more than 95% of the total protein. The clear supernatant fraction was then subjected to two-dimensional polyacrylamide gel electrophoresis, employing isoelectric focusing in the first dimension and electrophoresis in presence of sodium dodecyl sulfate in the second. After examining several cultivars, it was possible to construct a composite map to include all of the polypeptide species found among all of the cultivars examined. At least 74 major and between 100 and 125 minor components were detectable by Coomassie blue staining. The majority of these had isoelectric points between pH 4.4 and 8.0, and molecular weights between 16,000 and 75,000. Several different cultivars have been compared using this method and it has been shown that considerable variation exists among the major polypeptides present. The method should prove valuable for analyzing different genotypes and selecting varieties with a particular storage protein make-up, as well as for following compositional changes that occur during seed development and germination.

Journal Article↗
PubMed1984

Electrophoretic transfer as a technique for the detection and identification of plant amylolytic enzymes in polyacrylamide gels.

An electrophoretic transfer technique was developed for the specific identification of isozymes of starch debranching enzyme, alpha-amylase, and beta-amylase. Amylolytic enzymes are separated by native polyacrylamide slab gel electrophoresis and proteins in gels are electrophoretically transferred through starch-containing polyacrylamide gels. Each amylolytic enzyme degrades starch in the transfer gel to its characteristic limit dextrin as it moves through the gel. Various limit dextrins in the starch gel are identified by their characteristic color development in KI/I solution. Isozymes of starch debranching enzyme, alpha-amylase, and beta-amylase can be easily identified in the same gel.

Journal Article↗
PubMed2006

A new bulking agent (polyacrylamide hydrogel) for treating stress urinary incontinence in women.

OBJECTIVE: To evaluate the efficacy and safety of a transurethral injection with polyacrylamide hydrogel (PAHG) for treating stress urinary incontinence (SUI) in women. PATIENTS AND METHODS: The study comprised 17 women with pure SUI and eight with mixed incontinence (age range 35-84 years). Between November 2001 and November 2003, the women were injected into the urethral wall with a PAHG (Aquamid, Contura International A/S, Denmark), a homogenous, highly biocompatible, atoxic, nonresorbable sterile watery gel consisting of approximately 2.5% cross-linked polyacrylamide and 97.5% nonpyrogenic water. The women were followed prospectively (assessed at 1, 3 and 12 months after treatment) and their clinical outcome documented. RESULTS: Four women did not complete the study, and of the remainder, eight (38%) were subjectively dry and a further nine (43%) improved. Objectively, urine leakage/24 h was decreased by 93% and the number of incontinence episodes by 87%. Quality-of-life measures improved significantly in all domains other than general health perception. There were no significant changes of urodynamic variables. Treatment-related adverse events were recorded in 16 women. Urinary tract infection (10 cases) and urinary retention (five cases) were most common. There were no injection site reactions. CONCLUSION: PAGH seems to be a promising new bulking agent for the treatment of SUI.

Acrylic Resins↗
PubMed2004

Mechanical properties of a reversible, DNA-crosslinked polyacrylamide hydrogel.

Mechanical properties of a polyacrylamide gel with reversible DNA crosslinks are presented. In this system, three DNA strands replace traditional chemical crosslinkers. In contrast to thermoset chemically crosslinked polyacrylamide, the new hydrogel is thermoreversible; crosslink dissociation without the addition of heat is also feasible by introducing a specific removal DNA strand. This hydrogel is characterized by a critical crosslink concentration at which gelation occurs. Below the critical point, a characteristic temperature exists at which a transition in viscosity is observed. Both temperature-dependent viscosity and elastic modulus of the material are functions of crosslink density.

Acrylic Resins↗
PubMed2002

Relative effectiveness of polyacrylamide gel dosimeters applied to proton beams: Fourier transform Raman observations and track structure calculations.

The feasibility of using polyacrylamide gel (PAG) to characterize a clinically relevant 74 MeV proton beam has been considered. Fourier transform Raman spectroscopy has been used to measure the response (i.e., consumption of monomer) of PAG exposed to the central and end portions of a spread out Bragg peak (SOBP), i.e., in two regions with measurable difference in proton linear energy transfer (LET). The response curve in each region was compared with a typical 6 MV x-ray irradiated gel response curve, thus arriving at a gel "relative effectiveness" (RE) in each of the two regions. In addition, the theory of track structure, which is typically used to calculate a detector RE, is shown to give reasonable agreement when compared with the experimental results. Both experimental and track structure results indicate a decrease in gel response when irradiated with protons, as compared with the x-ray response. In addition, both sets of results indicate a variation in gel response between the mid and end SOBP regions, thus illuminating the dependence of gel response to proton LET. The physical phenomenon causing a lower proton versus x-ray gel response may be understood by considering the track structure calculations, which indicate that gel radiosensitive elements close to the track of a proton (i.e., within 1.5 x 10(-6) cm) are saturated. This saturation is due to the high delta-ray doses deposited in these regions. The track calculations are extended to other situations (e.g., raw BP, different gel compositions) where experimental determination of RE is difficult or time consuming. Results again indicate a gel response dependent on position in the depth dose curve (i.e., LET). Overall, this study illuminates the difficulty in using polyacrylamide gel to extract quantitative dose maps when exposed to proton radiation.

Acrylic Resins↗
PubMed1985

Activity stain for rapid characterization of pectic enzymes in isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gels.

A system was developed for the rapid characterization of microbial pectic enzyme complexes and then tested on Erwinia chrysanthemi and Sclerotium rolfsii. Pectic enzymes in minute samples of crude culture filtrates were resolved by ultrathin-layer polyacrylamide gel isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then assayed with an ultrathin pectate-agarose overlay stained with ruthenium red. The simple procedure can be completed within 30 min after isoelectric focusing, can detect extremely low levels of pectate lyase (6.4 x 10 mumol of product per min), and is sufficiently sensitive to determine the pectate lyase isozyme profile of a single bacterial colony with a diameter of 4 mm. Pectate lyases and polygalacturonases can be distinguished by altering buffer conditions in the overlays. The assay system revealed additional isozymes not resolved by classical techniques and generally corroborated the previously published isoelectric points and molecular weights of the pectate lyase isozymes and exo-poly-alpha-d-galacturonosidase produced by E. chrysanthemi and the endopolygalacturonase and exopolygalacturonase produced by S. rolfsii.

Journal Article↗
PubMed1971

Polyacrylamide gel electrophoresis of Corynebacterium diphtheriae: a possible epidemiological aid.

In this preliminary study, the use of polyacrylamide gel electrophoresis as an aid in the characterization of Corynebacterium diphtheriae was evaluated and a standardized method was developed. The electrophoretic patterns of 17 gravis, 14 mitis, and 2 intermedius types of C. diphtheriae were compared with the electrophoretic patterns of 5 Robinson and Peeney stock gravis serotype strains. Each of the 5 stock serotype strains had different electrophoretic patterns, although some common bands were present. The 17 gravis strains isolated in the United States showed patterns identical to those of the stock gravis serotype II strain. The 14 mitis strains examined produced 6 different electrophoretic patterns, irrespective of geographical location. One mitis pattern corresponded with the pattern of gravis serological type II. The two intermedius strains examined had identical electrophoretic patterns that resembled the pattern of gravis serotype IV. Polyacrylamide gel electrophoresis of C. diphtheriae strains may prove to be a useful epidemiologic tool in establishing the distribution and occurrence of various C. diphtheriae types.

Bacteriological Techniques↗
PubMedDate not supplied

Optimized visualization and PCR reamplification of differentially displayed cDNA bands detected by silver staining in polyacrylamide gels as established in the model of dithranol-treated keratinocytes.

The differential display of cDNA species defined by a combination of so-called anchored and arbitrary primers has been acknowledged as a powerful complex strategy to identify differences in gene expression, and depends in its original version, inaugurated by P. Liang and A. B. Pardee in 1992, on the use of radioactive-labelled nucleotides. As a non-radioactive methodological alternative, we established the use of polyesterfilm-backed 10% polyacrylamide gels for horizontal differential-display electrophoresis under non-denaturing conditions, with subsequent detection of cDNA bands by an optimized, semi-automated silver staining omitting any fixation step. Polyacrylamide gel slices carrying the silvered cDNA species of interest were cut out, chopped, squashed and incubated in an ammonium acetate/EDTA solution at 37 degrees C overnight under vigorous shaking. This procedure resulted in a 70% average success rate for subsequent PCR reamplification with regard to the number of cDNAs harvested from the differential-display gel. Novel sequence data of three cDNA clones are communicated, which under these methodological conditions were selected to be up- or down-regulated, respectively, by antipsoriatic dithranol in cultured HaCaT keratinocytes.

Acrylic Resins↗
PubMed2006

Electrophoresis of proteins and DNA on horizontal sodium dodecyl sulfate polyacrylamide gels.

An inexpensive Plexiglas apparatus which allows a simple and rapid preparation of horizontal polyacrylamide gels of different dimensions for different purposes, is described. Preparation of such gels is as easy and rapid as agarose gel preparation, and polymerized polyacrylamide gels are used to fractionate proteins or small DNA fragments using a common horizontal electrophoretic tank. This apparatus was used to electrophoretically fractionate proteins or DNA for immuno-blot analyses, particularly in the study of the allergenic response to Parietaria judaica pollen in senescence, for Southern-blot hybridizations and in the study of DNA polymorphisms.

Journal Article↗
PubMed2003

Non-denaturing polyacrylamide gradient gel electrophoresis for the diagnosis of dysbetalipoproteinemia.

Dysbetalipoproteinemia, an uncommon but highly atherogenic mixed hyperlipidemia due to the accumulation of remnants of triglyceride-rich lipoproteins, is characterized by cholesterol-enriched VLDL that migrates in the beta-position on agarose gels. The demonstration of a broad beta-band on agarose gel electrophoresis of plasma is an insensitive method and ultracentrifugation is an impractical method of diagnosing this condition. Non-denaturing polyacrylamide gradient gel electrophoresis (PGGE) was investigated as a screening method for the diagnosis of dysbetalipoproteinemia. A minigel procedure separating the Sudan Black prestained apolipoprotein B (apoB)-containing lipoproteins on a 2-8% polyacrylamide gel at 4 degrees C overnight was analyzed for ultracentrifugally and genetically proven dysbetalipoproteinemic subjects as well as matched controls for mixed hyperlipidemia. Visual inspection revealed that the presence of only small VLDL- and IDL-like particles in untreated patients was highly sensitive (72%) and specific (95%) for dysbetalipoproteinemia. Videodensitometric analysis of area under the curve for large and small VLDL, as well as IDL and LDL, permitted even better discrimination in subjects whose profiles included some staining in the LDL-like region. A ratio of area under the curve of more than 0.5 for IDL-LDL allowed for a specificity of 100% and a sensitivity of 89% for the diagnosis of dysbetalipoproteinemia. This modified PGGE system may be useful in screening for dysbetalipoproteinemia.

Acrylic Resins↗
PubMed1990

Two-dimensional polyacrylamide gel electrophoresis of proteins synthesized and released by conceptuses and endometria from pony mares.

Conceptuses were obtained from pony mares on each day of pregnancy between Days 12 and 28, and on Days 39, 45, 65 and 100. Endometrium was obtained from mares at Days 12, 14, 16, 18, 39, 45, 65 and 100 of pregnancy, and from non-pregnant mares during anoestrus, during transition into the breeding season, at oestrus, or during dioestrus. Tissues were incubated in vitro for 24 h with L-[3H]leucine. Proteins synthesized and released into the culture medium were analysed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and fluorography. Conceptuses obtained before Day 14 after ovulation released a characteristic pattern of labelled proteins. These included two groups of apparent isoelectric variants of relative molecular weights (Mr) 30,000-40,000 (pI values 4.5-5.5 and 6-7), one group of Mr approximately 22,000 (pI 6.5-7), and large protein(s) that did not enter the 10% polyacrylamide gel. After Day 14 the array of labelled proteins had changed and resembled that produced by isolated yolk sac at the later stages of pregnancy studied. Included amongst these were several acidic polypeptides with Mr 20,000 (pI 5-6). The endometrial samples released an array of non-dialysable polypeptides into the culture medium. Fluorograms could be assigned to one of three general groups, with endometrium from mares within each group producing similar patterns of labelled proteins. The first group consisted of anoestrous, transitional and ovariectomized mares, and mares at oestrus or Day 1 or Day 18 after ovulation. The second group was comprised of mares at Days 12-16 of dioestrus or Days 12-18 of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

A new isoelectric focusing system for fast two-dimensional gel electrophoresis using a low-concentration polyacrylamide gel supported by a loose multifilament string.

A new isoelectric focusing (IEF) system for two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) has been proposed. In this system, a super-soft and tough IEF gel was achieved by casting polyacrylamide gel down to 2.0% T using a loose multifilament string (LMS) of nylon as a gel support. The IEF apparatus for the LMS-gel, fabricated from acrylic boards, had a cooling water chamber, and eliminated the need of electrode solutions by directly connecting the two ends of individual gels to platinum electrodes. The carrier ampholyte-generated pH gradients using the new IEF system was stable over a long duration of time and a wide range of voltages, and the IEF time became shorter using a 2.0% T gel than using a 4.0% T gel. Also, the LMS-gels prepared in different runs exhibited excellent reproducibility. The new IEF system was applied to 2-D PAGE of a chicken skeletal muscle extract, and it was found that the protein loading capacity, protein entry into the LMS-gels, and protein transfer efficiency from the first-dimensional to the second-dimensional gels were significantly improved by using a low-concentration (2.5% T) gel. Also, proteins of high molecular weight of more than 200 kDa were observed in the 2-D maps, and therefore the new IEF system has a very good potential to be applied for fast 2-D PAGE of high molecular-weight proteins.

Journal Article↗
PubMed1975

Disc electrophoresis of turkey serum alkaline phosphatase isoenzymes using polyacrylamide gel. 1. Procedure.

The isoenzymes of alkaline phosphatase in turkey serum were separated by disc electrophoresis using polyacrylamide gel as the supporting medium In this laboratory we have been unable to adapt polyacrylamide gel electrophoresis procedures for turkey serum that had been described by previous workers as successful in separating the isoenzymes of avian alkaline phosphatase. A rapid and repeatable procedure that yielded excellent resolution of alkaline phosphatase isoenzymes was devised. This procedure involved a step-by-step determination of the following: a suitable gel system, buffer system, staining procedure and sample preparation.

Alkaline Phosphatase↗
PubMed2005

[Analysis of complications induced by polyacrylamide hydrogel injection for augmentation mammaplasty].

OBJECTIVE: To analyze the complications induced by polyacrylamide hydrogel injection for augmentation mammaplasty, explore the reason of the complication. METHODS: Twenty three patients with complications after polyacrylamide hydrogel injection were classified by signs and symptoms, ultrasound and pathologic examinations were made. RESULTS: The main complications were pain, hard nodule, asymmetry and breast deformation. The injected material was distributed diffusely behind gland, in gland, in muscles subcutaneous, even out of breast, caused some pathologic changes and it's hard to be cleaned completely from normal tissue. CONCLUSIONS: The complications were caused mainly by incorrect manipulation during operation, others might be relative to the injected material. The reliability of this injection method for augmentation should be cautiously observed.

Acrylic Resins↗