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PubMed1993

The relationship of agarose gel structure to the sieving of spheres during agarose gel electrophoresis.

To understand the organization of fibers in an agarose gel, digitized electron micrographs are used here to determine the frequency distribution of interfiber distance (2Pc) in thin sections of agarose gels. For a preparation of underivatized agarose, a 1.5% gel has a Pc distribution that is indistinguishable from the Pc distribution of a computer-generated, random-fiber gel; the log of the occurrence frequency (F) decreases linearly as a function of Pc. As the agarose concentration decreases below 1.5%, the semilogarithmic F versus Pc plot becomes progressively less linear. Two straight lines represent the data; the plot is steeper at the lower Pc values. As the percentage of agarose increases above 1.5%, the semilogarithmic F versus Pc plot becomes steeper at the higher Pc values. This change in the shape of semilogarithmic F versus Pc plots is possibly explained by the existence in agarose gels of two zones, one whose Pc distribution is more sensitive to the average agarose concentration than the other. To compare the structure of agarose gels to their sieving during electrophoresis, the root mean square value of Pc (Pc) is compared to the sieving-based radius of the effective pore (PE; Griess et. al. (16)) for both underivatized agarose and a derivatized agarose that has a smaller PE at any given agarose percentage. For 0.8-2.0% gels of either underivatized or derivatized agarose, PE/Pc is a constant within experimental error. Deviations from this constant are observed at lower gel percentages. This relationship of PE to Pc constrains theoretical descriptions of the motion of spheres in fibrous networks.

Biophysical Phenomena↗
PubMedDate not supplied

Cervical ripening: randomized comparison of intravaginal prostaglandin E2 gel with prostaglandin E2 gel plus laminaria tents.

The purpose of this study was to evaluate the efficacy of adding laminaria tents to sequential intravaginal prostaglandin E2 (PGE2) gel for cervical ripening. A prospective, randomized study was conducted from October 1994 to May 1995. Pregnant women with maternal or fetal indications for induction of labor at > or = 37 weeks gestation and a Bishop score of < or = 4 were eligible. Nineteen patients received laminaria tents in addition to 4 mg PGE2 gel, while 25 patients received PGE2 gel alone. After 4 hr, the laminaria tents were removed and the gel was continued in both groups at 4-hr intervals. Induction with oxytocin was initiated after a Bishop score of > or = 5 was achieved. The groups were comparable with respect to maternal age, parity, gestational age, reason for induction, and initial Bishop score. The addition of laminaria tents to sequential PGE2 gel did not statistically improve the time to a favorable cervix (control group 12.7 +/- 8.5 hr (95% CI, 9.1-16.3) and study group 10.9 +/- 7.1 hr (95% CI, 7.5-14.3) (P = 0.59). The 6-hr difference from the time of the initial PGE2 gel placement to delivery was not detected (control group 22.4 +/- 11.2 hr, 95% CI 17-27 and study group 23.4 +/- 13.1 hr, 95% CI 17-29.6 (P = 0.79). The combination approach of laminaria tents and PGE2 gel did not have a significant impact on the vaginal delivery rate, with 28.0% of patients in the control group and 26.3% of patients in the study group undergoing cesarean section (P = 0.90). Maternal and neonatal complications were rare in both groups. We had insufficient evidence to show that the addition of laminaria tents to PGE2 gel improved cervical ripening, the induction to delivery interval, or the cesarean section rate in patients at term undergoing induction of labor.

Administration, Intravaginal↗
PubMed1991

Estimation of polyacrylamide gel pore size from Ferguson plots of normal and anomalously migrating DNA fragments. I. Gels containing 3% N,N'-methylenebisacrylamide.

The mobilities of normal and anomalously migrating DNA fragments were determined in polyacrylamide gels of different acrylamide concentrations, polymerized with 3% N,N'-methylenebisacrylamide as the crosslinker. The DNA samples were a commercially available 123-bp ladder and two molecular weight ladders containing multiple copies of two 147-base pair (bp) restriction fragments, obtained from the MspI digestion of plasmid pBR322. One of the 147 bp fragments is known to migrate anomalously slowly in polyacrylamide gels. Ferguson plots were constructed for all multimer ladders, using both absolute mobilities and relative mobilities with respect to the smallest DNA molecule in each data set. If the retardation coefficients were calculated from the relative mobilities, and the rms radius of gyration was used as the measure of DNA size, the Ogston equations were obeyed and the gel fiber parameters could be calculated. The effective pore sizes of the gels were estimated from the gel concentration at which the mobility of a given DNA molecule was reduced to one-half its mobility at zero gel concentration. The estimated pore radii ranged from approximately 130 nm for 3.5% gels to approximately 70 nm for 10.5% gels. These values are much larger than the pore sizes previously determined for the polyacrylamide matrix.

Acrylamides↗
PubMed1998

Apparent pore size of polyacrylamide gels: comparison of gels cast and run in Tris-acetate-EDTA and Tris-borate-EDTA buffers.

The electrophoretic mobilities of DNA molecules in three different molecular weight ladders were measured in polyacrylamide gels containing different acrylamide concentrations (%T) and cross-linker ratios (%C), cast and run in Trisacetate-EDTA (TAE) buffer. The apparent pore radius of each gel was estimated from Ferguson plots of the relative mobilities of each of the DNA molecules, using the mobility of the monomer fragment in each molecular weight ladder as the reference mobility. The effective size of each of the DNA molecules was estimated from its radius of gyration. The apparent gel pore radii calculated in this manner ranged from 21 nm in gels containing 10.5%T, 5%C to 200 nm in gels with 4.6%T, 2%C, similar to the values observed for polyacrylamide gels cast and run in Tris-borate-EDTA (TBE) buffer (Holmes and Stellwagen, Electrophoresis 1991, 12, 612-619). Hence, the effective pore size of polyacrylamide gels is essentially independent of whether the gels are cast and run in TAE or TBE buffer.

Acetates↗
PubMed2006

Simultaneous electrophoretic analysis of proteins of very high and low molecular weights using low-percentage acrylamide gel and a gradient SDS-PAGE gel.

To be able to separate and analyze giant proteins and small proteins in the same electrophoretic gel, we have used a continuous SDS-PAGE gel formed by the combination of a low-percentage acrylamide gel and a gradient SDS-PAGE gel that we have named LAG gel. To get a good resolution for proteins of more than 200 kDa, we used an acrylamide/bisacrylamide ratio of 80:1 in the low-percentage acrylamide gel. To successfully resolve proteins in the 5-200 kDa range, we used a conventional 6-15% SDS-PAGE gradient gel with the standard acrylamide/bisacrylamide ratio of 40:1. We show that the LAG system can be successfully used in general applications of SDS-PAGE electrophoresis such as proteomics and immunobloting techniques. Thus, using this continuous LAG gel, it is possible to simultaneously analyze giant proteins, such as HERC1 and dynein, big proteins like clathrin heavy chain and small proteins like ARF. The LAG system has a good resolution, low cost, and high reproducibility. Moreover, to simultaneously analyze all proteins saves time. All these characteristics, together with the use of a standard apparatus found in any biochemistry laboratory, make the LAG system an easy tool to use.

Acrylamides↗
PubMed2006

Universal method for synthesis of artificial gel antibodies by the imprinting approach combined with a unique electrophoresis technique for detection of minute structural differences of proteins, viruses, and cells (bacteria). III: gel antibodies against cells (bacteria).

Artificial antibodies in the form of gel granules were synthesized from the monomers acrylamide and N,N'-methylenebisacrylamide by the imprinting method in the presence of Echerichia coli bacteria as template. The electrophoretic migration velocities of the gel antibodies (i) saturated with the antigen (Escherichia coli MRE-600), (ii) freed of the antigen, and (iii) resaturated with bacteria, were determinated by electrophoresis in a rotating narrow-bore tube of 245 mm length and the 2.5 and 9.6 mm inner and outer diameters, respectively. Removal of bacteria from the gel antibodies was made by treatment with enzymes, followed by washing with SDS and buffer. Gel granules becoming charged by adsorption of bacteria move in an electrical field. We obtained a significant selectivity of gel antibodies for E. coli MRE-600, since the granules did not interact with Lactococcus lactis; and when E. coli BL21 bacteria were added to the gels selective for E. coli MRE-600, a significant difference in the migration rate of the complexes formed with the two strains was observed indicating the ability of differentiation between the two strains. The gel antibodies can be used repeatedly. The new imprinting method for the synthesis of artificial gel antibodies against bioparticles described herein, and the classical electrophoretic analysis technique employed, thus represent - when combined - a new approach to distinguish between different types and strains of bacteria. The application area can certainly be extended to cover other classes of cells.

Acrylamide↗
PubMedDate not supplied

Multiple-point adsorption of terbium ions by lead ion templated thermosensitive gel: elucidating recognition of conformation in gel by terbium probe.

Lead ion templated thermosensitive heteropolymer gel which has recognition ability of methacrylate pairs has been synthesized and characterized. The gel consists of a main monomer component, N-isopropylacrylamide (NIPA), responsible for volume phase transition, methacrylic acid (MAA) moieties imprinted as pairs to adsorb terbium ions and cross-links. An imprinting technique was applied using lead ion complex with methacrylate ligands in dioxane media. After gel was obtained, lead ions were removed by washing and the imprinted gel showed strong binding ability to terbium ions, comparable with that of the non-imprinted gel prepared without lead ions. It was found that the Tb(3+) fluorescence intensity was considerably increased upon binding this ion to both imprinted and non-imprinted gels, but the largest enhancement of fluorescence intensity was observed when Tb(3+) was bound to imprinted gel in shrunken state. This is because of the decrease of coordinated water molecules on Tb(3+) and the strong binding of this ion to methacrylate pairs which are encoded within the weakly cross-linked network of imprinted gel.

Acrylamides↗
PubMed1986

The effect of endocervical PGE2-gel (Prepidil) gel on plasma levels of 13,14-dihydro-15-keto-PGE2 (PGEM) in women at term.

Term pregnant patients undergoing preinduction cervical softening were randomized to receive no treatment (controls) or 0.5 mg PGE2-triacetin gel (Prepidil gel) endocervically. Plasma samples containing PGEM collected 4 hrs post-treatment and converted to the stable bicyclo degradation product (bicyclo-PGEM) were assayed by RIA. Positive clinical effect (responders) during 12 hrs after treatment (Bishop score increase greater than or equal to 3, in labor or delivered) were assessed. All evaluations were blind. In nonresponders (n = 35), the means of the bicyclo-PGEM variables (mean, maximum, area under the curve) were all about 18% higher in gel-treated patients (n = 6) than controls (n.s.). In responders (n = 38), the variables were all about 80% higher in gel-treated women (n = 32) than controls (p less than .01). In controls (n = 35), the responders (n = 6) had 50% higher levels than nonresponders (n.s.). In the gel-treated women (n V 38), responders (n = 32) had about 140% higher levels than nonresponders (less than .01). The results suggest that both exogenous and endogenous bicyclo-PGEM were measured. Differences in pairwise comparisons suggest that there may be substantially less exogenous bicyclo-PGEM in the gel nonresponders than in gel responders or substantially more endogenous bicyclo-PGEM in gel responders than in control-responders.

Adolescent↗
PubMed1985

[Affinity electrophoresis in polyacrylamide gel. Influence of the concentration in the gel on the apparent affinity of cholinesterase for an anionic ligand site].

Affinity electrophoresis of three purified molecular forms of human plasma cholinesterase (monomer C1, dimer C3, tetramer C4) was carried out in polyacrylamide gels at various total acrylamide concentrations ranging from 3.48 to 9% in a discontinuous buffer system. A water-soluble linear copolymer supporting procainamide, a ligand of the anionic site of cholinesterase, was physically entrapped at various concentrations within the gel network. The combined effects of gel concentration and ligand concentration on the affinity pattern of the three molecular forms were studied. It was found that gel concentration influences the apparent binding activity of their anionic site: The apparent strength of interaction varied with the gel concentration: the denser the gel was, the higher the apparent affinity. The ligand-induced isomerization process was also depending on the gel concentration: the ligand concentration from which each zone is splitting into two moving zones decreased as the total gel concentration increased. These results show that the electrophoretic matrix plays an important role in the affinity process in affinity electrophoresis presumably by controlling kinetic effects: kinetics of protein-ligand complex formation and dissociation reactions, and mass transfer kinetics.

Butyrylcholinesterase↗
PubMed2003

Cation effects on sol-gel and gel-sol phase transitions of kappa-carrageenan-water system.

Sol-gel and gel-sol phase transitions of kappa-carrageenan in pure water and in KCl solution were studied using photon transmission technique. Photon transmission intensity, I(tr), was monitored against temperature to determine the sol-gel and gel-sol temperatures (T(sg) and T(gs)) and activation energies (deltaH(sg) and deltaH(gs)). It was observed that T(gs) was notably higher than T(sg) due to the hysteresis on the phase transition loops. T(gs) and deltaH(gs) values were also higher for gels containing KCl than for those without KCl. The increase in carrageenan content caused an increase in both critical temperatures and activation energies for the gels prepared in pure water and in KCl solution. Increases in the KCl/carrageenan ratio, raised both T(gs) and T(sg). Similarly deltaH(sg) was elevated by the increase in cation content of the gel. These results were interpreted as the formation of stronger gels in the presence of KCl in water.

Carrageenan↗
PubMedDate not supplied

In vitro comparison of antifungal effects of a coal tar gel and a ketoconazole gel on Malassezia furfur.

Malassezia furfur seems to be a major pathogenetic factor in seborrhoeic dermatitis, a frequent human skin disease. To estimate the antifungal properties of a coal tar gel (5 mg ml-1 coal tar) which is used in the treatment of seborrhoeic dermatitis of the scalp, we compared its effects on the in vitro growth of M. furfur with those of a ketoconazole gel (20 mg ml-1 ketoconazole). None of the gels was fungicidal within incubation times up to 20 min. During a single application, both gels remain on the skin for only 5 min. Fungicidal effects are consequently unlikely to play a substantial therapeutic role. Fungistatic effects were observed with both gels. In cultures inoculated with 1 x 10(3) cells ml-1, a 1:49 152 dilution of the ketoconazole gel and a 1:768 dilution of the coal tar gel still showed inhibitory effects. At inoculum densities of 1 x 10(5) ml-1, both gels were fungistatic only in dilutions of a maximum of 1:40. Our results suggest that under clinical treatment conditions the fungistatic activities of both preparations should be comparable.

Coal Tar↗
PubMed1999

Double-blind controlled clinical study of the efficacy and tolerability of diclofenac-N-(2-hydroxyethyl)-pyrrolidine lecithin gel compared with diclofenac-N-(2-hydroxyethyl)-pyrrolidine gel in patients with peri and extraarticular inflammatory diseases.

To evaluate the efficacy and tolerability of the new diclofenac-N-(2-hydroxyethyl)-pyrrolidine lecithin gel (DHEP lecithin gel, with 1.3% DHEP and 2.4% lecithin) compared with the efficacy and tolerability of diclofenac-N-(2-hydroxyethyl)-pyrrolidine gel (DHEP gel) in peri and extraarticular inflammatory states, a controlled, randomized, double-blind clinical study was conducted. Two groups of 50 patients each were enrolled and were given one of the two different formulations with a slight massage on the painful area three times a day for 10 consecutive days. Patients received a self-evaluation notebook in which to record daily assessment of spontaneous pain (Huskisson's visual analogue scale). On days 0, 3 and 10, the patients were visited by the investigator. All patients completed the study. The assessment of spontaneous pain showed that although pain decreased in both groups, the decrease was more marked in patients taking DEHP lecithin gel and that it reached a statistically significant difference at days 5, 6, 7 and 8. This decrease was also confirmed by assessments on the ordinal scale. Although periarticular swelling disappeared in both groups, swelling severity decreased sooner in patients taking DHEP lecithin gel. The efficacy and safety of both treatments was judged to be good or excellent by 70% of the patients in each group. The efficacy of the active principle, pyrrolidine salt, is confirmed. Moreover, the formulation containing lecithin passes through the skin lipid barrier more easily than the formulation without lecithin and is as valid as the other in the therapy of rheumatic disorders. Finally, DHEP lecithin gel preparation has a quicker therapeutic action on symptoms, such as spontaneous pain and local swelling, than DHEP gel.

Adolescent↗
PubMed2001

Efficacy and tolerability of once-daily tazarotene 0.1% gel versus once-daily tretinoin 0.025% gel in the treatment of facial acne vulgaris: a randomized trial.

Tazarotene 0.1% gel and tretinoin 0.025% gel are both effective in the treatment of acne vulgaris. Results of a multicenter, double-blind, randomized, parallel-group study that compared the efficacy and tolerability of these drugs are presented here. A total of 143 patients with mild-to-moderate facial acne vulgaris were randomized to receive tazarotene 0.1% gel or tretinoin 0.025% gel once daily for 12 weeks. Tazarotene 0.1% gel was more effective than tretinoin 0.025% gel in reducing the open comedo count (P < or = .05), the total noninflammatory lesion count (P < or = .05), and the total inflammatory lesion count (not statistically significant). At some time points, tazarotene was associated with increased irritation, but peeling, erythema, dryness, burning, and itching never exceeded trace levels. We conclude that tazarotene 0.1% gel is more effective than tretinoin 0.025% gel in reducing noninflammatory lesions and similarly effective in reducing inflammatory lesions.

Acne Vulgaris↗
PubMed1985

Binding of serum proteins to polymer gels. II. Binding mechanism to polyoxyphenol-formaldehyde gels.

The binding mechanism of proteins to an amorphous polymer gel [formaldehyde-hydroquinone (FA-HQ)], which is a product of addition condensation of hydroquinone with formaldehyde, is examined. Proteins such as serum albumin and gamma-globulin bound to the FA-HQ gel rapidly and irreversibly (without elution by acid, alkali, urea, or detergent solution). The binding of a modified bovine albumin to the FA-HQ gel showed that the blocking of the amino groups in the albumin molecule decreased the amount of protein bound to the gel. Amino acids bound to the FA-HQ gel to a larger extent at alkaline than at neutral pH. These results supported the essential role of the amino groups in binding to the FA-HQ gel. Using the FA-HQ gel-packed glass column or polymer tube, rapid and complete removal of proteins from serum could be carried out, which suggests the usefulness of the gel for the easy pretreatment of biological samples for clinical assays using immobilized enzyme columns.

Amino Acids↗
PubMed2006

Bovine chondrocyte behaviour in three-dimensional type I collagen gel in terms of gel contraction, proliferation and gene expression.

This study evaluated the in vitro behaviour of bovine chondrocytes seeded in collagen gels, promising recently reported scaffolds for the treatment of full-thickness cartilage defects. To determine how chondrocytes respond to a collagen gel environment, 2 x 10(6) chondrocytes isolated from fetal, calf and adult bovine cartilage were seeded within type I collagen gels and grown for 12 days in both attached and floating (detached from the culture dish after polymerisation) conditions. Monolayer cultures were performed in parallel. All chondrocytes contracted floating gels to 55% of the initial size, by day 12. Contraction was dependent on initial cell density and inhibited by the presence of dihydrocytochalasin B as previously observed with fibroblasts. Gene expression was determined using conventional and real-time PCR. The chondrocyte phenotype was better maintained in floating gels compared to attached gels and monolayers. This was demonstrated by comparing the ratio of COL2A1/ COL1A2 mRNA and also of alpha10/alpha11 integrin mRNA. A strong up-regulation of MMP13 expression was measured at day 12 in floating gels. The composition of cartilage-like tissue obtained by growing chondrocytes in a collagen gel varied depending on the floating or attached conditions and initial cell density. It is thus important to consider these parameters when using this culture system in order to prepare a well-defined implant for cartilage repair.

Animals↗
PubMed2004

In vivo distribution of a vaginal gel: MRI evaluation of the effects of gel volume, time and simulated intercourse.

A microbicide is designed to coat the vaginal epithelium and prevent transmission of HIV. Complete coverage is desired for optimal protection. In vivo factors affecting coverage have not yet been studied. This randomized crossover trial evaluates the effect of gel volume and patient activity upon vaginal epithelial coating. Gynol II gel was mixed with a magnetic resonance imaging (MRI) contrast agent. Ten women self-inserted, on separate visits, 3 or 5 mL of gel and underwent serial MRI scanning both before and after simulated intercourse. Gel spread was dependent upon time and volume. There was modest spread during the first hour and greater spread 6 h after insertion. Five milliliters of gel resulted in statistically significantly greater coverage immediately following insertion, within the first 30 min and at 6 h after insertion. Simulated intercourse greatly enhances gel spread. After simulated intercourse, the distribution of the gel at each volume was similar. Less leakage of gel was reported with the smaller volume.

Adult↗
PubMed2002

A randomized, double-blind comparison of a clindamycin phosphate/benzoyl peroxide gel formulation and a matching clindamycin gel with respect to microbiologic activity and clinical efficacy in the topical treatment of acne vulgaris.

BACKGROUND: One approach to suppressing the overgrowth of antibiotic-resistant bacteria is to develop combination products composed of active constituents with complementary but distinct mechanisms of antibacterial action. OBJECTIVE: The purpose of this study was to compare the antimicrobial and clinical efficacy and tolerability of clindamycin phosphate 1%/benzoyl peroxide 5% gel formulation with matching clindamycin 1% gel in the treatment of acne vulgaris. METHODS: This 16-week, single-center, double-blind, randomized, parallel-group study compared the combination gel with clindamycin monotherapy applied BID in patients 13 to 30 years of age with mild to moderate acne and facial Propionibacterium acnes counts > or = 10(4) colony-forming units per square centimeter of skin. RESULTS: Seventy-nine patients were enrolled and randomly assigned to receive the combination gel (n = 40) or clindamycin monotherapy (n = 39). Seventy patients (50 males, 20 females; mean age, 18.2 years) were included in the intent-to-treat group. The combination gel treatment produced significantly greater reductions (P < or = 0.046) from baseline in total lesion counts and in numbers of inflammatory lesions and comedones compared with clindamycin monotherapy. Greater reductions in the severity of acne also were observed in the physician's and patient's Clinical Global Improvement scale scores and in other secondary efficacy measurements. Reductions in clindamycin-resistant P acnes counts were observed relative to baseline in the combination gel group; in contrast, P acnes counts increased by >1,600% in the clindamycin monotherapy group at week 16 (P = 0.018 vs combination gel). Reductions in inflammatory (r2 = 0.31; P = 0.016) and total (r2 = 0.28; P = 0.027) lesions were correlated with decreases in clindamycin-resistant bacteria. Also, significant correlations were observed between the percent change from baseline in total lesion counts (r2 = 0.44; P < 0.001) and comedo counts (r2 = 0.50; P < 0.001) and the log10 change from baseline in total P acnes counts. CONCLUSIONS: The total P acnes count (P = 0.002) and the clindamycin-resistant P acnes count (P = 0.018) were significantly reduced after 16 weeks of treatment with combination gel compared with clindamycin monotherapy. These reductions in total P acnes and clindamycin-resistant P acnes counts correlated with reductions in total acne lesions.

Acne Vulgaris↗
PubMed2006

Evolution of gel structure during thermal processing of Na-geopolymer gels.

The present work examines how the gel structure and phase composition of Na-geopolymers derived from metakaolin with varied Si/Al ratio evolve with exposure to temperatures up to 1000 degrees C. Gels were thermally treated and characterized using quantitative XRD, DTA, and FTIR to elucidate the changes in gel structure, phase composition, and porosity at each stage of heating. It is found that the phase stability, defined by the amount and onset temperature of crystallization, is improved at higher Si/Al ratios. Two different mechanisms of densification have been isolated by FTIR, related to viscous flow and collapse of the highly distributed pore network in the gel. Gels with low Si/Al ratio only experience viscous flow that correlates with low thermal shrinkage. Gels at a higher Si/Al ratio, which have a homogeneous microstructure composed of a highly distributed porosity, undergo both densification processes corresponding to a large extent of thermal shrinkage during densification. This work elucidates the intimate relationship between gel microstructure, chemistry, and thermal evolution of Na-geopolymer gels.

Journal Article↗