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PubMed1975

Agar derivatives for chromatography, electrophoresis and gel-bound enzymes. III. Rigid agarose gels cross-linked with divinyl sulphone (dvs).

Agarose cross-linked with divinyl sulphone (DVS) is a new matrix for chromatography and immobilized enzymes that has distinct advantages over common agarose gels. It has outstanding mechanical stability as compared with these gels, and the rigid gel beads form beds permitting very high flow-rates. In addition, DVS-agarose is superior to agarose gels with respect to chemical stability in acid and neutral media. In alkaline solutions above pH 8, there is a slow elimination of the sulphone-containing bridges, but without noticeable concomitant dissolution of the gels below pH 12 for moderately or highly cross-linked gels. The DVS-agarose is sufficiently thermostable to be heated in an autoclave.

Chromatography, Gel↗
PubMed2000

Phase separation and gel formation in kinetically trapped gelatin/maltodextrin gels.

The kinetics of phase separation and gel formation of gelatin/maltodextrin mixtures have been studied using confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), stereological image analysis and rheology. The quantified microstructural parameters were the volume-weighted mean volume and the interfacial area. The temperature of phase separation was defined as the temperature where the first signs of phase separation were observed in CLSM. The gelatin concentration varied between 4 (wt.) and 5% and the maltodextrin concentration varied between 2 and 6%. Maltodextrin was labelled covalently with RITC to improve the contrast between the gelatin phase and the maltodextrin phase. The solutions were cooled from 60 to 10 degrees C, and the cooling rates used were 0.4, 1 and 3 degrees C/min. All systems were found to be gelatin continuous under the experimental conditions used. The results showed that the temperature of phase separation (TPS) increased both with the gelatin concentration and the maltodextrin concentration, but particularly with the former. The size of the maltodextrin inclusions increased with TPS, and the interfacial area decreased with increasing TPS. The diameter of the maltodextrin inclusions varied between 1.6 and 8.5 microm at 1 degrees C/min. The size of the maltodextrin inclusions was found to increase with decreasing cooling rate and was largest at 0.4 degrees C/min. The TPS was compared with the gelation temperature (Tgel) at three different concentrations of gelatin and maltodextrin (4/3, 4/5, 5/5%). CLSM micrographs and TEM micrographs showed that these three concentrations of gelatin and maltodextrin had different microstructures. At a TPS above Tgel (5/5%), the phase separation proceeded faster than the gel formation and the microstructure had few, large maltodextrin inclusions and a clean continuous gelatin phase. At a TPS comparable with Tgel (4/5%), phase separation occurred during gel formation, which led to a varying microstructure and competition between the phase separation and the gel formation. At a TPS below Tgel (4/3%), gel formation proceeded faster than the phase separation and the microstructure had many, small inclusions and a diffuse microstructure, and the phase separation was incomplete. It was established that the microstructure was determined by the relative rates of the phase separation and the gel formation. Three different zones of phase separation could be distinguished based on comparisons of TPS and Tgel, and results from CLSM, TEM and image analysis.

Animals↗
PubMed1999

Detection of beta-1,6-glucanase isozymes from Trichoderma strains in sodium dodecyl sulphate-polyacrylamide gel electrophoresis and isoelectrofocusing gels.

The filamentous fungus Trichoderma produces, under specific growth conditions, several extracellular fungal cell wall degrading enzymes, amongst them beta-1,6-glucanases. These enzymes seem to play an important role in the antagonistic action of Trichoderma against a wide range of fungal plant pathogens. In this report we describe two different methods for the specific detection of the activity of beta-1,6-glucanase isozymes in gels. After sodium dodecyl sulphate-polyacrylamide gel electrophoresis, beta-1,6-glucanase activity can be assayed in the gel by renaturation of the enzyme, incubation with an overlay agarose gel containing solubilized pustulan (a commercially available beta-1,6-glucan), followed by the staining of the agarose gel with Congo Red. In native isoelectrofocusing gels, as little as 1 mU can be detected after incubation with solubilized pustulan followed by a detection reaction of the released reducing sugars with 2,3,5-triphenyltetrazolium chloride. The latter technique has been successfully applied to the screening of beta-1,6-glucanase isozymes from different Trichoderma strains under different growth conditions.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

Small-angle X-ray scattering and rheological characterization of alginate gels. 3. Alginic acid gels.

Alginic acid gels were studied by small-angle X-ray scattering and rheology to elucidate the influence of alginate chemical composition and molecular weight on the gel elasticity and molecular structure. The alginic acid gels were prepared by homogeneous pH reduction throughout the sample. Three alginates with different chemical composition and sequence, and two to three different molecular weights of each sample were examined. Three alginate samples with fractions of guluronic acid residues of 0.39 (LoG), 0.50 (InG), and 0.68 (HiG), covering the range of commercially available alginates, were employed. The excess scattering intensity I of the alginic acid gels was about 1 order of magnitude larger and exhibited a stronger curvature toward low q compared to ionically cross-linked alginate. The I(q) were decomposed into two components by assuming that the alginic acid gel is composed of aggregated multiple junctions and single chains. Time-resolved experiments showed a large increase in the average size of aggregates and their weight fraction within the first 2 h after onset of gelling, which also coincides with the most pronounced rheological changes. At equilibrium, little or no effect of molecular weight was observed, whereas at comparable molecular weights, an increased scattering intensity with increasing content of guluronic acid residues was recorded, probably because of a larger apparent molecular mass of domains. The results suggest a quasi-ordered junction zone is formed in the initial stage, followed by subsequent assembling of such zones, forming domains in the order of 50 A. The average length of the initial junction zones, being governed by the relative fraction of stabilizing G-blocks and destabilizing alternating (MG) blocks, determines the density of the final random aggregates. Hence, high-G alginates give alginic acid gels of a higher aggregate density compared to domains composed of loosely packed shorter junction zones in InG or LoG system.

Alginates↗
PubMed2006

QCM studies of gel spreading: Kraton gels on polystyrene surfaces.

Contact of a polymer gel made from a styrene/ethylene-butene/styrene triblock copolymer in mineral oil was investigated by bringing the gel into contact with the coated surface of a quartz crystal microbalance (QCM). The experimental apparatus enabled simultaneous measurement of the load, displacement, and contact area, in addition to the resonant frequency and dissipation of the oscillating quartz crystal. The QCM response was determined by the linear viscoelastic properties of the gel at the frequency of oscillation. A geometric correction factor involving the contact area provided a means for quantitatively determining these viscoelastic parameters as the gel spread over the QCM surface. When the gel was removed from the surface, a thin solvent layer was left behind. The thickness of this solvent layer was determined from the QCM response and was compared to predictions from a simple model involving the disjoining pressure of the film and the osmotic pressure of the gel. Qualitative agreement with the model required that tensile, adhesive forces at the perimeter of the gel/QCM contact area were taken into account when calculating the film thickness.

Chemical Phenomena↗
PubMed1987

The use of gel chromatography for the determination of sizes and relative molecular masses of proteins. Interpretation of calibration curves in terms of gel-pore-size distribution.

The separation of proteins by gel-exclusion chromatography has been explained in terms of partitioning of the macromolecules within the gel by a distribution of pores of various radii. The assumption that the distribution of pore sizes is Gaussian has led to the prediction of a linear relationship between the molecular Stokes radius (RS) of the protein and the function erf-1 (1-KD), where KD is the partition coefficient [Ackers (1967) J. Biol. Chem. 242, 3237-3238]. Since careful calibrations of classical (agarose and dextran) gels and h.p.l.c. gels have shown that such a linear relationship is not verified experimentally over a wide range of native protein sizes, we have reinvestigated the model of Ackers (above reference). We show that Ackers' (above reference) derivation is not valid except for a particular Gaussian distribution of pore sizes centred at the origin. Relaxation of this restriction to allow for other types of Gaussian distributions cannot account for the non-linear calibration curves that we have obtained. Instead we show that the pore-size distribution can be calculated from the experimentally determined function KD = f(RS) and that this distribution is bimodal (non-Gaussian). One distribution is centred below 2 nm, whereas the mean value of the second one is around 6-8 nm. The minimum in this bimodal distribution corresponds, for some gels, to a region of poor resolution, which needs to be appreciated for the proper use of gel chromatography in the determination of molecular size.

Chromatography, Gel↗
PubMed2004

Genetic analysis of Pseudomonas aeruginosa by enterobacterial repetitive intergenic consensus polymerase chain reaction (PCR) and arbitrarily primed PCR: gel analysis compared with microchip gel electrophoresis.

OBJECTIVES: To assess the applicability of a newly emerging microchip gel electrophoresis for rapid strain differentiation among clinical isolates of Pseudomonas aeruginosa, and to compare this technique with the traditional gel method for DNA separation. METHODS: One hundred clinical strains of P. aeruginosa obtained from a hospital in northwestern Ohio were tested for reactivity to 3 serotype-specific monoclonal antibodies by enzyme-linked immunosorbent assay. Twelve strains (4 from each serogroup) were selected for DNA analysis by polymerase chain reaction (PCR)-based, single primer DNA fingerprinting methods with 3 different primers: 1 enterobacterial repetitive intergenic consensus PCR and 2 arbitrarily primed PCRs. The PCR products were analyzed by agarose slab gel and microchip gel electrophoresis. RESULTS: Of the 100 clinical isolates tested, 39% (4%, 14%, and 21%) were found to be serotypes 0:3, 0:6, and 0:11, respectively. Twelve strains were chosen for DNA analysis by PCR. The PCR products were analyzed by agarose slab gel electrophoresis and on microchips to determine interspecies diversity. Both methods demonstrated that different serotypes exhibited different electrophoretic patterns. Two strains (clinical strains 6 and 7, serotype 0:6) showed identical patterns, indicating a high degree of relatedness. CONCLUSION: In all cases, there was concordance between the electrophoretic patterns detected by the two methods. The capability of conducting both PCR and microchip gel electrophoresis offers an opportunity for an automated and rapid method for genetic analysis and differentiation among strains of P. aeruginosa and other microorganisms.

Bacterial Typing Techniques↗
PubMed2000

A randomized controlled trial comparing topical piroxicam gel with a homeopathic gel in osteoarthritis of the knee.

OBJECTIVE: : To evaluate the efficacy and safety of a homeopathic gel vs an NSAID (piroxicam) gel in the treatment of osteoarthritis of the knee. METHOD: : One hundred and eighty-four out-patients with radiographically confirmed symptomatic osteoarthritis of the knee were entered into a pragmatic, randomized, double-blind controlled trial and treated with 1 g of gel three times daily for 4 weeks. Main outcome measures were pain on walking as a Visual Analogue Score (VAS) and a single-joint Ritchie index. RESULTS: : One hundred and seventy-two of the 184 enrolled patients had endpoints for the main outcome parameters. The pain reduction was 16.5 mm VAS in the homeopathy group (n = 86) and 8.1 mm in the piroxicam group (n = 86); the difference between treatment groups was 8.4 mm (95% confidence interval 0.8-15.9), and after adjustment for pain at baseline it was 6.8 mm (95% confidence interval -0.3 to 13.8). There was no significant difference between treatment groups in the single-joint Ritchie index (P = 0.78). Adverse events occurred in 28 patients (12 homeopathy group, 5 withdrawn; 16 piroxicam group, 9 withdrawn); 18 of the events involved a local reaction (7 homeopathy group, 2 withdrawn; 11 piroxicam group, 5 withdrawn). CONCLUSION: : The homeopathic gel was at least as effective and as well tolerated as the NSAID gel. The presence of a clinically relevant difference between treatment groups cannot be excluded. The homeopathic gel supplemented by simple analgesics if required may provide a useful treatment option for patients with osteoarthritis.

Administration, Topical↗
PubMed1997

Use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis to resolve mRNA and its protein product in one gel.

We demonstrate that it is possible to simultaneously resolve both an mRNA and its protein product by electrophoresis in a single SDS-polyacrylamide gel by using double labeling with [32P]H3PO4 and [35S]methionine, and an elongated 5% stacking gel atop the 10% resolving gel. The mRNA is resolved in the 5% gel; the protein, as expected, resolves in the 10% gel. Using a T7 expression system, we show that putative mRNA bands in the 5% gel are: 1) labeled only with 32P and not with 35S; 2) inducible with isopropylthiogalactopyranoside (needed to induce a T7 RNA polymerase gene under control of a lac promoter); 3) synthesized in the presence of rifampicin (T7 RNA polymerase is not inhibited by rifampicin); 4) degraded by base or RNase treatment; and 5) are largely resistant to DNase treatment. The mRNA bands were also evident in samples not treated with rifampicin. We used this technique to confirm previously published results that inhibition of expression by consecutive low-usage AGG arginine codons inserted near the 5' end of a test message in Escherichia coli is at the level of translation.

Autoradiography↗
PubMed2002

Silicone gel breast implant failure: evaluation of properties of shells and gels for explanted prostheses and meta-analysis of literature rupture data.

After 30 years of clinical use, the 1992 Food and Drug Administration moratorium on silicone gel breast implants (SGBIs) resulted from a paucity of scientific data concerning their safety. The frequency of rupture and reoperative procedures was not known, nor were reliable data available for changes in the physical properties of shells and the composition of gels that might lead to SGBI failure. For this reason the authors conducted large-cohort meta-analyses of failure data for SGBIs based on numerous literature reports and also investigated systematically shell and gel properties from explanted SGBIs. They report their failure analysis data for more than 9,770 SGBIs (an update of an earlier study of more than 8,000 implants) as well an examination of the properties of shells and gels for 74 explanted SGBIs that ranged in age from 2 to 19 years (mean implanted age, 9.9 years). The explants tested were from several different manufacturers. For the modest-size explant cohort that was tested, 31 of 74 implants (42%) were found to be ruptured (some extensively). Even many intact shells were so weakened that only 51 shells had sufficient strength to enable preparation of samples for testing of mechanical properties and for analysis of composition by solvent extraction. Shells were found to contain 15 to 25% of extractable silicone. Exhaustive extraction of gels showed that they actually contained very little crosslinked silicone--85 to 95% being extractable soluble silicone fluid. Tensile and tear strengths of explanted silicone elastomer shells were lower than unimplanted prostheses and were generally well below reported manufacturers' values. This updated large-cohort failure analysis continues to show that shell rupture is related directly to implant duration (e.g., from analysis of variance statistics, 26% failure at 3.9 years, 47% at 10.3 years, 69% at 17.8 years; < or = 0.001). However, for the relatively small series of explants for which physical property data are reported, no significant correlation was observed between implant duration and the degradation of implant strength. It therefore appears most reasonable to conclude that after early weakening of shells as a result of swelling of the shell elastomer by diffusion of silicone oil from the gel, SGBI failure can occur in a time-dependent manner as a result of continuing implant motion and cyclic stresses that are exacerbated by stress concentration at thin areas, defects, and folds in the shells.

Breast Implants↗
PubMed2006

A pilot clinical trial comparing an acid-buffering formulation (ACIDFORM gel) with metronidazole gel for the treatment of symptomatic bacterial vaginosis.

AIM: To compare the effectiveness of an acid-buffering formulation gel (ACIDFORM) with metronidazole gel in the treatment of symptomatic bacterial vaginosis (BV). METHODS: After a confirmed diagnosis of BV according to the criteria established by Nugent and Amsel, 30 nonpregnant women were enrolled in a randomized, double-blind clinical study. The women were randomly assigned to receive either 5 g ACIDFORM gel (n = 13) or 10% metronidazole gel (n = 17) intravaginally once daily for five consecutive days. Participants were evaluated in two follow-up visits (7-12 days and 28-35 days after treatment). Therapeutic success was defined as the presence of less than three of Amsel's criteria. If three or more criteria were present at first or second follow-up visit, the woman was excluded from the study and treated orally with metronidazole. Nugent scores were recorded at each visit but these were not used to define cure. RESULTS: At the first follow-up visit, 15 (88%) of the women in the metronidazole group were cured compared with only three (23%) in the ACIDFORM group (P < 0.001). The remaining 12 women (10 of the ACIDFORM group and two of the metronidazole group) were considered as failure and were treated orally with metronidazole. At the second follow-up visit, two of the ACIDFORM-treated women and six of the metronidazole-treated women presented recurrent BV. Four women in the ACIDFORM group and one in the metronidazole group reported occasional burning and itching during product use. CONCLUSION: ACIDFORM gel was significantly less effective than high-dose metronidazole gel for the treatment of symptomatic BV.

Administration, Intravaginal↗
PubMedDate not supplied

Percutaneous treatment of acute soft tissue lesions with naproxen gel and ketoprofen gel.

A randomized independent-group, single-blind study was performed to compare the analgesic efficacy and the local and cosmetic tolerability of 3-5 cm of 10% naproxen gel with 10% ketoprofen gel in 30 patients complaining of moderate or severe pain due to acute soft tissue lesions. Both drugs were administered topically and were applied to the painful area at least once every 12 h as required. Naproxen gel was effective, cosmetically acceptable and safe in the treatment of acute soft tissue lesions. Efficacy and tolerability of both naproxen gel and ketoprofen gel were comparable, although naproxen gel produced a significantly greater reduction in pain on deep palpation by the third day of treatment.

Administration, Topical↗
PubMed2007

Quantitative proteomics for two-dimensional gels using difference gel electrophoresis.

Difference gel electrophoresis (DIGE) technology provides a powerful quantitative component to proteomics experiments involving two-dimensional (2D) gel electrophoresis. DIGE allows for the detection of subtle changes in protein abundance with statistical confidence while controlling for gel-to-gel variation, as well as additional variation that is non-biological in origin (e.g., sample preparation error, normal variation in a system). Samples are differentially labeled with spectrally resolvable fluorescent dyes (Cy2, Cy3, and Cy5) and co-resolved for direct quantification within the same 2D gel. Increased statistical confidence is obtained when combining experimental repetition with internal standards such that independent replicate measurements from single- and multivariable analyses can be intercompared with a relatively small number of coordinated DIGE gels.

Electrophoresis, Gel, Two-Dimensional↗
PubMed2006

[Contraceptive efficacy of bioadhesive benzalkonium chloride gel in comparison with nonoxynol-9 gel].

OBJECTIVE: To compare the contraceptive efficacy of a new spermicide, bioadhesive benzalkonium chloride (BZK) gel, with the traditional nonoxynol (NP-9) gel. METHODS: A total of 240 child-bearing age women volunteers were randomly divided into two groups: 120 using the BZK gel for contraception, and the other 120 using the NP-9 gel. Using life table method and log-rank test, we compared the pregnancy rates and discontinuation rates after follow-up for 6 months in two groups. RESULTS: No abnormal findings of cervical smears were detected before and after this clinical trial in all 240 women. The follow-up rates at 6 months were 100.0% and 99.2% in the BZK group and the NP-9 group, respectively. The 6-month gross cumulative pregnancy rates of typical use were 1.72 and 0.91 per 100 women (P > 0.05), respectively. If we excluded the 2 pregnant women (1 in each group), who did not correctly or consistently use the spermicides for every intercourse, the cumulative pregnancy rates at 6 months in perfect use would be 0.87 and 0 per 100 women (P > 0.05). And the gross cumulative discontinuation rates due to allergy or other adverse reactions at 6 months in typical use were 0 and 2.68 per 100 women (P > 0.05), respectively. CONCLUSION: The contraceptive efficacy of bioadhesive BZK gel is the same as that of the NP-9 gel, and it is more acceptable in clinical use.

Adult↗
PubMed1989

Studies on the techniques of topical application with fluoride gel. 2. Standardization on the amounts of gel applied.

In the previous report, the results of an experiment for utilization of the practically available tray in our effort to introduce a new technique for the application of fluoride gel products to patients were described. Through the experiment, it was found that the groove in the sponge tray is too shallow for the application of gel, and the need for standardization of the proper amount of fluoride gel for application was felt. In the present study, an experiment using an improved version of a ready-made sponge tray was conducted. Simultaneously, the standardization of the amount of gel for application using cotton pellets, sponge tray and custom-fitted tray was attempted with good results. However, problems still remain concerning the way of accommodating the standardized amount of gel in a tray, and how to apply the gel intraorally using the cotton pellets.

Dental Instruments↗
PubMedDate not supplied

A clinical evaluation of piroxicam gel: an open comparative trial with diclofenac gel in the treatment of acute musculoskeletal disorders.

An open, parallel trial was conducted to compare the efficacy and toleration of piroxicam 0.5% gel and diclofenac 1.16% topical gel preparations in the treatment of 173 patients with well-defined, acute sprains and tendinitis of the ankle, shoulder, or elbow. Therapy was begun within three to five days of the injury and continued for up to 14 days. Piroxicam gel was applied to the injured area four times daily by 84 patients and diclofenac gel was similarly applied by 89 patients. Pain, tenderness, and restriction of joint movement were markedly improved with both drugs after three days of treatment. Further improvement was noted after 14 days of treatment and patients generally resumed normal activities in nine days. There was no difference in the response to treatment or in the global impressions of efficacy between piroxicam and diclofenac. Toleration was regarded as good or excellent by 98% of patients receiving piroxicam and 94% of patients receiving diclofenac. There were few adverse effects reported by either group. The type and incidence of these effects were similar for both drugs, with the majority consisting of mild or moderate local skin reactions at the site of application. The results of this study show that piroxicam 0.5% gel and diclofenac 1.16% gel are equally effective and well tolerated in the treatment of selected acute sprains and tendinitis.

Acute Disease↗
PubMed1990

Drying acrylamide slab gels for fluorography without using gel drier and vacuum pump.

A method for drying acrylamide slab gels for fluorography without using a gel drier and a vacuum pump is described. The method involves the use of inexpensive acrylic frames, cellophane, and plastic supplies. The fluorographs obtained from gels dried by this method are comparable to those obtained using a gel drier and a vacuum pump. Several gels can be dried by this method simultaneously at room temperature. The method is less time consuming and is economical and practically crack free.

Acrylamide↗
PubMed1981

Investigation of gel structure of aluminum hydroxycarbonate gel using a tension cell.

A tension cell was designed to measure the gel structure of aluminum hydroxycarbonate gel. Equilibrium measurements of the total water outflow versus applied tension given insight into the rigidity of the gel structure. Dynamic measurements of the rate of outflow of water at various applied tensions yield the capillary conductivity of the gel, which is related to the apparent surface area, particle size, and porosity. An aluminum hydroxycarbonate gel with a high apparent viscosity exhibited an increase in viscosity upon aging at 25 degrees, which was accompanied by an increase in the equilibrium tension of the water phase, an increase in delta (-)GH2O, and a decrease in capillary conductivity. In contrast, the apparent viscosity of a low viscosity aluminum hydroxycarbonate gel, which was precipitated from the same reagents but with different precipitation temperature, pH, and stirring speed, exhibited a decrease in equilibrium water tension, a decrease in delta (-)GH2O, and an increase in capillary conductivity during aging at 25 degrees.

Aluminum Hydroxide↗