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At least 325 records · Page 18Linked to original sources

PubMed1998

The effects of custom tray material on the accuracy of master casts.

PURPOSE: The accuracy of master cast reproduction by a polyvinylsiloxane impression material using two visible-light-curing resin and an autopolymerizing polymethyl methacrylate resin custom tray materials was investigated. MATERIALS AND METHODS: Custom trays were fabricated from a master cast that had three index points marked on both the inner and outer vestibules. Impressions were made of the master cast using Extrude and then poured in Die Keen Green stone. The distances between the reproduced index points were measured to +/- 0.01 mm with a traveling microscope and the algebraic norms calculated for each tray material. RESULTS: No differences (p > .05) were found in the dimensions of the inner index points, while the separations of the outer index points indicated that there were differences in the accuracy of reproduction (p < .01) by the three tray materials. The index points reproduced on the casts, compared with the master cast, were closer together for the Triad Blue trays than for the TruTray and Ontray impression trays. CONCLUSIONS: All three tray materials produced acceptable casts, but the greatest accuracy was achieved with TruTray, followed by Ontray. Triad Blue produced casts that were slightly smaller than the master. In practice, the small measured differences in cast dimensions may not have clinical significance.

Analysis of Variance↗

PubMed2004

In vivo study of different ointments for drug delivery into oral mucosa by EPR oximetry.

The aim of the present study was to determine the rate of transport and long-term effect of a drug applied to the oral mucosa in different ointments. Three ointments with bioadhesive properties: Orabase, Carbopol 935P, and polymethyl methacrylate (PMM) and the ointment Miglyol without such properties were used. Benzyl nicotinate (BN) was used as an active ingredient that causes hyperemia. The kinetics of drug action was measured by electron paramagnetic resonance (EPR) oximetry in vivo using the paramagnetic probe (Lithium phthalocyanine) implanted beneath the epithelium of the buccal mucosa in rats. EPR spectra line-width was proportional to local changes of partial pressure of oxygen (pO(2)) in tissue and was monitored for 90 min after the application of ointments mixed with BN. The greatest increase in pO(2) and the highest efficiency of drug action was observed after the application of 2% BN in PMM (P<0.01). Additionally in PMM the drug effect increased linearly with BN concentration up to 3%, at higher concentrations (3.5 and 4% BN) no further effect was observed. The results demonstrated that the greatest and the longest effect caused by a hyperemic drug in PMM. By increasing the concentration of the drug in PMM higher pO(2) in the oral mucosa can be established but only until the saturation is reached.

Acrylates↗

PubMed2002

Seoul-type keratoprosthesis: preliminary results of the first 7 human cases.

OBJECTIVE: To evaluate the clinical efficacy of a newly designed Seoul-type keratoprosthesis (S-KPro). METHODS: The S-KPro, which consists of a polymethyl methacrylate optic, a skirt (polyurethane or polypropylene), and polypropylene haptics, was developed and implanted into 2 unsighted and 5 sighted eyes of 7 patients. One patient had a chemical burn, another had an ocular pemphigoid, and the remainder were diagnosed as having Stevens-Johnson syndrome. The preoperative visual acuities ranged from light perception to hand motions. The average follow-up time was 25.6 months. MAIN OUTCOME MEASURES: We evaluated anatomical stability, visual acuity, retinal status, and the visual field. RESULTS: At the last follow-up visit, the S-KPro was well placed in 6 patients. The best-corrected visual acuities of the sighted patients ranged from 20/100 to 20/60 in the affected eye. One patient each experienced retinal detachment or endophthalmitis. Partial extrusion was found in the patient with glaucoma. A retroprosthetic membrane was detected in 1 patient and was treated with an Nd:YAG laser. No glaucomatous visual field defects were found in any of the sighted patients. CONCLUSIONS: Anatomical success was achieved in 6 of 7 eyes. In 3 of the 5 sighted eyes, the S-KPro could rehabilitate corneal blindness not correctable with keratoplasty.

Adult↗

PubMed2003

In vitro resistance of reinforced interim fixed partial dentures.

STATEMENT OF PROBLEM: Comprehensive restorative dental treatment often necessitates the use of interim fixed partial dentures (FPDs) with high stiffness, especially in long-span restorations or areas of heavy occlusal stress. PURPOSE: This in vitro study evaluated the fracture load of interim FPDs made with various materials and span lengths. MATERIAL AND METHODS: Groups (n = 3) of interim FPDs were fabricated with prosthodontic resin materials on 2 abutments with 3 different pontic widths of 3 units (12 mm), 4 units (19 mm), and 5 units (30 mm). The following materials were tested: (1) a thermoplastic polymer (Promysan Star), (2) Promysan Star with a veneering composite (Vita Zeta), (3) a nonimpregnated polyethylene fiber reinforced resin (Ribbond) with a veneering composite (Sinfony), (4) an impregnated fiber reinforced composite system (Targis/Vectris), and (5) a conventional polymethyl methacrylate, Biodent K+B, (control group). After 5000 thermocycles in 2 water baths at 5 degrees and 55 degrees C, the FPDs were temporarily fixed with a provisional cement on the corresponding abutments and subjected to 3-point bending until fracture by a universal testing machine. Statistical analysis consisted of an analysis of variance (ANOVA, 1-way, 2-way) and Bonferroni-Dunn's multiple comparisons post hoc analysis for test groups (alpha = .05). RESULTS: Fracture resistance (N) differed significantly for 3 (mean: 640 +/- 146 N), 4 (626 +/- 229 N), and 5 unit (658 +/- 98 N) Targis/Vectris FPDs compared with the corresponding Promysan (284 +/- 21 N to 125 +/- 73 N), Biodent K+B (247 +/- 91 N to 218 +/- 85 N), and Promysan/Vita Zeta (95 +/- 15 N to 82 +/- 6 N) groups (P < .05). Significant differences were obtained for the 4 and 5 unit Targis/Vectris FPDs compared with the Sinfony/Ribbond FPDs (281 +/- 25 N - 252 +/- 74 N) for the corresponding pontic spans. CONCLUSION: Within the limitations of this in vitro study the impregnated fiber reinforcement may considerably enhanced the fracture resistance of interim FPDs of different span lengths.

Analysis of Variance↗

PubMed2004

A 1-year study on carbon, titanium surface-modified intraocular lens in rabbit eyes.

PURPOSE: To evaluate biocompatibility of Carbon (C) and Titanum (T) surface modified Polymethyl-methacrylate (PMMA) Intraocular Lens (IOLs) in pseudophakic rabbit model. METHODS: Extracapsule Cataract Extraction (ECCE) and IOLs implantation were performed in Japanese albino rabbit eyes. The white cell concentration from the aqueous humor in the eyes was counted within 3 months post operation. The inflammatory cells in the eyes were noted and graded by slit lamp using a semiquantitive scale up to 1-year post operation. The rabbit eyes were inspected under light microscopy, where pathology of the eyes was caracterized. RESULTS: The white cell concentration in the aqueous humor was significantly attenuated in C and T IOL-implanted eyes compared with PMMA IOL-implanted eyes 1 week post operation. The exudate levels in the anterior ocular chamber and the posterior synechias were significant lower in T IOL-implanted eyes than in PMMA IOL-implanted eyes 1 week and 2 weeks after surgery. The exudate levels in the anterior chambers and the posterior synechias were not significantly different in C IOL-implanted versus PMMA IOL-implanted eyes. CONCLUSIONS: This in vivo study provides evidence of effectiveness of Carbon and Titanium IOLs in improving the biocompatibility of PMMA IOLs.

Animals↗

PubMed2004

Effect of PMMA cement radical polymerisation on the inflammatory response.

The effect of the radical polymerisation taking place during the hardening of the polymethyl methacrylate (PMMA) bone cements is known to cause bone necrosis through the relatively high exothermic reaction and the leaching of toxic non reacted monomers. The inflammatory response towards this class of cements has also been shown and ascribed mainly to the phagocytosis of the material particles. However, the effect of the radical polymerisation on the adsorption of plasma proteins and on the activation of monocytes/macrophages when the material is in a non-phagocytosable dimension has not been elucidated. In the present work, the polymerisation of three bone cements, CMW-1, Palavit and Simplex-P in a clinically reflective environment and its effect on the formation of a surface conditioning film as well as on the inflammatory cell activation were investigated. The data showed that on CMW and Simplex-P the polymerisation was not fully accomplished. CMW released high levels of non-reacted monomers, no significant macrophage adhesion and high oxidative burst and cytokine production. The relatively lower levels of released monomers in Simplex and Palavit seemed to promote a lower inflammatory response while cell adhesion was favoured by patches of plasma components entrapped in the hardening dough during the polymerisation.

Bone Cements↗

PubMed1998

Failure of total hip arthroplasty with a precoated prosthesis. 4- to 11-year results.

A series of early femoral component failures prompted a detailed retrospective clinical and radiographic review of 176 hybrid cemented total hip arthroplasties using a polymethyl-methacrylate coated femoral prosthesis. All surgeries were performed using third generation cement techniques. Average length of followup was 6.3 years (range, 3-12 years). Twenty-one patients died, and one underwent revision surgery because of sepsis. Of the remaining 154 total hip arthroplasties, 23 (15%) of the femoral components failed (21 revised, two definitely loose). The average time to revision was 3.9 years. None of the acetabular components failed. Comparison between the failure and nonfailure groups revealed that poor cement mantles (Grades C or D) with distal cement mantle deficiencies were statistically significant predictors of femoral failure. The most common mechanism of failure was progressive, circumferential cement-bone interface osteolysis with relative preservation of the cement-metal interface. Debonding of the cement column from the prosthesis was a late finding and occurred in only 45% of failed cases. Incorporating the techniques of centralization and centrifugation significantly improved clinical results. Strengthening of the cement-prosthesis interface may magnify the deleterious effects of a poor cement mantle and predisposes the cement-bone interface to failure.

Aged↗

PubMed2002

Floating microparticles based on low density foam powder.

The aim of this study was to develop a novel multiparticulate gastroretentive drug delivery system and to demonstrate its performance in vitro. Floating microparticles consisting of (i) polypropylene foam powder; (ii) verapamil HCl as model drug; and (iii) Eudragit RS, ethylcellulose (EC) or polymethyl methacrylate (PMMA) as polymers were prepared with an O/W solvent evaporation method. The effect of various formulation and processing parameters on the internal and external particle morphology, drug loading, in vitro floating behavior, in vitro drug release kinetics, particle size distribution and physical state of the incorporated drug was studied. The microparticles were irregular in shape and highly porous. The drug encapsulation efficiency was high and almost independent of the theoretical loading. Encapsulation efficiencies close to 100% could be achieved by varying either the ratio 'amount of ingredients: volume of the organic phase' or the relative amount of polymer. In all cases, good in vitro floating behavior was observed. The release rate increased with increasing drug loading and with decreasing polymer amounts. The type of polymer significantly affected the drug release rate, which increased in the following rank order: PMMA<EC<Eudragit RS. A broad spectrum of release patterns could be obtained with the investigated formulations. In contrast, the effect of the volume of the aqueous phase on drug release was not very pronounced. The size of the microparticles was almost independent of the drug loading, but strongly depended on the amount of polymer. The drug was partly dissolved and partly in the amorphous form distributed throughout the system.

Drug Compounding↗

PubMed2005

Chemoattraction of inflammatory cells by various intraocular lens materials.

PURPOSE: To compare the chemotactic activity induced by polymethyl methacrylate (PMMA), acrylic, and silicone intraocular lens (IOL) materials, regardless of the surgical and host factors. METHODS: The chemotactic effect of five different IOLs was studied using a modified multi-well Boyden chamber. Two different non-coated PMMA IOLs, a heparin-coated PMMA IOL, an acrylic IOL, and a silicone IOL were assessed. Each mean migration distance of the IOLs was compared with the others using Student's t test. RESULTS: All IOLs induced some amount of leukocyte chemotaxis. There was no statistically significant difference between the chemotactic activity of PMMA IOLs. However, chemotactic activity was significantly higher in acrylic (p<0.05) and silicone (p<0.05) IOLs compared to one of the PMMA lenses. CONCLUSIONS: This limited study has proven that chemotaxis assay is a useful tool to assess the biocompatibility of IOLs. The IOL material itself might attract inflammatory cells to its surface in the absence of surgical and host factors. As PMMA IOLs do not cause an increase in inflammatory reaction, they may be considered safe to use. Further improvement in chemical composition and surface characteristics of IOLs should reduce the inflammatory reaction and increase the biocompatibility and safety of IOLs.

Acrylic Resins↗

PubMed2004

Apical clearance rigid contact lenses induce corneal steepening.

PURPOSE: Anecdotal reports suggest that steeply fitted rigid contact lenses can induce corneal steepening and myopic shifts in refraction. This study investigated changes in corneal topography, corneal thickness, and refraction after short-term wear of apical clearance lenses. METHODS: : Ten young adults participated in the study in which apical clearance lenses (Conoid, Hydron Pty. Ltd., Frenchs Forest, NSW, Australia), fitted approximately 0.3 mm steeper than the flattest keratometric reading, were worn for 4 h. A polymethyl methacrylate (PMMA) lens was worn in one eye, and a Boston XO lens (Bausch & Lomb, Rochester, NY) was worn in the other. Lenses were nonfenestrated in the first trial, and a single midperipheral fenestration was incorporated for a second trial. Corneal topography was monitored using the EyeSys topographic analysis system (EyeSys Vision, Inc., Houston, TX); central corneal thickness was quantified using ultrasonic pachometry; and refraction and anterior ocular response were also monitored. RESULTS: Significant central corneal edema (8.2 +/- 2.2%) was demonstrated in the PMMA lens-wearing eye only. Fenestration did not reduce the edema response. We found significant corneal steepening over a 5- to 6-mm central zone, which was more pronounced in the PMMA lens-wearing eye and was modified by lens fenestration. The curvature changes altered central corneal shape from prolate (Q = -0.06 +/- 0.10) to oblate (Q = -0.26 +/- 0.31). A slight myopic shift in refraction (-0.38 +/- 0.60 D) was found with the PMMA lenses only. CONCLUSIONS: : Apical clearance lenses induce corneal steepening after short-term wear. Although corneal molding is implicated as the primary factor driving the shape change, corneal edema and postlens tear film pressures can modify this response.

Adult↗

PubMed2006

FTIR studies of PVC/PMMA blend based polymer electrolytes.

The polymer electrolytes composing of the blend of polyvinyl chloride-polymethyl methacrylate (PVC/PMMA) with lithium triflate (LiCF3SO3) as salt, ethylene carbonate (EC) and dibutyl phthalate (DBP) as plasticizers and silica (SiO2) as the composite filler were prepared. FTIR studies confirm the complexation between PVC/PMMA blends. The CCl stretching mode at 834 cm-1 for pure PVC is shifted to 847 cm-1 in PVC-PMMA-LiCF3SO3 system. This suggests that there is interaction between Cl in PVC with Li+ ion from LiCF3SO3. The band due to OCH3 at 1150 cm-1 for PVC-PMMA blend is shifted to 1168 cm-1 in PVC-PMMA-LiCF3SO3 system. This shift is expected to be due to the interaction between Li+ ion and the oxygen atom in PMMA. The symmetric vibration band and the asymmetric vibration band of LiCF3SO3 at 1033 and 1256 cm-1 shifted to 1075 and 1286 cm-1 in the DBP-EC plasticized PVC-PMMA-LiCF3SO3 complexes. The interaction between Li+ ions and SiO2 will lead to an increase in the number of free plasticizers (which does not interact with Li+ ions). When the silica content increases from 2% to 5%, the intensity of the peak at 896 cm-1 (due to the ring breathing vibration of free EC) increases in PVC-PMMA-LiCF3SO3-DBP-EC system.

Dibutyl Phthalate↗

PubMed1999

Pathology findings with acrylic implants.

We report the pathological findings in cases of acrylic implants obtained by direct intratumoral injection of polymethyl-methacrylate (PMMA) and N-butyl-cyano-acrylate (NBCA). Direct intratumoral injection of acrylic implants was performed for a variety of primary and secondary bone lesions. These types of treatments have been used at our institution in the last 4 years for 40 vertebroplasty (PMMA) procedures and for nine bone lesions of other locations (PMMA, NBCA). Postmortem histology became available for 1 case of PMMA and for 5 cases with NBCA intratumoral acrylic implants. The pathological findings associated with PMMA and NBCA were evaluated and compared. PMMA exhibited a macroscopic and microscopic rim of tumor necrosis, 6 months after implantation. NBCA exhibited compressive effects on the nearby tumor tissue, however, without signs of significant necrosis outside the acrylic tumor cast. Tumor captured inside the acrylic cast showed extensive to near complete necrosis. Acrylic implants may lead to necrosis when injected directly in tumors. The necrotizing effect may extend beyond the limits of an implant in the case of PMMA. Such an extended effect of PMMA, when compared with NBCA, may be due to the variable toxicity of acrylic implants, including the different degrees of the exothermic reaction during polymerization.

Adenocarcinoma↗

PubMed2000

In vitro determination of contact areas in the normal elbow joint of dogs.

OBJECTIVE: To evaluate areas of articular contact of the proximal portions of the radius and ulna in normal elbow joints of dogs and the effects of axial load on size and location of these areas. SAMPLE POPULATION: Forelimbs obtained from cadavers of 5 adult mixed-breed dogs. PROCEDURE: After forelimbs were removed, liquid-phase polymethyl methacrylate was applied to articular surfaces of the elbow joint, and limbs were axially loaded. Articular regions void of casting material were stained with water-soluble paint. Relative articular contact areas were determined by computer-assisted image analyses of stained specimens. Repeatability of the technique was evaluated by analyses of casts from bilateral forelimbs of 1 cadaver. Incremental axial loads were applied to left forelimbs from 4 cadavers to determine effects of load on articular contact. RESULTS: Specific areas of articular contact were identified on the radius, the craniolateral aspect of the anconeus, and the medial coronoid process. The medial coronoid and radial contact areas were continuous across the radioulnar articulation. There was no articular contact of the medial aspect of the anconeus with the central trochlear notch. Coefficients of variation of contact areas between repeated tests and between contralateral limbs was < 20%. Significant overall effects of axial load on contact area or location were not identified. CONCLUSIONS: Three distinct contact areas were evident in the elbow joint of dogs. Two ulnar contact areas were detected, suggesting there may be physiologic incongruity of the humeroulnar joint. There was no evidence of surface incongruity between the medial edge of the radial head and the lateral edge of the medial coronoid process.

Animals↗

PubMed2005

Liquid phase coating to produce controlled-release alginate microspheres.

This study explored a liquid phase coating technique to produce polymethyl methacrylate (PMMA)-coated alginate microspheres. Alginate microspheres with a mean diameter of 85.6 microm were prepared using an emulsification method. The alginate microspheres, as cores, were then coated with different types of PMMA by a liquid phase coating technique. The release characteristics of these coated microspheres in simulated gastric (SGF) and intestinal (SIF) fluids and the influence of drug load on encapsulation efficiency were studied. The release of paracetamol, as a model hydrophilic drug, from the coated microspheres in SGF and SIF was greatly retarded. Release rates of Eudragit RS100-coated microspheres in SGF and SIF were similar as the rate-controlling polymer coat was insoluble in both media. Drug release from Eudragit S100-coated microspheres was more sustained in SGF than in SIF, due to the greater solubility of the coating polymer in media with pH greater than 7.0. The drug release rate was affected by the core:coat ratio. Drug release from the coated microspheres was best described by the Higuchi's square root model. The liquid phase coating technique developed offers an efficient method of coating small microspheres with markedly reduced drug loss and possible controlled drug release.

Acetaminophen↗

PubMedDate not supplied

A simplified method of opacifying and mixing acrylic cement for percutaneous vertebroplasty: a clinical and in vitro study.

The objective of this study was to simplify the opacifying mixing process of the bone cement and contrast used for percutaneous vertebroplasty (PVP). We performed a biomechanical study of polymethyl methacrylate (PMMA) (Corinplast 3) using three different mixtures of PMMA, monomer, and contrast: group I, 2:1; group II, 3:2; group III, 3:2:1 ratio of powder/monomer/iodinated contrast (Omnipaque). In vitro biomechanical testing of ultimate compressive strength was carried out in all samples. Following the conclusion of a proper bone cement mixture regimen drawn from the in vitro study, PVP was performed in 125 patients: 58 with cancer, 12 with hemangioma, and 54 with osteoporotic fracture. The ultimate compressive strength in group III was decreased by 38% compared to groups II and I. Proper fluoroscopic visualization was achieved in all PVP procedures using this mixture. There were no major complications associated with injection of the cement mixture. Complete (CR) and partial response (PR) was obtained in 64% and 32.8%, respectively. No further vertebral collapse occurred during follow-up. The regimen using iodinated contrast for cement visualization during PVP provides a simple and convenient new method for mixing. Although the biomechanical strength is altered by the contrast medium added, it seems insignificant in clinical practice based on the authors' limited experience.

Adolescent↗

PubMed2002

Percutaneous vertebroplasty for the treatment of osteoporotic vertebral compression fractures: a preliminary report.

BACKGROUND: This report assesses the efficacy and safety of percutaneous vertebroplasty for osteoporotic vertebral compression fractures and reports on preliminary results of its use. METHODS: The technique was used on 50 patients with 86 painful vertebral fractures, all of which had failed to respond to earlier conservative medical treatment. The technique involves percutaneous puncture of the involved vertebra via a transpedical approach followed by injection of polymethyl methacrylate (PMMA) into the compressed vertebra. Patients were asked to quantity their degree of pain on Huskisson's visual analogue scale (VAS) to assess the clinical symptoms and surgical results. RESULTS: The procedures were technically successful in all patients, and no complications relating to either the anesthesia or the surgical procedure were reported. The quantity of PMMA injected per vertebral body varied from 2.5 to 12 ml according to both the position of the damaged vertebra(e) and the severity of the compression fracture. Pain, as assessed on the Huskisson's VAS, decreased from 82 +/- 15 mm at the baseline to 37 +/- 22 mm on the first postoperative day, and 32 +/- 19 mm at 1 month. Reductions in pain from the baseline to the first day and to 1 month were both statistically significant (p < 0.05). All patients were able to return to their previous activity and quality of life. CONCLUSION: Through the expertise and attention of experienced surgeons, percutaneous vertebroplasty appears to provide a very good surgical choice for patients with vertebral compression fractures, as this surgical procedure is able to eliminate the risk of major spinal surgery, and through prompt pain relief, may provide early mobilization and rehabilitation for elderly polymorbid patients.

Adult↗

PubMed2006

Expression of ADAM9 (meltrin-gamma) around aseptically loosened total hip replacement implants.

OBJECTIVE: To investigate the involvement of a disintegrin and the metalloproteinase ADAM9 (meltrin-gamma) in the formation of multinuclear giant cells and osteoclasts in aseptic loosening of hip replacement implants. METHODS: We used in situ hybridization, immunohistochemical staining and western blotting of interface membrane surrounding loosened hip implants, macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor kappaB ligand (RANKL) costimulation and polymethyl methacrylate (PMMA) particle stimulation of human monocytes followed by immunofluorescence staining and flow cytometric analysis. RESULTS: Morphometric analysis revealed that the ADAM9+ area in the revision total hip replacement (THR) interface was larger than in primary THR samples (37.6+/-5.1 vs 5.2+/-0.8%, P=0.002). Double immunofluorescence staining showed that CD68+ interface tissue macrophages and multinuclear giant cells were ADAM9+. ADAM9 mRNA containing mononuclear and multinuclear cells was often seen in a close spatial relationship with other ADAM9+ cells. Western blotting disclosed a 50 kDa ADAM9 band in tissue extracts. Upon M-CSF and RANKL costimulation of human monocytes, the ADAM9 staining pattern changed over time and ADAM9+ cells formed bi- and multinuclear cells. Flow cytometry disclosed that cells of the monocyte/macrophage lineage changed from ADAM9-negative cells into strongly positive cells during a 3-day culture. CONCLUSION: ADAM9 is expressed in interface tissues around aseptically loosened THR implants. ADAM9 may play a role as a fusion molecule in the formation of multinuclear giant cells and osteoclasts from mononuclear precursors in diseases characterized by bone tissue destruction.

ADAM Proteins↗

PubMed1999

Assessment of an automated solid phase competitive fluoroimmunoassay for benzoylecgonine in untreated urine.

A new solid phase fluoroimmunoassay using a fully automated flow fluorometer adapted for urinalysis of drug metabolites is described. Fluorescein-conjugated benzoylecgonine (FL-BE) and monoclonal antibodies (mAb) against benzoylecgonine (BE) were the reagents used for demonstration. The solid phase consisted of anti-BE mAbs immobilized on the surface of polymethyl methacrylate (PMMA) beads. Free BE in solution competed with FL-BE and reduced bead-bound fluorescence in a concentration-dependent manner. The binding of FL-BE to the anti-BE mAb reached steady-state within minutes. FL-BE was not bound by uncoated beads nor beads coated with non-specific proteins or IgG. The signal-to-noise ratio was 33, and the sensitivity of the assay was 2 ng ml(-1) for BE. The effective concentration of BE was 1 to 100 ng ml(-1), with an IC50 value of 12 ng ml(-1). The mAb showed equal affinities for BE, cocaine, and cocaethylene, but a five order-of-magnitude lower affinity for ecgonine and ecgonine methylester. In a double-blind comparison using clinical urine samples, the data from this single-step competitive assay had excellent agreement with results obtained using a fiber-optic biosensor (FOB), and the EMIT assay performed commercially. The assay provided kinetic data rapidly and can be used to detect small analytes for which antibodies and fluorescein conjugates are available. The affinity of the mAb for FL-BE, calculated from kinetic analysis of the time course of the on and off reaction, was 2.25 x 10(-9) M.

Antibody Affinity↗