Elution Characteristics Research Articles

Application of Multi-Layered Temperature-Responsive Polymer Brushes Coating on Titanium Surface to Inhibit Biofilm Associated Infection in Orthopedic Surgery

Infection associated with biomedical implants remains the main cause of failure, leading to reoperation after orthopedic surgery. Orthopedic infections are characterized by microbial biofilm formation on the implant surface, which makes it challenging to diagnose and treat. One potential method to prevent and treat such complications is to deliver a sufficient dose of antibiotics at the onset of infection. This strategy can be realized by coating the implant with thermoregulatory polymers and triggering the release of antibiotics during the acute phase of infection. We developed a multi-layered temperature-responsive polymer brush (MLTRPB) coating that can release antibiotics once the temperature reaches a lower critical solution temperature (LCST). The coating system was developed using copolymers composed of diethylene glycol methyl ether methacrylate and 2-hydroxyethyl methacrylate by alternatively fabricating monomers layer by layer on the titanium surface. LCST was set to the temperature of 38-40 °C, a local temperature that can be reached during infection. The antibiotic elution characteristics were investigated, and the antimicrobial efficacy was tested against S. aureus species (Xen29 ATCC 29 213) using one to four layers of MLTRPB. Both in vitro and in vivo assessments demonstrated preventive effects when more than four layers of the coating were applied, ensuring promising antibacterial effects of the MLTRPB coating.

Étude in vitro de la cinétique d’élution et de l’activité biologique de la pipéracilline/tazobactam et de la gentamicine dans du ciment osseux acrylique

BackgroundAntibiotics differ in their elution characteristics from bone cement. But no such data is available on piperacillin and tazobactam. Therefore, we performed an in vitro observational study to examine: (1) in-vitro elution characteristics of piperacillin and tazobactam from bone cement, (2) their biological activity using minimum inhibitory concentration and (3) elution characteristics and biological activity when combined with gentamicin in bone cement. HypothesisThe null hypothesis was that piperacillin and tazobactam after elution from bone cement can achieve concentrations higher than minimum inhibitory concentration. Material and methodsForty milligrams bone cement was mixed with the following combination of antibiotics: without any antibiotic (Sample A, Control), 4g/0.50g piperacillin/tazobactam (Sample B), 6g/0.75g piperacillin/tazobactam (Sample C), 8g/1.0g piperacillin/tazobactam (Sample D) and 4g/0.50g piperacillin/tazobactam and 400mg gentamicin (Sample E). Samples were analysed on reverse-phase ultra-high-performance liquid chromatography. Antibacterial activity in the elute were tested against standard ATCC (American Type Culture Collection) strains. ResultsDetectable drug elution for piperacillin and tazobactam was seen till 21 days. Peak drug levels for all formulations were seen at 48hours (140.8 and 297.5μg/ml for Samples B of piperacillin and tazobactam respectively). About 0.83–1.24% of piperacillin and 23.17-29.17% of tazobactam were released from the samples. Gentamicin improved elution of piperacillin and tazobactam: 140.8 vs 919.9μg/ml (p = 0.000) for Samples B and E of piperacillin respectively and 297.5 and 1138.4μg/ml (p = 0.001) for Samples B and E of tazobactam respectively at 2 days. Sample E showed complete inhibition of tested microorganisms, while B sample was microbiologically less active compared to E on day 5. ConclusionsPiperacillin and tazobactam eluted successfully from bone cement and also retained antimicrobial activity after elution. Maximum elution was seen up to day 2 after which it reduced drastically. Antimicrobial action was seen up to 7 days. Level of evidenceIII; comparative study.

Prospects for Adding Drugs with Known Anti-tuberculosis Activity to the Composition of Bone Cement for Treatment of Tuberculous Arthritis

The objective: to evaluate the possibility of using linezolid, amikacin, levofloxacin and bedaquiline mixed with bone cement for the treatment of patients with tuberculous arthritis taking into account changes in mechanical properties of bone cement, antimycobacterial activity of drugs and characteristics of their release.Subjects and Methods. The antimycobacterial, elution and strength characteristics of bone cement mixed with the drugs known for their anti-tuberculosis activity were studied: linezolid, amikacin, levofloxacin, and bedaquiline. The antimycobacterial effect was evaluated by the minimum inhibitory concentration (MIC) of the reference strain of Mycobacterium tuberculosis H37RV sensitive to anti-tuberculosis drugs (TB drugs). To study the kinetics of elution, the methods of high-performance mass spectrometry and spectrophotometry were used. The strength characteristics were determined using LFM-50 electromechanical testing machine.Results. The obtained results demonstrated satisfactory elution and antimycobacterial parameters for linezolid and amikacin, thus they can be mixed with bone cement, and the cement retained its strength characteristics. Levofloxacin showed antimycobacterial activity only within 1 day after the cement sample was immersed in the solution. Bedaquiline showed negative elution and antimycobacterial characteristics in the cement sample.

Meropenem-loaded Cement Is Effective in Preventing Gram-negative Osteomyelitis in an Animal Model.

Low-dose antibiotic-loaded acrylic cement is routinely used for preventing skeletal infection or reimplantation in patients with periprosthetic joint infections. However, few reports about the selection of antibiotics in acrylic cement for antigram-negative bacteria have been proposed. (1) Does the addition of antibiotics (tobramycin, meropenem, piperacillin, ceftazidime, ciprofloxacin, and aztreonam) to acrylic cement adversely affect compressive strength before and after elution? (2) Which antibiotics have the highest cumulative release within 28 days? (3) Which antibiotics showed antimicrobial activity within 28 days? (4) Does meropenem-loaded cement improve body weight, temperature, and other inflammatory markers compared with control unloaded cement? This is an in vitro study that assessed the mechanical strength, antibiotic elution, and antibacterial properties of antibiotic-loaded cement, combined with an animal study in a rat model that evaluated key endpoints from the animal study. In the in vitro study, we added 2 g of tobramycin (TOB), meropenem (MEM), piperacillin (PIP), ceftazidime (CAZ), ciprofloxacin (CIP), and aztreonam (ATM) to 40 g of acrylic cement. The compressive strength, elution, and in vitro antibacterial properties of the antibiotic-loaded cement were detected. Thirty male rats were randomly divided into two groups: CON (antibiotic-unloaded cement) and MEM (meropenem-loaded cement, which had the most stable antibacterial properties of the six tested antibiotic-loaded cements in vitro within 28 days). The right tibia of all rats underwent arthroplasty and was implanted with the cement, followed by inoculation with Pseudomonas aeruginosa in the knee. General status, serum biomarkers, radiology, microbiological assay, and histopathological tests were assessed over 14 days postoperatively. The compressive strength of all tested antibiotic cement combinations exceeded the 70 MPa threshold (the requirement established in ISO 5833). The cumulative release proportions of the raw antibiotic in cement were 1182.8 ± 37.9 µg (TOB), 355.6 ± 16.2 µg (MEM), 721.2 ± 40.3 µg (PIP), 477.4 ± 37.1 µg (CAZ), 146.5 ± 11.3 µg (CIP), and 372.1 ± 14.5 µg (ATM) within 28 days. Over a 28-day period, meropenem cement demonstrated antimicrobial activities against the four tested gram-negative bacteria ( Escherichia coli , P. aeruginosa , Klebsiella pneumoniae , and Proteus vulgaris ). Ciprofloxacin cement inhibited E. coli growth, ceftazidime and aztreonam cement inhibited K. pneumonia growth, and tobramycin cement inhibited P. aeruginosa . Only meropenem demonstrated antimicrobial activity against all gram-negative bacteria on agar diffusion bioassay. Rats treated with meropenem cement showed improved body weight (control: 280.1 ± 4.2 g, MEM: 288.5 ± 6.6 g, mean difference 8.4 [95% CI 4.3 to 12.6]; p < 0.001), improved knee width (control: 13.5 ± 0.3 mm, MEM: 11.8± 0.4 mm, mean difference 1.7 [95% CI 1.4 to 2.0]; p < 0.001), decreased inflammatory marker (control: 316.7 ± 45.0 mm, MEM: 116.5 ± 21.8 mm, mean difference 200.2 [95% CI 162.3 to 238.2]; p < 0.001), decreased radiographic scores (control: 17.7 ± 2.0 mm, MEM: 10.7± 1.3 mm, mean difference 7.0 [95% CI 5.4 to 8.6]; p < 0.001), improved bone volume/total volume (control: 8.7 ± 3.0 mm, MEM: 28.5 ± 5 .5 mm, mean difference 19.8 [95% CI 13.3 to 26.2]; p < 0.001), decreased Rissing scale scores of the knee gross pathology (control: 3.3 ± 0.5, MEM: 1.1 ± 0.7, mean difference 2.2 [95% CI 1.7 to 2.7]; p < 0.001), decreased Petty scale scores of knee synovium (control: 2.9 ± 0.4 mm, MEM: 0.7 ± 0.7 mm, mean difference 2.1 [95% CI 1.7 to 2.5]; p < 0.001), and decreased bacterial counts of the bone and soft tissues and negative bacterial cultures of cement (p < 0.001, p < 0.001, p < 0.001, p < 0.001, respectively). In this current study, MEM cement had the most stable in vitro antimicrobial activities, effective in vivo activity while having acceptable mechanical and elution characteristics, and it may be an effective prophylaxis against skeletal infection caused by gram-negative bacteria. Meropenem-loaded acrylic cement is a potentially effective prevention measure for skeletal infection caused by gram-negative bacteria; however, more related clinical research is needed to further evaluate the safety and efficacy.

Comparison of three methods for assessment of drug elution: In vitro elution of gentamicin from a collagen-based scaffold

In vitro drug elution experiments are commonly performed when evaluating the fitness of drug delivery devices for in vivo use. Evaluation of drug elution characteristics spans many drug delivery applications including local delivery of antimicrobials and chemotherapeutics, and is of particular interest for prevention and treatment of orthopedic infections. Despite widespread utility, there is little agreement on methodology to perform such studies, and there are recognized limitations in published works. We evaluated three of the most commonly reported in vitro drug elution methods. We utilized a commercially available collagen matrix (Fibro-Gide®, Geistlich) and an antibiotic that is widely used for local antimicrobial therapy (gentamicin). The protocols used are: 1. complete replacement of media and washing of device, 2. complete replacement of media without washing, or 3. partial replacement of media. The results show statistically significant differences in elution characteristics among the three methods utilizing this delivery vehicle and drug. These results may provide the framework for moving toward more consistent methodology for in vitro elution experiments and address certain acknowledged limitations in the literature.

Insight into the liquid adsorption of tobacco specific nitrosamines on ZIF-8

Liquid adsorption of TSNA by ZIF-8 was studied in this paper for the first time, applying the deformable molecular sieve to adsorb and separate TSNA. ZIF-8 can adsorb the bulky NNK molecules whose size exceeds its pore size, whereas NaA and KA zeolites cannot though they have similar pore sizes. Moreover, ZIF-8 selectively adsorbed NNK in solution and reached adsorption equilibrium within 5 min. In contrast, NNN was hard to be adsorbed and easy to be eluted by water, which is useful for the separation of TSNA. The influence of solid-liquid (S/L) ratio and other factors on TSNA liquid adsorption was investigated in detail. When S/L was 0.2, ZIF-8 exerted the highest efficiency and the adsorption capacity per unit surface area reached 12–15 nmol. Through the comparison of adsorption of NNK, NNN and NPYR, it is found that the adsorption of TSNA by ZIF-8 depended on π-π electron interaction mainly, rather than geometric confinement effect. The liquid adsorption curve of NNK conforms to Langmuir isothermal adsorption model, and its saturated adsorption capacity Qm was estimated to be 4.34 mg g−1, but actually it could reach 3.19 mg g−1 only. In addition, ZIF-8 had a mixing effect in liquid adsorption of TSNA: the presence of NNK promoted the adsorption of NNN slightly. ZIF-8 has the characteristics of fast adsorption and easy elution of TSNA in solution, which is beneficial for removal of TSNA to protect the environment and public health.

In vitro study of elution kinetics and biological activity of piperacillin/tazobactam and gentamicin in acrylic bone cement

BackgroundAntibiotics differ in their elution characteristics from bone cement. But no such data is available on piperacillin and tazobactam. Therefore, we performed an in vitro observational study to examine (1) in vitro elution characteristics of piperacillin and tazobactam from bone cement, (2) their biological activity using minimum inhibitory concentration and (3) elution characteristics and biological activity when combined with gentamicin in bone cement. HypothesisThe null hypothesis was that piperacillin and tazobactam after elution from bone cement can achieve concentrations higher than minimum inhibitory concentration. Material and methodsForty milligrams bone cement was mixed with the following combination of antibiotics: without any antibiotic (sample A, control), 4g/0.50g piperacillin/tazobactam (sample B), 6g/0.75g piperacillin/tazobactam (sample C), 8g/1.0g piperacillin/tazobactam (sample D) and 4g/0.50g piperacillin/tazobactam and 400mg gentamicin (sample E). Samples were analysed on reverse-phase ultra-high-performance liquid chromatography. Antibacterial activity in the elute were tested against standard American Type Culture Collection (ATCC) strains. ResultsDetectable drug elution for piperacillin and tazobactam was seen till 21days. Peak drug levels for all formulations were seen at 48hours (140.8 & 297.5μg/mL for samples B of piperacillin and tazobactam respectively). About 0.83–1.24% of piperacillin and 23.17–29.17% of tazobactam were released from the samples. Gentamicin improved elution of piperacillin and tazobactam: 140.8 vs. 919.9μg/mL (p=0.000) for samples B & E of piperacillin respectively and 297.5 & 1138.4μg/mL (p=0.001) for samples B & E of tazobactam respectively at 2days. Sample E showed complete inhibition of tested microorganisms, while B sample was microbiologically less active compared to E on day 5. ConclusionsPiperacillin and tazobactam eluted successfully from bone cement and also retained antimicrobial activity after elution. Maximum elution was seen up to day 2 after which it reduced drastically. Antimicrobial action was seen up to 7days. Level of evidenceIII; comparative study.

Study on Arsenic Elution Characteristics of Excavated Material using Saturated/Unsaturated Column Tests

Study on Arsenic Elution Characteristics of Excavated Material using Saturated/Unsaturated Column Tests

Influence of Tranexamic Acid on Elution Characteristics and Compressive Strength of Antibiotic-Loaded PMMA-Bone Cement with Gentamicin.

Purpose: The topical application of tranexamic acid (TXA) into the joint space during total joint arthroplasty (TJA) with no increase of complications, has been widely reported. We investigated the influence of TXA on antibiotic release, activity of the released antibiotic against a clinical isolate of S. aureus, and compressive strength of a widely used commercially prepared gentamicin-loaded cement brand (PALACOS R + G). Method: 12 bone cement cylinders (diameter and height = 6 and 12 mm, respectively) were molded. After curing in air for at least 1 h, six of the cylinders were completely immersed in 5 mL of fetal calf serum (FCS) and the other six were completely immersed in a solution consisting of 4.9 mL of FCS and 0.1 mL (10 mg) of TXA. Gentamicin elution tests were performed over 7 d. Four hundred µL of the gentamicin eluate were taken every 24 h for the first 7 d without renewing the immersion fluid. The gentamicin concentration was determined in a clinical analyzer using a homogeny enzyme immuno-assay. The antimicrobial activity of the eluate, obtained after day 7, was tested. An agar diffusion test regime was used with Staphylococcus aureus. Bacteria were grown in a LB medium and plated on LB agar plates to get a bacterial lawn. Fifty µL of each eluate were pipetted on 12-mm diameter filter discs, which were placed in the middle of the agar gel. After 24 h of cultivation at 37 °C, the zone of inhibition (ZOI) for each specimen was measured. The compressive strength of the cements was determined per ISO 5833. Results: At each time point in the gentamicin release test, the difference in gentamicin concentration, obtained from specimens immersed in the FCS solution only and those immersed in the FCS + TXA solution was not significant (p = 0.055–0.522). The same trend was seen in each of the following parameters, after 7 d of immersion: (1) Cumulative gentamicin concentration (p < 0.297); (2) gentamicin activity against S. aureus (strongly visible); (3) ZOI size (mostly > 20 mm) (p = 0.631); and (4) compressive strength (p = 0.262). Conclusions: For the PALACOS R + G specimens, the addition of TXA to FCS does not produce significant decreases in gentamicin concentration, in the activity of the gentamicin eluate against a clinical isolate of S. aureus, the zone of inhibition of S. aureus, and in the compressive strength of the cement, after 7 d of immersion in the test solution.

Elution and Containment of Harmful Substances in Construction-Generated Soil: A Case Study of Oshikado Tunnel, Japan

In recent years, there has been an increasing number of cases in Japan where countermeasures against environmental pollution caused by natural heavy metals contained in soil and wastewater generated during construction work have become a problem. For example, when arsenic, which is often used, exceeds 0.01 mg/L, which is the criterion in the elution test, the generated soil is covered with low-permeability (permeability coefficient ≤1×10-6 cm/s) soil mixed with bentonite to prevent heavy metal leakage. Although the impact on the surrounding environment is predicted in the design of such a disposal site, it does not accurately reflect the behavior of leachate in the embankment and the elution characteristics of heavy metals. Therefore, in this study, for the purpose of optimal design of the disposal site, the distribution of heavy metals in the embankment, behavior of leachate, and elution amount of heavy metals were investigated, and a numerical analysis method using the advection-dispersion equation was examined. In addition, a large column test using soil at the site was conducted to reproduce the site. The parameters related to the permeation characteristics obtained from the column test agreed with the field test; however, the unit elution amount, which is a parameter related to the elution characteristics, was 7.5 times that of the field test. This result indicates the possibility of overestimating the elution amount of heavy metals in the test modeling of the disposal site.

Superheated reversed phase chromatography with ultrashort columns for the analysis of therapeutic proteins

Mild or elevated temperatures are routinely used for the analysis of therapeutic proteins by reversed phase liquid chromatography. Generic conditions can be used for the analysis of monoclonal antibodies, and may be adapted for species derived thereof, for instance their immuno-conjugates. Beyond platform monoclonal antibodies, many novel, non-covalent protein complexes are also frequently pursued as protein therapeutics. These complexes, in reverse phased chromatography, may require extremely harsh, superheated conditions to dissociate and elute as interpretable profiles. In order to minimize on-column degradation under superheated conditions, the analysis time has to be reduced as much as possible. Using ultrashort columns and fast gradients is a promising approach in achieving informative separations within a minute, or even faster. Here the applicability of this approach, which supports maintaining levels of degradation products close to the intrinsic sample composition without further on-column degradation is demonstrated. NISTmAb as conventional IgG, a bispecific homodimer and a bispecific homotetramer were used for demonstrating differences in the elution characteristics and the necessity of using the proposed approach. The analysis of the bispecific homodimer was discussed in detail as a case study.

Study of elution characteristics of anti-tuberculosis drugs mixed with bone cement

The objective: to assess the elution characteristics of anti-tuberculosis drugs (isoniazid, cycloserine, rifampicin, amikacin, kanamycin, ethambutol) placed into bone cement samples and put in a liquid medium to determine the possibility of using such systems as a drug reservoir.Subjects and methods. For in vitro studies, pure substances of the drugs were used. The spectrophotometry was used to study the elution kinetics of the drugs. Absorption spectra of the drugs in the visible and ultraviolet regions were analyzed to reveal the absorption maxima, and the resistance of the chemical structure of the drugs to heating was assessed. Further, the changes of drug release from hardened bone cement samples under static conditions were studied.Results. It has been found that studied drugs demonstrated satisfactory parameters of thermal stability and elution which makes it possible to use them in a mixture with bone cement.

In vitro elution characteristics of gentamicin- and teicoplanin-loaded CMW1 and Palacos R bone cement

PurposeTo compare the in vitro elution characteristics of CMW1 and Palacos R bone cement loaded with gentamicin, teicoplanin, or in combination. MethodsFour bone cement discs were prepared for each cement type. Disc 1 contained no antibiotics; disc 2 contained 0.5 g gentamicin; disc 3 contained 2 g teicoplanin; disc 4 contained 0.5 g gentamicin and 2 g teicoplanin. Elution studies were conducted using a fluorescence polarisation immunoassay technique and performed at intervals of 6 weeks. ResultsFor CMW1, gentamicin and teicoplanin elution levels in combination discs were higher than those in the single antibiotic discs (p < 0.001 & p < 0.06). For Palacos R, gentamicin elution levels in combination discs were higher than those in the single antibiotic discs (p < 0.001), but teicoplanin elution levels in combination discs were lesser than that from the single antibiotic discs (p < 0.02). In single and combination discs, gentamicin elution levels in Palacos R were higher than those in CMW1 (p < 0.001 & p < 0.001). Palacos R eluted more teicoplanin than CMW1, except in combined disc with gentamicin, when less teicoplanin was eluted. ConclusionAntibiotic elution is higher in Palacos R than CMW1. Antibiotic combination in both cement types has the synergistic effect of increasing antibiotic elution, except for teicoplanin from Palacos R. When high elution of gentamicin is required, Palacos R is preferable. When high elution of teicoplanin is required, Palacos R with only teicoplanin is superior to CMW1.

Comparison of elution characteristics and mechanical properties of acrylic bone cements with and without superficial vancomycin coating (SVC) in the late phase of polymerization

IntroductionAntibiotic-loaded bone cements (ALBCs) are used as spacers in two-stage revision arthroplasty for periprosthetic joint infection. We previously described a new technique applying vancomycin powder coating to custom-made cements. To our best knowledge, this method of superficial vancomycin coating (SVC) has not been assessed before. We therefore performed an in-vitro study to determine: (1) whether manually applied SVC strengthened the cements’ antibiotic effect; and (2) whether the mechanical requirements for the cements were fulfilled. HypothesisSVC increases the antibiotic effect of cement within the first 24hours. MethodsCuboid blocks were produced from two commercially available acrylic ALBCs (Palacos R+G and Copal G+V) with and without SVC. Each block was eluted in phosphate-buffered saline at 37°C. Eluates obtained at 1, 2, 3, 4, 5, 10, 15, 30 and 60minutes and 3, 6 and 24hours were evaluated against Staphylococcus aureus (Palacos, Copal) and methicillin-resistant Staphylococcus aureus (MRSA) (Copal) using zone of inhibition tests. Mechanical test results (bending modulus, bending strength) were compared to ISO requirements (≥1800MPa, ≥50MPa). ResultsPalacos with SVC produced significantly greater zones of inhibition against Staphylococcus aureus than Palacos without SVC (p=0.002). Copal with SVC showed greater zones of inhibition against both Staphylococcus aureus and MRSA (p=0.002). The antibiotic effect was enhanced by SVC in both cements at every time point within 24hours. The bending modulus and bending strength of Palacos with SVC (2089±166MPa, 60.8±2.6 MPA) and Copal with SVC (2283±195MPa, 56.9±2.4MPa) were significantly above ISO requirements. ConclusionSVC boosts the antibiotic effect of ALBCs in the first 24hours, while maintaining sufficient stability. These findings endorse SVC as a promising additive in septic revision surgery. Level of evidenceIII; case control study.

Bivalirudin and sirolimus co-eluting coronary stent: Potential strategy for the prevention of stent thrombosis and restenosis

Localized drug delivery with sustained elution characteristics from nanocarrier coated stents represents a viable therapeutic approach to circumvent concerns related to coronary stent therapy. We fabricated a Sirolimus (SRL) and Bivalirudin (BIV) releasing nanoparticles (NPs) coated stent for concurrent mitigation of vascular restenosis and acute stent thrombosis. SRL NPs were prepared by nanoprecipitation method whereas the BIV vesicles were generated using hydrophobic ion pair approach followed by micellization phenomenon. MTT assay and confocal microscopic analysis indicated superior anti-proliferative activity and higher cellular uptake of SRL NPs into human coronary artery smooth muscle cells, respectively. DSC and ATR-FTIR techniques confirmed the formation of complex between BIV and phosphatidylglycerol via some weak physical interactions. More than 2 fold rise in log P value was obtained for DSPG-BIV at 3:1 M ratio compared with native BIV solution. The SAXS analysis indicated formation of oligolamellar vesicles of DSPG-BIV complex which was preferentially entrapped into lipophilic lamellae of vesicles. APTT, PT, and TT tests revealed that the BIV vesicles caused significant prolongation of clotting time compared to native BIV solution. The SEM analysis showed uniform and defect free stent coating. In vitro release study demonstrated that SRL and BIV were eluted in a sustained manner from coated stents.

Evaluation of Elution Characteristics by Material for Kitchen Utensils

Evaluation of Elution Characteristics by Material for Kitchen Utensils

Elution characteristics of undesirable anionic species from fly ash blended cement in different aqueous solutions

There are few reports to explore immobilization of undesirable anionic species released from fly ash (FA) blended cement. This study clarifies the stabilities of several undesirable anionic species, through dissolution tests under a different matrix. The immobilization mechanism mainly involves co-precipitation with ettringite and hydrocalumite, the marginal formation of insoluble Ca salts, and occlusion in calcium silicate hydrates and amorphous phases produced during the pozzolanic reaction. The products released some amounts of chromate, arsenate, and selenite but not borate in dissolution tests. Elution of borate was the most effectively immobilized by Ca additives, owing to selective incorporation in ettringite. Moreover, selenite showed a trend of dissolving in acidic conditions, presumably owing to the dissolution of CaSeO3 with relatively high Ksp in addition to coprecipitation with hydrocalumite and ettringite. Under the present mixing condition of cementation, only selenite is a cautionary species which excessively eluted over the environmental standard.

Combustion Melting Characterisation of Solid Fuel Obtained from Sewage Sludge

Solid fuelization technology can increase the heating value of sewage sludge such that it can be utilised as a fossil fuel substitutes. Reducing landfilling of bottom and fly ash resulting from heavy metals contained in sewage sludge is challenging. Hence, combustion melting technology (CMT), which can discharge bottom ash in the form of slag, has been proposed herein as an alternative to the conventional incineration technology. However, further research is required to improve the flowability of slag. Applicability of CMT for the stable treatment of heavy metals in the ash generated during the energisation of sewage sludge solid fuel has been reviewed. The change in the degree of fluidity was identified via a laboratory-scale fluidity measurement experiment following changes in melting temperature, mixing ratio of sewage sludge and sawdust, and basicity. The pouring index (PI) of sewage sludge solid fuel (pellet) was maintained at a level of about 60% at a basicity index of 0.8. Based on the results, the slagging rates and volume reduction rates, exhaust gas analysis, and heavy metal elution characteristics under oxygen enrichment were derived from a 2 ton/day combustion melting pilot plant experiment; thereafter, the feasibility of combustion melting of sewage sludge solid fuel was determined.

Creation of a Custom-Length, Humeral Antibiotic Cement Spacer for Use in Treatment of Shoulder Periprosthetic Joint Infection

Periprosthetic joint infection of the shoulder is a challenging clinical situation to manage owing to the fastidious organisms often present and delayed clinical presentation. While several treatment options have been described, the mainstay of treatment remains a staged revision with the use of a humeral antibiotic cement spacer. Such spacers are commercially available or can be made by hand. When an extended humeral osteotomy is required to remove a well-fixed long stem humeral component, it may be advantageous to place an antibiotic spacer with a stem length approximately as long as the hardware being removed. This technique demonstrates creation of a custom length, humeral antibiotic cement spacer for use in treatment of shoulder periprosthetic joint infection.

In vitro elution characteristics of gentamicin-impregnated Polymethylmethacrylate: premixed with a second powder vs. liquid Lyophilization

BackgroundAntibiotic-loaded bone cement, or antibiotic-impregnated polymethylmethacrylate (PMMA), were developed to prevent and treat bone and joint infections. Gentamicin is an antibiotic that is commonly used in combination with PMMA; however, gentamicin powder is hard to obtain in many countries. This study aimed to evaluate the elution characteristics of gentamicin-impregnated PMMA made with lyophilized liquid gentamicin, compared with PMMA; which is made from commercial gentamicin powder.MethodsThe experimental sample was divided into 2 groups: the gentamicin power group (PG-PMMA) and the lyophilized liquid gentamicin group (LG-PMMA). Ten cement spacers were prepared in each group. These were produced by mixing gentamicin powder, or lyophilized liquid gentamicin, with a powder polymer before adding the liquid monomer (2 g of gentamicin and 40 g of PMMA). The volume and surface area of the antibiotic-impregnated cement spacers were 50 cm3 and 110 cm2, respectively. Each spacer was immersed in phosphate-buffered saline, which was changed daily under sterile conditions. The solutions were collected to measure the level of gentamicin using the enzyme multiplied immunoassay technique (EMIT), at days 1, 2, 3, 4, 5, 6, 7, 14, 21, 28, 35 and 42.ResultsThe collections from both groups had high concentrations of gentamicin on day 1 (113.63 ± 23.42 mg/dL in LG-PMMA and 61.7 ±8.37 mg/dL in PG-PMMA), but experienced a continuous decrease over time. The PMMA spacers from both groups could release gentamicin for up to 6 weeks (3.28 ± 1.17 mg/dL in LG-PMMA and 1.21 ± 0.28 mg/dL in PG-PMMA). However, there were significantly higher levels of gentamicin concentrations in the LG-PMMA group compared to the PG-PMMA group at all time points (P< 0.05).ConclusionGentamicin-impregnated PMMA made with lyophilized liquid gentamicin had approximately a two times higher rate of antibiotic elution in preliminary in vitro studies, as compared with PMMA made with premixed gentamicin powder.