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

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Wongthawat Liawrungrueang ◽  
Suwipa Ungphaiboon ◽  
Arnurai Jitsurong ◽  
Natnicha Ingviya ◽  
Boonsin Tangtrakulwanich ◽  
...  
Keyword(s):  
Bone Cement ◽  
Experimental Sample ◽  
Time Points ◽  
Joint Infections ◽  
Immunoassay Technique ◽  
Power Group ◽  
High Concentrations ◽  
Phosphate Buffered Saline ◽  
Over Time

Abstract Background Antibiotic-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. Methods The 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. Results The 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). Conclusion Gentamicin-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.

scholarly journals Genomic DNA microarray comparison of gene expression patterns in Paracoccidioides brasiliensis mycelia and yeasts in vitro

Microbiology ◽  
2009 ◽  
Vol 155 (8) ◽  
pp. 2795-2808 ◽  
Author(s):  
Jomar Patrício Monteiro ◽  
Karl V. Clemons ◽  
Laurence F. Mirels ◽  
John A. Coller ◽  
Thomas D. Wu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Genomic Dna ◽  
Paracoccidioides Brasiliensis ◽  
Expression Patterns ◽  
Gene Expression Patterns ◽  
Protein Catabolism ◽  
Time Points ◽  
Over Time

Paracoccidioides brasiliensis is a thermally dimorphic fungus, and causes the most prevalent systemic mycosis in Latin America. Infection is initiated by inhalation of conidia or mycelial fragments by the host, followed by further differentiation into the yeast form. Information regarding gene expression by either form has rarely been addressed with respect to multiple time points of growth in culture. Here, we report on the construction of a genomic DNA microarray, covering approximately 25 % of the genome of the organism, and its utilization in identifying genes and gene expression patterns during growth in vitro. Cloned, amplified inserts from randomly sheared genomic DNA (gDNA) and known control genes were printed onto glass slides to generate a microarray of over 12 000 elements. To examine gene expression, mRNA was extracted and amplified from mycelial or yeast cultures grown in semi-defined medium for 5, 8 and 14 days. Principal components analysis and hierarchical clustering indicated that yeast gene expression profiles differed greatly from those of mycelia, especially at earlier time points, and that mycelial gene expression changed less than gene expression in yeasts over time. Genes upregulated in yeasts were found to encode proteins shown to be involved in methionine/cysteine metabolism, respiratory and metabolic processes (of sugars, amino acids, proteins and lipids), transporters (small peptides, sugars, ions and toxins), regulatory proteins and transcription factors. Mycelial genes involved in processes such as cell division, protein catabolism, nucleotide biosynthesis and toxin and sugar transport showed differential expression. Sequenced clones were compared with Histoplasma capsulatum and Coccidioides posadasii genome sequences to assess potentially common pathways across species, such as sulfur and lipid metabolism, amino acid transporters, transcription factors and genes possibly related to virulence. We also analysed gene expression with time in culture and found that while transposable elements and components of respiratory pathways tended to increase in expression with time, genes encoding ribosomal structural proteins and protein catabolism tended to sharply decrease in expression over time, particularly in yeast. These findings expand our knowledge of the different morphological forms of P. brasiliensis during growth in culture.

Selectlve desensitization of 5-hydroxytryptamine 2A receptor mediated contraction in guinea pig trachea

1994 ◽  
Vol 72 (5) ◽  
pp. 463-470 ◽  
Author(s):  
Stephanie W. Watts ◽  
Kathryn W. Schenck ◽  
Marlene L. Cohen
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Jugular Vein ◽  
Rat Aorta ◽  
Receptor Desensitization ◽  
Maximal Contraction ◽  
High Concentrations ◽  
Over Time ◽  
Stimulation Of

5-Hydroxytryptamine (serotonin, 5-HT) contracts the guinea pig trachea through stimulation of 5-HT2A receptors, an effect previously reported to rapidly desensitize. The present studies were designed to examine further the putative desensitization to serotonin. In vitro studies investigating functional desensitization of the guinea pig tracheal 5-HT2A receptor documented that 5-HT (3 × 10−7 M) significantly (50%) but incompletely reduced subsequent tracheal maximal contraction to 5-HT. In contrast, an equieffective concentration of carbamylcholine (3 × 10−8 M) did not reduce guinea pig tracheal contraction to 5-HT. Furthermore, 5-HT (3 × 10−7 M) did not diminish tracheal contraction to carbamylcholine. These data indicate that 5-HT can selectively desensitize guinea pig tracheal contraction to 5-HT. In addition, 5-HT-induced contraction but not carbamylcholine-induced contraction in guinea pig trachea declined over time, an effect that was more pronounced at high concentrations of 5-HT (1 × 10−6 and 1 × 10−5 M). Inhibitors of mechanisms that oppose contractility to 5-HT (5-HT-induced relaxation, uptake of 5-HT, or metabolism of 5-HT) did not reverse the decline in contraction to 5-HT (1 × 10−5 M). The decline in 5-HT-induced contraction was most rapid in the guinea pig trachea and less so in the rat jugular vein and rat aorta, two preparations in which 5-HT induced contraction also occurred via activation of 5-HT2A receptors. These studies suggest that 5-HT can functionally and selectively desensitize the 5-HT2A receptor in guinea pig trachea, an effect not likely to be related to opposing actions of 5-HT or reduction in concentration of 5-HT.Key words: phosphatidylinositol hydrolysis, receptor desensitization, smooth muscle.

scholarly journals In vitro evaluation of antibiotic diffusion from antibiotic-impregnated biodegradable beads and polymethylmethacrylate beads.

1997 ◽  
Vol 41 (2) ◽  
pp. 415-418 ◽  
Author(s):  
J T Mader ◽  
J Calhoun ◽  
J Cobos
Keyword(s):  
Secondary Surgery ◽  
Bacterial Killing ◽  
Bone Infections ◽  
Dead Bone ◽  
Disk Diffusion Assay ◽  
High Concentrations ◽  
Pmma Beads ◽  
Phosphate Buffered Saline ◽  
Diffusion Assay

Antibiotic-impregnated beads are used in the dead bone space following debridement surgery to deliver local, high concentrations of antibiotics. Polymethylmethacrylate (PMMA), 2,000-molecular-weight (MW) polylactic acid (PLA), Poly(DL-lactide)-coglycolide (PL:CG; 90:10, 80:20, and 70:30), and the combination 2,000-MW PLA-70:20 PL:CG were individually mixed with clindamycin, tobramycin, or vancomycin. Beads were placed in 1 ml of phosphate-buffered saline (PBS) and incubated at 37 degrees C. The PBS was changed daily, and the removed PBS samples were stored at -70 degrees C until the antibiotic in each sample was determined by microbiological disk diffusion assay. Nondissolving PMMA beads with tobramycin and clindamycin had concentrations well above breakpoint sensitivity concentrations (i.e., the antibiotic concentrations at the transition point between bacterial killing and resistance to the antibiotic) for more than 90 days, but vancomycin concentrations dropped by day 12. ALl PLA, PL:CG, and the 2,000-MW PLA-70:30 PL:CG biodegradable beads release high concentrations of all the antibiotics in vitro for the period of time needed to treat bone infections (i.e., 4 to 8 weeks). Antibiotic-loaded PLA and PL:CG beads have the advantage of better antibiotic elution and the ability to biodegradable (thereby averting the need for secondary surgery for bead removal) compared to the PMMA beads presently used in the clinical setting.

scholarly journals 1259. Activity of eravacycline against staphylococci isolated from periprosthetic joint infections

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S646-S646
Author(s):  
Georg Zhuchenko ◽  
Suzannah Schmidt-Malan ◽  
Robin Patel ◽  
Robin Patel
Keyword(s):  
Research Support ◽  
Methicillin Resistant ◽  
Joint Infections ◽  
Mueller Hinton ◽  
Common Causes ◽  
Visible Growth ◽  
Phosphate Buffered Saline ◽  
Mueller Hinton Broth ◽  
Intraabdominal Infections

Abstract Background Perirosthetic joint infections (PJIs) are costly and difficult to treat. The most common causes of PJIs are Staphylococcus aureus and Staphylococcus epidermidis. Eravacycline is a newer tetracycline with promising activity against Gram-positive and negative bacteria which is approved for treatment of complicated intraabdominal infections. Here, the in vitro activity of eravacycline was assessed against bacteria associated with PJI. Methods 185 staphylococcal isolates, including 38 methicillin-resistant S. aureus (MRSA), 64 methicillin-susceptible S. aureus (MSSA), 62 methicillin-resistant S. epidermidis (MRSE) and 21 methicillin-susceptible S. epidermidis (MSSE) strains were studied. Minimum inhibitory concentrations (MICs) were determined according to Clinical and Laboratory Standards Institute guidelines (range of 0.06-64 µg/ml tested). Results were analyzed using susceptible breakpoints from EUCAST (≤0.25 µg/ml) and the FDA (≤0.06 µg/ml). Minimum biofilm bactericidal concentrations (MBBCs) were determined using a modification of the Calgary biofilm method. Briefly, biofilms were formed on pegged lids in trypticase soy broth, after which the pegged lids were rinsed in phosphate buffered saline (PBS), transferred to a plate containing dilutions of eravacycline in cation-adjusted Mueller Hinton broth (CAMHB) and incubated for 20-24h. Finally, the pegged lids were again rinsed in PBS and transferred to a plate containing CAMHB and incubated for 24h. The MBBC was the lowest concentration with no visible growth. Results MIC50/90 (range) in µg/ml for MRSA, MSSA, MRSE, and MSSE were 0.125/0.125 (≤0.06-0.25), ≤0.06/0.125 (≤0.06-0.25). 0.125/1 (≤0.06-2), and 0.25/1 (≤0.06-1), respectively. Using the EUCAST susceptible breakpoint, 100% of isolates would be considered susceptible, whereas only 54% would be considered susceptible using the FDA breakpoint. MBBC50/90 (range) in µg/ml for MRSA and MSSA were both 8/16 (4-16); for MRSE and MSSE, the values were 4/16 (2-32) and 8/16 (2-32), respectively. Conclusion Our data suggest that the FDA susceptible breakpoint may need re-evaluation. Eravacycline has low anti-staphylococcal biofilm activity. Disclosures Robin Patel, MD, Accelerate Diagnostics (Grant/Research Support)CD Diagnostics (Grant/Research Support)Contrafect (Grant/Research Support)Curetis (Consultant)GenMark Diagnostics (Consultant)Heraeus Medical (Consultant)Hutchison Biofilm Medical Solutions (Grant/Research Support)Merck (Grant/Research Support)Next Gen Diagnostics (Consultant)PathoQuest (Consultant)Qvella (Consultant)Samsung (Other Financial or Material Support, Dr. Patel has a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, and a patent on an anti-biofilm substance issued.)Selux Dx (Consultant)Shionogi (Grant/Research Support)Specific Technologies (Consultant)

N ‐acetylcysteine use as an adjuvant to bone cement to fight periprosthetic joint infections: A preliminary in vitro efficacy and biocompatibility study

2020 ◽  
Author(s):  
Kamolsak Sukhonthamarn ◽  
Jeongeun Cho ◽  
Emanuele Chisari ◽  
Karan Goswami ◽  
William V. Arnold ◽  
...  
Keyword(s):  
Bone Cement ◽  
Joint Infections ◽  
Biocompatibility Study

scholarly journals Controlling Antibiotic Release from Polymethylmethacrylate Bone Cement

Biomedicines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 26
Author(s):  
Victoria Wall ◽  
Thi-Hiep Nguyen ◽  
Nghi Nguyen ◽  
Phong A. Tran
Keyword(s):  
Bone Cement ◽  
Joint Infections ◽  
Current State ◽  
Prosthetic Joint ◽  
Prosthetic Joint Infections ◽  
Antibiotic Release ◽  
Local Antibiotic ◽  
Bone Void

Bone cement is used as a mortar for securing bone implants, as bone void fillers or as spacers in orthopaedic surgery. Antibiotic-loaded bone cements (ALBCs) have been used to prevent and treat prosthetic joint infections by providing a high antibiotic concentration around the implanted prosthesis. High antibiotic concentrations are, on the other hand, often associated with tissue toxicity. Controlling antibiotic release from ALBCS is key to achieving effective infection control and promoting prosthesis integration with the surrounding bone tissue. However, current ALBCs still need significant improvement in regulating antibiotic release. In this review, we first provide a brief introduction to prosthetic joint infections, and the background concepts of therapeutic efficacy and toxicity in antibiotics. We then review the current state of ALBCs and their release characteristics before focusing on the research and development in controlling the antibiotic release and osteo-conductivity/inductivity. We then conclude by a discussion on the need for better in vitro experiment designs such that the release results can be extrapolated to predict better the local antibiotic concentrations in vivo.

scholarly journals Comparative Assessment of Cuspal Deflection in Premolars Restored with Bulk-Fill and Conventional Composite Resins

2020 ◽  
Author(s):  
Ebrahim Yarmohammadi ◽  
Shahin Kasraei ◽  
Yasaman Sadeghi
Keyword(s):  
Adverse Effect ◽  
Repeated Measures ◽  
Comparative Assessment ◽  
Composite Resins ◽  
Time Points ◽  
Repeated Measures Analysis ◽  
Maxillary Premolars ◽  
The Mean ◽  
Over Time

Objectives: It has been reported that bulk-fill composites simplify tooth restoration with no adverse effect on the success rate. This study sought to assess the cuspal deflection of premolars with mesio-occluso-distal (MOD) cavities restored with bulk-fill and conventional posterior composite resins. Materials and Methods: This in-vitro experimental study was conducted on 64 human maxillary premolars. MOD cavities were prepared on teeth and restored with Filtek P60 conventional composite and Filtek Bulk Fill flowable, X-tra fill, and X-tra base bulk-fill composites in four groups (n=16). Distance between the cusp tips was measured before, five minutes, 24 hours, 48 hours, and one week after restoration. The data were analyzed using repeated-measures analysis of variance (ANOVA) and Tukey’s test (α=0.05). Results: The mean±standard deviation (SD) of cuspal deflection at five minutes after the restoration was 13.5±5.3, 12.2±3.5, 11.3±4.4, and 10.4±3.7 µm for Filtek P60, Filtek Bulk Fill, X-tra fill, and X-tra base, respectively. ANOVA showed that bulk-fill composites did not cause a significant reduction in cuspal deflection compared to P60 (P>0.05). Cuspal deflection in all groups significantly decreased with time (P<0.05). Conclusion: Bulk-fill composites have no superiority over P60 in the reduction of cuspal deflection. The cuspal deflection was variable at different time points in all groups and decreased over time.

scholarly journals 84METHANOL AS A CRYOPROTECTANT FOR EQUINE EMBRYOS

2004 ◽  
Vol 16 (2) ◽  
pp. 163
Author(s):  
L.D. Bass ◽  
D.J. Denniston ◽  
L.J. Maclellan ◽  
P.M. McCue ◽  
E.L. Squires
Keyword(s):  
Room Temperature ◽  
Survival Rates ◽  
Pregnancy Rates ◽  
Low Permeability ◽  
Initial Exposure ◽  
Time Points ◽  
Murine Embryos ◽  
Diameter Change ◽  
Over Time

Equine embryos with diameters &gt;300μm have low survival rates post-thaw, possibly due to low permeability of the cryoprotectant glycerol. Methanol has been used successfully for freezing ovine and murine embryos. The objectives of this study were: (1) examine the effect of methanol as a cryoprotectant for large equine embryos; (2) determine the diameter change of embryos exposed to methanol compared to glycerol; and (3) compare pregnancy rates of embryos cultured in vitro prior to transfer. Equine embryos (n=43) were recovered nonsurgically 7 to 8 days after ovulation and randomly assigned to be cryopreserved in one of two cryoprotectants: 4.8% v/v methanol (n=22) or 10% v/v glycerol (n=21). Embryos (300μm to 1000μm) were measured at 5 time points after exposure to glycerol (0, 2, 5, 10, and 15min) or methanol (0, 1.5, 3.5, 7.5 and 10min) to determine changes in diameter over time (%±SD). Embryos were loaded into 0.25-mL plastic straws, sealed, placed in a programmable cell freezer and cooled from room temperature (22°C) to −6°C. Straws were then seeded, held at −6°C for 10min, and cooled at 0.3°C/min to −30°C and then at 0.1°C/min to −33°C before being plunged into liquid nitrogen. Sets of three straws within a treatment group were thawed in air for 10s and then immersed in a 38°C water bath for 20s. Each set of three embryos was further assigned to be either cultured for 12h prior to transfer or transferred nonsurgically to a single mare immediately. Embryo diameter decreased in all embryos upon initial exposure to cryoprotectant. Embryos in methanol shrank and then recovered slightly to 76±8% of their original diameter; however, embryos in glycerol continued to shrink, reaching 57±6% of their original diameter prior to cryopreservation. Survival rates of embryos through Day 16 of pregnancy were 38% and 23%, respectively, P&gt;0.05) for embryos cryopreserved in the presence of glycerol or methanol. There was no difference in pregnancy rates of mares receiving embryos that were cultured prior to transfer or not cultured (P&gt;0.05). Methanol provided no advantage over glycerol as a cryoprotectant for equine blastocysts. Neither cryoprotectant provided satisfactory pregnancy rates of frozen/thawed large equine embryos. Further studies are needed to develop procedures for freezing large equine embryos.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

The Development of Homologous (Canine/Anti-Canine) Antibodies in Dogs with Haemophilia A (Factor VIII Deficiency): A Ten-Year Longitudinal Study

1993 ◽  
Vol 69 (01) ◽  
pp. 021-024 ◽  
Author(s):  
Shawn Tinlin ◽  
Sandra Webster ◽  
Alan R Giles
Keyword(s):  
Factor Viii ◽  
Canine Model ◽  
Significant Inhibition ◽  
Human Condition ◽  
Haemophilia A ◽  
Variable Expression ◽  
The Family ◽  
Over Time

SummaryThe development of inhibitors to factor VIII in patients with haemophilia A remains as a serious complication of replacement therapy. An apparently analogous condition has been described in a canine model of haemophilia A (Giles et al., Blood 1984; 63:451). These animals and their relatives have now been followed for 10 years. The observation that the propensity for inhibitor development was not related to the ancestral factor VIII gene has been confirmed by the demonstration of vertical transmission through three generations of the segment of the family related to a normal (non-carrier) female that was introduced for breeding purposes. Haemophilic animals unrelated to this animal have not developed functionally significant factor VIII inhibitors despite intensive factor VIII replacement. Two animals have shown occasional laboratory evidence of factor VIII inhibition but this has not been translated into clinical significant inhibition in vivo as assessed by clinical response and F.VIII recovery and survival characteristics. Substantial heterogeneity of inhibitor expression both in vitro and in vivo has been observed between animals and in individual animals over time. Spontaneous loss of inhibitors has been observed without any therapies designed to induce tolerance, etc., being instituted. There is also phenotypic evidence of polyclonality of the immune response with variable expression over time in a given animal. These observations may have relevance to the human condition both in determining the pathogenetic factors involved in this condition and in highlighting the heterogeneity of its expression which suggests the need for caution in the interpretation of the outcome of interventions designed to modulate inhibitor activity.

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