Methyl methacrylate and polymethyl methacrylate.
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Abnormalities, Drug-Induced↗
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A polymethyl methacrylate method for large specimens of mineralized bone with implants.
A simple modified polymethyl methacrylate method is described for large mineralized bone specimens with implants and bioactive materials which produces consistently good histological preservation of the interface between bone and implant. Human femoral heads, whole rabbit condyles and canine tibias and femurs containing implants consisting of hydroxyapatite, smooth polyethylene, porous polyethylene and carbon were dehydrated in ascending grades of ethanol and cleared with xylene on an automated tissue processor which alternated vacuum and pressure for 22 hr. Infiltration was done with washed polymethyl methacrylate at 4 C under vacuum for 13 days. Polymerization was carried out in wide-mouth glass jars at 38 C for 36 hr so that the total processing time was less than 20 days. The only important modification was in the polymethyl methacrylate, which had less plasticizer than usual in order to give a harder block. This enabled production of 4 micron sections with good preservation of mineralized and cellular areas for the study of metabolic bone diseases, morphometry, fluorochrome labelling and interface analysis with the implant in situ.
Animals↗
Histopathological evaluation of polymethyl methacrylate as an embolic agent.
Polymethyl methacrylate (PMMA) microspheres were used as an embolic agent to reduce the vascularity in eight patients with intracranial vascular tumours. Post embolization angiograms showed 30-60% reduction in the vascularity of the tumours. No patient developed any neurological complications in the immediate post-embolization period. These eight patients subsequently underwent surgery for the removal of their tumours. During surgery there was minimal blood loss and a good plane of cleavage was obtained between the tumour and the adjacent brain. The surgical specimens were examined histopathologically for the effects of PMMA. PMMA microspheres, in contrast to other cyanoacrylates--isobutyl-2-cyanoacrylate (IBCA)--did not elicit either inflammatory reaction or mural angionecrosis within the wall of the embolised vessels. The histopathological studies suggest that PMMA microspheres are an inert material and can be used as an adjunct in the management of intracranial vascular tumours.
Adult↗
Evaluation of the burst mode of a neodymium: YAG laser in saline and polymethyl methacrylate.
We evaluated effect of burst mode on the plasma length of a Q-switched Neodymium: YAG laser in saline and polymethyl methacrylate with or without UV-absorbing pigment. In a saline solution, the plasma length was independent from the number of pulses used. In polymethyl methacrylate the plasma length increased proportional to the number of pulses in a burst mode. This effect was more pronounced in polymethyl methacrylate with UV absorber than without UV-absorbing pigment.
Cataract Extraction↗
Fatal fat embolism associated with polymethyl methacrylate bone cement.
Three fatalities after procedures involving the use of polymethyl methacrylate cement are reported. Autopsy studies showed varying degrees of pulmonary fat embolism although lack of correction of operative blood loss was the major factor.
Acrylates↗
Use of ceftazidime-impregnated polymethyl methacrylate beads in the treatment of Pseudomonas osteomyelitis.
Antibiotic-impregnated polymethyl methacrylate beads have been used in other countries to treat osteomyelitis. The drug of choice for this has historically been gentamicin. The authors have chosen ceftazidime to treat iatrogenic Pseudomonas aeruginosa osteomyelitis in rabbit femurs. After implanting the beads, the rabbits were killed at various times in the treatment period. Rabbits were killed at 15 days and later showed no signs of current osteomyelitis, including cultures and histologic examination. Blood antibiotic levels were measured at euthanasia and were minimal for all animals. It appears that ceftazidime may be an effective alternative to gentamicin, especially in treating gentamicin-resistant P. aeruginosa.
Animals↗
An improved method for embedding hard tissue in polymethyl methacrylate.
An improved routine method for embedding tissue, especially hard tissue, in polymethyl methacrylate (pMMA) is described. The improvements were: the final dehydration step before MMA infiltration was performed with methanol in a Soxhlet apparatus; the stabilizer hydroquinone was not extracted from the monomer (MMA), and more important, the commonly used polymerization initiator, benzoyl peroxide (bpo), was replaced by the initiator, bis (4-tert-butylcyclohexyl)peroxydicarbonate (bbpd). Bbpd is preferred to bpo because it is not explosive, far less is needed and it has a suitable half life. Moreover, bbpd, as obtained from the manufacturer, needs no further purification, in contrast to bpo. Temperatures during bbpd initiated polymerization did not exceed 48 C. In bbpd initiated pMMA, bubbles were almost never generated.
Benzoyl Peroxide↗
Human growth hormone in polymethyl methacrylate. A controlled study of 15 hip arthroplasties.
Growth hormone-loaded polymethyl methacrylate (PMMA) was used in 15 hip replacements. The levels of growth hormone and insulin growth factor-I from the hip and the blood were measured before, and after, implanting PMMA containing 20 mg of growth hormone. Low levels of growth hormone and insulin growth factor-I were found in the femur initially, but very high local levels were found after implanting the growth hormone-loaded PMMA. These results were compared with the low levels found in 15 patients in a control group undergoing cemented or cementless hip replacement without added growth hormone. The local levels of growth hormone and insulin growth factor-I declined rapidly during the first 72 hours and were near normal at the end of this time. Systemic levels of growth hormone and insulin growth factor-I were not affected by the implantation of growth hormone-loaded PMMA. No complications or adverse reactions were noted. However, randomized studies with long-term follow-up are mandatory before the use of growth hormone-loaded PMMA is justified.
Aged↗
Corneal endothelial response to refitting polymethyl methacrylate wearers with rigid gas-permeable lenses.
Thirteen persons who had been wearing only polymethyl methacrylate (PMMA) contact lenses for 3 years or more were switched to a contact lens material providing greater oxygen transmissibility (Itafocon A) while keeping other contact lens parameters the same. Monitoring of corneal endothelial cells during the first 4 months of the rigid gas-permeable (RGP) lens daily wear showed no significant change in the coefficient of variation of cell area (polymegethism) or percentage of hexagonal endothelial cells at the end of 4 months. However, paired data did show a small, but significant, decrease in cell density at the end of 4 months (3174 to 2908 cells/mm2). The results suggest that a sudden shift in the general corneal environment toward more available oxygen may have some early effect on endothelial cell density, but changes in endothelial cell size variation and form are not determined.
Adult↗
Comparative physiologic performance of polymethyl methacrylate and gas-permeable contact lenses.
A short-term study of the physiologic response of the cornea to polymethyl methacrylate (PMMA) contact lenses and hard, gas-permeable contact lenses of different materials (polycon and Menicon 02), thicknesses, and fittings, was carried out on nine unadapted subjects using one eye as the experimental eye and the other as the control eye (no lens). Changes in corneal thickness were monitored at seven locations across the cornea using an electronic micropachymeter. It was found that gas-permeable lenses produced less corneal swelling than the PMMA lenses. However, lens thickness and the fit of the lens were still important control variables with these gas-permeable lenses. The thin gas-permeable lens produced less swelling than thicker lenses, and the flatter fitting gas-permeable lenses produced less swelling than the steeper fitting lenses. The swelling with all the hard lenses studied was confined primarily to the central 6 mm of the cornea.
Adult↗
Lack of sister-chromatid exchange induction by polymethyl methacrylate bone cement in human lymphocytes cultured in vitro.
Human lymphocytes cultured in vitro were used to assess the ability of polymethyl methacrylate (PMMA), currently used in orthopedic surgery as bone cement, to induce sister-chromatid exchanges (SCE). Under the conditions used in this study, PMMA bone cement did not produce any significant increase in SCEs in phytohemagglutinin-stimulated human lymphocytes. However, a significant decline (p less than 0.05) in the proliferation rate index was observed, which might be an indicator of the cytotoxic effect of PMMA.
Adult↗
In vitro research on the possibility of chromosomal damage caused by polymethyl methacrylate in orthopaedics. A preliminary report.
There are few experimental studies in the literature concerned with evaluating the toxic effect of polymethyl methacrylate. Because of the number of patients who are now carriers of this substance, it seems important to ascertain whether or not it could cause chromosomal damage. This study reports the preliminary data obtained from an in vitro technique on human lymphocytes placed in contact with different concentrations of methyl methacrylate and its polymerized form. The method consists of an analysis of the exchanges of DNA tracts in the chromosomes of these lymphocytes; the increase in the frequency of exchange as compared to that in the controls is an indication of the mutagenic effect. A slight increase in the average frequency of isochromatid exchanges in the lymphocytes cultivated with the monomer was observed, and this deserves closer study. However, this preliminary data would appear to exclude the existence of chromosomal damage.
Adult↗
Residual ethylene oxide determination in polymethyl methacrylate disks and intraocular lenses by headspace gas analysis and N,N-dimethylformamide extraction.
The residue in an ethylene oxide (EO)-exposed polymethyl methacrylate (PMMA) material [flat disk and intraocular lens (IOL)] was determined using three methods: semiautomatic and manual headspace methods and N,N-dimethylformamide (DMF) solvent extraction. Results from the analysis of three different sample configurations at three different EO concentrations are compared. Results from the DMF extraction of PMMA indicate that the headspace methods at 100 degrees C are not exhaustive with respect to recovery of total residual ethylene oxide. Furthermore, the manual headspace method appears to be slightly more effective than the semiautomatic injection headspace method. Sorption of EO and subsequent extraction is related to the surface area-to-volume ratio of the sample, with higher concentrations observed in samples with the high ratio.
Autoanalysis↗
Silver polymethyl methacrylate antibacterial bone cement.
An improved antibacterial bone cement was sought based on the addition of low concentrations of inorganic silver compounds to polymethyl methacrylate. Composites with AgCl, Ag-AgCl, Ag2O, Ag2SO4 and Ag3PO4 in concentrations of 0.05% to 1% by weight, were tested in vitro against bacterial cultures. All were effective, but Ag2SO4 was especially so, even after 7 weeks of incubation in normal saline. Compressive strength of the cement was not affected by these additions, except in the case of Ag2O. Biocompabibility tests in rabbit muscle for up to 12 weeks showed no significant difference between the Ag -PMM and plain PMM in tissue reactivity, both being minimal. These features, coupled with the broad spectrum of antibacterial activity and low allergic potential of silver, make Ag-PMM an attractive alternative to conventional organic antibiotic/bone cement composites.
Acrylic Resins↗
Macrophage exposure to polymethyl methacrylate leads to mediator release and injury.
To understand further the role of macrophages in the loosening of cemented arthroplasty, several in vitro effects of polymethyl methacrylate (PMMA) particle exposure in these cells were studied. The kinetics of arachidonic acid and derived inflammatory mediator release was characterized following macrophage exposure to either PMMA or control polystyrene particles. Temporal release of radiolabeled products by [14C]arachidonate-labeled cells was determined by sequential scintillation counting. Significant dose-dependent release of arachidonic acid mediators by macrophages was observed within half an hour of exposure to either PMMA or styrene particles. Unexposed control cells incubated in media alone did not release detectable amounts of radiolabeled products. The leakage of intracellular lactate dehydrogenase (LDH), a marker of cell injury, was detected spectrophotometrically 4 h following exposure to PMMA but not styrene. PMMA-induced LDH release was dose dependent. In contrast, polystyrene exposure failed to increase LDH release above unexposed control cells. These in vitro studies reveal that macrophages rapidly released arachidonic acid and derived inflammatory mediators in response to both PMMA and styrene particles. However, cells exposed to PMMA are lethally damaged, as reflected by the subsequent leakage of their intracellular LDH. We propose that a similar sequence of events may occur when macrophages encounter PMMA particles at the bone-cement interface. This is characteristic of a foreign body granulomatous response.
Animals↗
An infrared study of the interaction of polymethyl methacrylate with the protein and mineral components of bone.
We used Fourier transform infrared (FT-IR) microscopic mapping techniques to investigate the infiltration of polymethyl methacrylate (PMMA), a widely used medium for embedding biological tissues, into rat femur sections. Monitoring of the infrared absorbances of the PMMA carbonyl stretch, the protein amide I, and the apatite mineral phosphate stretch over a 225 x 975-microns region of the epiphyseal growth plate region of the rat femur enabled comparison of the relative amount of each component in distinct regions of the tissue. It was found that PMMA penetrates less into regions of greater mineral density and that the frequency of the PMMA carbonyl absorbance from the embedded tissue, 1729 cm-1, is identical to the free PMMA carbonyl frequency. This is consistent with a diffusion mechanism of infiltration of the PMMA, with no specific chemical interaction between the PMMA and the tissue components.
Animals↗
Effect of Staphylococcus epidermidis on adherence of Pseudomonas aeruginosa and Proteus mirabilis to polymethyl methacrylate (PMMA) and gentamicin-containing PMMA.
The goals of this study were to determine 1) effect of Staphylococcus epidermidis adherence and biofilm production on adherence of the opportunistic pathogens Proteus mirabilis and Pseudomonas aeruginosa to polymethyl methacrylate (PMMA); 2) if the biofilm killed by autoclaving altered adherence of other organisms; 3) if adherence of S. epidermidis to gentamicin-containing PMMA altered adherence of the opportunistic pathogens P. mirabilis and P. aeruginosa to gentamicin-containing PMMA. Results show that biofilms formed by S. epidermidis, whether alive or dead, significantly increased adherence of Pseudomonas. Adherence of Proteus was significantly increased on dead biofilms and increased, but not significantly (p = less than 0.1), on live ones. Greatest adherence seen in the study was to autoclaved biofilms. Significant adherence of Proteus and Pseudomonas was found on gentamicin-containing PMMA specimens, which were preincubated with S. epidermidis for formation on the biofilm. These results indicate that a biofilm is formed on PMMA-gentamicin specimens and this may impair the ability of gentamicin to kill other organisms.
Bacterial Adhesion↗
Distribution and elimination of polymethyl methacrylate nanoparticles after peroral administration to rats.
Polymethyl [1-14C]methacrylate nanoparticles were administered orally to bile cannulated rats. Ten to fifteen percent of the administered radioactivity was absorbed and found in the bile and urine. Within 48 h, 94-97% of the absorbed radioactivity had been eliminated from the body. After 8 d, the highest residual radioactivity was found in the bone marrow, fatty renal tissue, stomach, liver, and lymph nodes.
Administration, Oral↗