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PubMed2000

Cost analysis of enteroviral polymerase chain reaction in infants with fever and cerebrospinal fluid pleocytosis.

BACKGROUND: Infants with fever and cerebrospinal fluid (CSF) pleocytosis are routinely admitted to the hospital for parenteral antibiotic therapy for potential bacterial meningitis pending results of CSF culture. Published estimates suggest that 90% of all episodes of meningitis are caused by enterovirus. Enteroviral polymerase chain reaction (ePCR) has a sensitivity of 92% to 100% and a specificity of 97% to 100% in CSF. OBJECTIVE: To compare a management strategy using ePCR with current practice to determine potential savings by allowing earlier discharge. METHODS: Decision analysis comparing 2 strategies for the care of a retrospective cohort of infants with fever and CSF pleocytosis: standard practice vs ePCR testing of all CSF samples. Model assumptions include the following: (1) standard practice patients continue parenteral antibiotic therapy until CSF cultures are negative at 48 hours, (2) patients with positive ePCR results would be discharged after 24 hours, (3) patients with positive ePCR results have a negative CSF culture, and (4) costs are calculated from actual patient charges with a cost-to-charge ratio of 0.65. SUBJECTS: All infants aged 28 days to 12 months admitted to an urban teaching hospital with fever, CSF pleocytosis, and a negative CSF Gram stain from January 1996 through December 1997. OUTCOME MEASURE: Total cost of hospitalization. RESULTS: A total of 126 infants were identified. One hundred twelve (89%) were discharged with a diagnosis of aseptic meningitis; 72% of these cases occurred during the peak enterovirus season (June to October). Three of 3 patients with positive CSF cultures had bacterial growth within 24 hours of admission. Mean length of stay for patients with aseptic meningitis was 2.3 days (SD, +/-1.4 days). Total cost of hospital care for all 126 infants was $381,145. In our patient population, total patient costs would be reduced by the ePCR strategy if enterovirus accounts for more than 5. 9% of all meningitis cases. Varying the sensitivity of the ePCR assay from 100% to 90% changes the "break-even" prevalence from 5.8% to 6.5%. Total cost savings of 10%, 20%, and 30% would occur at an enteroviral meningitis prevalence of 36.3%, 66.7%, and 97.1%, respectively. CONCLUSIONS: Enteroviral PCR analysis of CSF for infants admitted to the hospital with meningitis can result in cost savings when the prevalence of enteroviral meningitis exceeds 5.9%. Limiting use of ePCR to the enterovirus season would increase cost savings. A prospective study is needed to validate these results. Arch Pediatr Adolesc Med. 2000;154:817-821

Boston↗
PubMed1993

Ultrastructural changes of articular cartilage chondrocytes associated with freeze-thawing.

In an attempt to justify the use of cryopreserved versus fresh articular cartilage (AC) allografts, we used transmission electron microscopy (TEM) to study the ultrastructure of fresh versus frozen-thawed AC with or without a dimethyl sulfoxide (DMSO) treatment. AC explants were cut aseptically from the femoral condyles of healthy, mature rabbits when they were killed. Half of all explants were incubated in Ham's F-12 medium, supplemented with antibiotics and with or without 7.5% DMSO, frozen to -80 degrees C, stored for 24 h, and thawed rapidly. These, and the control explants, were fixed with glutaraldehyde, paraformaldehyde, and acrolein in cacodylate buffer. Sections were stained for acid phosphatase (APase), postfixed with osmium, embedded, and examined under TEM. The typical organization of the matrix and the cells was noted in control sections. The chondrocytes contained intact nuclei, organelles, and discrete plasma membrane. Although some endoplasmic reticula and nuclear membrane appeared intact, distinct ultrastructural changes were observed in frozen-thawed samples treated with DMSO. These changes included condensation of chromatin, large lipid droplets, partly disrupted plasma membrane, and pericellular precipitation of APase-positive crystalites. In sections not treated with DMSO, the cytoplasm was extensively vacuolated and no distinct organelles could be detected in the chondrocytes. Little difference was noted between the matrix organization of fresh or frozen-thawed samples. Our results suggest that distinct ultrastructural changes occur in the chondrocytes following freeze-thawing of intact AC and that DMSO pretreatment may contribute to improvement in the cryopreservation of AC.

Acid Phosphatase↗
PubMed2002

Oxytocin preparation stability in several common obstetric intravenous solutions.

OBJECTIVE: The purpose of this study was to determine the stability of oxytocin in lactated Ringer's solution and lactated Ringer's-dextrose 5% solution over a 24-hour period at 25 degrees C and over a 7-day period at 5 degrees C. STUDY DESIGN: Twenty units (2.1 microg equal 1 unit) of oxytocin were injected into 1000 mL of lactated Ringer's solution and lactated Ringer's-dextrose 5% solution. Samples for the analysis were drawn at specified times after storage at 5 degrees C and 25 degrees C. These samples were stored at -70 degrees C for later analysis. Statistical analysis was done with 1-way analysis of variance and Tukey-Kramer multiple comparisons. RESULTS: Twenty units of oxytocin in 1000 mL of lactated Ringer's solution and lactated Ringer's-dextrose 5% solution was found to be stable for 7 days at 5 degrees C and for 24 hours at 25 degrees C. CONCLUSION: Premixed oxytocin solutions in lactated Ringer's solution and lactated Ringer's-dextrose 5% solution are stable in conditions commonly found in dispensing pharmacies and labor and delivery units. This finding could lead to the more efficient use of personnel during the mixing process, could provide solutions that are aseptically prepared, and could be a tool to reduce costs and improve patient care.

Drug Combinations↗
PubMed1986

Laboratory diagnosis of peritonitis in patients treated with continuous ambulatory peritoneal dialysis.

Patients treated with continuous ambulatory peritoneal dialysis (CAPD) are constantly exposed to microbial invasion of the peritoneal cavity and rapid microbiological diagnosis of peritonitis is essential. Aseptic peritonitis is diagnosed in a high proportion of episodes when small volumes of dialysate are cultured. The aims of this study were to enumerate the microorganisms associated with clinical peritonitis and compare the efficacy of various culture systems for laboratory diagnosis of peritonitis. Four qualitative culture systems were compared: low (1 ml) volume and high (10 ml) volume inoculations of broth media, centrifugation (10 ml) followed by culture of the sediment and filtration (less than or equal to 100 ml) followed by culture of the filter. The pour plate and drop plate were the 2 quantitative methods used. Results of this study indicate that culture of 10 ml fluid volumes is comparable to culture of larger volumes sampled by filtration. Low volume cultures of fluid resulted in a lower proportion of positive cultures. The low numbers of viable microorganisms often found in dialysate from patients with peritonitis supports the concept of culturing a minimum of 10 ml of fluid.

Bacteria↗
PubMed1986

[Prospective evaluation of coagglutination and latex agglutination in the diagnosis of bacterial meningitis in childhood].

UNLABELLED: Two simple and low-priced kits to detect bacterial antigens in cerebrospinal fluid (CSF) specimens from patients with suspected meningitis have recently become available. Methods employed by these kits are staphylococcal coagglutination (COA) and latex agglutination (LA). The COA "Phadebact CSF-kit" (Pharmacia) detects Haemophilus influenzae type b (HIb), Neisseria meningitidis (NM) groups A, B, C, Y and W 135 and Streptococcus pneumoniae (SP), whereas the LA "Slidex Méningite-kit" (BioMérieux) includes HIb, NM A, NM C and SP. These two diagnostic tests were compared with the standard methods for analyzing CSF specimens from children with suspected meningitis. A total of 336 CSF specimens were tested. Forty-three were from children with bacterial meningitis due to HIb, NM or SP obtained before antimicrobial therapy. Thirty-four of them (79%) were correctly detected by COA, 23 (54%) by LA, and 42 (97%) by microscopic analysis of stained smears. There were 65 CSF samples of such meningitis cases obtained after initiation of antimicrobial therapy: COA detected 26 (40%), LA 17 (26%) and staining 26 (40%). With culture-positive CSF specimens from patients before therapy, the best sensitivities were obtained with LA for SP (100%) and COA for HIb (87%), whereas the results for NM antigen detection were only 43% with COA and 0% with LA (no reagent against NM B). Cross-reactions with other bacterial antigens were frequent with COA (26%) and rare with LA (2%), resulting in false-positive findings in 6 of the 66 positive tests with COA (9%) but in none of the 40 positive tests with LA (0%). One of the 48 specimens from aseptic meningitis cases was false-positive for HIb by COA, whereas all 172 normal specimens were negative with both methods. With 5 culture-negative CSF specimens from patients with unequivocal purulent meningitis COA detected bacterial antigen in 5 and LA in 2. CONCLUSIONS: The two kits evaluated cannot replace standard methods for analyzing CSF specimens, in view of insufficient sensitivity (mainly LA) or frequent cross-reactions and false-positive values (COA). However, due to their simplicity, rapidity, and possible identification of bacterial pathogens after initiation of antimicrobial therapy, these kits are recommended as an useful addition to standard methods.

Adolescent↗
PubMed2002

Multiple drug resistance in urinary pathogens at Gondar College of Medical Sciences Hospital, Ethiopia.

OBJECTIVE: To determine multiple drug resistance and its associated factors of urinary pathogens. DESIGN: Cross-sectional study. SETTING: Gondar College of Medical Sciences teaching and Referral Hospital, Northwest Ethiopia, between January and October 2000. SUBJECTS AND METHODS: Mid stream urine samples from 420 subjects were studied by quantitative culture method. Designed Questionnaires were used for data collection on the previous use of antimicrobials, catheterisation and hospitalisation. MAIN OUTCOME MEASURES: Rates of multiple drug resistance and the associated factors. RESULTS: Multiple drug resistance was common in the isolates tested against ten antibiotics showing more than 68% of the isolates being resistant to two or more antimicrobials. Significant variables associated with this were found to be urinary catheterisation, hospitalisation and previous use of antibiotics for urinary tract infection. CONCLUSION: The rate of multiple drug resistance was very high in this study. Probable contributing factors were found to be previous antibiotic exposure, urinary catheterisation and hospitalisation. Reduction of hospital stays and catheterisation, aseptic care of catheterised patients and selective use of antibiotics and strict follow up of hospital disease controls are recommended.

Adolescent↗
PubMed2004

In vitro gas production as a surrogate measure of the fermentability of cellulosic biomass to ethanol.

Current methods for measuring ethanol yields from lignocellulosic biomass are relatively slow and are not well geared for analyzing large numbers of samples generated by feedstock management and breeding research. The objective of this study was to determine if an in vitro ruminal fermentation assay used in forage quality research was predictive of results obtained using a conventional biomass-to-ethanol conversion assay. In the conventional assay, herbaceous biomass samples were converted to ethanol by Saccharomyces cerevisiae cultures in the presence of cellulase enzymes. Cultures were grown in sealed serum bottles and gas production monitored by measuring increasing head space pressure. Gas accumulation as calculated from the pressure measurements was highly correlated (r(2)>0.9) with ethanol production measured by gas chromatography at 24 h or 7 days. The same feedstocks were also analyzed by in vitro ruminal digestion, as also measured by gas accumulation. Good correlations (r(2) approximately 0.63-0.82) were observed between ethanol production during simultaneous saccharification and fermentation and gas accumulation in parallel in vitro ruminal fermentations. Because the in vitro ruminal fermentation assay can be performed without sterilization of the medium and does not require aseptic conditions, this assay may be useful for biomass feedstock agronomic and breeding research.

Biotechnology↗
PubMed2001

Novel rapid method for visualization of extent and location of aerosol contamination during high-speed sorting of potentially biohazardous samples.

BACKGROUND: Containment of potentially biohazardous aerosols that result from high-speed sorting of human cells has been an increasingly important problem in analytical cytometry. The current method for assessing the efficiency of aerosol containment involves detection of aerosols containing sorted T4 bacteriophage on lawns of T4-susceptible Escherichia coli on plates that are placed in and around the sort area. Although this method is sensitive, it is time consuming and involves maintenance and handling of bacteria and sorting of bacteriophage that may themselves serve as sources of contamination for sorted viable human cells. METHODS: Glo Germ (5-microm melamine copolymer resin beads), which are fluorescent under black light illumination, were sorted on a Beckman-Coulter Elite ESP sorter in order to visualize deposition of aerosols under normal and mock failure modes. RESULTS: Glo Germ was successfully used under both normal sorting conditions, as well as mock failure mode, to visualize aerosol formation. CONCLUSIONS: We have developed a method to examine aerosol containment using modified Glo Germ, a product used for teaching aseptic technique in hospitals, industry, restaurants, and schools. Use of this technique represents a rapid, inexpensive, qualitative analysis of the extent and location of aerosol contamination from cell sorters.

Aerosols↗
PubMed1992

Prostaglandin E2 level in tissue surrounding aseptic failed total hips. Effects of materials.

Production of inflammatory mediators (IM) by cells and specifically macrophages around loosened implants may be responsible for their loosening. Our hypothesis was that different materials give rise to different amounts of these IM. It is thought that alumina/alumina for total hip replacement (THR), which has been used for 15 years in our orthopedic department, may produce less IM than other systems. We initiated a clinical prospective study to measure the level of prostaglandin E2 (PGE2) in tissue surrounding loosened prostheses to quantify PGE2 production regarding the types of material involved in the friction couple, i.e., alumina/alumina versus metal/polyethylene, and the type of fixation, i.e., cemented versus cementless. A total of 29 THR revisions were performed in 28 patients. Four implant groups were identified: alumina/alumina cemented, alumina/alumina cementless, metal/polyethylene cemented, and metal/polyethylene cementless. For each revision, tissues surrounding the failed implants were harvested and processed, and the PGE2 was measured in a blind manner using an immunoassay technique. As the measuring technique was difficult, at least three determinations for each sample were necessary. Some samples were excluded from the analysis for various reasons, for example, second or further revisions involving many different materials in the past, conjunction of metallic and alumina debris and samples taken from non-loosened components. Finally, 15 samples were considered adequate for inclusion in this study. Two groups were analyzed and compared: the alumina/alumina couple and the metal/polyethylene couple. Tissue surrounding the first group demonstrated a PGE2 level of 69 +/- 56 fmol/mg wet weight compared to 202 +/- 156 fmol/mg for the second.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetabulum↗
PubMed1990

Detection and differentiation of picornaviruses in clinical samples following genomic amplification.

A polymerase chain reaction (PCR) assay was used to detect and differentiate picornaviruses (PVs), using primers homologous to the 5' non-coding and VP2 regions of the PV genome. The PCR resulted in a 530 bp PCR product for human rhinoviruses (HRVs) and a 650 bp product for polioviruses, coxsackieviruses (CV) or echoviruses. The PCR assay could detect as little as 1 p.f.u. of virus in either cerebrospinal fluid (CSF) or stool, using ethidium bromide-stained gels. Standard strains of poliovirus, CV, echovirus and HRV were detected, with the exception of echovirus type 22. In contrast, heterologous viruses, such as herpes simplex virus, human cytomegalovirus, adenovirus, influenza virus and rotavirus, as well as human and monkey cell DNA, were not amplified. In nasal swabs taken from patients with respiratory infections, the PCR detected 27 of 28 HRV isolation-positive specimens. All specimens from which viruses other than HRVs were isolated were negative by PCR. The PCR definitively identified poliovirus and CVs from the CSF or stool of patients with aseptic meningitis, as well as CV in the pericardial fluid of a patient who had suffered a myocardial infarction. Specimens taken from patients with similar pathologies, and from which heterologous viruses were isolated, were uniformly negative by PCR.

Base Sequence↗
PubMed1996

Sandfly fever viruses in Italy.

Two serologically distinct agents, the sandfly fever Sicilian and the sandfly fever Naples viruses, were isolated by Sabin from blood samples taken during an Italian epidemic of febrile illness. Since then, several different viruses have been isolated from sandflies and/or humans in both the Old and New World. Toscana virus, a new virus closely antigenically related to sandfly fever Naples virus, was isolated in 1971 from the sandfly Phlebotomus perniciosus in Italy. Extensive studies on the importance of Toscana virus as a human pathogen demonstrated its association with acute neurologic diseases. A serosurvey for the presence of antibodies to sandfly fever Sicilian, sandfly fever Naples and Toscana viruses indicated that, as in other Mediterranean areas, both sandfly fever Sicilian and sandfly fever Naples viral infections decreased or disappeared after the 1940s in countries performing insecticide-spraying malaria eradication campaigns. In contrast, clinical cases of aseptic meningitis or meningoencephalitis caused by Toscana virus are observed annually in Central Italy during the summer. Toscana virus may be present in other Mediterranean countries where sandflies of the genus Phlebotomus are present.

Animals↗
PubMed2005

Shelf lives of aseptically prepared medicines--stability of hydrocortisone sodium succinate in PVC and non-PVC bags and in polypropylene syringes.

Parenteral aseptic preparations of hydrocortisone sodium succinate (HSS) are used frequently in hospitals, but little definitive stability information is available. The purpose of this study was to obtain ultimate shelf lives for typical formulations so that they may be prepared in bulk in appropriately licensed facilities. In the first study, the stability of HSS, 1mg/ml, was determined in polyvinyl chloride (PVC) bags and polyolefine (non-PVC) bags, in 0.9% (w/v) sodium chloride at 7 degrees C, 25 degrees C/60% relative humidity (RH) and room temperature in the light (RTL) with storage for up to 135 days. In the second study, the stability of HSS, 50 mg/ml was determined in polypropylene syringes at 5 degrees C and 25 degrees C/60%RH with storage for up to 120 days. Samples from each admixture were analysed by stability indicating high performance liquid chromatography (HPLC) and were monitored for pH, appearance of solution and container, and the rate of appearance of decomposition products. Shelf lives were calculated using the maximum rate method. HSS at a concentration of 1 mg/ml in PVC bags was stable for up to 41 days at 7 degrees C, 8 days at 25 degrees C and 7 days at RTL. It was stable in non-PVC bags for up to 48, 8 and 6 days, respectively. HSS in polypropylene syringes at a strength of 50 mg/ml was stable for up to 81 days at 5 degrees C and 6 days at 25 degrees C.

Asepsis↗
PubMed2002

Bacterial contamination in postmortem bone donors.

We analyzed factors influencing the contamination rate of allografts and blood samples obtained from postmortem bone donors. 5,710 allografts were harvested, from 550 donors of which 3,164 (55%) were swab culture negative. Blood cultures were positive in 140 donors (26%). The risk of graft contamination increased with each extra team member (Odds Ratio 1.9). It was also higher with organisms of greater virulence in donors with a positive blood culture (OR 3.5). The risk of blood contamination increased per hour postmortem (OR 1.1) and the same increase was seen with organisms of high virulence. In donors with multiple trauma, the risk of blood contamination with organisms of high virulence was greater (OR 8.2), but smaller in donors with preceding organ procurement (OR 0.1). To minimize the bacterial load, donors should be obtained in operating rooms, using aseptic techniques with only a few personnel for procurement. The postmortem time should be kept to a minimum. The procurement cultures from donors with multiple trauma should be carefully interpreted. Blood cultures should be taken into account, since these can help to find contamination not detected by swab cultures.

Bacterial Infections↗
PubMed2000

Elevated interleukin-12 in pseudosynovial fluid in patients with aseptic loosening of hip prosthesis.

Loosening of a prosthesis is a major problem in total joint arthroplasty. To assess levels of cytokines in patients with such loosening, we measured the pseudosynovial fluid concentration of the following cytokines; tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1beta, IL-4, IL-6, IL-10, IL-12, matrix metalloproteinase (MMP)-1, and MMP-3. We examined the pseudosynovial fluid in patients with a loose hip prosthesis (group A; n = 8) and the synovial fluid in patients with osteoarthritis (OA) of the hip (group B; n = 18) using enzyme-linked immunosorbent assays. The mean concentration of IL-12 was significantly higher in group A than in group B (P < 0.01). Also, we found a significant (P < 0.05) correlation between the concentration of IL-12 and the concentration of MMP-1 in the patients with prosthesis loosening. The concentrations of TNF-alpha, IL-1beta, IL-4, IL-6, IL-10, IFN-gamma, MMP-1, and MMP-3 appeared to be similar in the two groups, although the small number of samples available precluded us from determining that there was no significant difference. The present study is the first to report elevated IL-12 levels in the pseudosynovial fluid of patients with a loose prosthesis. The immunoregulatory effect of IL-12 against wear particles could play an important role in causing loosening of the prosthesis.

Aged↗
PubMed2006

Assessment of a three-dimensional measurement technique for the porosity evaluation of PMMA bone cement.

In vitro testing of bone cement has historically resulted in the belief that porosity should be minimised to help reduce the risk of prosthesis failure through aseptic loosening. Traditional porosity measurement techniques rely on the analysis of a two dimensional representation of a three dimensional structure. However, with an increasing interest in the number, size and distribution of pores in bone cement, the reliability of a two dimensional approach is questionable. The purpose of this study was to investigate the use of micro computed tomography (micro-CT) for the three dimensional measurement of bone cement porosity by comparison with two traditional techniques. Eighteen bone cement specimens were analysed for porosity using each technique. Levels of agreement between techniques were evaluated, and technique precision was assessed in terms of repeatability and sensitivity to changes in threshold. Micro-CT data was used to illustrate the effectiveness of predicting the porosity of a whole structure from a sample region; an approach often used with traditional techniques. In summary, poor agreement was found between all techniques. However, micro-CT was found to be significantly more repeatable and less sensitive to changes in threshold. The results demonstrated that porosity cannot be reliably determined using traditional techniques and that a large proportion of a specimen is required to provide an accurate porosity measurement.

Biocompatible Materials↗
PubMed2001

D- and L-lactate in rabbit and human bacterial meningitis.

Increased total CSF lactate is an important indicator differentiating bacterial from aseptic meningitis. Bacteria can produce D- and L-lactate; mammalian cells produce only L-lactate. We measured D- and L-lactate production of Streptococcus pneumoniae, Staphylococcus aureus, Neisseria meningitidis and Escherichia coli in vitro, of S. pneumoniae and E. coli in rabbit experimental meningitis and of various common pathogens in CSF from patients with bacterial meningitis. Despite marked in vitro production of D-lactate by S. aureus (maximum: 4.59 mmol/l; i.e. 34.9% of total lactate), N. meningitidis (4.62 mmol/l; i.e. 98.1%) and E. coli (3.14 mmol/l; i.e. 97.2%), minimal amounts were measured in human S. aureus (0.38 mmol/l; i.e. 1.3% of total lactate) or N. meningitidis (0.28 mmol/l; i.e. 3.9%) and experimental E. coli meningitis (0.75 mmol/l; i.e. 4.4%). In only 9 of 54 human CSF samples did D-lactate exceed 0.15 mmol/l. S. pneumoniae did not produce significant amounts of D-lactate in vitro (maximum: 0.55 mmol/l; i.e. 2.7% of total lactate), in experimental meningitis (0.18 mmol/l; i.e. 3%) or in human cases of meningitis (0.28 mmol/l; i.e. 1.9%). In conclusion, increased total CSF lactate in meningitis consists mainly of L-lactate and originates predominantly from host cells. CSF D-lactate is of limited diagnostic value.

Animals↗
PubMed1982

Comparison of long-bone radiographs between U.S. Navy divers and matched controls.

The long-bone radiographs of a group of nondivers consisting of 177 U.S. Navy enlisted men were compared to the long-bone radiographs of 93 U.S. Navy enlisted divers who were 35 years of age and older. The nondiver control group was matched to the diver group for age, rank, and occupational specialty. Divers were found to have significantly more films classified as positive for aseptic bone necrosis (ABN) and bone cysts than nondivers, while the nondiver group had more films classified as doubtful for ABN than the diver group. The two groups were similar in the number of members classified as having bone islands and sclerotic areas. X-ray classifications by highly experienced radiologists were found to be only moderately reliable. These data indicate that diving as practiced by the U.S. Navy contributes independently to the development of ABN and bone cysts evidenced among divers in this age group. Some caution must be exercised in interpreting these findings, however, because of the larger number of doubtful films found for the nondiver group than for the diver group, the small number of positive and doubtful cases found in either group, the age of the samples used (35 years of age and older), and the substantial degree of unreliability demonstrated in classification of the films.

Adult↗
PubMed1999

Cytokine response of human macrophage-like cells after contact with polyethylene and pure titanium particles.

The aim of this study was to establish a human macrophage cell culture system to examine the effect of polyethylene (PE) and titanium particles on cytokine release by macrophage-like cells (MLC) and to quantify this response with respect to the nature and concentration of particles. Human monocytic leukemia cells were differentiated under standard conditions with vitamin D3 and granulocyte macrophage-colony-stimulating factor. Cells were characterized by fluorescence-activated cell-sorter Scan of CD 14 expression analysis as well as a phagocytosis test exploiting fluorescence-labeled particles of bacteria] walls. To achieve a relevant contact between the floating PE particles (approximately 1 microm in size) and MLC, a rotation device was used (15 rotations/min) during incubation. The same was done with the titanium particles. Cell culture supernatants were then analyzed for interleukin (IL)-1beta, IL-8, and tumor necrosis factor (TNF)-alpha using the enzyme-linked immunosorbent assay technique in the absence or presence of particles. Rotation of incubated MLC alone did not influence the secretion of TNF-alpha, but it enhanced secretion of IL-1beta and IL-8 about 30-fold compared to background levels. Both PE and titanium particles significantly enhanced MLC cytokine release, the amount of which depended on the concentration of particles. Using 40 X 10(8) PE particles (0.7 x 10(8) titanium particles) and 10(6) MLC, the maximal release of IL-1beta was about 20-fold (7-fold titanium particles) higher than that of the rotating control sample. The stimulation of IL-8 release was 4-fold (3-fold titanium particles) and of TNF-alpha. 300-fold (170-fold titanium particles) compared to controls. MLC were viable (>90% cell survival) at concentrations less than 108 x 10(8) polyethylene particles per 10(6) MLC and 16 x 10(8) titanium particles per 10(6) MLC. Rotation per se as well as exposure to increasing concentrations of PE and titanium particles stimulates cytokine release (TNF-alpha, IL-1beta, IL-8) by macrophages in vitro. This in vitro model resembles the in vivo situation near arthroplasties, where implant particles make contact with inflammatory cells, such as macrophages. Cytokine release by macrophages may impair osteoblast function as well as stimulate bone resorption by osteoclasts and macrophages, thereby causing aseptic loosening of arthroplasties. Our in vitro model provides a reproducible human cell system that might shed light on the pathogenesis of particle disease and might serve as a reproducible in vitro test system for the biocompatibility of foreign materials.

Cell Culture Techniques↗