SEARCH · PubMed Health

Results for “Contamination”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources

PubMed2001

Prevention of mycoplasma contamination in leukemia-lymphoma cell lines.

The contamination of cell lines with mycoplasmas is certainly one of the major problems occurring in cultured cells. Analyzing more than 460 human leukemia-lymphoma (LL) cell lines, we found that 28% of the cultures were mycoplasma-positive. Mycoplasmas can produce extensive changes, growth arrest and cell death in the infected cultures. While mycoplasma-infected cell lines can be truly cleansed from the contaminants, all the efforts would be in vain when the cells return to a mycoplasma-infested environment or are handled with unsuitable culture practices. Hence, the main focus of mycoplasma control should be on preventing cell culture contamination. Mycoplasmas can be introduced through several routes including culture reagents and laboratory personnel. Cross-contamination from infected cell cultures within one laboratory continues to be the major source for the spread of mycoplasma. Specific technical protocols and cell culturing guidelines may be followed in order to minimize the risk of mycoplasma contamination of cell lines. This "good culture practice" is of utmost importance as faulty cell culture techniques appear to be also the main reason for the high incidence of cross-contaminated LL cell lines which according to our experience using DNA fingerprinting of some 500 LL cell lines is about 15%.

Bacteriological Techniques↗

PubMed2002

Fish (Fundulus heteroclitus) populations with different exposure histories differ in tolerance of creosote-contaminated sediments.

Prior studies suggest that field-collected fish (Fundulus heteroclitus) from a creosote-contaminated Superfund site (Atlantic Wood Industries site, Elizabeth River, VA, USA) have enhanced tolerance to local, contaminated sediments. This study was designed to test whether other populations in the Elizabeth River at less contaminated sites also show similar tolerance and whether this tolerance is heritable. To test this, F. heteroclitus populations were sampled from four sites within the Elizabeth River with varying sediment polycyclic aromatic hydrocarbon (PAH) concentrations (3.9-264 ng PAH/g dry wt 10(3)) and one reference site in a nearby, uncontaminated estuary (York River, VA, USA; 0.27 ng PAH/g dry wt x 10(3)). Embryo assays were performed to quantify population differences in teratogenic effects during contaminated sediment exposure. Atlantic Wood sediment was mixed with reference sediment to achieve a range of sediment concentrations. Minimal differences were observed in teratogenic effects among fish taken from sites within the Elizabeth River; however, embryos of fish collected from a nearby, uncontaminated York River site and exposed to contaminated sediments had a significantly higher proportion of embryos with cardiac abnormalities than those from the Elizabeth River sites. Embryos from wild-caught and laboratory-reared Elizabeth River F. heteroclitus were simultaneously exposed to contaminated sediments, and no significant tolerance differences were found between embryos from fish taken directly from the field and those reared for a generation in the lab. Differences between fish populations from the two estuaries were larger than differences within the Elizabeth River, and these differences in tolerance were heritable.

Adaptation, Physiological↗

PubMed2002

An evaluation of the success of dredging as remediation at a DDT-contaminated site in San Francisco Bay, California, USA.

Lauritzen Canal, a portion of San Francisco Bay near Richmond, California, USA, was heavily contaminated with dichlorodiphenyltrichloroethane (DDT) and dieldrin as a result of releases from a pesticide-formulating firm. In 1996 and 1997, 82,000 m3 of contaminated sediment was removed from the canal by dredging. This study evaluated the success of the dredging based largely on body burdens of DDT and its metabolites (sigmaDDT) in resident biota, with some data on sediment- and water-contaminant levels and sediment toxicity testing. Sediment disturbance during dredging introduced a pulse of sigmaDDT into the Lauritzen Canal ecosystem, and body burdens of fish and invertebrates increased 2- to 76-fold, depending on the species. Approximately 1 1/2 years after remediation, 11 of 14 indicators showed contamination comparable with or worse than the contamination that existed prior to dredging. Monitoring of mussels up to four years postdredging suggests some modest improvement, although the sigmaDDT body burden of canal mussels remained far above the norm for San Francisco Bay. The elevated sigmaDDT body burdens in biota that persisted for years after remediation reflect recent exposure and are not merely a result of slow metabolic elimination of the sigmaDDT pulse associated with dredging. Sediment sigmaDDT concentrations were low immediately after dredging, but within months, the canal bottom became covered with a veneer of fine sediment as contaminated as that that had been removed. The source of this material has not been conclusively established, but we suspect it came from slumping and erosion from the flanks of the canal beneath docks and around pilings where dredging was not done. In retrospect, either capping in place or more thorough dredging may have been more successful in reducing pesticide exposure of the biota, although there were difficulties associated with both alternatives.

Animals↗

PubMed2003

[Roles of rhizosphere in remediation of contaminated soils and its mechanisms].

Rhizosphere is a special 'ecological remediation unit' to treat contaminated soils, which contains a great quantity of microorganisms such as fungi and rhizobacteria living with plant roots. Thus, physiological and ecological roles of plant roots to remedy contaminated soils, to accumulate and to solidify heavy metals, to absorb and degrade organic pollutants in rhizosphere were illustrated, and the function of mycorrhizospheric fungi to absorb, barrier and chelate heavy metals, to degrade organic pollutants through their metabolism activities, the action of rhizobacteria to absorb and solidify heavy metals, to degrade organic pollutants in rhizosphere through their active living activities, and the combined remediation of fungi and bacteria to pollutants in rhizosphere and their relevant mechanisms were explained. It was suggested that the remediation role of rhizosphere was the main part of phytoremediation, and one of the main basic theories to remedy contaminated soils by the activity of green plants and other organisms. The use of hyperaccumulative plants in remedying soils contaminated by some heavy metals would be prospective. It would be one of the important approach to contaminated soils remediation by organic pollutants through the mechanism of screening some special plants whose roots had strong secreting ability to absorb and accumulate dissolvent organic pollutants on the basis of inoculating specific or non-specific fungi and bacteria from the rhizosphere. This will be a developing trend of research on the remediation of contaminated soils by organic pollutants.

Bacteria↗

PubMed2003

[Bacterial contamination: epidemiology in cataract surgery].

PURPOSE: To evaluate anterior chamber (AC) bacterial contamination at the end of cataract surgery in a large series of patients, to determine the influence of operative technique on ocular contamination. METHODS: Retrospective study of 2,624 patients undergoing cataract extraction, 354 extracapsular cataract extraction (ECCE) and 2,270 phacoemulsification. Anterior chamber aspirates were performed on completion of surgery for microbiological studies. RESULTS: One hundred and thirty two patients (5%) had culture-positive anterior chamber aspirates. Coagulase-negative Staphylococcus, Propionibacterium sp. and Corynebacterium sp. were the most commonly isolated organisms. The AC contamination rates during ECCE (5.6%) and phacoemulsification (4.7%) were not statistically different. There was a statistically significantly higher risk of AC contamination in eyes receiving an intraocular lens (IOL) with polypropylene haptics (9.9%) than in eyes receiving the same IOL with polymethylmethacrylate haptics (4.4%). CONCLUSION: Surgical technique had no statistically significant effect on ocular contamination. Polypropylene haptics IOLs were associated with a higher risk of bacterial contamination.

Biocompatible Materials↗

PubMed1976

Evaluation of microbial contamination of surgical gloves during actual use.

The contamination rate of gloves is about the same for all scrubbed personnel, be they single or double gloves (33%). More holes are noted in the gloves of personnel who use their hands more strenuously. A double pair of gloves does not reduce the amount of contamination but does reduce the number of holes. The contamination could not be associated with the hole in the glove in our study. The amount of contamination beneath the glove does not influence its exterior contamination. Contamination generally comes from somewhere else in the operative field environment.

Bacteria↗

PubMed2003

Detection and treatment of mycoplasma contamination in cultured cells.

BACKGROUND: Mycoplasmas, the smallest and simplest prokaryotes that reside in endosomes of mammalian cells, are widespread contaminants found in cell cultures. About 30% of all cell cultures, varying from 15 to 80%, are reportedly contaminated with mycoplasmas. Here, we present our experience in successfully detecting and treating mycoplasmal infection in various cell lines. METHODS: The nested polymerase chain reaction (PCR) detection and microscopic examination, including phase-contrast, fluorescent, as well as differential interference contrast, were used for detecting potential mycoplasma contamination of cell lines used in our laboratory. As soon as mycoplasma was identified, antibiotic treatment was initiated. RESULTS: Mycoplasmal contamination was detected in six of 15 cell lines using the nested PCR amplification of mycoplasma DNA, which was further demonstrated using 4, 6-Diamidino-2-phenylindole (DAPI) staining and fluorescent microscopy. Alternate treatment with two antibiotics, macrolide (tiamulin) and tetracycline (minocycline), effectively eliminated mycoplasma, which was validated by both PCR and microscopic studies. CONCLUSIONS: The nested PCR using genomic DNA extracted from cultured cells as templates is a rapid and sensitive method for detecting mycoplasma contamination. Treatment with combined antibiotics can completely eradicate mycoplasmal infection from cultured cells. For the ease of use, PCR and/or DAPI staining appear suitable for detecting potential mycoplasmal contamination in laboratories that rely heavily on the cell culture system.

Anti-Bacterial Agents↗

PubMed1992

Streptomycin-resistant Escherichia coli as a marker of vulvovestibular contamination of endometrial culture swabs in the mare.

To investigate the vulvovestibular contamination of endometrial culture swabs in the mare, a liquid culture of a streptomycin-resistant strain of Escherichia coli was applied to the vulvovestibular area of mares and used as a marker of contamination of endometrial culture swabs. Prior to taking endometrial swabs, the perineal area was washed with soap, rinsed with water, and dried. Endometrial culture swabs were taken from mares that were in anestrus or diestrus and from mares that were in estrus. When a manual transvaginal swabbing technique was used, 22 of 24 endometrial swab specimens from 12 mares were contaminated with the experimental bacterial strain; culture of only one endometrial swab yielded more than nine colonies. When a speculum approach was employed, three of 12 swab specimens from 12 mares yielded between one and three colonies. The stage of cycle had no effect on the extent of contamination, but the proportion of positive cultures was significantly smaller when swabs were taken via a vaginal speculum approach, compared to a manual transvaginal approach. Complete preclusion of vulvovestibular contamination of endometrial swab specimens was not achieved; however, fewer than ten colonies can be expected even in mares in which the vulvovestibular area has been thoroughly contaminated with a broth culture, provided that the perineal area is adequately cleaned prior to swabbing.

Anestrus↗

PubMed2004

Hydrogen-based, hollow-fiber membrane biofilm reactor for reduction of perchlorate and other oxidized contaminants.

Many oxidized pollutants, such as nitrate, perchlorate, bromate, and chlorinated solvents, can be microbially reduced to less toxic or less soluble forms. For drinking water treatment, an electron donor must be added. Hydrogen is an ideal electron donor, as it is non-toxic, inexpensive, and sparsely soluble. We tested a hydrogen-based, hollow-fiber membrane biofilm reactor (MBfR) for reduction of perchlorate, bromate, chlorate, chlorite, chromate, selenate, selenite, and dichloromethane. The influent included 5 mg/L nitrate or 8 mg/L oxygen as a primary electron accepting substrate, plus 1 mg/L of the contaminant. The mixed-culture reactor was operated at a pH of 7 and with a 25 minute hydraulic detention time. High recirculation rates provided completely mixed conditions. The objective was to screen for the reduction of each contaminant. The tests were short-term, without allowing time for the reactor to adapt to the contaminants. Nitrate and oxygen were reduced by over 99 percent for all tests. Removals for the contaminants ranged from a minimum of 29% for chlorate to over 95% for bromate. Results show that the tested contaminants can be removed as secondary substrates in an MBfR, and that the MBfR may be suitable for treating these and other oxidized contaminants in drinking water.

Biofilms↗

PubMed2005

Low-dose infectivity of Staphylococcus aureus (SMH strain) in traumatized rat tibiae provides a model for studying early events in contaminated bone injuries.

Animal models of post-traumatic acute osteomyelitis (OM) that closely mimic human scenarios, including infection prophylactic procedures such as debridement and lavage, may provide a better understanding of OM. We contaminated mechanically traumatized rat tibiae (n = 69) with various doses of a Staphylococcus aureus strain (SMH) known to cause human OM and then performed curettage and lavage. Tibiae were harvested 24 h after lavage for assessment of bacterial load and determination of minimal infective doses for 50% (ID50) and 95% (ID95) of rats. Some experiments varied tibial harvest time after lavage (n = 10); for progressive infection, tibiae were evaluated at 7 and 15 days after contamination (n = 17 for each time point). At 24 h after contamination, the ID50 was 1.8 x 10(3) CFU, and the ID95 was 9.2 x 10(3) CFU. Tibial bacterial loads did not increase with inocula greater than the ID95. Lavage removed many bacteria from bone, but it did not prevent subsequent infection or disease. At 15 days after contamination, most tibiae (14 of 17) were infected, with macroscopic and radiological signs of established OM. This newly described rat OM model, with a low ID95 despite prophylactic curettage and lavage, closely mimics events in contaminated human bone injuries. This situation will allow study of early factors in contaminated bone injuries, including clinical interventions that may reduce infection and prevent disease.

Animals↗

PubMed2001

Evaluation of the intrinsic mtbe biodegradation potential in MTBE-contaminated soils.

MTBE has only recently being used as an octane enhancer in gasoline in Europe and is considered as a more recent groundwater contaminant on this continent. In this study we examined if during the recent contamination history, European MTBE contaminated aquifers had developed MTBE degrading microbial communities. Different MTBE contaminated and non-contaminated aquifers and soils were tested for their intrinsic biodegradation potential. The role of the oxygen concentration, the availability of nutrients and the influence of the presence of a co-contaminant like benzene on the MTBE biodegradation capabilities of the indigenous microorganisms were examined. All studied soil samples showed degradation of benzene under all tested conditions. On the other hand only one aquifer showed the capacity to degrade MTBE as demonstrated by the disappearance of MTBE and the production of TBA, the main degradation product of MTBE.

Biodegradation, Environmental↗

PubMedDate not supplied

Salivary contamination and bond strength of glass-ionomers to dentin.

This study evaluated the effect of salivary contamination on the shear bond strength of two highly viscous glass ionomer cements (Fuji IX GP Fast and Ketac-Molar Maxicap) to conditioned dentin and assessed the effect of cleaning the contaminated field prior to bonding. The buccal surfaces of 90 human molars and premolars were ground to expose dentin and the teeth were then set in resin. The specimens were divided into two groups for each material, then further subdivided into three groups of 15 teeth each: Group 1--uncontaminated (control), Group 2--dentin contaminated with saliva, Group 3--dentin contaminated, washed and air dried. The specimens were made by bonding the test material to dentin using a 4 mm diameter gelatin capsule. All specimens were protected with varnish and placed in distilled water at 37 degrees C for seven days prior to measuring bond strength in shear. Fractured surfaces were examined visually and by using SEM to assess mode of failure. There were no significant differences in mean shear bond strength among the three test groups for either material (ANOVA). However, shear bond strength of Fuji IX to dentin was significantly greater than Ketac-Molar (p=0.019) for all groups. Weibull analysis showed that contaminated (Group 2) specimens had a greater probability of failure at low stresses. Modes of failure were mostly cohesive for Fuji IX and adhesive/cohesive for Ketac-Molar. In conclusion, salivary contamination did not affect the mean shear bond strength of Fuji IX GP Fast and Ketac-Molar Maxicap to conditioned dentin; however, it increased the probability of failure at low stresses.

Adhesiveness↗

PubMedDate not supplied

Shear bond strength of pit-and-fissure sealants to saliva-contaminated and noncontaminated enamel.

PURPOSE: The purpose of this study was to investigate the shear bond strength of 2 resin-based pit-and-fissure sealants--Clinpro and Fluroshield--to saliva-contaminated and noncontaminated enamel. METHODS: Forty buccal halves of permanent molar crowns were individually embedded in polyester resin and ground with wet silicone carbide papers to obtain flat enamel surfaces. The specimens were randomly assigned to 2 groups: (A) without contamination; and (B) contaminated with 0.01 ml of fresh human saliva. Each group was divided into 2 subgroups (N=10), according to the sealant applied: (1) Clinpro; and (2) Fluroshield. Shear bond strength was tested at a crosshead speed of 0.5 mm/min. Failure mode was assessed. RESULTS: Means (MPa) were: (1) A1=7.66 +/- 3.12; A2=12.39 +/- 4.34; (2) B1=5.05 +/- 1.44; B2=10.44 +/- 2.35. Data were submitted to analysis of variance and Scheffé's statistical test (P<.05). There was a statistically significant difference (P<.05) between both the sealants and the experimental conditions analyzed. Fluroshield provided higher bond strength and was different from Clinpro (P<.05) in the absence of contamination. Within the saliva-contaminated group, however, no statistically significant difference (P>.05) was observed between the tested materials. CONCLUSIONS: It may be concluded that, under dry conditions, the filled pit-and-fissure sealant (Fluroshield) yielded better bonding performance. Salivary contamination undermined the adhesion of both materials to enamel and resulted in lower bond strengths.

Analysis of Variance↗

PubMed2006

Prevention of iatrogenic transmission of B19 infection: different approaches to detect, remove or inactivate virus contamination.

Parvovirus B19 is a frequent contaminant of human blood and plasma derivatives and iatrogenic transmission of B19 infection has been shown to occur through the administration of contaminated products. Manufacturing procedures, generally used for removal or inactivation of enveloped viruses (HIV, HCV and HBV) are not always effective in the elimination of B19 virus. A certain risk of contamination remains for some plasma derivatives due to the high-titer viral load in the starting blood donations and the extreme heat resistance and small size of the virus. This review provides an update on the different approaches currently available to detect, remove or inactivate B19 virus in order to enhance the safety margins of plasma products. Nucleic acid amplification techniques are the methods of choice for the detection of viruses, due to their high specificity and sensitivity. NAT assays are beneficial tools for the identification of contaminated mini-pools or plasma pools and the quantification of B19 contamination. They may also be valuable for testing the removal of B19 virus during manufacturing: since the virus may not be completely inactivated or removed by chemical or physical treatments, residual B19 contamination should always be checked. Solvent-detergent treatments fail to destroy B19 capsids because of the absence of a lipid-envelope, and heat treatments (pasteurization and dry-heat methods) cannot guarantee a complete viral inactivation because of the variable heat sensitivity of the virus.

Blood Component Transfusion↗

PubMed2006

Detecting bacterial contamination in platelet products.

Bacterial contamination of platelets is an important cause of transfusion-associated morbidity and mortality. It is currently the most frequent infectious complication of transfusion therapy, with between 1 in 1,000 and 1 in 3,000 platelet units being bacterially contaminated at time of transfusion. Several factors have contributed to the persistence of this problem including lack of sensitive detection methods, lack of recognition of the frequency of the problem, inadequate recognition of septic reactions by clinicians treating patients receiving platelet transfusions, differences in transfusion reactions between bacterial species and bacterial inocula transfused, and differing methodologies and time of testing for detection of bacteria in platelet units. There are also important correlations between the receipt of bacterially contaminated platelet units and the development of transfusion reactions and bacteremia. In the last few years the recognition of the importance of platelet bacterial contamination prompted the College of American Pathologists (CAP) and the American Association of Blood Banks (AABB) to set new standards requiring the screening of platelets for bacterial contamination. In the wake of these standards, an increasing number of approaches have been and are being developed to deal with this problem. The clinical sensitivity, specificity and predictive value of these detection methods vary considerably and need to be defined for routine laboratory practice. In this review, we focus on the practical aspects and feasibility of implementing FDA-cleared detection methods for identifying bacterially contaminated platelet units. We also present details of a number of methods under development for at-issue use.

Bacteria↗

PubMed2006

Removal of heavy metals from a contaminated soil using tartaric acid.

This study reports the feasibility of remediation of a heavy metal (HM) contaminated soil using tartaric acid, an environmentally-friendly extractant. Batch experiments were performed to test the factors influencing remediation of the HM contaminated soil. An empirical model was employed to describe the kinetics of HM dissolution/desorption and to predict equilibrium concentrations of HMs in soil leachate. The changes of HMs in different fractions before and after tartaric acid treatment were also investigated. Tartaric acid solution containing HMs was regenerated by chestnut shells. Results show that utilization of tartaric acid was effective for removal of HMs from the contaminated soil, attaining 50%-60% of Cd, 40%-50% of Pb, 40 %-50% of Cu and 20%-30% of Zn in the pH range of 3.5-4.0 within 24 h. Mass transfer coefficients for cadmium (Cd) and lead (Pb) were much higher than those for copper (Cu) and zinc (Zn). Sequential fractionations of treated and untreated soil samples showed that tartaric acid was effective in removing the exchangeable, carbonate fractions of Cd, Zn and Cu from the contaminated soil. The contents of Pb and Cu in Fe-Mn oxide fraciton were also significantly decreased by tartaric acid treatment. One hundred milliliters of tartaric acid solution containing HMs could be regenerated by 10 g chestnut shells in a batch reactor. Such a remediation procedure indicated that tartaric acid is a promising agent for remediation of HM contaminated soils. However, further research is needed before the method can be practically used for in situ remediation of contaminated sites.

Decontamination↗

PubMed2006

Organic contaminants in Croatian municipal wastewaters.

Municipal wastewaters are among the most important sources of waste materials released into the environment. In Croatia, this problem is especially pronounced since only 4.4% of the total wastewaters are subject to complete mechanical and biological treatment. Beside a limited number of regulated organic contaminants, wastewaters contain an extremely high number of different potentially harmful organic compounds. Comprehensive analyses of Croatian wastewaters using mass spectrometric techniques (GC/ MS, LC/MS) indicated the presence of a large number of different organic compounds with a predominance of two main groups of contaminants: petroleum hydrocarbons and detergent-derived surfactants. Recent investigations of specific organic contaminants in wastewater focused on the determination of so-called emerging contaminants, whose ecotoxicological relevance is based on new types of biological effects and for which water quality criteria have not yet been defined. The main goal of this paper is to make an overview of the present knowledge on the occurrence of different types of organic contaminants in Croatian municipal wastewaters, paying special attention to the emerging contaminants.

Croatia↗

PubMed1991

Wound contamination and postoperative infection. A review.

The risk of postsurgical infection is closely related to the type of operation performed. Wound sampling by Raahave's velvet pad method shows that operation wounds harbour ordinary aerobic and anaerobic commensals after incision (exogenous flora). When bacteria-containing viscera are opened or found perforated, bacterial densities increase significantly before wound closure (endogenous flora). Contamination level justifies the criteria for use of wound class, i.e. clean, potentially contminated, contaminated and dirty. There is a dose-response relationship between the density of bacteria during operation and postsurgical wound sepsis. The median infective dose of aerobic and anaerobic bacteria is 4.6 x 10(5) CFU x cm-2 wound. The surgeon opens up tissue planes which are primarily sterile and breaks natural barriers. However, using a trained technique, the surgeon should be able to control wound contamination safely throughout the operation. Although hos immunity and tissue resistance intervene between contamination and infection, the magnitude of contamination seems crucial. It ought to be axiomatic by now that reducing bacterial contamination reduces infection.

Anti-Bacterial Agents↗