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 1,045 records · Page 58Linked to original sources

PubMed1999

Some characteristics of platelet concentrates contaminated with Staphylococcus epidermidis.

The study investigates platelet concentrates (PCs) contaminated with Staphylococcus epidermidis. The work was conducted using 12 pairs of PCs. Light transmission through the PCs was observed over 7 days. Immediately after preparation, one PC was inoculated with Staphylococcus epidermidis (17-43 colony forming units (CFU)/ ml) and the other served as a non-contaminated control. In the contaminated PCs the CFU/ml and swirling were determined on days 1, 3 and 7. In all PCs determination of pH and the extent of shape change (ESC) was carried out on days 3 and 7. All contaminated PCs had visible swirling on day 3 but they contained 2.0 X 10 4 to 9.0 X 10 8 CFU/ml. pH (P=0.05) and ESC (P<0.05) then were slightly lower. On day 7, eight of 12 of the contaminated PCs failed to display transmission changes despite deranged analytical results and impaired swirling. During early storage the contaminated units had unimpaired swirling and only slightly impaired in vitro quality. They appear to be difficult to identify in the routine.

Journal Article↗

PubMed2003

Monitoring PAH-contaminated soil using laser-induced fluorescence (LIF).

The heterogeneity and opacity of soil matrices pose considerable challenges for the quantification of soil contaminants. In order to investigate the feasibility of applying the Laser-Induced Fluorescence technique to measure contamination levels of soils, statistical analyses of contaminant levels and intensity of fluorescence were investigated in relation to soil properties. A significant correlation (R2 > 0.97) between contaminant levels and intensity of fluorescence was shown under different matrix conditions, such as moisture content and particle size distribution. Higher fluorescence intensities were obtained from soils with higher sand and moisture content. The statistical results in relation to the interaction between fluorescence intensity and matrix properties rejected the hypothesis that all properties of the matrices and contaminants had an equal influence on fluorescence. This implied that the concentrations of contaminants had the greatest contribution to the fluorescence intensity, but other variables also showed a considerable influence.

Environmental Monitoring↗

PubMed2001

Breast tumor contamination of PBSC harvests: tumor depletion by positive selection of CD34(+) cells.

BACKGROUND: Positive selection of CD34(+) cells may reduce or eliminate tumor cells contaminating PBSC harvests of breast cancer (BrCa) patients. However, to assess tumor purging accurately methods may be needed that are of higher sensitivity than standard immunocytochemistry (ICC) assays. METHODS: BrCa-cell depletion, resulting from CD34(+) cell selection, was evaluated using a novel, highly sensitive assay based upon immunomagnetic enrichment with ICC detection in 36 BrCa patients undergoing highdose chemotherapy with autologous PBSC support. RESULTS: The prevalence of BrCa-cell contamination was significantly lower (P = 0.0078) in selected CD34(+) cell fractions (17/35, 49%) from apheresis collections compared with CD34(-) cell fractions (25/35, 71%). In 8/34 (24%) patients, BrCa cells were detected in CD34(-) cell fractions, but not in paired CD34(+) cell fractions. Significantly lower total numbers (P < 0.0005) of BrCa cells were enumerable in CD34(+) cell fractions compared with corresponding apheresis harvests. The median total BrCa-cell content of selected CD34(+) cell fractions with measurable contamination was 22 BrCa cells (range, 6-73 BrCa cells), compared with 3297 BrCa cells (range, 10-98 400 BrCa cells) in apheresis harvests. The median log depletion of BrCa cells achieved by positive CD34(+) cell selection in specimens with detectable contamination both before and after selection was 2.2 (range, 1.7-4.0). Total pre-selection BrCa cell number was significantly predictive (P = 0.004) of residual detectable post-selection contamination. DISCUSSION: Positive CD34(+) cell selection is an effective tumor purging strategy. The prevalence of PBSC contamination in BrCa patients is substantially higher than formerly appreciated.

Adult↗

PubMed2002

Health risk assessment on residents exposed to chlorinated hydrocarbons contaminated in groundwater of a hazardous waste site.

We conducted this study to estimate residents' chronic hazard and carcinogenic risk in a groundwater-contaminated community after on-site remediation in Taiwan during 1999-2000. We followed guidelines for assessing hazardous waste sites of the U.S. Environmental Protection Agency (EPA) and used empirically measured contaminant levels and exposure parameters to perform health risk assessment on seven chlorinated hydrocarbons. We measured groundwater concentrations of vinyl chloride, tetrachloroethylene, trichloroethylene, 1,1-dichloroethylene, 1,1,1-trichloroethane, cis-1,2-dichloroethylene, and 1,1-dichloroethane in 49 off-site residential wells by gas chromatography/mass spectrometry. Exposure parameters were mainly derived from our field survey of 382 residents, and partially from U.S. EPA default values. Total exposure dose estimation included routes of inhalation during showering and dermal absorption of showers and other activities involved with hand-water contacts. The ingestion route of water was not included because most residents drank boiled water with negligible contaminants. We calculated a hazard index (HI) for all seven chlorinated hydrocarbons and carcinogenic risks for known human carcinogen of vinyl chloride and probable human carcinogens of tetrachloroethylene and trichloroethylene, which had the same target organ, the liver. The HI values for reasonable maximal exposure (RME) and average exposure were 14.3 and 0.2, respectively. The cancer risks based on RME and average exposure (in parentheses) for vinyl chloride, tetrachloroethylene, and trichloroethylene were 8.4 x 10(-6) (7.3 x 10(-9)), 1.9 x 10(-4) (1.3 x 10(-7)), and 1.4 x 10(-4) (1.2 x 10(-6)), respectively. We applied Monte Carlo simulations to the sensitivity analysis, which showed that the contaminant levels, exposure duration, and time for showers were major determinants of health risks. We concluded that the contaminated groundwater was still unsafe for use even after the contaminated site underwent remediation by extraction and treatment in 1997.

Baths↗

PubMed2005

Contaminant loads and hematological correlates in the harbor seal (Phoca vitulina) of San Francisco Bay, California.

An expanding body of research indicates that exposure to contaminants may impact marine mammal health, thus possibly contributing to population declines. The harbor seal population of the San Francisco Bay (SFB), California, has suffered habitat loss and degradation, including decades of environmental contamination. To explore the possibility of contaminant-induced health alterations in this population, blood levels of polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE), and polybrominated diphenyl ethers (PBDEs) were quantified in free-ranging seals; relationships between contaminant exposure and several key hematological parameters were examined; and PCB levels in the present study were compared with levels determined in SFB seals a decade earlier. PCB residues in harbor seal blood decreased during the past decade, but remained at levels great enough that adverse reproductive and immunological effects might be expected. Main results included a positive association between leukocyte counts and PBDEs, PCBs, and DDE in seals, and an inverse relationship between red blood cell count and PBDEs. Although not necessarily pathologic, these responses may serve as sentinel indications of contaminant-induced alterations in harbor seals of SFB, which, in individuals with relatively high contaminant burdens, might include increased rates of infection and anemia.

Animals↗

PubMed1991

The case for a cause-effect linkage between environmental contamination and development in eggs of the common snapping turtle (Chelydra S.serpentina) from Ontario, Canada.

Concentrations of polychlorinated biphenyls (PCBs), dibenzo-p-dioxins, and dibenzofurans, organochlorine pesticides, and their metabolites were measured in eggs of the common snapping turtle (Chelydra s.serpentina) collected from four wetlands on the shorelines of Lakes Ontario, and Erie, and one control location in central Ontario, Canada. Snapping turtle eggs from these sites were also artificially incubated to determine hatching success, and incidence of deformities in embryo and hatchling turtles. The hypothesis that elevated incidences of egg death and/or deformities of hatchling turtles would occur in populations with high concentrations of organochlorine contaminants in eggs was tested. The results were elevated using epidemiological criteria. Unhatched eggs and deformities occurred at significantly higher rates in eggs from Lake Ontario wetlands. Two of three sites from Lake Ontario had substantially higher levels of PCBs, dioxins, and furans compared to eggs from Lake Erie and the control site. It could not be shown that contamination of eggs preceded the occurrence of poor development of eggs, although excellent hatching success and low numbers of deformities in eggs from the control site were considered representative of development in healthy eggs. The statistical association between contaminant levels in eggs and poor development of these eggs supported the hypothesis that eggs from sites with the greatest contamination had the highest rates of abnormalities. PCBs were the most strongly associated chemicals, although possible effects due to the presence of other chemicals in eggs was a confounding factor. The deformities and rates of unhatched eggs were similar to those occurring in other vertebrates collected from highly contaminated areas of the Great Lakes. There were several chemicals present in the eggs that can cause similar reproductive effects in other species; therefore a specific chemical effect was not identified. Results were coherent with known statistical and biological information. Theoretical and factual evidence of PCB contamination in wild-caught snapping turtles supported and hypothesis. However, lack of controlled studies of reproductive effects of polychlorinated hydrocarbons upon this species hindered the agreement of all factual and theoretical evidence with the hypothesis.

Animals↗

PubMed1981

Measurements of airborne aflatoxins during the handling of contaminated corn.

Sample of airborne dust generated the handling of aflatoxin-contaminated corn were collected and analyzed to assess potential exposures of farmers and other agricultural workers to these mycotoxins. Using high volume total dust samplers and a high volume Andersen sampler, downwind dust samples were collected on glass filter when contaminated corn was transferred by augers from a storage bin into a wagon and back into the storage bin. The aflatoxin B1 content of the 15 dust samples ranged from 12.5 to 204.3 ppb, with an average of 138 ppb; the aflatoxin B2 content ranged from 1.1 to 41.6 ppb, with an average of 24.6 ppb. The B1 and B2 levels of contamination in the bulk corn were 223.9 and 17.5 ppb, respectively. The gravimetric dust concentration in the air ranged from 7 mg/m3 to 417 mg/m3. The samples taken with an Andersen sampler indicate the dust is relatively coarse with only approximately 17% less than 7 micrometer. An analysis of the dust from each stage showed higher levels of aflatoxins in the larger first-stage particles than in the finer particles on the succeeding stages. The results of this study indicate that the dust generated when handling contaminated commodities also may be contaminated and represent a potential inhalation hazard. This fact, coupled with the extreme toxicity and carcinogenicity previously demonstrated in animal studies, suggests that appropriate measures be taken to prevent worker exposure during handling of contaminated materials.

Aflatoxins↗

PubMed2001

Comparison of ex situ and in situ bioremediation of unsaturated soils contaminated by petroleum.

The most feasible bioremediation technologies of unsaturated soils contaminated by Petroleum are (1) the on-site controlled remediation of the excavated contaminated plume in the contained system; and (2) the in situ sub-surface, highly controlled process in which nutrients and microbes or air are injected into the plume volume via a grid of wells and reversing the direction of the pumping. The detailed results of ex situ (controlled aerobic bioremediation) of ten sites with differing petroleum contamination and four in situ cases are reported and compared. It is concluded, that bioremediation of petroleum contaminated soil is an effective, safe and economically feasible remediation technique for the remediation of such contaminated sites, contingent on the providing of the site-specific appropriate conditions. However, the biodegradation rate of the NAPL is more variable in the in situ than in the ex situ aerobic process, correlating best in the latter with the molecular weight of the petroleum contaminants.

Bacteria, Aerobic↗

PubMed2004

Performance comparison of interceptor trench configurations for extracting contaminated groundwater.

Computer simulations tested the capability of five alternative interceptor trench configurations to capture an enclave (plume) of contaminated groundwater. The configurations included a single linear segment and angled segments, at 90 degrees and 135 degrees, with a common endpoint. Alternative angled configurations both faced and opposed the contaminant plume. Each trench configuration had the same total length and was located the same average distance from the contaminant plume. The minimum pumping rate required to capture the plume and a surrounding buffer zone, within a prescribed time period, was determined for each trench configuration. The 90 degree plume-opposed trench performed best, requiring approximately one-third the pumping rate of the 90 degree plume-facing configuration. The plume-opposed configuration yielded a capture zone that best conformed to the actual shape of the contaminant plume, thereby reducing the amount of groundwater that had to be removed from the aquifer to remove the contaminant plume. Ironically, plume opposed configurations are rarely used in practice. Results of this study suggest that alternative interceptor trench configurations, including funnels with mouths opposed to contaminant plumes, should be tested with computer simulations when devising protocols for groundwater remediation.

Computer Simulation↗

PubMed2005

Evaluation of extraction procedures for removing lead from contaminated soil.

Soil extraction of lead contaminated soil collected from sites near an abandoned battery recycling and secondary lead-smelting factory was investigated for potential use in decontaminating soil at the sites. A fractionation study was conducted to elucidate soil retention mechanism for Pb at the site. Three soil pits were selected from an area surrounding the factory based on level of Pb contamination. Soil samples were collected from each pit in two layers: surface soil and subsoil (0-15 cm and 15-30 cm). Soil physical analysis showed that the soil texture was sandy loam and sandy clay loam with clay content between 11-21%. Soil pH was strongly acid to moderately acid (pH 4.8-5.9). Pb levels in the surface soil were 1620 and 153 mg kg(-1) (air-dried basis) respectively for heavily and slightly contaminated soil. A reference soil site contained 15 mg kg(-1) of Pb. Partitioning studies indicated that more than 90% of total Pb in the soil existed in three primary fractions: exchangeable, carbonate, and Fe-Mn oxide. This suggested that Pb sources entering the soil from the Pb factory remained in relatively weakly bound forms, which are mobile and have potentially biological availability. Mobility of Pb as in the soil assessed by mobility factor (MF) was as high as 75% indicating a high potential of Pb remobilization. Due to high mobility, the Pb would be amendable to remediation or removal by soil extraction procedures. To determine if such weekly bound Pb could be easily removed, both soil washing (ex situ) and soil flushing (in situ) techniques were evaluated for potential Pb remediation procedure. Particle size separation of soil into coarse (2.0-0.25 mm), medium (0.25-0.15 mm), and fine size (<0.15 mm) was conducted before initiating soil washing for comparing Pb removal efficiency in these fractions with the indigenous soil fraction. Using EDTA (2:1 mole to Pb) as a washing solution up to 85-95% of Pb was removed under the optimum conditions (retention time = 60 min), and liquid to solid ratio (L/S) at 5:1 for coarse fraction and 10:1 for smaller fraction. Pb could be removed from contaminated soil using EDTA extraction; however, the efficiency was higher in the coarse texture soil fraction. As a result particle size separation is recommended before application of the soil washing procedure. For smaller soil particle size fraction a series of extraction was needed for obtaining an adequate extraction efficiency. Three solvents tested as flushing solution showed 85, 84, and 74% of Pb was removed by EDTA (2:1 mole to Pb), 1M HNO3, and 0.2 M ammonium citrate, respectively after flushing with 20 pore volumes. The capacity of the three flushing solutions to remove Pb from the contaminated soil were ranked in the order: EDTA approximately 1 M HNO3 > 0.2 N ammonium citrate. However, in highly contaminated soil all solvent extract required several Pb leaching cycles. The flushing process using 1 M HNO3 increased soil acidity to extreme acid conditions (pH 2.0) resulting in adverse effects to physicochemical properties of the treated soil. In general, results showed three factors influenced Pb removal by the extraction techniques: (i) initial Pb concentrations, (ii) Pb partitioning within soil, and (iii) particle size of soil matrix.

Chelating Agents↗

PubMed2003

Impact of ring wearing on hand contamination and comparison of hand hygiene agents in a hospital.

We determined risk factors for hand contamination and compared the efficacy of 3 randomly allocated hand hygiene agents in a group of surgical intensive care unit nurses. We cultured samples of one of the subjects' hands before and samples of the other hand after hand hygiene was performed. Ring wearing was associated with 10-fold higher median skin organism counts; contamination with Staphylococcus aureus, gram-negative bacilli, or Candida species; and a stepwise increased risk of contamination with any transient organism as the number of rings worn increased (odds ratio [OR] for 1 ring worn, 2.6; OR for >1 ring worn, 4.6). Compared with use of plain soap and water, hand contamination with any transient organism was significantly less likely after use of an alcohol-based hand rub (OR, 0.3; 95% confidence interval [CI], 0.1-0.8) but not after use of a medicated hand wipe (OR, 0.9; 95% CI, 0.5-1.6). Ring wearing increased the frequency of hand contamination with potential nosocomial pathogens. Use of an alcohol-based hand rub resulted in significantly less frequent hand contamination.

Alcohols↗

PubMed2001

Effectiveness of hand-cleansing agents for removing methicillin-resistant Staphylococcus aureus from contaminated hands.

OBJECTIVE: The effectiveness of hand-cleansing agents in removing a hospital strain of methicillin-resistant Staphylococcus aureus from artificially contaminated hands of five volunteers was studied. DESIGN: The products used were plain liquid soap, ethyl alcohol 70% (by weight), 10% povidone-iodine liquid soap (PVP-I), and chlorhexidine gluconate (4%) detergent. The experiments were performed using a Latin square statistical design, with two 5x4 randomized blocks. The removal rates of S aureus cells from contaminated fingertips were estimated by analysis of variance, the response variable being the log10 reduction factor (RF), ie, log10 of the initial counts minus log10 of the final counts. In the first and second blocks, the fingertips of the volunteers were contaminated in mean with 3.76 log10 colony-forming units ([CFU] light-contamination hand) and 6.82 log10 CFU (heavy-contamination hand), respectively. RESULTS: In the first block, there were significant differences between treatments (P<.05). The 10% PVP-I (RF, 3.76) and 70% ethyl alcohol (RF, 3.51) had significantly higher removal rates than plain liquid soap (RF, 1.96) and 4% chlorhexidine (RF, 1.91). In the second block, 10% PVP-I (RF, 4.39) and 70% ethyl alcohol (RF, 3.27) also were significantly more effective than plain liquid soap (RF, 1.77) and 4% chlorhexidine (RF, 1.37; P<.05). Plain liquid soap was significantly more effective than chlorhexidine (4%) detergent. CONCLUSIONS: The results suggest that 10% PVP-I and 70% ethyl alcohol may be the most effective hand-cleansing agents for removing methicillin-resistant S aureus strain from either lightly or heavily contaminated hands.

Cross Infection↗

PubMed2001

A monte carlo approach to electron contamination sources in the Saturne-25 and -41.

The various components of the accelerator treatment head act as sources of contaminating electrons. The presence of contamination electrons increases the surface dose, which deteriorates the skin-sparing effect. The present study examines the sources of this 'contamination', the influence on the surface dose and the shape of the build-up curve. The Monte Carlo simulation of two linear accelerators, Saturne-25 and -41, allowed us to study the influence of electron contamination in various therapeutic energies and in different geometries. The Saturne-25 and -41 cover a wide range of therapeutic energies with nominal energies 12/23 MV and 6/15 MV, respectively. The analysis of the results shows that at a source-to-surface distance of 100 cm and a wide opening of the collimators, the main sources of contaminating electrons are the flattening filter and the air below it. The contribution of the secondary contamination electrons on the surface dose is 16% for 6 MV and 12 MV, 6% for 15 MV and 17% for 23 MV. The energy spectra of electrons coming from the flattening filter and the air below it are completely different. The air produces electrons of low energies. The mean energies of these spectra vary from 1 MeV to 2 MeV depending on the nominal energy of the photon beam. The secondary electrons generated by the flattening filter produce a wide energy spectrum with mean energies of the same order of the bremsstrahlung spectrum. The flattening filter absorbs the secondary electrons generated in the target, the primary collimator and the air inside the head.

Air↗

PubMed2002

Nondigestible oligosaccharides do not increase accumulation of lipid soluble environmental contaminants by mice.

Supplementing diets with nondigestible fibers that are fermented by the gastrointestinal tract bacteria increases the dimension and absorptive capacities of the small intestine; we hypothesized that this would increase the accumulation of environmental contaminants. This was tested by feeding mice for 6-8 wk diets with fiber at two levels (0 and 100 g/kg) and from different sources (cellulose, lactosucrose, polydextrose, indigestible dextrin, inulin) before a 2-wk oral exposure to (14)C-labeled mirex or methylmercury in combination with (3)H-labeled retinol. Concentrations of contaminants and retinol were measured in urine and feces collected for the last 2 d of exposure and in seven tissues (small and large intestine, brain, liver, kidneys, gastrointestinal tract mesentery, gall bladder). Mice fed the same diets, but not exposed to the contaminants, were used for routine microbiology of alimentary canal contents, measurements of intestinal dimensions and in vitro rates of glucose, mirex, methylmercury and retinol absorption by the small intestine. Mice fed the diets with nondigestible oligosaccharides had higher densities of anaerobic bacteria and larger small and large intestines, but did not have greater rates of contaminant absorption or accumulation. Mice exposed to methylmercury accumulated less retinol than mice exposed to mirex. Although diets with nondigestible oligosaccharides fibers reduce accumulation of environmental contaminants, but not retinol, the specific responses vary among tissues, sources of fiber and contaminants. The mechanisms responsible for the influence of nondigestible oligosaccharides can include reduced absorption, increased fecal elimination and transformation to forms that are excreted in the urine.

Animals↗

PubMed2003

Trends in U.S. pleural mesothelioma incidence rates following simian virus 40 contamination of early poliovirus vaccines.

BACKGROUND: Poliovirus vaccines that were used during the late 1950s and early 1960s were contaminated with simian virus 40 (SV40), a monkey virus that is tumorigenic in rodents. SV40 DNA sequences have been detected in some human cancers, especially pleural mesotheliomas, although results are conflicting. We examined the relationship between SV40-contaminated poliovirus vaccine exposure and subsequent rates of pleural mesothelioma in the United States. METHODS: We used data from the Surveillance, Epidemiology, and End Results Program to estimate age- and sex-specific pleural mesothelioma incidence rates per 10(5) person-years (py) from 1975 through 1997 and the Poisson distribution to determine 95% confidence intervals (CIs) for each rate. The prevalence, by birth cohort, of poliovirus vaccine exposure during the period of widespread SV40 contamination was determined from published survey data. Trends in mesothelioma incidence rates were assessed by examining age- and sex-specific rates over calendar periods and with the use of the age-period-cohort model. Trends in mesothelioma incidence were then compared with trends in prevalence of exposure. All statistical tests were two-sided. RESULTS: The age-standardized pleural mesothelioma incidence rate for 1975 through 1997 was 1.29/10(5) py (95% CI = 1.24/10(5) to 1.34/10(5) py) in males and 0.21/10(5) py (95% CI = 0.20/10(5) to 0.23/10(5) py) in females. The rate in males increased from 0.79/10(5) py (95% CI = 0.62/10(5) to 1.0/10(5) py) in 1975 to a peak of 1.69/10(5) py (95% CI = 1.46/10(5) to 1.95/10(5) py) in 1992. Incidence rates increased the most among males who were 75 years of age or older, the age group least likely to have been immunized against poliovirus. Incidence rates among males in the age groups most heavily exposed to SV40-contaminated poliovirus vaccine remained stable or decreased from 1975 through 1997. Similar age-specific trends were observed among females. The age-period-cohort models for men and women also indicated that the trends in pleural mesothelioma incidence were not related to trends in exposure to SV40-contaminated poliovirus vaccine. CONCLUSIONS: Age-specific trends in U.S. pleural mesothelioma incidence rates are not consistent with an effect of exposure to SV40-contaminated poliovirus vaccine. Nonetheless, given reports of the detection of SV40 genomic DNA sequences in human mesotheliomas, monitoring of vaccine-exposed cohorts should continue.

Adolescent↗

PubMed1991

Construction of interleukin-1 alpha mutants using unequal contamination of synthetic oligonucleotides.

Proteins without readily available three-dimensional structural data present a difficult problem in the exploration of structure/function relationships. Saturation mutagenesis using contaminated oligonucleotides can identify potentially interesting regions of such a protein. This technique, in which synthesized oligonucleotides contain low-level base substitutions, allows random mutations to be placed throughout a gene sequence. Using double-stranded cassettes, a region of the human interleukin-1 alpha gene has been altered using such mutagenic oligonucleotides. However, instead of contaminating both strands of the gene sequence at the same level, each strand of the insert was contaminated at a different level. Several recombinants were sequenced and the effects of the mutations on the activity of the proteins were examined. Contaminating the two oligonucleotides at different levels produced a significantly different distribution of nucleotide changes from that seen if both strands were contaminated at the same level. The observed distribution followed the average of the distributions for each of the two contamination levels. This resulted in roughly equal frequencies of 1 to 5 nucleotide changes per clone with very few clones containing the wild-type nucleotide sequence. This helped overcome the redundancy in the genetic code, resulting in a high frequency of amino acid changes, and allowed changes at every amino acid to be sampled in a small number of mutants. This procedure can allow a gene sequence to be screened rapidly by removing most wild-type sequences from analysis while making sure that there are many amino acid changes in the resultant mutants.

Amino Acid Sequence↗

PubMed2003

A novel algorithm for computational identification of contaminated EST libraries.

A key goal of the Human Genome Project was to understand the complete set of human proteins, the proteome. Since the genome sequence by itself is not sufficient for predicting new genes and alternative splicing events that lead to new proteins, expressed sequence tags (ESTs) are used as the primary tool for these purposes. The high prevalence of artifacts in dbEST, however, often leads to invalid predictions. Here we describe a novel method for recognizing genomic DNA contamination and other artifacts that cannot be identified using current EST cleaning techniques. Our method uses the alignment of the entire set of ESTs to the human genome to identify highly contaminated EST libraries. We discovered 53 highly contaminated libraries and a subset of 24 766 ESTs from these libraries that probably represent contamination with genomic DNA, pre-mRNA, and ESTs that span non-canonical introns. Although this is only a small fraction of the entire EST dataset, each contaminating sequence could create a spurious transcript prediction. Indeed, in the clustering and assembly tool that we used, these sequences would have caused incorrect inference of 9575 new splice variants and 6370 new genes. Conclusions based on EST analysis, including prediction of alternative splicing, should be re-evaluated in light of these results. Our method, along with the identified set of contaminated sequences, will be essential for applications that depend on large EST datasets.

Algorithms↗

PubMed2003

The measurement of 60Co contaminated rebar buildings with thermoluminescence dosemeters.

Three contaminated housing units, yielding annual dose levels of 6, 22 and 57 mSv, were selected randomly from identified radiation contaminated buildings (RCBs) to perform this experiment. The results are presented of a study to investigate the probability of finding RCBs by using eight thermoluminescence dosemeters (TLDs) for each suspected radiation contaminated housing unit. The results revealed that, for these three housing units, the probabilities of detecting contaminated housing units using eight TLDs were 93%, 86% and 99%, respectively. The number of TLDs required for such a determination depended strongly on both the radiation contaminated level (i.e., the activity) in the housing unit and the distribution of contaminated columns and beams in the house.

Air Pollution, Indoor↗