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PubMed2002

Silver concentrations in Colorado, USA, watersheds using improved methodology.

River water samples were collected at five sites in the state of Colorado, USA, to assess the impact of municipal and industrial discharges on Ag concentrations and speciation in surface waters. Samples were collected and analyzed for total (unfiltered collections), filtered (0.1 and 0.4 microm), particulate (> or = 0.45 microm), and colloidal Ag (3 kDa-0.1 m) using ultraclean protocols. A series of laboratory experiments were conducted to assess bias from sample storage, digestion, and preconcentration protocols. In general, upstream unfiltered and particulate Ag concentrations fell within a fairly narrow range, 3.1 to 21 ng/L and 0.2 to 1.7 microg/g, respectively. Downstream unfiltered and particulate Ag concentrations showed a more broad range, 2.8 to 1,110 ng/L and 0.5 to 104 microg/g, respectively, and reflected attenuated impacts of Ag-laden discharge effluents. However, Ag concentrations in the 0.1-microm filter-passing fraction 0.8 to 1.2 km downstream from major treatment plant effluents were all below the chronic silver criteria. On average, more than 60% of the 0.1-microm filter-passing Ag was associated with colloidal macromolecular organic matter. Silver concentrations in colloids (microg/g) were, on average, the same as those in suspended particulate matter. The percentage abundance of colloidal Ag was similar to that of dissolved organic carbon, suggesting that strong Ag binding ligands exist in both the colloidal and the particle size fractions, as these macromolecular ligands likely play a major role in Ag speciation.

Chemical Industry↗
PubMedDate not supplied

Prevalence of allergy to latex in the pediatric population.

Latex is a substance that is extracted from the plant Hevea Brasiliensis, and world production is 6 million metric tons per year. After gathering it undergoes a series of processes in which ammonia, vulcanization-accelerating additives or anti-oxidants are added. All of this may constitute the antigenic load that latex contains. It is used in medicine for gloves, drainage tubes, dental implants and a growing number of products from condoms to sport products or automobile components. Over fifteen different allergenic bands have been described, with molecular weights of between 2 and 100 kDa. In a joint study, USA-Finland identified three antigenic bands that predominate according to the population type studied (2). In children with spina bifida, congenital urogenital abnormalities or those submitted to multiple surgical interventions, the band of 27 kDa is predominant. This antigen has not been detected in adult serum, which suggests that contact with the antigen is through the mucous membranes and the sensitization is triggered from here. The incidence of allergy to latex in the general population is not known, but it seems to be lower than 1%. Turjanmaa (1) establishes a frequency of 0.125% (1/800) in patients submitted to general surgery. The incidence of sensitization to latex varies according to the population studied. Among the population considered to be at risk are the workers of the health environment, where the incidence is between 2.6 and 16.9%, whereas in the general population the percentage is around 1%. Sensitivity to latex is of great importance in patients suffering from spina bifida, in whom an incidence of between 28 and 67% has been found. We present our experience in a group of children attending our service for the first time for diverse reasons of supposed allergic etiology. The objective is to determine the incidence of sensitization to latex according to the diagnostic methodology [cutaneous test or by determination of specific IgE (CAP)]; according to the type of patient (atopic or non-atopic), the direct relationship with latex material and the role that can be played by a history of surgical intervention. In our experience with 282 children studied in our pediatric allergology service using diverse methods, the incidence of allergy to latex is 3.19%. Nevertheless, if we analyze this percentage we observe that if the diagnosis is based exclusively on cutaneous tests, it is only 1.08%; if to establish a diagnosis we used exclusively the determination of specific IgE (CAP) we would label 7. 2% of our children as allergic. Atopy is a factor that facilitates sensitization. In our sample, the incidence among the atopic population is 4.4%, though this percentage may vary between 1.69% and 9.5% depending on the methodology used. There are several hypotheses for explaining these discrepancies in the diagnostic tests. Although there do not seem to be differences regarding the ammonia content of the different lots, it seems that the differential factor could lie in the type of extract and in whether it is commercial or a natural latex extract. It could be a consequence of the existence of a prophyllin, so it has not been ruled out that a part of the IgE is an antiprophyllin. The presence of different epitopes would mean that each of them has the ability to produce its own specific IgE, though the RAST/CAP was not able to differentiate them and identified them as whole. The rate of allergy to latex in a group of children suffering from myelomeningocele is 80%. At a paediatric level, sensitization to latex is influenced by the means of contact, the duration of the exposure to the antigen and the fact that the exposure occurs early, which in the case of children with myelomeningocele is associated with the immaturity of the defence mechanism of the mucous membranes.

Child↗
PubMed2006

Aetiological diagnosis of infective endocarditis by direct amplification of rRNA genes from surgically removed valve tissue. An 11-year experience in a Finnish teaching hospital.

BACKGROUND/AIMS: The aetiology of infective endocarditis (IE) can be determined directly from surgically removed valve tissue using broad-range bacterial rDNA polymerase chain reaction (PCR) followed by sequencing. We sought to assess the value of this methodology in a routine clinical setting. METHODS: Broad-range PCR with primers targeting conserved bacterial rDNA sequences was applied to directly analyse valve samples from 56 patients operated on for diagnosed or suspected IE. Identification of the aetiological agent was performed by partial DNA sequencing of the 16S and 23S rDNA genes. RESULTS: The final diagnosis was definite IE in 36 patients and possible IE in 2 patients, while the diagnosis of IE was rejected in 18 patients. PCR analysis from removed valve tissue was positive in 25 patients with IE. Molecular identification was consistent with the blood culture finding in 20 of these patients. The PCR approach was the only method to yield the aetiological diagnosis in additional 4 patients (2 Staphylococcus species, 1 Streptococcus bovis, 1 Bartonella quintana), all of whom had received antimicrobials before blood cultures were taken. The mean duration of preoperative antimicrobial treatment for the patients with PCR-positive valves was 19.6 (range 1-58) days. CONCLUSIONS: Bacterial DNA may persist during treatment in infected valves for long periods. The PCR method is especially useful when the causative agent of IE is fastidious or when the specimen is taken during antimicrobial treatment.

Bacterial Typing Techniques↗
PubMed1991

Mutagenicity study of urine from smoking and non-smoking road tanker drivers.

Urine from 32 road tanker drivers handling petrol, diesel, paraffin and white spirit was tested in the Salmonella/microsome mutagenicity system using tester strains TA98 anbd TA100. Urine samples were collected before and after tanking and were concentrated 250-fold on XAD-2 columns before testing. Controls were 33 office employees from the same plant. No effect on urinary mutagenicity of occupational exposure to petroleum products was found. Significant differences in mutagenic effect were demonstrated between smokers and non-smokers. Methodological experiments demonstrated a dose/response effect of smoking on urinary mutagenicity. A modified test using a preincubation period and an increased concentration of bacteria was more sensitive than the standard Ames test to mutagens from tobacco smoking.

Dose-Response Relationship, Drug↗
PubMed2000

A preliminary clinical investigation into the potential of blood lead levels to measure bone resorption in patients with skeletal metastases, using ICP-MS.

A simple, accurate and precise method to measure lead levels in whole blood by inductively coupled plasma-mass spectrometry (ICP-MS) has been developed. Blood samples were diluted (1 + 9) with 0.1% v/v Triton X-100 and 0.1% v/v nitric acid, and gave a limit of detection of 0.06 microgram/l (3sn). Spiking experiments demonstrated recoveries of 100 +/- 10% and verification against Seronorm reference and BCR certified reference materials gave experimental values in close agreement to the reference values. The methodology was used to conduct a feasibility study, involving a preliminary clinical investigation to assess the potential of whole blood lead levels as biochemical markers to measure bone resorption in patients with skeletal metastases and receiving treatment. The results from this feasibility study showed that the method remained under analytical control, giving inter and intra assay coefficients of variation of < 5%. This feasibility study also showed that the changes in the blood lead levels within individual patients were measurable and in many cases the patient's observed clinical performance demonstrated similar trends to the blood lead levels measured over time. Overall the results were encouraging and showed promise. Further and more detailed investigations into the use of lead and other trace metals as biomarkers of bone resorption is warranted.

Aged↗
PubMed1975

Measurement of bacterial and fungal contributions to respiration of selected agricultural and forest soils.

A technique using selective inhibitors was used to estimate the relative contributions of bacterial and fungal populations to the respiration of six soils and one litter sample. The ratios of bacterial to fungal respiration in the four agricultural soils, given in percentage of the total microbial activity, ranged from 10/90 to 35/65, with the average ratio being about 30/70. In the forest soils, the ratios were 20/80 and 30/70, and in a beech litter sample, the ratio was 40/60. The fungi clearly dominated in all samples. The ratios were not found to be pH related. The difficulties which had previously limited the use of selective inhibitors for in situ soil ecological investigations, such as insufficient inhibitor specificity, inhibitor inactivation or degradation, and errors of measurement caused by elimination of competitor populations, were either resolved or methodologically avoided in the experiments. Inhibitor selectivity was demonstrated using both mixed and pure cultures of microorganisms from each soil. Through the use of experiments with short incubation periods (6-8 h), problems with population shifts and inhibitor degradation were eliminated.

Actinomycetales↗
PubMedDate not supplied

Home intravenous therapy down under.

Health service research traditionally has relied on quantitative methodologies that view the question from the researcher's perspective. Exploring the question of what it is like to receive intravenous therapy at home has required investigation into what is known about home i.v. therapy and the impact on the patient in particular. The purpose of this study was to describe and understand the recipient's lived experience of home i.v. therapy using a research approach that preserves the uniqueness of the experience from the recipient's perspective. The method involved conducting in-depth interviews with a sample of 26 recipients of home i.v. therapy throughout Tasmania, Australia. Interviews were analyzed using an interpretative process, with the participants describing a process that included the main themes of "having a life" and "the hazards of hospitalization." The main goals of the work are to heighten nurses' and other healthcare professionals' understanding and awareness of home i.v. therapy from the consumer perspective and to address the lack of patient/consumer advocacy and exploration within the evaluative literature available on this subject.

Community Health Nursing↗
PubMed2005

Dietary restraint and US devaluation predict evaluative learning.

Previous research has indicated that flavor-flavor learning is impaired in restrained eaters. In Experiment 1 we sought to extend this finding using a larger sample and a more comprehensive assessment of dietary behavior. Participants (N=90, including 30 current dieters) sampled three novel flavors (CSs), each on 10 separate occasions, in a randomized order. Each flavor was paired with chocolate (US) either 10%, 50%, or 90% of the time. We then assessed liking for the three CSs and asked participants to complete the DEBQ-restraint and TFEQ-disinhibition sub-scales. After these CS-US parings, restrained eaters tended to prefer the 10% paired flavor whereas unrestrained eaters tended to prefer the 90% paired flavor. Differential CS liking was not evident in dieters and it was not predicted by disinhibition. Using a similar methodology, in Experiment 2 (N=76) we assessed evaluative change following picture-sweet pairings. Relative to the other CSs, the restrained eaters reported a greater increase in their liking for the 10% paired CS and the unrestrained eaters reported a greater increase in their liking for the 90% paired CS. We also discovered that evaluative change is related to the level of US devaluation that takes place during conditioning. Evidence that a sweet US can bring about a decrease in liking has not been reported previously. One interpretation is that negative beliefs and attitudes can contaminate the representation of the US during training.

Adult↗
PubMed2006

Turnover of stable carbon isotopes in the muscle, liver, and breath CO2 of alpacas (Lama pacos).

Stable carbon isotope analysis of animal liver and muscle has become a widespread tool for investigating dietary ecology. Nonetheless, stable carbon isotope turnover of these tissues has not been studied in large mammals except with isotopically labelled tracer methodologies, which do not produce carbon half-lives analogous to those derived from naturalistic diet-switch experiments. To address this gap, we studied turnover of carbon isotopes in the liver, muscle, and breath CO2 of alpacas (Lama pacos) by switching them from a C3 grass diet to an isonitrogenous C4 grass diet. Breath samples as well as liver and muscle biopsies were collected and analyzed for up to 72 days to monitor the incorporation of the C4-derived carbon. The data suggest half-lives of 2.8, 37.3, and 178.7 days for alpaca breath CO2, liver, and muscle, respectively. Alpaca liver and muscle carbon half-lives are about 6 times longer than those of gerbils, which is about what would be expected given their size. In contrast, breath CO2 turnover does not scale readily with body mass. We also note that the breath CO2 and liver data are better described using a multiple-pool exponential decay model than a single-pool model.

Aging↗
PubMed2006

Interpretive biases in chronic insomnia: an investigation using a priming paradigm.

Disorder-congruent interpretations of ambiguous stimuli characterize several psychological disorders and have been implicated in their maintenance. Models of insomnia have highlighted the importance of cognitive processes, but the possibility that biased interpretations are important has been minimally investigated. Hence, a priming methodology was employed to investigate the presence of an interpretive bias in insomnia. A sample of 78 participants, differing in the presence of a diagnosis of insomnia, severity of sleep disturbance, and sleepiness, was required to read ambiguous sentences and make a lexical decision about target words that followed. Sleepiness at the time of the experiment was associated with the likelihood with which participants made insomnia and threat consistent interpretations of ambiguous sentences. The results suggest that there is a general bias towards threatening interpretations when individuals are sleepy and suggests that cognitive accounts of insomnia require revision to include a role for interpretative bias when people are sleepy. Future research is required to investigate whether this interpretive bias plays a causal role in the maintenance of insomnia.

Adolescent↗
PubMed2002

Comparison of various extraction techniques for the determination of polycyclic aromatic hydrocarbons in worms.

Two less laborious extraction methods, viz. (i) a simplified liquid extraction using light petroleum or (ii) microwave-assisted solvent extraction (MASE), for the analysis of polycyclic aromatic hydrocarbons (PAHs) in samples of the compost worm Eisenia andrei, were compared with a reference method. After extraction and concentration, analytical methodology consisted of a cleanup of (part) of the extract with high-performance gel permeation chromatography (HPGPC) and instrumental analysis of 15 PAHs with reversed-phase liquid chromatography with fluorescence detection (RPLC-FLD). Comparison of the methods was done by analysing samples with incurred residues (n=15, each method) originating from an experiment in which worms were exposed to a soil contaminated with PAHs. Simultaneously, the performance of the total lipid determination of each method was established. Evaluation of the data by means of principal component analysis (PCA) and analysis of variance (ANOVA) revealed that the performance of the light petroleum method for both the extraction of PAHs (concentration range 1-30 ng/g) and lipid content corresponds very well with the reference method. Compared to the reference method, the MASE method yielded somewhat lower concentrations for the less volatile PAHs, e.g., dibenzo[ah]anthracene and benzo[ghi]perylene and provided a significant higher amount of co-extracted material.

Animals↗
PubMed2004

Threat appraisal and avoidance after traumatic brain injury: why and how often are activities avoided?

OBJECTIVE: Goldstein emphasized the anxiety-related avoidance of activities after brain injury, but such avoidance has rarely been systematically investigated. This study aimed to compile a list of specific threat appraisals that may lead to avoidance and to obtain data on the frequency with which these appraisals and consequent avoidance occur. DESIGN: Survey. METHOD: Qualitative methodology was used to obtain an account of threat appraisals. These data were then used to compile two questionnaires that asked about the experience of these appraisals and consequent avoidance. Fifty individuals with a TBI completed the questionnaires. RESULTS: A varied list of threat appraisals was obtained. Appraisals and consequent avoidance were frequent in the sample. Males and those whose TBI resulted from an assault reported more avoidance. CONCLUSIONS: A core aim of rehabilitation is to facilitate participation in valued roles and activities. Threat appraisals and avoidance deserve more attention in research and practice because they may constitute a significant obstacle to achieving this.

Accidental Falls↗
PubMed2001

Adolescents' perceptions of a health survey using multimedia computer-assisted self-administered interview.

OBJECTIVE: To ascertain young people's perceptions of an adolescent health survey when administered by multimedia computer assisted self-administered Interview (M-CASI) through analysis of (1) questionnaire item responses and (2) focus group interviews. METHODOLOGY SETTING: Auckland, New Zealand, 1999. STUDY TYPE: Pilot testing of a 488-item branching questionnaire delivered using a youth-oriented and user-friendly M-CASI interface in a variety of settings using both desktop and laptop computers. Post pilot focus groups of participants identifying their perceptions and experiences of the survey. SAMPLE: 110 school students aged 12 to 18 years. RESULTS: The mean number of questions answered by participants was 316 with the median time to completion being 48 minutes. On average 65% of the total number of questions were seen and of these 1.5% were deliberately not answered. A high level of acceptability and enjoyment of M-CASI was found in the analysis of focus group responses and agreed with the item responses relating to M-CASI within the questionnaire itself. Participants identified privacy and confidentiality as being particularly important for the honesty of their responses. The passive matrix screens of the computers were popular as they could only be viewed from in front. CONCLUSIONS: M-CASI is an acceptable instrument for the administration of a youth health survey. Laptop computers with passive matrix screens are able to enhance perceptions of privacy and confidentiality, which may improve honesty of responses. IMPLICATIONS: M-CASI is now feasible and offers advantages in health surveying.

Adolescent↗
PubMed1982

Further observations on the effects of dietary fatty acid composition on platelet reactivity and blood coagulation in man and the influence of methodology on findings.

Eight human subjects were fed diets enriched in saturated fat (SF), or polyunsaturated fat (PUF) and after each dietary regimen the plasma heparinthrombin clotting time (HTCT) was determined. The HTCT of citrated plasma indicated reduced heparin-neutralizing activity (HNA) after PUF feeding compared with SF feeding. Platelet factor 4 (PF4) levels in the citrated plasma samples demonstrated an inverse correlation with the HTCT (r = 0.62). Experiments with purified PF4 indicated that the PF4 present in citrated plasma could only account for approximately 10% of the HNA. Plasma prepared in a manner which minimized in vitro release of platelet constituents contained significantly less PF4 after PUF feeding and indicated that most of the PF4 found in citrated plasma resulted from in vitro release. The factor Xa inhibitory activity of citrated plasma was not significantly altered by either of the dietary regimens.

Adult↗
PubMed2006

Identification of compounds associated with testosterone depressions in fish exposed to bleached kraft pulp and paper mill chemical recovery condensates.

In previous experiments, bleached kraft chemical recovery condensates generated during softwood pulp production have been identified as a primary source of substances causing testosterone depressions in mummichog (Fundulus heteroclitus). Recent toxicity identification evaluations have encountered inconsistencies in the potential of condensates and fractions to reduce steroid concentrations between three repeated exposures. To assess the sources of these inconsistencies, temporal assessments of condensate extractives and analytical methodologies were evaluated. Condensates were collected during a six-month period, extracted by solid-phase extraction (SPE), and analyzed by gas chromatography-mass spectrometry and gas chromatography-flame photometric detection. All unique extractives were cataloged by mass spectra, peak area, and gas chromatographic retention time, and nine were confirmed and quantified against authentic standards. Confirmed components included phenolic guaiacyl-based lignin degradation products, sulfur (S9), three diterpenoids, and a dimethoxy stilbene. Concentrations of confirmed condensate extractives were consistent in all samples collected. Spiking experiments of confirmed extractives revealed substantial losses following high-pressure liquid chromatographic fractionation and three different methods of fraction preparation. In an effort to propose chemical classes associated with biological activity, all unique condensate extractives in previously established bioactive and inactive fractions were classified based on their potential to depress testosterone in mummichog. Of 39 unique components in bioactive SPE extracts of condensates, six were associated with hormonal activity. Mass spectral interpretation indicated hydroxylated diterpenoids, sesquiterpenoids, and a lignin-derived stilbene as classes of chemicals associated with steroid depressions.

Animals↗
PubMed2004

Medical researchers evaluate their methodological skills.

BACKGROUND AND OBJECTIVE: Clinical epidemiology and statistics skills of clinical researchers are often limited. We assessed methodological skills of medical researchers and identified factors associated with higher skill levels. METHODS: In a cross-sectional mail survey at two Swiss teaching hospitals, participants (N=409) rated their ability to perform 26 research-related activities, such as identifying the research question, selecting a study design, computing the required sample size, performing data analysis, and reporting results. RESULTS: The proportion of respondents who were able to perform a specific activity was 33.2% on average, ranging from 1.5% for "numerical statistics (bootstrap, simulation, cross-validation,...)" to 76.0% for "oral presentation of results." The overall skill level (expressed as a percentage of the 26 activities) was associated with principal investigator experience (+8.7%), greater percentage of time devoted to research (+12.4% for near full-time versus no time commitment), years of research experience (+17.6% for 15-40 years versus 0 years), past number of clinical research projects (+18.0% for 15-230 projects versus 0-1 projects), and hours of formal methodological training (+32.6% for 200-1200 hours versus 0-9 hours). CONCLUSION: Self-reported methodological skills were generally modest. The most important covariates of skill levels were current time commitment to research, past experience, and formal training.

Adult↗
PubMed1996

A method for titration of inhibiting antibodies to bacterial immunoglobulin A1 proteases in human serum and secretions.

Bacterial IgA1 proteases specifically cleave IgA1, including S-IgA1, molecules into Fab alpha and Fc alpha fragments. Hereby these enzymes interfere with the protective functions of antibodies belonging to this isotype. Antibodies inhibiting IgA1 proteases have been detected in humans, but the titration of such antibodies is a matter of methodological concern. Because human serum and secretions contain IgA1 substrate, it is impossible to provide uniform substrate conditions for samples of IgA1 protease incubated with inhibitors differing in their origin and state of dilution. This study demonstrates that such variations in substrate are not prohibitive for a reliable titration of inhibiting antibodies. This was evident from experiments demonstrating that the variations do not interfere with the quantification of residual IgA1 protease activity provided the activity is measured in terms of the proportion of IgA1 substrate cleaved during incubation. Proportions of cleaved IgA1 were measured by exploiting the differential reactivity of cleaved and intact IgA1 molecules in an ELISA using anti-Fc alpha and enzyme-conjugated anti-light chain antibodies for catching and development, respectively. A protocol for the titration of IgA1 protease-inhibiting antibodies based on this ELISA is described. By application of the protocol to chromatographic fractions of saliva, IgA1 protease-inhibiting activity was found to co-purify with salivary S-IgA.

Adult↗
PubMed1991

An improved dot-blot method for virus detection in chicken embryo fibroblast cultures.

A simplified dot-blot procedure is described for the detection of fowlpox virus (FPV) in infected monolayers of chicken embryo fibroblasts (CEF) cultured in 96-well microtiter plates. The relative resistance of DNA to hot NaOH, which hydrolyzes other macromolecules including RNA and protein, was exploited to solubilize virus infected cells and denature intracellular DNA in a simple, quick manner. Moreover, there was no need to purify virus or isolate viral DNA from cellular DNA prior to dot blotting. After incubation of CEF with FPV, the extracellular fluid from infected cells was collected for storage in 96-well microtiter plates. The remaining cell monolayers in each well were then solubilized with hot NaOH. The solubilized and denatured DNA was transferred to a nylon membrane using a dot-blot vacuum filtration manifold. Hybridization was carried out with a 32P-labeled FPV DNA probe. With this methodology it was possible to detect specific viral DNA sequences following the infection of cell monolayers with as little as 1 infectious unit per well. The ability to detect specific viral DNA sequences in infected cells, without the need to isolate pure viral DNA, made it possible to analyze large numbers of samples in a single experiment. Moreover, sufficient fowlpox virus was present in the extracellular media from each well for further amplification and analysis of selected samples.

Animals↗