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At least 487 records · Page 27Linked to original sources
PubMed2001

Atmospheric sampling of persistent organic pollutants: needs, applications and advances in passive air sampling techniques.

There are numerous potential applications for validated passive sampling techniques to measure persistent organic pollutants (POPs) in the atmosphere, but such techniques are still in their infancy. Potential uses include: monitoring to check for regulatory compliance and identification of potential sources; cheap/efficient reconnaissance surveying of the spatial distribution of POPs; and deployment in studies to investigate environmental processes affecting POP cycling. This article reviews and discusses the principles and needs of passive sampling methodologies. The timescales required for analytical purposes and for the scientific objectives of the study are critical in the choice and design of a passive sampler. Some techniques may operate over the timescales of hours/days, others over weeks/months/years. We distinguish between approaches based on "kinetic uptake" and "equilibrium partitioning". We highlight potentially useful techniques and discuss their potential advantages, disadvantages, and research requirements, drawing attention to the urgent need for detailed studies of sampler performance and calibration.

Air Pollutants↗
PubMed1992

Aeroallergen analyses and their clinical relevance. II. Sampling by high-volume airsampler with immunochemical quantification versus Burkard pollen trap sampling with morphologic quantification.

A comparison was made between the amount of airborne pollen collected by Burkard airsampler and the allergenic activity of particles trapped on glass fibre filters in an Accu-Vol high-volume airsampler. The comparison was made throughout the pollen seasons 1986 to 1989. Both airsamplers were operated 24 h a day. They were placed less than 5 m apart, and estimation of the pollen amount was made on a day-to-day basis during the pollen seasons, and on a weekly basis outside the seasons. The occurrence of the 3 clinically most important allergenic types of pollen, birch, grass, and mugwort, was analysed, and close correlations between the 2 sampling techniques were found (rs 0.5-0.8, p < 0.001). The detected range of counted pollens/m3 was: birch 0-1075, grass 0-156, and mugwort 0-44. By immunochemical analysis we found the corresponding amounts to be 0-80, 0-8, and 0-1 SQ-U/m3, respectively. Pollen counts and immunochemical estimation were compared with the symptom score recordings of allergic persons for birch season 1989 and for grass seasons 1986, 1988, and 1989. A close correlation was found for both sampling techniques for the grass seasons in 1986 and 1989 (rs 0.51-0.61, p < 0.001-0.0001), but a less significant correlation was found for the 1988 grass season, and for birch in 1989 (rs 0.24-0.34, p < 0.001-0.05).

Air Pollutants↗
PubMed1975

The inheritance of scholastric abilities in a sample of twins. I. Ascertainments of the sample and diagnosis of zygosity.

A sample of 149 twin pairs was ascertained by extracting all pairs of candidates with the same surname, birth date and address from the files of a public examination taken by about two thirds of the 15-year-old cohort in South Australia. Of these there were 39 opposite sex pairs and 100 same-sex pairs whose zygosity was determined by postal questionnaire. This diagnosis was checked and found to be accurate by typing 47 pairs for ten independent genetic markers. Several analyses suggest that the ascertained twin samples is fairly representative of the fraction of the cohort who took the examination so there is no evidence to suggest that between families components of variance will be underestimated for this reason.

Adolescent↗
PubMed1998

Comparison of C18-carboxypropylbetaine and glass bead DNA extraction methods for detection of Mycobacterium bovis in bovine milk samples and analysis of samples by PCR.

The purpose of this prospective study was to compare two different milk preparation methods to assay for the presence of Mycobacterium bovis by PCR. Detection by a C18-carboxypropylbetaine (CB-18)-based sample processing method was compared to extraction of DNA from milk with glass beads. Samples from 17 skin test-positive cattle were analyzed. Following CB-18 processing and glass bead extraction, the sensitivity of IS6110-based PCR was 94.1 and 58.8%, respectively (P < 0.025). Because CB-18 processing will permit the proficient use of PCR for diagnosis and surveillance of bovine tuberculosis, it will contribute to the more efficient detection and control of tuberculosis.

Animals↗
PubMed1998

Detection of JC virus in cerebrospinal fluid (CSF) samples from patients with progressive multifocal leukoencephalopathy but not in CSF samples from patients with herpes simplex encephalitis, enteroviral meningitis, or multiple sclerosis.

JC virus (JCV) DNA was detected in cerebrospinal fluid (CSF) samples from patients with progressive multifocal leukoencephalopathy (PML) but not in CSF samples from patients with herpes simplex encephalitis, enteroviral meningitis, or multiple sclerosis. This suggests that inflammatory processes in the brain do not necessarily reactivate JCV, which further supports the proposal that the presence of JCV DNA in the CSF is diagnostic for PML.

Adult↗
PubMed2005

Blind sampling is superior to anoscope guided sampling for screening for anal intraepithelial neoplasia.

OBJECTIVES: Anal cytology smears are either collected "blind" (swab inserted 4 cm into anal canal and rotated) or guided through an anoscope (transformation zone visualised and then sampled). We compared these smear techniques with respect to sample quality and patient acceptability. METHODS: Using a paired, random sequence clinical trial, 151 homosexual men (n = 95 HIV positive) underwent both smear techniques at a single visit; smear order was randomised and specimens were read blind. Both techniques utilised a Dacron swab, with water lubrication. Cytological specimens were prepared using a liquid based collection method (ThinPrep). The outcome measures were cytological specimen adequacy, cytological classification, presence of rectal columnar, squamous and metaplastic cells, contamination, patient comfort and acceptability, and volume of fluid that remained after the ThinPrep procedure. RESULTS: Regardless of smear order, guided smears were less likely to detect higher grade abnormalities than blind smears (15 v 27 cases, p = 0.001). Controlling for smear order, guided smears were more likely to be assessed as "unsatisfactory" for cytological assessment (OR 6.93, 95% CI 1.92 to 24.94), and contain fewer squamous (OR 0.20, 95% CI 0.04 to 0.94) and metaplastic cells (OR 0.12, 95% CI 0.03 to 0.54) than blind smears; there were no other statistically significant differences between techniques. Regardless of smear technique, first performed smears were more likely to detect a higher grade abnormality than second performed smears (23 v eight cases, p < 0.001). CONCLUSIONS: Blind cytology smears are superior to anoscope guided smears for screening for anal neoplasia in homosexual men.

Adult↗
PubMed2004

Free-breathing 3D steady-state free precession coronary MR angiography with radial k-space sampling: comparison with cartesian k-space sampling and cartesian gradient-echo coronary MR angiography--pilot study.

The authors compared radial steady-state free precession (SSFP) coronary magnetic resonance (MR) angiography, cartesian k-space sampling SSFP coronary MR angiography, and gradient-echo coronary MR angiography in 16 healthy adults and four pilot study patients. Standard gradient-echo MR imaging with a T2 preparatory pulse and cartesian k-space sampling was the reference technique. Image quality was compared by using subjective motion artifact level and objective contrast-to-noise ratio and vessel sharpness. Radial SSFP, compared with cartesian SSFP and gradient-echo MR angiography, resulted in reduced motion artifacts and superior vessel sharpness. Cartesian SSFP resulted in increased motion artifacts (P <.05). Contrast-to-noise ratio with radial SSFP was lower than that with cartesian SSFP and similar to that with the reference technique. Radial SSFP coronary MR angiography appears preferable because of improved definition of vessel borders.

Adult↗
PubMed1995

Hydrolytic degradation of benzylated poly(beta-malic acid): influence of sample size, sample shape, and polymer composition.

In order to investigate the effects of sample size, sample shape, and polymer composition on the hydrolytic degradation of water-insoluble benzylated poly(beta-malic acid) derivatives, three polymers were synthesized, namely PMLABe100, PMLABe90H10 and PMLABe80H20, containing 100, 90, and 80% of benzyl units respectively. For each polymer, 4-mm-thick compression molded pellets, 0.3-mm-thick casted films and 250-500 microns ground particles were made and allowed to age in 0.13 M, pH 7.4 sodium phosphate buffer at 37 degrees C. Degradation was monitored by measuring weight changes, variations of polymer composition, formation of benzyl alcohol, and molecular weight decreases. It was shown that degradation of particles and films depended initially on polymer composition due primarily to fast degradation of acid-rich segments present or formed by benzyl ester cleavages which led more or less rapidly to similar compositions for the three polymers. The higher the content in acid groups, the faster the degradation rate and the characteristic changes. It was also found that pellets made of PMLABe90H10 or PMLABe80H20 degraded heterogeneously and much faster than corresponding films and particles.

Benzene Derivatives↗
PubMed2006

A practical measure of impairment: psychometric properties of the impairment rating scale in samples of children with attention deficit hyperactivity disorder and two school-based samples.

Assessing impairment is an explicit component of current psychiatric diagnostic systems. A brief parent and teacher rating scale for assessing impairment was developed and studied using attention deficit hyperactivity disorder (ADHD) as an exemplar disorder. The psychometric properties of the Impairment Rating Scale (IRS) were measured in 4 samples. Two included ADHD and matched comparison children and the other 2 a school sample. Overall, IRS ratings exhibited very good temporal stability. They correlated with other impairment ratings and behavioral measures and displayed evidence of convergent and discriminant validity. The IRS was highly effective in discriminating between children with and without ADHD. Evidence that the parent and teacher IRS accounted for unique variance beyond ratings of ADHD symptoms is also presented. The scale is brief, practical, and in the public domain. The results of the studies and implications for the assessment of impairment are discussed.

Attention Deficit Disorder with Hyperactivity↗
PubMed1979

Matching-to-sample and oddity-from-sample in goldfish.

Acquisition of three-alternative simultaneous matching-to-sample and oddity-from-sample was investigated. Five goldfish were trained on matching and five on oddity for a minimum of 70 days. Subsequently, six of the fish were trained for 70 days on the other task. Acquisition was similar for oddity and matching. Correct responding started at about chance level and slowly increased to about 75%, with some animals performing at levels of over 85%. Acquisition of oddity following matching and matching following oddity began below chance. Maximal level of performance on second-task oddity was comparable to that on first-task matching. By contrast, the maximal levels of performance when matching was the second task were not as high as that of the same subjects at the end of first-task oddity. All fish exhibited strong color preferences during matching acquisition but not during oddity acquisition. The data demonstrated that goldfish can acquire a discrimination in which the stimulus associated with reinforcement depends on the identity of a second stimulus.

Animals↗
PubMed2005

Sample pretreatment and determination of non steroidal anti-inflammatory drugs (NSAIDs) in pharmaceutical formulations and biological samples (blood, plasma, erythrocytes) by HPLC-UV-MS and micro-HPLC.

The article discusses the qualitative and quantitative determination of non-steroidal anti-inflammatory drugs like salicin, salicylic acid, tenoxicam, ketorolac, piroxicam, tolmetin, naproxen, flurbiprofen, diclofenac and ibuprofen by reversed phase high performance liquid chromatography (RP-HPLC) and micro-HPLC (micro-HPLC) hyphenated with UV-absorbance and mass spectrometric detection. Both detection methods delivered calibration plots with good linearity (r(2) > 0.9800), limits of detection in the low nanogram range and recovery rates between 94 and 104 %. For the analysis of biological samples such as blood, plasma and erythrocytes liquid-liquid extraction (LLE) and solid phase extraction (SPE) on the basis of new synthesized glycidylmethacrylate/divinylbenzene copolymer (GMA/DVB) particles and commercially available material on the basis of poly(divinylbenzene-co-N-vinylpyrrolidone) copolymer were investigated. Finally the use of a micro-HPLC system with separation columns in the range of 8 cm x 200 microm I.D. for the determination of non-steroidal anti-inflammatory drugs (NSAIDs) is presented, emphasizing on the type of column and sample amount needed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Exposure to community violence and trauma symptoms in late adolescence: comparison of a college sample and a noncollege community sample.

This paper presents a comparison for two samples (college and noncollege) of older, urban African-American adolescents of correlations between two measures of exposure to community violence (victim and witness) and four types of psychological trauma symptoms (anger, anxiety, depression, and dissociation). The central issue is the generalizability of previous findings about these relationships obtained from beginning college students of traditional age. The two samples did not differ in the magnitude of either the zero-order correlations or the multiple correlations between the two types of exposure to community violence and the four types of symptoms of trauma. The conclusion is that findings regarding the relationship of exposure to community violence with psychological symptoms of trauma obtained from college students may tentatively be generalized to older adolescents who are not in college.

Adolescent↗
PubMed1991

Identification of kappa-casein genotype in Holstein sires: a comparison between analysis of milk samples from daughters and direct analysis of semen samples from sires by polymerase chain reaction.

Two different methods were used to determine kappa-casein genotypes of Holstein sires. In the earlier procedure, genotypes of sires were deduced by analyzing frequency distribution data of kappa-casein variants obtained through typing of milk samples from daughters by electrophoresis. The second method involved direct analysis of DNA obtained from semen samples of the sires. The polymerase chain reaction was used to amplify a 99-bp region from the kappa-casein gene that contains nucleotide substitutions that are diagnostic of variants A and B. Identity of the amplified product was confirmed by sequencing. Results obtained by both methods of genotyping were similar. For the 42 sires that were analyzed by both methods, the distribution of kappa-casein genotypes were 31 AA, 11 AB, and 0 BB. The frequency of B allele for kappa-casein in the sire population studied was lower than in larger Holstein cow populations. Due to the high demand for kappa-casein B milk by the dairy industry, it might be advantageous to increase this allele in the dairy cattle population by identifying sires with homozygous kappa-casein B and using them more frequently as service sires.

Alleles↗
PubMed2004

Are three-sample tasks less sensitive than two-sample tasks? Memory effects in the testing of taste discrimination.

In order to provide insights into why discrimination protocols with three stimuli sometimes tend to be less sensitive than protocols with two stimuli, two experiments were conducted. In these experiments, the relative effects of memory decay and memory interference were investigated. Both experiments involved purified water and/or solutions of low NaCl concentration. In Experiment 1, three protocols were compared: the traditional same-different test (Protocol 1), the same protocol with a rinse between the two samples (Protocol 2), and Protocol 2 with an added time delay between the first sample and the intermediate rinse (Protocol 3.) The decrease in measured d' values as time delay increased indicated that memory decay might be a factor for tests with three stimuli, such as the triangle method, rendering it less sensitive than tests with two stimuli, such as the same-different method. In Experiment 2, four protocols were compared: the traditional same-different test, the two-rinse same-different test, the triangle test, and what will be called duo same-different test. The experimental design allowed the individual consideration of memory decay and interference effects. From this last experiment, the substantial effect of memory interference was uncovered. Further experimentation will be necessary to estimate the exact relative effects of memory interference and memory decay.

Adult↗
PubMed2006

Objective detection of auditory steady-state responses: comparison of one-sample and q-sample tests.

Auditory steady-state responses (ASSR) are expected to be useful for the objective, frequency-specific assessment of hearing thresholds in small children. To detect ASSR close to the hearing threshold, a powerful statistical test has to be applied. At present, so-called one-sample tests are used. These tests only evaluate the phase, or the phase and amplitude, of the first harmonic, that is, the fundamental frequency. It is shown that higher harmonics with significant amplitudes are also contained in the ASSR spectrum. For this reason, statistical tests that only consider the first harmonic ignore a significant portion of the available information. The use of a q-sample test, which, in addition to the fundamental frequency, also includes higher harmonics in the detection leads to a better detection performance. The evaluation of test performance uses both detection rate and detection time.

Acoustic Stimulation↗
PubMed2003

Status of Soil Transmitted Helminth infections in an urban locality of Assam; as observed from survey by WHO sampling methodology for school children and community survey by random sampling.

In this study, an attempt was made to compare and correlate findings of a Soil Transmitted Helminths (STH) survey carried out using WHO sampling methodology for school children and community survey by random sampling. The prevalence and intensity of STH in the age-group of 9-10 yrs reportedly represent community status. The results showed that the STH prevalence and intensity in the age-group of 9-10 years do represent community burden. However, more such surveys will have to be carried out to substantiate this statement.

Adolescent↗
PubMed2005

[How to measure the structures, or new stereology. I. Sampling and orientation of samples].

This article presents a brief review of newly developed methods of modern stereology for measurement of biostructures, which allow to avoid problems of uncertainty and technical difficulties peculiar to old stereology. In the first part of the review, a brief historical report on the development of new stereological approaches and their practical application to the selection and orientation of samples, is given. In particular, Cavalieri's principle, random systematic isotropic sampling, fractionator, isector, orientator and principle of vertical sections are described. Some details for practical aspects of measurements have been provided.

Histocytological Preparation Techniques↗