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At least 343 records · Page 19Linked to original sources
PubMed2003

Incidence of Listeria monocytogenes in food and environmental samples in Italy between 1990 and 1999: serotype distribution in food, environmental and clinical samples.

We report the findings of the study of 4185 food samples and 958 environmental samples collected in Italy in the period 1990-1999 and tested for the presence of Listeria monocytogenes. The strains isolated were biochemically and serologically characterised. We found a fairly high percentage of L. monocytogenes contamination in food (12.8%), whereas the level of contamination was lower in the environment (environment and work surfaces in food processing plants) (6.1%). Serotyping showed a prevalence of a few serotypes (i.e., 1/2a, 1/2b, 1/2c and 4b), which were the same as those found in clinical samples collected during outbreaks and from sporadic cases of listeriosis reported in Italy in the period considered. The geographical distribution of the strains of L. monocytogenes isolated from food samples is very similar to that of the clinical strains.

Disease Outbreaks↗
PubMed2004

Evidence for detection of one duration sample and default responding to other duration samples by pigeons may result from an artifact of retention-test ambiguity.

S. C. Gaitan and J. T. Wixted (2000) proposed that when pigeons are trained on a conditional discrimination to associate 1 duration sample with 1 comparison and 2 other duration samples with a 2nd comparison, they detect only the single duration, and on trials involving either of the 2 other duration samples, they respond to the other comparison by default. In 2 experiments, the authors show instead that pigeons lend to treat the retention intervals (such as those used by Gaitan and Wixted) as intertrial intervals, and thus, they tend to treat all trials with a delay as 0-s sample trials. The authors tested this hypothesis by showing that divergent retention functions do not appear when the retention interval is discriminably different from the intertrial interval.

Animals↗
PubMed2001

Determination of PAH in food samples by HPLC with fluorimetric detection following sonication extraction without sample clean-up.

A rapid method is proposed for the determination of 16 polycyclic aromatic hydrocarbons (PAH) in non-fatty food (mashed potato, potato and toasted bread samples) based on their extraction with ethyl ether-methylene chloride (1:1) by sonication, and subsequent separation by high-performance liquid chromatography (HPLC) with fluorimetric detection. A Hypersil Green PAH column was used with a gradient of acetonitrile-water as the mobile phase, together with a programme of ten excitation and emission wavelength pairs. At levels 1.60-2320 microg kg(-1), mean recoveries of PAH were in the range 70-86% for mashed potato, potato and toasted bread samples. The relative standard deviations were in the range 4.2-11% (n = 6). Total PAH found in mashed potato were in the range 9.35-17.1 microg kg(-1), in potato samples 8.47-17.2 microg kg(-1) and in toasted bread samples 7.38-18.0 microg kg(-1), with relative standard deviations in the range 0.8-12%. Only chrysene, determined in Ortiz toasted bread (7.38 microg kg(-1)), has carcinogenic properties.

Bread↗
PubMed2002

Effect of sample flow rate and sampling duration on the absorption of NO2 in the sodium arsenite monitoring method.

The effect of the two most critical parameters, the sample flow rate and sampling duration, on the absorption efficiency of NO2 in the sodium arsenite method of nitrogen dioxide determination in ambient air was studied. Laboratory experiments showed a high sensitivity to these parameters, which were subjected to variation during actual field monitoring. The reported NO2 absorption efficiency of the method of 82% at a flow rate of 0.2 l min-1 was found to be as low as 33% at a flow rate of 1.0 l min-1 for a sampling duration of 24 h. Similarly, a considerable decrease in absorption efficiency with increasing sampling duration from 2 to 24 h was observed at a particular flow rate. Correction factors for the absorption efficiency were evolved that can be used to update the existing database, as well as future NO2 data generated using this manual monitoring method.

Absorption↗
PubMed1996

Sample size effects on temporal reliability of language sample measures of preschool children.

The present study examined the temporal reliability of four quantitative measurements of operationally defined linguistic behaviors observed in a naturalistic setting. The measures of language production were computed using the Systematic Analysis of Language Transcripts (SALT) software from two 20-minute language samples obtained 3 to 14 days apart for each of 20 preschool-aged children. Samples were edited to different sizes based either on duration (12 or 20 minutes) or on limits of the total number of complete and intelligible utterances (from 25 to 175 in increments of 25). Inadequate reliability was found for the language sample measure, total number of words; hence, the validity of this measure is questionable. In contrast, very high temporal reliability coefficients (r > .92) were obtained for the language sample measures of number of different words, mean length of utterance in morphemes, and mean sentence length in morphemes when derived from a large number (> or = 175) of complete and intelligible utterances. The temporal reliability of these measures reached acceptable levels, not only for research purposes, but for diagnostic purposes as well.

Child, Preschool↗
PubMedDate not supplied

[The use of ribonucleic acids as markers for the measuring of microbial protein yield in the rumen. 2. The effect of sample treatment, the time of sampling and the composition of the ration on the RNA:N ratio in rumen microbes].

In two experiments the influence of the treatment of samples, the sampling time and the composition of the rations on the RNA: N ratio in the rumen microbes was checked. Experiment I proved that freezing (-21 degrees C), thawing and freeze-drying of isolated bacteria and protozoa from the rumen fluid and from the duodenal content did not result in a change of the RNA content and the RNA-N: total N relation. If, however, the rumen fluid is stored deep-frozen before the isolation of the bacteria the N content in the DM of the bacteria decreases by 17% and that of RNA by 30%. This results in a change of the RNA: N relation of 16%. In conclusion, the bacteria are to be isolated immediately after rumen fluid sampling. Isolated bacteria can be stored deep-frozen before RNA determination and then freeze-dried. Experiment II showed that the RNA content of the rumen protozoa varies according to the period after feeding. The RNA: N relation was 0.50, 0.92, 0.70 and 0.58 on average 0, 3, 6 and 8 h after feeding, in which the 3rd hour after feeding can obviously be considered the time of increased microbial activity. The conclusion from this variation is that more than one isolation of microbes must be carried out in the course of the day in order to achieve representative samples. These statements apply to easily and not easily fermentable protein as N source in the feed. It could also be proved that no essential variation is to be expected in the RNA: N relation in the microbes isolated from the rumen fluid in the range of 8-21% crude protein in the DM of the ration (roughage: concentrate = 55: 45). On average the rumen microbes contained 1.7 g RNA-N/16 g N, essential differences between bacteria and protozoa could not be ascertained. From the slight variation of the RNA-N: N relation in the isolated bacteria from various cows one can conclude that there is no need to isolate the microbes of each individual animal.

Animal Feed↗
PubMed2000

Home sampling versus conventional swab sampling for screening of Chlamydia trachomatis in women: a cluster-randomized 1-year follow-up study.

We compared the efficacy of a screening program for urogenital Chlamydia trachomatis infections based on home sampling with that of a screening program based on conventional swab sampling performed at a physician's office. Female subjects, comprising students at 17 high schools in the county of Aarhus, Denmark, were divided into a study group (tested by home sampling) and a control group (tested in a physician's office). We assessed the number of new infections and the number of subjects who reported being treated for pelvic inflammatory disease (PID) at 1 year of follow-up; 443 (51.1%) of 867 women in the intervention group and 487 (58.5%) of 833 women in the control group were available for follow-up. Thirteen (2.9%) and 32 (6.6%) new infections were identified in the intervention group and the control group, respectively (Wilcoxon exact value, P=.026). Nine (2.1%) women in the intervention group and 20 (4.2%) in the control group reported being treated for PID (P=.045), indicating that a screening strategy involving home sampling is associated with a lower prevalence of C. trachomatis and a lower proportion of reported cases of PID.

Adolescent↗
PubMed2001

Referent sampling, family history and relative risk: the role of length-biased sampling.

Familial risk of disease is often assessed using case control studies based on referent databases. A referent database is a collection of family histories of cases typically assembled as a result of one family member being diagnosed with disease. This sampling scheme is equivalent to sampling families proportional to their size. The larger the family, the greater the probability of finding the family in the referent registry. This phenomena is known as length-biased sampling. The consequence of this kind of sampling is to bias the regression estimate associated with family history. The estimate is typically inflated in comparison to what is true for the actual population.

Journal Article↗
PubMed1996

Applying the sisterhood method for estimating maternal mortality to a health facility-based sample: a comparison with results from a household-based sample.

BACKGROUND: The sisterhood method is an indirect technique used to estimate maternal mortality in developing countries, where maternal deaths are often poorly registered in official statistics. It has been used successfully in many community-based household surveys. Because such surveys can be costly, this study investigated the suitability of using data collected in outpatient health facilities. METHODS: Adults visiting any one of 91 health centres or posts in a rural region of Nicaragua were randomly sampled and interviewed by health personnel. A sample size, proportional to the population served, was assigned to each facility and 9232 adults were interviewed. Characteristics of health facility users were compared with the general population to identify factors that would allow generalization of results to other settings. RESULTS: Based on these data, the lifetime risk of maternal death was 0.0144 (1 in 69). This estimate is essentially identical to that from a household-based survey in the same region 8 months earlier, which obtained a lifetime risk of 0.0145 (1 in 69). These findings correspond to a maternal mortality ratio of 241 and 243/100000 livebirths, respectively. CONCLUSIONS: This is the first report comparing results of the sisterhood method from household and health facility-based samples. The sisterhood method provided a robust estimate of the magnitude of maternal mortality. Results from the opportunistic health facility-based sample were virtually identical to results from the household-based study. Guidelines need to be developed for applying this low-cost and efficient aproach to estimating maternal mortality in suitable opportunistic settings at subnational levels.

Adolescent↗
PubMed1999

Microfabricated modules for sample handling, sample concentration and flow mixing: application to protein analysis by tandem mass spectrometry.

The comprehensive analysis of biological systems requires a combination of genomic and proteomic efforts. The large-scale application of current genomic technologies provides complete genomic DNA sequences, sequence tags for expressed genes (EST's), and quantitative profiles of expressed genes at the mRNA level. In contrast, protein analytical technology lacks the sensitivity and the sample throughput for the systematic analysis of all the proteins expressed by a tissue or cell. The sensitivity of protein analysis technology is primarily limited by the loss of analytes, due to adsorption to surfaces, and sample contamination during handling. Here we summarize our work on the development and use of microfabricated fluidic systems for the manipulation of minute amounts of peptides and delivery to an electrospray ionization tandem mass spectrometer. New data are also presented that further demonstrate the potential of these novel approaches. Specifically, we describe the use of microfabricated devices as modules to deliver femtomole amounts of protein digests to the mass spectrometer for protein identification. We also describe the use of a microfabricated module for the generation of solvent gradients at nl/min flow rates for gradient chromatography-tandem mass spectrometry. The use of microfabricated fluidic systems reduces the risk of sample contamination and sample loss due to adsorption to wetted surfaces. The ability to assemble dedicated modular systems and to operate them automatically makes the use of microfabricated systems attractive for the sensitive and large-scale analysis of proteins.

Equipment Design↗
PubMedDate not supplied

Magnetically induced surface charges on samples in magnetic resonance imaging radio-frequency coils: effect on electric fields, sample losses, and coil resonance.

We present a solution to Maxwell's equations which describe the inductive interaction between an irregularly shaped sample in a magnetic resonance imaging rf coil. It is demonstrated that the inductive interaction between the coil and sample can induce charge densities on the sample surface and that these charge densities lead to observable changes in coil Q, resonant frequency offset and sample power dissipation.

Humans↗
PubMed2000

Molecular epidemiological analysis of Cryptosporidium spp. in the United Kingdom: results of genotyping Cryptosporidium spp. in 1,705 fecal samples from humans and 105 fecal samples from livestock animals.

Cryptosporidium present in 1,705 fecal samples from humans and 105 from livestock animals were analyzed by PCR-restriction fragment length polymorphism of the Cryptosporidium oocyst wall protein. Overall, genotype 1 (human exclusive type) was detected in 37.8% of the samples from humans, genotype 2 (broad host range) was detected in 61.5%, a third genotype designated genotype 3 (Cryptosporidium meleagridis) was detected in 0.3%, and both genotypes 1 and 2 were recovered from 0.4%. All samples from livestock yielded genotype 2. Among 469 patients infected during eight drinking water-related outbreaks, five outbreaks were predominantly due to genotype 1, and three were due to genotype 2. Fifty-four samples were collected from patients involved with five swimming pool-associated outbreaks: two outbreaks were due to genotype 1, one was due to genotype 2, and the remaining two involved both genotypes 1 and 2. Among 26 family outbreaks and 1 children's nursery outbreak (2 to 3 members per group), the same genotype was recovered from the different members of each outbreak: 13 were due to genotype 1, and 14 were due to genotype 2. In eighteen patients reporting contact with animals and/or farms, genotype 1 was recovered from one patient and genotype 2 was recovered from the remaining 17. Among the sporadic cases, there were distinct geographical and temporal variations in the distribution of the genotypes. The spring peak in cases was due to genotype 2. Genotype 1 was significantly more common in patients infected during the late-summer-autumn peak and in those with a history of foreign travel.

Animals↗
PubMed1979

Sampling and analysis of organic solvent vapours--with special reference to sampling tubes for a short time and for the working period.

The present paper concerns the sampling and analysis of organic solvent vapours for a short period of time and for the working period. Porous polymer beads, Porapak Q, was applied to the adsorbent of the sampling tube for mixed vapours of aromatic compounds (benzene, toluene and xylenes). The adsorbent was packed in stainless steel column of a suitable size, and the adsorbed vapours were released by heating in the flasher then analysed by gas chromatography. The concentrations of the mixed vapours could be measured simultaneously with sufficient recoveries at the ordinary concentrations in the working yeard. The sampling conditions by pumps and the practical recoveries were tested. Being sucked with the vacuum pump using a Gastek detection tube (100 ml), the recoveries proved to be almost 100%. Being sucked with portable diaphragmatic pumps at a slow flow rate (22 ml/min), the recoveries were constant with only small variations. At a relatively fast flow rate (220-230 ml/min), the recoveries were not so high as those at the slow flow rate. These findings indicate that the sampling tube with Porapak Q is useful for aromatic compounds not only as a room air sampler for a short period of time but also as a personal air sampler.

Air Pollutants↗
PubMed1978

Temporal factors influencing the pigeon's successive matching-to-sample performance: sample duration, intertrial interval, and retention interval.

A successive matching-to-sample procedure that entails the sequential presentation of sample and test stimuli and the monitoring of response rates in a go/no-go discrimination of matching and nonmatching stimuli was studied as an alternative to the familiar delayed-matching paradigm of animal short-term memory. Three within-subject experiments studied the effects of sample duration (1 to 12 seconds), intertrial interval (5 to 50 seconds), and retention interval (1 to 50 seconds) on the pigeon's successive-matching performance. The results revealed that retention was (a) an increasing function of sample duration and intertrial interval, and (b) a decreasing function of retention interval. These results were in accord with those of more traditional short-term memory paradigms, and reveal the suitability of the successive-matching procedure for studying memory processes.

Journal Article↗
PubMedDate not supplied

Effects of sample holding time on concentrations of microorganisms in water samples.

This research investigated the effects of extending the holding time of samples for microbial analysis beyond the standard of 24 hours for purposes such as watershed characterization. Experiments were conducted with both sanitary wastewater and stormwater samples. The refrigerated samples (4 degrees C) were held for up to 9 days before being analyzed for two pathogens (Pseudomonas aeruginosa and Staphylococcus aureus) and five indicator organisms (total coliform, fecal coliform, fecal streptococcus, enterococcus, and Escherichia coli) by membrane filtration. The concentrations (as colony-forming units per 100 mL) were normalized by log10(transformation and used in subsequent statistical analysis testing for significant differences. The results suggested that the concentrations of microorganisms in water samples analyzed on days 1 and 2 did not vary significantly in 8 of 13 analyses. The results of a field study concluded that the concentration of fecal coliform did not change significantly between 7 hours holding time and greater than 24 hours holding time for fecal coliform.

Enterobacteriaceae↗
PubMed2003

Antimicrobial resistance of bacteria isolated from dairy cow milk samples submitted for bacterial culture: 8,905 samples (1994-2001).

OBJECTIVE: To determine whether antimicrobial resistance patterns of major mastitis pathogens isolated from milk samples from dairy cows have changed over time. DESIGN: Retrospective study. SAMPLE POPULATION: 8905 bacterial isolates obtained from milk samples submitted to the Wisconsin Veterinary Diagnostic Laboratory between January 1994 and June 2001. PROCEDURE: Antimicrobial susceptibility was determined by means of the Kirby-Bauer disk diffusion method. Logistic regression was used to determine whether percentages of isolates resistant to various antimicrobials changed over time. RESULTS: For the gram-positive mastitis pathogens, percentages of isolates resistant to various flactam antimicrobials did not increase over the course of the study. Percentage of Staphylococcus aureus isolates resistant to penicillin decreased from 49 to 30%; percentage of Streptococcus isolates resistant to penicillin decreased from 6 to 1%. Percentage of isolates resistant to erythromycin increased for S aureus, Escherichia coli, Enterobacter spp, Enterococcus spp, and Pasteurella spp. Percentage of isolates resistant to lincomycin increased for S aureus and Staphylococcus spp. Percentage of coagulase-negative Staphylococcus isolates resistant to pirlimycin increased from 6 to 19%. For several pathogens, percentages of isolates resistant to sulfisoxazole and to trimethoprim-sulfamethoxazole decreased. No pathogens had a significant increase in the percentage of isolates resistant to novobiocin-penicillin. CONCLUSIONS AND CLINICAL RELEVANCE: Results did not indicate a trend toward increased antimicrobial resistance among mastitis pathogens isolated from milk samples from dairy cows between 1994 and 2001. Reduced resistance to flactam antimicrobials was identified for several gram-positive mastitis pathogens.

Animals↗
PubMed2007

Prevalence of oxacillin- and multidrug-resistant staphylococci in clinical samples from dogs: 1,772 samples (2001-2005).

OBJECTIVE: To determine whether resistance to oxacillin and other antimicrobials in 3 Staphylococcus spp commonly isolated from dogs increased from 2001 to 2005. DESIGN: Retrospective case series. SAMPLE POPULATION: 1,772 clinical samples of various types obtained from dogs examined at the University of Tennessee Veterinary Teaching Hospital or at regional veterinary hospitals and submitted to the bacteriology and mycology laboratories associated with the teaching hospital. PROCEDURES: Samples were submitted by attending veterinarians to the bacteriology and mycology laboratories for routine aerobic microbial culture. Identification and antimicrobial susceptibility procedures were performed on all isolates. Susceptibility reports for each antimicrobial and Staphylococcus spp were determined from aggregate electronically archived test results. Oxacillin and multidrug resistance for Staphylococcus intermedius was analyzed by reviewing disk diffusion zone measurements. RESULTS: Oxacillin resistance increased among S. intermedius isolates during the past 5 years, and the increase was associated with multidrug resistance. In 2005, 1 in 5 Staphylococcus spp isolates from canine clinical samples was resistant to oxacillin. The most common staphylococcal species isolated were S. intermedius (n = 37), Staphylococcus schleiferi (21), and Staphylococcus aureus (4), and frequencies of oxacillin resistance in isolates of these species were 15.6%, 46.6%, and 23.5%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Veterinarians should be aware of the potential for empiric drug treatment failures in instances where Staphylococcus spp infections are common (eg, pyoderma). Judicious use of bacterial culture and susceptibility testing is recommended.

Animals↗
PubMed2002

Development of methods for the recovery of Escherichia coil O157:H7 and Salmonella from beef carcass sponge samples and bovine fecal and hide samples.

Culture methods were developed for the concurrent recovery of Escherichia coli O157:H7 and Salmonella from bovine carcass, hide, and fecal samples. Several enrichment conditions were tested for the overall growth of pure cultures; tryptic soy broth for 2 h at 25 degrees C and then for 6 h at 42 degrees C was the protocol selected for use. Immunomagnetic separation (IMS) was incorporated for sensitivity and selectivity, along with a post-IMS enrichment for the recovery of Salmonella as recommended by the manufacturer. Selective agars for plating after IMS were chosen on the basis of ease of target colony identification. Sorbitol MacConkey agar supplemented with cefixime and potassium tellurite and Rainbow agar supplemented with novobiocin and potassium tellurite were chosen for the recovery of E. coli O157:H7. Brilliant green agar with sulfadiazine and Hektoen enteric agar supplemented with novobiocin were selected for the recovery of Salmonella. The resulting methods were evaluated along with standard or previously used methods for the recovery of E. coli O157:H7 and Salmonella from bovine hide and fecal samples and carcass sponge samples. The Meats Research Unit (MRU) methods performed at least as well as the established methods, except that a secondary enrichment in tetrathionate (TT) broth prior to IMS was required for the optimal recovery of Salmonella from feces. Thus, the MRU and MRU-TT methods are effective in the recovery of both E. coli O157:H7 and Salmonella from a single bovine carcass, hide, or fecal sample.

Agar↗