Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Sampling”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 541 records · Page 30Linked to original sources
PubMed2003

Effect of anticoagulants and sampling time on results of progesterone determination in canine blood samples.

The concentration of plasma progesterone was measured by ELISA, in serum and samples prepared with three different anticoagulant agents - namely ethylenediaminetetraacetic acid (EDTA), heparine and sodium fluoride oxalate potassium(NaFK). Forty clinically healthy bitches were selected based on the signs of pro-oestrus or oestrus. Values of progesterone concentration were significantly higher in serum than in EDTA-plasma (p < 0.0005); heparin-plasma (p < 0.05) and NaFK-plasma (p < 0.005). During pro-oestrus and oestrus until the time of ovulation, progesterone exhibited a conspicuous and statistically verified diurnal pattern (p < 0.05), its serum concentration being higher during 6.00-7.00 p.m. than 8.00-9.00 a.m. By the time of ovulation tendency of higher p.m. progesterone level reverses and from this point on the a.m. progesterone concentration is higher. The results of these experiments indicate that the concentration of canine progesterone assayed with ELISA may be affected by the time of collection and the method of preservation used.

Animals↗
PubMed1975

Cotton dust sampling: I. Short termed sampling.

A short term sampler for cotton dust is introduced which, when used in conjunction with a correctly designed vertical elutriator, gives equivalent results to the Lumsden-Lynch vertical elutriator. The short termed sampler not only offers results which can be applied to the ACGIH TLV but offers an effective means of environmental surveillance in a byssinosis prevention program with the additional advantages of immediate read-out short termed sampling and truer employee exposure.

Byssinosis↗
PubMed2006

Standardization of sample preparation, staining and sampling methods for automated sperm head morphometry analysis of boar spermatozoa.

The accuracy of computer-assisted sperm morphometry analysis (CASMA) depends on the careful preparation, fixation and staining of spermatozoa. The efficiency of CASMA may be enhanced by developing optimized protocols. The aim of the present study was to evaluate the influence of sperm washing and the use of three staining techniques [rapid Panoptic, Hemacolor and Harris's Haematoxylin (HH)] on image-processing accuracy and boar sperm head morphometry. Sperm washing had a significant effect on samples stained with rapid Panoptic, increasing the percentage of correctly binarized sperm heads and the contrast between cells and background. However, rapid Panoptic yielded the lowest percentage of properly digitized sperm heads. HH provided the highest cell/background contrast, and also greater sperm head staining intensity, but discrimination of sperm midpieces was considered insufficient. Hemacolor occupied an intermediate position, providing acceptable colour intensity and satisfactory cell/background contrast. Use of different staining procedures prompted dimensional differences in sperm head morphometry. Significant differences between animals were observed for all morphometric parameters. Low within-animal variation coefficients reflected a homogeneous sperm head population. Between-animal variation coefficients were relatively high for Hemacolor and HH, and significantly high for the rapid Panoptic stain. Using Panoptic and HH, stable morphometric measurements required at least 100 properly digitized sperm heads rather than 200, while Hemacolor required only 50 spermatozoa. These results indicate that both washing of semen and staining procedures significantly affect the accuracy of image processing and sperm head dimensions. Hemacolor and HH proved to be the best staining techniques for evaluating sperm head dimensions in boar.

Animals↗
PubMed1985

Nitrous oxide exposure during routine anaesthetic work. Measurement of biologic exposure from urine samples and technical exposure by bag sampling.

Nitrous oxide exposure in a modern hospital during routine anaesthetic work was measured using a technical exposure measurement technique and compared to measurement of biologic exposure from urine samples. The study included different anaesthetic situations and also a study of the efficiency of close scavenging and general air-conditioning in reducing nitrous oxide exposure. Exposure to nitrous oxide varied greatly. The mean nitrous oxide exposure in the total material was 53 ppm corresponding to approximately half the Swedish control limit (100 ppm) for 8 h time-weighted average (TWA). The only anaesthetic situation regularly resulting in 8 h TWA exposure exceeding the control limit was paediatric anaesthesia (92 +/- 67 ppm, mean +/- s.d.). The use of close scavenging significantly reduced the 8 h TWA nitrous oxide exposure in paediatric anaesthesia. The reduction of exposure was not significant during other forms of anaesthesia where low levels were found when anaesthetic equipment with excess gas scavenging was used in theatres with non-recirculating air-conditioning. The correlation between conventional technical exposure measurement and urine headspace nitrous oxide measurement was good. Both theoretical arguments and practical experience indicate that this method can be used for assessing nitrous oxide exposure during routine anaesthetic work.

Air Pollutants, Occupational↗
PubMed2000

Estimates of maternal mortality by the sisterhood method in rural nothern Tanzania: a household sample and an antenatal clinic sample.

OBJECTIVE: To estimate maternal mortality in two samples of a population in northern Tanzania. SETTING: Rural communities and antenatal clinics, Mbulu and Hanang districts, Arusha region, Tanzania. POPULATION: From a household survey 2,043 men and women aged 15-60, and from an antenatal clinic survey 4,172 women aged 15-59. METHOD: The indirect sisterhood method. MAIN OUTCOME MEASURES: The risk of maternal deaths per 100,000 live births (maternal mortality ratio), and the lifetime risk of a maternal death. RESULTS: The risk of a maternal death per 100,000 live births was 362 (95% CI 269-456) and 444 (95% CI 371-517) for the household and antenatal clinic surveys, respectively. The lifetime risk of maternal death was 1 in 38 and 1 in 31, respectively, for the two surveys. A significantly lower risk of maternal death was observed for the respondents attending antenatal clinics closer to the hospital than for those attending clinics further away: 325 (95% CI 237-413) compared with 561 (95% CI 446-677) per 100,000 live births. Lifetime risk of maternal death was 1 in 42 and 1 in 25, respectively. CONCLUSIONS: The risk of maternal death per 100,000 live births in this area were comparatively high, but in our survey substantially lower than in previous surveys in Tanzania. Increasing distance from the antenatal clinics to the hospital was associated with higher maternal mortality. There was no significant difference between results based on household and antenatal clinic data, suggesting that accessible health facility data using the sisterhood method may provide a basis for local assessment of maternal mortality in developing countries.

Adolescent↗
PubMed1993

Fetal blood sampling and its complications related to the indications for fetal blood sampling.

A prospective study on fetal blood sampling (FBS) was conducted in the Fetomaternal Medicine Division of the Department of Obstetrics and Gynaecology at the National University Hospital, Singapore. FBS was performed on 159 occasions in 156 women between January, 1988 and December, 1991. The aim of this study was to identify the factors that were associated with an adverse outcome following the procedure. Twenty four abnormal pregnancies were terminated; of the remaining 132 desired pregnancies the overall pregnancy loss was 44 (33.3%), which included those within 2 weeks and those after 2 weeks of the procedure and neonatal deaths. Fetal loss occurring within 2 weeks of the procedure is considered a procedure-related loss which occurred in 19 (14.3%) of the 132 pregnancies. When the fetal loss occurred within 2 weeks of the procedure 89% had a major abnormality on ultrasonographic scanning. The conclusion from our study is that the risks of FBS were increased in abnormal pregnancies, most likely due to the underlying pathology.

Blood Specimen Collection↗
PubMed1999

Correct samples for diagnostic tests in sexually transmitted diseases: which sample for which test?

Amplified DNA technology such as the polymerase chain reaction (PCR) and ligase chain reaction (LCR) are new techniques for the diagnosis of genital chlamydial infections in both men and women. These tests are highly sensitive and specific in detecting chlamydial genes in different specimen types such as genital samples as well as in non-invasive specimens such as urine and vulval smears. Due to the advantage of a high reliability of these techniques even when they are performed on non-invasive specimen types, amplification tests allow chlamydial diagnosis for screening especially high risk persons as the basis of chlamydia control programs.

Chlamydia Infections↗
PubMed2006

Comparison between the Gen-Probe transcription-mediated amplification Trichomonas vaginalis research assay and real-time PCR for Trichomonas vaginalis detection using a Roche LightCycler instrument with female self-obtained vaginal swab samples and male urine samples.

This study compared two assays for Trichomonas vaginalis detection, Gen-Probe's transcription-mediated amplification (TMA) assay for Trichomonas vaginalis and BTUB FRET PCR, using self-obtained clinical samples from 611 patients. Infection status was defined as two positive results by two different tests. The initial TMA assay sensitivity was 96.7%; specificity was 97.5%. The TMA assay was comparable to BTUB FRET PCR.

Animals↗
PubMed1986

Alveolar sampling and fast kinetics of tetrachloroethene in man. I. Alveolar sampling.

Human subjects were exposed to tetrachloroethene (perchloroethylene, PER). The duration of exposure ranged from one to 60 minutes and the concentration of PER in inhaled air ranged from 0.02 to 0.40 mmol/m3. Alveolar air was sampled after several residence times (t*) in the lung. Both during and after exposure, the concentration of PER in alveolar air (C Alv) as a function of the residence time was studied to estimate the concentration in the pulmonary artery (C Ven: mixed venous blood) and in the pulmonary vein (C Art: arterial blood). During exposure C Alv decreased as function of t*. At t* = 10 s C Alv was 70-75% of the value presented at t* = 5 s; this decrease approximates an exponential curve. C Alv seemed to stabilise at t* = 10-12 s, whereas it decreased more rapidly at t* greater than 12 s; this decrease continued up to at least t* = 55 s when C Alv was about 40% of the value it represented at t* = 5 s. In the postexposure period C Alv increased as function of t* from 5 to 10 s. Both during and after exposure, no difference was observed between C Alv at t* = 10 s and C Alv in the exhaled part of the expiratory reserve volume. A simple gas exchange model showed that the decrease or increase of C Alv at t* less than 10 s could be explained by either absorption or excretion by mixed venous blood. C Alv at t* = 10-12 s provided a valid estimate of C Ven. To estimate C Art, its fluctuating character due to the discontinuous breathing with a breathing frequency had to be taken into account. It is shown that C Alv during normal breathing (t* = 5 s) provides a reasonable estimate of the time weighted concentration in arterial blood.

Female↗
PubMedDate not supplied

Loss of straight metalworking fluid samples from evaporation during sampling and desiccation.

Straight metalworking fluids (MWFs) were used to evaluate the potential for the loss of MWF mass from filters. Two methods were used to study the stability of MWF mass on filter media. The first was to spike known amounts of MWF onto polyvinyl chloride (PVC) filters, store the filters over silica gel desiccant, and take repeated gravimetric measurements of the filters at intervals of 1, 2, and 3 days. An MWF aerosol mist was generated in a test chamber and collected on PVC filters for the second experimental method. Additional clean air was drawn through a subset of filters (range 0.02-0.48 m(3)), which were then stored over silica gel prior to weighing. Losses due to desiccation were found in filters that had not been exposed to airflow, as well as for filters after aspiration. The losses occurring in spiked filters (range of mean 2.6-15.2%) were higher than those in collected filters (range 0.7-8.1%). The MWF aerosol mass collected on PVC filters decreased with the increasing volume of clean air passing through the filter. In a multiple regression model, to predict the loss of collected MWF due to desiccation, loading mass, fresh MWF, and air passing time of 10 min were significant predictors (p=.0001, R(2)=.374). In particular, only air passage of 10 min was significantly higher (2.13%) than the reference air passage (p=.0054). The investigators concluded that MWF aerosol collected on PVC filters may be lost to evaporation under conditions typical of shipment, storage, and desiccation of sample filters, and with airflow through the filter.

Aerosols↗
PubMed1986

Methods of time sampling: A reappraisal of momentary time sampling and partial interval recording.

We compared the accuracy of momentary time sampling (MTS) and partial interval recording (PIR) in estimating both absolute behavioral levels and relative change. A computer randomly generated runs of pseudobehavior varying in duration and rate and simulated MTS and PIR of each run. Results indicated that when estimating absolute behavioral levels, duration rather than rate should be used as the dependent measure, and MTS is more accurate than PIR. In contrast, PIR is the more sensitive method for detecting relative changes in behavioral levels, although, at high rates, PIR tends to underestimate the degree of change.

Journal Article↗
PubMed1983

The difference in the instar composition of immature mosquitoes sampled by three sampling techniques.

Three techniques, namely a ladle, a metal quadrat and a D-shaped aquatic net, were used for comparison to sample immature stages of mosquitoes in woodland pools in northern England. The quadrat proved to be more reliable in giving a more accurate representation of the different instar proportions in the ponds than the ladle and aquatic net. The ladle showed bias of undersampling the earlier instars. Similar but not so severe bias also occurred for the D-net.

Aedes↗
PubMed2002

Ultrarapid, ultrasensitive one-step kinetic immunoassay for C-reactive protein (CRP) in whole blood samples: measurement of the entire CRP concentration range with a single sample dilution.

BACKGROUND: Recently, measurement of very low concentrations of C-reactive protein (CRP) has gained popularity as a potential new means for predicting the risk of future cardiac complications. In this study, we demonstrate the feasibility of a kinetic, one-step microparticle assay for quantitative determination of extremely low and high CRP concentrations in the limited timeframe typical for point-of-care testing. METHODS: A noncompetitive, kinetic CRP immunoassay was developed that uses individual, porous microparticles as the solid phase. The microparticles were covalently coated with a monoclonal capture antibody, and the monoclonal detection antibody was labeled with europium. The one-step binding reaction was stopped by washing after 2 min of incubation, and the fluorescence signal of individual particles was measured. RESULTS: The analytical detection limit (mean of zero calibrator + 3 SD) was 0.00016 mg/L CRP. Clinical samples were diluted 400-fold before assay to cover the CRP concentration range of 0.064-1200 mg/L. The assay correlated well with the Dade Behring N High Sensitivity CRP assay (for 0-10 mg/L, r = 0.969, S(y/x) = 0.68, n = 54; for 0-350 mg/L, r = 0.969, S(y/x) = 11.7, n = 100). The within- and between-run CVs based on calculated concentrations were, respectively, 9-16% and 14% at 0.11 mg/L, 4.5-12% and 8.2% at 4.2 mg/L, and 3.5-6.3% and 4.4% at 105 mg/L, with a CV <15% at 0.2 mg/L and above. CONCLUSIONS: Use of the kinetic microparticle approach combined with time-resolved fluorometry allows ultrasensitive quantification of CRP in whole blood in 2 min with a linear assay range spanning more than four orders of magnitude.

Antibodies, Monoclonal↗
PubMed2002

Frequent detection of K-ras mutation in stool samples of colorectal carcinoma patients after improved DNA extraction: comparison with tissue samples.

Fecal occult blood testing is widely used in the clinical screening of colorectal tumors. However, this method has so frequent false-positive results that more accurate screening-strategy should be established. Although the molecular screening using K-ras gene mutation in stools has been attempted to improve the results, the low rate of DNA extraction from stools leaves this measurement under utility value. In this study, we investigated whether or not our applied DNA extraction method from stools could produce enough DNA for the molecular screening of colorectal tumors by K-ras gene mutations in stools. We applied cetyltrimethylammonium bromide (CTAB) solution to improve human DNA extraction from stools and a mutant-allele-sensitive amplification (MASA) method to detect K-ras mutation within codon 12. We were able to confirm the stool DNA by identifying K-ras fragments in all the 20 patients. Tissue K-ras mutation was identified in 4 (2 cancers and 2 adenomas) of 20 patients. Stool K-ras mutations were found in 6 patients, 3 tissue K-ras mutation positive patients (2 cancers and an adenoma) and 3 tissue K-ras mutation negative patients. These results indicate that it is possible to extract enough DNA from human stool samples of all patients with colorectal tumors for K-ras mutation studies. K-ras mutations are more frequently detected in stools than in resected colorectal tumors. This study indicates that K-ras mutation screening in stools for colorectal cancer may include not only a primary colorectal cancer but also precancerous lesions in all parts of a gastrointestinal tract.

Aged↗
PubMed2004

Assessment of human exposure to airborne fungi in agricultural confinements: personal inhalable sampling versus stationary sampling.

Accurate exposure assessment to airborne fungi in agricultural environments is essential for estimating the associated occupational health hazards of workers. The objective of this pilot study was to compare personal and stationary sampling for assessing farmers' exposure to airborne fungi in 3 different agricultural confinements located in Ohio, USA (hog farm, dairy farm, and grain farm), using Button Personal Inhalable Samplers. Personal exposures were measured with samplers worn by 3 subjects (each carrying 2 samplers) during 3 types of activities, including animal feeding in the hog farm, cleaning and animal handling in the dairy farm, and soybean unloading and handling in the grain farm. Simultaneously, the stationary measurements were performed using 5 static Button Samplers and 1 revolving Button Sampler. The study showed that the total concentration of airborne fungi ranged from 1.4 x 10(4)-1.2 x 10(5) spores m(-3) in 3 confinements. Grain unloading and handling activity generated highest concentrations of airborne fungi compared to the other 2 activities. Prevalent airborne fungi belonged to Cladosporium, Aspergillus/Penicillium, Ascospores, smut spores, Epicoccum, Alternaria, and Basidiospores. Lower coefficients of variations were observed for the fungal concentrations measured by personal samplers (7-12%) compared to the concentrations measured by stationary samplers (27-37%). No statistically significant difference was observed between the stationary and personal measurement data for the total concentrations of airborne fungi (p > 0.05). Revolving stationary and static stationary Button Samplers demonstrated similar performance characteristics for the collection of airborne fungi. This reflects the low sensitivity of the sampler's efficiency to the wind speed and direction. The results indicate that personal exposure of agricultural workers in confinements may be adequately assessed by placing several Button Samplers simultaneously operating in a static stationary mode throughout the work site.

Agriculture↗
PubMed1996

Measurement of insulin pulsatility by sampling directly from the portal vein: a surgical model for placement of long-term prehepatic vascular sampling catheters.

A practical and repeatable method for measurement of pulsatile insulin release in the dog was developed by direct, chronic cannulation of the portal vein cephalad to the pancrease and the entry point of the cranial pancreaticoduodenal vein, with subsequent exteriorization of the sampling catheter. Mixed breed male dogs of various body weights and ages underwent midline laparotomy for exposure of the portal vein system. After exposure the portal vein was dissected free and cannulated through a purse-string suture placed just caudad (approximately 1 cm) to the entry point of the cranial pancreaticoduodenal vein with a cuffed, medical grade, silastic catheter. The catheter was advanced cranial to a point just distal to the level of the liver and secured in place via the purse-string suture and a single stay suture. The catheter was then passed through the dorsolateral abdominal wall and routed subcutaneously to a point between the shoulder blades. After catheter plug attachment the catheter was tested for patency, flushed, heparin locked, then was secured to the subcutaneous tissue between the scapulas. The dorsal skin wound and abdominal incision were closed in a routine manner, and the dogs recovered from anesthesia. Catheter patency and function in all dogs were maintained for periods up to 4 weeks. No postoperative complications such as catheter tract infections occurred, maintenance was minimal, and all dogs were afforded complete freedom of movement and activity throughout the study, with no requirement for cumbersome jackets or wraps.

Animals↗