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[Quantitative cytological findings in mixed milk samples].

In two cow-houses (fifty cows in each), 5851 udder-quarter samples were subjected to cytological examination (by the Coulter Counter electronic computer) and to bacteriological examination during a ten-month period; the cytological examination was also performed with 141 can milk samples. The mixed samples in which the number of cellular elements does not exceed the level of 500 thousand ml-1 do not indicate reliably whether the milk comes from healthy udder quarters or contains an admixture of secretion from the diseased quarters. A value of above 500 thousand cellular elements per ml in mixed samples only suggests that the milk probably contains more secretion from infected udder quarters. The number of cells in the mixed samples does not constitute a basis for the conclusion concerning the number of quarters with impaired secretion which contributed to the sample, because the number of cells in the mixed samples depends also on the degree of disease in the respective quarters. An amount up to 500 thousand cellular elements per ml in the mixed sample provides practically no useful and usable information on milk quality. If the number of cellular elements per ml is higher than 500 thousand, this information is only suitable for revealing the stables with a high occurrence of mastitis--it is just a signal, not a parameter of such a situation. It is from this aspect that all results should be evaluated at those places where only mixed samples can be examined.

Animals↗

Control of choice in conditional discriminations by sample-specific behaviors.

When sample-specific responding is occasioned by sample stimuli in matching and oddity tasks with pigeons, such responding controls the choices between comparison stimuli. This control was investigated in four experiments. In Experiments 1 and 2, differential responding to the samples in line-line matching and line-line oddity was reversed following acquisition of these problems. The reversal interfered with reacquisition of the same conditional discrimination but facilitated acquisition of the opposite discrimination. In Experiment 3, pigeons initially trained on line-line matching were shifted to hue-line matching. Positive transfer occurred when correct choices in both tasks were paired with the same sample-response patterns. Conversely, negative transfer occurred when correct choices were paired with opposite patterns. In Experiment 4, two concurrent conditional discriminations were designed so that sample-response patterns were paired with specific sample stimuli, but not with correct choices. Faster acquisition occurred when response patterns differed within rather than between sample dimensions. Furthermore, sample-specific responding controlled choices when the dimensional stimuli were difficult to discriminate but not when they were easy to discriminate. The combined results are interpreted in terms of overshadowing. Visual stimuli that control choice can be overshadowed by sample-specific responding if the latter facilitates conditional discrimination acquisition.

Animals↗

Research design: sampling techniques.

Conditions affecting the decision of whether to take a census or a sample; the major types of sampling procedures, both probability and nonprobability;; and the statistical approaches to sample size determination for simple random samples are discussed. An overview of selected terms and symbols used in sampling literature and a checklist of basic questions to guide a researcher interested in using sampling for a study are provided. While the researcher can control sampling error by increasing the sample size, the concern should be the magnitude of the total error for the study (both sampling and nonsampling errors).

Pharmacy Service, Hospital↗

Ultra-rapid freezing of thin biological samples.

Miniature thermocouples are used to follow the time course of cooling within test samples plunged into liquid coolants. Variations in the temperature and type of coolant (propane, Freon 22, sub-cooled liquid nitrogen), in the velocity and depth of plunge, and in the size and shape of samples were investigated. Coolants have their optimum cooling properties at their lowest liquid temperatures but show different dependencies on temperature. The optimum velocity of plunge depends on the shape of the sample. The strongest influence on cooling rate comes from the size and shape of the sample. Spherical samples about 1 mm3 show rates < 500 decrees C/s while samples 0.001 mm3 show rates > 50,000 degrees C/s for freezing in liquid propane under identical conditions. Thin samples of equivalent volume can be more rapidly frozen. Cooling rates of about 11,900 degrees C/s (0 degrees C to -100 degrees C) are recorded for thin samples (0.1 mm3 and 20 micrometers thick) sandwiched between copper strips and rapidly plunged into liquid propane (-190 degrees C). An apparatus is described for using these holders in freeze-fracture studies. Thin samples thus frozen show no evidence of ice crystal growth in either low-temperature x-ray diffraction patterns or in freeze-fracture electron micrographs.

Freeze Fracturing↗

Do pharmaceutical representatives misuse their drug samples?

OBJECTIVE: To determine the extent to which pharmaceutical representatives misuse their samples. DESIGN: Voluntary questionnaire survey. SETTING: A family practice office. PARTICIPANTS: Pharmaceutical representatives visiting the office during a 3-month period. MAIN OUTCOME MEASURES: Number of surveyed representatives who self-medicated, provided samples of prescription drugs to nonphysicians, or exchanged drugs with other representatives; classes of prescription drugs most commonly used; and beneficiaries. RESULTS: Of the 27 representatives surveyed, 16 (59.2%) have provided prescription drug samples to individuals other than physicians. Thirteen (48.1%) either self-medicated or provided samples to friends or relatives. Seven (25.9%) have exchanged drug samples with other representatives. Eleven (40.7%) of the 27 surveyed had not sampled prescription drugs themselves, given them to others, or exchanged drugs with other representatives. The most commonly sampled drugs were nonsteroidal anti-inflammatory drugs. Drug samples were most often given to friends and spouses. CONCLUSION: Self-medication and giving samples to nonphysicians were practised by almost 60% of surveyed representatives. Representatives usually caution recipients, however, and there are very few complications. Drugs with potential for abuse or dependence and cardiovascular medications were rarely used.

Adult↗

[Reliability of bacteriological studies of composite samples in the diagnosis of subclinical udder infections in cattle].

This study evaluated the reliability of making bacteriological cultures of composite milk samples for the diagnosis of subclinical udder infections in dairy herds. Quarter samples as well as composite samples were collected from 482 cows with suspected subclinical mastitis from 69 Dutch dairy farms. The samples were used to measured somatic cell counts and to prepare bacteriological cultures. The sensitivity and specificity of the bacteriological cultures of the composite samples were compared with those of the quarter samples. The sensitivity of Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae and Streptococcus dysgalactiae was 57.9%, 65.2%, 86.6%, and 60.3%, respectively. The specificity was higher than 98% for all four bacteria. Although information is lost when composite samples are used, composite samples are useful, especially for large dairy herds. The advantage and disadvantages of the use of composite samples are discussed.

Animals↗

Prospective evaluation of selective venous sampling for parathyroid hormone concentration in patients undergoing reoperations for primary hyperparathyroidism.

BACKGROUND: The utility of standard radiologic imaging studies in guiding reoperative parathyroid surgery for primary hyperparathyroidism is widely known and accepted. The additional information gained by selective venous sampling in that patient population has not been well defined. We report the results of our experience with this method. METHODS: Between 1982 and 1992, 223 consecutive patients underwent reoperations for persistent or recurrent primary hyperparathyroidism after a prospectively determined series of imaging studies. Patients underwent noninvasive testing consisting of ultrasonography, computed tomography, technetium thallium scanning, and magnetic resonance imaging. Patients with negative, equivocal, or discordant results on the noninvasive studies proceeded to angiography. If angiography was negative, selective venous sampling was performed. RESULTS: Eighty-six patients (39%) with negative or equivocal noninvasive test and angiogram results underwent selective venous sampling. Seventy-six patients (88%) had a significant gradient in levels of parathyroid hormone from veins draining the left side of the neck (n = 25), the right side of the neck (n = 33), both sides of the neck (n = 7), and the thymus (n = 11). Correlation of these findings with operative findings revealed a sensitivity of 88% and a specificity of 86%. In the subgroup of patients who underwent venous sampling and had completely negative results of standard radiologic studies (35 of 86; 40%), 28 patients (80%) had venous gradients and seven patients (20%) had no gradient. Of those 28 patients in whom the venous sampling gradients were the only positive localization study, the venous samplings were helpful in 23 patients (true positive gradients), and the operative success rate was 93%. In the seven patients with no positive preoperative localizing studies including venous sampling, there were two operative failures (operative success, 71%). CONCLUSIONS: Our results show that selective venous sampling is a highly sensitive and specific method to regionally localize abnormal parathyroid glands not imaged by standard noninvasive and invasive radiologic techniques. Venous sampling is the study of choice in guiding reoperative procedures for occult abnormal parathyroid glands that are undetected despite the use of all available imaging studies.

Diagnostic Imaging↗

Papanicolaou smear adequacy: the effect of the sampling sequence.

BACKGROUND: The purpose of this study was to determine the effect of ectocervical sampling methods and sequence on Papanicolaou smear adequacy. METHODS: A randomized clinical trial was performed using either a curved cytologic sampling brush or Ayre spatula for ectocervical sampling before or after a straight sampling brush for endocervical sampling. RESULTS: The adequacy of ectocervical smears, as measured by the presence of columnar cells or squamous metaplasia, differed significantly among the four techniques studied. When the Ayre spatula was used second, 115 (69 percent) of 167 ectocervical smears were adequate compared with 75 (48 percent) of 156 smears when it was used first. Likewise, when the curved brush was used second, 116 (67 percent) of 172 ectocervical smears were adequate compared with 80 (50 percent) of 160 smears when it was used first. One hundred ninety-six (59 percent) of 332 ectocervical smears obtained with a curved brush were adequate compared with 190 (59 percent) of 323 ectocervical smears obtained with a spatula. CONCLUSIONS: The differences among the four ectocervical sampling techniques studied were due to the sequence of ectocervical sampling rather than the instrument utilized. We recommend that an ectocervical sample be obtained only after a straight brush is used to obtain an endocervical sample.

Adult↗

Efficacy of 1% sodium fluoride as a preservative in urine samples containing glucose and Candida albicans.

Whether urine samples used in forensic science DUI testing can be compromised by endogenous ethanol production is a recurrent and yet unresolved issue. This study first assessed unpreserved urine samples that were collected, processed, and analyzed repeatedly over 13 to 41 days using a standard gas chromatographic procedure for ethanol analysis. Despite extensive microbial growth, ethanol was not detected in any test sample. The extent of ethanol production in samples supplemented with glucose, Candida albicans, or both was determined to evaluate the potential for ethanol production in urine samples associated with pathological conditions such as urinary tract yeast infections and diabetes mellitus. Ethanol production under each of the above treatment conditions was assessed in the presence and absence of 1% sodium fluoride as a microbial suppressant. Mean ethanol concentrations were determined for unpreserved samples containing urine only (0.003 +/- 0.005 g%), urine plus yeast (0.006 +/- 0.009 g%) and urine plus glucose (0.067 +/- 0.070 g%). Unpreserved samples supplemented with both yeast and glucose attained mean ethanol concentrations of 0.164 +/- 0.057 g% (P < 0.01). Ethanol could not be detected in any corresponding duplicate samples, which were preserved with 1% sodium fluoride. A lack of ethanol production in any of the unpreserved urine samples indicates that false DUI convictions due to endogenous ethanol production are very unlikely. And while endogenous ethanol production is possible in the presence of both glucose and contaminating C. albicans, 1% sodium fluoride completely eliminated microbial fermentation.

Alcoholic Intoxication↗

Automated technique for sampling milk from farm bulk tanks: collaborative study.

An automated, in-line, mechanical technique for sampling milk from farm bulk tanks was evaluated in a collaborative study. The automated sampling device, which is mounted on the milk intake line, contains an electronically controlled peristaltic pump. The device takes a representative sample of the entire volume pumped through the system. Samples taken can be analyzed for both composition and microbiological quality. The study was performed in 3 phases. In the first 2 phases, samples taken by manual and automated methods were compared in analyses for somatic cell count, antibiotics, fat, protein, lactose, and solids-not-fat. The third phase, using a modified procedure, was designed to compare sampling methods in analyses for total bacteria count (standard plate count), psychrotrophic bacteria count, and coliform count. Evaluation of the data by a nested ANOVA indicated no difference between results for samples taken by the automated and manual methods (P = 0.05) in Phases 1 and 2, irrespective of whether the bulk milk was agitated before sampling. By introducing a sanitizing step between farms in Phase 3, the automated method also provided samples comparable with those taken manually for microbial analyses. The automated method has been adopted first action by AOAC International.

Animals↗

Diagnosis of Enterocytozoon bieneusi (microsporidia) infections by polymerase chain reaction in stool samples using primers based on the region coding for small-subunit ribosomal RNA.

OBJECTIVE: Enterocytozoon bieneusi is the most prevalent microsporidian causing chronic diarrhea in patients with acquired immunodeficiency syndrome. The current methods used for routine diagnosis of infections caused by microsporidia are based on microscopic detection of the microorganism spores in stained smears. We evaluated the usefulness of the polymerase chain reaction (PCR) technique as a tool to diagnose Enterocytozoon bieneusi infections, using the species-specific diagnostic primer pair EBIEF1/EBIER1 on stool samples that were also analyzed by optical microscopy. DESIGN: To perform PCR in such samples, we developed a novel protocol to obtain DNA free of PCR inhibitors. This protocol was based on disruption of spores using glass beads and overnight digestion with proteinase K; final purification was accomplished with the RapidPrep Micro Genomic DNA isolation Kit for Cells and Tissues (Pharmacia Biotech Inc, Piscataway, NJ). We also evaluated this approach on aliquots of a sample fixed in formalin from 1 to 10 days. PATIENTS AND SAMPLES: We evaluated the PCR technique on 64 stool samples obtained from patients with acquired immunodeficiency syndrome who had persistent chronic diarrhea. Patients were from Spain, Brazil, Germany, and the United States. RESULTS: Using this approach, we could confirm the presence of E bieneusi in all 17 positive samples; no false-positive results were observed. We could also amplify E bieneusi DNA in 10 aliquots of one sample fixed up to 10 days in 10% formalin. CONCLUSION: We conclude that PCR technology is very suitable for species identification of microsporidia in stool samples and may have a potential application in prospective studies in formalin-fixed samples.

Animals↗

Epidemiologic analysis of Mycoplasma spp isolated from bulk-tank milk samples obtained from dairy herds that were members of a milk cooperative.

OBJECTIVE: To determine the prevalence of Mycoplasma spp in herds that were members of a milk cooperative. DESIGN: Epidemiologic study. SAMPLE POPULATION: 267 dairy herds that were members of a milk cooperative. PROCEDURE: Bulk-tank milk samples were collected monthly during a 6-year period from all dairies in the cooperative. Samples were submitted to the cooperative's laboratory for bacterial culture for Mycoplasma spp, using direct plating. Milk samples positive for Mycoplasma organisms were speciated. RESULTS: Prevalence of positive samples varied from 1.8 to 5.8% for all species of Mycoplasma and from 1.2 to 3.1% for Mycoplasma spp known to be mastitis pathogens. One mycoplasmal species was isolated initially on 99 of 198 (50.0%) dairies, but 68 of 198 (34.3%) dairies had 2 species isolated. Mycoplasma bovis, M californicum, and M bovigenitalium were consistently isolated, but M bovis (243/499; 48.6%) was the most commonly isolated species. Acholeplasma laidlawii was more prevalent in 1989 and 1995 than other years. Mycoplasma bovigenitalium and M californicum had a seasonal distribution. Less than 50 colonies per plate were isolated for most (317/500; 63.4%) bulk-tank samples. Of the milk samples with > 100 colonies/plate, Mycoplasma bovis was isolated most frequently (73/243; 30.0%). CLINICAL IMPLICATIONS: Distribution of Mycoplasma spp varied by year, number of colonies isolated per sample, season, and herd. Therefore, it may be necessary to routinely sample bulk-tank milk, and all isolates should be speciated. Culture results from milk cooperatives should be used with other monitoring information to determine the Mycoplasma status of herds.

Analysis of Variance↗

Critical issues and further questions about respondent-driven sampling: comment on Ramirez-Valles, et al. (2005).

The application of respondent-driven sampling (RDS) is a promising new approach to understanding hidden populations, including those at high risk for HIV infection. The method has significant advantages over other sampling methods, including the possibility that representativeness samples can be accrued. However, the requirements for a respondent-driven sample to achieve representative and to demonstrate its superiority over other methods are quite strict. This report focuses on whether the accompanying paper by Ramirez-Valles et al. fulfills these requirements in terms of the theorems underlying RDS regarding sample recruitment rates, referral patterns, and network sizes. Further, it investigates the assertion that the accrued sample has proven that RDS is superior to more traditional time-location or venue-based sampling methods. Unconvinced that either is the case, the author suggests a method to test if RDS is indeed the gold-standard recruitment strategy for obtaining inclusive and representative samples of hidden populations.

Data Collection↗

Large-sample confidence intervals for validity and reliability coefficients.

Large-sample confidence intervals (CI) for reliability, validity, and unattenuated validity are presented. The CI for unattenuated validity is based on the Bonferroni inequality, which relies on one CI for test-retest reliability and one for validity. Covered are four reliability-validity situations: (a) both estimates were from random samples; (b) reliability was from a random sample but validity was from a selected sample; (c) validity was from a random sample but reliability was from a selected sample; and (d) both estimates were from selected samples. All CIs were evaluated by using a simulation. CIs on reliability, validity, or unattenuated validity are accurate as long as selection ratio is at least 20% and selected sample size is 100 or larger. When selection ratio is less than 20%, estimators tend to underestimate their parameters.

Confidence Intervals↗

Sampling designs for HIV molecular epidemiology with application to Honduras.

Proper sampling is essential to characterize the molecular epidemiology of human immunodeficiency virus (HIV). HIV sampling frames are difficult to identify, so most studies use convenience samples. We discuss statistically valid and feasible sampling techniques that overcome some of the potential for bias due to convenience sampling and ensure better representation of the study population. We employ a sampling design called stratified cluster sampling. This first divides the population into geographical and/or social strata. Within each stratum, a population of clusters is chosen from groups, locations, or facilities where HIV-positive individuals might be found. Some clusters are randomly selected within strata and individuals are randomly selected within clusters. Variation and cost help determine the number of clusters and the number of individuals within clusters that are to be sampled. We illustrate the approach through a study designed to survey the heterogeneity of subtype B strains in Honduras.

Adolescent↗

Sample size calculations for paired or matched ordinal data.

The problem of calculating the number of subjects in a paired or matched study in which the outcome variable is ordinal is discussed. A common approach in the case of a two category variable is to calculate the required number of discordant pairs, and then divide this by the expected proportion of discordant pairs to obtain the total sample size. An approximate solution for the number of discordant pairs is proposed for ordinal data and compared to sample sizes estimated through simulation. It is shown that the sample sizes are underestimated when the number of categories is two, but that the approximation improves as the number of categories increases. Comparison of the required discordant sample size when there are two categories with the required sample size for more than two categories would suggest that the loss of power is not great if a categorical variable is collapsed into only two categories. However, the total sample size required is likely to be greater with only two categories, since the expected proportion of discordant to concordant pairs increases. Since the expected number of discordant pairs is likely to decrease as the number of categories increases, this suggests that as a rule of thumb the required discordant sample size for the two category case be used as an approximation to the total required sample size when the number of categories is greater than two.

Clinical Trials as Topic↗

Metaproteomic Analysis to Assess the Impact of Storage Media on Human Gut Microbiome in Fecal Samples.

The human gut microbiome is a diverse community of microorganisms residing in the gastrointestinal tract. The storage condition of fecal samples may impact the taxonomic and protein compositions of microbiomes in these samples. Here, we performed a mass spectrometry-based metaproteomic study to assess the impact of storage media on human gut microbiome in fecal samples. We evaluated FDA-authorized OMNIgene&#xb7;GUT (OG), phosphate-buffered saline (PBS), and RNALater (RNAL) buffers and identified 38,185 microbial peptides corresponding to 7348 microbial proteins, which matched 16 phyla, 20 classes, 50 orders, 104 families, 332 genera, and 453 species. We found a high similarity among the fecal microbiomes preserved in OG, PBS, and RNAL in terms of the identification of proteins, taxa, and functional annotations. Both alpha and beta diversity suggested the high similarity among samples stored in the three media. Nonetheless, we also found some notable differences among buffers regarding the abundances of a few taxon groups. A partial human proteome (over 400 proteins) was identified in the fecal samples, with most of these proteins associated with the membrane and extracellular regions. The findings indicate the similarity among microbiomes in the fecal samples stored in OG, PBS, and RNAL regarding proteome profile, taxa, and functional capacity. SUMMARY: This study thoroughly analyzed and compared the metaproteomes of fecal samples preserved at -80&#xb0;C in PBS, RNALater, and OMNIgene&#xb7;GUT Dx buffers, offering novel insights into the effectiveness of these buffers in maintaining the stability and composition of the human gut microbiome. We found a high similarity in the identification and quantification of proteins, taxa, and functional annotations across the three buffers, with notable quantitative differences highlighting subtle yet important variations in preservation efficacy. The unique datasets and findings could offer valuable revelations into the impact of fecal sample preservation on translational and clinical analyses of the human gut microbiome.

Humans↗

Sampling minority groups in health surveys.

Sampling racial and ethnic minority groups in population-based health studies presents the statistical designer with a variety of notable challenges, many of which can be traced to the manner in which the sampling frame maps into the set of group members. A brief review of sampling approaches aimed at race/ethnic groups is followed by findings on two particularly important statistical issues one may face when sampling minorities: the implications of the geographic diffusion of minorities within sampled area clusters, and the relative utility of different forms of space and time sampling to deal with sometimes dramatic change over time in the linkage between entries on a sampling frame and members of relatively mobile minority groups. Simulated findings from practical illustrations involving the sampling of Hispanics are presented to address each issue.

Health Services Needs and Demand↗