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PubMed1999

Amniocentesis or chorionic villus sampling in multiple gestations? Experience with 500 cases.

500 women with multiple pregnancies underwent amniocentesis or chorionic villus (CV) sampling at our department between January 1988 and July 1997. The aim of this retrospective study was to evaluate the laboratory aspects and the consequences of discordant results in these pregnancies in relation to the method of sampling. Uncertain results in one or both samples, requiring further investigation were more frequent in CV samples (eight times in 163 paired samples, 5 per cent) than in amniotic fluid (AF) samples (once in 298 paired samples, 0.3 per cent). Sampling one fetus twice (erroneous sampling) was seen only once among 163 pregnancies with two CV samples in our study. Cross contamination due to mixed sampling was discovered in two of seven pregnancies that underwent DNA diagnosis in CV and might be a rather regular occuring phenomenon. In none of the 500 pregnancies mixed sampling caused diagnostic dilemmas. A third sampling problem, maternal cell contamination caused a diagnostic problem once among the AF samples. Selective fetal reduction appeared safer after CV sampling than after amniocentesis. Subsequently, CV sampling instead of amniocentesis has become the method of choice for prenatal diagnosis in multiple pregnancies in our department.

Amniocentesis↗
PubMed2005

Comparison of two techniques for transcervical cell sampling performed in the same study population.

OBJECTIVES: The aim of this study was to evaluate and compare the presence of fetal cells in transcervical cell (TCC) samples collected in the first trimester of pregnancy by two different procedures [mucus collection and intrauterine lavage (IUL)], performed consecutively in the same subjects scheduled for elective termination of pregnancy (TOP). METHODS: A total of 126 mucus/IUL sample pairs were retrieved from pregnant women immediately before TOP at a gestational age ranging from 7 to 12 weeks; at termination, samples of placental tissue were collected in all cases. All mucus samples were analysed by a polymerase chain reaction (PCR) assay and, in a subset of experiments involving 56 specimens, also by fluorescence in situ hybridization (FISH) procedure. IULs were divided in two aliquots, one for PCR analysis and one for the preparation of FISH slides. All placental tissue samples obtained at termination were analysed by FISH for fetal sexing. The PCR assay for fetal sex determination was performed by using, in a multiplex reaction, primers for SRY (Y chromosome sex-determining region, 738 bp) and HUMARA (human androgen receptor on the X chromosome, 280 bp) genes. The FISH analysis was carried out using direct-labelled commercial probes for X chromosome alpha-satellite (DXZ1, Xp11.1-q11.1, spectrum green) and Y chromosome alpha-satellite (DYZ3, Yp11.1-q11.1, spectrum orange) regions. RESULTS: In samples from known male pregnancies (n = 67), full concordance between IUL and mucus results could be found in 11 cases (16.4%); in 41 cases, Y chromosome material was detected by FISH (n = 2), by PCR (n = 5) or both (n = 34) in IUL samples, but not in the corresponding mucus samples. Y chromosome material was not documented in 10 mucus/IUL sample pairs. In 5 cases, the FISH (n = 2), the PCR (n = 1) or both (n = 2) failed to detect Y chromosome material in IULs, which was detected, however, by PCR in the corresponding mucus samples. Overall, correct sex prediction was achieved in 55/67 IULs (82%) and in 16/67 (23.9%) mucus samples from male pregnancies. In samples from known female pregnancies (n = 56), full concordance between results of IUL/mucus pairs and those on placental samples could be found in 53 cases (94.6%); in 3 cases, Y chromosome material was documented by PCR in mucus samples, but not in the corresponding IULs. Correct sex prediction was therefore achieved in 56/56 IULs (100%) and in 53/56 (94.6%) mucus samples from female pregnancies. CONCLUSION: This study provides evidence that, among TCC sampling techniques, IUL, but not mucus collection, can yield fetal cells in a constant and reliable fashion, which is a basic prerequisite for possible clinical usage. This suggestion had already emerged from some previous investigations but, owing to the study design, differences in study populations can no longer be used to explain the very different and sometimes-conflicting results reported in earlier studies.

Abortion, Induced↗
PubMed2003

Evaluation of herd sampling for Salmonella isolation on midwest and northeast US dairy farms.

Epidemiologic investigations of Salmonella infections in dairy cattle often rely on testing fecal samples from individual animals or samples from other farm sources to determine herd infection status. The objectives of this project were to evaluate the effect of sampling frequency on Salmonella isolation and to compare Salmonella isolation and serogroup classification among sample sources on 12 US dairy farms sampled weekly for 7-8 weeks. Three herds per state were enrolled from Michigan, Minnesota, New York and Wisconsin based upon predefined herd-size criteria. Weekly samples were obtained from cattle, bulk tank milk, milk filters, water and feed sources and environmental sites. Samples were submitted to a central laboratory for isolation of Salmonella using standard laboratory procedures. The herd average number of cattle fecal samples collected ranged from 26 to 58 per week. Salmonella was isolated from 9.3% of 4049 fecal samples collected from cattle and 12.9% of 811 samples from other sources. Serogroup C1 was found in more than half of the samples and multiple serogroups were identified among isolates from the same samples and farms. The percentage of herd visits with at least one Salmonella isolate from cattle fecal samples increased with overall herd prevalence of fecal shedding. Only the three herds with an average fecal shedding prevalence of more than 15% had over 85% of weekly visits with at least one positive fecal sample. The prevalence of fecal shedding from different groups of cattle varied widely among herds showing that herds with infected cattle may be classified incorrectly if only one age group is tested. Testing environmental sample sources was more efficient for identifying infected premises than using individual cattle fecal samples.

Animals↗
PubMed2004

Representativity of a mid-lake surface water chemistry sample.

A mid-lake sample is the conventional sampling strategy used in lake chemistry monitoring programs. Hence, addressing the question of how representative a mid-lake sample is of in-lake conditions is important for interpreting changes in long-term monitoring programs. Our hypotheses were that; (i) the location of a sampling site within a lake will affect its representativity and (ii) a mid-lake sample could be considered representative of average surface water physico-chemistry. We focused on the surface water chemistry in 34 Swedish lakes. To obtain a wide diversity of lake types, the lakes were classified according to mean depth, water residence time, and three main ecoregions. Two sampling seasons were selected, representative of high and low biological activity and stratified and non-stratified conditions, respectively. Ten samples were collected in each lake. The mid-lake samples differed significantly from the nine remaining samples in less than 4% of the total number of two-sample t-tests performed. Samples collected close to lake inlets differed from the other samples more often than samples collected in the central parts of the lakes. We concluded that the location of a sampling site within a lake may affect the sample's representativity of lake water chemistry, and that a mid-lake surface water sample could be considered representative of surface water chemistry.

Environmental Monitoring↗
PubMed2002

Increased taxon sampling greatly reduces phylogenetic error.

Several authors have argued recently that extensive taxon sampling has a positive and important effect on the accuracy of phylogenetic estimates. However, other authors have argued that there is little benefit of extensive taxon sampling, and so phylogenetic problems can or should be reduced to a few exemplar taxa as a means of reducing the computational complexity of the phylogenetic analysis. In this paper we examined five aspects of study design that may have led to these different perspectives. First, we considered the measurement of phylogenetic error across a wide range of taxon sample sizes, and conclude that the expected error based on randomly selecting trees (which varies by taxon sample size) must be considered in evaluating error in studies of the effects of taxon sampling. Second, we addressed the scope of the phylogenetic problems defined by different samples of taxa, and argue that phylogenetic scope needs to be considered in evaluating the importance of taxon-sampling strategies. Third, we examined the claim that fast and simple tree searches are as effective as more thorough searches at finding near-optimal trees that minimize error. We show that a more complete search of tree space reduces phylogenetic error, especially as the taxon sample size increases. Fourth, we examined the effects of simple versus complex simulation models on taxonomic sampling studies. Although benefits of taxon sampling are apparent for all models, data generated under more complex models of evolution produce higher overall levels of error and show greater positive effects of increased taxon sampling. Fifth, we asked if different phylogenetic optimality criteria show different effects of taxon sampling. Although we found strong differences in effectiveness of different optimality criteria as a function of taxon sample size, increased taxon sampling improved the results from all the common optimality criteria. Nonetheless, the method that showed the lowest overall performance (minimum evolution) also showed the least improvement from increased taxon sampling. Taking each of these results into account re-enforces the conclusion that increased sampling of taxa is one of the most important ways to increase overall phylogenetic accuracy.

Likelihood Functions↗
PubMed1987

The development and evaluation of a hydrobromic acid-coated sampling tube for measuring occupational exposures to ethylene oxide.

A new sampling method has been developed for the measurement of ethylene oxide (EtO) exposures in the workplace. This sampling method uses a hydrobromic acid-coated charcoal tube to collect EtO as its 2-bromoethanol reaction product. Because 2-bromoethanol is less volatile and less reactive than EtO, improved sampling capacity and sample stability are observed with this method over the collection of EtO on untreated charcoal. Sample analysis is performed by gas chromatography with electron capture detection (GC/ECD) following desorption with dimethylformamide (DMF) and derivatization of the 2-bromoethanol reaction product with heptafluorobutyrylimidazole (HFBI). The direct analysis of 2-bromoethanol by GC/ECD was not reproducible and this effect was attributed to the presence of excess hydrobromic acid (HBr) in the sample. This matrix effect was eliminated by the formation of the heptafluorobutyrate ester, a water-insoluble derivative of 2-bromoethanol, which was extracted into iso-octane for analysis. This analytical scheme is very sensitive and was used to monitor test atmospheres of EtO at the 0.1 ppm level. An average recovery of 96% was obtained for short-term samples (15 minutes) collected from a 5-ppm test atmosphere at 23 degrees C and 80% relative humidity. Similar high recoveries were obtained for 4-hr samples collected at a sampling rate of 0.1 L/min from test atmospheres in the concentration range of 0.1 to 16 ppm EtO at high humidity (80%) and ambient temperature (22 degrees C to 25 degrees C). Samples collected under these same conditions and stored for a minimum of 2 weeks resulted in average recoveries that ranged from 84% to 101%. Average recoveries of 97% were obtained for 2-ppm air samples collected at low humidity with no storage; however, storage of these samples at 22 degrees C to 25 degrees C resulted in an approximate loss of 5% per week. A field comparison study of samples, that was obtained from a hospital sterilization facility, used the test method and the Qazi-Ketchum sample method and resulted in a correlation for paired samples of 0.99 over a concentration range of 0.3 to 7.0 ppm EtO. These results indicate that this sampling and analytical method is a convenient, accurate and reliable means of monitoring EtO exposures in the workplace.

Acids↗
PubMedDate not supplied

Detection of day blood filarial antigens by Og4C3 ELISA test using filter paper samples.

BACKGROUND: The launching of the global filariasis elimination programme has necessitated the use of highly sensitive and specific diagnostic tests. The Og4C3 monoclonal antibody-based ELISA test has been found to be highly specific and sensitive for the diagnosis of filariasis using night blood samples. However, it requires a serum sample which poses problems of transport and storage. Collection of blood samples on filter paper the will greatly circumvent these problems. Therefore, we evaluated the utility of the Og4C3 assay on filter paper samples collected during daytime. METHODS: Blood samples were collected from 63 microfilariae (mf) carriers during different time periods in a day on filter paper discs as well as venous blood for sera. The mf carriers and chronic (hydrocele n = 20; lymphoedema n = 120) and acute filariasis (adenolymphangitis n = 39) patients were from the endemic areas and the non-endemic normals were from Uthagamandalam district of Tamil Nadu, India. The filarial antigens in the samples were determined using the Og4C3 filarial antigen assay as per the manufacturer's instructions (JCU TrapBio, Australia). The sensitivity of the assay on sera and filter paper samples collected during night and also on filter paper samples collected during different time intervals of the day were compared with those of the membrane filtration technique, which was used as a gold standard. RESULTS: The geometric mean titre of the sera samples collected during night was 11 units/ml for non-endemic normals and 601.2 units/ml for mf carriers. The specificity of the assay on sera samples collected during night was 100% and the sensitivity 96.8% and the positive and negative values were 100% and 95.2%, respectively. The antigen positivity of the filter paper samples collected during morning hours was 93.3% while it was 76.6% and 86.7% for afternoon and evening hours. A significant association was observed between antigenaemia levels and mf density in the blood samples collected during the night. CONCLUSION: The samples collected on filter paper during the day can be used as an alternative to sera samples for detection of filarial antigens employing Og4C3 ELISA. Also, samples collected during morning hours yield a higher positivity. The assay when applied to serum samples will be useful especially when quantitative results are required.

Antibodies, Monoclonal↗
PubMed1992

Sample medication dispensing in a residency practice.

BACKGROUND: The distribution of sample medications to physicians by pharmaceutical manufacturers has been regulated by Congress and extensively critiqued in the medical literature. Manufacturers distributed 2.4 billion samples in 1988, yet there are no published reports on the clinical use of sample medications. METHODS: A 4-week descriptive study was conducted that catalogued the contents of a sample medication collection in a family practice residency model office, calculated the value of the sample collection (average wholesale price [AWP]), and monitored dispensing of medication samples. RESULTS: The collection initially contained 5546 samples with an AWP of $19,273. A total of 1012 samples worth $4154 was withdrawn from the collection during the study period. Patients received 548 of the sample packages in 105 dispensements ($2583), physicians or their families received 169 samples in 44 dispensements ($603), others received 26 samples in 6 dispensements ($152), and the destination of 269 samples ($816) was unknown. When a prescription was written at the time that a sample was dispensed, it was almost always for the same brand-name medication. CONCLUSIONS: Although a majority of medications dispensed were given to patients, approximately one third of the value of the medications withdrawn either went to physicians and their families or had an unknown destination. The high association of sample dispensing and simultaneous prescribing of the same brand-name drug supports the contention that sampling influences physician-prescribing habits. Further research should define how the availability of free sample medications affects physician-prescribing practices.

Adult↗
PubMed1998

Analysis of immunoregulatory cytokines in ocular fluid samples from patients with uveitis.

PURPOSE: To investigate the T-helper cell cytokine profiles in two well-defined clinical uveitis entities caused by an infectious mechanism. METHODS: Cytokines (interleukin [IL]-2, IL-4, IL-6, IL-10, and interferon [IFN]-gamma) were measured in ocular fluid samples obtained from patients with herpes simplex- or varicella-zoster virus-induced acute retinal necrosis (ARN; n = 17) and toxoplasma chorioretinitis (n = 27) using enzyme-linked immunosorbent assay techniques. The data were compared with data for 51 control samples taken during cataract surgery (n = 10), vitrectomy in diabetic retinopathy (n = 10), eye bank eyes (n = 10) and with samples from patients with "autoimmune" uveitis (n = 21). RESULTS: Interleukin-6 was detected in 44 of 51 control samples and 43 of 44 eyes of patients with uveitis. The highest levels in the control samples were detected in 9 of 10 vitreous samples from patients with diabetic retinopathy (mean, 648 pg/ml). In 8 of 10 samples taken from patients during cataract surgery and in 7 of 10 eye bank eyes the amount of IL-6 was significantly lower (mean, 10 pg/ml and 136 pg/ml, respectively). Interleukin-6 levels in patients with ARN (mean, 1436 pg/ml) were significantly higher than in those with toxoplasma chorioretinitis (mean, 272 pg/ml). Interleukin-2 was detected in one of the samples from patients with toxoplasma chorioretinitis (1105 pg/ml) and in three samples from the control subjects suffering from Fuchs' heterochromic anterior uveitis (mean, 752 pg/ml). No IL-4 (<2 pg/ml) was detected either in patient or control samples. Interferon-gamma could be detected in 7 of 17 ARN patients (range, 277-3483 pg/ml), in 13 of 27 samples from patients with toxoplasma chorioretinitis (range, 12-250 pg/ml), and in 1 of 21 of the samples from control subjects with uveitis (31 pg/ml) but was absent in nonuveitic control samples. Interleukin-10 was detected in 10 of 17 ARN patients (range, 29-3927 pg/ml), in 13 of 27 samples from patients with toxoplasma chorioretinitis (range, 4-67 pg/ml), and in only 3 of 51 control samples (6 pg/ml, 16 pg/ml, and 20 pg/ml). CONCLUSIONS: Various immunoregulatory cytokines (IL-6, IL-10, and IFN-gamma) were detected in ocular fluid samples from patients with uveitis. A separate role for either a T-helper type 1 or T-helper type 2 response in the pathogenesis of clinical uveitis could not be proven.

Animals↗
PubMed2006

Sampling plan for Diaphania spp. (Lepidoptera: Pyralidae) and for hymenopteran parasitoids on cucumber.

The objective of this work was to determine the best technique, sampling unit, and the number of samples to compose a conventional sampling plan for the cucurbit borers, Diaphania spp. (Lepidoptera: Pyralidae), and for hymenopteran parasitoids on cucumber. This research was carried out in 10 commercial cucumber crops fields from July to December 2000 in Tocantins, Minas Gerais State, Brazil (21 degrees 11' 15" S; 42 degrees 03' 45" W; altitude 363 m). The sampling methods studied were beating on a tray, direct counting of insects on the lower leaf surface, and whole leaf collection. Three sampling units also were studied: leaves from a branch located in the apical, median, or basal third of the canopy. The best sampling systems, which included the best technique and sampling unit, were determined based on the relative variance and the economic precision of the sampling. Once the best sampling systems were established, the numbers of samples to compose the conventional sampling plans were determined. The more suitable sampling system for the larvae of Diaphania spp. in cucumber plants was beating a leaf of the median third of the canopy on a plastic tray. One leaf must be sampled for every 50 plants in a crop. The more suitable sampling system for hymenopteran parasitoids in cucumber plants was to directly count the adults on one leaf of the median third of the canopy. One leaf must be sampled for every 74 plants in a crop.

Animals↗
PubMed1997

Analysis of the movement of line-like samples of variable length along the X-axis of a double TE104 and a single TE102 rectangular cavity

Movement of line-like samples with lengths from 5 to 50 mm along the x-axis of the double TE104 rectangular cavity has been analyzed. The observed dependencies of the EPR signal intensity versus sample position showed: (i) a sharp maximum for sample lengths from 5 to 20 mm; (ii) a plateau, over which the EPR signal intensity remained constant within experimental errors of 0.26-1.07%, for lengths from 30 to 40 mm; and (iii) a "sloping plateau," which could be approximated by the linear function (correlation, r = 0.98) for sample length 50 mm. Theoretical values of the experimentally observed dependencies of the intensity versus sample position were calculated using the modified sine-squared function and the correlation between observed and theoretically predicted dependencies is very good. The experimental dependence of the EPR signal intensity versus the sample length for samples situated at the same point in the cavity was nonlinear with a maximum for the 40-mm sample. The dependence of the EPR signal intensity upon the movement of a large cylindrical sample (o.d. 4 mm and length 100 mm) along the x-axis of the cavity was similar to that found for the 50-mm sample. However, an additional oscillating signal superimposed on the sloping plateau was observed. The presence of a large sample fixed in the complementary cavity of the double TE104 cavity caused an additional deformation of the signal intensity for a 30-mm sample which was moving in the first cavity. The primary effect was that the plateau was replaced by a region in which the intensity increased linearly with sample position, r = 0.99. Each of the above phenomena may be a source of significant errors in quantitative EPR spectroscopy. Cylindrical samples to be compared should be of identical length and internal diameter. Accurate and precise positioning of each sample in the microwave cavity is essential. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed2005

Liquid chromatography of polymers under limiting conditions of adsorption. IV. Sample recovery.

The high performance liquid chromatography of polymers under limiting conditions of adsorption (LC LCA) separates macromolecules, either according to their chemical structure or physical architecture, while molar mass effect is suppressed. A polymer sample is injected into an adsorption-active column flushed with an adsorption promoting eluent. The sample solvent is a strong solvent which prevents sample adsorption. As a result, macromolecules of sample elute within the zone of their original solvent to be discriminated from other, non-adsorbing polymer species, which elute in the exclusion mode. LC LCA sample recovery has been studied in detail for poly (methyl methacrylate)s using a bare silica gel column and an eluent comprised toluene (adsorli) and tetrahydrofuran (desorli). Sample solvent was tetrahydrofuran. It was found that a large part of injected sample may be fully retained within the LC LCA columns. The amount of retained polymer increases with decreasing packing pore size and with higher sample molar masses and, likely, also with the column diameter. The extent of full retention of sample does not depend of sample volume. An additional portion of the injected desorli sample solvent (a tandem injection) does not fully eliminate full retention of the sample fraction and the reduced recovery associated with it. The injected sample is retained along the entire LC LCA column. The reduced sample recovery restricts applicability of many LC LCA systems to oligomers and to discrimination of the non-adsorbing minor macromolecular components of complex polymer mixtures from the adsorbing major component(s). The full retention of sample molecules within columns may also complicate the application of other liquid chromatographic methods, which combine entropic and enthalpic retention mechanisms for separation of macromolecules.

Adsorption↗
PubMed2006

Comparison of different sampling techniques and enumeration methods for the isolation and quantification of Campylobacter spp. in raw retail chicken legs.

Comparable quantitative data of Campylobacter spp. on chicken products are a major data lack for quantitative risk assessment approaches. The objective of this study was to compare two different sampling techniques for the isolation and enumeration of Campylobacter spp. in chicken and to evaluate a suitable enumeration method comparing the most probable number (MPN) technique to the direct plating method. For this, 90 packages containing at least two raw chicken legs were examined for the comparison of sampling techniques, rinsing one leg and homogenizing 25 g of skin of the other leg of each package; both sample preparation types were examined by direct plating method and MPN technique in 40 out of 90 packages. Of the skin samples, 70% (63/90), and of the rinse samples, 77% (69/90), were Campylobacter-positive. Enumeration of Campylobacter spp. by direct plating revealed a median of log 4 cfu/leg surface in skin samples (S.D.=0.6) and a median of log 4.3 cfu/leg surface in rinse samples (S.D.=0.9) of the rinse samples; 73% (37/51) had higher numbers of Campylobacter spp. than the skin samples although the difference was not significant (p=0.08). The correlation coefficient of Campylobacter counts in skin and rinse samples was 0.43. The prevalence of Campylobacter spp. in rinse samples was 58% (23/40). In 5% (2/40) of the rinse samples, numbers of Campylobacter spp. could be detected only by the MPN technique due to the lower detection limit compared to the direct plating method. The MPN technique turned out to be unsuitable for the enumeration of Campylobacter spp. in skin samples because a layer formation on the top of the incubated MPN-tubes leads to irregular MPN results. Out of 80% (16/20) of the compared rinse samples, the direct plating detected higher numbers of Campylobacter spp., with a median count of log 4.2 cfu/leg surface (S.D.=1) compared the MPN technique where a median of log 4 cfu/leg surface (S.D.=1.1) was obtained. The difference was not significant (p=0.05). A highly positive correlation coefficient of 0.9 was observed between the direct plating and the MPN technique. Both sampling methods, rinsing the chicken leg and homogenizing the skin, are suitable for the detection and quantification of Campylobacter spp.; the direct plating method was superior to the MPN technique for enumerating Campylobacter spp. in raw chicken legs at retail level because enumeration is more rapid and less laborious.

Animals↗
PubMed2004

Sampling artifacts of acidity and ionic species in PM2.5.

Although sampling artifacts of acidity, ammonium, nitrate, and chloride in airborne particulate pollutants can be reduced by the use of denuders to absorb interfering gases, artifacts due to interparticle interactions still remain. In this study, the contribution of individual artifact reactions to particle evaporation and the effects of aerosol composition on the extents of sampling artifacts in PM2.5 were investigated. Samples were collected using a Harvard honeycomb denuder/filter-pack system at an urban site and a rural site in Hong Kong. The results show that the formation of artifacts can be categorized into two regimes: ammonium rich (AR) samples with a molar ratio [NH4+]/ [SO4(2-)] greater than 1.5 and ammonium poor (AP) samples with a molar ratio [NH4+]/[SO4(2-)] less than or equal to 1.5. The urban samples were all AR samples, and they were characterized by high nitrate and low in situ free acid concentrations. In contrast, the rural samples were all AP samples and they were characterized by low nitrate and high in situ free acid concentrations. We have developed a methodology to estimate the contribution of each artifact reaction to the sampling loss of nitrate, chloride, ammonium, and acidity. In the AR samples, the evaporation of HNO3 and HCl and concomitant evaporation of NH3 were the principal reactions in determining the extent of the sampling loss of nitrate and chloride. In the AP samples, the evaporation of HNO3 and HCl alone was the principal reaction instead, especially at high sampling loss. The in situ free acid concentration, a function of aerosol composition and ambient conditions, is a more useful parameter than strong acidity in understanding the sampling loss of acidity, nitrate, and chloride from the collected particles.

Aerosols↗
PubMed2003

Adequacy of mucosal sampling with the "two-bite" forceps technique: a prospective, randomized, blinded study.

BACKGROUND: Although the "two-bite" technique (obtaining 2 mucosal biopsy specimens with a single passage of the forceps) is used routinely, the adequacy of the second biopsy for histopathologic examination has not been evaluated. Our hypothesis was that the second sample will be inadequate for this purpose. The aim of this study was to prospectively assess the adequacy of mucosal biopsy specimens obtained with 3 different types of forceps with the two-bite technique. METHODS: Patients undergoing diagnostic EGD were prospectively enrolled in the study. In each patient, mucosal biopsy specimens were obtained as follows: 4 specimens with the two-bite technique in 2 separate passages of the forceps (one from the esophagus followed by one from the stomach, and one from the stomach followed by one from the esophagus, the order being chosen randomly) and 2 single-bite specimens from the same anatomic locations (esophagus and stomach). Each patient underwent the same biopsy sampling sequence with 3 different forceps. An experienced pathologist blinded to the sequence and technique of obtaining the samples and the forceps used evaluated the specimens for number submitted, integrity, and adequacy for histopathologic diagnosis and depth of the sample as assessed by the presence or absence of muscularis mucosae. RESULTS: A total of 288 mucosal samples were obtained from 16 patients. Of these, 192 were taken by using the two-bite technique. Thirty-five (18.2%) samples were missing when the two-bite technique was used compared with only 2 (2.1%) when the single bite technique was used (p < 0.05). Irrespective of the location from which the first mucosal sample was taken, a significantly greater number of first samples were lost (25%) compared with second samples (11.5%) (p < 0.05). The forceps without a spike was associated with significantly more missing samples than the spiked forceps (28.1% vs. 13.3%; p = 0.01). At histopathologic evaluation, there were no significant differences between first and second samples nor differences between samples taken with the two-bite and the single-bite techniques with regard to adequacy, integrity, and depth. With respect to histopathologic evaluation, there were no differences among the 3 types of forceps used in the study. CONCLUSIONS: Although the second mucosal sample obtained with the two-bite technique is adequate for histopathologic purposes, there is a significant risk of losing samples (the first one in particular) with this technique, and thus an increase in the probability of sampling error. This may be particularly true for forceps without a spike.

Adult↗
PubMed1996

Comparison of core sampling and pupal traps for monitoring immature stable flies and house flies (Diptera: Muscidae) in beef feedlot pens.

Core samples and cylindrical pupal traps were used to monitor immature stages of the stable fly, Stomoxys calcitrans (L.), and house fly, Musca domestica L., from 5 sample areas in beef feedlot pens: the feed apron-soil interface, the back fence, the side (pen dividing) fence, the mound, and the general lot. One feedlot was sampled during 1986, two feedlots were sampled in 1987, and three samples were taken at random from each sample area on each sample date. Core samples showed that both populations were highest from the feed apron sample area. Pupal traps tended to show the same result but differences between sample areas were not significant for immature stable flies. Both sampling methods generally indicated similar population trends of the 2 fly species over the season; correlation coefficients between the 2 sampling methods were generally significant but few correlations were strong and large divergences between population trends were present. Only approximately 69% of the total number of pupal traps placed were recovered; the loss of traps could have contributed to differences between the 2 sampling methods. Core sampling would be preferred if lower variance of samples is important; if collecting pupae of known age is important, then pupal traps may be useful if they are protected from trampling by cattle.

Animals↗
PubMed1992

Effect of sampling strategy on the false-negative rate for detection of selected subgingival species.

Subgingival plaque samples were obtained from the mesial surface of each tooth (maximum 28 samples per subject) in 62 subjects with prior evidence of destructive periodontal disease. The resulting 1596 samples were evaluated for their content of 14 selected taxa using a colony lift method and DNA probes. The present investigation compared the ability of 6 sampling strategies to detect a species known to be present in a subject as determined by the 28-site sampling procedure. On average, a species was not detected in 68% of the positive subjects if only the upper right first molar was sampled; 55% of subjects if both upper first molars were sampled; 36% of subjects if the 4 first molars were sampled; 28% of subjects if the 6 Ramfjord teeth were sampled; 60% of subjects if the deepest pocket was sampled and 25% of subjects if the 4 deepest pockets were sampled. The error rate was greatest for species that were infrequently detected in plaque samples such as Actinobacillus actinomycetemcomitans serotype b. This species was not detected in 49% of positive subjects, when the 6 Ramfjord teeth were sampled and 38% of subjects when the 4 deepest pockets were sampled. The data indicated that multiple plaque samples are needed to minimize false-negative rates.

Adolescent↗
PubMed2026

Evaluation of amplicon-based nanopore sequencing for foot-and-mouth disease viruses in clinical and environmental samples.

Foot-and-mouth disease (FMD) causes severe global economic loss, necessitating rapid viral characterization. Nanopore sequencing provides a simple, real-time workflow suitable for on-site outbreak response, addressing the limitations of conventional methods. In this study, we optimized a previously published amplicon-based protocol and used this method to characterize a diverse range of samples (vesicular fluid, epithelium, serum, nasal/oral swabs, and environmental samples) collected during FMD outbreaks in 2025 in the Republic of Korea. Of the 129 samples collected, we successfully recovered complete genomes from 37 samples and VP1 sequences from 85 samples. Amplifying the S-fragment in isolation and separately barcoding each pool of PCR amplicons markedly improved sequence recovery. Furthermore, sequencing success depended on viral load and sample type. Based on comparisons with real-time RT-PCR results, whole-genome sequence (WGS) recovery exceeded 77.3% at cycle threshold (Ct) values &#x2264;25 across all clinical samples. In the Ct > 30 category, serum samples yielded the highest WGS recovery rates (44.4%). This rate was markedly higher than the success rates observed for epithelium (20.0%) and nasal swabs (9.1%), whereas oral swabs and environmental samples failed to yield any sequences (0%). However, VP1 recovery from environmental samples reached 80% at Ct &#x2264; 30 (8/10), providing an approach to enable non-invasive monitoring. These findings demonstrate that amplicon-based nanopore sequencing is a practical method for the rapid generation of genomic data during FMD outbreaks.IMPORTANCEAlthough rapid detection and genomic data analysis are crucial for effective foot-and-mouth disease (FMD) control, the collection of these data can be challenging for certain sample types and impacted by reduced viral loads that result from nationwide FMD vaccination. This study provides a practical solution through large-scale evaluation of an optimized amplicon-based nanopore sequencing protocol to enhance the sequencing success rates for both clinical and environmental samples. Using a modified protocol to enhance genome recovery, we demonstrated that sequence data could be retrieved from diverse sample types (even with high real-time RT-PCR cycle threshold values). We identified serum as the most suitable sample, with environmental sample sequencing allowing for non-invasive monitoring during outbreaks. These results support the use of nanopore sequencing for rapid genomic analysis, particularly in outbreak responses, such as rapid surveillance, emergency vaccine selection, and epidemiological monitoring.

Foot-and-Mouth Disease↗