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PubMed1975

An evaluation of time-sample measures of behavior.

Continuous and time-sample measures of the in-seat behavior of a secretary were obtained. Measurement error, i.e., the extent to which the sample measures deviated from the continuous measure, was a function of the frequency of the sample measurements and the criterion used to score an example of the behavior. If the behavior had to be exhibited throughout the observational interval (whole-interval time sampling), there was a consistent underestimate of the continuous measure. If the behavior had to be exhibited only briefly within the observational interval (partial-interval time sampling), there was a consistent overestimate of the continuous measure. And, if the behavior had to be exhibited at the end of the observational interval (momentary time sampling), overestimations and underestimations of the continuous measure occurred about equally often. As expected, the more frequently the sample measures were made the closer was the agreement between the sample and continuous measures. Two conclusions concerning measurement error in interval time sampling were made. The first was that the error will be a function of the mean time per response. The second is that this error will not be consistent across experimental conditions.

Journal Article↗
PubMed1976

Differential sample response schedules in the acquisition of conditional discriminations by pigeons.

Pigeons were trained on four matching-to-sample tasks with various schedule requirements in effect on the sample key. Differential sample-schedule requirements (a differential-reinforcement-of-low-rates of 3 sec in the presence of one sample and a fixed-ratio 16 in the presence of the other) produced rapid rates of acquisition that did not differ across tasks. Nondifferential sample-schedule requirements (fixed-ratio 1, fixed-ratio 16 or a differential-reinforcement-of-low-rates of 3 sec in the presence of both samples) produced slower rates of acquisition, which depended on the difficulty of the discriminations between samples and between comparisons. Patterns of stimulus and position preferences were influenced both by the comparison stimuli in each task and by the sample-schedule requirements. Detailed analyses of acquisition revealed frequent instances of complete differential sample control of comparison responding at intermediate levels of overall "accuracy".

Journal Article↗
PubMed1984

Coding responses and the generalization of matching to sample in children.

Two experiments studied the conditions of stimulus control necessary for the generalization of relational matching to sample. Matching required the selection of comparison shapes rotated 90 degrees clockwise from the orientation of the corresponding sample. In Experiment 1, five children were taught to: (a) code the orientations of samples, (b) transform sample codings to account for the 90 degree rotation, and (c) repeat the transformed sample coding response to a comparison. High levels of generalization occurred with a set of novel stimuli for which stable sample-coding responses were initially available. In another novel set, where stable sample-coding responses were not initially available, low levels of generalized matching were recorded. Matching performance improved after stable coding responses were trained. In Experiment 2, two children and three adults were trained in a form of the matching task that produced poor generalization despite the presence of stable sample-coding responses. Retraining to modify the stimulus control exerted by these coding responses produced an immediate improvement in generalized matching to sample. Results suggest that the generalization of matching is dependent on structure of stimulus control that the component responses exert on each other.

Child, Preschool↗
PubMed1998

Reinforcer efficacy in a delayed matching-to-sample task.

Five domestic hens were exposed to a delayed matching-to-sample task. Conditions 1, 5, and 8 were variable-delay conditions in which five delays (0.25, 1, 2, 4, and 8 s) from the red or green sample to the presentation of the red and green comparison stimuli were presented a number of times during each session. In the fixed-delay condition (Condition 3), each delay was presented for 15 sessions under a Latin square design across birds. When improvements in accuracy across the variable-delay conditions are taken into account, the data were similar under both the variable and fixed delays. In Conditions 2, 4, 6, and 7 sample-reinforcer intervals were held at 8, 8, 4, and 2 s, respectively, while sample-choice intervals were varied within these during each session. With increasing sample-reinforcer interval, both initial discriminability (i.e., with sample-choice delay = 0) and rate of decrement in discriminability decreased. Although the former would be predicted if accuracy depends of the average sample-reinforcer interval, the latter would not. These data show that increasing the sample-choice interval had less effect on matching accuracy than increasing the sample-reinforcer interval did.

Animals↗
PubMed2003

Quantitative analyses of matching-to-sample performance.

Six pigeons performed a simultaneous matching-to-sample (MTS) task involving patterns of dots on a liquid-crystal display. Two samples and two comparisons differed in terms of the density of pixels visible through pecking keys mounted in front of the display. Selections of Comparison 1 after Sample 1, and of Comparison 2 after Sample 2, produced intermittent access to food, and errors always produced a time-out. The disparity between the samples and between the comparisons varied across sets of conditions. The ratio of food deliveries for the two correct responses varied over a wide range within each set of conditions, and one condition arranged extinction for correct responses following Sample 1. The quantitative models proposed by Davison and Tustin (1978), Alsop (1991), and Davison (1991) failed to predict performance in some extreme reinforcer-ratio conditions because comparison choice approached indifference (and strong position biases emerged) when the sample clearly signaled a low (or zero) rate of reinforcement. An alternative conceptualization of the reinforcement contingencies operating in MTS tasks is advanced and was supported by further analyses of the data. This model relates the differential responding between the comparisons following each sample to the differential reinforcement for correct responses following that sample.

Animals↗
PubMed2006

Intertrial sources of stimulus control and delayed matching-to-sample performance in humans.

Two experiments compared delayed matching-to-sample (DMTS) accuracy under 2 procedures in adults with mental retardation. In the trial-unique procedure, every trial in a session contained different stimuli. Thus, comparison stimuli that were correct on one trial were never incorrect on other trials in that session (or vice versa). In the 2-sample DMTS procedure, the same 2 comparison stimuli were presented on each trial, and their function changed quasi-randomly across trials conditional upon the sample stimulus. Across 2 experiments, 7 of 8 subjects showed the highest overall accuracy under the trial-unique procedure, and no subject showed consistently higher accuracy under the 2-sample procedure. Negative, exponential decay functions fit to logit p values showed that this difference was due largely to the steeper delay-mediated decline in sample control for the 2-sample procedure. Stimulus-control analyses indicated that, under the 2-sample procedure, the selection of the comparison stimulus on Trial N was often controlled by the comparison stimulus selection on Trial N-1 rather than the Trial-N sample stimulus. This source of competing stimulus control is not present in trial-unique procedures. Experiment 2 manipulated intertrial interval duration. There was a small but consistent increase in accuracy as a function of intertrial interval duration under the 2-sample procedure, but not under the trial-unique procedure.

Adult↗
PubMed2007

Two subgingival plaque-sampling strategies used with RNA probes.

BACKGROUND: The purpose of this study was to compare the results of microbiological RNA-probe analysis after subgingival plaque sampling applying two different strategies. METHODS: In 220 patients, clinical examinations were obtained prior to commencement of therapy for aggressive or generalized severe chronic periodontitis (n = 113), after combined mechanical and antibiotic anti-infective periodontal therapy (n = 43), or because of periodontal pockets despite adequate therapy (n = 64). Subgingival plaque samples were obtained from the three pockets with the deepest probing depths. Two sterile paper points were inserted simultaneously into the periodontal pockets. One paper point from each pocket was put into a separate transport vial; the second paper point was pooled (multiple site test [MT3]) with paper points from each of the two other sampling sites from the respective patient into a transport vial. The content of each vial was analyzed separately for Actinobacillus actinomycetemcomitans, Tannerella forsythensis, Porphyromonas gingivalis, and Treponema denticola (Td) with a commercially available RNA-probe test. RESULTS: For all tested pathogens, log-transformed numbers of bacteria were higher in pooled samples compared to the mean values for the separate samples (P < or =0.01). However, for Td only, statistically significant differences in frequency were seen between the separate samples and MT3. These findings were observed over all samples as well as after evaluation of subgroups separately. CONCLUSIONS: Pooling of plaque samples increased the bacterial counts per analysis compared to separate samples and thus may increase the probability of detecting existing pathogens. However, this observation only was statistically significant for the frequency of Td.

Aggregatibacter actinomycetemcomitans↗
PubMed2005

Precise Zn isotopic ratio measurements of human red blood cell and hair samples by multiple collector-ICP-mass spectrometry.

Precise 66Zn/64Zn and 68Zn/64Zn isotopic ratios of biochemical samples have been measured using multiple collector-ICP-mass spectrometry (MC-ICPMS). In order to eliminate the mass spectrometric interferences on Zn isotopes (e.g., 64Ni+ and 136Ba2+), we chemically purified the analyte using an ion chromatographic technique. The resulting precisions of the 66Zn/64Zn and 68Zn/64Zn ratio measurements were 0.05/1000 and 0.10/1000 (2SD), respectively, which were enough to detect the isotopic variation of Zn in nature. Red blood cell (RBC) samples were collected from five volunteers (four males and one female), including a series of 12 RBC samples from one person through monthly-based sampling over a year. These were analyzed to test possible seasonal changes and variations in 66Zn/64Zn and 68Zn/64Zn ratios among the individuals. The 66Zn/64Zn and 68Zn/64Zn ratios for a series of 12 RBC samples collected over a year were 0.43/1000 and 0.83/1000 higher than the values of highly purified Zn metal (JMC Zn), and no seasonal change could be found. The 66Zn/64Zn and 68Zn/64Zn ratios for RBC samples collected from five volunteers did not vary significantly. In order to investigate Zn isotopic heterogeneity in a human body, Zn isotopic ratios of a hair sample collected from one of the volunteers was also analyzed. The 66Zn/64Zn and 68Zn/64Zn ratios for the hair sample were 0.59/1000 and 1.14/1000 lower than the mean value of RBC samples. This result demonstrates that detectable isotopic fractionation occurs in the human body. The data obtained here suggest that the isotopic ratios of trace metals could provide new information about transportation of metal elements in vivo.

Chromatography, Ion Exchange↗
PubMed2000

Paper-based archiving of mammalian and plant samples for RNA analysis.

The ability to archive biological samples for subsequent nucleic acid analysis is essential for tissue specimens and forensic samples. FTA Card is a chemically treated filter paper designed for the collection and room temperature storage of biological samples for subsequent DNA analysis. Its usefulness for the preservation of biological samples for subsequent RNA analysis was tested. Here, we demonstrate that RNA in biological samples stored on FTA Cards is stable and can be used successfully for RT-PCR and northern blot analysis. RNA stability depends on the storage temperature and the type of biological specimen. RNA in mammalian cells stored on FTA Cards is stable for over one year at temperatures at or below -20 degrees C and for two to three months in samples stored at room temperature. For plant leaf, longer storage times (> 5 days) require temperatures at or below -70 degrees C following sample application. FTA Cards may constitute a method not only for convenient collection and storage of biological samples but also for rapid RT-PCR analysis of tissue and cell samples.

Animals↗
PubMed1999

Evaluation of sandwich ELISA galactomannan test in samples of positive LA test and positive aspergillus antibody.

OBJECTIVE: The detection of circulating Aspergillus galactomannan antigen is a useful tool for serodiagnosis of aspergillosis. However, the latex agglutination test for the detection of galactomannan is not completely reliable due to it's low sensitivity. The sandwich ELISA was developed to achieve high sensitivity. MATERIALS: The sandwich immunocapture ELISA was evaluated by testing 56 sero-positive and 56 sero-negative samples of circulating galactomannan detected by LA test retrospectively. RESULTS: Sixty of the samples were positive for galactomannan as measured by sandwich ELISA. Fifteen samples out of 56 samples negative by LA test were positive by ELISA and 4 samples out of 56 samples positive by LA test were negative by ELISA. Among 47 serum samples positive for anti-Aspergillus antibody, 14 samples were positive by ELISA. CONCLUSION: In conclusion, galactomannan may be detected in more samples of by the new sandwich ELISA than by LA test.

Antibodies, Fungal↗
PubMed2003

Detection of biofilm formation and nanobacteria under long-term cell culture conditions in serum samples of cattle, goats, cats, and dogs.

OBJECTIVE: To determine the prevalence of biofilm formation under long-term cell culture conditions in serum samples of dairy cattle, goats, cats, and dogs, and to determine whether there is an association between nanobacteria and biofilm formation. SAMPLE POPULATION: Serum samples of clinically normal animals (313 dairy cattle, 48 goats, 140 dogs, and 44 cats) and animals with various medical conditions (60 dogs and 116 cats). PROCEDURE: Serum was incubated under cell culture conditions and observed for biofilm formation by use of light microscopy, electron microscopy, and spectroscopy. A polymerase chain reaction assay was developed to identify 16S rRNA gene sequences of nanobacteria. RESULTS: Biofilm formation developed in serum samples of 304 of 313 (97%) cattle, 44 of 48 (92%) goats, 44 of 44 (100%) cats, and 126 of 140 (90%) dogs. Prevalence of serum samples with positive results for biofilm formation was not significantly different between cats or dogs with and without medical conditions associated with pathologic extraskeletal calcification processes. Scanning electron microscopy and spectroscopy of biofilm samples revealed small coccoid particles consisting mainly of calcium and phosphate. Polymerase chain reaction assay failed to amplify sequences of nanobacteria. CONCLUSIONS AND CLINICAL RELEVANCE: Under long-term cell culture conditions, biofilm made up of aggregates of calcium and phosphate crystals does form in serum samples of clinically normal dairy cattle, goats, cats, and dogs. Disease, however, does not predispose to biofilm formation in serum samples of dogs and cats. Our findings did not support the existence of nanobacteria in serum samples of cattle, goats, cats, and dogs.

Animals↗
PubMed2004

Evaluation of microbial culture of pooled fecal samples for detection of Mycobacterium avium subsp paratuberculosis in large dairy herds.

OBJECTIVE: To evaluate sensitivity of microbial culture of pooled fecal samples for detection of Mycobacterium avium subsp paratuberculosis (MAP) in large dairy herds and assess the use of the method for estimation of MAP prevalence. ANIMALS: 1,740 lactating cows from 29 dairy herds in California. PROCEDURE: Serum from each cow was tested by use of a commercial ELISA kit. Individual fecal samples were cultured and used to create pooled fecal samples (10 randomly selected fecal samples/pool; 6 pooled samples/herd). Sensitivity of MAP detection was compared between Herrold's egg yolk (HEY) agar and a new liquid culture method. Bayesian methods were used to estimate true prevalence of MAP-infected cows and herd sensitivity. RESULTS: Estimated sensitivity for pooled fecal samples among all herds was 0.69 (25 culture-positive pools/36 pools that were MAP positive). Sensitivity increased as the number of culture-positive samples in a pool increased. The HEY agar method detected more infected cows than the liquid culture method but had lower sensitivity for pooled fecal samples. Prevalence of MAP-infected cows was estimated to be 4% (95% probability interval, 2% to 6%) on the basis of culture of pooled fecal samples. Herd-level sensitivity estimate ranged from 90% to 100% and was dependent on prevalence in the population and the sensitivity for culture of pooled fecal samples. CONCLUSIONS AND CLINICAL RELEVANCE: Use of pooled fecal samples from 10 cows was a cost-effective tool for herd screening and may provide a good estimate of the percentage of MAP-infected cows in dairy herds with a low prevalence of MAP.

Animals↗
PubMed2004

Investigation of in vitro transdermal absorption of fentanyl from patches placed on skin samples obtained from various anatomic regions of dogs.

OBJECTIVE: To investigate in vitro transdermal absorption of fentanyl from patches through skin samples obtained from various anatomic regions of dogs. SAMPLE POPULATION: Skin samples from 5 Greyhounds. PROCEDURE: Skin samples from the dogs' thoracic, neck, and groin regions were collected postmortem and frozen. After samples were thawed, circular sections were cut and placed in Franz-type diffusion cells in a water bath (32 degrees C). A commercial fentanyl patch, attached to an acetate strip with a circular hole, was applied to each skin sample. Cellulose strips were used as control membranes. Samples of receptor fluid in the diffusion cells were collected at intervals for 48 hours, and fentanyl concentrations were analyzed by use of high-performance liquid chromatography. RESULTS: Mean+/-SD release rate of fentanyl from the patch, defined by its absorption rate through the non-rate-limiting cellulose membrane, was linear during the first 8 hours (2.01+/-0.05 microg/cm2 of cellulose membrane/h) and then decreased. Fentanyl passed through skin from the groin region at a faster rate and with a significantly shorter lag time, compared with findings in neck or thoracic skin samples. CONCLUSIONS AND CLINICAL RELEVANCE: In vitro, fentanyl from a patch was absorbed more quickly and to a greater extent through skin collected from the groin region of dogs, compared with skin samples from the thoracic and neck regions. Placement of fentanyl patches in the groin region of dogs may decrease the lag time to achieve analgesia perioperatively; however, in vivo studies are necessary to confirm these findings.

Administration, Cutaneous↗
PubMed2002

Assessment of test results when using a commercial enzyme-linked immunosorbent assay for diagnosis of paratuberculosis in repeated samples collected from adult dairy cattle.

OBJECTIVE: To determine the proportion of adult cattle that change test status when an ELISA for antibodies against Mycobacterium avium subsp paratuberculosis (MAP) is used to assay samples collected twice at variable intervals and to determine whether cows with an initial strong positive result were more likely to maintain positive status, compared with all cows with an initial positive result. DESIGN: Cross-sectional observational study. ANIMALS: 3,757 adult dairy cattle. PROCEDURE: Serum samples were obtained twice from cattle at intervals ranging from 77 to 600 days between collections. Samples were tested with an ELISA for detection of antibodies to MAP. RESULTS: Of 157 cattle with initial positive results (value for the sample divided by the value for positive-control serum [S/P] > or = 0.25), 62 (39.5%) had negative results for the second sample. Of 71 cattle with an initial S/P value > or = 0.40, 13 (18.3%) had a negative result (S/P < 0.25) for the second sample. Of 33 cattle with an initial S/P > or = 0.70, 3 (9.1%) had a negative result (S/P value < 0.25) for the second sample. Interval between collection of samples did not affect results. CONCLUSIONS AND CLINICAL RELEVANCE: Many cows changed ELISA status between samples collected at variable intervals. Cows with an initial high S/P value (> or = 0.70) were more likely to maintain positive status than cows classified as positive on the basis of cutoff values of > or = 0.25 or > or = 0.40. Veterinarians should expect variability in ELISA results when repeated testing of cattle is used as part of an MAP control program.

Animals↗
PubMed2002

Comparison of glucose concentrations in blood samples obtained with a marginal ear vein nick technique versus from a peripheral vein in healthy cats and cats with diabetes mellitus.

OBJECTIVE: To compare blood glucose (BG) concentrations measured with a portable blood glucose meter in blood samples obtained with a marginal ear vein (MEV) nick technique, from a peripheral venous catheter, and by direct venipuncture in healthy cats and cats with diabetes mellitus. DESIGN: Prospective study. ANIMALS: 1 0 healthy cats and 11 cats with diabetes mellitus. Procedure-On day 1, blood samples were collected every hour for 10 hours by the MEV nick technique and from a peripheral venous catheter. On day 2, blood samples were collected every hour for 10 hours by the MEV nick technique and by direct venipuncture of the medial saphenous vein. RESULTS: For all cats, mean BG concentration for samples collected by the MEV nick technique was not significantly different from mean concentration for samples obtained from the peripheral venous catheter. For healthy cats, mean BG concentration for samples collected by the MEV nick technique was not significantly different from mean concentration for samples obtained by direct venipuncture. For cats with diabetes mellitus, mean BG concentration for samples collected by the MEV nick technique was significantly different from mean concentration for samples obtained by direct venipuncture; however, for the range of concentrations examined, this difference was not clinically important. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that for the range of concentrations examined, the MEV nick technique is a reasonable alternative to venous blood collection for serial measurement of BG concentrations in cats.

Animals↗
PubMed1997

Omasal sampling technique for assessing fermentative digestion in the forestomach of dairy cows.

A procedure allowing digesta sampling from the omasum via a ruminal cannula without repeated entry into the omasum was developed. The sampling system consisted of a device inserted into the omasum via the ruminal cannula, a tube connecting the device to the ruminal cannula, and a single compressor/vacuum pump. Eight cows given ad libitum access to a total mixed diet were used in a crossover design to evaluate the effects of the sampling system on digestive activity, animal performance, and animal behavior. Results indicated that the omasal sampling system has minimal effect on normal digestive and productive functions of high-producing dairy cows. Dry matter intake was reduced (24.0 vs 21.8 kg/d; P < .02) and seemed related more to the sampling procedures than to the device in the omasum. Observations of animal behavior indicated that cows with the sampling device were similar to control cows, although rumination and total chewing times were reduced slightly. The composition of digesta samples was biased toward an over-abundance of the liquid phase, but using a double-marker system to calculate digesta flow resulted in fairly small coefficients of variation for measurements of ruminal digestion variables. This technique may prove useful for partitioning digestion between the fermentative portion of the forestomach and the lower gastrointestinal tract. The omasal sampling procedure requires less surgical intervention than the traditional methods using abomasal or duodenal cannulas as sampling sites to study forestomach digestion and avoids potentially confounding endogenous secretions of the abomasum.

Amino Acids↗
PubMed1999

Technical note: a device for obtaining time-integrated samples of ruminal fluid.

A device was adapted to allow for time-integrated sampling of fluid from the rumen via a cannula. The sampler consisted of a cup-shaped ceramic filter positioned in the ventral rumen of a cannulated cow and attached to a tube through which fluid entering the filter was removed continuously using a peristaltic pump. Rate of ruminal fluid removal using the device was monitored over two 36-h periods (at 6-h intervals) and was not affected (P > .05) by time, indicating that the system was not susceptible to clogging during this period. Two cows having ad libitum access to a totally mixed ration were used in a split-block design to evaluate the utility of the system for obtaining time-integrated samples of ruminal fluid. Ruminal fluid VFA concentration and pattern in samples collected in two replicated 8-h periods by the time-integrated sampler (at 1-h intervals) were compared with composite samples collected using a conventional suction-strainer device (at 30-min intervals). Each 8-h collection period started 2 h before or 6 h after feeding. Results indicated that total VFA concentration was not affected (P > .05) by the sampling method. Volatile fatty acid patterns were likewise unaffected (P > .05) except that acetate was 2.5% higher (P < .05) in samples collected 2 h before feeding and valerate was 5% higher (P < .05) in samples collected 6 h after feeding by the suction-strainer device. Although significant, these differences were not considered physiologically important. We concluded that use of the ceramic filter improved the sampling of ruminal fluid by simplifying the technique and allowing time-integrated samples to be obtained.

Animals↗
PubMed1989

The suitability of carbamazepine as a single-sample probe of human mixed function oxidase activity.

1. Carbamazepine concentrations measured in plasma and plasma ultrafiltrates by fluorescence polarization immunoassay (f.p.i.a.) from 0 to 48 h post-dose were used to calculate CL, V, clearance of plasma unbound drug (CLunb), Vunb; mean (+/- SD) values for these were: 0.017 l/kg/h (+/- 0.004), 1.05 l/kg (+/- 0.14), 0.058 l/h/kg (+/- 0.012), and 4.28 l/kg (+/- 0.41), respectively. 2. A single-dose, single-sample procedure for estimating carbamazepine oral clearance was evaluated with a view to using carbamazepine as a probe in screening for host factor influences on human drug metabolism. Single sample estimates of carbamazepine clearance (CL) were closest to multiple sample values for carbamazepine clearance (CL) when blood samples were collected 48 h after carbamazepine ingestion. This was the case for plasma total carbamazepine and plasma unbound carbamazepine. 3. A value of 1.1 l/kg was used for V in calculating all single sample estimates of clearance (CL), and a value of 4.3 l/kg was used to calculate single sample estimates of clearance of plasma unbound drug (CLunb). The mean prediction error (MPE) was negatively biased for CL and CLunb values calculated from single carbamazepine concentrations in samples collected at 24, 36, and 48 h post-dose. MPE was less than 5% errant for CL and less than 1% errant for CLunb when those parameters were calculated from 48 h concentrations of plasma total carbamazepine or plasma unbound carbamazepine, respectively. Root mean squared error (r.m.s.e.) was lost lowest when 48 h post-dose samples were used for single-sample clearance estimates.

Administration, Oral↗