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PubMed2002

An investigation of new toxicity test method performance in validation studies: 2. Comparison of three measures of toxicity test performance.

An area that requires further research is how best to measure test method performance in validation studies and how to set criteria that should be used to judge the adequacy of this performance. The studies reported here were designed to begin an investigation of these questions. Computer simulations were used to generate data sets similar to those that might be obtained from a large validation study. These data were then analysed using three procedures including determination of the 95% prediction interval (PI), calculation of Pearson's correlation coefficient and calculation of the contingent probability statistics (CPS), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The results of this work suggest that of the three approaches examined, quantitative measurements with calculation of the 95% PI provide the most information to allow discrimination between the performance of several different NTMs. The results also suggest that dividing data sets into positive and negative toxicity classifications followed by the calculation of CPS leads to considerable information loss. This loss of information may be so significant that it is not possible in certain circumstances to distinguish between NTMs that are adequate and those that are not.

Predictive Value of Tests↗

PubMed2001

Performance of a commercial immunoassay for detection and differentiation of periodontal marker bacteria: analysis of immunochemical performance with clinical samples.

BACKGROUND: We employed a commercial immunoassay for simultaneous detection and differentiation of marker bacteria Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia and reassessed the immunochemical performance of the assay. METHODS: We compared the analytical performance of the immunoassay in our study of clinical samples from 249 periodontal patients in 2 private periodontal practices with the previously reported analytical performance of the same immunoassay. We also compared immunoassay measurements of the marker bacteria in clinical samples with values obtained in other studies by direct culture of the same organisms. RESULTS: The assay produced 3 times more high-end readings than reported previously. We also reassessed and revised previously published calibration curves for the immunoassay. The immunoassay provided measurements of the marker bacteria in clinical samples from our patients that were comparable to and consistent with measurements of the same bacteria by direct culture in other studies. CONCLUSIONS: We ascribe the increased sensitivity of the immunoassay in our study to: 1) a more standardized and vigorous sample dispersion that improves release of particulate and soluble antigens from dental plaque biofilm, and 2) better visualization of the reaction product of the enzyme-linked immunoassay. High-technology assays, such as diagnostic immunoassays, have a significant potential for future development in dental diagnosis, because they simplify detection and measurement of biologically important markers such as specific bacteria in clinical samples. Commercial assays also have an important potential for standardization of clinical measurements of biological markers.

Aggregatibacter actinomycetemcomitans↗

PubMed1995

Influence of high-starch vs high-fiber energy supplements on performance of stocker cattle grazing wheat pasture and subsequent feedlot performance.

A 3-yr study was conducted to determine effects of high-starch (HS) or high-fiber (HF) energy supplements on performance of fall-weaned steer calves (n = 192, Exp. 1 and 2; n = 84, Exp. 3) grazing winter wheat pasture (Triticum aestivum variety 2157) and subsequent feedlot performance. The steers received 1) no supplement (CL) other than free-choice access to a commercial mineral mixture or 2) were hand-fed 6 d/wk either a corn-based HS supplement, or 3) a soybean hull/wheat middling-based HF supplement. In Exp. 1 (1989-1990), a fourth treatment provided ad libitum access to the HF supplement (SFHF). Supplements contained 88 mg of monensin/kg and the combination of ionophore, minerals and salt (8%) was used to limit intake of the SFHF supplement. Target level of daily consumption of all supplements was .75% of mean BW. Stocking density was increased by 33% (i.e., from 1.24 to 1.65 steers/ha) in Exp. 1 and 3, and by 22 to 44% in Exp. 2 when supplements were fed. Subsequent to grazing wheat pasture in Exp. 2 and 3, feedlot performance and carcass quality (Exp. 2 only) of the cattle were measured. Over the 3-yr period (pooled analysis), mean daily supplement consumption was .65% BW. Daily gains were increased (P < .001) .15 kg by supplementation and were .92, 1.06, and 1.08 kg for CL, HS, and HF, respectively. Daily gains were not influenced (P > .45) by type of energy supplement. Mean supplement conversions (kilograms asfed.kilogram of increased gain-1.hectare-1) were 5.4 for HS and 5.0 for HF and did not differ (P > .95). Subsequent feedlot daily gain was decreased .09 kg (P < .05) by supplementation in Exp. 2 but not in Exp. 3 (P > .80). This supplementation program for growing cattle on wheat pasture allowed stocking density to be increased by approximately one-third and increased daily gains by .15 kg.

Animal Feed↗

PubMed2002

Influence of rumen protein degradability and supplementation frequency on performance and nitrogen use in ruminants consuming low-quality forage: cow performance and efficiency of nitrogen use in wethers.

Two studies were conducted to determine the influence of CP degradability and supplementation frequency (SF) on ruminant performance and N efficiency. Treatments included an unsupplemented control (CON) and degradable intake protein (DIP; 82% of CP) or undegradable intake protein (UIP; 60% of CP) provided daily, every 3 d, or every 6 d. Seven wethers (36+/-1 kg BW) were used in the digestibility study with DIP and UIP treatments formulated to meet CP requirements. Eighty-four Angus x Hereford cows (512+/-42 kg BW) in the last third of gestation were used for the performance study. The DIP treatments were calculated to provide 100% of the DIP requirement and UIP treatments were provided on an isonitrogenous basis compared with DIP. Basal diets consisted of low-quality (5% CP) meadow hay. Forage DMI and N intake by lambs decreased (P < 0.05) linearly as SF decreased. Additionally, DMI, OM intake, N retention, N digestibility, and digested N retained were greater (P < 0.01) for supplemented wethers than for controls with no difference due to crude protein degradability. Nitrogen balance, DMI, and OM intake decreased linearly (P < 0.05) as SF decreased. Plasma urea (PU; mM) was measured over a 6-d period and supplemented lambs had increased (P < 0.01) PU compared with CON. Plasma urea linearly decreased (P < 0.01) as SF decreased. Pre- and postcalving (within 14 d and 24 h of calving, respectively) cow weight and body condition score change were more positive (P < 0.05) for supplemented groups than for controls. Results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by ruminants consuming low-quality forage without adversely affecting N efficiency and animal performance, even when provided as infrequently as once every 6 d.

Animals↗

PubMed2004

Performance of mouse lines divergently selected for heat loss when exposed to different environmental temperatures. I. Reproductive performance, pup survival, and metabolic hormones.

Mouse populations differing in metabolic rate have been developed through selection for high (MH) and low (ML) heat loss, along with the unselected controls (MC). Objectives of the study were to compare the MH, ML, and MC lines for reproductive performance, pup survival, and metabolic hormones when reared at 12, 22, and 31 degrees C, and to search for line x environment interactions. Conception and litter size were recorded on the parent generation mice introduced to the environments at 11 wk of age and bred after a 3-wk acclimatization period. Survival of pups (preweaning to 3 wk; postweaning from 3 to 9 wk of age) was measured with continuous exposure in the designated environment from birth to the time of measurement. Corticosterone, triiodothyronine (T3), and thyroxine (T4) serum concentrations were measured on the parent generation after producing litters and on the pup generation at 9 wk. No line x environment interaction was detected for conception rate, preweaning mortality, postweaning survival, pup weaning weight, or body temperature. There were no differences in conception rate among lines and environments. Environments affected survival of pups, but there were no line differences. Rectal body temperatures were greater for MH than ML mice, and MC mice were intermediate; body temperature of mice did not differ among the environments. Lines differed significantly in litter size only in the 22 degrees C environment. No significant line differences were found for serum corticosterone or serum T3 or T4. Line x environment interaction was detected only for litter size and for serum corticosterone concentration in dams. Contrary to the other two lines, ML dam performance relative to MH and MC was not affected negatively by either of the thermal environments. Results from this study do not raise concern that selection to decrease maintenance requirements will produce livestock with any greater liability to cope and perform under an array of environmental temperatures.

Animals↗

PubMed1999

Cytologic examination of specimens obtained by means of tracheal washes performed before and after high-speed treadmill exercise in horses with a history of poor performance.

OBJECTIVE: To evaluate results of cytologic examination of specimens obtained by means of tracheal washes (TW) in 42 horses with a history of poor performance. DESIGN: Cross-sectional case series. ANIMALS: 42 horses with a history of poor performance. PROCEDURE: A TW was performed via endoscopy before and after horses exercised on a high-speed treadmill, and specimens were evaluated microscopically and graded. RESULTS: Ten (24%) horses were considered to be clinically normal before and after exercise. Pulmonary hemorrhage was diagnosed in 8 (19%) horses. One horse had evidence of exercise-induced pulmonary hemorrhage (EIPH) before exercise and pulmonary hemorrhage and allergic or inflammatory airway disease (IAD) after exercise. Five (12%) horses had IAD, and 1 had IAD and pulmonary hemorrhage after exercise. Seven (17%) horses had evidence of EIPH and IAD in both specimens. Four (10%) horses with EIPH had an increase in the proportion of hemosiderophages in the specimen obtained after exercise. Specimens obtained before exercise in 6 (14%) horses were not representative of the respiratory tract and could not be compared with specimens obtained after exercise. CLINICAL IMPLICATIONS: Interpretation of TW specimens obtained before and after exercise differed for only 5 of 36 (14%) horses. Specimens obtained after exercise were more likely to reveal airway disease. All specimens obtained after exercise adequately represented the respiratory tract, whereas 6 specimens obtained before exercise did not. Specimens obtained after exercise contained more airway secretions and had less cytologic evidence of pharyngeal contamination. Therefore, we recommend that TW samples be obtained after exercise in horses.

Animals↗

PubMed2003

Exercise performance and oxygen uptake efficiency slope in obese children performing standardized exercise.

Oxygen uptake efficiency slope (OUES) is an index meant to provide an objective measure of cardiopulmonary function at submaximal exercise. The aim was to study the exercise performance and OUES in obese children performing standardized exercise. Sixty children aged 6-17 years performed incremental treadmill exercise test. They were divided into two groups matched by age, sex and height: thirty obese subjects (15 girls/15 boys; BMI = 27.4+/-1.7 m x kg(-2)) and 30 controls (BMI = 18.8+/-1.0 m x kg(-2)). Perceived exertion was assessed by means of CR-10 Borg scale. The duration of the exercise for the obese children was significantly shorter than for controls (p = 0.010) but obese children had greater absolute values for oxygen uptake (VO2 peak mL x min(-1) = 1907+/-249 vs. 1495+/-208; p = 0.013) which, adjusted for body mass, decreased significantly (VO2/kg mL x min(-1) x kg(-1) = 29.2+/-1.4 vs. 33.6+/-1.3; p < 0.001). OUES correlated strongly with VO2 peak (r = 0.91) and oxygen pulse (r = 0.80), as well as with anthropometric variables height (r = 0.88) and age (r = 0.83). Extremely high correlation was found between OUES calculated for 100% of exercise duration and OUES at the anaerobic threshold (r = 0.979; p < 0.001). No significant differences were found between the studied groups concerning the absolute values of OUES. Obese children rated perceived exertion significantly higher than controls (Borg score 6.2+/-0.4 vs. 5.2+/-0.4; p = 0.001). In conclusion, the absolute metabolic cost of exercise and perceived exertion were higher in the obesity group. OUES is an objective measure of cardiopulmonary reserve that doesn't require a maximal effort but it is considerably dependent on anthropometric variables which impedes its interpretation as exercise index in childhood.

Adolescent↗

PubMed2003

Longitudinal performance of infants with cerebral palsy on the Test of Infant Motor Performance and on the Alberta Infant Motor Scale.

Understanding the natural history of development in children with cerebral palsy (CP) is important for studying the consequences of early intervention. The purpose of this paper is to present results on the Test of Infant Motor Performance (TIMP) from 0-4 months of age and on the Alberta Infant Motor Scale (AIMS) from 3 to 12 months of age in a group of infants later diagnosed as having CP. Ages at which infants with CP were first recognized as having delayed motor performance on each instrument and the stability of performance over time are presented. Clinical implications for using both instruments are discussed.

Age Distribution↗

PubMed2004

Abdominal Muscle Activity While Performing Trunk-Flexion Exercises Using the Ab Roller, ABslide, FitBall, and Conventionally Performed Trunk Curls.

OBJECTIVE: To compare the surface electromyographic activity of the abdominal musculature and rectus femoris (RF) muscle during trunk-flexion exercises using 3 abdominal exercise devices (Ab Roller, ABslide, and FitBall) and the traditional trunk curl. DESIGN AND SETTING: Each subject performed approximately 15 repetitions for each exercise condition. A repeated-measures, one-way multivariate analysis of variance was used to compare the mean integrated electric activity value for each muscle during each exercise condition. SUBJECTS: A total of 10 male and 13 female collegiate undergraduate students. MEASUREMENTS: Surface electromyographic activity was recorded for the upper rectus abdominis (URA), lower rectus abdominis (LRA), external oblique (EO), and RF during 5 consecutive repetitions of each exercise bout. The signal was amplified by a factor of 1000, rectified, and integrated. These integrated values were then divided by the time value for each exercise to give the mean integrated electromyography value. RESULTS: A significant difference existed among exercise conditions for the RF (P <.0001), with the ABslide and the FitBall having greater electric activity than the other exercise conditions. Activity was significantly different (P <.0009) for the URA, with the ABslide having the least electric activity. For the EO, exercising with the ABslide produced significantly greater electric activity (P <.0001) than all other exercise conditions. No significant difference was found across exercise conditions for the LRA (P <.051). CONCLUSIONS: Performing abdominal exercises with the Ab Roller, ABslide, and FitBall did not elicit greater activity of the URA and LRA than performing traditional trunk curls. Use of the ABslide elicited greater EO activity and significantly less URA activity than the other 3 modes. Both the ABslide and FitBall resulted in greater involvement of the hip flexors, an undesirable feature of abdominal exercises.

Journal Article↗

PubMed2006

The quality of laboratory testing today: an assessment of sigma metrics for analytic quality using performance data from proficiency testing surveys and the CLIA criteria for acceptable performance.

To assess the analytic quality of laboratory testing in the United States, we obtained proficiency testing survey results from several national programs that comply with Clinical Laboratory Improvement Amendments (CLIA) regulations. We studied regulated tests (cholesterol, glucose, calcium, fibrinogen, and prothrombin time) and nonregulated tests (international normalized ratio [INR], glycohemoglobin, and prostate-specific antigen [PSA]). Quality was assessed on the sigma scale with a benchmark for minimum process performance of 3 sigma and a goal for world-class quality of 6 sigma. Based on the CLIA criteria for acceptable performance in proficiency testing (allowable total errors [TEa]), the national quality of cholesterol testing (TEa = 10%) estimated sigma values as 2.9 to 3.0; glucose (TEa = 10%), 2.9 to 3.3; calcium (TEa = 1.0 mg/dL), 2.8 to 3.0; prothrombin time (TEa = 15%), 1.8; INR (TEa = 20%), 2.4 to 3.5; fibrinogen (TEa = 20%), 1.8 to 3.2; glycohemoglobin (TEa = 10%), 1.9 to 2.6; and PSA (TEa = 10%), 1.2 to 1.8. The analytic quality of laboratory tests requires improvement in measurement performance and more intensive quality control monitoring than the CLIA minimum of 2 levels per day.

Benchmarking↗

PubMed1986

Trends of performance in Arkansas cooperative beef-bull performance tests from 1962 through 1982.

Individual records of performance of 2787 bulls in cooperative beef-bull performance tests from 1962 through 1982 were analyzed to determine trends in final weight, average daily gain, daily feed consumption and gross feed efficiency. Data from Angus, Polled Hereford, Charolais, Hereford and Santa Gertrudis breeds were analyzed separately. Performance-test procedures and the ration fed remained the same in all tests. Least-squares means by year, adjusted for location of test, initial weight, initial age and initial condition score, were regressed on time to determine average yearly change in the traits. Yearly changes for Angus, Polled Hereford, Charolais, Hereford and Santa Gertrudis breeds in final weight were 3.3, 1.6, 3.3, 2.5, and 2.6 kg, respectively; in average daily gain and yearly changes were .02, .01, .02, .02, and .02 kg, respectively; in daily feed consumption the yearly changes were .08, .03, .09, and .04 kg, respectively; and in feed per kg gain the yearly changes were -.08, -.04, -.05, -.03, and -.07 kg, respectively. Because the test procedures were the same in all years, these trends represent genetic progress made by the Arkansas beef industry toward faster-gaining, more efficient cattle.

Animals↗

PubMed1979

[Studies on the performance of the dental air turbine handpieces. (Part 1). Air pressure and bur length to be influenced over the rotational performance of the air bearing type handpieces (author's transl)].

Air turbine handpieces are used as the dental cutting instruments for the clinical use and many appliances. But, there are no studies on the performance of air turbine handpieces. So, this paper shows the rotational performance of air turbine handpieces which are influenced over the supplying air pressure and cutting bur length. Experimentally used air turbine handpieces is air bearing type and it's set up air pressure to be supplied is 3.5 kg/cm2. So, in this experiments, the range of air pressure is 1.8 approximately 3.5 kg/cm2, which is established five stages. And the bur length of the rotational parts is 5 approximately 9 mm with five steps. As the results, the rotational performance of air handpieces are influenced over these factors of the air pressure and the bur length. And air pressure to be supplied are influenced to be not only over the rotational speed but the load for the putting a stop to the revolutions.

Air Pressure↗

PubMed1979

Knowledge of performance, skill level and performance on the balance beam.

Knowledge of performance (KP) using video-tape replay (VTR) was given to a group of girls aged 12--13, n = 8, learning to perform a beginning balance beam routine. A control group (n = 8) was taught utilizing conventional information feedback. Performance was assessed by three U.S. Federation Gymnastic judges after four weeks and again after six weeks. All S's in the experimental group were judged to be at the associative learning stage. The data were analyzed using a mixed repeated measures design with one between and one within subjects variables. A significant treatment effect (F = 48.7, alpha less than or equal to .01) and treatment by group interaction (F = 19.21, alpha less than or equal to .01) resulted. The experimental group was responsible for the bulk of the significance and it was therefore concluded th KP via VTP for S's in the associative learning stage was beneficial.

Adolescent↗

PubMed1981

[Studies on the performance of the dental air turbine handpieces. (Part 4) Analysis of the rotational performance of air turbine handpieces (N = N0 - CvFv gamma (author's transl)].

By the introduction of the diamond instruments and carbide burs measurably improved the quality and ease of cavity preparation, the several kinds of the air turbine handpieces, that is, standard type, torque type and miniature type air handpieces have been recently developed. In this paper, the performance tests of these air turbine handpieces have been carried out, and obtained the relations are indicated speeds and the vertical and horizontal loads or torque using the test bur. These relations are indicated by the logarithmic expressions, N = N0 - CvFv gamma, where N is the rotational speed of the air turbine handpieces during rotation, N0 is the free rotational speed of the air turbine handpieces, Fv is the vertical loads on the tests burs and Cv and gamma is the experimental constants. And then, the maximum performed work or the air turbine handpieces is presented by the expression as follows. W max = pimicrod/60(1/Cv)1/ gamma gamma (N0/gamma + 1)(1 + gamma)/gamma And we proposed the formula to be calculated for the performance ability of the air turbine handpieces.

Dental High-Speed Equipment↗

PubMed1981

[Studies on the performance of the dental air turbine handpieces. (Part 5) Rotational performance of various kinds of dental air turbine handpieces (N = N0--CvFv gamma) (author's transl)].

Making research on the rotational performance of the dental air turbine handpieces widely used for dental cutting instruments, we investigated with the relation between rotational speed and load on many kinds of dental handpieces used for clinical divisions and with the applications of the theoretical equations to have be shown in the previous report. And then we have the investigation on these properties. Dental handpieces to measured with these properties were classified the four types, standard types, torque type, miniature type and air bearing type. And we applied the experimental equations to these experimental values and determined the rotational coefficients, gamma and Cv. The rotational speed N and normal force Fv, which occurred the maximum work of air turbine handpieces, were calculated with our analysis and then these values of N and Fv were compared with the experimental results. These results, that is, experimental and calculated values have a good agreement and the development of the theoretical approach is useful for the estimation of the rotational performance. And we examined the possibility of rotational performance's estimation with the process of simple experiment on these air turbine handpieces.

Dental High-Speed Equipment↗

PubMed1976

[Psychophysiological studies of EEG, operational performance and the dynamics of vigilance regulation. I. The EEG during performance of Brickenkamp's attention-concentration test (test d 2) (author's transl)].

During the performance of the d 2 test developed by Brickenkamp (standardized test of attention and concentration), occipital EEG activity was registered telemetrically in 10 male students aged 25 to 32 years. Simultaneously, the pencil markings performed by the subjects, indicating the time course of their pattern recognition and discrimination, were recorded by means of a piezo-electrical transducer. The EEG behavior during test performance was evaluated by serial spectral analysis. The analysis of the EEG parameters derived from it (total power, absolute and relative alpha-power) showed that there is a relationship between these EEG measures reflecting the regulation of cortical vigilance and the error rate in the concentration test. While subjects with low error rate present a heightening of cortical arousal focused in the right occipital area, subjects with higher error rate tend to have a higher degree of general cortical activation.

Adult↗

PubMed1996

Isokinetic performance capacity of trunk muscles. Part I: The effect of repetition on measurement of isokinetic performance capacity of trunk muscles among healthy controls and two different groups of low-back pain patients.

The aim of this investigation was to assess the reproducibility of the isokinetic trunk muscle performance measurement among patients with different degrees of low-back pain. Twenty-two healthy volunteers, 20 patients with mild and 18 patients with severe low-back pain participated in isokinetic measurements. Lidoback isokinetic dynamometer was used. The measurements were performed with the subjects standing, using velocities of 60, 90 and 120 degrees/second. Five repetitions were performed at each velocity. All subjects were tested three times with a 1-week interval between the tests. Peak torque, average peak torque, coefficient of variation, total work done and peak torque to body weight ratio were calculated for each velocity for both flexion and extension. The results showed that in every measurement peak torque, average peak torque, peak torque to body weight ratio and total work done correlated with each other very strongly both in flexion and extension (r > or = 0.9). The average peak torques increased in further measurements. The change had a strong correlation with the severity of the back problem, which was evaluated by means of the Oswestry disability index. The critical value was found to be 20% in the Oswestry index: values above this meant big changes between measurements and values below this meant small changes between measurements.

Adult↗

PubMed2002

Talking while performing a task: a better attentional performance in patients with closed head injury?

This study explored the potentially beneficial effect of explicit verbalization on the attentional performance in patients with closed head injury (CHI) in both distracting and nondistracting environments. Ten patients with CHI and 10 normal controls were recruited. The findings indicated that in the absence of distractors, the two groups did not differ significantly on the total actual time of off-task behaviour. When distractors were present, the patients performed worse than their controls; whereas verbalization tended to reduce total actual time of off-task behaviour in patients more than normal controls (z=1.965, p=.049), the controls were at ceiling under the verbalization condition. Although the findings must be considered tentative because of this ceiling effect and the small sample sizes, our results do suggest that patients with CHI benefit more from self-instructional cues in a complex and distracting environment.

Adult↗