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The reproducibility of flow cytometric analyses in human tumors. Methodological aspects.

Various methodological aspects of flow cytometry were studied in material from endometrial carcinoma, ovarian tumors and bladder carcinoma. Measurements of identical samples on two different occasions gave an excellent correlation of the obtained DNA values, r = 0.997 and a good reproducibility of the S-phase rate, r = 0.87. In large tumors different DNA values were found in 5/36 cases when central and surface biopsies were compared (indicating tumor heterogeneity) which stresses the importance of multiple biopsies. The S-phase rate of the surface biopsies was generally higher. Comparing staining with ethidium bromide and DAPI, a good correspondence of ploidy determinations in human bladder tumors was found, provided that diploid cells from the normal tissue component were used as internal reference. When ethidium bromide staining was used, there was a good agreement between the values of tumor ploidy obtained by external standardization using lymphocytes and internal standardization using diploid tumor cells, respectively. In DAPI staining with lymphocytes as an external standard the tumor ploidy was systematically overestimated by about 10% due to suboptimal staining of lymphocytes after 3 hours. This difference decreased after 18 hours of staining. Determination of S-phase fraction showed a good correlation between DAPI and ethidium bromide stained bladder tumor samples (r = 0.86). Human lymphocytes as an external standard showed good reproducibility. In conclusion, flow cytometric measurements of the ploidy level and S-phase rate are highly reproducible provided that tumor heterogeneity is taken into account and proper preparation and standardization methods are used.

DNA, Neoplasm↗

PubMed1989

Reproducibility of non-invasive vascular diagnosis in patients with diabetes mellitus.

Reproducibility of noninvasive ultrasound methods for vascular diagnosis was studied in 36 patients with Insulin Dependent Diabetes Mellitus. The vascular examination included a) the measurement of ankle systolic arterial pressure and ankle/arm pressure index (c.w. Doppler), b) Echo-Doppler examination of iliac arteries with measurement of maximum systolic frequency, systolic spectrum width and diastolic reverse flow component. A grading of iliac artery stenosis was also performed. The examination was repeated after one month according to a blind protocol. The coefficients of variation were as follows: 8% for ankle pressure; 8% for ankle/arm pressure index; 9% for the maximum systolic frequency; 18% for the spectrum width and 15% for the reverse flow component. The reproducibility of the grading of iliac artery stenosis based on the combined use of the three Echo-Doppler parametres was measured by the Kendall coefficient (W = 0.865). These results confirm that non invasive methods are suitable and reliable for investigating vascular disease in diabetic patients. Accurate estimates of reproducibility are essential pre-requisites for the planning of studies on the natural history of vascular disease and on progression-regression of arterial lesions.

Aged↗

PubMed1989

Reproducibility of the indirect immunobead assay for detecting sperm antibodies in serum.

Although an immunobead assay (IBA) for the detection of antisperm antibodies was developed several years ago and has been used for the study of immunologic infertility, no data regarding its variability and reproducibility are yet available. We evaluated the intraassay reproducibility of the indirect IBA by testing aliquots of antisperm-antibody-positive sera from two patients against the same donor sperm sample. The interassay reproducibility was evaluated by testing a positive serum sample first with different sperm samples from the same donor and second with sperm samples from different donors. The results of those experiments showed that the indirect IBA has very low intraassay variation and greater interassay variability.

Female↗

PubMed1995

Reproducibility of 24-h energy expenditure, substrate utilization and spontaneous physical activity in obesity measured in a respiration chamber.

OBJECTIVE: Determination of within-subject day-to-day coefficients of variations (CV) of 24-h measurements of spontaneous physical activity (SPA), macronutrient oxidation, energy expenditure (EE) and heart rate (HR). DESIGN: Two 24-h measurements in respiration chamber, separated by 14 days of strict weight stability. SUBJECTS: 22 healthy obese subjects, 15 females and seven males (age 27-64 y, BMI: 30-39 kg/m2). MEASUREMENTS: SPA assessed by microwave radar, substrate oxidation and EE measured by indirect calorimetry and heart rate measured by telemetry. RESULTS: For 24-h measurements CV was 0.8% for RQ, 6.7% for fat oxidation, 5.6% for carbohydrate oxidation, 14.5% for protein oxidation, and 4.3% for heart rate. SPA assessed by microwave radar was also reproducible (CV = 9.7%). Within-subject day-to-day coefficients of variations (CV) were 1.5 and 1.8% for 24-h EE and sleeping EE, and 4.1% for RMR. Both on day 1 and 14, 93.4% of the variation in 24-h EE could be explained by differences in fat-free mass (92.3 and 92.4%, respectively) and SPA (1.1 and 1.0%), respectively). Also the algorithm and correlation between 24-h RQ and 24-h energy balance were highly reproducible (r = 0.56, P < 0.01 and r = 0.48, P < 0.05). CONCLUSION: Both macronutrient oxidation, SPA and EE in obese patients can be determined with high reproducibility in a respiration chamber.

Adrenergic beta-Agonists↗

PubMed1995

[Objectivity, reproducibility and validity of 3D ultrasound in dermatology].

Recently it has become possible to visualize the three-dimensional (3D) architecture of sonographic structures using high-resolution ultrasound above 20 MHz (Dermascan C, Denmark; DUB 20, Germany). We studied the objectivity, reproducibility, and validity of these two 3D analysis systems on 22 skin tumors. To validate both systems, we compared the sonometric and histometric volume in 4 tumors. The objectivity was calculated by repeated evaluation of the volume on the same serial B-scan sections at 3-month intervals. The two-dimensional B-scans and 3D images exhibited similar characteristics. Volumetric evaluations were reproducible with both systems (variation coefficient < or = 9.9%), when the applicator was oriented longitudinal to the body axis. By changing the orientation, the coefficient increased up to 58.1% (DUB 20). Sonometric and histometric volumes of a phantom model and of the tumors exhibited small deviations in the Dermascan C (< or = 8.1%) and in some tumors large deviations in the DUB 20 (< or = 93.1%). We can conclude that the 3D sonography is a reproducible method, which can be used to evaluate the volume of skin tumors and metastases under chemotherapy or radiotherapy. We suggest in particular to use the in-vivo tumor volume as a prognostic parameter for the malignant melanoma.

Adult↗

PubMed1995

Soft toric lens power accuracy and reproducibility.

Lens power accuracy is the most frequently cited requirement for reproducible soft toric lens performance. Power accuracy is even more critical with planned replacement soft toric lenses because of the increased rate at which lenses are replaced. However, no reproducible methodology exists for making such an evaluation. We developed a power measurement method from which measurement error was eliminated. Geometric optical calculation was used to calculate the resulting optical error. The relationship between visual acuity loss and optical errors was used to predict the effect on visual acuity. This method was applied to a sample of 457 Focus Toric soft contact lenses. We found that 83.5 +/- 1.7% of the lenses were accurate enough to deliver one line or less of loss in visual acuity. Our estimate of the clinical problem rate associated with power reproducibility was 3.3 +/- 0.9% of lens pairs. If lenses were replaced on a monthly basis, this would amount to one problem pair every 30 months.

Contact Lenses, Hydrophilic↗

PubMed1995

[Multicenter study for the evaluation of the reproducibility in the measurement of rectal sensorial threshold].

A simple way to evaluate the rectal sensorial threshold has been the sloped distention of a rectal balloon, as a way to obtain the required volume to induce desire to defecate (VDE) and pain (VTM). Six medical groups belonging to the Argentine Motility Circle, studied in 14 patients (7M, 7F age 51 +/- 10.1) the VDE and VTM. The measurements were repeated in the same subjects with intervals longer than 24 Hs. The estimate of precision established a coefficient of variation (CV) for VDE of 10.23% (2CV = 20.46%). And so Reproducibility was found to be not acceptable. The CV for VMT was 1.44 (2CV = 2.88%) this could be considered a very good reproducibility. In conclusion, the VTM appears to be a reproducible measurement suitable for clinical and pharmacological studies of the rectal sensorial perception.

Adult↗

PubMed1995

Reproducibility of semi-automated cell cycle analysis of flow cytometric DNA-histograms of fresh breast cancer material.

DNA-variables such as DNA-ploidy, DNA-index and %S-phase cells have been proven to have prognostic value for breast cancer patients. These variables can be obtained by interpreting DNA-histograms by cell cycle analysis. Since there are a number of potential error sources, the aim of this study was to determine the intra- and inter-observer reproducibility of semi-automated cell cycle analysis with the emphasis on DNA ploidy and %S-phase assessments. The 149 DNA-histograms we used were randomly selected from the Multicentre Morphometric Mammary Carcinoma Project, a nationwide prospective study in The Netherlands on the reproducibility and prognostic power of quantitative assessments. These DNA-histograms were obtained by flow cytometry of fresh frozen breast cancer material. Cell cycle analysis was performed according to a strict protocol with the semi-automated computer program 'MultiCycle', using the background correction option; 68 histograms were analyzed in duplicate by the same observer, and 81 histograms were analyzed by two observers. Assessment of DNA-ploidy showed an intra-observer concordance of 99% (kappa-value 0.98) and an inter-observer concordance of 94% (kappa-value 0.91). The disagreement could be attributed to overlooking a DNA-tetraploid cell cycle in one case, some difficult histograms and varying opinions about small peaks between the observers in a few cases. Intra-observer %S-phase correlation coefficients varied between 0.72 for the %S-phase of the second aneuploid cell cycle and 0.99 for the %S-phase of the diploid cell cycle. Inter-observer correlation coefficients varied between 0.81 for the %S-phase of the second cell cycle and 0.95 for the %S-phase of the diploid cell cycle and the average %S-phase cells. As for DNA-index, intra- and inter-observer correlation coefficients were 0.97 and 0.94, respectively. In conclusion, intra- and inter-observer reproducibility of semi-automated cell cycle analysis of flow cytometric DNA-histograms from fresh breast cancer material using the Multi-Cycle program, following a strict protocol, is in principle high. The results of this study may help us to decide which of the different %S-phases provided by cell cycle analysis software should be used in daily practice.

Breast Neoplasms↗

PubMed1995

[Non-invasive 13C octanoic acid breath test for measuring stomach emptying of a solid test meal--correlation with scintigraphy in diabetic patients and reproducibility in healthy probands].

The recently developed 13C-octanoic acid breath test allows the measurement of gastric emptying of solids. In this prospective study we wanted to investigate, whether the 13C-octanoic acid breath test using breath samples every half an hour is suitable in assessing gastric emptying in comparison to scintigraphy in diabetics. Furthermore, we examined the intraindividual reproducibility in healthy volunteers. 20 consecutive diabetics with clinical symptoms of gastroparesis received a solid double-labeled standard test meal. The meal consisted of 1 scrambled egg, labeled with 75 mg 13C-octanoic acid and 0.5 mCi 99mTc colloid, 50 g rye bread, 20 g butter, 200 ml orange juice; 280 kcal. Breath samples were taken at half hour intervals for 4 hours and analyzed for 13CO2 by isotope ratio mass spectrometry. Using a regression method gastric emptying half times (t 1/2) were determined and correlations to simultaneous 99mTc-scintigraphy were calculated. There was a moderate significant correlation of 13C-octanoic acid breath test t 1/2 and scintigraphic t 1/2 (R = 0.6; p = 0.008). The 13C-octanoic acid breath test t 1/2 obtained in 20 healthy volunteers measured at two separate days showed a coefficient of variation (VC), that was greater between subjects (VK = 42%) than between two measurements in the same subject (VK = 24%), which reflects a moderate intraindividual reproducibility. Taking breath samples every half an hour the 13C-octanoic acid breath test only reveals a moderate intraindividual reproducibility and a moderate correlation to scintigraphy in diabetics. For detailed assessment of solid gastric emptying in diabetics a 13C-octanoic acid breath test using shorter breath sampling intervals is recommended.

Aged↗

PubMed1995

Reproducibility of SPECT measurement of benzodiazepine receptors in human brain with iodine-123-iomazenil.

UNLABELLED: Iodine-123-iomazenil is a SPECT radiotracer used to image and quantify benzodiazepine receptors. The reproducibility of the measurement of benzodiazepine receptors in human brain with [123I]iomazenil and SPECT was investigated with a test/retest paradigm. METHODS: Six subjects underwent two experiments during a 1-wk interval. Iodine-123-iomazenil was injected as a single bolus (12 mCi). The time-activity curves of the tracer in the arterial plasma were measured and corrected for metabolites. Regional time-activity curves of five brain regions were measured with the CERASPECT camera for 145 min postinjection with serial 2-min acquisitions. Data were analyzed using three kinetic models that included a two-compartment model, an unconstrained three-compartment model and a three-compartment model with a constraint on the nondisplaceable compartment. RESULTS: The results from the various analyses and fitting strategies were compared. The variability (average absolute difference between test and retest, expressed as a percentage of the mean of both measurements) was 10% to 17%, depending on the outcome measure and the fitting procedure. The most reproducible outcome measure was the regional tracer distribution volume relative to the total arterial concentration (VT'). VT' showed an average regional variability of 10% +/- 2%, with an intraclass correlation coefficient of 0.81. CONCLUSION: SPECT measurement of regional [123I]iomazenil VT' is reproducible and reliable. The use of regional ratios results in a significant loss of information.

Adult↗

PubMed1994

Reproducibility of a meal-based food frequency questionnaire. The influence of format and time interval between questionnaires.

OBJECTIVE: To compare the reproducibility and reported level of energy intake obtained using three versions of a meal-based food frequency questionnaire (FFQ) considering, firstly, the influence of FFQ format and, secondly, the influence of time interval between questionnaires. DESIGN: The study was conducted in two parts. In the first, subjects were randomly allocated to three groups (one for each FFQ) and sent, by mail, the same FFQ to complete on two separate occasions with a time interval of 4-6 weeks. In the second study, the reproducibility of one of the FFQs used in the initial study was compared, after an interval of 3 months, in a further group of people, matched as far as possible for gender, age and socio-economic status of area of residence. SUBJECTS: The study population was 651 supermarket shoppers from Geelong, a regional centre with a population of 150,000 situated in Victoria, Australia, who had previously responded to an in-store survey about meat purchasing patterns. Of the 651 shoppers, 144 women and nine men (38% of those eligible) in part I and 98 women and two men (45% of those eligible) in part II of the study satisfactorily completed a FFQ on both occasions. RESULTS: While there were few statistically significant differences in terms of mean nutrient intake and nutrient density between the three FFQ formats, all under-estimated energy intake relative to the minimum estimated energy requirements for a sedentary population. A significant decrease in reported intake of approximately 10% was also observed, regardless of FFQ format used, when the same questionnaire was completed a second time after an interval of 4-6 weeks. In contrast, when the time interval between questionnaires was increased to 3 months, there were few significant differences in intake between the first and second administrations. Moreover those changes in food intake which were significantly different after the longer interval were, in general, consistent with expected seasonal changes in food intake patterns. CONCLUSION: Under the conditions of our study differences in FFQ format appeared to have less effect on estimates of mean intake than the length of the time interval between questionnaires. Our results suggest that motivation to complete a FFQ is significantly diminished on the second occasion, when the interval between FFQs is only 4-6 weeks and to a lesser extent when it is 3 months. Researchers planning studies which aim to assess short-term changes in food intake by means of a FFQ, for example after an intervention programme, need to be aware of this effect and to determine its magnitude, by assessing the reproducibility of their FFQ over the relevant time-interval prior to the proposed intervention and by including an appropriate non-intervention comparison group in the design of their study if seasonal effects are likely to occur in the course of the study.

Energy Intake↗

PubMed1994

[Reproducibility of head-up tilt test in patients with neurocardiogenic syncope].

PURPOSE: In order to identify the reproducibility of head-up tilt test, a second test one week later in 22 patients with a positive first test, was performed. METHODS: The test was performed in a fasting state during the morning. The heart rate and blood pressure were monitored during 20 minutes in the supine position and then at 60 degrees for up to 40 minutes. The test were considered positive if the patient experienced syncope or pre-syncope with fall in systolic blood pressure > 30mmHg. The following aspects were evaluated: reproducibility of the positive response; the type of response (hypotension, asystole or hypotension plus bradycardia) and the time interval between tilt and the beginning of symptoms. RESULTS: Eighteen (82%) patients had a second positive response; 14 (77.8%) of then had the same type of response; and 17 (94%) had syncope in similar time interval after tilt. CONCLUSION: The head-up tilt testing has good reproducibility, although its use in the therapeutic management needs a longer period of evaluation.

Adolescent↗

PubMed1994

[Response rate, missing values, validity and reproducibility of responses in mark-sheet and conventional questionnaires].

A self-administered questionnaire using the mark-sheet method (MSM), in which responses of subjects are computer processed directly through an optical scanning device, has recently been utilized in epidemiologic surveys. Compared to the data coding process for a conventional questionnaire, in which a keypuncher enters the responses manually into a computer (manual method; MM), optical scanning requires less time and cost. Accuracy of the MSM for use in the general population in Japan, however, remains uncertain. Therefore the response rates, frequencies of missing values, validity and reproducibility of the answers in self-administered questionnaires were compared between the MSM and MM. Subjects were 463 residents aged 40-69 years living in 6 local districts of a rural town in northeastern Japan. They were randomly allocated, by district basis, to the MSM group (n = 242) or the MM group (n = 221). The questionnaire was delivered and collected at the subject's home by volunteers. Two weeks after collecting the original questionnaire, the same type of questionnaire was again distributed to half of the responders randomly chosen to investigate reproducibility. The overall response rate did not differ in MSM and MM (96.7% vs 98.2%, p = 0.312). Among questions with a multiple-choice type of answer, proportions of missing values were not different for most of the items, but it was lower in MSM for all of the 33 food frequency items. Reproducibilities of food frequency items measured by Spearman's rank correlation did not differ substantially in two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

[Accuracy and reproducibility of the Eyesys corneal topographic analysis system].

Corneal topographic analysis has become quite useful for corneal surgery. Quantitative data on the quality and accuracy of the available instruments are not well known. We studied the accuracy and the reproducibility of the Eyesys machine using 4 calibrated balls: 8.99 mm, 7.93 mm, 7.10 mm, 6.13 mm. The machine is accurate (precision less than 0.1D for all the balls) and reproducible (4 measurements) with a SD less than 0.05 diopter for all the balls except for the 55.04's ball (0.06 to 0.1). We also studied reproducibility with six normal corneas using the same method. SD was 0.26 diopter for keratometry and 0.50 diopter for the astigmatism value.

Astigmatism↗

PubMed1994

Evaluation of the accuracy and reproducibility of ambulatory blood pressure monitoring in the very elderly using the Takeda TM-2420.

The accuracy and reproducibility of ambulatory blood pressure monitoring (ABPM) were evaluated in the healthy elderly (> or = 75 years) using the Takeda TM-2420 ambulatory BP monitor (A & D Mercury, Australia). Accuracy was assessed from 90 standardised sphygmomanometer and simultaneously recorded TM-2420 BP measurements in 28 subjects with a BP range of 60-210 mmHg. Reproducibility was determined in 19 subjects who underwent four separate days of ABPM by calculating the standard deviation of the mean differences between pairs of recording days (sdd) and the coefficient of reliability (R). Adaptation was also assessed using R. Of 3471 BP measurements in 19 subjects over 76 recording days, 76% were valid readings. The TM-2420 overestimated simultaneously recorded sphygmomanometer measurements with a bias (mean difference, d +/- sdd) of 13.9 +/- 13.9 mmHg for SBP and 7.5 +/- 6.4 mmHg for DBP. The mean sdd between pairs of recording days was greater for SBP (20.0) than for DBP (9.4) but R was very high for both SBP (0.914) and DBP (0.904). Adaptation effects were not detected. ABPM with the TM-2420 is highly reproducible in the elderly. The TM-2420 performs acceptably in 'field' testing and as it overestimates cuff measurements consistently, appropriate adjustment of recorded TM-2420 BP should be possible in elderly individuals.

Aged↗

PubMed1994

[Reproducibility of symptom-limited oxygen consumption and anaerobic threshold within the scope of spiroergometric studies in patients with heart failure].

A prerequisite for the clinical utility of cardiopulmonary exercise testing is high reproducibility of gas-exchange characteristics. Therefore, we studied reproducibility of peak oxygen uptake and anaerobic threshold during bicycle-exercise stress testing in 34 patients with congestive heart failure in NYHA classes II and III. Additionally, we analyzed interobserver variability with regard to anaerobic threshold measured with the V-slope method. Correlations of results between two exercise stress tests were high concerning peak oxygen uptake and anaerobic threshold (r = 0.871 and r = 0.917, respectively). For both measures, however, 90% percentile of the relative difference between tests was 25% and 22%, respectively. Correlation between two observers with regard to the anaerobic threshold was high (r = 0.985). We conclude that reproducible determination of peak oxygen uptake and anaerobic threshold is possible in heart-failure patients. In individual subjects, however, considerable variation of results may occur during serial exercise testing. Interobserver variability with regard to anaerobic threshold is low.

Adult↗

PubMed1994

Randomly amplified DNA polymorphisms in dogs are reproducible and display Mendelian transmission.

Many inherited diseases occur in pure-bred dogs, but diagnosis at the level of DNA is impossible because the canine genome is largely unknown. Random amplification of polymorphic DNA (RAPD) provides many polymorphisms, but the reproducibility and Mendelian inheritance are not beyond doubt. An optimized polymerase chain reaction (PCR) was developed for canine DNA with respect to the annealing temperature and the concentrations of MgCl2, template DNA and primers. RAPD amplification products were in the range of 100-1500 base pairs. With six primers, 21 different reactions with different electrophoretic patterns were obtained, yielding 9-29 products per reaction. In DNA from dogs of 16 different breeds, 14% of the products were polymorphic; when only beagles were included the rate of polymorphism was 10%. All of the reaction products were completely reproducible in 16 DNA samples. Mendelian transmission was analysed in six beagle families (42 dogs). The segregation of polymorphic amplification products in 21 reactions performed on DNA from all beagles was nearly complete; in only two of the 630 reactions was there a product that could not be traced back to either of the parents. The reproducibility and Mendelian behaviour of polymorphisms generated by RAPD in dogs makes this tool very suitable for development of DNA markers of canine inherited diseases.

Animals↗

PubMed1994

Reproducibility of a food frequency questionnaire for use in ocular research. Eye Disease Case-Control Study Group.

PURPOSE: Assessment of nutritional factors was an ancillary component of the Eye Disease Case-Control Study sponsored by the National Eye Institute. This multicenter study was designed to evaluate the role of potential risk factors for a number of retinal disorders. The authors examined the reproducibility of the food frequency questionnaire used in this study. METHODS: A semiquantitative food frequency questionnaire, designed for use in this study, was self-administered by participants. To evaluate the reproducibility of this dietary questionnaire, a subsample of 325 participants completed a second questionnaire within 12 to 18 months of the first. Pearson product-moment coefficient was used to assess the correlation between the log of calorie-adjusted nutrient scores, and Spearman correlations were used for specific food items. RESULTS: The responses for intake of 60 food items in the questionnaire were reasonably consistent. Correlation coefficients for individual food items ranged from 0.40 to 0.82. Pearson correlation coefficients for logs of calorie-adjusted intake of nutrients ranged from 0.38 to 0.75. Nutrients of interest in eye disease include total protein (r = 0.57), total fat (r = 0.71), saturated fats (r = 0.69), carotene (r = 0.61), vitamin C (with supplements, r = 0.66), vitamin E (with supplements, r = 0.69), and zinc (with supplements, r = 0.43). Partial correlations controlling for age, sex, and clinical center were similar. CONCLUSIONS: These findings indicate that the food frequency questionnaire used in this study provides reasonably reproducible dietary information.

Adult↗