Atrial natriuretic peptides: reproducibility of renal effects and response of liver blood flow.

To assess the variability of the response to exogenous atrial natriuretic peptide (ANP), it was infused at the rate of 1 microgram/min for 2 h in 6 salt-loaded normal volunteers under controlled conditions on 2 occasions at an interval of 1 week. The effect on solute excretion and the haemodynamic and endocrine actions were highly reproducible. The constant ANP infusion caused a delayed and prolonged excretion of sodium, chloride and calcium, no change in potassium or phosphate excretion or in glomerular filtration rate but a marked decrease in renal plasma flow. Blood pressure, heart rate and the plasma levels of angiotensin II, aldosterone, arginine vasopressin and plasma renin activity were unaltered. The effect of a 2-h infusion of ANP 0.5 microgram/min or its vehicle on apparent hepatic blood flow (HBF) was also studied in 14 normal volunteers by measuring the indocyanine green clearance. A 21% decrease in HBF was observed in subjects who received the ANP infusion (p less than 0.01 vs vehicle). Thus, ANP infused at a dose that did not lower blood pressure decreased both renal and liver blood flow in normotensive volunteers. The renal and endocrine responses to ANP were reproducible over a 1-week interval.

Validation and reproducibility of a semi-quantitative Food Frequency Questionnaire for use in elderly Swiss women.

OBJECTIVE: The principal aim of this study was to develop a Swiss Food Frequency Questionnaire (FFQ) for the elderly population for use in a study to investigate the influence of nutritional factors on bone health. The secondary aim was to assess its validity and both short-term and long-term reproducibility. DESIGN: A 4-day weighed record (4 d WR) was applied to 51 randomly selected women of a mean age of 80.3 years. Subsequently, a detailed FFQ was developed, cross-validated against a further 44 4-d WR, and the short- (1 month, n = 15) and long-term (12 months, n = 14) reproducibility examined. SETTING: French speaking part of Switzerland. SUBJECTS: The subjects were randomly selected women recruited from the Swiss Evaluation of the Methods of Measurement of Osteoporotic Fracture cohort study. RESULTS: Mean energy intakes by 4-d WR and FFQ showed no significant difference [1564.9 kcal (SD 351.1); 1641.3 kcal (SD 523.2) respectively]. Mean crude nutrient intakes were also similar (with nonsignifcant P-values examining the differences in intake) and ranged from 0.13 (potassium) to 0.48 (magnesium). Similar results were found in the reproducibility studies. CONCLUSION: These findings provide evidence that this FFQ adequately estimates nutrient intakes and can be used to rank individuals within distributions of intake in specific populations.

Reproducibility of straylight measurement by C-Quant for assessment of retinal straylight using the compensation comparison method.

BACKGROUND: Straylight gives the appearance of a veil of light thrown over a person's retinal image when there is a strong light source present. We examined the reproducibility of the measurements by C-Quant, and assessed its correlation to characteristics of the eye and subjects' age. PARTICIPANTS AND METHODS: Five repeated straylight measurements were taken using the dominant eye of 45 healthy subjects (age 21-59) with a BCVA of 20/20: 14 emmetropic, 16 myopic, eight hyperopic and seven with astigmatism. We assessed the extent of reproducibility of straylight measures using the intraclass correlation coefficient. RESULTS: The mean straylight value of all measurements was 1.01 (SD 0.23, median 0.97, interquartile range 0.85-1.1). Per 10 years of age, straylight increased in average by 0.10 (95%CI 0.04 to 0.16, p < 0.01]. We found no independent association of refraction (range -5.25 dpt to +2 dpt) on straylight values (0.001; 95%CI -0.022 to 0.024, p = 0.92). Compared to emmetropic subjects, myopia reduced straylight (-.011; -0.024 to 0.02, p = 0.11), whereas higher straylight values (0.09; -0.01 to 0.20, p = 0.09) were observed in subjects with blue irises as compared to dark-colored irises when correcting for age. The intraclass correlation coefficient (ICC) of repeated measurements was 0.83 (95%CI 0.76 to 0.90). CONCLUSIONS: Our study showed that straylight measurements with the C-Quant had a high reproducibility, i.e. a lack of large intra-observer variability, making it appropriate to be applied in long-term follow-up studies assessing the long-term effect of surgical procedures on the quality of vision.

Parametrization of spectral surfaces of a class of periodic 5-diagonal matrices

The main result of this work is a parametric description of the spectral surfaces of a class of periodic 5-diagonal matrices, related to the strong moment problem. This class is a self-adjoint twin of the class of CMV matrices. Jointly they form the simplest possible classes of 5-diagonal matrices.

Reproducibility of acute mountain sickness in children and adults : a prospective study

Objectif: Alors qu'un antécédent d' AMS est couramment utilisé pour fournir des conseils et recommander une prophylaxie médicamenteuse pour les expositions ultérieures à la haute altitude, la reproductibilité intra-individuelle de l'AMS au cours d'expositions répétées n'a jamais été examinée dans une étude prospective contrôlée. Méthodes : Chez 27 enfants et 29 adultes non acclimatés, nous avons évalué la présence et la sévérité de l' AMS durant les 48 premières heures après une montée rapide à 3450m, et ceci en deux occasions distantes de 9 à 12 mois. Résultats: 18 adultes (62 %) et 6 enfants (22 %) ont souffert d'AMS durant la première exposition et 14 adultes (48 %) et 4 enfants (15 %) durant la seconde (P=O.Ol, adultes versus enfants). Mais surtout, la reproductibilité intra-individuelle de l'AMS était très différente (P < 0.001) entre les deux groupes; en effet, aucun des 6 enfants ayant souffert d'AMS au cours de la première exposition n'en n'a souffert au cours de la seconde mais 4 enfants sans AMS lors de la première exposition ont été touchés lors de la seconde exposition. Contrairement à cela, 14 des 18 adultes qui ont souffert de 1' AMS lors de la première exposition ont également présenté ce problème au cours de la seconde et aucun nouveau cas ne s'est développé dans ceux qui n'avaient pas souffert de cette affection lors de la première occasion. ConClusion : Si chez 1' adulte, un antécédent d' AMS a une bonne valeur prédictive d'un nouvel épisode durant les expositions futures dans des conditions similaires, il n'en est pas de même chez l'enfant chez lequel il n'a pas de valeur prédictive. Un antécédent d'AMS ne devrait donc pas inciter les praticiens à déconseiller la réexposition ou à prescrire une prophylaxie médicamenteuse chez l'enfant.

A multicenter study to validate the reproducibility of MSI testing with a panel of 5 quasimonomorphic mononucleotide repeats.

Microsatellite instability (MSI) testing in clinics is becoming increasingly widespread; therefore, there is an urgent need for methodology standardization and the availability of quality control. This study is aimed to assess the interlaboratory reproducibility of MSI testing in archive samples by using a panel of 5 recently introduced, mononucleotide repeats (MNR). The quality control involved 8 European institutions. Participants were supplied with DNA extracted from 15 archive colon carcinoma samples and from the corresponding normal tissues. Every group was asked to assess the MSI status of the samples by using the BAT25, BAT26, NR21, NR24, and NR27 mononucleotide markers. Four institutions repeated the analysis using the NCI reference panel to confirm the results obtained with the MNR markers. The overall concordance among institutions for MSI analyses at single locus level was 97.7% when using the MNR panel and 95.0% with the NCI one. The laboratories obtained a full agreement in scoring the MSI status of each patient sample, both using the mononucleotide and the NCI marker sets. With the NCI marker set, however, concordance was lowered to 85.7% when considering the MSI-Low phenotype. Concordance between the 2 panels in scoring the MSI status of each sample was complete if no discrimination was made between MSI-Stable and MSI-L, whereas it dropped to 76.7% if MSI-L was considered. In conclusion, the use of the MNR panel seems to be a robust approach that yields a very high level of reproducibility. The results obtained with the 5 MNR are diagnostically consistent with those obtained by the use of the NCI markers, except for the MSI-Low phenotype.

Reproducibility of acute mountain sickness in children and adults: a prospective study.

OBJECTIVE: Although a history of previous acute mountain sickness (AMS) is commonly used for providing advice and recommending its prophylaxis during subsequent exposure, the intraindividual reproducibility of AMS during repeated high-altitude exposure has never been examined in a prospective controlled study.METHODS: In 27 nonacclimatized children and 29 adults, AMS was assessed during the first 48 hours after rapid ascent to 3450 m on 2 consecutive occasions 9 to 12 months apart.RESULTS: During the first exposure, 18 adults (62%) and 6 children (22%) suffered from AMS; during the second exposure, 14 adults (48%) and 4 children (15%) suffered from this problem (adults versus children, P <= .01). Most importantly, the intraindividual reproducibility of AMS was very different (P < .001) between children and adults. None of the 6 children having suffered from AMS during the first exposure suffered from AMS during the second exposure, but 4 children with no AMS during the first exposure did experience this problem during the second exposure. In contrast, 14 of the 18 adults who suffered from AMS on the first occasion also presented with this problem during the second exposure, and no new case developed in those who had not experienced AMS on the first occasion.CONCLUSIONS: In adults, a history of AMS is highly predictable of the disease on subsequent exposure, whereas in children it has no predictive value. A history of AMS should not prompt practitioners to advise against reexposure to high altitude or to prescribe drugs for its prophylaxis in children. Pediatrics 2011;127:e1445-e1448

Reproducibility of 3D free-breathing magnetic resonance coronary vessel wall imaging.

AIMS: Although the coronary artery vessel wall can be imaged non-invasively using magnetic resonance imaging (MRI), the in vivo reproducibility of wall thickness measures has not been previously investigated. Using a refined magnetization preparation scheme, we sought to assess the reproducibility of three-dimensional (3D) free-breathing black-blood coronary MRI in vivo. METHODS AND RESULTS: MRI vessel wall scans parallel to the right coronary artery (RCA) were obtained in 18 healthy individuals (age range 25-43, six women), with no known history of coronary artery disease, using a 3D dual-inversion navigator-gated black-blood spiral imaging sequence. Vessel wall scans were repeated 1 month later in eight subjects. The visible vessel wall segment and the wall thickness were quantitatively assessed using a semi-automatic tool and the intra-observer, inter-observer, and inter-scan reproducibilities were determined. The average imaged length of the RCA vessel wall was 44.5+/-7 mm. The average wall thickness was 1.6+/-0.2 mm. There was a highly significant intra-observer (r=0.97), inter-observer (r=0.94), and inter-scan (r=0.90) correlation for wall thickness (all P<0.001). There was also a significant agreement for intra-observer, inter-observer, and inter-scan measurements on Bland-Altman analysis. The intra-class correlation coefficients for intra-observer (r=0.97), inter-observer (r=0.92), and inter-scan (r=0.86) analyses were also excellent. CONCLUSION: The use of black-blood free-breathing 3D MRI in conjunction with semi-automated analysis software allows for reproducible measurements of right coronary arterial vessel-wall thickness. This technique may be well-suited for non-invasive longitudinal studies of coronary atherosclerosis.

Regional reproducibility of calibrated BOLD functional MRI: implications for the study of cognition and plasticity.

Calibrated BOLD fMRI is a promising alternative to the classic BOLD contrast due to its reduced venous sensitivity and greater physiological specificity. The delayed adoption of this technique for cognitive studies may stem partly from a lack of information on the reproducibility of these measures in the context of cognitive tasks. In this study we have explored the applicability and reproducibility of a state-of-the-art calibrated BOLD technique using a complex functional task at 7 tesla. Reproducibility measures of BOLD, CBF, CMRO2 flow-metabolism coupling n and the calibration parameter M were compared and interpreted for three ROIs. We found an averaged intra-subject variation of CMRO2 of 8% across runs and 33% across days. BOLD (46% across runs, 36% across days), CBF (33% across runs, 46% across days) and M (41% across days) showed significantly higher intra-subject variability. Inter-subject variability was found to be high for all quantities, though CMRO2 was the most consistent across brain regions. The results of this study provide evidence that calibrated BOLD may be a viable alternative for longitudinal and cognitive MRI studies.

Reproducibility of twitch mouth pressure, sniff nasal inspiratory pressure, and maximal inspiratory pressure.

Twitch mouth pressure (Pmo,tw) during magnetic phrenic nerve stimulation and sniff nasal inspiratory pressure (SNIP) were recently proposed as alternative noninvasive methods for assessing inspiratory muscle strength. This study aimed to compare their reproducibility with maximal inspiratory pressure (MIP) in normal subjects. Ten healthy subjects were studied at functional residual capacity in semirecumbent position. Cervical magnetic phrenic nerve stimulation was performed during gentle expiration against an occlusion incorporating a small leak. Constancy of stimulation was controlled by recording diaphragmatic electromyogram. Within and between-session reproducibility of pressure were studied for Pmo,tw, SNIP, and MIP. The subjects were studied during a session of 10 manoeuvres repeated after 1 day and 1 month. The mean values were 16 cmH2O for Pmo,tw, 118 cmH2O for SNIP, and 115 cmH2O for MIP. For the three tests, the within subject variation was small in relation to between-subject variation, with the intraclass correlation coefficient ranging 0.79-0.90 for Pmo,tw, 0.85-0.92 for SNIP, and 0.88-0.92 for MIP. At 1 day interval, the coefficient of repeatability (2 SD of differences) was 3.6 cmH2O for Pmo,tw, 32 cmH2O for SNIP and 28 cmH2O for MIP. At 1 month interval, the coefficient of repeatability was 5.8 cmH2O for Pmo,tw, 23 cmH2O for SNIP and 21 cmH2O for MIP. We conclude that the within session reproducibility of the new tests twitch mouth pressure and sniff nasal inspiratory pressure is sufficient to be clinically useful. For sniff nasal inspiratory pressure, the between session reproducibility established after 1 day was maintained after 1 month. For twitch mouth pressure, the between session reproducibility declined slightly after 1 month. These characteristics should be considered when using these methods to follow an individual patient over time.

Reproducibility of species lists, visual cover estimates and frequency methods for recording high mountain vegetation

Question: When multiple observers record the same spatial units of alpine vegetation, how much variation is there in the records and what are the consequences of this variation for monitoring schemes to detect change? Location: One test summit in Switzerland (Alps) and one test summit in Scotland (Cairngorm Mountains). Method: Eight observers used the GLORIA protocols for species composition and visual cover estimates in percent on large summit sections (>100 m2) and species composition and frequency in nested quadrats (1 m2). Results: The multiple records from the same spatial unit for species composition and species cover showed considerable variation in the two countries. Estimates of pseudoturnover of composition and coefficients of variation of cover estimates for vascular plant species in 1m x 1m quadrats showed less variation than in previously published reports whereas our results in larger sections were broadly in line with previous reports. In Scotland, estimates for bryophytes and lichens were more variable than for vascular plants. Conclusions: Statistical power calculations indicated that, unless large numbers of plots were used, changes in cover or frequency were only likely to be detected for abundant species (exceeding 10% cover) or if relative changes were large (50% or more). Lower variation could be reached with the point methods and with larger numbers of small plots. However, as summits often strongly differ from each other, supplementary summits cannot be considered as a way of increasing statistical power without introducing a supplementary component of variance into the analysis and hence the power calculations.

Sprinkle Treatment of Asphalt Surfaces, HR-199, 1984

Methods of improving highway safety are of major concern to everyone who is involved in the planning, development and construction of improvements of our vast highway network. Other major concerns are the conservation of our rapidly disappearing sources of energy and quality building materials. This research is devoted to further exploration of a process which will: 1. help preserve higher quality aggregates; and, 2. improve the frictional characteristics and surface texture of asphalt pavement surfaces. Sprinkle treatment of asphalt concrete pavement surfaces with a non-polishing aggregate, a procedure which was developed in Europe, is one method which has shown promise in accomplishing the above listed objectives. This research seeks to explore the feasibility and cost effectiveness of using standard asphalt mixtures of local, less expensive aggregates for surface courses followed by a surface sprinkle treatment of a hard, durable, non-polishing layer of precoated chips to produce a durable, non-skid pavement surface for safe highway travel. Three standard mixture types are being evaluated for aggregate retention characteristics and six sprinkle aggregates are being evaluated for durability, polishing and friction characteristics. In addition, measurements of the surface texture by the silicone putty method are being made. Another feature of this research is the evaluation of a rubberized asphalt material called Overflex MS as a crack filler. It has been reported that the material could be beneficial in reducing reflective cracking. The project was begun in July of 1978 and was completed in August. A review made in the spring of 1979 indicates very satisfactory performance. It was determined from slide photos taken after construction and again in the spring that aggregate retention was very good. However, many cracks had reflected indicating that the Overflex MS had not been effective. Follow up friction test results and texture analysis were also very good. The results of these tests are shown in Appendix A.

A comparative study on inter and intralaboratory reproducibility of renin measurement with a conventional enzymatic method and a new chemiluminescent assay of immunoreactive renin.

BACKGROUND: The activity of the renin-angiotensin system is usually evaluated as plasma renin activity (PRA, ngAI/ml per h) but the reproducibility of this enzymatic assay is notoriously scarce. We compared the inter and intralaboratory reproducibilities of PRA with those of a new automated chemiluminescent assay, which allows the direct quantification of immunoreactive renin [chemiluminescent immunoreactive renin (CLIR), microU/ml]. METHODS: Aliquots from six pool plasmas of patients with very low to very high PRA levels were measured in 12 centres with both the enzymatic and the direct assays. The same methods were applied to three control plasma preparations with known renin content. RESULTS: In pool plasmas, mean PRA values ranged from 0.14 +/- 0.08 to 18.9 +/- 4.1 ngAI/ml per h, whereas those of CLIR ranged from 4.2 +/- 1.7 to 436 +/- 47 microU/ml. In control plasmas, mean values of PRA and of CLIR were always within the expected range. Overall, there was a significant correlation between the two methods (r = 0.73, P < 0.01). Similar correlations were found in plasmas subdivided in those with low, intermediate and high PRA. However, the coefficients of variation among laboratories found for PRA were always higher than those of CLIR, ranging from 59.4 to 17.1% for PRA, and from 41.0 to 10.7% for CLIR (P < 0.01). Also, the mean intralaboratory variability was higher for PRA than for CLIR, being respectively, 8.5 and 4.5% (P < 0.01). CONCLUSION: The measurement of renin with the chemiluminescent method is a reliable alternative to PRA, having the advantage of a superior inter and intralaboratory reproducibility.