[The relationship between oral microbiota and taste]. / De relatie tussen mondmicrobiota en smaak.

Disruption of the perception of taste can have severe consequences on general health. Although evidence suggests that the oral microbiota plays a role in taste perception, little is known about this possible influence. In this scoping review, the influence of oral microbiota on taste perception was studied. Current scientific literature is heterogeneous in study methods and study populations, which impedes comparison of results. Although the findings of this review provide insufficient evidence to confirm the influence of oral microbiota on taste perception, some results show a relationship between taste perception and specific microorganisms. Several factors play a role in taste perception, including tongue coating, use of medication, advanced age, and decreased salivary flow rate, and when these factors are present, it is important to be alert to possible changes in taste. Large-scale studies, in which the multifactorial etiology of taste perception is addressed, are needed to clarify the role of the oral microbiota on taste perception.

Summer temperatures reach the thermal tolerance threshold of photosynthetic decline in temperate conifers.

Climate change-related environmental stress has been recognized as a driving force in accelerating forest mortality over the last decades in Central Europe. Here, we aim to elucidate the thermal sensitivity of three native conifer species, namely Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and silver fir (Abies alba), and three non-native species, namely Austrian pine (Pinus nigra), Douglas fir (Pseudotsuga menziesii) and Atlas cedar (Cedrus atlantica). Thermal sensitivity, defined here as a decline of the maximum quantum yield of photosystem II (Fv /Fm ) with increasing temperature, was measured under varying levels of heat stress and compared with the turgor loss point (πtlp ) as a drought resistance trait. We calculated three different leaf thermotolerance traits: the temperature at the onset (5%) of the Fv /Fm decline (T5), the temperature at which Fv /Fm was half the maximum value (T50) and the temperature at which only 5% Fv /Fm remained (T95). T5 ranged from 38.5 ± 0.8 °C to 43.1 ± 0.6 °C across all species, while T50 values were at least 9 to 11 degrees above the maximum air temperatures on record for all species. Only Austrian pine had a notably higher T5 value than recorded maximum air temperatures. Species with higher T5 values were characterized by a less negative πtlp compared to species with lower T5. The six species could be divided into 'drought-tolerant heat-sensitive' and 'drought-sensitive heat-tolerant' groups. Exposure to short-term high temperatures thus exhibits a considerable threat to conifer species in Central European forest production systems.

The recent expansion of Pluto's atmosphere.

Stellar occultations--the passing of a relatively nearby body in front of a background star--can be used to probe the atmosphere of the closer body with a spatial resolution of a few kilometres (ref. 1). Such observations can yield the scale height, temperature profile, and other information about the structure of the occulting atmosphere. Occultation data acquired for Pluto's atmosphere in 1988 revealed a nearly isothermal atmosphere above a radius of approximately 1,215 km. Below this level, the data could be interpreted as indicating either an extinction layer or the onset of a large thermal gradient, calling into question the fundamental structure of this atmosphere. Another question is to what extent Pluto's atmosphere might be collapsing as it recedes from the Sun (passing perihelion in 1989 in its 248-year orbital period), owing to the extreme sensitivity of the equilibrium surface pressure to the surface temperature. Here we report observations at a variety of visible and infrared wavelengths of an occultation of a star by Pluto in August 2002. These data reveal evidence for extinction in Pluto's atmosphere and show that it has indeed changed, having expanded rather than collapsed, since 1988.

Improved orbital and physical parameters for the pluto-charon system.

Analysis of the observations of several Pluto-Charon occultation and transit events in 1985 and 1986 has provided a more detailed knowledge of the system. The sum of the radii of Pluto and Charon is 1786 +/- 19 kilometers, but the individual radii are somewhat more poorly determined; Pluto is 1145 +/- 46 kilometers in radius and Charon is 642 +/- 34 kilometers in radius. The mean density of the system is 1.84 +/- 0.19 grams per cubic centimeter, implying that more than half of the mass is due to rock. Charon appears to have hemispheres of two different colors, the Plutofacing side being neutral in color and the opposite hemisphere being a reddish color similar to Pluto.

Occultation by a possible third satellite of neptune.

The 24 May 1981 close approach of Neptune to an uncataloged star was photoelectrically monitored from two observatories separated by 6 kilometers parallel to the occultation track. An 8.1-second drop in signal, recorded simultaneously at both sites, is interpreted as resulting from the passage of a third satellite of Neptune in front of the star. From the duration of the event, the derived minimum diameter for an object sharing Neptune's motion is 180 kilometers. If the object was in Neptune's equatorial plane and there are no significant errors in the prediction ephemeris, the object was located at a distance of 3 Neptune radii from Neptune's center.

The detection of eclipses in the pluto-charon system.

The first eclipses between Pluto and its satellite ("Charon") were detected in January and February 1985, confirming the satellite's existence. Eclipses lasting a few hours will now occur at 3.2-day intervals for the next 5 to 6 years and then will cease for about 120 years. Careful observations of these eclipses will allow greatly improved determinations to be made of several physical parameters for the Pluto-Charon system: the diameters of the planet and satellite, the surface albedo distribution on one hemisphere of the planet, the orbit of the satellite, and the mass of the planet and hence its density. Knowledge of the density will provide a constraint on models of Pluto's bulk composition.

The relationship of instrument parameters to performance within a survey peer group.

Using simulators of transmission imaging, an interlaboratory survey assessed the discriminatory performance of 86 subscribers, each of whom imaged a liver phantom in anterior and right lateral projections. Analysis was by receiver operating characteristic (ROC) with Az, the area under the ROC curve, used as a measure of accuracy unconfounded by decision bias. Az values were then defined as the dependent variable in a statistical model that related performance to several instrument design and operating parameters. Six of 14 postulated parameters explained approximately half of observed subscriber variability. These were: year of camera manufacture or upgrade, number of photomultiplier tubes, collimator type, total counts collected, use of a Co-57 disk source for imaging the phantom, and computer processing of the image. The findings confirm previous inferences drawn from controlled intralaboratory experimentation, but hitherto unsubstantiated by clinical imaging data.

Academic manpower survey of 1990: II. Kinetics in the United States (from the Joint Task Force on Pathology Manpower ASCP/CAP/APC).

Survey data obtained from chairmen of United States departments of pathology shows a continued shortage of faculty, especially those with the MD or MD/PhD degree. Losses of such faculty by responding departments during the 12 months prior to the survey were distributed as follows: retirement, 40 (15.6% of total); disability/death, 19 (7.4%); termination, 23 (8.9%); resignation, 172 (69.3%); and other, 3 (1.2%). Resignations were due primarily to decisions to join another university (41.4%) or to enter private practice (42.5%); a small proportion were due to individuals who left academe for a pathology position in government or industry, or left both academe and pathology for another field. Comparison with a similar survey performed in 1984 suggests that the manpower situation in academic pathology is worsening, especially with respect to physician faculty. An assessment of those factors known to influence manpower kinetics suggests that it will continue to deteriorate for the foreseeable future with an adverse impact on all sectors of pathology.

Academic manpower survey of 1990: I. Descriptors of departments of pathology in the United States (from the Joint Task Force on Pathology Manpower ASCP/CAP/APC).

A survey of chairmen of United States departments of pathology (97% response rate) augmented with data from the Association of American Medical Colleges shows that roughly two thirds (65%) of departmental faculty are physicians, the great majority of whom are pathologists. Most of the remainder are persons with solely the PhD degree (26.4% of faculty). The composition of departments of pathology in terms of age, gender, ethnic origin, academic rank, and tenure status is also reported. In contrast to a comparable survey performed 5 years previously, the present report shows that in 1989, departments of pathology contained (1) 20.6% more faculty positions, (2) a greater proportion of faculty members with a PhD degree, (3) greater numbers of open positions, and (4) a probable increase in the proportion of faculty that are female and that are of an ethnic minority.

Special report--National Manpower Survey of 1987. Manpower needs in community hospital and private laboratory practice of pathology.

A new survey of manpower requirements in the community hospital and private laboratory practice of pathology has been completed and analyzed. The survey used a new instrument, the National Pathology Manpower Database, which will be useful in conducting longitudinal surveys. This instrument will permit organized pathology to monitor changes in pathology manpower needs in the years ahead, which are likely to be fraught with change. The results of this survey foretell a significant deficit of pathologists in community hospital and private laboratory practice within the next five years.

Source of analytic variation in ligand assay: a study based on data from the 1976 and 1981 Basic Ligand Assay Surveys of the College of American Pathologists.

Six paired specimens distributed to laboratories in 1981 at approximately three-month intervals and four paired specimens distributed to laboratories in 1976 at intervals of three to nine months for analysis by the College of American Pathologists Survey form the basis for this study. Twelve of 37 (35%) of pool-analyte-technic combinations yielded significantly changed mean values in 1976, while 34 of 196 (17%) pool-analyte-technic combinations yielded significantly changed values in 1981. Probable instability in thyroxine and folate was demonstrated in the 1981 control pools. Precision generally continued to improve from 1976 to 1981. The poorest precision now is observed in the analysis of peptide hormones. A majority of the observed analytic variation during 1981 for most analytes relates to extralaboratory factors. Improvement in performance is largely dependent on intermanufacturer standardization of procedures and long-term maintenance of equivalence of the results of kit procedures by each manufacturer.

A statistical procedure for measuring and evaluating performance in interlaboratory comparison programs.

There are scientific and regulatory needs to measure individual laboratory performance on a series of challenges, for single analytes and for all analytes in a particular discipline. Because these needs must be met with a very limited amount of information, optimal statistics should be used to measure performance. Since punitive action could result from poor performance, there should be precise quantitative goals that can be measured directly with the performance statistic. Finally, it is important to limit the likelihood of falsely penalizing a laboratory, since the large majority of laboratories are not in need of regulatory action. A statistic is described that measures individual performance on quantitative interlaboratory proficiency tests. This statistic is based on actual error relative to the amount of error that is tolerable. It can be accumulated over several challenges (specimens tested as unknowns) to give an estimate of a participant's performance level for that analyte. It can also be accumulated across analytes to give scores for Survey mailings or for accumulated performance. Because the statistic measures error, it contains more information than does the percentage of acceptable results, and therefore has greater power to detect poor performance. The distribution of the statistic is described and tested for validity. Then, a procedure is presented to evaluate laboratories relative to a performance goal. The entire procedure is then tested with recent College of American Pathologists Chemistry Survey data.

Alternative statistical techniques to evaluate linearity.

With the increase in demand for linearity assessment, a wide variety of analysis techniques have been advocated. There is no consensus on optimal techniques. This article reviews different approaches that have been advocated by the College of American Pathologists, by the National Committee for Clinical Laboratory Standards, and by manufacturers of diagnostic methods and controls. This is not a review of all statistical techniques proposed for linearity assessment. I discuss four basic categories of methods, with the first and simplest being visual review. The second general approach includes the conventional statistical techniques based on least-squares regression; this includes an equation for the line and statistical tests for linearity and for curvature. The third general approach involves comparison of slopes for line segments, or "deltas." This approximates the visual assessment of linearity. The fourth approach involves comparing observed and expected values, with some allowance for differences. Comparisons can be made for observed single results, means of replicates, or components of variance. Allowances for error can be internal goals or goals that are recommended for clinical usefulness. Each approach has strengths in different aspects of linearity assessment, including intuitive appeal, statistical rigor, and objectivity. Similarly, each approach has limitations that are not always obvious.

Reference values and participant means as targets in proficiency testing.

Regulatory agencies will be placing greater reliance on the results of proficiency testing (PT) for determining licensing status of individual laboratories. This has caused a renewed interest in the process used by proficiency test providers for determining the correct result for each proficiency test challenge. Three general techniques have been proposed and would be allowed under the regulations: (1) participant-derived targets (means from a specific group of participants); (2) targets from a set of "reference" laboratories, from either a subset of participants or a selected group of experts using a rigorous experimental protocol; or (3) definitive values from a single source. The College of American Pathologists (CAP) has used all three techniques at different stages and for different purposes in the history of the CAP Surveys programs. This article reviews the early experiences of the CAP, the evolution of the current protocol, and activities to monitor the accuracy of target values. Participant-derived "consensus" results have been shown to be highly accurate and reliable. The CAP uses definitive methods at the National Institute for Standards and Technology and certified reference materials to monitor the validity of targets used in proficiency testing.

A nonparametric analysis method for evaluation of survey results. Application to ligand assay survey.

A nonparametric analysis method that does not depend on gaussian data distributions is proposed for evaluation of proficiency survey results. The proposed method also provides a mechanism for processing results qualitatively reported as "less than" or "greater than" pre-established limits of quantitation. The evaluation limits for acceptability are calculated to include the central 95% of all test results from all methods. Systematic differences in the levels of analyte concentrations caused by differences in analytical measurement systems are normalized by mathematically transforming the test results from each analytic method by dividing them by their method-specific group median. This nonparametric method was compared with the traditional mean +/- 2 SD limits using data collected for digoxin, free thyroxine, and quantitative chorionic gonadotropin measurement in the College of American Pathologists Ligand Assay Survey. The nonparametric method more accurately classified 5% of the results as "unacceptable." When more than 2.5% of the test results for a method were designated as "less than," no lower limit was used for evaluation and only 2.5% of results were classified as "unacceptably high." The current College of American Pathologists procedure favors analytical methods with larger coefficients of variation by setting wider limits of acceptability, while the proposed procedure favors methods with smaller coefficients of variation.

The usefulness of calibration verification and linearity surveys in predicting acceptable performance in graded proficiency tests.

OBJECTIVE: To assess the association between performance on graded chemistry surveys and evaluation of linearity and calibration in Linearity surveys. DESIGN: Data from Linearity Surveys (LN series) and from routine comprehensive College of American Pathologists chemistry surveys (all series) were used to evaluate the hypothesis that laboratories with nonlinear or univerified calibration would have a greater likelihood of unacceptable performance on comprehensive chemistry surveys. RESULTS: This study found that acceptable calibration verification evaluation is significantly related to acceptable rates for most analytes, including albumin, calcium, chloride, glucose, iron, magnesium, sodium, total bilirubin, uric acid, high-density lipoprotein cholesterol, triglycerides, alkaline phosphatase, alanine and aspartate aminotransferase, digoxin, gentamicin, phenobarbital, procainamide, and thyroxine. CONCLUSION: There is a consistent and strong relationship between calibration verification problems in the Linearity Surveys and failure rates in the College of American Pathologists chemistry surveys. Laboratories with poor calibration evaluations on Linearity Surveys have higher unacceptable rates on proficiency tests. Individual laboratories who were rated linear and whose calibration was verified by Linearity Surveys have lower unacceptable rates.

Determination of reference ranges for serum enzymes via a large interlaboratory survey.

We obtained enzyme data on normal individuals in conjunction with a large interlaboratory enzyme survey. For the 12 largest peer groups using unique methods, we found a simple relationship between the upper reference limits and the laboratories' results obtained from human-enzyme-supplemented survey serum. A conversion to a common base made possible the merging of data on the normal individuals and interconversion of results by diverse methods. We determined the upper reference limits for serum lactate dehydrogenase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and creatine kinase for approximately 8000 adult men and women believed to be in good health. Using a technique described here, we believe that the results can be transformed to user-specific units, and that the large data base can be applied to the many diverse enzyme methods in current use. With these data, enzyme survey participants will be able to estimate appropriate reference intervals for their particular method.

Some characteristics of the community practice of pathology in the United States. National Manpower Survey of 1987.

An evaluation of 629 pathologists engaged in community hospital and private laboratory practice and representing 601 pathology practices of varying size shows surprising uniformity in the distribution of professional effort. On average, pathologists in community practice distribute their effort as follows: surgical pathology, 34.6%; autopsy pathology, 6.7%; cytology, 8.8%; clinical pathology, 18.0%; teaching, 6.0%; research and development, 2.3%; laboratory administration, 17.5%; hospital administration, 2.9%; and other, 3.2%. The average community pathologist is male, 52 years of age, and a graduate of an American medical school (60%). When surveyed in 1986, community pathologists worked an average of 50 hours per week and retired at an average age of 62 years.

Proficiency testing of enzymes. Charting the way toward standardization.

Laboratories participating in the College of American Pathologists Enzyme Survey (ES) and Comprehensive Chemistry Survey used diverse methods for the same analyte, resulting in a considerable range of values for the commonly performed enzyme measurements. Nevertheless, with the techniques developed for the ES, both the short-term (within-mailing) and long-term (between-mailings) coefficients of variation (CVs) can be determined. The ten-year experience of the ES has shown improvement in the short-term CV; however, long-term stability of enzyme testing requires more effort on the part of the instrument and reagent suppliers and participating laboratories. A reference material with an International Federation of Clinical Chemistry-established aspartate aminotransferase value, National Bureau of Standards RM 8430, is now available and was sent to three large peer groups as part of a special study. Correction of the results to the RM 8430 aspartate aminotransferase value resulted in reducing the range of data from peers using the duPont aca but not from those using the American Monitor KDA or Technicon SMAC. Based on our experience with the ES, goals of 5% for the short-term CV and 10% for the long-term CV are proposed; they are achievable by most laboratories and meet medical needs for biochemical screening. Fixed criteria for the evaluation of enzyme results appear to be appropriate given the way most enzyme data are used clinically.

Multiprogram characterization of laboratory bias, precision, and total error. Proposal for improved assessment with shared external and expanded internal (regional) quality control pools.

We establish that, for the analytes aspartate aminotransferase, glucose, phosphorus, and potassium, there is significant correlation between laboratory performance as determined by College of American Pathologists-sponsored external (Surveys) and expanded internal (regional) quality control (Quality Assurance Service) programs. However, relatively low parametric and nonparametric correlation coefficients and significant departure of linear regression slopes from unity reflect major differences in the calculated parameters of absolute bias, precision, and total error obtained through internal and external quality control. Significantly better performance in both Surveys and the Quality Assurance Service was documented for laboratories participating in the College of American Pathologists Laboratory Accreditation Program. Multiple descriptors of laboratory quality, as indicated here, are superior in describing laboratory performance to proficiency testing alone. As a bridge between external and internal quality control, shared pools of quality control materials are described for use as unknown Survey challenges and subsequent distribution for regional quality control. Such programs, which can be configured to serve thousands of laboratories, could offer cost savings, better quality assurance, and improved characterization of laboratory performance by minimizing interprogram differences in control matrix and method classification and providing greater reliability of target values.