Interdecile Range Research Articles

Plasma cytokine levels predict mortality in patients with acute renal failure

Critically ill patients with acute renal failure (ARF) experience a high mortality rate. Animal and human studies suggest that proinflammatory cytokines lead to the development of a systemic inflammatory response syndrome (SIRS), which is temporally followed by a counter anti-inflammatory response syndrome (CARS). This process has not been specifically described in critically ill patients with ARF. The Program to Improve Care in Acute Renal Disease (PICARD) is a prospective, multicenter cohort study designed to examine the natural history, practice patterns, and outcomes of treatment in critically ill patients with ARF. In a subset of 98 patients with ARF, we measured plasma proinflammatory cytokines [interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha)], the acute-phase reactant C-reactive protein (CRP), and the anti-inflammatory cytokine IL-10 at study enrollment and over the course of illness. When compared with healthy subjects and end-stage renal disease patients on maintenance hemodialysis, patients with ARF had significantly higher plasma levels of all measured cytokines. Additionally, the proinflammatory cytokines IL-6 and IL-8 were significantly higher in nonsurvivors versus survivors [median 234.7 (interdecile range 64.8 to 1775.9) pg/mL vs. 113.5 (46.1 to 419.3) pg/mL, P= 0.02 for IL-6; 35.5 (14.1 to 237.9) pg/mL vs. 21.2 (8.5 to 87.1) pg/mL, P= 0.03 for IL-8]. The anti-inflammatory cytokine IL-10 was also significantly higher in nonsurvivors [3.1 (0.5 to 41.9) pg/mL vs. 2.4 (0.5 to 16.9) pg/mL, P= 0.04]. For each natural log unit increase in the levels of IL-6, IL-8, and IL-10, the odds of death increased by 65%, 54%, and 34%, respectively, corresponding to increases in relative risk of approximately 30%, 25%, and 15%. The presence or absence of SIRS or sepsis was not a major determinant of plasma cytokine concentration in this group of patients. There is evidence of ongoing SIRS with concomitant CARS in critically ill patients with ARF, with higher levels of plasma IL-6, IL-8, and IL-10 in patients with ARF who die during hospitalization. Strategies to modulate inflammation must take into account the complex cytokine biology in patients with established ARF.

A survey of women's experiences of vaginal loss from 24 hours to three months after childbirth (the BLiPP study)

Objective: to describe the range of normal vaginal loss as reported by women from 24 hours after delivery until three months postnatally. Setting: two health districts in the south of England. Methods: a prospective survey of women's experiences and expectations of the duration, amount and colour of vaginal loss after childbirth. The term vaginal loss includes all types of fluid loss from the vagina following childbirth. Findings: five hundred and twenty-four women were recruited to the survey in 1995. Vaginal loss, as reported by the women, was considerably more varied in duration, amount and colour than descriptions in current midwifery textbooks. The median number of days reported for the duration of vaginal loss was 21 days and the interdecile range (10th to 90th percentile) was 10–42 days. For colour of lochia, women overall reported their vaginal loss to be more predominantly red/brown in colour and the traditional descriptions of the timing and colour phases of lochia rubra, serosa and alba are not supported by the majority of the women's experiences. Primiparous women were significantly more likely to report feelings of surprise or shock about their experiences of vaginal blood loss after the birth (odds ratio 4 [95% Confidence Interval 2–9]). Seven primiparous women (2%) were unaware that they would have a blood loss at all after the birth. Implications for practice: the findings from this survey have been used to develop information leaflets for women and health professionals about vaginal loss following childbirth. These leaflets include descriptions of normal ranges for the colour, amount and duration of vaginal loss in the first three months after childbirth.

On the efficiencies of some common quick estimators

The quick estimators of location and scale have broad applications and are widely used. For a variety of symmetric populations we obtain the quantiles and the weights for which the asymptotic variances of the quick estimators are minimum. These optimal quick estimators are then used to obtain the asymptotic relative efficiencies of the commonly used estimators such as trimean. gastwirth. median, midrange. and interquartile range with respect to the optimal quick estimators in order to determine a choice among them and to check whether they are unacceptably poor. In the process it is seen that the interquartile range is the optimal quick estimator of scale for Cauchy populations; but the interdecile range is in general preferable. Also the optimal estimator of the location for the logistic distribution puts weights 0.3 on each of the two quartiles and 0.4 on the median. It is shown that for the symmetric distributions, such as the beta and Tukey- lambda with [d] > 0, which have finite support and short tails, i.e. the tail exponents (Parzen, 1979) satisfy [d] < 1, the midrange and the range are the optimal quick estimators of location and scale respectively if [d] < 1/2. The class of such distributions Include the distributions with high discontinuous tails, e.g. Tukey-lambda with [d] > 1, as well as some distributions with p.d.f.'s going to zero at the ends of the finite support, such as Tukey-lambda with 1/2 < [d] < 1. As a byproduct an interesting tail correspondence between beta and Tukey-lambda distributions is seen.

Validity of self reported data on injury prevention behavior: lessons from observational and self reported surveys of safety belt use in the US.

To examine the validity of self reported data on safety belt use and to consider the implications for research on injury prevention behaviors. 1992 and 1993 self reported data on safety belt use were obtained from the Behavioral Risk Factor Surveillance System and observational data were obtained from the National Highway Traffic Safety Administrations for 49 states in 1992 and 50 states in 1993. The ratio of self reported to observed belt use was calculated for each state, and linear regression models were used to examine the association between the two methods. There was variation between states, but the overall median ratio of self reported to observed safety belt use was 1.05 in 1992 (interdecile range 0.87-1.36) and 1.02 in 1993 (interdecile range 0.87-1.31). Self reports were substantially higher in southern states and in states with the lowest levels of observed use. Linear regression models indicated a moderately strong association between state estimates using both methods. For every percentage point increase in self reported data in 1993, observed safety belt use increased by 0.95 percentage point. In the aggregate, self reported estimates were only 2% to 5% higher than observed estimates. This is a substantial improvement from previous studies. This is probably due to the increased prevalence of safety belt use and the declining effects of social desirability on self reported use. In general, the validity of self reported estimates of socially desirable injury prevention behaviors will be higher when the actual prevalence of the behavior is higher, but lower when this is not true.

ABILITY OF THE CANADIAN GRADING SYSTEM TO SEGREGATE CANADIAN WHEAT BY ALPHA-AMYLASE LEVELS

A survey of falling number values in carlots of most classes of wheat (Triticum aestivum L.) was undertaken between October 1985 and February 1986. The purpose was to assess the effectiveness of the present visual grading system for segregating wheat by α-amylase levels as indicated by the falling number method. In addition, the survey was used to pinpoint areas of the western Canadian prairies from which sprout-damaged wheat originated. CWRS wheat had increasing amounts of α-amylase (lower falling number values) with lower grade. The values obtained for a given grade remained relatively constant over the entire testing period. Furthermore, the interdecile range in falling number values for the samples in a particular grade was only around 110 s. Other classes of wheat (CPS, CWSWS, CWRW) exhibited lower falling number values than CWRS wheat, reflecting increased susceptibility to preharvest sprouting and/or different tolerances for maximum percentage of sprouted kernels. Over the testing period, certain grades of some classes also varied more than CWRS wheats in falling number values. The interdecile range in values for these classes was very large and there was considerable overlap in falling number between grades. This suggests that some form of α-amylase testing could be used to advantage for these classes of wheat to ensure more consistent and uniform quality.Key words: Wheat, alpha-amylase, grading, falling number

Understanding Middleton's Canonical Formula for Class a Noise

This paper develops an intuitive understanding of the meaning and implications of Middleton's canonical formula for Class A noise. The probability density function (pdf) for noise in decibels is derived, and each of the parameters has a clear physical meaning. The effects of parameter variation on the pdf are shown graphically. The canonical Class A formula predicts that the interdecile range of non- Gaussian noise (structured interference) is less than about 30 dB. A simple scenario that produces canonical Class A interference is described. The limited interdecile range of the interference forces the interfering sources in the simple scenario to be located within a limited range of distances. Thus the strictly canonical formula for Class A noise is inadequate for modeling many physical situations.

Concentration of analytical data as part of data processing in trace element analysis

Statistical data evaluation in trace element analysis was mainly influenced by the Normal Law of Error, which is based on the assumption of a Gaussian normal distribution. Supposing that the analytical error of the trace element concentration is negligibly small compared with its true variations in nature, skew distributions may become more important than normal ones. Often, but not always, the lognormal distribution is a good approximation of the skew distribution. Careful investigation of the type of distribution before starting data evaluation in trace element analysis is still frequently overlooked today. In this Department, data concentration is performed on a routine basis by two programmes ZCH-2 and ZCH-3/1. They include a) investigation of the type of distribution by drawing the histogrammes, probability plot for normal and lognormal distribution as Hazen's straight lines, Kolmogorov-Smirnov- and Cramer- van Mises goodness-of-fit tests as well as skewness and kurtosis. Outliers of the normal distribution can be eliminated b) by t-, Nalimov's r-, Grubb's and Dixon's tests. c) As central values for data location, the arithmetic, geometric, and harmonic means and median are calculated. d) The dispersion around the mean is characterized by variance, standard deviation of a single value as well as the mean, relative coefficient of variation, mean deviation from the arithmetic mean, geometric standard deviation, range and 80% inter-decile range. Confidence intervals are given for the arithmetic mean, geometric mean and median. Typical problems of data concentration are the deviation from the normal distribution, comparison of different mean values, outlier elimination, concentrations below detection limit, homogeneity and heterogeneity of the data sample. They are discussed for examples of data series from one of the author's laboratories, e.g. trace element concentrations in air, lead content in dental calculus, toxic heavy metal leaching from ceramic ware and gamma dose rates from an area of higher natural radioactivity in the Federal Republic of Germany. As a conclusion, it is emphasized that the trace element analyst should overcome the “Mystery of the Normal and Quasi-normal Distribution” and include skew data distributions and their statistical treatment into his repertoire of routine procedures as well as in his way of thinking.

Heterozygote detection in angiokeratoma corporis diffusum (Anderson-Fabry disease). Studies on plasma, leucocytes, and hair follicles.

Heterozygote detection for angiokeratoma corporis diffusum (Anderson-Fabry disease, ACD), an X-linked disorder of glycosphingolipid metabolism was examined using alpha-galactosidase activity, an alpha-galactosidase/beta-galactosidase activity ratios (alpha/beta ratio) in leucocytes, plasma, and hair follicles; For leucocytes, 22 obligate heterozygotes, 25 suspected heterozygotes, and 47 control subjects were studied, while for plasma, the groups were 17 obligate heterozygotes and 35 controls. The alpha/beta ratio in plasma and leucocytes was clearly a better discriminator between obligate heterozygotes and controls than alpha-galactosidase activity alone, but still failed to detect 3 obligates with leucocytes and 2 with plasma. Discrimination was not improved by joint use of plasma and leucocyte alpha/beta ratios, but was improved by measurement of hair-follicle alpha/beta ratios. The interdecile range of log (alpha-galactosidase/beta-galactosidase activity) in 20 hair follicles from each of 4 obligate and 7 suspected heterozygotes was clearly different from 11 control subjects. Accordingly, for rapid screening for carriers of ACD, we recommend use of leucocyte or plasma alpha/beta ratios which should detect greater than 85% of heterozygotes. When results are equivocal, and ancillary information suggests heterozygous status, the more time-consuming measurement of hair-follicle alpha/beta ratios is a useful additional test.

Swimming Speeds of Sockeye and Coho Salmon on Spawning Migration

The speed at which sockeye and coho salmon swim while on spawning migration through a river was determined by direct timing of individual fish over measured river sections and by measurement of opposing water velocities. Migration was accomplished by two locomotory patterns: dart and steady swimming. For steady swimming there was a critical opposing water velocity from 1.1 to 1.7 ft/sec (mean 1.4 ft/sec). Against currents slower than the critical range steady swimming to a maximum speed of approximately 3.4 ft/sec (1.7 body lengths (L)/sec) was sustained through the observation areas, but against currents faster than the critical range salmon broke into position-holding behaviour at intervals. The calculated inter-decile range of swimming speeds (excluding slowest 10% and fastest 10%) against water velocities below the critical range was 1.75–3.18 ft/sec (0.9–1.7 L/sec) for sockeye salmon and 1.70–3.14 ft/sec (0.9–1.7 L/sec) for coho salmon. These swimming speeds were below maximum sustained values which have been determined experimentally.

Growth Rate and Variance in the Razor Clam

In discussing the growth of the razor clam (Siliqua patula, Dixon) we have pointed out a correlation between the absolute growth rate and the variability as measured by “D”, the interdecile range.1 In this work we used samples of clams representing the normal population of the respective beds. For this reason the numbers in the older age groups were small, and it was not possible to determine the presence or extent of selective mortality which might greatly affect the relation between growth and variance.Recently we have selected 2 samples of clams, one from Little River, Humboldt County, California, containing 300 specimens, all 7 years of age, and one from Hallo Bay on the Alaskan Peninsula, containing 76 specimens 13 years old. A complete growth record was obtained for each individual by measuring the consecutive annual rings. The mean length and the variance were calculated for each year for the 2 localities, and the tenth, the fiftieth (median), and the ninetieth percentiles were determined for the d...