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Reference values for bronchoalveolar lavage in children.

Bronchoalveolar lavage (BAL) is a well-established diagnostic tool for the assessment of pulmonary diseases in adults. How BAL contributes to the diagnostic process in childhood lung diseases is less clear. One of the problems in interpreting BAL findings in children is that there are few reference data for BAL fluid constituents in children. This report addresses some of the technical problems of bronchoalveolar lavage in children and summarizes current knowledge on cellular and noncellular bronchoalveolar lavage fluid components in children without lung disease.

Antigens, Surface↗

Reference values for metacarpophalangeal joint stiffness in normals.

A new form of microprocessor-controlled arthrograph is described which measures stiffness parameters of the metacarpophalangeal joints of the index, middle, and ring fingers of both hands. The apparatus is simple and quick to use and gives reproducible results. The arthrograph is used to determine the reference limits for stiffness at the middle finger of the right hand in 128 normal subjects. It is found that incorporating information on the subject's finger circumference allows a much improved precision to be achieved, but the precision is not further enhanced by including details of age and sex.

Adolescent↗

Impact of subgroup prevalences on partitioning of Gaussian-distributed reference values.

BACKGROUND: The aims of this report were to examine how unequal subgroup prevalences in the source population may affect reference interval partitioning decisions and to develop generally applicable guidelines for partitioning gaussian-distributed data. METHODS: We recently proposed a new model for partitioning reference intervals when the underlying data distribution is gaussian. This model is based on controlling the proportions of the subgroup distributions that fall outside each of the common reference limits, using the distances between the reference limits of the subgroup distributions as functions to these proportions. We examine the significance of the unequal prevalence effect for the partitioning problem and quantify it for distance partitioning criteria by deriving analytical expressions to express these criteria as a function of the ratio of prevalences. An application example, illustrating various aspects of the importance of the prevalence effect, is also presented. RESULTS: Dramatic shrinkage of the critical distances between reference limits of the subgroups needed for partitioning was observed as the ratio of prevalences, the larger one divided by the smaller one, was increased from unity. Because of this shrinkage, the same critical distances are not valid for all ratios of prevalences, but specific critical distances should be used for each particular value of this ratio. Although proportion criteria used in determining the need for reference interval partitioning are not dependent on the prevalence effect, this effect should be accounted for when these criteria are being applied by adjusting the sample sizes of the subgroups to make them correspond to the ratio of prevalences. CONCLUSIONS: The prevalences of subgroups in the reference population should be known and observed in the calculations for every reference interval study, irrespective of whether distance or proportion criteria are being used to determine the need for reference interval partitioning. We present detailed methods to account for the prevalences when applying each of these types of criteria. Analytical expressions for the distance criteria, to be used when high precision is needed, and approximate distances, to be used in practical work, are derived. General guidelines for partitioning gaussian distributed data are presented. Following these guidelines and using the new model, we suggest that partitioning can be performed more reliably than with any of the earlier models because the new model not only offers an improved correspondence between the critical distances and the critical proportions, but also accounts for the prevalence effect.

Biometry↗

Metabolic and cellular profile testing in calves under feedlot conditions: protein fractions and lactate dehydrogenase isoenzymes--reference values.

Serum protein and lactate dehydrogenase (LDH) isoenzyme values were determined for frozen serum samples from crossbred yearling feedlot cattle on feed for 56 days. The mean percentage values for serum protein components from 114 samples were: albumin, 46.5; alpha-globulin, 10.4; beta-globulin, 18.7; gamma-globulin, 23.8. For LDH isoenzymes, they were: LDH1, 36.5; LDH2, 24.7; LDH3, 16.9; LDH4, 12.0; LDH5, 9.1. These values are compared with values from dairy cattle.

Animal Feed↗