Human milk oligosaccharide blood group epitopes and innate immune protection against campylobacter and calicivirus diarrhea in breastfed infants.
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Blood Group Antigens↗
Biomedical subjects
M Altaye
Publications and source records attributed to M Altaye.
A general goodness-of-fit approach for inference procedures concerning the kappa statistic.
The kappa statistic is frequently used as a measure of agreement among two or more raters. Although considerable research on statistical inferences for this statistic has been published for the case of two raters and a binary outcome, relatively little work has appeared on inference problems for the case of multiple raters and/or polytomous nominal outcome categories. In this paper we propose a new procedure for constructing inferences for the kappa statistic that may be applied to this general case. The procedure is based on a chi-square goodness-of-fit test as applied to the Dirichlet multinomial model, and is a natural extension of previously proposed procedures that apply to more restricted cases. A simulation study shows that the new procedure provides confidence interval coverage levels and type I error rates close to nominal over a wide range of parameter combinations. We also present a sample size formula which may be used to determine the required number of subjects and raters for a given number of outcome categories.
Bias↗
Fucosylated human milk oligosaccharides vary between individuals and over the course of lactation.
Specific human milk oligosaccharides, especially fucosylated neutral oligosaccharides, protect infants against specific microbial pathogens. To study the concentrations of individual neutral oligosaccharides during lactation, a total of 84 milk samples were obtained from 12 women at 7 time periods during weeks 1-49 postpartum. The neutral oligosaccharides from each sample were isolated, perbenzoylated, resolved, and quantified by reversed-phase high-performance liquid chromatography. The resultant oligosaccharide peaks, identified by co-elution with authentic standards and mass spectrometry, ranged in size from tri- to octasaccharides. The total concentration of oligosaccharides declined over the course of lactation; the mean concentration at 1 year was less than half that in the first few weeks postpartum. One of the 12 donors produced milk fucosyloligosaccharides that were essentially devoid of alpha1,2 linkages (but contained alpha1,3- and alpha1,4-linked fucose) until late in lactation, consistent with the nonsecretor phenotype. In milk samples from the remaining 11 donors, fucosyloligosaccharides containing alpha1,2-linked fucose were prevalent, and their profiles were distinct from those of fucosyloligosaccharides devoid of alpha1,2-linked fucose. The ratio of alpha1,2-linked oligosaccharide concentrations to oligosaccharides devoid of alpha1,2-linked fucose changed during the first year of lactation from 5:1 to 1:1. Furthermore, the absolute and the relative concentrations of individual oligosaccharides varied substantially, both between individual donors and over the course of lactation for each individual. The patterns of milk oligosaccharides among individuals suggest the existence of many genotype subpopulations. This variation in individual oligosaccharide concentrations suggests that the protective activities of human milk could also vary among individuals and during lactation.
Carbohydrate Conformation↗
Inference procedures for assessing interobserver agreement among multiple raters.
We propose a new procedure for constructing inferences about a measure of interobserver agreement in studies involving a binary outcome and multiple raters. The proposed procedure, based on a chi-square goodness-of-fit test as applied to the correlated binomial model (Bahadur, 1961, in Studies in Item Analysis and Prediction, 158-176), is an extension of the goodness-of-fit procedure developed by Donner and Eliasziw (1992, Statistics in Medicine 11, 1511-1519) for the case of two raters. The new procedure is shown to provide confidence-interval coverage levels that are close to nominal over a wide range of parameter combinations. The procedure also provides a sample-size formula that may be used to determine the required number of subjects and raters for such studies.
Binomial Distribution↗
Effect of method of defining the active patient population on measured immunization rates in predominantly Medicaid and non-Medicaid practices.
OBJECTIVE: To examine the effect of patient selection criteria on immunization practice assessment outcomes. METHODS: In 3 high- (50%-85%) and 7 low- (<25%) Medicaid pediatric practices in urban eastern Virginia, we assessed immunization rates of children 12 and 24 months old comparing the standard criteria (charts in the active files excluding those that documented the child moved or went elsewhere) with 3 alternative criteria for selecting active patients: 1) follow-up: the chart contained a complete immunization record or the patient was found to be active in the practice through follow-up contact by phone or mail; 2) seen in the past year: the chart indicated that the patient was seen in the practice in the past year; 3) consecutive: patients that were seen consecutively for any reason. RESULTS: Of the 1823 charts assessed in the high- and low-Medicaid practices, follow-up identified 61% and 83% as active patients; 78% and 95% were ever seen in the past year. At 24 months, mean practice immunization rates were lower for standard (70%) than all 3 alternative criteria (78%-86%). Immunization rate differences between standard and alternative criteria were greater in high- (17%-23%) than low-Medicaid practices (5%-13%). CONCLUSION: The standard for practice assessment should be based on a consistent definition of active patients as the immunization rate denominator.
Ambulatory Care↗