Duplication of the CYP21A2 gene complicates mutation analysis of steroid 21-hydroxylase deficiency: characteristics of three unusual haplotypes.

Steroid 21-hydroxylase deficiency, the primary cause of congenital adrenal hyperplasia, is caused by defects of the CYP21A2 gene. As a complement to hormonal measurements, mutation analysis of CYP21A2 is an important tool in the diagnosis of steroid 21-hydroxylase deficiency. Contemporary mutation-detection protocols based on the polymerase chain reaction often depend on the assumption that no more than one CYP21A2 gene is present on each chromosome 6.

Carriership of a defective tenascin-X gene in steroid 21-hydroxylase deficiency patients: TNXB -TNXA hybrids in apparent large-scale gene conversions.

Steroid 21-hydroxylase deficiency is caused by a defect in the CYP21A2 gene. CYP21A2, the adjacent complement C4 gene and parts of the flanking genes RP1 and TNXB constitute a tandemly duplicated arrangement in the central (class III) region of the major histocompatibility complex. The typical number of repeats of the CYP21/C4 region is two, with one repeat carrying CYP21A2 and the other carrying the highly homologous pseudogene CYP21A1P.

CYP21 and CYP21P variability in steroid 21-hydroxylase deficiency patients and in the general population in the Netherlands.

Steroid 21-hydroxylase deficiency is caused by defectiveness of the CYP21 gene. Such defects have presumably originated from interactions with the nearby CYP21P pseudogene during evolution. We studied these mechanisms by comparing the genetic variability of CYP21, CYP21P, and CYP21P/CYP21 hybrids (resulting from large-scale rearrangements) at eight mutation sites in a group of Dutch steroid 21-hydroxylase deficiency patients, their family members, and controls.

Aldosterone production despite absence or defectiveness of the CYP21 genes in two patients with salt-losing congenital adrenal hyperplasia caused by steroid 21-hydroxylase deficiency.

Aldosterone and cortisol were found in plasma samples from two patients with salt-losing congenital adrenal hyperplasia caused by steroid 21-hydroxylase deficiency. One patient had a CYP21 gene deletion on one chromosome and a mutation causing erroneous mRNA splicing on the other. The other patient had a CYP21 gene deletion on one chromosome and a large scale conversion of CYP21 to CYP21P on the other.

Energy utilization and growth in breast-fed and formula-fed infants measured prospectively during the first year of life.

This study is the first to report approximations of energy requirements for male and female breast-fed and formula-fed infants based on individual estimates of total daily energy expenditure (TDEE) and energy deposition derived from total body fat (TBF) and fat-free mass (FFM) gain as determined by total-body electrical conductivity. In 46 healthy, full-term infants the effect of > or = 4 mo of exclusive breast-feeding compared with formula feeding on macronutrient and energy intake, TDEE, energy deposition, and growth were investigated prospectively. Metabolizable energy intake (MEI) was assessed from macronutrient intake by test weighing (MEI-TW) and from the sum of TDEE and energy deposition (MEI-Pred).

Structural position and amount of palmitic acid in infant formulas: effects on fat, fatty acid, and mineral balance.

The structure of the triglycerides (TG) in human milk (HM) differs from those of vegetable oils used in infant formulas. In HM, palmitic acid is predominantly esterified to the center or beta-position of the TG, in vegetable oil, it is mainly at the external or alpha-positions. These differences in configuration affect intestinal fat absorption.

The very low birth weight premature infant is capable of synthesizing arachidonic and docosahexaenoic acids from linoleic and linolenic acids.

Infants fed formulas devoid of long-chain polyunsaturated fatty acids (LCP) exhibit low plasma LCP concentrations and have poorer retinal and neurologic development in comparison with their human milk-fed counterparts. It is not known whether the low plasma LCP concentrations result from an impaired biosynthetic capacity, a high need or a low dietary intake. With stable isotope technology and high sensitivity tracer detection using gas chromatography-isotope ratio mass spectrometry we measured the conversion of [13C]linoleic acid (C18:2n-6) and [13C]linolenic acid (C18:3n-3) into their longer chain derivatives in five 1-mo-old formula-fed preterm infants (birth weight 1.

Standards for total body fat and fat-free mass in infants.

Data on body composition in conjunction with reference centiles are helpful in identifying the severity of growth and nutritional disorders in infancy and for evaluating the adequacy of treatment given during this important period of rapid growth. Total body fat (TBF) and fat-free mass (FFM) were estimated from total body electrical conductivity (TBEC) measurements in 423 healthy term Caucasian infants, aged 14-379 days. Cross sectional age, weight, and length related centile standards are presented for TBF and FFM.

Density of eosinophils reflects activity of disease in allergic asthmatic children.

Background: Low density eosinophils are more prominent in asthmatic patients compared with healthy subjects. LDE are metabolically more active and produce more tissue-injuring and spasmogenic proteins than normal eosinophils.

Objective And Methods: With a method providing information about eosinophils of 12 different densities we were able to study eosinophil density characteristics in 24 young patients in detail with allergic asthma in a stable phase, and in 21 patients after a bronchial allergen challenge.

Effect of dietary triacylglycerol fatty acid positional distribution on plasma lipid classes and their fatty acid composition in preterm infants.

Seven premature infants were each fed, for 1 wk in a crossover design. The beta formula contained triacylglycerols resembling the stereoisomeric structure of human milk fat (25.4% by wt 16:0, 76.

Measurement of fat-free mass in infants.

Body composition data are important for adequate monitoring of growth and nutritional status in infants. 18O Isotope dilution techniques (ID18-O) are widely used to estimate total body water (TBW) and calculate fat-free mass (FFM). A problem of isotope dilution is an underestimation of TBW by the extrapolation to t = O approach and an overestimation of TBW by the plateau approach.

Body fat and fat-free mass in infants: new and classic anthropometric indexes and prediction equations compared with total-body electrical conductivity.

Anthropometry is frequently used for nutritional assessment. Little is known in infants about the validity of anthropometric measurements in relation to whole-body fat (TBF) and fat-free mass (FFM) composition. We compared TBF and FFM estimations by total-body electrical conductivity (TOBEC) with anthropometry in 435 healthy infants ages 21-365 d.

Feeding premature newborn infants palmitic acid in amounts and stereoisomeric position similar to that of human milk: effects on fat and mineral balance.

The effect of the structure of human milk triglycerides on intestinal fat absorption remains controversial. Twelve infants were each fed, for 1 wk in a crossover design, two formulas that differed only in triglyceride configuration. The "beta" formula contained triglycerides similar to those in human milk (26% palmitic acid, esterified predominantly to the sn-2 position) whereas in the "alpha" formula, which contained triglycerides similar to those in formulas currently marketed, palmitate was mainly at the sn-1,3 positions.

Whole-body protein turnover in preterm appropriate for gestational age and small for gestational age infants: comparison of [15N]glycine and [1-(13)C]leucine administered simultaneously.

Measurements of whole-body protein turnover in preterm infants have been made using different stable isotope methods. Large variation in results has been found, which could be due to different clinical conditions and/or the use of different tracers. We studied 14 appropriate for gestational age and nine small for gestational age orally fed preterm infants using [15N]glycine and [1-(13)C]leucine simultaneously, which allowed us to make a comparison of commonly used methods to calculate whole-body protein turnover.

Quantitative assessment of infant body fat by anthropometry and total-body electrical conductivity.

Measurement of total-body electrical conductivity (TOBEC) has emerged as a rapid, safe, and reproducible method for estimation of infant total body fat (TBF). Agreement of two anthropometric methods [by Dauncey et al (1977) and Weststrate et al (1989)] with TOBEC-TBF was assessed in 435 healthy infants aged 21-365 d. Dauncey-TBF correlated with TOBEC-TBF by r2 = 0.

Total body electrical conductivity measurements: an evaluation of current instrumentation for infants.

Quantitation of the body's fat and learn masses is an important component of nutritional assessment. Such measurements, however, are difficult to conduct routinely in infants due to the numerous limitations of traditional methods. The application of total body electrical conductivity measurements for quantitating fat-free mass (FFM) overcomes many of these limitations.

Conversion of octanoic acid into long-chain saturated fatty acids in premature infants fed a formula containing medium-chain triglycerides.

A large number of very-low-birth weight infants are fed formulas containing medium-chain triglycerides (MCT) to enhance fat and calcium absorption. Studies are available on the intestinal absorption of MCT, which is nearly complete, but uncertainties exist on the metabolic fate of octanoic acid, the major component of MCT. Oxidation accounts for approximately 50% of the dietary intake, and losses as dicarboxylic acids in the urine are negligible.

A practical approach to the detection of androgen receptor gene mutations and pedigree analysis in families with x-linked androgen insensitivity.

Androgen insensitivity syndrome (AIS) is an X-linked disorder in which defects in the androgen receptor gene have prevented the normal development of both internal and external male structures in 46,XY individuals. This survey reports the analysis of 11 AIS subjects. The androgen receptor gene of these subjects was analyzed using polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis and sequencing or sequencing of PCR-amplified androgen receptor gene fragments alone.

The effect of alterations in physical and chemical characteristics on TOBEC-derived body composition estimates: validation with non-human models.

The measurement of total-body electrical conductivity (TOBEC) has become one of the standard methods for the estimation of body composition in infants. We investigated, using non-human models, the effect on the accuracy of TOBEC-derived body composition estimates of alterations in physical and chemical characteristics of the fat-free mass (FFM). The effect of electrolyte type, concentration and volume on TOBEC was determined using 2, 3 and 51 solutions of six different chlorides and sodium bicarbonate.

Differential splicing of human androgen receptor pre-mRNA in X-linked Reifenstein syndrome, because of a deletion involving a putative branch site.

The analysis of the androgen receptor (AR) gene, mRNA, and protein in a subject with X-linked Reifenstein syndrome (partial androgen insensitivity) is reported. The presence of two mature AR transcripts in genital skin fibroblasts of the patient is established, and, by reverse transcriptase-PCR and RNase transcription analysis, the wild-type transcript and a transcript in which exon 3 sequences are absent without disruption of the translational reading frame are identified. Sequencing and hybridization analysis show a deletion of > 6 kb in intron 2 of the human AR gene, starting 18 bp upstream of exon 3.

Effect of dexamethasone on protein metabolism in infants with bronchopulmonary dysplasia.

Corticosteroids result in protein wasting in human adults and rats. To determine to what extent this therapy affects protein metabolism in preterm infants, we studied 10 very low birth weight infants before a gradually tapered dexamethasone regimen was started and at day 4 of treatment (dexamethasone dosage 0.35 +/- 0.

Glucose kinetics and glucoregulatory hormone levels in ventilated preterm infants on the first day of life.

Glucose production and oxidation were measured in ventilated preterm appropriate-for-gestational-age and small-for-gestational-age infants on the first day of life. Using a new technique of NaH13CO3 infusion followed by a [U-13C]glucose infusion, we measured glucose oxidation rates without measuring the CO2 production rate. Infants were studied at 18 +/- 4 h (mean +/- 1 SD) of life and received parenterally administered glucose only (4.