439 research outputs found
Nonclassic lipoid congenital adrenal hyperplasia masquerading as familial glucocorticoid deficiency
Context: Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder resulting from resistance to the action of ACTH on the adrenal cortex. Affected individuals are deficient in cortisol and, if untreated, are likely to succumb to hypoglycemia and/or overwhelming infection. Mutations of the ACTH receptor (MC2R) and the melanocortin 2 receptor accessory protein (MRAP), FGD types 1 and 2 respectively, account for approximately 45% of cases.
Objective: A locus on chromosome 8 has previously been linked to the disease in three families, but no underlying gene defect has to date been identified.
Design: The study design comprised single-nucleotide polymorphism genotyping and mutation detection.
Setting: The study was conducted at secondary and tertiary referral centers.
Patients: Eighty probands from families referred for investigation of the genetic cause of FGD participated in the study.
Interventions: There were no interventions.
Results: Analysis by single-nucleotide polymorphism array of the genotype of one individual with FGD previously linked to chromosome 8 revealed a large region of homozygosity encompassing the steroidogenic acute regulatory protein gene, STAR. We identified homozygous STAR mutations in this patient and his affected siblings. Screening of our total FGD patient cohort revealed homozygous STAR mutations in a further nine individuals from four other families.
Conclusions: Mutations in STAR usually cause lipoid congenital adrenal hyperplasia, a disorder characterized by both gonadal and adrenal steroid deficiency. Our results demonstrate that certain mutations in STAR (R192C and the previously reported R188C) can present with a phenotype indistinguishable from that seen in FGD
Thermal transport properties of magnetic refrigerants La(FexSi1-x)13 and their hydrides, and Gd5Si2Ge2 and MnAs
Advances in Thick GEM-like gaseous electron multipliers. Part I: atmospheric pressure operation
Thick GEM-like (THGEM) gaseous electron multipliers are made of standard
printed-circuit board perforated with sub-millimeter diameter holes, etched at
their rims. Effective gas multiplication factors of 100000 and 10000000 and
fast pulses in the few nanosecond rise-time scale were reached in single- and
cascaded double-THGEM elements, in atmospheric-pressure standard gas mixtures
with single photoelectrons. High single-electron detection efficiency is
obtained in photon detectors combining THGEMs and semitransparent UV-sensitive
CsI photocathodes or reflective ones deposited on the top THGEM face; the
latter benefits of a reduced sensitivity to ionizing background radiation.
Stable operation was recorded with photoelectron fluxes exceeding MHz/mm2. The
properties and some potential applications of these simple and robust
multipliers are discussed.Comment: 41 pages, 27 figures. Submitted to Nucl. Instr. and Meth. A, Dec 21,
200
High-resolution microwave frequency dissemination on an 86-km urban optical link
We report the first demonstration of a long-distance ultra stable frequency
dissemination in the microwave range. A 9.15 GHz signal is transferred through
a 86-km urban optical link with a fractional frequency stability of 1.3x10-15
at 1 s integration time and below 10-18 at one day. The optical link phase
noise compensation is performed with a round-trip method. To achieve such a
result we implement light polarisation scrambling and dispersion compensation.
This link outperforms all the previous radiofrequency links and compares well
with recently demonstrated full optical links.Comment: 11 pages, 5 figure
Giant isotropic magnetostriction of itinerant-electron metamagnetic La(Fe0.88Si0.12)13Hy compounds
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