Search NASA⌕ Search
Home/Archive/NASA NTRS

NASA NTRS · 20040089531

Current methods and advances in bone densitometry

Guglielmi, G.·Gluer, C. C.·Majumdar, S.·Blunt, B. A.·Genant, H. K.
View original source ↗Export metadata ↓

Abstract

Bone mass is the primary, although not the only, determinant of fracture. Over the past few years a number of noninvasive techniques have been developed to more sensitively quantitate bone mass. These include single and dual photon absorptiometry (SPA and DPA), single and dual X-ray absorptiometry (SXA and DXA) and quantitative computed tomography (QCT). While differing in anatomic sites measured and in their estimates of precision, accuracy, and fracture discrimination, all of these methods provide clinically useful measurements of skeletal status. It is the intent of this review to discuss the pros and cons of these techniques and to present the new applications of ultrasound (US) and magnetic resonance (MRI) in the detection and management of osteoporosis.

Explore related subjects

Review, AcademicReviewNon-NASA CenterNASA Discipline MusculoskeletalOsteoporosis/diagnosis/radiography/ultrasonographyBone Density/physiologyDensitometry/instrumentation/methods/trendsDensitometry, X-RayMagnetic Resonance ImagingBone and Bones/pathology/radiography/ultrasonographyComparative StudyAbsorptiometry, PhotonTomography Scanners, X-Ray ComputedUltrasonography

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Guglielmi, G., Gluer, C. C., Majumdar, S., Blunt, B. A., Genant, H. K.. 1995-01-01. Current methods and advances in bone densitometry. https://ntrs.nasa.gov/citations/20040089531

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

NASA NTRS2003

The evolution of transcriptional regulation in eukaryotes

Gene expression is central to the genotype-phenotype relationship in all organisms, and it is an important component of the genetic basis for evolutionary change in diverse aspects of phenotype. However, the evolution of transcriptional regulation remains understudied and poorly understood. Here we review the evolutionary dynamics of promoter, or cis-regulatory, sequences and the evolutionary mechanisms that shape them. Existing evidence indicates that populations harbor extensive genetic variation in promoter sequences, that a substantial fraction of this variation has consequences for both biochemical and organismal phenotype, and that some of this functional variation is sorted by selection. As with protein-coding sequences, rates and patterns of promoter sequence evolution differ considerably among loci and among clades for reasons that are not well understood. Studying the evolution of transcriptional regulation poses empirical and conceptual challenges beyond those typically encountered in analyses of coding sequence evolution: promoter organization is much less regular than that of coding sequences, and sequences required for the transcription of each locus reside at multiple other loci in the genome. Because of the strong context-dependence of transcriptional regulation, sequence inspection alone provides limited information about promoter function. Understanding the functional consequences of sequence differences among promoters generally requires biochemical and in vivo functional assays. Despite these challenges, important insights have already been gained into the evolution of transcriptional regulation, and the pace of discovery is accelerating.

Review, Academic↗
NASA NTRS2002

The origin and evolution of model organisms

The phylogeny and timescale of life are becoming better understood as the analysis of genomic data from model organisms continues to grow. As a result, discoveries are being made about the early history of life and the origin and development of complex multicellular life. This emerging comparative framework and the emphasis on historical patterns is helping to bridge barriers among organism-based research communities.

Review, Academic↗