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871.
872.
Biochemical markers of bone turnover part II: clinical applications in the management of osteoporosis
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Seibel MJ 《The Clinical biochemist. Reviews / Australian Association of Clinical Biochemists》2006,27(3):123-138
With the ageing population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to every day clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis and follow-up of such pathologies have markedly grown. Together with clinical and imaging techniques, biochemical tests play an important role in the assessment and differential diagnosis of metabolic bone disease. These biochemical indices are non-invasive, comparatively inexpensive and, when applied and interpreted correctly, helpful tools in the diagnostic and therapeutic assessment of metabolic bone disease.This second part of the two part series reviews the current evidence regarding the clinical use of biochemical markers of bone remodelling in the management of osteoporosis. 相似文献
873.
874.
Vacuolin, a flotillin/reggie-related protein from Dictyostelium oligomerizes for endosome association 总被引:1,自引:1,他引:0
Dirk Wienke Anja Drengk Christian Schmauch Nicole Jenne Markus Maniak 《European journal of cell biology》2006,85(9-10):991
We have analysed the domain structure of vacuolin, a Dictyostelium protein binding to the cytoplasmic surface of late endosomes. Localisation studies using GFP fusions together with a yeast two-hybrid analysis and co-immunoprecipitation experiments reveal that a region close to the C-terminus mediates oligomer formation of the protein through a coiled-coil mechanism which in turn is a prerequisite for the efficient binding to endosomal membranes via a prohibitin (PHB) domain in the middle of the molecule. Overexpression of the coiled-coil domain strongly competes with endogenous vacuolin in the oligomers and reduces the efficiency of membrane targeting. The domain arrangement of vacuolin is most similar to flotillin/reggie, a protein found on late endosomes of mammalian cells. 相似文献
875.
Wienke D Drengk A Schmauch C Jenne N Maniak M 《European journal of cell biology》2006,85(9-10):991-1000
We have analysed the domain structure of vacuolin, a Dictyostelium protein binding to the cytoplasmic surface of late endosomes. Localisation studies using GFP fusions together with a yeast two-hybrid analysis and co-immunoprecipitation experiments reveal that a region close to the C-terminus mediates oligomer formation of the protein through a coiled-coil mechanism which in turn is a prerequisite for the efficient binding to endosomal membranes via a prohibitin (PHB) domain in the middle of the molecule. Overexpression of the coiled-coil domain strongly competes with endogenous vacuolin in the oligomers and reduces the efficiency of membrane targeting. The domain arrangement of vacuolin is most similar to flotillin/reggie, a protein found on late endosomes of mammalian cells. 相似文献
876.
Prediction of charge-induced molecular alignment: residual dipolar couplings at pH 3 and alignment in surfactant liquid crystalline phases 总被引:2,自引:0,他引:2
Zweckstetter M 《European biophysics journal : EBJ》2006,35(2):170-180
Recently we reported that the alignment tensor of a biological macromolecule, which was dissolved in a dilute suspension of
highly negatively charged filamentous phage at close to neutral pH, can be predicted from the molecule’s 3D charge distribution
and shape (Zweckstetter et al. 2004). Here it is demonstrated that this approach is also applicable to alignment of proteins
in liquid crystalline phases formed by filamentous phage at low pH. Residual dipolar couplings (RDCs) predicted by our simple
electrostatic model for the B1 domain of protein G in fd phage at pH 3 fit very well with the experimental values. The sign
of charge–shape predicted one-bond 1H–15N dipolar couplings for the B1 domain of protein G (GB1) was inverted at pH 3 compared to neutral pH, in agreement with experimental
observations. Our predictions indicate that this is a feature specific for GB1. In addition, it is shown that RDCs induced
in the protein ubiquitin by the presence of a positively charged surfactant system comprising cetylpyridinium bromide/hexanol/sodium
bromide can be predicted accurately by a simple electrostatic alignment model. This shows that steric and electrostatic interactions
dominate weak alignment of biomolecules for a wide range of pH values both in filamentous phage and in surfactant liquid crystalline
phases. 相似文献
877.
Sims NA Brennan K Spaliviero J Handelsman DJ Seibel MJ 《American journal of physiology. Endocrinology and metabolism》2006,290(3):E456-E462
Although testosterone (T) has striking effects on mature skeletal size and structure, it is not clear whether this depends exclusively on adult circulating levels of T or whether additional early-life factors also play a role. We have compared the androgen-deficient hypogonadal (hpg) mutant mouse with intact, orchidectomized, and T-treated non-hpg mice to determine relative contributions of adult and perinatal T to bone growth and development. At 3 wk of age, although trabecular and cortical bone structure was normal, bone turnover was significantly altered in hpg male mice; osteoid volume (OV/BV) and osteoblast surface (ObS/BS) were significantly lower and osteoclast surface (OcS/BS) significantly higher in hpg mice compared with age-matched non-hpg mice, pointing to a role for the perinatal T surge in determining bone turnover levels before sexual maturity. At 9 wk of age, the hpg bone phenotype mimicked closely that of age-matched non-hpg mice that had been orchidectomized at 3 wk of age, including low trabecular bone mass and high bone turnover. These bone phenotypes of hpg and orchidectomized non-hpg mice were all prevented by replacement doses of T or dihydrotestosterone (DHT), suggesting that these are determined by adult sex steroid hormones. In contrast, a short bone phenotype that could not be prevented by T or DHT treatment was observed in 9-wk-old hpg mice yet not in intact or castrated non-hpg mice. These data suggest a role for the perinatal T surge in determining adult bone length and confirms that adult circulating T determines adult bone density. 相似文献
878.
Rovina P Jaritz M Höfinger S Graf C Dévay P Billich A Baumruker T Bornancin F 《The Biochemical journal》2006,400(2):255-265
CerK (ceramide kinase) produces ceramide 1-phosphate, a sphingophospholipid with recognized signalling properties. It localizes to the Golgi complex and fractionates essentially between detergent-soluble and -insoluble fractions; however, the determinants are unknown. Here, we made a detailed mutagenesis study of the N-terminal PH domain (pleckstrin homology domain) of CerK, based on modelling, and identified key positively charged amino acid residues within an unusual motif in the loop interconnecting beta-strands 6 and 7. These residues are critical for CerK membrane association and polyphosphoinositide binding and activity. Their mutagenesis results in increased thermolability, sensitivity to proteolysis, reduced apparent molecular mass as well as propensity of the recombinant mutant protein to aggregate, indicating that this loop impacts the overall conformation of the CerK protein. This is in contrast with most PH domains whose function strongly relies on charges located in the beta1-beta2 loop. 相似文献
879.
The nucleocytoplasmic exchange of macromolecules is mediated by receptors specialized in passage through the nuclear pore complex. The majority of these receptors belong to the importin beta protein family, which has 14 members in Saccharomyces cerevisiae. Nine importins carry various cargos from the cytoplasm into the nucleus, whereas four exportins mediate nuclear export. Kap120 is the only receptor whose transport cargo has not been found previously. Here, we characterize Kap120 as an importin for the ribosome maturation factor Rpf1, which was identified in a two-hybrid screen. Kap120 binds directly to Rpf1 in vitro and is released by Ran-GTP. At least three parallel import pathways exist for Rpf1, since nuclear import is defective in strains with the importins Kap120, Kap114, and Nmd5 deleted. Both kap120 and rpf1 mutants accumulate large ribosomal subunits in the nucleus. The nuclear accumulation of 60S ribosomal subunits in kap120 mutants is abolished upon RPF1 overexpression, indicating that Kap120 does not function in the actual ribosomal export step but rather in import of ribosome maturation factors. 相似文献
880.
BACKGROUND AND AIMS: Loasaceae subfam. Loasoideae are mostly distributed in South America (sea level to over 4500 m) with a wide range of animals documented as pollinators. The aim was to investigate correlations between nectar parameters, flower morphology, pollination syndrome and phylogeny. METHODS: Nectar was collected from 29 species from seven genera in the subfamily. Concentration and volumes were measured and the amount of sugar calculated. Correlations of nectar data were plotted on a ternary graph and nectar characteristics compared with flower visitors, floral morphology and phylogenetic data. KEY RESULTS: Sugar concentrations are generally higher than reported for most plant families in the literature. The species investigated can be roughly grouped as follows. Group I: plants with approx. 1.5(-3.5) microL nectar with (40-)60-80% sugar and 0.19-2 mg sugar flower-1; with small, white, star-shaped corollas, pollinated by short-tongued bees. Groups II, III and IV: plants with mostly orange, balloon-, saucer-, bowl- or bell-shaped corollas. Group II: plants with approx. 9-14 microL nectar with 40-60% sugar and 4-10 mg sugar flower-1; mostly visited by long-tongued bees and/or hummingbirds. Group III: plants with 40-100 microL nectar with 30-40% sugar and 14-36 mg sugar flower-1, mostly visited by hummingbirds. Group IV: geoflorous plants with 80-90 microL with 10-15% sugar and 8.5-12 mg sugar flower-1, presumably visited by small mammals. Groups II and III include species visited by bees and/or hummingbirds. CONCLUSIONS: Pollinator switches from short-tongued bees via long-tongued bees to hummingbirds appear to have taken place repeatedly in the genera Nasa, Loasa and Caiophora. Changes in nectar amount and concentration appear to evolve rapidly with little phylogenetic constraint. 相似文献