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31.
Spinal fusions are being performed for various pathologies of the spine. Stabilizing vertebral segments by eliminating motion
across those segments becomes critical in dealing with pathologies of the spine that lead to instability. The use of autograft
has been the gold standard for spine fusion. However, due to complications such as donor site morbidity, increased operating
time, and limited supply, the use of allograft as a graft extender has become an acceptable practice especially in fusions
spanning multiple segments. The discovery and isolation of novel proteins (i.e., bone morphogenetic proteins, BMPs), which
initiate the molecular cascade of bone formation, have experimentally been shown in numerous animal studies to be as effective
as autografts. Although the use of BMPs has exciting applications in spine surgery, long-term clinical studies must be evaluated
for its efficacy in various applications in humans. The use of biomimetic materials such as hydroxyapatite (HA), or tricalcium
phosphate (TCP) has also been examined in several animal models as bone graft substitutes or carriers. Although these materials
have shown some promise in specific site applications, more work remains in elucidating an efficacious combination of these
materials and BMPs that can be as effective as autografts. This review will present the status of bone grafts, bone morphogenetic
proteins, gene therapy, and work that has been done to facilitate spinal fusion and simultaneously eliminate the need for
bone graft.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
32.
The synthesis of three novel phosphonobile acids from natural bile acids is reported. The CMC of phosphonodeoxycholic acid (PDCA) at pH 8.2 was found to be lower than that of the parent deoxycholic acid (DCA). PDCA micelles were also found to have higher microviscosity compared to DCA micelles, suggesting higher hydrophobicity and tighter packing in the interior of PDCA micelles. PDCA aggregated further to form an aqueous gel at pH 4. 相似文献
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Eukaryotic translation initiation factor 5 (eIF5) interacts with the 40S ribosomal initiation complex (40S.eIF3.AUG.Met-tRNA(f).eIF2.GTP) to promote the hydrolysis of bound GTP. In Saccharomyces cerevisiae, eIF5, a protein of 45346Da, is encoded by a single-copy essential gene, TIF5. In this paper, we have isolated a temperature-sensitive S. cerevisiae strain, TMY5-1, by replacing the wild-type chromosomal copy of TIF5 with one mutagenized in vitro. The mutant yeast cells rapidly cease protein synthesis when grown under non-permissive conditions, lose polyribosomes and accumulate free 80S ribosomes. Further characterization of mutant eIF5 showed that the mutant protein, expressed in Escherichia coli, is defective both in its interaction with eIF2 as well as in mediating the hydrolysis of GTP bound to the 40S initiation complex and consequently in the formation of the 80S initiation complex. Additionally, the availability of a yeast strain containing temperature-sensitive mutation in the eIF5 gene allowed us to construct a cell-free translation system that was dependent on exogenously added eIF5 for translation of mRNAs in vitro. 相似文献
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The Saccharomyces cerevisiae Homologue of Mammalian Translation Initiation Factor 6 Does Not Function as a Translation Initiation Factor 总被引:1,自引:0,他引:1 下载免费PDF全文
Eukaryotic translation initiation factor 6 (eIF6) binds to the 60S ribosomal subunit and prevents its association with the 40S ribosomal subunit. The Saccharomyces cerevisiae gene that encodes the 245-amino-acid eIF6 (calculated Mr 25,550), designated TIF6, has been cloned and expressed in Escherichia coli. The purified recombinant protein prevents association between 40S and 60S ribosomal subunits to form 80S ribosomes. TIF6 is a single-copy gene that maps on chromosome XVI and is essential for cell growth. eIF6 expressed in yeast cells associates with free 60S ribosomal subunits but not with 80S monosomes or polysomal ribosomes, indicating that it is not a ribosomal protein. Depletion of eIF6 from yeast cells resulted in a decrease in the rate of protein synthesis, accumulation of half-mer polyribosomes, reduced levels of 60S ribosomal subunits resulting in the stoichiometric imbalance in the 40S/60S subunit ratio, and ultimately cessation of cell growth. Furthermore, lysates of yeast cells depleted of eIF6 remained active in translation of mRNAs in vitro. These results indicate that eIF6 does not act as a true translation initiation factor. Rather, the protein may be involved in the biogenesis and/or stability of 60S ribosomal subunits. 相似文献
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Prajna Gayen Sudipta Maitra Sutapa Datta Santi P. Sinha Babu 《Journal of biosciences》2010,35(1):73-77
Wolbachia are symbiotic endobacteria that infect the majority of filarial nematodes, including Wuchereria bancrofti, Brugia malayi and Onchocerca volvulus. Recent studies have suggested that Wolbachia are necessary for the reproduction and survival of filarial nematodes and have highlighted the use of antibiotic therapy
such as tetracycline/doxycycline as a novel method of treatment for infections caused by these organisms. Before such therapy
is conceived and implemented on a large scale, it is necessary to assess the prevalence of the endosymbiont in W. bancrofti from different geographical locations. We present data from molecular and electron microscopic studies to provide evidence
for Wolbachia symbiosis in W. bancrofti microfilariae collected from two districts (Bankura and Birbhum) of West Bengal, India. 相似文献
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Aishwarya Natarajan Krishnan Rangan Ramakrishna Vadrevu 《Journal of peptide science》2023,29(2):e3451
The self-assembly of peptides is influenced by their amino acid sequence and other factors including pH, charge, temperature, and solvent. Herein, we explore whether a four-residue sequence, EKKE, consisting of exclusively charged amino acids shows the propensity to form self-assembled ordered nanostructures and whether the overall charge plays any role in morphological and functional properties. From a combination of experimental data provided by Thioflavin T fluorescence, Congo red absorbance, circular dichroism spectroscopy, dynamic light scattering, field emission-scanning electron microscopy, atomic force microscopy, and confocal microscopy, it is clear that the all-polar peptide and charged EKKE sequence shows a pH-dependent tendency to form amyloid-like structures, and the self-assembled entities under acidic, basic and neutral conditions exhibit morphological variation. Additionally, the ability of the self-assembled amyloid nanostructures to bind to the toxic metal, lead (Pb2+), was demonstrated from the analysis of the ultraviolet absorbance and X-ray photoelectron spectroscopy data. The modulation at the sequence level for the amyloid-forming EKKE scaffold can further extend its potential role not only in the remediation of other toxic metals but also towards biomedical applications. 相似文献
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