63 research outputs found
Structure and conformation of the disulfide bond in dimeric lung surfactant peptides SP-B1ā25 and SP-B8ā25
AbstractRaman spectroscopy was used to determine the conformation of the disulfide linkage between cysteine residues in the homodimeric construct of the N-terminal alpha helical domain of surfactant protein B (dSP-B1ā25). The conformation of the disulfide bond between cysteine residues in position 8 of the homodimer of dSP-B1ā25 was compared with that of a truncated homodimer (dSP-B8ā25) of the peptide having a disulfide linkage at the same position in the alpha helix. Temperature-dependent Raman spectra of the SāS stretching region centered at ā¼500Ā cmā1 indicated a stable, although highly strained disulfide conformation with a Ļ(CSāSC) dihedral angle of Ā±10Ā° for the dSP-B1ā25 dimer. In contrast, the truncated dimer dSP-B8ā25 exhibited a series of disulfide conformations with the Ļ(CSāSC) dihedral angle taking on values of either Ā±30Ā° or 85Ā±20Ā°. For conformations with Ļ(CSāSC) close to the Ā±90Ā° value, the Raman spectra of the 8ā25 truncated dimers exhibited Ļ(SSāCC) dihedral angles of 90/180Ā° and 20ā30Ā°. In the presence of a lipid mixture, both constructs showed a Ī½(SāS) band at ā¼488Ā cmā1, corresponding to a Ļ(CSāSC) dihedral angle of Ā±10Ā°. Polarized infrared spectroscopy was also used to determine the orientation of the helix and Ī²-sheet portion of both synthetic peptides. These calculations indicated that the helix was oriented primarily in the plane of the surface, at an angle of ā¼60ā70Ā° to the surface normal, while the Ī²Ā structure had ā¼40Ā° tilt. This orientation direction did not change in the presence of a lipid mixture or with temperature. These observations suggest that: (i) the conformational flexibility of the disulfide linkage is dependent on the amino acid residues that flank the cysteine disulfide bond, and (ii) in both constructs, the presence of a lipid matrix locks the disulfide bond into a preferred conformation
Rapid and Sensitive Detection of Rotavirus Molecular Signatures Using Surface Enhanced Raman Spectroscopy
Human enteric virus infections range from gastroenteritis to life threatening diseases such as myocarditis and aseptic meningitis. Rotavirus is one of the most common enteric agents and mortality associated with infection can be very significant in developing countries. Most enteric viruses produce diseases that are not distinct from other pathogens, and current diagnostics is limited in breadth and sensitivity required to advance virus detection schemes for disease intervention strategies. A spectroscopic assay based on surface enhanced Raman scattering (SERS) has been developed for rapid and sensitive detection of rotavirus. The SERS method relies on the fabrication of silver nanorod array substrates that are extremely SERS-active allowing for direct structural characterization of viruses. SERS spectra for eight rotavirus strains were analyzed to qualitatively identify rotaviruses and to classify each according to G and P genotype and strain with >96% accuracy, and a quantitative model based on partial least squares regression analysis was evaluated. This novel SERS-based virus detection method shows that SERS can be used to identify spectral fingerprints of human rotaviruses, and suggests that this detection method can be used for pathogen detection central to human health care
Detection of Mycoplasma pneumoniae in Simulated and True Clinical Throat Swab Specimens by Nanorod Array-Surface-Enhanced Raman Spectroscopy
The prokaryote Mycoplasma pneumoniae is a major cause of respiratory disease in humans, accounting for 20% of all community-acquired pneumonia and the leading cause of pneumonia in older children and young adults. The limitations of existing options for mycoplasma diagnosis highlight a critical need for a new detection platform with high sensitivity, specificity, and expediency. Here we evaluated silver nanorod arrays (NA) as a biosensing platform for detection and differentiation of M. pneumoniae in culture and in spiked and true clinical throat swab samples by surface-enhanced Raman spectroscopy (SERS). Three M. pneumoniae strains were reproducibly differentiated by NA-SERS with 95%ā100% specificity and 94ā100% sensitivity, and with a lower detection limit exceeding standard PCR. Analysis of throat swab samples spiked with M. pneumoniae yielded detection in a complex, clinically relevant background with >90% accuracy and high sensitivity. In addition, NA-SERS correctly classified with >97% accuracy, ten true clinical throat swab samples previously established by real-time PCR and culture to be positive or negative for M. pneumoniae. Our findings suggest that the unique biochemical specificity of Raman spectroscopy, combined with reproducible spectral enhancement by silver NA, holds great promise as a superior platform for rapid and sensitive detection and identification of M. pneumoniae, with potential for point-of-care application
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Composition for personal growth : program design and evaluation.
<p>Two categories were used for cross-validation of the model, either type 1 or type 2. Clinical isolates were treated as an unknown class and cross-validated sensitivity, specificity, and class error were based on their classification prediction score with their respective reference strain control class. CV, cross-validated.</p><p>Cross-validated PLS-DA modeling statistics for the prediction performance for NA-SERS typing of individual type 1 and 2 <i>M</i>. <i>pneumoniae</i> clinical isolates.</p
A HIF1Ī± Regulatory Loop Links Hypoxia and Mitochondrial Signals in Pheochromocytomas
Pheochromocytomas are neural crestāderived tumors that arise from inherited or sporadic mutations in at least six independent genes. The proteins encoded by these multiple genes regulate distinct functions. We show here a functional link between tumors with VHL mutations and those with disruption of the genes encoding for succinate dehydrogenase (SDH) subunits B (SDHB) and D (SDHD). A transcription profile of reduced oxidoreductase is detected in all three of these tumor types, together with an angiogenesis/hypoxia profile typical of VHL dysfunction. The oxidoreductase defect, not previously detected in VHL-null tumors, is explained by suppression of the SDHB protein, a component of mitochondrial complex II. The decrease in SDHB is also noted in tumors with SDHD mutations. Gain-of-function and loss-of-function analyses show that the link between hypoxia signals (via VHL) and mitochondrial signals (via SDH) is mediated by HIF1Ī±. These findings explain the shared features of pheochromocytomas with VHL and SDH mutations and suggest an additional mechanism for increased HIF1Ī± activity in tumors
2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease
The recommendations listed in this document are, whenever possible, evidence based. An extensive evidence review was conducted as the document was compiled through December 2008. Repeated literature searches were performed by the guideline development staff and writing committee members as new issues were considered. New clinical trials published in peer-reviewed journals and articles through December 2011 were also reviewed and incorporated when relevant. Furthermore, because of the extended development time period for this guideline, peer review comments indicated that the sections focused on imaging technologies required additional updating, which occurred during 2011. Therefore, the evidence review for the imaging sections includes published literature through December 2011
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