Novel Wavelength-Specific Blue Light-Emitting Headlamp for 5-Aminolevulinic Acid Fluorescence-Guided Resection of Glioblastoma.

OBJECTIVE: Extent of resection of glioblastoma is an important predictor for overall survival, and 5-aminolevulinic acid fluorescence-guided surgery can improve outcomes. However, the technique requires the installation of a blue light module on operative microscopes and may be cost prohibitive. A novel and economical blue light-emitting headlamp was designed, and its clinical utility was explored. METHODS: A remote-controlled dual light emitting diode headlamp system was constructed with 1 diode emitting white light and the other blue. Spectrographic analysis of the blue light emitted from a commercial operative microscope and the headlamp was performed. A comparative evaluation of the 2 illumination systems was conducted for 3 patients who underwent craniotomy for glioblastoma resection. Histologic examination of the fluorescing tissue detected by the headlamp was performed, and the extent of resection was assessed by postoperative day 1 magnetic resonance imaging. RESULTS: Spectrography of blue light emitted from the headlamp system was wavelength specific with a single emission peak at 416 nm and a linewidth of 35 nm. In contrast, blue light from the microscope (peak: 426 nm) had a wider linewidth of 54 nm and was not wavelength specific with additional infrared radiation detected. Gross or near-total resection of contrast-enhancing glioblastoma was performed for all 3 patients. Intraoperatively, comparable tumor fluorescence was observed under microscope and headlamp blue light illumination. Histologic examination of tissue fluorescing under headlamp blue light confirmed the presence of glioblastoma. CONCLUSIONS: This novel proof-of-concept blue light-emitting headlamp device may offer an opportunity for institutions with limited resources to implement 5-aminolevulinic acid fluorescence-guided glioblastoma resections.

Comparison of next-generation sequencing systems.

With fast development and wide applications of next-generation sequencing (NGS) technologies, genomic sequence information is within reach to aid the achievement of goals to decode life mysteries, make better crops, detect pathogens, and improve life qualities. NGS systems are typically represented by SOLiD/Ion Torrent PGM from Life Sciences, Genome Analyzer/HiSeq 2000/MiSeq from Illumina, and GS FLX Titanium/GS Junior from Roche. Beijing Genomics Institute (BGI), which possesses the world's biggest sequencing capacity, has multiple NGS systems including 137 HiSeq 2000, 27 SOLiD, one Ion Torrent PGM, one MiSeq, and one 454 sequencer. We have accumulated extensive experience in sample handling, sequencing, and bioinformatics analysis. In this paper, technologies of these systems are reviewed, and first-hand data from extensive experience is summarized and analyzed to discuss the advantages and specifics associated with each sequencing system. At last, applications of NGS are summarized.

Physicochemical characterization of siRNA-peptide complexes.

Short interfering RNAs (siRNAs) trigger RNA interference (RNAi), where the complementary mRNA is degraded, resulting in silencing of the encoded protein. A delivery carrier is desired to increase the solution stability of siRNA and improve its cellular uptake to overcome its rapid enzymatic degradation and low transfection efficiency. In this study, Arginine-9 (R9), a cell-penetrating peptide derived from the HIV 1 Tat protein, was investigated as a potential carrier for siRNAs. A connective tissue growth factor (CTGF) encoding siRNA was used because of its therapeutic potential of treating breast cancer. The interaction between R9 and siRNA was studied by UV/vis spectroscopy and circular dichroism (CD). The hydrodynamic diameter of the siRNA-R9 complexes was determined by dynamic light scattering (DLS), and the Zeta potential of the complexes was obtained by measuring the electrophoretic mobility. The effect of salt addition is also quantified using UV-vis spectroscopy. The siRNA and R9 readily formed complexes/aggregates through molecular association, accompanying a change in surface charge with increasing peptide concentration, reaching a maximum hydrodynamic diameter of approximately 1 mum at siRNA saturation. The highest binding ratio of R9 to siRNA determined from the UV/vis spectra and CD is 10.3:1 and 39.1:1 from DLS (corresponds to charge ratios of 2.2:1 (+/-) and 8.4:1, respectively). The difference in binding ratio is possibly because of the difference in signal contribution between absorption and light scattering. The physicochemical characterization of CTGF siRNA-R9 complexes presented here have shown that various methods can be used to control the properties of the siRNA-peptide complexes, which provide a basis for the formulation of siRNA therapeutics with peptide carriers.

Interaction of a self-assembling peptide with oligonucleotides: complexation and aggregation.

Molecular interaction of a self-assembling peptide, EAK16-II, to single- and double-stranded oligodeoxynucleotides (ODNs) was investigated under various solution conditions. The molecular events leading to EAK-ODN complexation and further aggregation were elucidated using a series of spectroscopic and microscopic methods. Despite the ability to self-assemble, EAK molecules bind to ODN molecules first upon mixing, resulting in EAK-ODN complexes. The complexes further associate to form EAK-ODN aggregates. A method based on UV-Vis absorption and centrifugation was developed to quantify the fraction of ODNs in the aggregates. The results were used to construct binding isotherms via a binding density function analysis. To compare the effects of different pH values and nucleotide types, the modified noncooperative McGhee and von Hippel model was used to extract binding parameters from the binding isotherms. The binding constant of EAK to ODNs was higher at pH 4 than at pH 7, and no binding was observed at pH 11, indicating that the interaction involved is primarily electrostatic in nature. EAK bound more strongly to single-stranded ODNs. The EAK-ODN aggregates were further visualized using atomic force microscopy; their size distribution as a function of EAK concentration was monitored by dynamic light scattering. The timescale for the EAK-ODN aggregation was on the order of minutes by fluorescence anisotropy and steady-state light scattering experiments. Fluorescence quenching experiments demonstrated that the ODNs in the aggregates were less accessible to the solvent, demonstrating a potential of oligonucleotide encapsulation by the self-assembling peptide.