RESUMEN

BACKGROUND CONTEXT: One of the common causes of low back pain is intervertebral disc degeneration. The pathophysiology of disc degeneration involves apoptosis of nucleus pulposes cells and degradation of extra cellular matrix (ECM). Caspase 3 plays a central role in apoptosis and the ADAMTS5 (A Disintegrin and Metalloproteinase with Thrombospondin motifs 5) gene plays a critical role in ECM degradation. Hence, we hypothesized that if one can silence these two genes, both apoptosis and ECM degradation can be prevented, thereby preventing the progression and even reverse disc degeneration. PURPOSE: The purpose of this study is to demonstrate the regenerative potential of small interfering RNA (siRNA) designed against Caspase 3 and ADAMTS5 genes in an in vitro and animal model of disc degeneration. STUDY DESIGN: In vitro study followed by in vivo study in a rabbit model. METHODS: In vitro studies were done using the human hepatocellular carcinoma (Hep G2) cell line for validating the efficacy of liposomal siRNA in controlling the expression of genes (Caspase 3 and ADAMTS5). Later, siRNA's validation was done in a rabbit annular punctured model by administering siRNA's individually (Caspase 3 and ADAMTS5) and in combination Caspase3-ADAMTS5) for assessing their synergistic effect in down regulating the gene expression in the degenerative discs. Annular punctured intervertebral discs of the rabbit were injected with siRNA formulations (single and dual) and phosphate buffer saline, one week after initial puncture. Magnetic resonance imaging (MRI) scans were done before and after siRNA treatment (1, 4 and 8 weeks) for assessing the progression of disc degeneration. The histopathology and real time polymerase chain reaction (RT-PCR) studies were done for evaluating their efficacy. We did not receive any funding for conducting the study, and we do not have a conflict of interest with any researchers or scientific groups. RESULTS: The observations made from both in vitro and in vivo studies indicate the beneficial effects of siRNA formulation in down regulating the expression of Caspase 3 and ADAMTS5 genes. The MRI and histopathological evaluation showed that the disc degeneration was progressive in phosphate buffer saline and AT5-siRNA injected discs but the discs that received Caspase 3-siRNA and dual siRNA (Cas3-AT5-siRNA) formulation showed signs of recovery and regeneration 4 and 8 weeks after injection. The efficacy of siRNA designed against Cas3 and AT5 was also assessed in both in vitro and in vivo experiments by using RT-PCR analysis and the results showed downregulation of Caspase 3 gene in Caspase 3-siRNA group, but there was no significant downregulation of ADAMTS5 gene in ADAMTS5-siRNA group (ie, indicated by fold change). Synergistic effect was observed in the group that received dual siRNA (Cas3-AT5 siRNA) formulation. CONCLUSIONS: This experiment suggests that intervention by siRNA treatment significantly reduced the extent of apoptosis in the discs. CLINICAL SIGNIFICANCE: Delivery of siRNA directly into spinal discs has a potential in treating disc degeneration nonsurgically.

Asunto(s)

RESUMEN

We announce here the draft genome sequence of Brevibacillus laterosporus strain Lak 1210, isolated from mangrove soil. This alkaliphilic strain is an efficient chitin degrader and has the ability to control insects and inhibit phytopathogenic fungi. The assembly consists of 5,082,926 bp, with 4,321 protein-coding sequences and a GC content of 41.15%.

RESUMEN

Annotation of peptide sequence from tandem mass spectra constitutes the central step of mass spectrometry-based proteomics. Peptide mass spectra are obtained upon gas-phase fragmentation. Identification of the protein from a set of experimental peptide spectral matches is usually referred as protein inference. Occurrence and intensity of these fragment ions in the MS/MS spectra are dependent on many factors such as amino acid composition, peptide basicity, activation mode, protease, etc. Particularly, chemical derivatizations of peptides were known to alter their fragmentation. In this study, the influence of acetylation, guanidinylation, and their combination on peptide fragmentation was assessed initially on a lipase (LipA) from Bacillus subtilis followed by a bovine six protein mix digest. The dual modification resulted in improved fragment ion occurrence and intensity changes, and this resulted in the equivalent representation of b- and y-type fragment ions in an ion trap MS/MS spectrum. The improved representation has allowed us to accurately annotate the peptide sequences de novo. Dual labeling has significantly reduced the false positive protein identifications in standard bovine six peptide digest. Our study suggests that the combinatorial labeling of peptides is a useful method to validate protein identifications for high confidence protein inference. Graphical Abstract ᅟ.

Asunto(s)

RESUMEN

Photosensitizer (PS) mediated Photodynamic Therapy (PDT) is a preferred treatment modality for certain cancers. Some of the factors limiting the expansion of PDT to other clinical conditions are the aggregation of hydrophobic PS in aqueous media and the inefficient biodistribution of photosensitizers. Formulations containing the PS have overcome some of the limitations by controlling aggregation-dependent quenching of PS and by improving the biodistribution of PS. We report a photosensitizer delivery system with protein nanoparticles that does not involve any chemical modifications. Using Lactoferrin, an iron-carrying milk protein, as sole matrix and Chlorine e6 (Ce6), an FDA-approved PS. The nanoparticles were prepared by the water-in-oil emulsion method. The spectral and physical properties of the particles were analyzed. Production of reactive oxygen was enhanced in the formulations (LeN) compared to free Ce6 as indicated by the water-soluble and -insoluble dyes. LeN show a specific Ce6 release at low pH, which is an advantage in the acidic environment of tumors and in endosomes. The uptake and intracellular concentrations of Ce6 by SK-OV-3, estimated by confocal microscopy, FACS and fluorescence spectroscopy, were significantly higher with LeN compared to free Ce6. Upon light exposure, LeN showed a substantial decrease (>4 times) in Ce6 requirement compared to free Ce6 in its ability to cause light-mediated cell death in the SK-OV-3 and MDA-MD 231 cells. LeN were shown to be non-toxic to the cells even at concentrations ten times that used in the PDT study. Safety, efficient loading and significant uptake by cells and more importantly a significant decrease in IC50 values demonstrate that LeN have potential in PDT.