In-vivo optical detection of cancer using chlorin e6 – polyvinylpyrrolidone induced fluorescence imaging and spectroscopy

<p>Abstract</p> <p>Background</p> <p>Photosensitizer based fluorescence imaging and spectroscopy is fast becoming a promising approach for cancer detection. The purpose of this study was to examine the use of the photosensitizer chlorin e6 (Ce6) formulated in polyvinylpyrrolidone (PVP) as a potential exogenous fluorophore for fluorescence imaging and spectroscopic detection of human cancer tissue xenografted in preclinical models as well as in a patient.</p> <p>Methods</p> <p>Fluorescence imaging was performed on MGH human bladder tumor xenografted on both the chick chorioallantoic membrane (CAM) and the murine model using a fluorescence endoscopy imaging system. In addition, fiber optic based fluorescence spectroscopy was performed on tumors and various normal organs in the same mice to validate the macroscopic images. In one patient, fluorescence imaging was performed on angiosarcoma lesions and normal skin in conjunction with fluorescence spectroscopy to validate Ce6-PVP induced fluorescence visual assessment of the lesions.</p> <p>Results</p> <p>Margins of tumor xenografts in the CAM model were clearly outlined under fluorescence imaging. Ce6-PVP-induced fluorescence imaging yielded a specificity of 83% on the CAM model. In mice, fluorescence intensity of Ce6-PVP was higher in bladder tumor compared to adjacent muscle and normal bladder. Clinical results confirmed that fluorescence imaging clearly captured the fluorescence of Ce6-PVP in angiosarcoma lesions and good correlation was found between fluorescence imaging and spectral measurement in the patient.</p> <p>Conclusion</p> <p>Combination of Ce6-PVP induced fluorescence imaging and spectroscopy could allow for optical detection and discrimination between cancer and the surrounding normal tissues. Ce6-PVP seems to be a promising fluorophore for fluorescence diagnosis of cancer.</p

REDD1 Protects Osteoblast Cells from Gamma Radiation-Induced Premature Senescence

Radiotherapy is commonly used for cancer treatment. However, it often results in side effects due to radiation damage in normal tissue, such as bone marrow (BM) failure. Adult hematopoietic stem and progenitor cells (HSPC) reside in BM next to the endosteal bone surface, which is lined primarily by hematopoietic niche osteoblastic cells. Osteoblasts are relatively more radiation-resistant than HSPCs, but the mechanisms are not well understood. In the present study, we demonstrated that the stress response gene REDD1 (regulated in development and DNA damage responses 1) was highly expressed in human osteoblast cell line (hFOB) cells after γ irradiation. Knockdown of REDD1 with siRNA resulted in a decrease in hFOB cell numbers, whereas transfection of PCMV6-AC-GFP-REDD1 plasmid DNA into hFOB cells inhibited mammalian target of rapamycin (mTOR) and p21 expression and protected these cells from radiation-induced premature senescence (PS). The PS in irradiated hFOB cells were characterized by significant inhibition of clonogenicity, activation of senescence biomarker SA-β-gal, and the senescence-associated cytokine secretory phenotype (SASP) after 4 or 8 Gy irradiation. Immunoprecipitation assays demonstrated that the stress response proteins p53 and nuclear factor κ B (NFkB) interacted with REDD1 in hFOB cells. Knockdown of NFkB or p53 gene dramatically suppressed REDD1 protein expression in these cells, indicating that REDD1 was regulated by both factors. Our data demonstrated that REDD1 is a protective factor in radiation-induced osteoblast cell premature senescence

A Cross-Level Investigation of the Role of Human Resources Practices: Does Brand Equity Matter?

The extant literature has suggested that high-performance human resources practices (HRPs), such as employee training, employment security, and a results-oriented appraisal system, promote favorable employee behaviors. This research predicts that such practices render a mechanism that reduces hotel employees’ propensity to quit through lowering their emotional exhaustion. However, does this mechanism work more effectively in hotels with a strong brand? To address this question, we propose a multilevel research model to assess the effectiveness of HRPs under different conditions of brand equity. Drawing on both social exchange theory and social identification theory, the current study works to advance the literature by investigating the cross-level brand equity boundary condition on the HRPs−intention-to-quit moderated mediation process from two independent sets of data. It advances the literature by bridging the research gap between human resource management and brand management

Gamma-radiation induced senescence in hFOB cells.

<p>Following radiation (0, 4, or 8 Gy), senescent hFOB cells were determined by (A) clonogenicity assays, (B) MTS-proliferation assay and (C) SA-β-gal staining. SA-β-gal-positive cells were increased 72 h after 8 Gy γ irradiation. Representative data was from one of a total of 3 independent experiments. (D) Conditioned medium (CM) from hFOB cells was collected and pooled from three experiments 48 h after irradiation and the concentration of cytokines was analyzed by Luminex in triplicate. Gamma radiation-induced IL-6, IL-8, G-CSF and GM-CSF were significantly increased. Means ± SD. *: p<0.05, **: p<0.01, IR vs. non-irradiated cells.</p

REDD1 expression in human hematopoietic cells.

<p>Purified human CD34+ cells were cultured for 4 and 14 days before being exposed to 2 Gy radiation. (A) mRNA levels for <i>REDD1</i> in 14-day cultured CD34+ cells using 18S rRNA as a control to calculate the relative quantity (RQ) of gene expression at different times after IR. Means ± SD. *, p <0.05, 2 Gy vs. 0 Gy sham-irradiated control. (B) Western blot shows REDD1 protein levels in cultured CD34+ cells at different times after 2 Gy irradiation. Representative immunoblots and ratio of REDD1/β-actin expression from 3 independent experiments are shown. Flow cytometric analysis for the apoptotic cell death marker Annexin-V/7AAD and CD34 surface marker was performed. Radiation resulted in more apoptotic cells in 4-day (C-1) cultured cells than in 14-day (D-1) culture. (C-2) and (D-2) CD34-positive (progenitor) and CD34-negative (mature) populations were separately gated for Annexin-V/7AAD analysis. FS, forward angle light scatter.</p

Radiation regulated miRNAs expression in both CD34+ and hFOB cells.

<p>Data from miRNA Microarray (LC Sciences Co. Houston, Texas).</p

REDD1 protects hFOB cells from γ radiation-induced senescence.

<p>The effects of REDD1 were evaluated using gene silencing (si-RNA) and overexpression (plasmid DNA transfection) approaches. (A) Western blot shows REDD1 and β-actin (loading control) expression in control (non-transfection CT), REDD1 siRNA-transfected (si-REDD1), and maxGFP siRNA-transfected control (si-CT) samples after 0 or 8 Gy irradiation. Transfection of si-REDD1 decreased the radiation-induced REDD1 expression. (B) Survival cell number (trypan blue–negative) was decreased in siREDD1-transfected hFOB cells 24 hours after IR. Means ± SD for 3 independent experiments. *: p<0.05, si-REDD1 vs. CT and si-CT. (C) Quantitative RT-PCR determined <i>REDD1</i> gene expression in non-gene transfected control (CT), vector-transfected(GFP) and REDD-gene containing construct transfected hFOB cells at 4 and 48 h after irradiation. The relative quantity of gene expression was calculated using 18 S rRNA as a control. (D) Overexpression of REDD1 inhibited SA-β-gal activation after irradiation. Representative image of SA-β-gal staining and statistical data from three experiments are shown. Means ± SD. **: p<0.01, REDD1 plasmid DNA-transfected vs. CT or vector-transfected samples.</p