Ferritin as a novel reporter gene for photoacoustic molecular imaging.

Reporter genes may serve as endogenous contrast agents in the field of photoacoustic (PA) molecular imaging (PMI), enabling greater characterization of detailed cellular processes and disease progression. To demonstrate the feasibility of using ferritin as a reporter gene, human melanoma SK-24 (SK-MEL-24) cells were co-transfected with plasmid expressing human heavy chain ferritin (H-FT) and plasmid expressing enhanced green fluorescent protein (pEGFP-C1) using lipofectamine™ 2000. Nontransfected SK-MEL-24 cells served as a negative control. Fluorescent imaging of GFP confirmed transfection and transgene expression in co-transfected cells. To detect iron accumulation due to ferritin overexpression in SK-MEL-24 cells, a focused high-frequency ultrasonic transducer (60 MHz, f/1.5), synchronized to a pulsed laser (fluence < 5 mJ/cm(2)) was used to scan the PA signal at a wide range NIR wavelengths (850-950 nm). PA signal intensity from H-FT transfected SK-MEL-24 cells was about 5-9 dB higher than nontransfected SK-MEL-24 cells at 850-950 nm. Immunofluorescence and RT-PCR analysis both indicate high levels of ferritin expression in H-FT transfected SK-MEL24 cells, with little ferritin expression in nontransfected SK-MEL-24 cells. In this study, the feasibility of using ferritin as a reporter gene for PMI has been demonstrated in vitro. The use of ferritin as a reporter gene represents a novel concept for PMI using an endogenous contrast agent and may provide various opportunities for molecular imaging and basic science research.

A natural vanishing act: the enzyme-catalyzed degradation of carbon nanomaterials.

Over the past three decades, revolutionary research in nanotechnology by the scientific, medical, and engineering communities has yielded a treasure trove of discoveries with diverse applications that promise to benefit humanity. With their unique electronic and mechanical properties, carbon nanomaterials (CNMs) represent a prime example of the promise of nanotechnology with applications in areas that include electronics, fuel cells, composites, and nanomedicine. Because of toxicological issues associated with CNMs, however, their full commercial potential may not be achieved. The ex vitro, in vitro, and in vivo data presented in this Account provide fundamental insights into the biopersistence of CNMs, such as carbon nanotubes and graphene, and their oxidation/biodegradation processes as catalyzed by peroxidase enzymes. We also communicate our current understanding of the mechanism for the enzymatic oxidation and biodegradation. Finally, we outline potential future directions that could enhance our mechanistic understanding of the CNM oxidation and biodegradation and could yield benefits in terms of human health and environmental safety. The conclusions presented in this Account may catalyze a rational rethinking of CNM incorporation in diverse applications. For example, armed with an understanding of how and why CNMs undergo enzyme-catalyzed oxidation and biodegradation, researchers can tailor the structure of CNMs to either promote or inhibit these processes. In nanomedical applications such as drug delivery, the incorporation of carboxylate functional groups could facilitate biodegradation of the nanomaterial after delivery of the cargo. On the other hand, in the construction of aircraft, a CNM composite should be stable to oxidizing conditions in the environment. Therefore, pristine, inert CNMs would be ideal for this application. Finally, the incorporation of CNMs with defect sites in consumer goods could provide a facile mechanism that promotes the degradation of these materials once these products reach landfills.

Ex vivo imaging of basal cell carcinoma using synchrotron phase-contrast X-ray microscopy.

BACKGROUND/AIMS: There is a need for development of non-invasive methods to improve early diagnosis and screening of suspected malignant lesions. Phase-contrast X-ray microscopy (PCXM) has potential to reveal the structures inside soft tissues, and fine details can be observed without any staining or contrast-enhancing cell preparation. We aimed to investigate the possibility that PCXM can be used to explore the microscopic details of basal cell carcinoma (BCC). METHODS: Paraffin blocks of specimens from patients with basal cell carcinoma were cut with 30 microm thickness for PCXM imaging. Experiments were performed at the International Consortium of Phase Contrast Imaging and Radiology (ICPCIR) (7B2) beamline of the Pohang light source in Korea. The PCXM images were achieved by using coherent hard X-rays from a synchrotron source with no monochromatization. RESULTS: We could obtain images with clear edge enhancement by PCXM. The images taken with this technique showed clear anatomic details of organelles in normal skin such as epidermis, dermis and skin appendages. Most of cancerous lesions were clearly differentiated from adjacent normal tissues and the images closely corresponded to those obtained with low-magnification optical microscopy. CONCLUSION: In this pilot study, we successfully demonstrated that synchrotron PCXM could be used for radiological imaging of BCC with great anatomic details.

Objective interpretation of severity of SLS induced edema by stereoimaging.

BACKGROUND: In the evaluation of the severity of skin inflammations, visual scoring system is widely being used as a subjective method. However, it is well known that interobserver variations occur even between the interpretations of experienced dermatologists. OBJECTIVE: To develop a new objective and quantitative method for the evaluation of skin surface contours and for the assessment of severity in SLS-induced edema, a new investigatory tool based on the concept of "stereoimaging" was studied. Differences between binocular images were used by a stereoimage optical topometer (SOT) system capable of calculating skin surface topographic information, which was then used to produce a three-dimensional image. METHODS: We compared the results obtained by SOT with a visual scoring system after applying sodium lauryl sulfate (SLS) to skin. The degree of edema was assessed qualitatively by visual scoring (0: none, 1: mild edema, 2: moderate edema, 3: severe edema). To quantify the severity, five three-dimensional parameters (S(a), S(z), SL, SA and SV) were used in the SOT analysis. RESULTS: The means of these five parameters increased significantly in visual grade 1+ compared to visual grade 0 and the means of the five parameters decreased significantly and proportionally as the visual grades increased from 1+ to 3+. A highly significant correlation was found to exist between the visual scoring results and the five SOT parameters. CONCLUSION: SOT can be used to evaluate the severity of SLS-induced edema objectively and can be extensively applied to evaluate the degree of severity in other inflammatory skin conditions.

Quantitative evaluation of severity in psoriatic lesions using three-dimensional morphometry.

The severity of psoriasis has been traditionally assessed by measures, such as the psoriasis area and severity index (PASI), the psoriasis severity scores, and the lesional severity scores. As a result, even experienced dermatologists show variations when attempting to determine the severity of psoriasis. Therefore, a better non-invasive and objective measurement of clinical signs is needed. In this study, an instrument, a so-called 'stereoimage optical topometer' (SOT), based on a new concept of 'stereoimaging' was used to measure the three-dimensional skin surface. The aim of this study was to compare the results obtained by the SOT with the visual score of psoriasis lesion. Thirty psoriatic patients were enrolled in this study. Initially, the severity of the infiltration and the scale of 134 psoriatic lesions were assessed by using a visual scoring system (0: none, 1: mild, 2: moderate, 3: severe, and 4: very severe), as scored by five dermatologists. The SOT was then used to quantify the severity of each psoriatic lesion using four three-dimensional SOT parameters (Sa, SL, SA, and SV). Secondly, the involved skin-surface area in the psoriasis cases was scored by the naked eye by the five dermatologists and by image analysis. Statistically significant differences were observed between grades 0, 1, 2, and 3 in terms of the severity measurements of the individual psoriatic lesions by SOT when using the parameters Sa, SL, SA, and SV. Therefore, it was concluded that there is a strong correlation between the results measured by visual scoring and by SOT in psoriasis.