Terahertz imaging of human skin pathologies using laser feedback interferometry with quantum cascade lasers.

Early detection of skin pathologies with current clinical diagnostic tools is challenging, particularly when there are no visible colour changes or morphological cues present on the skin. In this study, we present a terahertz (THz) imaging technology based on a narrow band quantum cascade laser (QCL) at 2.8 THz for human skin pathology detection with diffraction limited spatial resolution. THz imaging was conducted for three different groups of unstained human skin samples (benign naevus, dysplastic naevus, and melanoma) and compared to the corresponding traditional histopathologic stained images. The minimum thickness of dehydrated human skin that can provide THz contrast was determined to be 50 µm, which is approximately one half-wavelength of the THz wave used. The THz images from different types of 50 µm-thick skin samples were well correlated with the histological findings. The per-sample locations of pathology vs healthy skin can be separated from the density distribution of the corresponding pixels in the THz amplitude-phase map. The possible THz contrast mechanisms relating to the origin of image contrast in addition to water content were analyzed from these dehydrated samples. Our findings suggest that THz imaging could provide a feasible imaging modality for skin cancer detection that is beyond the visible.

Modelling a Linker Mix-and-Match Approach for Controlling the Optical Excitation Gaps and Band Alignment of Zeolitic Imidazolate Frameworks.

Tuning the electronic structure of metal-organic frameworks is the key to extending their functionality to the photocatalytic conversion of absorbed gases. Herein we discuss how the band edge positions in zeolitic imidazolate frameworks (ZIFs) can be tuned by mixing different imidazole-based linkers within the same structure. We present the band alignment for a number of known and hypothetical Zn-based ZIFs with respect to the vacuum level. Structures with a single type of linker exhibit relatively wide band gaps; however, by mixing linkers of a low-lying conduction edge with linkers of a high-lying valence edge, we can predict materials with ideal band positions for visible-light water splitting and CO2 reduction photocatalysis. By introducing copper in the tetrahedral position of the mixed-linker ZIFs, it would be possible to increase both photo-absorption and the electron-hole recombination times.

Intraosseous Hibernoma in the Sacrum of an Adult.

Hibernoma is an uncommon lipomatous tumor composed of brown adipose cells that until recently has only ever been described in soft tissue locations. This report describes the histological features of a discrete lesion in the sacrum of an 84-year-old lady. Biopsy of this lesion demonstrated that it consisted predominantly of multivacuolated lipocytes with a morphological and immunohistochemical profile consistent with brown fat cells. The lesion was diagnosed as an intraosseous hibernoma. This is the 16th report in the English literature of a hibernoma occurring outside of a soft tissue location.

Reactivation of embryonic nodal signaling is associated with tumor progression and promotes the growth of prostate cancer cells.

BACKGROUND: Nodal is a member of the transforming growth factor ß (TGFß) superfamily that directs embryonic patterning and promotes the plasticity and tumorigenicity of tumor cells, but its role in the prostate is unknown. The goal of this study was to characterize the expression and function of Nodal in prostate cancer and determine whether, like other TGFß ligands, it modulates androgen receptor (AR) activity. METHODS: Nodal expression was investigated using immunohistochemistry of tissue microarrays and Western blots of prostate cell lines. The functional role of Nodal was examined using Matrigel and soft agar growth assays. Cross-talk between Nodal and AR signaling was assessed with luciferase reporter assays and expression of endogenous androgen regulated genes. RESULTS: Significantly increased Nodal expression was observed in cancer compared with benign prostate specimens. Nodal was only expressed by DU145 and PC3 cells. All cell lines expressed Nodal's co-receptor, Cripto-1, but lacked Lefty, a critical negative regulator of Nodal signaling. Recombinant human Nodal triggered downstream Smad2 phosphorylation in DU145 and LNCaP cells, and stable transfection of pre-pro-Nodal enhanced the growth of LNCaP cells in Matrigel and soft agar. Finally, Nodal attenuated AR signaling, reducing the activity of a PSA promoter construct in luciferase assays and down-regulating the endogenous expression of androgen regulated genes. CONCLUSIONS: An aberrant Nodal signaling pathway is re-expressed and functionally active in prostate cancer cells.