Energy distribution curves of ultrafast laser-induced field emission and their implications for electron dynamics

Energy distribution curves of laser-induced electron pulses from a tungsten tip have been measured as a function of tip voltage and laser power. Electron emission via tunneling through and/or excitation over the surface barrier from photoexcited nonequilibrium electron distributions are clearly observed. The spectral shapes largely vary with the emission processes and are strongly affected by electron dynamics. Simulations successfully reproduce the spectra, thus allowing direct insight into the involved electron dynamics and revealing the temporal tunability of electron emission via the two experimental parameters. These results should be useful to optimize the pulse characteristics for many applications based on ultrafast laser-induced electron emission.

Generalized solar lentigines in a patient with a history of radon exposure

A woman with generalized lentigines without associated non-cutaneous abnormalities is described. The patient showed brownish-pigmented flat or slightly elevated spots with a diameter of 1–5 mm. The histopathology of the lesions was compatible with a diagnosis of solar lentigines (SLs) or flat seborrhoeic keratosis. Unlike SLs, which develop typically on sun-damaged skin of the face, the dorsum of the hands and forearms, this patient showed the lentigines most prominently on the thighs and lower legs. Besides increased recreational UV exposure, the patient had a history of occupational radon exposure in a spa with radon-containing water. Genetic analysis identified a p.S249C FGFR3 hotspot mutation in 1 lesion, supporting the diagnosis of SLs. It remains elusive whether the occupational exposure to radon-containing water in addition to the recreational UV light exposure caused the unusual distribution of the SLs in this patient.

Low incidence of EGFR and HRAS mutations in cutaneous squamous cell carcinomas of a German cohort

Epidermal growth factor receptor (EGFR) is highly expressed in squamous cell carcinoma (SCC). The response of patients with lung cancer to EGFR inhibitors is significantly associated with the presence of EGFR mutations. Although these drugs have already been used for the treatment of advanced cutaneous SCC, the knowledge about EGFR mutations in this cancer is limited to one previous study in the US population. We analysed the presence of EGFR and concomitant HRAS mutations in a German cohort of 31 patients with cutaneous SCC by direct sequencing of EGFR and SNaPshot analysis of concomitant RAS mutations. We found a low prevalence of EGFR mutations (1/31; 3%) and HRAS mutations (1/31; 3%). The detected P741L EGFR mutation was proven to be somatic. Our results indicate that both EGFR and HRAS mutations are rare events in the carcinogenesis of cutaneous SCC, and therefore, only a small subgroup of patients will benefit from the screening for EGFR mutations in the run-up to targeted therapies with EGFR inhibitors.

Investigation of plasmon resonances in metal films with nanohole arrays for biosensing applications

Biosensing with nanoholes is one of the most promising applications of nanoplasmonic devices. The sensor properties, however, are complex due to coupled resonances through propagating and localized surface plasmons. This Full Paper demonstrates experimental and simulation studies on different plasmonic hole systems, namely various patterns of circular holes in gold films. In contrast to most previous work, here, the challenging situation of optically thin films is considered. The refractive-index-sensing properties, such as sensitive locations in the nanostructure and sensitive spectral features, are investigated. The multiple multipole program provides the complete field distribution in the nanostructure for different wavelengths. It is shown that the spectral feature most sensitive to refractive-index changes is the extinction minimum, rather than the maximum. The results are consistent with theory for perfect electrical conductors. The spectral response is investigated for molecular adsorption at different positions inside or outside a hole. Furthermore, the optical properties of nanohole arrays with long-range and short-range order are compared and found to demonstrate remarkable similarities. Our results help to predict the resonance wavelengths of nanoholes with arbitrary patterns, including short-range order. The results presented here are highly important since they extend and challenge several aspects of the current understanding of plasmon resonances in nanohole arrays. These theoretical models, simulation results, and experimental data together help provide the understanding necessary for the development of efficient biomolecular analysis tools based on metallic nanoholes.

Systemic epidermal nevus with involvement of the oral mucosa due to FGFR3 mutation

BACKGROUND

Epidermal nevi (EN) represent benign congenital skin lesions following the lines of Blaschko. They result from genetic mosaicism, and activating FGFR3 and PIK3CA mutations have been implicated.

CASE PRESENTATION

We report a female patient with a systemic keratinocytic nevus also involving the oral mucosa. Molecular genetic analysis revealed a mosaicism of the FGFR3 hotspot mutation R248C in the EN lesions of the skin and of the oral mucosa. The detection of the R248C mutation in a proportion of blood leukocytes and a slight scoliosis suggest an EN syndrome.

CONCLUSIONS

Our results show that activating FGFR3 mutations can also affect the oral mucosa and that extracutaneous manifestations of EN syndrome can be subtle. We highlight the theoretical risk of the patient having an offspring with thanatophoric dysplasia as gonadal mosaicism for the R248C mutation cannot be excluded.

Fully Metal-Coated Scanning Near-Field Optical Microscopy Probes with Spiral Corrugations for Superfocusing under Arbitrarily Oriented Linearly Polarised Excitation

We study the effect of a spiral corrugation on the outer surface of a fully metal-coated scanning near-field optical microscopy (SNOM) probe using the finite element method. The introduction of a novel form of asymmetry, devoid of any preferential spatial direction and covering the whole angular range of the originally axisymmetric tip, allows attaining strong field localization for a linearly polarised mode with arbitrary orientation. Compared to previously proposed asymmetric structures which require linearly polarised excitation properly oriented with respect to the asymmetry, such a configuration enables significant simplification in mode injection. In fact, not only is the need for the delicate procedure to generate radially polarised beams overcome, but also the relative alignment between the linearly polarised beam and the tip modification is no longer critical.

Skin alterations due to illegal drug abuse

Drug abuse is associated with a wide variety of skin alterations. Being aware of the typical signs and symptoms of the drug addicts' skin is of special importance to dermatologists, even though dermatologists are commonly not involved in the treatment of these patients. There is yet a chance for dermatologists to identify drug abusers early by to some extent specific cutaneous signs and after exclusion of several other etiological factors, so that this will lead to further treatment through the respective specialists. The objective of this paper is to draw particular attention to typical skin lesions and diseases which may be associated with drug abuse.

Absence of BRAF and HRAS mutations in eruptive Spitz naevi

BACKGROUND

Eruptive Spitz naevi have been reported rarely in the literature. In solitary Spitz naevi, BRAF and HRAS mutations, as well as increased copy numbers of chromosome 11p have been identified.

OBJECTIVES

To investigate the genetic changes underlying eruptive Spitz naevi.

METHODS

We report on a 16-year-old boy who developed multiple disseminated eruptive Spitz naevi within a few months. We analysed BRAF, HRAS, KRAS and NRAS genes in 39 naevi from this patient for hotspot mutations. Furthermore, comparative genomic hybridization analysis was performed in three lesions.

RESULTS

None of the Spitz naevi displayed a mutation in the analysed genes, and no chromosomal imbalances were observed. Conclusions  Our results indicate that the typical genetic alterations described in solitary Spitz naevi appear to be absent in eruptive Spitz naevi. Yet unknown alternative genetic alterations must account for this rare syndrome.

Identification of new genes associated with melanoma

PURPOSE

Repeated failures in melanoma therapy made clear that the molecular mechanisms leading to melanoma are still poorly understood. In this study, we aim to provide a more comprehensive understanding of the transcriptional profiles and signalling pathways associated with melanoma.

METHODS

Gene expression was analysed using the Affymetrix Human Genome U133A 2.0 GeneChip arrays. To avoid culture artifacts, we used microdissected fresh frozen material of 18 melanocytic nevi (MN), 20 primary melanomas (PM) and 20 metastatic melanomas (MM). Statistical analysis was performed with Genomatix Chipinspector, Ingenuity™ Software, SPSS Software and Partek Genomic Suite 6.4. Expression levels of selected transcripts were verified by quantitative real-time RT-PCR and immunostaining of a tissue microarray sampling more than 280 cases of MN, PM and MM with known clinical outcome.

RESULTS

A total of 284 differentially expressed genes was detected in PM compared with MN and 189 genes in MM compared with PM affecting common cancer pathways such as MAPK-, Wnt- and Notch-signalling. Using principal component analysis, the samples could be grouped according to their histological entity. We identified a panel of novel melanoma-associated markers: frizzled-related protein, an antagonist of Wnt; tranducin-like enhancer of split 1, a transcription factor partner of TCF/LEF-1; CNTN1, an activator of Notch signalling; two Serpin peptidase inhibitors, Serpin B3/B4 and the TGF-β family member GDF15, the latter with association to MAPK-signalling.

Fast numerical methods for the design of layered photonic structures with rough interfaces

A multilayer approach (MA) and modified boundary conditions (MBC) are proposed as fast and efficient numerical methods for the design of 1D photonic structures with rough interfaces. These methods are applicable for the structures, composed of materials with an arbitrary permittivity tensor. MA and MBC are numerically validated on different types of interface roughness and permittivities of the constituent materials. The proposed methods can be combined with the 4x4 scattering matrix method as a field solver and an evolutionary strategy as an optimizer. The resulted optimization procedure is fast, accurate, numerically stable and can be used to design structures for various applications.

Mutational activation of FGFR3 is not involved in the development of prostate cancer

OBJECTIVE

The mutational constitutive activation of FGFR3 has been discovered in several malignancies but only limited data on FGFR3 mutations in prostate cancer are available. Most recently, activating FGFR3 mutations were described as being associated with low-grade prostate tumors. Therefore, we investigated the FGFR3 mutation status in a comprehensive series of prostate tumors.

METHODS

102 archival formalin-fixed paraffin-embedded prostate tumors of patients treated with radical prostatectomy [with a low-grade subgroup (Gleason score ≤6) of 29 patients] as well as 29 incidental prostate tumors [low-grade tumors (Gleason score ≤6); n = 22] and 16 benign prostatic hyperplasia samples obtained by transurethral resection of the prostate were investigated. After microdissection and DNA isolation, all FGFR3 mutation hotspots discovered in human malignancies were analyzed using the SNaPshot(©) approach or restriction fragment length polymorphism (RFLP) analysis.

RESULTS

All cases could successfully be analyzed by SNaPshot; 80 cases were investigated using RFLP. No mutation in FGFR3 could be detected in any of the analyzed cases.

CONCLUSION

The most recently reported FGFR3 mutations in low-grade prostate tumors could not be verified in our series. There were also no mutations in prostate tumors from patients with concomitant bladder tumors as reported previously. These data suggest that the mutational activation of FGFR3 plays no important role in prostate carcinogenesis, which is in accordance with previous studies performed on smaller tumor cohorts.

Antiproliferative effects of rapamycin and celecoxib in angiosarcoma cell lines

BACKGROUND/AIM

Beyond their primary field of application some well-established drugs exhibit antitumour effects in a variety of cancers. The aim of this study was to investigate the effects of the COX2 inhibitor celecoxib and the mTOR antagonist rapamycin on angiosarcoma cell lines.

MATERIALS AND METHODS

Cell proliferation was measured in ASM, ISOS 1 and ISO HAS angiosarcoma cell lines with the BrdU assay.

RESULTS

In all angiosarcoma cell lines, celecoxib as well as rapamycin inhibited cell growth in a dose-dependent manner. In ASM and ISOS 1, but not in ISO HAS angiosarcoma cells, additive growth inhibitory effects were detected by combining both agents.

CONCLUSION

Our results indicate that angiosarcoma cell proliferation can be inhibited by subtoxic doses of rapamycin and celecoxib. Due to their direct and stroma-mediated anticancer activities, mTOR antagonists and COX2 inhibitors represent very promising drugs in the palliative treatment of angiosarcoma.

[R248C FGFR3 mutation. Effect on cell growth, apoptosis and attachment in HaCaT keratinocytes]

Activating FGFR3 mutations have been identified in a variety of benign skin lesions (seborrheic keratosis, epidermal nevus, solar lentigo). However, the functional consequences of these mutations in the human epidermis are unknown. We therefore analyzed functional effects of the common R248C mutation in HaCaT keratinocytes. The cells were stably transduced with the R248C FGFR3 mutation or FGFR3-IIIb wildtype sequence using a retroviral system. The R248C mutant keratinocytes revealed significantly enhanced cell growth compared with wildtype cells after reaching confluence. Likewise, apoptosis and attachment to fibronectin were significantly reduced in mutant cells. In contrast, there was no difference regarding migration and oncogene-induced senescence. Gene expression analysis revealed only a few differentially expressed genes between mutant and wildtype HaCaT keratinocytes. ERK1/2 appear to be involved in the FGFR3-dependent signalling of R248C mutant keratinocytes. Our results indicate that an increased cell number at confluence along with reduced apoptosis may contribute to the growth of benign acanthotic tumors in the human epidermis.

Electrochemistry on a localized surface plasmon resonance sensor

The optical signal of a localized surface plasmon resonance (LSPR)-based sensor combined with electrochemistry was investigated. Gold nanoparticles were immobilized on an indium tin oxide (ITO) substrate, which functioned as working electrode. Using cyclic voltammetry synchronized with LSPR sensing, surface reactions on gold were detected both electrically and optically. In the capacitive charging regime, optical signals linear to the applied potential were detected. Gold was found to be dissolved above the oxidation potential and partially redeposited during the reduction, which changed size and conformation of the gold nanoparticles. In kinetic measurements, slower potential establishment was observed at lower salt concentrations. Simulations by multiple multipole program (MMP) suggested the formation of a lossy layer by combination of charge depletion of gold and negative ion adsorption even below the reaction potential. We consider the results presented here of importance for any future sensors based on combined plasmonics and electrochemistry.

Optical sensing and determination of complex reflection coefficients of plasmonic structures using transmission interferometric plasmonic sensor

The combination of interferometry and plasmonic structure, which consists of gold nanoparticle layer, sputter coated silicon oxide spacer layer, and aluminum mirror layer, was studied in transmission mode for biosensing and refractive index sensing applications. Because of the interferometric nature of the system, the information of the reflection amplitude and phase of the plasmonic layer can be deduced from one spectrum. The modulation amplitude in the transmission spectrum, caused by the interference between the plasmonic particle layer and the mirror layer, increases upon the refractive index increase around the plasmonic particles due to their coherent backscattering property. Our proposed evaluation method requires only two light sources with different wavelengths for a stable self-referenced signal, which can be easily and precisely tuned by a transparent spacer layer thickness. Unlike the standard localized surface plasmon sensors, where a sharp resonance peak is essential, a broad band plasmon resonance is accepted in this method. This leads to large fabrication tolerance of the plasmonic structures. We investigated bulk and adsorption layer sensitivities both experimentally and by simulation. The highest sensitivity wavelength corresponded to the resonance of the plasmonic particles, but useful signals are produced in a much broader spectral range. Analysis of a single transmission spectrum allowed us to access the wavelength-dependent complex reflection coefficient of the plasmonic particle layer, which confirmed the reflection amplitude increase in the plasmonic particle layer upon molecular adsorption.