76 research outputs found
Through-membrane electron-beam lithography for ultrathin membrane applications
We present a technique to fabricate ultrathin (down to 20 nm) uniform
electron transparent windows at dedicated locations in a SiN membrane for in
situ transmission electron microscopy experiments. An electron-beam (e-beam)
resist is spray-coated on the backside of the membrane in a KOH- etched cavity
in silicon which is patterned using through-membrane electron-beam lithography.
This is a controlled way to make transparent windows in membranes, whilst the
topside of the membrane remains undamaged and retains its flatness. Our
approach was optimized for MEMS-based heating chips but can be applied to any
chip design. We show two different applications of this technique for (1)
fabrication of a nanogap electrode by means of electromigration in thin
free-standing metal films and (2) making low-noise graphene nanopore devices
Use of polyethylene glycol coatings for optical fibre humidity sensing
Humidity induced change in the refractive index and thickness of the polyethylene glycol (PEG) coatings are in situ investigated for a range from 10 to 95%, using an optical waveguide spectroscopic technique. It is experimentally demonstrated that, upon humidity change, the optical and swelling characteristics of the PEG coatings can be employed to build a plastic fibre optic humidity sensor. The sensing mechanism is based on the humidity induced change in the refractive index of the PEG film, which is directly coated onto a polished segment of a plastic optical fibre with dip-coating method. It is observed that PEG, which is a highly hydrophilic material, shows no monotonic linear response to humidity but gives different characteristics for various ranges of humidity levels both in index of refraction and in thickness. It undergoes a physical phase change from a semi-crystal line structure to a gel one at around 80% relative humidity. At this phase change point, a drastic decrease occurs in the index of refraction as well as a drastic increase in the swelling of the PEG film. In addition, PEG coatings are hydrogenated in a vacuum chamber. It is observed that the hydrogen has a preventing effect on the humidity induced phase change in PEG coatings. Finally, the possibility of using PEG coatings in construction of a real plastic fibre optic humidity sensor is discussed. (C) 2008 The Optical Society of Japan
p27(Kip1 )is expressed in proliferating cells in its form phosphorylated on threonine 187
BACKGROUND: G1/S cell cycle progression requires p27(Kip1 )(p27) proteolysis, which is triggered by its phosphorylation on threonine (Thr) 187. Since its levels are abundant in quiescent and scarce in cycling cells, p27 is an approved marker for quiescent cells, extensively used in histopathology and cancer research. METHODS: However here we showed that by using a specific phosphorylation site (pThr187) antibody, p27 is detectable also in proliferative compartments of normal, dysplastic and neoplastic tissues. RESULTS: In fact, whereas un-phosphorylated p27 and MIB-1 showed a significant inverse correlation (Spearman R = -0.55; p < 0,001), pThr187-p27 was positively and significantly correlated with MIB-1 expression (Spearman R = 0.88; p < 0,001). Thus proliferating cells only stain for pThr187-p27, whereas they are un-reactive with the regular p27 antibodies. However increasing the sensitivity of the immunocytochemistry (ICH) by the use of an ultra sensitive detection system based on tiramide signal amplification, simultaneous expression and colocalisation of both forms of p27 was shown in proliferating compartments nuclei by double immunofluorescence and laser scanning confocal microscopy studies. CONCLUSION: Overall, our data suggest that p27 expression also occurs in proliferating cells compartments and the combined use of both regular and phospho- p27 antibodies is suggested
Prognostic value of p27(Kip1 )expression in Basaloid Squamous Cell Carcinoma of the larynx
BACKGROUND: Very few reports have investigated the role of cell cycle regulators as biomarkers in Basaloid Squamous Cell Carcinoma (BSCC) of the larynx, a definite morphologic, uncommon, very aggressive variant of squamous cell carcinoma. Lower expression of Ki67/Mib-1, a proliferation marker highly expressed in the majority of tumours, and p53, a tumour suppressor protein that can induce an arrest of the G1-S transition, was related to a better prognosis in laryngeal BSCC. In the head and neck, p27(kip1), a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors, has emerged as an independent prognostic factor, able to identify low-expressing tumours with unfavourable course. Up to date the role of this protein was never studied in BSCC. Aim of our study was to investigate the potential prognostic value of p27(kip1 )levels and their correlation with Ki67/Mib-1 and p53 expression in BSCC of the larynx. METHODS: The retrospective study group consisted of 15 male and 1 female patients, affected by laryngeal BSCC, ranging in age from 44 to 69 years (mean 58). The tumour originated from the supraglottis in thirtheen cases and from the glottis in the remaining three. Ten patients had metastatic cervical lymph nodes at presentation and were classified as N+. Post surgical stage was IV in four patients, III in nine, II in two cases and I in the remaining one. Follow-up ranged from a minimum of 5 months up to 9 years. Paraffin-embedded tissue sections of each laryngeal tumour were analyzed for p27(kip), Ki67/Mib-1 and p53 expression by immunohistochemistry. RESULTS: The immunohistochemical study showed p27(kip1 )expression in 40% of the patients with no evidence of disease (NED) and in none (0%) of the patients dead of disease (DOD), whilst p53 was expressed in 60% of patients in NED status and in 90% of patients in DOD status. Ki67/Mib-1 was positive in 80% of NED patients and in 100% of DOD patients. At multivariate analysis, performed by means of Discriminant analysis, low levels of p27(kip1 )expression significantly correlated with poor prognosis (P < 0.05). CONCLUSION: p27(kip1 )protein has been shown to be a significant independent prognostic factor in laryngeal SCC. In our series of laryngeal BSCC the resulting data seem to confirm the clinical prognostic relevance of p27(kip1 )low expression, which directly correlated with biological aggressiveness and consequent shortened survival
Detection of BRAF mutation in colorectal cancer patients and compare the tumors and normal tissues with PNA clamp qPCR
Effect of vitamin A pretreatment on Escherichia coli-induced lipid peroxidation and level of 3-nitrotyrosine in kidney of guinea pig
In the present study, we report the effect of vitamin A (Vit A, retinol palpitate) on kidney lipid peroxidation and 3-nitrotyrosine (3-NT) levels induced after Escherichia coli administration to guinea pigs. Vit A was administrated intraperitoneally (i.p.) to guinea pigs at a dose 15,000 IU/kg per day for 7 days prior to E. coli injection. On day 8, the animals were injected i.p. with E. coli dosed at 12 x10(9) colony forming units per kilogram. Kidneys were collected 6 h after administration of E. coli. Malondialdehyde (MDA) as a lipid peroxidation product, and 3-NT levels were measured by reverse phase high-performance liquid chromatography. There was a significant increase in MDA and 3-NT levels in lipopolysaccaharide-induced group (p < 0.001). 3-NT was not detectable in kidney of normal control animals. However, Vit A administration prior to E. coli injection prevented 3-NT formation but did not prevent the rice in MDA level of kidney (p < 0.001). Vit A alone did not alter the MDA level in the kidney of the control group
E-cadherin gene C-160A promoter polymorphism and risk of colorectal cancer in a Turkish population
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