124 research outputs found
Ion-implantation induced anomalous surface amorphization in silicon
Spectroscopic ellipsometry (SE), high-depth-resolution Rutherford backscattering (RBS) and channeling have been used to examine the surface damage formed by room temperature N and B implantation into silicon. For the analysis of the SE data we used the conventional method of assuming appropriate optical models and fitting the model parameters (layer thicknesses and volume fraction of the amorphous silicon component in the layers) by linear regression. The dependence of the thickness of the surface-damaged silicon layer (beneath the native oxide layer) on the implantation parameters was determined: the higher the dose, the thicker the disordered layer at the surface. The mechanism of the surface amorphization process is explained in relation to the ion beam induced layer-by-layer amorphization. The results demonstrate the applicability of Spectroscopic ellipsometry with a proper optical model. RBS, as an independent cross-checking method supported the constructed optical model
Genome-wide approaches for identification of nuclear receptor target genes
Large-scale genomics analyses have grown by leaps and bounds with the rapid advances in high throughput DNA sequencing and synthesis techniques. Nuclear receptor signaling is ideally suited to genomics studies because receptors function as ligand-regulated gene switches. This review will survey the strengths and limitations of three major classes of high throughput techniques widely used in the nuclear receptor field to characterize ligand-dependent gene regulation: expression profiling studies (microarrays, SAGE and related techniques), chromatin immunoprecipitation followed by microarray (ChIP-on-chip), and genome-wide in silico hormone response element screens. We will discuss each technique, and how each has contributed to our understanding of nuclear receptor signaling
Determination of complex dielectric functions of ion implanted and implantedāannealed amorphous silicon by spectroscopic ellipsometry
Measuring with a spectroscopic ellipsometer (SE) in the 1.8ā4.5 eV photon energy region we determined the complex dielectric function (Ļµ = Ļµ1 + iĻµ2) of different kinds of amorphous silicon prepared by selfāimplantation and thermal relaxation (500āĀ°C, 3 h). These measurements show that the complex dielectric function (and thus the complex refractive index) of implanted aāSi (iāaāSi) differs from that of relaxed (annealed) aāSi (rāaāSi). Moreover, its Ļµ differs from the Ļµ of evaporated aāSi (eāaāSi) found in the handbooks as Ļµ for aāSi. If we use this Ļµ to evaluate SE measurements of ion implanted silicon then the fit is very poor. We deduced the optical band gap of these materials using the DavisāMott plot based on the relation: (Ļµ2E2)1/3 ā¼ (Eā Eg). The results are: 0.85 eV (iāaāSi), 1.12 eV (eāaāSi), 1.30 eV (rāaāSi). We attribute the optical change to annihilation of point defects
Feasibility of sedation and analgesia interruption following cannulation in neonates on extracorporeal membrane oxygenation
Purpose: In most extracorporeal membrane oxygenation (ECMO) centers patients are heavily sedated to prevent accidental decannulation and bleeding complications. In ventilated adults not on ECMO, daily sedation interruption protocols improve short- and long-term outcome. This study aims to evaluate safety and feasibility of sedation interruption following cannulation in neonates on ECMO. Methods: Prospective observational study in 20 neonates (0.17-5.8 days of age) admitted for ECMO treatment. Midazolam (n = 20) and morphine (n = 18) infusions were discontinued within 30 min after cannulation. Pain and sedation were regularly assessed using COMFORT-B and visual analog scale (VAS) scores. Midazolam and/or morphine were restarted and titrated according to protocolized treatment algorithms. Results: Median (interquartile range, IQR) time without any sedatives was 10.3 h (5.0-24.1 h). Median interruption duration for midazolam was 16.5 h (6.6-29.6 h), and for morphine was 11.2 h (6.7-39.4 h). During this period no accidental extubations, decannulations or bleeding complications occurred. Conclusions: This is the first study to show that interruption of sedatives and analgesics following cannulation in neonates on ECMO is safe and feasible. Interruption times are 2-3 times longer than reported for adult ICU patients not on ECMO. Further trials are needed to substantiate these findings and evaluate short- and long-term outcomes
Progestogenic effects of tibolone on human endometrial cancer cells
Tibolone, a synthetic steroid acting in a tissue-specific manner and used
in hormone replacement therapy, is converted into three active
metabolites: a Delta(4) isomer (exerting progestogenic and androgenic
effects) and two hydroxy metabolites, 3 alpha-hydroxytibolone (3
alpha-OH-tibolone) and 3beta-OH-tibolone (exerting estrogenic effects). In
the present study an endometrial carcinoma cell line (Ishikawa PRAB-36)
was used to investigate the progestogenic properties of tibolone and its
metabolites. This cell line contains progesterone receptors A and B, but
lacks estrogen and androgen receptors. When tibolone was added to the
cells, complete conversion into the progestogenic/androgenic Delta(4)
isomer was observed within 6 d. Furthermore, when cells were cultured with
tibolone or when the Delta(4) isomer or the established progestagen
medroxyprogesterone acetate was added to the medium, marked inhibition of
growth was observed. Interestingly, 3 beta-OH-tibolone also induces some
inhibition of growth. These growth inhibitions were not observed in
progesterone receptor-negative parental Ishikawa cells, and
progestagen-induced growth inhibition of PRAB-36 cells could readily be
reversed using the antiprogestagen Org-31489. Upon measuring the
expression of two progesterone-regulated genes (fibronectin and
IGF-binding protein-3), tibolone, the Delta(4) isomer and
medroxyprogesterone acetate showed similar gene expression regulation.
These results indicate that tibolone, the Delta(4) metabolite, and to some
extent 3 beta-OH-tibolone exert progestogenic effects. Tibolone and most
likely 3 beta-OH-tibolone are converted into the Delta(4) metabolite
Consequences of loss of progesterone receptor expression in development of invasive endometrial cancer
PURPOSE: In endometrial cancer, loss of progesterone receptors (PR) is
associated with more advanced disease. This study aimed to investigate the
mechanism of action of progesterone and the loss of its receptors (PRA and
PRB) in development of endometrial cancer. EXPERIMENTAL DESIGN: A
9600-cDNA microarray analysis was performed to study regulation of gene
expression in the human endometrial cancer subcell line Ishikawa PRAB-36
by the progestagen medroxy progesterone acetate (MPA). Five MPA-regulated
genes were selected for additional investigation. Expression of these
genes was studied by Northern blot and by immunohistochemistry in Ishikawa
subcell lines expressing different PR isoforms. Additionally, endometrial
cancer tissue samples were immunohistochemically stained to study the in
vivo protein expression of the selected genes. RESULTS: In the PRAB-36
cell line, MPA was found to regulate the expression of a number of
invasion- and metastasis-related genes. On additional investigation of
five of these genes (CD44, CSPG/Versican, Tenascin-C, Fibronectin-1, and
Integrin-beta 1), it was observed that expression and progesterone
regulation of expression of these genes varied in subcell lines expressing
different PR isoforms. Furthermore, in advanced endometrial cancer, it was
shown that loss of expression of both PR and E-cadherin was associated
with increased expression CD44 and CSPG/Versican. CONCLUSION: The present
study shows that progestagens exert a modulatory effect on the expression
of genes involved in tumor cell invasion. As a consequence, loss of PR
expression in human endometrial cancer may lead to development of a more
invasive phenotype of the respective tumor
- ā¦