Rapid fabrication of polymer microfluidic systems for the production of artificial lipid bilayers

A polymer microfluidic device has been fabricated using rapid prototyping techniques. The device was built up to allow the formation and subsequent investigation of artificial bilayer lipid membranes (BLMs). A simple dry film photoresist stamp was used to hot emboss microfluidic channels into PMMA films. Laser micromachining was employed to form an aperture into PMMA films. Laser micromachining was employed to form an aperture through the PMMA channels, across which the BLM was later formed. The dry film phororesist was also used as a simple etch mask for the deep etching of glass substrates in buffered HF solutions, which was used in this work for the production of glass embossing stamps. We show that bilayer films can be successfully produced across laser micromachined apertures in PMMA films

A Method to Determine the In-Air Spatial Spread of Clinical Electron Beams

We propose and analyze in detail a method to measure the in-air spatial spread parameter of clinical electron beams. Measurements are performed at the center of the beam and below the adjustable collimators sited in asymmetrical configuration in order to avoid the distortions due to the presence of the applicator. The main advantage of our procedure lies in the fact that the dose profiles are fitted by means of a function which includes, additionally to the Gaussian step usually considered, a background which takes care of the dose produced by different mechanisms that the Gaussian model does not account for. As a result, the spatial spread is obtained directly from the fitting procedure and the accuracy permits a good determination of the angular spread. The way the analysis is done is alternative to that followed by the usual methods based on the evaluation of the penumbra width. Besides, the spatial spread found shows the quadratic-cubic dependence with the distance to the source predicted by the Fermi-Eyges theory. However, the corresponding values obtained for the scattering power are differing from those quoted by ICRU nr. 35 by a factor ~2 or larger, what requires of a more detailed investigation.Comment: 11 pages, 5 Postscript figures, to be published in Medical Physic

Changes in vitamin biomarkers during a 2-year intervention trial involving increased fruit and vegetable consumption by free-living volunteers

Peer reviewedPublisher PD

Quantification of functionalised gold nanoparticle-targeted knockdown of gene expression in HeLa cells

Introduction: Gene therapy continues to grow as an important area of research, primarily because of its potential in the treatment of disease. One significant area where there is a need for better understanding is in improving the efficiency of oligonucleotide delivery to the cell and indeed, following delivery, the characterization of the effects on the cell. Methods: In this report, we compare different transfection reagents as delivery vehicles for gold nanoparticles functionalized with DNA oligonucleotides, and quantify their relative transfection efficiencies. The inhibitory properties of small interfering RNA (siRNA), single-stranded RNA (ssRNA) and single-stranded DNA (ssDNA) sequences targeted to human metallothionein hMT-IIa are also quantified in HeLa cells. Techniques used in this study include fluorescence and confocal microscopy, qPCR and Western analysis. Findings: We show that the use of transfection reagents does significantly increase nanoparticle transfection efficiencies. Furthermore, siRNA, ssRNA and ssDNA sequences all have comparable inhibitory properties to ssDNA sequences immobilized onto gold nanoparticles. We also show that functionalized gold nanoparticles can co-localize with autophagosomes and illustrate other factors that can affect data collection and interpretation when performing studies with functionalized nanoparticles. Conclusions: The desired outcome for biological knockdown studies is the efficient reduction of a specific target; which we demonstrate by using ssDNA inhibitory sequences targeted to human metallothionein IIa gene transcripts that result in the knockdown of both the mRNA transcript and the target protein

A visible light-activated direct-bonding material: An in vivo comparative study

A clinical trial was carried out to evaluate and compare the clinical performance of a visible light-cured material with a chemically cured adhesive. This was used in combination with two types of bracket base. Fifty-two patients entered the trial and 542 bracket bases were placed. The incidence and site of bond failure were recorded. The overall failure rate for the light-cured material in combination with both types of bracket was 4.7% and 6% for the chemical-cured adhesive. There were no significant differences detected between the failure rates for both types of adhesive in combination with either bracket base, and no bracket base/adhesive combination proved superior (p > 0.05). When the data were examined in an overall manner, a significantly higher posterior tooth failure rate was detected for all adhesive/base combinations (p <0.001). © 1989

Development of a Proton Radiation Therapy Facility at IUCF

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

The future of medical diagnostics: Review paper

While histopathology of excised tissue remains the gold standard for diagnosis, several new, non-invasive diagnostic techniques are being developed. They rely on physical and biochemical changes that precede and mirror malignant change within tissue. The basic principle involves simple optical techniques of tissue interrogation. Their accuracy, expressed as sensitivity and specificity, are reported in a number of studies suggests that they have a potential for cost effective, real-time, in situ diagnosis. We review the Third Scientific Meeting of the Head and Neck Optical Diagnostics Society held in Congress Innsbruck, Innsbruck, Austria on the 11th May 2011. For the first time the HNODS Annual Scientific Meeting was held in association with the International Photodynamic Association (IPA) and the European Platform for Photodynamic Medicine (EPPM). The aim was to enhance the interdisciplinary aspects of optical diagnostics and other photodynamic applications. The meeting included 2 sections: oral communication sessions running in parallel to the IPA programme and poster presentation sessions combined with the IPA and EPPM posters sessions. © 2011 Jerjes et al; licensee BioMed Central Ltd

Status of the IUCF Proton Radiation Therapy Facility

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Determination of the combined effect of grape seed extract and cold atmospheric plasma on foodborne pathogens and their environmental stress knockout mutants

The aim of this study was to explore the antimicrobial efficacy of grape seed extract (GSE) and cold atmospheric plasma (CAP) individually or in combination against L. monocytogenes and E. coli wild type (WT) and their isogenic mutants in environmental stress genes. More specifically, we examined the effects of 1 % (w/v) GSE, 4 min of CAP treatment, and their combined effect on L. monocytogenes 10403S WT and its isogenic mutants ΔsigB, ΔgadD1, ΔgadD2, ΔgadD3, as well as E. coli K12 and its isogenic mutants ΔrpoS, ΔoxyR, ΔdnaK. Additionally, the sequence of the combined treatments was tested. A synergistic effect was achieved for all L. monocytogenes strains when exposure to GSE was followed by CAP 31 treatment. However, the same effect was observed against E. coli strains, only for the reversed treatment sequence. Additionally, L. monocytogenes ΔsigB was more sensitive to the individual GSE and the combined GSE/CAP treatment, whereas ΔgadD2 was more sensitive to CAP, as compared to the rest of the mutants under study. Individual GSE exposure was unable to inhibit E. coli strains, and individual CAP treatment resulted in higher inactivation of E. coli in comparison to L. monocytogenes with the strain ΔrpoS appearing the most sensitive among all studied strains. Our findings provide a step towards a better understanding of the mechanisms playing a role in tolerance/sensitivity of our model Gram-positive and Gram negative bacteria towards GSE, CAP and their combination. Therefore, our results contribute to the development of more effective and targeted antimicrobial strategies for sustainable decontamination

Controlled delivery of membrane proteins to artificial lipid bilayers by nystatin-ergosterol modulated vesicle fusion

The study of ion channels and other membrane proteins and their potential use as biosensors and drug screening targets require their reconstitution in an artificial membrane. These applications would greatly benefit from microfabricated devices in which stable artificial lipid bilayers can be rapidly and reliably formed. However, the amount of protein delivered to the bilayer must be carefully controlled. A vesicle fusion technique is investigated where composite ion channels of the polyene antibiotic nystatin and the sterol ergosterol are employed to render protein-carrying vesicles fusogenic After fusion with an ergosterol-free artificial bilayer the nystatin-ergosterol channels do not dissociate immediately and thus cause a transient current signal that marks the vesicle fusion event. Experimental pitfalls of this method were identified, the influence of the nystatin and ergosterol concentration on the fusion rate and the shape of the fusion event marker was explored, and the number of different lipid was reduced. Under these conditions, the B-amyloid peptide could be delivered in a controlled manner to a standard planar bilayer. Additionally, the electrical recordings were obtained of vesicles fusing with a planar lipid bilayer in a microfabricated device, demonstrating the suitability of nystatin-ergosterol modulated vesicle fusion for protein delivery within microsystems