3,954 research outputs found
Microfluidic polymerase chain reaction
We implement microfluidic technology to miniaturize a thermal cycling system for amplifying DNA fragments. By using a microfluidic thermal heat exchanger to cool a Peltier junction, we have demonstrated rapid heating and cooling of small volumes of solution. We use a miniature K-type thermocouple to provide a means for in situ sensing of the temperature inside the microrefrigeration system. By combining the thermocouple, two power supplies controlled by a relay system, and computer automation, we reproduce the function of a commercial polymerase chain reaction thermal cycler and demonstrate amplification of a DNA sample of about 1000 base pairs
Design and fabrication of chemically robust three-dimensional microfluidic valves
A current problem in microfluidics is that poly(dimethylsiloxane) (PDMS), used to fabricate many microfluidic devices, is not compatible with most organic solvents. Fluorinated compounds are more chemically robust than PDMS but, historically, it has been nearly impossible to construct valves out of them by multilayer soft lithography (MSL) due to the difficulty of bonding layers made of non-stick fluoropolymers necessary to create traditional microfluidic valves. With our new three-dimensional (3D) valve design we can fabricate microfluidic devices from fluorinated compounds in a single monolithic layer that is resistant to most organic solvents with minimal swelling. This paper describes the design and development of 3D microfluidic valves by molding of a perfluoropolyether, termed Sifel, onto printed wax molds. The fabrication of Sifel-based microfluidic devices using this technique has great potential in chemical synthesis and analysis
Human Papillomavirus in Endometrial Adenocarcinomas: Infectious Agent or a Mere “Passenger”?
Aims. To investigate the possible association
of human papillomavirus (HPV) with endometrial hyperplasias and
neoplasia. Does HPV play any role in the initiation or
prognosis of endometrial adenocarcinomas?
Methods. Twenty-five endometrial adenocarcinomas
of the endometrioid cell type, with and without squamous
differentiation, and twenty-four endometrial hyperplasias of various
forms (simple, complex, and atypical) were analyzed for the
presence of type 16 and 18 HPV by the polymerase chain
reaction (PCR). The results were related to histopathological
features of the tumour, and the patients' age, and
prognosis. Results. Six of 25 endometrial
adenocarcinomas were HPV 16-positive
(24%),
and 5 of 25
(20%)
were HPV 18-positive. Simple endometrial hyperplasias was
associated somewhat more commonly with HPV 16 and 18 (2/8 and
1/8 cases, resp.) than hyperplasias progressing to
endometrial adenocarcinomas, namely, atypical endometrial
hyperplasia (1/8 and 0/8 cases, resp.). None of the
positive cases in the series, whether hyperplastic or
neoplastic, demonstrated cytological evidence of HPV
infection. There was no relation between HPV-positive cases
and squamous differentiation, depth of myometrial invasion,
lymphatic involvement, lymphocytic response, patients' age,
or prognosis. Conclusion. It appears that the
presence of HPV in the endometrium, as detected by PCR, does
not play any role in the initiation or prognosis of
endometrial adenocarcinoma
The Analgesic Effect of Oxytocin in Humans: A Double-Blind, Placebo-Controlled Cross-Over Study Using Laser-Evoked Potentials
Oxytocin is a neuropeptide regulating social‐affiliative and reproductive behaviour in mammals. Despite robust preclinical evidence for the antinociceptive effects and mechanisms of action of exogenous oxytocin, human studies have produced mixed results regarding the analgesic role of oxytocin and are yet to show a specific modulation of neural processes involved in pain perception. In the present study, we investigated the analgesic effects of 40 IU of intranasal oxytocin in 13 healthy male volunteers using a double‐blind, placebo‐controlled, cross‐over design and brief radiant heat pulses generated by an infrared laser that selectively activate Aδ‐ and C‐fibre nerve endings in the epidermis, at the same time as recording the ensuing laser‐evoked potentials (LEPs). We predicted that oxytocin would reduce subjective pain ratings and attenuate the amplitude of the N1, N2 and P2 components. We observed that oxytocin attenuated perceived pain intensity and the local peak amplitude of the N1 and N2 (but not of P2) LEPs, and increased the latency of the N2 component. Importantly, for the first time, the present study reports an association between the analgesic effect of oxytocin (reduction in subjective pain ratings) and the oxytocin‐induced modulation of cortical activity after noxious stimulation (attenuation of the N2 LEP). These effects indicate that oxytocin modulates neural processes contributing to pain perception. The present study reports preliminary evidence that is consistent with electrophysiological studies in rodents showing that oxytocin specifically modulates Aδ/C‐fibre nociceptive afferent signalling at the spinal level and provides further specificity to evidence obtained in humans indicating that oxytocin may be modulating pain experience by modulating activity in the cortical areas involved in pain processing
Validation of the Mind Excessively Wandering Scale and the Relationship of Mind Wandering to Impairment in Adult ADHD.
OBJECTIVE: This study investigates excessive mind wandering (MW) in adult ADHD using a new scale: the Mind Excessively Wandering Scale (MEWS). METHOD: Data from two studies of adult ADHD was used in assessing the psychometric properties of the MEWS. Case-control differences in MW, the association with ADHD symptoms, and the contribution to functional impairment were investigated. RESULTS: The MEWS functioned well as a brief measure of excessive MW in adult ADHD, showing good internal consistency (α > .9), and high sensitivity (.9) and specificity (.9) for the ADHD diagnosis, comparable with that of existing ADHD symptom rating scales. Elevated levels of MW were found in adults with ADHD, which contributed to impairment independently of core ADHD symptom dimensions. CONCLUSION: Findings suggest excessive MW is a common co-occurring feature of adult ADHD that has specific implications for the functional impairments experienced. The MEWS has potential utility as a screening tool in clinical practice to assist diagnostic assessment
A Gas Leak Rate Measurement System for the ATLAS MUON BIS-Monitored Drift Tubes
A low-cost, reliable and precise system developed for the gas leak rate measurement of the BIS-Monitored Drift Tubes (MDTs) for the ATLAS Muon Spectrometer is presented. In order to meet the BIS-MDT mass production rate, a total number of 100 tubes are tested simultaneously in this setup. The pressure drop of each one of the MDT is measured, within a typical time interval of 48 hours, via a differential manometer comparing with the pressure of a gas tight reference tube. The precision of the method implemented is based on the system temperature homogeneity, with accuracy of ÄT = 0.3 oC. For this reason, two thermally isolated boxes are used testing 50 tubes each of them, to achieve high degree of temperature uniformity and stability. After measuring several thousands of the MDTs, the developed system is confirmed to be appropriate within the specifications for testing the MDTs during the mass production
Author Correction: Effects of route of administration on oxytocin-induced changes in regional cerebral blood flow in humans
Synthesis and Application of Dye-Ligand Affinity Adsorbents
Dye-ligand affinity chromatography is a widely used technique in protein purification. The utility of the reactive dyes as affinity ligands results from their unique chemistry, which confers wide specificity towards a large number of proteins. They are commercially available, are inexpensive, and can easily be immobilized. Important factors that contribute to the successful operation of a dye-ligand chromatography include adsorbent properties, such as matrix type and ligand concentration, the buffer conditions used in the adsorption and elution stages, and contacting parameters like flow rate and column geometry. In general, with dye-ligand affinity chromatography, the specificity is provided by the adsorption and elution conditions employed in a particular purification, and these must often be worked out by trial and error. The present chapter provides protocols for the synthesis of dye-ligand affinity adsorbents as well as protocols for screening, selection, and optimization of a dye-ligand purification step. The purification of the glutathione transferases from Phaseolus vulgaris crude extract on Cibacron Blue 3GA-Sepharose is given as an example
System Test of the ATLAS Muon Spectrometer in the H8 Beam at the CERN SPS
An extensive system test of the ATLAS muon spectrometer has been performed in
the H8 beam line at the CERN SPS during the last four years. This spectrometer
will use pressurized Monitored Drift Tube (MDT) chambers and Cathode Strip
Chambers (CSC) for precision tracking, Resistive Plate Chambers (RPCs) for
triggering in the barrel and Thin Gap Chambers (TGCs) for triggering in the
end-cap region. The test set-up emulates one projective tower of the barrel
(six MDT chambers and six RPCs) and one end-cap octant (six MDT chambers, A CSC
and three TGCs). The barrel and end-cap stands have also been equipped with
optical alignment systems, aiming at a relative positioning of the precision
chambers in each tower to 30-40 micrometers. In addition to the performance of
the detectors and the alignment scheme, many other systems aspects of the ATLAS
muon spectrometer have been tested and validated with this setup, such as the
mechanical detector integration and installation, the detector control system,
the data acquisition, high level trigger software and off-line event
reconstruction. Measurements with muon energies ranging from 20 to 300 GeV have
allowed measuring the trigger and tracking performance of this set-up, in a
configuration very similar to the final spectrometer. A special bunched muon
beam with 25 ns bunch spacing, emulating the LHC bunch structure, has been used
to study the timing resolution and bunch identification performance of the
trigger chambers. The ATLAS first-level trigger chain has been operated with
muon trigger signals for the first time
Characteristics of patients presenting to the vascular emergency department of a tertiary care hospital: a 2-year study
<p>Abstract</p> <p>Background</p> <p>The structure of health care in Greece is receiving increased attention to improve its cost-effectiveness. We sought to examine the epidemiological characteristics of patients presenting to the vascular emergency department of a Greek tertiary care hospital during a 2-year period. We studied all patients presenting to the emergency department of vascular surgery at Red Cross Hospital, Athens, Greece between 1<sup>st </sup>January 2009 and 31st December 2010.</p> <p>Results</p> <p>Overall, 2452 (49.4%) out of 4961 patients suffered from pathologies that should have been treated in primary health care. Only 2509 (50.6%) needed vascular surgical intervention.</p> <p>Conclusions</p> <p>The emergency department of vascular surgery in a Greek tertiary care hospital has to treat a remarkably high percentage of patients suitable for the primary health care level. These results suggest that an improvement in the structure of health care is needed in Greece.</p
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