1,674 research outputs found
Synchrotron-radiation x-ray multiple diffraction applied to the study of electric-field-induced strain in an organic nonlinear optical material
In this work, distortions produced in the unit cell of a MBANP [(-)-2-(alpha-methylbenzylamino)-5-nitropyridine] nonlinear organic crystal under the influence of an applied electric field, (E) over bar, are investigated by using synchrotron-radiation x-ray multiple diffraction (XRMD). The method is based in the inherent sensitivity of this technique to determine small changes in the crystal lattice, which provide peak position changes in the XRMD pattern (Renninger scan). A typical Renninger scan shows numerous secondary peaks, each one carrying information on one particular direction within the crystal. The (hkl) peak position in the pattern, for a fixed wavelength, is basically a function of the unit cell lattice parameters. Thus small changes in any parameter due to a strain produced by (E) over right arrow give rise to a corresponding variation in the (hkl) peak position and the observed strain is related to the piezoelectric coefficients. The advantage of this method is the possibility of determining more than one piezoelectric coefficient from a single Renninger scan measurement [L. H. Avanci, L. P. Cardoso, S. E. Girdwood, D. Pugh, J. N. Sherwood, and K. J. Roberts, Phys. Rev. Lett. 81, 5426 (1998)]. The method has been applied to the MBANP (monoclinic, point group 2) crystal and we were able to determine four piezoelectric coefficients: \d(21)\ = 0.2(1) X 10(-11) CN-1, \d(22)\ = 24.8(3) X 10(-11) CN-1, \d(23)\ = 1.3(1) x 10(-11) CN-1, and \d(25)\ = 5.9(1) X 10(-11) CN-1. The measurements were carried out using the SRS stations 16.3, Daresbury Laboratory, Warrington, UK.61106507651
Effects of terlipressin as early treatment for protection of brain in a model of haemorrhagic shock
Introduction:
We investigated whether treatment with terlipressin during recovery from hypotension due to haemorrhagic shock (HS) is effective in restoring cerebral perfusion pressure (CPP) and brain tissue markers of water balance, oxidative stress and apoptosis.
Methods:
In this randomised controlled study, animals undergoing HS (target mean arterial pressure (MAP) 40 mmHg for 30 minutes) were randomised to receive lactated Ringer’s solution (LR group; n =14; volume equal to three times the volume bled), terlipressin (TERLI group; n =14; 2-mg bolus), no treatment (HAEMO group; n =12) or sham (n =6). CPP, systemic haemodynamics (thermodilution technique) and blood gas analyses were registered at baseline, shock and 5, 30, 60 (T60), 90 and 120 minutes after treatment (T120). After the animals were killed, brain tissue samples were obtained to measure markers of water balance (aquaporin-4 (AQP4)), Na+-K+-2Cl− co-transporter (NKCC1)), oxidative stress (thiobarbituric acid reactive substances (TBARS) and manganese superoxide dismutase (MnSOD)) and apoptotic damage (Bcl-x and Bax).
Results:
Despite the HS-induced decrease in cardiac output (CO) and hyperlactataemia, resuscitation with terlipressin recovered MAP and resulted in restoration of CPP and in cerebral protection expressed by normalisation of AQP4, NKCC1, TBARS and MnSOD expression and Bcl-x/Bax ratio at T60 and T120 compared with sham animals. In the LR group, CO and blood lactate levels were recovered, but the CPP and MAP were significantly decreased and TBARS levels and AQP4, NKCC1 and MnSOD expression and Bcl-x/Bax ratio were significantly increased at T60 and T120 compared with the sham group.
Conclusions:
During recovery from HS-induced hypotension, terlipressin was effective in normalising CPP and cerebral markers of water balance, oxidative damage and apoptosis. The role of this pressor agent on brain perfusion in HS requires further investigation
Phosphoinositide 3-Kinaseγ Controls the Intracellular Localization of CpG to Limit DNA-PKcs-Dependent IL-10 Production in Macrophages
Synthetic oligodeoxynucleotides containing unmethylated CpG motifs (CpG) stimulate innate immune responses. Phosphoinositide 3-kinase (PI3K) has been implicated in CpG-induced immune activation; however, its precise role has not yet been clarified. CpG-induced production of IL-10 was dramatically increased in macrophages deficient in PI3Kγ (p110γ−/−). By contrast, LPS-induced production of IL-10 was unchanged in the cells. CpG-induced, but not LPS-induced, IL-10 production was almost completely abolished in SCID mice having mutations in DNA-dependent protein kinase catalytic subunit (DNA-PKcs). Furthermore, wortmannin, an inhibitor of DNA-PKcs, completely inhibited CpG-induced IL-10 production, both in wild type and p110γ−/− cells. Microscopic analyses revealed that CpG preferentially localized with DNA-PKcs in p110γ−/− cells than in wild type cells. In addition, CpG was preferentially co-localized with the acidic lysosomal marker, LysoTracker, in p110γ−/− cells, and with an early endosome marker, EEA1, in wild type cells. Over-expression of p110γ in Cos7 cells resulted in decreased acidification of CpG containing endosome. A similar effect was reproduced using kinase-dead mutants, but not with a ras-binding site mutant, of p110γ. Thus, it is likely that p110γ, in a manner independent of its kinase activity, inhibits the acidification of CpG-containing endosomes. It is considered that increased acidification of CpG-containing endosomes in p110γ−/− cells enforces endosomal escape of CpG, which results in increased association of CpG with DNA-PKcs to up-regulate IL-10 production in macrophages
From DNA sequence to application: possibilities and complications
The development of sophisticated genetic tools during the past 15 years have facilitated a tremendous increase of fundamental and application-oriented knowledge of lactic acid bacteria (LAB) and their bacteriophages. This knowledge relates both to the assignments of open reading frames (ORF’s) and the function of non-coding DNA sequences. Comparison of the complete nucleotide sequences of several LAB bacteriophages has revealed that their chromosomes have a fixed, modular structure, each module having a set of genes involved in a specific phase of the bacteriophage life cycle. LAB bacteriophage genes and DNA sequences have been used for the construction of temperature-inducible gene expression systems, gene-integration systems, and bacteriophage defence systems.
The function of several LAB open reading frames and transcriptional units have been identified and characterized in detail. Many of these could find practical applications, such as induced lysis of LAB to enhance cheese ripening and re-routing of carbon fluxes for the production of a specific amino acid enantiomer. More knowledge has also become available concerning the function and structure of non-coding DNA positioned at or in the vicinity of promoters. In several cases the mRNA produced from this DNA contains a transcriptional terminator-antiterminator pair, in which the antiterminator can be stabilized either by uncharged tRNA or by interaction with a regulatory protein, thus preventing formation of the terminator so that mRNA elongation can proceed. Evidence has accumulated showing that also in LAB carbon catabolite repression in LAB is mediated by specific DNA elements in the vicinity of promoters governing the transcription of catabolic operons.
Although some biological barriers have yet to be solved, the vast body of scientific information presently available allows the construction of tailor-made genetically modified LAB. Today, it appears that societal constraints rather than biological hurdles impede the use of genetically modified LAB.
Discordance in glycemic categories and regression to normality at baseline in 10,000 people in a Type 2 diabetes prevention trial
The world diabetes population quadrupled between 1980 and 2014 to 422 million and the enormous impact of Type 2 diabetes is recognised by the recent creation of national Type 2 diabetes prevention programmes. There is uncertainty about how to correctly risk stratify people for entry into prevention programmes, how combinations of multiple ‘at high risk’ glycemic categories predict outcome, and how the large recently defined ‘at risk’ population based on an elevated glycosylated haemoglobin (HbA1c) should be managed. We identified all 141,973 people at highest risk of diabetes in our population, and screened 10,000 of these with paired fasting plasma glucose and HbA1c for randomisation into a very large Type 2 diabetes prevention trial. Baseline discordance rate between highest risk categories was 45.6 %, and 21.3 - 37.0 % of highest risk glycaemic categories regressed to normality between paired baseline measurements (median 40 days apart). Accurate risk stratification using both fasting plasma glucose and HbA1c data, the use of paired baseline data, and awareness of diagnostic imprecision at diagnostic thresholds would avoid substantial overestimation of the true risk of Type 2 diabetes and the potential benefits (or otherwise) of intervention, in high risk subjects entering prevention trials and programmes
Photonic quantum technologies
The first quantum technology, which harnesses uniquely quantum mechanical
effects for its core operation, has arrived in the form of commercially
available quantum key distribution systems that achieve enhanced security by
encoding information in photons such that information gained by an eavesdropper
can be detected. Anticipated future quantum technologies include large-scale
secure networks, enhanced measurement and lithography, and quantum information
processors, promising exponentially greater computation power for particular
tasks. Photonics is destined for a central role in such technologies owing to
the need for high-speed transmission and the outstanding low-noise properties
of photons. These technologies may use single photons or quantum states of
bright laser beams, or both, and will undoubtably apply and drive
state-of-the-art developments in photonics
The effect of radio-adaptive doses on HT29 and GM637 cells
<p>Abstract</p> <p>Background</p> <p>The shape of the dose-response curve at low doses differs from the linear quadratic model. The effect of a radio-adaptive response is the centre of many studies and well known inspite that the clinical applications are still rarely considered.</p> <p>Methods</p> <p>We studied the effect of a low-dose pre-irradiation (0.03 Gy – 0.1 Gy) alone or followed by a 2.0 Gy challenging dose 4 h later on the survival of the HT29 cell line (human colorectal cancer cells) and on the GM637 cell line (human fibroblasts).</p> <p>Results</p> <p>0.03 Gy given alone did not have a significant effect on both cell lines, the other low doses alone significantly reduced the cell survival. Applied 4 h before the 2.0 Gy fraction, 0.03 Gy led to a significant induced radioresistance in GM637 cells, but not in HT29 cells, and 0.05 Gy led to a significant hyperradiosensitivity in HT29 cells, but not in GM637 cells.</p> <p>Conclusion</p> <p>A pre-irradiation with 0.03 Gy can protect normal fibroblasts, but not colorectal cancer cells, from damage induced by an irradiation of 2.0 Gy and the application of 0.05 Gy prior to the 2.0 Gy fraction can enhance the cell killing of colorectal cancer cells while not additionally damaging normal fibroblasts. If these findings prove to be true in vivo as well this may optimize the balance between local tumour control and injury to normal tissue in modern radiotherapy.</p
Feasibility study of a clinically-integrated randomized trial of modifications to radical prostatectomy
<p>Abstract</p> <p>Background</p> <p>Numerous technical modifications to radical prostatectomy have been proposed. Such modifications are likely to lead to only slight improvements in outcomes. Although small differences would be worthwhile, an appropriately powered randomized trial would need to be very large, and thus of doubtful feasibility given the expense, complexity and regulatory burden of contemporary clinical trials. We have proposed a novel methodology, the clinically-integrated randomized trial, which dramatically streamlines trial procedures in order to reduce the marginal cost of an additional patient towards zero. We aimed to determine the feasibility of implementing such a trial for radical prostatectomy.</p> <p>Methods</p> <p>Patients undergoing radical prostatectomy as initial treatment for prostate cancer were randomized in a factorial design to involvement of the fascia during placement of the anastomotic sutures, urethral irrigation, both or neither. Endpoint data were obtained from routine clinical documentation. Accrual and compliance rates were monitored to determine the feasibility of the trial.</p> <p>Results</p> <p>From a total of 260 eligible patients, 154 (59%) consented; 56 patients declined to participate, 20 were not approached on recommendation of the treating surgeon, and 30 were not approached for logistical reasons. Although recording by surgeons of the procedure used was incomplete (~80%), compliance with randomization was excellent when it was recorded, with only 6% of procedures inconsistent with allocation. Outcomes data was received from 71% of patients at one year. This improved to 83% as the trial progressed.</p> <p>Conclusions</p> <p>A clinically-integrated randomized trial was conducted at low cost, with excellent accrual, and acceptable compliance with treatment allocation and outcomes reporting. This demonstrates the feasibility of the methodology. Improved methods to ensure documentation of surgical procedures would be required before wider implementation.</p> <p>Trial registration</p> <p>ClinicalTrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT00928850">NCT00928850</a></p
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