bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonspecific CD4+ T cells with uptake of antigen-specific dendritic cell-released exosomes stimulate antigen-specific CD8+ CTL responses and long-term T cell memory
Authors: Hao Siguo , Yuan Jinying , Xiang Jim 
Published: July 2007

AbstractDendritic cell (DC) and DC-derived exosomes (EXO) have been used extensively for tumor vaccination. However, its therapeutic efficiency is limited to only production of prophylactic immunity against tumors. T cells can uptake DC-released EXO. However, the functional effect of transferred exosomal molecules on T cells is unclear. In this study, we demonstrated that OVA protein-pulsed DC-derived EXO (EXOOVA) can be taken up by Con A-stimulated, nonspecific CD4+ T cells derived from wild-type C57BL/6 mice. The active EXO-uptaken CD4+ T cells (aTEXO), expressing acquired exosomal MHC I/OVA I peptide (pMHC I) complexes and costimulatory CD40 and CD80 molecules, can act as APCs capable of stimulating OVA-specific CD8+ T cell proliferation in vitro and in vivo and inducing efficient CD4+ Th cell-independent CD8+ CTL responses in vivo. The EXOOVA-uptaken CD4+ aTEXO cell vaccine induces much more efficient CD8+ T cell responses and immunity against challenge of OVA-transfected BL6-10 melanoma cells expressing OVA in wild-type C57BL/6 mice than EXOOVA. The in vivo stimulatory effect of the CD4+ aTEXO cell to CD8+ T cell responses is mediated and targeted by its CD40 ligand signaling/acquired exosomal CD80 and pMHC I complexes, respectively. In addition, CD4+ aTEXO vaccine stimulates a long-term, OVA-specific CD8+ T cell memory. Therefore, the EXOOVA-uptaken CD4+ T cells may represent a new, effective, EXO-based vaccine strategy in induction of immune responses against tumors and other infectious diseases.
Heteroaryl-susbstituted phenols as potential antioxidants
Authors: Ferrini Serena , Fusi Stefania , Ponticelli Fabio , Valoti Massimo 
Published: July 2007

Abstract
A series of O-heteroaryl phenols have been synthesised and structurally characterised. Photo-Fries rearrangement of these compounds represents a useful way to access the corresponding C-heteroaryl derivatives. The activity of the new phenolic compounds as radical scavengers towards the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS+•) has been evaluated. 2-tert-Butyl-4-(4-phenyl-isoxazol-3-ylmethoxy)-phenol (compound 3c) showed the highest scavenger activity (IC50 value (i.e. the concentration that scavenged 50% of the radicals) 3.17 × 10−6 M), which was one order of magnitude greater than that of the corresponding lead compound tert-butylhydroxy-anisole (BHA) (IC50 1.04 × 10−5 M). In further experiments, compound 3c showed dose-dependent inhibition of the oxidation of linoleic acid, as well as methaemoglobin formation, promoted by the presence of the radical generator 2,2′-azobis(amidino-propane) hydrochloride (AAPH) and it was markedly more potent than BHA in these assays.
Dihydroartemisinin exerts cytotoxic effects and inhibits hypoxia inducible factor-1α activation in C6 glioma cells
Authors: Huang Xiao-Jia , Ma Zhen-Qiu , Zhang Wei-Ping , Lu Yun-Bi , Wei Er-Qing 
Published: July 2007

Abstract
Artemisinin and its analogue dihydroartemisinin exert cytotoxic effects in some kinds of cancer cell lines. Here we determined whether dihydroartemisinin inhibits the growth and induces apoptosis of rat C6 glioma cells. We found dihydroartemisinin (5–25 μM) inhibited the growth and induced apoptosis of C6 cells in a concentration- and time-dependent manner; however, it was much less toxic to rat primary astrocytes. Dihydroartemisinin (5–25 μM) also increased the generation of reactive oxygen species in C6 cells. These effects of dihydroartemisinin were enhanced by ferrous ions (12.5–100 μM) and reduced by the iron chelator deferoxamine (25–200 μM). Immunoblotting analysis revealed that dihydroartemisinin (5–25 μM) significantly reduced hypoxia- and deferoxamine-induced expression of hypoxia inducible factor-1α and its target gene protein, vascular endothelial growth factor, in C6 cells. The results showed that dihydroartemisinin exerts a selective cytotoxic effect on C6 cells by increasing the reactive oxygen species and inhibiting hypoxia inducible factor-1α activation.
Novel methoxylated flavone inhibitors of cytochrome P450 1B1 in SCC-9 human oral cancer cells
Authors: Walle Thomas , Walle U Kristina 
Published: July 2007

AbstractDietary polyphenols, including flavonoids, have been implied to have cancer preventive properties. Suggested mechanisms include inhibition of carcinogen-activating cytochrome P450 (CYP) transcription and activities. These studies have focused mainly on CYP1A1. However, CYP1B1 has recently been shown to be of particular importance in smoking-induced oral and oesophageal cancer. Previous observations in our laboratory demonstrated that methoxylated flavonoids may be effective inhibitors of CYP1A1 transcription and activity as well as being orally bioavailable. In this study, an initial screening of 19 methoxylated flavones, using the ethoxyresorufin de-ethylation assay in human oral squamous cell carcinoma SCC-9 cells pretreated with 1μM benzo[a]pyrene, identified six strongly inhibitory compounds for further studies. The effect of these flavones on CYP1B1 mRNA expression was measured with quantitative branched DNA methodology. Four of the compounds −3′,4′-dimethoxyflavone and 5,7,4′-trimethoxyflavone and, in particular, 7,3′-dimethoxyflavone and 7,4′-dimethoxyflavone — were potent inhibitors of CYP1B1 mRNA expression. Two of the more common unmethylated polyphenols — curcumin and quercetin — were also potent inhibitors. Whereas most unmethylated polyphenols, such as curcumin and quercetin, have very poor bioavailability, the high metabolic stability of the methoxylated flavones studied here suggests that these CYP1B1 inhibitors may also be effective in-vivo.
Eugenosedin-A amelioration of lipopolysaccharide-induced up-regulation of p38 MAPK, inducible nitric oxide synthase and cyclooxygenase-2
Authors: Shen Kuo-Ping , Liou Shu-Fen , Hsieh Su-Ling , Chen Ing-Jun , Wu Bin-Nan 
Published: July 2007

AbstractIn this study, we investigate the protective effects of eugenosedin-A on p38 mitogen-activated protein kinase (MAPK), inflammatory nitric oxide (NO) and cyclooxygenase-2 (COX-2) pathways in a rat model of endotoxin shock. Rats were pretreated with eugenosedin-A, trazodone, yohimbine (1 mg kg−1, i.v.), aminoguanidine or ascorbic acid (15 mg kg−1, i.v.) 30 min before endotoxin challenge. Endotoxaemia was induced by a single i.v. injection of lipopolysaccharide (LPS, 10 mg kg−1). In rats not treated with eugenosedin-A, LPS increased plasma concentrations of NO and prostaglandin E2 (PGE2), and levels of p38 MAPK, inducible NO synthase (iNOS) and COX-2 proteins in the liver, lung, aorta and lymphocytes. In the pre-treated rats, eugenosedin-A not only inhibited the LPS-induced NO and PGE2 levels but also attenuated the LPS-induced increase in p38 MAPK and iNOS levels in the liver, aorta and lymphocytes. Eugenosedin-A also reduced LPS-induced COX-2 proteins in the aorta and lymphocytes. Likewise, aminoguanidine, ascorbic acid, yohimbine and trazodone were also found to decrease NO and PGE2 concentrations after endotoxin challenge. While aminoguanidine and ascorbic acid also attenuated the LPS-induced increase in p38 MAPK, iNOS and COX-2 proteins in the aorta and lymphocytes, trazodone and yohimbine inhibited only the increase in p38 MAPK, iNOS and COX-2 proteins in lymphocytes. Finally, eugenosedin-A (10−10-10−8 M) significantly inhibited the biphasic response induced by hydrogen peroxide (10−6-3 × 10−5 M) in rat denudated aorta. Taken together, the results of this study indicate that eugenosedin-A, as well as ascorbic acid, can attenuate free-radical-mediated aortic contraction and relaxation. It may therefore be able to reduce the damage caused by septic shock by inhibiting formation of p38 MAPK, iNOS, COX-2 and free radicals.
Recent developments in naturally derived antimalarials: cryptolepine analogues
Authors: Wright Colin W 
Published: July 2007

Abstract
Increasing resistance of Plasmodium falciparum to commonly used antimalarial drugs has made the need for new agents increasingly urgent. In this paper, the potential of cryptolepine, an alkaloid from the West African shrub Cryptolepis sanguinolenta, as a lead towards new antimalarial agents is discussed. Several cryptolepine analogues have been synthesized that have promising in-vitro and in-vivo antimalarial activity. Studies on the antimalarial modes of action of these analogues indicate that they may have different or additional modes of action to the parent compound. Elucidation of the mode of action may facilitate the development of more potent antimalarial cryptolepine analogues.
Development of strain gauge techniques for the measurement of propeller shaft torque in distant water trawlers
Authors: Bennett R , Hatfield M 
Published: July 2007

In the course of research and development work on deep sea fishing vessels, a continuing requirement is for a system to measure and record propeller shaft torque that will remain reliable and accurate on commercial fishing voyages of up to seven weeks duration, in the extreme environment of Arctic and North Atlantic waters, in all weathers, and at all seasons of the year. The system should be suitable for use in conjunction with dial indicators and recorders on voyages manned by development engineers and also suitable for use in automatic data logging systems. A system has been developed and tried consisting of d.c. energized foil strain gauges and simple slip rings consisting of silver strip wrapped on to the shaft, with unamplified readout on to galvanometers of either direct reading light spot type or those in trace recorders. The system can be used for the measurement of both steady and oscillatory torques. Almost 100 per cent reliability has been achieved on a number of installations. Both calibrated and uncalibrated installations have been used. The calibrated systems have an accuracy of better than 1 per cent. From experience gained to date the conclusion is drawn that an uncalibrated system can be expected to have a mean accuracy of about ±31/2 per cent, using the maker's gauge factors and a mean value of 11.9 ×106 for the torsional modulus for mild steel. In several vessels special short lengths of intermediate shafting have been provided in duplicate, in order to facilitate frequent re-calibration. Scatter in a given set of readings is low, the standard deviation being about 1 per cent at a surface stress of 3000——4000 lb/in2 (steaming power range) and up to about 21/2 per cent at stresses in the range 1200——2500 lb/in2 (trawling power). Determining scatter due to the variability of the instrument in the face of variations due to weather, ship displacement and other causes was one of the problems encountered during early trials on commercial voyages. It was anticipated that zero drift could be a very severe problem but this has not been the case. The maximum drift over several weeks has been 21/2 per cent of maximum torque and it has frequently been negligible. The system is now being applied to the measurement of thrust, using hollow shafts. Both torque and thrust signals are being fed into data loggers on certain trawlers. The problem of automatic logging of mean thrust and torque in the face of oscillations with periods of up to 14 seconds, induced by ship motion, without imposing heavy strains on analytical and computing facilities, has been solved.
A note on the elastic stress in tunnel linings
Authors: Jordan D. W. 
Published: July 2007

A circular tunnel lining is idealized as a perfectly elastic annulus either keyed to, or a sliding fit in a hole in an infinite elastic medium of different Young's modulus, the system being under stress at infinity. The solution to this problem is used to give a qualitative discussion of two situations: 1 The resistance of a tunnel lining is limited amongst other things by its inability to withstand tensile stress. It is shown that in the above idealization, the more flexible the lining the less likely are tensions to arise. Such flexibility might be achieved by allowing the lining freedom to slide relative to the surrounding rock rather than by keying it to the walls, by making it of laminated construction or by lowering its Young's modulus. Increasing the thickness may increase the liability to tension. 2 As a means of estimating the load on a lining, gauges may be placed to measure circumferential strain, and from these measurements the load is deduced by assuming that the lining behaves like a bending beam. A difficulty in interpreting such measurements is pointed out in the case of a keyed lining, when the shearing stresses are very large.
An experimental investigation of a right-angled single unreinforced mitred-bend subjected to various bending moments
Authors: Jones N , Kitching R 
Published: July 2007

It is well known that, upon the application of an in-plane bending moment, the initially circular cross-section of a curved pipe tends to flatten and become approximately elliptical in shape making it much more flexible than an equivalent straight tube. Mitred-bends exhibit similar properties though the behaviour is far more complex. A comprehensive study of a 90° single unreinforced mitred-bend having a radius/thickness ratio of 19 has been performed by means of a stress-probing method. In order to make the work more complete, results have been obtained for a similar bend when subjected to out-of-plane bending and twisting moments. Experimental measurements of stress and flexibility for each type of loading are discussed and certain modifications suggested to existing design procedures.
Natural frequencies of cooling tower shells
Authors: Neal B G 
Published: July 2007

A theoretical determination of the lowest natural frequencies of inextensional vibrations of hyperbolic cooling tower shells is first presented. It is shown that inextensional behaviour is only possible for certain types of support condition at the base, one of which consists of four pairs of inclined columns evenly spaced round the circumference which, at their points of attachment, only permit displacements normal to the plane of the shell. Experiments to determine the natural frequencies and modes of vibration of a model shell are then described. This model, which was made by the electro-deposition of copper on a Perspex mould, could be supported at its base by up to forty pairs of inclined columns. Using only four evenly spaced pairs of columns the lowest natural frequencies of inextensional vibrations were first determined, and found to agree well with the theoretical values. The natural frequencies and modes of the extensional vibrations which occurred when the shell was supported by forty pairs of columns were then explored. Finally, the effect of removing some of the supports, thereby simulating a horizontal fracture in part of the shell, was studied. The possibility of wind-induced vibrations occurring in practice is then considered. It is concluded that these are unlikely to occur unless the shell has already suffered damage, as for example by experiencing a horizontal fracture over part of its circumference near the base.
Axi-symmetric method for determining thermal stresses in pistons
Authors: Enderby L R , White D J 
Published: July 2007

An axi-symmetric method, which is easy to apply and is quick in yielding an answer, is presented for the analysis of thermal stresses in pistons. The designer who wishes to use the method will find the relevant formulae collected together in Appendix 2. The theory has been applied to four different pistons and it reproduced the general measured stress levels above the gudgeon-pin bosses, although the predicted stresses were in some cases up to 30 per cent lower than the maximum measured values. It is concluded that the method gives a useful description of the thermal stresses in this critical region.
A quick method of estimating the maximum stress in a longitudinally reciprocated bar
Authors: Beddoe B 
Published: July 2007

A dimensionless form of transient solution for a single reversal of a uniform bar is derived and interpreted in terms of reflected stress waves. It is shown that the maximum bar stress is simply related to the function that specifies the reversal of the bar and to the ratio of the return time (defined as the time for a longitudinal wave to propagate twice the length of the bar) to the reversal time. Uniformly distributed viscous damping may increase the maximum bar stress. This “one reversal” solution is invaluable for determining maximum stresses in cam-driven traverse bars on fibre-winding machines which carry uniformly spaced yarn guides. It can conveniently be used to determine the stress due to a regular succession of reversals and thereby provide solutions for continuous reciprocation, including resonant conditions, without recourse to Fourier analysis.
Tension-compression stress-strain curves from bending tests
Authors: Oldroyd P W J 
Published: July 2007

A formula—Nadai's bending formula—is derived which enables the tension (or compression) stress-strain curve for a material to be obtained from the curve relating bending moment to curvature for a beam of solid rectangular section. The method is extended to give a formula which covers deformations in which reversals of plastic strain occur. The results obtained from a unidirectional bending test made on annealed copper are compared with those obtained from a tensile test made on the same material and the accuracy of the stress-strain values obtained from the bending test is discussed. The results obtained from a reversed bending test are also compared with those obtained from a tension-compression test in which a specimen was first stretched and then compressed to its original length. The limitations imposed by this method of obtaining the stress-strain curve for a material are examined and the advantages its presents in the study of the behaviour of materials under uniaxial stress are outlined.
Thermal stresses in axially connected circular cylinders
Authors: Hallam C B , Ollerton E 
Published: July 2007

Experimental and theoretical investigations are reported concerning the stresses and deflections which occur in a composite cylinder due to a uniform rise in temperature. The composite cylinder consists of two solid circular cylinders, made of dissimilar materials but having the same diameter, which are stuck together so that their axes coincide. The interface between the two cylinders is a plane prependicular to their axes, and the lengths of both parts of the composite cylinder can vary. The composite cylinder is assumed to be free of stress initially. Theoretical results have been obtained by use of infinite-difference approximations to the governing equations and an iterative technique involving successive over-relaxation. These have been compared with experimental results obtained by a special application of the frozen-stress technique of photoelasticity.
Principal displacements in a pressurized elliptic cylinder: Theoretical predictions with experimental verification by laser interferometry
Authors: Holland M , Lalor M J , Walsh J 
Published: July 2007

Equations for principal displacements in a uniformly pressurized thin-walled cylinder having an elliptic median line are developed from a knowledge of the expressions for tension and bending moment (1) at a general position in the cylinder wall. Displacements derived from these equations are compared with the simple expressions presented by Bresse (2) and MacAlpine (3). The results of a detailed experimental study in which displacements were measured by a laser interferometer are used to assess the validity of the new displacement equations and to compare these with the predictions due to Bresse and MacAlpine. It is shown that the equations developed here give good agreement with experimentally measured displacements and furthermore the predictions made in (2) and (3) grossly overestimate the displacement values and are also very much in error when stating that the minor-diameter expansion is of the same order as the major-diameter contraction. In the investigation reported here (ellipse with mean aspect ratio 1.9509) the expansion of the minor diameter is approximately twice the value obtained for the contraction of the major diameter.
Stress analysis of adhesive-bonded lap joints
Authors: Adams R D , Peppiatt N A 
Published: July 2007

Stresses in a standard metal-to-metal adhesive-bonded lap joint are analysed by a two-dimensional finite-element method and comparisons are made with previous analyses. Particular attention is paid to the stresses at the ends of the adhesive layer. Unlike previous work, which assumes the adhesive to have a square edge, the adhesive spew is treated as a triangular fillet. The highest stresses exist at the adherend corner within the spew. Linear elastic behaviour is assumed throughout. A rubber model is reported which confirms these results physically. Good agreement was also obtained between some practical results and the finite-element predictions.
The effect of stress history on fatigue crack retardation behaviour
Authors: Obianyor D F , Miller K J 
Published: July 2007

The effect of a decrease in stress range on fatigue crack propagation behaviour in mild-steel plate is investigated. An experimentally determined equation relating the threshold stress intensity factor to stress intensity history is introduced and is seen to be a function of specimen thickness, which determines the crack tip stress—strain state. The delay period between the arrest of a stage II crack and its re-propagation is also a function of stress history and specimen thickness. The effect of increasing the initial high values of stress intensity is to cause the delay period and the threshold stress intensity to increase, both of which are beneficial, i.e. they increase fatigue lifetime.
Stress intensity factors in elastic plates with re-entrant corners asymmetrically loaded
Authors: Theocaris P S , Prassianakis J 
Published: July 2007

The method of reflected caustics was extended to evaluate the complex stress intensity factors at the roots of re-entrant corners in elastic plates under generalized plane-stress conditions. The plates were considered loaded under a general mode of loading creating asymmetric stress states at the corners and, thus, engendering complex stress intensity factors at these zones. For the evaluation of the complex stress intensity factors the coordinates of at least two points on the caustics are necessary whose polar coordinates on the respective initial curves on the specimen are defined in advance. These experimental data must be introduced into a system of six equations, four of which are linear and the remaining two non-linear. The solution of this system yields the components of the complex stress intensity factors with a high accuracy, independently of the form and shape of the caustics developed around the roots of the corners. This high accuracy was achieved among others by the fact that two terms in the asymptotic expansion of Muskhelishvili's complex stress function Φ(z) are taken into consideration for the evaluation of stress intensity factors. The method was applied first to a symmetric notch whose theoretical solution is known, so that the accuracy of the method could be checked, and afterwards to an asymmetrically loaded notch whose theoretical solution does not exist. For this case a recurrent procedure was applied for checking the accuracy of the experimental results.