bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of novel biodegradable aliphatic poly(ester amide)s containing cyclohexane units
Authors: Lecomte Hélène A. , Liggat John J. , Curtis Adam S. G. 
Published: January 2006

AbstractPolyesters provide a good basis to work on for designing novel biodegradable materials that are also mechanically and thermally resistant. In this study, a series of aliphatic poly(ester amide)s (PEA) based on cyclohexane units was synthesized. Block‐copolymers of cyclohexyl sebacate and cyclohexyl sebacamide were produced by controlling the length of the ester block and the amount of amide during a two‐step melt/interfacial polycondensation reaction. Films produced from these materials could retain their shape above 373 K due to the physical network of amide hydrogen‐bonding. Thermal properties were also evaluated, with various melting and softening points obtained depending on the PEA composition. The determining factor for mechanical properties was the amount of amide introduced, with films containing up to 10 mol % amide showing the best handleability and flexibility. Tensile properties typical of an amorphous viscoelastic material were observed, but with much superior elongation to break achievable (∼1700%). These materials were also shown to be hydrolyzable, noncytotoxic, and favorable for cell attachment: they may therefore have a promising future in the area of medical devices or packaging, especially as their properties can be tuned by changing their composition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1785–1795, 2006
Synthesis and characterization of glycidyl methacrylate/butyl acrylate copolymers obtained at a low temperature by atom transfer radical polymerization
Authors: de la Fuente José Luis , Cañamero Pedro Francisco , Fernández‐García Marta 
Published: January 2006

AbstractStatistical glycidyl methacrylate/butyl acrylate copolymerization, at three different feed monomer compositions (75:25, 50:50, and 25:75), was carried out under atom transfer radical polymerization conditions with ethyl 2‐bromoisobutyrate as an initiator, copper chloride as a catalyst, and N,N,N′,N″,N″‐pentamethyldiethylenetriamine as a ligand in 50% (v/v) toluene and diphenyl ether solutions and at 30 °C. Linear first‐order kinetics, linearly increasing molecular weight with conversion, and low polydispersities were observed for all the copolymerizations. The apparent propagation constant obtained for each molar fraction in the feed had similar values in the two solvents and increased as the glycidyl methacrylate molar fraction in the feed increased. The monomer reactivity ratios, 2.78 ± 0.32 for glycidyl methacrylate and 0.16 ± 0.07 for butyl acrylate, were estimated with the extended Kelen–Tüdos equation, and the copolymer compositions were determined by 1H NMR spectroscopy. The cumulative copolymer compositions as a function of conversion for the different molar fractions in the feed were quite consistent with the theoretically calculated values from the Mayo–Lewis terminal model. Moreover, the cure behavior of a copolymer with a commercial linear diamine was also analyzed by differential scanning calorimetry. A single exothermic peak was observed for a nonisothermal curing reaction, indicating the clear potential of the obtained copolymers for epoxy applications. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1807–1816, 2006
Errors induced in quartz crystal mass uptake measurements by nongravimetric effects: Considerations beyond the EerNisse caution
Authors: Banda Lameck , Alcoutlabi Mataz , McKenna Gregory B. 
Published: January 2006

AbstractWe report frequency changes in AT‐cut quartz crystals for glassy polymers subsequent to temperature and carbon dioxide pressure changes. Anomalous frequency shifts are observed for the crystal subsequent to such changes. Since, the Sauerbrey equation has been applied routinely for mass uptake measurements in glassy polymers, using the quartz crystal microbalance fitted with AT‐cut quartz crystals, it is important that nongravimetric effects that impact the frequency change be well understood. In the present work, we provide a quantitative analysis of the breakdown of the Sauerbrey equation for viscoelastic materials by using the Johannsmann (Macromol Chem Phys 1999, 200, 501) treatment of the response of AT‐cut crystals. Clearly, there exist significant errors in mass uptake measurements for materials deposited on AT‐cut quartz crystals when precautions pertaining to film thickness and viscoelastic compliance are ignored. We show that while the early caution of EerNisse on stress effects in AT‐cut quartz crystals can be important in mass uptake measurements, for polymers, the major source of error arises from viscoelastic effects in the coating. We conclude that mass uptake measurements for films of compliant materials and polymers above their glass transition cannot be performed with accuracy, using AT‐cut quartz crystals if the results are not corrected for frequency shifts due to viscoelastic effects of the overlayer unless the films are extremely thin, that is, less than 100 nm. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 801–814, 2006
Visual odometry for ground vehicle applications
Authors: Nistér David , Naroditsky Oleg , Bergen James 
Published: January 2006

AbstractWe present a system that estimates the motion of a stereo head, or a single moving camera, based on video input. The system operates in real time with low delay, and the motion estimates are used for navigational purposes. The front end of the system is a feature tracker. Point features are matched between pairs of frames and linked into image trajectories at video rate. Robust estimates of the camera motion are then produced from the feature tracks using a geometric hypothesize‐and‐test architecture. This generates motion estimates from visual input alone. No prior knowledge of the scene or the motion is necessary. The visual estimates can also be used in conjunction with information from other sources, such as a global positioning system, inertia sensors, wheel encoders, etc. The pose estimation method has been applied successfully to video from aerial, automotive, and handheld platforms. We focus on results obtained with a stereo head mounted on an autonomous ground vehicle. We give examples of camera trajectories estimated in real time purely from images over previously unseen distances (600 m) and periods of time. © 2006 Wiley Periodicals, Inc.
Recent developments in subterranean robotics
Authors: Morris Aaron , Ferguson Dave , Omohundro Zachary , Bradley David , Silver David , Baker Chris , Thayer Scott , Whittaker Chuck , Whittaker William 
Published: January 2006

AbstractRobotic systems exhibit remarkable capability for exploring and mapping subterranean voids. Information about subterranean spaces has immense value for civil, security, and commercial applications where problems, such as encroachment, collapse, flooding and subsidence can occur. Contemporary method for underground mapping, such as human surveys and geophysical techniques, can provide estimates of void location, but cannot achieve the coverage, quality, or economy of robotic approaches. This article presents the challenges, mechanisms, sensing, and software of subterranean robots. Results obtained from operations in active, abandoned, and submerged subterranean spaces will also be shown. © 2006 Wiley Periodicals, Inc.
Morbidity in patients waiting for tonsillectomy in Cardiff: a cross-sectional study
Authors: Fox R , Tomkinson A , Myers P 
Published: January 2006

Objective: Our aim was to determine the morbidity of patients awaiting tonsillectomy.Design: The study comprised a questionnaire survey of 379 children and 278 adults waiting over 12 months for tonsillectomy.Outcome measures: These comprised frequency of infection, sickness absence and continuing desire for surgery.Results: Response rates were 70 per cent (children) and 60 per cent (adults). Morbidity was similar in adults and children, and in those waiting more or less than two years. In the six months prior to the study, 86 per cent of children and 83 per cent of adults had had tonsillitis. Sixty per cent of children and 50 per cent of adults had had three or more episodes. Sixty-two per cent of children and 59 per cent of adults had had at least one long episode of tonsillitis, and 29 per cent of children and 24 per cent of adults had had more than three long episodes. Eighty-nine per cent of children had missed school at least once, compared with 71 per cent of adults missing work at least once (p = 0.01). The frequency of infection was significantly associated with patients' desire for surgery (p < 0.001).Conclusions: Patients awaiting tonsillectomy experience considerable morbidity. This study does not support the hypothesis that untreated patients will ‘outgrow’ their condition.
Systematic review of multi-symptom conditions in Gulf War veterans
Authors: THOMAS HOLLIE V. , STIMPSON NICOLA J. , WEIGHTMAN ALISON L. , DUNSTAN FRANK , LEWIS GLYN 
Published: January 2006

Background. Gulf War veterans have a number of health complaints. We therefore decided to carry out a systematic review to identify and summarize the findings from studies that have assessed multi-symptom conditions in Gulf War veterans and in an unexposed comparison group.Method. Studies published between January 1990 and May 2004 were identified by searching a large number of electronic databases. Reference lists and websites were also searched and key researchers were contacted. Studies were included if they compared the prevalence of chronic fatigue syndrome, multiple chemical sensitivity, CDC-defined chronic multi-symptom illness, fibromyalgia, or symptoms of either fatigue or numbness and tingling in Gulf War veterans and non-Gulf veterans. A total of 2401 abstracts were independently reviewed by two authors.Results. Twenty-three publications fulfilled the inclusion criteria. Gulf deployment was most strongly associated with chronic fatigue syndrome (OR 3·8, 95% CI 2·2–6·7). Gulf War veterans were also approximately three and a half times more likely than non-Gulf veterans to report multiple chemical sensitivity or chronic multi-symptom illness as defined by CDC. The methodological quality of the studies varied but the later and larger studies were of a high methodological standard with robust sampling strategies, adequate response rates and good adjustment for confounders.Conclusions. The results support the hypothesis that deployment to the Gulf War is associated with greater reporting of multi-symptom conditions.
Shiga toxin B‐subunit binds to the chaperone BiP and the nucleolar protein B23
Authors: Falguières Thomas , Johannes Ludger 
Published: January 2006

Background information. In many cell lines, such as HeLa cells, STxB (Shiga toxin B‐subunit) is transported from the plasma membrane to the ER (endoplasmic reticulum), via early/recycling endosomes and the Golgi apparatus, bypassing the late endocytic pathway. In human monocyte‐derived macrophages and dendritic cells that are not sensitive to Shiga toxin‐induced protein biosynthesis inhibition, STxB is not detectably targeted to the retrograde route and is degraded in late endosomes/lysosomes.Results. We have identified B‐subunit interacting proteins in HeLa cells and macrophages. In HeLa cells, the ER‐localized chaperone BiP (binding protein) was co‐immunoprecipitated with the B‐subunit. This interaction was not observed in macrophages, consistent with our previous trafficking results. In both cell types, the B‐subunit also interacted with the nucleolar protein B23. Consistently, the B‐subunit could be detected on nucleoli, suggesting that it could serve to bring the holotoxin to the site of synthesis of its molecular target, rRNA. The nucleolar localization data are critically discussed.Conclusion. The interaction of STxB with BiP, involved in the retrotranslocation process to the cytosol and nucleolar B23, as described in this study, might be of relevance for explaining the efficiency of even low doses of Shiga toxin to inactivate cellular ribosomes, and for the use of STxB as a vector for targeting antigens to cytosolic proteasomes of the MHC I‐restricted antigen presentation pathway.
PKB/AKT is involved in resumption of meiosis in mouse oocytes
Authors: Kalous Jaroslav , Solc Petr , Baran Vladimir , Kubelka Michal , Schultz Richard M. , Motlik Jan 
Published: January 2006

Background information. In fully grown mouse oocytes, a decrease in cAMP concentration precedes and is linked to CDK1 (cyclin‐dependent kinase 1) activation. The molecular mechanism for this coupling, however, is not defined. PKB (protein kinase B, also called AKT) is implicated in CDK1 activation in lower species. During resumption of meiosis in starfish oocytes, MYT1, a negative regulator of CDK1, is phosphorylated by PKB in an inhibitory manner. It can imply that PKB is also involved in CDK1 activation in mammalian oocytes.Results. We monitored activation of PKB and CDK1 during maturation of mouse oocytes. PKB phosphorylation and activation preceded GVBD (germinal vesicle breakdown) in oocytes maturing either in vitro or in vivo. Activation was transient and PKB activity was markedly reduced when virtually all of the oocytes had undergone GVBD. PKB activation was independent of CDK1 activity, because although butyrolactone I prevented CDK1 activation and GVBD, PKB was nevertheless transiently phosphorylated and activated. LY‐294002, an inhibitor of phosphoinositide 3‐kinase—PKB signalling, suppressed activation of PKB and CDK1 as well as resumption of meiosis. OA (okadaic acid)‐sensitive phosphatases are involved in PKB‐activity regulation, because OA induced PKB hyperphosphorylation. During resumption of meiosis, PKB phosphorylated on Ser473 is associated with nuclear membrane and centrosome, whereas PKB phosphorylated on Thr308 is localized on centrosome only.Conclusions. The results of the present paper indicate that PKB is involved in CDK1 activation and resumption of meiosis in mouse oocytes. The presence of phosphorylated PKB on centrosome at the time of GVBD suggests its important role for an initial CDK1 activation.
Transcriptional regulation of lysophosphatidic acid-induced interleukin-8 expression and secretion by p38 MAPK and JNK in human bronchial epithelial cells
Authors: Saatian Bahman , Zhao Yutong , He Donghong , Georas Steve N. , Watkins Tonya , Spannhake Ernst Wm , Natarajan Viswanathan 
Published: January 2006

HBEpCs (human bronchial epithelial cells) contribute to airway inflammation by secreting a variety of cytokines and chemokines in response to allergens, pathogens, viruses and environmental toxins and pollutants. The potent neutrophil chemoattractant, IL-8 (interleukin-8), is a major cytokine secreted by HBEpCs. We have recently demonstrated that LPA (lysophosphatidic acid) stimulated IL-8 production in HBEpCs via protein kinase C δ dependent signal transduction. However, mechanisms of IL-8 expression and secretion are complex and involve multiple protein kinases and transcriptional factors. The present study was undertaken to investigate MAPK (mitogen-activated protein kinase) signalling in the transcriptional regulation of IL-8 expression and secretion in HBEpCs. Exposure of HBEpCs to LPA (1 μM) enhanced expression and secretion of IL-8 by 5–8-fold and stimulated threonine/tyrosine phosphorylation of ERK (extracellular-signal-regulated kinase), p38 MAPK and JNK (c-Jun N-terminal kinase). The LPA-induced secretion of IL-8 was blocked by the p38 MAPK inhibitor SB203580, by p38 MAPK siRNA (small interfering RNA), and by the JNK inhibitor JNKi II, but not by the MEK (MAPK/ERK kinase) inhibitor, PD98059. LPA enhanced the transcriptional activity of the IL-8 gene; that effect relied on activation of the transcriptional factors NF-κB (nuclear factor κB) and AP-1 (activator protein-1). Furthermore, SB203580 attenuated LPA-dependent phosphorylation of IκB (inhibitory κB), NF-κB and phospho-p38 translocation to the nucleus, NF-κB transcription and IL-8 promoter-mediated luciferase reporter activity, without affecting the JNK pathway and AP-1 transcription. Similarly, JNKi II only blocked LPA-mediated phosphorylation of JNK and c-Jun, AP-1 transcription and IL-8 promoter-mediated luciferase reporter activity, without blocking p38 MAPK-dependent NF-κB transcription. Additionally, siRNA for LPA1–3 receptors partially blocked LPA-induced IL-8 production and activation of MAPKs. The LPA1 and LPA3 receptors, as compared with LPA2, were most efficient in transducing LPA-mediated IL-8 production. These results show an independent role for p38 MAPK and JNK in LPA-induced IL-8 expression and secretion via NF-κB and AP-1 transcription respectively in HBEpCs.
Ligand specificities and structural requirements of two Tachypleus plasma lectins for bacterial trapping
Authors: Kuo Tun-Hsun , Chuang Shiao-Cheng , Chang Sing-Yang , Liang Po-Huang 
Published: January 2006

TPL (Tachypleus plasma lectin)-1 was purified by using a Sepharose column and TPL-2 was purified from an LPS–Sepharose (LPS coupled to Sepharose matrix) affinity column, as described previously [Chiou, Chen, Y.-W., Chen, S.-C., Chao and Liu (2000) J. Biol. Chem. 275, 1630–1634] and the corresponding genes were cloned [Chen, Yen, Yeh, Huang and Liu (2001) J. Biol. Chem. 276, 9631–9639]. In the present study, TPL-1 and -2 were produced in yeast, and the recombinant proteins secreted into the media were purified and characterized. The proteins show specific PGN (peptidoglycan)- and LPS-binding activity, suggesting a role in trapping Gram-positive and Gram-negative bacteria respectively in innate immunity. Using BIAcore® assays, the dissociation constant for the TPL-1–PGN complex was measured as 8×10−8 M. Replacement of Asn74, the N-glycosylation site of TPL-1, with Asp abolishes the PGN-binding affinity, whereas the unglycosylated TPL-2 N3D mutant retains LPS-binding activity. DTT (dithiothreitol) treatment to break disulphide linkages abrogates TPL-2 activity but does not interfere with TPL-1 function. Cys4 in TPL-2 may form an intermolecular disulphide bond, which is essential for activity. As a result, the TPL-2 C4S mutant is inactive and is eluted as a monomer on a non-reducing gel. TPL-2 C6S is active and forms a non-covalently linked dimer. A model describing TPL-2 binding with LPS is proposed. These two plasma lectins that have different ligand specificities can be used for the detection and discrimination of bacteria and removal of endotoxins.
Effects of angiotensin-converting-enzyme inhibitors in combination with diuretics on blood pressure and renal injury in nitricoxide-deficiency-induced hypertension in rats
Authors: García-Estañ Joaquín , Ortiz M. Clara , O'Valle Francisco , Alcaraz Antonia , Navarro Esther G. , Vargas Félix , Evangelista Stefano , Atucha Noemí M. 
Published: January 2006

The present study investigates the effects of chronic administration of ACEIs (angiotensin-converting-enzyme inhibitors; either zofenopril or enalapril) in combination with a diruetic (hydrochlorothiazide) on BP (blood pressure) increase and renal injury induced by L-NAME (NG-nitro-L-arginine methyl ester), an inhibitor of NO (nitric oxide) synthesis. Rats were untreated or received L-NAME alone, L-NAME+zofenopril+hydrochlorothiazide or L-NAME+enalapril+hydrochlorothiazide for 8 weeks. L-NAME treatment resulted in marked elevation in BP and mortality. Treatment with either ACEI and diuretic prevented the increase in BP induced by L-NAME, reduced the death rate and improved excretory parameters. Renal injury in the L-NAME group was severe, but, in the groups treated with either ACEI and diuretic, glomerular and tubulointerstitial lesions were not observed and the intensity, number and size of vessels affected was reduced. However, the efficacy of zofenopril+diuretic was superior to that of enalapril+diuretic in reducing vascular alterations. Oxidative stress indices and the expression of NO synthase and nitrotyrosine were normalized by the treatments. In conclusion, the combined treatment of zofenopril or enalapril with hydrochlorothiazide completely prevented the development of arterial hypertension induced by L-NAME. Renal morphological and functional alterations in the hypertensive animals were also almost completely normalized, but the treatment with zofenopril+diuretic produced a more complete organ protection. The protective effect is related to an activation of endothelial NO synthase expression and to a normalization of the oxidative stress parameters due to the inhibition of angiotensin II.
Effect of high altitude and exercise on microvascular parameters in acclimatized subjects
Authors: Bauer Andreas , Demetz Florian , Bruegger Dirk , Schmoelz Martin , Schroepfer Sebastian , Martignoni André , Baschnegger Heiko , Hoelzl Josef , Thiel Manfred , Choukér Alexander , Peter Klaus , Gamble John , Christ Frank 
Published: January 2006

The role of microvascular fluid shifts in the adaptation to hypobaric hypoxia and its contribution to the pathophysiology of AMS (acute mountain sickness) is unresolved. In a systematic prospective study, we investigated the effects of hypobaric hypoxia and physical exercise alone, and in combination, on microvascular fluid exchange and related factors. We used computer-assisted VCP (venous congestion plethysmography) on the calves of ten altitude-acclimatized volunteers. We investigated the effects of: (i) actively climbing to an altitude of 3196 m, (ii) airlifting these subjects to the same altitude, and (iii) exercise at low altitude. CFC (capillary filtration capacity), Pvi (isovolumetric venous pressure) and Qa (calf blood flow) were assessed before and after each procedure and then repeated after an overnight rest. Measurements of CFC showed no evidence of increased microvascular permeability after any of the procedures. Pvi was significantly decreased (P&lt;0.001) from 20.3±4.4 to 8.9±4.3 mmHg after active ascent, and was still significantly lower (P=0.009) after overnight rest at high altitude (13.6±5.9 mmHg). No such changes were observed after the passive ascent (16.7±4.0 mmHg at baseline; 17.3±4.5 mmHg after passive ascent; and 19.9±5.3 mmHg after overnight rest) or after exercise at low altitude. After the active ascent, Qa was significantly increased. We also found a significant correlation between Qa, Pvi and the number of circulating white blood cells. In conclusion, we found evidence to support the hypothesis that increased microvascular permeability associated with AMS does not occur in acclimatized subjects. We also observed that the microvascular equilibrium pressure (Pvi) fell in inverse relation to the increase in Qa, especially in hypoxic exercise. We hypothesize that this inverse relationship reflects the haemodynamic changes at the microvascular interface, possibly attributable to the flow-induced increases in endothelial surface shear forces.