bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification and characterization of the central segment of prothymosin‐α: methodology for handling highly acidic peptides
Authors: Wilson Christopher L. , Monteith William B. , Danell Allison S. , Burns Colin S. 
Published: September 2006

AbstractProthymosin‐α is a highly acidic protein consisting of 110 amino acids. The central segment of this protein, residues 51–89, is thought to be involved in metal binding which may be necessary for its physiological function. To carry out studies of this peptide, this central segment was synthesized in a linear fashion using Fmoc‐based methods on rink amide MBHA resin. However, this peptide could not be purified with the typical straightforward approach of RP HPLC followed by negative mode electrospray ionization mass spectrometry (ESI‐MS). This was attributed to the high proportion of acidic residues: 26 out of the 39 residues are aspartic and glutamic acids. The acidity of the peptide prevented retention on the RP HPLC column. Additionally, the ability of the highly negatively charged peptide to retain sodium ions prevented molecular weight determination with ESI‐MS. A systematic approach to the purification of this highly acidic peptide was undertaken. Ultimately, strong anion exchange chromatography was used to purify the peptide. Extensive desalting using dialysis was required prior to ESI‐MS, and the choice of the buffer proved to be critical. In the end, a purification method was devised that yielded a highly purified peptide and is readily compatible with analysis by ESI‐MS. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis and biological activity of homoarginine‐containing opioid peptides
Authors: Izdebski Jan , Kunce Danuta , Schiller Peter W. , Chung Nga N. , Gers Tomasz , Zelman Monika , Grabek Monika 
Published: September 2006

AbstractTwo tris‐alkoxycarbonyl homoarginine derivatives, Boc‐Har{ω,ω′‐[Z(2Br)]2}‐OH and Boc‐Har{ω,ω′‐[Z(2Cl)]2}‐OH, were prepared by guanidinylation of Boc‐Lys‐OH, and used for the synthesis of neo‐endorphins and dynorphins. The results were compared with that obtained in the synthesis in which Boc‐Lys(Fmoc)‐OH was incorporated into the peptide chain, and after removing Fmoc protection, the resulting peptide‐resin was guanidinylated with N,N′‐[Z(2Br)]2‐ or N,N′‐[Z(2Cl)]2‐S‐methylisourea. The peptides were tested in the guinea‐pig ileum (GPI) and mouse vas deferens (MVD) assays. The results indicated that replacement of Arg by Har may be a good avenue for the design of biologically active peptides with increased resistance to degradation by trypsin‐like enzymes. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Afterglow, TL and IRSL in beta‐irradiated HPHT type Ib synthetic diamond
Authors: Meléndrez R. , Schreck M. , Chernov V. , Preciado‐Flores S. , Pedroza‐Montero M. , Barboza‐Flores M. 
Published: September 2006

AbstractThe presence of nitrogen or other impurities in HPHT type Ib synthetic diamond may produce shallow or deep localized trapping states for electrons (holes) with activation energies below the conduction (above the valence) band. The present work deals with room temperature afterglow (AG), thermoluminescence (TL) and infrared‐stimulated luminescence (IRSL) in HPHT type Ib diamond. The existence of vacancy impurity‐related defects gives rise to a characteristic AG, TL and IRSL in beta‐irradiated samples. The AG luminescence decays fast, decreasing to about 103 of its initial intensity value in 100 s. The deconvoluted TL glow curve is composed of a 1.4‐order peak at 375 K and three first‐order kinetics peaks at 442, 475 and 514 K. The IRSL was excited with 830 nm light releasing electrons from the trapping states with different efficiencies. The TL glow curve was found to be non‐reproducible because the multiple impurity‐related defects induced by irradiation are unstable at temperatures around 800 K. The peculiar AG and TL behavior observed in the investigated HPHT type Ib synthetic diamond may hinder its application in TL dosimetry. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of nanocrystalline diamond films deposited by microwave plasma CVD system at low substrate temperatures
Authors: Potocky S. , Kromka A. , Potmesil J. , Remes Z. , Polackova Z. , Vanecek M. 
Published: September 2006

AbstractNanocrystalline diamond (NCD) films were grown by microwave plasma CVD in hydrogen‐based gas mixture. Deposition experiments were performed at different temperatures varying from 370 to 1100 °C. Before growth step, silicon (100) oriented substrates were nucleated by bias enhanced nucleation procedure and glass substrates were pretreated in ultrasonic bath. Optical, structural and morphological properties of NCD films were systematically studied by using an optical spectroscopy, scanning electron microscopy and Raman spectroscopy. NCD films were optically transparent in wide range and had high refractive index of 2.34. All deposited samples exhibited diamond characteristic line in the Raman spectrum. The growth kinetic was attributed to the hydrogen abstraction model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrochemical oxidation and reduction processes at diamond electrodes of varying phase purity
Authors: Foord John , Hu Jing Ping 
Published: September 2006

AbstractDiamond electrodes were prepared by MWCVD, using varying methane‐to‐hydrogen feedstock ratios to form both micro‐ and nano‐crystalline samples. Although Raman spectroscopy indicated substantial concentrations of non‐diamond carbon in the nanodiamond forms, XPS and ELS measurements confirm that the area‐averaged concentration of such material in the outer layers is very low. Nonetheless, pronounced electrochemical signatures associated with disordered sp2 carbon phases are detected, at sites which are highly aggregated in the grain boundaries. Potential cycling in nitric acid presents an effective route for the complete removal of sp2 carbon material from the electrodes, but this then leads to the formation, of what electrochemically, are completely inactive nanodiamond phases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An investigation of structural and electrical properties of boron doped and undoped nanocrystalline diamond films
Authors: Hikavyy A. , Clauws P. , Maes J. , Moshchalkov V. V. , Butler J. E. , Feygelson T. , Williams O. A. , Daenen M. , Haenen K. 
Published: September 2006

AbstractNanocrystalline and microcrystalline undoped and boron doped diamond films are investigated by means of SEM, Raman and photocurrent techniques. SEM measurements on nanocrystalline diamond show the typical diamond columnar structure whereas for microcrystalline diamond such structure is not observed. Raman investigation shows a clear diamond peak at 1332 cm–1 for all investigated films and a Fano resonance is observed for the microcrystalline sample prepared with 2000 ppm of boron in the gas mixture indicating a transition into the semi‐metallic state. Photocurrent measurements also show a presence of boron in some films. It is found that when temperature is decreased lower than 80 K, the boron photocurrent threshold in the case of NCD material behaves differently compared to bulk diamond. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bulk and surface‐enhanced Raman spectroscopy of nitrogen‐doped ultrananocrystalline diamond films
Authors: Vlasov I. I. , Ralchenko V. G. , Goovaerts E. , Saveliev A. V. , Kanzyuba M. V. 
Published: September 2006

AbstractUltrananocrystalline diamond films (UNCD) grown in an Ar‐rich microwave plasma with nitrogen gas added in amounts of 0–25% were studied by Raman spectroscopy using 514.5 and 413.1 nm laser excitation. Besides the Raman spectra of diamond, the first and second order Raman scattering of disordered graphite and polyacetylene were detected and analyzed for samples with different nitrogen content. With surface enhanced Raman scattering (SERS) a variety of surface vibrational modes was observed: (i) CHx stretching vibrations of sp3 and sp2 hybridized carbon in the range of 2800–3100 cm–1; (ii) the sp2 and sp1 hybridized CC(CN) stretching modes in the range of 1600–2300 cm–1; and (iii) lines in the range of 200–1250 cm–1 related to different kinds of vibrations of substituted aromatic rings. These results indicate that in N‐doped UNCD films the intergrain material is a well connected mixture of predominantly sp2 phase with some amount of sp1 phase of carbon and nitrogen that is suggested to provide high electrical conductivity. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study on the adsorption of armchair carbon nanotubes on the hydrogenated surface of diamond
Authors: Sque Stephen J. , Jones Robert , Öberg Sven , Briddon Patrick R. 
Published: September 2006

AbstractFirst‐principles density‐functional theory has been used to investigate the interaction of (metallic) (7,7) carbon nanotubes with the hydrogenated (001) surface of diamond. There is no evidence for a significant chemical interaction between the nanotubes and the diamond surface, although an appreciable binding energy is obtained. The corresponding electronic band structures are indicative of moderate electron transfer from the diamond substrate to the nanotube, which would in practice leave behind a mobile layer of holes. These results suggest that carbon nanotubes may, like buckminsterfullerene, act as suitable p‐type transfer dopants for diamond. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoelastic constants in diamond and silicon
Authors: Hounsome L. S. , Jones R. , Shaw M. J. , Briddon P. R. 
Published: September 2006

AbstractAb Initio calculations, using density functional theory within the AIMPRO code, have been performed on bulk diamond and silicon in order to calculate the change in the dielectric constant due to strain, and hence the values of the photoelastic tensors. A combination of compressive and tensile strain has been applied to two atom unit cells of Si and diamond and the tensors relating to p 11 + 2p 12, p 12 – 2p 11 and p 44 extracted. Good agreement is found with experimental results for absolute values and frequency dependence of the constants for silicon. Results are also given for diamond where experimental data is much more limited and scattered. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Seeding, growth and characterization of nanocrystalline diamond films on various substrates
Authors: Daenen M. , Williams O. A. , D'Haen J. , Haenen K. , Nesládek M. 
Published: September 2006

AbstractBy optimizing seeding techniques and plasma parameters for deposition, nanocrystalline diamond (NCD) films were deposited on different sorts of substrates with varying parameters such as temperature and methane content. Results of this optimization process were analysed by SEM, XRD, Raman, and transmission measurements. Experiments with titanium interlayers lead to a better understanding of the nucleation step and can enhance the nucleation density. This research resulted in homogeneously coalesced NCD films of less than 100 nm thickness over 3 inch Si wafers. It is also shown that it is possible to grow on different sorts of glass, using a low temperature process. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of boron concentration on the XPS spectra of the (100) surface of homoepitaxial boron‐doped diamond films
Authors: Ghodbane S. , Ballutaud D. , Deneuville A. , Baron C. 
Published: September 2006

AbstractAs‐grown (100) homoepitaxial diamond films with boron concentrations [B] from 4.6 × 1016 to 1.5 × 1021 cm–3 have been analysed using X‐ray photoelectron spectroscopy (XPS). Their C 1s core levels contain a dominant component around 284.17 ± 0.2 eV ascribed to sp3 C and a main secondary component around 284.88 ± 0.2 eV ascribed to CHx (x ≥ 2) on surface defects. Their relative concentration decreases and increases, respectively, as [B] increases. A significant component around 286.4 ± 0.2 eV ascribed to ether group (C–O–C) remains nearly constant up to [B] ≈ 3 × 1020 cm–3, then increases for greater boron concentrations. Other components around 283.0 ± 0.2, 287.69 ± 0.2 and 288.76 ± 0.2 eV ascribed, respectively, to sp2 C, carbonyl (C=O) and carboxyl (HO–C=O) on surface defects remain with low concentrations. The occurrence of these XPS components, their assignments and their relative concentrations are satisfactorily compared to those previously found for IIb crystals with (100) surface and for polycrystalline films with [B] around 1019 and 7 × 1020 cm–3. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unusual morphological features of natural diamond samples characterized with Micro Raman Spectroscopy
Authors: Sachdev Hermann , Kramlich Erwin 
Published: September 2006

AbstractIn the present study, unusual morphological features of natural diamonds were characterized by Micro Raman Spectroscopy. The growth of diamond crystallites through secondary nucleation was observed in microscopic cracks in natural specimens. The protrusion of small gaps in the diamond crystal by the growth medium was leading to the formation of 2nd and higher generation crystallites without the deposition of additional phases. This fact clearly indicates that a highly mobile and volatile flux system has to be held responsible for the secondary diamond growth. Specific features of natural diamond samples can be interpreted as growth forms from volatile or highly mobile liquid species in the C–H–O‐system, thus merging CVD and hydrothermal conditions in the latter system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study on the adsorption of armchair carbon nanotubes on the hydrogenated surface of diamond
Authors: Sque Stephen J. , Jones Robert , Öberg Sven , Briddon Patrick R. 
Published: September 2006

AbstractThe cover picture from the article [1] is the electronic band structure calculated by first‐principles density‐functional theory for a metallic (7,7) nanotube adsorbed on the (001)‐(2 × 1):H diamond surface. Occupied and empty levels are shown as thick dark and thin lighter lines, respectively, while the shaded regions indicate the valence and conduction bands of bulk diamond. The dashed horizontal line is the electron chemical potential. Due to the electron transfer from the diamond to the nanotube a hole is created at the top of the diamond valence band.This issue contains papers presented at SBDD XI. After the celebration of the 10th edition of the successful series of meetings in 2005, this year the 11th International Workshop on Surface and Bulk Defects in CVD Diamond Films was hosted in Diepenbeek–Hasselt, Belgium.
Depressive Symptomatology among HIV‐Positive Women in the Era of HAART: A Stress and Coping Model
Authors: Remien Robert H. , Exner Theresa , Kertzner Robert M. , Ehrhardt Anke A. , Rotheram-Borus Mary Jane , Johnson Mallory O. , Weinhardt Lance S. , Kittel Lauren E. , Goldstein Rise B. , Pinto Rogério M. , Morin Stephen F. , Chesney Margaret A. , Lightfoot Marguerita , Gore-Felton Cheryl , Dodge Brian , Kelly Jeffrey A. ,   NIMH Healthy Living Project Trial Group
Published: September 2006

AbstractObjective: An enhanced stress and coping model was used to explain depression among HIV‐positive women in healthcare and community settings where highly active anti‐retroviral treatment (HAART) was commonplace. Method: HIV‐infected women in four cities (N=978) were assessed, cross‐sectionally, for mental and physical health, stress, social support, and other background factors. Results: Self‐reported level of depressive symptomatology was high. Number of physical symptoms, illness intrusiveness, and perceived stress were positively associated with depressed mood, while coping self‐efficacy and social support were negatively associated. Stress mediated the effect of health status on depression and coping self‐efficacy mediated the effect of psychosocial resources on depression. Our enhanced stress and coping model accounted for 52% of variance in depressive symtpomatology. Conclusions: Interventions focused on improving coping self‐efficacy, bolstering social supports, and decreasing stress in the lives of HIV‐positive women may help to reduce the negative effects of HIV disease on mood.
Microtubular and actin cytoskeletons and ultrastructural characteristics of the potentially pathogenic basidiomycetous yeast Malassezia pachydermatis
Authors: David Marek , Gabriel Miroslav , Kopecká Marie 
Published: September 2006

AbstractMicrotubular and actin cytoskeletons were investigated in the lipophilic yeast Malassezia pachydermatis by fluorescence and electron microscopy. To detect microtubules by indirect immunofluorescence using monoclonal anti‐tubulin antibody, a prolonged incubation with lysing enzymes was necessary due to its very thick cell wall. Cytoplasmic microtubules were detected in interphase and a spindle with astral microtubules was seen in M‐phase. The disintegration of cytoplasmic microtubules and migration of the nucleus to the bud before mitosis were characteristic features of the basidiomycetous yeast Malassezia pachydermatis. The visualisation of F‐actin structures (patches, cables and cytokinetic rings) by fluorescence microscopy using both monoclonal anti‐actin antibody and rhodamine‐phalloidin failed, but actin was detected by electron microscopy with immunogold labelling. Clusters of gold particles indicating actin structures were detected at the plasma membrane of cells with unique cortical ultrastructural features characteristic of the genus Malassezia. A possible association of these with the actin cytoskeleton is suggested.
Nitric oxide affects preimplantation embryonic development in a rotating wall vessel bioreactor simulating microgravity
Authors: Cao Yu‐jing , Fan Xun‐jun , Shen Zheng , Ma Bao‐hua , Duan En‐kui 
Published: September 2006

AbstractMicrogravity was simulated with a rotating wall vessel bioreactor (RWVB) in order to study its effect on pre‐implantation embryonic development in mice. Three experimental groups were used: stationary control, rotational control and clinostat rotation. Three experiments were performed as follows. The first experiment showed that compared with the other two (control) groups, embryonic development was significantly retarded after 72 h in the clinostat rotation group. The second experiment showed that more nitric oxide (NO) was produced in the culture medium in the clinostat rotation group after 72 h (P < 0.05), and the nitric oxide synthase (NOS) activity in this group was significantly higher than in the controls (P < 0.01). In the third experiment, we studied apoptosis in the pre‐implantation mouse embryos after 72 h in culture and found that Annexin‐V staining was negative in the normal (stationary and rotational control) embryos, but the developmentally retarded (clinostat rotation) embryos showed a strong green fluorescence. These results indicate that microgravity induced developmental retardation and cell apoptosis in the mouse embryos. We presume that these effects are related to the higher concentration of NO in the embryos under microgravity, which have cause cytotoxic consequences.
Connective tissue growth factor and fibronectin secretion in renal tubular epithelial cells induced by TGF‐β1: Suppressive effects of troglitazone
Authors: Wei Jia‐li , Peng You‐ming , Liu Fuyou 
Published: September 2006

AbstractAlthough some studies have suggested that troglitazone could retard the progression of glomerulosclerosis, its effects on renal tubulointerstitial fibrosis have not been completely clarified. The aim of this study was to investigate the effects of troglitazone on the secretion of connective tissue growth factor (CTGF) and fibronectin (FN) in human renal proximal tubular epithelial (HK‐2) cells induced by transforming growth factor‐β1 (TGF‐β1). The mRNA of CTGF and FN were measured by semi‐quantitative RT‐PCR. CTGF and FN protein were detected by Western blot and ELISA, respectively. Our results revealed that troglitazone could inhibit CTGF and FN expression in a dose‐dependent manner in human renal proximal tubular epithelial cells induced by TGF‐β1, which may be one of the mechanisms of troglitazone contributing to retard the progression of renal tubulointerstitial fibrosis.
Overexpression of cyclin D1 is associated with elevated levels of MAP kinases, Akt and Pak1 during diethylnitrosamine‐induced progressive liver carcinogenesis
Authors: Parekh Palak , Rao K.V.K. 
Published: September 2006

AbstractHepatocellular carcinoma (HCC) is a multi‐factorial and multi‐step process. However, the molecular mechanisms, which play a pivotal role during progressive development of HCC, are not known. Accordingly Sprague—Dawley rats were administered diethylnitrosamine (DEN) for one to three months in order to understand the molecular alterations during progressive development of liver tumor. In this study involvement of G1/S regulatory proteins, MAP kinases and cell survival factors were analyzed using RT‐PCR, western blotting and in vitro kinase assays. The data showed overexpression of cyclin D1 and increased expression and activation of ERK1/2, p38 kinase and JNK1/2 with progression of tumor suggesting that MAP kinases play an important role during tumorigenesis. These molecular alterations were supported by Akt upregulation and increase in the levels of inactive GSK3β with progression of liver tumor. Further, p21‐actived kinase1 (Pak1) was found to be upregulated with tumor progression, which is a novel observation during progressive liver carcinogenesis. These results indicate that elevated levels of all the three MAP kinases (ERK1/2, p38 and JNK1/2), Akt/GSK3β and Pak1 are associated with cyclin D1 upregulation, which helps in the disruption of the G1/S regulatory point of the cell cycle and leads to abnormal cell proliferation during progressive hepatocarcinogenesis.
Cellular effects and metabolic stability of N1‐cyclic inosine diphosphoribose and its derivatives
Authors: Kirchberger T , Wagner G , Xu J , Cordiglieri C , Wang P , Gasser A , Fliegert R , Bruhn S , Flügel A , Lund F E , Zhang L‐h , Potter B V L , Guse A H 
Published: September 2006

Background and purpose:Recently, a number of mimics of the second messenger cyclic ADP‐ribose (cADPR) with replacement of adenosine by inosine were introduced. In addition, various alterations in the molecule ranging from substitutions at C8 of the base up to full replacement of the ribose moieties still retained biological activity. However, nothing is known about the metabolic stability and cellular effects of these novel analogues.Experimental approach:cADPR and the inosine‐based analogues were incubated with CD38, ADP‐ribosyl cyclase and NAD‐glycohydrolase and metabolism was analysed by RP‐HPLC. Furthermore, the effect of the analogues on cytokine expression and proliferation was investigated in primary T‐lymphocytes and T‐lymphoma cells.Key results:Incubation of cADPR with CD38 resulted in degradation to adenosine diphosphoribose. ADP‐ribosyl cyclase weakly catabolised cADPR whereas NAD‐glycohydrolase showed no such activity. In contrast, N1‐cyclic inosine 5′‐diphosphoribose (N1‐cIDPR) was not hydrolyzed by CD38. Three additional N1‐cIDPR analogues showed a similar stability. Proliferation of Jurkat T‐lymphoma cells was inhibited by N1‐cIDPR, N1‐[(phosphoryl‐O‐ethoxy)‐methyl]‐N9‐[(phosphoryl‐O‐ethoxy)‐methyl]‐hypoxanthine‐cyclic pyrophosphate (N1‐cIDP‐DE) and N1‐ethoxymethyl‐cIDPR (N1‐cIDPRE). In contrast, in primary T cells neither proliferation nor cytokine expression was affected by these compounds.Conclusions and Implications:The metabolic stability of N1‐cIDPR and its analogues provides an advantage for the development of novel pharmaceutical compounds interfering with cADPR mediated Ca2+ signalling pathways. The differential effects of N1‐cIDPR and N1‐cIDPRE on proliferation and cytokine expression in primary T cells versus T‐lymphoma cells may constitute a starting point for novel anti‐tumor drugs.British Journal of Pharmacology (2006) 149, 337–344. doi:10.1038/sj.bjp.0706869