bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioselective Hydrogenation of Alkenes with Iridium–PHOX Catalysts: A Kinetic Study of Anion Effects
Authors: Smidt Sebastian P. , Zimmermann Nicole , Studer Martin , Pfaltz Andreas 
Published: August 2004

AbstractIn the asymmetric hydrogenation of unfunctionalized olefins with cationic iridium–PHOX catalysts, the reaction kinetics and, as a consequence, catalyst activity and productivity depend heavily on the counterion. A strong decrease in the reaction rate is observed in the series [Al{OC(CF3)3}4]−>BArF−>[B(C6F5)4]−>PF6−≫BF4−>CF3SO3−. With the first two anions, high rates, turnover frequencies (TOF>5000 h−1 at 4 °C), and turnover numbers (TONs) of 2000–5000 are routinely achieved. The hexafluorophosphate salt reacts with lower rates, although they are still respectable; however, this salt suffers from deactivation during the reaction and extreme water‐sensitivity, especially at low catalyst loading. Triflate and tetrafluoroborate almost completely inhibit the catalyst. In contrast to the hexafluorophosphate salt, catalysts with [Al{OC(CF3)3}4]−, BArF−, and [B(C6F5)4]− as counterions do not lose activity during the reaction and remain active, even after all the substrate has been consumed. In addition they are much less sensitive to moisture and, in general, rigorous exclusion of water and oxygen is not necessary. A first‐order rate dependence on the hydrogen pressure was determined for the BArF− and the PF6− salts. At low catalyst loading, the rate dependence on catalyst concentration was also first order. The rate dependence on the alkene concentration was strikingly different for the two salts. While the reaction rate observed for the BArF− salt slightly decreased with increasing alkene concentration (rate order −0.2), a rate order of ≈1 was determined for the corresponding hexafluorophosphate at low alkene concentrations.
CCL25/CCR9 promotes the induction and function of CD103 on intestinal intraepithelial lymphocytes
Authors: Ericsson Anna , Svensson Marcus , Arya Anu , Agace William W. 
Published: August 2004

AbstractThe integrin CD103 and the chemokine receptor CCR9 are co‐expressed on small intestinal CD8+ intraepithelial lymphocytes (IEL), naïve murine CD8+ T cells and by a small population of effector/memory CD8+ T cells, indicating a potential role for CCR9 in regulating CD103 expression and function. Here, we demonstrate that CD103, in contrast to CCR9, is down‐regulated on CD8+ T cells following their activation in mesenteric lymph nodes and that effector CD8+ T cells upon initial entry into the small intestinal epithelium are CCR9+CD103–. CD103 was rapidly induced on wild‐type CD8+ T cells subsequent to their entry into the small intestinal epithelium, however, CCR9–/– CD8+ T cells exhibited a significant delay in CD103 induction at this site. In addition, the CCR9 ligand, CCL25, that is constitutively expressed in the small intestinal epithelium, induced transient, dose‐dependent and pertussis toxin‐sensitive CD103‐mediated adhesion of CD8+ small intestinal IEL to a murine E‐cadherin human Fc (mEFc) fusion protein. Together, these results demonstrate a role for CCR9/CCL25 in promoting the induction and function of CD103 on CD8+ IEL and suggest that this chemokine receptor/chemokine pair may function to regulate lymphocyte‐epithelial interactions in the small intestinal mucosa.
Type V collagen regulates the expression of apoptotic and stress response genes by breast cancer cells
Authors: Luparello Claudio , Sirchia Rosalia 
Published: August 2004

AbstractType V collagen is a “minor” component of normal human breast stroma, which is subjected to over‐deposition in cases of ductal infiltrating carcinoma (DIC). We reported that, if used as a culture substrate for the DIC cell line 8701‐BC, it exhibited poorly‐adhesive properties and restrained the proliferative and motile behavior of the cell subpopulation able to attach onto it. Moreover, this collagen species was able to trigger DNA fragmentation and impair survival of 8701‐BC cells. In this study, we have extended our investigation with the aim to obtain further evidence that the death induced by type V collagen was of the apoptotic type by (i) microscopic detection and quantitation of Apoptag‐labeled cells, (ii) analysis of the expression levels of selected genes coding for apoptosis‐linked factors, caspases, and stress‐response proteins by conventional and semi‐quantitative multiplex PCR, and (iii) evaluation of the extent of caspase activation by chromogenic assay. We report here that type V collagen is able to determine an increase in the percentage of Apoptag‐positive cells, to up‐regulate Bcl‐xS, Bad, Dap kinase, hsf‐1, mthsp75, caspase‐1, ‐5, ‐8, ‐9, and ‐14, whilst down‐regulating Bcl‐2, Bcl‐xβ, and hsp60. Treatment of cell lysates with chromogenic tetrapeptide substrates specific for caspase‐1, ‐5, ‐8, and ‐9 demonstrated a marked increase of enzymatic activity in the presence of type V collagen. Our data validate 8701‐BC cell line as a suitable “in vitro” model for further and more detailed studies on the molecular mechanisms of the death response induced by type V collagen on primary DIC cells. © 2004 Wiley‐Liss, Inc.
Methylation‐regulated expression of cancer testis antigens in primary effusion lymphoma: Immunotherapeutic implications
Authors: Calabrò Luana , Fonsatti Ester , Altomonte Maresa , Pezzani Laura , Colizzi Francesca , Nanni Paola , Gattei Valter , Sigalotti Luca , Maio Michele 
Published: August 2004

AbstractPrimary effusion lymphoma (PEL) is a large B‐cell neoplasm with an unfavorable prognosis and limited therapeutic options. In this study, cancer testis antigens (CTA) were investigated as potential immunotherapeutic targets in patients with PEL. Baseline expression of a panel of 11 CTA was highly heterogeneous among five PEL cell lines. In particular, the investigated CTA were not expressed in BC‐2 and BC‐3 cells, while BC‐1, HBL‐6, and BCBL‐1 cells tested positive for 6, 8, and 9 CTA, respectively. The DNA hypomethylating agent 5‐aza‐2′‐deoxycytdine (5‐AZA‐CdR) invariably induced or up‐regulated the expression of all investigated CTA in all cell lines analyzed. The de novo expression of CTA was still detectable at mRNA and protein level at least 2 months after the end of 5‐AZA‐CdR treatment. These findings, and the concomitant up‐regulation of HLA‐class I antigens and ICAM‐1 by 5‐AZA‐CdR, support its clinical use to set‐up innovative chemo‐immunotherapeutic approaches in PEL. © 2004 Wiley‐Liss, Inc.
Cysteine‐protease involved in male chromatin remodeling after fertilization co‐localizes with α‐tubulin at mitosis
Authors: Concha Carolina , Morin Violeta , Bustos Paula , Genevière Anne Marie , Heck Margarete M.S. , Puchi Marcia , Imschenetzky Maria 
Published: August 2004

AbstractWe postulated an essential role for a cysteine‐protease in sea urchins sperm histones degradation which follows fertilization. We now report the purification of this enzyme, the determination of its N‐terminal amino acid sequence and the localization of the protein with antibodies generated against this amino‐terminal peptide. The immunofluorescence data confirmed the presence of this enzyme in the nucleus of unfertilized eggs. After fertilization labeling is observed both in female and male pronuclei suggesting a rapid recruitment of the enzyme to the male pronuclei. Interestingly, we have found that this cysteine‐protease persists in the nucleus of the zygotes during S phase of the cell cycle and co‐localizes with α‐tubulin that organizes the mitotic spindle during the initial embryonic cell division. © 2004 Wiley‐Liss, Inc.
Systematic studies of structure and physiological activity of alapyridaine. A novel food‐born taste enhancer
Authors: Soldo Tomislav , Frank Oliver , Ottinger Harald , Hofmann Thomas 
Published: August 2004

AbstractBy application of taste dilution analysis (+)‐(S)‐1‐(1‐carboxyethyl)‐5‐hydroxy‐2‐(hydroxymethyl)‐pyridinium inner salt was recently successfully identified as a multimodal taste enhancer in beef bouillon. While being taste‐less on its own, this so‐called alapyridaine was found to intensify the human perception of sweet, salty, and umami taste. To gain information on the molecular requirements of this novel class of taste enhancer, a range of structurally related pyridinium betaines were synthesized, purified, and their physiological activities sensorially evaluated. Removal or modification of the hydroxyl and the hydroxymethyl group, respectively, induced a loss in bioactivity, thus indicating the 2‐(hydroxymethyl)‐5‐hydroxypyridinium moiety as an essential structural element for taste enhancement. Regarding the amino substituent, neither the prolongation or removal of the alkyl chain or the carboxy function in the 1‐(1‐carboxy‐2‐ethyl)‐moiety, nor the incorporation of an additional carboxy function led to any active derivative, thus demonstrating that also the structure of the nitrogen substituent is rather conserved for taste enhancement. But substitution of the methyl group by a benzyl group yielded a compound showing similar taste enhancing activities as found for alapyridaine. Interestingly, additional insertion of glycine between the 1‐(1‐carboxy‐2‐phenylethyl)‐moiety and the pyridinium ring resulted in a compound eliciting comparable taste enhancing effects as shown for the compound lacking the glycine spacer. In contrast to these multimodal taste enhancers, substitution of the alanine moiety in alapyridaine by an arginine moiety revealed an one‐dimensional taste enhancer exclusively increasing the human sensitivity for salty taste.
Antioxidant activity of plant extracts on the inhibition of citral off‐odor formation
Authors: Liang Chia‐Pei , Wang Mingfu , Simon James E. , Ho Chi‐Tang 
Published: August 2004

AbstractGrape seed, pomegranate seed, green tea, and black tea extracts were used to inhibit the off‐odor from citral degradation. A 0.1 M citrate buffer (pH 3), containing 100 ppm citral and 200 ppm gallic acid equivalent plant extract, was incubated at 40°C. The reaction mixtures were analyzed by high‐performance liquid chromatography (HPLC) at days 0, 6, 10, 13, and 16 to monitor degradation of citral and formation of α, p‐dimethylstyrene, p‐cymene‐8‐ol, and p‐methylacetophenone. The addition of plant phenolic extracts could not inhibit citral degradation, however, all four plant extracts significantly inhibited p‐methylacetophenone formation. The samples, with the addition of plant extracts, exhibited higher concentrations of α, p‐dimethylstyrene and p‐cymene‐8‐ol than the control. This is presumed to be due to the oxygen‐scavenging effect of plant extracts blocking the pathway from p‐cymene‐8‐ol to p‐methylacetophenone. Our results suggest that these plant extracts act as general antioxidants inhibiting the generation of p‐methylacetophenone regardless of the types of water‐soluble phenolic compounds existing in the plant extracts.
Coupled‐cluster studies of HOONO+: Additional conformers of the 2A″ON+OOH complex and a comparison of restricted and unrestricted open‐shell Hartree–Fock coupled‐cluster results
Authors: Watts John D. , Francisco Joseph S. 
Published: August 2004

AbstractCoupled‐cluster calculations using the CCSD(T) method (coupled‐cluster singles and doubles with perturbative inclusion of triple excitations) and correlation‐consistent basis sets have been used to address aspects of the lowest 2A′ and 2A″ potential energy surfaces of the peroxynitrous acid cation (HOONO+). First, searches were made for conformers of the 2A″ ON+OOH complex in addition to the cis–trans species previously located by the authors (J Chem Phys 2003, 118, 1721). Two conformers were located—namely, trans–cis and trans–trans species—and these were confirmed to be local minima. The trans–trans conformer was calculated to be less than 0.5 kcal mol−1 higher in energy than the cis–trans conformer, and the trans–cis conformer was calculated to be about 6.4 kcal mol−1 higher in energy than the cis–trans conformer. Second, comparisons were made between CCSD(T) results obtained with unrestricted Hartree–Fock (UHF) and restricted open‐shell Hartree–Fock (ROHF) reference determinants. These comparisons were made on the 2A″ complexes and the planar 2A′ HOONO+ stationary points. In general, the energy differences between UHF‐CCSD(T) and ROHF‐CCSD(T) were very small, and well within the error bars of the methods. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
MIMO ARIMA models for handoff resource reservation in multimedia wireless networks
Authors: Rožić Nikola , Kandus Gorazd 
Published: August 2004

AbstractThis paper presents a new approach to prediction of resource demand for future handoff calls in multimedia wireless IP networks. Our approach is based on application of multi‐input‐multi‐output (MIMO) multiplicative autoregressive‐integrated‐moving average (ARIMA) (p,d,q)x(P,D,Q)S models fitted to the traffic data measured in the considered cell itself and on the new call admission control (CAC) algorithm that simultaneously maximizes the system throughput while keeping the handoff call dropping probability (CDP) below the targeted value. The main advantages of the proposed approach are the following: first, the proposed multi‐variable prediction method gives on average better predictions (i.e. narrower prediction confidence interval) for realistic traffic situations, which results in lower new call blocking probability (CBP) at the targeted handoff CDP and second, the model is simple to implement since it does not require communication among the adjacent cells. Simulation results show the superiority of the proposed MIMO prediction approach combined with the proposed call admission control algorithm for some typical nonstationary situations in comparison with univariate models. Copyright © 2004 John Wiley & Sons, Ltd.
Dynamic resource scheduling (DRS): a multimedia QoS framework for W‐CDMA
Authors: Gürbüz Özgür , Owen Henry 
Published: August 2004

AbstractMulti‐media support is an important feature of third generation (3G) wireless communication systems, and Quality of Service (QoS) is a crucial issue, as in any other networking environment. In this paper, the QoS issues in the wireless last‐mile is investigated for 3G systems based on Wideband‐Code division multiple access (W‐CDMA). Supporting multiple rates in the CDMA environment introduces the power assignment problem, which is coupled with the bandwidth and error QoS parameters. Also, multi‐media traffic flows should be classified and serviced in such a way to provision delay guarantees. In this paper, a new framework, namely dynamic resource scheduling (DRS), is described and extensively studied. In order to serve multi‐media services with different requirements, a family of nine algorithms has been developed within the DRS framework. These algorithms can be categorized with respect to single or prioritized queuing architectures, fixed or variable rate bandwidth and power allocation, and variable spreading gain or multi‐code spreading strategies. The paper presents the performance of the DRS algorithms in comparison with each other and with conventional scheduled‐CDMA (S‐CDMA) and proposed schemes in the W‐CDMA standard. The performance for error and throughput QoS provisioning and power control dynamics are explored; advantages, disadvantages and limitations of the algorithms are discussed. The DRS framework is concluded to be a promising QoS architecture, with a simple, flexible, scalable structure that can be configured according to a given traffic scenario. Copyright © 2004 John Wiley & Sons, Ltd.
Prions of yeast fail to elicit a transcriptional response
Authors: Ross Eric D. , Wickner Reed B. 
Published: August 2004

AbstractAmyloid deposits are associated with numerous human diseases. The [URE3] prion of Saccharomyces is an infectious, inactive, amyloid form of the Ure2p protein. Despite the presence of large prion aggregates in [URE3] yeast, the only apparent phenotypes associated with the prion are attributable to loss of Ure2p function. We used cDNA microarrays to look for genes in yeast that are differentially expressed in the presence of the [URE3] prion and which might act to mitigate the detrimental effects of the prion aggregates. On comparing [URE3] vs. ure2 yeast, we were surprised to find that the only expression changes detected were attributable to the low level of residual Ure2p activity in the [URE3] cells. Interestingly, in addition to repressing the activity of genes required for utilization of poor nitrogen sources when yeast are grown in the presence of a good nitrogen source, Ure2p appears to be involved in stimulating some of these same genes in the absence of a good nitrogen source. Copyright © 2004 John Wiley & Sons, Ltd.
Cardiologic and neurologic findings in left ventricular hypertrabeculation/non‐compaction related to wall thickness, size and systolic function
Authors: Stöllberger Claudia , Finsterer Josef 
Published: August 2004

AbstractLeft ventricular hypertrabeculation/noncompaction (LVHT) is a rare cardiac abnormality, diagnosed echocardiographically when >3 left ventricular trabeculations are visible in one image plane apically to the papillary muscles and intertrabecular spaces are perfused from the ventricular cavity. In the majority of the cases, LVHT is associated with neuromuscular disorders (NMD). LVHT occurs in dilated as well as in normally sized ventricles, with or without systolic dysfunction and wall thickening. Aim of the study was to assess whether cardiologic and neurologic findings differ between patients according to echocardiographically determined left ventricular size, systolic function and wall thickness. In 77 patients (19 f, mean age 52 years) LVHT was diagnosed. LVHT was assessed as ‘dilative’ (enddiastolic diameter ≥60 mm and fractional shortening ≤25%) in 43 cases, in 18 patients as ‘hypertrophic’ (interventricular septum and posterior wall ≥12 mm and fractional shortening ≥26%) and in the remaining 16 patients as ‘normally‐dimensioned’. Dilative LVHT patients were older than hypertrophic or normally‐dimensioned LHVT patients. The prevalence of NMD was 63% in dilative LVHT, 67% in hypertrophic LVHT and 56% in normally‐dimensioned LVHT. LHVT is more frequently found in dilated than hypertrophic ventricles. NMD are equally frequent in dilative, hypertrophic and normally‐dimensioned LVHT. Cardiac abnormalities may progress with age.
Selective versus nonselective β‐adrenergic receptor blockade in chronic heart failure: differential effects on myocardial energy substrate utilization
Authors: Al‐Hesayen Abdul , Azevedo Eduardo R. , Floras John S. , Hollingshead Shauna , Lopaschuk Gary D. , Parker John D. 
Published: August 2004

Background:Non‐selective and selective β‐blockers have been shown to improve outcomes in chronic heart failure (CHF). Recent data suggests the non‐selective β‐blockers have a more favourable effect on outcomes than β1‐selective agents. We sought to examine the differential effects of non‐selective versus selective β‐blockade on myocardial substrate utilization in patients with CHF.Methods and results:Twenty‐two patients with CHF were randomised to the non‐selective β‐blocker carvedilol or the selective β‐blocker metoprolol (double‐blind). Measurement of hemodynamics, arterial and coronary sinus free fatty acid (FFA) and lactate levels, and cardiac norepinephrine spillover (CANESP) were made before and after 4 months of therapy. In the carvedilol group (n=11), there was a significant reduction in myocardial FFA uptake (0.12±0.02 to 0.1±0.02 mmol/l, P<0.03). By contrast, in the metoprolol group (n=11) there was no change in myocardial FFA extraction. Carvedilol therapy tended to increase myocardial lactate extraction (0.24±0.05 to 0.35±0.08 mmol/l, P=0.08) while metoprolol therapy resulted in a trend in the opposite direction (0.18±0.03 to 0.11±0.04 mmol/l, P=0.09). The change in lactate extraction in the carvedilol group was significantly different from that in the metoprolol group (+0.11±0.06 vs. −0.09±0.04 mmol/l, P<0.01). Carvedilol treatment caused a significant reduction in CANESP while metoprolol had a neutral effect (−95±27 vs. 25±42 pmol/min, carvedilol vs. metoprolol P<0.03).Conclusion:Carvedilol treatment caused a 20% reduction in myocardial free fatty acid extraction while metoprolol had a neutral effect. These differences are most probably related to the differential effects of these two agents on efferent cardiac sympathetic activity and may be relevant to the reported differential effects of these drugs on clinical outcomes.
Plasma brain natriuretic peptide levels in patients with rheumatic heart disease
Authors: Gölbaþý Zehra , Uçar Özgül , Yüksel Ayşe Geçer , Gülel Okan , Aydoğdu Sinan , Ulusoy Vasfi 
Published: August 2004

AbstractBackground:Brain natriuretic peptide (BNP) is a cardiac hormone secreted from the ventricular myocardium as a response to ventricular volume expansion and pressure overload. Rheumatic heart disease (RHD) is still an important cause of heart failure in developing countries.Aims:To measure BNP levels in patients with RHD and to determine whether BNP concentrations correlate with clinical and echocardiographic findings.Methods:Eighty‐eight patients with rheumatic valve disease and 24 age‐ and sex‐matched healthy subjects were entered in the study. BNP was measured using the Triage B‐Type Natriuretic Peptide test (Biosite Diagnostics, San Diego, CA). Transthoracic echocardiography was performed in all patients to assess the severity of the valve disease and for the measurement of pulmonary artery pressure.Results:The plasma concentrations of BNP were significantly higher in patients with rheumatic heart disease than in control subjects (232±294 vs. 14±12 pg/ml, p<0.0001). The plasma BNP level was significantly higher in NYHA class III+IV than in class II (463±399 vs. 192±243 pg/ml, p<0.0001) and in NYHA class II than in class I (192±243 vs. 112±135 pg/ml, p<0.001). The independent determinants of higher BNP levels were NYHA functional class and systolic pulmonary artery pressure in multivariate analysis.Conclusion:We found increased plasma BNP levels in patients with rheumatic heart disease compared with healthy subjects.
COMT (Val158Met) polymorphism is not associated to neuropathic pain in a Spanish population
Authors: Armero Pilar , Muriel Clemente , Santos Juan , Sànchez‐Montero F.J. , Rodróguez Raquel E. , González‐Sarmiento Rogelio 
Published: August 2004

AbstractIt is well known that the response to painful stimuli varies between individuals and this could be consequence of individual differences to pain sensitivity that may be related to genetic factors. Catechol‐O‐methyltransferase (COMT) is one of the enzymes that metabolize catecholamine neurotransmitters. Differences in the activity of COMT influence the functions of these neurotransmitters. A single nucleotide polymorphism (Val158Met) of COMT leads to a three to four fold reduction in the activity of the enzyme and has been associated to modifications in the response to a pain stressor. Neuropathic pain is a progressive nervous system disease due to an alteration of the peripheral or central nervous system. To elucidate the possible role of COMT polymorphism in the susceptibility to neuropathic pain, we have performed a case‐control study in a Spanish population. Analysis of the (Val158Met) COMT polymorphism was performed by PCR amplification and DNA digestion with restriction enzymes. Our study concludes that functional Val158Met polymorphism of COMT gene is not associated to increased susceptibility to neuropathic pain.