bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maximal exercise test is a useful method for physical capacity and oxygen consumption determination in streptozotocin-diabetic rats
Authors: Rodrigues Bruno , Figueroa Diego M , Mostarda Cristiano T , Heeren Marcelo V , Irigoyen Maria-Cláudia , De Angelis Kátia 
Published: December 2007

Abstract

Background
The aim of the present study was to investigate the relationship between speed during maximum exercise test (ET) and oxygen consumption (VO2) in control and STZ-diabetic rats, in order to provide a useful method to determine exercise capacity and prescription in researches involving STZ-diabetic rats.

Methods
Male Wistar rats were divided into two groups: control (CG, n = 10) and diabetic (DG, n = 8). The animals were submitted to ET on treadmill with simultaneous gas analysis through open respirometry system. ET and VO2 were assessed 60 days after diabetes induction (STZ, 50 mg/Kg).

Results
VO2 maximum was reduced in STZ-diabetic rats (72.5 ± 1 mL/Kg/min-1) compared to CG rats (81.1 ± 1 mL/Kg/min-1). There were positive correlations between ET speed and VO2 (r = 0.87 for CG and r = 0.8 for DG), as well as between ET speed and VO2 reserve (r = 0.77 for CG and r = 0.7 for DG). Positive correlations were also obtained between measured VO2 and VO2 predicted values (r = 0.81 for CG and r = 0.75 for DG) by linear regression equations to CG (VO2 = 1.54 * ET speed + 52.34) and DG (VO2 = 1.16 * ET speed + 51.99). Moreover, we observed that 60% of ET speed corresponded to 72 and 75% of VO2 reserve for CG and DG, respectively. The maximum ET speed was also correlated with VO2 maximum for both groups (CG: r = 0.7 and DG: r = 0.7).

Conclusion
These results suggest that: a) VO2 and VO2 reserve can be estimated using linear regression equations obtained from correlations with ET speed for each studied group; b) exercise training can be prescribed based on ET in control and diabetic-STZ rats; c) physical capacity can be determined by ET. Therefore, ET, which involves a relatively simple methodology and low cost, can be used as an indicator of cardio-respiratory capacity in future studies that investigate the physiological effect of acute or chronic exercise in control and STZ-diabetic male rats.
Asn 362 in gp120 contributes to enhanced fusogenicity by CCR5-restricted HIV-1 envelope glycoprotein variants from patients with AIDS
Authors: Sterjovski Jasminka , Churchill Melissa J , Ellett Anne , Gray Lachlan R , Roche Michael J , Dunfee Rebecca L , Purcell Damian FJ , Saksena Nitin , Wang Bin , Sonza Secondo , Wesselingh Steven L , Karlsson Ingrid , Fenyo Eva-Maria , Gabuzda Dana , Cunningham Anthony L , Gorry Paul R 
Published: December 2007

Abstract

Background
CCR5-restricted (R5) human immunodeficiency virus type 1 (HIV-1) variants cause CD4+ T-cell loss in the majority of individuals who progress to AIDS, but mechanisms underlying the pathogenicity of R5 strains are poorly understood. To better understand envelope glycoprotein (Env) determinants contributing to pathogenicity of R5 viruses, we characterized 37 full-length R5 Envs from cross-sectional and longitudinal R5 viruses isolated from blood of patients with asymptomatic infection or AIDS, referred to as pre-AIDS (PA) and AIDS (A) R5 Envs, respectively.

Results
Compared to PA-R5 Envs, A-R5 Envs had enhanced fusogenicity in quantitative cell-cell fusion assays, and reduced sensitivity to inhibition by the fusion inhibitor T-20. Sequence analysis identified the presence of Asn 362 (N362), a potential N-linked glycosylation site immediately N-terminal to CD4-binding site (CD4bs) residues in the C3 region of gp120, more frequently in A-R5 Envs than PA-R5 Envs. N362 was associated with enhanced fusogenicity, faster entry kinetics, and increased sensitivity of Env-pseudotyped reporter viruses to neutralization by the CD4bs-directed Env mAb IgG1b12. Mutagenesis studies showed N362 contributes to enhanced fusogenicity of most A-R5 Envs. Molecular models indicate N362 is located adjacent to the CD4 binding loop of gp120, and suggest N362 may enhance fusogenicity by promoting greater exposure of the CD4bs and/or stabilizing the CD4-bound Env structure.

Conclusion
Enhanced fusogenicity is a phenotype of the A-R5 Envs studied, which was associated with the presence of N362, enhanced HIV-1 entry kinetics and increased CD4bs exposure in gp120. N362 contributes to fusogenicity of R5 Envs in a strain dependent manner. Our studies suggest enhanced fusogenicity of A-R5 Envs may contribute to CD4+ T-cell loss in subjects who progress to AIDS whilst harbouring R5 HIV-1 variants. N362 may contribute to this effect in some individuals.
HTLV-1 HBZ cooperates with JunD to enhance transcription of the human telomerase reverse transcriptase gene (hTERT)
Authors: Kuhlmann Anne-Sophie , Villaudy Julien , Gazzolo Louis , Castellazzi Marc , Mesnard Jean-Michel , Duc Dodon Madeleine 
Published: December 2007

Abstract

Background
Activation of telomerase is a critical and late event in tumor progression. Thus, in patients with adult-T cell leukaemia (ATL), an HTLV-1 (Human T cell Leukaemia virus type 1)-associated disease, leukemic cells display a high telomerase activity, mainly through transcriptional up-regulation of the human telomerase catalytic subunit (hTERT). The HBZ (HTLV-1 bZIP) protein coded by the minus strand of HTLV-1 genome and expressed in ATL cells has been shown to increase the transcriptional activity of JunD, an AP-1 protein. The presence of several AP-1 binding sites in the hTERT promoter led us to investigate whether HBZ regulates hTERT gene transcription.

Results
Here, we demonstrate using co-transfection assays that HBZ in association with JunD activates the hTERT promoter. Interestingly, the -378/+1 proximal region, which does not contain any AP-1 site was found to be responsible for this activation. Furthermore, an increase of hTERT transcripts was observed in cells co-expressing HBZ and JunD. Chromatin immunoprecipitation (ChIP) assays revealed that HBZ, and JunD coexist in the same DNA-protein complex at the proximal region of hTERT promoter. Finally, we provide evidence that HBZ/JunD heterodimers interact with Sp1 transcription factors and that activation of hTERT transcription by these heterodimers is mediated through GC-rich binding sites for Sp1 present in the proximal sequences of the hTERT promoter.

Conclusion
These observations establish for the first time that HBZ by intervening in the re-activation of telomerase, may contribute to the development and maintenance of the leukemic process.
The effects of neighborhood density and street connectivity on walking behavior: the Twin Cities walking study
Authors: Oakes J Michael , Forsyth Ann , Schmitz Kathryn H 
Published: December 2007

AbstractA growing body of health and policy research suggests residential neighborhood density and street connectivity affect walking and total physical activity, both of which are important risk factors for obesity and related chronic diseases. The authors report results from their methodologically novel Twin Cities Walking Study; a multilevel study which examined the relationship between built environments, walking behavior and total physical activity. In order to maximize neighborhood-level variation while maintaining the exchangeability of resident-subjects, investigators sampled 716 adult persons nested in 36 randomly selected neighborhoods across four strata defined on density and street-connectivity – a matched sampling design. Outcome measures include two types of self-reported walking (from surveys and diaries) and so-called objective 7-day accelerometry measures. While crude differences are evident across all outcomes, adjusted effects show increased odds of travel walking in higher-density areas and increased odds of leisure walking in low-connectivity areas, but neither density nor street connectivity are meaningfully related to overall mean miles walked per day or increased total physical activity. Contrary to prior research, the authors conclude that the effects of density and block size on total walking and physical activity are modest to non-existent, if not contrapositive to hypotheses. Divergent findings are attributed to this study's sampling design, which tends to mitigate residual confounding by socioeconomic status.
Apoptosis is not the major death mechanism induced by celecoxib on rheumatoid arthritis synovial fibroblasts
Authors: Audo Rachel , Deschamps Véronique , Hahne Michael , Combe Bernard , Morel Jacques 
Published: December 2007

AbstractSynovial hyperplasia in rheumatoid arthritis (RA) has been associated with apoptosis deficiency of RA fibroblast-like synoviocytes (FLSs). Celecoxib is a non-steroidal anti-inflammatory drug that has been demonstrated to induce apoptosis in some cellular systems. We have therefore examined the dose- and time-dependent effects of celecoxib on RA FLS viability. Treatment of RA FLSs with celecoxib for 24 hours reduced their viability in a dose-dependent manner. Analysis of celecoxib-treated RA FLSs for their content of apoptotic and necrotic cells by Annexin V staining and TO-PRO-3 uptake displayed only few apoptotic cells. Caspase 3, a key mediator of apoptosis, was not activated in celecoxib-treated RA FLSs, and the presence of specific caspase 3 or pan-caspase inhibitors did not affect celecoxib-induced cell death. Moreover, we could not detect other signs of apoptosis, such as cleavage of poly(ADP-ribose) polymerase, caspase 8 or 9, or DNA fragmentation. We therefore conclude that apoptosis is not the major death pathway in celecoxib-treated RA FLSs.
Anticlusterin treatment of breast cancer cells increases the sensitivities of chemotherapy and tamoxifen and counteracts the inhibitory action of dexamethasone on chemotherapy-induced cytotoxicity
Authors: Redondo Maximino , Téllez Teresa , Roldan Maria J , Serrano Alfonso , García-Aranda Maria , Gleave Martin E , Hortas Maria L , Morell Miguel 
Published: December 2007

Abstract
Introduction
Overexpression of the apoptosis-related protein clusterin is associated with breast cancer development and tumor progression. We describe the use of clusterin-specific antisense oligonucleotides and antibodies to sensitize breast carcinoma cells to anticancer drugs routinely used in breast cancer therapy.

Methods
MCF-7 and MDA-MB-231 cells were treated with the oligonucleotide or antibody, chemotherapeutic agents (doxorubicin or paclitaxel), tamoxifen, or with combinations of these.

Results
Treatments that include antisense clusterin oligonucleotide or antibody to clusterin have been shown to reduce the number of viable cells more effectively than treatment with the drugs alone. We also demonstrate that dexamethasone pretreatment of breast cancer cell lines inhibits chemotherapy-induced cytotoxicity and is associated with the transcriptional induction of clusterin. However, anticlusterin treatment increases chemotherapy-induced cytotoxicity, even in the presence of glucocorticoids, suggesting a possible role for these proteins in glucocorticoid-mediated survival.

Conclusion
These data suggest that combined treatment with antibodies to clusterin or antisense clusterin oligodeoxynucleotides and paclitaxel, doxorubicin, or tamoxifen could be a novel and attractive strategy to inhibit the progression of breast carcinoma by regulation of the clusterin function. Moreover, glucocorticoid activation in breast cancer cells regulates survival signaling by the direct transactivation of genes like clusterin which encode proteins that decrease susceptibility to apoptosis. Given the widespread clinical administration of dexamethasone before chemotherapy, understanding glucocorticoid-induced survival mechanisms is essential for achieving optimal therapeutic responses.
Vasopressin in septic shock: effects on pancreatic, renal, and hepatic blood flow
Authors: Krejci Vladimir , Hiltebrand Luzius B , Jakob Stephan M , Takala Jukka , Sigurdsson Gisli H 
Published: December 2007

Abstract
Introduction
Vasopressin has been shown to increase blood pressure in catecholamine-resistant septic shock. The aim of this study was to measure the effects of low-dose vasopressin on regional (hepato-splanchnic and renal) and microcirculatory (liver, pancreas, and kidney) blood flow in septic shock.

Methods
Thirty-two pigs were anesthetized, mechanically ventilated, and randomly assigned to one of four groups (n = 8 in each). Group S (sepsis) and group SV (sepsis/vasopressin) were exposed to fecal peritonitis. Group C and group V were non-septic controls. After 240 minutes, both septic groups were resuscitated with intravenous fluids. After 300 minutes, groups V and SV received intravenous vasopressin 0.06 IU/kg per hour. Regional blood flow was measured in the hepatic and renal arteries, the portal vein, and the celiac trunk by means of ultrasonic transit time flowmetry. Microcirculatory blood flow was measured in the liver, kidney, and pancreas by means of laser Doppler flowmetry.

Results
In septic shock, vasopressin markedly decreased blood flow in the portal vein, by 58% after 1 hour and by 45% after 3 hours (p < 0.01), whereas flow remained virtually unchanged in the hepatic artery and increased in the celiac trunk. Microcirculatory blood flow decreased in the pancreas by 45% (p < 0.01) and in the kidney by 16% (p < 0.01) but remained unchanged in the liver.

Conclusion
Vasopressin caused marked redistribution of splanchnic regional and microcirculatory blood flow, including a significant decrease in portal, pancreatic, and renal blood flows, whereas hepatic artery flow remained virtually unchanged. This study also showed that increased urine output does not necessarily reflect increased renal blood flow.
An experimental investigation on optimized manifold injection in a direct-injection diesel engine with various hydrogen flowrates
Authors: Saravanan N , Nagarajan G 
Published: December 2007

In recent days, the importance of environment and energy have been emphasized and, among various energy sources, the fuels for automotive use are attracting attention as they are closely related to day-to-day life. The fossil fuels that are widely used have some serious problems. One of these problems is the limit in reserves, the second problem is that they cannot be recycled, and another problem is that they produce many exhaust emissions. Therefore, various research studies on alternative fuels have been carried out to find a substitute for fossil fuels. Hydrogen, a non-carbon fuel, can meet zero-emission vehicles standards in the future and can be commercially used as a fuel, even though it has a number of technical and economical barriers. For this paper, experiments were conducted to determine the optimized injection timing, injection duration, and injection quantity of the fuel for a manifold injected hydrogen-operated engine using diesel fuel as an ignition source for hydrogen. In the manifold injection technique, the optimized condition is the start of injection at gas exchange top dead centre (TDC) with an injection duration of 30° crank angle (CA) with a hydrogen flowrate of 7.5 l/min. The brake thermal efficiency is found to increase by 9 per cent compared with diesel fuel. Smoke is found to be lower for all hydrogen flowrates at all the load conditions owing to the absence of carbon in hydrogen. CO emissions vary from 0.03 to 0.12 vol% compared with from 0.08 to 0.14 vol% in a diesel fuel investigation. The exhaust gas temperature is found to be slightly higher by 7 per cent for the hydrogen operation compared with diesel fuel. Manifold injection systems with diesel fuel as the ignition source operate smoothly, show improved performance, and emit less pollution than diesel fuel does. It is possible to operate the direct-injection diesel engine smoothly using hydrogen in dual-fuel mode for the entire load spectrum.
Theoretical Studies of Chemical Reactions—A Fascinating World of Chemistry from Gas-Phase Elementary Reactions through Nanostructure Formation and Homogeneous Catalysis to Reactions of Metalloenzymes
Authors: Morokuma Keiji 
Published: December 2007

Abstract
Theoretical/computational studies of chemical reactions provide insight into detailed pathways and energy profiles that are not easily available from experiments. Although finding the potential energy profile for ground-state reactions of small molecular systems has become routine, there are many challenges in theoretical studies of chemical reactions. There are still a lot to learn from gas-phase reactions of small molecular systems, starting from an excited state and cascading though many potential surfaces via conical intersections. Molecular dynamics using quantum mechanical energy (QM/MD) was found to be an ideal tool for study of reactions occurring far from equilibrium, such as formation of fullerenes from small carbon fragments and growth of carbon nanotubes. Challenges in theoretical studies of homogeneous catalysis are subtle ligand effects, involvement of multiple spin states and cooperative effects of multiple metal centers. Discussions here cover stories on activation of molecular nitrogen by zirconium complexes, olefin epoxidation by Salen complexes and reactions of tri-ruthenium complexes. Metalloenzymatic reactions have been discussed using protein models with ONIOM QM:MM approaches as well as active site models. Cases are presented where the enzymatic environment makes rather small effects, where it makes energetically significant effects and where it participates positively into the reaction coordinate.
Studies of Organic Protein Cofactors Using Electron Paramagnetic Resonance
Authors: Weber Stefan , Bittl Robert 
Published: December 2007

Abstract
The elucidation of structural and electronic aspects of paramagnetic organic cofactors in their protein surroundings and related model compounds is a topic of widespread interest. In this field, electron paramagnetic resonance (EPR) spectroscopy, especially in conjunction with high-resolution electron-nuclear double resonance (ENDOR) is an important tool, allowing us to analyze details of the distribution of the unpaired electron spin, which is influenced by the interaction between the cofactor and its immediate environment, as well as to characterize paramagnetic intermediate states in the course of the protein action. In this account, investigations are reported in which EPR/ENDOR methods have contributed significantly to answering questions on mechanistic and structural aspects of protein function. Emphasis is given to in-depth characterizations of electronic and spatial structures of radical cofactors and their positioning relative to substrate molecules. After a brief introduction, covering some of the trends of modern EPR/ENDOR method development, we will focus, as examples, on characterizations of quinone-type and flavin cofactors in two proteins, (i) quinoprotein alcohol dehydrogenase, and (ii) DNA photolyase.
Formation, Structure, and Stability of α- and β-Cyclodextrin Inclusion Complexes of Phenol and Benzoic Acid Derivatives in Vacuo and in Water
Authors: Song Le Xin , Wang Hai Ming , Xu Peng , Zhang Zi Qiang , Liu Qing Qing 
Published: December 2007

Abstract
Inclusion complexations of α- and β-cyclodextrin (CD) with a series of phenol and benzoic acid derivatives both in vacuo and in water were investigated by semiempirical PM3 method. The inclusion systems with a higher negative value of complexation energy or interaction energy were found to have also a larger value of formation constant (Kf) in aqueous solution. The stability of β-CD inclusion complexes depended on the size/shape-fit between host and guest. A good size fitting between the volume of a guest molecule and the free space size of CD cavity effectively improved the stability of CD inclusion complex of the guest. Even though there was no appropriate molar volume ratio (MVR) of a guest to β-CD cavity, a good structural matching between the shape of a guest molecule and the arrangement of β-CD cavity should also obviously improve the stability of β-CD inclusion complex of the guest. Moreover, the CD cavity size exerted a big influence on the stability of these supramolecular complexes. There was an energetic advantage of larger than 45 kJ mol−1 in favor of the intermolecular complexations between α-CD and mono-ortho-substituted phenol derivatives relative to phenol or mono-para-substituted phenol derivatives.
DFT Analysis of Cubane-Type FeIr3S4 Clusters. Dinitrogen Binding and Activation at the Tetrahedral Fe Site
Authors: Kozlowski Pawel M , Shiota Yoshihito , Gomita Satomi , Seino Hidetake , Mizobe Yasushi , Yoshizawa Kazunari 
Published: December 2007

Abstract
The electronic and structural properties of the cubane-type mixed-metal sulfido clusters with a FeIr3S4 core and possible dinitrogen binding and activation were analyzed by density functional theory (DFT) calculations. Five different charges of the cluster and manifold of the electronic states were investigated. For each charge under consideration (+2,+1,0,−1,−2) systematic analysis of structural and electronic properties was carried out. The DFT calculations show that both Fe–N and N≡N bond lengths correlate with the total charge of the cluster. The length of the Fe–N bond decreased, whereas the N≡N bond length increased with the number of added electrons. However, only noticeable elongation of the N≡N bond was observed when the charge of the cluster became negative. Similar analysis was extended to species that have protonated dinitrogen bond. The results obtained from the DFT analysis are useful in considering the principles of the reduction of dinitrogen to ammonia at a single metal center.
Ferromagnetic Interactions in Non-Kekulé Polymers
Authors: Hatanaka Masashi , Shiba Ryuichi 
Published: December 2007

Abstract
Ferromagnetic interactions in non-Kekulé polymers were analyzed under the periodic boundary condition. We transformed Bloch functions of non-bonding crystal orbitals (NBCOs) into Wannier functions. The product of the ν-th and (ν+1)-th Wannier functions was defined as PNBCOν,ν+1 (product of NBCOs). In so-called nondisjoint-type polymers, ferromagnetic ground states resulted from instabilities of anti-parallel-spin states in PNBCOν,ν+1. The instabilities consisted of “on-site term” and “through-space term.” The former corresponded to squared amplitude of the same atomic site on PNBCOν,ν+1, and the latter corresponded to antibonding-through-space interactions in PNBCOν,ν+1. The instabilities led to ferromagnetic-spin alignment. On the other hand, in so called disjoint polymers, such instabilities did not emerge.
Synergistic Extraction and Solution Structures of Ternary Complexes of Lanthanoids with 2-Thenoyltrifluoroacetone and Linear Poly(oxyethylene) in 1,2-Dichloroethane
Authors: Gagabe Gene Frederick , Satoh Yuta , Satoh Keiichi , Sawada Kiyoshi 
Published: December 2007

Abstract
Synergistic extraction of thenoyltrifluoroacetone (tta) complexes of 14 trivalent lanthanoids (Ln3+) into 1,2-dichloroethane with linear poly(oxyethylene) compounds (POE) was investigated at 25.0 °C, where the linear POE [HO–(CH2CH2O–)nR] are monodispersed DEOn (R=C12H25; n=4, 6, and 8) and polydispersed TX-100 (R = octylphenyl; nave=9.6). Equilibrium studies showed a 1:1 adduct complex with POE compound, Ln(tta)3·(POE), formed in the organic phase. The adduct formation constant, βadd, increased as the ionic radius of lanthanoid increased for any kind of POE. The very high stability of the 18-crown-6 adducts is explained by the incorporation of Ln3+ ion into the cavity of the crown ether. Adduct formation constants of the POE having short ethylene oxide (EO) chain, such as DEO4 and 12-crown-4, were fairly small; thus, it was estimated that those coordinate to the metal ion as a bidentate or tridentate ligand. Relatively large values of βadd of long chain POE (n≥6) indicate the indirect outer-sphere interaction of the uncoordinated residual EO units with the metal ion. Adduct formation with linear POEs significantly reduced the difference in extraction constants among the lanthanoid ions. Therefore, this synergistic extraction system is advantageous for the separation of lanthanoid ions as a group from other metal ions.