bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the nexus between obesity, metabolic syndrome, and colorectal cancer
Authors: Lee Jong Yoon
Published: March 2024

The increasing global prevalence of obesity and metabolic syndrome (MetS) is strongly associated with the incidence of colorectal cancer (CRC). Obesity and MetS detrimentally impact the treatment outcomes of CRC and share similar mechanisms that contribute to the development of CRC. Increased insulin resistance in patients with obesity is linked to CRC, and altered levels of sex hormones and adipokines affect cell growth and inflammation. Obesity and MetS also alter the gut microbiome. Bile acids, which are crucial for lipid metabolism, are elevated in patients with obesity. Moreover, specific bile acids are associated with colonic damage, inflammation, and the development of CRC. Obesity and MetS increase the risk of postoperative complications and affect the response to chemotherapy. The promotion of weight loss and the resolution of MetS can reduce the occurrence of CRC and increase treatment efficacy. Therefore, it is imperative to implement appropriate management strategies to address obesity and MetS with the aim of improving the prognosis and reducing the incidence of CRC. Moreover, additional research should be conducted to determine the optimal timing for tailored CRC screening in patients with obesity or MetS. In this review, we explore the impact of obesity and MetS on the development of CRC and examine potential strategies to mitigate CRC risk in individuals with obesity and MetS.
Depth distribution law of polarization characteristics of vector acoustic field in shallow sea (Retracted)
Authors: Wei Yi-Zheng , Sun Chao , Zhu Qi-Xuan ,   School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China,   Key Laboratory of Ocean Acoustic and Sensing, Ministry of Industry and Information Technology, Northwestern Polytechnical University, Xi’an 710072, China
Published: March 2024

The polarization of the acoustic field in the ocean waveguide environment is a unique property that can be measured by using a particle velocity sensor in the water column. It can provide new ideas for locating and detecting the underwater target, so it is interesting to study the polarization. The polarization of a monochromatic signal has been described by the Stokes parameters, a set of four real-valued quantities in previous work. In this work, the Stokes parameters are extended to the broadband form, and the expression is simplified by using the nonstationary phase approximation, which reduces the complexity of the theoretical derivation and reveals the physical mechanism behind the significant variations in polarization with source depth and symmetrical depth. Theoretical analysis shows that the polarization characteristics in the ideal waveguide vary significantly in the sea surface, the sea bottom, the depth of the sound source and symmetrical depth. In this work the numerical simulation is used to verify the theoretical analysis and study the relationship between range and integral bandwidth when nonstationary phase approximation method is effective. The numerical results demonstrate that the simplified expression using the nonstationary phase approximation is effective and can better characterize the depth distribution characteristics of the polarization. Additionally, by normalizing the broadband Stokes parameters, the effect of range on the depth distribution characteristics of polarization can be removed. It means that the normalized broadband Stokes parameters are in theory free of the range and depend on the environment, the receiver depth and the source depth, which have the potential to be used for source depth estimation. Subsequently, focusing on normalized broadband Stokes parameters, we analyzes the effects of parameters such as source frequency, source depth, sound speed profile and water depth on the depth distribution characteristics of polarization. The analysis results show that environmental factors have great influence on the depth distribution characteristics of polarization. In the end, the validity of the nonstationary phase approximation and the range-independent property of the normalized broadband Stokes parameters are verified by the results of the RHUM-RUM experimental data processing. The findings provide a theoretical basis for passive target depth estimation based on polarization.
Neural criticality from effective latent variables
Authors: Morrell Mia C , Nemenman Ilya , Sederberg Audrey
Published: March 2024

Observations of power laws in neural activity data have raised the intriguing notion that brains may operate in a critical state. One example of this critical state is ‘avalanche criticality’, which has been observed in various systems, including cultured neurons, zebrafish, rodent cortex, and human EEG. More recently, power laws were also observed in neural populations in the mouse under an activity coarse-graining procedure, and they were explained as a consequence of the neural activity being coupled to multiple latent dynamical variables. An intriguing possibility is that avalanche criticality emerges due to a similar mechanism. Here, we determine the conditions under which latent dynamical variables give rise to avalanche criticality. We find that populations coupled to multiple latent variables produce critical behavior across a broader parameter range than those coupled to a single, quasi-static latent variable, but in both cases, avalanche criticality is observed without fine-tuning of model parameters. We identify two regimes of avalanches, both critical but differing in the amount of information carried about the latent variable. Our results suggest that avalanche criticality arises in neural systems in which activity is effectively modeled as a population driven by a few dynamical variables and these variables can be inferred from the population activity.
Combinatorial expression of γ-protocadherins regulates synaptic connectivity in the mouse neocortex
Authors: Zhu Yi-jun , Deng Cai-yun , Fan Liu , Wang Ya-Qian , Zhou Hui , Xu Hua-tai
Published: March 2024

In the process of synaptic formation, neurons must not only adhere to specific principles when selecting synaptic partners but also possess mechanisms to avoid undesirable connections. Yet, the strategies employed to prevent unwarranted associations have remained largely unknown. In our study, we have identified the pivotal role of combinatorial clustered protocadherin gamma (γ-PCDH) expression in orchestrating synaptic connectivity in the mouse neocortex. Through 5' end single-cell sequencing, we unveiled the intricate combinatorial expression patterns of γ-PCDH variable isoforms within neocortical neurons. Furthermore, our whole-cell patch-clamp recordings demonstrated that as the similarity in this combinatorial pattern among neurons increased, their synaptic connectivity decreased. Our findings elucidate a sophisticated molecular mechanism governing the construction of neural networks in the mouse neocortex.
The catalytic mechanism of the RNA methyltransferase METTL3
Authors: Corbeski Ivan , Vargas-Rosales Pablo Andrés , Bedi Rajiv Kumar , Deng Jiahua , Coelho Dylan , Braud Emmanuelle , Iannazzo Laura , Li Yaozong , Huang Danzhi , Ethève-Quelquejeu Mélanie , Cui Qiang , Caflisch Amedeo
Published: March 2024

The complex of methyltransferase-like proteins 3 and 14 (METTL3-14) is the major enzyme that deposits N6-methyladenosine (m6A) modifications on messenger RNA (mRNA) in humans. METTL3-14 plays key roles in various biological processes through its methyltransferase (MTase) activity. However, little is known about its substrate recognition and methyl transfer mechanism from its cofactor and methyl donor S-adenosylmethionine (SAM). Here, we study the MTase mechanism of METTL3-14 by a combined experimental and multiscale simulation approach using bisubstrate analogues (BAs), conjugates of a SAM-like moiety connected to the N6-atom of adenosine. Molecular dynamics simulations based on crystal structures of METTL3-14 with BAs suggest that the Y406 side chain of METTL3 is involved in the recruitment of adenosine and release of m6A. A crystal structure with a BA representing the transition state of methyl transfer shows a direct involvement of the METTL3 side chains E481 and K513 in adenosine binding which is supported by mutational analysis. Quantum mechanics/molecular mechanics (QM/MM) free energy calculations indicate that methyl transfer occurs without prior deprotonation of adenosine-N6. Furthermore, the QM/MM calculations provide further support for the role of electrostatic contributions of E481 and K513 to catalysis. The multidisciplinary approach used here sheds light on the (co)substrate binding mechanism, catalytic step, and (co)product release, and suggests that the latter step is rate-limiting for METTL3. The atomistic information on the substrate binding and methyl transfer reaction of METTL3 can be useful for understanding the mechanisms of other RNA MTases and for the design of transition state analogues as their inhibitors.
Demystifying the ‘hidden curriculum’ for minoritized graduate students
Authors: Hopkins Michael J , Moore Brittni N , Jeffery Jasmin L , Young Andrea S
Published: March 2024

Graduate programs in the biomedical sciences dedicate considerable resources to recruiting students from underrepresented racial and ethnic groups. However, students from these minoritized groups have decreased access to the ‘hidden curriculum’ that must be navigated in order to be successful in graduate school. Here, we describe a student-led initiative at Johns Hopkins University, the Hidden Curriculum Symposium, that is organized to help prepare new students from underrepresented groups for graduate school. Preliminary evidence from surveys suggests that the initiative does increase the preparedness of minoritized students, and we believe this approach could also prove useful at other academic institutions.
Alteration of long and short-term hematopoietic stem cell ratio causes myeloid-biased hematopoiesis
Authors: Nishi Katsuyuki , Sakamaki Taro , Nagasaka Akiomi , Kao Kevin S. , Sadaoka Kay , Asano Masahide , Yamamoto Nobuyuki , Takaori-Kondo Akifumi , Miyanishi Masanori
Published: March 2024

Myeloid-biased hematopoiesis is a well-known age-related alteration. Several possibilities, including myeloid-biased hematopoietic stem cell (HSC) clones, may explain this. However, the precise mechanisms remain controversial.Utilizing the Hoxb5 reporter system to prospectively isolate long-term HSCs (LT-HSCs) and short-term HSCs (ST-HSCs), we found that young and aged LT-HSCs co-transplanted into the same recipients demonstrated nearly equivalent myeloid lineage output, contrary to the theory of myeloid-biased HSC clones. Transcriptomics indicated no significant myeloid gene enrichment in aged LT-HSCs compared to their young counterparts. Instead, transplanting reconstituted young HSCs with the ratio of LT/ST-HSCs seen in aged mice can significantly skew the lineage output to myeloid cells. In addition, while the niche environment in the bone marrow minimally affects myeloid-biased hematopoiesis, aged thymi and spleens substantially hinder lymphoid hematopoiesis, resulting in further myeloid-domination. Thus, we demonstrate that myeloid-biased hematopoiesis in aged organisms originates due to alteration of the ratio between LT-HSCs and ST-HSCs rather than in heterogeneous HSC clones with various cell fates.
Impact of the coronavirus disease 2019 pandemic on the diversity of notifiable infectious diseases: a case study in Shanghai, China
Authors: Zhang Yongfang , Feng Wenli
Published: March 2024

The outbreak of coronavirus disease 2019 (COVID-19) has not only posed significant challenges to public health but has also impacted every aspect of society and the environment. In this study, we propose an index of notifiable disease outbreaks (NDOI) to assess the impact of COVID-19 on other notifiable diseases in Shanghai, China. Additionally, we identify the critical factors influencing these diseases using multivariate statistical analysis. We collected monthly data on 34 notifiable infectious diseases (NIDs) and corresponding environmental and socioeconomic factors (17 indicators) from January 2017 to December 2020. The results revealed that the total number of cases and NDOI of all notifiable diseases decreased by 47.1% and 52.6%, respectively, compared to the period before the COVID-19 pandemic. Moreover, the COVID-19 pandemic has led to improved air quality as well as impacted the social economy and human life. Redundancy analysis (RDA) showed that population mobility, particulate matter (PM2.5), atmospheric pressure, and temperature were the primary factors influencing the spread of notifiable diseases. The NDOI is beneficial in establishing an early warning system for infectious disease epidemics at different scales. Furthermore, our findings also provide insight into the response mechanisms of notifiable diseases influenced by social and environmental factors.
Effectiveness of Cordia verbenacea and Propolis as Irrigation Solution on the Bond Strength of Filling Material to the Root Dentin: In vitro Study
Authors: Barroso Gabriel Kennedy , Soares Kaio Henrique , Silva Ângelo Fonseca , Fonseca-Silva Thiago , Santos Carolina Carvalho de Oliveira
Published: March 2024

Introduction: Endodontic treatment aims to eliminate pathological microbiota from root canals to prevent or treat infections in periapical tissues. Irrigation is a crucial step in this process, serving important mechanical, chemical, and biological functions.

Objective: This study aimed to evaluate the effect of irrigation with Cordia verbenacea and propolis solutions compared to chlorhexidine and sodium hypochlorite on the bond strength of the filling material to the root dentin.

Materials and Methods: This In vitro experimental study involved 40 healthy human premolars subjected to the push-out test. The teeth underwent decoronation, followed by biomechanical endodontic preparation using mechanized files. The teeth were then divided into four groups according to the irrigating solution: NaOCl 5.25%, chlorhexidine 2%, aqueous extract of Cordia verbenacea and aqueous extract of propolis. Data were statistically analyzed using analysis of variance and the Post-Hoc Bonferroni test.

Results: The group irrigated with propolis showed greater resistance to the push-out test in the middle and apical thirds when compared to the other groups (p<0.05). There were no statistically significant differences among the other groups.

Conclusion: Irrigation with propolis extract resulted in higher bond strength of the obturating material to the root canal, while irrigation with Cordia verbenacea showed similar results to chlorhexidine and sodium hypochlorite.
The performance analyses of multitarget CMA adaptive array considering mutual coupling and diffraction effects
Authors: Xu Jin , Zhu GuoQiang , Yuan Fei
Published: November 2006

The performance of a multitarget constant modulus algorithm (MU‐CMA) adaptive array located on a regular conducting plate is studied in this paper. The effects of mutual coupling (MC) between array elements and diffraction caused by the conducting plate are taken into account. A hybrid method of equivalent edge current method (ECM) and moment method (MM) is employed in electromagnetic calculation to investigate the distortion of initial array pattern. We compare the capture property of three well‐known MU‐CMA arrays, respectively: multitarget least‐squares constant modulus array (MT‐LSCMA), multitarget decision‐directed array (MT‐DD) and least‐squares despread respread multitarget constant modulus array (LS‐DRMTCMA). Simulation result shows that: (i) the distorted initial pattern leads to the descending of the signal catch performance of MT‐LSCMA and MT‐DD; (ii) only the LS‐DRMTCMA can work correctly due to its stronger anti‐jamming ability in the presence of MC and diffraction. Copyright © 2006 John Wiley & Sons, Ltd.
Critical Loads for Cd and Pb in the Province of Bologna
Authors: Morselli Luciano , Bernardi Elena , Passarini Fabrizio , Tesini Enrico
Published: November 2006

Atmospheric deposition represents a significant source of heavy metals entering soil and aquatic ecosystems. The evaluation of their vulnerability can be carried out by the Critical Load criterion. In this work we focus the attention on the terrestrial ecosystems in the Province of Bologna, estimating the maximum tolerable load of cadmium and lead they are able to bear without sustain the occurrence of harmful ecotoxicological effects. To this aim the Steady‐State Mass Balance method is applied on a small scale (10×10 Km EMEP grids) and the more suitable approach to define critical limits for the Province condition, effect‐base or stand‐still, is discussed. The opportunity of simplifying the input data collection is also considered, trying to deduce soil properties from geological information.

Finally, the environmental risk due to the present deposition of Pb and Cd on provincial soils is described as exceedances over the critical loads.
Titelbild: “Sulflower”: A New Form of Carbon Sulfide (Angew. Chem. 44/2006)
Authors: Chernichenko Konstantin Yu. , Sumerin Viktor V. , Shpanchenko Roman V. , Balenkova Elizabeth S. , Nenajdenko Valentine G.
Published: November 2006

Einer blühenden Sonnenblume gleicht die hoch symmetrische Struktur des planaren Octathio[8]circulens. In der Zuschrift auf S. 7527 ff. geben V. G. Nenajdenko und Mitarbeiter Einblick in die Synthese und Charakterisierung dieser Verbindung, die als ein neues Kohlenstoffsulfid oder als ein Oligothiophen betrachtet werden kann – sie ist anorganisch und organisch zugleich. (Hintergrundbild: “Sonnenblumen” von Vincent van Gogh. Copyright: Neue Pinakothek, München.)
Reactions in Droplets in Microfluidic Channels
Authors: Song Helen , Chen Delai L. , Ismagilov Rustem F.
Published: November 2006

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet‐based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet‐based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.
Chemiluminescence of synephrine based on the cerium(IV)–rhodamine B system
Authors: Wang Ruifen , Wan Lijuan , Li Qian , Liu Xidong , Huang Yuming
Published: November 2006

A new chemiluminescence (CL) method is described for the determination of synephrine. It is based on the reaction between synephrine and Ce(IV) in a nitric acid medium and measurement of the CL intensity produced by rhodamine B used as a luminophore, similar to luminol or lucigenin in basic media, instead of as a sensitizer. In the optimum conditions, the increase of CL intensity was correlated with synephrine concentration over the range 5.0 × 10−9–1.0 × 10−6 g/mL with a detection limit of 1.0 × 10−9 g/mL. The relative standard deviation (RSD) was 2.9% for 1.0 × 10−7 g/mL synephrine (n = 11). The method was applied to the determination of a drug in herbal products, citrus fruit and biological samples, with satisfactory results. The results given by the proposed method are in good agreement with those given by HPLC‐UV and UV spectrophotometry. Copyright © 2006 John Wiley & Sons, Ltd.
Development of imidazopyrazinone red‐chemiluminescent probes for detecting superoxide anions via a chemiluminescence resonance energy transfer method
Authors: Teranishi Katsunori
Published: November 2006

During the development of useful probes for detecting superoxide anions via chemiluminescence with longer wavelengths than that of green, chemiluminescent probes that emit red light (λmax 610 nm) when induced by superoxide anions were synthesized and characterized. These red‐chemiluminescent probes consist of a 6‐(4‐methoxyphenyl)imidazo[1,2‐a] pyrazin‐3(7H)‐one moiety, which reacts with superoxide anions to generate energy, and a sulphorhodamine 101 moiety, which accepts the energy and emits red light. Using a hypoxanthine–xanthine oxidase system for the generation of superoxide anions, it was shown that the superoxide anion‐induced chemiluminescences of red‐chemiluminescent probes (3 and 4) were more intense than those of the blue‐ and green‐chemiluminescent probes 2‐methyl‐6‐(4‐methoxyphenyl)imidazo[1,2‐a] pyrazin‐3(7H)‐one (MCLA) and 6‐[4‐[2‐[N′‐(5‐fluoresceinyl)thioureido]‐ethoxy]phenyl]‐2‐methylimidazo[1,2‐a]pyrazin‐3(7H)‐one (FCLA), respectively, which are generally considered to be the most sensitive chemiluminescent probes. The ratio between the superoxide‐dependent and background chemiluminescence intensities for 3 was comparable to those of MCLA and FCLA, but higher than that of 4. Due to its highly intense superoxide anion‐induced chemiluminescence at low probe concentrations, red‐chemiluminescent probe 3 is superior to MCLA and FCLA for measurement of superoxide anions. Copyright © 2006 John Wiley & Sons, Ltd.
Rapid formation of hydrogen‐producing granules in an anaerobic continuous stirred tank reactor induced by acid incubation
Authors: Zhang Zhen‐Peng , Show Kuan‐Yeow , Tay Joo‐Hwa , Liang David Tee , Lee Duu‐Jong , Jiang Wen‐Ju
Published: November 2006

A novel approach to rapidly initiate granulation of hydrogen‐producing sludge was developed in an anaerobic continuous stirred tank reactor at 37°C. To induce microbial granulation, the acclimated culture was subject to an acid incubation for 24 h by shifting the culture pH from 5.5 to 2.0. The culture was resumed to pH 5.5 after the incubation and the reactor was operated at hydraulic retention times (HRTs) of 12, 6, 2, 1, and 0.5 h in sequence. Microbial aggregation took place immediately with the initiation of acid incubation and granules were developed at 114 h. No granule was observed in the absence of acid incubation in the control test. Changing the culture pH resulted in improvement in surface physicochemical properties of the culture favoring microbial granulation. The zeta potential increased from −11.6 to −3.5 mV, hydrophobicity in terms of contact angle improved from 31° to 43° and extracellular proteins/polysaccharides ratio increased from 0.2 to 0.5–0.8. Formation of granular sludge facilitated biomass retention of up to 32.2 g‐VSS/L and enhanced hydrogen production. The hydrogen production rate and hydrogen yield increased with the reduction in HRT at an influent glucose concentration of 10 g/L once steady granular sludge layer was formed, achieving the respective peaks of 3.20 L/L · h and 1.81 mol‐H2/mol‐glucose at 0.5 h HRT. The experimental results suggested that acid incubation was able to initiate the rapid formation of hydrogen‐producing granules by regulating the surface characteristics of microbial aggregates in a well‐mixed reactor, which enhanced the hydrogen production. Biotechnol. Bioeng. 2007;96:1040–1050. © 2006 Wiley Periodicals, Inc.
An in silico model for HIF‐α regulation and hypoxia response in tumor cells
Authors: Yucel Meryem A. , Kurnaz Isil Aksan
Published: November 2006

The dependency of the growth and metastasis of tumors on the new blood vessel formation, or angiogenesis, has opened up new potentials to tumor therapy, nevertheless understanding the molecular mechanisms involved in angiogenesis is crucial in the bioengineering of novel anti‐angiogenic drugs. The key component in hypoxia sensing in tumor cells is the hypoxia‐inducible factor, HIF‐1α, which is inactivated through proteosome‐mediated degradation under normoxic conditions. Two enzymes have been reported to hydroxylate HIF‐1α, namely prolyl hydroxylase (PH), recruiting the proetasome complex and degrading cytoplasmic HIF‐1α, and asparaginyl hydroxylase/factor inhibiting HIF‐1α (FIH‐1), downregulating the recruitment of p300 to the promoter, thereby reducing the transcriptional activity of HIF‐1α. In this study, we have constructed an in silico model of a tumor cell using the GEPASI 3.30 biochemical simulation software (http://www.gepasi.org) and studied the performances of PH and FIH‐1 on HIF‐1α degradation and inactivation, respectively, as monitored by expression of the vascular endothelial growth factor, VEGF, during hypoxia. In our biochemical models, FIH‐1 can successfully increase hypoxic transcription of VEGF, however FIH‐1 on its own is not sufficient to inactivate HIF‐1 completely, leading to background VEGF transcription under normoxic conditions. On the other hand, PH is necessary to increase the hypoxic transcriptional response, and can effectively shut off normoxic transcription. We therefore propose that regulating PH activity can be a primary target for anti‐angiogenic bioengineering research. Biotechnol. Bioeng. 2007;97: 588–600. © 2006 Wiley Periodicals, Inc.
Characterization of Peptide–Pyrazole Interactions in Solution by Low‐Temperature NMR Studies
Authors: Wang Wei , Weisz Klaus
Published: November 2006

Complexation of the amino‐ and carboxyl‐protected tripeptide Piv‐L‐Val‐L‐Val‐L‐Val‐tBu with 3‐methylpyrazole and 3‐amino‐5‐methylpyrazole was studied by low‐temperature NMR experiments in a freonic solvent. The peptide forms an extended β‐type structure at all temperatures and associates through hydrogen bonding with the two pyrazole‐based β‐sheet ligands. A detailed structural characterization of the formed complexes by one‐ and two‐dimensional NMR experiments under slow exchange conditions was made possible by employing very low temperatures. The tripeptide associates to stable antiparallel dimers that are symmetrically capped on both sides by two pyrazole receptors to form 2:2 complexes. Amide groups of two neighboring residues in an extended conformation are involved in cyclic hydrogen bonds to the pyrazole. Based on amide chemical shift changes, the relative strength of intermolecular hydrogen bonds can be assessed and correlated with the electronic effects of the substituents on the pyrazole.
Reactions of Sn(NMe2)2 with MPHCy: The Effects of Alkali Metal Phosphide Coupling (Cy=Cyclohexyl; M=Li, Na, K, Rb)
Authors: Alvarez Paula , García Felipe , Hehn Jörg P. , Kraus Florian , Lawson Gavin T. , Korber Nikolaus , Mosquera Marta E. G. , McPartlin Mary , Moncrieff David , Pask Christopher M. , Woods Anthony D. , Wright Dominic S.
Published: November 2006

The reactions of the SnII base Sn(NMe2)2 with CyPHM (Cy=cyclohexyl) produce a range of products, depending primarily on the alkali metal (M) involved. The 1:3 stoichiometric reaction of Sn(NMe2)2 with CyPHNa in the presence of the Lewis base donor PMDETA (PMDETA=(Me2NCH2CH2)2NMe) gives [(Na⋅PMDETA)2{Sn(μ‐PCy)}3] (3), containing the electron‐deficient [{Sn(μ‐PCy)}3]2− dianion. Natural bond order (NBO) and electron localisation function (ELF) calculations show that this species is described most appropriately by a two‐electron, three‐centre Sn3 bonding model. Evidence that 3 results from phosphide coupling is provided by the 1:1 reaction of Sn(NMe2)2 with CyPHNa in the presence of PMDETA, which gives 3 and trace amounts of (Na⋅PMDETA)2[{Sn(μ‐PCy)}2(μ‐PCyPCy)] (4) (containing one PCyPCy2− dianion). Greater extents of phosphide coupling are observed as the size of the Group 1 metal is increased. Thus, the 1:3 reaction of Sn(NMe2)2 with CyPHK in THF gives the co‐crystalline product {(K⋅2 THF)2[{Sn(μ‐PCyPCy)}2(μ‐PCy)]}0.9{(K⋅2 THF)2[{Sn(μ‐PCy)}2(μ‐PCyPCy)]}0.1 (5) (containing [{Sn(μ‐PCyPCy)}2(μ‐PCy)]2− and [{Sn(μ‐PCy)}2(μ‐PCyPCy)]2− dianions), whereas the analogous reaction of Sn(NMe2)2 with RbPHCy gives [Rb⋅PMDETA{(CyP)3SnP(H)Cy}] (6) (containing a cyclic {(CyP)3Sn} unit).
The Effect of Counterion/Ligand Interplay on the Activity and Stereoselectivity of Palladium(II)–Diimine Catalysts for CO/p‐Methylstyrene Copolymerization
Authors: Binotti Barbara , Bellachioma Gianfranco , Cardaci Giuseppe , Carfagna Carla , Zuccaccia Cristiano , Macchioni Alceo
Published: November 2006

The catalytic activity and stereoselectivity of complexes [Pd(η1,η2‐C8H12OMe)(ArNC(R′)C(R′)NAr)]X in the copolymerization of CO and p‐methylstyrene have been correlated with their interionic structure in solution and in the solid state, as determined by 19F,1H‐HOESY NMR spectroscopy and X‐ray diffraction studies, respectively. The highest productivity is obtained with unhindered diimine ligands bearing electron‐donating substituents and with the least coordinating counterion. Copolymers with a microstructure ranging from atactic to predominantly isotactic are obtained. The degree of isotacticity increases as the steric hindrance in the apical positions and the coordinating ability of the counterion increase. The counterion is located close to the diimine in both solution and the solid state but it moves toward the palladium as the steric hindrance in the apical positions decreases. When the latter is small the counterion competes with the substrate for apical coordination, and consequently it affects the productivity. In the case of ortho‐dimethyl‐substituted ligands the counterion is confined in the back, above the NC(R′)C(R′)N moiety, and does not affect the productivity. However, it contributes to increasing the stereoregularity of the copolymer by making the aryl moieties more rigid. With R′=Me and Ar=o‐Me2C6H3 an ll of 81 % and 72 % was obtained with X−=CF3SO3− or BArF−, respectively. The isotacticity of the copolymers produced by ortho‐monosubstituted catalysts depends greatly on the counterion and ranges from 30 % to 59 % with X−=BArF− and X−=CF3SO3−, respectively, with Ar=o‐EtC6H4 and R′=Me. Based on the interionic structural results, this effect can be explained by a greater reduction of the copolymerization rate of Cs‐symmetric isomers with respect to their C2‐symmetric counterparts.
The stereoselective metabolism of halofantrine to desbutylhalofantrine in the rat: Evidence of tissue‐specific enantioselectivity in microsomal metabolism
Authors: Gharavi Negar , Sattari Somayeh , Shayeganpour Anooshirvan , El‐Kadi Ayman O.S. , Brocks Dion R.
Published: November 2006

The pharmacokinetics of the antimalarial drug (±)‐halofantrine are stereoselective in humans and rats. To better understand the stereoselective metabolism of the drug to its primary metabolite, desbutylhalofantrine (DHF), a series of in vitro and in vivo experiments were undertaken in the rat. Formation of (−)‐DHF exceeded that of (+)‐DHF in liver microsomes [(−):(+) ratio of intrinsic formation clearances = 1.4]. In contrast, in intestinal microsomes no significant stereoselectivity was noted in the formation of the DHF enantiomers. Intestinal microsomes were also less efficient at producing the DHF enantiomers than were liver microsomes. Based on kinetic analysis of the DHF formation, there appeared to be more than one enzyme involved in the biotransformation. (±)‐Ketoconazole (KTZ) effectively inhibited the formation of both DHF enantiomers by both liver and intestinal microsomes, although the reduction was more marked in liver microsomes. Through a combination of the use of CYP antibodies and recombinant CYP isoenzymes, the involvement of CYP 2B1/2, 3A1, 3A2, 1A1, 2C11, 2C6, 2D1, and 2D2 were implicated in the metabolism of halofantrine to DHF. Of these, CYP3A1/2 and CYP2C11 appeared to be the primary isoenzymes involved, although CYP2C11 showed greater (+)‐DHF than (−)‐DHF formation, whereas for CYP3A1 it was similar to the isolated rat liver microsomes. In vivo, oral (±)‐KTZ caused significant increases in plasma halofantrine and decreases in DHF enantiomer plasma concentrations. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Stereoselective determination of benalaxyl in plasma by chiral high‐performance liquid chromatography with diode array detector and application to pharmacokinetic study in rabbits
Authors: Qiu Jing , Wang Qiuxia , Zhu Wentao , Jia Guifang , Wang Xinquan , Zhou Zhiqiang
Published: November 2006

A chiral high‐performance liquid chromatography method with diode array detector was developed and validated for stereoselective determination of benalaxyl (BX) in rabbit plasma. Good separation was achieved at 20°C using cellulose tris‐(3,5‐dimethylphenylcarbamate) as chiral stationary phase, a mixture of n‐hexane and 2‐propanol (97:3) as mobile phase at a flow rate of 1.0 ml/min. The assay method was linear over a range of concentrations (0.25–25 μg/ml) in plasma and the mean recovery was greater than 90% for both enantiomers. The limits of quantification and detection for both enantiomers in plasma were 0.25 and 0.1 μg/ml, respectively. Intra‐ and interday relative standard deviations (RSDs) did not exceed 10% for three‐tested concentrations. The method was successfully applied to pharmacokinetic studies of BX enantiomers in rabbits. The result suggested that the pharmacokinetics of BX enantiomers was stereoselective in rabbits. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Enantioselective disposition of PCB 136 (2,2′,3,3′,6,6′‐hexachlorobiphenyl) in C57BL/6 mice after oral and intraperitoneal administration
Authors: Kania‐Korwel Izabela , Shaikh Nadim S. , Hornbuckle Keri C. , Robertson Larry W. , Lehmler Hans‐Joachim
Published: November 2006

Studies of xenobiotic disposition in rodents often employ experimental designs using differing routes of administration. In an effort to investigate the effects of route of administration on enantioselective disposition of xenobiotics, a chiral polychlorinated biphenyl (PCB), racemic PCB 136, was administered as a single dose (50 mg/kg body weight) to male or female C57BL/6 mice either orally or via intraperitoneal injection. Mice were sacrificed after either 3 or 6 days, and blood and organs were collected for PCB analysis. Intraperitoneal injection of PCB 136 produced statistically higher PCB levels in blood and organs than did the oral administration. Tissue levels were higher after 3 days than those after 6 days. Enantioselective analysis showed that (+)‐PCB 136 was enriched in most organs, with the most pronounced enrichment found in the liver and the brain of animals dosed orally or by intraperitoneal injection, respectively. Significantly higher retained enantiomeric fractions of PCB 136 were found in the oral treatment groups compared with those found in intraperitoneal treatment groups, possibly as a result of the lower PCB levels in oral treatment groups. Therefore, the choice of administration route may well have implications for the enantioselective disposition of PCB 136 and other chiral substances. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Fountain Flow™ cytometry, a new technique for the rapid detection and enumeration of microorganisms in aqueous samples
Authors: Johnson Paul E. , Deromedi Anthony J. , Lebaron Philippe , Catala Philippe , Cash Jennifer
Published: November 2006

Background:

Pathogenic microorganisms are known to cause widespread waterborne disease worldwide. There is an urgent need to develop a technique for the real‐time detection of pathogens in environmental samples at low concentrations, <10 microorganisms/ml, in large sample volumes, ≥100 ml.

Methods:

A novel method, Fountain Flow™ cytometry, for the rapid and sensitive detection of individual microorganisms in aqueous samples is presented. Each sample is first incubated with a fluorescent label and then passed as a stream in front of a laser, which excites the label. The fluorescence is detected with a CCD imager as the sample flows toward the imager along its optical axis. The feasibility of Fountain Flow cytometry (FFC) is demonstrated by the detection of Escherichia coli labeled with ChemChrome CV6 and SYBR Gold in buffer and natural river water.

Results:

Detections of labeled E. coli were made in aqueous suspensions with an efficiency of 96% ± 14% down to a concentration ∼200 bacteria/ml.

Conclusions:

The feasibility of FFC is demonstrated by the detection of E. coli in buffer and natural river water. FFC should apply to the detection of a wide range of pathogenic microorganisms including amoebae. © 2006 International Society for Analytical Cytology
Mouse Rab11‐FIP4 regulates proliferation and differentiation of retinal progenitors in a Rab11‐independent manner
Authors: Muto Akihiko , Aoki Yutaka , Watanabe Sumiko
Published: November 2006

We identified Rab11‐family interacting protein 4 (Rab11‐FIP4) as a gene strongly expressed in the developing mouse retina. The major transcript encoding a full‐length protein, mRab11‐FIP4A, was expressed predominantly in neural tissues; whereas an alternative transcript encoding an N‐terminally truncated form of the protein, mRab11‐FIP4B, was expressed ubiquitously as a minor form. Gain‐of‐function of mRab11‐FIP4A in retina promoted cell cycle exit and increased subpopulations of retinal cells localized in the inner nuclear layer, such as bipolar cells and Müller glia. Reversal of the phenotype was observed in the loss‐of‐function experiment. Furthermore, Shh signaling was suggested to be involved in these functions. Analysis using truncation mutants revealed the essential role of the N‐terminal region containing a conserved EF‐hand motif for the retinal phenotypes induced by the expression of mRab11‐FIP4A, whereas binding to Rab11 was dispensable, suggesting the involvement of a novel Rab11‐independent mechanism for mRab11‐FIP4A action in the regulation of retinal development. Developmental Dynamics 236:214–225, 2007. © 2006 Wiley‐Liss, Inc.
Timing and sequence of the onset of overweight, dieting, and binge eating in overweight patients with binge eating disorder
Authors: Reas Deborah L. , Grilo Carlos M.
Published: November 2006

Objective:

To examine the self‐reported sequence and timing of onset of overweight, binge eating, and dieting in adult patients diagnosed with binge eating disorder (BED).

Method:

Participants were 284 treatment‐seeking adults (73 men and 211 women) who met DSM‐IV research criteria for BED. Patients were interviewed with structured diagnostic interviews and were queried regarding history of overweight, dieting, and binge eating behaviors. Questionnaires were also administered to assess current eating disturbances, body dissatisfaction, and general functioning. Participants were classified as Overweight First, Binge First, or Diet First, and the three groups were compared on developmental sequence and using the battery of measures.

Results:

Sixty‐three percent of the 284 participants reported becoming overweight prior to the onset of dieting or binge eating. Participants who reported they were overweight first had significantly greater BMI at the time of assessment. The 16% of the participants who reported binge eating first were significantly younger at the onset of BED diagnosis and reported significantly less dietary restraint. Onset order differed significantly by gender; proportionally more women (25%) than men (11%) reported that dieting preceded overweight or binge eating.

Conclusion:

Weight problems preceded dieting and binge eating behaviors for a majority of treatment‐seeking overweight participants diagnosed with BED. © 2006 by Wiley Periodicals, Inc. Int J Eat Disord 2006
Ligand Effects on the Chemical Activity of Copper(I) Complexes: Outer‐ and Inner‐Sphere Oxidation of CuIL
Authors: Burg Ariela , Maimon Eric , Cohen Haim , Meyerstein Dan
Published: November 2006

The effect of the ligands acetonitrile (AN), fumaric acid (H2fum) and 2,5,8,11‐tetramethyl‐2,5,8,11‐tetraazadodecane (L1) on the kinetics of oxidation of CuI complexes by [(cyclam)NiIII(SO4)2]– and [(NH3)5CoIIICl]2+ in aqueous solutions via an outer‐ and inner‐sphere mechanism, respectively, has been studied. The effects of the ligands on the electron self‐exchange rate constants have also been evaluated. All ligands studied stabilize CuI in aqueous solution but affect the redox potential of the CuII/IL couple differently. The ligands decrease the rate of the redox reactions and the electron self‐exchange rate constants. The results indicate that acetonitrile and alkenes should not be used as solvents for [CuIL]+‐catalyzed processes that involve redox steps. On the other hand, the results also suggest that [CuIL1]+ should be a good catalyst for such processes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Series of Lithium Rare Earth Polyphosphates [LiLn(PO3)4] (Ln = La, Eu, Gd) and Their Structural, Optical, and Electronic Properties
Authors: Zhu Jing , Cheng Wen‐Dan , Wu Dong‐Sheng , Zhang Hao , Gong Ya‐Jing , Tong Hua‐Nan , Zhao Dan
Published: November 2006

The structural, optical, and electronic properties of a series of lithium rare earth polyphosphates [LiLn(PO3)4] [Ln = La (1), Eu (2), Gd (3)] have been investigated by means of single‐crystal X‐ray diffraction, elemental analyses, and spectroscopic measurements, as well as calculations of energy‐band structures, density of states, and optical response functions by density functional methods. These LiLn(PO3)4 systems are monoclinic with space group C2/c and Z = 4. Their unit‐cell parameters decrease as the ionic radius of Ln3+ decreases (La3+ > Eu3+ > Gd3+). Both (PO4)3– zig‐zag chains and infinite chains formed by the alternate connection of LnO8 polyhedra and LiO4 tetrahedra run parallel to the b‐axis in the structure. The energy‐band structures, density of states, the chemical bonds, and optical properties have been investigated by density functional methods for some of the title compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
How to Reach Stereogenic Trifluoromethylated Carbon? En Route to the “Grail” of the Asymmetric Trifluoromethylation Reaction
Authors: Billard Thierry , Langlois Bernard R.
Published: November 2006

The importance of trifluoromethylated molecules has undergone regular growth during the last years, and asymmetric molecules with the CF3 group borne by a chiral carbon have become more popular. However, methods used to achieve such molecules are still limited. The building block strategy has been the method most employed these last years and stereocontrolled trifluoromethylation reactions have begun to emerge as potential valuable alternatives. Trifluoromethylation of chiral molecules, by using diastereoselective induction, seems promising and already gives good results in certain cases. However, although actively studied to this day, the enantioselective trifluoromethylation of prochiral compounds is still not very efficient even if some interesting results have been already described. Nevertheless, such reactions still present a challenge in terms of efficiency. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Direct Composition Analysis of a Dynamic Library of Imines in an Aqueous Medium
Authors: Zameo Sandrine , Vauzeilles Boris , Beau Jean‐Marie
Published: November 2006

Dynamic Combinatorial Chemistry: Direct detection of imines in water and their adaptive re‐equilibration in the presence of a target are possible by simple HPLC analysis. The equilibrating mixture is fixed by a fast drop in the pH during the analytical step. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Influences of perceived autonomy support on physical activity within the theory of planned behavior
Authors: Chatzisarantis Nikos L. D. , Hagger Martin S. , Smith Brett
Published: November 2006

Three studies tested the contribution of perceived autonomy support to the prediction of health‐related intentions within the theory of planned behavior. Perceived autonomy support refers to the extent to which individuals perceive that significant others encourage choice and participation in decision‐making, provide a meaningful rationale, minimize pressure, and acknowledge the individual's feelings and perspectives. Findings from Studies 1 and 2 demonstrated that perceived autonomy support predicted intentions to participate in physical activity behavior directly and indirectly via attitudes. Perceived autonomy support predicted intention even after statistically controlling for the effects from past behavior, descriptive norms, and perceived social support. Study 3 found that persuasive communications influenced perceptions of autonomy support, attitudes, and intentions. Overall, the findings support the incorporation of perceived autonomy support into the theory of planned behavior. Copyright © 2006 John Wiley & Sons, Ltd.
Self‐esteem moderates preferences for accepting versus rejecting interaction partners
Authors: Rudich Eric A. , Sedikides Constantine , Gregg Aiden P.
Published: November 2006

Two experiments compared the social orientations of people with high and low self‐esteem (HSEs vs. LSEs). In Experiment 1, participants received positive or negative interpersonal feedback from an accepting or rejecting evaluator. HSEs chose to interact with a rejecting evaluator more often than LSEs did. In Experiment 2, participants received solely negative interpersonal feedback from an accepting or rejecting evaluator of high or low social status. This time, both HSEs and LSEs chose an accepting/high‐status evaluator over a rejecting/low‐status one, but only HSEs chose a rejecting/high‐status evaluator over an accepting/low‐status one. Implications are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Cone calorimeter analysis of UL‐94 V‐rated plastics
Authors: Morgan Alexander B. , Bundy Matthew
Published: November 2006

Cone calorimeter analysis was conducted on 18 thermoplastics with different UL‐94 vertical burn test (V) ratings. Ratings varied from V‐0 to no rating (NR), and the types of thermoplastics included were polycarbonate (PC), acrylonitrile–butadiene–styrene (ABS), PC/ABS blends, high‐impact polystyrene (HIPS), polypropylene (PP), and poly(vinyl chloride) (PVC). Our analysis of the cone calorimeter data found that there were correlations between UL‐94 V rating and some cone calorimeter measurements (peak heat release rate (HRR) average and HRR at 60 s) and no relationship for other measurements (time to ignition and total heat release). However, no precise correlation was found due to significant differences in flame retardant mechanism and polymer fuel energy values. In this paper, we seek to explain further why a broad quantitative relationship between UL‐94 V and cone calorimeter remains elusive, and also to show how the cone calorimeter can be used to understand why a material passes or fails a particular UL‐94 V rating. Copyright © 2006 John Wiley & Sons, Ltd.
Eye position‐dependent activity in the primary visual area as revealed by fMRI
Authors: Andersson Frédéric , Joliot Marc , Perchey Guy , Petit Laurent
Published: November 2006

Internal senses of the position of the eye in the orbit may influence the cognitive processes that take into account gaze and limb positioning for movement or guiding actions. Neuroimaging studies have revealed eye position‐dependent activity in the extrastriate visual, parietal, and frontal areas, but, at the earliest vision stage, the role of the primary visual area (V1) in these processes remains unclear. Functional MRI (fMRI) was used to investigate the effect of eye position on V1 activity evoked by a quarter‐field stimulation using a visual checkerboard. We showed that the amplitude of V1 activity was modulated by the position of the eye, the activity being maximal when both the eye and head positions were aligned. Previous studies gave impetus to the emerging view that V1 activity is a cortical area in which contextual influences take place. The present study suggests that eye position may affect an early stage of visual processing. Hum Brain Mapp, 2006. © 2006 Wiley‐Liss, Inc.