bluuebunny/crossref_metadata_2025_split huggingface dataset:
2,3‐Bis(diarylphosphanyl)‐1,4‐diazadienes: P,P Coordination of PdII, PtII and a Nickelacyclopentanone with Subsequent Formation of Quinoxalines by a Ring‐Closure Reaction at the Periphery
Authors: Walther Dirk , Liesicke Stefan , Fischer Reinald , Görls Helmar , Weston Jennie , Batista Ariadna 
Published: December 2003

AbstractThe solid‐state structures of several 2,3‐bis(phosphanyl)‐1,4‐diazadiene ligands of the general formula RN=C(PPh2)−C(PPh2)=NR (B: R = 4‐tolyl; C: R = 4‐tert‐butylphenyl; D: R = mesityl) were determined by single‐crystal X‐ray diffraction. The ligands B and C are nonplanar and lie between the (E) and the (Z) form (N=C−C=N is 99.5° in B, 94.0° in C, and 128.2° in D). In the presence of air, B is oxidized to its corresponding phosphane oxide. Reaction of D with elemental sulfur yields the corresponding phosphane sulfide. Furthermore, ligand C reacts with [PtCl2(cod)] and [PdCl2(CH3CN)2] to form mononuclear complexes (1 and 2, respectively) in which the two P atoms are bound to the metal center. X‐ray structural analysis showed that in both complexes the 1,4‐diazadiene functionality at the periphery had undergone a ring‐closure reaction with one of the aromatic N‐substituents thus resulting in a quinoxaline ring. The bulkier ligand D reacts with [PdCl2(CH3CN)2] to form the mononuclear complex 3. In the solid state, the two phosphorus atoms are coordinated to the metal center in a five‐membered chelate ring. In contrast to 1 or 2, a cyclohexadiene system is formed as result of a cycloaddition reaction of one aromatic N‐substituent with the 1,4‐diazadiene system. The nickel complex [Ni(tmeda)(C2H4COO)] reacts with D by displacement of tmeda to form a mononuclear complex 4a with P,P coordination. A subsequent ring‐closure reaction (cycloaddition) at the periphery does not occur in 4a. If the ligand is sterically less demanding (B or C), a cycloaddition between the 1,4‐diazadiene system and one aromatic substituent takes place in the nickel complex to form complexes of the type 5 containing a quinoxaline ring. This reaction could be monitored by 31P NMR spectroscopy for ligand C. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Radical Cation and Dication Derived from 4,8‐Diethylbenzo[1,2‐d:4,5‐d′]bis[1,2,3]trithiole [DEBBT]: Change of Electronic State from Singlet‐State Dication DEBBT(2+)‐S to Triplet‐State Dimer 2DEBBT(2+)‐T in D2SO4 and CD3CN Solutions
Authors: Kimura Takeshi , Sasaki Takashi , Yamaki Hiroaki , Suzuki Eiichi , Niizuma Sigeya 
Published: December 2003

Abstract4,8‐Diethylbenzo[1,2‐d:4,5‐d′]bis[1,2,3]trithiole [DEBBT] was oxidized using concentrated D2SO4, leading to the generation of the radical cation DEBBT(·+) which was verified by ESR spectroscopy. DEBBT(·+) in the solution was further oxidized to produce the dication DEBBT(2+), as determined by 1H and 13C NMR spectroscopy. DEBBT(2+) was also prepared by treating DEBBT 1‐oxide [DEBBT 1‐O] with concentrated D2SO4, and was verified by 1H and 13C NMR spectroscopy. The 13C NMR chemical shifts of DEBBT(2+), calculated by the density functional theoretical (DFT) method at the B3LYP6‐31G** level, correlated well with those obtained experimentally. The ESR signal of DEBBT(2+) generated from DEBBT 1‐O was observed in solution, which implies that the singlet‐state dication DEBBT(2+)‐S isomerizes to the triplet‐state dication DEBBT(2+)‐T, and that two molecules of DEBBT(2+)‐T further form a spin pair at one trithiole ring with significant distance between the two radical centers. The oxidation of DEBBT with one or two equivalents of single‐electron oxidizing reagents produced DEBBT(·+) and DEBBT(2+), and the salts were isolated in a stable form. However, the DEBBT(2+) that was prepared by oxidation with NOPF6 proved silent for NMR in CD3CN, while ESR was active. The stability, electronic state, and NMR and ESR spectroscopy of the dication are affected by solvation with D2SO4 and CD3CN. The optimized structures and the total energy of the singlet‐ and triplet‐state dication were calculated using the DFT method at the B3LYP6‐31G** level, which shows that the structures of the singlet‐ and triplet‐state dications have a completely planar form with 1.7 kcal/mol as the total energy difference between them. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Characterization of Novel Substituted 3,6‐Di(2‐pyridyl)pyridazine Metal‐Coordinating Ligands
Authors: Hoogenboom Richard , Kickelbick Guido , Schubert Ulrich S. 
Published: December 2003

AbstractThe synthesis of novel functionalized 3,6‐di(2‐pyridyl)pyridazines via an inverse electron demand Diels−Alder reaction between the corresponding 3,6‐di(2‐pyridyl)‐1,2,4,5‐tetrazine and various alkynes is reported. The resulting 3,6‐di(2‐pyridyl)pyridazines were investigated using X‐ray crystallography, IR spectroscopy, and NMR spectroscopy, whereby several 2D NMR spectroscopic techniques were exploited to conclusively assign all proton‐ and carbon‐resonances. In addition, it was demonstrated that the functionalized 3,6‐di(2‐pyridyl)pyridazines are capable of forming [2 × 2] grid‐like metal complexes with copper(I) and silver(I) ions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Antitumor Cytotoxicity Evaluation of Novel Thiazole‐Containing Glycosylated Polyamides
Authors: Kumar Rohtash , Lown J. William 
Published: December 2003

AbstractCertain thiazole‐containing water‐soluble glycosylated polyamides were synthesized and preliminary anti‐cancer evaluation carried out by NCI against three types of cancer‐cells. Glycosyl moieties were introduced onto the polyamide backbone in order to increase the water‐solubility of the longer polymers. This necessitated the development of novel synthetic methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
3,5‐Di‐(tert‐Butyl)‐6‐fluoro‐cycloSal‐d4TMP − A Pronucleotide with a Considerably Improved Masking Group
Authors: Ducho Christian , Wendicke Silke , Görbig Ulf , Balzarini Jan , Meier Chris 
Published: December 2003

AbstractA new, considerably improved cycloSal masking group has been developed. This new group combines four desirable properties and has been attached to the anti‐HIV drug 2′,3′‐dideoxy‐2′,3′‐didehydrothymidine (d4T, 1) to give 3,5‐(di‐tert‐butyl)‐6‐fluoro‐cycloSal‐d4TMP (2i). This phosphate triester has a reasonable chemical half‐life, highly selectively released d4TMP, has poor − if any − inhibitory effect on butyrylcholinesterase (BChE), and achieved the TK‐bypass. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
One‐Pot Synthesis of α‐Amino Phosphonates Using Samarium Diiodide as a Catalyst Precursor
Authors: Xu Fan , Luo Yiqin , Deng Mingyu , Shen Qi 
Published: December 2003

AbstractA simple and efficient preparation of α‐amino phosphonates under relatively mild conditions by the one‐pot reaction of aldehydes with amines and dialkyl phosphites using catalytic amounts of SmI2 is described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Simplification in Synthesis
Authors: Bertz Steven H. , Rücker Christoph , Rücker Gerta , Sommer Toby J. 
Published: December 2003

AbstractMathematics Applied to Synthetic Analysis (MASA) is a useful addition to Logic and Heuristics Applied to Synthetic Analysis (LHASA), as it can be used to calculate the simplification afforded by alternative disconnections of a target molecule. One‐bond and two‐bond disconnections that are more efficient as far as simplification is concerned than those identified by the LHASA criteria have been found by using MASA. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Three origins of ΦX174 am3 revertants in transgenic cell culture
Authors: Malling Heinrich V. , Delongchamp Robert R. , Valentine Carrie R. 
Published: December 2003

AbstractTransgenic systems for measuring mammalian mutagenesis often use recoverable viral vectors. We hypothesize that mutations in these transgenic systems can arise from three different origins of DNA damage and replication errors and that these three origins of mutations (in vivo, ex vivo, and in vitro) can be differentiated in the ΦX174 am3, cs70 single burst assay (SBA) on the basis of burst size (BS). In vivo mutations are fixed in the animal, ex vivo mutations are fixed in bacterial cells during recovery of the phage, and in vitro revertants arise during the first replications of nonmutant phages under selective conditions. PX‐2 cells, derived from a homozygous embryo of a ΦX174 transgenic mouse, were treated with vehicle or N‐ethyl‐N‐nitrosourea (ENU). An algorithm was developed to estimate the BS that resulted in the highest induced revertant frequency; the estimate was 56. In vivo revertants were defined as having BS >55, ex vivo revertants as having a BS of 13–56, and in vitro revertants as having a BS of <14. The frequencies of in vivo revertants at 0, 100, and 200 mg/kg ENU were 0.06, 0.36, and 4.10 × 10−6 (dose response, P = 0.004); ex vivo revertants were 0.36, 0.46, and 0.41 × 10−6 (P = 0.37), and in vitro revertants were 0.39, 0.46, and 0.41 × 10−6 (P = 0.55), respectively. These results show that only in vivo revertants reflect mutagen treatment. They also provide a basis for identifying ΦX174 am3 revertants induced in vivo and may increase the sensitivity of the assay for in vivo mutation. Environ. Mol. Mutagen. 42:258–273, 2003. Published 2003 Wiley‐Liss, Inc.
Sources of polycyclic aromatic hydrocarbon exposure in non‐occupationally exposed Koreans
Authors: Yang Mihi , Kim Soyeon , Lee Eunil , Cheong Hae‐Kwan , Chang Seong‐Sil , Kang Daehee , Choi Yunhee , Lee Su‐Man , Jang Jae‐Yeon 
Published: December 2003

AbstractUrinary 1‐hydroxypyrene (1‐OHP), an exposure biomarker for polycyclic aromatic hydrocarbons (PAHs), was used to identify potential sources of PAH exposure for 660 Koreans who were not occupationally exposed to PAHs (65% male; 35% female; mean age, 36.5 ± 11.1 years). In this study, 74% of subjects had detectable levels of urinary 1‐OHP, with a concentration range of 0.001–3.796 μg/L (median, 0.079 μg/L). A backward elimination was conducted: five variables were selected with a significance level for removal of P ≤ 0.1. The results of this study showed that residence in areas with relatively poor environmental conditions (Seoul and Suwon) was strongly associated with high concentrations of urinary 1‐OHP (P = 0.007), while consumption of fried chicken and length of time spent outdoors had marginal positive associations with urinary 1‐OHP levels (P = 0.06 and P = 0.09, respectively). Compared with the above three factors, tobacco smoking and urinary cotinine levels were poorly associated with urinary 1‐OHP (P = 0.16 and 0.23, respectively). Pear consumption had an inverse association with urinary 1‐OHP levels (P < 0.01). Individual variations in urinary 1‐OHP concentrations were evaluated by considering the subjects' age, sex, and genetic polymorphisms in enzymes involved in the metabolism of PAHs. Among the individual variations, GSTT1‐present subjects showed higher 1‐OHP levels than GSTT1‐absent subjects in cities having 10‐μm particulate matter (PM10) levels and population density lower than those of Seoul and Suwon (P < 0.05). These epidemiological results suggest that the above factors that should be considered in preventing PAH exposure. Environ. Mol. Mutagen. 42:250–257, 2003. © 2003 Wiley‐Liss, Inc.
Deletion, rearrangement, and gene conversion; genetic consequences of chromosomal double‐strand breaks in human cells
Authors: Honma Masamitsu , Izumi Masako , Sakuraba Mayumi , Tadokoro Satoshi , Sakamoto Hiroko , Wang Wensheng , Yatagai Fumio , Hayashi Makoto 
Published: December 2003

AbstractChromosomal double‐strand breaks (DSBs) in mammalian cells are usually repaired through either of two pathways: end‐joining (EJ) or homologous recombination (HR). To clarify the relative contribution of each pathway and the ensuing genetic changes, we developed a system to trace the fate of DSBs that occur in an endogenous single‐copy human gene. Lymphoblastoid cell lines TSCE5 and TSCER2 are heterozygous (+/−) or compound heterozygous (−/−), respectively, for the thymidine kinase gene (TK), and we introduced an I‐SceI endonuclease site into the gene. EJ for a DSB at the I‐SceI site results in TK‐deficient mutants in TSCE5 cells, while HR between the alleles produces TK‐proficient revertants in TSCER2 cells. We found that almost all DSBs were repaired by EJ and that HR rarely contributes to the repair in this system. EJ contributed to the repair of DSBs 270 times more frequently than HR. Molecular analysis of the TK gene showed that EJ mainly causes small deletions limited to the TK gene. Seventy percent of the small deletion mutants analyzed showed 100‐ to 4,000‐bp deletions with a 0‐ to 6‐bp homology at the joint. Another 30%, however, were accompanied by complicated DNA rearrangements, presumably the result of sister‐chromatid fusion. HR, on the other hand, always resulted in non‐crossing‐over gene conversion without any loss of genetic information. Thus, although HR is important to the maintenance of genomic stability in DNA containing DSBs, almost all chromosomal DSBs in human cells are repaired by EJ. Environ. Mol. Mutagen. 42:288–298, 2003. © 2003 Wiley‐Liss, Inc.
Model assessment and model building in fMRI
Authors: Razavi Mehrdad , Grabowski Thomas J. , Vispoel Walter P. , Monahan Patrick , Mehta Sonya , Eaton Brent , Bolinger Lizann 
Published: December 2003

AbstractModel quality is rarely assessed in fMRI data analyses and less often reported. This may have contributed to several shortcomings in the current fMRI data analyses, including: (1) Model mis‐specification, leading to incorrect inference about the activation‐maps, SPM{t} and SPM{F}; (2) Improper model selection based on the number of activated voxels, rather than on model quality; (3) Under‐utilization of systematic model building, resulting in the common but suboptimal practice of using only a single, pre‐specified, usually over‐simplified model; (4) Spatially homogenous modeling, neglecting the spatial heterogeneity of fMRI signal fluctuations; and (5) Lack of standards for formal model comparison, contributing to the high variability of fMRI results across studies and centers. To overcome these shortcomings, it is essential to assess and report the quality of the models used in the analysis. In this study, we applied images of the Durbin‐Watson statistic (DW‐map) and the coefficient of multiple determination (R2‐map) as complementary tools to assess the validity as well as goodness of fit, i.e., quality, of models in fMRI data analysis. Higher quality models were built upon reduced models using classic model building. While inclusion of an appropriate variable in the model improved the quality of the model, inclusion of an inappropriate variable, i.e., model mis‐specification, adversely affected it. Higher quality models, however, occasionally decreased the number of activated voxels, whereas lower quality or inappropriate models occasionally increased the number of activated voxels, indicating that the conventional approach to fMRI data analysis may yield sub‐optimal or incorrect results. We propose that model quality maps become part of a broader package of maps for quality assessment in fMRI, facilitating validation, optimization, and standardization of fMRI result across studies and centers. Hum. Brain Mapping 20:227–238, 2003. © 2003 Wiley‐Liss, Inc.
Early stage Parkinson's disease patients and normal volunteers: Comparative mechanisms of sequence learning
Authors: Mentis Marc J. , Dhawan V. , Feigin Andrew , Delalot Dominique , Zgaljardic Dennis , Edwards Christine , Eidelberg David 
Published: December 2003

AbstractEarly‐stage nondemented Parkinson's disease (PD(es)) patients can learn short but not long sequences as well as controls. We have previously shown that to achieve normal performance, PD(es) patients activated the same right‐sided cortical regions as controls plus the homologous left sided cortex and bilateral cerebellum. In this study, we evaluated two related hypotheses to explain the behavioral abnormalities and the increased bilateral brain activation observed in the PD(es) group. Hypothesis 1 proposed that PD(es) patients recruit regions from a normal bilateral network specialized for sequence learning that healthy controls would activate if performing difficult tasks. Thus, PD(es) patients can learn short sequences as well as controls. Hypothesis 2 proposed that information processing within the network in the PD(es) group is impaired. Thus, PD(es) patients cannot learn as difficult a sequence as controls. To test hypothesis 1, we increased task difficulty and statistical power in the control group and showed that the control and the PD(es) groups activated the same regions. To test hypothesis 2, we analyzed the equal performance data using two partial least squares (PLS) multivariate analyses. The task‐PLS analysis showed that to perform equally with controls, the PD(es) group expressed the normal bilateral network more than the control group. The behavior‐PLS analysis showed that the correlation between learning performance and regional activation was significantly different between the groups. We conclude that PD(es) patients have near normal learning if task difficulty is moderate because they can recruit additional regions from a normal bilateral network specialized for sequence learning. However, when a difficult task would normally require bilateral activation, PD(es) patients fail to learn because information processing within the network is impaired. Hum. Brain Mapp. 20:246–258, 2003. © 2003 Wiley‐Liss, Inc.
Modelling supply and demand influences on the use of health care: implications for deriving a needs‐based capitation formula
Authors: Gravelle Hugh , Sutton Matthew , Morris Stephen , Windmeijer Frank , Leyland Alastair , Dibben Chris , Muirhead Mike 
Published: December 2003

AbstractMany health‐care systems allocate funding according to measures of need. The utilisation approach for measuring need rests on the assumptions that use of health care is determined by demand and supply and that need is an important element of demand. By estimating utilisation models which allow for supply it is possible to isolate the socio‐economic and health characteristics which affect demand. A subset of these variables can then be identified by a combination of judgement and further analysis as needs variables to inform funding allocations. We estimate utilisation models using newly assembled data on admissions to acute hospitals, measures of supply, morbidity and socio‐economic characteristics for 8414 small geographical areas in England. We make a number of methodological innovations including deriving additional measures of specific morbidities at small area level from individual level survey data. We compare models with different specifications for the effect of waiting times and provider characteristics, with total, planned and unplanned hospital admissions, and estimated at small area (ward) and primary care organisation (general practice) level. After allowing for waiting times, distance, capacity and the availability of private health care, measures of mortality, self‐reported morbidity, low education and low income increase the use of health care. We find evidence of horizontal inequity with respect to ethnicity and employment and suggest a method for reducing its effects when deriving a needs‐based allocation formula. Copyright © 2003 John Wiley & Sons, Ltd.
Transient‐state groundwater flow in various geometries with wells at arbitrary positions: analytical methods
Authors: Roth M. W. , Wilson C. M , Iqbal M. Z. 
Published: December 2003

AbstractWe have developed a method for analytically solving the porous medium flow equation in many different geometries for horizontal (two‐dimensional), homogeneous and isotropic aquifers containing impermeable boundaries and any number of pumping or injection wells located at arbitrary positions within the system. Solutions and results are presented for rectangular and circular aquifers but the method presented here is easily extendible to many geometries. Results are also presented for systems where constant head boundary conditions can be emulated internal to the aquifer boundary. Recommendations for extensions of the present work are briefly discussed. Copyright © 2003 John Wiley & Sons, Ltd.
REM behavior disorder and excessive daytime somnolence in Machado–Joseph disease (SCA‐3)
Authors: Friedman Joseph H. , Fernandez Hubert H. , Sudarsky Lewis R. 
Published: December 2003

AbstractWe reported previously that behavior suggestive of rapid eye movement sleep behavior disorder (RBD) was markedly increased in a small population of SCA‐3 patients. We, therefore, asked patients and nonpatient attendees at an SCA‐3 annual clinic to complete a questionnaire soliciting RBD‐like behavior. Our results support the previous observation that RBD‐like behaviors are significantly increased in SCA‐3. © 2003 Movement Disorder Society
Cognitive executive function in dystonia
Authors: Jahanshahi Marjan , Rowe John , Fuller Rebecca 
Published: December 2003

AbstractDystonia is a movement disorder considered to result from basal ganglia dysfunction. The aim of this study was to investigate the functional significance of frontal hyperactivity demonstrated in dystonia in imaging studies by examining executive function and working memory, in which the prefrontal cortex is known to be involved. We assessed 10 patients with idiopathic dystonia and 12 age‐ and IQ‐matched normal controls. All subjects completed tests of first letter, category, and alternating category word fluency, the Wisconsin Card Sorting Test, the Stroop Colour Word Naming Test, the Missing Digit Test of working memory, a test of random number generation, a test requiring generation of self‐ordered random number sequences, the Paced Serial Addition Test, a test of conditional associative learning, and finger tapping and peg insertion under unimanual, bimanual, and dual task conditions. The patients with dystonia did not differ significantly from controls on any measures of executive function or working memory used other than category word fluency and the extent of decline in tapping with one hand under dual task conditions when simultaneously inserting pegs with the other hand. For this small sample, the results suggest that unlike other movement disorders associated with fronto‐striatal dysfunction such as Parkinson's disease or Huntington's disease, dystonia was not associated with deficits on the tests of executive function or working memory used. A more detailed investigation of cognitive function in a larger sample of patients is required. © 2003 Movement Disorder Society
Pure cerebello‐olivary degeneration of Marie, Foix, and Alajouanine presenting with progressive cerebellar ataxia, cognitive decline, and chorea
Authors: Fox Susan H. , Nieves Anette , Bergeron Catherine , Lang Anthony E. 
Published: December 2003

AbstractParenchymatous cerebellar cortical atrophy (CCA) usually presents with a “pure” cerebellar ataxia. We describe a patient with a sporadic, late‐onset progressive cerebellar ataxia plus cognitive decline and chorea who had CCA at post mortem. We discuss this unique case in the current context of classification of idiopathic cerebellar ataxia. © 2003 Movement Disorder Society
Striatal encephalitis after varicella zoster infection complicated by Tourettism
Authors: Dale Russell C. , Church Andrew J. , Heyman Isobel 
Published: December 2003

AbstractWe describe a case of encephalitis after primary varicella zoster infection with localised basal ganglia imaging abnormalities. The patient subsequently developed a chronic tic disorder with attention deficit disorder. This case furthers the proposed association between Tourettism and the basal ganglia. © 2003 Movement Disorder Society