bluuebunny/crossref_metadata_2025 huggingface dataset:
Part-time and full-time medical specialists, are there differences in allocation of time?
Authors: de Jong Judith D , Heiligers Phil , Groenewegen Peter P , Hingstman Lammert
Published: March 2006

Background

An increasing number of medical specialists prefer to work part-time. This development can be found worldwide. Problems to be faced in the realization of part-time work in medicine include the division of night and weekend shifts, as well as communication between physicians and continuity of care. People tend to think that physicians working part-time are less devoted to their work, implying that full-time physicians complete a greater number of tasks. The central question in this article is whether part-time medical specialists allocate their time differently to their tasks than full-time medical specialists.

Methods

A questionnaire was sent by mail to all internists (N = 817), surgeons (N = 693) and radiologists (N = 621) working in general hospitals in the Netherlands. Questions were asked about the actual situation, such as hours worked and night and weekend shifts. The response was 53% (n = 411) for internists, 52% (n = 359) for surgeons, and 36% (n = 213) for radiologists. Due to non-response on specific questions there were 367 internists, 316 surgeons, and 71 radiologists included in the analyses. Multilevel analyses were used to analyze the data.

Results

Part-time medical specialists do not spend proportionally more time on direct patient care. With respect to night and weekend shifts, part-time medical specialists account for proportionally more or an equal share of these shifts. The number of hours worked per FTE is higher for part-time than for full-time medical specialists, although this difference is only significant for surgeons.

Conclusion

In general, part-time medical specialists do their share of the job. However, we focussed on input only. Besides input, output like the numbers of services provided deserves attention as well. The trend in medicine towards more part-time work has an important consequence: more medical specialists are needed to get the work done. Therefore, a greater number of medical specialists have to be trained. Part-time work is not only a female concern; there are also (international) trends for male medical specialists that show a decline in the number of hours worked. This indicates an overall change in attitudes towards the number of hours medical specialists should work.
Protein cleavage strategies for an improved analysis of the membrane proteome
Authors: Fischer Frank , Poetsch Ansgar
Published: March 2006

Background

Membrane proteins still remain elusive in proteomic studies. This is in part due to the distribution of the amino acids lysine and arginine, which are less frequent in integral membrane proteins and almost absent in transmembrane helices. As these amino acids are cleavage targets for the commonly used protease trypsin, alternative cleavage conditions, which should improve membrane protein analysis, were tested by in silico digestion for the three organisms Saccharomyces cerevisiae, Halobacterium sp. NRC-1, and Corynebacterium glutamicum as hallmarks for eukaryotes, archea and eubacteria.

Results

For the membrane proteomes from all three analyzed organisms, we identified cleavage conditions that achieve better sequence and proteome coverage than trypsin. Greater improvement was obtained for bacteria than for yeast, which was attributed to differences in protein size and GRAVY. It was demonstrated for bacteriorhodopsin that the in silico predictions agree well with the experimental observations.

Conclusion

For all three examined organisms, it was found that a combination of chymotrypsin and staphylococcal peptidase I gave significantly better results than trypsin. As some of the improved cleavage conditions are not more elaborate than trypsin digestion and have been proven useful in practice, we suppose that the cleavage at both hydrophilic and hydrophobic amino acids should facilitate in general the analysis of membrane proteins for all organisms.
Tumor-associated endothelial cells display GSTP1 and RARβ2 promoter methylation in human prostate cancer
Authors: Grover Amelia C , Tangrea Michael A , Woodson Karen G , Wallis Benjamin S , Hanson Jeffrey C , Chuaqui Rodrigo F , Gillespie John W , Erickson Heidi S , Bonner Robert F , Pohida Thomas J , Emmert-Buck Michael R , Libutti Steven K
Published: March 2006

Background

A functional blood supply is essential for tumor growth and proliferation. However, the mechanism of blood vessel recruitment to the tumor is still poorly understood. Ideally, a thorough molecular assessment of blood vessel cells would be critical in our comprehension of this process. Yet, to date, there is little known about the molecular makeup of the endothelial cells of tumor-associated blood vessels, due in part to the difficulty of isolating a pure population of endothelial cells from the heterogeneous tissue environment.

Methods

Here we describe the use of a recently developed technique, Expression Microdissection, to isolate endothelial cells from the tumor microenvironment. The methylation status of the dissected samples was evaluated for GSTP1 and RARβ2 promoters via the QMS-PCR method.

Results

Comparing GSTP1 and RARβ2 promoter methylation data, we show that 100% and 88% methylation is detected, respectively, in the tumor areas, both in epithelium and endothelium. Little to no methylation is observed in non-tumor tissue areas.

Conclusion

We applied an accurate microdissection technique to isolate endothelial cells from tissues, enabling DNA analysis such as promoter methylation status. The observations suggest that epigenetic alterations may play a role in determining the phenotype of tumor-associated vasculature.
The effects of sex and hormonal status on restraint-stress-induced working memory impairment
Authors: Shansky Rebecca M , Rubinow Katya , Brennan Avis , Arnsten Amy FT
Published: March 2006

Background

Restraint stress has been shown to elicit numerous effects on hippocampal function and neuronal morphology, as well as to induce dendritic remodeling in the prefrontal cortex (PFC). However, the effects of acute restraint stress on PFC cognitive function have not been investigated, despite substantial evidence that the PFC malfunctions in many stress-related disorders.

Methods

The present study examined the effects of restraint stress on PFC function in both male rats and cycling female rats in either the proestrus (high estrogen) or estrus (low estrogen) phase of the estrus cycle. Animals were restrained for 60 or 120 minutes and then tested on spatial delayed alternation, a PFC-mediated task. Performance after stress was compared to performance on a different day under no-stress conditions, and analyzed using analysis of variance (ANOVA).

Results

Sixty minutes of restraint impaired only females in proestrus, while 120 minutes of restraint produced significant impairments in all animals. Increases in task completion times did not affect performance.

Conclusion

These results demonstrate an interaction between hormonal status and cognitive response to stress in female rats, with high estrogen levels being associated with amplified sensitivity to stress. This effect has been previously observed after administration of a pharmacological stressor (the benzodiazepine inverse agonist FG7142), and results from both studies may be relevant to the increased prevalence of stress-related disorders, such as major depressive disorder, in cycling women. Overall, the results show that restraint stress has important effects on the cognitive functions of the PFC, and that hormonal influences in the PFC are an important area for future research.
Changes in farmers' knowledge of maize diversity in highland Guatemala, 1927/37-2004
Authors: van Etten Jacob
Published: March 2006

Small-scale studies on long-term change in agricultural knowledge might uncover insights with broader, regional implications. This article evaluates change in farmer knowledge about crop genetic resources in highland Guatemala between 1927/37 and 2004. It concentrates on maize (Zea mays ssp. mays L.) in one Guatemalan township, Jacaltenango, an area with much ecological and maize diversity. It relies on a particular type of baseline information: lists of farmer-defined cultivars drawn up by ethnographers in the first half of the twentieth century. A questionnaire format based on two independent lists of local farmer cultivars dating from 1927 and 1937 was used to assess changes in maize diversity. Comparisons between attributes given to each cultivar in the past and in 2004 were used as a partial test of the stability of cultivar identity. In farmers' perceptions, cultivar loss was low and limited to certain cultivars adapted to the warmer environments. Crop production problems were mentioned as the main motives for change. No evidence for a loss of cultivars due to the political violence of the 1980s was found. In the lower areas many newly introduced cultivars were found, which reportedly provide solutions for the production problems the older cultivars have. The article contrasts these findings with those of an earlier study which suggested much cultivar loss due to political violence, and draws conclusions about the methodological implications.
Does prophylactic sotalol and magnesium decrease the incidence of atrial fibrillation following coronary artery bypass surgery: a propensity-matched analysis
Authors: Aerra V , Kuduvalli M , Moloto AN , Srinivasan AK , Grayson AD , Fabri BM , Oo AY
Published: March 2006

Background

Atrial fibrillation can occur in up to 40% of patients undergoing coronary surgery.

Methods

We retrospectively analysed 103 consecutive coronary surgery patients under the care of one surgeon between April 2003 and September 2003. These patients received 40 mg of sotalol orally twice daily from the first post-operative day for 6 weeks and 2 g of magnesium intravenously immediately post surgery and on the first post-operative day. We developed a propensity score for the probability of receiving sotalol and magnesium after coronary surgery. 89 patients from the sotalol and magnesium group were successfully matched with 89 unique coronary surgery patients who did not receive either sotalol or magnesium with an identical propensity score.

Results

Preoperative characteristics were well matched between groups. There was no significant difference with respect to in-hospital mortality between groups (sotalol and magnesium 1.1% versus control 4.5%; p = 0.17). The incidence of atrial fibrillation in the sotalol and magnesium group was 13.5% compared to 27.0% in the controls (p = 0.025).

Conclusion

The combination of sotalol and magnesium can significantly reduce the incidence of post-operative atrial fibrillation following coronary surgery.
Ultrasonography of the metacarpophalangeal and proximal interphalangeal joints in rheumatoid arthritis: a comparison with magnetic resonance imaging, conventional radiography and clinical examination
Authors: Szkudlarek Marcin , Klarlund Mette , Narvestad Eva , Court-Payen Michel , Strandberg Charlotte , Jensen Karl E , Thomsen Henrik S , Østergaard Mikkel
Published: March 2006

Signs of inflammation and destruction in the finger joints are the principal features of rheumatoid arthritis (RA). There are few studies assessing the sensitivity and specificity of ultrasonography in detecting these signs. The objective of the present study was to investigate whether ultrasonography can provide information on signs of inflammation and destruction in RA finger joints that are not available with conventional radiography and clinical examination, and comparable to the information provided by magnetic resonance imaging (MRI). The second to fifth metacarpophalangeal and proximal interphalangeal joints of 40 RA patients and 20 control persons were assessed with ultrasonography, clinical examination, radiography and MRI. With MRI as the reference method, the sensitivity, specificity and accuracy of ultrasonography in detecting bone erosions in the finger joints were 0.59, 0.98 and 0.96, respectively; they were 0.42, 0.99 and 0.95 for radiography. The sensitivity, specificity and accuracy of ultrasonography, with signs of inflammation on T1-weighted MRI sequences as the reference method, were 0.70, 0.78 and 0.76, respectively; they were 0.40, 0.85 and 0.72 for the clinical examination. With MRI as the reference method, ultrasonography had higher sensitivity and accuracy in detecting signs of inflammation and destruction in RA finger joints than did clinical and radiographic examinations, without loss of specificity. This study shows that ultrasonography has the potential to improve assessment of patients with RA.
Expression of the inflammatory chemokines CCL5, CCL3 and CXCL10 in juvenile idiopathic arthritis, and demonstration of CCL5 production by an atypical subset of CD8+ T cells
Authors: Pharoah Daniel S , Varsani Hemlata , Tatham Richard W , Newton Katy R , de Jager Wilco , Prakken Berent J , Klein Nigel , Wedderburn Lucy R
Published: March 2006

This study focuses upon three chemokines, namely CCL5, CXCL10 and CCL3, which are potential novel therapeutic targets in arthritis. The aim of the study was to analyse the expression and production of these three chemokines within the joints of children with juvenile idiopathic arthritis (JIA) of the oligoarticular and polyarticular subtypes. All three of these chemokines are highly expressed at the level of mRNA, with the most significant increase in mRNA levels being demonstrated for CCL5 when compared with matched peripheral blood samples and controls. We show that high levels of all three chemokines are present in synovial fluid of children with JIA. We investigate the major source of CCL5 from inflammatory synovial cells, which we show to be CD8+ T cells. This CD8+ synovial T cell population has an unexpected phenotype that has not been described previously, being CCR7- yet predominantly CD28+ and CD45RA-. These cells contain high levels of stored intracellular CCL5, and rapid release of CCL5 takes place on T cell stimulation, without requiring new protein synthesis. In addition, we demonstrate that CCL5 is present in synovial biopsies from these patients, in particular on the endothelium of small and medium sized vessels. We believe this to be the first in depth analysis of these mediators of inflammation in JIA.
Lack of association of a variable number of aspartic acid residues in the asporin gene with osteoarthritis susceptibility: case-control studies in Spanish Caucasians
Authors: Rodriguez-Lopez Julio , Pombo-Suarez Manuel , Liz Myriam , Gomez-Reino Juan J , Gonzalez Antonio
Published: March 2006

A recent genetic association study has identified a microsatellite in the coding sequence of the asporin gene as a susceptibility factor for osteoarthritis (OA). Alleles of this microsatellite determine the variable number of aspartic acid residues in the amino-terminal end of the asporin protein. Asporin binds directly to the growth factor transforming growth factor beta and inhibits its anabolic effects in cartilage, which include stimulation of collagen and aggrecan synthesis. The OA-associated allele, with 14 aspartic acid residues, inhibits the anabolic effects of transforming growth factor beta more strongly than other asporin alleles, leading to increased OA liability. We have explored whether the association found in several cohorts of Japanese hip OA and knee OA patients was also present in Spanish Caucasians. We studied patients that had undergone total joint replacement for primary OA in the hip (n = 303) or the knee (n = 188) and patients with hand OA (n = 233), and we compared their results with controls (n = 294) lacking overt OA clinical symptoms. No significant differences were observed in any of the multiple comparisons performed, which included global tests of allele frequency distributions and specific comparisons as well as stratification by affected joint and by sex. Our results, together with reports from the United Kingdom and Greece, indicate that the stretch of aspartic acid residues in asporin is not an important factor in OA susceptibility among European Caucasians. It remains possible that lifestyle, environmental or genetic differences allow for an important effect of asporin variants in other ethnic groups as has been reported in the Japanese, but this should be supported by additional studies.
Differential Modulation of Estrogen Receptors (ERs) in Ischemic Brain Injury: A Role for ERα in Estradiol-Mediated Protection against Delayed Cell Death
Authors: Dubal Dena B. , Rau Shane W. , Shughrue Paul J. , Zhu Hong , Yu Jin , Cashion Adrienne B. , Suzuki Shotaro , Gerhold Lynnette M. , Bottner Martina B. , Dubal Sam B. , Merchanthaler Istvan , Kindy Mark S. , Wise Phyllis M.
Published: March 2006

Estradiol enhances plasticity and survival of the injured brain. Our previous work demonstrates that physiological levels of estradiol protect against cerebral ischemia in the young and aging brain through actions involving estrogen receptors (ERs) and alterations in gene expression. The major goal of this study was to establish mechanisms of neuroprotective actions induced by low levels of estradiol. We first examined effects of estradiol on the time-dependent evolution of ischemic brain injury. Because estradiol is known to influence apoptosis, we hypothesized that it acts to decrease the delayed phase of cell death observed after middle cerebral artery occlusion (MCAO). Furthermore, because ERs are pivotal to neuroprotection, we examined the temporal expression profiles of both ER subtypes, ERα and ERβ, after MCAO and delineated potential roles for each receptor in estradiol-mediated neuroprotection. We quantified cell death in brains at various times after MCAO and analyzed ER expression by RT-PCR, in situ hybridization, and immunohistochemistry. We found that during the first 24 h, the mechanisms of estradiol-induced neuroprotection after MCAO are limited to attenuation of delayed cell death and do not influence immediate cell death. Furthermore, we discovered that ERs exhibit distinctly divergent profiles of expression over the evolution of injury, with ERα induction occurring early and ERβ modulation occurring later. Finally, we provide evidence for a new and functional role for ERα in estradiol-mediated protection of the injured brain. These findings indicate that physiological levels of estradiol protect against delayed cell death after stroke-like injury through mechanisms requiring ERα.
Surgical Management of Depressed Cranial Fractures
Authors: Bullock M Ross , Chesnut Randall , Ghajar Jamshid , Gordon David , Hartl Roger , Newell David W. , Servadei Franco , Walters Beverly C. , Wilberger Jack
Published: March 2006

RECOMMENDATIONS (see Methodology)

Indications

Timing

Methods
Electronically Tunable Compact Trialkylphosphines: SMAPs-bridged Bicyclic Phosphines
Authors: Ochida Atsuko , Ito Shinichiro , Miyahara Takahiro , Ito Hajime , Sawamura Masaya
Published: March 2006

A series of silicon-constrained monodentate trialkylphosphines SMAPs bearing a Si substituent with diverse electronic natures were synthesized. DFT calculations and NMR measurements indicated that these compounds constitute a class of electronically tunable trialkylphosphines. The tunable range of donor power overlaps those of tri(tert-butyl)phosphine and monoalkyldiarylphosphines.
Reaction of Allylic-type Diindium Compounds with Electrophiles
Authors: Hirashita Tsunehisa , Arai Shun , Mitsui Kazuma , Makino Hajime , Araki Shuki
Published: March 2006

Allylic-type diindium reagents were prepared from 3-bromo-1-iodopropene (1a), 3-bromo-1-iodo-1-phenylpropene (1b), or 2,4-diiodobut-2-en-1-ol (1c) with metallic indium, and their successive coupling with electrophiles was examined. The coupling behavior of the diindium reagents was found to depend on the electrophiles and the substituent on the diindium compounds.
Glycosylation of Vitamin E Homologue by Cultured Plant Cells
Authors: Kondo Yoko , Shimoda Kei , Takimura Junichi , Hamada Hatsuyuki , Hamada Hiroki
Published: March 2006

Biotransformation of 2,2,5,7,8-pentamethyl-6-chromanol (vitamin E homologue) was investigated with cultured plant cells of Phytolacca americana, Catharanthus roseus, and Eucalyptus perriniana. The cultured cells of P. americana converted 2,2,5,7,8-pentamethyl-6-chromanol into its β-glucoside, whereas conversion with C. roseus and E. perriniana also afforded the hydrolysis product of β-glucoside and a new β-gentiobioside product, i.e., 2,2,5,7,8-pentamethylchroman-6-yl 6-O-β-d-glucopyranosyl-β-d-glucopyranoside.
Preparation of Novel Eu-doped Titanate Nanotube Phosphor
Authors: Chi Bo , Victorio Erick S , Jin Tetsuro
Published: March 2006

A novel titanate nanotube phosphor doped with Eu was synthesized through a facile hydrothermal treatment method. The multilayered nanotubes have an outer diameter of 12 nm and inner diameter of 4 nm, with a BET surface area of 225 m2·g−1. The nanotube was identified to have a monoclinic layered titanate structure. The Eu-doped nanotube exhibits luminescent property that is slightly different from the corresponding nanopowder.
New Charge-transfer Salts Based on Unsymmetrical Donor DMET and Metal Complex Anions: (DMET)3[Cr(isoq)2(NCS)4] and (DMET)3[Cr(phen)(NCS)4]·CH3CN
Authors: Umemiya Masamichi , Goto Makoto , Kobayashi Norihito , Takaishi Shinya , Kajiwara Takashi , Yamashita Masahiro , Miyasaka Hitoshi , Sugiura Ken-ichi , Watanabe Harutaka , Suzuki Daichi , Ito Hiroshi , Kuroda Shin-ichi
Published: March 2006

Two charge-transfer salts (DMET)3[Cr(isoq)2(NCS)4] (1) and (DMET)3[Cr(phen)(NCS)4]·CH3CN (2) have been prepared and characterized. The single-crystal X-ray crystallography revealed that the structures of both salts consist of segregated columns of DMET and metal complex anions. The magnetic and transport properties have shown that these salts are paramagnetic semiconductors.
Cationization versus Surface Activity—The Effect on Electrospray Ionization
Authors: Frańska Magdalena , Przybysz Ilona , Borkowska Magdalena , Kozik Tomasz
Published: March 2006

Ethoxylated fatty alcohols, C12E1, C12E2, C18E1 and C18E2, were studied by electrospray ionization mass spectrometry (E is the ethoxylene unit –OCH2CH2–). For compounds containing two ethoxylene units, which form quite stable adducts with sodium cation, the abundances of [M + Na]+ ions were not affected by alkyl chain, so the hydrophobic effect was not observed. For the compounds containing one ethoxylene unit, forming rather unstable adducts with sodium, the hydrophobic effect was clearly seen since the [C18E1 + Na]+ ion was more abundant than the [C12E1 + Na]+ ion. Two ethoxylene units are not able to form stable adducts with potassium cations, therefore the hydrophobic effect was observed for the [C12E2 + K]+ and [C18E2 + Na]+ ions, the latter being more abundant than the former. For lithium cation adducts with C12E1 and C18E1, the hydrophobic effect was observed, but was less manifested than for sodium cations since lithium adducts are more stable than sodium ones. C18E1 and C18E2 gave more intense signals at higher cone voltage values than C12E1 and C12E2, respectively. However, this is not related to the hydrophobic effect but to the collisions being less effective for the former.
Negative Electrospray, Ion Trap Multistage Mass Spectrometry of Synthetic Fragments of the O-PS of Vibrio Cholerae O:1
Authors: Bekešová Slávka , Kováčik Vladimír , Chmelík Josef , Kováč Pavol
Published: March 2006

Saccharides (mono through hexasaccharides) that mimic the terminal epitopes of O-antigens of Vibrio cholerae O:1, serotypes Ogawa and Inaba, were studied by electrospray ion trap (ESI IT) mass spectrometry (MS) in the negative mode. Anionized adducts are the characteristic ions formed by the capture of H3O2− under the condition of ESI MS analysis. The reactive species are produced by reaction of hydroxyl anions with the molecule of water. Thus the [M + H3O2]− have the highest m/z value in the ESI IT negative mass spectra. After dissociation of adducts by loss of 2H2O the [M – H]− ions are produced. The fragmentation pathways were confirmed by multistage measurements (MS n). The predominant pathway of fragmentation of the mono- and oligomers is the elimination of a molecule of α-hydroxy-γ-butyrolactone from the 4-(3-deoxy-l-glycero-tetronamido) group. The other characteristic pathway occurs by shortening the length of oligosaccharides. In this way, conversion of the Ogawa to Inaba fragments takes place under the conditions of measurement. Negative ESI MS/MS provided sufficient information about molecular mass, the number of saccharide residues, basic structure of saccharides, about the tetronamide part of the compounds investigated and allowed Ogawa and Inaba serotypes to be distinguished.
Generation of Alkoxide Anions from a Series of Aliphatic Diols and Alcohols and Their Ion—Molecule Reactions with Carbon Dioxide in the Gas Phase
Authors: Kumar M. Ravi , Prabhakar S. , Reddy T. Jagadeshwar , Vairamani M.
Published: March 2006

Alkoxide anions, [M – H]− from a series of aliphatic diols and alcohols are generated in the source under negative ion electrospray ionisation conditions by cone-voltage fragmentation of the corresponding [M + F]− ions. The collision-induced dissociation (CID) spectra of [M – H]− ions consist of [M – H – 2H]− ions, in addition to the other characteristic fragment ions, and the relative abundance of [M – H – 2H]− ions among the series of diols varies as a function of chain length that could be explained based on their stabilities through intramolecular hydrogen bonding. The reactivity of alkoxide anions is studied through ion–molecule reactions with CO2 in the collision cell of a triple quadrupole mass spectrometer. All the alkoxide anions reacted with CO2 and formed corresponding carbonate anions, [M – H + CO2]− ions. The reactivity of alkoxide anions within the series of diols also reflected the stability of their [M – H]− ions.
Sulfenylphosphinoferrocenes: Novel planar chiral ligands in enantioselective catalysis
Authors: Cabrera Silvia , García Mancheño Olga , Gómez Arrayás Ramón , Alonso Inés , Mauleón Pablo , Carretero Juan C.
Published: March 2006

Structurally well-defined transition-metal complexes of 1-phosphino-2-sulfenylferrocene (Fesulphos ligands) act as highly efficient catalysts in a variety of mechanistically different transformations. Excellent enantioselectivities were achieved in Pd-catalyzed allylic substitutions, desymmetrization of meso-heterobicyclic alkenes by Pd-catalyzed addition of dialkylzinc reagents, Pd-catalyzed Diels-Alder reaction of cyclopentadiene with N-acryloyl oxazolidinones, and in Cu-catalyzed formal aza-Diels-Alder reaction of Danishefsky diene to N-sulfonyl aldimines.
Catalytic asymmetric addition reactions leading to carbon-carbon bond formation: Phenyl and alkenyl transfer to aldehydes and alkynylation of α-imino esters
Authors: Ji Jian-Xin , Wu Jing , Xu Lijin , Yip Chiu-Wing , Lam Kim Hung , Chan Albert S. C.
Published: March 2006

Optically active tertiary aminonaphthol ligands were obtained by a new, convenient procedure and were found to catalyze the enantioselective alkenyl and phenyl transfer to aldehydes in high yields and excellent enantiomeric excesses (ee's). The catalytic asymmetric introduction of alkynyl functionality to α-amino acid derivatives was realized by the direct addition of terminal alkynes to α-imino ester in the presence of chiral copper(I) complex under mild reaction conditions.
Development of homogeneous and heterogeneous asymmetric catalysts for practical enantioselective reactions
Authors: Ding Kuiling
Published: March 2006

Two strategies for the development of practical asymmetric catalysis have been discussed in this article. The first part of this article focuses on the design and screening of highly efficient and enantioselective chiral catalysts for asymmetric hydrogenation reactions employing combinatorial approach. The second part presents a conceptually new strategy (i.e., "self-supporting" approach) for the immobilization of homogeneous catalysts through assembly of chiral multitopic ligands and metal ions without using any support. The success of this strategy will be exemplified in heterogeneous asymmetric carbonyl-ene, sulfoxidation, and epoxidation, as well as in asymmetric hydrogenation reactions.
Rhodium-catalyzed asymmetric reactions with a dynamic library of chiral tropos phosphorus ligands
Authors: Gennari Cesare , Monti Chiara , Piarulli Umberto
Published: March 2006

Nineteen chiral tropos phosphorus ligands, based on a flexible (tropos) biphenol unit and a chiral P-bound alcohol (11 phosphites) or secondary amine (8 phosphoramidites), were screened, individually and as a combination of two, in various Rh-catalyzed asymmetric reactions. In the Rh-catalyzed asymmetric conjugate addition of phenylboronic acid to cyclic enones, enantiomeric excesses (ee's) up to 95 % were obtained with a 1:1 mixture of a phosphite [derived from (1R,2S)-2-(1-methyl-1-phenylethyl)cyclohexanol] and a phosphoramidite [derived from (S,S)-2,5-diphenylpyrrolidine]. In the mixed Rh precatalyst, which was characterized via 31P-NMR, the biphenol-derived phosphite is free to rotate (tropos) while the biphenol-derived phosphoramidite shows a temperature-dependent tropos/atropos behavior (coalescence temperature = 310 K). The ligands were also screened in the hydrogenation of dehydro-α-amino acids and dehydro-β-amino acids. Ee's up to 98% were obtained for the dehydro-α-amino acids, using the combination of a phosphite [derived from (1R,2S)-2-phenyl-1-cyclohexanol] and a phosphoramidite [derived from (S,S)-bis(α-methylbenzyl)amine]. The reaction was optimized by lowering the phosphite/phosphoramidite ratio to 0.25:1.75 with a resulting improvement of the product ee.
Syntheses and reactions of optically active α-aminoallenylstannanes and α-aminopropargylboranes
Authors: Hegedus Louis S. , Ranslow Peter , Achmatowicz Michal , de los Rios Cristobal , Hyland Christopher , Garcia-Frutos Eva M. , Salman Sarri
Published: March 2006

An efficient synthesis of α-aminoallenylstannane from propargyloxazolidinone has been developed. It undergoes reaction with aldehydes to give homopropargylic alcohols with high syn selectivity. Epoxides undergo a similar reaction preceded by rearrangement to the aldehyde. These alcohols were used in the synthesis of β-amino acids, azasugars, and deoxyaminohexoses. Imines underwent reaction with this stannane to give 1,2-diamines. The related propargylborane reacts with aldehydes to produce allenyl carbinols. The Co2(CO)6 complexes of propargyloxazolidinones were developed as an α-aminopropargyl cation equivalent.
Development of palladium catalysts for asymmetric hydroamination reactions
Authors: Hii King Kuok
Published: March 2006

Our development of dicationic palladium(II) complexes for asymmetric hydroamination reactions, particularly the aza-Michael addition, is reviewed.
Palladium-catalyzed ring-forming reactions: Methods and applications
Authors: Lautens Mark , Alberico Dino , Bressy Cyril , Fang Yuan-Qing , Mariampillai Brian , Wilhelm Thorsten
Published: March 2006

Several Pd-catalyzed cyclization methods were developed, including norbornene-mediated Catellani-type reactions, a Pd-catalyzed coupling reaction of aryl iodides and allyl moieties, and a tandem C-N/C-C coupling of gem-dihalovinyl systems. These ring-forming methods were applied to the synthesis of highly functionalized carbocyclic and heterocyclic compounds. Intermolecular Pd-catalyzed methods for synthesis of highly substituted arene compounds were also developed.
Synthesis and reactivity of new strained cyclic allene and alkyne precursors
Authors: Peña Diego , Iglesias Beatriz , Quintana Iago , Pérez Dolores , Guitián Enrique , Castedo Luis
Published: March 2006

The synthesis of ortho-(trimethylsilyl)vinyl triflates is described. Fluoride-induced decomposition of these triflates leads to the generation of strained cycloallenes and cycloalkynes under mild reaction conditions. The generation rate of these highly reactive intermediates can be modulated by modifying the solubility of the fluoride source. The slow generation of cyclic allenes and alkynes is a prerequisite for their use in homogeneous catalysis.
Acid-base catalysis using chiral palladium complexes
Authors: Sodeoka Mikiko , Hamashima Yoshitaka
Published: March 2006

Chiral Pd aqua and µ-hydroxo complexes were found to act as mild Brønsted acids and bases, and chiral Pd enolates were generated from these complexes even under acidic conditions. Highly enantioselective Michael addition, Mannich-type reaction, fluorination, and conjugate addition of amines have been developed based on the acid-base character of these Pd complexes.
Debating Identity, Sovereignty, and Civilization: The Arkansas Valley after the Louisiana Purchase
Authors: DuVal Kathleen
Published: March 2006

In the early nineteenth century, various native peoples engaged in a multilateral debate over their place in the republic, a debate that revolved around issues of identity, sovereignty, cross-cultural relations, rights to resources, and, increasingly, the concepts of civilization and savagery. This article provides a multicultural intellectual history of various Indians and Anglo-Americans in the Louisiana Purchase. It centers on the Arkansas River Valley, where Thomas Jefferson instructed Indians from the east to settle, and on four of its peoples—native Osages and Quapaws and immigrant Cherokees and Anglo-Americans. As Indian and white westward migration intensified competition for game and land, Arkansas Valley inhabitants (old and new, Indian and white) began to look to the federal government to help resolve their disputes, and they couched their arguments in terms that appealed to United States policy-makers. But when local Indians and whites employed the concepts of civilization and savagery, they defined them in their own ways and used them for their own purposes—to argue for their rights to government protection and to land. Although white settlers' desires ultimately prevailed, alternative visions mattered, both in their own right and because they affected the ways in which Anglo-Americans defined themselves and others. Thus, this article presages debates over race and removal later in the century and adds to recent scholarship showing that race is not simply a system of beliefs imposed by whites on nonwhites.
Troubled Manhood in the Early Republic: The Life and Autobiography of Sailor Horace Lane
Authors: Glenn Myra C
Published: March 2006

This essay examines the life and autobiography of Horace Lane (1789-1866), an alcoholic sailor who became a thief and convict after his seafaring career ended. Study of Lane's life offers a revealing example of failed manhood in the early republic. It also sheds light on how the dominant society defined acceptable codes of masculinity and how it treated men who violated these codes. Lane's 1839 autobiography The Wandering Boy warrants analysis not only as a historical document illuminating his life but also as a personal narrative interpreting that life. This essay situates Lane's text in the context of memoirs by other ex-sailors, convicts, and alcoholics and suggests resonances among these seemingly disparate narratives. Discussion of The Wandering Boy also offers another perspective from which to view antebellum slave narratives and the evangelical reform literature to "uplift" different groups of men, including alcoholic seamen. Another major goal of this essay is to contribute to several areas of scholarship, including the historiographies of antebellum reform and seafaring life, the burgeoning scholarship on nineteenth-century manhood, and both literary and historical analyses of the autobiographies of nonprivileged people in the early republic.
"A Melancholy and Trying Season": Cholera and the Conflict over Cultural Boundaries in Early Michigan
Authors: Schwartz James Z
Published: March 2006

The article examines two cholera epidemics that struck Michigan in the early 1830s, arguing that the conflict generated by these crises reveals underlying social tensions between one frontier city and its rural hinterlands. Building on Charles Rosenberg's classic The Cholera Years, it contends that his study underestimates the ferocity of the debate over how cholera spread in 1832 and the conflict that uncertainty generated. In Michigan, unlike the East, a furious dispute raged over the etiology of cholera, with newspapers in the countryside insisting that the disease was contagious and those in Detroit contending that the malady did not spread through human contact. Such disagreements produced different strategies for combating cholera. Although Detroiters shunned quarantines, their counterparts in the countryside quickly established these artificial borders to protect themselves from an urban pestilence associated with poverty, crime, and disorder. Tensions exploded into violence in the summer of 1832, when Ypsilanti officials shot at two stagecoaches allegedly seeking to violate the town's quarantine; the incident transformed the conflict over cholera from a regional into a partisan political battle, with Democrats defending and Whigs attacking the individuals who fired at the travelers. In examining such questions, the essay demonstrates the vital role that those living in the emerging West assigned to defending cultural and regional boundaries and suggests that tensions along cultural borders may have played a more important role in frontier communities than historians have been able to appreciate. Although historians recently have produced a growing body of work on national and cultural borders, they have not focused as much attention on less clearly defined boundaries, such as those separating cities from the countryside. Examining such barriers, particularly in western locations, may prove fruitful in the future.
Reconsidering the Abolitionists in an Age of Fundamentalist Politics
Authors: Stewart James Brewer
Published: March 2006

This essay addresses two problems. The first is the political impact of the abolitionist movement (or reputed lack thereof) on the collapse and realignment of parties within the free states that preceded the Civil War. The second is the political claims made by contemporary right wing fundamentalists that the abolitionist movement supplies them with religious, moral, and historical precedents for their political activism today. What puts these problems together on a common ground is centrality of religious activism in defining American politics. This essay, therefore, urges above all, that political historians take religion extremely seriously. The burden of the essay's specific argument is to link the evolution of abolitionist activism to the evolution of the Whig Party in the free states, 1840-1856, arguing that the history of the former is central to understanding the history of the latter. In the process of developing these claims, the essay also contests vigorously contemporary right wing assertions that abolitionism is the moral and spiritual progenitor of today's "pro-life" and "family values" crusades.
Influence of Sample Type and Storage Conditions on Soluble CD40 Ligand Assessment
Authors: Weber Michael , Rabenau Birgitt , Stanisch Michael , Elsaesser Albrecht , Mitrovic Vesselin , Heeschen Christopher , Hamm Christian
Published: March 2006

Background: Several studies have consistently shown that soluble CD40 ligand (sCD40L) concentrations are increased in patients with acute coronary syndromes and can serve as a biomarker for risk stratification. However, few data are available on preanalytic conditions that impact sCD40L values. Thus, the aim of our prospective study was to evaluate the impact of sampling techniques and storage conditions on sCD40L concentrations.

Methods: We included a total of 30 patients with no, stable, or unstable coronary heart disease. Blood samples were collected in gel-filled tubes without additives, in EDTA-filled tubes, and in citrate-filled tubes and were kept at various storage conditions.

Results: Median (interquartile range) sCD40L values at baseline were higher in serum samples [5.29 (3.89–6.33) μg/L] than in either EDTA plasma [0.78 (0.39–1.12) μg/L; P <0.001] or citrate plasma [0.37 (0.22–0.51) μg/L; P <0.001]. Serum values increased with delayed processing [7.94 (5.97–9.62) μg/L after 1.5 h (P <0.001) vs baseline; 10.55 (7.58–11.55) μg/L after 3 h (P <0.001) vs baseline]. However, after centrifugation, sCD40L values remained stable for all 3 sample types.

Conclusion: Plasma, but not serum, samples are appropriate for sCD40L measurements. In general, preanalytic conditions are critical in the assessment of sCD40L concentrations and thus should be carefully considered for future studies.
Stability constants of technetium(IV) oxalate complexes as a function of ionic strength
Authors: Xia Yuanxian , Hess Nancy J. , Felmy Andrew R.
Published: March 2006

Solvent extraction method was used to determine the stability constants of Tc(IV) with oxalate anions in NaCl solutions ranging in concentration from 0.5 M to 2.0 M. All experiments were conducted in an atmosphere-controlled chamber under Ar atmosphere (<1.0 ppm O2). A reducing agent (hydrazine) was used during extractions to maintain technetium in the tetravalent oxidation state. Independent tests confirmed that the oxidation state of technetium did not change during extractions. The distribution ratio of Tc(IV) between the organic and aqueous phases was found to decrease as the concentration of oxalic acid increased. At the oxalic acid concentrations used in these experiments, the complexes TcO(Ox) and TcO(Ox)22-were found to be the dominant aqueous species. Based on these data, the thermodynamic stability constants of Tc(IV) with oxalate complexes were calculated by the Specific Ion Interaction Theory (SIT).
Efficient preparation of 6-[18F]fluoroveratraldehyde, the precursor of the multi-step synthesis of [18F]FDOPA
Authors: Al-Labadi A. , Zeller K.-P. , Machulla H.-J.
Published: March 2006

As a clinically well established PET tracer, 6-[18F]fluoro-L-dopa is prepared by a multi-step synthesis if [18F]fluoride is to be used for labelling. The [18F] label is introduced in the first step, i.e. 6-[18F]fluoroveratraldehyde is prepared first with yields reported in the literature ranging between 20 and 50%. To obtain higher over-all yields in the synthesis of 6-[18F]fluoro-L-dopa, the 18F incorporation in the first step was optimised by determining the yield dependencies on solvent, concentration of the precursor, temperature and time of the reaction. Thus, the product is formed with a yield of 89 ± 2% (n = 15) when using 20 mg of 6-nitroveratraldehyde in 1 mL DMF at 140 °C within a reaction time of 10 min.
Direct labeling of isoniazid with technetium-99m for diagnosis of tuberculosis
Authors: Roohi Samina , Mushtaq A. , Jehangir M. , Malik Salman A.
Published: March 2006

Isonicotinic acid hydrazide (isoniazid) is one of the most effective agents in tuberculosis therapy. Hence it was chosen as ligand for99mTc labeling and imaging in the developed animal model with a gamma camera. Direct labeling of isoniazid with technetium-99m was studied. Factors affecting the radiolabeling efficiency such as amount of reducing agent, pH and time of the reaction were studied. Biodistribution of the labeled compound was performed in Sprague–Dawley rats. The localization kinetics of the radiolabeled complex was also studied in the developed animal model by injecting 100–125 MBq99mTc-isoniazid intravenously in the ear of rabbit and the images were taken with a gamma camera. Optimum conditions gave > 98% labeling efficiency of99mTc-isoniazid. Biodistribution studies in rats revealed that the maximum uptake was in kidneys (15%, 8% and 2.5% at 0.5, 4 and 24 hours, respectively), indicating renal excretion of the99mTc-isoniazid. High accumulation was obtained in liver (10%, 11% and 4% at 0.5, 4 and 24 hours, respectively) and significant radioactivity was also seen in the intestines (8%, 6% and 1% at 0.5, 4 and 24 hours, respectively), indicating hepatobiliary excretion of the complex. Less than 2% uptake in stomach until 24 hours confirmed goodin vivostability of the complex.99mTc-isoniazid initially accumulated in infective lesions ofS. aureusin rabbits due to hyper-vascularity, but because of its non specificity forS. aureusthe residency of99mTc-isoniazid was low and it showed rapid wash out from the lesion, whereas residency of tubercular lesion was high and it remained in the tubercular lesion in the delayed images also. The results suggest that99mTc-isoniazid is a specific agent for localization of tubercular lesions.
Assessment of air quality of two metropolitan cities in Pakistan: Elemental analysis using INAA and AAS
Authors: Waheed Shahida , Rahman A. , Khalid N. , Ahmad Shujaat
Published: March 2006

For the assessment of air quality of two cities in Pakistan, Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectrometry (AAS) have been used. In all 26 elements were determined in suspended particulate matter (SPM) and soil samples. The SPM levels from different locations of Rawalpindi and Lahore indicate unhealthy to hazardous air quality much above the World Health Organization (WHO) guidelines. Metrological conditions and nature of soil that contains clay components mainly contribute to the inventory of the SPM elements of these cities. The calculated enrichment factors (EF) also indicate the dominance of the soil components. Contributions of inorganic elements due to heavy traffic with automotive exhaust and other commercial activities in this area have been identified. Areas of Qurtaba Chowk and Bank Square in Lahore in particular showed high EF for lead depicting burning of the automotive fuel and road dust. The accuracy and precision of the work has been maintained through the concurrent use of IAEA Reference Materials.
Geographical distribution of 90Sr contamination in Poland
Authors: Gaca Pawel , Skwarzec Bogdan , Mietelski Jerzy W.
Published: March 2006

The paper presents results on determination of 90Sr in bilberry and cowberry leaves (Vaccinium myrtillus and Vaccinium vitis-idaea) and the use of these plants as bio-monitors of radiostrontium contamination in Poland. Radiostrontium was determined by mean of liquid scintillation spectrometry preceded by radiochemical separation using Sr-resin and 85Sr tracer. The approximate map of 90Sr contamination of Poland is presented. The activity ratio between 90Sr and obtained earlier data for 137Cs in the same samples is discussed. The enhancement of radiostrontium content observed in northeastern Poland seems to be the trace of hot-particles fallout from initial Chernobyl cloud, which passed over Polish territory toward Scandinavia.
Childhood Learning and the Distribution of Knowledge in Foraging Societies
Authors: Keith Kathryn
Published: March 2006

A differential distribution of knowledge is characteristic of all human societies, and in relatively egalitarian foraging societies, in which age and gender tend to structure the few distinct social roles available, the distribution of cultural knowledge is also expected to occur along these lines. In this chapter, I consider the relationship between child‐rearing practices and the distribution of cultural knowledge across social roles. In particular, I look at gendered patterns of knowledge and decision‐making, drawing upon foraging societies in three different environmental zones as case studies for comparison: the !Kung San of the Kalahari Desert, the Aka Pygmies of the central African forests, and the Utku and Nunamiut Eskimo of northern Alaska and Canada. Child‐rearing practices vary among the three groups considered here and are found to relate to the distribution of knowledge and skills across gender roles. This, in turn, may be among the factors influencing group decision‐making patterns.