bluuebunny/crossref_metadata_2025 huggingface dataset:
(S,S)-Formoterol Increases the Production of IL-4 in Mast Cells and the Airways of a Murine Asthma Model
Authors: Abraha Daniel , Cho Seong H. , Agrawal Devendra K. , Park Jae M. , Oh Chad K.
Published: March 2004

Background: Racemic formoterol is an equimolar mixture of (R,R)- and (S,S)-formoterol. Several studies have shown (S,S)-formoterol to have proinflammatory effects. We previously reported that (S)-albuterol increased the secretion of histamine and interleukin (IL)-4 in murine mast cells. We thus hypothesized that (S,S)-formoterol promotes asthma by enhancing IL-4 production in mast cells of the asthmatic airway. Methods: Murine and human mast cells were stimulated by high affinity IgE receptor (FcΕRI) cross-linking or with phorbol myristate acetate/calcium ionophore A23187 (PMA/A23187). Jurkat T cells were stimulated with PMA. Cells were pretreated with either (R,R)- or (S,S)-formoterol. Ovalbumin (OVA)-sensitized BALB/c mice were pretreated with (R,R)- or (S,S)-formoterol before each intranasal OVA challenge for 10 days. Bronchoalveolar lavage fluid was obtained from the mice. The levels of IL-4, histamine and PGD2 were measured. Early and late allergic responses (EAR and LAR, respectively) to OVA challenge and airway hyperresponsiveness (AHR) were measured. Results: (S,S)-formoterol enhanced the production of IL-4, histamine, and PGD2 in mast cells, whereas (R,R)-formoterol had no effect. Neither (S,S)- nor (R,R)-formoterol had effect on IL-4 production in Jurkat T cells. In OVA-challenged mice, (S,S)-formoterol increased IL-4 secretion, whereas (R,R)-formoterol had no effect. Finally, (S,S)-formoterol enhanced the inflammatory changes in the peribronchial and perivascular areas without affecting EAR, LAR or AHR, whereas (R,R)-formoterol reduced EAR, LAR and AHR as well as cellular infiltration in the lung tissue of these mice. Conclusion: (S,S)-formoterol may exert adverse effects in asthma control by activating mast cells to produce proinflammatory mediators such as IL-4.
Aldosterone Antagonism Ameliorates Proteinuria and Nephrosclerosis Independent of Glomerular Dynamics in L-NAME/SHR Model
Authors: Zhou Xiaoyan , Ono Hidehiko , Ono Yuko , Frohlich Edward D.
Published: March 2004

Background: The renin-angiotensin-aldosterone system participates importantly in the progression of hypertensive renal disease. Angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists have been demonstrated to afford renoprotection in L-NAME-exacerbated nephrosclerosis in SHR rats. This study was designed to examine the effects of the aldosterone antagonist eplerenone on systemic and renal hemodynamics, glomerular dynamics, renal function and histopathology in L-NAME/SHR, and determine whether aldosterone antagonism would enhance the effectiveness of ACE inhibition. Methods: Six groups of 20-week-old SHR were studied using renal micropuncture and histopathological techniques after 3 weeks of treatment: SHR control (tapwater, n = 10); SHR + eplerenone (101 ± 8.3 mg/kg/day, n = 10); SHR + L-NAME (5.0 ± 0.12 mg/kg/day, n = 9); SHR + L-NAME + eplerenone (n = 8); SHR + L-NAME + lisinopril (3 mg/kg/day, n = 9), and SHR + L-NAME + eplerenone + lisinopril (n = 9). Results:L-NAME-treated SHR developed massive proteinuria, severe hypertensive nephrosclerosis, and tubulointerstitial damage. Eplerenone significantly reduced proteinuria (127.4 ± 26.5 vs. 51.9 ± 16.7 mg/24 h, p < 0.01), improved glomerular and arteriolar injuries (65 ± 9 vs. 29 ± 9 score/100 glomeruli, p < 0.01; 116 ± 18 vs. 41 ± 13 score/100 arterioles, p < 0.01, respectively), and decreased tubulointerstitial damage index (1.43 ± 0.07 vs. 0.39 ± 0.07, p < 0.01) without altering mean arterial pressure or glomerular dynamics. Combined therapy of eplerenone with lisinopril produced no further benefits than lisinopril alone. Conclusion: The aldosterone antagonist eplerenone significantly ameliorated proteinuria and nephrosclerosis in the L-NAME/SHR model, independent of hemodynamic effects.
Effects of Conjugated Equine Estrogenand Medroxyprogesterone Acetate on Lipoprotein(a) and Other Lipoproteins in Japanese Postmenopausal Women with and without Dyslipidemia
Authors: Sumino Hiroyuki , Ichikawa Shuichi , Sakamoto Hironosuke , Sawada Yoshie , Kumakura Hisao , Takayama Yoshiaki , Sakamaki Tetsuo , Kurabayashi Masahiko
Published: March 2004

Background/Aim: The cardiovascular effects of postmenopausal hormone replacement are controversially discussed. We investigated the effects of 12 months of treatment with conjugated equine estrogen and medroxyprogesterone acetate on lipoprotein(a) [Lp(a)] and other lipoproteins in Japanese postmenopausal women (PMW) with and without dyslipidemia. Methods: Forty-three normolipidemic and 17 dyslipidemic PMW [total cholesterol (TC) ≧220 mg/dl or triglyceride (TG) ≧150 mg/dl] received conjugated equine estrogen (0.625 mg) plus medroxyprogesterone acetate (2.5 mg) daily for 12 months, and the results were compared with those of 26 normolipidemic and 14 dyslipidemic subjects declining this treatment as controls. The fasting serum levels of Lp(a), TC, TG, high-density lipoprotein cholesterol, low- density lipoprotein cholesterol, apolipoprotein (Apo) AI, Apo AII, Apo B, Apo CII, and Apo E were measured in each subject at baseline and 12 months after this treatment initiation. Results: The treatment decreased Lp(a) similarly in normolipidemic and dyslipidemic PMW and decreased TC, low-density lipoprotein cholesterol, Apo CII, and Apo E and increased high-density lipoprotein cholesterol, Apo AI, and Apo AII in both groups. The therapy also significantly increased TG in normolipidemic but not dyslipidemic subjects. In controls, the levels of Lp(a) and other lipoproteins were unaltered. Conclusions: In PMW with or without dyslipidemia, improvement in Lp(a) and other lipoproteins may represent cardiovascular benefits of hormone replacement therapy. However, an elevation of the TG levels seen with the therapy warrants caution, especially in PMW without dyslipidemia.
Growth and Metabolic Control during Puberty in Girls with X-Linked Hypophosphataemic Rickets
Authors: Sochett Etienne , Doria Andrea S. , Henriques Flavia , Kooh Sang Whay , Daneman Alan , Mäkitie Outi
Published: March 2004

Objective: X-linked hypophosphataemic rickets (XLH) results in defective bone mineralization and impaired growth. Treatment with oral phosphate (Pi) and calcitriol improves but does not normalize growth. This study assessed whether pubertal growth and metabolic control contribute to the height deficit. Methods: Study included patients with XLH who were treated with Pi-calcitriol from diagnosis to adult height; their hospital records, biochemistry and radiographs were reviewed. Results: Six females with XLH were included. Their mean peak height velocity and total height gain during puberty were nearly normal despite deteriorating metabolic control. Conclusions: In treated girls with XLH, the pubertal growth is nearly normal despite suboptimal metabolic control. The major height loss occurs prior to puberty and is not recovered during the pubertal growth spurt.
Chemie und Biologie von Terpentrilactonen ausGinkgo biloba
Authors: Strømgaard Kristian , Nakanishi Koji
Published: March 2004

Ginkgo biloba– der Ginkgobaum – ist die älteste lebende Baumart der Welt. Ginkgo‐Präparate sind ein wichtiger Bestandteil in der traditionellen chinesischen Medizin, und in den letzten Jahren haben die Blattextrakte als Phytopräparat in Europa und als Nahrungsergänzungsmittel weltweit breiten Absatz gefunden. Zu den postulierten Wirkungen desGinkgo‐biloba‐Extrakts gehören die Verbesserung der Gedächtnisleistung, die Steigerung der Blutzirkulation und eine Verzögerung der Alzheimer‐Demenz. Was den Extrakt so einzigartig macht, sind die Terpentrilactone – Ginkgolide und Bilobalid –, die als strukturell komplexe Moleküle attraktive Zielstrukturen für Totalsynthesen waren. Es wird angenommen, dass Terpentrilactone für die neuroregulatorischen Eigenschaften derGinkgo‐biloba‐Extrakte mit ausschlaggebend sind. Eine Reihe biologischer Wirkungen der in den letzten Jahren entdeckten Terpentrilactone macht diese zu aussichtsreichen pharmakologischen Substanzen.
Nanokatalyse: alter Wein in neuen Schläuchen oder etwas wirklich Neues?
Authors: Schlögl Robert , Abd Hamid Sharifah Bee
Published: March 2004

Das Nanofieber hat die Forschung über heterogene Katalysatoren erreicht. Begreift man Nanokatalyse als einen Paradigmenwechsel in der Katalysatorherstellung hin zur Synthese von Katalysatoren mit auf mehreren Größenskalen kontrollierten Eigenschaften, so ergibt sich folgender Ansatz: Die Struktur lässt sich durch einen Aufbau des Katalysators als anorganisches Polymer kontrollieren. Primäre, sekundäre und tertiäre Struktur des Polymers entsprechen molekularen Baueinheiten und deren Verknüpfungen, der Defektstruktur des Festkörpers bzw. der Teilchenmorphologie. Hochdurchsatzexperimente zur Optimierung der Syntheseparameter, die von in situ erhaltenen analytischen Daten der Herstellprozesse geführt werden, sind ein Weg zu Katalysatoren, welche die hohen Erwartungen, die sich mit dem Prädikat “nano” verbinden, erfüllen können.
Infrared Spectra of Indium Hydrides in Solid Hydrogen and of Solid Indane
Authors: Andrews Lester , Wang Xuefeng
Published: March 2004

Bei Reaktionen laserabgelöster Indiumatome mit Wasserstoff beobachtet man scharfe IR‐Absorptionsbanden von InH‐Intermediaten. Die Einstrahlung bei 193 nm begünstigt die Weiterreaktion zu monomerem Indan (InH3). Beim Tempern konnte zunächst die Existenz von In2H6 bestätigt werden, bevor die scharfen Banden durch eine breite IR‐Bande um 1460 cm−1 ersetzt wurden, die festem Indan (InH3)n zugeordnet wurde (siehe Gleichung).${\vcenter{\openup.5em\halign{$#$\cr {\rm InH}_{3}\rightarrow {1\over 2}{\rm In}_{2}{\rm H}_{6}\rightarrow {1\over n}({\rm InH}_{3})_{n}\hfill\cr}}}$
Titelbild: Chemie und Biologie von Terpentrilactonen aus Ginkgo biloba (Angew. Chem. 13/2004)
Authors: Strømgaard Kristian , Nakanishi Koji
Published: March 2004

Terpentrilactone aus dem Ginkgobaum (Ginkgo biloba) sind wohl zumindest teilweise für die neuromodulatorischen Effekte von G.‐biloba‐Extrakten ausschlaggebend. Das Titelbild zeigt einen jungen Ginkgobaum mit seinen charakteristischen fächerförmigen Blättern, der einem menschlichen Gehirn entwächst, zusammen mit den Molekülstrukturen von Bilobalid und Ginkgolid B. K. Strømgaard und K. Nakanishi fassen im Aufsatz auf S. 1670 ff. den aktuellen Stand der Ginkgolid‐Forschung mit dem Schwerpunkt auf biologischen und Synthesestudien zusammen.
Nanocatalysis: Mature Science Revisited or Something Really New?
Authors: Schlögl Robert , Abd Hamid Sharifah Bee
Published: March 2004

“Nanomania” has reached the area of heterogeneous catalysis. Nanosized catalyst constituents are important for functions that require structural control over several scales of dimension. Nanocatalysis may be understood as a redefinition of catalyst synthesis: multidimensional structural control is exerted by considering catalysts as inorganic polymers rather than as close‐packed crystals. Primary, secondary, and tertiary structural hierarchies translate into molecular building blocks and linkers, the defect structure of crystals, and particle morphology. High‐throughput techniques and in situ synthetic analysis are the tools required to arrive at better defined catalytic materials that can fulfil the high expectations created by the incorporation of catalysts into the “nano” research field.
Cover Picture: Chemistry and Biology of Terpene Trilactones from Ginkgo Biloba (Angew. Chem. Int. Ed. 13/2004)
Authors: Strømgaard Kristian , Nakanishi Koji
Published: March 2004

Terpene trilactones from the ginkgo tree (Ginkgo biloba) are at least partly responsible for the neuromodulatory effects of G. biloba extracts. The cover picture shows a young ginkgo tree, with its characteristic fan‐shaped leaves, growing out of a human brain. Superimposed are the X‐ray crystal structures of bilobalide and ginkgolide B. K. Strømgaard and K. Nakanishi discuss the current status of bilobalide and ginkgolides in their Review on page 1640 ff., with a particular focus on chemical and biological studies.
Novel Reaction Products from Thiobarbituric Acid of Biological Interest
Authors: Aly Ashraf A. , Mourad Aboul‐Fetouh E. , Hassan Alaa A. , Mohamed Nasr K. , Ali Bahaa A. , El‐Sayed Mohamed M.
Published: March 2004

The reactions of 1, 2‐dihydro‐2‐thioxo‐4, 6(1H, 5H)pyrimidinedione (1) with some π‐deficients have led to the formation of unexpected heterocyclic products such as anilinomethylenethioxopyrimidinedione, 2, 2'‐bis(pyrimidinecarbothioamide), allylthioxopyrimidinecarbothioamide, indenopyranopyrimidine and benzofuropyrimidine derivatives. A possible mechanism for the formation of these products is discussed, and the biological activity is determined.
Synthesis and Antimicrobial Evaluation of Some Novel Cholestane Heterocyclic Derivatives
Authors: Elmegeed Gamal A. , Wardakhan Wagnat W. , Younis Magdi , Louca Nadia A.
Published: March 2004

This study was performed to investigate the reactivity of 5α‐cholestan‐3‐one (1) towards various chemical reagents to produce new steroidal heterocyclic derivatives. The aminothieno[2, 3:2, 3]cholestane derivative 2 was synthesized according to Gewald's conditions. The diazonium salt of compound 2 coupled with malononitrile to afford dicyanomethylenhydrazinothieno[2′, 3′:2, 3]cholestane derivative 5. The behavior of compound 5 towards nitrogen nucleophiles and several active methylene reagents was investigated. Additionally, a variety of steroidal heterocyclic derivatives like compounds 15a, b‐22a, b were synthesized starting with 5α‐cholestan‐3‐one (1). The structures of the compounds were established based on the analytical and spectral data. The in vitro antimicrobial activity of some newly synthesized compounds against bacteria and fungi was studied.
Antiaggregating and Antithrombotic Activities of new 1, 2, 3‐Triazolecarboxamides
Authors: Cwiklicki Anke , Rehse Klaus
Published: March 2004

Twenty five new triazolecarboxamides related to YC‐1 were prepared and tested for their antiplatelet (in vitro) and antithrombotic (in vivo) activities. Five of them inhibited the aggregation of blood platelets (Born test, inducer collagen) with IC50 values between 90 and 130 μM. Nine compounds exhibited significant antithrombotic properties with an inhibition of thrombus formation between 11 and 7%. Only one compound (8c) showed both, in vitro and in vivo effects. In vitro, the most active compounds were 11c and 12d. They inhibit platelet aggregation with IC50 = 90 and 95 μM. In vivo, 10a showed the strongest inhibition of thrombus formation with 11% in arterioles (5% in venules) after a single oral dose of 60 mg/kg. With serotonin as inducer both, 11c and 12d, showed lower IC50 values namely 25 or 30 μM, respectively. Additional antiplatelet activities were found for 11c against adrenaline (IC50 = 25 μM) and for 12d against platelet activating factor (PAF) (IC50 = 15 μM) as inducer.
Hypoglycemia induced changes in cell death and cell proliferation in the organogenesis stage embryonic mouse heart
Authors: Ghatnekar Gautam S. , Barnes Jill A. , Dow Janet L. , Smoak Ida W.
Published: March 2004

BACKGROUND

Hypoglycemia is a side effect of diabetes therapy and causes abnormal heart development. Embryonic heart cells are largely resistant to teratogen‐induced apoptosis.

METHODS

Hypoglycemia was tested for effects on cell death and cell proliferation in embryonic heart cells by exposing mouse embryos on embryonic day (E) 9.5 (plug = E0.5) to hypoglycemia (30–50 mg/dl glucose) in vivo or in vitro for 24 hr. Long‐term effects of in vivo exposure on conceptus viability were evaluated at E18.5. Cell death was evaluated on E10.5 by: 1) two TUNEL assays in sectioned embryos to demonstrate DNA fragmentation; 2) confocal microscopy in whole embryos stained with Lysotracker; 3) flow cytometry in dispersed heart cells stained for TUNEL and myosin heavy chain (MHC) to quantify and characterize cell type susceptibility; and 4) immunohistochemistry (IHC) and Western analysis in sectioned embryos to evaluate potential involvement of caspase‐3 active subunit and p53. Effects on cell proliferation were evaluated by IHC and Western analysis of proliferating cell nuclear antigen (PCNA).

RESULTS

In vivo hypoglycemic exposure on E9.5 reduced viability in conceptuses examined on E18.5. Hearts examined on E10.5 demonstrated increased TUNEL and Lysotracker staining. In hearts of embryos exposed to hypoglycemia, flow cytometry demonstrated increased TUNEL‐positive cells and cells dual‐labeled for TUNEL and MHC. Protein expression of caspase‐3 active subunit and p53 was increased and PCNA was markedly reduced in hearts of embryos exposed to hypoglycemia.

CONCLUSIONS

Hypoglycemia reduces embryonic viability, induces significant cell death, and reduces cell proliferation in the E9.5 mouse heart, and these processes may involve active caspase‐3 and p53. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.
Evidence that the risk of spina bifida is influenced by genetic variation at the NOS3 locus
Authors: Brown Karen S. , Cook Michelle , Hoess Katy , Whitehead Alexander S. , Mitchell Laura E.
Published: March 2004

BACKGROUND:

There is substantial evidence that the risk of spina bifida, a malformation of the caudal neural tube, may be associated with maternal or embryonic disturbances in the folate–homocysteine metabolic axis. Hence, variants of genes that influence this pathway represent an intriguing group of candidate genes for spina bifida and other neural tube defects (NTD). A common variant of the gene for endothelial nitric oxide synthase (NOS3 G894T) was recently added to this group of NTD candidate genes, based on a report demonstrating that homozygosity for the T allele of this variant is associated with increased homocysteine levels in normal adult populations.

METHODS:

The association between the risk of spina bifida and both the maternal and embryonic genotype for the NOS3 G894T variant was evaluated in data from 301 families by using the transmission disequilibrium test (TDT) and log‐linear modeling.

RESULTS:

Analyses of these data using the TDT provided no evidence that the risk of spina bifida was significantly related to either the maternal or embryonic NOS3 genotype. However, the log‐linear analyses indicated that the risk of spina bifida was significantly associated with the embryonic, but not the maternal, genotype for the NOS3 G894T variant.

CONCLUSIONS:

The results of the present analyses suggest that the embryonic NOS3 G894T genotype is associated with the risk of spina bifida. Moreover, these analyses highlight the importance of a detailed examination of the study data. Had these analyses been restricted to the methodologically simpler TDT, the association between the NOS3 G894T genotype and risk of spina bifida may well have been overlooked. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.
Excess birth prevalence of Hypoplastic Left Heart syndrome in eastern Wisconsin for birth cohorts 1997–1999
Authors: Cronk Christine E. , Pelech Andrew N. , Malloy Marsha E. , McCarver D. Gail
Published: March 2004

BACKGROUND

Hypoplastic Left Heart syndrome (HLHS) is a group of cardiac malformations involving underdevelopment of the left heart with an inability to maintain systemic circulation. Because of a clinical impression of excess HLHS prevalence, we completed a medical record review of cases born from 1997 through 1999 who were Wisconsin residents and seen at the Children's Hospital of Wisconsin (CHW).

METHODS

Cases were identified either in the CHW medical records database or the Division of Pediatric Cardiology database and confirmed by echocardiogram, catheterization, surgery, or autopsy. U.S. and international surveillance systems were used to estimate population risk. Rates per 10,000 births were computed for eastern Wisconsin and four regions within this portion of the state, and compared to the estimated population risk. The same methods were used to evaluate whether rates for tetralogy of Fallot and transposition of the great arteries were elevated.

RESULTS

A total of 61 cases were ascertained yielding a birth prevalence of 3.7 per 10,000 births, which was greater than the estimated population risk of 2.79. The rate for the southeast region also exceeded the expected rate. The most urban and industrialized areas had the highest rates. Rates for the other two diagnoses evaluated were not different from estimated population risks.

CONCLUSIONS

Eastern Wisconsin, particularly the urban southeast region, had elevated rates of HLHS. Because of the geographic clustering of high rates, environmental factors may be associated with this finding. Birth Defects Research (Part A) 70:114–120, 2004. © 2004 Wiley‐Liss, Inc.
Determination of organochlorine compounds in human biological samples by GC‐MS/MS
Authors: Frías Mercedes Moreno , Torres Margarita Jiménez , Frenich Antonia Garrido , Martínez Vidal Jose Luis , Olea‐Serrano Fátima , Olea Nicolás
Published: March 2004

A study was undertaken to determine the extent of organochlorine pesticide (OP) and polychlorinated biphenyl (PCB) contamination in infant formula milk and in the human milk, fat and serum of women from an agricultural area in Southern Spain. A procedure is proposed that simultaneously detects trace levels of lindane, endosulfan‐ether, vinclozolin, aldrin, endosulfan‐lactone, endosulfan‐alpha, 4,4′DDE, 2,4′DDT, endosulfan‐beta, 4,4′DDT, kepone, endosulfate‐sulfate, methoxychlor, mirex, 2,3,4 PCB, 2,2′,4,5 PCB, 2,3,4,5 PCB and 2,2′,3,3′,6,6′PCB. After liquid–liquid or solid–liquid extraction, the extract of the sample was cleaned by high performance liquid chromatography (HPLC) and the ﬁrst eluted fraction was analysed by gas chromatography (GC) with mass spectrometry (MS) detector in tandem mode. To evaluate the validity of the method the following parameters were studied: linearity, detection limits, quantiﬁcation limits, speciﬁcity, percentage recovery and precision. A study of the uncertainty associated with the analytical method was also carried out. Copyright © 2003 John Wiley & Sons, Ltd.
Quantifying and handling errors in instrumental measurements using the measurement error theory
Authors: Andersen C. M. , Bro R. , Brockhoff P. B.
Published: March 2004

Measurement error modelling is used for investigating the influence of measurement/sampling error on univariate predictions of water content and water‐holding capacity (reference measurement) from nuclear magnetic resonance (NMR) relaxations (instrumental) measured on two gadoid fish species. This is a new way of using the measurement error theory. Reliability ratios illustrate that the models for the two fish species are influenced differently by the error. However, the error seems to influence the predictions of the two reference measures in the same way. The effect of using replicated x‐measurements is illustrated by simulated data and by NMR relaxations measured several times on each fish. The standard error of the physical determination of the reference values is lower than the standard error of the NMR measurements. In this case, lower prediction error is obtained by replicating the instrumental measurements. A new general formula is given for how to correct the least squares regression coefficient when a different number of replicated x‐measurements is used for prediction than for calibration. It is shown that the correction should be applied when the number of replicates in prediction is less than the number in calibration. This can be relevant for on‐line applications and in other situations where it is important to make fast measurements in the prediction phase. Copyright © 2004 John Wiley & Sons, Ltd.
Nanostructured Polyaniline Sensors
Authors: Huang Jiaxing , Virji Shabnam , Weiller Bruce H. , Kaner Richard B.
Published: March 2004

The conjugated polymer polyaniline is a promising material for sensors, since its conductivity is highly sensitive to chemical vapors. Nanofibers of polyaniline are found to have superior performance relative to conventional materials due to their much greater exposed surface area. A template‐free chemical synthesis is described that produces uniform polyaniline nanofibers with diameters below 100 nm. The interfacial polymerization can be readily scaled to make gram quantities. Resistive‐type sensors made from undoped or doped polyaniline nanofibers outperform conventional polyaniline on exposure to acid or base vapors, respectively. The nanofibers show essentially no thickness dependence to their sensitivity.
Diaroyl(methanato)boron Difluoride Compounds as Medium‐Sensitive Two‐Photon Fluorescent Probes
Authors: Cogné‐Laage Emmanuelle , Allemand Jean‐François , Ruel Odile , Baudin Jean‐Bernard , Croquette Vincent , Blanchard‐Desce Mireille , Jullien Ludovic
Published: March 2004

This paper evaluates the use of diaroyl(methanato)boron difluoride compounds for designing efficient fluorescent probes through two‐photon absorption. Three different pathways allowing for the syntheses of symmetrical and dissymmetrical molecules are reported. The stable diaroyl(methanato)boron difluoride derivatives can be easily obtained in good yields. They exhibit a large one‐photon absorption that is easily tuned in the near‐UV range. Their strong fluorescence emission covers the whole visible domain. In addition to these attractive linear properties, several diaroyl(methanato)boron difluoride derivatives possess significant cross sections for two‐photon absorption. The derived structure–property relationships are promising for designing new generations of molecules relying on the diaroyl(methanato)boron difluoride backbone.
Self‐Assembly of Normal Alkanes on the Au (111) Surfaces
Authors: Zhang Hai‐Ming , Xie Zhao‐Xiong , Mao Bing‐Wei , Xu Xin
Published: March 2004

The self‐assembled monolayers (SAMs) of normal alkanes (n−CnH2n+2) with different carbon chain lengths (n=14–38) in the interfaces between alkane solutions (or liquids), and the reconstructed Au (111) surfaces have been systematically studied by means of scanning tunneling microscopy (STM). In contrast to previous studies, which concluded that some n‐alkanes (n=18–26) can not form well‐ordered structures on Au (111) surfaces, we observed SAM formations for all these n‐alkanes without any exceptions. We find that gold reconstruction plays a critical role in the SAM formation. The alkane monolayers adopt a lamellar structure in which the alkane molecules are packed side‐by‐side, to form commensurate structures with respect to the reconstructed Au (111) surfaces. The carbon skeletons are found to lie flat on the surfaces, which is consistent with the infrared spectroscopic studies. Interestingly, we find that two‐dimensional chiral lamellar structures form for alkanes with an even carbon number due to the specific packing of alkane molecules in a tilted lamella. Furthermore, we find that the orientation of alkane molecules deviates from the exact [01$\bar 1$] direction, because of the intermolecular interactions among the terminal methyl groups of neighboring lamellae; this results in differences of molecular orientation between mirror structures of adjacent zigzag alkane lamellae. Structural models have been proposed, that shed new light on monolayer formation.
Synthesis and Properties of para‐Substituted NCN‐Pincer Palladium and Platinum Complexes
Authors: Slagt Martijn Q. , Rodríguez Gema , Grutters Michiel M. P. , Klein Gebbink Robertus J. M. , Klopper Wim , Jenneskens Leonardus W. , Lutz Martin , Spek Anthony L. , van Koten Gerard
Published: March 2004

A variety of para‐substituted NCN‐pincer palladium(II) and platinum(II) complexes [MX(NCN‐Z)] (M=PdII, PtII; X=Cl, Br, I; NCN‐Z=[2,6‐(CH2NMe2)2C6H2‐4‐Z]−; Z=NO2, COOH, SO3H, PO(OEt)2, PO(OH)(OEt), PO(OH)2, CH2OH, SMe, NH2) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water‐soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by 195Pt NMR spectroscopy and DFT calculations. Both the 195Pt chemical shift and the calculated natural population charge on platinum correlate linearly with the σp Hammett substituent constants, and thus the electronic properties of predesigned pincer complexes can be predicted. The σp value for the para‐PtI group itself was determined to be −1.18 in methanol and −0.72 in water/methanol (1/1). Complexes substituted with protic functional groups (CH2OH, COOH) exist as dimers in the solid state due to intermolecular hydrogen‐bonding interactions.
Modification of (1R,2S)‐1,2‐Diphenyl‐2‐aminoethanol for the Highly Enantioselective, Asymmetric Alkylation of N‐Diphenylphosphinoyl Arylimines with Dialkylzinc
Authors: Zhang Hai‐Le , Jiang Fan , Zhang Xiao‐Mei , Cui Xin , Gong Liu‐Zhu , Mi Ai‐Qiao , Jiang Yao‐Zhong , Wu Yun‐Dong
Published: March 2004

Experimental studies on the modification of (1R,2S)‐1,2‐diphenyl‐2‐aminoethanol, which is used to promote the alkylation of N‐diphenylphosphinoyl benzalimine with diethylzinc, revealed that N‐monosubstituted amino alcohols exhibited higher enantioselectivities than their N,N‐disubstituted counterparts and imino alcohols. Application of the optimal chiral ligand 3 c to activate the reaction of N‐diphenylphosphinoyl arylimines with diethylzinc and dibutylzinc resulted in excellent enantiomeric selectivities of up to 98 % ee. The origin of the experimentally observed enantioselectivities was revealed by density functional calculations (B3LYP/6‐31G*) on the transition structures of several model reactions.
Heck Coupling Reaction of Iodobenzene and Styrene Using Supercritical Water in the Absence of a Catalyst
Authors: Zhang Rong , Sato Osamu , Zhao Fengyu , Sato Masahiro , Ikushima Yutaka
Published: March 2004

Heck coupling reaction of iodobenzene and styrene proceeds rapidly and selectively in supercritical water even without any catalyst in the presence of base. Both the choice of base and the reaction conditions had a significant effect on the conversion and the selectivity of the coupling products. The addition of a relatively mild base such as potassium acetate facilitated the cross‐coupling reaction, while the hydrolysis of phenyl halide was favored in the presence of a strong base. The conversion and the yields of coupling products increased with increasing temperature, reaching a maximum at 650 K near the critical temperature of water, and then decreased as the temperature was further increased. Water density had a significant influence on the reaction rate, showing nearly 30 % augmentation with a slight increase in density from 0.45 to 0.56 g cm−3, but had less effect on the product selectivity. Two possibilities of the role of water responsible for the noncatalytic Heck coupling reaction in supercritical water, that is, ion and water‐catalyzed mechanisms have been considered.
Cover Picture: Ginkgolides and Glycine Receptors: A Structure–Activity Relationship Study (Chem. Eur. J. 6/2004)
Authors: Jaracz Stanislav , Nakanishi Koji , Jensen Anders A. , Strømgaard Kristian
Published: March 2004

The cover picture shows the characteristic fan‐shaped leaf from the Ginkgo biloba tree and the blue pentameric assemblies that represent the glycine receptors which are blocked by ginkgolides, the skeleton of which is seen in the background. The first structure–activity relationship study of ginkgolides and glycine receptors is reported in the paper by K. Nakanishi, K. Strømgaard et al. on p. 1507 ff.
Blowup in a three‐dimensional vector model for the Euler equations
Authors: Friedlander Susan , Pavlović Nataša
Published: March 2004

We present a three‐dimensional vector model given in terms of an infinite system of nonlinearly coupled ordinary differential equations. This model has structural similarities with the Euler equations for incompressible, inviscid fluid flows. It mimics certain important properties of the Euler equations, namely, conservation of energy and divergence‐free velocity. It is proven for certain families of initial data that the model system permits local existence in time for initial conditions in Sobolev spaces Hs, s > $5 \over 2$; and blowup occurs in the sense that the H3/2 + ϵ norm becomes unbounded in finite time. © 2004 Wiley Periodicals, Inc.
Oscillation and convergence behaviours exhibited in an ‘unstable’ second‐order digital filter with saturation‐type non‐linearity
Authors: Ling Bingo Wing‐Kuen , Ho Charlotte Yuk‐Fan , Leung Raymond Shing‐Keung , Tam Peter Kwong‐Shun
Published: March 2004

This letter explains the oscillatory behaviours exhibited in a second‐order digital filter with saturation‐type non‐linearity via the Hopf bifurcation theorem. It is shown that depending on the bifurcation parameter, the state variables may converge to zero even when the eigenvalues of the system matrix are outside the unit circle. Copyright © 2004 John Wiley & Sons, Ltd. abstract
Autonomous response of a third‐order digital filter with two's complement arithmetic realized in cascade form
Authors: Ling Bingo Wing‐Kuen , Hung Wai‐Fung , Tam Peter Kwong‐Shun
Published: March 2004

In this letter, results on the autonomous response of a third‐order digital filter with two's complement arithmetic realized as a first‐order subsystem cascaded by a second‐order subsystem are reported. The behaviour of the second‐order subsystem depends on the pole location and the initial condition of the first‐order subsystem, because the transient behaviour is affected by the first‐order subsystem and this transient response can be viewed as an excitation of the original initial state to another state. New results on the set of necessary and sufficient conditions relating the trajectory equations, the behaviours of the symbolic sequences and the sets of the initial conditions are derived. The effects of the pole location and the initial condition of first‐order subsystem on the overall system are discussed. Some interesting differences between the autonomous response of the second‐order subsystem and the response due to the exponentially decaying input are reported. Some simulation results are given to illustrate the analytical results. Copyright © 2004 John Wiley & Sons, Ltd.
On dissipative two‐state quantum cells and cellular networks
Authors: Civalleri Pier Paolo , Gilli Marco
Published: March 2004

Quantum cellular networks are structures composed of two‐state quantum cells in equilibrium with a stationary thermal bath, which interact among themselves in a classical way. It is shown that if system–bath coupling is set up in the representation based on the given states, as done in the literature, or in the energy representation, as the theory assumes under several approximations, different models are obtained for the cell performance, and hence for the dynamics of the whole network. The model based on the state representation could also be derived by a heuristic approach. The final choice should be decided by experiment. Copyright © 2004 John Wiley & Sons, Ltd.
Applying iterative methods to the analysis of VLSI circuits
Authors: Maffezzoni Paolo
Published: March 2004

This letter proposes a method to properly formulate the analysis of VLSI circuits through a set of well‐conditioned equations. This system of equations can then be efficiently solved by means of an iterative solution method. Copyright 2004 © John Wiley & Sons, Ltd.
The role of pdx1 and HNF6 in proliferation and differentiation of endocrine precursors
Authors: Wilding Laura , Gannon Maureen
Published: March 2004

Ex vivo expansion of embryonic stem cells (ES cells) or pancreatic stem cells for insulin delivery to diabetic patients provides potential for the restoration of islet function in these individuals. Understanding the spatial and temporal requirements of crucial factors for endocrine progenitor specification, proliferation, and terminal differentiation remains a major challenge in the field of pancreas development. Here, we provide speculation as to the role of pdx1 and HNF6 in these different stages of pancreatic endocrine cell development. At the time when islets begin to form within the pancreas, the expression patterns of pdx1 and HNF6 diverge, suggesting distinct functions for each of the genes over the course of endocrine cell development. The current body of evidence provides support for a role of both factors in early endocrine specification as well as a requirement for pdx1 in the generation of mature pancreatic endocrine cells. The precise temporal requirement of HNF6 in the production of terminally differentiated endocrine cells remains unclear. Future studies in this area will rely on conditionally manipulatable systems in combination with lineage‐tracing studies for a more accurate assessment of pdx1 and HNF6 function at different stages along the pathway of endocrine cell development. Copyright © 2004 John Wiley & Sons, Ltd.
Current literature in diabetes
Authors:   John Wiley & Sons, Ltd.
Published: March 2004

In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of diabetes/metabolism. Each bibliography is divided into 17 sections: 1 Books, Reviews & Symposia; 2 General; 3 Genetics; 4 Epidemiology; 5 Immunology; 6 Prediction; 7 Prevention; 8 Intervention: a) General; b) Pharmacology; 9 Pathology: a) General; b) Cardiovascular; c) Neurological; d) Renal; 10 Endocrinology & Metabolism; 11 Nutrition; 12 Animal Studies; 13 Techniques. Within each section, articles are listed in alphabetical order with respect to author (6 Weeks journals ‐ Search completed at 21st Jan. 2004)
High‐frequency C‐V characteristics of a buried‐channel MOS capacitor
Authors: Miyake Masayasu
Published: March 2004

This paper discusses the high‐frequency equilibrium‐state capacitance–voltage (C–V) characteristics of a buried‐channel MOS capacitor, that is, a MOS capacitor with a thin p‐type layer at the surface of an n‐type Si substrate. For this device, changing the gate voltage in the negative direction converts the surface p‐type layer from a depletion region into an accumulation region (an inversion region for the n‐type substrate). The high‐frequency characteristics reveal that the capacitance first decreases to a minimum and then saturates after a slight increase. The author discusses the underlying physics of this capacitance minimum, which is a peculiar characteristic of buried‐channel MOS capacitors, based on the general relation between the high‐frequency capacitance and the depletion layer width. The discussion suggests that the origin of this effect is an ac component of the density distribution of holes that follows the high‐frequency signal, even when the total number of holes is unable to track the same signal. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 25–33, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10081
An architecture for realizing a distributed voice conference system over IP networks
Authors: Yamada Hideaki , Oda Toshikane
Published: March 2004

With the rapidly spreading use of IP networks such as intranets and the Internet, there have been efforts to develop voice‐over IP (VoIP) devices and services by utilizing them. In particular, in the commercial user environment, wide use is likely to be made of services with a high added value in which the telephone network function and the IP network connection function are combined by fully utilizing a high‐level user interface provided by an information processing terminal. This paper considers a voice conference service as the value‐added service in which the telephone function terminals on the telephone network and IP network are interconnected. The construction of a system for providing a voice conference service is investigated, considering requirements such as flexibility, scalability, and quality. A method of construction is proposed. The effectiveness of the proposed method is demonstrated by performance evaluation of an experimental system based on the method. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 53–64, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20071
An Alternative Procedure for the Synthesis of [5]‐ and [7]Carbohelicenes
Authors: El Abed Riadh , Ben Hassine Béchir , Genêt Jean‐Pierre , Gorsane Mohamed , Marinetti Angela
Published: March 2004

2‐Bromo[5]helicene derivatives and substituted [7]helicenes have been prepared through a synthetic sequence relying on Heck‐type and photocyclodehydrogenation reactions. This procedure provides a new, versatile and efficient approach to helicene derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Electron‐Transfer Cycloreversion of 2,3‐Diaryloxetanes: Influence of the Substitution and the Photosensitizer on the Regioselectivity
Authors: Izquierdo M. Angeles , Miranda Miguel A.
Published: March 2004

The regioselectivity in the oxidative electron‐transfer cycloreversion (CR) of 2,3‐diaryloxetanes depends on the substitution of the aryl groups and on the nature of the electron‐transfer photosensitizer. The reaction occurs with fragmentation of the C2−C3 and C4−O bonds either in the presence of electron‐releasing substituents in the 3‐aryl groups, or when chloranil is used as photosensitizer. Thus, CR of the methoxy‐substituted derivative trans,trans‐3‐(4‐methoxyphenyl)‐4‐methyl‐2‐phenyloxetane (1b) results in the production of trans‐anethole and benzaldehyde. In this case, the trans‐anethole radical cation has been detected as transient intermediate by means of laser flash photolysis. Likewise, CR of 1a, photosensitized by chloranil, results in the formation of products arising from the trapping of the trans‐β‐methylstyrene radical cation by chloranil‐derived intermediates. The reverse regioselectivity has been previously found in the ET cycloreversion of 4‐methyl‐2,3‐diphenyloxetane (1a) using (thio)pyrylium salts as photosensitizers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Aliphatic (E)‐α,β‐Unsaturated Amides with High Diastereoselectivity from α,β‐Epoxyamides Promoted by SmI2/HMPA
Authors: Concellón José M. , Bardales Eva
Published: March 2004

Synthesis of aliphatic (E)‐α,β‐unsaturated amides 2, in which the C=C bond is di‐ or trisubstituted, is achieved by using samarium diiodide and HMPA. The starting compounds 1 were easily prepared by the reaction of the corresponding lithium or potassium enolates of α‐chloroamides with aldehydes. A mechanism to explain this process is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Captodative Stabilization in Geminally Substituted Allylic Radicals Assessed by Means of the EPR‐Spectral D Parameter of 1,3‐Cyclopentanediyl Triplet Diradicals
Authors: Adam Waldemar , Schulte Claudio M. Ortega
Published: March 2004

The EPR‐spectral zero‐field parameter D of low‐temperature persistent triplet diradicals T was used to assess the electronic substituent effects in EA/ED and ED/ED geminally substituted allylic radicals. From these EPR data, the interaction parameter (ΔS) was calculated for a set of doubly functionalized radicals, which expresses the ability of the unpaired electron to interact either individually with the functional groups or simultaneously in either a synergistic or antagonistic way. We show that the ED/ED combinations interact antagonistically with the odd electron, whereas the R2N/EA and the MeO/EA pairs display a pronounced captodative delocalization. Compared to MeO/EA, the MeS/EA functionalities manifest just an additive effect of the individual substituents. These results are rationalized in terms of appropriate electron‐transfer‐type mesomeric structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Enantiopure 1‐Aryl‐1‐butylamines and 1‐Aryl‐3‐butenylamines by Diastereoselective Addition of Allylzinc Bromide to Imines Derived from (R)‐Phenylglycine Amide
Authors: Dalmolen Jan , van der Sluis Marcel , Nieuwenhuijzen José W. , Meetsma Auke , de Lange Ben , Kaptein Bernard , Kellogg Richard M. , Broxterman Quirinus B.
Published: March 2004

The synthesis of enantiopure 1‐aryl‐1‐butylamines via a highly diastereoselective addition of allylzinc bromide to imines derived from (R)‐phenylglycine amide is reported. These are synthesised by a three‐step procedure, which involves: (a) formation of the chiral imines; (b) asymmetric addition of the allylzinc reagent; (c) removal of the chiral auxiliary by means of a reductive or non‐reductive method. The reductive method provides 1‐aryl‐1‐butylamines whereas the non‐reductive method preserves the double bond to afford 1‐aryl‐3‐butenylamines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Reciprocal Donor Acceptor Selectivity (RDAS) and Paulsen’s Concept of “Match” in Saccharide Coupling
Authors: Fraser‐Reid Bert , López J. Cristóbal , Gómez Ana M. , Uriel Clara
Published: March 2004

Three modes of selectivity — enantio, stereo, and regio — are critically important for efficient organic synthesis. In the sub‐domain of oligosaccharide synthesis, the first is (usually!) irrelevant in view of the chiralities of the reacting partners. The challenge posed by the other two is compounded by the reality that “protecting groups” are the major, if not only, instruments by which control can be exercised. The role that O2 protecting groups play in stereocontrol of coupling reactions was formulated 60 years ago. In this microreview, evidence is presented which shows that O2 protecting groups also exercise regiocontrol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Efficient Synthesis of Structurally Diverse Diazabicycloalkanes: Scaffolds for Modular Dipeptide Mimetics with Tunable Backbone Conformations
Authors: Maison Wolfgang , Grohs Daniel C. , Prenzel Alexander H. G. P.
Published: March 2004

A stereoselective synthesis of new dipeptide mimetics based on a diazabicycloalkane scaffold is reported. The route starts from enantiomerically pure azabicycloalkenes 1 that are bis(hydroxylated) and coupled N‐terminally to a second amino acid. The key step of the reaction sequence is an oxidative cleavage of the resulting dipeptides 5 to give highly functionalised diazabicycloalkanes 6, which can be easily converted into a number of dipeptide mimetics with defined and variable stereochemistry and a number of different amino acid side chains. The backbone dihedral angles within these dipeptide mimetics can be tuned by varying the stereochemistry and the ring sizes of the diazabicycloalkane scaffold. The syntheses of conformationally constrained dipeptide analogues in four to five steps are presented. With the syntheses of dipeptide mimetics 19a−c, suitable linker moieties for conjugation of diazabicycloalkanes to other functional molecules like markers or solid phases are introduced, making these compounds modular dipeptide mimetics that might find applications as modular ligands or as solid‐phase‐attached scaffolds in combinatorial chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)