bluuebunny/crossref_metadata_2025 huggingface dataset:
Occupational Exposure Associated with Reproductive Dysfunction
Authors: Kumar Sunil
Published: March 2004

Occupational Exposure Associated with Reproductive Dysfunction: Sunil Kumar. Reproductive Toxicology and Histochemistry Division, National Institute of Occupational Health, India—Evidence suggestive of harmful effects of occupational exposure on the reproductive system and related outcomes has gradually accumulated in recent decades, and is further compounded by persistent environmental endocrine disruptive chemicals. These chemicals have been found to interfere with the function of the endocrine system, which is responsible for growth, sexual development and many other essential physiological functions. A number of occupations are being reported to be associated with reproductive dysfunction in males as well as in females. Generally, occupations involving the manufacture/or application of some of the persistent chemicals that are not easily degradable as well as bio‐accumulative chemicals, occupations involving intensive exposure to heat and radiation, occupations involving the use of toxic solvents as well as toxic fumes are reported to be associated with reproductive dysfunction. Occupational exposure of males to various persistent chemicals have been reported to have male mediated adverse reproductive outcomes in the form of abortion, reduction in fertility etc. with inconclusive or limited evidence. Nevertheless, there is a need for more well designed studies in order to implicate any individual chemical having such effects as in most occupations workers are exposed to raw, intermediate and finished products and there are also several confounding factors associated with lifestyles responsible for reproductive dysfunction. There is an urgent need to look at indiscriminate use of persistent chemicals especially pesticides and persistent organic pollutants (POP's) as these chemicals enter the food chain also and could be potential for exposure during the critical period of development. It is also necessary to impart information, and to educate about the safe use of these chemicals, as a very sensitive reproduction issue is involved with exposure to these chemicals. Occupational exposures often are higher than environmental exposures, so that epidemiological studies should be conducted on these chemicals, on a priority basis, which are reported to have adverse effects on reproduction in the experimental system.
External Validation of Psychological Job Demands in a Bus Driver Sample
Authors: Gimeno David , Benavides Fernando G. , Mira Miquel , Martínez José Miguel , Benach Joan
Published: March 2004

External Validation of Psychological Job Demands in a Bus Driver Sample: David Gimeno, et al. Occupational Health Research Unit. Department of Health and Experimental Sciences, Universitat Pompeu Fabra, Spain—Psychosocial risk factors have been considered as characteristics of the work environment rather than an individual issue, but their presence in the workplace is usually measured by self‐reported questionnaires, based on worker attitudes. The objective of the study was to compare a self‐reported measure of psychological job demands in a bus driver sample with selected indicators of bus company activity, as external ‘objective’ indicators, in order to assess its external validity. The final sample included 713 drivers in 41 routes. Self‐reported measures of psychosocial work risk factors were obtained by the Job Content Questionnaire (JCQ). Four external indicators were available for each route: passengers, break times, bus incidents, and regulating actions. Spearman's correlation coefficient was estimated to assess the validity. Correlation coefficients showed that self‐reported psychological demands were statistically significant correlated (p<0.05) with two external indicators: bus incidents (rho=0.397), and regulating actions (rho=0.475). Self‐reported psychosocial risk factors have been compared with independent external indicators of the psychosocial work environment, trying to avoid any subject's perception. According to our results, psychological demands measured by the JCQ seem to reflect the actual psychosocial work environment. Other studies are necessary to confirm these results and to assess job control and job social support. This would be another step in improving our knowledge of the quality of measurement of psychosocial risk factors.
Chemistry and Biology of Terpene Trilactones fromGinkgo Biloba
Authors: Strømgaard Kristian , Nakanishi Koji
Published: March 2004

Ginkgo biloba, the ginkgo tree, is the oldest living tree, with a long history of use in traditional Chinese medicine. In recent years, the leaf extracts have been widely sold as phytomedicine in Europe and as a dietary supplement worldwide. Effects ofGinkgo bilobaextracts have been postulated to include improvement of memory, increased blood circulation, as well as beneficial effects to sufferers of Alzheimer's disease. The most unique components of the extracts are the terpene trilactones, that is, ginkgolides and bilobalide. These structurally complex molecules have been attractive targets for total synthesis. Terpene trilactones are believed to be partly responsible for the neuromodulatory properties ofGinkgo bilobaextracts, and several biological effects of the terpene trilactones have been discovered in recent years, making them attractive pharmacological tools that could provide insight into the effects ofGinkgo bilobaextracts.
Synthesis and Biological Testing of Novel Analogues of Sydnone as Potential Antibacterial Agents
Authors: Moustafa Mohamed A. , Nasr Magda N. , Gineinah Magdy M. , Bayoumi Waleed A.
Published: March 2004

Several series of 3‐phenylsydnone derivatives conjugated to well‐known moieties with antibacterial activity were synthesized via several routes. These derivatives include 3‐cyano‐2‐oxopyridine, 2‐amino‐3‐cyanopyridine, 2‐arylidene‐1‐ethylidenehydrazine and 2‐aroyl‐1‐ethylidenehydrazine moieties. Thus, the key intermediate 3‐(4‐acetylphenyl)sydnone (3) was allowed to react with the appropriate aldehyde, ethyl cyanoacetate or malononitrile in presence of excess ammonium acetate in two steps (method 1) or through a one‐pot reaction technique (methods 2 and 3) to give the corresponding sydnone derivatives 5 and 6, respectively. Moreover, condensation of compound 3 with hydrazine hydrate followed by the reaction with the appropriate aldehyde, mono‐ and dicarboxylic acid hydrazide yielded the corresponding sydnone derivatives 8, 9 and 10, respectively. Most of the synthesized compounds were screened for their in vitro antibacterial activity against various pathogenic organisms of both Gram‐positive and Gram‐negative bacteria. The minimum inhibitory concentrations (MICs) were determined using agar dilution method.
Maternal use of acetaminophen and nonsteroidal anti‐inflammatory drugs (NSAIDs), and muscular ventricular septal defects
Authors: Cleves Mario A. , Savell Van H. , Raj Sarika , Zhao Weizhi , Correa Adolfo , Werler Martha M. , Hobbs Charlotte A.
Published: March 2004

BACKGROUND

Muscular ventricular septal defects (mVSDs) are the most common congenital heart defects. Previous studies have suggested maternal use of acetaminophen or nonsteroidal anti‐inflammatory drugs (NSAIDs), and/or fever as risk factors. We evaluated the association between mVSDs and maternal use of acetaminophen or NSAIDs adjusting for fever.

METHODS

Infants with nonsyndromic mVSDs (cases) and without birth defects (controls), with gestational age ≥37 weeks and their mothers were enrolled in the National Birth Defects Prevention Study. Two exposure periods were defined: the first trimester of pregnancy, and one month before pregnancy through delivery. Mothers reporting fever or medication use at least once during either period were considered exposed. Adjusted odds ratios and 95% confidence intervals were estimated independently for each exposure period.

RESULTS

The analysis included 168 cases and 692 controls. Two case groups were evaluated: all mVSD infants (n = 168) (including those with associated minor cardiac defects or noncardiac defects), and infants with isolated mVSDs (n = 133). Mothers of cases were less likely to be African‐American than Caucasian (OR, 0.36; 95% CI, 0.18, 0.73). Approximately equal numbers of case mothers and control mothers (10.4 versus 9.7%, respectively) reported at least one febrile episode during the first trimester. Neither acetaminophen nor NSAID exposure was significantly associated with mVSDs. This was true for both case groups and both exposure periods.

CONCLUSIONS

Significant associations were not detected between the occurrence of mVSDs and maternal use of NSAIDs or acetaminophen adjusting for maternal fever, nor were they detected between maternal fever and mVSDs. Birth Defects Research (Part A), 2004. Published 2004 Wiley‐Liss, Inc.
Changes in sialylation in homozygous Sp2H mouse mutant embryos
Authors: Glogarová Kateřina , Buckiová Daniela
Published: March 2004

BACKGROUND

The splotch (Sp2H), Pax‐3 mutant mice are characterized by neurulation defects, neural crest deficiencies, and altered somitogenesis. A link connecting all morphological abnormalities in the Pax‐3 homozygous embryos is the composition of extracellular matrix and misexpression of cell adhesion molecules. The neural cell adhesion molecule (NCAM) is one of the Pax‐3 target genes. Its adhesive properties depend on the attached polysialic acid (PSA). We have studied whether NCAM sialylation has been affected in the Pax‐3 mutant embryos.

METHODS

Genotyping of embryos was determined using polymerase chain reaction. The periodate‐resorcinol method was used for quantitative determination of sialic acid. Immunoblotting was used to detect sialylated NCAM isoforms and sialic acids on the blot. This antibody was also used to detect PSA‐NCAM spatial expression.

RESULTS

Quantitative determination of sialic acid at days 10.5–13.5 showed decreased sialic acid content in Sp2H homozygotes. The results of both techniques used in evaluating the expression of PSA‐NCAM isoforms in our study indicate that the 180‐kDa isoform is decreased in homozygous Splotch (Sp2H) embryos. Immunohistochemistry showed decreased staining in the neural tube, ganglion VIII, (day 13.5), frontal lobe, olfactory bulb, and neuroblastic retinal cells (day 18.5).

CONCLUSIONS

PSA‐NCAM is present in Sp2H embryos of all genotypes, starting on developmental day 9.5. Sialylation of the 180‐kDa NCAM isoform begins to decrease on day 12.5 in Sp2H homozygotes. Reduced NCAM sialylation could contribute to the decreased migration of cells in the sensory organs. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.
Determination of three compounds in Aloe vera by capillary electrophoresis
Authors: Yang Yifang , Wang Hongmei , Guo Lei , Chen Yi
Published: March 2004

A capillary electrophoretic assay for determining aloe‐emodin (AE), methyl p‐coumarate (MC), and 3,4‐dihydro‐6,8‐dihydroxyl‐[(3s)‐2′‐acetyl‐3′‐hydroxyl‐5′‐methoxy‐benzyl]‐isocoumarin (DDI) in Aloe vera has been developed. Baseline separation was achieved within 15 min using a running buffer of 20 mm borax containing 10% (v/v) acetonitrile at pH 10.5. A linear relationship between the peak area and the concentration of the analytes was found in the ranges 5–500, 10–1000 and 2–1000 µg/mL for AE, MC and DDI, respectively, with correlation coefﬁcients of 0.9992–0.9998. The relative standard deviations of migration time and peak area were within 0.17–0.19 and 1.52–3.37%, respectively. The recoveries of AE, MC and DDI were 105, 102 and 96.4%. The contents of AE, MC and DDI in Aloe vera were measured to be 5.13, 0.768 and 1.30 mg/g, respectively. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of latent structures in linear models
Authors: Höskuldsson Agnar
Published: March 2004

In chemometrics the emphasis is on latent structure models. The latent structure is the part of the data that the modeling task is based upon. This paper addresses some fundamental issues that arise when latent structures are used. The paper consists of three parts. The first part is concerned with defining the latent structure of a linear model. Here the ‘atomic’ parts of the algorithms that generate the latent structure for linear models are analyzed. It is shown how the PLS algorithm fits within this way of presenting the numerical procedures. The second part concerns graphical illustrations, which are useful when studying latent structures. It is shown how loading weight vectors are generated and how they can be interpreted in analyzing the latent structure. It is shown how the covariance can be used to get useful a priori information on the modeling task. Some simple methods are presented for deciding whether a single or multiple latent structures should be used. The last part is about choosing the variables that should be used in the analysis. The traditional procedures for selecting variables to include in the model are presented and the insufficiencies of such approaches are demonstrated. A case study to illustrate the use of CovProc methods is presented. The CovProc methods are discussed and some of their advantages are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Theory of net analyte signal vectors in inverse regression
Authors: Bro Rasmus , Andersen Charlotte M.
Published: March 2004

The net analyte signal and the net analyte signal vector are useful measures in building and optimizing multivariate calibration models. In this paper a theory for their use in inverse regression is developed. The theory of net analyte signal was originally derived from classical least squares in spectral calibration where the responses of all pure analytes and interferents are assumed to be known. However, in chemometrics, inverse calibration models such as partial least squares regression are more abundant and several tools for calculating the net analyte signal in inverse regression models have been proposed. These methods yield different results and most do not provide results that are in accordance with the chosen calibration model. In this paper a thorough development of a calibration‐specific net analyte signal vector is given. This definition turns out to be almost identical to the one recently suggested by Faber (Anal. Chem. 1998; 70: 5108–5110). A required correction of the net analyte signal in situations with negative predicted responses is also discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Is Water Templating Nanoporous Materials?
Authors: Henry Marc , Taulelle Francis , Loiseau Thierry , Beitone Lionel , Férey Gerard
Published: March 2004

(H2O)17, a cluster with pentagonal water arrangements, squeezed in the sodalite cage of the crystal structure MIL‐74 (Zn6Al12P24O96⋅ [N(CH2CH2NH3)3]8⋅(H2O)34), has its oxygen atoms well located by X‐ray powder diffraction. Positioning of hydrogen atoms has been performed by a dynamic partial atomic charges and hardnesses analysis calculation, in which partial charges are recalculated for each hydrogen sub‐network modification. Hydrogen atoms are therefore positioned by energy minimization. A quantitative estimation of the hydrogen bonds energy for each Hbond and for the network in the MIL‐74 nanoporous compound has been obtained. This result allows a discussion of the effect of imprinting the nanoporous structure onto water or alternatively the templating effect of the cluster onto the inorganic framework.
Diorganotin(IV) Derivatives of Substituted Benzohydroxamic Acids with High Antitumor Activity
Authors: Li Qingshan , Guedes da Silva M. Fátima C. , Pombeiro Armando J. L.
Published: March 2004

A series of diorganotin(IV) and dichlorotin(IV) derivatives of 4‐X‐benzohydroxamic acids, [HL1 (X = Cl) or HL2 (X = OCH3)] formulated as [R2SnL2] (R = Me, Et, nBu, Ph or Cl; L = L1 or L2), along with their corresponding mixed‐ligand complexes [R2Sn(L1)(L2)] have been prepared and characterized by FT‐IR, 1H, 13C, and 119Sn NMR spectroscopy, mass spectrometry, elemental analysis, and melting points. In addition, single‐crystal X‐ray diffraction analyses were carried out for [Me2SnL2] (L = L1 or L2), which show coordination structures intermediate between distorted octahedra and bicapped tetrahedra. The hydroxamate ligands are asymmetrically coordinated by the oxygen atoms, the carbonyl oxygen atom is further away from the metal center than the other oxygen atom. The complexes are stable monomeric species; most of them are soluble not only in chlorohydrocarbon solvents, but also in alcohols and hydroalcoholic solutions. In polar solvents, the mixed‐ligand complexes gradually decompose into the corresponding single‐ligand complex couples. The complexes exhibit in vitro antitumor activities (against a series of human tumor cell lines) which, in some cases, are identical to, or even higher than, that of cisplatin. For the dialkyltin complexes, the activity increases with the length of the carbon chain of the alkyl ligand and is higher in the case of the chloro‐substituted benzohydroxamato ligand. The [nBu2Sn(L1)2] complex displays a high in vivo activity against H22 liver and BGC‐823 gastric tumors, and has a relatively low toxicity.
Ligand Design for Alkali‐Metal‐Templated Self‐Assembly of Unique High‐Nuclearity CuII Aggregates with Diverse Coordination Cage Units: Crystal Structures and Properties
Authors: Du Miao , Bu Xian‐He , Guo Ya‐Mei , Ribas Joan
Published: March 2004

The construction of two unique, high‐nuclearity CuII supramolecular aggregates with tetrahedral or octahedral cage units, {(μ3‐Cl)[Li⊂ Cu4(μ‐L1)3]3}(ClO4)8(H2O)4.5 (1) and {[Na2⊂Cu12(μ‐L2)8(μ‐Cl)4](ClO4)8(H2O)10(H3O+)2}∞ (2) by alkali‐metal‐templated (Li+ or Na+) self‐assembly, was achieved by the use of two newly designed carboxylic‐functionalized diazamesocyclic ligands, N,N′‐bis(3‐propionyloxy)‐1,4‐diazacycloheptane (H2L1) or 1,5‐diazacyclooctane‐N,N′‐diacetate acid (H2L2). Complex 1 crystallizes in the trigonal R̄3c space group (a = b = 20.866(3), c = 126.26(4) Å and Z = 12), and 2 in the triclinic P$\bar 1$ space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) Å, α = 99.836(6), β = 95.793(5), γ = 116.124(5)° and Z = 1). By subtle variation of the ligand structures and the alkali‐metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu4 tetrahedral cage units with a Li+ template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu6 polyhedra with a Na+ template. The effects of ligand functionality and alkali metal template ions on the self‐assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.
Multistate/Multifunctional Behaviour of 4′‐Hydroxy‐6‐nitroflavylium: A Write‐Lock/Read/Unlock/Enable‐Erase/Erase Cycle Driven by Light and pH Stimulation
Authors: Moncada Margarida C. , Parola A. Jorge , Lodeiro Carlos , Pina Fernando , Maestri Mauro , Balzani Vincenzo
Published: March 2004

We have investigated the network of reactions observed for the photochromic 4′‐hydroxy‐6‐nitroflavylium compound in aqueous solutions upon pH changes (including pH jump and stopped flow experiments) and light excitation. The changes observed in the NMR and UV/Vis spectra allowed identification of ten different forms in which this compound can be transformed depending on the experimental conditions. Equilibrium and kinetic constants have been determined. Compared with other members of the flavylium family, 4′‐hydroxy‐6‐nitroflavylium is characterized by a large cis→trans isomerization barrier, and a very efficient hydration reaction. These peculiar features allow writing, reading, storing and erasing photonic information on 4′‐hydroxy‐6‐nitroflavylium by a novel cyclic process that involves the following steps: write‐lock/read/unlock/enable‐erase/erase.
Synthesis and Characterization of Dendritic Multichromophores Based on Rylene Dyes for Vectorial Transduction of Excitation Energy
Authors: Weil Tanja , Reuther Erik , Beer Cornelia , Müllen Klaus
Published: March 2004

The synthesis of dendritic multichromophores based on a rigid polyphenylene scaffold is presented. Different rylene chromophores are incorporated into the core, the branches, and the surface of the dendrimer. In this way, two generations of dendritic dyads consisting of a terrylenediimide core, a stiff polyphenylene scaffold, and a perylenemonoimide periphery were obtained. Furthermore, the first synthetic approach to a dendritic triad is introduced. The outer sphere of this macromolecule is formed by naphthalenemonoimide chromophores, whereas perylenemonoimide groups are located in the dendritic scaffold, and the terrylenediimide chromophore serves as a core molecule. This multichromophore absorbs over the whole range of the visible spectrum and shows well‐separated absorption envelopes. In the course of dendrimer synthesis new attempts towards a straightforward functionalization strategy for rylene dyes are also presented.
Mechanism of the Reaction of the [W3S4H3(dmpe)3]+ Cluster with Acids: Evidence for the Acid‐Promoted Substitution of Coordinated Hydrides and the Effect of the Attacking Species on the Kinetics of Protonation of the Metal‐Hydride Bonds
Authors: Basallote Manuel G. , Feliz Marta , Fernández‐Trujillo M. Jesús , Llusar Rosa , Safont Vicent S. , Uriel Santiago
Published: March 2004

The cluster [W3S4H3(dmpe)3]+ (1) (dmpe=1,2‐bis(dimethylphosphino)ethane) reacts with HX (X=Cl, Br) to form the corresponding [W3S4X3(dmpe)3]+ (2) complexes, but no reaction is observed when 1 is treated with an excess of halide salts. Kinetic studies indicate that the hydride 1 reacts with HX in MeCN and MeCN–H2O mixtures to form 2 in three kinetically distinguishable steps. In the initial step, the WH bonds are attacked by the acid to form an unstable dihydrogen species that releases H2 and yields a coordinatively unsaturated intermediate. This intermediate adds a solvent molecule (second step) and then replaces the coordinated solvent with X− (third step). The kinetic results show that the first step is faster with HCl than with solvated H+. This indicates that the rate of protonation of this metal hydride is determined not only by reorganization of the electron density at the MH bonds but also by breakage of the HX or H+solvent bonds. It also indicates that the latter process can be more important in determining the rate of protonation.
First Preparation of Nanocrystalline Zinc Silicate by Chemical Vapor Synthesis Using an Organometallic Single‐Source Precursor
Authors: Roy A. , Polarz S. , Rabe S. , Rellinghaus B. , Zähres H. , Kruis F. E. , Driess Matthias
Published: March 2004

A method is presented to prepare nanocrystalline α‐Zn2SiO4 with the smallest crystal size reported so far for this system. Our approach combines the advantages of organometallic single‐source precursor routes with aerosol processing techniques. The chemical design of the precursor enables the preferential formation of pure zinc silicates. Since gas‐phase synthesis reduces intermolecular processes, and keeps the particles small, zinc silicate was synthesized from the volatile organometallic precursor [{MeZnOSiMe3}4], possessing a Zn‐methyl‐ and O‐silyl‐substituted Zn4O4‐heterocubane framework (cubane), under oxidizing conditions, using the chemical vapor synthesis (CVS) method. The products obtained under different process conditions and their structural evolution after sintering were investigated by using various analytical techniques (powder X‐ray diffraction, transmission electron microscopy, EDX analysis, solid‐state NMR, IR, Raman, and UV/Vis spectroscopy). The deposited aerosol obtained first (processing temperature 750 °C) was amorphous, and contained agglomerates with primary particles of 12 nm in size. These primary particles can be described by a [Zn‐O‐Si] phase without long‐range order. The deposit obtained at 900 °C contained particles with embedded nanocrystallites (3–5 nm) of β‐Zn2SiO4, Zn1.7SiO4, and ZnO in an amorphous matrix. On further ageing, the as‐deposited particles obtained at 900 °C form α‐Zn2SiO4 imbedded in amorphous SiO2. The crystallite sizes and primary particle sizes in the formed α‐Zn2SiO4 were found to be below ∼50 nm and mainly spherical in morphology. A gas‐phase mechanism for the particle formation is proposed. In addition, the solid‐state reactions of the same precursor were studied in detail to investigate the fundamental differences between a gas‐phase and a solid‐state synthesis route.
A Rationale for the Large Breathing of the Porous Aluminum Terephthalate (MIL‐53) Upon Hydration
Authors: Loiseau Thierry , Serre Christian , Huguenard Clarisse , Fink Gerhard , Taulelle Francis , Henry Marc , Bataille Thierry , Férey Gérard
Published: March 2004

Aluminum 1,4‐benzenedicarboxylate Al(OH)[O2CC6H4CO2]⋅ [HO2CC6H4CO2H]0.70 or MIL‐53 as (Al) has been hydrothermally synthesized by heating a mixture of aluminum nitrate, 1,4‐benzenedicarboxylic acid, and water, for three days at 220 °C. Its 3 D framework is built up of infinite trans chains of corner‐sharing AlO4(OH)2 octahedra. The chains are interconnected by the 1,4‐benzenedicarboxylate groups, creating 1 D rhombic‐shaped tunnels. Disordered 1,4‐benzenedicarboxylic acid molecules are trapped inside these tunnels. Their evacuation upon heating, between 275 and 420 °C, leads to a nanoporous open‐framework (MIL‐53 ht (Al) or Al(OH)[O2CC6H4CO2]) with empty pores of diameter 8.5 Å. This solid exhibits a Langmuir surface area of 1590(1) m2 g−1 together with a remarkable thermal stability, since it starts to decompose only at 500 °C. At room temperature, the solid reversibly absorbs water in its tunnels, causing a very large breathing effect and shrinkage of the pores. Analysis of the hydration process by solid‐state NMR (1H, 13C, 27Al) has clearly indicated that the trapped water molecules interact with the carboxylate groups through hydrogen bonds, but do not affect the hydroxyl species bridging the aluminum atoms. The hydrogen bonds between water and the oxygen atoms of the framework are responsible for the contraction of the rhombic channels. The structures of the three forms have been determined by means of powder X‐ray diffraction analysis. Crystal data for MIL‐53 as (Al) are as follows: orthorhombic system, Pnma (no. 62), a = 17.129(2), b = 6.628(1), c = 12.182(1) Å; for MIL‐53 ht (Al), orthorhombic system, Imma (no. 74), a = 6.608(1), b = 16.675(3), c = 12.813(2) Å; for MIL‐53 lt (Al), monoclinic system, Cc (no. 9), a = 19.513(2), b = 7.612(1), c = 6.576(1) Å, β = 104.24(1)°.
Shape‐Persistent Macrocycles: From Molecules to Materials
Authors: Höger Sigurd
Published: March 2004

Shape‐persistent macrocycles with an interior in the nanometer regime allow the attachment of (functional) side groups at defined positions at the ring. These side groups can have either a fixed orientation relative to the molecular backbone or they can adapt their orientation according to an external stimulus. The properties and applications of the compounds depend strongly on the orientation of these side groups. Macrocycles with intraannular or adaptable long alkyl groups display a new design principle for discotic liquid crystals. Macrocycles with extraannular (oligo)alkyl groups can be used for surface patterning in the nanometer regime and rings with extraannular oligostyryl groups are able to aggregate to supramolecular hollow polymer brushes.
Self‐Assembly of Tris(2‐ureidobenzyl)amines: A New Type of Capped, Capsule‐Like Dimeric Aggregates Derived from a Highly Flexible Skeleton
Authors: Alajarín Mateo , Pastor Aurelia , Orenes Raúl‐Ángel , Steed Jonathan W. , Arakawa Ryuichi
Published: March 2004

A set of tris(2‐ureidobenzyl)amines 3 was prepared and their dimerization processes thoroughly investigated. In spite of their inherent flexibility, tris(ureas) 3 form dimeric aggregates both in the solid state and in solution. Evidence for the existence of these dimeric species was provided by a combination of techniques (X‐ray analysis, NMR and IR spectroscopy, and ESI‐MS). The association constants and thermodynamic parameters for the dimerization processes of selected tris(ureas) were determined and show that they are enthalpically driven. Heterodimerization experiments in solution reveal a high degree of self‐recognition or narcissistic self‐sorting. On the other hand, desymmetrized tris(ureas) derived from 3 self‐assemble with modest regioselectivities depending on the terminal substituent of every urea functionality.
Fredholm theory and transversality for noncompact pseudoholomorphic mapsin symplectizations
Authors: Dragnev Dragomir L.
Published: March 2004

We study pseudoholomorphic maps from a punctured Riemann surface into the symplectization of a contact manifold. A Fredholm theory yields the virtual dimension of the moduli spaces of such maps in terms of the Euler characteristic of the Riemann surface and the asymptotics data given by the periodic solutions of the Reeb vector field associated to the contact form. The transversality results establish the existence of additional structure for these spaces. To be more precise, we prove that these spaces are generically smooth manifolds, and therefore their virtual dimension coincides with their actual dimension. © 2004 Wiley Periodicals, Inc.
Gender differences in GAD antibody – positive diabetes mellitus in relation to age at onset, C‐peptide and other endocrine autoimmune diseases
Authors: Lindholm Eero , Hallengren Bengt , Agardh Carl‐David
Published: March 2004

Background

Females have an increased incidence of autoimmune diseases. However, no gender difference in the incidence of type 1 diabetes is found. The frequency of antibodies against glutamic acid decarboxylase (GADA) in diabetes mellitus depends on age at diagnosis and also gender. Several studies have shown that high GADA levels can predict future β‐cell failure and need for insulin treatment. The aim of this study was to investigate possible gender differences in relation to GADA levels, fasting plasma C‐peptide levels and frequency of other autoimmune endocrine diseases in GADA‐positive patients with different age at diabetes diagnosis.

Methods

GADA were screened in 4974 patients from a local diabetes registry (Diabetes 2000), and plasma C‐peptide was measured and a history of other autoimmune endocrine diseases was recorded. Of these patients, 822 were GADA positive and were further divided into four groups depending on the age at diagnosis of diabetes; Group 1: <20 years, Group 2: 20–39 years, Group 3: 40–59 years and Group 4: ≥60 years.

Results

Female patients in Group 3 had lower fasting plasma C‐peptide levels (median 0.21[0.00–0–56] vs. 0.41[0.00–0.73] nmol/L, p = 0.02), higher GADA levels (median 7 [4–9] vs. 5 [2–7] Arbitrary Unit (AU), p = 0.0003) and higher frequency of other autoimmune endocrine diseases (22.4 vs. 5.3%, p = 0.0001) than male patients. In a stepwise logistic regression analysis, diabetes duration (p < 0.000001), high GADA levels (Exp (B) 3.68 CI 1.69–7.98, p = 0.001) and low BMI (p = 0.00002) were associated with total β‐cell failure in Group 3.

Conclusions

GADA‐positive female diabetic patients with an age at diagnosis between 40 and 59 years have higher GADA levels and a more severe loss of β‐cell function than male patients with the same age at diagnosis. This could be due to the effect of sex steroids and/or GnRH on the regulation of the immune system. Female patients with high GADA levels also had a high prevalence of other autoimmune endocrine diseases, especially autoimmune thyroid disease, which further emphasises the need for screening of thyroid function in female patients with high GADA levels. Copyright © 2004 John Wiley & Sons, Ltd.
Calcium‐dependent mitochondrial permeability transition is augmented in the kidney of Goto‐Kakizaki diabetic rat
Authors: Oliveira Paulo J. , Esteves Telma C. , Seiça Raquel , Moreno António J. M. , Santos Maria S.
Published: March 2004

Background

Renal disease associated with diabetes mellitus is a major problem among diabetic patients. The role of mitochondria in the pathogenesis of diabetes has received a large amount of attention in the last years, but many aspects of this subject are still poorly understood. In the present study, we studied the susceptibility of the mitochondrial permeability transition (MPT) on kidney mitochondria from the Goto‐Kakizaki (GK) rat, an animal model featuring physiological and pathological alterations characteristic of type 2 diabetes.

Methods

Kidney mitochondria were isolated by differential centrifugations; mitochondrial electric transmembrane potential and calcium loading capacity were evaluated with a TPP+‐selective electrode and with a calcium‐sensitive fluorescent probe. Coenzyme Q9, Q10 and vitamin E were evaluated by high‐performance liquid chromatography (HPLC).

Results

Kidney mitochondria from the diabetic animals had an increased susceptibility to the induction of the MPT by calcium. We observed a loss of calcium‐loading capacity and a higher calcium‐induced mitochondrial depolarization. Vitamin E and coenzyme Q9 were also increased in kidney mitochondria from GK rats.

Conclusions

The results show an enhanced MPT activation in kidney mitochondria from GK rats, which lead us to suggest that this condition may be one major alteration triggered by chronic diabetes in kidney cells, ultimately leading to cell dysfunction. Copyright © 2004 John Wiley & Sons, Ltd.
Genetic prediction of type 1 diabetes in a population with low frequency of HLA risk genotypes and low incidence of the disease (the DIABFIN study)
Authors: Buzzetti R. , Galgani A. , Petrone A. , Del Buono M. L. , Erlich H. A. , Bugawan T. L. , Lorini R. , Meschi F. , Multari G. , Pozzilli P. , Locatelli M. , Bottazzo G. , Di Mario U.
Published: March 2004

Background

To develop a sensitive, specific screening strategy for predicting genetic risk for type 1 diabetes mellitus (T1DM) in the low‐incidence continental Italian population, and to define with this tool, a cohort of high‐to‐moderate risk infants for an immunological follow‐up study aimed at identifying environmental risk factors for T1DM.

Methods

4855 newborns in three regions of continental Italy were screened for T1DM HLA‐DRB1‐DQB1 risk genotypes using a reverse line blot typing method. Risk classification was based on odds ratios (OR) found in a preliminary case–control study (356 T1DM patients, 412 controls). Screening efficiency was optimized by allele subtyping.

Results

Screening for well‐known T1DM susceptibility genotypes [DRB1*03/*04‐DQB1*0302; DRB1*03/*03; DRB1*04/*04‐DQB1*0302; DRB1*04‐DQB1*0302/X where X ≠ DRB1*03, DRB1*04‐DQB1*0302, DQB1*0602 or DQB1*0603] was associated with <60% sensitivity due to their low frequencies in the general Italian population. Inclusion of an additional genotype from which protective DRB1 and DQB1 alleles had been excluded [DRB1*03/X° where DQB1 ≠ *0301, *0503, *0602, or *0603 and X° ≠ DRB1*03, DRB1*04‐DQB1*0302 or DRB1*07] increased screening sensitivity to 75% (specificity: 85%). Among 4855 newborns, we have found the high‐risk genotype [DRB1*03/*04‐DQB1*0302; estimated absolute risk (AR) 1/23] to be present in only 0.9%. The moderate‐risk genotypes were found in 13.8% of newborns (estimated AR 1/177).

Conclusions

Risk classification must be tailored to the characteristics of the individual population, in particular, the allelic frequencies in the background population and T1DM prevalence. We have developed a screening strategy with good levels of sensitivity that should prove effective for use throughout the Italian peninsula. Copyright © 2004 John Wiley & Sons, Ltd.
Evidence for a vicious cycle of exercise and hypoglycemia in type 1 diabetes mellitus
Authors: Ertl A. C. , Davis S. N.
Published: March 2004

Exercise is a cornerstone of diabetes management as it aids in glycemic control, weight management, reducing blood pressure, and improving the quality of life of patients. Unfortunately, owing to the complexity and difficulties of regulating exogenous insulin in a physiologic manner during exercise, physical activity often results in hypoglycemia in patients with type 1 diabetes mellitus (type 1 DM).

When glucose levels fall below threshold glycemic levels, neuroendocrine, autonomic nervous system (ANS), and metabolic glucose counterregulatory mechanisms are activated. These hypoglycemic counterregulatory mechanisms in type 1 DM can be blunted irreversibly by disease duration or by acute episodes of prior stress. These reduced (or absent) counterregulatory responses result in a threefold increase in severe hypoglycemia when intensive glycemic control is implemented in type 1 DM 1. Much recent work has been focused on determining the in vivo mechanisms responsible for causing the increased incidence of severe hypoglycemia in type 1 DM. Studies from several laboratories have demonstrated the role played by episodes of antecedent hypoglycemia in producing blunted glucose counterregulatory responses during subsequent exposures of hypoglycemia.

Until recently, the mechanisms responsible for exercise related hypoglycemia in type 1 DM have been attributed to relative or absolute increases of insulin levels or incomplete glycogen repletion after physical activity. Owing to the qualitative similarity of neuroendocrine, ANS, and metabolic responses to hypoglycemia and exercise, we have hypothesized that neuroendocrine and ANS counterregulatory dysfunction may also play an important role in the pathogenesis of exercise‐related hypoglycemia in type 1 DM. Vicious cycles can be created in type 1 DM, where an episode of hypoglycemia or exercise can feed forward to downregulate neuroendocrine and ANS responses to a subsequent episode of either stress, thereby creating further hypoglycemia (Figure 1). This article will review the recent work that has studied the contribution of counterregulatory dysfunction to exercise‐induced hypoglycemia in type 1 DM. Copyright © 2004 John Wiley & Sons, Ltd.

1. Reciprocal vicious cycles may be created in type 1 diabetes mellitus (type 1 DM), whereby an episode of hypoglycemia or exercise can feed forward to downregulate neuroendocrine and autonomic nervous system responses to a subsequent episode of either stress, thereby creating further hypoglycemia

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1. Reciprocal vicious cycles may be created in type 1 diabetes mellitus (type 1 DM), whereby an episode of hypoglycemia or exercise can feed forward to downregulate neuroendocrine and autonomic nervous system responses to a subsequent episode of either stress, thereby creating further hypoglycemia
Memory effect of ferroelectric liquid crystal stabilized by polymer fibers
Authors: Murashige Takeshi , Fujikake Hideo , Ikehata Seiichiro , Sato Fumio
Published: March 2004

We investigated the bistable state of the molecular orientation of ferroelectric liquid crystal that is formed between micro‐polymer fibers, and demonstrated the occurrence of a memory effect when the smectic layer structure is corrected. In this study, we introduced high‐pretilt alignment layer and formed polymer fibers in the liquid crystal by using the photopolymerization phase separation method in order to make the creasing and bending of the layer in the direction of thickness unidirectional. In addition, we treated the composite film of the liquid crystal and the polymer fiber by applying an AC voltage in order to hold the cone axis of the liquid crystal molecule in a rubbing direction during the gradual cooling process in which the liquid crystal molecule tilt (phase transition from the smectic A phase to the smectic C* phase). The results of trial production confirmed an alleviation of the bending of the smectic layer in the horizontal plane and the occurrence of a memory effect, resulting in a minute distribution of bistable switching domains and a memory function involving area‐wise grayscale. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 16–24, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10082
New design method for tapered buffer circuit with TIS (Trench‐Isolated Transistor using sidewall gate) and its application to high‐density DRAMs
Authors: Watanabe Shigeyoshi
Published: March 2004

A new design method has been conceived for a buffer circuit using TIS. In the buffer circuit of a taper type with a fan‐out of 3 intended for driving a large load capacitance, a new design procedure is conceived that minimizes the pattern area without sacrificing characteristics such as power consumption. In the new design method, the “planar+TIS” method is employed, in which planar‐type transistors are used in the front stage of the buffer circuit while TIS‐type transistors are used in the latter stage. This design method is applied to a large‐capacity DRAM. Relative to the case in which conventional planar transistors are used, the chip area can be reduced by about 8% without sacrificing characteristics such as power consumption. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 9–15, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10152
Fabrication of extended porous polymer films for aligning nematic liquid crystal
Authors: Kuboki Masashi , Fujikake Hideo , Murashige Takeshi , Sato Hiroto , Fujisaki Yosihide , Kawakita Masahiro , Kikuchi Hiroshi , Kurita Taichiro , Sato Fumio
Published: March 2004

A method is proposed for fabricating extended porous polymer films for spatially aligning liquid crystals. By means of the successive biaxial extension method, polyolefin porous polymer films are extended to a great degree (10µm thick, porosity 72.4%). After the porous polymer films are filled with nematic liquid crystals, a liquid crystal cell is fabricated by attaching glass substrates. The extension factor is 2.4 times and 6 times along the two orthogonal directions. As a result of observation by a polarization microscope, it is recognized that the liquid crystal molecules are aligned along the extension direction within the porous film. An optical modulation function using the birefringence of the liquid crystal is observed on application of a voltage. Unlike the conventional rubbing orientation process, the present scheme does not generate any static electricity or fine dust. Further, high‐temperature baking of the alignment layer is not necessary. Orientation processing of liquid crystals is possible with the substrate maintained at room temperature. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 1–8, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10164
A neural network system composed of 1000 neurons and 1 million 7‐bit synapses
Authors: Hirai Yuzo , Ochiai Tatsuo , Yasunaga Moritoshi
Published: March 2004

A pulse‐density‐type digital neural network system is developed in which digital circuits are used and all neurons operate asynchronously. The system is hardware of a scale in which 1008 neurons are mutually coupled through more than 1 million synapses with 7‐bit precision. The scale is the largest in the world. The system has the feature that the operation of the individual neuron follows a nonlinear first‐order differential equation, although digital circuits are used. Consequently, it is a system that can solve a 1000‐dimensional system of nonlinear differential equations in continuous time and in parallel. In order to realize the physical mutual couplings between more than 1000 neurons, the following simplifications are applied. The number of signal lines is reduced through the use of pulse density. The precision of the synaptic coupling coefficient is maintained as 7 bits. Spatial summation of the synaptic outputs is realized by using a pulse OR circuit. In spite of these simplifications, a discrimination experiment on the handwritten numerals using the nearest‐neighbor method shows that the proposed method is comparable to that of a workstation with floating‐point arithmetic. This system is connected to the Internet and can be accessed from any part of the world. The home page address ishttp://www.viplab.is.tsukuba.ac.jp/. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 34–43, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20069
Automatic prank call rejection system for home country direct based on speech recognition technology
Authors: Kuroiwa Shingo , Naito Masaki , Nakamura Makoto , Sakayori Shin'ichi , Mukasa Takeshi
Published: March 2004

A system that automatically rejects prank calls coming through home country direct from abroad, which is one of the international telephone services, is presented in this paper. Home country direct is a service whereby a user can use international telephone services in his/her native language by directly accessing home country's international station operators. Since this service does not require fees for calling operators, prank calls made by children from abroad pose a problem. Thus, an “automatic prank call rejection system” that determines a legitimate user by instructing him in Japanese to say a specific word, and determining him to be a legitimate user if he repeats this word correctly or determining the call to be a prank call otherwise has been developed. When this system was applied to commercial services, it rejected 94.7% of prank calls. Legitimate users erroneously rejected constituted 0.8%. It has been confirmed that erroneously rejected legitimate users ended up being connected by repeating the word correctly ultimately by hanging up the phone and redialing a number of times. This system has been found to reject about 10,000 prank calls a day when applied to the operations of the KDD International Telephone Center since March 1996. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 44–52, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20070
A method of spotting retrieval of similar intervals using frame‐wisely renewing query
Authors: Sekimoto Nobuhiro , Nishimura Takuichi , Takahashi Hironobu , Oka Ryuichi
Published: March 2004

The authors propose a method called the Rutic method for detecting time‐series intervals similar to a sequentially entered time‐series query in a large‐scale time‐series database containing data such as video or audio data. Although conventional methods such as RIFCDP or IPM handled sequentially entered time‐series queries, they required a relatively large amount of calculations and were unsuitable for real‐time retrieval from a large database. The proposed method enables retrieval results for the sequentially entered time‐series query to be output for each entered frame. Since the Rutic method requires few calculations, it enables spotting retrieval to be implemented in real time. This paper describes the algorithm of the Rutic method and verifies its effectiveness by performing experiments using video retrieval to compare it with other methods. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(4): 65–76, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20072
Michael Additions of Aldehydes and Ketones to β‐Nitrostyrenes in an Ionic Liquid
Authors: Kotrusz Peter , Toma Stefan , Schmalz Hans‐Günther , Adler Andreas
Published: March 2004

Michael additions of different aldehydes and ketones to β‐nitrostyrene and 2‐(β‐nitrovinyl)thiophene in 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim]PF6) were studied. β‐Nitrostyrene was a better acceptor than 2‐(β‐nitrovinyl)thiophene, in terms of both reactivity and selectivity. Aldehydes proved to be better donors than ketones, which were themselves better than β‐diketones. L‐proline proved to be the best catalyst among seven organocatalysts tested. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Asymmetric Electrophilic α‐Amination of Carbonyl Groups
Authors: Greck Christine , Drouillat Bruno , Thomassigny Christine
Published: March 2004

The electrophilic amination constitutes an unconventional C−N bond‐forming reaction. Asymmetric versions have been developed using chiral reagents or catalysts and starting from optically pure substrates. The aminated products can be obtained with high stereoselectivities. These methodologies are flexible routes for the synthesis of α‐amino acids and nitrogen heterocycles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)