bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of New Transplatinum Complexes Containing Phosphane Groups − Cytotoxic Studies in Cisplatin‐Resistant Cells
Authors: Ramos‐Lima Francisco J. , Quiroga Adoración G. , Pérez José M. , Font‐Bardía Mercé , Solans Xavier , Navarro‐Ranninger Carmen
Published: April 2003

In this paper we report the synthesis and characterization of novel trans platinum(II) complexes of general formula trans‐[PtCl2(L)(PPh3)], where L is NH2CH(CH3)CH2CH3 (complex 1), (R)‐NH2CH(CH3)CH2CH3 (complex 2), (S)‐NH2CH(CH3)CH2CH3 (complex 3) and NH2CH(CH3)2 (complex 4). The new complexes contain phosphane ligands trans to the amine group. X‐ray crystal structure determinations of complexes 1 and 3 confirmed their trans configurations. The cytotoxic activity of these complexes have been evaluated and compared with the activity of trans platinum complexes already viewed as potential drugs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Dynamic Features of (Chloro)zirconocene Cations Stabilised by Pendant (Diarylphosphanyl)alkyl and (Dimethylamino)alkyl Substituents at Their Cyclopentadienyl Ring Systems
Authors: Döring Steve , Kotov Vasily V. , Erker Gerhard , Kehr Gerald , Bergander Klaus , Kataeva Olga , Fröhlich Roland
Published: April 2003

Treatment of the substituted (diarylphosphanyl)methyl group‐4 metallocene complexes [(C5H4−CR1R2−PAr2)2ZrCl2] (2: R1/R2 = CH3/CH3, H/CH3, H/aryl) with Li[B(C6F5)4] in dichloromethane solution results in chloride ligand abstraction (with LiCl precipitation) to yield the complexes [(C5H4−CR1R2−PAr2)2Zr−Cl+] (5), with both phosphanyl groups internally coordinated to the metal centre. Three possible diastereoisomers are observed in the case of 5c (R1 = H; R2 = CH3), while bulkier R2 substituents give higher selectivities. The thermally induced (reversible) cleavage of the Zr−phosphane linkage results in dynamic NMR behaviour. Gibbs activation energies of ΔG≠(298 K) = 14.8 ± 0.5 and 14.5 ± 0.5 kcal/mol were obtained for these intramolecular equilibration processes in the complexes trans‐5d (R1 = H; R2 = Ph) and trans‐5e (R1 = H; R2 = ferrocenyl), respectively. Treatment of the substituted (dimethylamino)methyl metallocene complexes [(C5H4−CR1R2−NMe2)2ZrCl2] (6a, 6b) with Li[B(C6F5)4] proceeds analogously to yield the cation systems [{C5H4−C(CH3)2−NMe2}2ZrCl+] (12a) and [{C5H4−CH(CH3)−NMe2}2ZrCl+] (12b, three possible diastereoisomers). Both complexes have their pairs of amino groups coordinated to the metal centre. The complexes exhibit dynamic NMR spectra. Selective equilibration of the diastereotopic N(CH3)A(CH3)B resonances of complex 12a is observed [ΔG≠(233 K) = 11.5 ± 0.2 kcal/mol], whereas the adjacent C(CH3)A(CH3)B methyl groups remain diastereotopic. The dynamic equilibration of the latter was observed at a markedly higher temperature [ΔG≠(333 K) = 17.3 ± 0.2 kcal/mol]. Treatment of [{C5H4−C(CH3)2−NMe2}CpZrCl2] (10) with Li[B(C6F5)4] resulted in the formation of complex [{C5H4−C(CH3)2−NMe2}CpZr−Cl+] (11), which shows the internal −N(CH3)A(CH)B equilibration proceeding with a markedly higher activation barrier [ΔG≠(333 K) = 17.6 ± 0.2 kcal/mol] than in 12a, and a stereochemical memory effect indicative of solvent coordination to the metal centre of the resulting highly electrophilic chlorozirconocene cation intermediate. Complex 11 was characterised by an X‐ray crystal structure analysis, which shows the internal Zr←amine coordination. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
SiO2‐CaO Vitreous Films Deposited onto Ti6Al4V Substrates
Authors: Izquierdo‐Barba Isabel , Asenjo Agustina , Esquivias Luis , Vallet‐Regí María
Published: April 2003

A sol‐gel dipping method has been utilised to deposit SiO2‐CaO films onto Ti6Al4V alloy substrates. These layers were prepared by the dip‐coating technique from a series of precursor solutions with different concentrations of glassy xSiO2‐(1 − x)CaO (x = 0.8 mol) diluted with absolute ethanol. The characterisation of the films by a variety of techniques reveals differences in the textural properties and in the films’ thicknesses depending on the sol concentration in the precursor solution. Concentrated precursor solutions yield porous layers with a higher thickness and surface roughness than those obtained from the dilute ones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Ruthenium‐Catalysed Selective Transetherification of Substituted Vinyl Ethers To Form Acetals and Aldehydes
Authors: Saoud Mustapha , Romerosa Antonio , Mañas Carpio Sonia , Gonsalvi Luca , Peruzzini Maurizio
Published: April 2003

The water‐soluble ruthenium allenylidene complex [{RuCl(μ‐Cl)(C=C=CPh2)(TPPMS)2}2]Na4 catalyses the selective transformation of substituted linear and cyclic vinyl ethers with MeOH, under mild non acidic conditions, to give acetals, while aldehydes and ketones are obtained in a CHCl3/H2O mixture, which allows for easy recycling of the catalyst. NMR studies showed that the reaction follows a transetherification mechanism rather than simple acid‐catalysed hydrolysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Oligomerisation of Ethylene to Linear α‐Olefins by new Cs‐ and C1‐Symmetric [2,6‐Bis(imino)pyridyl]iron and ‐cobalt Dichloride Complexes
Authors: Bianchini Claudio , Mantovani Giuseppe , Meli Andrea , Migliacci Fabio , Zanobini Fabrizio , Laschi Franco , Sommazzi Anna
Published: April 2003

A new family of Cs‐ and C1‐symmetric 2,6‐bis(imino)pyridyl ligands has been synthesised. These ligands, which differ from their known counterparts in the contemporaneous presence of alkyl and aryl substituent at the ketimine nitrogen atoms, form stable, five‐coordinate complexes with FeCl2 and CoCl2. All ligands and catalysts have been fully characterised both in the solid state and in solution. A single‐crystal X‐ray analysis of [CoCl2{2‐[CMe=N−(2,6‐dimethylphenyl)]‐6‐(CMe=N−C6H11)C5H3N}]·H2O shows the metal centre to adopt a highly distorted square‐pyramidal geometry. In combination with methylaluminoxane (MAO), both iron and cobalt compounds act as effective and selective (> 99%) catalysts for the oligomerisation of ethylene to a Schulz−Flory distribution of α‐olefins, with the α factor ranging from 0.61 to 0.91. The iron catalysts exhibit TOFs as high as 7·105 mol C2H4 (mol of cat × h)−1 and are much more active than their cobalt analogues. Experiments at different ethylene pressures with the iron catalysts showed that both the propagation rate and the chain transfer rate are first order in ethylene pressure. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2003)
Mn and Fe K‐edge XAS Spectra of Manganese and Iron Nitrido Compounds
Authors: Niewa Rainer , Hu Zhiwei , Kniep Rüdiger
Published: April 2003

We performed a Mn K‐edge XAFS study of a number of highly moisture‐sensitive nitridomanganates with manganese in different oxidation states and in various surroundings: Li2[(Li1−xMnIx)N] [x = 0.75(1)], Li24[MnIIIN3]3N2, and Li7[MnVN4]. For reference purposes Mn, MnO and θ‐Mn6N5+x [x = 0.26(1)] were measured. The energy positions of the pre‐edge maxima are almost independent of the electronic state of Mn, while the intensity is sensitive to the geometric arrangement of the coordination of Mn. The main‐edge is sensitive to the oxidation state − a clear shift to higher energies with increasing oxidation state can be seen. This shift is smaller than the shift observed for the corresponding oxides, due to the lower electronegativity of nitrogen compared to oxygen, and corresponds to a higher covalency of the Mn−N bond. Similar results can be taken from the Fe K‐edges of Li2[(Li1−xFeIx)N] with x = 0.20(1) and Li3[FeIIIN2] in comparison to metallic Fe, FeIISO4·7H2O and α‐FeIII2O3. The results are consistent with the presence of an unusual oxidation state (+1) for the transition metals in the phases of the general composition Li2[(Li1−xMx)N]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Characterization of (PTU)I2 (PTU = 6‐n‐propyl‐2‐thiouracil) and (CMBZT)I2 (CMBZT = 5‐chloro‐2‐mercaptobenzothiazole) and Possible Implications for the Mechanism of Action of Anti‐Thyroid Drugs
Authors: Antoniadis Constantinos D. , Corban Ghada J. , Hadjikakou Sotiris K. , Hadjiliadis Nick , Kubicki Maciej , Warner Stephanie , Butler Ian S.
Published: April 2003

Direct reaction of 6‐n‐propyl‐2‐thiouracil (PTU), a widely used anti‐thyroid drug against hyperthyroidism (Graves’ disease), or 5‐chloro‐2‐mercaptobenzothiazole (CMBZTH) with iodine in a molar ratio of 1:1 resulted in the formation of the charge‐transfer (CT) complexes [(PTU)I2] (1) or [(CMBZT)I2] (2). All reactions were carried out in dichloromethane and water solutions. Compounds 1 and 2 were characterized by elemental analyses, FT‐Raman, FT‐IR, UV/Vis and 1H NMR spectroscopy. The crystal structures of both complexes were determined by X‐ray diffraction at 120(1) K (1) and 293(2) K (2). The charge‐transfer nature of the bonds in the adducts 1 and 2 was verified by the lengthening of the I−I bond lengths as compared to the S−I bond lengths and by the characteristic CT bands observed in the UV spectra of the complexes. Compound 1 [(C7H10N2OS)I2] [monoclinic with space group P21/c and a = 9.8501(7), b = 10.3101(7), c = 12.0287(8) Å, β = 99.707(6)°, Z = 4] consists of a propylthiouracil ligand bonded with an iodine atom through sulfur. Extended intermolecular N−H···O contacts link the molecules forming a supramolecular assembly. Compound 2 {(C7H4ClNS2)I2} [orthorhombic, space group P212121, a = 4.1650(10), b = 9.691(2), c = 28.471(6) Å, Z = 4] consists of a 5‐chloro‐2‐mercaptobenzothiazole ligand bonded with an iodine atom through sulfur. An extended intermolecular linkage via I···H−N bonds leads to the formation of an extended structure. Attempts to draw conclusions on the behavior of a thioamide — when used as an anti‐thyroidal drug — towards iodine have been made. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Human Telomeric Sequence (T2AG3)n is Efficiently Cross‐Linked by AN1 Binding to the Platinum of a trans‐Pt(NH3)2 Chelate of an Antisense Oligo‐2′‐O‐Methylribonucleotide
Authors: Perrier Sandrine , Seela Frank , Schwartz Annie , Leng Marc , Chottard Jean‐Claude
Published: April 2003

In order to irreversibly cross‐link an antisense oligonucleotide to the human telomeric sequence (T2AG3)n, the inter‐strand bridging rearrangement described by Leng et al. was investigated on (21‐mer antisense) (20‐mer target) duplexes: (G*NG*)(TA) ⇄ (G*NG)(TA*), G*NG* being a trans‐[Pt(NH3)2{1,3‐(GNG)‐N7‐G,N7‐G}] chelate with N = U or T. Three different duplexes were studied, confirming first that for a DNA target strand the rearrangement was faster with a platinated oligo‐2′‐O‐methylribonucleotide than with a deoxy oligonucleotide as antisense strand. Second, a telomeric DNA target strand was cross‐linked faster than an all‐purine oligonucleotide containing a single TA doublet. Accordingly, the half time of formation of the cross‐linked hybrid duplex [2′‐OMe‐r(CCCUAACCCG*UGACCCUAACCC)]·[d(T2AG3)2(TTA*G3)(T2AG3)] is one minute, compared with the nine days required for the complete formation of the bridged d(CTCCTG*TGTCTC)·d(GAGATA*AGGAG) duplex. The NMR analysis of the latter showed that the platinum cross‐link involves the A*N1 moiety as ligand. The timescale difference between the two reactions raised the question of an eventual kinetic cross‐link which might isomerize to the final one observed. This question was addressed using 1‐deazaadenine in the TA doublet of the three target strands of this work. No cross‐linking reaction was observed, proving that AN1 is the bridging atom in all the cases studied so far. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Use of essential oils as media for the enantioselective esterification of the monoterpene perillyl alcohol catalyzed by lipase
Authors: Skouridou Vasso , Stamatis Haralambos , Kolisis Fragiskos N.
Published: April 2003

The synthesis of perillyl alcohol esters by direct esterification catalyzed by immobilized lipase from Candida antarctica (Novozyme 435) was studied. For this purpose, fatty acids with a chain length from 3‐16 were used. The reactions were carried out in mixtures of α‐pinene and myrcene as well as in pure organic solvents. It was found that the esterification rates increased from 3.7‐6.9 mM/min when using decreasing concentrations of myrcene in α‐pinene (100‐0%). Higher rates and conversions were obtained with decanoic acid as the acyl donor (6.9 mM/min, 81.5%), while lower conversions were obtained with fatty acids of shorter (propionic acid, 5.6%) or longer (hexadecanoic acid, 62.5%) carbon chain. In addition, it was found that the effect of the water activity depended on the chain length of the acyl donor and the composition of the solvent mixture. Also, esterification rates increased from 1.8‐6.9 mM/min with increasing hydrophobicity of the solvent (logP from 0.9‐4.8) of the organic solvent used. Finally, it was found that Candida antarctica lipase presented a preference in the esterification of (S)‐(—)‐ and (R)‐(+)‐perillyl alcohol in favor of the (R)‐(+) enantiomer. The enantioselectivity was found increased with increasing logP, whereas the water activity of the reaction mixture did not affect the enantioselectivity significantly.
Effects of dietary fish oil and oxidized cholesterol on the concentration of 7β‐hydroxycholesterol in liver, plasma, low density lipoproteins and erythrocytes of rats at various vitamin E supply
Authors: Ringseis Robert , Eder Klaus
Published: April 2003

Two experiments with rats were carried out to investigate the effect of dietary fish oil and oxidized cholesterol on the concentration of 7β‐hydroxycholesterol, an oxysterol of mainly nonenzymatic origin, in liver, plasma, low density lipoproteins and erythrocytes of rats at different vitamin E supply. In Experiment 1, four groups of rats received diets with coconut oil or salmon oil (100 g/kg diet) and vitamin E concentrations of 40 or 240 mg α‐tocopherol equivalents/kg. In Experiment 2, eight groups of rats received diets supplemented with pure or oxidized cholesterol (5 g/kg), coconut oil or salmon oil (100 g/kg diet) and vitamin E concentrations of 40 or 240 mg α‐tocopherol equivalents/ kg. Rats fed the salmon oil diets had significantly higher concentrations of 7β‐hydroxycholesterol in liver, plasma, low density lipoproteins and erythrocytes than rats fed coconut oil diets. Rats fed the diets supplemented with oxidized cholesterol had significantly higher concentrations of 7β‐hydroxycholesterol in all the samples analyzed than rats fed pure cholesterol. Increasing the dietary vitamin E concentration from 40 to 240 mg α‐tocopherol equivalents/kg diet reduced the concentration of 7β‐hydroxycholesterol in plasma; the concentrations of 7β‐hydroxycholesterol in liver, low density lipoproteins and erythrocytes were not influenced by the dietary vitamin E concentration. The study suggests that diets with fish oil or oxidized cholesterol are critical with respect to the formation of 7β‐hydroxycholesterol.
Chemical and physical properties of a sunflower oil with high levels of oleic and palmitic acids
Authors: Guinda Ángeles , Dobarganes M. Carmen , Ruiz‐Mendez M. Victoria , Mancha Manuel
Published: April 2003

High‐oleic high‐palmitic sunflower oil (HOHPSO) has been obtained from field‐grown mutant sunflower seeds CAS‐12. The fatty acid and triacylglycerol compositions, the thermo‐oxidative stability and the physical properties of the HOHPSO were determined and compared with those of the conventional and high oleic sunflower oils and those of a liquid fraction of palm oil (olein). The major fatty acids of the HOHPSO were monoenes (57.7% oleic, 7.3% palmitoleic) and palmitic (27, 8%), while the content of linoleic acid was low (2.3%). The saturated fatty acids were almost absent from the sn‐2 position and, thus, the major triacylglycerol (TAG) molecular species were those with one or two saturated fatty acids at the sn‐1, 3 positions and oleic acid at the sn‐2 position (mainly POO and POP). Total polar compounds and their distribution in oxidised TAG monomers and TAG polymers were determined after 10 h at 180 °C. The HOHPSO showed enhanced thermal stability, producing half the amount of total polar compounds, and much less TAG polymers, as the palm olein. The stability index (Rancimat) of the HOHPSO was unusually high (19 h at 120 °C). The thermal properties of the HOHPSO (determined from the differential scanning calorimetry thermograms) were different from those of the palm olein. The HOHPSO presents lower solid fat con‐tents than the palm olein above 15 °C and hence remains liquid at common working temperatures.
Adsorptive fouling of inorganic membranes during microfiltration of vegetable oils
Authors: Hafidi Abdellatif , Pioch Daniel , Ajana Hamid
Published: April 2003

a The objective of the present paper is to contribute to a better understanding of the fouling phenomenon occurring during microfiltration of crude vegetable oil. To assess the role some oil components play in the fouling, the latter was monitored by the evolution of fluxes during the microfiltration of different model oils. Resistances to mass transfer were discussed to estimate the contribution of different phenomena and to compare hydrophilic and hydrophobic membrane materials. A drastic flux decline was obtained when filtering crude sunflower oil through different types of alumina membranes. Purified sunflower oil, with or without added free fatty acids, did not show any important fouling during crossflow microfiltration, suggesting that neither triglycerides nor free fatty acids are involved in the phenomenon to a large extent. By way of contrast, addition of phospholipids to the purified oil caused a drastic flux drop similar to that observed for the crude oil. The presence of small amounts of phospholipids increased the resistance to about 60 to 130% compared to that of the purified oil. The reason is most likely a fast adsorption occurring in the first instants during membrane wetting. Overall the fouling phenomenon is probably due to the fact that the phospholipids form supramolecular structures at the surface of the membrane.
Quality parameters evolution during biodiesel oxidation using Rancimat test
Authors: Lacoste Florence , Lagardere Lionel
Published: April 2003

A study was carried out in order to evaluate the evolution of peroxide value, anisidine value, kinematic viscosity at 40 °C, ester and linolenic acid content, UV absorbency, acid value, polymer and tocopherol content during the oxidation of fatty acid methyl ester (FAME) using the Rancimat test chosen by CEN for measuring oxidation stability of FAME (pr EN 14112). The oxidation curves obtained during Rancimat test were compared with those obtained by the variation of oxidation parameters mentioned above, against the time. All quality parameters studied present visible variation along Rancimat test except UV 270 nm. At the end of Rancimat induction period, the seven samples tested do not meet FAME or oils and fats specifications such as kinematic viscosity, acid value, ester content or peroxide value. Rancimat induction period is well correlated to induction period given by quality parameters (0.963<R2<0.999), but Rancimat induction period is almost 10% higher than induction period given by quality parameters. Main conclusion is that induction period determined by conductivity is well correlated to degradation of quality parameters along Rancimat test.
Determination of trans double bonds in polyunsaturated fatty acid methyl esters from their electron impact mass spectra
Authors: Mjøs Svein Are , Pettersen Jan
Published: April 2003

The geometrical isomers of unsaturated fatty acid methyl esters were analysed by gas chromatography — electron impact mass spectrometry. Distinct differences in the electron impact mass spectra of methylene‐interrupted tri‐ and tetra‐unsaturated fatty acid methyl esters were observed. The differences were particularly related to the geometry of the central double bond in trienes or the two central double bonds in tetraenes. Trans geometry in these positions led to a significant decrease of m/z 79 [C6H7]+, which is the base peak in the all‐cis isomers. Disappearance or significant reductions of ions that are used for the determination of double bond positions in the corresponding cis isomers were also observed in the same spectra. The observed differences may be of help in the identification of double bond geometry in fatty acid isomers.
Oxidation of mixtures of triolein and trilinolein at elevated temperatures
Authors: Kamal‐Eldin Afaf , Velasco Joaquín , Dobarganes Carmen
Published: April 2003

The aim of this study was to investigate how triolein and trilinolein are oxidised at elevated temperatures (60‐220 °C) in mixtures with octadecane, used as a saturated diluent. The percentages of triolein/trilinolein and octadecane and the oxidation conditions (temperature and time) were chosen according to a statistical central composite design. Heating was performed in a Rancimat equipment. The extent of oxidation was assessed by measuring the peroxide value by titration against potassium iodide, total polar compounds by solid‐phase extraction, triacylglycerol polymers by high‐performance size‐exclusion chromatography, and the losses of triolein and trilinolein by gasliquid chromatography. The results indicated that maximum peroxide values were obtained at intermediate temperatures while the formation of polar compounds and polymers were only significant at temperatures above 140 °C. Interestingly, under the conditions used, concentration of octadecane was not significant in spite of the wide temperature range selected. Finally, independently of the concentration of triolein and trilinolein in the sample, at temperatures below 140 °C only losses of trilinolein were observed.
Proposed mechanisms of cholesterol‐lowering action of plant sterols
Authors: Trautwein Elke A. , Duchateau Guus S. M. J. E. , Lin Yuguang , Mel'nikov Sergey M. , Molhuizen Henri O. F. , Ntanios Fady Y.
Published: April 2003

Plant sterols (or phytosterols) are naturally occurring compounds structurally related to cholesterol with different side chain configurations. To date, numerous studies have shown that dietary intake of plant sterols either in their free form or as fatty acid esters is effective at lowering plasma total and low density lipoprotein cholesterol. The main mechanism responsible for the cholesterol‐lowering effect of free and esterified plant sterols is the inhibition of intestinal cholesterol absorption. Several sites within the intestinal tract have been suggested where this inhibition might take place. Different mechanisms, such as competition with cholesterol for solubilisation in dietary mixed micelles, co‐crystallisation with cholesterol to form insoluble mixed crystals, and interference with the hydrolysis process by lipases and cholesterol esterases are believed to contribute to the lowering of serum cholesterol concentrations by plant sterols. There is also emerging evidence that plant sterols interfere with transport‐mediated processes of cholesterol uptake. The consequence of all these actions, although their individual contribution on the overall effect remains to be established, is that intestinal cholesterol absorption is reduced, while more cholesterol is excreted in the faeces.

The aim of this review is to summarise the current understanding concerning the mechanism of action by which plant sterols affect cholesterol metabolism and thus exert their cholesterol‐lowering effect. The review will focus on the gut, e.g. on the physico‐chemical effects at the gastric‐duodenal level, on absorptive site effects, and on intra‐cellular trafficking, i.e. effects at the epithelial cell level.
Simple multifractal cascade model for air pollutant concentration (APC) time series
Authors: Lee Chung‐Kung , Ho Ding‐Shun , Yu Chung‐Chin , Wang Cheng‐Cai , Hsiao Yun‐Hua
Published: April 2003

A simple two‐scale Cantor set with unequal scales and weights was presented for the APC time series. The validity of this multifractal cascade model was examined with a one‐year length of hourly average CO, NO, NO2, O3, PM10 and SO2 observations. This model fits remarkably well the entire spectrum of scaling exponents for the examined APC time series. It was found that the multifractal characteristics of the examined APC time series were closely related to both scale and weight parameters. Moreover, the weight parameter could be used to distinguish the degree of right‐skewness of APC frequency distribution. However, the relationship between the long‐range dependence and model parameters still requires further investigation. Some problems concerning the applicability of multifractal models on air pollution are also discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Assessment of short‐term association between health outcomes and ozone concentrations using a Markov regression model
Authors: Zeghnoun Abdelkrim , Czernichow Pierre , Declercq Christophe
Published: April 2003

Longitudinal binary data are often used in panel studies where short‐term associations between air pollutants and respiratory health outcomes are investigated. A Markov regression model in which the transition probabilities depend on the covariates, as well as the past responses, was used to study the short‐term association between daily ozone (O3) concentrations and respiratory health outcomes in a panel of schoolchildren in Armentières, Northern France. The results suggest that there was a small but statistically significant association between O3 and children's cough episodes. A 10 μg/m3 increase in O3 concentrations was associated with a 13.9 % increase in cough symptoms (CI 95% = 1.2–28.1%).

The use of a Markov regression model can be useful as it permits one to address easily both the regression objective and the stochastic dependence between successive observations. However, it is important to verify the sensitivity of the Markov regression parameters to the time‐dependence structure.

In this study, it was found that, although what happened on the previous day was a strong predictor of what happened on the current day, this did not contradict the O3‐respiratory symptom associations. Compared to the Markov regression model, the signs of the parameter estimates of marginal and random‐intercept models remain the same. The magnitudes of the O3 effects were also essentially the same in the three models, whose confidence intervals overlapped. Copyright © 2003 John Wiley & Sons, Ltd.
Improving the precision of longitudinal ecological surveys using precisely defined observational units
Authors: Ryan Daniel A. J. , Heyward Andrew
Published: April 2003

In ecological longitudinal studies, it is difficult to precisely define an observational unit. In many cases the investigator must decide between permanent observational units or observational units with no permanent markers (re‐established each year). The latter choice is appealing as there are no maintenance costs, but the loss of precision in a longitudinal study can be severe. In this article, we analytically demonstrate that by not permanently and precisely marking observational units in a longitudinal study, the efficiency can be reduced, or the cost increased, or both. The magnitude of loss is illustrated for a coral reef benthic survey where precision was reduced by as much as a factor of 12. General formulae to estimate the relative efficiency of ecological surveys based on different levels of observational unit markings are also presented. Copyright © 2003 John Wiley & Sons, Ltd.
Spatial covariance modelling in a complex coastal domain by multidimensional scaling
Authors: Løland Anders , Høst Gudmund
Published: April 2003

In aquatic studies, spatial interactions may be both easier to interpret and to quantify by using water distance than by using geographic distance. The water distance is the shortest path between those two sites that may be traversed entirely over water. One problem is that water distances may be non‐Euclidean, and thus covariance and variogram functions are not necessarily valid when using the water distance as a distance metric. Another problem is that the computation of water distances for a large set of spatial locations is computationally expensive. Our alternative is a computationally efficient method for calculation of a Euclidean approximation to water distances. The first step of the method is to define a triangular grid covering the complex domain of interest. Using this triangular grid, we pre‐compute approximate water distances using a graph search algorithm. These water distances are then approximated by multidimensional scaling, giving a Euclidean space. Finally, we use linear interpolation to move the data locations into the new Euclidean space. By using this method, subsequent computations of water distances between any locations can be done very fast and the method leads to a theoretically valid spatial covariance model. We apply our method to herring data from the Vestfjord system in Northern Norway. Copyright © 2003 John Wiley & Sons, Ltd.
A general model for predicting brown tree snake capture rates
Authors: Engeman Richard M. , Paige Groninger N. , Vice Daniel S.
Published: April 2003

The inadvertent introduction of the brown tree snake (Boiga irregularis) to Guam has resulted in the extirpation of most of the island's native terrestrial vertebrates, has presented a health hazard to small children, and also has produced economic problems. Trapping around ports and other cargo staging areas is central to a program designed to deter dispersal of the species. Sequential trapping of smaller plots is also being used to clear larger areas of snakes in preparation for endangered species reintroductions. Traps and trapping personnel are limited resources, which places a premium on the ability to plan the deployment of trapping efforts. In a series of previous trapping studies, data on brown tree snake removal from forested plots was found to be well modeled by exponential decay functions. For the present article, we considered a variety of model forms and estimation procedures, and used capture data from individual plots as random subjects to produce a general random coefficients model for making predictions of brown tree snake capture rates. The best model was an exponential decay with positive asymptote produced using nonlinear mixed model estimation where variability among plots was introduced through the scale and asymptote parameters. Practical predictive abilities were used in model evaluation so that a manager could project capture rates in a plot after a period of time, or project the amount of time required for trapping to reduce capture rates to a desired level. The model should provide managers with a tool for optimizing the allocation of limited trapping resources. Copyright © 2003 John Wiley & Sons, Ltd.
Pesticide dispersion–advection equation with soil temperature effect
Authors: Paraiba Lourival Costa , Pulino Petronio
Published: April 2003

A dispersion–advection equation, denoted as a DAPESTE model, of one‐dimensional evolution to simulate pesticide leaching in soil with a sinusoidal function to describe the daily average soil temperature at different depths is presented. In numerical simulation, the finite element method (FEM) will be used for space semi‐discretization and the regressive Eüler method (REM) for time discretization. It will be used as an FEM for dispersion–advection problems in which the advective transport predominates over the dispersive one. Let us suppose that the pesticide diffusivities in the gaseous and aqueous soil phases depend on the soil temperature. In this way, the effective hydrodynamic dispersion coefficient of the dispersion–advection equation will depend on the soil temperature. The pesticide air–water partition coefficient of the Henry law, varying with temperature, will be determined by the Clausius–Clapeyron equation. The van't Hoff equation will be used to determine the temperature dependence of the pesticide soil sorption coefficient. The Arrhenius equation will be used to estimate the effect of the soil temperature on the pesticide degradation rate. These temperature dependence relationships can help comprehend the pesticide behavior in the soil under different scenarios of the soil temperatures, especially in pesticide concentration leaching and its half‐life in soil. Copyright © 2003 John Wiley & Sons, Ltd.
Pilot‐aided acquisition algorithms for asynchronous
Authors: Xiao Pei , Ström Erik
Published: April 2003

The problem of estimating propagation delays of orthogonally modulated signals in asynchronous DS‐CDMA systems over time‐varing Rayleigh‐fading channels is treated in this paper. The maximum likelihood (ML) estimator and its unaffordable complexity for implementation are discussed. Some suboptimal solutions, e.g., whitened sliding correlator, MMSE estimator, subspace‐based estimator, approximate ML estimator, are proposed to combat the multiple access interference in the fading channels. The performance of these estimators are evaluated with the computer simulations and shown to have better acquisition performance than the standard sliding correlator. They also achieve reduced computational complexity compared with the ML estimator, while maintaining an acceptable performance degradation. Copyright © 2003 AEI
Combining Galois with complex field coding for space–time communications
Authors: Wang Renqiu , Wang Zhengdao , Giannakis Georgios B.
Published: April 2003

A joint scheme combining error‐control coding (ECC) with complex‐field coding (CFC) is proposed for space–time communications through flat or frequency‐selective fading multiple‐input multiple‐output (MIMO) channels. It is shown that the diversity gain of this joint coding scheme is the product of the free distance of the ECC, the complex‐field block encoder size, and the number of receiving antennas, which is computationally prohibitive to achieve using ECC alone. The decoding complexity with the proposed iterative decoder is comparable to a system without CFC. Numerical simulations for perfectly interleaved and HIPERLAN channels with both single and multiple antennas show great potential of the proposed joint coding scheme. Copyright © 2003 AEI
Co‐channel interference mitigation in GSM networks by iterative estimation of channel and data
Authors: Lončar Maja , Mecklenbräuker Christoph F. , Müller Ralf R.
Published: April 2003

In multiple‐access communication systems several users share the system resources, thus creating co‐channel interference to each other. Multiuser detection, applied at the receiver side, is a powerful technique to combat co‐channel interference, in contrast to single‐user approaches that treat the interference as additive noise. In this paper, we investigate the feasibility of achieving increased spectral efficiency in GSM‐like TDMA networks by applying multiuser detection. We focus on downlink operation and consider two mobile users that share the same physical channel within the same cell or in two adjacent cells. No synchronization between the base stations is assumed. Mobile terminals exploit multiple receiving antennas. We propose a simple iterative receiver algorithm that performs joint channel and data estimation. Results of simulations that evaluate the receiver's performance are presented. Copyright © 2003 AEI
Traditions in monkeys
Authors: Perry Susan , Manson Joseph H.
Published: April 2003

Traditions, defined as relatively long‐lasting behavioral practices shared among members of a group partly via social learning, were studied in monkeys, specifically Japanese macaques, before being studied in great apes. Although apes and humans may share some social learning capacities that are absent in monkeys, a complete understanding of the roots of human culture requires attention to the socioecological conditions favoring traditions, however generated, in animals generally and in multiple behavioral domains. Using the four criteria of intergroup variation, observation of the origin and spread of a novel behavior, dissemination patterned according to age or kinship, or individuals' close observation of others' performance of the behavior before engaging in it, over twenty‐five behaviors have been nominated as traditions in free‐ranging monkey populations. Tolerant gregariousness has been proposed to increase the likelihood of the emergence of traditions in any behavioral domain. Omnivory and extractive foraging should favor the emergence of foraging‐related traditions; strong cooperative relationships and flexible coalitionary structure should favor the emergence of social conventions that function to test social bonds. These conditions are taxonomically widespread. Thus, the current restriction of most reported free‐ranging monkey traditions to two taxa (Macaca fuscata and Cebus) is likely to reflect variation in primatologists' research goals, methods, and concepts rather than real interspecific variation in the propensity to generate traditions.
Is culture a golden barrier between human and chimpanzee?
Authors: Boesch Christophe
Published: April 2003

Culture pervades much of human existence. Its significance to human social interaction and cognitive development has convinced some researchers that the phenomenon and its underlying mechanisms represent a defining criterion for humankind. However, care should be taken not to make hasty conclusions in light of the growing number of observations on the cultural abilities of different species, ranging from chimpanzees and orangutans to whales and dolphins. The present review concentrates on wild chimpanzees and shows that they all possess an extensive cultural repertoire. In the light of what we know from humans, I evaluate the importance of social learning leading to acquisition of cultural traits, as well as of collective meaning of communicative traits. Taking into account cross‐cultural variations in humans, I argue that the cultural abilities we observe in wild chimpanzees present a broad level of similarity between the two species.
Cultural panthropology
Authors: Whiten Andrew , Horner Victoria , Marshall‐Pescini Sarah
Published: April 2003

Culture, in the most basic sense of “tradition,” has been shown to exist in many species. There is more to the phenomenon of culture in humans, however, than the mere existence of traditions. Thus, rather than expecting that culture can be assigned to living or ancestral species in an all‐or‐none fashion, reconstruction of the evolution of this uniquely complex phenomenon is likely to depend on successfully teasing apart its components, which may have evolved in a somewhat mosaic fashion. In this paper, we dissect ten different aspects of human culture and offer evidence that most of them are manifested in chimpanzees, even if in limited ways, permitting inferences about the cultural profile of our common ancestor. The aspects of culture examined include large‐scale patterns of behavioral variation across populations, the mechanisms available for social transmission, and cultural contents. The contrasts thus drawn for humans and chimpanzees offer a framework for cultural comparisons between other taxa from the past and present.
The evolution of culture: New perspectives and evidence
Authors: Janson Charles H. , Smith Eric A.
Published: April 2003

This and the next issue of Evolutionary Anthropology are devoted to presenting the most recent advances in our understanding of the evolution of culture in non‐human primates and humans. This effort was stimulated in part by the recent explosion of comparative evidence for extensive communicative and material culture in two great apes, chimpanzees1 and orangutans.2 Before this evidence accumulated, it was easy for anthropologists to maintain that examples of non‐human primate culture were little more impressive than those put forward for many other non‐human species, and thus they could leave intact the seemingly huge gap between animal and human culture. The overall purpose of this special pair of issues of Evolutionary Anthropology is to ask how and why culture has changed over evolutionary time from non‐primates to non‐human primates to early hominins to modern humans.
Genetic alterations in primary cutaneous CD30+ anaplastic large cell lymphoma
Authors: Mao Xin , Orchard Guy , Lillington Debra M. , Russell‐Jones Robin , Young Bryan D. , Whittaker Sean
Published: April 2003

Primary cutaneous CD30+ anaplastic large cell lymphoma (C‐ALCL) represents a distinct clinical subtype of CD30+ anaplastic large cell lymphomas. The etiology and underlying molecular pathogenesis of C‐ALCL remain unclear. This study aimed to investigate genetic changes in C‐ALCL. Comparative genomic hybridization (CGH) analysis of 23 DNA samples from 15 C‐ALCL cases identified chromosome imbalances (CI) in 10 samples from eight cases (43%). The mean number of CI per sample was 2.09 ± 3.86, with gains (2.00 ± 3.85) more common than losses (0.09 ± 0.29). The most frequent CI were gains of 1/1p and 5 (50%) and 6, 7, 8/8p, and 19 (38%). Microarray‐based CGH analysis of six DNA samples from five cases with CI revealed genomic imbalances (GI) in all of the cases studied. This included oncogene copy number gains of FGFR1 (8p11) in three cases, and NRAS (1p13.2), MYCN (2p24.1), RAF1 (3p25), CTSB (8p22), FES (15q26.1), and CBFA2 (21q22.3) in two cases. Real‐time PCR analysis of nine DNA samples from eight cases with CI and GI detected amplifications of CTSB and RAF1 in seven cases (88%), REL (2p13p12) and JUNB (19p13.2) in six cases (75%), and MYCN and YES1 (18p11.3) in four cases (50%). Immunohistochemical staining of paraffin sections from six cases demonstrated expression of JUNB protein in five cases and BCL2 in three cases. These results reveal a consistent pattern of genetic alterations in C‐ALCL and provide the molecular basis for further investigation of this disease. © 2003 Wiley‐Liss, Inc.
Chromosomal instability in pancreatic ductal cells from patients with chronic pancreatitis and pancreatic adenocarcinoma
Authors: Moskovitz Alexander H. , Linford Nancy J. , Brentnall Teresa A. , Bronner Mary P. , Storer Barry E. , Potter John D. , Bell Richard H. , Rabinovitch Peter S.
Published: April 2003

Pancreatic adenocarcinoma is a disease with high mortality for which chronic pancreatitis confers a markedly increased risk. We hypothesize that chromosome instability and genomic damage occur in pre‐neoplastic pancreatic ductal epithelium, and that this damage may be related to oxidative stress. We used dual‐color fluorescence in situ hybridization with centromere probes and locus‐specific arm probes for chromosome arms 11q, 17p, and 18q to identify genomic instability in cultures of normal‐appearing human pancreatic ductal epithelium from normal organ donor controls compared to patients with chronic pancreatitis or pancreatic adenocarcinoma. To examine early pancreatic tumorigenesis, we studied only normal‐appearing pancreatic ductal cells adjacent to pancreatitis or carcinoma. We found that, compared to the finding in normal controls, chromosomal abnormalities are present in normal‐appearing human pancreatic ductal epithelia obtained from patients with chronic pancreatitis or pancreatic adenocarcinoma. Furthermore, these chromosomal abnormalities could be induced in cultured pancreatic ductal epithelium from normal organ donors by chronic exposure to dilute hydrogen peroxide, suggesting that oxidative stress may contribute to the development of chromosomal instability in the pancreas. These results elucidate a potential mechanism linking chronic pancreatitis to pancreatic cancer and suggest that chromosomal instability may be an early event in the pathogenesis of pancreatic cancer. © 2003 Wiley‐Liss, Inc.
The presence of multiple regions of homozygous deletion at the CSMD1 locus in oral squamous cell carcinoma question the role of CSMD1 in head and neck carcinogenesis
Authors: Toomes Carmel , Jackson Andrew , Maguire Kristie , Wood Joseph , Gollin Susanne , Ishwad Chandramohan , Paterson Ian , Prime Steven , Parkinson Kenneth , Bell Sandra , Woods Geoffrey , Markham Alexander , Oliver Richard , Woodward Robert , Sloan Philip , Dixon Michael , Read Andrew , Thakker Nalin
Published: April 2003

We and others previously identified a region of hemizygous or homozygous deletion at chromosome band 8p23 in oral and oropharyngeal squamous cell carcinomas (OSCCs) and many other cancer types, suggesting the presence of a tumor‐suppressor gene (TSG) in this region. Recently, based on a single region of homozygous deletion in head and neck squamous cell carcinomas (HNSCC), a putative TSG, CUB and sushi multiple domains‐1 (CSMD1), has been identified. In the present study, we mapped three OSCC cell lines with previously described homozygous deletions at a high resolution onto a detailed physical map. Critically, this map covered a wider region than that used in previous studies, and in contrast to these studies, our results revealed multiple regions of homozygous deletion within a small interval on 8p23. To investigate this deletion pattern further, we generated a panel of 34 sequence tagged site (STS) markers spanning the region and tested these three cell lines and an additional 34 OSCC cell lines, identifying homozygous deletions in a further four. Combining the results from all seven deleted cell lines identified three non‐overlapping regions of homozygous deletion. This complex pattern could be consistent with the presence of multiple TSGs or one very large TSG in this region, and/or specific chromosomal instability. CSMD1 spans two of the three deleted regions and, therefore, would appear to be an excellent candidate for a TSG. However, deletion mapping with STSs corresponding to the exons of CSMD1 shows that some of the deletions do not interrupt its coding region, and in other cell lines the coding region is interrupted by two discontinuous homozygous deletions, suggesting the presence of redundant deletions. These results call into question whether the CSMD1 gene is the 8p23 TSG or whether this or any other genes at this locus are involved in the development of OSCC. © 2003 Wiley‐Liss, Inc.
Peculiar structure and location of 9p21 homozygous deletion breakpoints in human cancer cells
Authors: Florl Andrea R. , Schulz Wolfgang A.
Published: April 2003

The CDKN2A tumor‐suppressor gene in chromosome band 9p21 encoding CDKN2A (also known as p16, INK4A), a negative regulator of cyclin‐dependent kinases, and p14ARF1, an activator of TP53, is inactivated in many human cancers by point mutations, promoter hypermethylation, or deletions. Homozygous deletions predominate in certain cancer types (e.g., bladder cancers). To understand why deletions are unusually prevalent at this locus, deletions in bladder and renal cancer cell lines were mapped in detail and several deletion breakpoints cloned. Deletions were interstitial and encompassed 0.1 to >30 Mb. Most deletion breakpoints were located in or close to LINE‐1 retrotransposon clusters. Therefore, deletions of CDKN2A may be facilitated by the presence of LINE‐1 clusters that flank the locus. All cloned junctions were products of non‐homologous recombination and consistently contained exact 2‐bp microhomologies. Microhomologies are otherwise hallmarks of DNA double‐strand break repair by non‐homologous end joining, but the consistent size found at the CDKN2A deletion junctions is difficult to reconcile with the known properties of this process. Therefore, an unknown mechanism appears to be involved in the generation of CDKN2A deletions during carcinogenesis. © 2003 Wiley‐Liss, Inc.