bluuebunny/crossref_metadata_2025 huggingface dataset:
Genes expressed in the developing endocrine pancreas and their importance for stem cell and diabetes research
Authors: Wells James M.
Published: June 2003

The genes that regulate endocrine pancreas development, maintain adult endocrine cells, and stimulate progenitor/stem cells during regeneration remain largely unstudied. There is ample evidence that many of the genes involved in endocrine pancreas development also function in the homeostasis of the adult islet. In light of the potential benefits to diabetic research, it is surprising that there is little information about the genes expressed throughout the ontogeny of the endocrine pancreas. In the past few years, efforts have been made to establish the Endocrine Pancreas Consortium database (EPConDB), in which many of the genes expressed in the developing endocrine pancreas are in a database with a corresponding publicly available clone bank. In addition, advances in microarray technology now allow for a quantitative expression analysis of thousands of genes simultaneously, which makes it possible to generate a quantitative catalog of the genes expressed at each step of endocrine differentiation, from embryonic endoderm to mature beta cells. In this review, I will discuss how genes discovered by virtue of their role in endocrine pancreas development may function in the maintenance of pancreatic stem cells and the regeneration of islets. I will further summarize the recent advances in genomics‐based studies of the developing endocrine pancreas and will discuss how they might impact on the discovery of diagnostics and research into stem cell–based approaches for the treatment of diabetes. Copyright © 2003 John Wiley & Sons, Ltd.
Increase in adenosine A1 receptor gene expression in the liver of streptozotocin‐induced diabetic rats
Authors: Liu I. M. , Tzeng T. F. , Tsai C. C. , Lai T. Y. , Chang C. T. , Cheng J. T.
Published: June 2003

Background

Adenosine A1 receptor (A1‐AR) activation can lower plasma glucose in diabetic rats lacking insulin. We investigated the change in A1‐AR gene expression in diabetic rats.

Methods

The incorporation of [U‐14C]‐glucose into glycogen was carried out to evaluate the effect of N6‐cyclopentyladenosine (CPA) on glucose utilization in vitro. The plasma glucose concentration was assessed by the glucose oxidase method. The mRNA and protein levels of A1‐AR in isolated liver were detected by Western blotting analysis and Northern blotting analysis, respectively.

Results

The effect of CPA, an agonist of A1‐AR, on glycogen incorporation in hepatocytes isolated from streptozotocin‐induced diabetic rats (STZ‐diabetic rats) was more marked than that from the normal rats. However, similar glycogen synthesis was not modified by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), an activator of protein kinase C, in the isolated hepatocytes from both the normal and the STZ‐diabetic rats. A change in response at the receptor level can thus be considered. The mean level of liver mRNA transcripts encoding A1‐AR was increased in STZ‐diabetic rats to about 250% of that in normal rats. Exogenous insulin at a dose sufficient to normalize the plasma glucose of STZ‐diabetic rats reversed the mRNA level of A1‐AR in the liver after a four‐day treatment. Similar results were also observed in STZ‐diabetic rats that received treatment with phlorizin for four days. Moreover, the protein level of A1‐AR was higher in the liver of STZ‐diabetic rats than that in the normal rats. Similar treatment with exogenous insulin or phlorizin reversed the elevated protein level of A1‐AR in the liver of STZ‐diabetic rats to near the normal level. Therefore, correction of hyperglycemia in STZ‐diabetic rats can reverse the higher gene expression of A1‐AR in liver.

Conclusions

The obtained results suggest that an increase in plasma glucose is responsible for the higher gene expression of A1‐AR in the liver of STZ‐diabetic rats. Copyright © 2003 John Wiley & Sons, Ltd.
Recall of severe hypoglycaemia and self‐estimated state of awareness in type 1 diabetes
Authors: Pedersen‐Bjergaard Ulrik , Pramming Stig , Thorsteinsson Birger
Published: June 2003

Background

The ability of people with insulin‐treated diabetes to remember severe hypoglycaemia and the consistency of their self‐estimated awareness of hypoglycaemia are not well documented but are important in clinical practice. The aim of this study is to assess recall of severe hypoglycaemia in patients with type 1 diabetes and to evaluate the feasibility of a simple method for clinical classification of the awareness of hypoglycaemia.

Methods

A one‐year prospective study was performed on a cohort of patients with type 1 diabetes (n = 230). The rate of severe hypoglycaemia reported retrospectively at the end of the study was compared to the prospectively recorded rate during the study period. Self‐estimated awareness was explored in questionnaires at baseline and at the end, and assessments were evaluated by the occurrence of severe hypoglycaemic episodes.

Results

Almost 90% of the participants correctly recalled whether they had had severe hypoglycaemia. However, those with high prospectively recorded numbers had incomplete recall, resulting in a 15% underestimation of the overall rate. On the basis of the answer to the question ‘Do you recognise symptoms when you have a hypo?’, the population was classified into three groups: 40% with normal awareness, 47% with impaired awareness and 13% with unawareness. The groups with impaired awareness and unawareness had 5.1 and 9.6 times higher rates of severe hypoglycaemia, respectively, compared to the group with normal awareness (p < 0.001).

Conclusion

People with type 1 diabetes generally remember severe hypoglycaemic episodes during a one‐year period. A simple method is proposed for classifying the state of awareness of hypoglycaemia in clinical practice. Copyright © 2003 John Wiley & Sons, Ltd.
Current Awareness in Geriatric Psychiatry
Authors:   John Wiley & Sons, Ltd.
Published: June 2003

In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of geriatric psychiatry. Each bibliography is divided into 9 sections: 1 Books, Reviews & Symposia; 2 General; 3 Assessment; 4 Epidemiology; 5 Therapy; 6 Care; 7 Dementia; 8 Depression; 9 Psychology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted
Preparation of affinity carriers for the study of binding properties of aspartic proteinases
Authors: Kučerová Zdenka , Tichá Marie
Published: June 2003

We have chosen aromatic amino acids and their derivatives as ligands for the affinity chromatography of aspartic proteinases (pepsins and pepsinogens). The following ligands were used: L‐tyrosine, L‐phenylalanine, tyramine, and N‐acetyl‐L‐phenylalanine, and their iodinated derivatives (mono‐ and di‐substituted) with free or blocked amino group. Two types of reactions were used for coupling ligands to Sepharose activated with divinyl sulfone (DVS): via amino group or via carboxyl group. Ligands with free amino group were directly coupled to the activated matrix (L‐tyrosine, 3‐iodo‐L‐tyrosine, 3,5‐diiodo‐L‐tyrosine, L‐phenylalanine, 4‐iodo‐L‐phenylalanine, tyramine); ligands with blocked amino group (N‐acetyl‐L‐phenylalanine, BOC‐L‐tyrosine, BOC‐3,5‐diiodo‐L‐tyrosine; BOC: tert‐butoxy carbonyl) were coupled to Sepharose containing linked ethylenediamine using the carbodiimide reaction. Alternatively, ethylenediamine was bound to free carboxyl croup using the same reaction and these ligand derivatives reacted with divinyl sulfone activated Sepharose. The prepared affinity carriers were used to study the binding properties of porcine pepsin and pepsinogen.
Determination of total oncopterin, neopterin and biopterin in human urine by high performance liquid chromatography with solid phase extraction
Authors: Tomandl Josef , Tallova Jaroslava , Tomandlova Marie , Palyza Vladimir
Published: June 2003

A new, sensitive method for the determination of oncopterin, biopterin, and neopterin in human urine has been developed using SPE with 6,7‐dimethylpterin as internal standard and gradient HPLC with fluorescence detection. SPE was tested for the pre‐treatment of urine samples on different types of sorbents (strong ion exchange resins, polar adsorbents, and reversed‐phase sorbents). RP‐SPE with subsequent evaporation of eluate has been found to be the most appropriate. The extraction efficiency exceeded 95% for all selected pterins. The extracted pterins were subsequently analyzed on a Purospher RP‐18 RP column. The LOD of oncopterin was 1.43 nmol/L of urine. The intra‐day and inter‐day imprecision at a physiological oncopterin concentration never exceeded 10%. The potential of this method was tested using urine samples of healthy volunteers and cancer patients without methotrexate therapy.
Comparison of enantioseparation of selected benzodiazepine and phenothiazine derivatives on chiral stationary phases based on β‐cyclodextrin and macrocyclic antibiotics
Authors: Tesařová Eva , Bosáková Zuzana
Published: June 2003

Enantioselective separation of some phenothiazine and benzodiazepine derivatives was studied on six different chiral stationary phases (CSPs) in HPLC. Selected CSPs, with respect to the structure of the separated compounds, were either based on β‐cyclodextrin chiral selectors – underivatized β‐cyclodextrin and hydroxypropyl ether β‐cyclodextrin, or on macrocyclic antibiotics – vancomycin, teicoplanin, teicoplanin aglycone, and ristocetin A. Measurements were carried out in a reversed‐phase separation mode. The influence of mobile phase composition on retention and enantioseparation was studied. Benzodiazepines could be enantioresolved with almost all the chiral stationary phases used, except for the vancomycin‐bonded CSP. Peak coalescence of oxazepam and lorazepam was observed if separation was carried out at laboratory temperature. Reduced temperature was required in some instances in order to avoid the on‐column racemization. Separation systems composed of teicoplanin‐bonded CSP and buffer‐methanolic or pure methanolic mobile phases were shown to be suitable even for preparative purposes due to high resolution values of the enantiomers. Enantioseparation of phenothiazine derivatives was more difficult to achieve but it was successful, at least partly, also with both types of the CSPs used (except for levomepromazine).
Determination of oxalate in beer by zone electrophoresis on a chip with conductivity detection
Authors: Masár Marián , Žúborová Mária , Kaniansky Dušan , Stanislawski Bernd
Published: June 2003

The use of a poly(methylmethacrylate) capillary electrophoresis chip, provided with a high sample load capacity separation system (a 8500 nL separation channel combined with a 500 nL sample injection channel) and a pair of on‐chip conductivity detectors, for zone electrophoresis (ZE) determination of oxalate in beer was studied. Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the chip were suppressed and electrophoresis was a dominant transport process in the separations performed on the chip. A low pH of the carrier electrolyte (3.8), implemented by aspartic acid and bis‐tris propane, provided an adequate selectivity in the separation of oxalate from anionic beer constituents and, at the same time, also a sufficient sensitivity in its conductivity detection. Under our working conditions, this anion could be detected at a 0.5 μmol/L concentration also in samples containing chloride (a major anionic constituent of beer) at a 1800 higher concentration. Such a favorable analyte/matrix concentration ratio made possible accurate and reproducible [typically, 2–5% relative standard deviation (RSD) values of the peak areas of the analyte in dependence on its concentration in the sample] determination of oxalate in 500 nL volumes of 20–50‐fold diluted beer samples. Short analysis times (about 200 s), minimum sample preparation, and reproducible migration times of this analyte (0.5–1.0% RSD values) were characteristic for ZE on the chip.
Selective determination of famotidine in human plasma by high performance liquid chromatography in alkaline media with solid phase extraction
Authors: Anzenbacherová Eva , Filipová Karolina , Nobilis Milan , Anzenbacher Pavel
Published: June 2003

A new method is described for the determination of famotidine by solid phase extraction from alkalinized human plasma followed by reversed phase (RP) HPLC in acetonitrile/alkaline buffer with molsidomine as an internal standard. Different acetonitrile/aqueous buffer mobile phases as well as various RP columns were used. Alkaline medium allowed the limit of quantitation to be lowered to 5 ng/mL of plasma as the famotidine gives more intense absorption at about 286 nm (at pH values higher than 7). Moreover, work in alkaline media and at this wavelength is highly selective as peaks corresponding to impurities present in most samples are well separated. A method using a mildly alkaline mobile phase (acetonitrile/10 mM phosphate with 10 mM 1‐heptanesulphonic acid, pH 7.5) was successfully used for determination of famotidine in human plasma in a pharmacokinetic study.
High performance liquid chromatography and capillary electrophoresis determination of sanguinarine in biological matrices
Authors: Kosina Pavel , Ševčík Juraj , Modrianský Martin , Gavenda Aleš , Bednář Petr , Barták Petr , Walterová Daniela , Ulrichová Jitka
Published: June 2003

HPLC and CE methods were employed to determine the quaternary benzo[c]phenanthridine alkaloid sanguinarine in biological matrices (rat hepatocytes, human gingival fibroblasts, feed, porcine faeces, body fluids and tissues). HPLC was carried out on a C18 column using gradient elution and ion pairing techniques with 1‐heptanesulfonic acid as ion pairing agent under acidic conditions. The detection limit for fluorimetric detection at λex = 327 nm and λem = 577 nm was 3 nM sanguinarine. CE analyses were performed in 50 mM phosphate‐Na buffer pH 2.5, with 150 mM SDS used for pre‐concentration by the sweeping effect. This experimental configuration allows injecting the total capillary length with sanguinarine sample. The detection limit for UV detection at 285 nm was 12 nM. Both methods are suitable for analysing submicromolar quantities of sanguinarine in biological materials. The HPLC method is more sensitive than CE because it uses fluorescence detection.
Analysis of 3‐quinuclidinol derivatives by capillary electrophoresis
Authors: Bednář Petr , Barták Petr , Lemr Karel , Ševčík Juraj , Stránský Zdeněk
Published: June 2003

Capillary electrophoresis with indirect UV detection was applied to the analysis of a mixture of 3‐quinuclidinol and its four quaternary derivatives (N‐methyl, N‐ethyl, N‐propyl, and N‐isopropyl derivative). 10 mM imidazole acetate buffer, pH = 4.0 offers suitable detection sensitivity (LOD = 1 μmol L–1) and permits separation of the mixture except for the pair 3‐quinuclidinol–N‐methyl derivative. The separation of all analytes was achieved on addition of 15 mmol L–1 β‐cyclodextrin or 25% (w/w) polyethylene glycol 2000 to the background electrolyte. The optimized method was employed for the analysis of pond water spiked with these analytes. Actual ionic mobilities of the studied compounds were measured using mobility standards (potassium, sodium, tetramethyl‐ and tetrabutylammonium). The migration index was derived as another identification parameter based on migration data and the precision of the obtained values is discussed in brief.
Separation of diastereomers of phosphinic pseudopeptides by capillary zone electrophoresis and reverse phase high‐performance liquid chromatography
Authors: Koval Dušan , Kašička Václav , Jiráček Jiři , Collinsová Michaela
Published: June 2003

Capillary zone electrophoresis (CZE) and reverse phase high‐performance liquid chromatography (RP‐HPLC) were used for separation of diastereomers of phosphinic pseudopeptides in achiral separation media. A set of phosphinic pseudopeptides, i. e. peptides with one peptide bond substituted by phosphinic acid moiety ‐PO2–‐CH2‐ derived from the structure N‐Ac‐Val‐AlaB(‐CH2)Leu‐His‐NH2 synthesized as a mixture of four diastereomers was used. Separations of diastereomers by CZE were carried out in Tris‐phosphate background electrolytes in the pH range 1.1–3.2 and at least partial separation of the four diastereomers of each pseudopeptide was achieved. A routinely used RP‐HPLC method (C18‐silica column and water/acetonitrile/trifluoroacetic acid mobile phase) was also capable of resolving the diastereomers. In addition, since individual diastereomers of majority of the pseudopeptides were isolated by RP‐HPLC it was possible to check the purity of these RP‐HPLC separated diastereomers and to compare the migration order of the diastereomers in CZE with their elution order in RP‐HPLC. The results obtained by CZE and RP‐HPLC demonstrate a complementarity of both methods in analysis and separation of phosphinic pseudopeptides including their diastereomers.
Investigation of the separability of thaumatin by capillary electrophoresis
Authors: Vespalcová Milena , Gregorová Daniela
Published: June 2003

The electrophoretic behaviour of the highly basic protein thaumatin was explored in strongly acid (pH 2) and mildly acid (pH 4.5) separation systems using both bare and coated fused silica capillaries. The separation selectivity for thaumatin I, thaumatin II, and for other sample constituents was insufficient for their baseline separation at pH 2 in an uncoated capillary because the separation efficiency was markedly lower than is common in the electrophoretic separations of proteins. A separation selectivity higher by up to one order of magnitude has been reached at pH 4.5. A pronounced asymmetry of zones, which impaired resolution at this pH, was effectively suppressed by coating of the capillary wall with a polymer. In fact, adsorption on the capillary coating always plays a contributory role whenever a good separation of thaumatin constituents is attained. This indicates that electrochromatographic separation systems based on capillaries coated with the layer of either cationic or hydrophilic uncharged polymer hold promise for the development of methods for thaumatin analysis.
Analysis of phenolic acids in plant materials using HPLC with amperometric detection at a platinum tubular electrode
Authors: Jirovský David , Horáková Daniela , Kotouček Milan , Valentová Kateřina , Ulrichová Jitka
Published: June 2003

The suitability of a simple amperometric platinum tubular detector for HPLC analysis of selected phenolic acids in yacon (Smallanthus sonchifolius, Asteraceae) is reported. The detector offers good overall limits of detection for the phenolic acids of interest. Three different types of extracts from yacon leaves were analyzed and compared with respect to their content of phenolic acids. Caffeic acid was found in all yacon extracts, whereas the content of chlorogenic acid depends more on the extraction procedure used. It has been demonstrated that no complicated and sophisticated equipment is needed and HPLC with amperometric detection seems to be a very useful technique for analysis of plant extracts containing phenolic acids.
Direct determination of valproate in serum by zone electrophoresis–isotachophoresis on a column‐coupling chip
Authors: Ölvecká Eva , Koníková Michaela , Grobuschek Nina , Kaniansky Dušan , Stanislawski Bernd
Published: June 2003

A feasibility study was performed using zone electrophoresis (ZE) coupled on‐line with isotachophoresis (ITP) sample pretreatment on a poly(methyl methacrylate) column‐coupling chip with integrated conductivity detection for direct determination of drugs in serum. Valproic acid (an antiepileptic drug), having a therapeutic range of 0.35–0.69 mmol/L (50–100 mg/L), was a test analyte while reference serum samples served as proteinaceous matrices. ITP provided in the ITP‐ZE combination a multitask sample pretreatment: (1) separation of the analyte from the serum matrix and its concentration into a narrow ITP band, (2) removal of the matrix constituents migrating in the ITP stack from the separation compartment of the chip, (3) ITP stacking of the drug released on a continuous electrophoretic decomposition of the drug‐protein complex. A high sample loadability, closely linked with the use of ITP in the first separation stage, made it possible to inject diluted serum samples with the aid of a 0.95 μL sample channel of the chip. Consequently, a 1–2 μmol/L concentration limit of quantitation for valproate from the response of the conductivity detector in the ZE stage of the combination was reached. The drug could be reliably determined in less than 10 minutes also in instances when its concentration in serum was below the lower value of the therapeutic range. 90–94% recoveries of valproate from serum samples were obtained in its direct ITP‐ZE determination when the filtration of the diluted serum (a 0.45 μm pore size filter) was the only pre‐column sample handling operation. No disturbances attributable to the precipitation of proteins from the loaded samples in the chip channels were detected.
Synthesis of New Polymethyloxazoline Hydrogels by the “Macroinitiator” Method
Authors: Rueda Juan , Suica Raúl , Komber Hartmut , Voit Brigitte
Published: June 2003

New polymethyloxazoline hydrogels are synthesized by the cationic ring‐opening copolymerization of 2‐methyl‐2‐oxazoline and 2,2′‐tetramethylenebis(2‐oxazoline), using random copolymers of chloromethylstyrene and methyl methacrylate, or of chloromethylstyrene and styrene as macroinitiators. The synthesis is carried out in benzonitrile at 110 °C in the presence of potassium iodide, which activates the chloromethyl group as initiating functionality. In general, the hydrogels are obtained very rapidly, with a yield of between 42 and 95 wt.‐%. Besides its initiating function, the macroinitiator also provides the possibility of introducing heterogeneity into the hydrogel structure by forming rigid hydrophobic domains. The hydrogel structures were characterized by high‐resolution magic angle spinning NMR spectroscopy, and their solvent absorption capacity was determined by swelling experiments in solvents of different polarity. The hydrogels showed a maximal swelling degree of 18 g of water and 40 g of methanol, respectively, per gram of the hydrogel.

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Synthesis and Properties of Hydrophilic Polymers, 10
Authors: Pizarro Guadelupe del C. , Marambio Oscar G. , O Mario Jeria , Geckeler Kurt E.
Published: June 2003

Water‐soluble poly[(N‐maleoylglycine)‐co‐(hydroxyethyl methacrylate)] was employed for the separation of a series of metal ions in the aqueous phase using the liquid‐phase polymer‐based retention method. The method is based on the retention of inorganic ions by this polymer in conjunction with membrane filtration and subsequent separation of low‐molecular‐mass species from the polymer complex formed. It is shown that the polymer can bind several metal ions in aqueous solution at pH 3, 5, and 7, for example Cr(II), Co(II), Zn(II), Ni(II), Cu(II), Cd(II), Pb(II) inorganic ions. The interaction of the inorganic ions with the hydrophilic polymer was determined as a function of pH and filtration factor. The water‐soluble polymeric reagent with strong metal‐complexing properties was synthesized and used to separate complexed from non‐complexed ions in the homogeneous phase. The polymer exhibited high retention capability at pH 5 and 7. It was characterized by elemental analysis, FT‐IR, 1H NMR, and 13C NMR spectroscopy, as well as by thermogravimetry. Additionally, viscosimetric measurements of the copolymer were performed at different pH values.

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Polymer‐Dispersed Liquid Crystals Based on Polystyrene and EBBA: Analysis of Phase Diagrams and Morphologies Generated
Authors: Hoppe Cristina E. , Galante María J. , Oyanguren Patricia A. , Williams Roberto J. J.
Published: June 2003

As an example of thermoplastic/liquid crystal blends that do not exhibit a liquid‐liquid immiscibility region in their phase diagrams, a polystyrene (PS)/N‐4‐ethoxybenzylidene‐4′‐butylaniline (EBBA) blend was analyzed. The complete phase diagram was built up using thermal transitions determined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The boundary of the nematic + isotropic region was fitted with the Flory‐Huggins‐Maier‐Saupe model, extended to consider the polydispersity of PS. Main factors controlling the morphologies generated by thermal‐induced phase separation (TIPS) were the initial EBBA concentration in the blend and the cooling rate. Cooling at a fast rate led to small nematic domains with a narrow size distribution. Slow cooling rates led to the coexistence of very large and small dispersed domains. This was because of the large extent of coalescence of the droplets first generated associated with the continuation of the nucleation/growth process in a medium of increasing viscosity. The use of fast cooling rates might be important for the generation of a narrow size‐distribution of nematic droplets by TIPS in polymer‐dispersed liquid crystals (PDLC) used in electrooptical devices.

Micrograph obtained by transmission optical microscopy without crossed polarizers, showing nematic domains dispersed in a glassy matrix arising by a fast cooling of the blend from 130 °C; composition of blend: 70 wt.‐% EBBA.

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Micrograph obtained by transmission optical microscopy without crossed polarizers, showing nematic domains dispersed in a glassy matrix arising by a fast cooling of the blend from 130 °C; composition of blend: 70 wt.‐% EBBA.
Macromolecular Crystal Engineering Based on Segmented Polymers: Influence of Heteroatoms on the Thermal Properties and Crystallization of m,n‐Polyurethanes Derived from Long‐Chain, Heteroatom‐Containing, Monodisperse α,ω‐Diols
Authors: McKiernan Robin L. , Cardoen Grégoire , Boutevin Bernard , Améduri Bruno , Gido Samuel P. , Penelle Jacques
Published: June 2003

Long‐chain heteroatom‐containing telechelic diols with 29–32 atoms in the backbone were synthesized by a one‐step, free‐radical telomerization of 10‐undecene‐1‐ol with commercially available α,ω‐dithiols. The oxygen and sulfur atoms caused a decrease in the melting point and enthalpy of the diols, compared to the corresponding purely aliphatic diols. The heteroatom‐containing α,ω‐diols HO(CH2)11S(CH2)2X(CH2)2S(CH2)11OH, where X = CH2, O, or O(CH2)2O, were reacted in the melt with 1,6‐diisocyanatohexane OCN(CH2)6NCO, producing a series of polyurethanes containing an increasing amount of heteroatoms. Characterization by differential scanning calorimetry, infra‐red spectroscopy, thermogravimetric analysis, and wide angle x‐ray scattering of the m,n‐polyurethane series showed that, like the telechelic diols they were synthesized from, the heteroatoms caused a decrease in the melting point and enthalpy. However, they did not affect either the decomposition temperature or the crystal structure/packing.

Typical decomposition behavior of all the heteroatom‐containing m,6‐polyurethane.

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Typical decomposition behavior of all the heteroatom‐containing m,6‐polyurethane.
Synthesis of Poly(ethylene terephthalate)‐block‐Poly(tetramethylene oxide) Copolymer by Direct Polyesterification of Reactive Oligomers
Authors: Saint‐Loup René , Robin Jean‐Jacques , Boutevin Bernard
Published: June 2003

The object of this study was the synthesis of thermoplastic elastomer compounds by direct copolyesterification of reactive oligomers of poly(ethylene terephthalate) (PET) and of poly(tetramethylene oxide) (PTMO). PET was glycolysed to synthesise hydroxytelechelic oligomers of PET. Commercially available hydroxytelechelic PTMO was modified to synthesise carboxytelechelic oligomers. The chemical structures of these oligomers were investigated by 1H NMR and size exclusion chromatography. Multiblock poly(ester‐ether) was then obtained by polyesterification of the hydroxytelechelic and carboxytelechelic oligomers, using different catalysts and different reaction conditions. The best stoichiometric ratio was determined to lead to the highest Mn. The chemical structure of the synthesised poly(ester‐ether) was investigated by size exclusion chromatography and 1H NMR. The thermal and thermomechanical behaviour of the synthesised poly(ester‐ether) was investigated by differential scanning calorimetry and by dynamic mechanical analysis, and showed a thermoplastic elastomer behaviour. This product could also be an interesting way of chemically recycling PET waste.

Polyesterification of hydroxytelechelic PET with carboxytelechelic PTMO.

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Polyesterification of hydroxytelechelic PET with carboxytelechelic PTMO.
A Comprehensive Experimental and Theoretical Investigation of the Styrene/2‐Ethylhexyl Acrylate Emulsion Copolymerization
Authors: Kammona Olga , Pladis Prokopis , Frantzikinakis Costas E. , Kiparissides Costas
Published: June 2003

In the present study an experimental and theoretical investigation on the styrene/2‐ethylhexyl acrylate emulsion copolymerization is reported. Kinetic experiments were carried out in a laboratory batch reactor, to analyze the effects of the initial styrene mole fraction, non‐ionic surfactant, and initiator concentrations on the reaction kinetics, copolymer composition and particle size distribution of the latex. All kinetic experiments were run through the full conversion. A comprehensive mathematical model was developed to describe the dynamic behavior of the styrene/2‐ethylhexyl acrylate batch emulsion copolymerization. The model includes a detailed kinetic mechanism, the thermodynamics of the emulsion mixture, dynamic molar species balances in the polymer and aqueous phases, the rate of particle formation, and growth and diffusion controlled phenomena. Detailed dynamic species mass balances are derived to follow the evolution of the particle nucleation rate, total number of particles, polymerization rate and particle size distribution in a batch reactor. The proposed particle nucleation mechanism accounts for both homogeneous and micellar particle nucleation. The capabilities of the present model are demonstrated by comparison of model predictions with the experimental data on conversion and particle size distribution (PSD). It is shown that the model is capable of correctly reflecting the time evolution of conversion, particle size and PSD over substantial variations of the process operating conditions.

Comparison of model predictions and experimental measurements on average particle size.

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Comparison of model predictions and experimental measurements on average particle size.
PI3K is a key molecule in the Nrf2‐mediated regulation of antioxidative proteins by hemin in human neuroblastoma cells
Authors: Nakaso Kazuhiro , Yano Hidetaka , Fukuhara Yoko , Takeshima Takao , Wada-Isoe Kenji , Nakashima Kenji
Published: June 2003

Oxidative stress and ferrous metabolism are important in the pathogenesis in Parkinson's disease. In dopaminergic neurons, several stress proteins are upregulated under oxidative stress. To clarify this mechanism, we investigated hemin‐related signal transduction and the induction of oxidative stress‐related proteins in SH‐SY5Y cells. We identified phosphatidylinositol 3‐kinase (PI3K) and Nrf2 as important molecules in the induction of heme oxygenase‐1, thioredoxin, and peroxiredoxin‐I. PI3K‐related signal controlled Nrf2 activation, and consequently, PI3K inhibitors blocked the nuclear translocation of Nrf2 and induction of stress proteins. These observations suggest that PI3K and Nrf2 are key molecules in maintaining suitable conditions under oxidative stress and ferrous metabolism.
Are syn‐ligated (bacterio)chlorophyll dimers energetic traps in light‐harvesting systems?
Authors: Balaban Teodor Silviu
Published: June 2003

A recent study of the stereochemical details of chlorophyll ligation in photosystem I [Balaban et al., Biochim. Biophys. Acta 1556 (2002) 197–207] has revealed that only 14 chlorophylls out of the total 96 are ligated from the same side (syn) as the 17‐propionic acid residue which is esterified with phytol. The syn chlorophylls are carefully surrounding the reaction center forming the inner core antenna system and their ligands have been strongly conserved in several species during evolution. We hypothesize here that the two dimers of closely spaced syn chlorophylls which are encountered within roughly 2 nm of P700 are the ultimate energetic traps of this light‐harvesting system. Structurally very similar bacteriochlorophyll a dimers are encountered within the Fenna–Matthews–Olson protein complex and within the B850 ring of the LH2 complex of purple bacteria. The non‐random disposal of these dimers lends support to our hypothesis that the syn ligation coupled with a strong excitonic interaction leads to the most red‐shifted pigments in light‐harvesting systems. We would like to encourage both theoretical and experimental studies to either prove or disprove this intriguing structure–function conjecture in view of designing efficient artificial light‐harvesting systems.
Pellino2 activates the mitogen activated protein kinase pathway
Authors: Jensen Liselotte E. , Whitehead Alexander S.
Published: June 2003

Engagement of the interleukin‐1 (IL1) and Toll receptors, which are part of the innate immune system, facilitates activation of the transcription factors NF‐κB, Elk‐1 and AP‐1. Pellino1 and Pellino2 have recently been shown to be intermediates in the pathway leading to activation of NF‐κB. Here we demonstrate for the first time that human Pellino2 interacts with TRAF6 (tumor necrosis factor receptor associated factor 6) and that both Pellino1 and Pellino2 also interact with TAK1 (transforming growth factor‐β activated kinase 1). We also show that Pellino2, but not Pellino1, can activate the mitogen activated protein kinase pathway leading to activation of AP‐1 and Elk‐1. These observations suggest a role for the Pellino proteins in the IL1/Toll signaling cascades as scaffold proteins that may regulate signaling branch‐points.
PTEN modulates insulin‐like growth factor II (IGF‐II)‐mediated signaling; the protein phosphatase activity of PTEN downregulates IGF‐II expression in hepatoma cells
Authors: Kang-Park Sukmi , Lee Yoon Ik , Lee Young Ik
Published: June 2003

The PTEN gene (phosphatase and tensin homologous on chromosome 10) is frequently mutated or deleted in a number of malignancies including human hepatocellular carcinoma (HCC). We reported previously that the hepatitis B virus X (HBx) protein, known to be a causative agent in the formation of HCC, activates insulin‐like growth factor II (IGF‐II) expression through Sp1 phosphorylation by protein kinase C (PKC) or mitogen‐activated protein kinase (MAPK) signaling. In this report we demonstrate that the PTEN effect on HBx induced IGF‐II activation in a hepatoma cell line. Expression of PTEN and IGF‐II was inversely related in different hepatoma cell lines. PTEN expression induced decreased Sp1 DNA binding by dephosphorylating Sp1 and interfered with transcriptional transactivation of IGF‐II by HBx in hepatoma cells. The protein phosphatase activity was involved in PTEN downregulation of IGF‐II transcription through downregulation of MAPK, MAPK kinase phosphorylation and PKC translocation. Our data suggest that PTEN blocks Sp1 phosphorylation in response to HBx, by inactivating PKC, MAPK and MAPK kinase which eventually downregulate IGF‐II expression, during the formation of HCC.
Drosophila chk2 plays an important role in a mitotic checkpoint in syncytial embryos
Authors: Xu Jinhua , Du Wei
Published: June 2003

Drosophila chk2 (Dmchk2, also called Dmnk) plays a crucial role in the DNA damage response pathway mediating cell cycle arrest and apoptosis [Xu et al., FEBS Lett. 508 (2001) 394–398; Peters et al., Proc. Natl. Acad. Sci. USA 99 (2002) 11305–11310]. In this study, the role of Dmchk2 in early embryogenesis was investigated. In the absence of Dmchk2 function, abnormal nuclei accumulate in the cortex of the syncytial embryo. We show that the abnormal nuclei result from a failure of chromosome segregation probably due to damaged or incomplete replicated DNA. Importantly, this Dmchk2 phenotype is partially suppressed by reducing the gene dosage of polo or stg. As Polo‐like kinase was shown to colocalize and coimmunoprecipitate with Chk2 [Tsvetkov et al., J. Biol. Chem. 278 (2003) 8468–8475] in mammals, these observations suggest that polo might be a key target of Dmchk2 in regulating mitotic entry in response to DNA damage or replication block.
The R1 subunit of herpes simplex virus ribonucleotide reductase has chaperone‐like activity similar to Hsp27
Authors: Chabaud Stéphane , Lambert Herman , Sasseville A.Marie-Josée , Lavoie Hugo , Guilbault Claire , Massie Bernard , Landry Jacques , Langelier Yves
Published: June 2003

HSV‐2 R1, the R1 subunit of herpes simplex virus (HSV) ribonucleotide reductase, protects cells against apoptosis. Here, we report the presence in HSV‐2 R1 of a stretch exhibiting similarity to the α‐crystallin domain of the small heat shock proteins, a domain known to be important for oligomerization and cytoprotective activities of these proteins. Also, the HSV‐2 R1 protein, which forms multimeric structures in the absence of nucleotide, displayed chaperone ability as good as Hsp27 in a thermal denaturation assay using citrate synthase. In contrast, mammalian R1, which does not contain an α‐crystallin domain, has neither chaperone nor anti‐apoptotic activity. Thus, we propose that the chaperone activity of HSV‐2 R1 could play an important role in viral pathogenesis.
Management of cellular energy by the AMP‐activated protein kinase system
Authors: Hardie D.Grahame , Scott John W , Pan David A , Hudson Emma R
Published: June 2003

The AMP‐activated protein kinase is a sensor of cellular energy status that is found in all eukaryotic cells. It is activated by rising AMP and falling ATP by a complex mechanism that results in an ultrasensitive response. The functions of the different domains on the three subunits of the αβγ heterotrimer are slowly being unravelled, and a recent development has been the identification of a glycogen‐binding domain on the β subunit. Along with findings that high cellular glycogen represses kinase activation, this suggests that the system may be a sensor of glycogen content as well as of AMP and ATP. New insights have been obtained into the sequence and structural features by which the kinase recognises its downstream target proteins, and these are discussed. Once activated by depletion of cellular energy reserves, the kinase switches on ATP‐producing catabolic pathways and switches off ATP‐consuming processes, both via direct phosphorylation of regulatory proteins and via indirect effects on gene expression. A survey of the range of downstream targets for this important signalling pathway is presented.
Search for new cyclic AMP‐binding proteins
Authors: Dremier S. , Kopperud R. , Doskeland S.O. , Dumont J.E. , Maenhaut C.
Published: June 2003

Today, there is evidence that the cAMP‐dependent kinases (PKA) are not the only intracellular receptors involved in intracellular cAMP signalling in eukaryotes. Other cAMP‐binding proteins have been recently identified, including some cyclic nucleotide‐gated channels and Epac (exchange protein directly activated by cAMP) proteins. All these proteins bind cAMP through conserved cyclic nucleotide monophosphate‐binding domains. However, all putative cAMP‐binding proteins having such domains, as revealed by computer analysis, do not necessarily bind cAMP, indicating that their presence is not a sufficient criteria to predict cAMP‐binding property for a protein.
Unravelling the activation mechanisms of protein kinase B/Akt
Authors: Scheid Michael P. , Woodgett James R.
Published: June 2003

Over the past decade, protein kinase B (PKB, also termed Akt) has emerged as an important signaling mediator between extracellular cues and modulation of gene expression, metabolism, and cell survival. The enzyme is tightly controlled and consequences of its deregulation include loss of growth control and oncogenesis. Recent work has better characterized the mechanism of PKB activation, including upstream regulators and secondary binding partners. This minireview refreshes some old concepts with new twists and highlights current outstanding questions.
cAMP effector mechanisms. Novel twists for an ‘old’ signaling system
Authors: Kopperud Reidun , Krakstad Camilla , Selheim Frode , Døskeland Stein Ove
Published: June 2003

Cyclic AMP (cAMP) has traditionally been thought to act exclusively through cAMP‐dependent protein kinase (cAPK, PKA), but a growing number of cAMP effects are not attributable to general activation of cAPK. At present, cAMP is known also to directly regulate ion channels and the ubiquitous Rap guanine exchange factors Epac 1 and 2. Adding to the sophistication of cAMP signaling is the fact that (1) the cAPK holoenzyme is incompletely dissociated even at saturating cAMP, the level of free R subunit of cAPK being able to regulate the maximal activity of cAPK, (2) cAPK activity can be modulated by oxidative glutathionylation, and (3) cAPK is anchored close to relevant substrates, other signaling enzymes, and local compartments of cAMP. Finally, we will demonstrate an example of fine‐tuning of cAMP signaling through synergistic induction of neurite extensions by cAPK and Epac.
Identification of RIP140 as a nuclear receptor cofactor with a role in female reproduction
Authors: Parker Malcolm , Leonardsson Göran , White Roger , Steel Jennifer , Milligan Stuart
Published: June 2003

Nuclear receptors function as ligand‐dependent transcription factors by recruiting cofactors that remodel chromatin and recruit the transcription machinery. RIP140 (receptor interacting protein with a molecular weight of 140 kDa) is a widely expressed corepressor that has the potential to inhibit the transcriptional activity of most, if not all nuclear receptors. Mice devoid of RIP140 indicate that it plays a crucial role in female fertility and in adipose biology. It is essential in the ovary for ovulation, specifically oocyte release but not luteinisation of mature follicles. Our goal is to identify the key nuclear receptor(s) and their target genes responsible for ovulation.
Control of glycogen deposition
Authors: Ferrer Juan C. , Favre Cristián , Gomis Roger R. , Fernández-Novell Josep M. , Garcı́a-Rocha Mar , de la Iglesia Núria , Cid Emili , Guinovart Joan J.
Published: June 2003

Traditionally, glycogen synthase (GS) has been considered to catalyze the key step of glycogen synthesis and to exercise most of the control over this metabolic pathway. However, recent advances have shown that other factors must be considered. Moreover, the control of glycogen deposition does not follow identical mechanisms in muscle and liver. Glucose must be phosphorylated to promote activation of GS. Glucose‐6‐phosphate (Glc‐6‐P) binds to GS, causing the allosteric activation of the enzyme probably through a conformational rearrangement that simultaneously converts it into a better substrate for protein phosphatases, which can then lead to the covalent activation of GS. The potency of Glc‐6‐P for activation of liver GS is determined by its source, since Glc‐6‐P arising from the catalytic action of glucokinase (GK) is much more effective in mediating the activation of the enzyme than the same metabolite produced by hexokinase I (HK I). As a result, hepatic glycogen deposition from glucose is subject to a system of control in which the ‘controller’, GS, is in turn controlled by GK. In contrast, in skeletal muscle, the control of glycogen synthesis is shared between glucose transport and GS. The characteristics of the two pairs of isoenzymes, liver GS/GK and muscle GS/HK I, and the relationships that they establish are tailored to suit specific metabolic roles of the tissues in which they are expressed. The key enzymes in glycogen metabolism change their intracellular localization in response to glucose. The changes in the intracellular distribution of liver GS and GK triggered by glucose correlate with stimulation of glycogen synthesis. The translocation of GS, which constitutes an additional mechanism of control, causes the orderly deposition of hepatic glycogen and probably represents a functional advantage in the metabolism of the polysaccharide.
Functional identification of Gd3+ binding site of metabotropic glutamate receptor 1α
Authors: Abe Hideki , Tateyama Michihiro , Kubo Yoshihiro
Published: June 2003

We previously reported that the metabotropic glutamate receptor1α (mGluR1α) has a sensitivity to extracellular polyvalent cations such as Ca2+ and Gd3+ as well as glutamate. Gd3+ binding site was recently identified by crystal structure analysis at the interface of two subunits including Glu238, but it remains unknown whether this site is functionally involved in the activation of mGluR1α by Gd3+ or not. We analyzed the ligand sensitivity of the Glu238Gln mutant, and observed that the sensitivity to extracellular Gd3+ was completely lost, while the sensitivity to glutamate and Ca2+ was not affected. We also observed that the presence of Gd3+ increased the sensitivity of mGluR1α to glutamate, and that this effect was again lost by Glu238Gln mutation. These results suggest that the binding of Gd3+ or a related endogenous substance to this site, alone or in cooperation with glutamate binding at a distant site, leads mGluR1α to activation.
Annexin A1 processing is associated with caspase‐dependent apoptosis in BZR cells
Authors: Debret R. , El Btaouri H. , Duca L. , Rahman I. , Radke S. , Haye B. , Sallenave J.M. , Antonicelli F.
Published: June 2003

Annexins are widely distributed and have been described in lung as well as in other cells and tissues. Annexin I (ANX AI) is a member of the calcium‐dependent phospholipid binding protein family. Besides its anti‐inflammatory function, ANX AI has been involved in several mechanisms such as the Erk repression pathway or apoptosis. To investigate the role of ANX AI on apoptosis in broncho‐alveolar cells, we have constructed a plasmid containing the ANX AI full length cDNA. Transfected BZR cells displayed a higher level of both forms of ANX AI (37 and 33 kDa) as well as a decrease in cell viability (two‐fold versus cells transfected with an empty vector). In order to analyse the endogenous ANX AI processing during stimulus‐induced apoptosis, BZR cells were treated with a commonly used inducer, i.e. C2 ceramides. In these conditions, microscopic analysis revealed chromatin condensation in dying cells and the Bcl‐2, Bcl‐xL/Bax mRNA balance was altered. Caspase‐3 is one of the key executioners of apoptosis, being responsible for the cleavage of many proteins such as the nuclear enzyme poly(ADP‐ribose) polymerase (PARP). We demonstrate that caspase‐3 was activated after 4 h treatment in the presence of ceramide leading to the cleavage of PARP. Dose–response experiments revealed that cell morphology and viability modifications following ceramide treatment were accompanied by an increase in endogenous ANX AI processing. Interestingly, in both ceramide and transfection experiments, the ANX AI cleaved form was enhanced whereas pre‐treatment with the caspase inhibitor Z‐VAD‐fmk abolished ANX AI cleavage. In conclusion, this study demonstrates a complex regulatory role of caspase‐dependent apoptosis where ANX AI is processed at the N‐terminal region which could give susceptibility to apoptosis upon ceramide treatment.