bluuebunny/crossref_metadata_2025 huggingface dataset:
The local thermomechanical conditions and the fracture behavior of an injection‐molded poly(oxymethylene)
Authors: Viana J.C.
Published: December 2005

This work explores the fracture behavior of an injection‐molded engineering thermoplastic, poly(oxymethylene), POM. Lateral gated discs of 120 mm diameter and 1.5 mm thick were molded with variations of the melt temperature and injection flow rate. The local thermomechanical environment was characterized by computer simulations of mould filling phase. This also allows the computation of two thermomechanical indices related to the morphological state of the moldings. From the molded discs, double edge notched tensile (DENT) specimens were meticulously cut at different angles with respect to the flow direction and with distinct ligament lengths. The fracture tensile tests were performed at 2 mm/min at controlled room temperature. As the test configuration (specimen geometry) imposes a plane stress state, the stress intensity factor, KI, was calculated as function of the processing conditions and orientation angle with respect to the flow direction. The KI values and their degree of anisotropy are dependent upon processing conditions. Finally, the dependences of KI values upon the thermomechanical indices (and therefore on the expected morphological state of the moldings) are established. POLYM. ENG. SCI. 46:181–187, 2006. © 2005 Society of Plastics Engineers
Structure and mechanical properties of compatibilized poly(ethylene terephthalate)/poly(ethylene octene) blends
Authors: Guerrica‐Echevarría G. , Eguiazábal J.I. , Nazábal J.
Published: December 2005

Poly(ethylene terephthalate) (PET) based blends were obtained by melt blending PET with up to 30 wt% poly(ethylene‐octene) either modified with maleic anhydride (mLLDPE) or not (LLDPE). Both PET/LLDPE and PET/mLLDPE blends were immiscible. The dispersed phase particle size was large in LLDPE blends, but upon mLLDPE addition, it decreased to a small (submicron) and rather constant value with composition. This indicated compatibilization, and was attributed to specific interactions between the ester and maleic groups of PET and mLLDPE, respectively, rather than grafting reactions between components. Linear decreases in Young's modulus and yield stress, and ductility increases were observed in blends with mLLDPE. Super‐toughness was achieved in blends with mLLDPE, which took place when the critical interparticle distance (IDc) was below 0.17 μm and with only half the cross section of the specimens broken. The IDc of these blends and those of other blends from bibliography were compared with the adhesion levels estimated from the expected main interactions between the components of the blends. This comparison strongly indicated that, at least through an adhesion range, IDc depends on the adhesion level, and that IDc decreases as the adhesion level increases. POLYM. ENG. SCI. 46:172–180, 2006. © 2005 Society of Plastics Engineers
Novel aromatic polyimide fiber with biphenyl side‐groups: Dope synthesis and filament internal morphology control
Authors: Liu Xiangyang , Xu Wei , Ye Guangdou , Gu Yi
Published: December 2005

A new organic‐soluble aromatic polyimide with biphenyl side‐groups has been synthesized from 4,4′‐oxydiphthalic anhydride and 3,5‐diamino‐benzonic‐4′‐biphenyl ester (DABBE) via a one‐step polymerization in m‐cresol. A higher molecular weight polyimide has been obtained by the addition of chlorotrimethylsilane (TMSCl) in the solution of DABBE to form, in situ, silylated diamine. The optimum mole amount of TMSCl relative to the number of amino groups is 100%. This polyimide is soluble in m‐cresol, allowing fibers to be spun from isotropic solution using a dry‐jet wet spinning method. Based on a ternary phase diagram of m‐cresol, ethanol, and water, controlling of the internal morphology of as‐spun fibers has been achieved by varying the rate of polyimide coagulation through adjustment of nonsolvent/solvent miscibility in the coagulation bath. Scanning electron microscopic pictures show that filament internal morphologies ranged from porous‐like to fully solid. The solid as‐spun fibers can be drawn at high temperatures (>330°C) under tension to high drawn ratios (up to 6×), which produces a remarkable increase in tensile strength to about 1.0 GPa and an initial modulus higher than 60 GPa. POLYM. ENG. SCI. 46:123–128, 2006. © 2005 Society of Plastics Engineers
Torque‐rheometry investigation of model transreactions involving condensation polymers. I. Polyesters
Authors: Filippi Sara , Madrigali Laura , Polacco Giovanni , Magagnini Pierluigi , La Mantia Francesco P. , Acierno Domenico
Published: December 2005

The chemical transformations taking place when poly(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, undergone by the polyesters in reactive blending operations. The polyester molecular weight changes caused by the alcoholysis, acidolysis, aminolysis, and esterolysis reactions have been monitored by torque‐rheometry, using a Brabender Plasticorder static mixer. The degradation of the polyesters by hydrolysis was also studied, under similar conditions, by the addition of a water‐releasing substance (wet polyamide‐6), and was shown to occur quite rapidly, although most of the added water was lost by flash vaporization caused by the high temperature of the polyester melt. It has been shown that the rate constants of the reactions leading to breakage of the inner ester bonds of the polyester macromolecules decrease in the following order: aminolysis (with aliphatic amines, either primary and secondary) > alcoholysis (with aliphatic alcohols) ≈ hydrolysis > acidolysis (with aromatic acids) ≥ acidolysis (with aliphatic acids) ≫ aminolysis (with aromatic amines) > alcoholysis (with phenols) ≫ esterolysis. POLYM. ENG. SCI. 46:139–152, 2006. © 2005 Society of Plastics Engineers
On the injection molding of nanostructured polymer surfaces
Authors: Pranov Henrik , Rasmussen Henrik Koblitz , Larsen Niels Bent , Gadegaard Nikolaj
Published: December 2005

Well‐defined nano‐topographies were prepared by electron‐beam lithography and electroplated to form nickel‐shims. The surface pattern consisted of square pillars repeated equidistantly within the plane of the surface in a perpendicular arrangement. The width and distance between the squares both ranged from 310 to 3100 nm. All the pillars were 220 nm high. The nickel‐shim was used as a surface‐template during injection molding of polycarbonate. Secondly, a nickel shim, with a surface pattern consisted of a squared sine with a period of 700 nm and amplitude of 450 nm, was mounted on, and it was in good thermal contact with the upper plate in a hot‐press. Polycarbonate/polystyrene was melted on the lower plate while the temperature of the shim was kept below the glass transition temperature. The upper plate was lowered until the shim was in contact with the melt. Experiments were carried out with a clean shim and a shim coated with a monolayer of fluorocarbonsilane. As a result of the surface coating, the amplitude of the replicated grating decreased from about 350 nm in polycarbonate and 100 nm in polystyrene to less than 10 nm. The experiments strongly suggest that the possibility to injection mold sub‐micrometer surface structures in polymers mainly relates to adhesive energy between polymer and shim. POLYM. ENG. SCI. 46:160–171, 2006. © 2005 Society of Plastics Engineers
Ultrasonically initiated miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles
Authors: Qiu Guihua , Wang Qi , Wang Chao , Lau Willie , Guo Yili
Published: December 2005

Ultrasonically initiated miniemulsion polymerization of styrene was conducted in the presence of Fe3O4 nanoparticles. Stable polystyrene (PS)/Fe3O4 nanocomposite emulsions were prepared and magnetic PS/Fe3O4 composite particles were obtained through magnetic separation. The whole procedure comprised two steps. First, Fe3O4 nanoparticles were dispersed in the monomer phase with the aid of stabilizer Span‐80. Second, miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles was carried out under an ultrasonic field in the absence of a chemical initiator. The affecting factors, including stabilizer concentration, surfactant concentration, hexadecane concentration and the amount of Fe3O4, were systematically studied. Stabilizer concentration, surfactant concentration and hexadecane concentration strongly affected the formation of the coagulation. The least amount of coagulation was formed at 2.5 wt% Span‐80 concentration. The addition of Fe3O4 nanoparticles drastically increased the polymerization rate owing to the fact that Fe3O4 nanoparticles increased the acoustic intensity and Fe2+ reacted with H2O2 to produce hydroxyl radicals and increase the number of radicals. The increase in cosurfactant concentration and power output also increased the polymerization rate. Copyright © 2005 Society of Chemical Industry
Luminescence techniques and characterization of the morphology of polymer latices. 1. Fluorescence quenching studies upon labelled acrylic dispersions
Authors: Soutar Ian , Swanson Linda , Annable Tom , Padget John C , Satgurunathan Rajasingham
Published: December 2005

Fluorescence‐quenching measurements have been made on five differently labelled poly(n‐butyl methacrylate) latices. The accessibility of the fluorescent label to a freely diffusing quencher (nitromethane, in the case of the current study) gives information on the label's micro‐environment. However, it is shown that this is not (necessarily) relevant to considerations of the particle morphology in the absence of the label: the presence of the label during formation of the latex influences the nature of the domain in which it is finally located.

Used with caution, fluorescence quenching is capable of yielding information regarding the morphology of polymer latices, especially when complemented by other techniques, such as rheology measurements or small angle neutron scattering. Copyright © 2005 Society of Chemical Industry
Synthesis of oligocaprolactone vinyl ether macromonomers and their use for indomethacin encapsulation in polymer nanoparticles based on polycaprolactone macromonomer–maleic anhydride–N‐vinyl pyrrolidone terpolymers
Authors: Iojoiu Cristina , Cade David , Fessi Hatem , Hamaide Thierry
Published: December 2005

Oligocaprolactone macromonomers functionalized with vinyl ether have been synthesized by polymerization of ε‐caprolactone in the presence of hydroxy ethyl or butyl vinyl ether and characterised by NMR and Maldi time‐of‐flight mass spectroscopy. These macromonomers have been copolymerized with maleic anhydride and N‐vinyl pyrrolidone to give terpolymers, which have been used to obtain nanoparticles by the phase‐separation‐dialysis method. Previously dissolving indomethacin in the terpolymer solution allows one to encapsulate the drug inside the nanoparticles. Copyright © 2005 Society of Chemical Industry
Synthesis and characterization of novel perfluorinated polyimides with 3D‐controlled structures for photonic applications
Authors: Park Jin Kyu , Lee Dong Hun , Song Bok Ju , Oh Jae Buem , Kim Hwan Kyu
Published: December 2005

We have designed and synthesized novel perfluorinated polyimides with 3D controlled structure. At first, we successfully developed the new synthetic routes to diamines with pendant bulky perfluorinated aromatic units in a multi‐step synthetic procedure. Novel perfluorinated polyimides were prepared in a two‐step reaction in N‐methyl‐2‐pyrrolidinone (NMP) solution: The first step was for the synthesis of polyamic acids (PAAs) and the second reaction was for the imidization of PAA. The polymer yield was over 89% and the inherent viscosity of PAAs was in the range of 0.24–0.36 dL/g. The thin films were prepared by spin‐coating the PAA solution in NMP onto various substrates such as a Si wafer or a KBr pellet, dried at 80 °C and further cured at 230 °C. The resultant polyimides are thermally stable over 400 °C. The refractive index and birefringence of the resultant polyimides are 1.5858–1.6452 and 0.01–0.005, respectively. The refractive index of polyimide decreases with increasing the fluorine content. The copolymerization and the ether linkages into the backbone reduce the birefringence of polyimides. Surprisingly, the pendant ether linkage is not a crucial factor in reducing the polyimide birefringence. Their birefringence is comparatively very low, compared with that of previous polyimides. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1326–1342, 2006
Absenteeism from work: the experience of employed breast and prostate cancer patients in the months following diagnosis
Authors: Bradley Cathy J. , Oberst Kathleen , Schenk Maryjean
Published: December 2005

Background: A better understanding of how cancer treatments affect patient's employment may help patients and physicians make more informed choices between treatment alternatives. This study examined the number of days employed patients undergoing treatment for either breast or prostate cancer were absent from their jobs.

Method: Using the Detroit Surveillance, Epidemiology, End‐Results registry, all potentially eligible women diagnosed with breast cancer and men diagnosed with prostate cancer were selected. Subjects who were employed full‐time were included in this analysis.

Results: Women treated for breast cancer missed an average of 44.5 days from work; the median days missed was 22. The median days missed by women treated with surgery and chemotherapy was 40. Men diagnosed with prostate cancer missed an average of 27 days (median days=20) from work. The median days missed for men treated surgically without hormone or radiation therapy was 25. In multivariable analyses, taking a leave of absence and greater elapsed time from diagnosis to interview were associated with the greatest number of days absent from work for all patients. Men treated with hormone and/or radiation therapy or who were not treated missed fewer days from work relative to men undergoing surgery.

Conclusion: Research and interventions are needed to minimize work loss for cancer patients. Vocational rehabilitation programs may minimize the impact of treatment on work. Information on how treatments may infringe the ability for patients to earn a living may influence treatment decisions. Copyright © 2005 John Wiley & Sons, Ltd.
Prognostic value of PINP, bone alkaline phosphatase, CTX‐I, and YKL‐40 in patients with metastatic prostate carcinoma
Authors: Brasso Klaus , Christensen Ib Jarle , Johansen Julia S. , Teisner Børge , Garnero Patrick , Price Paul A. , Iversen Peter
Published: December 2005

BACKGROUND

To examine the prognostic value of markers of bone metabolism (serum PINP, BAP, and CTX‐I) and serum YKL‐40 in metastatic prostate carcinoma (PC).

METHODS

The biomarkers were determined by ELISAs in 153 metastatic PC patients before treatment with parenteral estrogen or total androgen ablation. The median follow‐up was 4.9 years. One hundred fifteen patients died.

RESULTS

The biomarkers were increased in the patients compared to controls (P < 0.001), and related to performance status and Soloway score (except YKL‐40), but not to T‐category and WHO tumor grade. PINP was elevated in 87%, BAP (55%), CTX‐I (33%), and YKL‐40 (43%). Univariate analysis showed an association to survival: PINP (HR = 1.6, P < 0.0001), BAP (HR = 1.4, P < 0.0001), CTX‐I (HR = 1.7, P < 0.0001), and YKL‐40 (HR = 1.4, P = 0.004). In multivariate Cox analysis performance status, WHO grade, Soloway score, PINP, and YKL‐40 were independently predictive factors.

CONCLUSIONS

High serum PINP, BAP, CTX‐I, and YKL‐40 are associated with poor outcome of metastatic PC patients. Prostate © 2005 Wiley‐Liss, Inc.
Metastable and quasiperiodic phases in rapidly quenched Fe–B–Si–Nb(Cu) alloys
Authors: Lyasotskii I. V. , Dyakonova N. B. , Vlasova E. N. , Dyakonov D. L. , Yazvitskii M. Yu.
Published: December 2005

The formation of metastable phases as a result of devitrification of amorphous iron‐based alloys, in particular at the initial stages of the process, was investigated. Compositions with 4–14 at% B, 3–10 at% Nb, 13–15 at% Si, 0–1 at% Cu were studied by means of transmission electron microscopy, X‐ray diffraction, and differential thermal analysis. The following metastable phases were observed: bcc phase with α‐Mn‐type structure; quasiperiodic structure with cubic symmetry; hexagonal phase (rhombohedral distortion of α‐Mn structure); and Laves C14 phase. Some of these phases are also observed in “Finemet” alloys with 1% Cu: cubic quasiperiodic phase and α‐Mn‐type phase after laser annealing of amorphous phase, and the hexagonal phase at the late stages of crystallization. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of resistivity of a p‐Si chip on the light‐emitting efficiency of a top‐emission organic light‐emitting diode with the p‐Si chip as the anode
Authors: Xu A. G. , Ran G. Z. , Wu Z. L. , Ma G. L. , Qiao Y. P. , Xu Y. H. , Yang B. R. , Zhang B. R. , Qin G. G.
Published: December 2005

For the top‐emission organic light‐emitting diode (TOLED) with a structure of p‐Si/SiOx/N,N′‐bis‐(1‐naphthl)‐diphenyl‐1,1′‐biphenyl‐4,4′‐diamine (NPB)/tris‐(8‐hydroxyquinoline) aluminum (AlQ)/Sm/Au, we found the resistivity of the p‐Si anode has a great effect on the hole injection and hence on the light‐emitting efficiency. Among the p‐Si anode TOLEDs each having a resistivity of 10–3, 10–1, 1, 10, 20, 40, and 70 Ω cm, the light‐emitting power efficiency is highest for the one with a 40 Ω cm p‐Si anode. The existence of an optimum resistivity for the p‐Si anode is mainly due to the near balance of hole injection with electron injection. When the p‐Si resistivity and the device voltage are high enough, the hole‐injection ability of the p‐Si anode becomes weaker than that of an indium‐tin oxide anode. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ac conductivity and dielectric properties of TlIn0.975Y0.025S2 single crystal
Authors: El‐Nahass M. M. , El‐Barry A. M. A. , Abd el Rahman S.
Published: December 2005

The frequency dependence of the electrical conductivity, dielectric properties, and dielectric loss of TlIn0.975Y0.025S2 single crystal was studied in the temperature range 303–473 K over the frequency range 102–105 Hz. A characteristic frequency, ωp, was found involved in the conduction mechanism, above which the electrical conductivity increased sharply. This observed variation was explained according to Summerfield theory for hopping conductivity which predicted a scaling law for the low‐frequency ac conductivity: σ(ω) = σ(0) [1 + (ω/ωp)β]. At higher frequency (≥4 kHz) the ac conductivity increased sharply with frequency according to the power law σac ≈ Aωs. The analysis of the ac conductivity at higher frequency showed that the correlated barrier hopping model is the most appropriate mechanism. Also, the loss tangent, tanδ, was predicted to decrease with increasing frequency. Capacitance was found to decrease with increasing frequency and decreasing temperature. The capacitance reached a minimum value, Cmin, at higher frequencies. Finally the maximum barrier height, WM, the hopping energy, ωH, the relaxation time, τ, and the density of states, N(Ef), for TlIn0.975Y0.025S2 single crystals were determined. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of nickel–zinc ferrite nanoparticles in polyol: morphological, structural and magnetic studies
Authors: Beji Z. , Ben Chaabane T. , Smiri L. S. , Ammar S. , Fiévet F. , Jouini N. , Grenèche J. M.
Published: December 2005

Nickel–zinc ferrite monodisperse nanoparticles are synthesized by forced hydrolysis in diethylenglycol. FC and ZFC susceptibility curves suggest that they present superparmagnetic behaviour with a blocking temperature between 63 and 15 K depending on the zinc content. The saturation magnetization of the nanocrystals at 5 K is very close to that of bulk materials, and very high compared to that of similar particles prepared by other chemical routes. High Resolution Transmission Electron Microscopy and In‐field Mössbauer studies show clearly that these relatively high values are mainly due to: (i) the high crystalline quality of the particles and (ii) a cation distribution different from the classical distribution encountered in the bulk material. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling suppression of cyanobacterial blooms by flow management in a lowland river
Authors: Mitrovic Simon M. , Chessman Bruce C. , Bowling Lee C. , Cooke Richard H.
Published: December 2005

Growth and dominance of the cyanobacterium Anabaena circinalis in weir pools of the Barwon–Darling River, Australia, are related to persistent vertical thermal stratification between October and March, when discharge is low. We determined critical velocities and discharges required to suppress bloom formation at three sites, and modelled the occurrence of sub‐critical discharges in order to predict the frequency of blooms under different management scenarios. Our model suggests that the frequency of blooms was about double that expected under near‐natural flows (without major impoundment or water extraction) for 1990–2000. Flow management, through Environmental Water Provisions that limit water extraction when river levels are low, has been in place since July 2000. Our model suggests that these provisions are unlikely to have had an effect on bloom frequency for 2000–2003. In the longer term, however, they could reduce bloom frequency at some sites by up to one‐third. Copyright © 2006 John Wiley & Sons, Ltd.
Cyclosporin A does not protect the disruption of the inner mitochondrial membrane potential induced by potassium ionophores in intact K562 cells
Authors: Marques‐Santos Luis F. , Coqueiro Vivian M. , Rumjanek Vivian M.
Published: December 2005

Mitochondrial dysfunction has been widely associated with programmed cell death. Studies of intact cells are important for the understanding of the process of cell death and its relation to mitochondrial physiology. Using cytofluorometric approaches we studied the mitochondrial behavior in an erythroleukemic cell line. The effects of protonophore carbonyl cyanide m‐chlorophenylhydrazone (CCCP), potassium exchanger (nigericin), potassium ionophore (valinomycin), Na+K+‐ATPase inhibitor (ouabain) and mitochondrial permeability transition pore inhibitor (cyclosporin A) were evaluated. Cyclosporin A (CSA) was very effective in attenuating the disruption of inner mitochondrial membrane potential induced by CCCP. However, CSA failed to protect the loss of inner mitochondrial membrane potential induced by potassium intracellular flux manipulation. Our findings suggest that mitochondrial cyclophilin is not involved in the cell events mediated by deregulation of potassium flux, underlining the need for further studies in intact tumor cells for a better understanding of the involvement of mitochondria physiology in cell death events.
Does yeast shmooing mean a commitment to apoptosis?
Authors: Zadrag Renata , Wojnar Leszek , Bartosz Grzegorz , Biliński Tomasz
Published: December 2005

Treatment of yeast Saccharomyces cerevisiae with α‐pheromone has been reported to lead to massive apoptosis of cells finding no conjugation partner [Severin FF, Hyman AA. Pheromone induces programmed cell death in S. cerevisiae. Curr Biol 2002;12:R233–5]. We report here that this effect is not common in yeast. Using different yeast strains, we demonstrate that identical treatment results in a low mortality even after prolonged treatment with the pheromone. These findings are followed by a general discussion of the biological relevance of apoptosis in yeast.
Antiproliferation and apoptosis induced by curcumin in human ovarian cancer cells
Authors: Shi Mingxin , Cai Qiufeng , Yao Luming , Mao Yubin , Ming Yanlin , Ouyang Gaoliang
Published: December 2005

Curcumin, an active ingredient from the rhizome of the plant, Curcuma longa, has antioxidant, anti‐inflammatory and anti‐cancer activities. It has recently been demonstrated that the chemopreventive activities of curcumin might be due to its ability to inhibit cell growth and induce apoptosis. In the present study, we have investigated the effects of curcumin on growth and apoptosis in the human ovarian cancer cell line Ho‐8910 by MTT assay, fluorescence microscopy, flow cytometry and Western blotting. Our data revealed that curcumin could significantly inhibit the growth and induce apoptosis in Ho‐8910 cells. A decrease in expression of Bcl‐2, Bcl‐XL and pro‐caspase‐3 was observed after exposure to 40 μM curcumin, while the levels of p53 and Bax were increased in the curcumin‐treated cells. These activities may contribute to the anticarcinogenic action of curcumin.
Electrically induced gel‐to‐gel phase‐transition in neurons
Authors: Kellermayer Richard , Zsombok Andrea , Auer Tibor , Gallyas Ferenc
Published: December 2005

At the end of transcardial perfusions with ice‐cold physiological saline for 30 min or with isoosmotic potassium chloride for 5 min, but immediately before perfusion fixation, condenser‐discharge electric shocks were administered to rats through surface electrodes pressed onto the temporal muscles of the scalped skull. As a result, striking ultrastructural compaction came about in numerous neurons thinly scattered in certain brain areas. Its features displayed a high degree of similarity to those previously observed following the in vivo administration of the same kind of electric shocks. This surprising independence from the actual state of metabolism questions whether the ultrastructural compaction, induced either in vivo or post mortem, is the result of any cascade of enzyme‐mediated processes. On the other hand, a physical mechanism, phase transition propagated by non‐covalent free energy stored in a cytoplasmic gel structure, which was proposed recently to explain a mechanically induced similar ultrastructural compaction, appears to apply also to the present case.
Chronic infarct‐related artery occlusion is associated with a reduction in capillary density. Effects on infarct healing
Authors: Prech Marek , Grajek Stefan , Marszalek Andrzej , Lesiak Maciej , Jemielity Marek , Araszkiewicz Aleksander , Mularek‐Kubzdela Tatiana , Cieslinski Andrzej
Published: December 2005

Aim:

To assess the relationship between infarct‐related artery (IRA) stenosis and capillary density and to assess its effect on scar formation in the human heart.

Materials and methods:

Morphometric evaluation was performed in 51 human hearts, as follows. Group I non‐cardiac death (control), Group II post‐Q‐wave myocardial infarction (QMI) death and Group III patients who survived QMI and who underwent aneurysmectomy. Using morphometric parameters, the relationship between left ventricle (LV) mass, infarct size, IRA stenosis, cellular hypertrophy and changes in microcirculation were analyzed within the infarcted area and free LV wall.

Results:

A significant reduction in capillary density within the infarcted area was noted in group II when compared to the control group (1525.6±378.5/mm2 vs. 2968.7±457.3/mm2; p<0.001). Reduction in capillary density was inversely related to infarct size (r=−0.616; p=0.006) and degree of IRA stenosis (rS=−0.512; p=0.03). The most significant reduction in capillary density was observed in patients with total IRA occlusion (1204.6±156.9/mm2 vs. 1676.6±245.8/mm2; p<0.001). Similarly, a reduction in capillary density of over 60% (1030.7±241.8/mm2) was observed within aneurysms resected surgically.

Conclusions:

The study demonstrated precise quantification of the capillary network in patients following QMI. The most significant reduction in capillary density was observed in patients with chronic total IRA occlusion.
The SigB σ factor mediates high‐temperature responses in the cyanobacterium Synechocystis sp. PCC6803
Authors: Tuominen Ilona , Pollari Maija , Tyystjärvi Esa , Tyystjärvi Taina
Published: December 2005

The σ factors of RNA polymerase play central roles when bacteria adapt to different environmental conditions. We studied heat‐shock responses in the cyanobacterium Synechocystis sp. PCC6803 using the σ factor inactivation strains ΔsigB, ΔsigD and ΔsigBD. The SigB factor was found to be important for short‐term heat‐shock responses and acquired thermotolerance. The normal high‐temperature induction of the hspA gene depended on the SigB factor. The SigD σ factor had a role in high‐temperature responses as well, and the double inactivation strain ΔsigBD grew more slowly at 43 °C than the ΔsigB and ΔsigD strains.
Tea polyphenol epigallocatechin 3‐gallate impedes the anti‐apoptotic effects of low‐grade repetitive stress through inhibition of Akt and NFκB survival pathways
Authors: Sen Prosenjit , Chakraborty Prabir Kumar , Raha Sanghamitra
Published: December 2005

V79 Chinese Hamster lung fibroblasts were subjected to repetitive low‐grade stress through multiple exposures to 30 μM H2O2in culture for 4 weeks. Akt/protein kinase B became phosphorylated at serine473and threonine308during this period of repetitive stress. Concurrent exposure of the cells to LY294002 (5 μM), a phosphoinositide‐3 kinase inhibitor or 4.5 μM epigallocatechin 3‐gallate (EGCG), a tea polyphenol almost completely blocked Akt activation by repetitive stress. Phosphorylation of I kappa B kinase (IKK) and transcriptional activity driven by nuclear factor kappa B (NFκB) were significantly enhanced by repetitive oxidative stress. These increases were largely abolished by simultaneous exposure to EGCG. The repetitively stressed cells demonstrated a significant resistance to apoptosis by subsequent acute stress in the form of ultraviolet radiation at 5 J/m2or H2O2(7.5 mM). The resistance to apoptosis conferred by repetitive stress was drastically reduced (>80%) by constant exposure to EGCG during the stress period while the presence of LY294002 or the NFκB inhibitor SN50 brought about a relatively moderate effect (about 50–65%). Our data indicate that activation of Akt and NFκB pro‐survival pathways by repetitive low‐grade stress results in a strong inhibition of the normal apoptotic response after subsequent acute stress. The tea polyphenol EGCG impedes the activation of both Akt and NFκB by repetitive stress and as a result preserves the normal apoptotic response during subsequent acute stress.
Dehydroepiandrosterone increases β‐cell mass and improves the glucose‐induced insulin secretion by pancreatic islets from aged rats
Authors: Medina Mayrin C. , Souza Lílian C. , Caperuto Luciana C. , Anhê Gabriel F. , Amanso Angélica M. , Teixeira Vicente P.A. , Bordin Silvana , Carpinelli Ângelo R. , Britto Luiz R.G. , Barbieri Renato L. , Borella Maria I. , Carvalho Carla R.O.
Published: December 2005

The effect of dehydroepiandrosterone (DHEA) on pancreatic islet function of aged rats, an animal model with impaired glucose‐induced insulin secretion, was investigated. The following parameters were examined: morphological analysis of endocrine pancreata by immunohistochemistry; protein levels of insulin receptor, IRS‐1, IRS‐2, PI 3‐kinase, Akt‐1, and Akt‐2; and static insulin secretion in isolated pancreatic islets. Pancreatic islets from DHEA‐treated rats showed an increased β‐cell mass accompanied by increased Akt‐1 protein level but reduced IR, IRS‐1, and IRS‐2 protein levels and enhanced glucose‐stimulated insulin secretion. The present results suggest that DHEA may be a promising drug to prevent diabetes during aging.
Arabidopsis KRPs have distinct inhibitory activity toward cyclin D2‐associated kinases, including plant‐specific B‐type cyclin‐dependent kinase
Authors: Nakai Tomohiro , Kato Ko , Shinmyo Atsuhiko , Sekine Masami
Published: December 2005

Arabidopsis contains seven Kip‐related protein (KRP) genes encoding CDK (cyclin‐dependent kinase) inhibitors (CKIs), which shares a restricted similarity with mammalian p27Kip1. Here, we analyze the characteristics of the KRPs. Although KRP1–KRP7 interact with active cyclin D2 (CYCD2)/CDKA and CYCD2/CDKB complexes to a similar extent, they inhibit kinase activity to a different extent. Our results suggest that inhibitory activity is related to the binding ability between KRP proteins and cyclin/CDK complexes, but secondary and tertiary structure may be also involved. These data provide the first evidence that KRPs inhibit kinase activity associated with plant‐specific CDKB.
ABC lipid transporters: Extruders, flippases, or flopless activators?
Authors: van Meer Gerrit , Halter David , Sprong Hein , Somerharju Pentti , Egmond Maarten R.
Published: December 2005

Many mammalian ABC transporters move membrane lipids to acceptor lipid assemblies in the extracellular aqueous milieu. Because the desorption from the membrane costs more energy than provided by two ATPs, the transporter probably only translocates the lipid to a partially hydrophilic site on its extracellular face. From this high‐energy site, the lipid may efficiently move to the acceptor, which ideally is bound to the transporter, or, in the absence of an acceptor, fall back into the membrane. If the lipid originated from the cytosolic membrane surface, this represents lipid flop and is probably a side activity of the transporters.
Crystal structure of the PB1 domain of NBR1
Authors: Müller Simone , Kursula Inari , Zou Peijian , Wilmanns Matthias
Published: December 2005

The scaffold protein NBR1 is involved in signal transmission downstream of the serine/protein kinase from the giant muscle protein titin. Its N‐terminal Phox and Bem1p (PB1) domain plays a critical role in mediating protein–protein interactions with both titin kinase and with another scaffold protein, p62. We have determined the crystal structure of the PB1 domain of NBR1 at 1.55 Å resolution. It reveals a type‐A PB1 domain with two negatively charged residue clusters. We provide a structural perspective on the involvement of NBR1 in the titin kinase signalling pathway.
Protein kinase A phosphorylates and regulates dimerization of 14‐3‐3ζ
Authors: Gu Young-Mi , Jin Yun-Hye , Choi Joong-Kook , Baek Kwang-Hyun , Yeo Chang-Yeol , Lee Kwang-Youl
Published: December 2005

Recognition of phosphorylated serine/threonine‐containing motifs by 14‐3‐3 depends on the dimerization of 14‐3‐3. However, the molecular cues that control 14‐3‐3 dimerization are not well understood. In order to identify proteins that control 14‐3‐3 dimerization, we analyzed proteins that have effects on 14‐3‐3 dimerization and report that protein kinase A (PKA) phosphorylates 14‐3‐3ζ at a specific residue (Ser58). Phosphorylation by PKA leads to modulation of 14‐3‐3ζ dimerization and affect its interaction with partner proteins. Substitution of Ser58 to Ala completely abolished phosphorylation of 14‐3‐3ζ by PKA. A phospho‐mimic mutant of 14‐3‐3ζ, Ser58 to Glu substitution, failed to form homodimers, showed reduced interaction with 14‐3‐3ε and p53, and could not enhance transcriptional activity of p53. Moreover, activation of PKA decreases and inhibition of PKA increases the dimerization of 14‐3‐3ζ and the functional interaction of 14‐3‐3ζ with p53. Therefore, our results suggest that PKA is a new member of protein kinases that can phosphorylate and impair the function of 14‐3‐3.
Phosphorylation and concomitant structural changes in human 2‐Cys peroxiredoxin isotype I differentially regulate its peroxidase and molecular chaperone functions
Authors: Jang Ho Hee , Kim Sun Young , Park Soo Kwon , Jeon Hye Sook , Lee Young Mee , Jung Ji Hyun , Lee Sun Yong , Chae Ho Byoung , Jung Young Jun , Lee Kyun Oh , Lim Chae Oh , Chung Woo Sik , Bahk Jeong Dong , Yun Dae-Jin , Cho Moo Je , Lee Sang Yeol
Published: December 2005

The H2O2‐catabolizing peroxidase activity of human peroxiredoxin I (hPrxI) was previously shown to be regulated by phosphorylation of Thr90. Here, we show that hPrxI forms multiple oligomers with distinct secondary structures. HPrxI is a dual function protein, since it can behave either as a peroxidase or as a molecular chaperone. The effects of phosphorylation of hPrxI on its protein structure and dual functions were determined using site‐directed mutagenesis, in which the phosphorylation site was substituted with aspartate to mimic the phosphorylated status of the protein (T90D‐hPrxI). Phosphorylation of the protein induces significant changes in its protein structure from low molecular weight (MW) protein species to high MW protein complexes as well as its dual functions. In contrast to the wild type (WT)‐ and T90A‐hPrxI, the T90D‐hPrxI exhibited a markedly reduced peroxidase activity, but showed about sixfold higher chaperone activity than WT‐hPrxI.
A radical solution for the biosynthesis of the H‐cluster of hydrogenase
Authors: Peters John W. , Szilagyi Robert K. , Naumov Anatoli , Douglas Trevor
Published: December 2005

Fe‐only or FeFe hydrogenases, as they have more recently been termed, possess a uniquely organometallic enzyme active site, termed the H‐cluster, where the electronic properties of an iron–sulfur cluster are tuned with distinctly non‐biological ligands, carbon monoxide and cyanide. Recently, it was discovered that radical S‐adenosylmethionine enzymes were involved in active hydrogenase expression. In the current work, we present a mechanistic scheme for hydrogenase H‐cluster biosynthesis in which both carbon monoxide and cyanide ligands can be derived from the decomposition of a glycine radical. The ideas presented have broader implications in the context of the prebiotic origin of amino acids.
Bi‐directional regulation of emodin and quercetin on smooth muscle myosin of gizzard
Authors: Zhang Hou-Li , Tang Ze-Yao , Yang Jing-Xian , Zhang Ying , Li Yue , Lin Yuan
Published: December 2005

This study is to reveal the characteristics of bidirectional regulation of emodin (1,3,8‐trihydroxy‐6‐methyl‐anthraquinone) and quercetin on gizzard smooth muscle myosin. Our results indicate that: (a) emodin demonstrates stimulatory effects, and quercetin produces inhibitory effects on myosin phosphorylation and Mg2+‐ATPase activities of Ca2+/calmodulin‐dependent phosphorylated myosin in a dose‐dependent manner; (b) a combination of emodin and quercetin enhances phosphorylation and Mg2+‐ATPase activities for partially phosphorylated myosin and inhibits those activities for fully phosphorylated myosin; (c) 1‐(5‐Chloronaphthalene‐1‐sulfonyl)‐1H2‐hexahydro‐1,4‐diazepine inhibits myosin phosphorylation in the presence of emodin and/or quercetin. A combination of emodin and quercetin indicates its potential for modulating gastric‐intestinal smooth muscle.
Biophysical re‐equilibration of Ca2+ fluxes as a simple biologically plausible explanation for complex intracellular Ca2+ release patterns
Authors: Burdakov Denis , Verkhratsky Alexei
Published: December 2005

Physiological regulation of Ca2+ release from the endoplasmic reticulum (ER) is critical for cell function. Recent direct measurements of free [Ca2+] inside the ER ([Ca2+]ER) revealed that [Ca2+]ER itself is a key regulator of ER Ca2+ handling. However, the role of this new regulatory process in generating various patterns of Ca2+ release remains to be elucidated in detail. Here, we incorporate the recently quantified experimental correlations between [Ca2+]ER and Ca2+ movements across the ER membrane into a mathematical model ER Ca2+ handling. The model reproduces basic experimental dynamics of [Ca2+]ER. Although this was not goal in model design, the model also exhibits mechanistically unclear experimental phenomena such as “quantal” Ca2+ release, and “store charging” by increasing resting cytosolic [Ca2+]. While more complex explanations cannot be ruled out, on the basis of our data we propose that “quantal release” and “store charging” could be simple re‐equilibration phenomena, predicted by the recently quantified biophysical dynamics of Ca2+ movements across the ER membrane.
Organization and function of the plant pleiotropic drug resistance ABC transporter family
Authors: Crouzet Jérôme , Trombik Tomasz , Fraysse Å. Staffan , Boutry Marc
Published: December 2005

Among the ABC transporters, the pleiotropic drug resistance (PDR) family is particular in that its members are found only in fungi and plants and have a reverse domain organization, i.e., the nucleotide binding domain precedes the transmembrane domain. In Arabidopsis and rice, for which the full genome has been sequenced, the family of plant ABC transporters contains 15 and 23 PDR genes, respectively, which can be tentatively organized using the sequence data into five subfamilies. Most of the plant PDR genes so far characterized belong to subfamily I and have been shown to be involved in responses to abiotic and biotic stress, in the latter case, probably by transporting antimicrobial secondary metabolites to the cell surface. Only a single subfamily II member has been characterized. Induction of its expression by iron deficiency suggests its involvement in iron deficiency stress, thus, enlightening a new physiological role for a PDR gene.
Dominant‐negative effect of mutant valosin‐containing protein in aggresome formation
Authors: Kitami Makiko-Iijima , Kitami Toshiaki , Nagahama Masami , Tagaya Mitsuo , Hori Seiji , Kakizuka Akira , Mizuno Yoshikuni , Hattori Nobutaka
Published: December 2005

Lewy bodies (LBs) are the pathologic hallmark of Parkinson's disease. Recent studies revealed that LBs exhibit several morphologic and molecular similarities to aggresomes. Aggresomes are perinuclear aggregates representing intracellular deposits of misfolded proteins. Recently, valosin‐containing protein (VCP) was one of the components of LBs, suggesting its involvement in LB formation. Here, we showed the localization of VCP in aggresomes induced by a proteasome inhibitor in cultured cells. Cells overexpressing mutant VCP (K524M: D2) showed reduced aggresome formation relative to those overexpressing wild‐type and mutant (K251M: D1) VCPs. Our findings suggest that the D2 domain is involved in aggresome formation.
Lifespan decrease in a Caenorhabditis elegans mutant lacking TRX‐1, a thioredoxin expressed in ASJ sensory neurons
Authors: Miranda-Vizuete Antonio , González Juan Carlos Fierro , Gahmon Gabriele , Burghoorn Jan , Navas Plácido , Swoboda Peter
Published: December 2005

Thioredoxins are a class of small proteins that play a key role in regulating many cellular redox processes. We report here the characterization of the first member of the thioredoxin family in metazoans that is mainly associated with neurons. The Caenorhabditis elegans gene B0228.5 encodes a thioredoxin (TRX‐1) that is expressed in ASJ ciliated sensory neurons, and to some extent also in the posterior‐most intestinal cells. TRX‐1 is active at reducing protein disulfides in the presence of a heterologous thioredoxin reductase. A mutant worm strain carrying a null allele of the trx‐1 gene displays a reproducible decrease in both mean and maximum lifespan when compared to wild‐type. The identification and characterization of TRX‐1 paves the way to use C. elegans as an in vivo model to study the role of thioredoxins in lifespan and nervous system physiology and pathology.
Chromium(III) ion and thyroxine cooperate to stabilize the transthyretin tetramer and suppress in vitro amyloid fibril formation
Authors: Sato Takashi , Ando Yukio , Susuki Seiko , Mikami Fumi , Ikemizu Shinji , Nakamura Masaaki , Suhr Ole , Anraku Makoto , Kai Toshiya , Suico Mary Ann , Shuto Tsuyoshi , Mizuguchi Mineyuki , Yamagata Yuriko , Kai Hirofumi
Published: December 2005

Transthyretin (TTR) amyloid fibril formation, which is triggered by the dissociation of tetrameric TTR, appears to be the causative factor in familial amyloidotic polyneuropathy and senile systemic amyloidosis. Binding of thyroxine (T4), a native ligand of TTR, stabilizes the tetramer, but the bioavailability of T4 for TTR binding is limited due to the preferential binding of T4 to globulin, the major T4 carrier in plasma. Here, we show that Cr3+ increased the T4‐binding capacity of wild‐type (WT) and amyloidogenic V30M‐TTR. Moreover, we demonstrate that Cr3+ and T4 cooperatively suppressed in vitro fibril formation due to the stabilization of WT‐TTR and V30M‐TTR.
Decreased blood pressure in NOX1‐deficient mice
Authors: Gavazzi Gaetan , Banfi Botond , Deffert Christine , Fiette Laurence , Schappi Michela , Herrmann Francois , Krause Karl-Heinz
Published: December 2005

To understand the role of the superoxide‐generating NADPH oxidase NOX1 in the vascular system, we have generated NOX1‐deficient mice. NOX1‐deficient mice had a moderately decreased basal blood pressure. In response to angiotensin II they showed an almost complete loss of the sustained blood pressure response, while the initial increase was conserved. NOX1‐deficient mice showed a marked reduction in aortic media hypertrophy. Angiotensin II‐induced smooth muscle cell proliferation was conserved, but there was a marked decrease in extracellular matrix accumulation. Our results establish a role for NOX1 in blood pressure regulation and vascular angiotensin II response.
Yeast ABC transporters – A tale of sex, stress, drugs and aging
Authors: Jungwirth Helmut , Kuchler Karl
Published: December 2005

Yeast ATP‐binding cassette (ABC) proteins are implicated in many biological phenomena, often acting at crossroads of vital cellular processes. Their functions encompass peptide pheromone secretion, regulation of mitochondrial function, vacuolar detoxification, as well as pleiotropic drug resistance and stress adaptation. Because yeast harbors several homologues of mammalian ABC proteins with medical importance, understanding their molecular mechanisms, substrate interaction and three‐dimensional structure of yeast ABC proteins might help identifying new approaches aimed at combating drug resistance or other ABC‐mediated diseases. This review provides a comprehensive discussion on the functions of the ABC protein family in the yeast Saccharomyces cerevisiae.
Immediate Corticocancellous Bone Autografting in Segmental Bone Defects of the Hand
Authors: SAINT-CYR MICHEL , MIRANDA DIEGO , GONZALEZ RUBEN , GUPTA AMIT
Published: December 2005

We performed a retrospective analysis of 12 type III open hand fractures in seven patients with segmental bone loss and associated soft tissue injuries to determine the effectiveness of immediate autologous corticocancellous bone grafting. Radical débridement and fracture fixation were performed prior to bone grafting. Results were interpreted according to clinical and radiologic time of bony healing, rate of infection, time to return to regular work duty, grip strength, rate of complications and range of motion. The final union rate was 92%, with a mean time to bony union of 18 weeks. The infection rate was 0%. The mean time to return to regular work duty, including recovery time after secondary surgeries, was 5 months and 21 days. All patients returned to their pre-injury employment. The mean total active motion of the combined metacarpophalangeal proximal interphalangeal and distal interphalangeal joints in bone-grafted digits was 178±53° at final follow-up.
Peripheral Nerve Compression Neuropathy after Fractures of the Distal Radius
Authors: BIENEK T. , KUSZ D. , CIELINSKI L.
Published: December 2005

Sixty patients with unilateral distal radius fractures were managed conservatively. Clinical assessment included objective and subjective evaluations of the outcome of treatment. Radiographic evaluation included fracture classification using the AO/ASIF system and measurement of volar tilt, radial inclination and radial height shortening at the end of treatment. Clinical signs of carpal tunnel syndrome were confirmed electrodiagnostically in 12 patients (20%) during the recovery period. Each patient had electrodiagnostic studies of both upper limbs performed to confirm the diagnosis. The mean time between injury and the onset of symptoms was 10 months (range 6.5 weeks–27 months). A statistically significant correlation between the final clinical results of treatment and post-traumatic median nerve compression neuropathy was found, but the occurrence of the neuropathy correlated with neither fracture type nor with the final radiographic findings. No clinical signs of ulnar or radial nerve compression occurred in this study.