bluuebunny/crossref_metadata_2025 huggingface dataset:
VARIATION AND RELATIONSHIPS AMONG SOME NUTRITIONAL TRAITS IN SICILIAN GENOTYPES OF CHICKPEA (CICER ARIETINUM L.)
Authors: PATANÈ CRISTINA
Published: May 2006

The chemical composition of several chickpeas originating from Sicily, compared with the International Center for Agricultural Research in the Dry Areas genotype “ILC 484” and the Italian cultivar “Calia,” was determined. A large variability was ascertained for crude fiber (coefficient of variation [CV] = 29.3%), calcium (CV = 39.3%) and tannins (CV = 120.0%). The genotype statistically affected all nutrient characteristics assessed, whose mean values were: (1) 100‐seed weight 34.0 ± 3.3 g; (2) crude fiber 2.88 ± 0.8 g/100 g; (3) fat 6.0 ± 0.9 g/100 g; (4) total carbohydrates 62.0 ± 1.4 g/100 g; (5) ash 2.64 ± 0.2 g/100 g; (6) iron 4.50 ± 0.3 mg/100 g; (7) calcium 109.6 ± 43.1 mg/100 g; (8) magnesium 189.4 ± 18.5 mg/100 g; (9) potassium 1318.7 ± 95.6 mg/100 g; and (10) tannins 0.90 ± 1.1 g/100 g. An average energy value of 379.8 ± 6.2 kcal/100 g was computed. The wide variability ascertained for some chemical attributes such as crude fiber, tannins and Ca content, and interesting correlations observed among characteristics, such as the negative correlation between Fe and tannins or fiber, or the positive correlation between ash and Fe, suggest the possibility of identifying genotypes to be used in breeding programs for the improvement of chickpea quality in Sicily.
Development of an spFRET method to measure structure changes in ion exchange proteins
Authors: Lesoine J. F. , Holmberg B. , Maloney P. , Wang X. , Novotny L. , Knauf P. A.
Published: May 2006

Aim:  Understanding the mechanism of tightly coupled ion exchange proteins, important effectors of cell volume regulation and other physiologically important transport processes requires means to observe dynamic changes in structure during the transport cycle. As a step towards this goal, we have applied single‐pair fluorescence resonance energy transfer to a monomeric bacterial oxalate‐formate exchanger (OxlT).

Methods:  A His‐9 tagged OxlT mutant containing two cysteines at positions 17 and 224 was labelled with cyanine dye maleimides (Cy3 donor and Cy5 acceptor) and attached to glass coverslips for measurements of donor and acceptor emission from single molecules, as described (P. Pal et al. Biophys J89, L11, 2005).

Results:  Time‐series data from 20 spots containing donor and acceptor provided evidence for single‐pair energy transfer. From the efficiency of energy transfer, the mean donor–acceptor distance was determined to be 44.2 Å. Considering the size of the probes, this is in good agreement with the Cα distance of 39.6 Å for the corresponding sites found in the OxlT structural (homology) model (Q. Yang et al. Proc Natl Acad Sci102, 8513, 2005).

Conclusion:  These results demonstrate the feasibility of single‐pair fluorescence resonance energy transfer to measure distances between known sites in single OxlT molecules. This technique provides a potential means to test models for transport‐related conformational changes, as well as to detect real‐time structure alterations during the catalytic transport cycle.
The Na+–K+–2Cl− cotransporter and the osmotic stress response in a model salt transport epithelium
Authors: Lionetto M. G. , Schettino T.
Published: May 2006

Epithelia are physiologically exposed to osmotic stress resulting in alteration of cell volume in several aspects of their functioning; therefore, the activation of ‘emergency’ systems of rapid cell volume regulation is fundamental in their physiology. In this review, the physiological response to osmotic stress, particularly hypertonic stress, was described in a salt‐transporting epithelium, the intestine of the euryhaline teleost European eel. This epithelium is physiologically exposed to changes in extracellular osmolarity and represents a good physiological model for functional studies on cellular volume regulation, permitting the study of volume regulated ion transport mechanisms in a native tissue. An absorptive form of the cotransporter, homologue of the renal NKCC2, localized on the apical membrane, was found in the intestine of the euryhaline teleost European eel. This cotransporter accounts for the luminal uptake of Cl−; it operates in series with a basolateral Cl− conductance and presumably a basolateral electroneutral KCl cotransport and in parallel with a luminal K+ conductance. The ion transport model described for eel intestine, based on the operation of an absorptive luminal Na+–K+–2Cl−, is basically the same as the model that has been proposed for the thick ascending limb (cTAL) of the mammalian renal cortex. This paper focuses on the role of Na+–K+–2Cl− cotransport in the responses to hypertonic stress in the eel intestine and the role of cytoskeleton (either actin‐based or tubulin based) is discussed.
Swelling‐activated ion channels: functional regulation in cell‐swelling, proliferation and apoptosis
Authors: Stutzin A. , Hoffmann E. K.
Published: May 2006

Cell volume regulation is one of the most fundamental homeostatic mechanisms and essential for normal cellular function. At the same time, however, many physiological mechanisms are associated with regulatory changes in cell size meaning that the set point for cell volume regulation is under physiological control. Thus, cell volume is under a tight and dynamic control and abnormal cell volume regulation will ultimately lead to severe cellular dysfunction, including alterations in cell proliferation and cell death. This review describes the different swelling‐activated ion channels that participate as key players in the maintenance of normal steady‐state cell volume, with particular emphasis on the intracellular signalling pathways responsible for their regulation during hypotonic stress, cell proliferation and apoptosis.
Hypotonicity and ethanol modulate BK channel activity and chloride currents in GH4/C1 pituitary tumour cells
Authors: Jakab M. , Schmidt S. , Grundbichler M. , Paulmichl M. , Hermann A. , Weiger T. , Ritter M.
Published: May 2006

Aim: Description of the effects of hypotonic cell swelling and ethanol on maxi Ca2+‐activated K+channel (BK channel) activity and Cl−channel activity in GH4/C1 pituitary tumour cells.

Methods: Whole cell‐, cell attached‐ and outside‐out patch clamp measurements, fluorescence (fluo‐3) measurements of intracellular Ca2+concentration, cell size video monitoring.

Results: GH4/C1 pituitary tumour cells respond to both hypotonicity and ethanol with cell swelling which is followed by a regulatory volume decrease (RVD). Tetraethylammonium and 4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid (DIDS) induced cell swellingper seand inhibited hypotonicity induced RVD. Ethanol‐induced swelling is paralleled by an increase in the intracellular Ca2+concentration and augmented by DIDS. BK channel activation by hypotonicity and ethanol is demonstrated in patch clamp experiments both in intact cells (cell attached configuration) and a subset of excised membrane patches (outside‐out configuration). Cell swelling and addition of ionomycin under isotonic conditions leads to the activation of outwardly rectifying Cl−currents with time dependent activation at positive potentials.

Conclusions: In GH4/C1 cells both hypotonicity and ethanol lead to cell swelling, RVD and to activation of BK channels. The hypotonicity‐induced BK channel activation can also be observed in cell free outside‐out patches. Hypotonicity, but not ethanol leads to the activation of Cl−channels with features of Ca2+‐activated Cl−currents.
Thyrotropin‐releasing hormone in rat heart: effect of swelling, angiotensin II and renin gene
Authors: Bačova Z. , Baqi L. , Beňačka O. , Payer J. , Križanová O. , Zeman M. , Smreková L. , Zorad Š. , Štrbák V.
Published: May 2006

Aim:  This study was performed to examine thyrotropin‐releasing hormone (TRH) secretion and regulation in rat heart.

Methods:  Expression of prepro‐TRH gene in left atrium and left ventricle was studied by RT‐PCR. TRH secretion from slices of left auricle and left ventricle in response to cell swelling (induced by hypotonic medium or ethanol in isosmotic medium), angiotensin II and losartan and their combinations was studied.

Results:  RT‐PCR revealed two times higher prepro‐TRH expression in left auricle than left ventricle. In transgenic rats with extra copy of mouse renin gene a marked increase of prepro‐TRH expression in the heart was noted but the relative difference between left atrium and left ventricle persisted. The swelling stimulated TRH release from both left auricle and left ventricle and this stimulation could not be inhibited by bumetanide. Angiotensin II (10 nmol L−1) added into medium significantly decreased basal secretion of TRH. The inhibiting effect of Angiotensin II was prevented by 1 μmol L−1 losartan, an angiotensin II AT1 receptor blocker. When angiotensin II and hypotonicity were applied simultaneously, swelling‐induced secretion persisted.

Conclusion:  TRH secretion from heart slices has attributes of regulated secretion – depending on the stimulus it could be either stimulated or inhibited. Renin positively affects prepro‐TRH expression in the heart. Angiotensin II inhibits TRH secretion from heart tissue by a mechanism involving AT1 receptors. Swelling‐induced TRH secretion overrides inhibitory effect of angiotensin II. Swelling could be a useful tool when natural or pharmacological secretagogue is unknown. Peptides and proteins released by swelling could be mediators of local and remote ischaemic preconditioning protecting from subsequent ischaemia.
The death of cardiotonic steroid‐treated cells: evidence of Na+i,K+i‐independent H+i‐sensitive signalling
Authors: Orlov S. N. , Hamet P.
Published: May 2006

Na/K‐ATPase is the only known target of cardiotonic steroids (CTS) identified in plants, amphibians and later on in several mammalian species, including human. We focus our review on recent data implicating CTS in the tissue‐specific regulation of cell survival and death. In vascular smooth muscle cells, CTS inhibited cell death triggered by apoptotic stimuli via a novel Na+i‐mediated, Ca2+i‐independent mechanism of expression of antiapoptotic genes, including mortalin. In contrast, exposure to CTS in vascular endothelial and renal epithelial cells led to cell death, showing combined markers of apoptosis and necrosis. This mode of cell death, termed oncosis, is caused by CTS interaction with Na/K‐ATPase but is independent of the inhibition of Na/K‐ATPase‐mediated ion fluxes and inversion of the [Na+]i/[K+]i ratio. The intermediates of intracellular signalling involved in Na+i, K+i‐independent oncosis of CTS‐treated cells remain unknown. Recently, we found that this mode of cell death can be protected by modest intracellular acidification via the expression of H+i‐sensitive genes. The molecular origin of intracellular Na+ and H+ sensor involvement in the development of apoptosis and oncosis is currently under investigation.
Cell hydration and mTOR‐dependent signalling
Authors: Schliess F. , Richter L. , Vom Dahl S. , Häussinger D.
Published: May 2006

Insulin‐ and amino acid‐induced signalling by the mammalian target of rapamycin (mTOR) involves hyperphosphorylation of the p70 ribosomal S6 protein kinase (p70S6‐kinase) and the eukaryotic initiation factor 4E (eIF4E) binding protein 4E‐BP1 and contributes to regulation of protein metabolism. This review considers the impact of cell hydration on mTOR‐dependent signalling. Although hypoosmotic hepatocyte swelling in some instances activates p70S6‐kinase, the hypoosmolarity‐induced proteolysis inhibition in perfused rat liver is insensitive to mTOR inhibition by rapamycin. Likewise, swelling‐dependent proteolysis inhibition by insulin and swelling‐independent proteolysis inhibition by leucine, a potent activator of p70S6‐kinase and 4E‐BP1 hyperphosphorylation, in perfused rat liver is insensitive to rapamycin, indicating that at least rapamycin‐sensitive mTOR signalling is not involved. Hyperosmotic dehydration in different cell types produces inactivation of signalling components around mTOR, thereby attenuating insulin‐induced glucose uptake, glycogen synthesis, and lipogenesis in adipocytes, and MAP‐kinase phosphatase MKP‐1 expression in hepatoma cells. Direct inactivation of mTOR, stimulation of the AMP‐activated protein kinase, and the destabilization of individual proteins may impair mTOR signalling under dehydrating conditions. Further investigation of the crosstalk between the mTOR pathway(s) and hyperosmotic signalling will improve our understanding about the contribution of cell hydration changes in health and disease and will provide further rationale for fluid therapy of insulin‐resistant states.
The ICln interactome
Authors: Fürst J. , Bottà G. , Saino S. , Dopinto S. , Gandini R. , Dossena S. , Vezzoli V. , Rodighiero S. , Bazzini C. , Garavaglia M. L. , Meyer G. , Jakab M. , Ritter M. , Wappl‐Kornherr E. , Paulmichl M.
Published: May 2006

The many different functional phenotypes described in mammalian cells can only be explained by an intense interaction of the underlying proteins, substantiated by the fact that the number of independently expressed proteins in living cells seems not to exceed 25 K, a number way too small to explain the >250 K different phenotypes on a one‐protein–one‐function base. Therefore, the study of the interactome of the different proteins is of utmost importance. Here, we describe the present knowledge of the ICln interactome. ICln is a protein, we cloned and whose function was reported to be as divers as (i) ion permeation, (ii) cytoskeletal organization, and (iii) RNA processing. The role of ICln in these different functional modules can be described best as being a ‘connector hub’ with ‘date hub’ function.
Functional role of amino terminus in ClC‐3 chloride channel regulation by phosphorylation and cell volume
Authors: Rossow C. F. , Duan D. , Hatton W. J. , Britton F. , Hume J. R. , Horowitz B.
Published: May 2006

Aim:  This study investigated the functional role of the ClC‐3 amino‐terminus in channel regulation in response to changes in cell volume.

Methods:  Wild‐type sClC‐3 tagged with a green fluorescence protein (GFP) at the C‐terminus was used as a template to construct a number of deletion mutants which were functionally expressed in NIH‐3T3 cells. Whole cell and single channel patch‐clamp electrophysiology was used to determine the functional properties of heterologously expressed channels.

Results:  The first 100 amino acids of the ClC‐3 N‐terminus were removed and the truncated channel (sClC‐3ΔNT) was functionally expressed. Immunocytochemistry confirmed membrane expression of both wtsClC‐3 and sClC‐3ΔNT channels in NIH/3T3 cells. sClC‐3ΔNT yielded constitutively active functional channels, which showed no response to protein kinase C or changes in cell volume. Deletion of a cluster of negatively charged amino acids 16–21 (sClC‐3Δ16–21) within the N‐terminus also yielded a constitutively active open channel phenotype, indicating these amino acids are involved in the N‐type regulation. Intracellular delivery of a thiol‐phosphorylated peptide corresponding to N‐terminal residues 12–61 (NT peptide) markedly inhibited sClC‐3ΔNT whole‐cell and single‐channel currents, further confirming the essential role of the N‐terminus in volume regulation of channel activity.

Conclusions:  These data strongly suggest the N‐terminus of sClC‐3 channels acts as a blocking particle inhibiting the flow of anions through the channel pore. This ‘N‐type’ regulation of sClC‐3 channels may be an important transducing mechanism linking changes in cell volume and channel protein phosphorylation to channel gating.
Normotonic cell shrinkage induces apoptosis under extracellular low Cl− conditions in human lymphoid and epithelial cells
Authors: Maeno E. , Shimizu T. , Okada Y.
Published: May 2006

Aim:  Sustained cell shrinkage is associated with apoptosis. Apoptotic volume decrease, which is known to be induced by release of osmolytes including Cl− ions, may be an essential event for apoptosis induction. Provided any anion channels and/or anion transporters are basally functioning, there is a possibility that imposition of a driving force for Cl− efflux per se results in sustained cell shrinkage and thereby induces apoptotic death. Here, this possibility was tested by reducing the extracellular Cl− concentration.

Methods:  Human lymphoid U937 and epithelial HeLa cells were provided for experiments after exposing to isotonic electrolyte solution which contains 146 or 1 mm Cl−. Measurements of mean cell volume, caspase‐3 activity and cell viability were performed by a Coulter‐type cell size analyzer, a fluorometric assay and a colorimetric assay, respectively.

Results:  After exposure to low Cl− solution in which most chloride was replaced with aspartate, gluconate, phosphate or methanesulphonate, both U937 and HeLa cells exhibited, for up to 60 min, shrinkage to a level (90–80%) significantly lower than that in control high Cl− solution. Reduction in cell viability started within 2 h and reached below 20% within 8 h after exposure to low Cl− solution. The cell death was found to be associated with caspase‐3 activation and DNA fragmentation.

Conclusions:  Exposure to isotonic low Cl− solution induced sustained shrinkage and thereafter apoptotic death in U937 and HeLa cells. Thus, it is suggested that sustained cell shrinkage per se provides a sufficient condition for apoptosis induction.
Na+/H+ exchangers and the regulation of volume
Authors: Alexander R. T. , Grinstein S.
Published: May 2006

The regulation of volume is fundamental to life. There exist numerous conditions that can produce perturbations of cell volume. The cell has developed mechanisms to directly counteract these perturbations so as to maintain its physiological volume. Directed influx of the major extracellular cation, sodium, serves to counteract a decreased cell volume through the subsequent osmotically coupled movement of water to the intracellular space. This process, termed regulatory volume increase is often mediated by the ubiquitous sodium/hydrogen ion exchanger, NHE1. Similarly, the maintenance of intravascular volume is essential for the maintenance of blood pressure and consequently the proper perfusion of vital organs. Numerous mechanisms exist to counterbalance alterations in intravascular volume, not the least of which is the renal absorption of sodium filtered at the glomerulus. Two‐thirds of filtered sodium and water are absorbed in the renal proximal tubule, a mechanism that intimately involves the apical sodium/hydrogen ion exchanger, NHE3. This isoform is fundamental to the maintenance and regulation of intravascular volume and blood pressure. In this article, the effects of cell volume on the activity of these different isoforms, NHE1 and NHE3, will be described and the consequences of their activity on intracellular and intravascular volume will be explored.
On the mechanism of ionic regulation of apoptosis: would the Na+/K+‐ATPase please stand up?
Authors: Panayiotidis M. I. , Bortner C. D. , Cidlowski J. A.
Published: May 2006

Apoptosis is an active process with distinct features including loss of cell volume, chromatin condensation, internucleosomal DNA fragmentation, and apoptotic body formation. Among the classical characteristics that define apoptosis, the loss of cell volume has become a very important component of the programmed cell death process. Changes in cell volume result from alterations in the homeostasis of ions and in particular the movement of Na+ and K+ ions. Most living cells have a high concentration of intracellular K+ and a low concentration of intracellular Na+. This is in contrast to the outside of the cell, where there is a high concentration of extracellular Na+ and a low concentration of extracellular K+. Thus a concentration gradient exists for the loss and gain of intracellular K+ and Na+, respectively. This gradient is maintained through the activity of various ionic channels and transporters, but predominantly the activity of the Na+/K+‐ATPase. During apoptosis, there is compelling evidence indicating an early increase in intracellular Na+ followed by a decrease in both intracellular K+ and Na+ suggesting a regulatory role for these cations during both the initial signalling, and the execution phase of apoptosis. Recent studies have shown that the Na+/K+‐ATPase is involved in controlling perturbations of Na+ and K+ homeostasis during apoptosis, and that anti‐apoptotic Bcl‐2 and Bcl‐XL molecules influence these ionic fluxes. Finally, understanding the regulation or deregulation of ionic homeostasis during apoptosis is critical to facilitate the treatment of cardiovascular, neurological, and renal diseases where apoptosis is known to play a major role.
Aquaporins in plants
Authors: Kaldenhoff R. , Fischer M.
Published: May 2006

Although very often exposed to a rapid changing environment, plants are in general unable to evade from unfavourable conditions. Therefore, a fine tuned adaptation of physiology including the water balance appears to be of crucial importance. As a consequence a relatively large number of aquaporin genes are present in plant genomes. So far aquaporins in plants were shown to be involved in root water uptake, reproduction or photosynthesis. Accordingly, plant aquaporin classification as simple water pores has changed corresponding to their molecular function into channels permeable for water, small solutes and/or gases. An adjustment of the respective physiological process could be achieved by regulation mechanisms, which range from post‐translational modification, molecular trafficking to heteromerization of aquaporin isoforms. Here the function of the four plant aquaporin family subclasses with regard to substrate specificity, regulation and physiological relevance is described.
SPAK and OSR1, key kinases involved in the regulation of chloride transport
Authors: Delpire E. , Gagnon K. B.
Published: May 2006

Reversible phosphorylation by protein kinases is probably one of the most important examples of post‐translational modification of ion transport proteins. Ste20‐related proline alanine‐rich kinase (SPAK) and oxidative stress response kinase (OSR1) are two serine/threonine kinases belonging to the germinal centre‐like kinase subfamily VI. Genetic analysis suggests that OSR1 evolved first, with SPAK arising following a gene duplication in vertebrate evolution. SPAK and OSR1 are two recently discovered kinases which have been linked to several key cellular processes, including cell differentiation, cell transformation and proliferation, cytoskeleton rearrangement, and most recently, regulation of ion transporters. Na–K–2Cl cotransporter activity is regulated by phosphorylation. Pharmacological evidence has identified several kinases and phosphatases which alter cotransporter function, however, no direct linkage between these enzymes and the cotransporter has been demonstrated. This article will review some of the physical and physiological properties of SPAK and OSR1, and present new evidence of a direct interaction between the Na–K–Cl cotransporter and the stress kinases.
Fluid transport and ion fluxes in mammalian kidney proximal tubule: a model analysis of isotonic transport
Authors: Larsen E. H. , Møbjerg N. , Sørensen J. N.
Published: May 2006

Aim:  By mathematical modelling, we analyse conditions for near‐isotonic and isotonic transport by mammalian kidney proximal tubule.

Methods:  The model comprises compliant lateral intercellular space (lis) and cells, and infinitely large luminal and peritubular compartments with diffusible species: Na+, K+, Cl− and an intracellular non‐diffusible anion. Unknown model variables are solute concentrations, electrical potentials, volumes and hydrostatic pressures in cell and lis, and transepithelial potential. We used data mainly from rat proximal tubule to model epithelial cells and interspace with luminal and peritubular baths of identical composition.

Results:  The model of the tubular epithelium with physiological water permeability and paracellular electrical resistance generates solute coupled water uptake with an approx. 3% hypertonic absorbate. This function remains unperturbed following ‘blocking’ of apical water channels and in ‘aquaporin‐null’ simulation. Reduced rate of volume reabsorption in AQP(‐/‐) mice would also require decreased apical sodium permeability. Paracellular convection accounts for approx. 36% of the net Na+ absorption, and the model epithelium accomplishes uphill water transport similar to rat proximal tubule. Na+ recirculation is required for truly isotonic transport. The tonicity of the absorbate and the recirculation flux depend critically on ion permeabilities of interspace basement membrane.

Conclusion:  Our model based on solute‐solvent coupling in lateral space simulates major physiological features of proximal tubule, including significantly lower water permeability of the AQP1‐null preparation, and a ratio of net sodium uptake and oxygen consumption exceeding that predicted from stoichiometry of the Na+/K+‐pump. Physical properties of interspace basement membrane are critical for obtaining near‐isotonic and truly isotonic transport.
Nitric oxide in the kidney: functions and regulation of synthesis
Authors: Mount P. F. , Power D. A.
Published: May 2006

In the kidney nitric oxide (NO) has numerous important functions including the regulation of renal haemodynamics, maintenance of medullary perfusion, mediation of pressure–natriuresis, blunting of tubuloglomerular feedback, inhibition of tubular sodium reabsorption and modulation of renal sympathetic neural activity. The net effect of NO in the kidney is to promote natriuresis and diuresis. Significantly, deficient renal NO synthesis has been implicated in the pathogenesis of hypertension. All three isoforms of nitric oxide synthase (NOS), namely neuronal NOS (nNOS or NOS1), inducible NOS (iNOS or NOS2) and endothelial NOS (eNOS or NOS3) are reported to contribute to NO synthesis in the kidney. The regulation of NO synthesis in the kidney by NOSs is complex and incompletely understood. Historically, many studies of NOS regulation in the kidney have emphasized the role of variations in gene transcription and translation. It is increasingly appreciated, however, that the constitutive NOS isoforms (nNOS and eNOS) are also subject to rapid regulation by post‐translational mechanisms such as Ca2+ flux, serine/threonine phosphorylation and protein–protein interactions. Recent studies have emphasized the role of post‐translational regulation of nNOS and eNOS in the regulation of NO synthesis in the kidney. In particular, a role for phosphorylation of nNOS and eNOS at both activating and inhibitory sites is emerging in the regulation of NO synthesis in the kidney. This review summarizes the roles of NO in renal physiology and discusses recent advances in the regulation of eNOS and nNOS in the kidney by post‐translational mechanisms such as serine/threonine phosphorylation.
Cellular basis of sex disparities in human cardiac electrophysiology
Authors: Verkerk A. O. , Wilders R. , De Geringel W. , Tan H. L.
Published: May 2006

Aim: Sex disparities in electrocardiogram variables and dysrhythmia susceptibility exist, notably in long QT syndrome (LQTS) and Brugada syndrome, but the underlying mechanisms in man are unknown. We studied the cellular basis of sex distinctions in human cardiac electrophysiology and dysrhythmia susceptibility using mathematical models of human ventricular myocytes.

Methods: We implemented sex differences in the Priebe–Beuckelmann and ten Tusscher–Noble–Noble–Panfilov human ventricular cell models by modifying densities of the L‐type Ca2+current (ICa,L), transient outward K+current (Ito), and rapid delayed rectifier K+current (IKr), according to experimental data from male and female hearts of various species. Sex disparities in transmural repolarization were studied in transmural strands of cells with ion current densities based on canine experimental data.

Results: Female cells have longer action potential duration (APD), steeper APD‐heart rate relationship, larger transmural APD heterogeneity, and a greater susceptibility to pro‐dysrhythmogenic early afterdepolarizations (EADs) than male cells. Conversely, male cells have more prominent phase‐1 repolarization and are more susceptible to all‐or‐none repolarization.

Conclusion: Sex differences inICa,L,ItoandIKrdensities may explain sex disparities in human cardiac electrophysiology. Female cells exhibit a limited ‘repolarization reserve’ as demonstrated by their larger susceptibility to EADs, which, combined with their larger transmural electrical heterogeneity, renders them more vulnerable to tachydysrhythmias in LQTS. Conversely, male cells have a limited ‘depolarization reserve’, as shown by their larger susceptibility to all‐or‐none repolarization, which facilitates tachydysrhythmias in Brugada syndrome. These general principles may also apply to dysrhythmia susceptibility in common disease.
Overexpression of VEGF‐A induces neovascularization and increased vascular leakage in rabbit eye after intravitreal adenoviral gene transfer
Authors: Kinnunen K. , Korpisalo P. , Rissanen T. T. , Heikura T. , Viita H. , Uusitalo H. , Ylä‐Herttuala S.
Published: May 2006

Aims:  The aim of this study was to determine dose–response effects of vascular endothelial growth factor A as delivered using an adenoviral vector on vascular growth and pathological changes in the rabbit eye. Moreover, we wanted to develop a large animal model for angioproliferative diseases in the eye.

Methods:  Seventeen New Zealand White rabbits were injected with adenoviral vascular endothelial growth factor‐A (AdVEGF‐A) intravitreally with different doses (109–1011 vp). Controls were injected with an empty virus (AdCMV). Some animals had a combination of AdVEGF‐A and AdsKDR (a soluble form of the VEGF receptor‐2). Animals were killed 6 days after the gene transfer. On the basis of these results, 14 rabbits were injected intravitreally with AdVEGF‐A or adenoviral LacZ (AdLacZ) with 1010 vp in a volume of 0.1 mL. Animals were killed 3, 6, 14 and 28 days after the gene transfer, eyes were removed and analysed histologically.

Results:  In enzyme‐linked immunosorbent assay (ELISA) analysis, human VEGF‐A was present in vitreous humour in all VEGF‐A transduced eyes. The amount of VEGF‐A showed a dose‐dependent increase with the AdVEGF‐A dose and was the highest 6 days after the gene transfer. Histologic analyses revealed an increased capillary area and density in the AdVEGF‐A eyes when compared with the AdLacZ eyes (P < 0.05). In the AdVEGF‐A/AdsKDR eyes the average capillary area was not increased compared with AdLacZ eyes.

Conclusion:  This model could be useful for large animal studies regarding the pathogenesis of neoangiogenesis and for the development of new therapeutic strategies for angioproliferative diseases of the eye. Our results establish the key role of VEGF‐A in the induction of neovascularization and pathological changes in the rabbit eye.
Global invasive potential of the house crow Corvus splendens based on ecological niche modelling
Authors: Nyári Árpád , Ryall Colin , Townsend Peterson A.
Published: May 2006

Summaries of recent rapid range expansions shown by the house crow Corvus splendens have provided insights into the global nature of this invasion process, but its long‐term potential has not yet been evaluated. To explore the potential dimensions of this geographic expansion, we used ecological niche modeling based on known occurrences of the species on its native distributional area, in the context of GIS data sets describing climatic variables, topographic information, and human presence. Our models provided predictions of areas already invaded that were statistically significantly more coincident than expected under random (null) models. The predicted potential range of the species includes areas already affected, as well as potentially suitable areas in Central America, the Caribbean, equatorial and West Africa, and mainland and insular Southeast Asia, not yet colonized.
Nest orientation and hatching success in the tree pipit Anthus trivialis
Authors: Burton Niall H. K.
Published: May 2006

Many open‐nesting bird species orient their nests relative to surrounding vegetation to avoid adverse environmental conditions. In eastern England, tree pipit Anthus trivialis nests predominantly faced east, an orientation that provided shelter from prevailing WSW winds, allowed warming by the morning sun and which, together with relatively high field layer cover, shaded nest contents from the midday sun. Mean orientation moved from south to north through the breeding season as temperatures increased, suggesting that solar radiation was a key influence on nest placement for tree pipits in the study area. Tree pipit nests with eastward orientations experienced better hatching success than those in less‐preferred orientations and it is suggested that this was due to their thermal advantages. In contrast, nest orientation had no influence on nestling survival.
Study of a Novel [CuII(TPP)]/Nafion Film Electrode for the Detection of Nitric Oxide Radical (NO)
Authors: Wang Ya-Zhen , Chen Wan-Hua , hu Sheng-Shui
Published: May 2006

A novel modified platinum electrode coated with copper(II)-5,10,15,20-tetraphenylporphyrin, [CuII(TPP)], has been developed. The electrochemical behavior of NO at the modified electrode was studied by cyclic and differential pulse voltammetries. In a deoxygenated phosphate-buffered saline solution (pH 7.4), the [CuII(TPP)]/Nafion-modified Pt electrode exhibits a strong electrocatalytic effect and stability to oxidation with NO and can be employed as a NO sensor. In this system, the modification film is capable of removing some endogenous anionic electroactive substances in biological samples, such as nitrite and ascorbate. The oxidation currents increase linearly with the concentration of NO in the range 1.8 × 10-7-0.9 × 10-4 M. The detection limit is 2.0 × 10-8 M. The nitric oxide radical, released from sodium nitroprusside (SNP), was also determined using chronoamperometry in the presence of light.
Atomic Force Microscopy and Light Scattering Study of Onion-Type Micelles Formed by Polystyrene-block-poly(2-vinylpyridine) and Poly(2-vinylpyridine)-block-poly(ethylene oxide) Copolymers in Aqueous Solutions
Authors: Matějíček Pavel , Štěpánek Miroslav , Uchman Mariusz , Procházka Karel , Špírková Milena
Published: May 2006

The three-layer onion micelles formed in aqueous solution by hierarchical self-assembly of polystyrene-block-poly(2-vinylpyridine) micelles, PS-PVP, and poly(2-vinylpyridine)-block-poly(ethylene oxide) chains, PVP-PEO, were studied by a combination of light scattering (LS) and atomic force microscopy (AFM). Section analysis of AFM images of micelles deposited on mica in combination with LS data from micellar solutions provide distribution functions of sizes from which the number and mass distributions of molar masses of micelles can be evaluated. Both light scattering and AFM data reveal that the used preparation protocol yields onion micelles accompanied by an admixture of PVP-PEO micelles. It means that only a certain amount of PVP-PEO self-assembles with PS-PVP and forms onion micelles. The remaining PVP-PEO copolymer forms either small PVP-PEO micelles or participates in formation of large aggregates at longer times. The time-dependent measurements show that both onion-type and core-shell PVP-PEO micelles are fairly stable over a long time period and only a low fraction of large aggregate forms on the timescale of weeks and at longer times, the solution does not change any more.
A PROBABILITY-LIKE NEW FUZZY SET THEORY
Authors: GAO XIAOYU , GAO Q. S. , HU Y. , LI L.
Published: May 2006

In this paper, the reasons for the shortcoming of Zadeh's fuzzy set theory — it cannot correctly reflect different kinds of fuzzy phenomenon in the natural world — are discussed. In addition, the proof of the error of Zadeh's fuzzy set theory — it incorrectly defined the set complement that cannot exist in Zadeh's fuzzy set theory — is proposed. This error of Zadeh's fuzzy set theory causes confusion in thinking, logic and conception. It causes the seriously mistaken belief that logics of fuzzy sets necessarily go against classical and normal thinking, logic and conception. Two new fuzzy set theories, C-fuzzy set theory and probability-like fuzzy set theory, the N-fuzzy set theory, are proposed. The two are equivalent, and both overcome the error and shortcoming of Zadeh's fuzzy set theory, and they are consistent with normal, natural and classical thinking, logic and concepts. The similarities of N-fuzzy set theory with probability theory are also examined.
MULTIPLE HUMAN DETECTION AND TRACKING BASED ON WEIGHTED TEMPORAL TEXTURE FEATURES
Authors: YANG HEE-DEOK , LEE SANG-WOONG , LEE SEONG-WHAN
Published: May 2006

In this paper, we present a method of tracking and identifying persons in video images taken by a fixed camera situated at an entrance. In video sequences a person may be totally or partially occluded in a scene for some period of time. The proposed approach uses the appearance model for the identification of persons and the weighted temporal texture features. The weight is related to the size, duration as well as the number of persons adjacent to the target person. Most systems have built an appearance model for each person to solve occlusion problems. The appearance model contains certain information on the target person. We have compared the proposed method with other related methods using color and shape features, and analyzed the features' stability. Experimental results with various real video data sequences revealed that real time person tracking and recognition is possible with increased stability in video surveillance applications even under situations of occasional occlusion.
A GABOR FILTER BASED FINGERPRINT ENHANCEMENT SCHEME USING AVERAGE FREQUENCY
Authors: ZHU EN , YIN JIANPING , ZHANG GUOMIN , HU CHUNFENG
Published: May 2006

Fingerprint minutiae are prevalently used in fingerprint recognition systems. The extraction of fingerprint minutiae is heavily affected by the quality of fingerprint images. This leads to the incorporation of a fingerprint enhancement module in fingerprint recognition systems to make the system robust with respect to the quality of input fingerprint images. Most of existing enhancement methods suffer from two main kinds of defects: (1) time consuming and thus unusable in time critical applications; and (2) blocky and directional effects in the enhanced image. This paper proposes an improved fingerprint enhancement scheme based on the Gabor filter tuning its frequency to the average frequency of the input image and changing its shape from square to circle and dynamically adjusting the filter's size based on the average frequency. This scheme can enhance the fingerprint image rapidly and overcome the blocky and directional effects and does improve the performance of minutiae detection.
THINNING CHARACTER USING MODULUS MINIMA OF WAVELET TRANSFORM
Authors: YOU XINGE , CHEN QIUHUI , FANG BIN , TANG YUAN YAN
Published: May 2006

An essential step in character recognition is to extract the skeleton characteristics of the character. In this paper, an efficient algorithm is proposed to extract visually satisfactory skeleton from printed and handwritten characters, which overcomes fundamental shortcomings of our previous skeletonization technique based on the maximum modulus symmetry of wavelet transform (WT). The proposed method is motivated from some desirable properties of the WT with constructed wavelet functions: namely, the local modulus minima of the WT are scale-independent at different level scales and are located at the medial axis of the symmetrical contours of character stroke. Thus the modulus minima of the WT are computed as the intrinsic skeletons of character strokes. To achieve faster implementation, a multiscale processing technique is employed. Thus major structures of the skeleton are extracted using the coarse scale, while fine structures are extracted using the fine scale. We have tested the algorithm on handwritten and printed character images. Experimental results show that the proposed algorithm is applicable to not only binary image but also gray-level image where it can be impractical to use other skeletonization techniques, such as thinning and distance transforms. Further, it can effectively remove unwanted artifacts and branches from the extracted skeletons at the intersections and junctions of character strokes and is robust against noises while most existing methods perform poorly.
SLUG (SNAI2) overexpression in embryonic development
Authors: Pérez-Mancera P.A. , González-Herrero I. , Maclean K. , Turner A.M. , Yip M.-Y. , Sánchez-Martín M. , García J.L. , Robledo C. , Flores T. , Gutiérrez-Adán A. , Pintado B. , Sánchez-García I.
Published: May 2006

The Snail-related zinc-finger transcription factor, SLUG (SNAI2), is critical for the normal development of neural crest-derived cells and loss-of-function SLUG mutations have been proven to cause piebaldism and Waardenburg syndrome type 2 in a dose-dependent fashion. However, little is known about the consequences of SLUG overexpression in embryonic development. We report SLUG duplication in a child with a unique de novo 8q11.2→q13.3 duplication associated with tetralogy of Fallot, submucous cleft palate, renal anomalies, hypotonia and developmental delay. To investigate the effects of Slug overexpression on development, we analyzed mice carrying a Slug transgene. These mice were morphologically normal at birth, inferring that Slug overexpression is not sufficient to cause overt morphogenetic defects. In the adult mice, there was a 20% incidence of sudden death, cardiomegaly and cardiac failure associated with incipient mesenchymal tumorigenesis. These findings, while not directly implicating Slug in congenital and acquired heart disease, raise the possibility that Slug overexpression may contribute to specific cardiac phenotypes and cancer development.
Cloning, chromosome mapping and expression characteristics of porcine ANGPTL3 and -4
Authors: Feng S.Q. , Chen X.D. , Xia T. , Gan L. , Qiu H. , Dai M.H. , Zhou L. , Peng Y. , Yang Z.Q.
Published: May 2006

Angiopoietin-like protein 3 and -4 (ANGPTL3 and -4) are two members of angiopoietin-like proteins (ANGPTLs), which have the signature structure of the angiopoietin family but cannot bind to the TIE2 receptor. It has been reported that they both affect lipid metabolism by inhibiting the activity of lipoprotein lipase (LPL). Here we report the cDNA cloning, chromosome mapping and expression analysis of ANGPTL3 and -4 in pigs. Sequence analysis shows that ANGPTL3 contains an open reading frame of 1,389 bp, which encodes 462 amino acids, and ANGPTL4 contains a coding region of 1,239 bp, which encodes 412 amino acids. Porcine ANGPTL3 deduced amino acid sequence shares 83% and 73.7% identity with human and mouse, respectively, and ANGPTL4 shares 79.4% and 77.7% amino acid identity with human and mouse, respectively. Porcine ANGPTL3 and -4 were mapped to the 6q31→q35 and 2q21→q24 region, respectively, by radiation hybrid mapping. Tissue distribution analysis indicated that porcine ANGPTL3 mRNA was exclusively expressed in liver, and porcine ANGPTL4 was ubiquitously expressed with the highest abundance in white adipose tissue. Furthermore, the mRNA level of ANGPTL3 and -4 in liver and the mRNA level of ANGPTL4 in white adipose tissue were significantly higher in genetically obese pigs than in their lean counterparts. This is the first report of molecular cloning and characterization of ANGPTL3 and -4 in pigs, which will be helpful for a better understanding of the role of ANGPTLs in lipid metabolism.
Cytological characterization of sex chromosomes and ribosomal DNA location in Anastrepha species (Diptera, Tephritidae)
Authors: Goday C. , Selivon D. , Perondini A.L.P. , Greciano P.G. , Ruiz M.F.
Published: May 2006

This paper reports a comparative analysis of heterochromatin organization in the sex chromosomes of the fruit fly Anastrepha. Mitotic chromosomes of eight Anastrepha species from different taxonomic groups were stained with DAPI and chromomycin A3 fluorochromes followed by C-banding. A specific sex-chromosome banding pattern was obtained for each of the analyzed species. Fluorescence in situ hybridization (FISH) was performed to investigate the chromosomal location of rDNA loci. In all cases the rDNA sequences were found to localize exclusively to the sex chromosomes. The results further extend the chromosomal knowledge of Anastrepha and allow a precise species identification.
Nuclear DNA content and nuclear and cell volume are positively correlated in angiosperms
Authors: Jovtchev G. , Schubert V. , Meister A. , Barow M. , Schubert I.
Published: May 2006

Volumes of flow sorted nuclei were analyzed from two highly endopolyploid (diploids with endopolyploid tissues) species (Arabidopsis thaliana and Barbarea stricta), from a less endopolyploid species (Allium cepa) and from two non-endopolyploid species (Chrysanthemum multicolor and Fritillaria uva-vulpis). Intraspecific as well as interspecific comparisons revealed a highly positive correlation (r >0.99) between DNA content and nuclear volume. No significant differences between expected and measured nuclear volumes were noted indicating that chromatin packing is not increased with increasing DNA content in the tested plant species. In epidermis cells of A. thaliana, A. cepa and Ch. multicolor, a lower (r between 0.6 and 0.7) but significant positive correlation between nuclear volume and cell volume was found. This correlation is compatible with the hypothesis that endopolyploidization (EP = consecutive replication cycles not separated by nuclear and cell divisions) might speed up the growth of endopolyploid species and compensate for small genome size.
A 17q21.31 microdeletion encompassing the MAPT gene in a mentally impaired patient
Authors: Varela M.C. , Krepischi-Santos A.C.V. , Paz J.A. , Knijnenburg J. , Szuhai K. , Rosenberg C. , Koiffmann C.P.
Published: May 2006

About 15% of patients with a clinical phenotype of Angelman syndrome (AS) have an unknown etiology. We report a patient with features reminiscent of AS, including a pattern of characteristic facial anomalies as well as speech impairment, developmental delay and frequent laughter. In addition, the patient had features not commonly associated with AS such as heart malformations and scoliosis. She was negative in SNURF-SNRPN exon 1 methylation studies and the G-banded karyotype was normal. Array-based comparative genomic hybridization disclosed a deletion of maximally 1 Mb at 17q21.31. The deleted region contains the MAPT gene, implicated in late onset neurodegenerative disorders, and the STH and NP_056258.1 genes. Another gene, such as CRHR1, might also be included based on maximum possible size of the deletion. We suggest that microdeletions within the 17q21.31 segment should be considered as a possible cause of phenotypes resembling AS, particularly when easily controlled seizures and/or cardiac abnormalities are also present.