bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive mechanical forces upregulate the fast myosin heavy chain IId/x via integrin and p38 MAP kinase activation in a primary muscle cell culture
Authors: Hanke Nina , Kubis Hans-Peter , Scheibe Renate J. , Berthold-Losleben Mark , Hüsing Olaf , Meissner Joachim D. , Gros Gerolf
Published: January 2010

We have studied the mechanism by which a previously described primary muscle culture growing on microcarriers predominantly expresses fast myosin heavy chain (MHC) IId/x. We have measured MHC IId/x mRNA and protein levels, mRNA of MHC I and markers of muscle metabolism, insulin-like growth factor (IGF)-1 and mechano-growth factor (MGF) transcripts, indicators of the activation of the Akt-mammalian target of rapamycin (mTOR) axis, the p38-, ERK1/2-, and JNK-mitogen-activated protein kinase (MAP) kinase pathways, and of protein phosphatase PP2A, and we have assessed the involvement of integrin. By placing the culture flasks on a rotary shaker, we induce a continuous motion of the culture medium in which the carrier-myotube aggregates are suspended. This motion exerts passive forces on the myotubes that are decisive for the predominance of MHC II expression. These forces act via integrin, which transduces the mechanical signal into activation of PP2A and of p38 MAP-Kinase. The latter presumably is directly responsible for a drastic upregulation of MHC IId/x, whereas MHC I and metabolic markers remain unaffected. At the same time, despite an elevated level of IGF-1 transcription under passive forces, the IGF-1 receptor-Akt-mTOR axis is switched off as evident from the lack of an effect of inhibition of the IGF-1 receptor and from the PP2A-mediated low degree of phosphorylation of Akt and 4E-BP1. Similarly, the ERK1/2- and JNK-MAP kinase pathways are repressed. We conclude that passive stretch exerted on the myotubes by the rotary fluid motion induces a rather selective upregulation of fast MHC II, which goes along with a mild muscle hypertrophy as judged from the amount of protein per cell and is caused by p38 MAP kinase activity elevated via integrin sensing. The direct link between passive stretch and MHC II expression constitutes a novel mechanism, which is expected to become effective physiologically under passive stretch and eccentric contractions of skeletal muscles.
Role of purinergic signaling pathways in V-ATPase recruitment to apical membrane of acidifying epididymal clear cells
Authors: Belleannée Clémence , Da Silva Nicolas , Shum Winnie W. C. , Brown Dennis , Breton Sylvie
Published: January 2010

Extracellular purinergic agonists regulate a broad range of physiological functions via P1 and P2 receptors. Using the epididymis as a model system in which luminal acidification is essential for sperm maturation and storage, we show here that extracellular ATP and its hydrolysis product adenosine trigger the apical accumulation of vacuolar H+-ATPase (V-ATPase) in acidifying clear cells. We demonstrate that the epididymis can hydrolyze luminal ATP into other purinergic agonists such as ADP via the activity of nucleotidases located in the epididymal fluid and in the apical membrane of epithelial cells. Alkaline phosphatase activity and abundant ecto-5′-nucleotidase protein were detected in the apical pole of principal cells. In addition, we show that nine nucleotidase genes ( Nt5e, Alpl, Alpp, Enpp1, 2, and 3, and Entpd 2, 4, and 5), seven ATP P2 receptor genes (P2X1, P2X2, P2X3, P2X4, P2X6, P2Y2, P2Y5), and three adenosine P1 receptor genes (A1, A2B, and A3) are expressed in epithelial cells isolated by laser cut microdissection (LCM). The calcium chelator BAPTA-AM abolished the apical V-ATPase accumulation induced by ATP, supporting the contribution of P2X or P2Y in this response. The PKA inhibitor myristoylated protein kinase inhibitor (mPKI) inhibited adenosine-dependent V-ATPase apical accumulation, indicating the participation of the P1 A2B receptor. Altogether, these results suggest that the activation of P1 and P2 purinergic receptors by ATP and adenosine might play a significant role in luminal acidification in the epididymis, a process that is crucial for the establishment of male fertility.
Triacylglycerol lipases and metabolic control: implications for health and disease
Authors: Watt Matthew J. , Spriet Lawrence L.
Published: January 2010

Fatty acids derived from the hydrolysis of adipose tissue and skeletal muscle triacylglycerol (TG) are an important energy substrate at rest and during physical activity. This review outlines the identification of the new TG lipase, adipose triglyceride lipase, the current understanding of how cellular TG lipases are regulated, and the implications for understanding the integrated control of TG lipolysis. Furthermore, this review outlines recent advances that propose a “revised” role for TG lipases in cellular function, metabolic homeostasis, and disease prevention.
Mechanisms of nitric oxide-mediated, neurogenic vasodilation in mesenteric resistance arteries of toad Bufo marinus
Authors: Jennings Brett L. , Donald John A.
Published: January 2010

This study determined the role of nitric oxide (NO) in neurogenic vasodilation in mesenteric resistance arteries of the toad Bufo marinus . NO synthase (NOS) was anatomically demonstrated in perivascular nerves, but not in the endothelium. ACh and nicotine caused TTX-sensitive neurogenic vasodilation of mesenteric arteries. The ACh-induced vasodilation was endothelium-independent and was mediated by the NO/soluble guanylyl cyclase signaling pathway, inasmuch as the vasodilation was blocked by the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and the NOS inhibitors Nω-nitro-l-arginine methyl ester and Nω-nitro-l-arginine. Furthermore, the ACh-induced vasodilation was significantly decreased by the more selective neural NOS inhibitor N5-(1-imino-3-butenyl)-l-ornithine. The nicotine-induced vasodilation was endothelium-independent and mediated by NO and calcitonin gene-related peptide (CGRP), inasmuch as pretreatment of mesenteric arteries with a combination of Nω-nitro-l-arginine and the CGRP receptor antagonist CGRP-(8–37) blocked the vasodilation. Clotrimazole significantly decreased the ACh-induced response, providing evidence that a component of the NO vasodilation involved Ca2+-activated K+or voltage-gated K+channels. These data show that NO control of mesenteric resistance arteries of toad is provided by nitrergic nerves, rather than the endothelium, and implicate NO as a potentially important regulator of gut blood flow and peripheral blood pressure.
Species differences in respiratory rhythm generation in rodents
Authors: Gajda B. M. , Fong A. Y. , Milsom W. K.
Published: January 2010

We examined the role of riluzole (RIL)- and flufenamic acid (FFA)-sensitive mechanisms in respiratory rhythmogenesis in rats and hamsters using the in situ arterially perfused preparation. Based on the hypothesis that respiratory networks in animals capable of autoresuscitation would have a greater prevalence of membrane mechanisms that promote endogenous bursting, we predicted that older (weaned) hamsters (a hibernating species) would be more sensitive to the blockade of RIL- and FFA-sensitive mechanisms than age-matched rats and that younger (preweaned) rats would behave more like hamsters. Consistent with this, we found that respiratory motor output in weaned hamsters [>21 days postnatal (P21)] was highly sensitive to RIL (0.2–20 μM), while in young rats (P12–14) it was less so (only affected at higher concentrations of RIL), and weaned rats were not affected at all. On the other hand, respiratory motor output was equally reduced by FFA (0.25–25 μM) in both young and weaned rats but was unaffected in weaned hamsters. Coapplication of RIL and FFA (RIL + FFA) produced greater inhibition of respiration in both young and weaned rats compared with either drug alone. In contrast, in weaned hamsters, FFA coapplication offset the inhibitory effect of RIL alone. Increasing respiratory drive with hypercapnia/acidosis ameliorated the respiratory inhibition produced by RIL + FFA in weaned rats but had no effect in young rats. Data from the present study indicate that respiratory rhythmogenesis in young rats is more dependent on excitatory RIL-sensitive and FFA-sensitive mechanisms than older rats and that fundamental differences exist in the respiratory rhythmogenic mechanisms between rats and hamsters.
Acute and chronic effects of endotoxin on cerebral circulation in lambs
Authors: Feng Susan Y. S. , Samarasinghe Thilini , Phillips David J. , Alexiou Theodora , Hollis Jacob H. , Yu Victor Y. H. , Walker Adrian M.
Published: January 2010

The impact of endotoxemia on cerebral endothelium and cerebral blood flow (CBF) regulation was studied in conscious newborn lambs. Bacterial endotoxin [LPS, 2 μg/kg iv] was infused on 3 consecutive days. Cerebrovascular function was assessed by monitoring CBF and cerebral vascular resistance (CVR) over 12 h each day and by the endothelium-dependent vasodilator bradykinin (BK) ( n = 10). Inflammatory responses were assessed by plasma tumor necrosis factor-α (TNF-α, n = 5). Acutely, LPS disrupted the cerebral circulation within 1 h, with peak cerebral vasoconstriction at 3 h (CBF −28 and CVR +118%, P < 0.05) followed by recovery to baseline by 12 h. TNF-α and body temperature peaked ∼1 h post-LPS. BK-induced vasodilatation (CVR −20%, P < 0.05) declined with each LPS infusion, was abolished after 3 days, and remained absent for at least the subsequent 5 days. Histological evidence of brain injury was found in four of five LPS-treated newborns. We conclude that endotoxin impairs cerebral perfusion in newborn lambs via two mechanisms: 1) acute vasoconstriction (over several hours); and 2) persistent endothelial dysfunction (over several days). Endotoxin-induced circulatory impairments may place the newborn brain at prolonged risk of CBF dysregulation and injury as a legacy of endotoxin exposure.
Functional expression of purinergic P2X7 receptors in pregnant rat myometrium
Authors: Miyoshi Hiroshi , Yamaoka Kaoru , Urabe Satoshi , Kodama Miho , Kudo Yoshiki
Published: January 2010

ATP has been reported to enhance the membrane conductance of myometrial cells and uterine contractility. Purinergic P2 receptor expression has been reported in the myometrium, using molecular biology, but the functional identity of the receptor subtype has not been determined. In this study, ATP-induced currents were recorded and characterized in single myometrial cells from pregnant rats using whole cell patch clamping. Extracellular ATP was applied in the range of 10 μM-1 mM and induced currents with an EC50of 74 μM, with no desensitization, time dependency, or voltage dependency. The currents induced carried multiple monovalent cations, with conductances ranked as K+> Cs+> Li+> Na+. They were activated by P2X receptor agonists, with their effectiveness ranked as 2′,3′- O-(4-benzoylbenzoyl)-ATP >> ATP > αβ-methylene-ATP > 2-methylthio ATP ≥ UTP ≥ GTP > ADP. These currents were blocked by the selective P2X7 receptor antagonist 3-[5-(2,3-dichlorophenyl)-1 H-tetrazol-1-yl]methyl pyridine (A-438079). We therefore concluded that ATP-induced currents in rat myometrial cells crossed cell membranes via P2X7 receptors. We further showed that the ATP-induced currents were blocked by extracellular Mg2+(IC50= 0.26 mM). Clinically, administering extracellular Mg2+is known to inhibit uterine contraction. It therefore seems likely that uterine contraction may be induced by raised extracellular ATP and suppressed via Mg2+inhibiting P2X7 receptors. Further research is needed into the P2X7 receptor as a therapeutic target in abnormal uterine contraction, as a possible treatment for premature labor.
Leptin reduces plasma ANP level via nitric oxide-dependent mechanism
Authors: Yuan Kuichang , Yu Jiahua , Shah Amin , Gao Shan , Kim Sun Young , Kim Sung Zoo , Park Byung-Hyun , Kim Suhn Hee
Published: January 2010

Leptin is a circulating adipocyte-derived hormone that influences blood pressure (BP) and metabolism. This study was designed to define the possible role of leptin in regulation of the atrial natriuretic peptide (ANP) system using acute and chronic experiments. Intravenous infusion of rat leptin (250 μg/kg injection plus 2 μg·kg−1·min−1for 20 min) into Sprague-Dawley rats increased BP by 25 mmHg and decreased plasma level of ANP from 80.3 ± 3.45 to 51.8 ± 3.3 pg/ml. Reserpinization attenuated the rise in BP, but not the reduction of plasma ANP during leptin infusion. Nω-nitro-l-arginine methyl ester prevented the effects of leptin on the reduction of ANP level. In hyperleptinemic rats that received adenovirus containing rat leptin cDNA (AdCMV-leptin), BP increased during first 2 days and then recovered to control value. Plasma concentration of ANP and expression of ANP mRNA, but not of atrial ANP, in hyperleptinemic rats were lower than in the control groups on the first and second week after administration of AdCMV-leptin. These effects were not observed by the pretreatment with Nω-nitro-l-arginine methyl ester. No differences in renal function and ANP receptor density in the kidney were found between hyperleptinemic and control rats. Basal ANP secretion and isoproterenol-induced suppression of ANP secretion from isolated, perfused atria of hyperleptinemic rats were not different from those of other control groups. These data suggest that leptin inhibits ANP secretion indirectly through nitric oxide without changing basal or isoproterenol-induced ANP secretion.
Intragastric monosodiuml-glutamate stimulates motility of upper gut via vagus nerve in conscious dogs
Authors: Toyomasu Yoshitaka , Mochiki Erito , Yanai Mitsuhiro , Ogata Kyoichi , Tabe Yuichi , Ando Hiroyuki , Ohno Tetsuro , Aihara Ryuusuke , Zai Hiroaki , Kuwano Hiroyuki
Published: January 2010

Monosodium l-glutamate (MSG) is a substance known to produce the umami taste. Recent studies indicate that MSG also stimulates a variety of activities in the gastrointestinal tract through its receptor in the gut, but no study has reported the activity in conscious large experimental animals. The aim of our study was to investigate whether direct intragastric MSG stimulates gut motility and to identify the mechanism in conscious dogs. Contractile response to intraluminal injection of MSG was studied in the fed and fasted states by means of chronically implanted force transducers. MSG (5, 15, 45, and 90 mM/kg) dissolved in water was injected into the stomach and duodenum in normal and vagotomized dogs. MSG solution was administered into the stomach before feeding, and gastric emptying was evaluated. Several inhibitors of gastrointestinal motility (atropine, hexamethonium, and granisetron) were injected intravenously before MSG administration to the stomach. The effect of MSG was investigated in Pavlov (vagally innervated corpus pouch), Heidenhain (vagally denervated corpus pouch), and antral pouch (vagally innervated) dogs. Upper gut motility was significantly increased by intragastric MSG but not significantly stimulated by intraduodenal MSG. Intragastric MSG (45 mM/kg) stimulated postprandial motility and accelerated gastric emptying. MSG-induced contractions were inhibited by truncal vagotomy, atropine, hexamethonium, and granisetron. Gut motility was increased by intrapouch injection of MSG in the Pavlov pouch, but it was not affected in the Heidenhain or antral pouch dogs. We conclude that intragastric MSG stimulates upper gut motility and accelerates gastric emptying. The sensory structure of MSG is present in the gastric corpus, and the signal is mediated by the vagus nerve.
Developmental effect of antenatal exposure to betamethasone on renal angiotensin II activity in the young adult sheep
Authors: Contag Stephen A. , Bi Jianli , Chappell Mark C. , Rose James C.
Published: January 2010

Antenatal corticosteroids may have long-term effects on renal development which have not been clearly defined. Our objective was to compare the responses to intrarenal infusions of ANG II in two groups of year-old, male sheep: one group exposed to a clinically relevant dose of betamethasone before birth and one not exposed. We wished to test the hypothesis that antenatal steroid exposure would enhance renal responses to ANG II in adult life. Six pairs of male sheep underwent unilateral nephrectomy and renal artery catheter placement. The sheep were infused for 24 h with ANG II or with ANG II accompanied by blockade of the angiotensin type 1 (AT1) or type 2 (AT2) receptor. Baseline mean arterial blood pressure among betamethasone-exposed sheep was higher than in control animals (85.8 ± 2.2 and 78.3 ± 1.0 mmHg, respectively, P = 0.003). Intrarenal infusion of ANG II did not increase systemic blood pressure ( P ≥ 0.05) but significantly decreased effective renal plasma flow and increased renal artery resistance ( P < 0.05). The decrease in flow and increase in resistance were significantly greater in betamethasone- compared with vehicle-exposed sheep (betamethasone P < 0.05, vehicle P ≥ 0.05). This effect appeared to be mediated by a heightened sensitivity to the AT1receptor among betamethasone-exposed sheep. Sodium excretion initially decreased in both groups during ANG II infusion; however, a rebound was observed after 24 h. AT1blockade was followed by a significant rebound after 24 h in both groups. AT2blockade blunted the 24-h rebound effect among the vehicle-exposed sheep compared with the betamethasone-exposed sheep. In conclusion, antenatal corticosteroid exposure appears to modify renal responsiveness to ANG II by increasing AT1- and decreasing AT2receptor-mediated actions particularly as related to renal blood flow and sodium excretion.
p21-Activated kinases regulate actin remodeling in glomerular podocytes
Authors: Zhu Jianxin , Attias Ortal , Aoudjit Lamine , Jiang Ruihua , Kawachi Hiroshi , Takano Tomoko
Published: January 2010

The tyrosine phosphorylation of nephrin is reported to regulate podocyte morphology via the Nck adaptor proteins. The Pak family of kinases are regulators of the actin cytoskeleton and are recruited to the plasma membrane via Nck. Here, we investigated the role of Pak in podocyte morphology. Pak1/2 were expressed in cultured podocytes. In mouse podocytes, Pak2 was predominantly phosphorylated, concentrated at the tips of the cellular processes, and its expression and/or phosphorylation were further increased when differentiated. Overexpression of rat nephrin in podocytes increased Pak1/2 phosphorylation, which was abolished when the Nck binding sites were mutated. Furthermore, dominant-negative Nck constructs blocked the Pak1 phosphorylation induced by antibody-mediated cross linking of nephrin. Transient transfection of constitutively kinase-active Pak1 into differentiated mouse podocytes decreased stress fibers, increased cortical F-actin, and extended the cellular processes, whereas kinase-dead mutant, kinase inhibitory construct, and Pak2 knockdown by shRNA had the opposite effect. In a rat model of puromycin aminonucleoside nephrosis, Pak1/2 phosphorylation was decreased in glomeruli, concomitantly with a decrease of nephrin tyrosine phosphorylation. These results suggest that Pak contributes to remodeling of the actin cytoskeleton in podocytes. Disturbed nephrin-Nck-Pak interaction may contribute to abnormal morphology of podocytes and proteinuria.
Impact of Cyclin B2 and Cell division cycle 2 on tubular hyperplasia in progressive chronic renal failure rats
Authors: Nishihara Kumiko , Masuda Satohiro , Nakagawa Shunsaku , Yonezawa Atsushi , Ichimura Takaharu , Bonventre Joseph V. , Inui Ken-ichi
Published: January 2010

To clarify the specific molecular events of progressive tubular damage in chronic renal failure (CRF), we conducted microarray analyses using isolated proximal tubules from subtotally nephrectomized (Nx) rats as a model of CRF. Our results clearly demonstrated time-dependent changes in gene expression profiles localized to proximal tubules. The expression of mitosis-specific genes Cyclin B2 and Cell division cycle 2 (Cdc2) was significantly and selectively increased in the proximal tubules during the compensated period but decreased to basal level in the end-stage period. Administration of everolimus, a potent inhibitor of mammalian target of rapamycin, markedly reduced compensatory hypertrophy and hyperplasia of epithelial cells, which was accompanied by complete abolishment of the expression of Cyclin B2 and Cdc2 enhancement; renal function was then severely decreased. Treatment with the Cdc2 inhibitor 2-cyanoethyl alsterpaullone clearly decreased epithelial cell hyperplasia, based on staining of phosphorylated histone H3 and Ki-67, while hypertrophy was not inhibited. In conclusion, we have demonstrated roles of Cyclin B2 and Cdc2 in the epithelial hyperplasia in response to Nx. These results advance the knowledge of the contribution of cell cycle regulators, especially M phase, in pathophysiology of tubular restoration and/or degeneration, and these two molecules are suggested to be a marker for the proliferation of proximal tubular cells in CRF.
Neural Correlates of High-Level Adaptation-Related Aftereffects
Authors: Cziraki Csaba , Greenlee Mark W. , Kovács Gyula
Published: January 2010

Prolonged exposure to complex stimuli, such as faces, biases perceptual decisions toward nonadapted, dissimilar stimuli, leading to contrastive aftereffects. Here we tested the neural correlates of this perceptual bias using a functional magnetic resonance imaging adaptation (fMRIa) paradigm. Adaptation to a face or hand stimulus led to aftereffects by biasing the categorization of subsequent ambiguous face/hand composite stimuli away from the adaptor category. The simultaneously observed fMRIa in the face-sensitive fusiform face area (FFA) and in the body-part–sensitive extrastriate body area (EBA) depended on the behavioral response of the subjects: adaptation to the preferred stimulus of the given area led to larger signal reduction during trials when it biased perception than during trials when it was less effective. Activity in two frontal areas correlated positively with the activity patterns in FFA and EBA. Based on our novel adaptation paradigm, the results suggest that the adaptation-induced aftereffects are mediated by the relative activity of category-sensitive areas of the human brain as demonstrated by fMRI.
Temporal Coding by Populations of Auditory Receptor Neurons
Authors: Sabourin Patrick , Pollack Gerald S.
Published: January 2010

Auditory receptor neurons of crickets are most sensitive to either low or high sound frequencies. Earlier work showed that the temporal coding properties of first-order auditory interneurons are matched to the temporal characteristics of natural low- and high-frequency stimuli (cricket songs and bat echolocation calls, respectively). We studied the temporal coding properties of receptor neurons and used modeling to investigate how activity within populations of low- and high-frequency receptors might contribute to the coding properties of interneurons. We confirm earlier findings that individual low-frequency-tuned receptors code stimulus temporal pattern poorly, but show that coding performance of a receptor population increases markedly with population size, due in part to low redundancy among the spike trains of different receptors. By contrast, individual high-frequency-tuned receptors code a stimulus temporal pattern fairly well and, because their spike trains are redundant, there is only a slight increase in coding performance with population size. The coding properties of low- and high-frequency receptor populations resemble those of interneurons in response to low- and high-frequency stimuli, suggesting that coding at the interneuron level is partly determined by the nature and organization of afferent input. Consistent with this, the sound-frequency-specific coding properties of an interneuron, previously demonstrated by analyzing its spike train, are also apparent in the subthreshold fluctuations in membrane potential that are generated by synaptic input from receptor neurons.
Cholinergic Modulation of Neuronal Excitability in the Rat Suprachiasmatic Nucleus
Authors: Yang Jyh-Jeen , Wang Yu-Ting , Cheng Pi-Cheng , Kuo Yeh-Jung , Huang Rong-Chi
Published: January 2010

The central cholinergic system regulates both the circadian clock and sleep-wake cycle and may participate in the feedback control of vigilance states on neural excitability in the suprachiasmatic nucleus (SCN) that houses the circadian clock. Here we investigate the mechanisms for cholinergic modulation of SCN neuron excitability. Cell-attached recordings indicate that the nonspecific cholinergic agonist carbachol (CCh) inhibited 55% and excited 21% SCN neurons, leaving 24% nonresponsive. Similar response proportions were produced by two muscarinic receptor [muscarinic acetylcholine receptor (mAChR)] agonists, muscarine and McN-A-343 (M1/4 agonist), but not by two nicotinic receptor (nAChR) agonists, nicotine and choline (α7-nAChR agonist), which, however, produced similar response proportions. Whole cell and perforated-patch recordings indicate that CCh inhibition of firing was mediated by membrane hyperpolarization due to activation of background K+currents, which were sensitive to submillimolar concentrations of Ba2+and to millimolar concentrations of TEA. RT-PCR analysis demonstrated the presence of mRNA for M1 to M5 mAChRs in SCN. The CCh-induced hyperpolarization and activation of background K+currents were blocked by M4 antagonists and to a lesser degree by M1 antagonists but were insensitive to the antagonists for M2 or M3, suggesting the involvement of M4 and M1 mAChRs in mediating CCh inhibition of firing. CCh enhancement of firing was mediated by membrane depolarization, as a result of postsynaptic inhibition of background K+currents. The multiple actions of cholinergic modulation via multiple receptors and ion channels may allow acetylcholine to finely control SCN neuron excitability in different physiological settings.
Mitochondrial Ca2+Activates a Cation Current inAplysiaBag Cell Neurons
Authors: Hickey Charlene M. , Geiger Julia E. , Groten Chris J. , Magoski Neil S.
Published: January 2010

Ion channels may be gated by Ca2+entering from the extracellular space or released from intracellular stores—typically the endoplasmic reticulum. The present study examines how Ca2+impacts ion channels in the bag cell neurons of Aplysia californica. These neuroendocrine cells trigger ovulation through an afterdischarge involving Ca2+influx from Ca2+channels and Ca2+release from both the mitochondria and endoplasmic reticulum. Liberating mitochondrial Ca2+with the protonophore, carbonyl cyanide-4-trifluoromethoxyphenyl-hydrazone (FCCP), depolarized bag cell neurons, whereas depleting endoplasmic reticulum Ca2+with the Ca2+-ATPase inhibitor, cyclopiazonic acid, did not. In a concentration-dependent manner, FCCP elicited an inward current associated with an increase in conductance and a linear current/voltage relationship that reversed near −40 mV. The reversal potential was unaffected by changing intracellular Cl−, but left-shifted when extracellular Ca2+was removed and right-shifted when intracellular K+was decreased. Strong buffering of intracellular Ca2+decreased the current, although the response was not altered by blocking Ca2+-dependent proteases. Furthermore, fura imaging demonstrated that FCCP elevated intracellular Ca2+with a time course similar to the current itself. Inhibiting either the V-type H+-ATPase or the ATP synthetase failed to produce a current, ruling out acidic Ca2+stores or disruption of ATP production as mechanisms for the FCCP response. Similarly, any involvement of reactive oxygen species potentially produced by mitochondrial depolarization was mitigated by the fact that dialysis with xanthine/xanthine oxidase did not evoke an inward current. However, both the FCCP-induced current and Ca2+elevation were diminished by disabling the mitochondrial permeability transition pore with the alkylating agent, N-ethylmaleimide. The data suggest that mitochondrial Ca2+gates a voltage-independent, nonselective cation current with the potential to drive the afterdischarge and contribute to reproduction. Employing Ca2+from mitochondria, rather than the more common endoplasmic reticulum, represents a diversification of the mechanisms that influence neuronal activity.
Identification of a Typical CSTR Using Optimal Focused Time Lagged Recurrent Neural Network Model with Gamma Memory Filter
Authors: Naikwad S. N. , Dudul S. V.
Published: January 2010

A focused time lagged recurrent neural network (FTLR NN) with gamma memory filter is designed to learn the subtle complex dynamics of a typical CSTR process. Continuous stirred tank reactor exhibits complex nonlinear operations where reaction is exothermic. It is noticed from literature review that process control of CSTR using neuro-fuzzy systems was attempted by many, but optimal neural network model for identification of CSTR process is not yet available. As CSTR process includes temporal relationship in the input-output mappings, time lagged recurrent neural network is particularly used for identification purpose. The standard back propagation algorithm with momentum term has been proposed in this model. The various parameters like number of processing elements, number of hidden layers, training and testing percentage, learning rule and transfer function in hidden and output layer are investigated on the basis of performance measures like MSE, NMSE, and correlation coefficient on testing data set. Finally effects of different norms are tested along with variation in gamma memory filter. It is demonstrated that dynamic NN model has a remarkable system identification capability for the problems considered in this paper. Thus FTLR NN with gamma memory filter can be used to learn underlying highly nonlinear dynamics of the system, which is a major contribution of this paper.
Spectral Approximation of Infinite‐Dimensional Black‐Scholes Equations with Memory
Authors: Chang Mou-Hsiung , Youree Roger K.
Published: January 2010

This paper considers the pricing of a European
option using a
(B, S)‐market
in which the stock price and the asset in the riskless bank
account both have hereditary price structures described by
the authors of this paper (1999). Under the smoothness assumption of the
payoff function, it is shown that the infinite dimensional
Black‐Scholes equation possesses a unique classical solution. A
spectral approximation scheme is developed using the Fourier
series expansion in the space C[−h, 0] for the Black‐Scholes equation. It is also shown that the nth approximant resembles the classical Black‐Scholes equation in finite
dimensions.
Statistical Analysis of Variation in the Human Plasma Proteome
Authors: Corzett Todd H. , Fodor Imola K. , Choi Megan W. , Walsworth Vicki L. , Turteltaub Kenneth W. , McCutchen-Maloney Sandra L. , Chromy Brett A.
Published: January 2010

Quantifying the variation in the human plasma proteome is an essential prerequisite for disease-specific biomarker detection. We report here on the longitudinal and individual variation in human plasma characterized by two-dimensional difference gel electrophoresis (2-D DIGE) using plasma samples from eleven healthy subjects collected three times over a two week period. Fixed-effects modeling was used to remove dye and gel variability. Mixed-effects modeling was then used to quantitate the sources of proteomic variation. The subject-to-subject variation represented the largest variance component, while the time-within-subject variation was comparable to the experimental variation found in a previous technical variability study where one human plasma sample was processed eight times in parallel and each was then analyzed by 2-D DIGE in triplicate. Here, 21 protein spots had larger than 50% CV, suggesting that these proteins may not be appropriate as biomarkers and should be carefully scrutinized in future studies. Seventy-eight protein spots showing differential protein levels between different individuals or individual collections were identified by mass spectrometry and further characterized using hierarchical clustering. The results present a first step toward understanding the complexity of longitudinal and individual variation in the human plasma proteome, and provide a baseline for improved biomarker discovery.
Frequency and Temperature Dependences of Dielectric Dispersion and Electrical Properties of Polyvinylidene Fluoride/Expanded Graphite Composites
Authors: Li Yu Chao , Li Robert Kwok Yiu , Tjong Sie Chin
Published: January 2010

A conductive nanofiller, expanded graphite (EG), was introduced into polyvinylidene fluoride (PVDF) by direct melt blending process. The electrical conductivity and dielectric properties of resulting PVDF/EG composites were investigated in a wide range of frequencies from 102 to 108 Hz. The dielectric dispersion and conductivity of the composite system exhibited a strong frequency dependence particularly in the vicinity of percolation threshold (Φc = 6 vol%). Moreover, the dielectric permittivity tended to decrease with increasing frequency while the conductivity displayed a reverse trend. A large permittivity was found in the composite having EG content near Φc. Accordingly, percolation concept and biased random walk approach can be used to describe the carrier transport of percolating PVDF/EG system. The conductivity and permittivity of percolating PVDF/EG composites were observed to be temperature dependent.
Bandwidth Reduction via Localized Peer-to-Peer (P2P) Video
Authors: Kerpez Ken , Luo Yuanqiu , Effenberger Frank J.
Published: January 2010

This paper presents recent research into P2P distribution of video that can be highly localized, preferably sharing content among users on the same access network and Central Office (CO). Models of video demand and localized P2P serving areas are presented. Detailed simulations of passive optical networks (PON) are run, and these generate statistics of P2P video localization. Next-Generation PON (NG-PON) is shown to fully enable P2P video localization, but the lower rates of Gigabit-PON (GPON) restrict performance. Results here show that nearlyallof the traffic volume of unicast video could be delivered via localized P2P. Strong growth in video delivery via localized P2P could lower overall future aggregation and core network bandwidth of IP video traffic by 58.2%, and total consumer Internet traffic by 43.5%. This assumes aggressive adoption of technologies and business practices that enable highly localized P2P video.
Release of Glycoprotein (GP1) from the Tegumental Surface ofTaenia soliumby Phospholipase C fromClostridium perfringensSuggests a Novel Protein-Anchor to Membranes
Authors: Landa Abraham , Willms Kaethe , Laclette Juan Pedro
Published: January 2010

In order to explore how molecules are linked to the membrane surface in larvalTaenia solium, whole cysticerci were incubated in the presence of phospholipase C fromClostridium perfringens(PLC). Released material was collected and analyzed in polyacrylamide gels with sodium dodecyl sulfate. Two major bands with apparent molecular weights of 180 and 43 kDa were observed. Western blot of released material and localization assays in cysticerci tissue sections using antibodies against five known surface glycoproteins ofT. soliumcysticerci indicated that only one, previously called GP1, was released. Similar localization studies using the lectins wheat-germ-agglutinin and Concanavalin A showed that N-acetyl-D-glucosamine, N-acetylneuraminic, sialic acid,αmethyl-D-mannoside, D-manose/glucose, and N-acetyl-D-glucosamine residues are abundantly present on the surface. On the other hand, we find that treatment with PLC releases molecules from the surface; they do not reveal Cross Reacting Determinant (CRD), suggesting a novel anchor to the membrane for the glycoprotein GP1.
Clot formation of neonates tested by thromboelastography correlates with gestational age
Authors: Strauss Tzipi , Levy-Shraga Yael , Ravid Bruria , Schushan-Eisen Irit , Maayan-Metzger Ayala , Kuint Jacob , Kenet Gili
Published: January 2010

Evaluation of clot formation in neonates is troublesome. Our aim was to investigate cord blood clot formation of pre-term versus full-term infants and adults, using rotating thromboelastogram (ROTEM®, Pentafarm, Munich, Germany). ROTEM was investigated in cord blood of 184 full-term and 47 pre-term infants. Measurements of the clotting time (CT), clot formation time (CFT) and maximal clot firmness (MCF) were obtained in order to asses reference values for this age group, and compare between full-term and pre-term neonates and compared to adult controls. For each infant demographic information and data regarding pregnancy and delivery were gathered. Infants were prospectively followed until discharge. CT and CFT were significantly shorter among pre-term and term infants as compared to adults [median CT: 185, 194, 293 seconds respectively, p≤0.001, CFT: 80, 76, 103 seconds respectively, p≤0.001). MCF was lower in pre-term and term as compared to adults (p≤0.001) with significantly lower values in pre-term as compared to full-term neonates (p=0.004). Clotting time and MCF correlated with gestational age (R=0.132, p=0.045, R= 0.259, p<0.001, respectively). No association was found between any ROTEM values and the occurrence of post-natal complications in infants of our study group. This is the first study assessing clot formation by ROTEM in pre-term infants. Clot formation parameters of term and premature infants correlated with gestational age. The predictive value of clot formation tests in neonates deserves further attention.
Lower versus standard intensity oral anticoagulant therapy (OAT) in elderly warfarin-experienced patients with non-valvular atrial fibrillation
Authors: Cucchini Umberto , Denas Gentian , Davidson Bruce , Marzot Filippo , Jose Seena Padayattil , Iliceto Sabino , Pengo Vittorio
Published: January 2010

It has been observed that elderly patients with nonvalvular atrial fibrillation (NVAF) benefit from standard [an international normalised ratio (INR) goal of 2.0–3.0] oral anticoagulant treatment (OAT). The hypothesis that lower-intensity anticoagulation therapy can offset the higher bleeding risk in this population has never been tested in an ‘ad hoc’ clinical trial. Patients over 75 years of age with NVAF were randomised to receive warfarin to maintain the INR at 1.8 (range 1.5–2.0) or at a standard target of 2.5 (range 2.0–3.0). There were 135 patients in the low-intensity and 132 in the standard-intensity groups. During a mean follow-up lasting 5.1 years, 59 primary outcome events (thromboembolism and major haemorrhage) were recorded, 24 (3.5 per 100 patient-years) in the low-intensity group and 35 (5.0 per 100 patient-years) in the standard-intensity group (HR=0.7, 95% CI 0.4–1.1, p=0.1). The reduction in the primary endpoint was mainly due to a diminution in major bleedings (1.9 vs. 3.0 per 100 patient-years; HR=0.6, 95% CI 0.3–1.2, p=0.1). The median achieved INR value was 1.86 in the low-intensity and 2.24 in the standard-intensity group (p<0.001). The frequency of INR testing was 26.1 ± 13.5 vs. 24.3 ± 11.6 days, p<0.0001). In this exploratory study we observed a low rate of stroke and major bleeding in elderly patients (>75) being managed in an anticoagulation clinic for primary stroke prevention with low-intensity anticoagulation (INR 1.5–2.0). However, further trials are needed to confirm the hypothesis generated by the present study.
ADP-receptor blockade: A case for personalised pharmacotherapy?
Authors: Geisler Tobias , Gawaz Meinrad , Zürn Christine
Published: January 2010

The dual antiplatelet therapy consisting of aspirin and the ADP-receptor blocker clopidogrel is the current standard medication after acute coronary events. However, clopidogrel is characterised by a high interindividual response variability, insufficient inhibition of platelet aggregation in a significant number of patients, relatively slow onset of efficacy and potential interaction with different co-medication via diverse hepatic cytochrome enzymes. In various trials, response variability of clopidogrel was translated into a higher rate of recurrent cardiovascular events. Different clinical and non-genetic factors contribute to the phenomenon of clopidogrel response variability. An individualised antithrombotic pharmacotherapy taking these factors into account, including the definition of status of response, verification of the efficacy by standardised platelet function testing, intensified or alternative platelet inhibition would be the ultimate goal for patients treated with clopidogrel. Currently, new drugs are on the way and promise a more consistent efficacy and smaller amount of response variability. However, the bleeding risk in subgroups of patients and further side effect profile remains to be clearly defined. Therefore, risk stratification models are warranted to identify patients who benefit from personalised pharmacotherapy in terms of improved clinical net benefit. In this review, we discuss treatment failure of clopidogrel based on platelet function testing, the mechanism of established and new ADP-blockers as well as new therapeutic principles.
Macrophage-modulating cytokines predict adverse outcome in heart failure
Authors: Hohensinner Philipp , Rychli Kathrin , Zorn Gerlinde , Hülsmann Martin , Berger Rudolf , Mörtl Deddo , Richter Bernhard , Huber Kurt , Wojta Johann , Niessner Alexander , Pacher Richard
Published: January 2010

Cytokines regulating the mobilisation, recruitment and survival of mononuclear cells may play an important role in progression of heart failure. Therefore, we investigated the role of granulocyte colony stimulating factor (G-CSF), monocyte chemoattractant protein 1 (MCP-1) and macrophage colony stimulating factor (M-CSF) in patients with advanced heart failure. G-CSF, MCP-1 and M-CSF were determined in plasma of 351 patients with advanced heart failure by specific ELISAs. During a median follow up period of 16 months (95% confidence interval [CI]: 15–17 months) 175 patients (50%) experienced the composite endpoint rehospitalisation and all-cause mortality. M-CSF tertiles were associated with a gradually increasing risk with hazard ratios (HR) of 2.2 (95% CI: 1.5–3.2; for trend, p<0.001) for the composite endpoint and 2.6 (95% CI: 1.5–4.6; for trend, p=0.002) for all-cause mortality comparing third and first tertile. These associations remained significant in a multivariable Cox regression model after adjustment for BNP and other known risk factors (p=0.043 and p=0.024). High MCP-1 concentrations were associated with an increased risk of all-cause mortality with an adjusted HR of 1.9 (third vs. first tertile, 95% CI: 1.1–3.3; for trend, p=0.034). In contrast, G-CSF tertiles were not significantly associated with the composite endpoint or all-cause mortality in multivariable Cox regression. In conclusion, the independent and concentration-dependent association of macrophage-modulating cytokines and in particular of M-CSF with adverse outcome in advanced HF patients suggests that these cytokines may play an important pathophysiological role in progression of cardiomyopathy.
Polymorphisms in platelet glycoproteins Ia and IIIa are associated with arterial thrombosis and carotid atherosclerosis in type 2 diabetes
Authors: Pellitero Silvia , Tàssies Dolors , Pizarro Eduarda , Monteagudo Juan , Salinas Isabel , Aguilera Eva , Sanmartí Anna , Reverter Juan Carlos , Reverter Jordi
Published: January 2010

To determine the genotype distributions of the polymorphisms in platelet glycoproteins (GP) Ib-alpha, Ia/IIa and IIb/IIIa and their association with clinical arterial thrombosis and preclinical carotid atherosclerosis in type 2 diabetes we studied 229 patients with type 2 diabetes and 229 controls matched by age, gender and ethnicity. Biochemical and haemostasis analyses were performed. The GP Ib-alpha VNTR, GP Ia 807 C/T and GP IIIa Pl(A) polymorphisms were determined by PCR. Thrombotic events were registered and carotid atherosclerosis was evaluated by ultrasound examination. A total of 107 patients had clinical atherothrombosis (CA), 65 subclinical atherosclerosis (SA), and 57 had no evidence of atherosclerosis (NA). There were no differences in allele frequencies and the genotype distribution of platelet GP polymorphisms between diabetic patients and controls. The VNTR Ib-alpha polymorphism was not associated with CA. We found a significant association between CA and the 807T (odds ratio [OR]: 2.86, confidence interval [CI]: 1.65–4.93; p<0.001) and PlA2 (OR: 2.03, CI: 1.13–3.65; p=0.03) alleles (in GP Ia and GP IIIa, respectively) in comparison to SA and NA group. Diabetic patients with the coexistence of the 807T and PlA2 alleles presented the highest risk of CA (OR: 3.59, CI: 1.64–7.8; p<0.001). The coexistence of both 807T and PlA2 alleles was also associated with the presence of SA (OR: 9.00, CI: 1.10–73.42; p=0.04). In conclusion, the 807T allele of GP Ia and the PlA2 allele of GP IIIa, and specially its combination, may confer an additional risk for development of carotid atherosclerosis and arterial thrombosis in type 2 diabetes.
Integrin cleavage regulates bidirectional signalling in vascular smooth muscle cells
Authors: Kappert Kai , Furundzija Vesna , Fritzsche Jan , Margeta Christian , Krüger Janine , Meyborg Heike , Fleck Eckart , Stawowy Philipp
Published: January 2010

Integrins link the cytoskeleton to the extracellular matrix, providing outside-in/inside-out signalling essential for vascular smooth muscle cell (VSMC) migration in atherosclerosis. The integrin αv subunit is synthesised from its precursor via furin-dependent endoproteolytic cleavage. Furin is a proprotein convertase (PC) highly expressed in VSMCs and in human atherosclerotic lesions. Inhibition of αv processing inhibits binding to vitronectin and migration. However, the precise role of furin-dependent αv cleavage on integrin bidirectional signalling and subsequent VSMC functions is unknown. Our present study demonstrates that the furin-like PC inhibitor decanoyl-RVKR-chloromethylke-tone (dec-CMK) inhibited αv cleavage. This reduced vitronectin-induced (outside-in) focal adhesion kinase (FAK)- and paxillin-phosphorylation, and VSMC motility. Inside-out-stimulated, integrin-mediated VSMC adhesion/migration relied on integrin-adaptor protein activation following protein kinase C (PKC) and ERK1/2 phosphorylation. In contrast to outside-in signalling, PKC-dependent phosphorylation of FAK and paxillin was unaffected by the status of integrin cleavage. Still, cytoskeleton and focal adhesion site rearrangements were modulated by the inhibition of furin-dependent integrin cleavage, thereby lessening inside-out dependent migration. Hence, we find that integrin bidirectional signalling is critically controlled by furin. Furin-dependent integrin processing modulates rapid adaptive integrin/cytoskeleton changes, essential to VSMC motility, which represents a crucial component in atherosclerosis and restenosis.