bluuebunny/crossref_metadata_2025 huggingface dataset:
Abundance of TRPC6 protein in glomerular mesangial cells is decreased by ROS and PKC in diabetes
Authors: Graham Sarabeth , Gorin Yves , Abboud Hanna E. , Ding Min , Lee Duck Yoon , Shi Honglian , Ding Yanfeng , Ma Rong
Published: April 2011

The present study was performed to investigate the underlying mechanism, particularly the roles of reactive oxygen species (ROS) and protein kinase C (PKC), in the diabetes-induced canonical transient receptor potential 6 (TRPC6) downregulation. We found that high glucose (HG) significantly reduced TRPC6 protein expression in cultured mesangial cells (MCs). TRPC6 protein was also significantly reduced in the glomeruli but not in the heart or aorta isolated from streptozotocin-induced diabetic rats. In the cultured MCs, H2O2 suppressed TRPC6 protein expression in a dose- and time-dependent manner, which emulated the HG effect. Catalase as well as superoxide dismutase were able to prevent the inhibitory effect of HG on TRPC6. The antioxidant effect observed in cultured cells was also observed in diabetic rats treated with tempol for 2 wk, which exhibited a preservation of TRPC6 in the glomeruli. Specific knockdown of Nox4, a component of NADPH oxidase, increased TRPC6 protein expression. Furthermore, the PKC activator phorbol 12-myristate 13-acetate (PMA), but not its analog 4α-phorbol 12, 13-didecanoate (4α-PDD), suppressed TRPC6 expression, and this PMA effect was not affected by catalase. Moreover, Gö6976, but not LY333531, attenuated the negative effect of HG on TRPC6 expression. Gö6976 also inhibited H2O2 effect on TRPC6. Furthermore, either knockdown of TRPC6 or HG treatment significantly decreased ANG II-stimulated MC contraction, and the HG-impaired MC contraction was rescued by overexpression of TRPC6. These results suggest that hyperglycemia in diabetes downregulated TRPC6 protein expression in MCs through a NADPH oxidase Nox4-ROS-PKC pathway, proving a mechanism for impaired MC contraction in diabetes.
Endothelin-1 contributes to increased NFATc3 activation by chronic hypoxia in pulmonary arteries
Authors: de Frutos Sergio , Ramiro Diaz Juan Manuel , Nitta Carlos H. , Sherpa Mingma L. , Gonzalez Bosc Laura V.
Published: April 2011

Chronic hypoxia (CH) activates the Ca2+-dependent transcription factor nuclear factor of activated T cells isoform c3 (NFATc3) in mouse pulmonary arteries. However, the mechanism of this response has not been explored. Since we have demonstrated that NFATc3 is required for CH-induced pulmonary arterial remodeling, establishing how CH activates NFATc3 is physiologically significant. The goal of this study was to test the hypothesis that endothelin-1 (ET-1) contributes to CH-induced NFATc3 activation. We propose that this mechanism requires increased pulmonary arterial smooth muscle cell (PASMC) intracellular Ca2+ concentration ([Ca2+]i) and stimulation of RhoA/Rho kinase (ROK), leading to calcineurin activation and actin cytoskeleton polymerization, respectively. We found that: 1) CH increases pulmonary arterial pre-pro-ET-1 mRNA expression and lung RhoA activity; 2) inhibition of ET receptors, calcineurin, L-type Ca2+ channels, and ROK blunts CH-induced NFATc3 activation in isolated intrapulmonary arteries from NFAT-luciferase reporter mice; and 3) both ET-1-induced NFATc3 activation in isolated mouse pulmonary arteries ex vivo and ET-1-induced NFATc3-green fluorescence protein nuclear import in human PASMC depend on ROK and actin polymerization. This study suggests that CH increases ET-1 expression, thereby elevating PASMC [Ca2+]i and RhoA/ROK activity. As previously demonstrated, elevated [Ca2+]i is required to activate calcineurin, which dephosphorylates NFATc3, allowing its nuclear import. Here, we demonstrate that ROK increases actin polymerization, thus providing structural support for NFATc3 nuclear transport.
Inhibition in the balance: binaurally coupled inhibitory feedback in sound localization circuitry
Authors: Burger R. Michael , Fukui Iwao , Ohmori Harunori , Rubel Edwin W.
Published: April 2011

Interaural time differences (ITDs) are the primary cue animals, including humans, use to localize low-frequency sounds. In vertebrate auditory systems, dedicated ITD processing neural circuitry performs an exacting task, the discrimination of microsecond differences in stimulus arrival time at the two ears by coincidence-detecting neurons. These neurons modulate responses over their entire dynamic range to sounds differing in ITD by mere hundreds of microseconds. The well-understood function of this circuitry in birds has provided a fruitful system to investigate how inhibition contributes to neural computation at the synaptic, cellular, and systems level. Our recent studies in the chicken have made significant progress in bringing together many of these findings to provide a cohesive picture of inhibitory function.
Inactivation and stimulation of the frontal pursuit area change pursuit metrics without affecting pursuit target selection
Authors: Mahaffy Shaun , Krauzlis Richard J.
Published: April 2011

The frontal pursuit area (FPA) lies posterior to the frontal eye fields in the frontal cortex and contains neurons that are directionally selective for pursuit eye movements. Lesions of the FPA (alternately called “FEFsem”) cause deficits in pursuit acceleration and velocity, which are largest for movements directed toward the lesioned side. Conversely, stimulation of the FPA evokes pursuit from fixation and increases the gain of the pursuit response. On the basis of these properties, it has been hypothesized that the FPA could underlie the selection of pursuit direction. To test this possibility, we manipulated FPA activity and measured the effect on target selection behavior in rhesus monkeys. First, we unilaterally inactivated the FPA with the GABA agonist muscimol. We then measured the monkeys' performance on a pursuit-choice task. Second, we applied microstimulation unilaterally to the FPA during pursuit initiation while monkeys performed the same pursuit-choice task. Both of these manipulations produced significant effects on pursuit metrics; the inactivation decreased pursuit velocity and acceleration, and microstimulation evoked pursuit directly. Despite these changes, both manipulations failed to significantly alter choice behavior. These results show that FPA activity is not necessary for pursuit target selection.
Calcium-dependent phosphorylation regulates neuronal stability and plasticity in a highly precise pacemaker nucleus
Authors: George Andrew A. , Macleod Gregory T. , Zakon Harold H.
Published: April 2011

Specific types of neurons show stable, predictable excitability properties, while other neurons show transient adaptive plasticity of their excitability. However, little attention has been paid to how the cellular pathways underlying adaptive plasticity interact with those that maintain neuronal stability. We addressed this question in the pacemaker neurons from a weakly electric fish because these neurons show a highly stable spontaneous firing rate as well as an N-methyl-d-aspartate (NMDA) receptor-dependent form of plasticity. We found that basal firing rates were regulated by a serial interaction of conventional and atypical PKC isoforms and that this interaction establishes individual differences within the species. We observed that NMDA receptor-dependent plasticity is achieved by further activation of these kinases. Importantly, the PKC pathway is maintained in an unsaturated baseline state to allow further Ca2+-dependent activation during plasticity. On the other hand, the Ca2+/calmodulin-dependent phosphatase calcineurin does not regulate baseline firing but is recruited to control the duration of the NMDA receptor-dependent plasticity and return the pacemaker firing rate back to baseline. This work illustrates how neuronal plasticity can be realized by biasing ongoing mechanisms of stability (e.g., PKC) and terminated by recruiting alternative mechanisms (e.g., calcineurin) that constrain excitability. We propose this as a general model for regulating activity-dependent change in neuronal excitability.
Acetylcholine and norepinephrine mediate GABAergic but not glycinergic transmission enhancement by melittin in adult rat substantia gelatinosa neurons
Authors: Liu Tao , Fujita Tsugumi , Kumamoto Eiichi
Published: April 2011

GABAergic and glycinergic inhibitory synaptic transmissions in substantia gelatinosa (SG; lamina II of Rexed) neurons of the spinal dorsal horn play an important role in regulating nociceptive transmission from the periphery. It has not yet been well known whether each of the inhibitory transmissions plays a distinct role in the regulation. We report an involvement of neurotransmitters in GABAergic but not glycinergic transmission enhancement produced by the PLA2activator melittin, where the whole-cell patch-clamp technique is applied to the SG neurons of adult rat spinal cord slices. Glycinergic but not GABAergic spontaneous inhibitory postsynaptic current (sIPSC) was increased in frequency and amplitude by melittin in the presence of nicotinic, muscarinic acetylcholine, and α1-adrenergic receptor antagonists (mecamylamine, atropine, and WB-4101, respectively). GABAergic transmission enhancement produced by melittin was unaffected by the 5-hydroxytryptamine 3 receptor and P2X receptor antagonists (ICS-205,930 and pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid, respectively). Nicotinic and muscarinic acetylcholine receptor agonists [(−)-nicotine and carbamoylcholine, respectively] and norepinephrine, as well as melittin, increased GABAergic sIPSC frequency and amplitude. A repeated application of (−)-nicotine, carbamoylcholine, and norepinephrine, but not melittin, at an interval of 30 min produced a similar transmission enhancement. These results indicate that melittin produces the release of acetylcholine and norepinephrine, which activate (nicotinic and muscarinic) acetylcholine and α1-adrenergic receptors, respectively, resulting in GABAergic but not glycinergic transmission enhancement in SG neurons. The desensitization of a system leading to the acetylcholine and norepinephrine release is slow in recovery. This distinction in modulation between GABAergic and glycinergic transmissions may play a role in regulating nociceptive transmission.
Modification of saccadic gain by reinforcement
Authors: Madelain Laurent , Paeye Céline , Wallman Josh
Published: April 2011

Control of saccadic gain is often viewed as a simple compensatory process in which gain is adjusted over many trials by the postsaccadic retinal error, thereby maintaining saccadic accuracy. Here, we propose that gain might also be changed by a reinforcement process not requiring a visual error. To test this hypothesis, we used experimental paradigms in which retinal error was removed by extinguishing the target at the start of each saccade and either an auditory tone or the vision of the target on the fovea was provided as reinforcement after those saccades that met an amplitude criterion. These reinforcement procedures caused a progressive change in saccade amplitude in nearly all subjects, although the rate of adaptation differed greatly among subjects. When we reversed the contingencies and reinforced those saccades landing closer to the original target location, saccade gain changed back toward normal gain in most subjects. When subjects had saccades adapted first by reinforcement and a week later by conventional intrasaccadic step adaptation, both paradigms yielded similar degrees of gain changes and similar transfer to new amplitudes and to new starting positions of the target step as well as comparable rates of recovery. We interpret these changes in saccadic gain in the absence of postsaccadic retinal error as showing that saccade adaptation is not controlled by a single error signal. More generally, our findings suggest that normal saccade adaptation might involve general learning mechanisms rather than only specialized mechanisms for motor calibration.
Honeybees as a Model for the Study of Visually Guided Flight, Navigation, and Biologically Inspired Robotics
Authors: Srinivasan Mandyam V.
Published: April 2011

Research over the past century has revealed the impressive capacities of the honeybee, Apis mellifera , in relation to visual perception, flight guidance, navigation, and learning and memory. These observations, coupled with the relative ease with which these creatures can be trained, and the relative simplicity of their nervous systems, have made honeybees an attractive model in which to pursue general principles of sensorimotor function in a variety of contexts, many of which pertain not just to honeybees, but several other animal species, including humans. This review begins by describing the principles of visual guidance that underlie perception of the world in three dimensions, obstacle avoidance, control of flight speed, and orchestrating smooth landings. We then consider how navigation over long distances is accomplished, with particular reference to how bees use information from the celestial compass to determine their flight bearing, and information from the movement of the environment in their eyes to gauge how far they have flown. Finally, we illustrate how some of the principles gleaned from these studies are now being used to design novel, biologically inspired algorithms for the guidance of unmanned aerial vehicles.
Physiology of Microglia
Authors: Kettenmann Helmut , Hanisch Uwe-Karsten , Noda Mami , Verkhratsky Alexei
Published: April 2011

Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed “resting microglia.” Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the “activated microglial cell.” This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
Axon Physiology
Authors: Debanne Dominique , Campanac Emilie , Bialowas Andrzej , Carlier Edmond , Alcaraz Gisèle
Published: April 2011

Axons are generally considered as reliable transmission cables in which stable propagation occurs once an action potential is generated. Axon dysfunction occupies a central position in many inherited and acquired neurological disorders that affect both peripheral and central neurons. Recent findings suggest that the functional and computational repertoire of the axon is much richer than traditionally thought. Beyond classical axonal propagation, intrinsic voltage-gated ionic currents together with the geometrical properties of the axon determine several complex operations that not only control signal processing in brain circuits but also neuronal timing and synaptic efficacy. Recent evidence for the implication of these forms of axonal computation in the short-term dynamics of neuronal communication is discussed. Finally, we review how neuronal activity regulates both axon morphology and axonal function on a long-term time scale during development and adulthood.
Biology of Human Sodium Glucose Transporters
Authors: Wright Ernest M. , Loo Donald D. F. , Hirayama Bruce A.
Published: April 2011

There are two classes of glucose transporters involved in glucose homeostasis in the body, the facilitated transporters or uniporters (GLUTs) and the active transporters or symporters (SGLTs). The energy for active glucose transport is provided by the sodium gradient across the cell membrane, the Na+glucose cotransport hypothesis first proposed in 1960 by Crane. Since the cloning of SGLT1 in 1987, there have been advances in the genetics, molecular biology, biochemistry, biophysics, and structure of SGLTs. There are 12 members of the human SGLT (SLC5) gene family, including cotransporters for sugars, anions, vitamins, and short-chain fatty acids. Here we give a personal review of these advances. The SGLTs belong to a structural class of membrane proteins from unrelated gene families of antiporters and Na+and H+symporters. This class shares a common atomic architecture and a common transport mechanism. SGLTs also function as water and urea channels, glucose sensors, and coupled-water and urea transporters. We also discuss the physiology and pathophysiology of SGLTs, e.g., glucose galactose malabsorption and familial renal glycosuria, and briefly report on targeting of SGLTs for new therapies for diabetes.
Local Gene Delivery System by Bubble Liposomes and Ultrasound Exposure into Joint Synovium
Authors: Negishi Yoichi , Tsunoda Yuka , Endo-Takahashi Yoko , Oda Yusuke , Suzuki Ryo , Maruyama Kazuo , Yamamoto Matsuo , Aramaki Yukihiko
Published: April 2011

Recently, we have developed novel polyethylene glycol modified liposomes (bubble liposomes; BL) entrapping an ultrasound (US) imaging gas, which can work as a gene delivery tool with US exposure. In this study, we investigated the usefulness of US-mediated gene transfer systems with BL into synoviocytes in vitro and joint synovium in vivo. Highly efficient gene transfer could be achieved in the cultured primary synoviocytes transfected with the combination of BL and US exposure, compared to treatment with plasmid DNA (pDNA) alone, pDNA plus BL, or pDNA plus US. When BL was injected into the knee joints of mice, and US exposure was applied transcutaneously to the injection site, highly efficient gene expression could be observed in the knee joint transfected with the combination of BL and US exposure, compared to treatment with pDNA alone, pDNA plus BL, or pDNA plus US. The localized and prolonged gene expression was also shown by an in vivo luciferase imaging system. Thus, this local gene delivery system into joint synovium using the combination of BL and US exposure may be an effective means for gene therapy in joint disorders.
A Comparison of Flame Spread Characteristics over Solids in Concurrent Flow Using Two Different Pyrolysis Models
Authors: Tseng Ya-Ting , T′ien James S.
Published: April 2011

Two solid pyrolysis models are employed in a concurrent‐flow flame spread model to compare the flame structure and spreading characteristics. The first is a zeroth‐order surface pyrolysis, and the second is a first‐order in‐depth pyrolysis. Comparisons are made for samples when the spread rate reaches a steady value and the flame reaches a constant length. The computed results show (1) the mass burning rate distributions at the solid surface are qualitatively different near the flame (pyrolysis base region), (2) the first‐order pyrolysis model shows that the propagating flame leaves unburnt solid fuel, and (3) the flame length and spread rate dependence on sample thickness are different for the two cases.
Acute Arterial Thrombosis after Covered Stent Exclusion of Bleeding Mycotic Pseudoaneurysm: Treatment Using Catheter-Directed Thrombolysis
Authors: Palestrant Sarah , Knuttinen M. Grace , Gaba Ron C. , Bui James T. , Owens Charles A.
Published: April 2011

Conventional absolute contraindications to catheter-directed thrombolysis include active or recent hemorrhage and the presence of local vascular infection, both of which increase the risk of procedure-related complications such as bleeding and systemic sepsis. For this reason, lytic therapy of arterial thromboembolism under these circumstances is generally precluded. Herein, we describe a unique case of safe catheter-directed lysis of an acutely thrombosed iliac artery following covered stent placement for treatment of an actively bleeding infected pseudoaneurysm. Our management approach is discussed.
Mechanisms That Regulate Peripheral Immune Responses to Control Organ-Specific Autoimmunity
Authors: Hoyne Gerard F.
Published: April 2011

The immune system must balance the need to maintain a diverse repertoire of lymphocytes to be able to fight infection with the need to maintain tolerance to self-proteins. The immune system places strict regulation over the ability of T cells to produce the major T cell growth factor interleukin 2 as this cytokine can influence a variety of immune outcomes. T cells require the delivery of two signals, one through the antigen receptor and a second through the costimulatory receptor CD28. The immune system uses a variety of E3 ubiquitin ligases to target signaling proteins that function downstream of the TCR and CD28 receptors. Mutations in these E3 ligases can lead to a breakdown in immune tolerance and development of autoimmunity. This paper will examine the role of a range of E3 ubiquitin ligases and signaling pathways that influence the development of T-cell effector responses and the development of organ-specific autoimmune diseases such as type 1 diabetes.
Identification of Missense Mutation (I12T) in the BSND Gene and Bioinformatics Analysis
Authors: Iqbal Hina , Sarfaraz Tayyba , Anjum Farida , Anwar Zubair , Mir Asif
Published: April 2011

Nonsyndromic hearing loss is a paradigm of genetic heterogeneity with 85 loci and 39 nuclear disease genes reported so far. Mutations of BSND have been shown to cause Bartter syndrome type IV, characterized by significant renal abnormalities and deafness and nonsyndromic nearing loss. We studied a Pakistani consanguineous family. Clinical examinations of affected individuals did not reveal the presence of any associated signs, which are hallmarks of the Bartter syndrome type IV. Linkage analysis identified an area of 18.36 Mb shared by all affected individuals between markers D1S2706 and D1S1596. A maximum two‐point LOD score of 2.55 with markers D1S2700 and multipoint LOD score of 3.42 with marker D1S1661 were obtained. BSND mutation, that is, p.I12T, cosegregated in all extant members of our pedigree. BSND mutations can cause nonsyndromic hearing loss, and it is a second report for this mutation. The respected protein, that is, BSND, was first modeled, and then, the identified mutation was further analyzed by using different bioinformatics tools; finally, this protein and its mutant was docked with CLCNKB and REN, interactions of BSND, respectively.
Protective Effects of Luteolin on Diabetic Nephropathy in STZ‐Induced Diabetic Rats
Authors: Wang Guo Guang , Lu Xiao Hua , Li Wei , Zhao Xue , Zhang Cui
Published: April 2011

Diabetic nephropathy is a long‐term complication of diabetic mellitus. Many experimental evidences suggest that persistent hyperglycaemia generates intracellular reactive oxygen species (ROS) and upregulates transforming growth factor‐b1 and extracellular matrix expression in mesangial and tubular epithelial cells, which is involved of free radicals in the pathogenesis of diabetes and more importantly in the development of diabetic complications. Antioxidants effectively inhibit high‐glucose‐ and H2O2‐induced transforming growth factor‐b1 and fibronectin upregulation, thus providing evidence that ROS play an important role in high glucose‐induced renal injury. The flavonoid luteolin has been shown to possess direct antioxidant activity, therefore we hypothesize that it may be useful in treatment of many chronic disease associated with oxidative stress, such as diabetic nephropathy via its antioxidant properties. Our results suggested that protection against development of diabetic nephropathy by luteolin treatment involved changes in superoxide dismutase (SOD) activity, the malondialdehyde (MDA) content and expression of Heme Oxygenase‐1 (HO‐1) protein.
Technical Advances in Skin Sparing Mastectomy
Authors: Carlson Grant W.
Published: April 2011

Skin sparing mastectomy has resulted in marked improvement in the aesthetic results of immediate breast reconstruction. Mature data has confirmed its oncological safety in the treatment of breast cancer. The procedure has gained wide acceptance and has undergone numerous technical advances since its introduction over twenty years ago. Careful patient selection and choice of skin incisions are necessary to avoid complications.
Technetium‐99m‐Labeled Autologous Serum Albumin: A Personal‐Exclusive Source of Serum Component
Authors: Wang Yuh-Feng , Chen Yi-Chun , Li Dian-Kun , Chuang Mei-Hua
Published: April 2011

Technetium‐99m human serum albumin (99mTc‐HSA) is an important radiopharmaceutical required in nuclear medicine studies. However, the risk of transfusion‐transmitted infection remains a major safety concern. Autopreparation of serum component acquired from patient provides a “personal‐exclusive” source for radiolabeling. This paper is to evaluate the practicality of on‐site elusion and subsequent radiolabeling efficacy for serum albumin. Results showed that the autologous elute contained more albumin fraction than serum without extraction procedure. Good radiochemical purity and stability were demonstrated after radiolabeling. Biodistribution study showed that labeled albumin accumulated immediately in the lung, liver, and kidney. It was cleared steadily and excreted in the urine. The biologic half‐life was defined, and all samples passed the pyrogenicity and sterility tests. In conclusion, autoalbumin could be extracted and radiolabeled properly in a nuclear medicine setting. Moreover, the risk of transfusion‐transmitted infection associated with nonautologous, multisource 99mTc‐HSA agents can be reduced.
Spontaneous Supraceliac Isolated Abdominal Aortic Dissection Sparing Major Visceral and Renal Vessels and Presenting as Chronic Limb Ischemia
Authors: Bello Sean O. Z. , Kouerinis Ilias , Pillay Woolagasen
Published: April 2011

Aortic dissections that originate from isolated tears in the abdominal aorta are uncommon. Rarer still are cases of isolated abdominal aortic dissections arising in suprarenal locations, as most appear from infrarenal intimal defects. We present a quite unusual case of a spontaneous supraceliac isolated abdominal aortic dissection sparing the renal and mesenteric arteries and manifesting as chronic rather than acute limb ischemia. The atypical presentation of this case led to repeated misdiagnosis with consequent loss of part of the patient's limb. Better illustration of the natural history of this ill-defined pathology is needed to aid understanding and improve patient care.
Efficient Congestion Mitigation Using Congestion-Aware Steiner Trees and Network Coding Topologies
Authors: Chaudhry M. A. R. , Asad Z. , Sprintson A. , Hu J.
Published: April 2011

In the advent of smaller devices, a significant increase in the density of on-chip components has raised congestion
and overflow as critical issues in VLSI physical design automation. In this paper, we present novel techniques for
reducing congestion and minimizing overflows. Our methods are based on ripping up nets that go through the
congested areas and replacing them with congestion-aware topologies.
Our contributions can be summarized as follows. First, we present several efficient algorithms for finding
congestion-aware Steiner trees that is, trees that avoid congested areas of the chip. Next, we show that the novel
technique of network coding can lead to further improvements in routability, reduction of congestion, and overflow
avoidance. Finally, we present an algorithm for identifying efficient congestion-aware network coding topologies.
We evaluate the performance of the proposed algorithms through extensive simulations.
Differential Neuroprotection of Selective Estrogen Receptor Agonists against Autonomic Dysfunction and Ischemic Cell Death in Permanent versus Reperfusion Injury
Authors: Connell Barry J. , Saleh Tarek M.
Published: April 2011

In the present study, we tested the hypothesis that selective activation of estrogen receptor subtypes (ERαand ERβ) would be neuroprotective following ischemia and/or ischemia-reperfusion, as well as prevent the associated autonomic dysfunction. The selective ERαagonist, PPT, when administered 30 min prior to occlusion of the middle cerebral artery (pMCAO), resulted in a dose-dependent neuroprotection as measured 6 hours postpermanent MCAO, but not following 30 mins of MCAO followed by 5.5 hrs of reperfusion (I/R). In contrast, 30 min pretreatment with the selective ERβagonist, DPN, resulted in a dose-dependent neuroprotection following I/R, but was not protective following pMCAO. Both drugs prevented the ischemia-induced autonomic dysfunction as measured by a decrease in the baroreceptor reflex sensitivity (BRS). The data presented here suggest a differential role of each ER subtype in targeting the mechanisms of cell death that occur in ischemia versus reperfusion injury.
Bortezomib Primes Glioblastoma, Including Glioblastoma Stem Cells, for TRAIL by Increasing tBid Stability and Mitochondrial Apoptosis
Authors: Unterkircher Thomas , Cristofanon Silvia , Vellanki Sri Hari Krishna , Nonnenmacher Lisa , Karpel-Massler Georg , Wirtz Christian Rainer , Debatin Klaus-Michael , Fulda Simone
Published: April 2011

Purpose: Searching for novel approaches to sensitize glioblastoma for cell death, we investigated the proteasome inhibitor bortezomib.

Experimental Design: The effect of bortezomib on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)–induced apoptosis signaling pathways was analyzed in glioblastoma cell lines, primary glioblastoma cultures, and in an in vivo model.

Results: Bortezomib and TRAIL synergistically trigger cell death and reduce colony formation of glioblastoma cells (combination index < 0.1). Investigations into the underlying molecular mechanisms reveal that bortezomib and TRAIL act in concert to cause accumulation of tBid, the active cleavage product of Bid. Also, the stability of TRAIL-derived tBid markedly increases on proteasome inhibition. Notably, knockdown of Bid significantly decreases bortezomib- and TRAIL-mediated cell death. By comparison, silencing of Noxa, which is also upregulated by bortezomib, does not confer protection. Coinciding with tBid accumulation, the activation of Bax/Bak and loss of mitochondrial membrane potential are strongly increased in cotreated cells. Overexpression of Bcl-2 significantly reduces mitochondrial perturbations and cell death, underscoring the functional relevance of the mitochondrial pathway. In addition, bortezomib cooperates with TRAIL to reduce colony formation of glioblastoma cells, showing an effect on long-term survival. Of note, bortezomib profoundly enhances TRAIL-triggered cell death in primary cultured glioblastoma cells and in patient-derived glioblastoma stem cells, underlining the clinical relevance. Importantly, bortezomib cooperates with TRAIL to suppress tumor growth in an in vivo glioblastoma model.

Conclusion: These findings provide compelling evidence that the combination of bortezomib and TRAIL presents a promising novel strategy to trigger cell death in glioblastoma, including glioblastoma stem cells, which warrants further investigation. Clin Cancer Res; 17(12); 4019–30. ©2011 AACR.
Brain Size and Social Complexity: A Computed Tomography Study in Hyaenidae
Authors: Sakai Sharleen T. , Arsznov Bradley M. , Lundrigan Barbara L. , Holekamp Kay E.
Published: April 2011

The social brain hypothesis posits that the demands of living in complex social groups require increased neural processing, and that this underlies the expansion of brain areas involved in mediation of complex social behavior. However, much of the support for the social brain hypothesis is derived from comparative studies in primates. If large brains evolved as a result of selection pressures imposed by life within complex societies, as the social brain hypothesis predicts, then gregarious nonprimate species should possess large brains and exhibit comparable expansion of brain areas mediating social behavior. Our purpose here was to test a prediction of the social brain hypothesis – that increased brain size is related to social complexity – by examining species in the carnivore family Hyaenidae. Hyaenidae contains 4 extant species that span a spectrum of social complexity: the aardwolf (Proteles cristata) is solitary during the nonbreeding season, and forms monogamous pairs during the breeding season; the striped hyena (Hyaena hyaena) lives solitarily or in small groups; the brown hyena (Parahyaena brunnea) lives in groups of up to 14 individuals; and the spotted hyena (Crocuta crocuta) lives in complex hierarchically organized groups containing up to 90 animals. Computed tomography was used to create three-dimensional endocasts based on serial analysis of coronal sections of the adult endocranium. The largest brain volume, relative to body size, is found in the spotted hyena. We found no significant variation in relative brain volume among striped hyenas, brown hyenas, and aardwolves. The spotted hyena also possesses a larger anterior cerebrum volume relative to total brain volume than is found in the other hyena species; this region is composed primarily of frontal cortex. These data are consistent with the idea that expansion of the frontal cortex is driven by the demands of processing cognitive information associated with complex social lives, but other factors may drive the evolution of large brains in hyaenids.
The Cooperation of Enamelin and Amelogenin in Controlling Octacalcium Phosphate Crystal Morphology
Authors: Fan Daming , Iijima Mayumi , Bromley Keith M. , Yang Xiudong , Mathew Shibi , Moradian-Oldak Janet
Published: April 2011

Enamel matrix proteins, including the most abundant amelogenin and lesser amounts of enamelin, ameloblastin, and proteinases, play vital roles in controlling crystal nucleation and growth during enamel formation. The cooperative action between amelogenin and the 32-kDa enamelin is critical to regulating the growth morphology of octacalcium phosphate crystals. Using biophysical methods, we investigated the interaction between the 32-kDa enamelin and recombinant pig amelogenin 148 (rP148) at pH 6.5 in phosphate-buffered saline (PBS). Dynamic light scattering results showed a trend of increasing particle size in the mixture with the addition of enamelin to amelogenin. Upon addition of the 32-kDa enamelin, the shift and intensity decrease in the ellipticity minima of rP148 in the circular dichroism spectra of rP148 illustrated a direct interaction between the 2 proteins. In the fluorescence spectra, the maximum emission of rP148 was blue shifted from 335 to 333 nm in the presence of enamelin as a result of complexation of the 2 proteins. Our results demonstrate that the 32-kDa enamelin has a close association with amelogenin at pH 6.5 in PBS buffer. Our present study provides novel insights into the possible cooperation between enamelin and amelogenin in macromolecular coassembly and in controlling enamel mineral formation
Enamel Pathology Resulting from Loss of Function in the Cystic Fibrosis Transmembrane Conductance Regulator in a Porcine Animal Model
Authors: Chang Eugene H. , Lacruz Rodrigo S. , Bromage Timothy G. , Bringas, Jr. Pablo , Welsh Michael J. , Zabner Joseph , Paine Michael L.
Published: April 2011

Cystic fibrosis (CF) is caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR), a phosphorylation- and ATP-regulated anion channel. CFTR expression and activity is frequently associated with an anion exchanger (AE) such as AE2 coded by the Slc4a2 gene. Mice null for Cftr and mice null for Slc4a2 have enamel defects, and there are some case reports of enamel anomalies in patients with CF. In this study we demonstrate that both Cftr and AE2 expression increased significantly during the rat enamel maturation stage versus the earlier secretory stage (5.6- and 2.9-fold, respectively). These qPCR data im- ply that there is a greater demand for Cl– and bicarbonate (HCO3–) transport during the maturation stage of enamel formation, and that this is, at least in part, provided by changes in Cftr and AE2 expression. In addition, the enamel phenotypes of 2 porcine models of CF, CFTR-null, and CFTR-ΔF508 have been examined using backscattered electron microscopy in a scanning electron microscope. The enamel of newborn CFTR-null and CFTR-ΔF508 animals is hypomineralized. Together, these data provide a molecular basis for interpreting enamel disease associated with disruptions to CFTR and AE2 expression.
Long-Term, Clinical Follow-Up in Fatty Liver Patients
Authors: Bendtsen Flemming , Dam-Larsen Sanne
Published: April 2011

The risk of progression to cirrhosis and death in patients with pure alcoholic (AFLD) and non-alcoholic steatosis (NAFLD) has only sparsely been studied. The aims of the present long-term follow-up study were to analyze for risks of progression to cirrhosis and death in a cohort of patients with histologically verified ‘pure fatty liver’. 247 patients with biopsy verified AFLD and 170 patients with NAFLD without inflammation were included in the period from 1978 to 1987. Patients in the study cohort were linked through their personal identification number to The National Patient Registry (LPR) and The Causes of Death Registry. All admissions, discharge diagnoses, and causes of death were obtained from January 1, 1977 until death (2004) or December 31, 1999 in the registries. Surviving patients were offered a clinical follow-up in 2004. Survival was observed to be significantly higher (p < 0.01) in NAFLD for men as well as for women, which was not different from the Danish age- and gender-matched population. Two (1.2%) patients with NAFLD developed cirrhosis, while 54 patients (21.9%) with AFLD developed cirrhosis. The degree of steatosis was the only histological parameter significantly associated with premature death in AFLD, but not in NAFLD patients. Risk of progression to cirrhosis and time to development was significantly associated to being of female gender. In conclusion, for patients with NAFLD, survival was good, while patients with AFLD had excess in mortality and risk of development of cirrhosis, which was associated with the degree of steatosis in the index biopsy and being of female gender.
Induction of Cross-Linking and Silencing of Sp1 by Transglutaminase during Liver Injury in ASH and NASH via Different ER Stress Pathways
Authors: Kojima Soichi , Kuo Ting-Fang , Tatsukawa Hideki , Hirose Shigehisa
Published: April 2011

Alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH) share many histological similarities, but the molecular mechanisms responsible for hepatic apoptosis remain unclear. We previously reported that transglutaminase 2 (TG2), a protein cross-linking enzyme, is induced in the nucleus of ethanol-treated hepatocytes, and cross-links and inactivates a general transcription factor Sp1, which eventually leads to reduced expression of c-Met and caspase-independent hepatic apoptosis [Tatsukawa et al., Gastroenterology 2009;136:1783–1795]. In this study, we investigated if a similar change might be observed also in NASH and if yes how TG2 and cross-linked Sp1 (CLSp1) would be induced in NASH and ASH. We obtained elevated nuclear TG2 and CLSp1 formation in NASH patients, as well as in HepG2 cells treated with free fatty acids (FFAs). Biochemical analyses on this culture model revealed that both ethanol and FFAs provoked fat accumulation, endoplasmic reticulum (ER) stress, increased nuclear factor-ĸB (NFĸB) and nuclear TG2, but the synergistic effect was not obvious between FFA and ethanol. Salubrinal, a selective inhibitor against dephosphorylation of eukaryotic initiation factor-2α in ER stress-induced pancreatic ER kinase (PERK) signal pathway, inhibited NFĸB activation, nuclear TG2 expression and apoptosis only induced by FFAs, but not those induced by ethanol, while retinoid antagonist blocks ethanol induction of NFĸB and TG2. These results suggest that FFA and ethanol may increase ER stress and lead to nuclear NFĸB activation and TG2 induction through respectively distinctive pathways, leading to TG2-mediated apoptosis via cross-linking and inactivation of Sp1 and reduction in c-Met.
New Advances in Cell Physiology and Pathophysiology of the Exocrine Pancreas
Authors: Mössner Joachim
Published: April 2011

This review provides some aspects on the physiology of stimulation and inhibition of pancreatic digestive enzyme secretion and the pathophysiology of pancreatic acinar cell function leading to pancreatitis. Cholecystokinin (CCK) stimulates both directly via CCK-A receptors on acinar cells and indirectly via CCK-B receptors on nerves, followed by acetylcholine release, pancreatic enzyme secretion. It is still not known whether CCK-A receptors exist in human acinar cells, in contrast to acinar cells of rodents where CCK-A receptors have been well described. CCK has numerous actions both in the periphery and in the central nervous systems. CCK inhibits gastric motility and regulates satiety. Another major function of CCK is stimulation of gallbladder contraction. This function enables that bile acids act simultaneously with pancreatic lipolytic enzymes. Secretin is a major stimulator of bicarbonate secretion. Trypsinogen is activated by the gut mucosal enzyme enterokinase. The other pancreatic proenzymes are activated by trypsin. Termination of enzyme secretion may be regulated by negative feedback mechanisms via destruction of CCK-releasing peptides by trypsin. Furthermore, the ileum may act as a brake by release of inhibitory hormones such as PYY and somatostatin. In the pathophysiology of acute pancreatitis, fusion of zymogen granules with lysosomes leading to intracellular activation of trypsinogen is regarded as an initiation step. This activation of trypsinogen may be caused by the lysosomal enzyme cathepsin B. However, autoactivation of trypsinogen itself may be a possibility in pathogenesis. Autoactivation is enhanced in certain mutations of trypsinogen. Furthermore, an imbalance of protease inhibitors and active proteases may be involved. The role of pancreatic lipolytic enzymes, the role of bicarbonate secretion, and toxic Ca2+ signals by excessive liberation from the endoplasmic reticulum have to be discussed in the pathogenesis of acute pancreatitis.
Animal Models of Alcoholic Liver Disease
Authors: Arteel Gavin E.
Published: April 2011

The risk of alcohol-induced liver disease (ALD) increases dose- and time-dependently with consumption of alcohol. The progression of the disease is well characterized; however, although the progression of alcohol-induced liver injury is well characterized, there is no universally-accepted therapy available to halt or reverse this process in humans. With better understanding of the mechanism(s) and risk factors that mediate the initiation and progression of this disease, rational targeted therapy can be developed to treat or prevent it in the clinics. Several models for experimental ALD exist, including non-human primates, micropigs and rodents. However, most researchers employ rodent models of ALD. Furthermore, the advent of genetically modified strains of rodents (e.g. ‘knockout’ mice) has increased the specificity of the hypotheses that can be directly tested. Based on these models systems, several plausible hypotheses to explain the mechanism(s) by which alcohol leads to liver damage have been proposed, including consequences of alcohol metabolism, oxidative/nitrosative stress, altered inflammatory responses, and increased sensitivity to cytotoxic stimuli. These studies have also identified candidate genes for polymorphism studies to explain potential increased genetic risk in some individuals. However, despite significant advances in our understanding of the mechanisms by which ALD develops based on studies with these models, this work has yet to translate to a viable therapy for ALD in the clinics. This talk will also discuss potential reasons for these limitations to date and suggest future prospects to improve the translational utility of modeling ALD.
Zinc and Alcoholic Liver Disease
Authors: Zhou Zhanxiang
Published: April 2011

Zinc deficiency is one of the most consistent nutritional/biochemical observations in alcoholic liver disease (ALD). The objectives of our research are to determine how alcohol interferes with cellular zinc homeostasis and if zinc deficiency is a causal factor in the development of ALD. Metallothionein (MT) is a major protein responsible for cellular zinc homeostasis. MT-transgenic (MT-TG) mice with hepatic overexpression of MT and elevation of zinc level were resistant to ethanol-induced liver injury. MT-knockout (MT-KO) mice with a reduction of hepatic zinc were more susceptible to alcohol toxicity. However, zinc treatment also provided beneficial effects on alcohol hepatoxicity in MT-KO mice, suggesting a MT-independent action. Dietary zinc supplementation normalized hepatic zinc level and attenuated the pathological changes in the liver of mice chronically fed alcohol. Several mechanisms were involved in zinc action against alcoholic cytotoxicity. Zinc enhanced cellular antioxidant capacity and corrected alcohol metabolic switch from alcohol dehydrogenase to cytochrome P4502E1. Zinc attenuated cytokine production and TNF-α receptor- and Fas-mediated cell death pathways. Zinc restored activities of hepatocyte nuclear factor-4α (HNF-4α) and peroxisome proliferation activator-α (PPAR-α), and enhanced hepatic fatty acid β-oxidation and lipid secretion. Hepatoma cell cultures showed that zinc deprivation induces lipid accumulation via inactivating HNF-4α and PPAR-α. These results suggest that alcohol exposure interferes with hepatic zinc homeostasis, leading to cellular zinc deprivation. Inactivation of zinc proteins due to zinc release is likely an important molecular mechanism in the pathogenesis of ALD.
Role of the Endocannabinoid System in Alcoholic Liver Disease
Authors: Siegmund S.V.
Published: April 2011

Alcohol abuse is a major cause of liver fibrosis and cirrhosis in developed countries. Alcoholic liver disease (ALD) is distinctively characterized by a pronounced inflammatory response due to elevated gut-derived endotoxin plasma levels, an augmented generation of oxidative stress with pericentral hepatic hypoxia and the formation of noxious ethanol metabolites (e.g. acetaldehyde or lipid oxidation products). These factors, based on a complex network of cytokine actions, together result in increased hepatocellular damage and activation of hepatic stellate cells, the key cell type of liver fibrogenesis. Recent studies suggest that the endocannabinoid system is a signaling system that also plays an important role in the pathogenesis of ALD. A study comparing chronic alcohol administration in cannabinoid receptor (CB) 1 or CB2 knockout versus wild-type mice revealed that CB1 signaling aggravated hepatic steatosis and fibrogenesis whereas CB2 protected the liver from ALD. These data suggested a protective role of CB2 (in contrast to CB1) in ALD. Similar results were found in global or hepatocyte-specific CB1 knockout mice that were resistant to ethanol-induced steatosis. Moreover, ethanol feeding upregulated the endocannabinoid 2-arachidonoyl glycerol and its biosynthetic enzyme diacylglycerol lipase-β selectively in hepatic stellate cells and subsequently increased expression of CB1 receptors in hepatocytes of wild-type mice leading to CB1-dependent hepatic steatosis by activation of lipogenic pathways. This ethanol-induced upregulation of CB1 receptors was partly dependent on the ethanol metabolite acetaldehyde. Thus, the hepatic endocannabinoid system offers emerging options for therapeutic exploitation not only for liver disease in general, but also for ALD.