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OPEN ACCESS PLUS
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Contents
19(): Pp. 1 - 8
Victor Arvanian
[Open Access Plus] |
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Synaptic transmission through descending motor pathways to lumbar motoneurons and then to leg muscles is essential for walking in humans and rats. Spinal cord injury (SCI), even when incomplete, results in diminished transmission to motoneurons and very limited recovery of motor function. Neurotrophins have emerged as essential molecules known to promote cell survival and support anatomical reorganization in damaged spinal cord. This review will summarize the evidence implicating the role of neurotrophins in synaptic plasticity in both undamaged and damaged spinal cord, with special emphasis on the potential for neurotrophins to strengthen synaptic connections to motoneurons in support of the application of neurotrophins for recovery of locomotor function after SCI. An important consideration related to therapeutic use of neurotrophins is the successful delivery of these molecules. Prolonged delivery of neurotrophins to the spinal cord of adult mammals has recently become possible through advances in biotechnology. Fibroblasts engineered to secrete neurotrophins and gene transfer of neurotrophins via recombinant viral vectors are among the most promising therapeutic transgene delivery systems for safe and effective neurotrophin delivery. Administration of neurotrophins to the spinal cord using these delivery systems was found to enhance both anatomical and synaptic plasticity and improve functional recovery after SCI. The findings summarized here indicate that neurotrophins have translational research potential for SCI repair, most likely as an essential component of combination therapy.
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19(14): Pp. 2606 - 2614
Ken Okamoto, Teruo Kusano and Takeshi Nishino
[Open Access Plus] |
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Xanthine oxidoreductase (XOR), a complex flavoprotein, catalyzes the metabolic reactions leading from hypoxanthine to xanthine and from xanthine to urate, and both reactions take place at the molybdenum cofactor. The enzyme is a target of drugs for therapy of gout or hyperuricemia. We review the chemical nature and reaction mechanisms of the molybdenum cofactor of XOR, focusing on molybdenum-dependent reactions of actual or potential medical importance, including nitric oxide (NO) synthesis. It is now generally accepted that XOR transfers the water-exchangeable -OH ligand of the molybdenum atom to the substrate. The hydroxyl group at OHMo( IV) can be replaced by urate, oxipurinol and FYX-051 derivatives and the structures of these complexes have been determined by xray crystallography under anaerobic conditions. Although formation of NO from nitrite or formation of xanthine from urate by XOR is chemically feasible, it is not yet clear whether these reactions have any physiological significance since the reactions are catalyzed at a slow rate even under anaerobic conditions.
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19(14): Pp. 2561 - 2573
Karina Kizjakina, John J. Tanner and Pablo Sobrado
[Open Access Plus] |
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UDP-Galactopyranose mutase (UGM) is a unique flavin-dependent enzyme that catalyzes the conversion of UDPgalactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf). The product of this reaction is the precursor to Galf, a major component of the cell wall and of cell surface glycoproteins and glycolipids in many eukaryotic and prokaryotic human pathogens. The function of UGM is important in the virulence of fungi, parasites, and bacteria. Its role in virulence and its absence in humans suggest that UGM is an ideal drug target. Significant structural and mechanistic information has been accumulated on the prokaryotic UGMs; however, in the past few years the research interest has shifted to UGMs from eukaryotic human pathogens such as fungi and protozoan parasites. It has become clear that UGMs from prokaryotic and eukaryotic organisms have different structural and mechanistic features. The amino acid sequence identity between these two classes of enzymes is low, resulting in differences in oligomeric states, substrate binding, active site flexibility, and interaction with redox partners. However, the unique role of the flavin cofactor in catalysis is conserved among this enzyme family. In this review, recent findings on eukaryotic UGMs are discussed and presented in comparison with prokaryotic UGMs.
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19(13): Pp. 2432 - 2438
Davide Grassi, Livia Ferri, Giovambattista Desideri, Paolo Di Giosia, Paola Cheli, Rita Del Pinto, Giuliana Properzi and Claudio Ferri
[Open Access Plus] |
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Hyperuricemia is commonly associated with traditional risk factors such as dysglicemia, dyslipidemia, central obesity and abnormal blood pressure, i.e. the metabolic syndrome. Concordantly, recent studies have revived the controversy over the role of circulating uric acid, hyperuricemia, and gout as an independent prognostic factor for cardiovascular morbidity and mortality. In this regard, different studies also evaluated the possible role of xanthine inhibitors in inducing blood pressure reduction, increment in flow-mediated dilation, and improved cardiovascular prognosis in various patient settings. The vast majority of these studies have been conducted with either allopurinol or its active metabolite oxypurinol, i.e. two purine-like non-selective inhibitors of xanthine oxidase. More recently, the role of uric acid as a risk factor for cardiovascular disease and the possible protective role exerted by reduction of hyperuricemia to normal level have been evaluated by the use of febuxostat, a selective, non purine-like xanthine oxidase inhibitor. In this review, we will report current evidence on hyperuricemia in cardiovascular disease. The value of uric acid as a biomarker and as a potential therapeutic target for tailored old and novel “cardiometabolic” treatments will be also discussed.
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19(4): Pp. 634 - 664
Andrey Voronkov and Stefan Krauss
[Open Access Plus] |
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Wnt/β-catenin signaling is a branch of a functional network that dates back to the first metazoans and it is involved in a broad range of biological systems including stem cells, embryonic development and adult organs. Deregulation of components involved in Wnt/β-catenin signaling has been implicated in a wide spectrum of diseases including a number of cancers and degenerative diseases. The key mediator of Wnt signaling, β-catenin, serves several cellular functions. It functions in a dynamic mode at multiple cellular locations, including the plasma membrane, where β-catenin contributes to the stabilization of intercellular adhesive complexes, the cytoplasm where β-catenin levels are regulated and the nucleus where β-catenin is involved in transcriptional regulation and chromatin interactions. Central effectors of β-catenin levels are a family of cysteine-rich secreted glycoproteins, known as Wnt morphogens. Through the LRP5/6-Frizzled receptor complex, Wnts regulate the location and activity of the destruction complex and consequently intracellular β- catenin levels. However, β-catenin levels and their effects on transcriptional programs are also influenced by multiple other factors including hypoxia, inflammation, hepatocyte growth factor-mediated signaling, and the cell adhesion molecule E-cadherin. The broad implications of Wnt/β-catenin signaling in development, in the adult body and in disease render the pathway a prime target for pharmacological research and development. The intricate regulation of β-catenin at its various locations provides alternative points for therapeutic interventions.
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19(4): Pp. 614 - 623
Santina Bruzzone, Marco Daniele Parenti, Alessia Grozio, Alberto Ballestrero, Inga Bauer, Alberto Del Rio and Alessio Nencioni
[Open Access Plus] |
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Sirtuins are a family of NAD+-dependent enzymes that was proposed to control organismal life span about a decade ago. While such role of sirtuins is now debated, mounting evidence involves these enzymes in numerous physiological processes and disease conditions, including metabolism, nutritional behavior, circadian rhythm, but also inflammation and cancer. SIRT1, SIRT2, SIRT3, SIRT6, and SIRT7 have all been linked to carcinogenesis either as tumor suppressor or as cancer promoting proteins. Here, we review the biological rationale for the search of sirtuin inhibitors and activators for treating cancer and the experimental approaches to their identification.
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19(4): Pp. 578 - 613
Federico Andreoli, Armenio Jorge Moura Barbosa, Marco Daniele Parenti and Alberto Del Rio
[Open Access Plus] |
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Research on cancer epigenetics has flourished in the last decade. Nevertheless growing evidence point on the importance to understand the mechanisms by which epigenetic changes regulate the genesis and progression of cancer growth. Several epigenetic targets have been discovered and are currently under validation for new anticancer therapies. Drug discovery approaches aiming to target these epigenetic enzymes with small-molecules inhibitors have produced the first pre-clinical and clinical outcomes and many other compounds are now entering the pipeline as new candidate epidrugs. The most studied targets can be ascribed to histone deacetylases and DNA methyltransferases, although several other classes of enzymes are able to operate post-translational modifications to histone tails are also likely to represent new frontiers for therapeutic interventions. By acknowledging that the field of cancer epigenetics is evolving with an impressive rate of new findings, with this review we aim to provide a current overview of pre-clinical applications of smallmolecules for cancer pathologies, combining them with the current knowledge of epigenetic targets in terms of available structural data and drug design perspectives.
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19(3): Pp. 430 - 440
Kata Juhasz, Roland Thuenauer, Andrea Spachinger, Ern Duda, Ibolya Horvath, Laszlo Vigh, Alois Sonnleitner and Zsolt Balogi
[Open Access Plus] |
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Tumor specific cell surface localization and release of the stress inducible heat shock protein 70 (Hsp70) stimulate the immune system against cancer cells. A key immune stimulatory function of tumor-derived Hsp70 has been exemplified with the murine melanoma cell model, B16 overexpressing exogenous Hsp70. Despite the therapeutic potential mechanism of Hsp70 transport to the surface and release remained poorly understood. We investigated principles of Hsp70 trafficking in B16 melanoma cells with low and high level of Hsp70. In cells with low level of Hsp70 apparent trafficking of Hsp70 was mediated by endosomes. Excess Hsp70 triggered a series of changes such as a switch of Hsp70 trafficking from endosomes to lysosomes and a concomitant accumulation of Hsp70 in lysosomes. Moreover, lysosomal rerouting resulted in an elevated concentration of surface Hsp70 and enabled active release of Hsp70. In fact, hyperthermia, a clinically applicable approach triggered immediate active lysosomal release of soluble Hsp70 from cells with excess Hsp70. Furthermore, excess Hsp70 enabled targeting of internalized surface Hsp70 to lysosomes, allowing in turn heat-induced secretion of surface Hsp70. Altogether, we show that excess Hsp70 expressed in B16 melanoma cells diverts Hsp70 trafficking from endosomes to lysosomes, thereby supporting its surface localization and lysosomal release. Controlled excess-induced lysosomal rerouting and secretion of Hsp70 is proposed as a promising tool to stimulate anti-tumor immunity targeting melanoma.
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18(32): Pp. 5070 - 5080
Charlotte Rapp, Hilal Bugra, Anita Riecher-Rossler, Corinne Tamagni and Stefan Borgwardt
[Open Access Plus] |
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It is unclear yet whether cannabis use is a moderating or causal factor contributing to grey matter alterations in schizophrenia and the development of psychotic symptoms. We therefore systematically reviewed structural brain imaging and post mortem studies addressing the effects of cannabis use on brain structure in psychosis. Studies with schizophrenia (SCZ) and first episode psychosis (FEP) patients as well as individuals at genetic (GHR) or clinical high risk for psychosis (ARMS) were included. We identified 15 structural magnetic resonance imaging (MRI) (12 cross sectional / 3 longitudinal) and 4 post mortem studies. The total number of subjects encompassed 601 schizophrenia or first episode psychosis patients, 255 individuals at clinical or genetic high risk for psychosis and 397 healthy controls. We found evidence for consistent brain structural abnormalities in cannabinoid 1 (CB1) receptor enhanced brain areas as the cingulate and prefrontal cortices and the cerebellum. As these effects have not consistently been reported in studies examining nonpsychotic and healthy samples, psychosis patients and subjects at risk for psychosis might be particularly vulnerable to brain volume loss due to cannabis exposure.
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18(24): Pp. 3480 - 3489
Janet Storm and Sylke Muller
[Open Access Plus] |
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α-Lipoic acid (6,8-thioctic acid; LA) is a vital co-factor of α-ketoacid dehydrogenase complexes and the glycine cleavage system. In recent years it was shown that biosynthesis and salvage of LA in Plasmodium are necessary for the parasites to complete their complex life cycle. LA salvage requires two lipoic acid protein ligases (LplA1 and LplA2). LplA1 is confined to the mitochondrion while LplA2 is located in both the mitochondrion and the apicoplast. LplA1 exclusively uses salvaged LA and lipoylates α-ketoglutarate dehydrogenase, branched chain α-ketoacid dehydrogenase and the H-protein of the glycine cleavage system. LplA2 cannot compensate for the loss of LplA1 function during blood stage development suggesting a specific function for LplA2 that has yet to be elucidated. LA salvage is essential for the intra-erythrocytic and liver stage development of Plasmodium and thus offers great potential for future drug or vaccine development. LA biosynthesis, comprising octanoyl-acyl carrier protein (ACP) : protein N-octanoyltransferase (LipB) and lipoate synthase (LipA), is exclusively found in the apicoplast of Plasmodium where it generates LA de novo from octanoyl-ACP, provided by the type II fatty acid biosynthesis (FAS II) pathway also present in the organelle. LA is the co-factor of the acetyltransferase subunit of the apicoplast located pyruvate dehydrogenase (PDH), which generates acetyl-CoA, feeding into FAS II. LA biosynthesis is not vital for intra-erythrocytic development of Plasmodium, but the deletion of several genes encoding components of FAS II or PDH was detrimental for liver stage development of the parasites indirectly suggesting that the same applies to LA biosynthesis. These data provide strong evidence that LA salvage and biosynthesis are vital for different stages of Plasmodium development and offer potential for drug and vaccine design against malaria.
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18(24): Pp. 3454 - 3466
Suzanne Peyrottes, Sergio Caldarelli, Sharon Wein, Christian Perigaud, Alain Pellet and Henri Vial
[Open Access Plus] |
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Emerging resistance against well-established anti-malaria drugs warrants the introduction of new therapeutic agents with original mechanisms of action. Inhibition of membrane-based phospholipid biosynthesis, which is crucial for the parasite, has thus been proposed as a novel and promising therapeutic strategy. This review compiles literature concerning the design and study of choline analogues and related cation derivatives as potential anti-malarials. It covers advances achieved over the last two decades and describes: the concept validation, the design and selection of a clinical candidate (Albitiazolium), back-up derivatives while also providing insight into the development of prodrug approaches.
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18(20): Pp. 2883 - 2890
Vladimir Krystof, Sonja Baumli and Robert Furst
[Open Access Plus] |
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Deregulation of cyclin-dependent kinases (CDKs) has been associated with many cancer types and has evoked an interest in chemical inhibitors with possible therapeutic benefit. While most known inhibitors display broad selectivity towards multiple CDKs, recent work highlights CDK9 as the critical target responsible for the anticancer activity of clinically evaluated drugs. In this review, we discuss recent findings provided by structural biologists that may allow further development of highly specific inhibitors of CDK9 towards applications in cancer therapy. We also highlight the role of CDK9 in inflammatory processes and diseases.
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18(13): Pp. 1755 - 1783
Ilaria Decimo, Francesco Bifari, Mauro Krampera and Guido Fumagalli
[Open Access Plus] |
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Presence of neural stem cells in adult mammalian brains, including human, has been clearly demonstrated by several studies. The functional significance of adult neurogenesis is slowly emerging as new data indicate the sensitivity of this event to several “every day” external stimuli such as physical activity, learning, enriched environment, aging, stress and drugs. In addition, neurogenesis appears to be instrumental for task performance involving complex cognitive functions. Despite the growing body of evidence on the functional significance of NSC and despite the bulk of data concerning the molecular and cellular properties of NSCs and their niches, several critical questions are still open. In this work we review the literature describing i) old and new sites where NSC niche have been found in the CNS; ii) the intrinsic factors regulating the NSC potential; iii) the extrinsic factors that form the niche microenvironment. Moreover, we analyse NSC niche activation in iv) physiological and v) pathological conditions. Given the not static nature of NSCs that continuously change phenotype in response to environmental clues, a unique “identity card” for NSC identification is still lacking. Moreover, the multiple location of NSC niches that increase in diseases, leaves open the question of whether and how these structures communicate throughout long distance. We propose a model where all the NSC niches in the CNS may be connected in a functional network using the threads of the meningeal net as tracks.
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18(11): Pp. 1519 - 1530
Alexios S. Antonopoulos, Marios Margaritis, Regent Lee, Keith Channon and Charalambos Antoniades
[Open Access Plus] |
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Ample evidence exists in support of the potent anti-inflammatory properties of statins. In cell studies and animal models statins exert beneficial cardiovascular effects. By inhibiting intracellular isoprenoids formation, statins suppress vascular and myocardial inflammation, favorably modulate vascular and myocardial redox state and improve nitric oxide bioavailability. Randomized clinical trials have demonstrated that further to their lipid lowering effects, statins are useful in the primary and secondary prevention of coronary heart disease (CHD) due to their anti-inflammatory potential. The landmark JUPITER trial suggested that in subjects without CHD, suppression of low-grade inflammation by statins improves clinical outcome. However, recent trials have failed to document any clinical benefit with statins in high risk groups, such in heart failure or chronic kidney disease patients. In this review, we aim to summarize the existing evidence on statins as an anti-inflammatory agent in atherogenesis. We describe the molecular mechanisms responsible for the antiinflammatory effects of statins, as well as clinical data on the non lipid-lowering, anti-inflammatory effects of statins on cardiovascular outcomes. Lastly, the controversy of the recent large randomized clinical trials and the issue of statin withdrawal are also discussed.
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18(10): Pp. 1434 - 1445
Dominique Charmot
[Open Access Plus] |
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Non-systemic drugs act within the intestinal lumen without reaching the systemic circulation. The first generation included polymeric resins that sequester phosphate ions, potassium ions, or bile acids for the treatment of electrolyte imbalances or hypercholesteremia. The field has evolved towards non-absorbable small molecules or peptides targeting luminal enzymes or transporters for the treatment of mineral metabolism disorders, diabetes, gastrointestinal (GI) disorders, and enteric infections. From a drug design and development perspective, non-systemic agents offer novel opportunities to address unmet medical needs while minimizing toxicity risks, but also present new challenges, including developing a better understanding and control of non-transcellular leakage pathways into the systemic circulation. The pharmacokinetic-pharmacodynamic relationship of drugs acting in the GI tract can be complex due to the variability of intestinal transit, interaction with chyme, and the complex environment of the surface epithelia. We review the main classes of nonabsorbable agents at various stages of development, and their therapeutic potential and limitations. The rapid progress in the identification of intestinal receptors and transporters, their functional characterization and role in metabolic and inflammatory disorders, will undoubtedly renew interest in the development of novel, safe, non-systemic therapeutics.
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18(10): Pp. 1319 - 1330
Suveera Dhup, Rajesh Kumar Dadhich, Paolo Ettore Porporato and Pierre Sonveaux
[Open Access Plus] |
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High rate of glycolysis is a metabolic hallmark of cancer. While anaerobic glycolysis promotes energy production under hypoxia, aerobic glycolysis, the Warburg effect, offers a proliferative advantage through redirecting carbohydrate fluxes from energy production to biosynthetic pathways. To fulfill tumor cell needs, the glycolytic switch is associated with elevated glucose uptake and lactic acid release. Altered glucose metabolism is the basis of positron emission tomography using the glucose analogue tracer [18F]- fluorodeoxyglucose, a widely used clinical application for tumor diagnosis and monitoring. On the other hand, high levels of lactate have been associated with poor clinical outcome in several types of human cancers. Although lactic acid was initially considered merely as an indicator of the glycolytic flux, many evidences originally from the study of normal tissue physiology and more recently transposed to the tumor situation indicate that lactic acid, i.e. the lactate anion and protons, directly contributes to tumor growth and progression. Here, we briefly review the current knowledge pertaining to lactic acidosis and metastasis, lactate shuttles, the influence of lactate on redox homeostasis, lactate signaling and lactate-induced angiogenesis in the cancer context. The monocarboxylate transporters MCT1 and MCT4 have now been confirmed as prominent facilitators of lactate exchanges between cancer cells with different metabolic behaviors and between cancer and stromal cells. We therefore address the function and regulation of MCTs, highlighting MCT1 as a novel anticancer target. MCT1 inhibition allows to simultaneously disrupt metabolic cooperativity and angiogenesis in cancer with a same agent, opening a new path for novel anticancer therapies.
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18(8): Pp. 1108 - 1122
Pedro Fernandez-Funez
[Open Access Plus] |
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Alzheimer's, Parkinson's, and Huntington's disease are complex neurodegenerative conditions with high prevalence character-ized by protein misfolding and deposition in the brain. Considerable progress has been made in the last two decades in identifying the genes and proteins responsible for several human ‘proteinopathies’. A wide variety of wild type and mutant proteins associated with neu-rodegenerative conditions are structurally unstable, misfolded, and acquire conformations rich in ß-sheets (ß-state). These conformers form highly toxic self-assemblies that kill the neurons in stereotypical patterns. Unfortunately, the detailed understanding of the molecu-lar and cellular perturbations caused by these proteins has not produced a single disease-modifying therapy. More than a decade ago, sev-eral groups demonstrated that human proteinopathies reproduce critical features of the disease in transgenic flies, including protein mis-folding, aggregation, and neurotoxicity. These in itial reports led to an explosion of research that has contributed to a better understanding of the molecular mechanisms regulating conformational dynamics and neurotoxic cascades. To remain relevant in this competitive envi-ronment, Drosophila models will need to expand their flexible, innovative, and multidisciplinary approaches to find new discoveries and translational applications.
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18(6): Pp. 755 - 767
Susanne Aileen Funke and Dieter Willbold
[Open Access Plus] |
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Alzheimer's disease (AD) is a progressive neurodegenerative disorder with devastating effects. The greatest risk factor to develop AD is age. Today, only symptomatic therapies are available. Additionally, AD can be diagnosed with certainty only post mortem, whereas the diagnosis “probable AD” can be established earliest when severe clinical symptoms appear. Specific neuropathological changes like neurofibrillary tangles and amyloid plaques define AD. Amyloid plaques are mainly composed of the amyloid-βpeptide (Aβ). Several lines of evidence suggest that the progressive concentration and subsequent aggregation and accumulation of Aβplay a fundamental role in the disease progress. Therefore, substances which bind to Aβ and influence aggregation thereof are of great interest. An enormous number of organic substances for therapeutic purposes are described. This review focuses on peptides developed for diagnosis and therapy of AD and discusses the pre- and disadvantages of peptide drugs.
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17(35): Pp. 3846 - 3853
Tomohisa Nagoshi, Michihiro Yoshimura, Giuseppe M. C. Rosano, Gary D. Lopaschuk and Seibu Mochizuki
[Open Access Plus] |
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The derangement of the cardiac energy substrate metabolism plays a key role in the pathogenesis of heart failure. The utilization of non-carbohydrate substrates, such as fatty acids, is the predominant metabolic pathway in the normal heart, because this provides the highest energy yield per molecule of substrate metabolized. In contrast, glucose becomes an important preferential substrate for metabolism and ATP generation under specific pathological conditions, because it can provide greater efficiency in producing high energy products per oxygen consumed compared to fatty acids. Manipulations that shift energy substrate utilization away from fatty acids toward glucose can improve the cardiac function and slow the progression of heart failure. However, insulin resistance, which is highly prevalent in the heart failure population, impedes this adaptive metabolic shift. Therefore, the acceleration of the glucose metabolism, along with the restoration of insulin sensitivity, would be the ideal metabolic therapy for heart failure. This review discusses the therapeutic potential of modifying substrate utilization to optimize cardiac metabolism in heart failure.
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17(30): Pp. 3258 - 3270
Lieven Thorrez and Maurilio Sampaolesi
[Open Access Plus] |
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The field of stem cell research was revolutionized with the advent of induced pluripotent stem cells. By reprogramming somatic cells to pluripotent stem cells, most ethical concerns associated with the use of embryonic stem cells are overcome, such that many hopes from the stem cell field now seem a step closer to reality. Several methods and cell sources have been described to create induced pluripotent stem cells and we discuss their characteristics in terms of feasibility and efficiency. From these cells, cardiac progenitors and cardiomyocytes can be derived by several protocols and most recent advances as well as remaining limitations are being discussed. However, in the short time period this technology has been around, evidence emerges that induced pluripotent stem cells may be more prone to genetic defects and maintain an epigenetic memory and thus may not be entirely the same as embryonic stem cells. Despite the lack of a complete fundamental understanding of stem cell biology, and even more of ways how to coax them into defined cell types, the technology is quickly adopted by industry. This paper gives an overview of the current applications of induced pluripotent stem cells in cardiovascular drug development and highlights active areas of research towards functional repair of the damaged heart. Adult stem cells have already been taken to clinical trials and we discuss these results in light of potential and hurdles to be taken to move induced pluripotent stem cells to the clinic.
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17(24): Pp. 2528 - 2541
Tristan R. McKay, Ahad A. Rahim, Suzanne M.K. Buckley, Natalie J. Ward, Jerry K.Y.Chan, Steven J. Howe and Simon N. Waddington
[Open Access Plus] |
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The liver acts as a host to many functions hence raising the possibility that any one may be compromised by a single gene defect. Inherited or de novo mutations in these genes may result in relatively mild diseases or be so devastating that death within the first weeks or months of life is inevitable. Some diseases can be managed using conventional medicines whereas others are, as yet, untreatable. In this review we consider the application of early intervention gene therapy in neonatal and fetal preclinical studies. We appraise the tools of this technology, including lentivirus, adenovirus and adeno-associated virus (AAV)-based vectors. We highlight the application of these for a range of diseases including hemophilia, urea cycle disorders such as ornithine transcarbamylase deficiency, organic acidemias, lysosomal storage diseases including mucopolysaccharidoses, glycogen storage diseases and bile metabolism. We conclude by assessing the advantages and disadvantages associated with fetal and neonatal liver gene transfer.
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17(22): Pp. 2241 - 2252
Shigeo Ohta
[Open Access Plus] |
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Persistent oxidative stress is one of the major causes of most lifestyle-related diseases, cancer and the aging process. Acute oxidative stress directly causes serious damage to tissues. Despite the clinical importance of oxidative damage, antioxidants have been of limited therapeutic success. We have proposed that molecular hydrogen (H2) has potential as a “novel” antioxidant in preventive and therapeutic applications [Ohsawa et al., Nat Med. 2007: 13; 688-94]. H2 has a number of advantages as a potential antioxidant: H2 rapidly diffuses into tissues and cells, and it is mild enough neither to disturb metabolic redox reactions nor to affect reactive oxygen species (ROS) that function in cell signaling, thereby, there should be little adverse effects of consuming H2. There are several methods to ingest or consume H2, including inhaling hydrogen gas, drinking H2-dissolved water (hydrogen water), taking a hydrogen bath, injecting H2- dissolved saline (hydrogen saline), dropping hydrogen saline onto the eye, and increasing the production of intestinal H2 by bacteria. Since the publication of the first H2 paper in Nature Medicine in 2007, the biological effects of H2 have been confirmed by the publication of more than 38 diseases, physiological states and clinical tests in leading biological/medical journals, and several groups have started clinical examinations. Moreover, H2 shows not only effects against oxidative stress, but also various anti-inflammatory and antiallergic effects. H2 regulates various gene expressions and protein-phosphorylations, though the molecular mechanisms underlying the marked effects of very small amounts of H2 remain elusive.
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17(17): Pp. 1672 - 1684
Yukiko Kamiya, Maho Yagi-Utsumi, Hirokazu Yagi and Koichi Kato
[Open Access Plus] |
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The sugar chains covalently modifying proteins and lipids are recognized by a variety of proteins, thereby mediating a broad range of physiological and pathological events on cell surfaces as well as in cells. Hence, these carbohydrate – protein interaction systems could be potential therapeutic targets for various diseases, including viral infections, autoimmune diseases and neurodegenerative disorders. Cumulative crystallographic data of lectins complexed with their cognate carbohydrate ligands have elucidated the sugar recognition modes of these proteins, offering a structural basis for the design of drugs targeting carbohydrate – lectin interaction systems. In particular, structural and functional studies of animal L-type lectins, which possess a carbohydrate recognition domain with a structural resemblance to that of leguminous lectins such as concanavalin A, have demonstrated the molecular mechanisms underlying their distinct roles in sorting and trafficking of glycoproteins in cells, exemplifying the structure-based engineering that manipulates the sugar-binding properties of lectins. Furthermore, structural basis has been provided for the functional interplay between the L-type lectin ERGIC-53 and the EF-hand Ca2+-binding protein MCFD2 in the intracellular transport of the coagulation factors V and VIII. This article also deals with pathological carbohydrate – protein interactions involving ganglioside clusters on cell surfaces, particularly focusing on the interaction between amyloid β (Aβ) and GM1 ganglioside. This interaction triggers conformational transition and consequent aggregation of Aβ, and therefore, is considered to be a key step in Alzheimer's disease. The recently reported structural information of the Aβ – GM1 interaction is presented, underscoring the significance of assemblages of glycoconjugates as therapeutic targets.
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17(10): Pp. 985 - 989
Hitoshi Hashimoto, Norihito Shintani, Mamoru Tanida, Atsuko Hayata, Ryota Hashimoto and Akemichi Baba
[Open Access Plus] |
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Pituitary adenylate cyclase-activating polypeptide (PACAP) is a highly conserved pleiotropic neuropeptide that functions as a neurotransmitter, neuromodulator and neurotrophic factor. Accumulating evidence implicates PACAP as an important regulator of both central and/or peripheral components of the stress axes, particularly exposure to prolonged or traumatic stress. Indeed, PACAP and its cognate receptors are widely expressed in the brain regions and peripheral tissues that mediate stress-related responses. In the sympathoadrenomedullary system, PACAP is required for sustained epinephrine secretion during metabolic stress. It is likely that PACAP regulates autonomic function and contributes to peripheral homeostasis by maintaining a balance between sympathetic and parasympathetic activity, favoring stimulation of the sympathetic system. Furthermore, PACAP is thought to act centrally on the paraventricular nucleus of the hypothalamus to regulate both the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Intriguingly, PACAP is also active in brain structures that mediate anxiety- and fear-related behaviors, and the expression of PACAP and its receptors are dynamically altered under pathologic conditions. Thus PACAP may influence both hard-wired (genetically determined) stress responses and gene-environment interactions in stress-related psychopathology. This article aims to overview the molecular mechanisms and psychiatric implications of PACAP-dependent stress responses.
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17(6): Pp. 578 - 590
Andrea Bisso, Licio Collavin and Giannino Del Sal
[Open Access Plus] |
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About half of all human tumors contain an inactivating mutation of p53, while in the remaining tumors, the p53 pathway is frequently abrogated by alterations of other components of its signaling pathway. In humans, the p53 tumor suppressor is part of a small gene family that includes two other members, p73 and p63, structurally and functionally related to p53. Accumulating evidences indicate that all p53-family proteins function as molecular hubs of a highly interconnected signaling network that coordinates cell proliferation, differentiation and death in response to physiological inputs and oncogenic stress. Therefore, not only the p53-pathway but the entire “p53-family pathway” is a primary target for cancer drug development. In particular, the p53-related protein p73 has a crucial role in determining cellular responses to chemotherapy, and can vicariate p53 functions in triggering cell death after DNA damage in multiple experimental models. The biology and regulation of p73 is complex, since the TP73 gene incorporates both tumor-suppressive and protooncogenic functions. However, the p73 gene is rarely mutated in tumors, so appropriate pharmacological manipulation of the p73 pathway is a very promising approach for cancer therapy. Here we provide an overview of the principal mechanism of p73 regulation, and describe several examples of pharmacological tools that can induce p73 accumulation and function by acting on upstream p73 modulators or displacing inhibitory p73 interactors. A better understanding of how the p73 pathway works is mandatory to discover additional players intervening in this pathway and has important implications for the improvement of cancer treatment with the development of new molecules or with the reposition of currently available drugs.
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17(5): Pp. 410 - 423
Takashi Muramatsu
[Open Access Plus] |
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Midkine (MK) is a heparin-binding cytokine, and promotes growth, survival, migration and other activities of target cells. After describing the general properties of MK, this review focuses on MK and MK inhibitors as therapeutics for diseases in the central nervous system. MK is strongly expressed during embryogenesis especially at the midgestation period, but is expressed only at restricted sites in adults. MK expression is induced upon tissue injury such as ischemic brain damage. Since exogenously administered MK or the gene transfer of MK suppresses neuronal cell death in experimental systems, MK has the potential to treat cerebral infarction. MK might become important also in the treatment of neurodegenerative diseases such as Alzheimers disease. MK is involved in inflammatory diseases by enhancing migration of leukocytes, inducing chemokine production and suppressing regulatory T cells. Since an aptamer to MK suppresses experimental autoimmune encephalitis, MK inhibitors are promising for the treatment of multiple sclerosis. MK is overexpressed in most malignant tumors including glioblastoma, and is involved in tumor invasion. MK inhibitors may be of value in the treatment of glioblastoma. Furthermore, an oncolytic adenovirus, whose replication is under the control of the MK promoter, inhibits the growth of glioblastoma xenografts. MK inhibitors under development include antibodies, aptamers, glycosaminoglycans, peptides and low molecular weight compounds. siRNA and antisense oligoDNA have proved effective against malignant tumors and inflammatory diseases in experimental systems. Practical information concerning the development of MK and MK inhibitors as therapeutics is described in the final part of the review.
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16(28): Pp. 3071 - 3088
Christian W. Gruber, Markus Muttenthaler and Michael Freissmuth
[Open Access Plus] |
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G protein-coupled receptors (GPCRs) are considered to represent the most promising drug targets; it has been repeatedly said that a large fraction of the currently marketed drugs elicit their actions by binding to GPCRs (with cited numbers varying from 30-50%). Closer scrutiny, however, shows that only a modest fraction of (∼60) GPCRs are, in fact, exploited as drug targets, only ∼20 of which are peptide-binding receptors. The vast majority of receptors in the humane genome have not yet been explored as sites of action for drugs. Given the drugability of this receptor class, it appears that opportunities for drug discovery abound. In addition, GPCRs provide for binding sites other than the ligand binding sites (referred to as the “orthosteric site”). These additional sites include (i) binding sites for ligands (referred to as “allosteric ligands”) that modulate the affinity and efficacy of orthosteric ligands, (ii) the interaction surface that recruits G proteins and arrestins, (iii) the interaction sites of additional proteins (GIPs, GPCR interacting proteins that regulate G protein signaling or give rise to G protein-independent signals). These sites can also be targeted by peptides. Combinatorial and natural peptide libraries are therefore likely to play a major role in identifying new GPCR ligands at each of these sites. In particular the diverse natural peptide libraries such as the venom peptides from marine cone-snails and plant cyclotides have been established as a rich source of drug leads. High-throughput screening and combinatorial chemistry approaches allow for progressing from these starting points to potential drug candidates. This will be illustrated by focusing on the ligand-based drug design of oxytocin (OT) and vasopressin (AVP) receptor ligands using natural peptide leads as starting points.
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16(14): Pp. 1582 - 1594
L. Leoni and B.B. Roman
[Open Access Plus] |
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The increasing global incidence of diabetes and advancements in clinical pancreatic islet transplantation for the treatment of Type I diabetes have renewed the interest in understanding the variations of β-cell mass and function relative not only to transplant outcome but also to the onset and progression of diabetes. A deeper comprehension of the molecular and cellular processes involved in pancreatic islet inflammation and cytotoxicity is necessary to further improve efficacy of islet transplantation and to develop new therapies aimed at preserving beta cell function in pathological conditions. Available diagnostic methods based on metabolic response are unsuitable as they lack correlation to islet mass, viability and function. Great emphasis has been placed on developing noninvasive imaging technologies which enable the tracking of both endogenous and transplanted islet mass and potentially function overtime, the characterization of changes in islet vasculature and the degree of T-cell infiltration during insulitis. Among the more relevant modalities are magnetic resonance, positron emitted tomography, single photon emission computed tomography, bioluminescence and fluorescence optical imaging. This review focuses on the most recent advancements in magnetic resonance imaging (MRI) of pancreatic islets. In-vitro approaches aimed at characterizing the potency of isolated islets as well as in-vivo advancements in the assessment of transplanted beta cell mass are presented together with the significant progress made in the in-vivo imaging of the endocrine pancreas and islet vasculature and inflammation. Different experimental approaches are compared via their advantages and limitations with respect to their clinical implementation.
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16(14): Pp. 1568 - 1581
Rajakrishnan Veluthakal and Paul Harris
[Open Access Plus] |
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In diabetic disease, blood glucose, HbA1c and insulin levels qualify as biomarkers reflecting endocrine pancreas function, but their shortfall in being truly useful predictors or surrogate endpoints of “abnormal processes or disease“ lies in that alteration in their levels are dependent on a variety comorbidities and occur too late in the disease process to be useful sentinels. Non invasive imaging of molecular targets within the beta cell carry the promise of revealing quantitative information about β-cell mass that can, at least theoretically, be used to monitor, in real-time, the natural history of T1DM progression, assess novel therapies designed to drive the proliferation and differentiation of endogenous beta cell progenitors, appraise methods of preserving mature beta cell mass as well as to track the function and viability of transplanted cells and tissues. In this article, we review and deconstruct available information regarding the methodology of making non invasive measurements of VMAT2 in the pancreas and the validity of these measurements to estimate beta cell mass in vivo.
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16(14): Pp. 1561 - 1567
Maarten Brom, Karolina Andraojc, Wim J.G. Oyen, Otto C. Boerman and Martin Gotthardt
[Open Access Plus] |
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The changes in beta-cell mass (BCM) during the course of diabetes are not yet well characterized. A non-invasive method to measure the BCM in vivo would allow us to study the BCM during the onset and progression of the diseases caused by beta-cell dysfunction. PET and SPECT imaging are attractive approaches to determine the BCM because of their high sensitivity and the possibility to quantitatively analyze the images. Several targets and their corresponding radiotracers have been examined for their ability to determine the BCM including radiolabeled antibodies, antibody fragments, peptides and small molecules. Although some of these tracers show promising results, there is still no reliable method to determine the beta-cell mass in vivo. In this review, the targets and the corresponding radiotracers evaluated so far for the determination of the BCM in vivo in humans will be discussed.
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16(14): Pp. 1550 - 1560
S. Kauhanen, M. Seppanen, H. Minn and P. Nuutila
[Open Access Plus] |
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Persistent hyperinsulinemic hypoglycemia (PHH) is caused by solitary benign insulinoma or hyperplasia of pancreatic beta cells. In infants, PHH is caused by functionally defective hyperplastic beta cells, which are either diffusely or focally distributed in the pancreas. In adults, insulinoma is the most common cause of PHH, but recently, an increasing number of beta-cell hyperplasias has been reported among adults. The cause of adult beta-cell hyperplasia is not known. Whether the increased use of bariatric surgery in the treatment of severe obesity plays a role here is under investigation. Accurate localization of disease focus in both insulinoma and focal beta-cell hyperplasia provides an important support for surgery, especially as the use of laparoscopic surgery has increased. Conventional imaging of these challenging pancreatic lesions has evolved during recent years, but current imaging methods still lack sufficient sensitivity or are invasive. In most pancreatic neuroendocrine tumors (NETs), the usefulness of positron emission tomography (PET) with fluorine-labeled fluorodeoxyglucose ([18F]FDG) for lesion detection is limited because of the low glucose turnover of these tumors. Based on the capacity of pancreatic beta cells to take up and decarboxylate amine precursors, several investigators have studied patients with pancreatic NETs using aminoacid precursors, such as [18F]dihydroxyphenylalanine (DOPA) and [11C]hydroxytryptophan (5-HTP), in an attempt to increase the sensitivity of PET scanning. Another characteristic of NETs is the expression of somatostatin receptors, and thus encouraging studies with somatostatin receptor imaging with [18Ga]-labeled somatostatin analogs have emerged as a new interesting imaging tool for the diagnosis of pancreatic NETs. This article provides an overview of our experiences and the current literature on PET imaging in patients with PHH caused by insulinoma or beta-cell hyperplasia.
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16(8): Pp. 906 - 914
Stefano Ciciliot and Stefano Schiaffino
[Open Access Plus] |
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Mammalian skeletal muscles can regenerate following injury and this response is mediated by a specific type of stem cell, the satellite cell. We review here the three main phases of muscle regeneration, including i) the initial inflammatory response and the dual role of macrophages as both scavengers involved in the phagocytosis of necrotic debris and promoters of myogenic differentiation, ii) the activation and differentiation of satellite cells and iii) the growth and remodeling of the regenerated muscle tissue. Nerve activity is required to support the growth of regenerated myofibers and the specification of muscle fiber types, in particular the activation of the slow gene program. We discuss the regeneration process in two different settings. Chronic degenerative diseases, such as muscular dystrophies, are characterized by repeated cycles of segmental necrosis and regeneration involving scattered myofibers. In these conditions the regenerative capacity of satellite cells becomes exhausted with time and fibrosis prevails. Acute traumatic injuries, such as strain injuries common in sport medicine, cause the rupture of large myofiber bundles leading to muscle regeneration and formation of scar tissue and new myotendinous junctions at the level of the rupture. Mechanical loading is essential for muscle regeneration, therefore, following initial immobilization to avoid the risk of reruptures, early remobilization is required to induce correct growth and orientation of regenerated myofibers. Finally, we discuss the causes of age-dependent decline in muscle regeneration potential and the possibility of boosting regeneration in aging muscle and in muscular dystrophies.
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15(28): Pp. 3209 - 3220
Esther M. Lafuente and Pedro A. Reche
[Open Access Plus] |
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T cell immune responses are driven by the recognition of peptide antigens (T cell epitopes) that are bound to major histocompatibility complex (MHC) molecules. T cell epitope immunogenicity is thus contingent on several events, including appropriate and effective processing of the peptide from its protein source, stable peptide binding to the MHC molecule, and recognition of the MHC-bound peptide by the T cell receptor. Of these three hallmarks, MHC-peptide binding is the most selective event that determines T cell epitopes. Therefore, prediction of MHC-peptide binding constitutes the principal basis for anticipating potential T cell epitopes. The tremendous relevance of epitope identification in vaccine design and in the monitoring of T cell responses has spurred the development of many computational methods for predicting MHC-peptide binding that improve the efficiency and economics of T cell epitope identification. In this report, we will systematically examine the available methods for predicting MHC-peptide binding and discuss their most relevant advantages and drawbacks.
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15(27): Pp. 3133 - 3145
Huige Li and Ulrich Forstermann
[Open Access Plus] |
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Nitric oxide (NO) produced by endothelial NO synthase (eNOS) represents an anti-atherosclerotic principle. NO bioavailability is decreased in atherosclerosis due to increased NO inactivation by reactive oxygen species and reduced NO synthesis. Various types of vascular pathophysiology are associated with oxidative stress, with NADPH oxidases as the major source of reactive oxygen species. These inactivate NO. Also, oxidative stress is likely to be the main cause for oxidation of the essential NOS cofactor, tetrahydrobiopterin (BH4). A lack of BH4 leads to eNOS uncoupling (i.e., uncoupling of oxygen reduction from NO synthesis in eNOS). Based on these pathomechanisms, the therapeutic potential of a number of compounds is discussed in this review: (1) NO donors; (2) L-arginine; (3) folic acid; (4) BH4 and its precursor sepiapterin; (5) compounds that upregulate eNOS and concomitantly maintain eNOS activity (e.g. midostaurin, betulinic acid, ursolic acid, AVE9488 and AVE3085); (6) compounds that enhance the de novo synthesis of BH4 by stimulating expression or activity of GTP cyclohydrolase I; and (7) 3-hydroxy-3-methylglutarylcoenzyme A inhibitors (statins) and drugs interrupting the renin-angiotensin-aldosterone system. Statins, angiotensin II type 1 receptor blockers, angiotensin-converting enzyme (ACE) inhibitors, the aldosterone antagonist eplerenone and the renin inhibitor aliskiren enhance NO bioactivity and reduce atherosclerosis progression through multiple mechanisms.
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15(24): Pp. 2833 - 2867
Dan W. Urry, Kelley D. Urry, Witold Szaflarski, Michal Nowicki and Maciej Zabel
[Open Access Plus] |
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The mechanism is presented whereby simultaneous hydrolysis of two molecules of ATP in the ATP-binding cassette (ABC) exporter protein, Sav 1866, opens a transmembrane channel to pump drug out of the cell and confers drug resistance, e.g., gives rise to methicillin resistant Staphylococcus aureus, MRSA. The proposed mechanism suggests pharmaceutical design strategies for overloading the capacity of two molecules of ATP to open access to the channel for export. Structural homology of Staphylococcus aureus, Sav 1866, to human P-glycoprotein and MRP2, suggests a similar mechanism could be relevant to human carcinoma cells. The transport mechanism utilizes two thermodynamic quantities - ΔGHA, the change in Gibbs free energy for hydrophobic association, and ΔGap, an apolar-polar repulsive free energy for hydration, derived from studies on designed elasticcontractile model proteins (ECMPs). These quantities also allow design of remarkably biocompatible ECMPs as drug delivery vehicles with remarkable control of release profiles and of ECMPs that provide the means of developing pharmaceuticals for blocking multi-drug resistance.
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15(22): Pp. 2535 - 2549
R. Smieskova, P. Fusar-Poli, P. Allen, K. Bendfeldt, R. D. Stieglitz, J. Drewe, E. W. Radue, P. K. McGuire, A. Riecher-Rossler and S. J. Borgwardt
[Open Access Plus] |
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Despite a large number of neuroimaging studies in schizophrenia reporting subtle brain abnormalities, we do not know to what extent such abnormalities reflect the effects of antipsychotic treatment on brain structure. We therefore systematically reviewed cross-sectional and follow-up structural brain imaging studies of patients with schizophrenia treated with antipsychotics. 30 magnetic resonance imaging (MRI) studies were identified, 24 of them being longitudinal and six cross-sectional structural imaging studies. In patients with schizophrenia treated with antipsychotics, reduced gray matter volume was described, particularly in the frontal and temporal lobes. Structural neuroimaging studies indicate that treatment with typical as well as atypical antipsychotics may affect regional gray matter (GM) volume. In particular, typical antipsychotics led to increased gray matter volume of the basal ganglia, while atypical antipsychotics reversed this effect after switching. Atypical antipsychotics, however, seem to have no effect on basal ganglia structure.
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15(21): Pp. 2488 - 2507
Feras Hatahet and Lloyd W. Ruddock
[Open Access Plus] |
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Protein folding in the cell is a complex process with a fine balance between productive and non-productive folding. To modulate, either up-regulating or down-regulating, the level of one specific protein with multiple approaches is possible, including the modulation of catalysed protein folding, the use of chemical and pharmacological chaperones, alteration of natural protein-protein interactions, the regulation of degradative pathways and manipulation of natural control mechanisms, such as the heat shock response and the unfolded protein response. Errors in proteostasis are linked to a wide range of disease states and many examples exist of the successful manipulation of proteostasis for the partial or complete elimination of the disease phenotype, including for many amyloid based diseases such as Parkinsons and Alzheimers as as well as for loss-of-function diseases such as Fabrys and Gauchers diseases. This review takes an overview of the different approaches that can be used to alter proteostasis with an emphasis on peptidomimetic inhibitors and activators of protein folding. It covers the modulators available, their mechanisms of action and potential limitations, including the problems of specificity in altering proteostasis.
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15(16): Pp. 1854 - 1867
Mitsuko Furuya, Yoshikazu Yonemitsu and Ichiro Aoki
[Open Access Plus] |
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Vascular system plays critical roles in tumor progression and metastasis. Tumor vessels generally sprout from preexisting vascular cells. In addition, pluripotent progenitor cells also participate in tumor neovascularization. The latter populations include endothelial progenitor cells, hematopoietic stem cells and mesenchymal stem cells that are stimulated and attracted into the lesion. Recent studies on tumor microenvironment have disclosed that BM (bone marrow)-derived progenitor cells contain unique subpopulations that do not become fully-differentiated vascular constituents; instead, they show the nature of immature myeloid or mesenchymal lineage, and they enhance tumor angiogenic milieu in close contact with tumor vessels. BM-derived cells also migrate into pre-metastatic niche and stimulate vascular beds of distant organ for attracting circulating tumor cells. Currently, several antiangiogenic molecules are under clinical trials and they are expected to improve overall prognosis. Humanized monoclonal antibody bevacizumab specifically targeting VEGF (vascular endothelial growth factor), and several tyrosine kinase inhibitors targeting VEGF receptors-mediated pathways are the most widely studied agents in several types of advanced cancers. It is obvious that VEGF contributes to tumor neovascularization as a mastermind molecule. On the other hand, the mechanism has also been elucidated how tumors evade VEGF targeting therapies. To establish safer and more effective antiangiogenic therapies, it is important to understand the crosscommunication between tumors and hosts in proinflammatory milieu. In this review, we discuss features of tumor angiogenic vessels and their microenvironment. Recent topics on the contribution of BM-derived cells, complexities of VEGFtargeting approaches, and chemoattractants that activate tumor vascular beds are summarized.
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15(13): Pp. 1546 - 1558
Patrice D. Cani and Nathalie M. Delzenne
[Open Access Plus] |
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Obesity is now classically characterized by a cluster of several metabolic disorders, and by a low grade inflammation. The evidence that the gut microbiota composition can be different between healthy and or obese and type 2 diabetic patients has led to the study of this environmental factor as a key link between the pathophysiology of metabolic diseases and the gut microbiota. Several mechanisms are proposed linking events occurring in the colon and the regulation of energy metabolism, such as i.e. the energy harvest from the diet, the synthesis of gut peptides involved in energy homeostasis (GLP-1, PYY … ), and the regulation of fat storage. Moreover, the development of obesity and metabolic disorders following a high-fat diet may be associated to the innate immune system. Indeed, high-fat diet feeding triggers the development of obesity, inflammation, insulin resistance, type 2 diabetes and atherosclerosis by mechanisms dependent of the LPS and/or the fatty acids activation of the CD14/TLR4 receptor complex. Importantly, fat feeding is also associated with the development of metabolic endotoxemia in human subjects and participates in the low-grade inflammation, a mechanism associated with the development of atherogenic markers. Finally, data obtained in experimental models and human subjects are in favour of the fact that changing the gut microbiota (with prebiotics and/or probiotics) may participate in the control of the development of metabolic diseases associated with obesity. Thus, it would be useful to find specific strategies for modifying gut microbiota to impact on the occurrence of metabolic diseases.
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16(34): Pp. 3776 - 3807
Eshaifol A. Omara, Antony Kam, Ali Alqahtania, Kong M. Li, Valentina Razmovski-Naumovski, Srinivas Nammi, Kelvin Chan, Basil D Roufogalis and George Q. Li
[Open Access Plus] |
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Diabetes is one of the most prevalent chronic diseases throughout the world. The majority of its complications arise from vascular- related inflammation apparently initiated by endothelial cell injury. One cause of this injury has been attributed to hyperglycaemia induced reactive oxygen species. Consequently, current drug developmental strategy has targeted specific inflammatory and oxidative stress pathways for the prevention of diabetic vascular complications. Herbal medicines have traditionally been used for the treatment of diabetes and its complications. In fact, current pre-clinical and clinical studies have demonstrated that many of them exhibit potent anti- inflammatory and anti-oxidative properties, and have also identified the active phytochemicals responsible for their activities. The present review summarises the latest research on the molecular mechanisms of diabetic vascular complications, and evaluates the level of scientific evidence for common herbal medicines and their bioactive phytochemicals. These agents have been shown to be effective through various mechanisms, particularly the NF-κB signalling pathways. Overall, herbal medicines and nutraceuticals, as well as their bioactive components, which exhibit anti-inflammatory and anti-oxidative properties, provide a promising approach for the prevention and treatment of diabetic complications.
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14(34): Pp. 3666 - 3673
A. Detzer, M. Overhoff, A. Mescalchin, M. Rompf and G. Sczakiel
[Open Access Plus] |
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The phosphorothioate(PS)-stimulated cellular uptake of naked short interfering RNA (siRNA) into mammalian cells indicates a promising new mechanistic strategy because it makes use of a caveosomal, rather than an endosomal pathway, which is used by the majority of known delivery systems. This PS-stimulated mode delivers large amounts of siRNA primarily into the perinuclear space which is related to measurable though moderate target suppression. The observed limited efficacy seems to be related to intracellular trapping of siRNA. Here, we studied the intracellular localisation of siRNA and Argonaute 2 (Ago2), the major component of the RNA interference (RNAi) machinery, by density gradient centrifugation and fluorescence microscopy after PS-stimulated delivery or transfection with Lipofectamine 2000. The two cell lines ECV-304 and SKRC-35 both take up siRNA in the PSstimulated mode but only ECV-304 shows RNAi, i.e. siRNA-mediated suppression of lamin A/C expression, whereas SKRC-35 does not. This lack of RNAi in the latter cell line seems to be due to a block of an intracellular siRNA translocation process. This study provides strong evidence for the view that co-localisation of siRNA and Ago2 in the vicinity of the rough endoplasmic reticulum (rER) in ECV-304 cells is related to target inhibition, whereas density gradient fractionation of cell organelles shows a lack of co-localisation in SKRC-35 cells in which RNAi does not occur after the PS-mediated delivery. In summary, we propose to exploit this dual cell system to identify important steps of intracellular trafficking of siRNA after PS-mediated delivery that are crucial for its biological activity and which seem to be of general importance for the understanding of the intracellular trafficking and release of siRNA.
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14(34): Pp. 3637 - 3655
S. D. Laufer and T. Restle
[Open Access Plus] |
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Cellular uptake of therapeutic oligonucleotides and subsequent intracellular trafficking to their target sites represents the major technical hurdle for the biological effectiveness of these potential drugs. Accordingly, laboratories worldwide focus on the development of suitable delivery systems. Among the different available non-viral systems like cationic polymers, cationic liposomes and polymeric nanoparticles, cell-penetrating peptides (CPPs) represent an attractive concept to bypass the problem of poor membrane permeability of these charged macromolecules. While uptake per se in most cases does not represent the main obstacle of nucleic acid delivery in vitro, it becomes increasingly apparent that intracellular trafficking is the bottleneck. As a consequence, in order to optimize a given delivery system, a side-by-side analysis of nucleic acid cargo internalized and the corresponding biological effect is required to determine the overall efficacy. In this review, we will concentrate on peptide-mediated delivery of siRNAs and steric block oligonucleotides and discuss different methods for quantitative assessment of the amount of cargo taken up and how to correlate those numbers with biological effects by applying easy to handle reporter systems. To illustrate current limitations of non-viral nucleic acid delivery systems, we present own data as an example and discuss options of how to enhance trafficking of molecules entrapped in cellular compartments.
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14(28): Pp. 2983 - 2998
Eyal Mishani, Galith Abourbeh, Martin Eiblmaier and Carolyn J. Anderson
[Open Access Plus] |
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Protein tyrosine kinases (PTKs) play a pivotal role in signal transduction pathways and in the development and maintenance of various cancers. They are involved in multiple processes such as transcription, cell cycle progression, proliferation, angiogenesis and inhibition of apoptosis. Among the PTKs, the EGFR is one of the most widely studied and has emerged as a promising key target for the treatment of cancer. Indeed, several drugs directed at this receptor are FDAapproved and many others are at various stages of development. However, thus far, the therapeutic outcome of EGFRtargeted therapy is suboptimal and needs to be refined. Quantitative PET molecular imaging coupled with selective labelled biomarkers may facilitate in vivo EGFR-targeted drug efficacy by noninvasively assessing the expression of EGFR in tumor, guiding dose and regime by measuring target drug binding and receptor occupancy as well as potentially detecting the existence of a primary or secondary mutation leading to either drug interaction or failure of EGFR recognition by the drug. This review describes the attempts to develop labelled EGFR molecular imaging agents that are based either on low molecular weight tyrosine kinase inhibitors or monoclonal antibodies directed to the extracellular binding domain of the receptor to be used in nuclear medicine modalities.
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14(20): Pp. 1950 - 1961
I. Pusic and J. F. DiPersio
[Open Access Plus] |
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Mobilized, peripheral blood stem cells (PBSC) are increasingly used for both autologous and allogeneic transplants. Granulocyte- colony-stimulating factor is the most widely used cytokine for mobilization. Several different mechanisms of stem cell mobilization have been proposed including protease-dependent and non-protease- dependent mechanisms. In autologous transplants, the addition of chemotherapy to mobilization can enhance the yield of PBSC collected but with substantial adverse effects, and not necessarily faster engraftment. In allogeneic transplants, the use of mobilized PBSC is associated with faster engraftment and donor chimerism compared to bone marrow. In the majority of studies, the rate of acute graft-versus-host disease (GVHD) has not been shown to be significantly higher with PBSC, but the rate of chronic GVHD appears to be increased. Several different strategies have been proposed for patients and donors who fail initial mobilization, including the use of novel agents. AMD3100 (Plerixafor) works by directly inhibiting the interaction between stromal cell-derived factor-1 and its receptor CXCR4, and mobilizes hematopoietic stem cells within hours. It is being studied alone or in conjunction with growth factors for PBSC mobilization in both autologous and allogeneic settings. Although the use of growth factors after PBSC transplantation results in faster neutrophil engraftment its impact on treatment-related mortality and survival does not appear significant. Here, we review the biology and methods of PBSC mobilization, the effect of growth factors on normal donors and the controversies of growth factor use in the post-transplant setting. We also review the data on novel agents for mobilization of stem cells.
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14(5): Pp. 412 - 421
N. G. Abraham, P. L. Tsenovoy, J. McClung and G. S. Drummond
[Open Access Plus] |
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Heme oxygenase-1 (HO-1) is central to the regulation of oxidative injury. The role of increased HO-1 expression and Heme oxygenase (HO) activity in mitigating the detrimental side effect of diabetes is examined. A review of the mechanism(s) of action is included. This may lead to the development of pharmacological and genetic approaches to mitigate the clinical complications associated with the progression of diabetes and obesity.
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14(3): Pp. 253 - 268
R. Paganelli, A. Giovannetti, M. Pierdominici, A. Di Iorio, R. Cianci, G. Murdaca, F. Puppo and F. Pandolfi
[Open Access Plus] |
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The immune system has evolved sophisticate mechanisms controlling the development of responses to dangerous antigens while avoiding unnecessary attacks to innocuous, commensal or self antigens. The risk of autoimmunity is continuously checked and balanced against the risk of succumbing to exogenous infectious agents. It is therefore of paramount importance to understand the molecular events linking the breakdown of tolerance and the development of immunodeficiency. Apoptotic mechanisms are used to regulate the development of thymocytes, the shaping of T cell repertoire, its selection and the coordinate events leading to immune responses in the periphery. Moreover, they are at the heart of the homeostatic controls restoring T cell numbers and establishing T cell memory. T lymphocytes shift continuously from survival to death signals to ensure immune responsiveness without incurring in autoimmune damage. In this review we shall consider some key facts on the relationship of lymphopenia to autoreactivity, the mechanisms controlling positive and negative selection in the thymus, the role of apoptosis in selected primary immunodeficiency states and in systemic and organ-specific autoimmunity, with examples from human diseases and their animal models.
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13(20): Pp. 2101 - 2112
Chisa Shukunami and Yuji Hiraki
[Open Access Plus] |
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The negative regulation of angiogenesis may provide a promising therapeutic target for a number of lifestyle-related diseases, as the switch to an angiogenic phenotype in many tissues represents a critical step during the progression of such disorders. Cartilage is avascular and shows resistance to vascular invasion from the surrounding well-vascularized mesenchyme. Using guanidine extracts of fetal bovine cartilage, we have identified and purified chondromodulin-I (ChM-I) as an angiogenesis inhibitor. The cDNA sequence of this factor has revealed that the ChM-I precursor protein is a type II transmembrane glycoprotein (334 amino acids) and that mature ChM-I is encoded in the C-terminal region of the precursor. After cleavage of the ChM-I precursor at its processing site, mature ChM-I (120 amino acids) is secreted from chondrocytes into the extracellular matrix. Following on from the identification of ChM-I as an angiogenesis inhibitor in cartilage, we have also cloned both mouse and human tenomodulin (TeM), which share significant homology with ChM-I at their C-termini. Moreover, exogenous expression experiments in COS cells suggests that TeM is a type II transmembrane glycoprotein (317 amino acids). When overexpressed in HUVECs, the C-terminal domain (116 amino acids) of the TeM protein shows both anti-angiogenic and anti-tumorigenic activities at equivalent levels to mature ChM-I. In our present review, we discuss the structure, biological activities and localization of these anti-angiogenic molecules.
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12(25): Pp. 3261 - 3279
A. Miller-Larsson and O. Selroos
[Open Access Plus] |
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Asthma treatment guidelines advocate the use of long-acting β2-agonists (LABA) in addition to inhaled corticosteroids (ICS) in patients whose asthma is uncontrolled by ICS alone, thereby addressing two processes fundamental to asthma: bronchoconstriction and inflammation. Superior control - including a reduction in severe exacerbations - of asthma and COPD by ICS/LABA combination therapy has been demonstrated. Results from clinical studies suggest additive and potentially synergistic effects when the two agents are used in combination. No new safety-related issues have been identified with ICS/LABA compared with the monocomponents. The exact mechanisms for the enhanced efficacy of ICS/LABA combinations are under investigation but likely include drug interactions at the receptor level and interwoven signalling pathways, which may result in improved function of 2- adrenoceptors and steroid receptors. Data from preclinical studies provide evidence of additive, compensatory, complementary and synergistic effects of ICS and LABA in the control of inflammation and airway and lung remodelling. These effects may contribute to the improved efficacy seen when treating asthma and COPD with ICS/LABA combinations in clinical studies. Two ICS/LABA combination products are available: budesonide/formoterol (Symbicort) and salmeterol/fluticasone propionate (SeretideTM). An ICS/LABA combination in a single inhaler represent safe, effective and convenient treatment options for the management of patients with asthma and COPD. Clinical results also suggest that adjustable dosing with budesonide/formoterol provides better asthma control than fixed dosing. Further elucidation of the underlying mechanisms responsible for this superior disease control is needed.
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12(15): Pp. 1867 - 1877
Matthias Gotte
[Open Access Plus] |
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A single cycle of nucleotide incorporation by the reverse transcriptase of the human immunodeficiency virus type 1 (HIV-1 RT) involves the initial binding of an incoming nucleotide, a conformational change that traps the substrate, the formation of a new phosphodiester bond, the release of pyrophosphate (PPi), and ultimately polymerase translocation, which clears the nucleotide binding site. This article reviews different mechanistic models for polymerase translocation with emphasis placed on HIV-1 RT. Structure-function analyses of stalled complexes of HIV-1 RT provide strong evidence to suggest that the enzyme can oscillate between pre- and post-translocational states. Nucleotide hydrolysis is not required for the movement of the polymerase in a stalled configuration; thermal energy is sufficient to allow random bidirectional sliding. The next complementary nucleotide, following the incorporated chain-terminator, acts like a pawl of a ratchet that traps the enzyme in the post-translocation state and prevents the reverse movement. Quantitative footprinting experiments have shown that the concentration of the templated nucleotide required to shift the translocational equilibrium forward depends crucially on the structure of the 3end of the primer. Changes in the relative population of pre- and post-translocation complexes can influence rates of excision of incorporated NRTIs, which, in turn, affects drug susceptibility. The concept of a ratchet model of HIV-1 RT translocation and its implications for drug action and resistance, and the discovery and development of novel antiviral compounds is discussed.
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