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OPEN ACCESS PLUS
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Contents
14(1): Pp. 13 - 19
Etheresia Pretorius, Janette Bester, Natasha Vermeulen and Boguslaw Lipinski
[Open Access Plus] |
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Blood coagulation under physiological conditions is activated by thrombin, which converts soluble plasma fibrinogen (FBG) into an insoluble clot. The structure of the enzymatically-generated clot is very characteristic being composed of thick fibrin fibers susceptible to the fibrinolytic degradation. However, in chronic degenerative diseases, such as atherosclerosis, diabetes mellitus, cancer, and neurological disorders, fibrin clots are very different forming dense matted deposits (DMD) that are not effectively removed and thus create a condition known as thrombosis. We have recently shown that trivalent iron (ferric ions) generates hydroxyl radicals, which subsequently convert FBG into abnormal fibrin clots in the form of DMDs. A characteristic feature of DMDs is their remarkable and permanent resistance to the enzymatic degradation. Therefore, in order to prevent thrombotic incidences in the degenerative diseases it is essential to inhibit the iron-induced generation of hydroxyl radicals. This can be achieved by the pretreatment with a direct free radical scavenger (e.g. salicylate), and as shown in this paper by the treatment with oxidizing agents such as hydrogen peroxide, methylene blue, and sodium selenite. Although the actual mechanism of this phenomenon is not yet known, it is possible that hydroxyl radicals are neutralized by their conversion to the molecular oxygen and water, thus inhibiting the formation of dense matted fibrin deposits in human blood.
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13(12): Pp. 1525 - 1534
Joo Ern Ang, Stan Kaye and Udai Banerji
[Open Access Plus] |
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Anti-cancer clinical drug development is currently costly and slow with a high attrition rate. There is thus an urgent and unmet need to integrate pharmacodynamic biomarkers into early phase clinical trials in the framework provided by the “pharmacologic audit trail” in order to overcome this challenge. This review discusses the rationale, advantages and disadvantages, as well as the practical considerations of various tissue-based approaches to perform pharmacodynamic studies in early phase oncology clinical trials using case histories of molecular targeting agents such as PI3K, m-TOR, HSP90, HDAC and PARP inhibitors. These approaches include the use of normal “surrogate” tissues such as peripheral blood mononuclear cells, platelet-rich plasma, plucked hair follicles, skin biopsies, plasma-based endocrine assays, proteomics, metabolomics and circulating endothelial cells. In addition, the review discusses the use of neoplastic tissues including tumor biopsies, circulating tumor DNA and tumor cells and metabolomic approaches. The utilization of these tissues and technology platforms to study biomarkers will help accelerate the development of molecularly targeted agents for the treatment of cancer.
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13(10): Pp. 1308 - 1323
Julius Semenas, Cinzia Allegrucci, Stephen A. Boorjian, Nigel P. Mongan and Jenny Liao Persson
[Open Access Plus] |
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Most of the prostate cancers (PCa) in advanced stage will progress to castration-resistant prostate cancer (CRPC). Within CRPC group, 50-70% of the patients will develop bone metastasis in axial and other regions of the skeleton. Once PCa cells spread to the bone, currently, no treatment regimens are available to eradicate the metastasis, and cancer- related death becomes inevitable. In 2012, it is estimated that there will be 28,170 PCa deaths in the United States. Thus, PCa bone metastasis-associated clinical complications and treatment resistance pose major clinical challenges. In this review, we will present recent findings on the molecular and cellular pathways that are responsible for bone metastasis of PCa. We will address several novel mechanisms with a focus on the role of bone and bone marrow microenvironment in promoting PCa metastasis, and will further discuss why prostate cancer cells preferentially metastasize to the bone. Additionally, we will discuss novel roles of several key pathways, including angiogenesis and extracellular matrix remodeling in bone marrow and stem cell niches with their relationship to PCa bone metastasis and poor treatment response. We will evaluate how various chemotherapeutic drugs and radiation therapies may allow aggressive PCa cells to gain advantageous mutations leading to increased survival and rendering the cancer cells to become resistant to treatment. The novel concept relating several key survival and invasion signaling pathways to stem cell niches and treatment resistance will be reviewed. Lastly, we will provide an update of several recently developed novel drug candidates that target metastatic cancer microenvironments or niches, and discuss the advantages and significance provided by such therapeutic approaches in pursuit of overcoming drug resistance and treating advanced PCa.
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13(6): Pp. 744 - 752
Vincenzo Corbo, Giampaolo Tortora and Aldo Scarpa
[Open Access Plus] |
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Pancreatic ductal adenocarcinoma (referred here as pancreatic cancer) is a lethal disease with the worst prognosis among all solid tumors. Surgical resection represents the only hope for cure but it is possible only in patients that present with local disease (about 20% of cases). Whether dismal prognosis of pancreatic cancer is a result of late diagnosis or early dissemination to distant organ is still a debate. Moreover, this disease shows an intrinsic chemotherapeutic resistance that has been mainly ascribed to the presence of a dense stromal reaction that significantly impairs drugs delivery. Clinical management of pancreatic cancer patients relies on few molecular markers (e.g., the diagnostic marker CA19-9) that, however, present several limitations to their use. The clinical usefulness of somatic alterations in well-characterized genes (such as KRAS and TP53), whose detection is technically feasible in different biological samples, has been extensively investigated leading to inconsistent results. Furthermore, none of the candidate molecular markers identified in recent years has shown an appropriate clinical performance and therefore none is routinely used. This depicts a scenario where the identification of novel and effective clinical biomarkers is mandatory. Very recent genome-wide comprehensive studies have shed light on the high degree of genetic complexity and heterogeneity of the pancreatic cancers. Although far from being introduced into the clinical settings, results from those studies are expected to change definitively the perspective through which we look at the clinical management of pancreatic cancer patients towards a personalized cancer medicine.
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13(4): Pp. 471 - 482
Yuan-Ping Pang, Stephen Brimijoin, David W. Ragsdale, Kun Yan Zhu and Robert Suranyi
[Open Access Plus] |
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Insect pests are responsible for human suffering and financial losses worldwide. New and environmentally safe insecticides are urgently needed to cope with these serious problems. Resistance to current insecticides has resulted in a resurgence of insect pests, and growing concerns about insecticide toxicity to humans discourage the use of insecticides for pest control. The small market for insecticides has hampered insecticide development; however, advances in genomics and structural genomics offer new opportunities to develop insecticides that are less dependent on the insecticide market. This review summarizes the literature data that support the hypothesis that an insect-specific cysteine residue located at the opening of the acetylcholinesterase active site is a promising target site for developing new insecticides with reduced off-target toxicity and low propensity for insect resistance. These data are used to discuss the differences between targeting the insect-specific cysteine residue and targeting the ubiquitous catalytic serine residue of acetylcholinesterase from the perspective of reducing off-target toxicity and insect resistance. Also discussed is the prospect of developing cysteine-targeting anticholinesterases as effective and environmentally safe insecticides for control of disease vectors, crop damage, and residential insect pests within the financial confines of the present insecticide market.
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13(3): Pp. 352 - 372
Andrew Robinson, Rebecca J. Causer and Nicholas E. Dixon
[Open Access Plus] |
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New antibiotics with novel modes of action are required to combat the growing threat posed by multi-drug resistant bacteria. Over the last decade, genome sequencing and other high-throughput techniques have provided tremendous insight into the molecular processes underlying cellular functions in a wide range of bacterial species. We can now use these data to assess the degree of conservation of certain aspects of bacterial physiology, to help choose the best cellular targets for development of new broad-spectrum antibacterials. DNA replication is a conserved and essential process, and the large number of proteins that interact to replicate DNA in bacteria are distinct from those in eukaryotes and archaea; yet none of the antibiotics in current clinical use acts directly on the replication machinery. Bacterial DNA synthesis thus appears to be an underexploited drug target. However, before this system can be targeted for drug design, it is important to understand which parts are conserved and which are not, as this will have implications for the spectrum of activity of any new inhibitors against bacterial species, as well as the potential for development of drug resistance. In this review we assess similarities and differences in replication components and mechanisms across the bacteria, highlight current progress towards the discovery of novel replication inhibitors, and suggest those aspects of the replication machinery that have the greatest potential as drug targets.
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12(13): Pp. 1957 - 1973
Pier-Luigi Lollini, Giordano Nicoletti, Lorena Landuzzi, Federica Cavallo, Guido Forni, Carla De Giovanni and Patrizia Nanni
[Open Access Plus] |
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The immune system effectively prevents cancer, whereas severe immunodepression increases its incidence. Cancer immunoprevention is a strategy based on the concept that enhancement of tumor immunity in healthy individuals reduces cancer risk. It can be viewed as a kind of chemoprevention. For cancer immunoprevention, the cancer universe can be neatly divided between tumors caused - directly or indirectly - by infectious agents and all other tumors. Immunoprevention of tumors caused by infectious agents is already implemented at the population level for hepatitis B virus (HBV)-related hepatocellular carcinoma and for tumors caused by human papillomaviruses (HPV), like cervical carcinoma. Now the challenge is to develop immunological strategies to prevent the bulk ( > 80%) of human tumor burden, unrelated to infections. Both vaccines against tumor antigens and immune modulators can prevent tumor onset in cancerprone mice. These studies outlined the target antigens and the molecular and cellular mechanisms of cancer immunoprevention: a) the best target antigens are surface molecules controlling tumor growth and progression (oncoantigens); b) combinations of potent vaccines and nonspecific stimuli (adjuvants) yield the strongest protection; c) immunoprevention must start early in the natural history of tumors, before key progression events like the onset of carcinoma in situ; d) lifetime protection requires repeated boosts, to maintain a strong and steady immune response; e) antibodies and helper, rather than cytotoxic, T cells mediate long-term protection from tumor onset; f) immunoprevention can be combined with chemoprevention. The development of agents like tamoxifen, which went from cancer therapy to chemoprevention, could be a model for the translation of cancer immunoprevention from mice to humans.
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12(7): Pp. 1000 - 1017
Annemarie H. Meijer and Herman P. Spaink
[Open Access Plus] |
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The zebrafish holds much promise as a high-throughput drug screening model for immune-related diseases, including inflammatory and infectious diseases and cancer. This is due to the excellent possibilities for in vivo imaging in combination with advanced tools for genomic and large scale mutant analysis. The context of the embryos developing immune system makes it possible to study the contribution of different immune cell types to disease progression. Furthermore, due to the temporal separation of innate immunity from adaptive responses, zebrafish embryos and larvae are particularly useful for dissecting the innate host factors involved in pathology. Recent studies have underscored the remarkable similarity of the zebrafish and human immune systems, which is important for biomedical applications. This review is focused on the use of zebrafish as a model for infectious diseases, with emphasis on bacterial pathogens. Following a brief overview of the zebrafish immune system and the tools and methods used to study host-pathogen interactions in zebrafish, we discuss the current knowledge on receptors and downstream signaling components that are involved in the zebrafish embryos innate immune response. We summarize recent insights gained from the use of bacterial infection models, particularly the Mycobacterium marinum model, that illustrate the potential of the zebrafish model for high-throughput antimicrobial drug screening.
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12(7): Pp. 942 - 954
Salvatore Bozzaro and Ludwig Eichinger
[Open Access Plus] |
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The use of simple hosts such as Dictyostelium discoideum in the study of host pathogen interactions offers a number of advantages and has steadily increased in recent years. Infection-specific genes can often only be studied in a very limited way in man and even in the mouse model their analysis is usually expensive, time consuming and technically challenging or sometimes even impossible. In contrast, their functional analysis in D. discoideum and other simple model organisms is often easier, faster and cheaper. Because host-pathogen interactions necessarily involve two organisms, it is desirable to be able to genetically manipulate both the pathogen and its host. Particularly suited are those hosts, like D. discoideum, whose genome sequence is known and annotated and for which excellent genetic and cell biological tools are available in order to dissect the complex crosstalk between host and pathogen. The review focusses on host-pathogen interactions of D. discoideum with Legionella pneumophila, mycobacteria, and Salmonella typhimurium which replicate intracellularly.
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12(5): Pp. 724 - 736
L. H. Jiang, N. Gamper and D. J. Beech
[Open Access Plus] |
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Mammals contain 28 genes encoding Transient Receptor Potential (TRP) proteins. The proteins assemble into cationic channels, often with calcium permeability. Important roles in physiology and disease have emerged and so there is interest in whether the channels might be suitable therapeutic drug targets. Here we review selected members of three subfamilies of mammalian TRP channel (TRPC5, TRPM2 and TRPA1) that show relevance to sensing of adversity by cells and biological systems. Summarized are the cellular and tissue distributions, general properties, endogenous modulators, protein partners, cellular and tissue functions, therapeutic potential, and pharmacology. TRPC5 is stimulated by receptor agonists and other factors that include lipids and metal ions; it heteromultimerises with other TRPC proteins and is involved in cell movement and anxiety control. TRPM2 is activated by hydrogen peroxide; it is implicated in stress-related inflammatory, vascular and neurodegenerative conditions. TRPA1 is stimulated by a wide range of irritants including mustard oil and nicotine but also, controversially, noxious cold and mechanical pressure; it is implicated in pain and inflammatory responses, including in the airways. The channels have in common that they show polymodal stimulation, have activities that are enhanced by redox factors, are permeable to calcium, and are facilitated by elevations of intracellular calcium. Developing inhibitors of the channels could lead to new agents for a variety of conditions: for example, suppressing unwanted tissue remodeling, inflammation, pain and anxiety, and addressing problems relating to asthma and stroke.
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12(4): Pp. 556 - 562
Arash S. Saffar, Heather Ashdown and Abdelilah S. Gounni
[Open Access Plus] |
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Neutrophil-dominated inflammation plays an important role in many airway diseases including asthma, chronic obstructive pulmonary disease (COPD), bronchiolitis and cystic fibrosis. In cases of asthma where neutrophil-dominated inflammation is a major contributing factor to the disease, treatment with corticosteroids can be problematic as corticosteroids have been shown to promote neutrophil survival which, in turn, accentuates neutrophilic inflammation. In light of such cases, novel targeted medications must be developed that could control neutrophilic inflammation while still maintaining their antibacterial/anti-fungal properties, thus allowing individuals to maintain effective innate immune responses to invading pathogens. The aim of this review is to describe the molecular mechanisms of neutrophil apoptosis and how these pathways are modulated by glucocorticoids. These new findings are of potential clinical value and provide further insight into treatment of neutrophilic inflammation in lung disease.
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11(12): Pp. 1551 - 1570
Halina Was, Jozef Dulak and Alicja Jozkowicz
[Open Access Plus] |
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Heme oxygenase-1 (HO-1) degrades heme to carbon monoxide (CO), biliverdin, and ferrous iron. As HO-1 expression is highly increased by stressful conditions, the major role of the enzyme is the protection against oxidative injury. Additionally, it regulates cell proliferation, modulates inflammatory response and facilitates angiogenesis. Beneficial activities of HO-1 have been recognized in many pathological states e.g. atherosclerosis, diabetes, ischemia/reperfusion injury or organ transplantation. Interestingly HO-1 expression is very often boosted in tumor tissues and could be further elevated in response to radio-, chemo-, or photodynamic therapy. A growing body of evidence suggests that HO-1 may play a role in tumor induction and can potently improve the growth and spread of tumors. This review discusses the implications of HO-1 properties for tumor proliferation and cell death, differentiation, angiogenesis and metastasis, and tumor-related inflammation. Finally, it suggests that pharmacological agents that regulate HO activity or HO-1 gene silencing may become powerful tools for preventing the onset or progression of various cancers and sensitize them to anticancer therapies.
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11(11): Pp. 1468 - 1482
Masayoshi Takeuchi, Jun-ichi Takino and Sho-ichi Yamagishi
[Open Access Plus] |
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Diabetic vascular complications are leading causes of acquired blindness, end-stage renal failure, a variety of neuropathies, and accelerated atherosclerosis, which may be involved in the disabilities and high mortality rates suffered by diabetic patients. Continuous hyperglycemia is involved in the pathogenesis of diabetic micro- and macrovascular complications via various metabolic pathways, and numerous hyperglycemia-induced metabolic and hemodynamic conditions exist, including increased generation of various types of advanced glycation end-products (AGEs). Recently, we demonstrated that glyceraldehyde-derived AGEs (Glycer-AGEs), the predominant components of toxic AGEs (TAGE), play an important role in the pathogenesis of angiopathy in diabetic patients. Moreover, a growing body of evidence suggests that the interaction of TAGE with the receptor for AGEs (RAGE) alters intracellular signaling, gene expression, and the release of pro-inflammatory molecules and elicits oxidative stress generation in numerous types of cells, all of which may contribute to the pathological changes observed in diabetic vascular complications. Therefore, the inhibition of TAGE formation, blockade of TAGE-RAGE interaction, and the suppression of RAGE expression or its downstream pathways are promising targets for therapeutic interventions against diabetic vascular complications. In this review, we discuss the pathophysiological role of the TAGE-RAGE-oxidative stress system and related therapeutic interventions for preventing the development and progression of diabetic vascular complications.
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11(9): Pp. 1157 - 1168
Kelsi L. Kretschmann, Henok Eyob, Saundra S. Buys and Alana L. Welm
[Open Access Plus] |
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Macrophage Stimulating Protein (MSP) is the only known ligand for the receptor tyrosine kinase Ron. The MSP/Ron pathway is involved in several important biological processes, including macrophage activity, wound healing, and epithelial cell behavior. A role for MSP/Ron in breast cancer has recently been elucidated, wherein this pathway regulates tumor growth, angiogenesis, and metastasis. Here, we review the recent literature surrounding MSP/Ron function in tumor cells, inflammatory cells, and osteoclasts – cell types that often coexist in breast tumor microenvironments. We discuss the potential implications of MSP/Ron activity occurring concurrently in these cell types on tumor progression and metastasis. Lastly, we outline the potential for targeting MSP/Ron as a novel therapy for breast cancer, and for other cancer types.
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11(8): Pp. 926 - 935
Virginija Jazbutyte and Thomas Thum
[Open Access Plus] |
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MicroRNA-21 (miR-21) expression is activated in multiple types of cancers, such as breast, liver, brain, prostate, myometrial cancers but also in cardiovascular disease. MiR-21 regulates a plethora of target proteins which are involved in cellular survival, apoptosis and cell invasiveness. MiR-21 regulation is complex due to an own promoter that is target for various transcription factors and hormones. The consistent miR-21 overexpression under pathophysiological conditions points to miR-21 as a valuable tool for new therapeutic strategies. In this review, we present and analyze current data about miR-21 expression in various pathologies ranging from cancer to cardiovascular disease. Further, miR- 21 regulatory mechanisms and miR-21 downstream targets are discussed. Finally, we highlight the particular role of miR- 21 as a therapeutic target in various diseases.
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10(12): Pp. 1212 - 1226
Akanksha Gupta, Mark D. Williams, William L. Macias, Bruce A. Molitoris and Brian W. Grinnell
[Open Access Plus] |
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Protein C is a plasma serine protease that when activated plays a central role in modulating the function of the vascular endothelium and its interface with the innate immune system. Activated protein C (APC) has a dual mechanism of action via the feedback inhibition of thrombin generation, and as an agonist of protease activated receptor-1 (PAR-1). Through different cofactor interactions, this dual mechanism of antithrombotic and cytoprotective activity results in the ability of APC to modulate endothelial dysfunction by blocking cytokine signaling, functional cell adhesion expression, vascular permeability, apoptosis, and modulating leukocyte migration and adhesion. Deficiency in protein C, which occurs during systemic inflammatory activation, is highly associated with organ dysfunction. APC has shown efficacy in a number of preclinical models of thrombosis and ischemia, and the recombinant human APC drotrecogin alfa (activated), reduces mortality in patients with high-risk severe sepsis. The ability of APC to suppress pro-inflammatory pathways and enhance cellular survival suggests that APC plays a key role in the adaptive response to protect the vessel wall from insult and to enhance endothelial, cellular, and organ survival. The focus of this review will be to summarize the emerging data suggesting the potential therapeutic benefit of APC and related members of the pathway in the prevention and treatment of acute kidney injury.
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10(10): Pp. 1001 - 1008
A. Dominguez-Rodriguez, P. Abreu-Gonzalez and J. C. Kaski
[Open Access Plus] |
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Clinicians have used additional tools to aid clinical assessment and to enhance their ability to identify the “vulnerable” patient at risk for cardiovascular diseases. Circulating biomarkers are one such tool used for identifying better high-risk individuals and to prognosticate effectively and treat patients with disease. A persistent immune activation is a main feature of atherosclerosis. The inflammatory activity is not only detectable in the vascular wall, but also in peripheral blood. Patients with coronary artery disease show increased numbers of neutrophils and T cells as well as elevated levels of several inflammatory mediators. On the other hand, several cardiovascular disease states show a daily cycle of activity, i.e. a peak incidence of cerebrovascular and cardiovascular events has been documented in the early morning hours. Several studies have shown diurnal variations in inflammatory systemic markers in patients with acute coronary syndrome. Diurnal variations can alter the analysis of blood-derived samples. Prior to the analysis of a blood sample, multiple steps are necessary to generate the desired specimen. The knowledge of diurnal variations is a prerequisite to understand and control their impact. This brief review comments the effect of the diurnal variation on the most important inflammatory systemic biomarkers in the setting acute coronary syndrome: interleukin-6, neopterin, matrix metalloproteinases, vascular cell adhesion molecule-1, intercellular adhesión molecule-1, soluble CD40 ligand, and C-reactive protein.
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8(11): Pp. 1181 - 1189
Hong Lu, Lisa A. Cassis and Alan Daugherty
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Increased blood pressure is a consistent risk factor for the development of atherosclerotic diseases in humans, although the basis for this relationship is unknown. Genetically engineered mice are now commonly used to study mechanisms of atherosclerosis. More recently, blood pressure can be reliably measured in conscious mice using either tail cuff or telemetric techniques. Thus, mouse models permit the investigation of the complex interactions of blood pressure and atherogenesis. Most mouse models exhibiting hypertension have increased atherosclerotic lesion size, although there have been exceptions to these findings. Also, there are several reports that have used methods to decrease blood pressure and demonstrated reduced atherosclerosis. In contrast, there are many studies in which atherosclerosis has been altered without changes in blood pressure, and conversely, studies in which blood pressure changes did not alter atherosclerosis. Studies that have specifically defined the role of elevated systolic blood pressure on the development of atherosclerosis have uniformly demonstrated that pressure per se is not responsible for changes in lesion development. Thus, while increased systolic blood pressure is frequently associated with atherosclerosis, the stimulus for the hypertension appears to be the major determinant of atherogenesis rather than pressure per se. A consistent theme in the literature has been that perturbations of the renin angiotensin system display the strongest correlations between blood pressure and atherosclerosis.
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7(11): Pp. 1411 - 1419
Leung Kim and Alan R. Kimmel
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GSK3 is a multifunctional protein kinase that is pivotal for the regulation of metabolism, the cytoskeleton, and gene expression. Multicellular eukaryotes utilize GSK3 as a molecular switch to specify distinct cell fates, but also to organize these cells spatially within the developing organism. We discuss the central role of GSK3 in control of the Wnt, Hedgehog, cAMP (in Dictyostelium), and other signaling pathways, but also focus on significant new evidence that GSK3 is required to establish cell polarity.
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