Current Medicinal Chemistry (v.15, #28)

The underlying gene interactions that collectively govern the regulation of cellular events can be studied by simultaneous measurement of the levels of mRNA from multiple involved genes. Ideally a single cell should be studied, for comparison with other cells, like and unlike. However, conventional gene expression profiling techniques require several thousands or even millions of cells in order to obtain a sufficient amount of mRNA for analysis. Obtaining this number of cells of a single type is difficult, especially in attempting to study rare stem cells. Single-cell gene expression profiling can, in theory, overcome this limitation. However, conventional analytic methods and equipment are not suitable for analyzing a single-cell, which has a volume of only one or two picoliters. Inexpensive microfluidic devices that can precisely manipulate several nanoliters of fluids are, in theory, ideal for single-cell analysis. By performing biochemical reactions in small volumes, microfluidic devices also minimize material loss in single-cell analysis. This review describes current microfluidic technology applied to single-cell analysis, with a primary focus upon study of single mammalian stem cells. Microfluidic devices have the potential to transform single-cell analysis from a major technological challenge task to a relatively routine procedure for research and clinical assays.

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants well known as mutagenic/carcinogenic agents. This review will discuss recent theoretical studies regarding the stability and reactivity of ultimate carcinogenic metabolites from PAHs, focusing on their diol epoxide and amine derivatives. Geometrical and electronic features will be analyzed in order to obtain structure-activity relationships. Charge delocalization modes (positive charge density distribution), substituent effects, and conformational aspects will be considered. Computed properties will be compared with the available biological activity data. Correlations between experimental mutagenic potencies reported in the literature and calculated reaction energies and electronic properties will be shown. Heteroaromatic compounds (aza-PAHs, thia-PAHs, and heteroaromatic amines) will also be examined. To model the important step of covalent adduct formation, calculation of the adducts resulting from bond formation between some of these electrophilic intermediates and nucleotide bases (guanine, cytosine) will be described.

The neuronal nicotinic receptor has gained considerable recognition as a target, not just for combating drug addiction but also for treating a number of illnesses ranging from neurodegenerative diseases to psychotic disorders like schizophrenia. This recognition has led to a burgeoning field examining the receptor at all levels. A class of nicotinic receptors that contains the and#945;7 gene product, apparently as a homomer, illustrates this multidisciplinary approach. Here, we review recent progress in our understanding of this class of receptors based on data from molecular, structural, physiological and patho-physiological studies. These studies have set the stage for rational drug design to combat disorders of the central nervous system. The studies also exemplify the cautious approach needed in developing CNS therapies and the importance of physiology in tempering drug design.

New Inhibitors of Glycogen Phosphorylase as Potential Antidiabetic Agents by L. Somsak, K. Czifrak, M. Toth, E. Bokor, E. Chrysina, K.-M. Alexacou, J. Hayes, C. Tiraidis, E. Lazoura, D. Leonidas, S. Zographos, N. Oikonomakos (2933-2983).
The protein glycogen phosphorylase has been linked to type 2 diabetes, indicating the importance of this target to human health. Hence, the search for potent and selective inhibitors of this enzyme, which may lead to antihyperglycaemic drugs, has received particular attention. Glycogen phosphorylase is a typical allosteric protein with five different ligand binding sites, thus offering multiple opportunities for modulation of enzyme activity. The present survey is focused on recent new molecules, potential inhibitors of the enzyme. The biological activity can be modified by these molecules through direct binding, allosteric effects or other structural changes. Progress in our understanding of the mechanism of action of these inhibitors has been made by the determination of high-resolution enzyme inhibitor structures (both muscle and liver). The knowledge of the three-dimensional structures of protein-ligand complexes allows analysis of how the ligands interact with the target and has the potential to facilitate structure-based drug design. In this review, the synthesis, structure determination and computational studies of the most recent inhibitors of glycogen phosphorylase at the different binding sites are presented and analyzed.

Targeting Vascular Niche by Parathyroid Hormone by Caterina Pagliarulo, Paola Salvatore, Claudio Napoli (2984-2990).
Currently, the parathyroid hormone (PTH) is a drug approved for use in humans only in bone metabolism diseases, as the osteoporosis. The PTH acts primarily by binding to its principal receptor, PTH/PTHrP-R, a member of the class B G protein-coupled receptor (GPCR) family that includes together receptors for other therapeutically important peptide hormones. PTH plays a central role in the maintenance of calcium and phosphate homeostasis and bone health. It acts to maintain bone and mineral homeostasis through several mechanisms: elevation of blood calcium by increasing osteoclastic bone resorption; enhancement of renal calcium reabsorption; stimulation of renal 1,25-dihydroxyvitamin D synthesis, leading to increased intestinal calcium absorption; and promotion of phosphaturia via inhibition of renal tubular transepithelial phosphate reabsorption . However, many findings indicate that the PTH could be a future drug essential in therapy of cardiovascular diseases through multiple effects on hematopoietic stem cells niche. In adult bone marrow, the hamatopoietic stem cells are located in the trabecular endosteum (osteoblastic niche) or sinusoidal perivascular areas (vascular niche). A plausible function for the vascular niche is to assist hematopoietic stem cells in transendothelial migration, which is important during both homing and mobilization. Indeed, in experimental models, PTH treatment increases migration of angiogenic CD45+/CD34+ progenitor cells to the hindlimb ischemia as well as in the ischemic heart, promoting tissue repair by enhanced neovascularization and cell survival.

Metabolic-Inflammatory Changes, and Accelerated Atherosclerosis in HIV Patients: Rationale for Preventative Measures by F. De Lorenzo, S. Collot-Teixeira, M. Boffito, M. Feher, B. Gazzard, J. McGregor (2991-2999).
Human immunodeficiency virus (HIV)-infected patients are at a significantly higher risk from coronary heart diseases (CHD) and myocardial infarction (MI) compared to gender- and age-matched non-infected individuals. Combination antiretroviral therapy (cART) has transformed a fatal illness into a chronic stable condition. However, cART induces metabolic abnormalities in HIV-infected patients, while its role in vascular atherosclerosis is still under investigation. The use of cART is linked to inflammation - a key mechanism in atherosclerotic progression and destabilisation that precedes clinical events like MI. There is evidence of visceral fat abnormal distribution in HIV infected patients, and inflammatory changes in HIV infected patients drive the initiation, progression and, ultimately, thrombotic clinical complications induced by atherosclerosis. Visceral adipose tissue, a virtual factory for manufacturing pro-inflammatory mediators, affects the liver function. The inflamed liver promotes the development of pro-atherogenic dyslipidaemia. Pro-inflammatory cytokines released by adipocytes travel to the skeletal muscles and other peripheral tissues, worsening insulin sensitivity and leading to hyperglycaemia. Increased high sensitivity C-reactive protein (hs-CRP) inflammatory marker is associated with endothelial dysfunction in HIV-infected patients. Increased levels of monocytic nuclear factor kappa-B (NFand#954;-B), a master switch in the inflammatory cascade, are documented in patients with elevated hs-CRP levels. It can be assumed that, as a result of NFand#954;-B activation, hs-CRP up-regulates cytokines that contribute to MI by recruiting leukocytes and promoting thrombosis. This review focuses on the association of HIV-infection, metabolic abnormalities and known mechanisms involved in inducing accelerated atherosclerosis and inflammation in HIV-infected patients, as well as the role of lipid lowering agents in potentially preventing CHD

Kawasaki's Disease, Acrodynia, and Mercury by J. Mutter, D. Yeter (3000-3010).
A superantigen or autoimmunity has been hypothesized to be the main cause of the Kawasaki's Disease but the etiology is unknown. Medical literature, epidemiological findings, and some case reports have suggested that mercury may play a pathogenic role. Several patients with Kawasaki's Disease have presented with elevated urine mercury levels compared to matched controls. Most symptoms and diagnostic criteria which are seen in children with acrodynia, known to be caused by mercury, are similar to those seen in Kawasaki's Disease. Genetic depletion of glutathione S-transferase , a susceptibility marker for Kawasaki's Disease, is known to be also a risk factor for acrodynia and may also increase susceptibility to mercury . Coinciding with the largest increase (1985-1990) of thimerosal (49.6and#x25; ethyl mercury) in vaccines, routinely given to infants in the U.S. by 6 months of age (from 75and#956;g to 187.5and#956;g), the rates of Kawasaki's Disease increased ten times, and, later (1985-1997), by 20 times. Since 1990 88 cases of patients developing Kawasaki's Disease some days after vaccination have been reported to the Centers of Disease Control (CDC) including 19and#x25; manifesting symptoms the same day. The presented pathogenetic model may lead to new preventive- and therapeutic strategies for Kawasaki's disease.

PPARγ and Early Human Placental Development by Thierry Fournier, Patrice Therond, Karen Handschuh, Vassilis Tsatsaris, Daniele Evain-Brion (3011-3024).
During pregnancy, the placenta ensures multiple functions, which are directly involved in the initiation, outcome of gestation and fetal growth. Human implantation involves a major invasion of the uterus wall and a complete remodeling of the uterine arteries by the extravillous cytotrophoblasts (EVCT) during the first trimester of pregnancy. Abnormality of these early steps of placental development leads to poor placentation, fetal growth defects and is very often associated with preeclampsia, a major and frequent complication of human pregnancy. Unexpectedly, genetic studies performed in mice established that the peroxisome proliferator-activated receptor-and#947; (PPARand#947;) is essential for placental development. In the human placenta, PPARand#947; is specifically expressed in the villous cytotrophoblast (VCT) and the syncytiotrophoblast (ST) as well as in the EVCT along their invasive pathway. To study the mechanisms that control human trophoblast invasion during early placental development and to provide new insight in the understanding of preeclampsia, we have developed in vitro models of human invasive trophoblasts. We observed that activation of the ligand-activated nuclear receptor PPARand#947; agonists inhibits the trophoblastic invasion process in a concentration-dependent manner. Analysis of PPARand#947;-target genes revealed that placental growth hormone, the protease PAPP-A and the human chorionic gonadotropin hormone (hCG) might be involved in the PPARand#947;-mediated effect in an autocrine manner. The presence of oxidized- LDLs at the maternofetal interface suggests that oxidized-LDLs from maternal sera might be a source of potential PPARand#947; ligands for the trophoblasts. Indeed, oxidized-LDLs decrease trophoblast invasion in vitro and analysis of their content revealed that they contain potent PPARand#947; agonists such as eicosanoids, but also oxysterols, which are ligands for another nuclear receptor, the liver X Receptor (LXR). LXRand#223; was found to be expressed in trophoblast and LXR agonists shown to inhibit trophoblast invasion. Together, these data underscore a major role for PPARand#947; in the control of human trophoblast invasion during early placental development and suggest that ligands such as oxidized-LDLs at the implantation site might contribute to the modulation of trophoblast invasion through activation of PPARand#947; and LXRand#223;, two nuclear receptors that modulate the human trophoblastic cell invasion process.