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Many Tissues (many + tissue)
Selected AbstractsHepatic tissue engineering for adjunct and temporary liver support: Critical technologiesLIVER TRANSPLANTATION, Issue 11 2004Christina Chan The severe donor liver shortage, high cost, and complexity of orthotopic liver transplantation have prompted the search for alternative treatment strategies for end-stage liver disease, which would require less donor material, be cheaper, and less invasive. Hepatic tissue engineering encompasses several approaches to develop adjunct internal liver support methods, such as hepatocyte transplantation and implantable hepatocyte-based devices, as well as temporary extracorporeal liver support techniques, such as bioartificial liver assist devices. Many tissue engineered liver support systems have passed the "proof of principle" test in preclinical and clinical studies; however, they have not yet been found sufficiently reliably effective for routine clinical use. In this review we describe, from an engineering perspective, the progress and remaining challenges that must be resolved in order to develop the next generation of implantable and extracorporeal devices for adjunct or temporary liver assist. (Liver Transpl 2004;10:1331,1342.) [source] Dlk1 expression marks developing endothelium and sites of branching morphogenesis in the mouse embryo and placentaDEVELOPMENTAL DYNAMICS, Issue 4 2006Aleksey Yevtodiyenko Abstract The protein product of the Delta-like 1 (Dlk1) gene belongs to the Delta-Notch family of signaling molecules, proteins involved in cell fate determination in many tissues during development. The DLK1 protein is believed to function as a growth factor, maintaining the proliferative state of undifferentiated cells, and is usually down-regulated as immature cells differentiate. The expression pattern of the DLK1 protein has been described in certain human tissues; however, Dlk1 expression is not well understood in the mouse, the most tractable mammalian genetic model system. To better understand the role of Dlk1 in embryonic development, the tissue-specific expression pattern of Dlk1 mRNA during mouse embryogenesis was analyzed by in situ hybridization. In embryonic day 12.5 (e12.5) embryos, high levels of Dlk1 were found in the developing pituitary, pancreas, lung, adrenal, and many mesodermally derived tissues. Strikingly, Dlk1 expression also marks the growing branches of organs that develop through the process of branching morphogenesis. At e16.5, Dlk1 expression is down-regulated in most tissues but remains in the pituitary, the adrenal gland, and in skeletal muscle. In the placenta, expression of Dlk1 is detected in endothelial cells lining the fetal blood vessels of the labyrinth. This pattern is distinct from that seen in the human placenta and suggests a role for Dlk1 in regulating maternal,fetal interactions. Developmental Dynamics 235:1115,1123, 2006. © 2006 Wiley-Liss, Inc. [source] Opposing effects on TSC-22 expression by BMP and receptor tyrosine kinase signals in the developing feather tractDEVELOPMENTAL DYNAMICS, Issue 1 2002Cord E. Dohrmann Abstract TSC-22 (transforming growth factor-,,stimulated clone 22) belongs to a family of leucine zipper transcription factors that includes sequences from invertebrates and vertebrates. The single Drosophila family member, encoded by the bunched gene, serves to integrate opposing bone morphogenic protein (BMP) and epidermal growth factor (EGF) signals during oogenesis. Similarly, mammalian TSC-22 expression is regulated by several families of secreted signaling molecules in cultured cells. Here, we show that chick TSC-22 is dynamically expressed in the condensing feather bud, as well as in many tissues of the chick embryo. BMP-2/4, previously shown to inhibit bud development, repress TSC-22 expression during feather bud formation in vivo. Noggin, a BMP antagonist, promotes TSC-22 expression. EGF, TGF-,, and fibroblast growth factor all promote both feather bud development and TSC-22 expression; each can promote ectopic feather buds that are regularly spaced between existing feather buds. Thus, TSC-22 is a candidate to integrate small imbalances in receptor tyrosine kinase and BMP signaling during feather tract development to generate stable and reproducible morphogenetic responses. © 2001 Wiley-Liss, Inc. [source] Metformin action on AMP-activated protein kinase: a translational research approach to understanding a potential new therapeutic targetDIABETIC MEDICINE, Issue 10 2010J. G. Boyle Diabet. Med. 27, 1097,1106 (2010) Abstract Clinical studies in Type 2 diabetes mellitus have shown that the effects of metformin go beyond improving HbA1c and include reductions in cardiovascular endpoints. Metformin therapy has been widely used in the treatment of Type 2 diabetes for many years, yet the precise mode of action remains uncertain. It has recently been proposed that metformin-mediated stimulation of hepatic AMP-activated protein kinase (AMPK) underlies the hypoglycaemic effects of metformin. AMPK is a heterotrimeric enzyme that is expressed in many tissues and plays a central role in the regulation of energy homoeostasis. Furthermore, there is increasing evidence that AMPK is implicated in the pathophysiology of cardiovascular and metabolic diseases. The generation of more specific and potent activators of AMPK, however, could have additional metabolic and vascular benefits for patients with Type 2 diabetes. [source] Upregulation of Brain Expression of P-Glycoprotein in MRP2-deficient TR - Rats Resembles Seizure-induced Up-regulation of This Drug Efflux Transporter in Normal RatsEPILEPSIA, Issue 4 2007Katrin Hoffmann Summary:,Purpose: The multidrug resistance protein 2 (MRP2) is a drug efflux transporter that is expressed predominantly at the apical domain of hepatocytes but seems also to be expressed at the apical membrane of brain capillary endothelial cells that form the blood,brain barrier (BBB). MRP2 is absent in the transport-deficient (TR,) Wistar rat mutant, so that this rat strain was very helpful in defining substrates of MRP2 by comparing tissue concentrations or functional activities of compounds in MRP2-deficient rats with those in transport-competent Wistar rats. By using this strategy to study the involvement of MRP2 in brain access of antiepileptic drugs (AEDs), we recently reported that phenytoin is a substrate for MRP2 in the BBB. However, one drawback of such studies in genetically deficient rats is the fact that compensatory changes with upregulation of other transporters can occur. This prompted us to study the brain expression of P-glycoprotein (Pgp), a major drug efflux transporter in many tissues, including the BBB, in TR, rats compared with nonmutant (wild-type) Wistar rats. Methods: The expression of MRP2 and Pgp in brain and liver sections of TR, rats and normal Wistar rats was determined with immunohistochemistry, by using a novel, highly selective monoclonal MRP2 antibody and the monoclonal Pgp antibody C219, respectively. Results: Immunofluorescence staining with the MRP2 antibody was found to label a high number of microvessels throughout the brain in normal Wistar rats, whereas such labeling was absent in TR, rats. TR, rats exhibited a significant up-regulation of Pgp in brain capillary endothelial cells compared with wild-type controls. No such obvious upregulation of Pgp was observed in liver sections. A comparable overexpression of Pgp in the BBB was obtained after pilocarpine-induced seizures in wild-type Wistar rats. Experiments with systemic administration of the Pgp substrate phenobarbital and the selective Pgp inhibitor tariquidar in TR, rats substantiated that Pgp is functional and compensates for the lack of MRP2 in the BBB. Conclusions: The data on TR, rats indicate that Pgp plays an important role in the compensation of MRP2 deficiency in the BBB. Because such a compensatory mechanism most likely occurs to reduce injury to the brain from cytotoxic compounds, the present data substantiate the concept that MRP2 performs a protective role in the BBB. Furthermore, our data suggest that TR, rats are an interesting tool to study consequences of overexpression of Pgp in the BBB on access of drugs in the brain, without the need of inducing seizures or other Pgp-enhancing events for this purpose. [source] The analysis of the fine specificity of celiac disease antibodies using tissue transglutaminase fragmentsFEBS JOURNAL, Issue 21 2002Daniele Sblattero Celiac disease is an intestinal malabsorption characterized by an intolerance to cereal proteins accompanied by immunological responses to dietary gliadins and an autoantigen located in the endomysium. The latter has been identified as the enzyme tissue transglutaminase which belongs to a family of enzymes that catalyze protein cross-linking reactions and is constitutively expressed in many tissues as well as being activated during apoptosis. In a recent paper, we described the selection and characterization of anti-transglutaminase Igs from phage antibody libraries created from intestinal lymphocytes from celiac disease patients. In this work, using transglutaminase gene fragments, we identify a region of tissue transglutaminase recognized by these antibodies as being conformational and located in the core domain of the enzyme. This is identical to the region recognized by anti-transglutaminase Igs found in the serum of celiac disease patients. [source] Nuclear factor-kappaB as a molecular target for migraine therapy.HEADACHE, Issue 4 2003U Reuter Ann Neurol. 2002;51:507-516. Nitric oxide (NO) generated from inducible NO synthase (iNOS) participates in immune and inflammatory responses in many tissues. The NO donor glyceryl trinitrate (GTN) provokes delayed migraine attacks when infused into migraineurs and also causes iNOS expression and delayed inflammation within rodent dura mater. Sodium nitroprusside, an NO donor as well, also increases iNOS expression. Because inflammation and iNOS are potential therapeutic targets, we examined transcriptional regulation of iNOS following GTN infusion and the consequences of its inhibition within dura mater. We show that intravenous GTN increases NO production within macrophages. L-N(6)-(1-iminoethyl)lysine, a selective iNOS inhibitor, attenuates the NO signal, emphasizing the importance of enzymatic activity to delayed NO production. iNOS expression is preceded by significant nuclear factor kappa B (NF-kappaB) activity, as reflected by a reduction in the inhibitory protein-kappa-Balpha (IkappaBalpha) and activation of NF-kappaB after GTN infusion. IkappaBalpha degradation, NF-kappaB activation, and iNOS expression were attenuated by parthenolide (3mg/kg), the active constituent of feverfew, an anti-inflammatory drug used for migraine treatment. These findings suggest that GTN promotes NF-kappaB activity and inflammation with a time course consistent with migraine attacks in susceptible individuals. We conclude, based on results with this animal model, that blockade of NF-kappaB activity provides a novel transcriptional target for the development of anti-migraine drugs. Comment: This paper suggesting the localization of NO production in dural macrophages as part of delayed inflammation may indicate proliferation and or recruitment of these cells in migraine. Could this also be a target for drug treatment? Specifically, is the genetic transcription that leads to nitric oxide generation such a target? To amend slightly the old advertising slogan, "when Michael Moskowitz talks, we all listen." DSM and SJT [source] Adiponectin protects LPS-induced liver injury through modulation of TNF-, in KK-Ay obese miceHEPATOLOGY, Issue 1 2004Takayuki Masaki Adiponectin, an adipocytokine, has been identified in adipose tissue, and its receptors are widely distributed in many tissues, including the liver. The present study was performed to clarify the role of adiponectin in lipopolysaccharide (LPS)-induced liver injury using KK-Ay obese mice. We analyzed the effects of adiponectin pretreatment on liver injury induced by D -galactosamine/LPS (GalN/LPS) in KK-Ay obese mice. GalN/LPS treatment induced significant increases in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in the blood, apoptotic and necrotic changes in hepatocytes, and/or showed a high degree of lethality. The GalN/LPS-induced liver injury was more pronounced in KK-Ay obese mice than in lean controls. Pretreatment with adiponectin ameliorated the GalN/LPS-induced elevation of serum AST and ALT levels and the apoptotic and necrotic changes in hepatocytes, resulting in a reduction in lethality. In addition, pretreatment with adiponectin attenuated the GalN/LPS-induced increases in serum and hepatic tumor necrosis factor , (TNF-,) levels and increased peroxisome proliferator-activated receptor (PPAR) , messenger RNA expression in the liver. Furthermore, abdominal macrophages from KK-Ay obese mice pretreated with adiponectin in vitro exhibited decreased LPS-induced TNF-, production compared with controls. Finally, adiponectin pretreatment also ameliorated TNF-,-induced liver injury. In conclusion, these findings suggest that adiponectin prevents LPS-induced hepatic injury by inhibiting the synthesis and/or release of TNF-, of KK-Ay obese mice. (HEPATOLOGY 2004;40:177,184.) [source] The CAG repeat polymorphism within the androgen receptor gene and maleness,INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2003Michael Zitzmann Summary The androgen testosterone and its metabolite dihydrotestosterone exert their effects on gene expression and thus effect maleness via the androgen receptor (AR). A diverse range of clinical conditions starting with complete androgen insensitivity has been correlated with mutations in the AR. Subtle modulations of the transcriptional activity induced by the AR have also been observed and frequently assigned to a polyglutamine stretch of variable length within the N-terminal domain of the receptor. This stretch is encoded by a variable number of CAG triplets in exon 1 of the AR gene located on the X chromosome. First observations of pathologically elongated AR CAG repeats in patients with X-linked spino-bulbar muscular atrophy showing marked hypoandrogenic traits were supplemented by partially conflicting findings of statistical significance also within the normal range of CAG repeat length: an involvement of prostate tissue, spermatogenesis, bone density, hair growth, cardiovascular risk factors and psychological factors has been demonstrated. The highly polymorphic nature of glutamine residues within the AR protein implies a subtle gradation of androgenicity among individuals within an environment of normal testosterone levels providing relevant ligand binding to ARs. This modulation of androgen effects may be small but continuously present during a man's lifetime and, hence, exerts effects that are measurable in many tissues as various degrees of androgenicity and represents a relevant effector of maleness. It remains to be elucidated whether these insights are important enough to become part of individually useful laboratory assessments. [source] Exclusive expression of a membrane-bound Spink3-interacting serine protease-like protein TESPL in mouse testisJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2010Chung-Mao Ou Abstract We identified a testis-specific protease-like protein tentatively named TESPL and a pancreatic trypsinogen Prss2 from the clones of a yeast two-hybrid screen against a mouse testicular cDNA library using the trypsin inhibitor Spink3 from male accessory sexual glands as bait. The enzymatic motifs and the cysteine patterns in serine proteases are highly conserved in these two proteins. Based on the phylogenetic analysis, Prss2 duplicated recently and TESPL underwent distant evolution without gene duplication from the progenitor of trypsin-like and chymotrypsin-like proteases. We found that TESPL transcription was restricted to the testis and that the level of transcription was positively correlated with animal maturation. In contrast, Prss2 was constitutively expressed in many tissues including testis. Alignment of the cDNA-deduced sequences of serine proteases showed the replacement of an essential serine residue in the catalytic triad of serine proteases by a proline residue in TESPL, which was demonstrated to be a membrane-bound protein devoid of proteolytic activity. The immunohistochemical staining patterns of seminiferous tubules in the testis revealed TESPL mainly on postmeiotic cells such as spermatids and spermatozoa. On the mouse sperm from caudal epididymis, TESPL was localized mainly on the plasma membrane overlaying the acrosomal region. Further, orthology group for mouse TESPL was identified in the conserved gene family of eutherian testis serine protease 5. J. Cell. Biochem. 110: 620,629, 2010. © 2010 Wiley-Liss, Inc. [source] Annulus cells release ATP in response to vibratory loading in vitroJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2003Satoru Yamazaki Abstract Mechanical forces regulate the developmental path and phenotype of a variety of tissues and cultured cells. Vibratory loading as a mechanical stimulus occurs in connective tissues due to energy returned from ground reaction forces, as well as a mechanical input from use of motorized tools and vehicles. Structures in the spine may be particularly at risk when exposed to destructive vibratory stimuli. Cells from many tissues respond to mechanical stimuli, such as fluid flow, by increasing intracellular calcium concentration ([Ca2+]ic) and releasing adenosine 5,-triphosphate (ATP), extracellularly, as a mediator to activate signaling pathways. Therefore, we examined whether ATP is released from rabbit (rAN) and human (hAN) intervertebral disc annulus cells in response to vibratory loading. ATP release from annulus cells by vibratory stimulation as well as in control cells was quantitated using a firefly luciferin-luciferase assay. Cultured hAN and rAN cells had a basal level of extracellular ATP ([ATP]ec) in the range of 1,1.5 nM. Vibratory loading of hAN cells stimulated ATP release, reaching a net maximum [ATP] within 10 min of continuous vibration, and shortly thereafter, [ATP] declined and returned to below baseline level. [ATP] in the supernatant fluid of hAN cells was significantly reduced compared to the control level when the cells received vibration for longer than 15 min. In rAN cells, [ATP] was increased in response to vibratory loading, attaining a level significantly greater than that of the control after 30 min of continuous vibration. Results of the current study show that resting annulus cells secrete ATP and maintain a basal [ATP]ec. Annulus cells may use this nucleotide as a signaling messenger in an autocrine/paracrine fashion in response to vibratory loading. Rapid degradation of ATP to ADP may alternatively modulate cellular responses. It is hypothesized that exposure to repetitive, complex vibration regimens may activate signaling pathways that regulate matrix destruction in the disc. As in tendon cells, ATP may block subsequent responses to load and modulate the vibration response. Rabbit annulus cells were used as a readily obtainable source of cells in development of an animal model for testing effects of vibration on the disc. Human cells obtained from discarded surgical specimens were used to correlate responses of animal to human cells. © 2003 Wiley-Liss, Inc. [source] Hot topics in stem cells and self-renewal: 2010AGING CELL, Issue 4 2010Norman E. Sharpless Summary In many tissues, mammalian aging is associated with a decline in the replicative and functional capacity of somatic stem cells and other self-renewing compartments. Understanding the basis of this decline is a major goal of aging research. In particular, therapeutic approaches to ameliorate or reverse the age-associated loss of stem function could be of use in clinical geriatrics. Such approaches include attempts to protect stem cells from age-promoting damage, to ,rejuvenate' stem cells through the use of pharmacologic agents that mitigate aging-induced alterations in signaling, and to replace lost stem cells through regenerative medicine approaches. Some headway has been made in each of these arenas over the last 18 months including advances in the production of donor-specific totipotent stem cells through induced pluripotency (iPS), gains in our understanding of how tumor suppressor signaling is controlled in self-renewing compartments to regulate aging, and further demonstration of extracellular ,milieu' factors that perturb stem cell function with age. This period has also been marked by the recent award of the Nobel Prize in Physiology or Medicine for elucidation of telomeres and telomerase, a topic of critical importance to stem cell aging. [source] Magnetic resonance imaging of entheses using ultrashort TE (UTE) pulse sequencesJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2007Michael Benjamin PhD Abstract The attachment of tendons, ligaments, and joint capsule to bone (entheses) is reviewed and new options for visualizing key components of entheses provided by ultrashort TE (UTE) pulse sequences are described. Many features of entheses are adapted to the dispersion of stress at the boundary between tendons/ligaments and bone. Of particular interest is fibrocartilage, which has mechanical properties different from those of both "pure" tendon/ligament and bone. Features typical of entheses can also be seen at sites where tendons or ligaments are in contact with (but not attached to) bone, and the concept of a "functional enthesis" has been developed to emphasize the similarities. The enthesis concept has also been broadened to include the idea of an "enthesis organ" in which many tissues play a role in dissipating stress concentration. UTE pulse sequences can specifically identify the calcified and uncalcified fibrocartilage tissue components of entheses and differentiate these from fibrous connective tissue and bone. These tissues cannot be separately visualized at entheses with conventional pulse sequences. Entheses are involved in overuse syndromes and seronegative spondyloarthropathies (SpA) and there are important issues related to tissue repair and healing following surgery. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc. [source] Agonists specific for the transcription factor PPARdelta accelerate differentiation of oligodendrocytesJOURNAL OF NEUROCHEMISTRY, Issue 2002R. P. Skoff Peroxisome proliferator activated receptors (PPARs) are transcription factors belonging to the nuclear hormone receptor superfamily that regulate key genes involved in lipid metabolism. PPAR, is ubiquitously expressed at low levels in many tissues and its function has remained elusive. However, we have shown that PPAR, is abundantly expressed in oligodendrocytes (Ols), suggesting this receptor plays a critical role in oligodendrocyte differentiation (Granneman et al. 1998 J. Neurosci. Res51, 563). We first investigated the effects of PPAR agonists on proliferation and differentiation of Ols in tissue culture. Primary glial and enriched Ol cultures were treated with ligands that specifically activate PPAR, and PPAR, (Berger et al. 1999 J. Biol. Chem. 274, 6717). PPAR, but not PPAR, agonists increased the size of OL membrane sheets within 24 h of application. The increase in membrane sheet size was mirrored by increases in MBP and PLP mRNA's. In enriched Ol cultures, the number of Ols was increased 70% with the PPAR, agonist but not the PPAR, agonist (Saluja et al. 2001 Glia33, 191). In vivo injections of PPAR, agonist into P2 and P3 mice show an increase of total macroglia in the ventral and dorsal funiculi of the spinal cord of 20,40% compared to controls. Preliminary observations suggest the Ols in agonist treated cultures are larger and more densely stained than controls. Our results show for the first time that a specific ligand for a transcription factor is capable of activating the program of Ol differentiation. Acknowledgements: Supported by NMSS. [source] Ethanol Decreases Rat Hepatic Arylsulfatase A Activity LevelsALCOHOLISM, Issue 11 2006Smith Jean Background: Arylsulfatase A (ASA) is an enzyme that catalyzes the degradation of sulfatides, a glycosphingolipid found in many tissues, but predominantly in myelin and kidney. Arylsulfatase A is 1 member of a family of sulfatases that is activated by a required co- or posttranslational modification with the oxidation of cysteine to formylglycine. This conversion requires a novel oxygenase mechanism that can be inhibited by reactive oxygen species. Ethanol is known to cause an increase in reactive oxygen species in the liver. Because of its effect on the levels of hepatic reactive oxygen species, we hypothesized that ethanol would cause a specific decrease of rat hepatic ASA activity levels. Methods: Male Sprague,Dawley rats received ethanol-containing, Lieber,DeCarli liquid diets for 15 days, and control rats were pair-fed a liquid diet in which dextrose was isocalorically substituted for ethanol. Results: Arylsulfatase A activity levels decreased in livers of animals receiving alcohol compared with control animals. No significant changes in ASA activity levels were observed in the cerebral cortex and kidney. Furthermore, ethanol did not have any significant effect on hexosaminidase activity in any of the tissues examined. Conclusion: Ethanol caused a tissue-specific decrease in hepatic ASA activity levels, but not hexosaminidase activity levels. [source] Principles of pharmacodynamics and their applications in veterinary pharmacologyJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2004P. LEES Pharmacodynamics (PDs) is the science of drug action on the body or on microorganisms and other parasites within or on the body. It may be studied at many organizational levels , sub-molecular, molecular, cellular, tissue/organ and whole body , using in vivo, ex vivo and in vitro methods and utilizing a wide range of techniques. A few drugs owe their PD properties to some physico-chemical property or action and, in such cases, detailed molecular drug structure plays little or no role in the response elicited. For the great majority of drugs, however, action on the body is crucially dependent on chemical structure, so that a very small change, e.g. substitution of a proton by a methyl group, can markedly alter the potency of the drug, even to the point of loss of activity. In the late 19th century and first half of the 20th century recognition of these facts by Langley, Ehrlich, Dale, Clarke and others provided the foundation for the receptor site hypothesis of drug action. According to these early ideas the drug, in order to elicit its effect, had to first combine with a specific ,target molecule' on either the cell surface or an intracellular organelle. It was soon realized that the ,right' chemical structure was required for drug,target site interaction (and the subsequent pharmacological response). In addition, from this requirement, for specificity of chemical structure requirement, developed not only the modern science of pharmacology but also that of toxicology. In relation to drug actions on microbes and parasites, for example, the early work of Ehrlich led to the introduction of molecules selectively toxic for them and relatively safe for the animal host. In the whole animal drugs may act on many target molecules in many tissues. These actions may lead to primary responses which, in turn, may induce secondary responses, that may either enhance or diminish the primary response. Therefore, it is common to investigate drug pharmacodynamics (PDs) in the first instance at molecular, cellular and tissue levels in vitro, so that the primary effects can be better understood without interference from the complexities involved in whole animal studies. When a drug, hormone or neurotransmitter combines with a target molecule, it is described as a ligand. Ligands are classified into two groups, agonists (which initiate a chain of reactions leading, usually via the release or formation of secondary messengers, to the response) and antagonists (which fail to initiate the transduction pathways but nevertheless compete with agonists for occupancy of receptor sites and thereby inhibit their actions). The parameters which characterize drug receptor interaction are affinity, efficacy, potency and sensitivity, each of which can be elucidated quantitatively for a particular drug acting on a particular receptor in a particular tissue. The most fundamental objective of PDs is to use the derived numerical values for these parameters to classify and sub-classify receptors and to compare and classify drugs on the basis of their affinity, efficacy, potency and sensitivity. This review introduces and summarizes the principles of PDs and illustrates them with examples drawn from both basic and veterinary pharmacology. Drugs acting on adrenoceptors and cardiovascular, non-steroidal anti-inflammatory and antimicrobial drugs are considered briefly to provide a foundation for subsequent reviews in this issue which deal with pharmacokinetic (PK),PD modelling and integration of these drug classes. Drug action on receptors has many features in common with enzyme kinetics and gas adsorption onto surfaces, as defined by Michaelis,Menten and Langmuir absorption equations, respectively. These and other derived equations are outlined in this review. There is, however, no single theory which adequately explains all aspects of drug,receptor interaction. The early ,occupation' and ,rate' theories each explain some, but not all, experimental observations. From these basic theories the operational model and the two-state theory have been developed. For a discussion of more advanced theories see Kenakin (1997). [source] Hypoxia-inducible factor-1 alpha and vascular endothelial growth factor expression in ischaemic colitis and ulcerative colitisALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 2006T. OKUDA Summary Background Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is a transcriptional factor induced by ischaemic crisis in many tissues. Vascular endothelial growth factor (VEGF) is an important growth factor that plays a major role in angiogenesis. Aim We examined the aetiology and pathophysiology of human ischaemic colitis and ulcerative colitis from the viewpoint of the expression of these two ischaemic factors. Methods Thirty-two patients with ischaemic colitis, 16 with ulcerative colitis and 25 normal controls underwent colonoscopy. Biopsy samples were taken from a colitis lesion and a normal region in the same patient. In the normal controls, four biopsy samples were obtained from each subject. Biopsy samples were subjected to real-time polymerase chain reaction. Results Hypoxia-inducible factor and VEGF were overexpressed in ischaemic colitis lesions and quickly decreased to normal levels in the healing phase. In contrast, HIF but not VEGF was overexpressed in active ulcerative colitis lesions. In the remission phase of ulcerative colitis, VEGF decreased to low levels, although HIF was continuously overexpressed. Conclusions Overexpression of HIF and VEGF contribute to the tolerance of ischaemia in patients with active ischaemic colitis. The inconsistency in their expression might be associated with the chronic intestinal damage characteristic of ulcerative colitis. [source] Electrospun Alginate Nanofibers with Controlled Cell Adhesion for Tissue Engineering,MACROMOLECULAR BIOSCIENCE, Issue 8 2010Sung In Jeong Abstract Alginate, a natural polysaccharide that has shown great potential as a cell scaffold for the regeneration of many tissues, has only been nominally explored as an electrospun biomaterial due to cytotoxic chemicals that have typically been used during nanofiber formation and crosslinking. Alginate cannot be electrospun by itself and is often co-spun with poly(ethylene oxide) (PEO). In this work, a cell adhesive peptide (GRGDSP) modified alginate (RA) and unmodified alginate (UA) were blended with PEO at different concentrations and blending ratios, and then electrospun to prepare uniform nanofibers. The ability of electrospun RA scaffolds to support human dermal fibroblast cell attachment, spreading, and subsequent proliferation was greatly enhanced on the adhesion ligand-modified nanofibers, demonstrating the promise of this electrospun polysaccharide material with defined nanoscale architecture and cell adhesive properties for tissue regeneration applications. [source] Restricted transgene persistence after lentiviral vector-mediated fetal gene transfer in the pregnant rabbit modelTHE JOURNAL OF GENE MEDICINE, Issue 9 2008Rafael Moreno Abstract Background Prenatal gene transfer may enable early causal intervention for the treatment or prevention of many devastating diseases. Nevertheless, permanent correction of most inherited disorders requires a sustained level of expression from the therapeutic transgene, which could theoretically be achieved with integrating vectors. Methods Rabbit fetuses received 8.5 × 106 HIV-based recombinant lentivirus particles containing the enhanced green fluorescent protein (EGFP) transgene by intrahepatic, intra-amniotic or intraperitoneal injection at 22 days of gestation. Provirus presence and transgene expression in rabbit tissues were evaluated at both 1.5 and 16 weeks post- in utero intervention by polymerase chain reaction (PCR) and reverse transcriptase-PCR, respectively. Moreover, we assessed persistence of EGFP by immunohistochemistry. Enzyme-linked immunosorbent assays confirmed the development of antibodies specific against both the viral vector and the reporter protein. Results Regardless of the route of administration employed, lentiviral vector-based in utero gene transfer was safe and reached 85% of the intervened fetuses at birth. However, the integrated provirus frequency was significantly reduced to 50% of that in young rabbits at 16 weeks post-treatment. In these animals, EGFP expression was evident in many tissues, including cytokeratin 5-rich basal cells from stratified and pseudostratified epithelia, suggesting that the lentiviral vector might have reached progenitor cells. Conversely, we identified the presence of immune-inflammatory infiltrates in several EGFP-expressing tissues. Moreover, almost 70% of the lentiviral vector-treated rabbits elicited a humoral immune response against the viral envelope and/or the EGFP. Conclusions At two-thirds gestational age, the adaptive immune system of the rabbit appears a relevant factor limiting transgene persistence and expression following lentiviral vector-mediated in utero gene transfer. Copyright © 2008 John Wiley & Sons, Ltd. [source] RNA-mediated neurodegeneration in repeat expansion disordersANNALS OF NEUROLOGY, Issue 3 2010Peter K. Todd MD Most neurodegenerative disorders are thought to result primarily from the accumulation of misfolded proteins, which interfere with protein homeostasis in neurons. For a subset of diseases, however, noncoding regions of RNAs assume a primary toxic gain-of-function, leading to degeneration in many tissues, including the nervous system. Here we review a series of proposed mechanisms by which noncoding repeat expansions give rise to nervous system degeneration and dysfunction. These mechanisms include transcriptional alterations and the generation of antisense transcripts, sequestration of mRNA-associated protein complexes that lead to aberrant mRNA splicing and processing, and alterations in cellular processes, including activation of abnormal signaling cascades and failure of protein quality control pathways. We place these potential mechanisms in the context of known RNA-mediated disorders, including the myotonic dystrophies and fragile X tremor ataxia syndrome, and discuss recent results suggesting that mRNA toxicity may also play a role in some presumably protein-mediated neurodegenerative disorders. Lastly, we comment on recent progress in therapeutic development for these RNA-dominant diseases. ANN NEUROL 2010;67:291,300 [source] Crystallization and preliminary X-ray crystallographic studies of human FAIM proteinACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2010Guoming Li Fas apoptosis inhibitory molecule (FAIM), an antagonist of Fas-induced cell death, is highly conserved and is broadly expressed in many tissues. It has been found that FAIM can stimulate neurite outgrowth in PC12 cells and primary neurons. However, the molecular mechanisms of action of FAIM are not understood in detail. Here, full-length human FAIM and two truncation constructs have successfully been cloned, expressed and purified in Escherichia coli. FAIM (1,90) was crystallized and diffracted to a resolution of 2.5,Å; the crystal belonged to space group P31, with unit-cell parameters a = b = 58.02, c = 71.11,Å, , = , = 90, , = 120°. There were two molecules in the asymmetric unit. [source] Auraptene, a citrus fruit compound, regulates gene expression as a PPAR, agonist in HepG2 hepatocytesBIOFACTORS, Issue 1 2008Nobuyuki Takahashi Abstract Citrus fruit compounds have various activities that improve pathological conditions in many tissues. In this study, we examined the effect of auraptene contained mainly in the peel of citrus on peroxisome proliferator-activated receptor-, (PPAR,) activation. To examine effects of auraptene on the PPAR, activation in hepatocytes, PPAR ligand assay system was developed using HepG2 hepatocytes, in which the endogenous PPAR, expression level is very low. In the PPAR ligand assay, the addition of auraptene showed significant effects on the transactivation of GAL4/PPAR, chimera proteins in a dose-dependent manner. Actually, treatment with auraptene induced the up-regulation of PPAR target genes, such as acyl-CoA oxidase (ACO), carnitine-palmitoyl transferase 1A (CPT1A) and acyl-CoA synthetase (ACS), in PPAR,-expressing HepG2 hepatocytes. The regulation of gene expression was dependent on PPAR, because mock-transfected HepG2 hepatocytes showed no regulation. The up-regulation of PPAR target gene expression by auraptene was sufficient to enhance oleic acid uptake into PPAR,-expressing HepG2 hepatocytes. These results indicate that auraptene acts as a PPAR, agonist in hepatocytes and that auraptene may improve lipid abnormality through PPAR, activation in the liver. [source] Die vielen Seiten des Sulfids.BIOLOGIE IN UNSERER ZEIT (BIUZ), Issue 5 2009Tödlich und doch lebensnotwendig Abstract Schwefelwasserstoff ist äußerst giftig und hat dennoch zahlreiche physiologische Funktionen. Tiere aus sulfidhaltigen Lebensräumen können sich effektiv vor einer Sulfidvergiftung schützen und nutzen diese reduzierte Schwefelverbindung sogar als Energielieferant. Das reichhaltige Leben an den Hydrothermalquellen der Tiefsee basiert vollständig auf der Oxidation anorganischer Substanzen, wobei Sulfid eines der Hauptsubstrate ist. Für den Menschen spielt Sulfid als gasförmiges Signalmolekül eine wichtige Rolle. Es wird in vielen Geweben produziert und ist an einigen entscheidenden Stoffwechselvorgängen, wie beispielsweise der Regulation des Blutdrucks und der Insulinsekretion beteiligt. Störungen des Schwefelstoffwechsels führen zu verschiedenen Erkrankungen, so dass die genaue Kenntnis der Umsetzung und Wirkungsweisen von Sulfid medizinisch von großem Interesse ist. Hydrogen sulfide is highly toxic, but nevertheless it has several physiological functions. Animals from sulfide containing habitats are able to protect themselves from sulfide poisoning and furthermore use this reduced sulfur compound for ATP production. Life at the deep-sea hydrothermal vents entirely depends on the oxidation of inorganic substrates, mainly sulfide. In humans sulfide acts as a gaseous signalling molecule. It is produced in many tissues and takes part in a number of important metabolic processes such as the regulation of blood pressure and insulin secretion. Several severe diseases are caused by dysfunctions in sulfur metabolism. Thus, a detailed knowledge of the reactions and effects of hydrogen sulfide is of considerable clinical relevance. [source] | ||||||||||||||||