The Roles of Guanine Nucleotide Binding Proteins in Health and Disease

G-proteins are important mediators of cellular and tissue functions and are characterised by a recognition site for Guanine Triphosphate (GTP), Guanine Diphosphate (GDP) and possess intrinsic GTPase activity. They play important roles in signal transduction responsible for cytoskeletal remodelling, cellular differentiation and vesicular transport. They are made up of three types namely, the small G-proteins, the sensors and the heterotrimeric G-proteins. The G-protein heterotrimers consist of G-alpha (G), G-beta (G$) and G-gamma (G() subunits. Each heterotrimeric G-protein have different subunits and the combination of these subunits define the specific role of each G-protein. The activation of G subunits regulates the activity of effector enzymes and ion channels while G$( subunits function in the regulation of mitogen-activated protein kinase (MAP-kinase) pathway. The G-protein-mediated signal transduction is important in the regulation of a cells morphological and physiological response to external stimuli. MAPKs are involved in the phosphorylation of transcription factors that stimulate gene transcription. Gs stimulates adenylate cyclase, thereby increasing cyclic adenosine monophosphate (cAMP) leading to the phosphorylation and subsequent activation of Ca_+ channels. G proteins are involved in disease pathology through several mechanisms which interfere with the G protein activity. Other disease pathologies associated with abnormal mutations in G proteins can interfere with signal transduction pathways which may involve signal transmission that is either excessive, by augmentation of G protein function, or insufficient, via inactivation of G proteins.sch_dieBenians, A., M. Nobles, S. Hosny and A. Tinker, 2005. Regulators of G-protein signalling form a quaternary complex with the agonist, receptor, and G-protein. 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Heterotrimeric G proteins. Curr. Opin. Cell Biol., 8(2): 189-196. Hepler, J.R. and A.G. Gilman, 1992. G proteins. Trend. Biochem. Sci., 17(10): 383-387. Howe, L.R. and C.J. Marshall, 1993. Lysophosphatidic acid stimulates mitogen-activated protein kinase activation via a G-protein-coupled pathway requiring p21ras and p74raf-1. J. Biol. Chem., 268(28): 20717-20720. Jiang, M., M.S. Gold, G. Boulay, K. Spicher, M. Peyton, P. Brabet, Y. Srinivasan, U. Rudolph, G. Ellison and L. Birnbaumer, 1998. Multiple neurological abnormalities in mice deficient in the G protein Go. Proc. Natl. Acad. Sci. USA, 95(6): 3269-3274. Kaziro, Y., H. Itoh, T. Kozasa, M. Nakafuku and T. Satoh, 1991. Structure and function of signaltransducing GTP-binding proteins. Annu. Rev. Biochem., 60: 349-400. Kitanaka, N., J. Kitanaka, F.S. Hall, T. Tatsuta, Y. Morita, M. Takemura, X.B. Wang and G.R. Uhl, 2008. Alterations in the levels of heterotrimeric G protein subunits induced by psychostimulants, opiates, barbiturates, and ethanol: Implications for drug dependence, tolerance, and withdrawal. Synapse, 62(9): 689-699. Kolch, W., G. Heidecker, G. Kochs, R. Hummel, H. Vahidi, H. Mischak, G. Finkenzeller, D. Marme and U.R. Rapp, 1993. Protein kinase C alpha activates RAF-1 by direct phosphorylation. Nature, 364(6434): 249-252. Levitzki, A., 1990. GTP-GDP exchange proteins. Science, 248(4957): 794. Lorenz, S., R. Frenzel, R. Paschke, G.E. Breitwieser and S.U. Miedlich, 2007. Functional desensitization of the extracellular calcium-sensing receptor is regulated via distinct mechanisms: Role of G proteincoupled receptor kinases, protein kinase C and {$}- arrestins. Endocrinology, 148(5): 2398-2404. Lowes, V.L., N.Y. Ip and Y.H. Wong, 2002. Integration of signals from receptor tyrosine kinases and g protein-coupled receptors. Neurosignals, 11(1): 5-19. Luttrell, L.M., Y. Daaka, G.J. 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G protein interaction with K+ and Ca2+ channels. Trend. Pharmacol. Sci., 18(1): 8-11. Schrder, S. and M.J. Lohse, 1996. Inhibition of Gprotein betagamma-subunit functions by phosducinlike protein. Proc. Natl. Acad. Sci. USA, 93(5): 2100- 2104. Siegel, G.J., B.W. Agranoff, R.W. Albers, S.K. Fisher and M.D. Uhler, 1999. Basic Neurochemistry; Molecular, Cellular and Medical Aspects. 6th Edn., Lippincott Williams and Wilkins, Philadelphia, pp: 1023-1120. Siegel, G.J., R.W. Albers, S.T. Brady and D.L. Price, 2006. Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 7th Edn., Elsevier Academic Press, San Diego, pp: 339-346. Slessareva, J.E., H. Ma, K.M. Depree, L.A. Flood, H. Bae, T.M. Cabrera-Vera, H.E. Hamm and S.G. Graber 2003. Closely related G-protein-coupled receptors use multiple and distinct domains on Gprotein alpha-subunits for selective coupling. J. Biol. Chem., 278(50): 50530-50536. Sprang, S.R., 1997. G proteins, effectors and GAPs: structure and mechanism.Curr. 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ANTIDIABETIC POTENTIAL OF Irvingia gabonensis ON DIABETES INDUCED MOTOR IMPAIRMENT ON ALBINO RATS CEREBELLUM

Hyperglycemia as a life threatening disease causes motor impairments which has been ignored by researchers and clinicians. The study investigated the antidiabetic potential of Irvingia gabonensis (IG) on diabetic induced motor disorder in albino rats. Thirty rats were assigned into 6 groups of 5 rats each. Diabetes was induced by a single intra-peritoneal injection of 60 mg/kg of Streptozotocin (STZ) and confirmed after 72 hours. Blood glucose was checked at interval of 5 days for sustained hyperglycemia. Groups C, D and E were treated with100, 200 and 300 mg/kg of IG while Group F received 500 mg/kg of metformin. Motor activities were tested using string method to ascertain the role of IG on motor impairment in diabetic rats. The supernatants of homogenates were used to assay for lipid profiles namely TChol, Trig, HDL and LDL. The result showed significant decrease in TChol, LDL, triglyceride and HDL across the treated groups compared to group B (P≤0.05). Grip strength significantly decreased in group B while the extract significantly increased the grip strength in Groups C, D and E (Table 2). Limb impairment was significantly reduced in group B compared to A and increased in groups C, D and E (P≤0.05). Microscopically, group B showed structural alterations in the cerebellum with structural improvement in treated groups C, D, and E compared to group B. In conclusion, Ig have the potential to improve grip strength and limb impairment which may be useful in addressing motor complications arising from diabetes

The Roles of Opioid Receptors and Agonists in Health and Disease Conditions

The authors graciously acknowledge Queen Margaret University, Edinburgh for the award of the Martlet research Scholarship and the Ahmadu Bello University Zaria-Nigeria for awarding the first author study fellowship to undertake this research studies.Opioid receptors are found in the Central Nervous System (CNS) and are classified as mu (µ), kappa (κ), delta (δ) and sigma (σ) opioid receptors. Opioid receptors belong to the large family of G Protein Coupled Receptors (GPCRs), and have diverse and important physiological roles. The aim of the present review is to discuss the roles played by opioid receptors, their agonists and antagonists in health and disease conditions. Opioid receptors are not uniformly distributed in the CNS and are found in areas concerned with pain, with the highest concentration in the cerebral cortex, followed by the amygdala, septum, thalamus, hypothalamus, midbrain and spinal cord. Activated delta opioid receptors are coupled to Gi1 while activated mu opioid receptors are coupled to Gi3 in neuroblastoma cells. Mu opioid receptors are activated by mu receptor agonists and are coupled through the Gi1 and GoA. Both mu and kappa opioid receptors are coupled via both Gi and Gz and opioid receptors are important targets for thousands of pharmacological agents. GPCRs typically require activation by agonists for their signalling activity to be initiated but some of the GPCRs may display basal or spontaneous signalling activity in the absence of an agonist. The stimulation of these receptors triggers analgesic effects and affects the function of the nervous system, gastrointestinal tract and other body systems. Hundreds of analogs of opioid peptides have been synthesized in an effort to make the compounds more active, selective, and resistant to biodegradation than the endogenous ligands. 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Reisine 1996. Molecular biology of opioid receptors. NIDA Res. Monogr., 61: 83-103. Reche, I., J.A. Fuentes and M. Ruiz-Gayo, 1996. Potentiation of 9-tetrahydro cannabinol-induced analgesia by morphine in mice: involvement of _- and 6-opioid receptors. Eur. J. Pharmacol., 318: 11-16. Reisine, T. and G.I. Bell, 1993. Molecular biology of opioid receptors. Trend. Neurosci., 16(12): 506-510. Reisine, T. and M.J. Brownstein, 1994. Opioid and cannabinoid receptors. Curr. Opin. Neurobiol., 4(3): 406-412. Rhim, H. and R.J. Miller, 1994. Opioid receptors modulate diverse types of calcium channels in the nucleus tractus solitarius of the rat. J. Neurosci., 14(12): 7608-7615. Rodr_guez de Fonseca, F., P. Rubio, F. Menzaghi, E. Merlo-Pich, J. Rivier, G.F. Koob, and M. Navarro, 1996. Corticotropin-Releasing Factor (CRF) antagonist [D-Phe12, Nle21,38,C alpha MeLeu37]CRF attenuates the acute actions of the highly potent cannabinoid receptor agonist HU-210 on defensive-withdrawal behaviour in rats. 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Involvement of delta-and mu-opioid receptors in the delayed cerebral ischemic tolerance induced by repeated electroacupuncture preconditioning in rats. Chin. Med. J. (Engl), 120(5): 394-3992pub2726pub

The Effect of Hypoxia on G Protein Coupled (CB1) Receptor Gene Expression in Cortical B50 Neurons in Culture

The authors acknowledge Queen Margaret University, Edinburgh for the award of the Martlet research Scholarship and the Ahmadu Bello University Zaria-Nigeria for awarding the first author study fellowship to undertake this research studies. The authors would like to thank Promega Corporation for generously providing us with free samples and assay kits and reagents. Our special thanks go to Drs Paul Kelly and Linda Ferrington of the Centre for Neuroscience, University of Edinburgh for their help and guidance in RT-PCR technique. Our thanks goes to Dr Elizabeth Fashola- Stone, Technical Manager European collection of cell cultures (ECACC), for providing specialist and technical advice on the use of B50 cells.Hypoxia adversely affects cells and tissues, and neuronal cells in particular have been shown to be more susceptible to the injurious effects of hypoxia in which they may begin to die when oxygen supply is reduced or completely eliminated. Cannabinoid (CB1) receptor agonists have been shown to elicit several Central Nervous System (CNS) effects, mediated via G protein-coupled receptors. The aim of this study was to examine the effect of hypoxia on G protein coupled receptor (CB1) gene expression in cortical neuronal B50 cell lines in culture. The B50 cells were cultured in normoxia (21% O2; 5% CO2) and hypoxia (5% O2; 5% CO2), and were treated with cannabinoid agonists to determine their effects on hypoxia-induced changes. Three cannabinoid agonists [Win55,212-2 mesylate (Win), arachidonoylethanolamide (AEA) and 2- arachidonylglycerol (2-AG)], were administered to the cells as treatment for 48 hours after 48hours of initial culture for a total of 96hours of culture in hypoxic conditions at concentrations of 10, 50 and 100 nM. The levels of G-protein coupled receptor (CB1) mRNAs were assessed using RT-PCR. The results showed that hypoxia induced morphological changes in B50 cells in hypoxia while the CB1 RT-PCR mRNA levels showed no appreciable changes in normal, hypoxic and treated cells. The results show that B50 neuronal cells are susceptible to damage and injurious effects of hypoxia, as are most brain cells and the cannabinoid agonist treatments showed there were no changes in the level of CB1 receptor gene expression due to hypoxia or agonist treatment in neuronal B50 cells in culture.sch_dieAguado, T., A. Carracedo, B. Julien, G. Velasco, G. Milman, R. Mechoulam, L. Alvarez, M. Guzman and I. Galve-Roperh, 2007. Cannabinoids induce glioma stem-like cell differentiation and inhibit gliomagenesis. J. Biol. Chem., 282(9): 6854-6862. Begg, M., P. Pacher, S. Batkai, D. Osei-Hyiaman, L. Offertaler, F.M. Mo, J. Liu and G. Kunos 2005. Evidence for novel cannabinoid receptors. Pharmacol Ther., 106(2):133-145. Berghuis, P., M.B. Dobszay, R.M. Ibanez, P. Ernfors and T. Harkany, 2004. 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Signaling Signatures and Functional Properties of Anti-Human CD28 Superagonistic Antibodies

Superagonistic CD28 antibodies (CD28SAs) activate T lymphocytes without concomitant perturbation of the TCR/CD3-complex. In rodents these reagents induce the preferential expansion of regulatory T cells and can be used for the treatment of autoimmune diseases. Unexpectedly, the humanized CD28 superagonist TGN1412 caused severe and life threatening adverse effects during a recently conducted phase I clinical trail. The underlying molecular mechanisms are as yet unclear. We show that TGN1412 as well as the commercially available CD28 superagonist ANC28.1 induce a delayed but extremely sustained calcium response in human naïve and memory CD4+ T cells but not in cynomolgus T lymphocytes. The sustained Ca++-signal was associated with the activation of multiple intracellular signaling pathways and together these events culminated in the rapid de novo synthesis of high amounts of pro-inflammatory cytokines, most notably IFN-γ and TNF-α. Importantly, sustained transmembranous calcium flux, activation of Src-kinases as well as activation of PI3K were found to be absolutely required for CD28SA-mediated production of IFN-γ and IL-2. Collectively, our data suggest a molecular basis for the severe side effects caused by TGN1412 and impinge upon the relevance of non-human primates as preclinical models for reagents that are supposed to modify the function of human T cells

Anthropometric Study of the Index (2 nd ) and Ring (4 th ) Digits in Ebira Ethnic Group of Nigeria

Abstract: The Anthropometric Study of Index (2D) and Ring (4D) Digits of Ebira tribe of Nigeria was carried out to determine the values of the 2D and 4D digit ratios and correlate them with other anthropometric variables. Six hundred adults between ages of 18 years and above were recruited randomly excluding those with hand deformities. Three hundred were males and three hundred were females and of these numbers, one hundred males and one hundred females students were selected from each of the participating areas. The index (2D) and ring (4D) digit lengths were measured from the basal crease to the tips using a digital measuring tape and the height and weight were measured. The 2D:4D ratios were then determined for each subject while the height and weight were used to calculate the BMI and the data analyzed. The results show significant difference (p<0.01) in 2D:4D ratio between the males and the females. Males have longer fourth (4D) and shorter second (2D) digit lengths with lower digit ratio while females have shorter fourth (4D) and longer second (2D) digit lengths with higher digit ratio. The result confirms that digit ratios are sexually dimorphic and there was a positive correlation between height, weight, BMI and digit lengths in both males and females. The result of the 2D:4D ratios of the Ebira ethnic group show that the 2D:4D ratio of females was greater than the digit ratio of the males and also the digit ratio has no relationship with either height, weight or BMI of an individual and represents the original data for the people of the Ebira tribe of Nigeria

The Roles of G-protein coupled receptors in health and disease conditions

The super family of G-protein-coupled receptors (GPCRs) is the main target for the actions exerted by hormones, drugs and neurotransmitters. Each GPCR shows preferential coupling to some members of the G-protein family such as Gs, Gi and Gq which in turn activates the defined second messenger pathways. The G protein-coupled receptors (GPCRs) represent 50-60% of the current drug targets and this family of membrane proteins plays a crucial role in drug discovery, health and disease conditions. The G-protein-mediated signalling system has been used to study transmembrane signalling mechanisms in eukaryotic organisms resulting in different cellular activities and effects such as cellular growth, proliferation and differentiation. The G-protein-mediated signalling systems are made up of three main components, the receptors, the heterotrimeric G-proteins and the effectors in addition to various proteins that modulate the G-protein-mediated signalling process like the regulators of G-protein signalling (RGS) proteins. Mammalian cells express many GPCRs and several types of heterotrimeric G-proteins and their effectors. A number of drugs based on GPCRs have been developed for such different indications as cardiovascular, metabolic, neurodegenerative, psychiatric, and oncologic diseases. Most neurotransmitters of the central nervous system (CNS) act on GPCRs to mediate different cellular responses in normal and disease states. The activation of receptors that interact through Gi e.g. cannabinoid receptor types convey neuronal protection against hypoxic insult and resultant excitotoxic deathsch_die1pub2898pub

ANTIDIABETIC POTENTIAL OF Irvingia gabonensis ON DIABETES INDUCED MOTOR IMPAIRMENT ON ALBINO RATS CEREBELLUM

International audienceHyperglycemia as a life threatening disease causes motor impairments which has been ignored by researchers and clinicians. The study investigated the antidiabetic potential of Irvingia gabonensis (IG) on diabetic induced motor disorder in albino rats. Thirty rats were assigned into 6 groups of 5 rats each. Diabetes was induced by a single intra-peritoneal injection of 60 mg/kg of Streptozotocin (STZ) and confirmed after 72 hours. Blood glucose was checked at interval of 5 days for sustained hyperglycemia. Groups C, D and E were treated with100, 200 and 300 mg/kg of IG while Group F received 500 mg/kg of metformin. Motor activities were tested using string method to ascertain the role of IG on motor impairment in diabetic rats. The supernatants of homogenates were used to assay for lipid profiles namely TChol, Trig, HDL and LDL. The result showed significant decrease in TChol, LDL, triglyceride and HDL across the treated groups compared to group B (P≤0.05). Grip strength significantly decreased in group B while the extract significantly increased the grip strength in Groups C, D and E (Table 2). Limb impairment was significantly reduced in group B compared to A and increased in groups C, D and E (P≤0.05). Microscopically, group B showed structural alterations in the cerebellum with structural improvement in treated groups C, D, and E compared to group B. In conclusion, Ig have the potential to improve grip strength and limb impairment which may be useful in addressing motor complications arising from diabetes

Oxidative stress-induced effects on pattern and pattern formation in cortical B50 neuronal cells in culture

Oxidative stress adversely affects cells and tissues, and neuronal cells in particular have been shown to be more susceptible to the injurious effects of oxidative stress in which the cells may die when oxygen supply is reduced or completely eliminated. The aim of the present study was to study the effect of oxidative stress using hypoxia as a bench mark on the morphology of B50 neuronal cell lines cultured in hypoxia using neuronal pattern and pattern formation as case study. The B50 cells were cultured in normal incubator (21%O2; 5% CO2) as control group and hypoxic incubator (5%O2; 5% CO2) as the experimental group. Neuronal morphology, pattern and wellbeing were assessed using same field morphological assessment of cells and lactate dehydrogenase leakage (LDH). The result showed groups of dead and degenerating B50 neuronal cells, altered neuronal pattern and pattern formation and some significant changes (P<0.05) in cellular levels of LDH leakage in normal B50 cells and hypoxic cells. The changes in morphology, neuronal pattern and LDH release indicate that oxidative stress has induced morphological and cellular changes in cortical B50 cells in culture and that the B50 neuronal cells are susceptible to damage and injurious effects of oxidative stress represented by hypoxia as most brain cells.sch_die3pub4518pub

The Effects of Hypoxia and Opioid Receptor Agonists Treatment in Cortical B50 Neuronal Cells in Culture

Hypoxia has been implicated in nerve cell deaths in many neurological disorders and opioid receptor agonists have some positive benefits on the nervous system. The aim of the present work was to investigate the effects of hypoxia and opioid receptor agonists' treatment on the morphology of B50 cells cultured in hypoxia using neuronal pattern and pattern formation as a case study. The B50 cells were cultured in normal incubator (21%O2; 5% CO2) as the control group and hypoxic incubator (5%O2; 5% CO2) as the experimental group and three opioid receptor agonists namely DAMGO (_), DSLET () and ICI-199,441 () were administered to the cells for 48 hours as treatment against hypoxia after 48 hours of culture at 10_M, 50_M and 100_M concentrations. Neuronal morphology and wellbeing was assessed using same field morphological assessment and lactate dehydrogenase leakage (LDH). The result showed groups of dead and degenerating B50 neuronal cells, altered neuronal pattern and pattern formation and some significant changes (P<0.05) in cellular levels of LDH leakage in normal, hypoxic cells and cells treated with different agonists. The changes in morphology, neuronal pattern and LDH release indicate that hypoxia induced morphological and cellular changes in B50 cells in hypoxia and opioid agonists have some potential benefits in the treatment of hypoxia-induced changes in B50 cells in culture.This paper is based on research funded by the World Health Organisation, the International Council ofNurses and the Royal College of Nursing of the United Kingdom. Whilst the primary focus is on the UK,general lessons related to international recruitment and migration of nurses are also highlighted.There is general agreement amongst all stakeholders in the UK that nursing shortages have become a majorfactor constraining health care delivery in the National Health Service in the UK. In order to overcomethese skills shortages, four areas of government initiative are underway: attracting more applicants to nurse education; encouraging returners to nursing employment; improving retention through improved careerstructures and flexible working practices; and recruiting nurses from abroad. NHS Plan targets for increased staffing have been one major factor in focusing attention on international recruitment.There has been a significant growth in the level on inflow of nurses from other countries to the UK.Registration data on annual admissions of nurses from non-UK sources shows a fivefold increase since theearly 1990s. In 2000/01 a total of 9,694 initial entrants on the UK Register were from all overseas sources.This figure has risen to approximately 15,000 in 2001/02, which equates to almost half of all new nursesentering the UK Register in the year.Registration data highlights that a total of more than 30,000 new non-UK nurses have registered in the UKin the last three years. The Philippines, South Africa and Australia have been the main sources.The trend in significant growth of recruitment of nurses from non-EU countries has not been matched byany growth in inflow from the countries of the European Union. In recent years the EU has reduced insignificance as a source of nurses entering the UK.The Department of Health in England issued guidance on ethical international recruitment practices in 1999requiring NHS employers to avoid direct recruitment from designated countries such as South Africa andthe West Indies. Registration data suggests that the 1999 guidelines may have had some short-term impactin reducing recruitment from South Africa and the Caribbean, but that this recruitment activity may havethen been displaced to other developing countries. The Department has issued a strengthened Code forinternational recruitment in late 2001.The pull factor of meeting NHS Plan staffing targets is likely to mean that the UK, particularly England,will continue to be active in recruiting from international nursing labour markets, partly as a result of newtargets having been set for 2008. UK government policy initiatives to increase the number of nursingstudents, and to improve retention and return rates, can have a positive effect. However, the growth in thenumber of UK nurses who can retire is likely to challenge the capacity of the NHS to retain the requirednumbers of nurses. 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