50,800 research outputs found
Selegiline (L-Deprenyl) as a Unique Neuroprotective Agent for Chronic Neurodegenerative Disorders- a Lesson from Mao Inhibition
No full textThe purpose of this review is to describe recent advances in understanding the neuroprotective effects of selegiline (N- propanyl-l- amphetamine; l-deprenyl) and the development of a variety of novel and interesting propargyl compounds that might be potentially useful in the treatment of chronic neurodegenerative brain disorders. Selegiline is a selective , non-competitive, irreversible inhibitor of monoamine oxidase ( MAO) B, and is widely used as an adjunct to Ldopa in the treatment of Parkinson's disease. Recent interest in selegiline has focused on its complex neuroprotective actions against a variety of neurotoxins, and on the pathological processes of oxidative stress and apoptosis which cause neuronal death in chronic neurodegenerative brain disorders, such as Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. These neuroprotective effects of selegiline are due not only to MAO-B inhibition, but also to many other effects, such as suppression of free radical formation elicited by MPP+ and glutamate, up regulation of the antioxidative enzymes, superoxide dismutase and catalase, induction of proteins interfering with the apoptotic pathway, and expression of neurotrophic factors. Recent molecular biological evidence suggests that selegiline may also alter the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and other redox active molecules such as thioredoxin in brain neurons. These unique neuroprotective mechanisms of selegiline may provide models for the synthesis of new Npropargyl analogues with different structure-activity relationships, and for the development of therapeutic strategies designed to prevent the evolution of pathologic neurodegeneration
Limnopilos Chuang & Ng 1991
No full textLimnopilos Chuang & Ng, 1991 Limnopilos Chuang & Ng, 1991: 363. Hymenicoides— Ng & Chuang, 1996: 50 (part); Guinot & Richer de Forges, 1997: 460 (part). Type species. Limnopilos naiyanetri Chuang & Ng, 1991, by original designation and monotypy; gender of genus masculine. Diagnosis. Carapace circular, pilose, dorsal surface concave; grooves distinct; rostrum absent or very weak; antenna with proximal portion of basal article posterior to inner section of proximal portion of eye; eyes, antennae, antennules visible dorsally; third maxillipeds narrow, not covering more than three-quarters of mouth field when closed, merus rectangular, dactylus styliform, approximately twice length of propodus; male chelae relatively stout, outer surface evenly convex, partially covered by dense setae, without tubercle. Female vulva placed on imaginary line joining inner ends of sutures between sternites 5, 6 on medial fused plate of thoracic sternum, vulva with basal mount. Male abdomen-pleotelson 6 segmented, pleotelson slightly trilobed, inner surface thickened distally, forming socket for sternal button (Fig. 1 c, d). G 1 stout, bent outwards medially; distal part with distal inner processes, tuberculate distal outer angle. Female abdomen-pleotelson with six distinctly demarcated segments, boundary between first and second (L. sumatranus) or between second and third segments (L. naiyanetri) movable; long, biramous pleopods on second to fifth segments, developed from distal outer end of inner surface of each segment. Remarks. Several characters clearly distinguish Limnopilos from Hymenicoides (see Remarks for Hymenicoides above). In addition to L. naiyanetri, the type species, H. microrhynchus Ng, 1995, and L. sumatranus new species, all possess the diagnostic characters of the genus and are therefore transferred to Limnopilos. In the case of L. microrhynchus, only male specimens are known thus far, and the female characters diagnosed above are therefore not known for this species.Published as part of Naruse, Tohru & Ng, Peter K. L., 2007, On the taxonomy of the genus Hymenicoides Kemp, 1917 (Crustacea: Decapoda: Brachyura: Hymenosomatidae), with resurrection of Limnopilos Chuang & Ng, 1991, and descriptions of two new species, pp. 17-31 in Zootaxa 1621 on page 26, DOI: 10.5281/zenodo.17919
G protein-coupled receptors: Heterologous regulation of homologous desensitization and its implications
No full textTwo patterns of rapid desensitization have been characterized for G protein-coupled receptors: homologous desensitization, which mainly involves G protein-coupled receptor kinases and arrestins, and heterologous desensitization, which mainly involves protein kinases A (PKA) and C (PKC). In this review, Tsu Tshen Chuang and colleagues discuss evidence to show that PKA and PKC can modify the functional state of the G protein-coupled receptor kinases/arrestin homologous desensitization machinery, providing a novel level of cross-talk in signal transduction. Studies on regulation of G protein-coupled receptor kinases and arrestins confirm that the functional state of this machinery may have important consequences for cellular responsiveness and may represent new targets for therapeutic strategies
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