Convergence cultural

In primary cultures of neonatal cerebellar granule neurons, all Ca2+ sensors, calmodulin, protein kinases C (PKC), and the p21(ras)/phosphatidylinositol 3 -kinase (Ptdlns-3K)/Akt pathway, converge towards NF-kB at the levels of nuclear translocation as well as transcription. The duration of NF-kB activation is a critical determinant for sensitivity toward excitotoxic stress and is dependent on the different upstream and downstream signaling associated with various kinases. This is in contrast to studies in non-neuronal cells, which either do not respond to Ca2+ or do not simultaneously activate all three cascades (Lilienbaum and Israel, 2003). Collective evidence suggests that brain inflammatory processes differ from systemic inflammation not only in the involvement of various types of neural cells but also in differences in response to second messengers. 

Despite the prima facie attraction of cultural convergence in medicine, there are not only major differences in the incidence and prevalence of many diseases between countries but also in expectations of these different cultural groups of patients. Even in a relatively homogeneous region such as Western Europe, the incidence of adverse drug reactions to a standard therapy varies dramatically from country to country. The perception of... 

Other related systems, which contain the 5-ylidenepyrrol-2-(5//)-one structural unit are (-)-ampullicin (91a) and (+)-isoampullicin (91b), sesquiterpene amides isolated from a culture filtrate of an Ampulliferine-like fungus sp. no. 27 [161], obtained from a dead pine tree (Pinus thunbergii). The latter compounds accelerate the root growth of lettuce, and their structures have been determined by X-ray diffraction and NMR data [162]. The total synthesis of both compounds (91) by means of a convergent synthesis from a tricyclic aldehyde and the phosphonate derived from a substituted maleimide has been reported [163,164]. (Scheme 42). 

Magal, E., Burnham, P., Varon, S., and Louis, J.-C. (1993) Convergent regulation by ciliary neurotrophic factor and dopamine of tyrosine hydroxylase expression in cultures of rat substantia nigra. Neuroscience 52 867-881. 

In the synthesis of aspyrone (994), an antibiotic isolated from the culture broth of Aspergillus species, lactaldehyde 990 supplies the asymmetric centers of the epoxide in the side chain (Scheme 134). The molecule is assembled convergently by addition of the lithium enolate of D-rhamnose-derived a-phenylseleno- -lactone 991 to aldehyde 990. After an initial aldol-type reaction, the intermediate alkoxide displaces tosylate to provide epoxide 992 with >99.8% stereoselectivity. Peroxide-induced elimination of phenylselenide furnishes TBS-protected aspyrone 993 in 61% overall yield from 990. 

The contribution of MS to identification of compounds and quantification of their concentration is complementary to other detection techniques and, despite being very practical and versatile, it remains fundamentally replaceable. However, knowledge of molecular weight is a prerequisite for techniques that rely on the synergies with stable isotopic tracers. In fact, powerful analytical methods exist to obtain important insights on cell dynamics from the ratiometric measurement of marked and not-marked species (or atoms). We cite, for example, (1) relative abundances of virtually all metabolites or proteins in two separate cultures are quantified based on the isotope dilution theory [43 5] (2) information on the mechanisms and kinetics of nonlinear chemical processes can be extracted from response tracer experiments [46 7] and (3) the labeling patterns in metabolic intermediates are used to resolve the relative rate in convergent reactions in vivo [48,49]. 

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