Bioreactors for surface-immobilized cells

Surface immobilization of plant cells avoids the problem of hydrodynamic or shear stress, which tends to be characteristic of suspended cells cultured in typical, mechanically agitated bioreactor systems. Surface immobilization also promotes the natural tendency for plant cells to aggregate, which may improve the synthesis and accumulation of secondary metabolites. In addition, exchange of medium is made simple in surface-immobilized systems, and extracellular secondary products are easily recovered on a continuous basis. However, problems related to regulation of the thickness of the immobilized cell layer, maintenance of the biomass in a productive condition, and vacuolar retention of secondary products have yet to be resolved satisfactorily. This review focusses on two surface-immobilization technologies, differing primarily in the nature and the configuration of the inert support. Prototypes of these designs have been applied to a variety of plant cell systems at bioreactor volumes up to 20 litres. Results obtained with several alternative technologies are also summarized.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - SIPCB surface-immobilized plant cell bioreactor National Research Council of Canada publication no. 38460     

Knowledge and use of medicinal plants by local specialists in an region of Atlantic Forest in the state of Pernambuco (Northeastern Brazil)

This paper investigates the wealth of medicinal plants used by the Apatani tribe of Arunachal Pradesh. Apatani have traditionally settled in seven villages in the Ziro valley of Lower Subansiri district of Arunachal Pradesh in the Eastern Himalayan region of India. The present study has resulted in the documentation of 158 medicinal plant species used by the Apatani group of villages. These medicinal plant species were distributed across 73 families and 124 genera. Asteraceae was the most dominant family (19 species, 11 genera) of medicinal plants, followed by Zingiberaceae, Solanaceae, Lamiaceae and Araceae. For curing ailments, the use of aboveground plant parts was higher (80%) than the belowground plant parts in the Apatani group of villages. Of the aboveground plant parts, leaf was used in the majority of cases (56 species), followed by fruit. Different belowground plant forms such as root, tuber, rhizome, bulb and pseudo-bulb were used by Apatani as a medicine. About 52 types of ailments were cured by using these 158 medicinal plant species. The results of this study are further discussed in the changing socio-economic contexts.     

Chemokine Receptors CCR6 and CXCR3 Are Necessary for CD4+ T Cell Mediated Ocular Surface Disease in Experimental Dry Eye Disease

CD4⁺ T cells are essential to pathogenesis of ocular surface disease in dry eye. Two subtypes of CD4⁺ T cells, Th1 and Th17 cells, function concurrently in dry eye to mediate disease. This occurs in spite of the cross-regulation of IFN-γ and IL-17A, the prototypical cytokines Th1 and Th17 cells, respectively. Essential to an effective immune response are chemokines that direct and summon lymphocytes to specific tissues. T cell trafficking has been extensively studied in other models, but this is the first study to examine the role of chemokine receptors in ocular immune responses. Here, we demonstrate that the chemokine receptors, CCR6 and CXCR3, which are expressed on Th17 and Th1 cells, respectively, are required for the pathogenesis of dry eye disease, as CCR6KO and CXCR3KO mice do not develop disease under desiccating stress. CD4⁺ T cells from CCR6KO and CXCR3KO mice exposed to desiccating stress (DS) do not migrate to the ocular surface, but remain in the superficial cervical lymph nodes. In agreement with this, CD4⁺ T cells from CCR6 and CXCR3 deficient donors exposed to DS, when adoptively transferred to T cell deficient recipients manifest minimal signs of dry eye disease, including significantly less T cell infiltration, goblet cell loss, and expression of inflammatory cytokine and matrix metalloproteinase expression compared to wild-type donors. These findings highlight the important interaction of chemokine receptors on T cells and chemokine ligand expression on epithelial cells of the cornea and conjunctiva in dry eye pathogenesis and reveal potential new therapeutic targets for dry eye disease.     

Effect of tyrosine ionization upon biological activities of angiotensin II and two new peptide analogues.

The role of the tyrosine side-chain in the smooth muscle contracting activity of angiotensin III was investigated by determining intrinsic activities and ED50 values of [4-(3-chlorotyrosine)]angiotensin II and [4-(3-benzyltyrosine)]angiotensin II in the isolated guinea-pig ileum and rat uterus. [4-(3-chlorotyrosine)]angiotensin II activity was compared with that of angiotensin II at different pH values, in which the ratio of their degrees of phenolic ionization varied. The results indicated that deprotonation of the phenolic group hinders binding to smooth muscle cell receptors, but not triggering of the response by the hormone-receptor complex. Steric hindrance by the benzyl substituent in [4-(3-benzyltyrosine)]angiotensin II reduced both receptor-binding and triggering of the response.