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61.
The CD4 and CD8 molecules play an important role in the stimulation of T cells and in the process of thymic education. Most mature T cells express the alpha beta TCR and either CD4 or CD8; however, there is a small population of alpha beta+ TCR T cells that lack both CD4 and CD8. Little is known of the biology of the CD4- CD8- (double-negative) alpha beta+ TCR T cells or the nature of the Ag to which they may respond. These cells not only represent a novel population of T cells but also provide useful biologic tools to study the roles that CD4 and CD8 play in T cell activation. In this study we have addressed two questions. Firstly, whether CD4- CD8- alpha beta+ TCR T cells have functionally active TCR and, secondly, whether CD4 or CD8 is required for the activation of T cells by bacterial enterotoxins. Six double-negative alpha beta+ TCR T cell clones, propagated from two healthy donors, were challenged with a panel of nine bacterial enterotoxins. The V alpha and V beta usage of their TCR was determined by polymerase chain reaction. All of the CD4-CD8- clones proliferated in response to at least one of the enterotoxins, in a V beta-specific manner. The proliferative response of the CD4-CD8- alpha beta+ TCR T cell clones was similar in magnitude to that exhibited by CD4+ T cell clones of known V beta expression. These data clearly show that the CD4 and CD8 molecules are not required for the activation of untransformed human T cells by bacterial enterotoxins. Furthermore, these results indicate that CD4-CD8- alpha beta+ TCR T cells, normally present in all individuals, are not functionally silent, because they can be stimulated via their TCR. Their physiologic role, like that of gamma delta T cells, remains to be elucidated.  相似文献   
62.
The key argument for the identification of prehistoric cannibalism is provided by analysis of close similarities in the treatment of human and animal remains. Such analysis requires precise data on depositional context, meticulous excavation records, detailed bone modification studies, a relatively large sample of human and animal postcranial bones, and data on local mortuary practices. With the exception of Fontbrégoua Cave, these necessary conditions are lacking at all Stone Age European sites where it has been hypothesized that cannibalism occurred. The alternative hypothesis of secondary burial practices has been proposed informally for some sites and, in a more formal and detailed way, for Krapina and Fontbrégoua. However, this hypothesis does not have a higher probability, is not justified by current data, and uses ethnographic analogies to prop up interpretations of materials for which contextual data are missing or have been neglected. At Fontbrégoua, cannibalism remains the simplest and most plausible explanation of the evidence; at Krapina and other sites the available evidence is insufficient to prove either secondary burial or cannibalism.  相似文献   
63.
A spermine-dependent, polyphenylalanine-synthesizing cell-free system having an optimum activity at 75-85 degrees C, has been developed from the extremely thermoacidophilic archaebacterium Caldariella acidophila. The C. acidophila system is totally insensitive to the EF-Tu targeted antibiotics pulvomycin (at 40 degrees C) and kirromycin (at 47-72 degrees C) contrary to control systems derived from both mesophilic (Escherichia coli) and thermoacidophilic (Bacillus acidocaldarius) eubacteria. The archaebacterial EF-Tu-equivalent factor is also immunologically unrelated to eubacterial EF-Tu and does not cross react with antibodies against Escherichia coli EF-Tu. The pulvomycin and kirromycin reactions thus provide new phyletic markers for archaebacterial ancestry.  相似文献   
64.
Six sesquiterpene lactones were isolated from Lactarius blennius. The structures of two new sesquiterpenes, blennin A and blennin B were determinated by spectroscopic methods and the structure of the seco-compound, blennin C, is revised. The two known furan sesquiterpenes and lactarorufin A were also identified.  相似文献   
65.
The binding of tritium-labelled 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (BP) and 3-methylcholanthrene (MCA) to DNA or polynucleotides in vitro was re-examined both in the presence and in the absence of rat liver or human placental microsomes.A high level of non-enzymatic binding was evident when thymus DNA was used as acceptor. This non-enzymatic binding made it difficult to determine the effect of microsomes, except in the case of BP when induced rat microsomes were used. Better results were obtained using polynucleotides: a definite microsome-dependent binding occurred between all the polynucleotides and all the hydrocarbons tested.No clear evidence of binding catalysed by microsomes from human placenta was found except in polynucleotide-BP interactions: further studies are required to completely evaluate the ability of such nucleic acid-microsomal system for testing in vitro possible oncogenic substances in animals and humans.  相似文献   
66.
The results of investigations onTyphlodromus italicus Chant in some peach orchards in the Verona district, where the predator is wide-spread, are described. Both field and laboratory studies have shown thatT. italicus grows rapidly (egg to adult 6 days at 25°C.) and has a long reproductive period, especially when prey is available. It speedily recovers in number and has a high prey-searching capacity. It is fast-moving, and its distribution over the tree corresponds to that of the phytophagous mites. It can live and reproduce on the tree in the absence of prey. A density of 50–60T. italicus/100 leaves is reached in August. FemaleT. italicus are found on leaves till November feeding whenever prey is available, and wintering in a mated condition in bark crevices. Many enter diapause in late autumn. Overwinter mortality is high. These characteristics enableT. italicus to play a very significant role in the control of peach mites and in orchards, which are unsprayed, it keeps their populations at a low density from spring to autumn.  相似文献   
67.
68.
The development of drugs able to target BTK, PI3k‐delta and BCL2 has dramatically improved chronic lymphocytic leukaemia (CLL) therapies. However, drug resistance to these therapies has already been reported due to non‐recurrent changes in oncogenic pathways and genes expression signatures. In this study, we investigated the cooperative role of the BCL2 inhibitor venetoclax and the BRD4 inhibitor JQ1. In particular, we found that JQ1 shows additional activity with venetoclax, in CLL cell lines and in ex vivo isolated primary CD19+ lymphocytes, arguing in favour of combination strategies. Lastly, JQ1 is also effective in venetoclax‐resistant CLL cell lines. Together, our findings indicated that the BET inhibitor JQ1 could be a promising therapy in CLL, both as first‐line therapy in combination with venetoclax and as second‐line therapy, after the emergence of venetoclax‐resistant clones.  相似文献   
69.
A multidisciplinary approach was carried out in order to study the biodeterioration and the associated microbiome of a XVIII Century wax seal coloured with minium. A small wax seal fragment was observed by scanning electron microscopy combined with energy dispersive spectroscopy in non-destructive mode. The same object was analysed by Raman and Fourier-transform infrared spectroscopy. The identification of the microbiota growing on the seal was performed with both a culture-dependent strategy, combined with hydrolytic assays, and high-throughput sequencing using the MinION platform. The whole bacterial 16S rRNA gene and the fungal markers ITS and 28S rRNA were targeted. It was observed that the carnauba wax coloured with lead tetroxide (minium) was covered by a biofilm consisting of a network of filaments and other structures of microbial origin. The culture-dependent and culture-independent investigations showed the presence of a complex microbiota composed mainly by fungal members, which demonstrated interesting properties related to lipids and lead processing. The formation of lead soaps and secondary biogenic minerals was also described.  相似文献   
70.
Climate change is currently affecting both biodiversity and human activities; land use change and greenhouse gas emissions are the main drivers. Many agricultural services are affected by the change, which in turn reflects on the basic provisioning services, which supply food, fibre and biofuels. Biofuels are getting increasing interest because of their sustainability potential. Jatropha curcas gained popularity as a biodiesel crop, due to its ease of cultivation even in harsh environmental conditions. Notwithstanding its high economic importance, few studies are available about its co‐occurrence with pests of the genus Aphthona in sub‐Saharan Africa, where these insects feed on J. curcas, leading to relevant economic losses. Using ecological niche modelling and GIS post‐modelling analyses, we infer the current and future suitable territories for both these taxa, delineating areas where J. curcas cultivations may occur without suffering the presence of Aphthona, in the context of future climate and land use changing. We introduce an area‐normalized index, the ‘Potential‐Actual Cultivation Index’, to better depict the ratio between the suitable areas shared both by the crop and its pest, and the number of actual cultivations, in a target country. Moreover, we find high economic losses (~?50%) both in terms of carbon sequestration and in biodiesel production when J. curcas co‐occur with the Aphthona cookei species group.  相似文献   
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