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排序方式: 共有740条查询结果,搜索用时 15 毫秒
1.
Carlo Ferrarese Flora Vaccarino Hannu Alho Britt Mellstrom Erminio Costa Alessandro Guidotti 《Journal of neurochemistry》1987,48(4):1093-1102
Diazepam binding inhibitor (DBI), a peptide located in CNS neurons, blocks the binding of benzodiazepines and beta-carbolines to the allosteric modulatory sites of gamma-aminobutyric acid (GABAA) receptors. Subcellular fractionation studies of rat brain indicate that DBI is compartmentalized. DBI-like immunoreactivity is highly enriched in synaptosomes obtained by differential centrifugation in isotonic sucrose followed by a Percoll gradient. In synaptosomal lysate, DBI-like immunoreactivity is primarily associated with synaptic vesicles partially purified by differential centrifugation and continuous sucrose gradient. Depolarization induced by high K+ levels (50 mM) or veratridine (50 microM) released DBI stored in neurons of superfused slices of hypothalamus, hippocampus, striatum, and cerebral cortex. The high K+ level-induced release is Ca2+ dependent, and the release induced by veratridine is blocked by 1.7 microM tetrodotoxin. Depolarization released GABA and Met5-enkephalin-Arg6-Phe7 together with DBI. DBI is also released by veratridine depolarization, in a tetrodotoxin-sensitive fashion, from primary cultures of cerebral cortical neurons, but not from cortical astrocytes. Depolarization fails to release DBI from slices of liver and other peripheral organs. These data support the view that DBI may be released as a putative neuromodulatory substance from rat brain neurons. 相似文献
2.
Ossi Renkonen Ritva Niemelä Anne Leppänen Hannu Maaheimo Antti Seppo Leena Penttilä Anja Vilkman 《Glycoconjugate journal》1991,8(4):368-375
Radiolabelled GlcNAc beta 1-3(GlcNAc beta 1-6)Gal (1), GlcNAc beta 1-3)GlcNAc beta 1-6)Gal beta 1-OCH3 (4), GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4Glc (7), and GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc (10) were cleaved partially with jack bean beta-N-acetylhexosaminidase (EC 3.2.1.30), and the digests were analysed chromatographically. All four oligosaccharides were hydrolysed faster at the (1-6) branch, than at the (1-3) branch, but a high branch specificity was observed only with the glycan 4. The saccharides 1 and 7 resembled each other in the kinetics of the enzyme-catalysed release of their two non-reducing N-acetylglucosamine units, but the glycan 10 was rather different. The partial digestions made it possible to obtain radiolabelled GlcNAc beta 1-6Gal, GlcNAc beta 1-6Gal beta 1-OCH3, GlcNAc beta 1-6Gal beta 1-4Glc, and, in particular, GlcNAc beta 1-6Gal beta 1-4GlcNAc. 相似文献
3.
A p50 surface antigen restricted to human urinary bladder carcinomas and B lymphocytes 总被引:18,自引:0,他引:18
Staffan Paulie Barbro Ehlin-Henriksson Håkan Mellstedt Hannu Koho Hedi Ben-Aissa Peter Perlmann 《Cancer immunology, immunotherapy : CII》1985,20(1):23-28
Summary We have previously described the derivation of a monoclonal antibody, S2C6, to a novel 50 Kdalton antigen associated with human urinary bladder carcinoma. No reactions were obtained with carcinomas of unrelated origin or with normal urothelial cells. However, the antibody also reacted with a similar antigen on some cell lines of B lymphocyte origin. Using large panels of target cells we have now shown that this reactivity was entirely restricted to cells of the B lineage within the haematopoietic system. As opposed to its apparent restriction to malignant cells of the urothelium, the S2C6 antigen was expressed by normal B lymphocytes as well as by many malignant B cells (chronic lymphocytic leukaemia, hairy cell leukaemia and immunocytoma). Pre-B cells derived from acute lymphocytic leukaemia and plasma cells from multiple myeloma lacked the antigen. Expression was significantly enhanced on cultured B cells from Burkitt lymphomas and on Epstein-Barr virus-transformed lymphoblastoid cell lines including those of the pre-B phenotype derived from fetal bone marrow. As judged from the molecular size and the distribution pattern displayed by the S2C6 antigen it appears to be distinct from other B cell antigens previously described. A possible relation of the S2C6 antigen to a receptor for B cell growth factors is discussed. 相似文献
4.
5.
Morphological changes of pancreatic tissue in young pigs caused by surgical ligation of the main pancreatic duct are described. Nineteen animals from 6 to 7 weeks in age were operated on and necropsied 3 or 6 to 8 weeks later. Twelve pigs developed a pronounced chronic pancreatitis with complete exocrine insufficiency. Of the 7 animals failing to develop ectasia of pancreatic ducts, 2 died due to surgical complications. In addition, 3 pigs were sham-operated and served as controls. In macroscopical studies it was observed that in the pronounced pancreatitis cases the ligated duct was greatly dilated by a clear watery fluid. Only remnants of pale and firm grandular tissues were seen around the ectatic ducts. Microscopically, typical changes of chronic pancreatitis were noted. Complete disappearance of acini was followed by ductular cell proliferations. Glandular tissues were divided into lobuli by fibrotic tissues and fat cells. The wall of the main pancreatic duct was greatly thickened and fibrotic, presenting intensely proliferating ductular cells and round cell infiltrates. Furthermore, enlarged endocrine islets surrounded by connective tissue fibres were seen. 相似文献
6.
Ismo Virtanen Jouni Lohi Taneli Tani Hannu Sariola Robert E. Burgeson Veli-Pekka Lehto 《The Histochemical journal》1996,28(9):643-650
Summary In recent studies, the α2 chain of laminin (Ln) has been suggested to be the only laminin α chain expressed in mouse and human
thymus. We have now used chain-specific monoclonal antibodies and indirect immunofluorescence microscopy to study the expression
of laminin chains in samples of foetal and 6-year-old human thymus. The subepithelial basement membrane of the capsule of
foetal 16- to 18-week thymus presented a bright immunoreactivity for Ln α1, α3, β1, β3 and γ1 chains but not for α2 chain,
suggesting the expression of laminins-1 and-5. Most cortical and medullary epithelial cells, including Hassall's corpuscles,
however, lacked laminin immunoreactivity. Immunoreactivity for Ln β2 chain was only seen in basal laminae of larger blood
vessels. In thymic specimens from 6-year-old children, immunoreactivity for the laminin α1, α3, β1, β3 and γ1 chains was invariably
found in subepithelial basement membrane of the capsule and that for laminin α2 chain was now also distinct but more heterogeneous.
Furthermore, the thymic subepithelial basement membrane of the capsule at all stages showed immunore-activity for collagen
type VII, forming the anchoring fibres in epithelial basement membranes. The subcapsular thymic epithelium also showed immunoreactivity
for the BP 230 antigen and β4 integrin subunit, both components of hemidesmosomes. The present results show that the thymic subepithelial basement membrane
of the capsule presents properties which are commonly seen in stratified and combined epithelia, and are compatible with suggestions
of the antigenic similarity of thymic epithelial cells and keratinocytes. 相似文献
7.
Suppressed breeding in the field vole (Microtus agrestis): an adaptation to cyclically fluctuating predation risk 总被引:6,自引:0,他引:6
The densities of microtine rodents and their main predators,small mustelids, fluctuate synchronously in 35-year cyclesin central and northern Fennoscandia. Predation by small mustelidshas been suggested as one of the driving forces in microtinecyclicity, causing deep synchronous declines of several volespecies. We studied experimentally the effects of small mustelidson mating behavior, foraging, and breeding in nonwintered fieldvoles (Microtus agrestis) originating from a cyclic population.By using mustelid odors, we simulated a crash phase environmentwith high predation risk for breeding pairs of voles. In ourexperiments, 87% of the female field voles suppressed breedingwhen exposed to mustelid odors. Both female and male behaviorchanged, and no mating behaviors were observed under the simulatedpredation risk. Weights of both sexes decreased when exposedto mustelid odor, probably due to decreased foraging; weightsof the control females increased due to pregnancy; and no weightchanges occurred in control males. Decreased breeding and foragingpossibilities under high predation pressure may form the basisfor the ultimate explanation for breeding suppression. Thereare at least two different mechanisms for breeding suppression:either mating does not take place or malnutrition in femalesdoes not' allow breeding to occur. Delayed breeding under highrisk of predation, for whatever reason, could increase the probabilityof individuals, especially that of the females, to survive overthe crash to the next, safer breeding season when their youngwould have better possibilities to survive. 相似文献
8.
Microfungal species composition and fungal biomass in a coniferous forest soil polluted by alkaline deposition 总被引:3,自引:0,他引:3
Isolations of soil microfungi from the humus (F/H-layer) of a coniferous forest soil which was either unpolluted (pH 4.1) or polluted (pH 6.6) for 25 years by deposition of alkaline dust, were made by soil washing and spore plating. Both techniques revealed similar changes in species composition. Alkaline dust exposure caused a reduction in overall species numbers, but led to higher relative isolation frequencies of Mortierella alpina, Oidiodendron tenuissimum, Penicillium montanese, Sagenomella verticillata, and Trichosporiella sporotrichioides. The incidence of M. isabellina, O. cf. clamydosporium, P. spinulosum, Penicillium sp. 1, P. sclerotiorum, Trichoderma viride, and Verticillium bulbillosum was reduced on polluted sites. The amount of the mainly fungal-derived phospholipid fatty acid 18 : 26 decreased by 23%, while the amount of ergosterol increased by 9% in the polluted soil.
Offprint requests to: H. Fritze. 相似文献
9.
Factors affecting species number and density of dabbling duck guilds in North Europe 总被引:2,自引:0,他引:2
We addressed how species number and pair density in guilds of co-existing species is related to habitat structure, and to the abundance and diversity of food resources using the assemblage of seven species of dabbling ducks (genus Anas ) breeding in 60 lakes distributed over six regions in temperate north Europe
Partial correlation and multiple regression revealed that species richness was best predicted by habitat structural diversity as indexed by a principal component analysis based on 18 vegetation and lake characteristics, and by the abundance of aquatic and emergent prey We found no effect of lake size or prey size diversity on species richness Pair density was correlated with the percentage of shoreline with horsetails ( Equisetum ), by habitat structural diversity and by the abundance of emergent invertebrate prey Neither prey size diversity nor abundance of aquatic prey correlated with pair density Species richness and pair density in North European duck guilds vary both with habitat structure and prey availability 相似文献
Partial correlation and multiple regression revealed that species richness was best predicted by habitat structural diversity as indexed by a principal component analysis based on 18 vegetation and lake characteristics, and by the abundance of aquatic and emergent prey We found no effect of lake size or prey size diversity on species richness Pair density was correlated with the percentage of shoreline with horsetails ( Equisetum ), by habitat structural diversity and by the abundance of emergent invertebrate prey Neither prey size diversity nor abundance of aquatic prey correlated with pair density Species richness and pair density in North European duck guilds vary both with habitat structure and prey availability 相似文献
10.
Thermal Inactivation of Nonproteolytic Clostridium botulinum Type E Spores in Model Fish Media and in Vacuum-Packaged Hot-Smoked Fish Products
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Miia Lindstrm Mari Nevas Sebastian Hielm Liisa Lhteenmki Michael W. Peck Hannu Korkeala 《Applied microbiology》2003,69(7):4029-4036
Thermal inactivation of nonproteolytic Clostridium botulinum type E spores was investigated in rainbow trout and whitefish media at 75 to 93°C. Lysozyme was applied in the recovery of spores, yielding biphasic thermal destruction curves. Approximately 0.1% of the spores were permeable to lysozyme, showing an increased measured heat resistance. Decimal reduction times for the heat-resistant spore fraction in rainbow trout medium were 255, 98, and 4.2 min at 75, 85, and 93°C, respectively, and those in whitefish medium were 55 and 7.1 min at 81 and 90°C, respectively. The z values were 10.4°C in trout medium and 10.1°C in whitefish medium. Commercial hot-smoking processes employed in five Finnish fish-smoking companies provided reduction in the numbers of spores of nonproteolytic C. botulinum of less than 103. An inoculated-pack study revealed that a time-temperature combination of 42 min at 85°C (fish surface temperature) with >70% relative humidity (RH) prevented growth from 106 spores in vacuum-packaged hot-smoked rainbow trout fillets and whole whitefish stored for 5 weeks at 8°C. In Finland it is recommended that hot-smoked fish be stored at or below 3°C, further extending product safety. However, heating whitefish for 44 min at 85°C with 10% RH resulted in growth and toxicity in 5 weeks at 8°C. Moist heat thus enhanced spore thermal inactivation and is essential to an effective process. The sensory qualities of safely processed and more lightly processed whitefish were similar, while differences between the sensory qualities of safely processed and lightly processes rainbow trout were observed. 相似文献