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81.
The brain organization of butterflyfishes   总被引:2,自引:0,他引:2  
Synopsis The encephalization indices of angelfishes (Pomacanthidae) and butterflyfishes (Chaetodontidae) are typical of advanced perciform fishes: both families lie in the upper part of the polygon of teleost indices. The chaetodontids seem to be a little more encephalized than pomacanthids. The general morphology of the brains in both families is very similar: small olfactory bulbs, large optic tectum and a cerebellum which covers the brain structures in front of it like a cap. This morphology is shared by another family of the coral reef biotope, the Acanthuridae. The histological architecture is also typical of advanced teleosts, with a cortex-like pallium, a laminated nucleus geniculatus (= pretectalis superficialis), a complex valvula cerebelli and a corpus glomerulosum with a clear neuropile centre. The quantitative analysis of the main subdivisions of the brain, either from relative volumes or from indices, shows small olfactory bulbs (microsmy) but important telencephalic and diencephalic centres, large tectal centres (vision) and large cerebellum (precise locomotion). Many of these peculiarities are shared by other fishes inhabiting coral reefs. The differences between the two families seem to be primarily correlated with food habits: the angelfishes, which are sponge-feeders and may have an overweight due to the ballast of the sponge-skeleton in their digestive tract, and which do not need either such good vision or such precise locomotion to pick up their prey, could be a little less encephalized than the butterflyfishes.  相似文献   
82.
The perennial taxa ofCrucianella in Asia form a coherent group, apparently diploid (x = 11) and outbreeding throughout, and should be placed into sect.Roseae. This Irano-Turanian group has its centre of diversity in the mountain systems south of the Caspian Sea and reaches with outposts NE. and E. Anatolia, NE. Iraq, S. Iran and C. Asia. Four species and 13 subspecies (within the polymorphicC. gilanica) are recognized, described (partly as new), and illustrated (Figs. 1–6). Conspectus, keys and distribution maps (Figs. 7 and 8) as well as plesio- and apomorphic character states and data on size of areas are provided (Table 1). There is an obvious correlation between more plesiomorphic taxa with smaller areas in the distribution centre of the group, and more apomorphic taxa with larger areas towards its periphery (Fig. 9). These findings are linked to a working hypothesis on the evolution of the group.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday.  相似文献   
83.
Acute and Chronic Effects of Ethanol on Transbilayer Membrane Domains   总被引:3,自引:1,他引:2  
Alcohols, including ethanol, have a specific effect on transbilayer and lateral membrane domains. Recent evidence has shown that alcohols in vitro have a greater effect on fluidity of one leaflet as compared to the other. The present study examined effects of chronic ethanol consumption on fluidity of synaptic plasma membrane (SPM) exofacial and cytofacial leaflets using trinitrobenzenesulfonic acid (TNBS) labeling and differential polarized fluorometry of 1,6-diphenyl-1,3,5-hexatriene (DPH). Mice were administered ethanol or a control liquid diet for 3 weeks. Animals were killed and SPM prepared. The exofacial leaflet of SPM was significantly more fluid than the cytofacial leaflet in both groups, as indicated by limiting anisotropy of DPH. However, differences between the two leaflets were much smaller in the ethanol-treated group. Ethanol at concentrations seen clinically had a greater effect in vitro on the more fluid exofacial leaflet. This asymmetric effect of ethanol was significantly diminished in the exofacial leaflet of the ethanol-treated mice. Chronic ethanol consumption has a specific effect on membranes. Membrane functions that may be regulated by asymmetry of fluidity and lipid distribution may be altered by chronic ethanol consumption.  相似文献   
84.
Summary Epithelial cells isolated from fragments of hamster pancreas interlobular ducts were freed of fibroblast contamination by plating them on air-dried collagen, maintaining them in serum-free Dulbecco's modified Eagle's (DME):F12 medium suppleneted with growth factors, and selecting fibroblast-free aggregates of duct cells with cloning cylinders. Duct epithelial cells plated on rat type I collagen gel and maintained in DME:F12 supplemented with Nu Serum IV, bovine pituitary extract, epidermal growth factor, 3,3′, 5-triodothyronine, dexamethasone, and insulin, transferrin, selenium, and linoleic acid conjugated to bovine serum albumin (ITS+), showed optimal growth as monolayers with a doubling time of about 20 h and were propagated for as long as 26 wk. Early passage cells consisted of cuboidal cells with microvilli on their apical surface, complex basolateral membranes, numerous elongated mitochondria, and both free and membrane-bound ribosomes. Cell grown as monolayers for 3 mo. were more flattened and contained fewer apical microvilli, mitochondria, and profiles of rough surfaced endoplasmic reticulum; in addition, there were numerous autophagic vacuoles. Functional characteristics of differentiated pancreatic duct cells which were maintained during extended monolayer culture included intracellular levels of carbonic anhydrase and their capacity to generate cyclic AMP (cAMP) after stimulation by 1×10−6 M secretin. From 5 to 7 wk in culture, levels of carbonic anhydrase remained stable but after 25 to 26 wk decreased by 1.9-fold. At 5 to 7 wk of culture, cyclic AMP increased 8.7-fold over basal levels after secretin stimulation. Although pancreatic duct cells cultured for 25 to 26 wk showed lower basal levels of cAMP, they were still capable of generating significant levels of cAMP after exposure to serretin with a 7.0-fold increase, indicating that secretin receptors and the adenyl cyclase system were both present and functional. These experiments document that pancreatic duct monolayer cultures can be maintained in a differentiated state for up to 6 mo. and suggest that this culture system may be useful for in vitro physiologic and pathologic studies. This research was supported by grant CA34051 from the National Cancer Institute, Bethesda, MD.  相似文献   
85.
Summary We have developed an in vitro model of human papillary collecting duct cells isolated from cadaver kidneys using methods similar to those we previously reported for the isolation of human proximal tubule cells. To date we have isolated papillary collecting duct cells from 100 normal human kidneys. Papillae were dissected and digested in Cellgro containing 400 U/ml collagenase. Cells were plated on fibronectin-coated culture flasks at a density of 104 live cells/ml in Cellgro supplemented with insulin and 10% fetal bovine serum. Confluent monolayers, which were able to withstand 600 mOsm for 8 h, were obtained within 10 to 15 d. Cells of primary isolates and first passages exhibited epithelial cell ultrastructure including cell junctions, microvilli, and cilia. A dark-brown reaction product was observed in these cells when stained by the immunoperoxidase method with peroxidase-labeled peanut lectin (Arachis hypogaea), which binds specifically to human distal tubule and collecting duct cells. These cells were negative for Factor-VIII (a marker for endothelial cells) and γ-glutamyltransferase (a marker for proximal tubule cells). High activities of the glycolytic enzyme pyruvate kinase and arginine vasopressin-stimulated cAMP production in these cells are consistent with a distal nephron origin. The results indicate that human collecting duct cells can be isolated and cultured to provide an in vitro system to probe pathogenetic mechanisms of potential nephrotoxins. Part of this work was presented at a Symposium of the Center for Alternatives to Animal Testing, April 4–5, 1989, Johns Hopkins Medical Institutions, Baltimore, MD 21205. This work was supported in part by grants R01-AI24179, PO1-A804393 for the Public Health Service, U.S. Department of Health and Human Services, and by a grant from the National Kidney Foundation, Baltimore, MD affiliate.  相似文献   
86.
In this paper some examples of the development of communities of microorganisms and plants on historic buildings and montiments are shown. When the building stones differ from the surrounding natural substrata, an increase in the biological diversity of the area is produced. In some cases, monuments can come to constitute a true refuge for a few species when the natural habitat is threatened. It is suggested that biological diversity, when it does not represent a threat for the cultural heritage, should be considered worthy of preservation.  相似文献   
87.
反复电针对慢性痛的累加治疗作用及其机制研究   总被引:22,自引:0,他引:22  
罗非 《生理科学进展》1996,27(3):241-244
本研究从基础和临床两方面观察了反复电针对慢性痛的累加治疗作用,并结合疼痛患者及慢性痛动物模型中几种神经肽的放射免疫测定及相应受体拮抗剂的药理学研究结果,探讨了产生累加效应的可能机制。结果表明,在临床脊髓损伤性痉挛患者,100Hz穴位体表电刺激有效地缓解痉挛并有累加效应;在临床慢性痛患者,2/15Hz变频TENS刺激有效地治疗疼痛并具有累加效应。在关节炎模型大鼠,电针刺激能产生明显的镇痛并具有累加效  相似文献   
88.
Three routes were investigated for the conversion of d-glucose into the title compound. In the first approach, reduction of the 5,6-thürane ring of 5,6-dideoxy-5,6-epithio-1,2-O-isopropylidene α-d-glucofuranose (17) as well as that of its 3-O-allyl derivative (13) with lithium aluminium hydride was investigated; 17 afforded the corresponding 6-deoxy derivative besides di-, tri-, and poly-mers, whereas only polymers were formed from 13. In the second approach, the oxirane ring of was reduced by sodium borohydride and the resulting 6-deoxy derivative was converted into the 5-thiobenzoate; the corresponding hex-4-enofuranose was formed as a byproduct. In the third approach partial mesylation of methyl 5-thio-α-d-glucopyranoside was attempted, but the 6-mesylate 27 could be isolated only in modest yield (28%) together with rearranged 2,5-thioanhydromannofuranoside derivatives. The mechanism of this rearrangement is discussed in detail. The 6-mesylate 27 was converted via the 6-iodo derivative into the title compound.  相似文献   
89.
Transfer factor in chronic mucocutaneous candidiasis   总被引:3,自引:0,他引:3  
Fifteen patients suffering from chronic mucocutaneous candidiasis were treated with an in vitro produced TF specific for Candida albicans antigens and/or with TF extracted from pooled buffy coats of blood donors. CMI of the patients was assessed using the LMT and the LST in presence of candidine. The aim of the study was the clinical evaluation of TF treatment and the incidence of positive tests before, during, and after therapy. Immunological data were matched using the Chi square test. 87 LMT were performed for each antigen dose and at the dilution of 1/50, 58.9% (33/56) tests were positive during non-treatment or non-specific TF treatment. On the contrary 83.9% (26/31) were positive during specific TF treatment (P<0.05). In the LST, a significant decrease of thymidine uptake in the control cultures in presence of autologous or AB serum was observed when patients were matched according to non-treatment, and both non specific (P<0.05) and specific TF treatment (P<0.01). Only during specific TF treatment was a significant increase of reactivity against the Candida antigen at the highest concentration noticed, when compared with the period of non specific treatment (P<0.01). Clinical observations were encouraging: all but one patient experienced significant improvement during treatment with specific TF. These data confirm that orally administered specific TF, extracted from induced lymphoblastoid cell-lines, increases the incidence of reactivity against Candida antigens in the LMT. LST reactivity appeared not significantly increased with respect to the periods of non treatment, but was significantly increased when it was compared to the non-specific TF treatment periods. At the same time, a clinical improvement was noticed.  相似文献   
90.
Uptake and biliary excretion of metals were studied in rainbow trout, Oncorhynchus mykiss, exposed through spiked sediment to a mixture of seven heavy metals. Metal concentrations and toxicity of bile and blood plasma were used as indicators of exposure. Among the seven metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) only three (Cu, Hg, and Pb) were concentrated in the bile (bile-plasma ratio >1). Bile-plasma ratios in the rainbow trout were similar to those found in rats for Cu and Hg. Daphnia magna bioassays were used to determine toxicity of bile and blood plasma in the same trout. Toxicity of bile and blood plasma increased after treatment with acid. An analysis of variance (ANOVA) showed that toxicity of bile and blood plasma to D. magna in metal-exposed trout was significantly correlated with (1) bile and blood plasma test concentration, (2) acid treatment of bile and blood plasma (hydrolysis of metal-plasma and metal-bile complexes) and (3) sediment concentration of metals during exposure of trout. In order to significantly detect the magnitude of the exposure to a xenobiotic the biomarker must respond in a dose- or time-dependent manner. Therefore, the potential use of bile toxicity as a biomarker of heavy metal exposure in fish is probably limited by the low bioconcentration of many of these toxicants in bile.  相似文献   
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