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101.
102.
Neurotoxic Effect of Intranigral Injection of 1-Methyl-4-Phenylpyridinium on GABA-Containing Neurons and Its Relation to Circling Behavior 总被引:1,自引:0,他引:1
Abstract: The ionic species 1-methyl-4-phenylpyridinium (MPP+ ) seems to be the metabolite responsible for the damage to dopaminergic neurons occurring after administration of the parkinsonian drug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. In the present study we show that the unilateral stereotaxic microinjection of MPP+ into the substantia nigra pars reticulata in rats produces immediately intense and long-lasting (up to 96 h) contralateral turning behavior in a dose-dependent manner. This behavioral effect was correlated with a dose- and time-dependent decrease (up to 90%) of glutamate decarboxylase activity and with a notable loss of neurons in the injected nigra reticulata. GABA levels in the injected nigra were also decreased, whereas the dopamine concentration in the ipsilateral striatum was not affected at 24 h, when maximal behavioral effects were observed. The circling behavior was prevented by the dopamine carrier blocker nomifensine only during the first 2 h, whereas the dopamine receptor antagonist haloperidol was ineffective. The results indicate that MPP+ is toxic for inhibitory GABAergic neurons in the nigra pars reticulata and, furthermore, suggest that disruption of the function of these GABAergic neurons may be involved in the abnormal motor behavior produced by the injection of MPP+ in the substantia nigra. 相似文献
103.
Ricardo Godoy Nicholas Brokaw David Wilkie 《Human ecology: an interdisciplinary journal》1995,23(1):29-52
We use microeconomic theory to frame hypotheses about the effects of income on the use of non-timber rain forest products. We hypothesize that an increase in income: (a) encourages foraging specialization, resulting in the extraction of fewer goods; (b) increases the share of household income from occupations besides foraging; (c) produces a yearly value from the extraction of nontimber forest goods of about $50 per hectare; and (d) produces depletion of forest goods entering commercial channels and sustainable extraction of goods facing cheaper industrial substitutes. To examine these hypotheses we present worldwide ethnographic information and preliminary findings from field work carried out among the Sumu Indians of Nicaragua. Field work suggests that higher income produces: (a) foraging specialization with animals rather than with plants; (b) a decline in the economic importance of forest goods in household income; (c) and a rise in the value of non-timber goods removed from the forest to about $35/ha/year. We did not have time to test hypothesis d. 相似文献
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Summary The main features of the behavioural ecology of rocky intertidal species are compared both within families — though concentrated on blennies — and between habitats. It is suggested that, at the behavioural level, the reduction of vertical and swimming elements in the male sexual and agonistic displays of Blennioidei may constitute an adaptation to typical intertidal conditions, especially in those species that inhabit areas exposed to strong wave action. The other aspect which is discussed is the prevalence of parental care in rocky intertidal fishes. In these fishes parental care is much more frequent than for marine fishes as a whole. Taken alone, this could also suggest that guarding evolved as an adaptation during the process of colonization of these habitats. The hypothesis proposed in this paper is that guarding was already present in the ancestors of the resident species, at least in the majority of cases. Many differences in interhabitat studies may express the action of the environment, not as an agent of natural selection, but as a filter, which prevented some groups from invading a given habitat and, at the same time, made colonization easier for other groups. When a number of taxa that colonized a given habitat display clear similarities in their behaviour and their biology, adaptation is not necessarily demonstrated. There is evidence in the literature to support the hypothesis that those traits were already present in the ancestors of the rocky intertidal resident fishes, thus being best viewed as exaptations. 相似文献
106.
Ricardo A. Margni 《Glycoconjugate journal》1984,1(1):59-66
IgG asymmetric antibodies are synthesized by the same cellular clones as the symmetric ones but appear in the immune response in different proportions. The evidence suggests that they are caused by asymmetric glycosylation on some IgG molecules in the Fab region. The cause of this is unknown but it could be speculated that there are cellular factors that induce glycosyl transferases or cause the molecule to be more accessible to glycosylation. The production of asymmetric antibodies can be modified by the physical status (soluble or particulate) of the antigen used as immunogen by the number and frequency of stimulation, and by physiological factors such as the ones secreted by the placenta and by lymphocytes that express progesterone receptors in response to hormone. An increase of these antibodies can be beneficial or harmful to the host, depending on the situation in which they act and the character of self or non-self of the antigens recognized.
Editors note—Many of the ideas proposed in this article are very speculative, but it was thought appropriate to publish it in order to stimulate further discussion of the subject. It is an interesting role for Fab glycosylation that is proposed by Professor Margni. The ideas discussed are not necessarily those held by the Editorial Board or the reviewers, who felt that the evidence for many of the deductions made was very limited. It was also emphasized by the reviewers that the author's case would be substantially improved if more corroborative evidence was available from other groups. The Editors would welcome any comments on the subject for publication in future issues of the journal. 相似文献
107.
Ricardo A. Godoy 《Human ecology: an interdisciplinary journal》1984,12(4):359-383
Andean cultural ecologists have made two claims in recent years: ecological decomposition is absent due to effective indigenous management of communal resources, and agricultural intensification is inversely related to altitude. Drawing on material from the Jukumani Indians of Northern Potosi, Bolivia, these assertions are challenged. First, there is little evidence to prove or disprove ecological degradation. Second, the location of agricultural intensification, as the Jukumani data suggests, is influenced by altitude as well as by the presence of market.Fieldwork in Bolivia was carried out between January 1979 and May 1981. This essay was originally presented at a conference entitled, How Communities Resolve Common Property Problems, sponsored by the Harvard Institute for International Development and the Center for Population Studies of Harvard University in the spring semester of 1983. 相似文献
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110.
Marden A. de Alvarenga Raimundo Braz Fo Otto R. Gottlieb João P. de P. Dias Aderbal F. Magalhães Eva G. Magalhães Gouvan C. de Magalhães Mauro T. Magalhães José G.S. Maia Raquel Marques Anita J. Marsaioli Antônio A.L. Mesquita Anselmo A. de Moraes Alaide B. de Oliveira Geovane G. de Oliveira Gentil Pedreira Sebastião K. Pereira Sonildes L.V. Pinho Celira C. Santos 《Phytochemistry》1978,17(3):511-516
Wood samples, infested by fungi during storage, were shown to contain, besides the known 5-methyl-mellein, additional (3R)-8-hydroxy-3-methyl-3,4-dihydroisocoumarins substituted by 7-methyl, 5-formyl, 5-carboxy, 5-hydroxy, 5-methoxy, 6-methoxy-5-methyl and 6,7-dimethoxy-5-methyl groups, as well as 6-formyl-7-hydroxy-5-methoxy-4-methylphthalide. Several 2-methylchromanones were synthesized in order to show that this class of compounds can be distinguished from 3-methyl-3,4-dihydroisocoumarins by MS. 相似文献