998 resultados para Pre-synaptic Neurotoxin


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We present the results of the microstratigraphic, phytolith and wood charcoal study of the remains of a 10.5 ka roof. The roof is part of a building excavated at Tell Qarassa (South Syria), assigned to the Pre-Pottery Neolithic B period (PPNB). The Pre-Pottery Neolithic (PPN) period in the Levant coincides with the emergence of farming. This fundamental change in subsistence strategy implied the shift from mobile to settled aggregated life, and from tents and huts to hard buildings. As settled life spread across the Levant, a generalised transition from round to square buildings occurred, that is a trademark of the PPNB period. The study of these buildings is fundamental for the understanding of the ever-stronger reciprocal socio-ecological relationship humans developed with the local environment since the introduction of sedentism and domestication. Descriptions of buildings in PPN archaeological contexts are usually restricted to the macroscopic observation of wooden elements (posts and beams) and mineral components (daub, plaster and stone elements). Reconstructions of microscopic and organic components are frequently based on ethnographic analogy. The direct study of macroscopic and microscopic, organic and mineral, building components performed at Tell Qarassa provides new insights on building conception, maintenance, use and destruction. These elements reflect new emerging paradigms in the relationship between Neolithic societies and the environment. A square building was possibly covered here with a radial roof, providing a glance into a topologic shift in the conception and understanding of volumes, from round-based to square-based geometries. Macroscopic and microscopic roof components indicate buildings were conceived for year-round residence rather than seasonal mobility. This implied performing maintenance and restoration of partially damaged buildings, as well as their adaptation to seasonal variability

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This report documents abundance and cover for selected elements of the benthic coral reef assemblage at the site of the 1984 grounding of the M/V Wellwood on Molasses Reef, Florida Keys. The purpose of the effort was to establish a pre-construction baseline before the installation of reef modules at the site. The installation process is intended to stabilize fractured substrates that were recently exposed by storm impacts, and to provide three-dimensional relief in order to enhance reef community recovery. It is hoped that the restoration effort will result in a biological assemblage with the character of the transition community that would exist there had the incident not occurred. To date, the assemblage has developed the character of a comparatively featureless hard ground similar in composition to hard ground areas and transition zones surrounding the grounding site. These data will allow scientists and resource managers to better track the trajectory of recovery following the installation of modules. Direct counts of scleractinian and gorgonian corals, hydrocorals of the genus Millepora, and zoanthids of the genus Palythoa were made in three areas within and around the grounding site. The site is poorly developed with respect to scleractinian colony size and cover compared to surrounding areas. Key scleractinian species necessary for the development of topographic relief in the area denuded by the grounding are not well represented in the current community. Though gorgonian cover and richness is similar in all study areas, gorgonian community recovery in the damaged area is not complete. Unlike surrounding areas, one species, Pseudopterogorgia americana, accounts for over half of all corals at the grounding site, over 80% of all gorgonians, and nearly all the coral cover. Based on these findings and other observations made in the 18 years since the grounding, recommendations are made that should be considered in the course of human intervention targeted at stabilizing and enhancing the site. (PDF contains 24 pages.)

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(PDF contains 1 page.)

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(PDF contains 4 pages.)

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Objective: Due to the low bioavailability of resveratrol, determining whether its metabolites exert any beneficial effect is an interesting issue. Methods: 3T3-L1 maturing pre-adipocytes were treated during differentiation with 25 mu M of resveratrol or with its metabolites and 3T3-L1 mature adipocytes were treated for 24 hours with 10 mM resveratrol or its metabolites. The gene expression of adiponectin, leptin, visfatin and apelin was assessed by Real Time RT-PCR and their concentration in the incubation medium was quantified by ELISA. Results: Resveratrol reduced mRNA levels of leptin and increased those of adiponectin. It induced the same changes in leptin secretion. Trans-resveratrol-3-O-glucuronide and trans-resveratrol-4'-O-glucuronide increased apelin and visfatin mRNA levels. Trans-resveratrol-3-O-sulfate reduced leptin mRNA levels and increased those of apelin and visfatin. Conclusions: The present study shows for the first time that resveratrol metabolites have a regulatory effect on adipokine expression and secretion. Since resveratrol has been reported to reduce body-fat accumulation and to improve insulin sensitivity, and considering that these effects are mediated in part by changes in the analyzed adipokines, it may be proposed that resveratrol metabolites play a part in these beneficial effects of resveratrol.

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[EN]The generation of spikes by neurons is energetically a costly process and the evaluation of the metabolic energy required to maintain the signaling activity of neurons a challenge of practical interest. Neuron models are frequently used to represent the dynamics of real neurons but hardly ever to evaluate the electrochemical energy required to maintain that dynamics. This paper discusses the interpretation of a Hodgkin-Huxley circuit as an energy model for real biological neurons and uses it to evaluate the consumption of metabolic energy in the transmission of information between neurons coupled by electrical synapses, i.e., gap junctions. We show that for a single postsynaptic neuron maximum energy efficiency, measured in bits of mutual information per molecule of adenosine triphosphate (ATP) consumed, requires maximum energy consumption. For groups of parallel postsynaptic neurons we determine values of the synaptic conductance at which the energy efficiency of the transmission presents clear maxima at relatively very low values of metabolic energy consumption. Contrary to what could be expected, the best performance occurs at a low energy cost.

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Background: Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare neurodegenerative disorder in humans included in the group of Transmissible Spongiform Encephalopathies or prion diseases. The vast majority of sCJD cases are molecularly classified according to the abnormal prion protein (PrPSc) conformations along with polymorphism of codon 129 of the PRNP gene. Recently, a novel human disease, termed "protease-sensitive prionopathy", has been described. This disease shows a distinct clinical and neuropathological phenotype and it is associated to an abnormal prion protein more sensitive to protease digestion. Case presentation: We report the case of a 75-year-old-man who developed a clinical course and presented pathologic lesions compatible with sporadic Creutzfeldt-Jakob disease, and biochemical findings reminiscent of "protease-sensitive prionopathy". Neuropathological examinations revealed spongiform change mainly affecting the cerebral cortex, putamen/globus pallidus and thalamus, accompanied by mild astrocytosis and microgliosis, with slight involvement of the cerebellum. Confluent vacuoles were absent. Diffuse synaptic PrP deposits in these regions were largely removed following proteinase treatment. PrP deposition, as revealed with 3F4 and 1E4 antibodies, was markedly sensitive to pre-treatment with proteinase K. Molecular analysis of PrPSc showed an abnormal prion protein more sensitive to proteinase K digestion, with a five-band pattern of 28, 24, 21, 19, and 16 kDa, and three aglycosylated isoforms of 19, 16 and 6 kDa. This PrPSc was estimated to be 80% susceptible to digestion while the pathogenic prion protein associated with classical forms of sporadic Creutzfeldt-Jakob disease were only 2% (type VV2) and 23% (type MM1) susceptible. No mutations in the PRNP gene were found and genotype for codon 129 was heterozygous methionine/valine. Conclusions: A novel form of human disease with abnormal prion protein sensitive to protease and MV at codon 129 was described. Although clinical signs were compatible with sporadic Creutzfeldt-Jakob disease, the molecular subtype with the abnormal prion protein isoforms showing enhanced protease sensitivity was reminiscent of the "protease-sensitive prionopathy". It remains to be established whether the differences found between the latter and this case are due to the polymorphism at codon 129. Different degrees of proteinase K susceptibility were easily determined with the chemical polymer detection system which could help to detect proteinase-susceptible pathologic prion protein in diseases other than the classical ones.

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32 Proben verpackten Frischfischs in Selbstbedienungspackungen, 16 Seelachs- und 16 Rotbarschproben aus deutschen Supermärkten wurden mit physikalischen, chemischen, mikrobiellen und sensorischen Methoden untersucht. Ziel der Untersuchung war dieWertung von Untersuchungsmethoden zur Qualitätsbestimmung. Es zeigte sich, daß neben der sensorischen Beurteilung die Bestimmung des TVB-N geeignet ist, die Qualität dieser Produkte zu beurteilen.

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This survey was carried out to provide the Kainji Lake Fisheries Promotion Project (KLFPP), whose overall goal is the improvement of the standard of living of fishing communities around Kainji Lake, Nigeria, and an increase in the availability of fish to consumers, with nutritional status baseline data for long-term monitoring and evaluation of the overall project goal. In a cross-sectional survey, baseline anthropometric data was collected from 768 children, aged 3-60 months in 389 fisherfolk households around the southern sector of Kainji Lake, Nigeria. In addition, data was collected on the nutritional status and fertility of the mothers, vaccination coverage of children and child survival indicators. For control purposes, 576 children and 292 mothers from non-fishing households around Kainji Lake were likewise covered by the survey. A standardised questionnaire was used to collect relevant information, while anthropometric measurements were made using appropriate equipment. Data compilation and analysis was carried out with DATAEASE registered and EPI-INFO registered software, using NCHS reference data for the analysis of anthropometric measurements. The prevalence of stunted children in fishing households was high at 40%, while the prevalence of wasted and underweight children was likewise high at 10% and 29% respectively. Children from non-fishing households had a marginally lower prevalence of stunting, wasting and underweight with 37%, 7% and 25 % respectively, although these differences were not statistically significant. Considering the fact that the survey was carried out during a period of relative food abundance, the prevalence of wasting and underweight children is likely to be much higher during periods of food shortage. The prevalence of stunting, wasting and underweight was relatively high for children aged 3 to 23 months, suggesting an increased risk of malnutrition during this period, most likely associated with inadequate weaning practices. The prevalence of malnourishment amongst women of child-bearing age was relatively high, irrespective of occupation of the household, with an average of 11% undernourished and 6% wasted. Vaccination coverage was very low while infant and child mortality were extremely high with about 1 in 5 children dying before their fifth birthday. Based on the ethical obligation to maximise the potential benefits of the survey, recommendations for activities to improve community nutrition and health were made for communication to relevant authorities. (PDF contains 52 pages)

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This survey was carried out to provide the Kainji Lake Fisheries Promotion Project (KLFPP), whose overall goal is the improvement of the standard of living of fishing communities around Kainji Lake, Nigeria, managing the fisheries on a sustainable basis, with follow-up data for long-term monitoring and evaluation of the overall project goal. A similar survey, conducted in 1996, provided the baseline against which data from the current survey was evaluated. In a cross-sectional survey, anthropometric data was collected from 576 children aged 3-60 months in 282 fisherfolk households around the southern sector of Kainji Lake, Nigeria. In addition, data was collected on the nutritional status and fertility of the mothers, vaccination coverage of children and child survival indicators. For control purposes, 374 children and 181 mothers from non-fishing households around Kainji Lake were likewise covered by the survey. A standardised questionnaire was used to collect relevant data, while anthropometric measurements were made using appropriate equipment. Data compilation and analysis was carried out with a specially designed Microsoft Access application, using NCHS reference data for the analysis of anthropometric measurements. Statistical significance testing was done using EPI-INFO" software. The results of the follow-up survey indicate a slight increase in the percentage of stunted pre-school children in fishing households around Kainji Lake, from 40% in 1996 to 41% in 1999. This increase is however not statistically significant (p= 0.704). Over the same period, the percentage of stunted children in non-fishing households increased from 37% to 39% (p= 0.540), which is also not statistically significant. Likewise, there were no statistically significant differences between the 1996 and 1999 results for the prevalence of either wasted or underweight children in fishing households. The same applies to children from non-fishing households. In addition, vaccination coverage remains very low while infant and child mortality rates continue to be extremely high with about 1 in 5 children dying before their fifth birthday. There has been no perceptible and lasting improvement in the standard of living of fishing households over the course of the second project phase as indicated by the persistently high prevalence of stunting. The situation is the same for the control group, indicating that for the region as a whole, a number of factors beyond the immediate influence of the project continue to negatively impact on the standard of living. The results also show that the project activities have not had any negative long-term effect on the nutritional status of the beneficiaries. (PDF contains 44 pages)

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This thesis presents a biologically plausible model of an attentional mechanism for forming position- and scale-invariant representations of objects in the visual world. The model relies on a set of control neurons to dynamically modify the synaptic strengths of intra-cortical connections so that information from a windowed region of primary visual cortex (Vl) is selectively routed to higher cortical areas. Local spatial relationships (i.e., topography) within the attentional window are preserved as information is routed through the cortex, thus enabling attended objects to be represented in higher cortical areas within an object-centered reference frame that is position and scale invariant. The representation in V1 is modeled as a multiscale stack of sample nodes with progressively lower resolution at higher eccentricities. Large changes in the size of the attentional window are accomplished by switching between different levels of the multiscale stack, while positional shifts and small changes in scale are accomplished by translating and rescaling the window within a single level of the stack. The control signals for setting the position and size of the attentional window are hypothesized to originate from neurons in the pulvinar and in the deep layers of visual cortex. The dynamics of these control neurons are governed by simple differential equations that can be realized by neurobiologically plausible circuits. In pre-attentive mode, the control neurons receive their input from a low-level "saliency map" representing potentially interesting regions of a scene. During the pattern recognition phase, control neurons are driven by the interaction between top-down (memory) and bottom-up (retinal input) sources. The model respects key neurophysiological, neuroanatomical, and psychophysical data relating to attention, and it makes a variety of experimentally testable predictions.

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Pre-mRNA splicing requires interaction of cis- acting intron sequences with trans -acting factors: proteins and small nuclear ribonucleoproteins (snRNPs). The assembly of these factors into a large complex, the spliceosome, is essential for the subsequent two step splicing reaction. First, the 5' splice site is cleaved and free exon 1 and a lariat intermediate (intron- exon2) form. In the second reaction the 3' splice site is cleaved the exons ligated and lariat intron released. A combination of genetic and biochemical techniques have been used here to study pre-mRNA splicing in yeast.

Yeast introns have three highly conserved elements. We made point mutations within these elements and found that most of them affect splicing efficiency in vivo and in vitro, usually by inhibiting spliceosome assembly.

To study trans -acting splicing factors we generated and screened a bank of temperature- sensitive (ts) mutants. Eleven new complementation groups (prp17 to prp27) were isolated. The four phenotypic classes obtained affect different steps in splicing and accumulate either: 1) pre-mRNA, 2) lariat intermediate, 3) excised intron or 4) both pre-mRNA and intron. The latter three classes represent novel phenotypes. The excised intron observed in one mutant: prp26 is stabilized due to protection in a snRNP containing particle. Extracts from another mutant: prpl8 are heat labile and accumulate lariat intermediate and exon 1. This is especially interesting as it allows analysis of the second splicing reaction. In vitro complementation of inactivated prp18 extracts does not require intact snRNPs. These studies have also shown the mutation to be in a previously unknown splicing protein. A specific requirement for A TP is also observed for the second step of splicing. The PRP 18 gene has been cloned and its polyadenylated transcript identified.

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