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1.
Allergy ; 72(9): 1423-1429, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28328103

RESUMO

Food allergies are recognized as an increasing health concern. Proteins commonly identified as food allergens tend to have one of about 30 different biochemical activities. This leads to the assumption that food allergens must have specific structural features which causes their allergenicity. But these structural features are not completely understood. Uncovering the structural basis of allergenicity would allow improved diagnosis and therapy of allergies and would provide insights for safer food production. The availability of recombinant food allergens can accelerate their structural analysis and benefit specific studies in allergology. Plant chitinases are an example of food allergenic proteins for which structural analysis of allergenicity has only partially been reported. The recombinant maize chitinase, rChiA, was purified from Pichia pastoris extracellular medium by differential precipitation and cation exchange chromatography. Enzyme activity was evaluated by halo-assays and microcalorimetric procedures. rChiA modeling was performed by a two-step procedure, using the Swiss-Model server and Modeller software. Allergenicity of rChiA was verified by immunoblot assays with sera from allergic subjects. rChiA is active in the hydrolysis of glycol chitin and tetra-N-acetylchitotetraose and maintains its activity at high temperatures (70°C) and low pH (pH 3). The molecule is also reactive with IgE from sera of maize-allergic subjects. rChiA is a valuable molecule for further studies on structure-allergenicity relationships and as a tool for diagnosing allergies.


Assuntos
Antígenos de Plantas/imunologia , Quitinases/imunologia , Hipersensibilidade Alimentar , Alérgenos , Quitinases/química , Quitinases/isolamento & purificação , Humanos , Imunoglobulina E , Pichia , Proteínas de Plantas/imunologia , Proteínas Recombinantes/química , Relação Estrutura-Atividade , Zea mays
2.
Transl Psychiatry ; 6(10): e921, 2016 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-27754482

RESUMO

The ability to predict psychiatric readmission would facilitate the development of interventions to reduce this risk, a major driver of psychiatric health-care costs. The symptoms or characteristics of illness course necessary to develop reliable predictors are not available in coded billing data, but may be present in narrative electronic health record (EHR) discharge summaries. We identified a cohort of individuals admitted to a psychiatric inpatient unit between 1994 and 2012 with a principal diagnosis of major depressive disorder, and extracted inpatient psychiatric discharge narrative notes. Using these data, we trained a 75-topic Latent Dirichlet Allocation (LDA) model, a form of natural language processing, which identifies groups of words associated with topics discussed in a document collection. The cohort was randomly split to derive a training (70%) and testing (30%) data set, and we trained separate support vector machine models for baseline clinical features alone, baseline features plus common individual words and the above plus topics identified from the 75-topic LDA model. Of 4687 patients with inpatient discharge summaries, 470 were readmitted within 30 days. The 75-topic LDA model included topics linked to psychiatric symptoms (suicide, severe depression, anxiety, trauma, eating/weight and panic) and major depressive disorder comorbidities (infection, postpartum, brain tumor, diarrhea and pulmonary disease). By including LDA topics, prediction of readmission, as measured by area under receiver-operating characteristic curves in the testing data set, was improved from baseline (area under the curve 0.618) to baseline+1000 words (0.682) to baseline+75 topics (0.784). Inclusion of topics derived from narrative notes allows more accurate discrimination of individuals at high risk for psychiatric readmission in this cohort. Topic modeling and related approaches offer the potential to improve prediction using EHRs, if generalizability can be established in other clinical cohorts.


Assuntos
Transtorno Depressivo Maior/diagnóstico , Transtorno Depressivo Maior/terapia , Registros Eletrônicos de Saúde , Narração , Processamento de Linguagem Natural , Sumários de Alta do Paciente Hospitalar , Readmissão do Paciente , Adulto , Idoso , Estudos de Coortes , Transtorno Depressivo Maior/psicologia , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Massachusetts , Pessoa de Meia-Idade , Modelos Estatísticos , Medição de Risco , Fatores de Tempo
3.
J Comp Neurol ; 325(2): 207-18, 1992 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-1281173

RESUMO

In this report the normal dendritic organization and fine structure of identified septohippocampal projection neurons is described as a prerequisite for a time course analysis of retrograde changes in these neurons following axotomy (see Naumann et al., J. Comp. Neurol. 325:219-242, 1992). Septohippocampal projection neurons were retrogradely labeled by injection of the fluorescent tracer Fluoro-Gold into the hippocampus. Next, retrogradely labeled cells in Vibratome sections of the medial septum/diagonal band complex were intracellularly stained with the fluorescent dye Lucifer Yellow (LY). Photooxidation of LY resulted in a stable electron-dense reaction product, which allowed us to study these double-labeled neurons by electron microscopy. Another series of sections containing retrogradely labeled neurons were immunostained for choline acetyltransferase (ChAT) or parvalbumin (PARV). In this way the fine structure of two different chemically characterized subpopulations of septohippocampal neurons could be compared with that of the LY-injected neurons. Intracellular filling of retrogradely labeled neurons with LY stained the cell body and the entire dendritic arbor. Essentially, three classes of neurons could be distinguished, i.e., bipolar cells, multipolar neurons, and an intermediate group. All these neurons displayed smooth, often varicose dendrites lacking spines. Mainly located close to the midline, there was a group of cells with only very few if any LY-stained dendrites. In the electron microscope, the double-labeled neurons were easily identified by numerous electron-dense lysosomes associated with transported Fluoro-Gold and the diffuse reaction product resulting from photooxidation. They displayed fine-structural characteristics as previously described for cholinergic neurons. In fact, our fine-structural analysis of ChAT-positive Fluoro-Gold-labeled neurons, but also of back-filled PARV-positive cells, gave very similar results. All these neurons had infolded nuclei, abundant cytoplasmic organelles, and a few axosomatic synapses. Thus, a plain electron microscopic study does not allow one to distinguish between subpopulations of septohippocampal projection neurons.


Assuntos
Hipocampo/química , Hipocampo/ultraestrutura , Neurônios Aferentes/química , Neurônios Aferentes/ultraestrutura , Núcleos Septais/química , Núcleos Septais/ultraestrutura , Estilbamidinas , Animais , Colina O-Acetiltransferase/química , Colina O-Acetiltransferase/imunologia , Feminino , Corantes Fluorescentes , Imuno-Histoquímica , Isoquinolinas , Masculino , Microscopia Imunoeletrônica , Parvalbuminas/química , Parvalbuminas/imunologia , Ratos , Ratos Sprague-Dawley , Coloração e Rotulagem
4.
J Comp Neurol ; 350(2): 161-70, 1994 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-7884035

RESUMO

Most cholinergic projection neurons in the medial septal nucleus (MS) lose their capability to synthesize choline acetyltransferase (ChAT) after axotomy by bilateral fimbria-fornix transection. We have recently shown that identified septohippocampal neurons survive axotomy up to 10 weeks and display fine-structural characteristics of cells in control rats. However, the fate and functional role of these neurons remained unclear. Here we describe observations made in rats which survived axotomy for 6 months. Adult Sprague-Dawley rats were subjected to bilateral transection of the fimbria-fornix system. In some animals septohippocampal projection neurons were labeled by the retrograde fluorescent tracer Fluoro-Gold (FG) prior to axotomy. After varying survival times following fimbria-fornix transection, the animals were fixed and sections of the septal region immunostained for ChAT. Three weeks postlesion, the number of ChAT-positive cells in the MS was reduced to 19% of control, suggesting a severe neuronal loss. However, 10 weeks and 6 months after axotomy this value increased to 28% and 54%, respectively. Fine-structural analysis of ChAT-positive neurons after 6 months survival revealed all characteristics of vital cells including normal input synapses. The majority of these cells could be identified as former septohippocampal projection neurons by the presence of FG. We conclude that many neurons in the MS have the capacity to restore their transmitter synthesis in a long-lasting process following axotomy.


Assuntos
Colina O-Acetiltransferase/análise , Hipocampo/ultraestrutura , Neurônios/ultraestrutura , Septo Pelúcido/ultraestrutura , Estilbamidinas , Animais , Vias Eferentes/fisiologia , Feminino , Corantes Fluorescentes , Imuno-Histoquímica , Masculino , Microscopia Eletrônica , Ratos , Ratos Sprague-Dawley
5.
J Comp Neurol ; 362(3): 385-99, 1995 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-8576446

RESUMO

Many septohippocampal neurons are GABAergic and are affected by transection of the fimbria-fornix, like the septohippocampal cholinergic cells. Here we have studied the changes that occur in GABAergic septohippocampal neurons following fimbria-fornix transection. For labeling of septohippocampal projection neurons, adult Sprague-Dawley rats received injections of the fluorescent tracer Fluoro-Gold into the hippocampus 1 week prior to bilateral transection of the fimbria-fornix. After axotomy, rats were allowed to survive for varying periods ranging from 3 weeks to 18 months. Following fixation of the animals, sections through the septal region were either stained by in situ hybridization for glutamate decarboxylase (GAD) mRNA or immunostained for parvalbumin (PARV), which is known to be present in GABAergic septohippocampal neurons. In situ hybridization for GAD mRNA revealed no statistically significant changes in cell number 3 weeks and 6 months postlesion. In contrast, PARV-immunoreactive neurons were reduced to 35% of control 3 weeks postlesion. This value increased to 66% after 6 months of survival. As seen in the electron microscope, axotomized PARV-positive neurons exhibited characteristics of vital cells. Most neurons contained lysosomes associated with Fluoro-Gold, resulting from retrograde labeling prior to fimbria-fornix transection. We conclude that mainly PARV-containing GABAergic neurons in the medial septal nucleus (MS) project to the hippocampus and are thus heavily affected by the lesion but are able to survive and restore the synthesis of PARV. The lack of significant changes in the number of GAD mRNA-expressing cells is explained by the presence of numerous GABAergic MS neurons not projecting to the hippocampus.


Assuntos
Glutamato Descarboxilase/genética , Hipocampo/citologia , Neurônios/enzimologia , Parvalbuminas/análise , Núcleos Septais/citologia , Estilbamidinas , Ácido gama-Aminobutírico/fisiologia , Animais , Especificidade de Anticorpos , Axônios/fisiologia , Corantes Fluorescentes , Hipocampo/enzimologia , Hipocampo/cirurgia , Imuno-Histoquímica , Hibridização In Situ , Microinjeções , Microscopia Eletrônica , Neurônios/química , Neurônios/ultraestrutura , Parvalbuminas/imunologia , RNA Mensageiro/análise , Ratos , Ratos Sprague-Dawley , Núcleos Septais/enzimologia , Núcleos Septais/cirurgia
6.
J Comp Neurol ; 325(2): 219-42, 1992 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-1460114

RESUMO

Previous light microscopic immunocytochemical studies with antibodies against transmitter-synthesizing enzymes have suggested that septohippocampal neurons undergo retrograde degeneration following transection of their axons by cutting the fimbria-fornix. However, a fine-structural analysis of the degeneration process in these cells is lacking so far. Here we have identified septohippocampal neurons by retrograde tracing with Fluoro-Gold. Thereafter, the fimbria-fornix was transected bilaterally. Fine-structural changes in prelabeled septohippocampal neurons were then studied after varying survival times up to 10 weeks. Examination under the fluorescence microscope of Vibratome sections through the septal region revealed numerous retrogradely labeled cells after all survival times following axotomy. These neurons were then intracellularly injected with the fluorescent dye Lucifer Yellow in order to stain their dendritic arbor. Many cells were found after each survival time that displayed characteristics of septohippocampal neurons in control rats (see Naumann et al., J Comp Neurol 325:207-218, 1992). In addition, increasing with survival time, there were many shrunken neurons with a reduced dendritic arbor. Representative examples of both normal appearing and shrunken neurons were photoconverted for subsequent electron microscopic analysis. Relatively few signs of neuronal degeneration were found at each survival time analyzed. The majority of cells, including the heavily shrunken ones, displayed fine-structural characteristics of normal neurons. However, a few degenerating neurons and reactive glial cells were present in all survival stages. We conclude that axotomized septohippocampal projection neurons cease the expression of transmitter-synthesizing enzymes and shrink, but many more cells survive for extended periods of time without target-derived neurotrophic factor than was assumed in previous light microscopic studies.


Assuntos
Axônios/fisiologia , Hipocampo/ultraestrutura , Degeneração Neural/fisiologia , Neurônios/ultraestrutura , Núcleos Septais/ultraestrutura , Animais , Feminino , Hipocampo/citologia , Histocitoquímica , Isoquinolinas , Neurônios/citologia , Ratos , Ratos Sprague-Dawley , Núcleos Septais/citologia , Fixação de Tecidos
7.
J Comp Neurol ; 379(4): 467-81, 1997 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-9067837

RESUMO

During normal development of the nervous system, the target fields influence the survival and differentiation of projection neurons, but the factors regulating this interaction remain obscure. In the present study, we have raised the question whether the target region is essential for the postnatal development and maintenance of two different types of central projection neurons, cholinergic and GABAergic septohippocampal cells. In early postnatal rats (P5, P10), the hippocampus was eliminated by unilateral intrahippocampal injections of the excitotoxin N-methyl-D-aspartate. After a long survival time (at P70), we have immunostained serial sections of the septal region with antibodies against choline acetyltransferase (ChAT), the acetylcholine-synthesizing enzyme, or the calcium-binding protein parvalbumin (PARV) which is known to be contained in GABAergic septohippocampal neurons. In the medial septum ipsilateral to the lesioned side, about 60% of ChAT-immunoreactive neurons and 62% of PARV-immunoreactive neurons were found in adulthood even after complete elimination of the hippocampus. Some immunoreactive cells appeared heavily shrunken, but electron microscopic analysis revealed ultrastructural characteristics typical for medial septal neurons obtained from controls. Our results indicate that target elimination during development affected both types of projection cells, although only the cholinergic cells are known to be responsive to target-derived factors.


Assuntos
Colina O-Acetiltransferase/análise , Hipocampo/química , Proteínas do Tecido Nervoso/análise , Neurônios/química , Septo Pelúcido/química , Ácido gama-Aminobutírico/análise , Animais , Feminino , Hipocampo/citologia , Hipocampo/crescimento & desenvolvimento , Imuno-Histoquímica , Masculino , Microscopia Eletrônica , N-Metilaspartato/farmacologia , Parvalbuminas/análise , Ratos , Ratos Sprague-Dawley , Septo Pelúcido/citologia , Septo Pelúcido/crescimento & desenvolvimento
8.
J Comp Neurol ; 372(2): 204-14, 1996 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-8863126

RESUMO

In the present study, we have investigated the developmental expression of the transmitter-synthesizing enzymes choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) in rat medial septal neurons by using in situ hybridization histochemistry. In addition, we have employed immunostaining for ChAT and the calcium-binding protein parvalbumin, known to be contained in septohippocampal GABAergic neurons. A large number of GAD67 mRNA-expressing neurons were already observed in the septal complex on embryonic day (E) 17, the earliest time point studied. During later developmental stages, there was mainly an increase in the intensity of labeling. Neurons expressing ChAT mRNA were first recognized at E 20, and their number slowly increased during postnatal development of the septal region. The adult pattern of ChAT mRNA-expressing neurons was observed around postnatal day (P) 16. By using a monoclonal ChAT antibody, the first immunoreactive cells were not seen before P 8. Similarly, the first weakly parvalbumin-immunoreactive neurons were seen in the septal complex by the end of the 1st postnatal week. These results indicate that in situ hybridization histochemistry may be an adequate method to monitor the different development of transmitter biosynthesis in cholinergic and GABAergic septal neurons. Moreover, the late onset of ChAT mRNA expression would be compatible with a role of target-derived factors for the differentiation of the cholinergic phenotype.


Assuntos
Colina O-Acetiltransferase/metabolismo , Fibras Colinérgicas/metabolismo , Glutamato Descarboxilase/metabolismo , Núcleos Septais/crescimento & desenvolvimento , Ácido gama-Aminobutírico/metabolismo , Animais , Feminino , Imuno-Histoquímica , Hibridização In Situ , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley
9.
J Comp Neurol ; 390(4): 481-96, 1998 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-9450531

RESUMO

Studies of postlesional microglial activation may gain insight into microglia/neuronal interactions in processes of neurodegeneration. We compared the microglial response after axotomy of septohippocampal projection neurons with that seen after selective immunolesioning of cholinergic septohippocampal neurons with the immunotoxin 192 IgG-saporin. Using the microglial marker isolectin B4 from Griffonia simplicifolia (GSA I-B4), we found striking differences in the microglial response between these two lesion paradigms. Following axotomy of septohippocampal neurons by fimbria-fornix transection (ff-t), there was only a moderate and short-lasting microglial reaction in the medial septum (MS) in the early postlesion period. Prelabeling of septohippocampal neurons with Fluoro-Gold (FG) prior to axotomy revealed the survival of most neurons, and only very rarely were microglial cells observed that had phagocytosed FG-labeled debris. In the lateral septum (LS) containing the degenerating terminals of hippocamposeptal fibers transected by ff-t, a heavy reaction of lectin-labeled activated microglial cells associated with high phagocytotic activity was noticed. Unexpectedly, after a long survival time (6 months) following ff-t, we observed an increase in microglial GSA I-B4 labeling in the MS. In contrast, an inverse pattern of the microglial response, i.e., a strong initial reaction in the MS and very little microglial activation in the LS, was observed after immunolesioning. Our results indicate that the microglial reaction in the MS following ff-t differs substantially from that seen in other models of axotomy.


Assuntos
Hipocampo/fisiologia , Microglia/fisiologia , Neurônios/fisiologia , Septo Pelúcido/fisiologia , Estilbamidinas , Animais , Anticorpos Monoclonais , Axotomia , Denervação , Corantes Fluorescentes , Imunotoxinas , N-Glicosil Hidrolases , Vias Neurais/fisiologia , Ratos , Ratos Sprague-Dawley , Proteínas Inativadoras de Ribossomos Tipo 1 , Saporinas
10.
Neuroscience ; 80(3): 731-9, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9276489

RESUMO

After unilateral entorhinal cortex lesion cholinergic septohippocampal fibres sprout in the denervated fascia dentata. This process is dependent on neurotrophin changes following the lesion. Thus, there is an up-regulation of nerve growth factor and brain-derived neurotrophic factor messenger RNA expression in the denervated granule cells which is detectable 4 h postlesion and returns to control levels by 24 h. Here, using a competitive polymerase chain reaction and in situ hybridization, a transient neurotropin messenger RNA increase could be demonstrated bilaterally following unilateral electrolytic entorhinal cortex lesion. Treatment of the animals with the N-methyl-D-aspartate receptor antagonist dizocilpine maleate blocked this messenger RNA increase, suggesting an involvement of this receptor type in the neurotrophin changes. However, in spite of this blockade, the typical cholinergic sprouting response as visualized with acetylcholinesterase histochemistry was present in animals four weeks after entorhinal cortex lesion. These data suggest that brief initial changes in neurotrophin messenger RNA expression in dentate granule cells are not responsible for the induction of the cholinergic sprouting. Changes in neurotrophin messenger RNA expression occurring immediately postlesion may be linked to glutamate release from entorhinal terminals resulting from the electrolytic lesion of the projection cells in the entorhinal cortex. We hypothesize that later changes in neurotrophin expression, for example in glial cells, are more likely to be related to the cholinergic sprouting process.


Assuntos
Acetilcolinesterase/análise , Fator Neurotrófico Derivado do Encéfalo/biossíntese , Giro Denteado/fisiologia , Córtex Entorrinal/fisiologia , Fibras Nervosas/fisiologia , Fatores de Crescimento Neural/biossíntese , Transcrição Gênica , Animais , Denervação , Giro Denteado/efeitos dos fármacos , Maleato de Dizocilpina/farmacologia , Eletrocoagulação , Lateralidade Funcional , Hibridização In Situ , Fibras Nervosas/efeitos dos fármacos , Reação em Cadeia da Polimerase , RNA Mensageiro/biossíntese , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores
11.
Neuroscience ; 81(3): 829-46, 1997 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9316032

RESUMO

The extracellular matrix protein tenascin-C has been implicated in the regulation of axonal growth. Using unilateral entorhinal cortex lesions, which induce a massive sprouting response in the denervated outer molecular layer of the rat fascia dentata, the role of tenascin-C for axonal growth was investigated in vivo. Monoclonal antibodies against the neurite outgrowth and anti-adhesive domains of the molecule were employed. Immunostaining was increased throughout the denervated outer molecular layer by day 2, reached a maximum around day 10, and was back to control levels by four weeks post lesion. Growth cone deflecting as well as neurite outgrowth promoting isoforms of tenascin-C were up-regulated after the lesion. Using electron microscopy, single intensely tenascin-C immunoreactive cells were identified as reactive astrocytes that phagocytose degenerated terminals. In situ hybridization histochemistry for tenascin-C messenger RNA revealed numerous cellular profiles in the denervated outer molecular layer of the ipsilateral and contralateral dentate gyrus two days post lesion. Tenascin-C messenger RNA-positive cells in the outer molecular layer were identified as astrocytes using double-labelling for tenascin-C messenger RNA and glial fibrillary acidic protein immunohistochemistry. Thus, a tenascin-C-rich substrate is present in the outer molecular layer during the time of sprouting and a sharp boundary is formed against the inner molecular layer. This pattern may contribute to the layer-specific sprouting response of surviving afferents after entorhinal lesion. Neurite outgrowth may be promoted within the denervated zone, whereas axons trying to grow into the denervated outer molecular layer, for example from the inner molecular layer, would be deflected by a tenascin-C-rich barrier.


Assuntos
Astrócitos/metabolismo , Giro Denteado/metabolismo , Córtex Entorrinal/fisiologia , Neuritos/fisiologia , Tenascina/metabolismo , Animais , Astrócitos/fisiologia , Axônios/fisiologia , Giro Denteado/citologia , Feminino , Imuno-Histoquímica , Masculino , Degeneração Neural , Terminações Nervosas/fisiologia , Fagocitose , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Tenascina/genética
12.
Comb Chem High Throughput Screen ; 4(6): 453-75, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11562252

RESUMO

During the practice of combinatorial chemistry, it has been realized that molecular diversity is not the only essential feature in a synthetically feasible library. In addition, it is of utmost importance to enrich potential libraries with those molecules which could be converted to viable drug candidates. Given the enormous number of potentially synthesizable compounds, there is a need to design a subset of true "drug-like" compounds. In addition, a paradigm shift in drug discovery has resulted in the integration of pharmacokinetic and drug development activities into early stages of lead discovery. In particular, in silico filters are being developed and used to help identify and screen out compounds that are unlikely to become drugs. This paper highlights recent computational approaches towards the design of drug-like compound libraries, in particular, the prediction of drug-likeness in a more general sense as well as intestinal absorption through passive transport, the permeation of the blood-brain barrier and recent developments towards identification of potentially metabolically unstable molecules. Current computational tools for library design allow the incorporation of medicinal chemistry knowledge into library planning by a variety of methods, ranging from the use of privileged building blocks and simple counting of structural properties (e.g. number of hydrogen bonding partners) to relatively complex regression or neural network-based models to explain oral bioavailability and other pharmacokinetic properties by structural features. These tools are being incorporated more frequently into drug design according to the "rule-of-five" which refers to simple descriptors correlated to oral drug absorption. Combining experimental knowledge with effective computational filtering and prediction of various aspects of drug-likeness thus facilitates the rapid and cost-effective elimination of poor candidates prior to synthesis and helps focus attention on interesting molecules.


Assuntos
Técnicas de Química Combinatória/métodos , Bases de Dados como Assunto , Desenho de Fármacos , Animais , Disponibilidade Biológica , Humanos , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Farmacocinética
13.
J Neurosci Methods ; 103(1): 11-21, 2000 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-11074092

RESUMO

Among the available retrograde fluorescent tracers Fluoro-Gold (FG) is particularly advantageous because it (1) is not only detectable by fluorescence microscopy but also immunocytochemically, resulting in an almost complete staining of the dendritic arbor, (2) is visible in lysosome-like structures allowing for the identification of projection neurons at the ultrastructural level, and (3) remains in the labeled neurons for extended periods of time. Photoconversion and immunostaining for FG, respectively, result in a stable, electron-dense reaction product. Thus, the retrogradely labeled cells can be analyzed quantitatively in the light- and electron microscope for their structural characteristics and input synapses. Long-term studies of back-filled neurons provided evidence for neurotoxic effects of FG in these cells.


Assuntos
Transporte Axonal/efeitos dos fármacos , Encéfalo/ultraestrutura , Corantes Fluorescentes , Degeneração Neural/induzido quimicamente , Vias Neurais/ultraestrutura , Neurônios/ultraestrutura , Neurotoxinas/toxicidade , Estilbamidinas , Animais , Transporte Axonal/fisiologia , Axotomia/efeitos adversos , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Feminino , Corantes Fluorescentes/toxicidade , Imuno-Histoquímica/métodos , Masculino , Degeneração Neural/patologia , Vias Neurais/efeitos dos fármacos , Vias Neurais/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Fotoquímica/métodos , Ratos , Ratos Sprague-Dawley , Núcleos Septais/efeitos dos fármacos , Núcleos Septais/fisiologia , Núcleos Septais/ultraestrutura , Fatores de Tempo
14.
J Neurosci Methods ; 103(1): 117-26, 2000 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-11074101

RESUMO

Fiber tracts in the brain are formed by neurochemically heterogeneous neuron populations. To distinguish between the different neurons that contribute to a fiber tract it is necessary to combine anterograde and retrograde tracing techniques with immunocytochemistry. In this article, we describe two techniques which allow for the neurochemical identification of retrogradely labeled neurons and anterogradely labeled axons on the ultrastructural level. The identification of the neurotransmitter identity of retrogradely labeled neurons is achieved by combining retrograde Fluoro-Gold tracing with preembedding immunocytochemistry, while the neurotransmitter identity of anterogradely labeled axons can be revealed by combining anterograde Phaseolus vulgaris-leucoagglutinin (PHAL) tracing and postembedding immunostaining.


Assuntos
Transporte Axonal/efeitos dos fármacos , Encéfalo/ultraestrutura , Microscopia Eletrônica/métodos , Vias Neurais/ultraestrutura , Neurônios/ultraestrutura , Neurotransmissores/metabolismo , Estilbamidinas , Animais , Transporte Axonal/fisiologia , Axônios/fisiologia , Axônios/ultraestrutura , Encéfalo/fisiologia , Corantes Fluorescentes , Imuno-Histoquímica/métodos , Vias Neurais/fisiologia , Neurônios/fisiologia , Fito-Hemaglutininas , Sinapses/fisiologia , Sinapses/ultraestrutura
15.
Brain Res ; 808(2): 155-65, 1998 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-9767155

RESUMO

The cholinergic system of the rat basal forebrain is used as a model for the homologous region in humans which is highly susceptible to neuropathological alterations as in Alzheimer's disease. Cholinergic cells in the basal forebrain express the low-affinity neurotrophin receptor p75NTR. This has been utilized for selective immunolesioning of cholinergic neurons after internalization of an immunotoxin composed of anti-p75NTR and the ribosome-inactivating toxin saporin. However, the goal of many studies may be not the lesion, but the identification of cholinergic cells after other experimentally induced alterations in the basal forebrain. Therefore, a novel cholinergic marker was prepared by conjugating the monoclonal antibody 192IgG directed against p75NTR with the bright red fluorochrome carbocyanine 3 (Cy3). Three days after intraventricular injection of Cy3-192IgG the fluorescence microscopic analysis revealed a pattern of Cy3-labelled cells matching the distribution of cholinergic neurons. Apparently the marker was internalized within complexes of p75NTR and Cy3-192IgG which were then retrogradely transported to the cholinergic perikarya of the basal forebrain. In addition to the even labelling of somata, a strong punctate-like Cy3-immunofluorescence was seen in structures resembling lysosomes. The specificity of the in vivo staining was proven by subsequent immunolabelling of choline acetyltransferase (ChAT) with green fluorescent Cy2-tagged secondary antibodies. In the medial septum, the diagonal band and the nucleus basalis only cholinergic neurons were marked by Cy3-192IgG. In parallel experiments, digoxigenylated 192IgG was not detectable within cholinergic basal forebrain neurons after intraventricular injection. Presumably, this modified antibody could not be internalized. On the other hand, digoxigenylated 192IgG was found to be an excellent immunocytochemical marker for p75NTR as shown by double labelling including highly sensitive mouse antibodies directed against ChAT. Based on the present findings, future applications of the apparently non-toxic Cy3-192IgG and other antibodies for fluorescent in vivo and in vitro labelling are discussed.


Assuntos
Fibras Colinérgicas/química , Prosencéfalo/química , Prosencéfalo/citologia , Receptores de Fator de Crescimento Neural/análise , Animais , Anticorpos Monoclonais , Transporte Axonal/fisiologia , Carbocianinas , Colina O-Acetiltransferase/análise , Colina O-Acetiltransferase/imunologia , Fibras Colinérgicas/enzimologia , Imunofluorescência , Imunoglobulina G , Microscopia de Fluorescência/métodos , Prosencéfalo/enzimologia , Ligação Proteica , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Receptor de Fator de Crescimento Neural , Receptores de Fator de Crescimento Neural/imunologia
16.
Neurosci Lett ; 211(2): 117-20, 1996 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-8830858

RESUMO

Previous studies have demonstrated that numerous septohippocampal neurons survive axotomy disconnecting them from target-derived neurotrophins. One reason for survival could be that these neurons have additional projections to other targets supplying them with neurotrophic factor(s). We show that anterograde tracing indeed labeled additional targets of the medial septum (MS) in controls as well as in experimental animals. However, only very few MS neurons could be double-labeled by retrograde tracer injections into the hippocampus and these targets. Thus, for the majority of septohippocampal neurons multiple projections cannot account for their survival following axotomy.


Assuntos
Axônios/fisiologia , Neurônios/fisiologia , Prosencéfalo/citologia , Prosencéfalo/fisiologia , Animais , Sobrevivência Celular/fisiologia , Hipocampo/citologia , Hipocampo/fisiologia , Histocitoquímica , Microscopia de Fluorescência , Vias Neurais/citologia , Vias Neurais/fisiologia , Fito-Hemaglutininas , Ratos , Ratos Sprague-Dawley
17.
Neurosci Lett ; 205(2): 119-22, 1996 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-8907331

RESUMO

Changes in the biochemical activity of choline acetyltransferase in the medial septal nucleus, diagonal band and hippocampus were determined following bilateral fimbria-fornix transection or selective immunolesioning of cholinergic septohippocampal neurons with 192 IgG-saporin. Following axotomy, choline acetyltransferase activity in the medial septal nucleus not only persisted but increased much above control values 6 months postlesion, confirming that many cholinergic neurons survive the transection of their axons. In contrast, immunolesioning led to a significant decrease in enzyme activity in the medial septal nucleus corresponding to the selective loss of septal cholinergic neurons in this lesion paradigm.


Assuntos
Colina O-Acetiltransferase/metabolismo , Hipocampo/cirurgia , Núcleos Septais/enzimologia , Animais , Anticorpos Monoclonais/farmacologia , Morte Celular/efeitos dos fármacos , Colinérgicos/farmacologia , Fibras Colinérgicas/efeitos dos fármacos , Hipocampo/citologia , Hipocampo/enzimologia , Imunotoxinas/farmacologia , N-Glicosil Hidrolases , Neurônios/citologia , Neurônios/enzimologia , Ratos , Ratos Sprague-Dawley , Proteínas Inativadoras de Ribossomos Tipo 1 , Saporinas , Núcleos Septais/citologia
18.
Neurosci Lett ; 138(1): 81-5, 1992 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-1383881

RESUMO

Previous studies have indicated that interruption of the connections between the medial septum and hippocampus by cutting the axons results in degeneration and death of the projecting septal neurons. However, in these studies cell death has been inferred primarily from the loss of immunoreactivity for transmitter-specific enzymes. In the present study, we labeled septohippocampal projection neurons by retrograde tracing and then cut their axons. Subsequent intracellular injection of prelabeled cells revealed the morphology of the soma and dendrites and allowed us to examine the ultrastructure of these neurons. A large number of septohippocampal neurons survived even 10 weeks after axotomy, suggesting that axotomized septohippocampal neurons survive for considerable periods beyond the time at which they stop expressing transmitter-specific immunoreactivity. Survival of axotomized neurons is a prerequisite for pharmacological interference aimed at reactivating transmitter expression, axonal re-growth, and the eventual reintegration into functionally relevant circuitries.


Assuntos
Hipocampo/citologia , Neurônios/citologia , Estilbamidinas , Animais , Transporte Axonal , Axônios/ultraestrutura , Sobrevivência Celular , Colina O-Acetiltransferase/análise , Feminino , Corantes Fluorescentes , Hipocampo/ultraestrutura , Isoquinolinas , Microscopia Eletrônica , Fatores de Crescimento Neural/fisiologia , Neurônios/ultraestrutura , Ratos , Ratos Wistar
19.
Neurosci Lett ; 176(2): 243-6, 1994 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-7830956

RESUMO

It has been shown that target-derived neurotrophins are not necessary for the survival of septohippocampal cholinergic neurons in adult rats. In this study, we have removed the hippocampus in early postnatal rats by unilateral excitotoxic N-methyl-D-aspartate lesions at postnatal days 5, 10 and 20. At postnatal day 70, numerous cholinergic neurons (60% of controls) were present in the medial septum on the lesioned side. This suggests that there is only a limited influence of target-derived neurotrophic factors to these cells also in development.


Assuntos
Hipocampo/fisiologia , Neurônios/metabolismo , Neurotransmissores/biossíntese , Sistema Nervoso Parassimpático/fisiologia , Animais , Animais Recém-Nascidos , Sobrevivência Celular/efeitos dos fármacos , Colina O-Acetiltransferase/biossíntese , Feminino , Hipocampo/metabolismo , Masculino , N-Metilaspartato/farmacologia , Neurônios/efeitos dos fármacos , Sistema Nervoso Parassimpático/citologia , Sistema Nervoso Parassimpático/metabolismo , Ratos , Ratos Sprague-Dawley
20.
Neurosci Lett ; 173(1-2): 213-5, 1994 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-7936417

RESUMO

Loss of choline acetyltransferase (ChAT)-immunoreactive neurons in the medial septum (MS) following fimbria transection can be prevented by nerve growth factor (NGF) application. Here we have studied the long-term effects of a short-term NGF treatment starting immediately after lesion and lasting for the first 3 weeks. We demonstrate that this NGF treatment rescues many ChAT neurons after short survival time (3 weeks) but does not have a long-lasting (6 months) effect on both ChAT- and parvalbumin-immunopositive (GABAergic) MS neurons.


Assuntos
Axônios/fisiologia , Hipocampo/efeitos dos fármacos , Fatores de Crescimento Neural/farmacologia , Neurônios/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Colina O-Acetiltransferase/imunologia , Colina O-Acetiltransferase/metabolismo , Hipocampo/citologia , Injeções Intraventriculares , Fatores de Crescimento Neural/administração & dosagem , Parvalbuminas/imunologia , Parvalbuminas/metabolismo , Ratos , Ratos Sprague-Dawley , Ácido gama-Aminobutírico/fisiologia
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