RESUMO
AIMS: We aimed to reclassify a population-based cohort of 529 adult glioma patients to evaluate the prognostic impact of the 2016 World Health Organization (WHO) central nervous system tumour classification. Moreover, we evaluated the feasibility of gene panel next-generation sequencing (NGS) in daily diagnostics of 225 prospective glioma patients. METHODS: The retrospective cohort was reclassified according to WHO 2016 criteria by immunohistochemistry for IDH-R132H, fluorescence in situ hybridization for 1p/19q-codeletion and gene panel NGS. All tumours of the prospective cohort were subjected to NGS analysis up-front. RESULTS: The entire population-based cohort was successfully reclassified according to WHO 2016 criteria. NGS results were obtained for 98% of the prospective patients. Survival analyses in the population-based cohort confirmed three major prognostic subgroups, that is, isocitrate dehydrogenase (IDH)-mutant and 1p/19q-codeleted oligodendrogliomas, IDH-mutant astrocytomas and IDH-wildtype glioblastomas. The distinction between WHO grade II and III was prognostic in patients with IDH-mutant astrocytoma. The survival of patients with IDH-wildtype diffuse astrocytomas carrying TERT promoter mutation and/or EGFR amplification overlapped with the poor survival of IDH-wildtype glioblastoma patients. CONCLUSIONS: Gene panel NGS proved feasible in daily diagnostics. In addition, our study confirms the prognostic role of glioma classification according to WHO 2016 in a large population-based cohort. Molecular features of glioblastoma in IDH-wildtype diffuse glioma were linked to poor survival corresponding to IDH-wildtype glioblastoma patients. The distinction between WHO grade II and III retained prognostic significance in patients with IDH-mutant diffuse astrocytic gliomas.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias Encefálicas/diagnóstico , Glioma/patologia , Sequenciamento de Nucleotídeos em Larga Escala , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Astrocitoma/diagnóstico , Astrocitoma/genética , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Feminino , Glioblastoma/diagnóstico , Glioblastoma/genética , Glioma/diagnóstico , Glioma/genética , Humanos , Isocitrato Desidrogenase/genética , Masculino , Pessoa de Meia-Idade , Mutação/genética , Prognóstico , Telomerase/genética , Adulto JovemRESUMO
BACKGROUND: OptimalTTF-2 is a randomized, comparative, multi-center, investigator-initiated, interventional study aiming to test skull remodeling surgery in combination with Tumor Treating Fields therapy (TTFields) and best physicians choice medical oncological therapy for first recurrence in glioblastoma patients. OptimalTTF-2 is a phase 2 trial initiated in November 2020. Skull remodeling surgery consists of five burrholes, each 15 mm in diameter, directly over the tumor resection cavity. Preclinical research indicates that this procedure enhances the effect of Tumor Treating Fields considerably. We recently concluded a phase 1 safety/feasibility trial that indicated improved overall survival and no additional toxicity. This phase 2 trial aims to validate the efficacy of the proposed intervention. METHODS: The trial is designed as a comparative, 1:1 randomized, minimax two-stage phase 2 with an expected 70 patients to a maximum sample size of 84 patients. After 12-months follow-up of the first 52 patients, an interim futility analysis will be performed. The two trial arms will consist of either a) TTFields therapy combined with best physicians choice oncological treatment (control arm) or b) skull remodeling surgery, TTFields therapy and best practice oncology (interventional arm). Major eligibility criteria include age ≥ 18 years, 1st recurrence of supratentorial glioblastoma, Karnofsky performance score ≥ 70, focal tumor, and lack of significant co-morbidity. Study design aims to detect a 20% increase in overall survival after 12 months (OS12), assuming OS12 = 40% in the control group and OS12 = 60% in the intervention group. Secondary endpoints include hazard rate ratio of overall survival and progression-free survival, objective tumor response rate, quality of life, KPS, steroid dose, and toxicity. Toxicity, objective tumor response rate, and QoL will be assessed every 3rd month. Endpoint data will be collected at the end of the trial, including the occurrence of suspected unexpected serious adverse reactions (SUSARs), unacceptable serious adverse events (SAEs), withdrawal of consent, or loss-to-follow-up. DISCUSSION: New treatment modalities are highly needed for first recurrence glioblastoma. Our proposed treatment modality of skull remodeling surgery, Tumor Treating Fields, and best practice medical oncological therapy may increase overall survival significantly. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT0422399 , registered 13. January 2020.
Assuntos
Neoplasias Encefálicas/cirurgia , Glioblastoma/cirurgia , Recidiva Local de Neoplasia/cirurgia , Osteotomia/métodos , Crânio/cirurgia , Adulto , Seguimentos , Glioblastoma/mortalidade , Humanos , Avaliação de Estado de Karnofsky , Recidiva Local de Neoplasia/mortalidade , Intervalo Livre de Progressão , Estudos Prospectivos , Qualidade de Vida , Fatores de Tempo , TransdutoresRESUMO
A lobular capillary hemangioma, previously known as a pyogenic granuloma, is a benign vascular lesion of the skin or mucous membrane. We report a case of capillary hemangioma of lobular subtype in the calvarium of a 28-year-old pregnant woman which presented as a sore and rapidly growing bulge over the left fronto-parietal region. Magnetic resonance imaging of the brain and skull showed an expansive tumor with brain displacement, skull erosion, and scalp infiltration. The tumor was surgically removed, and histopathological examination showed a capillary hemangioma of lobular subtype. To the best of our knowledge, this is the first report of a lobular capillary hemangioma in the calvarium, and it represents a rarity to be considered among the many other differential diagnoses for neurosurgical lesions involving the skull, especially in pregnant women.
Assuntos
Doenças Ósseas/cirurgia , Granuloma Piogênico/cirurgia , Complicações na Gravidez/cirurgia , Crânio/cirurgia , Adulto , Doenças Ósseas/diagnóstico , Doenças Ósseas/patologia , Diagnóstico Diferencial , Feminino , Granuloma Piogênico/diagnóstico , Granuloma Piogênico/patologia , Humanos , Imageamento por Ressonância Magnética , Gravidez , Complicações na Gravidez/diagnóstico , Complicações na Gravidez/patologia , Gestantes , Crânio/patologiaRESUMO
BACKGROUND: Cerebral mitochondrial dysfunction is prominent in the pathophysiology of severe bacterial meningitis. In the present study, we hypothesize that the metabolic changes seen after intracisternal lipopolysaccharide (LPS) injection in a piglet model of meningitis is compatible with mitochondrial dysfunction and resembles the metabolic patterns seen in patients with bacterial meningitis. METHODS: Eight pigs received LPS injection in cisterna magna, and four pigs received NaCl in cisterna magna as a control. Biochemical variables related to energy metabolism were monitored by intracerebral microdialysis technique and included interstitial glucose, lactate, pyruvate, glutamate, and glycerol. The intracranial pressure (ICP) and brain tissue oxygen tension (PbtO2) were also monitored along with physiological variables including mean arterial pressure, blood glucose, lactate, and partial pressure of O2 and CO2. Pigs were monitored for 60 min at baseline and 240 min after LPS/NaCl injection. RESULTS: After LPS injection, a significant increase in cerebral lactate/pyruvate ratio (LPR) compared to control group was registered (p = 0.01). This increase was due to a significant increased lactate with stable and normal values of pyruvate. No significant change in PbtO2 or ICP was registered. No changes in physiological variables were observed. CONCLUSIONS: The metabolic changes after intracisternal LPS injection is compatible with disturbance in the oxidative metabolism and partly due to mitochondrial dysfunction with increasing cerebral LPR due to increased lactate and normal pyruvate, PbtO2, and ICP. The metabolic pattern resembles the one observed in patients with bacterial meningitis. Metabolic monitoring in these patients is feasible to monitor for cerebral metabolic derangements otherwise missed by conventional intensive care monitoring.
Assuntos
Cérebro/metabolismo , Ácido Láctico/metabolismo , Lipopolissacarídeos/farmacologia , Meningites Bacterianas/metabolismo , Doenças Mitocondriais/metabolismo , Ácido Pirúvico/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Lipopolissacarídeos/administração & dosagem , Microdiálise , Monitorização Neurofisiológica , SuínosRESUMO
It is well described that patients with pulmonary arteriovenous malformations (PAVMs) and Hereditary Hemorrhagic Telangiectasia (HHT) have an increased risk of cerebral abscess (CA). However, as both CA and HHT are rare, the proportion of patients with CA who are diagnosed with HHT has not been previously described. A retrospective study was carried out of all patients treated surgically for CA between January 1995 and September 2014 at the Department of Neurosurgery, Odense University Hospital. The cases were then cross-referenced with the Danish HHT database. Eighty patients aged 5-79 years were included. The incidence of CA was 0.33/100,000/year. Two patients (2.5%) were registered as having HHT. Bacterial pathogens were identified in 70% of all cases, most frequently streptococci species (46.3%). The most common predisposing condition was odontogenic infection (20%), followed by post-operative infection (13.8%) and post-trauma (6.3%). Patients undergoing a full diagnostic program to determine predisposing conditions causing CA increased over the 20-year period from 11.8% to 65.2%. The 3-month and 1-year mortality rates were 7.5% and 11.25%, respectively. There is an overrepresentation of HHT patients in a cohort of patients with CA, and HHT should be investigated as the cause of the CA if no other apparent cause can be identified.
Assuntos
Abscesso Encefálico/epidemiologia , Telangiectasia Hemorrágica Hereditária/complicações , Adolescente , Adulto , Idoso , Bactérias/classificação , Bactérias/isolamento & purificação , Abscesso Encefálico/microbiologia , Abscesso Encefálico/cirurgia , Criança , Pré-Escolar , Dinamarca/epidemiologia , Feminino , Hospitais , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Retrospectivos , Adulto JovemRESUMO
The neuroprotective effect of neuropeptide Y (NPY) receptor activation was investigated in organotypic mouse hippocampal slice cultures exposed to the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Exposure of 2-week-old slice cultures, derived from 7-day-old C57BL/6 mice, to 8 microm AMPA, for 24 h, induced degeneration of CA1 and CA3 pyramidal cells, as measured by cellular uptake of propidium iodide (PI). A significant neuroprotection, with a reduction of PI uptake in CA1 and CA3 pyramidal cell layers, was observed after incubation with a Y(2) receptor agonist [NPY(13-36), 300 nm]. This effect was sensitive to the presence of the selective Y(2) receptor antagonist (BIIE0246, 1 microm), but was not affected by addition of TrkB-Fc or by a neutralizing antibody against brain-derived neurotrophic factor (BDNF). Moreover, addition of a Y(1) receptor antagonist (BIBP3226, 1 microm) or a NPY-neutralizing antibody helped to disclose a neuroprotective role of endogenous NPY in CA1 region. Cultures exposed to 8 microm AMPA for 24 h, displayed, as measured by an enzyme-linked immunosorbent assay, a significant increase in BDNF. In such cultures there was an up-regulation of neuronal TrkB immunoreactivity, as well as the presence of BDNF-immunoreactive microglial cells at sites of injury. Thus, an increase of AMPA-receptor mediated neurodegeneration, in the mouse hippocampus, was prevented by neuroprotective pathways activated by NPY receptors (Y(1) and Y(2)), which can be affected by BDNF released by microglia and neurons.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Microglia/metabolismo , Neurônios/metabolismo , Neuropeptídeo Y/metabolismo , Receptores de Neuropeptídeo Y/metabolismo , Animais , Ensaio de Imunoadsorção Enzimática , Hipocampo/metabolismo , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos C57BL , Técnicas de Cultura de Órgãos , Receptores de AMPA/metabolismo , Receptores de Neuropeptídeo Y/antagonistas & inibidores , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
AIM: Calcium channel blockers are widely used in cardiovascular diseases. Besides L-type channels, T- and P/Q-type calcium channels are involved in the contraction of human renal blood vessels. It was hypothesized that T- and P/Q-type channels are involved in the contraction of human brain and mammary blood vessels. METHODS: Internal mammary arteries from bypass surgery patients and cerebral arterioles from patients with brain tumours with and without hypertension were tested in a myograph and perfusion set-up. PCR and immunohistochemistry were performed on isolated blood vessels. RESULTS: The P/Q-type antagonist ω-agatoxin IVA (10-8 mol L-1 ) and the T-type calcium blocker mibefradil (10-7 mol L-1 ) inhibited KCl depolarization-induced contraction in mammary arteries from hypertensive patients with no effect on blood vessels from normotensive patients. ω-Agatoxin IVA decreased contraction in cerebral arterioles from hypertensive patients. L-type blocker nifedipine abolished the contraction in mammary arteries. PCR analysis showed expression of P/Q-type (Cav 2.1), T-type (Cav 3.1 and Cav 3.2) and L-type (Cav 1.2) calcium channels in mammary and cerebral arteries. Immunohistochemical labelling of mammary and cerebral arteries revealed the presence of Cav 2.1 in endothelial and smooth muscle cells. Cav 3.1 was also detected in mammary arteries. CONCLUSION: P/Q- and T-type Cav are present in human internal mammary arteries and in cerebral penetrating arterioles. P/Q- and T-type calcium channels are involved in the contraction of mammary arteries from hypertensive patients but not from normotensive patients. Furthermore, in cerebral arterioles P/Q-type channels importance was restricted to hypertensive patients might lead to that T- and P/Q-type channels could be a new target in hypertensive patients.
Assuntos
Canais de Cálcio/metabolismo , Artérias Cerebrais/metabolismo , Hipertensão/metabolismo , Artéria Torácica Interna/metabolismo , Vasoconstrição/fisiologia , Idoso , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/efeitos dos fármacos , Artérias Cerebrais/efeitos dos fármacos , Feminino , Humanos , Imuno-Histoquímica , Masculino , Artéria Torácica Interna/efeitos dos fármacos , Pessoa de Meia-Idade , Técnicas de Cultura de Órgãos , Técnicas de Patch-Clamp , Reação em Cadeia da Polimerase , Vasoconstrição/efeitos dos fármacosRESUMO
Using synchrotron radiation, the behaviour of the diffuse X-ray scatter was investigated in the relaxed and active phases of auxotonic and isometric contractions. Muscles were stimulated tetanically for 0.75 of a second, leaving intervals of three minutes between successive contractions. In isometric contractions the scatter is very asymmetric, which means that the myosin heads have a strongly preferred orientation. During tension rise the scatter expands in the meridional direction and contracts in the equatorial direction, the maximal local intensity change being about 20%. The shape change indicates that on average the myosin heads become oriented more perpendicularly to the fibre axis. The distribution of orientations at peak tension is quite different from that we found previously in X-ray scattering data from rigor muscles. In auxotonic contractions where muscles shorten against an increasing tension the scatter is practically circularly symmetrical. This suggests that during shortening the myosin heads go evenly through a wide range of orientations. It is concluded that the results from both the auxotonic and isometric experiments provide strong support for the rotating myosin head model. In isometric contractions the transition between the relaxed phase and peak tension is accompanied by an overall increase in scattering intensity of about 10%: this corresponds to a relative increase in the fraction of disordered myosin heads by almost 30%.
Assuntos
Contração Muscular , Miosinas , Animais , Contração Isométrica , Músculos/fisiologia , Rana esculenta , Rana pipiens , Espalhamento de Radiação , Raios XRESUMO
A method that relates molecular structure to the forces that maintain it and to its X-ray diffraction pattern is described and applied to muscle. In a computer model, the potential energy of the movable components (here the myosin heads) is minimized by letting them move down the steepest gradient in three dimensions from a variety of starting positions. Initial values are assumed for the parameters that determine the forces, and for those that define the structure and arrangement of the fixed components. The X-ray pattern expected from the resulting structures can be calculated in a straightforward manner and compared with relevant observed data. Discrepancies can then be minimized by varying the values initially assumed for the parameters, as in the conventional "trial and error" method. This first application of the present method is concerned with the effects of the hexagonal lattice on the myosin head configuration in thick filaments of the type found in vertebrate skeletal muscle. For that purpose, a very simple model was used with the following main features: smooth cylinders for the thin filaments and for the thick filament backbones, two spherical heads attached by Hookean springs to each point of a 9/3 helix on the surface of the backbone, and repulsive forces of the electrostatic double-layer type acting between each head and all other surfaces. The myosin head configuration was calculated for an isolated thick filament and a study was made of the effects of packing such filaments into a hexagonal lattice of various side spacings in the presence or absence of thin filaments. For the isolated filament, it was found that the 9/3 helical symmetry is maintained in the myosin head configuration and that the two heads of each molecule are splayed azimuthally. When such filaments are packed into the hexagonal lattice with thin filaments present, the 9/3 helical symmetry of the myosin head configuration is lost. As the lattice side spacing is reduced, the myosin heads become increasingly displaced not only in the radial and azimuthal directions but also in the axial direction, although they interact primarily with smooth cylinders. The axial separation of the two heads in each molecule becomes different in one level from that in the other two in the 43 nm axial repeat, thus increasing the repeat in projection onto the axis from 14.3 to 43 nm. This effect may contribute to the "forbidden meridionals" described by Huxley & Brown (1967).(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Músculos/ultraestrutura , Miosinas , Modelos Moleculares , Conformação Proteica , Difração de Raios XRESUMO
Activity-dependent brain-derived neurotrophic factor (BDNF) expression is Ca2+-dependent, yet little is known about the Ca2+ channel contributions that might direct selective expression of the multiple BDNF transcripts. Here, effects of pilocarpine-induced seizure activity on total BDNF expression and on the individual sensitivity of BDNF transcripts to glutamate receptor and Ca2+ channel blockers were evaluated using hippocampal slice cultures and in situ hybridization of transcript-specific cRNA probes directed against mRNAs for the four 5' exons (I-IV) of the BDNF gene. mRNAs for nerve growth factor (NGF) and tyrosine kinase B (trkB) also were studied. Pilocarpine (5 mM) induced a dose- and time-dependent increase in total BDNF (exon V) mRNA expression in the dentate granule cells and CA3-CA1 pyramidal cells with maximal effects at 6 and 24 h, respectively. Increases were blocked by co-treatment with the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid/kainate 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX: 25 microM) and the N-methyl-d-aspartic acid receptor antagonist 2-amino-5-phosphonovaleric acid (APV; 25 microM), whereas the L-type voltage sensitive Ca2+ channel blocker nifedipine (20 microM) was without detectable effect. Maximal NGF and trkB mRNA expression was induced by pilocarpine at 4 and 12 h, respectively. For the individual BDNF transcripts, APV blocked pilocarpine-induced increases in transcript II, whereas nifedipine blocked increases in transcripts I and III. Transcript IV levels were not altered by treatment. These results indicate that transcript II makes the greatest contribution to pilocarpine effects on total BDNF mRNA content in this model and provides evidence for regional and Ca2+ channel-specific differences in activity-dependent regulation of the different BDNF transcripts in hippocampus.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/genética , Cálcio/metabolismo , Pilocarpina/farmacologia , Convulsões/fisiopatologia , Processamento Alternativo , Animais , Fator Neurotrófico Derivado do Encéfalo/biossíntese , Fator Neurotrófico Derivado do Encéfalo/efeitos dos fármacos , Bloqueadores dos Canais de Cálcio/farmacologia , Relação Dose-Resposta a Droga , Antagonistas de Aminoácidos Excitatórios/farmacologia , Regulação da Expressão Gênica , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hibridização In Situ , Agonistas Muscarínicos/farmacologia , Fator de Crescimento Neural/efeitos dos fármacos , Fator de Crescimento Neural/metabolismo , Técnicas de Cultura de Órgãos , RNA Mensageiro/análise , Ratos , Receptor trkB/efeitos dos fármacos , Receptor trkB/metabolismo , Convulsões/induzido quimicamente , Fatores de TempoRESUMO
Hippocampal deafferentation increases the expression of insulin-like growth factor-1 by microglia, and of ciliary neurotrophic factor and basic fibroblast growth factor by astroglia in fields and periods of reactive axonal growth. Glucocorticoids attenuate lesion-induced hippocampal sprouting, possibly by reducing trophic signals that stimulate growth. With an interest in this hypothesis, the present studies evaluated the influence of systemic treatment with the synthetic glucocorticoid dexamethasone on entorhinal lesion-induced increases in neurotrophic factor expression in young adult rat hippocampus. Daily dexamethasone injections almost completely blocked increases in insulin-like growth factor-1 messenger RNA content, but did not perturb increases in ciliary neurotrophic factor or basic fibroblast growth factor messenger RNA content, in the deafferented dentate gyrus molecular layer. To determine if the suppression of insulin-like growth factor-1 expression was secondary to a general inhibition of microglial responses, and to identify the time period of glucocorticoid sensitivity, additional rats were prepared to evaluate the effects of semi-chronic (i.e. daily) and single dexamethasone injections on microglial proliferation, ED-1 immunoreactivity (a marker of microglial reactivity) and insulin-like growth factor-1 messenger RNA expression. Semi-chronic dexamethasone treatment attenuated all three measures of deafferentation-induced microglial reactivity. However, a single dexamethasone injection given two (but not one or three) days postlesion inhibited deafferentation-induced increases in insulin-like growth factor-1 messenger RNA content, without having significant effects on other measures. These results demonstrate that dexamethasone treatment preferentially suppresses microglial, as opposed to astroglial, trophic responses to deafferentation, and suggest that glucocorticoids attenuate reactive axonal sprouting by inhibiting the microglial production of insulin-like growth factor-1.
Assuntos
Denervação , Dexametasona/farmacologia , Glucocorticoides/farmacologia , Hipocampo/fisiologia , Microglia/efeitos dos fármacos , Microglia/fisiologia , Animais , Fator Neurotrófico Ciliar , Fator 2 de Crescimento de Fibroblastos/genética , Masculino , Proteínas do Tecido Nervoso/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Fatores de TempoRESUMO
Transection of the entorhino-dentate perforant path is a well known model for lesion-induced axonal sprouting and glial reactions in the rat. In this study, we have characterized the microglial reaction in the dentate molecular layer of the SJL/J and C57Bl/6 mouse. The morphological transformation of the microglial cells and their densitometrically measured Mac-1 immunoreactivity were correlated with the density of silver-impregnated axonal and terminal degeneration and the myelination of the degenerating medial and lateral perforant pathways. Anterograde axonal and terminal degeneration leads to: (i) altered myelin basic protein immunoreactivity with the appearance of discrete myelin deposits preferentially in the denervated medial and significantly less so in the lateral perforant path zone from day 2 after lesioning; (ii) an increase in number and Mac-1 immunoreactivity of morphologically-changed microglial cells in the denervated perforant path zones with more pronounced morphological transformation of microglia in the medial than in the lateral perforant path zones at day 2 but not day 5 after lesioning; and (iii) a linear correlation between the density of microglial Mac-1 reactivity and axonal degeneration in the medial but not in the lateral perforant path zone at two days postlesion, and a linear correlation in both zones at five days postlesion. We propose that the differentiated microglial response is due to the different densities of axonal and terminal degeneration, as observed in the individual cases. The finding of a potentiated or accelerated microglial activation in the medial as compared to the lateral perforant path zone suggests different kinetics of microglial activation in areas with degenerating myelinated and unmyelinated fibers.
Assuntos
Axônios/fisiologia , Giro Denteado/fisiologia , Microglia/fisiologia , Bainha de Mielina/fisiologia , Degeneração Neural/patologia , Via Perfurante/fisiologia , Terminações Pré-Sinápticas/fisiologia , Animais , Corantes , Densitometria , Giro Denteado/citologia , Giro Denteado/ultraestrutura , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Proteína Básica da Mielina/metabolismo , Oligodendroglia/metabolismo , Coloração pela Prata , Cloreto de TolônioRESUMO
Activity-induced brain-derived neurotrophic factor (BDNF) expression is negatively modulated by circulating adrenal steroids. The rat BDNF gene gives rise to four major transcript forms that each contain a unique 5' exon (I-IV) and a common 3' exon (V) that codes for BDNF protein. Exon-specific in situ hybridization was used to determine if adrenalectomy has differential effects on basal and activity-induced BDNF transcript expression in hippocampus. Adrenalectomy alone had only modest effects on BDNF mRNA levels with slight increases in exon III-containing mRNA with 7-10-day survival and in exon II-containing mRNA with 30-days survival. In the dentate gyrus granule cells, adrenalectomy markedly potentiated increases in exon I and II cRNA labeling, but not increases in exon III and IV cRNA labeling, elicited by one hippocampal afterdischarge. Similarly, for the granule cells and CA1 pyramidal cells, hilus lesion (HL)-induced recurrent limbic seizures elicited greater increases in exon I and II cRNA hybridization in adrenalectomized (ADX) as compared to adrenal-intact rats. In this paradigm, adrenalectomy modestly potentiated the increase in exon III-containing mRNA in CA1 but had no effect on exon IV-containing mRNA content. These results demonstrate that the negative effects of adrenal hormones on activity-induced BDNF expression are by far the greatest for transcripts containing exons I and II. Together with evidence for region-specific transcript expression, these results suggest that the effects of stress on adaptive changes in BDNF signalling will be greatest for neurons that predominantly express transcripts I and II.
Assuntos
Corticosteroides/fisiologia , Adrenalectomia , Fator Neurotrófico Derivado do Encéfalo/biossíntese , Giro Denteado/lesões , Regulação da Expressão Gênica , Hipocampo/metabolismo , Proteínas do Tecido Nervoso/biossíntese , RNA Mensageiro/biossíntese , Convulsões/metabolismo , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Giro Denteado/metabolismo , Traumatismos por Eletricidade/genética , Traumatismos por Eletricidade/metabolismo , Éxons/genética , Masculino , Proteínas do Tecido Nervoso/genética , Células Piramidais/metabolismo , RNA Mensageiro/genética , Ratos , Ratos Sprague-Dawley , Convulsões/genéticaRESUMO
The regulation of oligodendrocyte gene expression and myelination in vivo in the normal and injured adult CNS is still poorly understood. We have analyzed the effects of axotomy-induced axonal sprouting and microglial activation, on oligodendrocyte myelin basic protein (MBP) gene expression from 2 to 35 days after transection of the entorhino-hippocampal perforant path axonal projection. In situ hybridization analysis showed that anterograde axonal and terminal degeneration lead to upregulated oligodendrocyte MBP mRNA expression starting between day 2 and day 4, in (1) the deep part of stratum radiatum of CA3 and the dentate hilus, which display axonal sprouting but no degenerative changes or microglial activation, and (2) the outer part of the molecular layer of the fascia dentata, and in stratum moleculare of CA3 and stratum lacunosum-moleculare of CA1, areas that display dense anterograde axonal and terminal degeneration, myelin degenerative changes, microglial activation and axotomi-induced axonal sprouting. Oligodendrocyte MBP mRNA expression reached maximum in both these areas at day 7. MBP gene transcription remained constant in stratum radiatum, stratum pyramidale and stratum oriens of CA1, areas that were unaffected by perforant path transection. These results provide strong evidence that oligodendrocyte MBP gene expression can be regulated by axonal sprouting independently of microglial activation in the injured adult CNS.
Assuntos
Axônios/enzimologia , Hipocampo/fisiologia , Proteína Básica da Mielina/genética , Regeneração Nervosa/fisiologia , Degeneração Walleriana/fisiopatologia , Acetilcolinesterase/análise , Animais , Axônios/química , Corantes , Denervação , Córtex Entorrinal/química , Córtex Entorrinal/citologia , Córtex Entorrinal/fisiologia , Expressão Gênica/fisiologia , Hipocampo/química , Hipocampo/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/fisiologia , Plasticidade Neuronal/fisiologia , Oligodendroglia/fisiologia , Via Perfurante/química , Via Perfurante/citologia , Via Perfurante/fisiologia , RNA Mensageiro/análise , Coloração pela Prata , Cloreto de TolônioAssuntos
Actinas/análise , Músculos/anatomia & histologia , Animais , Anuros , Colo , Cobaias , Modelos Biológicos , Moluscos , Contração Muscular , Músculo Liso/análise , Músculo Liso/anatomia & histologia , Músculos/análise , Miofibrilas , Conformação Proteica , Rana temporaria , Rigor Mortis , Difração de Raios XAssuntos
Citocinas/fisiologia , Neuroglia/fisiologia , Animais , Sistema Nervoso Central/imunologia , Sistema Nervoso Central/fisiologia , Citocinas/genética , Humanos , Camundongos , Camundongos Transgênicos , Proteína Básica da Mielina/genética , Proteína Básica da Mielina/fisiologia , Neuroglia/imunologia , Via Perfurante/fisiologiaRESUMO
Using x-rays from synchrotron radiation, we studied diffuse scattering, sometimes together with the myosin layer lines. With an area detector, sartorius muscles and a time resolution of 150 ms, earlier results from semitendinosus muscles contracting isometrically at 6 degrees C (Lowy, J., and F. R. Poulsen. 1987. J. Mol. Biol. 194:595-600) were confirmed and extended. Evidence from intensity changes both in the diffuse scattering and in the myosin layer lines showed that the majority of the heads become disordered at peak tetanic tension. With a linear detector and a time resolution of 5 ms, it was found that during tension rise the intensity increase of the diffuse scattering (which amounted maximally to 12% recorded near the meridian) runs approximately 20 ms ahead of the mechanical change, comparing half-completion times. This suggests that an appreciable number of heads change orientation before peak tension is reached. In quick release experiments the diffuse scattering intensity showed very little change. Recorded near the meridian during rapid shortening, however, it decreased progressively with a half-time of approximately 40 ms. This change amounted to approximately 35% of that observed during the initial tension rise. We interpret this to indicate that during rapid shortening a certain number of heads assume an orientation characteristic of the relaxed state. Viewed in the context of the behavior of the first myosin layer line and the (1, 1) equatorial reflection in similar experiments (Huxley, H. E., M. Kress, A. R. Faruqi, and R. M. Simmons. 1988. Molecular Mechanism of Muscle Contraction), the present results provide further support for the view that the diffuse scattering is mostly due to disordered myosin heads; whilst ordered heads produce the myosin layer lines (Poulsen, F. R., and J. Lowy.1983. Nature lLond.l. 303:146-152).
Assuntos
Contração Muscular , Músculos/fisiologia , Animais , Técnicas In Vitro , Miosinas/fisiologia , Rana ridibunda , Sarcômeros/fisiologia , Difração de Raios X/métodosRESUMO
Low-angle X-ray diffraction patterns from relaxed and non-overlap rigor muscles show a central region of diffuse scattering (disk) which is circularly symmetrical, behaves as solution scattering and comes predominantly from myosin heads. In full-overlap rigor the disk is compressed in the diagonal direction, indicating that the myosin heads have a bent shape and a preferred orientation consistent with a 45 degree angle of attachment to actin.
Assuntos
Contração Muscular , Relaxamento Muscular , Miosinas/fisiologia , Actinas/fisiologia , Animais , Músculos/ultraestrutura , Conformação Proteica , Ranidae , Difração de Raios XRESUMO
The intensities of three regions of the low-angle X-ray diffraction pattern from a molluscan unstriated muscle have been followed during tension generation at a time resolution of 0.5-1 s using synchrotron radiation. The observed intensity changes can be reasonably interpreted in terms of myosin cross-bridge movements during the contractile cycle. A model that accounts for the intensity changes suggests that myosin heads move out from the thick filament during activation and attach to actin sites to produce tension with a small delay. During relaxation from both phasic and tonic contractions the heads remain attached to actin sites longer than it takes for tension to decay.