Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 39
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Biom J ; 61(1): 126-137, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30370548

RESUMO

The meta-analysis of diagnostic accuracy studies is often of interest in screening programs for many diseases. The typical summary statistics for studies chosen for a diagnostic accuracy meta-analysis are often two dimensional: sensitivities and specificities. The common statistical analysis approach for the meta-analysis of diagnostic studies is based on the bivariate generalized linear-mixed model (BGLMM), which has study-specific interpretations. In this article, we present a population-averaged (PA) model using generalized estimating equations (GEE) for making inference on mean specificity and sensitivity of a diagnostic test in the population represented by the meta-analytic studies. We also derive the marginalized counterparts of the regression parameters from the BGLMM. We illustrate the proposed PA approach through two dataset examples and compare performance of estimators of the marginal regression parameters from the PA model with those of the marginalized regression parameters from the BGLMM through Monte Carlo simulation studies. Overall, both marginalized BGLMM and GEE with sandwich standard errors maintained nominal 95% confidence interval coverage levels for mean specificity and mean sensitivity in meta-analysis of 25 of more studies even under misspecification of the covariance structure of the bivariate positive test counts for diseased and nondiseased subjects.


Assuntos
Biometria/métodos , Diagnóstico , Metanálise como Assunto , Infecções Relacionadas a Cateter/diagnóstico , Humanos , Análise Multivariada , Sensibilidade e Especificidade
3.
Acta Neuropathol ; 130(1): 93-105, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25962793

RESUMO

Multiple system atrophy (MSA) is a sporadic neurodegenerative disease clinically characterized by cerebellar signs, parkinsonism, and autonomic dysfunction. Pathologically, MSA is an α-synucleinopathy affecting striatonigral and olivopontocerebellar systems, while neocortical and limbic involvement is usually minimal. In this study, we describe four patients with atypical MSA with clinical features consistent with frontotemporal dementia (FTD), including two with corticobasal syndrome, one with progressive non-fluent aphasia, and one with behavioral variant FTD. None had autonomic dysfunction. All had frontotemporal atrophy and severe limbic α-synuclein neuronal pathology. The neuronal inclusions were heterogeneous, but included Pick body-like inclusions. The latter were strongly associated with neuronal loss in the hippocampus and amygdala. Unlike typical Pick bodies, the neuronal inclusions were positive on Gallyas silver stain and negative on tau immunohistochemistry. In comparison to 34 typical MSA cases, atypical MSA had significantly more neuronal inclusions in anteromedial temporal lobe and limbic structures. While uncommon, our findings suggest that MSA may present clinically and pathologically as a frontotemporal lobar degeneration (FTLD). We suggest that this may represent a novel subtype of FTLD associated with α-synuclein (FTLD-synuclein).


Assuntos
Encéfalo/patologia , Degeneração Lobar Frontotemporal/patologia , Atrofia de Múltiplos Sistemas/patologia , alfa-Sinucleína/metabolismo , Idoso , Idoso de 80 Anos ou mais , Encéfalo/metabolismo , Feminino , Degeneração Lobar Frontotemporal/genética , Degeneração Lobar Frontotemporal/fisiopatologia , Humanos , Atrofia de Múltiplos Sistemas/genética , Atrofia de Múltiplos Sistemas/fisiopatologia , alfa-Sinucleína/genética , Proteínas tau/metabolismo
4.
Hum Mutat ; 33(7): 1141-8, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22488673

RESUMO

Alexander disease (AxD) is a usually fatal astrogliopathy primarily caused by mutations in the gene encoding glial fibrillary acidic protein (GFAP), an intermediate filament protein expressed in astrocytes. We describe three patients with unique characteristics, and whose mutations have implications for AxD diagnosis and studies of intermediate filaments. Patient 1 is the first reported case with a noncoding mutation. The patient has a splice site change producing an in-frame deletion of exon 4 in about 10% of the transcripts. Patient 2 has an insertion and deletion at the extreme end of the coding region, resulting in a short frameshift. In addition, the mutation was found in buccal DNA but not in blood DNA, making this patient the first reported chimera. Patient 3 has a single-base deletion near the C-terminal end of the protein, producing a short frameshift. These findings recommend inclusion of intronic splice site regions in genetic testing for AxD, indicate that alteration of only a small fraction of GFAP can produce disease, and provide caution against tagging intermediate filaments at their C-terminal end for cell biological investigations.


Assuntos
Doença de Alexander/genética , Mutação da Fase de Leitura/genética , Proteína Glial Fibrilar Ácida/genética , Splicing de RNA/genética , Adulto , Astrócitos/metabolismo , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Mutação
5.
Acta Neuropathol ; 124(1): 143-8, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22370906

RESUMO

Mycoplasmas, particularly Mycoplasma pneumoniae, have been implicated as causative agents in a large variety of central nervous system diseases, especially acute childhood encephalitis. Postulated pathomechanisms for mycoplasma-mediated neurological disease have included: direct infection, autoimmunity, and vascular occlusion. Neuropathologic data are meager and are reviewed. We report a 3-year-old boy, who developed signs and symptoms of encephalitis 7 days after the onset of fever with cough and death 5 days later. At autopsy, he displayed diffuse vasogenic edema and perivascular to infiltrative inflammatory cells, the latter most prominent in gray matter of brainstem and amygdala. The predominant cell was the CD68-positive macrophage, followed by the T-lymphocyte. Cells immunolabeled with a polyclonal antibody to M. pneumoniae included perivascular to parenchymal macrophages/microglia, occasional oligodendrocytes, and neurons, particularly in brainstem. Affected neurons varied from morphologically normal to profoundly degenerate and necrotic. Ultrastructural study of the inferior olive confirmed the presence of 260-600 nm cell-wall-free microorganisms, consistent with mycoplasma, in perivascular cells and neurons. Foci of acute disseminated encephalomyelitis also were rarely identified. This case report confirms the postulated role of direct infection of brain by mycoplasma in acute childhood encephalitis, but also reveals a virus-like infection of central neurons. The pathogenesis of acute childhood encephalitis due to mycoplasma seems to be multifactorial.


Assuntos
Encéfalo/patologia , Encefalite/patologia , Infecções por Mycoplasma/patologia , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Encéfalo/metabolismo , Pré-Escolar , Encefalite/microbiologia , Humanos , Masculino , Microscopia Eletrônica de Transmissão , Infecções por Mycoplasma/microbiologia , Neurônios/patologia , Neurônios/ultraestrutura
6.
J Neuropathol Exp Neurol ; 69(10): 987-96, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20838246

RESUMO

Vanishing white matter (VWM) is one of the most prevalent inherited childhood leukoencephalopathies, but this may affect people of all ages, including neonates and adults. It is a progressive disorder clinically dominated by cerebellar ataxia and in which minor stress conditions, such as fever or mild trauma, provoke major episodes of neurologic deterioration. Typical pathological findings include increasing white matter rarefaction and cystic degeneration, oligodendrocytosis with highly characteristic foamy oligodendrocytes, meager astrogliosis with dysmorphic astrocytes, and loss of oligodendrocytes by apoptosis. Vanishing white matter is caused by mutations in any of the genes encoding the 5 subunits of the eukaryotic translation initiation factor 2B (eIF2B), EIF2B1 through EIF2B5. eIF2B is a ubiquitously expressed protein complex that plays a crucial role in regulating the rate of protein synthesis. Vanishing white matter mutations reduce the activity of eIF2B and impair its function to couple protein synthesis to the cellular demands in basal conditions and during stress. Reduced eIF2B activity leads to sustained improper activation of the unfolded protein response, resulting in concomitant expression of proliferation, prosurvival, and proapoptotic downstream effectors. Consequently, VWM cells are constitutively predisposed and hyperreactive to stress. In view of the fact that VWM genes are housekeeping genes, it is surprising that the disease is primarily a leukoencephalopathy. The pathophysiology of selective glial vulnerability in VWM remains poorly understood.


Assuntos
Leucoencefalopatias , Fibras Nervosas Mielinizadas/patologia , Fator de Iniciação 2B em Eucariotos/genética , Glicina/líquido cefalorraquidiano , Humanos , Leucoencefalopatias/genética , Leucoencefalopatias/patologia , Leucoencefalopatias/fisiopatologia
7.
Expert Rev Neurother ; 10(9): 1449-66, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20819015

RESUMO

Abnormalities of myelin are common in lysosomal and peroxisomal disorders. Most display a primary loss of myelin in which the myelin sheath and/or oligodendrocytes are selectively targeted by diverse pathogenetic processes. The most severe and, hence, clinically relevant are heritable diseases predominantly of infants and children, the leukodystrophies: metachromatic, globoid cell (Krabbe disease) and adreno-leukodystrophy. Our still limited understanding of these diseases has derived from multiple sources: originally, neurological-neuropathologic-neurochemical correlative studies of the natural disease in humans or other mammals, which has been enhanced by more sophisticated and contemporary techniques of cell and molecular biology. Transgenic mouse models seem to be the most promising methodology, allowing the examination of the cellular role of lysosomes and peroxisomes for formation and maintenance of both myelin and axons, and providing initial platforms to evaluate therapies. Treatment options are woefully inadequate and in their nascent stages, but still inspire some hope for the future.


Assuntos
Leucodistrofia Metacromática/patologia , Lisossomos/patologia , Bainha de Mielina/patologia , Transtornos Peroxissômicos/patologia , Animais , Humanos
8.
PLoS One ; 5(2): e9002, 2010 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-20126313

RESUMO

Neurodegenerative diseases are characterized by a number of features including the formation of inclusions, early synaptic degeneration and the selective loss of neurons. Molecules serving as links between these shared features have yet to be identified. Identifying candidates within the diseased microenvironment will open up novel avenues for therapeutic intervention. The transcription factor Elk-1 resides within multiple brain areas both in nuclear and extranuclear neuronal compartments. Interestingly, its de novo expression within a single dendrite initiates neuronal death. Given this novel regionalized function, we assessed whether extranuclear Elk-1 and/or phospho-Elk-1 (pElk-1) protein might be associated with a spectrum of human neurodegenerative disease cases including Lewy body Disease (e.g. Parkinson's), Alzheimer's disease, and Huntington's Disease. We first determined the importance of Elk-1 post-translational modifications on its ability to initiate regionalized cell death. We next screened human cases from three major neurodegenerative diseases to look for remarkable levels of Elk-1 and/or pElk-1 protein as well as their association with inclusions characteristic of these diseases. We compared our findings to age-matched control cases. We find that the ability of Elk-1 to initiate regionalized neuronal death depends on a specific phosphosite, T417. Furthermore, we find that T417(+) Elk-1 uniquely associates with several types of inclusions present in cases of human Lewy body Disease, Alzheimer's disease, and Huntington's Disease. These results suggest a molecular link between the presence of inclusions and neuronal loss that is shared across a spectrum of neurodegenerative disease.


Assuntos
Corpos de Inclusão/metabolismo , Doenças Neurodegenerativas/metabolismo , Neurônios/metabolismo , Proteínas Elk-1 do Domínio ets/metabolismo , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Animais , Sítios de Ligação/genética , Células Cultivadas , Feminino , Humanos , Doença de Huntington/metabolismo , Doença de Huntington/patologia , Imuno-Histoquímica , Corpos de Inclusão/patologia , Doença por Corpos de Lewy/metabolismo , Doença por Corpos de Lewy/patologia , Masculino , Microscopia Confocal , Pessoa de Meia-Idade , Mutagênese Sítio-Dirigida , Doenças Neurodegenerativas/patologia , Neurônios/citologia , Fosforilação , Ratos , Treonina/genética , Treonina/metabolismo , Transfecção , Proteínas Elk-1 do Domínio ets/genética
9.
J Neurol Sci ; 290(1-2): 70-4, 2010 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-19945717

RESUMO

X-linked adreno-leukodystrophy and its adult variant, adrenomyeloneuropathy, are caused by mutations in ABCD1 that encodes a peroxisomal membrane protein of unknown physiological significance. In spite of identical mutations, they can have markedly divergent neurological and neuropathologic characteristics. Adreno-leukodystrophy classically presents in normal boys with mild neuropsychiatric features, which progress to frank neurological signs, the vegetative state and death in approximately three years. Adrenomyeloneuropathy typically affects young men with spastic paraparesis and sensory ataxia that can progress over decades. The neuropathologic correlate for adreno-leukodystrophy is severe inflammatory demyelination of posterior cerebral white matter, while a chronic distal axonopathy of spinal cord and peripheral nerve occurs in adrenomyeloneuropathy. Consequently, both modifier genes and environmental factors have been implicated in their pathogeneses. We report five cases of adreno-leukodystrophy whose onsets were initiated by moderate to severe head trauma, two of whom were conversions from adrenomyeloneuropathy. Their clinical courses were rapidly incapacitating, short (i.e., weeks to a few years) and fatal due to marked cerebral inflammatory demyelination. These cases, in concert with several previous reports, indicate that head trauma is one environmental factor that can have a profoundly deleterious effect on those genetically at risk for, or with milder clinical phenotypes of, this disease. Avoidance of potential head trauma and a rapid response to episodes of moderate to severe head trauma in this patient population seem prudent.


Assuntos
Adrenoleucodistrofia/etiologia , Adrenoleucodistrofia/patologia , Lesões Encefálicas/complicações , Lesões Encefálicas/patologia , Adolescente , Adrenoleucodistrofia/genética , Adulto , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Encéfalo/fisiopatologia , Causalidade , Progressão da Doença , Evolução Fatal , Predisposição Genética para Doença/genética , Humanos , Metabolismo dos Lipídeos/genética , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Bainha de Mielina/metabolismo , Bainha de Mielina/patologia , Fibras Nervosas Mielinizadas/metabolismo , Fibras Nervosas Mielinizadas/patologia , Estado Vegetativo Persistente/etiologia , Estado Vegetativo Persistente/genética , Estado Vegetativo Persistente/patologia , Estudos Retrospectivos , Medula Espinal/diagnóstico por imagem , Medula Espinal/patologia , Medula Espinal/fisiopatologia , Fatores de Tempo , Tomografia Computadorizada por Raios X , Adulto Jovem
10.
Appl Immunohistochem Mol Morphol ; 17(5): 451-7, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19349855

RESUMO

Malignant solitary fibrous tumor (MSFT) is a rare neoplasm. Three cases of MSFT with unusual features, including 1 pleural and 2 extrapleural, are reported. A 64-year-old woman with a large right thoracic MSFT and episodes of severe hypoglycemia experienced resolution of her hypoglycemia immediately after resection of the MSFT. A 27-year-old woman with primary retroperitoneal MSFT had pulmonary metastases 10 months after resection of the primary tumor. A 54-year-old man with an intracranial solitary fibrous tumor suffered from multiple pulmonary metastases and local recurrence 21 and 28 months after resection of the primary tumor, respectively. All 3 cases of solitary fibrous tumor displayed malignant features. The tumor cells in each case were positive for CD34 and Bcl-2, but negative for cytokeratin, smooth muscle actin, S-100, and c-kit. In addition, the tumor cells in the case with concomitant hypoglycemia were strongly positive for insulin-like growth factor-II. The histopathologic diagnostic criteria for MSFT, the differential diagnosis with other spindle cell tumors, and the mechanism of MSFT-derived hypoglycemia via insulin-like growth factor-II are discussed.


Assuntos
Fibroma/diagnóstico , Adulto , Feminino , Fibroma/diagnóstico por imagem , Fibroma/metabolismo , Fibroma/patologia , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
11.
J Neuropathol Exp Neurol ; 68(2): 136-47, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19151628

RESUMO

Eosinophilic inclusions in the cytoplasm of protoplasmic astrocytes of the neocortex, usually in the clinical setting of epilepsy and/or psychomotor retardation, were first recognized and illustrated by Alois Alzheimer in 1910. Traditional special stains have failed to elucidate the specific nature of these inclusions. Ultrastructurally, the material was composed predominantly of highly electron-dense, non-membrane-bound, granular material distinct from Rosenthal fibers. Immunohistochemical examination has been informative but also sometimes inconsistent; it has recently been suggested that they may represent a filaminopathy (filamin A). We examined 5 cases with neocortical eosinophilic inclusions (3 autopsies, 2 surgical resections) using a standardized immunohistochemical protocol at a single institution. The specimens were immunostained with 32 antibodies to 30 potentially relevant proteins using several antigen retrieval protocols. We confirmed the presence of filamin A in these inclusions, but several additional proteins, particularly cytoglobin and glutamate transporter 1, were also identified. By electron microscopy in 2 cases, the granular fine structure of the inclusions was confirmed; mitochondria adjacent to, and perhaps within, the inclusions that contained many pleomorphic vesicular and membranous elements were also noted in 1 case. The pathophysiologic relevance of these proteins and the clinical significance of the hyaline inclusions are discussed.


Assuntos
Astrócitos/patologia , Epilepsia/patologia , Hialina/ultraestrutura , Corpos de Inclusão/patologia , Neocórtex/patologia , Proteínas do Tecido Nervoso/análise , Adolescente , Astrócitos/metabolismo , Criança , Pré-Escolar , Proteínas Contráteis/análise , Proteínas Contráteis/metabolismo , Citoglobina , Epilepsia/metabolismo , Epilepsia/fisiopatologia , Transportador 2 de Aminoácido Excitatório/análise , Transportador 2 de Aminoácido Excitatório/metabolismo , Feminino , Filaminas , Globinas/análise , Globinas/metabolismo , Humanos , Hialina/metabolismo , Imuno-Histoquímica/métodos , Corpos de Inclusão/metabolismo , Masculino , Proteínas dos Microfilamentos/análise , Proteínas dos Microfilamentos/metabolismo , Microscopia Eletrônica de Transmissão , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Neocórtex/metabolismo , Neocórtex/fisiopatologia , Proteínas do Tecido Nervoso/metabolismo , Proteômica , Transtornos Psicomotores/metabolismo , Transtornos Psicomotores/patologia , Transtornos Psicomotores/fisiopatologia , Coloração e Rotulagem , Adulto Jovem
12.
J Neuropathol Exp Neurol ; 66(12): 1100-17, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18090919

RESUMO

We present 3 sporadic cases of a subacute to chronic, progressive motor (i.e. weakness, ataxia, spasticity, dysarthria, and dysphagia) and cognitive disorder in adults of both sexes, without proven immunocompromise or malignancy. Neuroimaging studies revealed tiny calcifications with atrophy of the cerebrum, pons, and midbrain in 1 patient, cerebral atrophy in another, and cerebral atrophy and periventricular white matter hyperintensities in the third. Clinical diagnoses included cortico-pontine-cerebellar degeneration, mixed neurodegenerative disorder, progressive supranuclear palsy, diffuse Lewy body disease, and Lyme disease. One atrophic brain revealed widely disseminated, millimeter-sized gray lesions in cerebral white matter and obscured anatomic markings of the basis pontis. The most conspicuous microscopic feature in all was capillaries with focally piled up endothelial nuclei, some of which appeared to be multinucleated, or enlarged, hyperchromatic crescentic single nuclei. Although seen mostly without associated damage, they were also noted with white matter lesions displaying vacuolation, demyelination, spheroids, necrosis, vascular fibrosis, and mineralization; these were most severe in the basis pontis. Immunostains and probes to herpes simplex virus-I, -II, and -8; adenovirus, cytomegalovirus, varicella-zoster, Epstein-Barr virus, measles, JC virus, and herpes hominis virus-6 were negative. Electron microscopy revealed no virions in endothelial cells with multilobed or multiple nuclei and duplicated basal laminae. However, mycoplasma-like bodies, mostly 400 to 600 nm in size, were found in endothelial cell cytoplasm and capillary lumina. Platelets adhered to affected endothelial cells. Polymerase chain reaction and immunohistochemistry of fixed samples for Mycoplasma fermentans were negative; other species of Mycoplasma remain viable pathogenic candidates.


Assuntos
Encefalopatias/etiologia , Encefalopatias/patologia , Córtex Cerebral/patologia , Células Endoteliais/patologia , Infecções por Mycoplasma/complicações , Adulto , Idoso , Atrofia , Encefalopatias/microbiologia , Angiografia Cerebral , Córtex Cerebral/microbiologia , Córtex Cerebral/ultraestrutura , Células Endoteliais/microbiologia , Células Endoteliais/ultraestrutura , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Neuroglia/patologia , Neuroglia/ultraestrutura , Estudos Retrospectivos
13.
J Neuropathol Exp Neurol ; 66(7): 660-72, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17620991

RESUMO

We performed a blinded study on 5 cases of hereditary diffuse leukoencephalopathy with spheroids and 10 cases of the pigmentary type of orthochromatic leukodystrophy, 6 of the latter having a family history of neurologic illness. Patients presented in the third to sixth decade with behavioral, cognitive, and motor symptoms. All cases displayed widespread myelin loss, predominantly frontotemporal with relative sparing of subcortical U-fibers, and variable numbers of both neuroaxonal spheroids and pigmented glia. Immunohistochemically, spheroids contained amyloid precursor/neurofilament proteins, several neurotransmitters or neuropeptides, and ubiquitin. Cytoplasmic inclusions in glia and numerous pigmented macrophages were autofluorescent and stained consistently with diastase-periodic acid-Schiff, prolonged Ziehl-Nielsen, and Sudan black, but the same cells labeled inconsistently for iron or ferritin. Ultrastructurally, the most characteristic autofluorescent glial lipopigments consisted of bosselated masses of granular, electron-dense material. These morphologic features are those of ceroid, an end-product of oxidative damage. Glial immunoreactivity for markers of oxidative stress (hemeoxygenase-1 and superoxide dismutase 2) and damage (4-hydroxynonenal, malondialdehyde, and nitrotyrosine) was noted, particularly in cases with increased iron and ferritin. These data support the hypothesis that the similar clinicopathologic features of hereditary diffuse leukoencephalopathy with spheroids and the pigmentary type of orthochromatic leukodystrophy reflect a common disease due, at least in part, to an oxidative insult.


Assuntos
Axônios/patologia , Leucoencefalopatia Multifocal Progressiva , Distrofias Neuroaxonais , Neuroglia/patologia , Neurônios/patologia , Estresse Oxidativo/fisiologia , Adulto , Idoso , Peptídeos beta-Amiloides/metabolismo , Axônios/ultraestrutura , Saúde da Família , Feminino , Humanos , Leucoencefalopatia Multifocal Progressiva/genética , Leucoencefalopatia Multifocal Progressiva/patologia , Leucoencefalopatia Multifocal Progressiva/fisiopatologia , Lipídeos , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , Pessoa de Meia-Idade , Distrofias Neuroaxonais/genética , Distrofias Neuroaxonais/patologia , Distrofias Neuroaxonais/fisiopatologia , Neuroglia/metabolismo
14.
J Acoust Soc Am ; 121(5 Pt1): 2591-9, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17550158

RESUMO

Two experimental underwater acoustic projectors, a tonpilz array, and a cylindrical line array, were built with single crystal, lead magnesium niobate/lead titanate, a piezoelectric transduction material possessing a large electromechanical coupling factor (k33 = 0.9). The mechanical quality factor, Q(m), and the effective coupling factor, k(eff), determine the frequency band over which high power can be transmitted; k(eff) cannot be greater than the piezoelectric material value, and so a high material coupling factor is a requisite for broadband operation. Stansfield's bandwidth criteria are used to calculate the optimum Q(m) value, Q(opt) approximately 1.2 (1-k(eff)2 1/2/k(eff). The results for the tonpilz projector exhibited k(eff) = 0.730, Q(m) = 1.17 (very near optimal), and a fractional bandwidth of 0.93. For the cylindrical transducer array, k(eff) = 0.867, Q(m) = 0.91 (larger than the optimum value, 0.7), and the bandwidth was 1.16. Although the measured bandwidths were less than optimal, they were accurately predicted by the theory, despite the highly simplified nature of the Van Dyke equivalent circuit, on which the theory is based.


Assuntos
Acústica , Cristalização , Chumbo , Magnésio , Modelos Estatísticos , Titânio , Movimento (Física) , Som
15.
Lab Invest ; 87(3): 261-72, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17260006

RESUMO

X-linked adreno-leukodystrophy is a progressive, systemic peroxisomal disorder that primarily affects the adrenal cortex, as well as myelin and axons of the central nervous system. Marked phenotypic heterogeneity does not correlate with disease-causing mutations in ABCD1, which encodes a peroxisomal membrane protein that is a member of the ABC transmembrane transporter proteins. The precise physiological functions of ABCD1 and ABCD2, a closely related peroxisomal membrane half-transporter, are unknown. The abcd1 knockout mouse does not develop the inflammatory demyelination so typical and devastating in adreno-leukodystrophy, but it does display the same lamellae and lipid profiles in adrenocortical cells under the electron microscope as the human patients. The adrenocortical cells in the mouse also exhibit immunohistochemical evidence of oxidative stress at 12 weeks but no evidence of oxidative damage. To better understand the pathogenesis of this complex disease, we evaluate the adrenal lesion of the abcd1 knockout mouse as a function of normal aging, dietary or therapeutic manipulations, and abcd genotype. The loss of abcd2 causes oxidative stress in the adrenal at 12 weeks, as judged by increased immunoreactivity for the mitochondrial manganese superoxide dismutase, in both the inner cortex and medulla. The loss of abcd2 (n=20), but not abcd1 (n=27), results in the spontaneous and premature deposition of ceroid, a known end-product of oxidative damage, predominantly in adrenal medullary cells. These data indicate that the loss of abcd2 results in greater oxidative stress in murine adrenal cells than the loss of abcd1, providing a clue to its cellular function. We also find that the adrenocortical lesion of the abcd1 knockout mouse does not produce functional impairment at ten to nineteen months or overt hypocortisolism at any age, nor does it progress histologically; these and other data align this mouse model closer to human female heterozygotes than to male ALD or AMN hemizygotes.


Assuntos
Transportadores de Cassetes de Ligação de ATP/fisiologia , Glândulas Suprarrenais/metabolismo , Quimiocinas CC/fisiologia , Estresse Oxidativo , Peroxissomos/metabolismo , Subfamília D de Transportador de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Quimiocina CCL22 , Quimiocinas CC/genética , Quimiocinas CC/metabolismo , Sulfato de Desidroepiandrosterona/administração & dosagem , Combinação de Medicamentos , Ácidos Erúcicos/administração & dosagem , Imuno-Histoquímica , Hibridização In Situ , Masculino , Camundongos , Camundongos Knockout , Trioleína/administração & dosagem
16.
J Neurooncol ; 82(1): 23-7, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16955219

RESUMO

Gliomatosis cerebri (GC) is a rare tumor characterized by widespread infiltration of the brain and spinal cord. Although GC usually demonstrates histomorphological features of a low-grade tumor, the formation of secondary highly malignant tumor regions may occur. In order to reveal molecular genetic changes associated with tumor progression in GC, we analyzed factors known to be associated with malignant progression in common astocytomas in an unusual GC case of an 18-year-old patient suffering from this disease for almost 7 years. We detected allelic losses in the Rb gene and in exon 4 of the TP53 gene in a tumor region corresponding to a glioblastoma multiforme. EGFR or MDM2 gene amplifications were absent, and no PTEN mutation or allelic loss on chromosome 10 could be detected. Moreover, compared to tumor-free brain tissue of this patient, tumor regions showed increased EGFR expression. These findings show that malignant progression in GC might be associated with the acquisition of molecular genetic changes also found in low-grade astrocytomas with progression to secondary glioblastoma. These data support the notion that GC can be regarded as a subtype of a common astrocytoma.


Assuntos
Neoplasias Encefálicas/genética , Genes do Retinoblastoma/genética , Genes p53/genética , Perda de Heterozigosidade/genética , Neoplasias Neuroepiteliomatosas/genética , Adolescente , Astrocitoma/classificação , Astrocitoma/genética , Neoplasias Encefálicas/classificação , Neoplasias Encefálicas/metabolismo , Progressão da Doença , Receptores ErbB/genética , Receptores ErbB/metabolismo , Humanos , Imuno-Histoquímica , Masculino , Neoplasias Neuroepiteliomatosas/classificação , Neoplasias Neuroepiteliomatosas/metabolismo
17.
J Neuropathol Exp Neurol ; 65(7): 707-15, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16825957

RESUMO

Leukoencephalopathy with vanishing white matter (VWM) is a childhood white matter disorder with an autosomal-recessive mode of inheritance. The clinical course is chronic progressive with episodes of rapid neurologic deterioration after febrile infections. The disease is caused by mutations in the genes encoding the subunits of eukaryotic initiation factor 2B (eIF2B), a protein complex that is essential for protein synthesis. In VWM, mutations in the eIF2B genes are thought to impair the ability of cells to regulate protein synthesis under normal and stress conditions. It has been suggested that the pathophysiology of VWM involves inappropriate activation of the unfolded protein response (UPR). The UPR is a protective mechanism activated by an overload of unfolded or malfolded proteins in the endoplasmic reticulum. Activation of one pathway of the UPR, in which eIF2B is involved, has already been described in brain tissue of patients with VWM. In the present study, we demonstrate activation of all 3 UPR pathways in VWM brain tissue using real-time quantitative polymerase chain reaction and immunohistochemistry. We show that activation occurs exclusively in the white matter, predominantly in oligodendrocytes and astrocytes. The selective involvement of these cells suggests that inappropriate UPR activation may play a key role in the pathophysiology of VWM.


Assuntos
Doenças Desmielinizantes Hereditárias do Sistema Nervoso Central/metabolismo , Neuroglia/metabolismo , Dobramento de Proteína , Fator 6 Ativador da Transcrição/genética , Fator 6 Ativador da Transcrição/metabolismo , Adolescente , Adulto , Processamento Alternativo , Animais , Biomarcadores/metabolismo , Criança , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Retículo Endoplasmático/metabolismo , Chaperona BiP do Retículo Endoplasmático , Endorribonucleases/genética , Endorribonucleases/metabolismo , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Doenças Desmielinizantes Hereditárias do Sistema Nervoso Central/genética , Doenças Desmielinizantes Hereditárias do Sistema Nervoso Central/patologia , Humanos , Lactente , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Neuroglia/citologia , Neuroglia/patologia , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Biossíntese de Proteínas/fisiologia , Conformação Proteica , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Fatores de Transcrição de Fator Regulador X , Transdução de Sinais/fisiologia , Fatores de Transcrição , eIF-2 Quinase/genética , eIF-2 Quinase/metabolismo
18.
J Neuropathol Exp Neurol ; 65(7): 716-21, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16825958

RESUMO

The apoptotic death of putaminal neurons and glia in a patient with hereditary ferritinopathy is studied immunohistochemically with antibodies to p53, activated caspase-3, PUMA, BAX, cytochrome c, and inducible nitric oxide synthase. In addition to the overexpression of ferritin and the iron accumulations assumed to result from the genetically incompetent ferritin molecule, additional contributions to the iron, heme, and hyaline deposits in this disease are sought with antibodies to 2 recently discovered globins in humans, neuroglobin and cytoglobin. The "pathognomonic" swollen to vacuolated nuclei are immunoreactive for both p53 and activated caspase-3, indicating the intervention of the p53-mediated apoptotic pathway. The immunohistochemical demonstration of neuroglobin in the swollen nuclei and both globins in the hyaline deposits highlights the potential pathogenic importance of 2 other iron-containing proteins in this disease that is largely restricted to brain. Hereditary ferritinopathy is the first human disease in which abnormalities in these heme-containing proteins are demonstrated.


Assuntos
Apoptose/fisiologia , Ferritinas/metabolismo , Globinas/metabolismo , Transtornos Heredodegenerativos do Sistema Nervoso , Distúrbios do Metabolismo do Ferro , Proteínas do Tecido Nervoso/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Encéfalo/citologia , Encéfalo/metabolismo , Encéfalo/patologia , Caspase 3 , Caspases/metabolismo , Núcleo Celular/metabolismo , Ativação Enzimática , Transtornos Heredodegenerativos do Sistema Nervoso/genética , Transtornos Heredodegenerativos do Sistema Nervoso/metabolismo , Transtornos Heredodegenerativos do Sistema Nervoso/patologia , Humanos , Hialina/metabolismo , Ferro/metabolismo , Distúrbios do Metabolismo do Ferro/genética , Distúrbios do Metabolismo do Ferro/metabolismo , Distúrbios do Metabolismo do Ferro/patologia , Neuroglia/citologia , Neuroglia/metabolismo , Neuroglia/patologia , Neuroglobina , Neurônios/citologia , Neurônios/metabolismo , Neurônios/patologia , Putamen/citologia , Putamen/metabolismo , Putamen/patologia , Proteína Supressora de Tumor p53/genética
19.
J Immunol ; 176(12): 7676-85, 2006 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-16751415

RESUMO

Experimental autoimmune encephalomyelitis (EAE) is a Tcell-mediated autoimmune disease of the CNS that is widely used as an animal model of multiple sclerosis. In this study, we investigate the role of CXCL13, a chemokine involved in the development and organization of secondary lymphoid tissues, in the pathogenesis of EAE. We detected CXCL13 mRNA and protein in spinal cords of mice with EAE. CXCL13-deficient mice exhibited a mild, self-limited form of disease. CXCL13 appeared to be important for the establishment of chronic white matter lesions. Furthermore, adoptive transfer experiments with CXCL13-deficient hosts indicate that the chemokine plays a distinct role during the effector phase. Our findings raise the possibility that reagents that antagonize or inhibit CXCL13 might be useful for the treatment of neuroinflammatory diseases such as multiple sclerosis.


Assuntos
Quimiocinas CXC/fisiologia , Encefalomielite Autoimune Experimental/imunologia , Doença Aguda , Sequência de Aminoácidos , Animais , Movimento Celular/genética , Movimento Celular/imunologia , Células Cultivadas , Quimiocina CXCL13 , Quimiocinas CXC/biossíntese , Quimiocinas CXC/deficiência , Quimiocinas CXC/genética , Regulação para Baixo/genética , Regulação para Baixo/imunologia , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/patologia , Encefalomielite Autoimune Experimental/prevenção & controle , Glicoproteínas/administração & dosagem , Glicoproteínas/imunologia , Imunidade Ativa , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/patologia , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Dados de Sequência Molecular , Glicoproteína Mielina-Oligodendrócito , Fragmentos de Peptídeos/administração & dosagem , Fragmentos de Peptídeos/imunologia , RNA Mensageiro/biossíntese , Receptores CXCR5 , Receptores de Quimiocinas , Receptores de Citocinas/biossíntese , Recidiva , Medula Espinal/imunologia , Medula Espinal/metabolismo , Medula Espinal/patologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo
20.
J Neuropathol Exp Neurol ; 64(12): 1067-79, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16319717

RESUMO

X-linked adreno-leukodystrophy is a progressive, systemic peroxisomal disorder that affects primarily nervous system myelin and axons as well as the adrenal cortex. Several divergent clinical phenotypes can occur in the same family; thus, there is no correlation between the clinical phenotype and the mutation in the ABCD1 gene in this disease. The most urgent and unresolved clinical issue is the fulminant inflammatory (immune) demyelination of the central nervous system in which a variety of cellular participants, cytokines, and chemokines are noted. A knockout mouse model exhibits mitochondrial deficits and axonal degeneration, but not inflammatory demyelination. To determine whether oxidative stress and damage might play a pathogenic role, we assessed standard biochemical and immunohistochemical markers of such activity both in our knockout mouse model and patients. We find that oxidative stress, as judged by increased immunoreactivity for the mitochondrial manganese-superoxide dismutase, is present in the knockout mouse liver, adrenal cortex, and renal cortex, tissues that normally express high levels of ABCD1 but no evidence of oxidative damage. The brain does not exhibit either oxidative stress or damage. On the other hand, both the human adrenal cortex and brain show evidence of oxidative stress (e.g. hemoxygenase-1 and manganese-superoxide dismutase) and oxidative damage, particularly from lipid peroxidation (4-hydroxynonenal and malondialdehyde). The presence of nitrotyrosylated proteins is strong circumstantial evidence for the participation of the highly toxic peroxynitrite molecule, whereas the demonstration of interferon gamma and interleukin-12 is indicative of a TH1 response in the inflammatory demyelinative lesions of the cerebral phenotype. These differences between the adreno-leukodystrophy mouse and human patients are intriguing and may provide a clue to the phenotypic divergence in this disease.


Assuntos
Adrenoleucodistrofia/etiologia , Estresse Oxidativo , Córtex Suprarrenal/enzimologia , Córtex Suprarrenal/metabolismo , Córtex Suprarrenal/patologia , Adrenoleucodistrofia/metabolismo , Adrenoleucodistrofia/patologia , Animais , Bioquímica/métodos , Biomarcadores/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Quimiocina CCL22 , Quimiocinas CC/deficiência , Humanos , Imuno-Histoquímica , Interferon gama/metabolismo , Interleucina-12/metabolismo , Córtex Renal/enzimologia , Córtex Renal/patologia , Fígado/enzimologia , Fígado/patologia , Camundongos , Camundongos Knockout , Mitocôndrias/enzimologia , Mitocôndrias/patologia , Superóxido Dismutase/metabolismo , Tirosina/análogos & derivados , Tirosina/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...