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OBJECTIVE: To improve the timely recognition of patients with treatment-responsive causes of rapidly progressive dementia (RPD). METHODS: A total of 226 adult patients with suspected RPD were enrolled in a prospective observational study and followed for up to 2 years. Diseases associated with RPD were characterized as potentially treatment-responsive or non-responsive, referencing clinical literature. Disease progression was measured using Clinical Dementia Rating® Sum-of-Box scores. Clinical and paraclinical features associated with treatment responsiveness were assessed using multivariable logistic regression. Findings informed the development of a clinical criterion optimized to recognize patients with potentially treatment-responsive causes of RPD early in the diagnostic evaluation. RESULTS: A total of 155 patients met defined RPD criteria, of whom 86 patients (55.5%) had potentially treatment-responsive causes. The median (range) age-at-symptom onset in patients with RPD was 68.9 years (range 22.0-90.7 years), with a similar number of men and women. Seizures, tumor (disease-associated), magnetic resonance imaging suggestive of autoimmune encephalitis, mania, movement abnormalities, and pleocytosis (≥10 cells/mm3 ) in cerebrospinal fluid at presentation were independently associated with treatment-responsive causes of RPD after controlling for age and sex. Those features at presentation, as well as age-at-symptom onset <50 years (ie, STAM3 P), captured 82 of 86 (95.3%) cases of treatment-responsive RPD. The presence of ≥3 STAM3 P features had a positive predictive value of 100%. INTERPRETATION: Selected features at presentation reliably identified patients with potentially treatment-responsive causes of RPD. Adaptation of the STAM3 P screening score in clinical practice may minimize diagnostic delays and missed opportunities for treatment in patients with suspected RPD. ANN NEUROL 2024;95:237-248.
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Demência , Encefalite , Adulto , Masculino , Humanos , Feminino , Adulto Jovem , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Demência/diagnóstico , Demência/tratamento farmacológico , Demência/etiologia , Encefalite/complicações , Imageamento por Ressonância Magnética , Testes de Estado Mental e Demência , Progressão da DoençaRESUMO
OBJECTIVE: This study was undertaken to apply established and emerging cerebrospinal fluid (CSF) biomarkers to improve diagnostic accuracy in patients with rapidly progressive dementia (RPD). Overlap in clinical presentation and results of diagnostic tests confounds etiologic diagnosis in patients with RPD. Objective measures are needed to improve diagnostic accuracy and to recognize patients with potentially treatment-responsive causes of RPD. METHODS: Biomarkers of Alzheimer disease neuropathology (amyloid-ß 42/40 ratio, phosphorylated tau [p-tau181, p-tau231]), neuroaxonal/neuronal injury (neurofilament light chain [NfL], visinin-like protein-1 [VILIP-1], total tau), neuroinflammation (chitinase-3-like protein [YKL-40], soluble triggering receptor expressed on myeloid cells 2 [sTREM2], glial fibrillary acidic protein [GFAP], monocyte chemoattractant protein-1 [MCP-1]), and synaptic dysfunction (synaptosomal-associated protein 25kDa, neurogranin) were measured in CSF obtained at presentation from 78 prospectively accrued patients with RPD due to neurodegenerative, vascular, and autoimmune/inflammatory diseases; 35 age- and sex-matched patients with typically progressive neurodegenerative disease; and 72 cognitively normal controls. Biomarker levels were compared across etiologic diagnoses, by potential treatment responsiveness, and between patients with typical and rapidly progressive presentations of neurodegenerative disease. RESULTS: Alzheimer disease biomarkers were associated with neurodegenerative causes of RPD. High NfL, sTREM2, and YKL-40 and low VILIP-1 identified patients with autoimmune/inflammatory diseases. MCP-1 levels were highest in patients with vascular causes of RPD. A multivariate model including GFAP, MCP-1, p-tau181, and sTREM2 identified the 44 patients with treatment-responsive causes of RPD with 89% accuracy. Minimal differences were observed between typical and rapidly progressive presentations of neurodegenerative disease. INTERPRETATION: Selected CSF biomarkers at presentation were associated with etiologic diagnoses and treatment responsiveness in patients with heterogeneous causes of RPD. The ability of cross-sectional biomarkers to inform upon mechanisms that drive rapidly progressive neurodegenerative disease is less clear. ANN NEUROL 2024;95:299-313.
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Doença de Alzheimer , Demência , Doenças Neurodegenerativas , Humanos , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/líquido cefalorraquidiano , Proteína 1 Semelhante à Quitinase-3 , Proteínas tau/líquido cefalorraquidiano , Estudos Transversais , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Biomarcadores/líquido cefalorraquidianoRESUMO
Biallelic mutations in SNORD118, encoding the small nucleolar RNA U8, cause leukoencephalopathy with calcifications and cysts (LCC). Given the difficulty in interpreting the functional consequences of variants in nonprotein encoding genes, and the high allelic polymorphism across SNORD118 in controls, we set out to provide a description of the molecular pathology and clinical spectrum observed in a cohort of patients with LCC. We identified 64 affected individuals from 56 families. Age at presentation varied from 3 weeks to 67 years, with disease onset after age 40 years in eight patients. Ten patients had died. We recorded 44 distinct, likely pathogenic, variants in SNORD118. Fifty two of 56 probands were compound heterozygotes, with parental consanguinity reported in only three families. Forty nine of 56 probands were either heterozygous (46) or homozygous (three) for a mutation involving one of seven nucleotides that facilitate a novel intramolecular interaction between the 5' end and 3' extension of precursor-U8. There was no obvious genotype-phenotype correlation to explain the marked variability in age at onset. Complementing recently published functional analyses in a zebrafish model, these data suggest that LCC most often occurs due to combinatorial severe and milder mutations, with the latter mostly affecting 3' end processing of precursor-U8.
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Calcinose/genética , Estudos de Associação Genética , Leucoencefalopatias/genética , RNA Nucleolar Pequeno/genética , Adolescente , Adulto , Idoso , Animais , Calcinose/complicações , Calcinose/patologia , Criança , Pré-Escolar , Consanguinidade , Modelos Animais de Doenças , Feminino , Heterozigoto , Humanos , Lactente , Recém-Nascido , Leucoencefalopatias/complicações , Leucoencefalopatias/patologia , Masculino , Pessoa de Meia-Idade , Patologia Molecular , Adulto Jovem , Peixe-Zebra/genéticaRESUMO
BACKGROUND: The central vein sign (CVS) on brain magnetic resonance imaging (MRI) is a promising diagnostic marker for distinguishing adult multiple sclerosis (MS) from other demyelinating conditions, but its prevalence is not well-established in pediatric-onset multiple sclerosis (POMS) versus myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). MOGAD can mimic MS radiologically. This study seeks to determine the utility of CVS, together with other radiological findings, in distinguishing POMS from MOGAD in children. METHODS: Children with POMS or MOGAD were identified in a pediatric demyelinating database. Two reviewers, blinded to diagnosis, fused fluid-attenuated inversion recovery sequences and susceptibility-weighted imaging from clinical imaging to identify CVS. Agreement in CVS number was reported using intraclass correlation coefficients (ICC). We performed topographic analyses as well as characterization of the clinical information and lesions on brain, spinal cord, and orbital MRI when available. RESULTS: Twenty children, 10 with POMS and 10 with MOGAD, were assessed. The median lesion percentage of CVS was higher in POMS versus MOGAD for both raters (rater 1: 80% vs 9.8%; rater 2: 22.7% vs 7.5%). Inter-rater reliability for identifying total white matter lesions was strong (ICC 0.94 [95% confidence interval [CI] 0.84, 0.97]); however, it was poor for detecting CVS lesions (ICC -0.17 [95% CI: -0.37, 0.58]). CONCLUSION: The CVS can be a useful diagnostic tool for differentiating POMS from MOGAD. However, advanced clinical imaging tools that can better detect CVS are needed to increase inter-rater reliability before clinical application.
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Esclerose Múltipla , Humanos , Esclerose Múltipla/diagnóstico por imagem , Glicoproteína Mielina-Oligodendrócito , Reprodutibilidade dos Testes , Encéfalo/diagnóstico por imagem , Bases de Dados Factuais , AutoanticorposRESUMO
Importance: Autoimmune encephalitis misdiagnosis can lead to harm. Objective: To determine the diseases misdiagnosed as autoimmune encephalitis and potential reasons for misdiagnosis. Design, Setting, and Participants: This retrospective multicenter study took place from January 1, 2014, to December 31, 2020, at autoimmune encephalitis subspecialty outpatient clinics including Mayo Clinic (n = 44), University of Oxford (n = 18), University of Texas Southwestern (n = 18), University of California, San Francisco (n = 17), University of Washington in St Louis (n = 6), and University of Utah (n = 4). Inclusion criteria were adults (age ≥18 years) with a prior autoimmune encephalitis diagnosis at a participating center or other medical facility and a subsequent alternative diagnosis at a participating center. A total of 393 patients were referred with an autoimmune encephalitis diagnosis, and of those, 286 patients with true autoimmune encephalitis were excluded. Main Outcomes and Measures: Data were collected on clinical features, investigations, fulfillment of autoimmune encephalitis criteria, alternative diagnoses, potential contributors to misdiagnosis, and immunotherapy adverse reactions. Results: A total of 107 patients were misdiagnosed with autoimmune encephalitis, and 77 (72%) did not fulfill diagnostic criteria for autoimmune encephalitis. The median (IQR) age was 48 (35.5-60.5) years and 65 (61%) were female. Correct diagnoses included functional neurologic disorder (27 [25%]), neurodegenerative disease (22 [20.5%]), primary psychiatric disease (19 [18%]), cognitive deficits from comorbidities (11 [10%]), cerebral neoplasm (10 [9.5%]), and other (18 [17%]). Onset was acute/subacute in 56 (52%) or insidious (>3 months) in 51 (48%). Magnetic resonance imaging of the brain was suggestive of encephalitis in 19 of 104 patients (18%) and cerebrospinal fluid (CSF) pleocytosis occurred in 16 of 84 patients (19%). Thyroid peroxidase antibodies were elevated in 24 of 62 patients (39%). Positive neural autoantibodies were more frequent in serum than CSF (48 of 105 [46%] vs 7 of 91 [8%]) and included 1 or more of GAD65 (n = 14), voltage-gated potassium channel complex (LGI1 and CASPR2 negative) (n = 10), N-methyl-d-aspartate receptor by cell-based assay only (n = 10; 6 negative in CSF), and other (n = 18). Adverse reactions from immunotherapies occurred in 17 of 84 patients (20%). Potential contributors to misdiagnosis included overinterpretation of positive serum antibodies (53 [50%]), misinterpretation of functional/psychiatric, or nonspecific cognitive dysfunction as encephalopathy (41 [38%]). Conclusions and Relevance: When evaluating for autoimmune encephalitis, a broad differential diagnosis should be considered and misdiagnosis occurs in many settings including at specialized centers. In this study, red flags suggesting alternative diagnoses included an insidious onset, positive nonspecific serum antibody, and failure to fulfill autoimmune encephalitis diagnostic criteria. Autoimmune encephalitis misdiagnosis leads to morbidity from unnecessary immunotherapies and delayed treatment of the correct diagnosis.
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Doenças Autoimunes do Sistema Nervoso , Encefalite , Doenças Neurodegenerativas , Feminino , Humanos , Adulto , Adolescente , Pessoa de Meia-Idade , Masculino , Estudos Retrospectivos , Encefalite/diagnóstico , Erros de DiagnósticoRESUMO
Background and Objectives: Diagnostic criteria emphasize the use of sensitive and disease-specific tests to distinguish patients with rapidly progressive dementia (RPD) due to Creutzfeldt-Jakob disease (CJD) vs other causes (mimics). These tests are often performed in specialized centers, with results taking days to return. There is a need to leverage clinical features and rapidly reporting tests to distinguish patients with RPD due to CJD from those due to other causes (mimics) early in the symptomatic course. Methods: In this case-control series, clinical features and the results of diagnostic tests were compared between mimics (n = 11) and patients with definite (pathologically proven, n = 33) or probable CJD (with positive real-time quaking-induced conversion [RT-QuIC], n = 60). Patients were assessed at Mayo Clinic Enterprise or Washington University from January 2014 to February 2021. Mimics were enrolled in prospective studies of RPD; mimics met the diagnostic criteria for probable CJD but did not have CJD. Results: Mimics were ultimately diagnosed with autoimmune encephalitis (n = 6), neurosarcoidosis, frontotemporal lobar degeneration with motor neuron disease, dural arteriovenous fistula, cerebral amyloid angiopathy with related inflammation, and systemic lupus erythematous with polypharmacy. Age at symptom onset, sex, presenting features, and MRI and EEG findings were similar in CJD cases and mimics. Focal motor abnormalities (49/93, 11/11), CSF leukocytosis (4/92, 5/11), and protein >45 mg/dL (39/92, 10/11) were more common in mimics (p < 0.01). Positive RT-QuIC (77/80, 0/9) and total tau >1149 pg/mL (74/82, 2/10) were more common in CJD cases (all p < 0.01). Protein 14-3-3 was elevated in 64/89 CJD cases and 4/10 mimics (p = 0.067). Neural-specific autoantibodies associated with autoimmune encephalitis were detected within the serum (5/9) and CSF (5/10) of mimics; nonspecific antibodies were detected within the serum of 9/71 CJD cases. Discussion: Immune-mediated, vascular, granulomatous, and neurodegenerative diseases may mimic CJD at presentation and should be considered in patients with early motor dysfunction and abnormal CSF studies. The detection of atypical features-particularly elevations in CSF leukocytes and protein-should prompt evaluation for mimics and consideration of empiric treatment while waiting for the results of more specific tests.
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The tissue-specific drivers of neurosarcoidosis remain poorly defined. To identify cerebrospinal fluid (CSF) specific, antigen-driven T and B cell responses, we performed single-cell RNA sequencing of CSF and blood cells from neurosarcoid participants coupled to T and B cell receptor sequencing. In contrast to pulmonary sarcoidosis, which is driven by CD4 T cells, we found CD8 T cell clonal expansion enriched in the neurosarcoid CSF. These CSF-enriched CD8 T cells were composed of two subsets with differential expression of EBI2, CXCR3, and CXCR4. Lastly, our data suggest that IFNγ signaling may distinguish neurosarcoidosis from other neurological disorders.
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Doenças do Sistema Nervoso Central , Sarcoidose , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Doenças do Sistema Nervoso Central/líquido cefalorraquidiano , Humanos , Sarcoidose/líquido cefalorraquidianoRESUMO
The COVID-19 pandemic has a disruptive impact on neurology education, necessitating creative adjustments in the delivery of education, clinical training and wellbeing. In this piece, a group of educators reflects on challenges and lessons learnt on teaching, wellbeing and telemedicine, and how these can shape the future of neurology education. Developing standardized, rigorous evaluation of teaching methods and telemedicine, reinforcing wellbeing resources and promoting international educational collaborations can improve neurology training during and after the pandemic.
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Intravascular lymphoma is an uncommon subtype of B-cell lymphoma with neoplastic cells limited to the lumen of small blood vessels. We report a case of a 52-year-old man who presented with constitutional symptoms and rapidly progressive dementia. He was found to have diffuse leptomeningeal and faint parenchymal enhancement on magnetic resonance imaging and was subsequently diagnosed with intravascular lymphoma following a brain biopsy. He responded remarkably well to systemic and intrathecal chemotherapy. The diagnosis and treatment of intravascular lymphoma have been guided by a few case reports and are largely based on expert opinion.
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The clinical utility of fluoroquinolones (FQs) for the treatment of Pseudomonas aeruginosa (PA) and other serious Gram-negative infections is currently decreasing due to the rapid emergence of resistance. Because previous studies have shown that efflux is a common mechanism contributing to FQ resistance in PA, one suggested approach to extend the longevity of this class of drugs is combination therapy with an efflux pump inhibitor (EPI). In order to determine the viability of this approach, it is necessary to understand the relative contribution of efflux- vs. target-mediated mechanisms of FQ resistance in the clinic. A set of 26 recent PA clinical isolates were characterized for antibiotic resistance profiles, efflux pump expression, topoisomerase mutations, and FQ susceptibility with and without an EPI. The contribution of OprM to the overall antibiotic resistance was assessed in a subset of these strains. Our results suggest that the co-administration of an EPI with FQs or other antibiotics currently in use would not be sufficient to combat the complexity of resistance mechanisms now present in many clinical isolates.
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Fluoroquinolonas/farmacologia , Mutação , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Antibacterianos/farmacologia , Proteínas da Membrana Bacteriana Externa/antagonistas & inibidores , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , DNA Topoisomerases Tipo II/genética , DNA Topoisomerases Tipo II/metabolismo , Farmacorresistência Bacteriana , Humanos , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Testes de Sensibilidade Microbiana , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/isolamento & purificação , Pseudomonas aeruginosa/metabolismoRESUMO
Clostridium septicum is a spore-forming anaerobe frequently implicated in cases of gangrenous dermatitis (GD) and other spontaneously occurring myonecrotic infections of poultry. Although C. septicum is readily cultured from diseased tissues it can be difficult to enumerate due to its tendency to swarm over the surface of agar plates. In this study a quantitative real-time PCR assay was developed in order to more accurately measure the levels of C. septicum in healthy as well as GD associated poultry samples. The assay was specifically designed to target the C. septicum alpha toxin gene, csa, which is, to our knowledge, carried by all strains of C. septicum and has been shown to be essential for virulence. Genomic DNAs from a diverse collection of bacterial species, including closely related Clostridium chauvoei, Clostridium carnis, Clostridium tertium as well as several strains of Clostridium perfringens, all failed to produce a positive reaction. An approximate reproducible limit of detection in spiked extracts of at least 10(3) cfu/g of C. septicum was observed for a variety of different sample types. C. septicum levels in broiler chicken field samples estimated from the results of qPCR were statistically correlated to culture based enumerations obtained from those same tissues.
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Galinhas/microbiologia , Clostridium septicum/genética , Clostridium septicum/isolamento & purificação , Dermatite/veterinária , Gangrena Gasosa/veterinária , Reação em Cadeia da Polimerase/métodos , Doenças das Aves Domésticas/microbiologia , Animais , Bioensaio , Dermatite/complicações , Dermatite/diagnóstico , Dermatite/microbiologia , Gangrena Gasosa/complicações , Gangrena Gasosa/diagnóstico , Gangrena Gasosa/microbiologia , Reação em Cadeia da Polimerase/veterinária , Doenças das Aves Domésticas/diagnóstico , Padrões de Referência , Sensibilidade e Especificidade , Fatores de TempoRESUMO
Progressive multifocal leukoencephalopathy (PML) is a viral disease of the brain associated with immunodeficiency, immune suppressing medications, and malignancy. In the absence of effective anti-viral therapy for the causative JC virus, immune restoration has emerged as the critical therapeutic alternative. The evolving treatment of PML (and other rare JC virus-associated neurologic syndromes) requires consideration of baseline immune functioning and comorbid diseases while selecting from a number of therapeutic options to restore an effective immune response. This review focuses on the current options for management of PML in typical situations where this disease presents, including several where immune restoration is a standard therapeutic approach such as in PML associated with HIV/AIDS and in multiple sclerosis associated with natalizumab. Other circumstances in which PML occurs including associated with primary immunodeficiencies, malignancies, and transplants present greater challenges to immune reconstitution, but emerging concepts may enhance therapeutic options for these situations. Particular attention is focused on recent experience with checkpoint inhibitors, guidance for MS drug discontinuation, and strategies to monitor and facilitate immune restoration.
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Reconstituição Imune/imunologia , Imunossupressores/administração & dosagem , Imunossupressores/imunologia , Leucoencefalopatia Multifocal Progressiva/imunologia , Leucoencefalopatia Multifocal Progressiva/terapia , Animais , Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais Humanizados/imunologia , Humanos , Natalizumab/administração & dosagem , Natalizumab/imunologia , Resultado do TratamentoRESUMO
Grain and soil were sampled across a large part of Amhara, Ethiopia in a study motivated by prior evidence of selenium (Se) deficiency in the Region's population. The grain samples (teff, Eragrostis tef, and wheat, Triticum aestivum) were analysed for concentration of Se and the soils were analysed for various properties, including Se concentration measured in different extractants. Predictive models for concentration of Se in the respective grains were developed, and the predicted values, along with observed concentrations in the two grains were represented by a multivariate linear mixed model in which selected covariates, derived from remote sensor observations and a digital elevation model, were included as fixed effects. In all modelling steps the selection of predictors was done using false discovery rate control, to avoid over-fitting, and using an α-investment procedure to maximize the statistical power to detect significant relationships by ordering the tests in a sequence based on scientific understanding of the underlying processes likely to control Se concentration in grain. Cross-validation indicated that uncertainties in the empirical best linear unbiased predictions of the Se concentration in both grains were well-characterized by the prediction error variances obtained from the model. The predictions were displayed as maps, and their uncertainty was characterized by computing the probability that the true concentration of Se in grain would be such that a standard serving would not provide the recommended daily allowance of Se. The spatial variation of grain Se was substantial, concentrations in wheat and teff differed but showed the same broad spatial pattern. Such information could be used to target effective interventions to address Se deficiency, and the general procedure used for mapping could be applied to other micronutrients and crops in similar settings.
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Selênio , Grão Comestível , Etiópia , Solo , TriticumRESUMO
We evaluated the effectiveness of lime and red mud (by-product of aluminium manufacturing) to reduce metal availability to Festuca rubra and to allow re-vegetation on a highly contaminated brown-field site. Application of both lime and red mud (at 3 or 5%) increased soil pH and decreased metal availability. Festuca rubra failed to establish in the control plots, but grew to a near complete vegetative cover on the amended plots. The most effective treatment in decreasing grass metal concentrations in the first year was 5% red mud, but by year two all amendments were equally effective. In an additional pot experiment, P application in combination with red mud or lime decreased the Pb concentration, but not total uptake of Pb in Festuca rubra compared to red mud alone. The results show that both red mud and lime can be used to remediate a heavily contaminated acid soil to allow re-vegetation.
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Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos , Metais Pesados , Poluentes do Solo , Silicatos de Alumínio , Carbonato de Cálcio , Argila , Festuca/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Fósforo , Fatores de TempoRESUMO
Field trials were undertaken to investigate the effect of the application of metal mobilizing agents, different sowing strategies and length of growing season on the extraction of Cd and Zn from soils by Thlaspi caerulescens and Arabidopsis halleri. None of the mobilizing agents used enhanced metal accumulation by T. caerulescens. Between 1998 and 2000, on average across plots where Cd or Zn exceeded allowable limits, T. caerulescens removed 1.3 and 0.3% of the total soil Cd and Zn. In one season when T. caerulescens was grown for 14 months, 21.7 and 4.4% of the total soil Cd and Zn was removed. This was larger than values found when T. caerulescens was grown for 4 months. A. halleri accumulated similar concentrations of Zn, but lower Cd concentrations than T. caerulescens. The results indicate that metal phytoextraction using T. caerulescens can be used to clean up soils moderately contaminated by Cd.
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Poluição Ambiental , Resíduos Industriais , Metais Pesados , Poluentes do Solo , Thlaspi , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Biodegradação Ambiental , Cádmio/metabolismo , Quelantes/farmacologia , Ácido Cítrico/farmacologia , Ácido Edético/farmacologia , Metais Pesados/metabolismo , Ácido Nitrilotriacético/farmacologia , Poluentes do Solo/metabolismo , Thlaspi/crescimento & desenvolvimento , Thlaspi/metabolismo , Zinco/metabolismoAssuntos
Doenças do Sistema Nervoso Central/diagnóstico por imagem , Sarcoidose/diagnóstico por imagem , Medula Espinal/diagnóstico por imagem , Doenças do Sistema Nervoso Central/tratamento farmacológico , Feminino , Humanos , Imunossupressores/uso terapêutico , Pessoa de Meia-Idade , Sarcoidose/tratamento farmacológicoRESUMO
The anticancer activity of cisplatin derives from its ability to bind and cross-link DNA, with the major adduct being the 1,2-d(GpG) intrastrand cross-link. Here, the consequences of this adduct on the conformation, thermal stability, and energetics of duplex DNA are assessed, and the modulation of these parameters by the sequence context of the adduct is evaluated. The properties of a family of 15-mer DNA duplexes containing a single 1,2-d(GpG) cis-¿Pt(NH(3))(2)¿(2+) intrastrand cross-link are probed in different sequence contexts where the flanking base-pairs are systematically varied from T.A to C.G to A.T. By using a combination of spectroscopic and calorimetric techniques, the structural, thermal, and thermodynamic properties of each duplex, both with and without the cross-link, are characterized. Circular dichroism spectroscopic data reveal that the cross-link alters the structure of the host duplex in a manner consistent with a shift from a B-like to an A-like conformation. Thermal denaturation data reveal that the cross-link induces substantial thermal and thermodynamic destabilization of the host duplex. Significantly, the magnitudes of these cross-link-induced effects on duplex structure, thermal stability, and energetics are influenced by the bases that flank the adduct. The presence of flanking A.T base-pairs, relative to T.A or C.G base-pairs, enhances the extent of cross-link-induced alteration to an A-like conformation and dampens the extent of cross-link-induced duplex destabilization. These results are discussed in terms of available structural data, and in terms of the selective recognition of cisplatin-DNA adducts by HMG-domain proteins.
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Cisplatino/metabolismo , Reagentes de Ligações Cruzadas/metabolismo , DNA/química , DNA/metabolismo , Conformação de Ácido Nucleico , Pareamento de Bases/genética , Pareamento de Bases/efeitos da radiação , Sequência de Bases , Varredura Diferencial de Calorimetria , Dicroísmo Circular , DNA/genética , DNA/efeitos da radiação , Adutos de DNA/química , Adutos de DNA/genética , Adutos de DNA/metabolismo , Adutos de DNA/efeitos da radiação , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Conformação de Ácido Nucleico/efeitos da radiação , Desnaturação de Ácido Nucleico/efeitos da radiação , Oligodesoxirribonucleotídeos/química , Oligodesoxirribonucleotídeos/genética , Oligodesoxirribonucleotídeos/metabolismo , Oligodesoxirribonucleotídeos/efeitos da radiação , Especificidade por Substrato , Temperatura , Termodinâmica , Raios UltravioletaRESUMO
In this work we present a method for improving the speed of spin-spin relaxation time (T2) measurements for compartmental analysis in stimulated echo localized magnetic resonance spectroscopy without reducing the sampling density. The technique uses a progressive repetition time (TR) to compensate for echo time (TE) dependent variations in saturation effects that would otherwise modulate the received signal at short TRs. The method was validated in T2 studies on 10 young healthy subjects in spectroscopic voxels localized along either the right or left Sylvian fissure (2 x 2 x 1.5 cm3, 10 ms mixing time (TM), 2048 data points, 819.2 ms acquisition time). The TR was automatically adjusted so that TR-TM-TE/2 was kept constant as the TE was incremented. Compared to long TR T2 experiments, the progressive TR technique consistently replicated the T2 relaxation times and reference signals of the tissue water compartment while reducing the data acquisition time by more than 50%. The percent error was on average less than 2% for estimates of T2 and S(0) for the tissue water, an indication that the progressive TR technique is a useful method for determining the tissue water signal for internal referencing.