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1.
Eur J Endocrinol ; 185(1): 109-120, 2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-33886494

RESUMO

Background: Primary hyperparathyroidism is characterized by an autonomous hypersecretion of parathyroid hormone by one or more parathyroid glands. Preoperative localization of the affected gland(s) is of key importance in order to allow minimally invasive surgery. At the moment, 11C-Methionine and 18F-Fluorocholine PET studies appear to be among the most promising second-line localization techniques; their comparative diagnostic performance, however, is still unknown. Methods: PubMed/Medline and Embase databases were searched up to October 2020 for studies estimating the diagnostic accuracy of 11C-Methionine PET or 18F-Fluorocholine PET for parathyroid localization in patients with primary hyperparathyroidism. Pooled sensitivity and positive predictive value were calculated for each tracer on a 'per-lesion' basis and compared using a random-effect model subgroup analysis. Results: In total, 22Twenty-two studies were finally considered in the meta-analysis. Of these, 8 evaluated the diagnostic accuracy of 11C-Methionine and 14 that of 18F-Fluorocholine. No study directly comparing the two tracers was found. The pooled sensitivity of 18F-Fluorocholine was higher than that of 11C-Methionine (92% vs 80%, P < 0.01), while the positive predictive value was similar (94% vs 95%, P = 0.99). These findings were confirmed in multivariable meta-regression models, demonstrating their apparent independence from other possible predictors or confounders at a study level. Conclusion: This was the first meta-analysis that specifically compared the diagnostic accuracy of 11C-Methionine and 18F-Fluorocholine PET for parathyroid localization in patients with primary hyperparathyroidism. Our results suggested a superior performance of 18F-Fluorocholine in terms of sensitivity, while the two tracers had comparable accuracy in terms of positive predictive value.


Assuntos
Adenoma/diagnóstico por imagem , Colina/análogos & derivados , Hiperparatireoidismo Primário/diagnóstico por imagem , Metionina , Neoplasias das Paratireoides/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Adenoma/cirurgia , Radioisótopos de Carbono , Radioisótopos de Flúor , Humanos , Hiperparatireoidismo Primário/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos , Neoplasias das Paratireoides/cirurgia , Paratireoidectomia , Cuidados Pré-Operatórios
2.
J Environ Radioact ; 233: 106585, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33761388

RESUMO

This study examined the short term transfer of carbon-14 (14C) in the common carp Cyprinus carpio under laboratory conditions. Various experiments were achieved in order to investigate direct or trophic transfer for 4 days, using waterborne 14C-labelled arginine or 14C-labelled food pellets respectively. Radiolabelled food was prepared with 14C-labelled arginine or glucose in order to test how transfer kinetics might vary with the biochemical form of 14C. Elimination experiments were achieved using fish fed for 5 days on radiolabelled food and then placed under starvation for 4 days. In all experiments, water, food and fish activities were monitored every day. Different fish fractions (whole body, muscle) were sampled in order to elucidate the role of muscle as a potential storage. Results suggested that direct water-to-fish absorption rate was 20% d-1 per fish. Carps incorporated 14.3% of the absorbed 14C. Fish activity did not increase over days, due to a strong decrease in 14C concentration in the water (resulting from aquarium sorption). During trophic transfer experiments, food was entirely ingested and 14C sources rapidly assimilated. For either arginine or glucose, results suggested that 19-20% of ingested 14C was incorporated, yielding a significant increase in fish activity over days. No difference in mass-specific activity was observed among muscle and whole body. Total activity in the muscle represented 29%-32% of whole body activity, this proportion reflecting the contribution of muscle to whole body weight. During elimination experiments, results showed a significant decrease in whole body total activity and mass-specific activity with arginine. The decrease was not significant with glucose due to a great variability among fish. Results suggested that an essential amino-acid like arginine can be used as an energy source under starvation and that muscles can act as a storage for essential amino-acids.


Assuntos
Carpas , Monitoramento de Radiação , Animais , Radioisótopos de Carbono , Laboratórios
4.
J Vis Exp ; (168)2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33616103

RESUMO

Neutral lipids (NLs) are a class of hydrophobic, chargeless biomolecules that play key roles in energy and lipid homeostasis. NLs are synthesized de novo from acetyl-CoA and are primarily present in eukaryotes in the form of triglycerides (TGs) and sterol-esters (SEs). The enzymes responsible for the synthesis of NLs are highly conserved from Saccharomyces cerevisiae (yeast) to humans, making yeast a useful model organism to dissect the function and regulation of NL metabolism enzymes. While much is known about how acetyl-CoA is converted into a diverse set of NL species, mechanisms for regulating NL metabolism enzymes, and how mis-regulation can contribute to cellular pathologies, are still being discovered. Numerous methods for the isolation and characterization of NL species have been developed and used over decades of research; however, a quantitative and simple protocol for the comprehensive characterization of major NL species has not been discussed. Here, a simple and adaptable method to quantify the de novo synthesis of major NL species in yeast is presented. We apply 14C-acetic acid metabolic labeling coupled with thin layer chromatography to separate and quantify a diverse range of physiologically important NLs. Additionally, this method can be easily applied to study in vivo reaction rates of NL enzymes or degradation of NL species over time.


Assuntos
Radioisótopos de Carbono/análise , Cromatografia em Camada Delgada/métodos , Metabolismo dos Lipídeos , Lipídeos/análise , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Triglicerídeos/metabolismo , Homeostase , Humanos
6.
Isotopes Environ Health Stud ; 57(3): 217-235, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33528284

RESUMO

The Continental Intercalaire (CI) groundwaters of the Tidikelt (In-Salah region) are characterized by a high salinity and ion concentrations higher than the maximum standards for drinkability. The total dissolved solids range from 850 to 3390 mg L-1 for conductivities ranging from 1470 to 6780 µS cm-1. Their chemical facies is dominated by Cl-, SO42- and Na+, respectively. Alkali ions, Cl- and SO42- are acquired through the dissolution of Halite (NaCl) and Gypsum (CaSO4, 2H2O). CI waters have depleted δ values for 18O and 2H, corresponding to a cold end-member. This is an indication of a very homogeneous aquifer which is similar to what was observed for the CI in the eastern sub-basin (Great Oriental Erg) and for palaeowaters elsewhere in the Middle-East and Libya. Tritium analyses show that these waters are all very weakly tritiated, which is a testimony of the non-renewed character for these waters. Both δ13C and 14C measured on more than a dozen of samples also show that CI groundwaters are old, with ages comprised between 19,000 and 35,000 years with an average δ13C of -10 ‰. This means that these waters are derived from old precipitation whose features were totally different from the very scarce prevailing ones.


Assuntos
Água Subterrânea/análise , Água Subterrânea/química , Argélia , Isótopos de Carbono/análise , Radioisótopos de Carbono/análise , Cloretos/análise , Monitoramento Ambiental , Geologia , Isótopos de Oxigênio/análise , Salinidade , Sódio/análise , Trítio/análise
7.
PLoS One ; 16(1): e0245019, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33444356

RESUMO

The knowledge on the deposition and retention of the viral particle of SARS-CoV-2 in the respiratory tract during the very initial intake from the ambient air is of prime importance to understand the infectious process and COVID-19 initial symptoms. We propose to use a modified version of a widely tested lung deposition model developed by the ICRP, in the context of the ICRP Publication 66, that provides deposition patterns of microparticles in different lung compartments. In the model, we mimicked the "environmental decay" of the virus, determined by controlled experiments related to normal speeches, by the radionuclide 11C that presents comparable decay rates. Our results confirm clinical observations on the high virus retentions observed in the extrathoracic region and the lesser fraction on the alveolar section (in the order of 5), which may shed light on physiopathology of clinical events as well on the minimal inoculum required to establish infection.


Assuntos
/virologia , /fisiologia , Aerossóis/análise , Radioisótopos de Carbono , Humanos , Pulmão/metabolismo , Pulmão/patologia , Pulmão/virologia , Modelos Biológicos , Sistema Respiratório/metabolismo , Sistema Respiratório/virologia
8.
J Environ Sci Health B ; 56(3): 235-240, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33449826

RESUMO

Fertiactyl® is a foliar fertilizer with the potential to minimize the phytotoxicity effects caused by glyphosate drift in eucalyptus plants. As the interactions of the glyphosate and Fertiactyl® in tank mix on the plant behavior are not yet known, the objective was to evaluate the absorption and translocation of 14C-glyphosate, applied isolated and mixed in tank with Fertiactyl®, in young eucalyptus plants (clone I-144, Eucalyptus urophylla x E. grandis). The addition of Fertiactyl® to the mixture of 14C-glyphosate reduced the absorption by 94.3% in relation to the total absorbed at the end of the evaluation compared to plants treated only with 14C-glyphosate, i.e., Fertiactyl® protected the eucalyptus plants of the glyphosate intoxication by drift. The translocation rates from the treated leaves to the rest of the shoots and roots were low (<2% of the total recovered) in both treatments, suggest that restricted translocation is a mechanism of natural tolerance to glyphosate in plants of clone I-144. It is concluded that Fertiactyl®, mixed in the solution with glyphosate, protects young eucalyptus plants against glyphosate drift by reducing the amount of herbicide absorbed.


Assuntos
Eucalyptus/efeitos dos fármacos , Fertilizantes , Glicina/análogos & derivados , Herbicidas/farmacocinética , Radioisótopos de Carbono/farmacocinética , Eucalyptus/metabolismo , Glicina/farmacocinética , Glicina/toxicidade , Herbicidas/toxicidade , Folhas de Planta/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Distribuição Tecidual
9.
J Med Chem ; 64(3): 1223-1259, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33499603

RESUMO

The positron emission tomography (PET) molecular imaging technique has gained its universal value as a remarkable tool for medical diagnosis and biomedical research. Carbon-11 is one of the promising radiotracers that can report target-specific information related to its pharmacology and physiology to understand the disease status. Currently, many of the available carbon-11 (t1/2 = 20.4 min) PET radiotracers are heterocyclic derivatives that have been synthesized using carbon-11 inserted different functional groups obtained from primary and secondary carbon-11 precursors. A spectrum of carbon-11 PET radiotracers has been developed against many of the upregulated and emerging targets for the diagnosis, prognosis, prediction, and therapy in the fields of oncology, cardiology, and neurology. This review focuses on the carbon-11 radiochemistry and various target-specific PET molecular imaging agents used in tumor, heart, brain, and neuroinflammatory disease imaging along with its associated pathology.


Assuntos
Radioisótopos de Carbono/química , Cardiologia/métodos , Coração/diagnóstico por imagem , Imagem Molecular/métodos , Neoplasias/diagnóstico por imagem , Sistema Nervoso/diagnóstico por imagem , Neurologia/métodos , Tomografia por Emissão de Pósitrons/métodos , Radioterapia (Especialidade)/métodos , Compostos Radiofarmacêuticos/química , Animais , Humanos
10.
PLoS One ; 16(1): e0245580, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33481896

RESUMO

Iterative image reconstruction is widely used in positron emission tomography. However, it is known to contribute to quantitation bias and is particularly pronounced during dynamic studies with 11C-labeled radiotracers where count rates become low towards the end of the acquisition. As the strength of the quantitation bias depends on the counts in the reconstructed frame, it can differ from frame to frame of the acquisition. This is especially relevant in the case of neuro-receptor studies with simultaneous PET/MR when a bolus-infusion protocol is applied to allow the comparison of pre- and post-task effects. Here, count dependent changes in quantitation bias may interfere with task changes. We evaluated the impact of different framing schemes on quantitation bias and its propagation into binding potential (BP) using a phantom decay study with 11C and 3D OP-OSEM. Further, we propose a framing scheme that keeps the true counts per frame constant over the acquisition time as constant framing schemes and conventional increasing framing schemes are unlikely to achieve stable bias values during the acquisition time range. For a constant framing scheme with 5 minutes frames, the BP bias was 7.13±2.01% (10.8% to 3.8%) compared to 5.63±2.85% (7.8% to 4.0%) for conventional increasing framing schemes. Using the proposed constant true counts framing scheme, a stabilization of the BP bias was achieved at 2.56±3.92% (3.5% to 1.7%). The change in BP bias was further studied by evaluating the linear slope during the acquisition time interval. The lowest slope values were observed in the constant true counts framing scheme. The constant true counts framing scheme was effective for BP bias stabilization at relevant activity and time ranges. The mean BP bias under these conditions was 2.56±3.92%, which represents the lower limit for the detection of changes in BP during equilibrium and is especially important in the case of cognitive tasks where the expected changes are low.


Assuntos
Radioisótopos de Carbono , Imageamento Tridimensional/métodos , Tomografia por Emissão de Pósitrons , Marcação por Isótopo , Imagens de Fantasmas
11.
J Environ Radioact ; 226: 106345, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33032834

RESUMO

Accelerator mass spectrometry and benzene synthesis coupled with liquid scintillation spectrometry are often used for accurate measurements of 14C activity in the environmental matrices. Thermal oxidation is one of the methods employed for 14C determination in environmental matrices. In this method, the sample is oxidised at high temperature (600-900 °C) to convert carbon species to CO2 and trapped in an amine-based absorber for determining the activity in a liquid scintillation counting (LSC) system. In this study, the performance of a commercially available tube furnace system (pyrolyser), for batch combustion of samples, was evaluated for the determination of 14C specific activity in terrestrial biota samples. Significant improvements over the manufacturer specified method, which is primarily designed for analysis of samples with activity well above the environmental background level, was implemented to achieve accurate determination of 14C specific activity at ambient background level. In the improved method, the CO2 produced from the combustion of the sample was isolated from the combustion products through cryogenic trapping and then absorbed in the absorber (Carbo-Sorb E) through a simple off-line transfer process. This allowed (i) optimisation of CO2 absorption by the absorber (2.2477 g of CO2/10 mL), (ii) achieving good accuracy and precision in the measurements, and a minimum detectable activity value of 13 Bq kg-1C for a counting time of 300 min (7 Bq kg-1C for 1000 min), (iii) avoiding uncertainty associated with the determination of recovery of 14C in the combustion and trapping process, and (iv) elimination of the need for an independent determination of carbon content (%) for expressing the results in terms of 14C specific activity. The method is capable of yielding accurate results with a deviation of <2.4% from the target value for IAEA C3 quality assurance reference material (with a relative standard deviation of 1.40%, and relative error of 0.34%). The combined uncertainty (1σ) associated with the measurements was computed to be 3.4%. Upon optimisation, the suitability of the method for the determination of 14C specific activity in typical terrestrial biota samples of clean air region (region not affected by local anthropogenic sources) and for the quantification of a small increase in the 14C activity above ambient levels in the vicinity of a nuclear power plant is demonstrated.


Assuntos
Monitoramento de Radiação , Carbono , Radioisótopos de Carbono/análise , Centrais Nucleares
12.
Clin Nucl Med ; 46(1): e31-e33, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32657879

RESUMO

Three patients with neurological disorders (cerebral infarction, progressive multifocal leukoencephalopathy, and multiple sclerosis) underwent F-THK5351 and C-L-deprenyl PET on the same day to visualize lesions undergoing astrogliosis by measuring MAO-B activity. BPND map and SUV image with F-THK5351 as well as Ki map, Ki/K1 map and SUV image with C-L-deprenyl were created. F-THK5351 BPND maps and SUV images clearly identified the lesions undergoing astrogliosis. C-L-deprenyl Ki/K1 maps were close to F-THK5351 images, but very noisy. Ki maps and SUV images were likely affected by the effect of blood flow. Hence, F-THK5351 is superior to C-L-deprenyl for visualizing lesions undergoing astrogliosis.


Assuntos
Aminopiridinas/metabolismo , Radioisótopos de Carbono , Gliose/diagnóstico por imagem , Monoaminoxidase/metabolismo , Doenças do Sistema Nervoso/complicações , Tomografia por Emissão de Pósitrons , Quinolinas/metabolismo , Selegilina/metabolismo , Feminino , Gliose/complicações , Gliose/metabolismo , Humanos , Ligantes , Masculino
13.
Isotopes Environ Health Stud ; 57(2): 111-141, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33350358

RESUMO

Radiocarbon (14C) is useful for estimating groundwater ages for transport and water resource exploitation assessment. If the 14C content of dissolved inorganic carbon (14CDIC) is known, the age of groundwater can be estimated by applying a radiocarbon decay equation combined with an appropriate geochemical correction model. However, age determinations are subject to uncertainties caused by parameters which need to be estimated or assumed. Here, we discuss the principles of 14C-based groundwater age estimations and the corrections and errors that affect age determinations differently. Generally, the two factors that impact the results of 14C groundwater age are Type-1 and Type-2 errors. Type-1 errors are pulse-type changes on derived groundwater ages that are independent of the water age. Type-2 errors cause gradual changes on derived groundwater 14C ages that depend on the water age. The cumulative impact of these errors substantively reduces the accuracy and confidence of 14C age determinations and corrections. When using 14C for groundwater age, consideration of both error types along with the use of samples having a range of 14CDIC contents helps practitioners recognize and minimize 14C age uncertainty, especially for groundwater ages of <1000 and >30,000 years B.P.


Assuntos
Radioisótopos de Carbono/análise , Água Subterrânea/química , Isótopos de Carbono/análise , Monitoramento Ambiental/métodos , Datação Radiométrica/métodos , Fatores de Tempo , Incerteza
15.
PLoS One ; 15(12): e0243662, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33362206

RESUMO

Many recently published papers have investigated the spatial and temporal manifestation of the 4.2 ka BP climate event at regional and global scales. However, questions with regard to the potential drivers of the associated climate change remain open. Here, we investigate the interaction between Atlantic and Mediterranean climate forcing on the south-eastern Iberian Peninsula during the mid- to late Holocene using compound-specific hydrogen isotopes from fossil leaf waxes preserved in marine sediments. Variability of hydrogen isotope values in the study area is primarily related to changes in the precipitation source and indicates three phases of increased Mediterranean sourced precipitation from 5450 to 5350 cal. BP, from 5150 to 4300 cal. BP including a short-term interruption around 4800 cal. BP, and from 3400 to 3000 cal. BP interrupted around 3200 cal. BP. These phases are in good agreement with times of prevailing positive modes of the North Atlantic Oscillation (NAO) and reduced storm activity in the Western Mediterranean suggesting that the NAO was the dominant modulator of relative variability in precipitation sources. However, as previously suggested other modes such as the Western Mediterranean Oscillation (WeMO) may have altered this overall relationship. In this regard, a decrease in Mediterranean moisture source coincident with a rapid reduction in warm season precipitation during the 4.2 ka BP event at the south-eastern Iberian Peninsula might have been related to negative WeMO conditions.


Assuntos
Radioisótopos de Carbono/análise , Mudança Climática/história , Fósseis , Hidrogênio/análise , Folhas de Planta/química , Europa (Continente) , Cromatografia Gasosa-Espectrometria de Massas , Sedimentos Geológicos , História Antiga , Estações do Ano , Análise Espaço-Temporal , Ceras/análise
16.
Wiad Lek ; 73(9 cz. 2): 2076-2079, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33148863

RESUMO

OBJECTIVE: Positron emission tomography (PET/CT) is a non-invasive molecular imaging technique using isotopes with a short half-life usually in combination with chemical compounds. The most commonly used PET/CT tracer is 2-fluoro-2-deoxy-D-glucose labeled with fluorine (18-FDG). It is used mainly in oncological diagnostics as well as myocardial viability, epilepsy and inflammatory diagnostics. The tracer less commonly used in PET/CT could be carbon-labeled methionine (11C-MET). It is mainly used in the diagnosis of focal lesions in the central nervous system. There are also reports of the use of this tracer in diagnostics of the primary, secondary and tertiary hyperparathyroidism as well as multiple myeloma. This tracer may also be used in the diagnosis of lymphoproliferative diseases and solid tumors, although there is no clear evidence of its advantage over 18-FDG. CONCLUSION: Conclusion: Significant difficulties in the production and transport of this tracer and lack of reimbursement of this type of procedure in Poland limits the use of this tracer for scientific research.


Assuntos
Medicina Nuclear , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Radioisótopos de Carbono , Metionina , Polônia , Tomografia por Emissão de Pósitrons
17.
Eur J Endocrinol ; 183(6): 539-550, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33055298

RESUMO

Objective: Endocrine Society guidelines recommend adrenal venous sampling (AVS) in primary aldosteronism (PA) if adrenalectomy is considered. We tested whether functional imaging of adrenal cortex with 11C-metomidate (11C-MTO) could offer a noninvasive alternative to AVS in the subtype classification of PA. Design: We prospectively recruited 58 patients with confirmed PA who were eligible for adrenal surgery. Methods: Subjects underwent AVS and 11C-MTO-PET without dexamethasone pretreatment in random order. The lateralization of 11C-MTO-PET and adrenal CT were compared with AVS in all subjects and in a prespecified adrenalectomy subgroup in which the diagnosis was confirmed with immunohistochemical staining for CYP11B2. Results: In the whole study population, the concordance of AVS and 11C-MTO-PET was 51% and did not differ from that of AVS and adrenal CT (53%). The concordance of AVS and 11C-MTO-PET was 55% in unilateral and 44% in bilateral PA. In receiver operating characteristics analysis, the maximum standardized uptake value ratio of 1.16 in 11C-MTO-PET had an AUC of 0.507 (P = n.s.) to predict allocation to adrenalectomy or medical therapy with sensitivity of 55% and specificity of 44%. In the prespecified adrenalectomy subgroup, AVS and 11C-MTO-PET were concordant in 10 of 19 subjects with CYP11B2-positive adenoma and in 6 of 10 with CYP11B2-positivity without an adenoma. Conclusions: The concordance of 11C-MTO-PET with AVS was clinically suboptimal, and did not outperform adrenal CT. In a subgroup with CYP11B2-positive adenoma, 11C-MTO-PET identified 53% of cases. 11C-MTO-PET appeared to be inferior to AVS for subtype classification of PA.


Assuntos
Radioisótopos de Carbono/metabolismo , Hiperaldosteronismo/diagnóstico por imagem , Hiperaldosteronismo/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Córtex Suprarrenal/diagnóstico por imagem , Córtex Suprarrenal/metabolismo , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
18.
PLoS One ; 15(9): e0239484, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32956392

RESUMO

OBJECTIVE: To assess and compare the involvement of choroidal thickness (CT) in patients with mild cognitive impairment (MCI) and dementia due to Alzheimer's disease (AD) defined by amyloid PET and healthy controls (HC). METHODS: Sixty-three eyes from 34 AD patients [12 eyes (19.0%) with dementia and 51 eyes (80.9%) with MCI], positive to 11C-labelled Pittsburgh Compound-B with positron emission tomography (11C-PiB PET/CT), and the same number of sex- and age-paired HC were recruited. All participants underwent enhanced depth imaging optical coherence tomography (EDI-OCT) assessing CT at 14 measurements from 2 B-scans. Paired Student t-test was used to compare CT measurements between MCI, dementia and sex- and age-paired HC. A univariate generalized estimating equations model (GEE) test was performed to compare MCI and dementia individually with all HC included. RESULTS: Compared with HC, eyes from patients with positive 11C-PiB PET/CT showed a significant CT thinning in 5 selected locations (in foveal thickness in vertical scan, in temporal scan at 1500µm, in superior scan at 500µm and in inferior scan at 1000µm and 1500µm, p = 0.020-0.045) whilst few significant CT reduction data was reported in MCI or dementia individually versus HC. However, the GEE test identified significant CT thinning in AD compared with all HC included (p = 0.015-0.046). CONCLUSIONS: To our knowledge, the present study is the first measuring CT in eyes from MCI and dementia eyes positive to 11C-PiB PET/CT reporting a significant trend towards CT thinning in MCI patients which became more pronounced in dementia stage. We support further investigation involving larger and prospective OCT studies in AD population characterized with available biomarkers to describe whether choroidal vascular damage occurs specifically in prodromal stages of AD.


Assuntos
Doença de Alzheimer/patologia , Amiloide/análise , Corioide/ultraestrutura , Disfunção Cognitiva/patologia , Sintomas Prodrômicos , Tomografia de Coerência Óptica , Idoso , Doença de Alzheimer/diagnóstico por imagem , Compostos de Anilina , Antropometria , Área Sob a Curva , Radioisótopos de Carbono , Estudos de Casos e Controles , Disfunção Cognitiva/diagnóstico por imagem , Estudos Transversais , Progressão da Doença , Diagnóstico Precoce , Feminino , Humanos , Masculino , Neuroimagem , Variações Dependentes do Observador , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Compostos Radiofarmacêuticos , Reprodutibilidade dos Testes , Tiazóis
19.
Artigo em Russo | MEDLINE | ID: mdl-32929924

RESUMO

OBJECTIVE: To investigate the variations in 11C-methionine uptake in the intact brain tissue and in glial brain tumors of different types. MATERIAL AND METHODS: Forty patients (21 men, 19 women) with gliomas, Grade I-IV, underwent 11C-methionine PET-CT and contrast-enhanced MRI. Standardized uptake value (SUV), tumor-to-normal (T/N) ratios and tumor volume were analyzed. RESULTS: The high inter-subject variability was detected in the intact brain tissue (SUV in the frontal lobe (FL) varies from 0.47 to 1.73). Amino acid metabolism was more active in women than in men (FL SUV 1.32±0.22 and 1.05±0.24, respectively). T/N ratio better differentiates gliomas by the degree of anaplasia compared to SUV. Gliomas of Grade III (T/N=2.64±0.98) were significantly different (p<0.05) from those of Grade IV (T/N=3.83±0.75). The lowest level of methionine uptake was detected in diffuse astrocytomas (T/N=1.52±0.57), which was lower than with anaplastic astrocytomas (T/N=2.34±0.77, p<0.05). CONCLUSIONS: 11C-methionine PET-CT was informative in the high/low degree of malignancy differentiation (T/N 1.66±0.71 for Grade I-II and 3.18±1.06 for Grade III-IV, p<0.05). The method was also useful in separating astrocytomas of Grade II and III. The considerable variation of SUV in the intact brain tissue as well as the difference in uptake between selected areas of the brain were revealed.


Assuntos
Neoplasias Encefálicas , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Radioisótopos de Carbono , Feminino , Humanos , Masculino , Metionina , Tomografia por Emissão de Pósitrons
20.
PLoS One ; 15(8): e0237605, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804934

RESUMO

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Druksiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947-2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947-1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4-13.6 pMC during the first 15 years of plant operation. However, during the 2000-2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000-2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.


Assuntos
Radioisótopos de Carbono/análise , Sedimentos Geológicos/análise , Lagos/química , Monitoramento de Radiação/métodos , Animais , Radioisótopos de Césio/análise , Peixes/crescimento & desenvolvimento , Radioisótopos de Chumbo/análise , Lituânia , Centrais Nucleares
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