Identificação de sinais e sintomas visuais associados à exposição aos dispositivos emissores de luz azul / Identification of signs and symptoms associated with exposure to blue light emitting equipment

 Computadores, smartphones e tablets são agentes da denominada “era digital”, considerando sobretudo à ampliação do ensino à distância (EAD). Embora fundamentais para o trabalho, lazer e comunicação, estes dispositivos emitem quantidades significativas de radiação óptica de luz azul através de suas telas, cuja exposição excessiva tem sido associada a problemas oculares e de visão, entre outros. O presente estudo teve como objetivo avaliar o impacto da exposição à luz azul emitida por dispositivos eletrônicos e lâmpadas LED em trabalhadores de um escritório administrativo, relativos à saúde visual e qualidade do sono. A coleta dos dados foi realizada a partir da aplicação de um questionário com roteiro estruturado, cujos participantes foram escolhidos aleatoriamente. Os resultados indicaram que os sintomas oculares mais comuns, relatados, foram tensão ocular, hiperemia e irritação/ardor, compatíveis com a Síndrome da Visão de Computador (SVC). Dificuldade para adormecer e manter o sono também foram citadas. O conhecimento quanto a existência da luz azul e possíveis riscos associados demonstraram-se baixos, tanto por parte dos participantes quanto da empresa, que não orienta seus funcionários acerca do tema

Deregulated Cdc6 inhibits DNA replication and suppresses Cdc7-mediated phosphorylation of Mcm2–7 complex

Mcm2–7 is recruited to eukaryotic origins of DNA replication by origin recognition complex, Cdc6 and Cdt1 thereby licensing the origins. Cdc6 is essential for origin licensing during DNA replication and is readily destabilized from chromatin after Mcm2–7 loading. Here, we show that after origin licensing, deregulation of Cdc6 suppresses DNA replication in Xenopus egg extracts without the involvement of ATM/ATR-dependent checkpoint pathways. DNA replication is arrested specifically after chromatin binding of Cdc7, but before Cdk2-dependent pathways and deregulating Cdc6 after this step does not impair activation of origin firing or elongation. Detailed analyses revealed that Cdc6 deregulation leads to strong suppression of Cdc7-mediated hyperphosphorylation of Mcm4 and subsequent chromatin loading of Cdc45, Sld5 and DNA polymerase α. Mcm2 phosphorylation is also repressed although to a lesser extent. Remarkably, Cdc6 itself does not directly inhibit Cdc7 kinase activity towards Mcm2–4–6–7 in purified systems, rather modulates Mcm2–7 phosphorylation on chromatin context. Taken together, we propose that Cdc6 on chromatin acts as a modulator of Cdc7-mediated phosphorylation of Mcm2–7, and thus destabilization of Cdc6 from chromatin after licensing is a key event ensuring proper transition to the initiation of DNA replication

Development of N-[4-[6-(Isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methyl-4-[(11)C]methylbenzamide for Positron Emission Tomography Imaging of Metabotropic Glutamate 1 Receptor in Monkey Brain.

Three novel 4-substituted benzamides have been synthesized as potential ligands for the positron emission tomography (PET) imaging of metabotropic glutamate 1 (mGlu1) receptor in the brain. Of these compounds, N-(4-(6-(isopropylamino)pyrimidin-4-yl)-1,3-thiazol-2-yl)-N,4-dimethylbenzamide (4) exhibited the highest binding affinity (Ki =13.6 nM) for mGlu1 and was subsequently labeled with carbon-11. In vitro autoradiography using rat brain sections showed that [11C]4 binding was consistent with the distribution of mGlu1, with high specific binding in the cerebellum and thalamus. PET studies with [11C]4 in monkey showed a high brain uptake and a kinetic profile suitable for quantitative analysis. Pretreatment with a mGlu1-selective ligand 16 largely decreased the brain uptake, indicating high in vivo specific binding of [11C]4 to mGlu1. In metabolite analysis, only unchanged [11C]4 was found in the brain. [11C]4 is a useful PET ligand for the imaging and quantitative analysis of mGlu1 in monkey brain and merits further evaluation in humans

Development of [11C]MFTC for PET Imaging of Fatty Acid Amide Hydrolase in Rat and Monkey Brains

We developed 2-methylpyridin-3-yl-4-(5-(2-fluorophenyl)-4H-1,2,4-triazol-3-yl)piperidine-1-[11C]carboxylate ([11C]MFTC) as a promising PET tracer for in vivo imaging of fatty acid amide hydrolase (FAAH) in rat and monkey brains. [11C]MFTC was synthesized by reacting 3-hydroxy-2-methylpyridine (2) with [11C]phosgene ([11C]COCl2), followed by reacting with 4-(5-(2-fluorophenyl)-4H-1,2,4-triazol-3-yl)piperidine (3), with a 20 ± 4.6% radiochemical yield (decay-corrected, n = 30) based on [11C]CO2 and 40 min synthesis time from the end of bombardment. A biodistribution study in mice showed high uptake of radioactivity in FAAH-rich organs, including the lung, liver, and kidneys. Positron emission tomography (PET) summation images of rat brains showed high radioactivity in the frontal cortex, cerebellum, and hippocampus, which was consistent with the regional distribution pattern of FAAH in rodent brain. Pretreatment with MFTC or FAAH-selective URB597 significantly reduced the uptake in the brain. PET imaging of monkey brain showed relatively high uptake in the whole brain, particularly in the occipital cortex, which was also inhibited by treatment with MFTC or URB597. More than 96% of the total radioactivity was irreversible in the brain homogenate of rats 5 min after the radiotracer injection. The specific in vivo FAAH binding indicates that [11C]MFTC is a promising PET tracer for visualizing FAAH in the brain

Characterization of 1-(2-[18F]fluoro-3-pyridyl)-4-(2-isopropyl-1-oxo- isoindoline-5-yl)-5-methyl-1H-1,2,3-triazole, a PET ligand for imaging the metabotropic glutamate receptor type 1 in rat and monkey brains

We developed 1-(2-[18F]fluoro-3-pyridyl)-4-(2-isopropyl-1-oxoisoindoline-5-yl)-5-methyl-1H-1,2,3-triazole ([18F]FPIT) as a promising positron emission tomography (PET) ligand for in vitro and in vivo imaging of metabotropic glutamate receptor type 1 (mGluR1) in rat and monkey brains. In vitro autoradiography with [18F]FPIT was used to determine the distribution of radioactivity in rat and monkey brains. In vivo experiments were performed using dissection and small-animal PET onrats, and PET on monkey. Metabolite analysis was performed on rat plasma and brain, and monkey plasma. Autoradiography of rat and monkey brains showed that [18F]FPIT binding is aligned with the reported distribution of mGluR1 with high specific binding in the cerebellum and thalamus. PET study on rat and monkey showed high brain uptake and distribution patterns consistent with those seen in the autoradiographic studies. The radioactivity in the brain was significantly decreasedby pre-treatment with unlabeled FPIT, indicative of a specific signal for mGluR1 that was inhibited by mGluR1-selective ligand JNJ-16259865 in the brain. Metabolite analysis showed that the percentage of unchanged [18F]FPIT was 89% in the brain homogenate of rat at 90 min after injection. In the monkey plasma, the percentage of unchanged form was 50% at 90 min. [18F]FPIT produced in vitro and in vivo signalsto visualize mGluR1 expression in rat and monkey brains, suggesting the usefulness of [18F]FPIT for imaging mGluR1 in human brain

In vivo PET imaging of the behaviorally active designer receptor in macaque monkeys

DREADDs (Designer Receptors Exclusively Activated by Designer Drug) are pharmacogenetic agents that, when expressed on neuronal cell membranes and activated through systemic delivery of the targeting drug, will inhibit (or excite) activity of all neurons expressing the DREADD. Using the hM4Di receptor, an inhibitory DREADD that can be activated by clozapine-N-oxide (CNO), we have been able to (1) monitor the location and intensity of receptor expression by in vivo PET-imaging, and (2) modify monkey’s behavior reversibly. In our experiments, a lenti viral vector expressing the hM4Di receptor was injected into the putamen of two macaque monkeys. PET imaging using a ligand targeting the receptor showed a focal patch of high uptake at the injection site. The location matched the site of neuronal hM4Di expression identified histochemically post-mortem. Measuring uptake of the PET ligand following different CNO doses yielded to estimate the dose-occupancy relationship for binding of CNO to the hM4Di receptor. To measure the behavioral effect, an AAV vector expressing the hM4Di receptor was injected bilaterally into the ventral striatum of a monkey that had been trained to perform a reward-size task. PET imaging verified the expression of the hM4Di receptor. The monkey’s performance was altered by CNO treatment in a manner similar to that seen after bilateral inactivation of the ventral striatum with muscimol in two other monkeys. Given that PET-imaging is capable of monitoring in vivo DREADD expression, the DREADD provides a novel tool to study the neural mechanism of higher brain functions in nonhuman primates and, also, contributes to the development of human therapeutic settings.Neuroscience 201