Photoacoustic imaging of occlusal incipient caries in the visible and near-infrared range.

PURPOSE: This study aimed to demonstrate the presence of dental caries through a photoacoustic imaging system with visible and near-infrared wavelengths, highlighting the differences between the 2 spectral regions. The depth at which carious tissue could be detected was also verified. MATERIALS AND METHODS: Fifteen permanent molars were selected and classified as being sound or having incipient or advanced caries by visual inspection, radiography, and optical coherence tomography analysis prior to photoacoustic scanning. A photoacoustic imaging system operating with a nanosecond pulsed laser as the light excitation source at either 532 nm or 1064 nm and an acoustic transducer at 5 MHz was developed, characterized, and used. En-face and lateral (depth) photoacoustic signals were detected. RESULTS: The results confirmed the potential of the photoacoustic method to detect caries. At both wavelengths, photoacoustic imaging effectively detected incipient and advanced caries. The reconstructed photoacoustic images confirmed that a higher intensity of the photoacoustic signal could be observed in regions with lesions, while sound surfaces showed much less photoacoustic signal. Photoacoustic signals at depths up to 4 mm at both 532 nm and 1064 nm were measured. CONCLUSION: The results presented here are promising and corroborate that photoacoustic imaging can be applied as a diagnostic tool in caries research. New studies should focus on developing a clinical model of photoacoustic imaging applications in dentistry, including soft tissues. The use of inexpensive light-emitting diodes together with a miniaturized detector will make photoacoustic imaging systems more flexible, user-friendly, and technologically viable.

Antioxidant cytochrome c-like activity of para-Mn(III)TMPyP.

Manganese porphyrins are well-known protectors against the deleterious effects of pro-oxidant species such as superoxide ions and hydrogen peroxide. The present study investigated the antioxidant cytochrome c-like activities of Mn(III)TMPyP [meso-tetrakis (4-N-methyl pyridinium) porphyrin] against superoxide ion and hydrogen peroxide that remained unexplored for this porphyrin. The association of TMPyP with a model of the inner mitochondrial membrane, cardiolipin (CL)-containing liposomes, shifted +30 mV vs. NHE (normal hydrogen electrode) redox potential of the Mn(II)/Mn(III) redox couple. In CL-containing liposomes, Mn(III)TMPyP was reduced by superoxide ions and recycled by Fe(III)cytochrome c to the oxidized form. Similarly, isolated rat liver mitoplasts added to a sample of Mn(II)TMPyP promoted immediate porphyrin reoxidation by electron transfer to the respiratory chain. These results show that Mn(III)TMPyP can act as an additional pool of Fe(III)cytochrome c capable of transferring electrons that escape from the IV complex back into the respiratory chain. Unlike Fe(II)cytochrome c, Mn(II)TMPyP was not efficient for hydrogen peroxide clearance. Therefore, by reducing cytochrome c, Mn(II)TMPyP can indirectly contribute to hydrogen peroxide elimination.

Vivência de gestação gemelar associada a Lúpus Eritematoso Sistêmico-LES / Experience of twin pregnancy associated with Systemic Lupus Erythematosus-SLE

Introdução: ainda existem muitas controvérsias sobre o binômio lúpus-gestação e, historicamente, se a gravidez for múltipla, torna-se preocupante, requerendo cuidados intensivos. Objetivo: relatar uma experiência de gravidez gemelar associada ao Lúpus Eritematoso Sistêmico. Metodologia: estudo qualitativo baseado em uma experiência gestacional utilizando-se entrevistas do tipo história oral de vida. Os relatos foram gravados, analisados e transcritos, garantindo a forma das narrativas. Resultados: a gravidez ocorreu após um ano do diagnóstico de Lúpus, ainda existindo sintomas e ainda em tratamento. O pré-natal ocorreu sem complicações. Percebeu-se nas narrativas, um estado de intensa satisfação com a gravidez, sem traços de estresse. O parto ocorreu por via vaginal, com 32 semanas, devido à ruptura de uma das bolsas amnióticas, sem intercorrências materno-fetais. Acreditamos que a prematuridade aconteceu devido aos dois fatores de riscos envolvidos na concepção: a gemelaridade e o lúpus. Conclusão: o binômio lúpus-gestação pode ter sucesso independente do tipo de gravidez (múltipla ou única). Entretanto, muitas variáveis devem ser consideradas: a atividade do Lúpus e sintomatologia na concepção, o tipo de atendimento no pré-natal e o estado emocional da gestante.

Introduction: there are still many controversies about the binomial lupus-gestation and, historically, if the pregnancy is multiple, it becomes worrying, requiring intensive care. Objective: The purpose of this study is to relate a case of twin pregnancy associated with active systemic lupus erythematosus. Methodology: qualitative research about gestational experience, supported by oral life history. Results: the woman was diagnosed one year before become pregnant, still symptomatic and in treatment. Prenatal occurred without complications and the childbirth, despite the risks of prematurity, was normal, with 32 weeks and rupture of only one amniotic sac. The other, was ruptured artificially. The time interval between twins delivery was 16 minutes, and the second twin was bigger than the first. Historically, a twin pregnancy in association of Lupus is very worrying and requires intensive care. However, according to the narratives, the symptoms of the disease have simply disappeared and the joy of being a mother, prevail over the disease. We believe that prematurity occurred due to the two risk factors involved in the conception: gemelarity and Lupus. Conclusion: The Binomial lupus-gestation can succeed independently of the type of pregnancy (multiple or single). However, many variables should be considered: the activity of Lupus and symptomatology in conception, the type of prenatal care and the emotional state of the pregnant woman.

Cardiolipin Structure and Oxidation Are Affected by Ca2+ at the Interface of Lipid Bilayers.

Ca2+-overload contributes to the oxidation of mitochondrial membrane lipids and associated events such as the permeability transition pore (MPTP) opening. Numerous experimental studies about the Ca2+/cardiolipin (CL) interaction are reported in the literature, but there are few studies in conjunction with theoretical approaches based on ab initio calculations. In the present study, the lipid fraction of the inner mitochondrial membrane was modeled as POPC/CL large unilamellar vesicles (LUVs). POPC/CL and, comparatively, POPC, and CL LUVs were challenged by singlet molecular oxygen using the anionic porphyrin TPPS4 as a photosensitizer and by free radicals produced by Fe2+-citrate. Calcium ion favored both types of lipid oxidation in a lipid composition-dependent manner. In membranes containing predominantly or exclusively POPC, Ca2+ increased the oxidation at later reaction times while the oxidation of CL membranes was exacerbated at the early times of reaction. Considering that Ca2+ interaction affects the lipid structure and packing, density functional theory (DFT) calculations were applied to the Ca2+ association with totally and partially protonated and deprotonated CL, in the presence of water. The interaction of totally and partially protonated CL head groups with Ca2+ decreased the intramolecular P-P distance and increased the hydrophobic volume of the acyl chains. Consistently with the theoretically predicted effect of Ca2+ on CL, in the absence of pro-oxidants, giant unilamellar vesicles (GUVs) challenged by Ca2+ formed buds and many internal vesicles. Therefore, Ca2+ induces changes in CL packing and increases the susceptibility of CL to the oxidation promoted by free radicals and excited species.

Effects of Gold Salt Speciation and Structure of Human and Bovine Serum Albumins on the Synthesis and Stability of Gold Nanostructures.

The present study aimed to investigate the influence of albumin structure and gold speciation on the synthesis of gold nanoparticles (GNPs). The strategy of synthesis was the addition of HAuCl4 solutions at different pH values (3-12) to solutions of human and bovine serum albumins (HSA and BSA) at the same corresponding pH values. Different pH values influence the GNP synthesis due to gold speciation. Besides the inherent effect of pH on the native structure of albumins, the use N-ethylmaleimide (NEM)-treated and heat-denaturated forms of HSA and BSA provided additional insights about the influence of protein structure, net charge, and thiol group approachability on the GNP synthesis. NEM treatment, heating, and the extreme values of pH promoted loss of the native albumin structure. The formation of GNPs indicated by the appearance of surface plasmon resonance (SPR) bands became detectable from 15 days of the synthesis processes that were carried out with native, NEM-treated and heat-denaturated forms of HSA and BSA, exclusively at pH 6 and 7. After 2 months of incubation, SPR band was also detected for all synthesis carried out at pH 8.0. The mean values of the hydrodynamic radius (RH) were 24 and 34 nm for GNPs synthesized with native HSA and BSA, respectively. X-ray diffraction (XRD) revealed crystallites of 13 nm. RH, XRD, and zeta potential values were consistent with GNP capping by the albumins. However, the GNPs produced with NEM-treated and heat-denaturated albumins exhibited loss of protein capping by lowering the ionic strength. This result suggests a significant contribution of non-electrostatic interactions of albumins with the GNP surface, in these conditions. The denaturation of proteins exposes hydrophobic groups to the solvent, and these groups could interact with the gold surface. In these conditions, the thiol blockage or oxidation, the latter probably favored upon heating, impaired the formation of a stable capping by thiol coordination with the gold surface. Therefore, the cysteine side chain of albumins is important for the colloidal stabilization of GNPs rather than as the reducing agent for the synthesis. Despite the presence of more reactive gold species at more acidic pH values, i.e., below 6.0, in these conditions the loss of native albumin structure impaired GNP synthesis. Alkaline pH values (9-12) combined the unfavorable conditions of denaturated protein structure with less reactive gold species. Therefore, an optimal condition for the synthesis of GNPs using serum albumins involves more reactive gold salt species combined with a reducing and negatively charged form of the protein, all favored at pH 6-7.

pH-Dependent Synthesis of Anisotropic Gold Nanostructures by Bioinspired Cysteine-Containing Peptides.

In the present study, alkaline peptides AAAXCX (X = lysine or arginine residues) were designed based on the conserved motif of the enzyme thioredoxin and used for the synthesis of gold nanoparticles (GNPs) in the pH range of 2-11. These peptides were compared with free cysteine, the counterpart acidic peptides AAAECE and γ-ECG (glutathione), and the neutral peptide AAAACA. The objective was to investigate the effect of the amino acids neighboring a cysteine residue on the pH-dependent synthesis of gold nanocrystals. Kohn-Sham density functional theory (KS-DFT) calculations indicated an increase in the reducing capacity of AAAKCK favored by the successive deprotonation of their ionizable groups at increasing pH values. Experimentally, it was observed that gold speciation and the peptide structure also have a strong influence on the synthesis and stabilization of GNPs. AAAKCK produced GNPs at room temperature, in the whole investigated pH range. By contrast, alkaline pH was the best condition for the synthesis of GNP assisted by the AAARCR peptide. The acidic peptides produced GNPs only in the presence of polyethylene glycol, and the synthesis using AAAECE and γ-ECG also required heating. The ionization state of AAAKCK had a strong influence on the preferential growth of the GNPs. Therefore, pH had a remarkable effect on the synthesis, kinetics, size, shape, and polydispersity of GNPs produced using AAAKCK. The AAAKCK peptide produced anisotropic decahedral and platelike nanocrystals at acidic pH values and spherical GNPs at alkaline pH values. Both alkaline peptides were also efficient capping agents for GNPs, but they produced a significant difference in the zeta potential, probably because of different orientations on the gold surface.

Intermediate Tyrosyl Radical and Amyloid Structure in Peroxide-Activated Cytoglobin.

We characterized the peroxidase mechanism of recombinant rat brain cytoglobin (Cygb) challenged by hydrogen peroxide, tert-butylhydroperoxide and by cumene hydroperoxide. The peroxidase mechanism of Cygb is similar to that of myoglobin. Cygb challenged by hydrogen peroxide is converted to a Fe4+ oxoferryl π cation, which is converted to Fe4+ oxoferryl and tyrosyl radical detected by direct continuous wave-electron paramagnetic resonance and by 3,5-dibromo-4-nitrosobenzene sulfonate spin trapping. When organic peroxides are used as substrates at initial reaction times, and given an excess of peroxide present, the EPR signals of the corresponding peroxyl radicals precede those of the direct tyrosyl radical. This result is consistent with the use of peroxide as a reducing agent for the recycling of Cygb high-valence species. Furthermore, we found that the Cygb oxidation by peroxides leads to the formation of amyloid fibrils. This result suggests that Cygb possibly participates in the development of degenerative diseases; our findings also support the possible biological role of Cygb related to peroxidase activity.

Carga imediata em implantes unitários nos maxilares

A possibilidade de reabilitação oral com implantes dentários mostrou um avanço significativo nos últimos quarenta anos. O protocolo inicial da osseointegração, que ocorre em dois estágios cirúrgicos como proposto por Branemark, tem alcançado sucesso clínico comprovado. A evolução das técnicas cirúrgicas, o aperfeiçoamento dos métodos de diagnóstico, a melhoria na qualidade do implante em desenho e superfície, bem como o melhor conhecimento da biologia dos tecidos envolvidos vem dando suporte a estudos com protocolo de único estágio cirúrgico e a colocação de próteses sobre implantes recém-instalados...

Conceitos e ações de educação ambiental em grupos de terceira idade: perspectivas para desenvolvimento de programas educativos / Concepts and action of ambient education in groups of third age: perspectives for development of educative programs

Neste estudo investigou-se conceitos, percepções e possíveis ações da educação ambiental na terceira idade e nele estão propostas novas estratégias e materiais educativos, que estimulem a participação ativa dos idosos na valorização e preservação do amiente. Buscou-se diferentes referenciais teóricos-metodológicos que conseguissem se aproximar do objeto, multifacetado, educação ambiental e envelhecimento, priorizando a perspectiva qualitativa. A teoria das representações sociais foi o referencial que orientou o trabalho, na direção de um estudo comparativo entre 3 grupos de terceira idade da região metropolitana de Belo Horizonte, MG. Os sujeitos da pesquisa eram idosos compreendidos na faixa etária de 60-91 anos. Foram entrevistados 30 idosos e as entrevistas foram analisadas na perspectiva da análise do conteúdo. As representações mostraram que os idosos têm percepção da degradação ambiental e apostam na cooperação, solidariedade e educação, em sentido amplo. Em contextos singulares, apostam na sua participação como atores sociais para o despertar de uma consciência ecológica. Quanto à produção de...Nossos resultados...ambiente. Após as entrevistas, realizamos 4 oficinas sócio-educativas com o objetivo de aprofundar o nível de reflexão e conscientização dos idosos sobre a questão ambiental, bem como conhecer as suas crenças, idéias e sentimentos, visando à sua reflexão, adaptação e/ou mudança, e estimulando novas aprendizagens, para o enfrentamento desta problemática. Na oficina, exploramos os temas: reciclagem, preciclagem, coleta seletiva, seleção do lixo, os tipos de lixo quanto à sua composição e às formas de destinação final. Logo após as técnicas de grupo, discutimos os pontos relevantes de cada atividade e refletimos sobre alguns aspectos importantes para a educação ambiental e a preservação do ambiente. As técnicas lúdicas e as oficinas de trabalhos manuais foram recursos educativos que visaram aumentar a compreensão da informação bem como a...