Singlet molecular oxygen-quenching activity of carotenoids: relevance to protection of the skin from photoaging

Carotenoids are known to be potent quenchers of singlet molecular oxygen [O2 (1Δg)]. Solar light-induced photooxidative stress causes skin photoaging by accelerating the generation of reactive oxygen species via photodynamic actions in which O2 (1Δg) can be generated by energy transfer from excited sensitizers. Thus, dietary carotenoids seem to participate in the prevention of photooxidative stress by accumulating as antioxidants in the skin. An in vivo study using hairless mice clarified that a O2 (1Δg) oxygenation-specific peroxidation product of cholesterol, cholesterol 5α-hydroperoxide, accumulates in skin lipids due to ultraviolet-A exposure. Matrix metalloproteinase-9, a metalloproteinase family enzyme responsible for the formation of wrinkles and sagging, was enhanced in the skin of ultraviolet-A -irradiated hairless mice. The activation of metalloproteinase-9 and the accumulation of 5α-hydroperoxide, as well as formation of wrinkles and sagging, were lowered in mice fed a β-carotene diet. These results strongly suggest that dietary β-carotene prevents the expression of metalloproteinase-9 (at least in part), by inhibiting the photodynamic action involving the formation of 5α-hydroperoxide in the skin. Intake of β-Carotene therefore appears to be helpful in slowing down ultraviolet-A -induced photoaging in human skin by acting as a O2 (1Δg) quencher

New application of dynamic magnetic resonance imaging for the assessment of deglutitive tongue movement

Background: Deglutitive motion of the tongue may function to maintain tooth position. However, the causation between abnormal patterns of orofacial muscle function and dental malocclusion remains unclear. To clarify the pathogenic mechanism of malocclusion, it is important to determine the relative positional relationship between the tongue tip and incisor edge or the dorsal tongue and palate during deglutition. Here, we assessed the utility of 3-T segmented cine-magnetic resonance (MR) imaging, combined with static MR images for hard tissue visualization, in assessing the relationship between the tongue and the surrounding tissues during deglutitive tongue movement. Methods: Cine-MR images were acquired from three healthy female volunteers during deglutition who had no history of swallowing disorder or other chronic illness, normal alignment and occlusion, and a skeletal class I relationship. Three cine-MR images were taken during deglutition in accordance with an auditory cue for each volunteer. During static imaging, custom-made, contrast-medium-filled clear retainers were positioned in the mouth to allow visualization of the upper and lower incisors and hard palate boundaries. Static images were superimposed onto images of the three stages in deglutitive tongue movement, which were selected from a series of cine-MR images. These superimpositions were assessed five times by tracing cephalometric parameters to examine the reproducibility of the method. Results: Traces varied little across repeated measurements, and all subjects had a similar pattern of dorsal tongue movement. Tongue-to-palate contact increased slightly during the first to second stage of swallowing and abruptly increased during the second to third stage, while the tongue tip position remained constant. Conclusions: Segmented cine-MR imaging combined with static MR images is useful for assessing soft tissue motion during deglutition. This method is particularly useful in dentistry to evaluate the relationship between tongue function and maxillofacial morphology in terms of orthodontic treatment and orofacial myofunctional therapy, and for improving tongue movement during speech therapy

Influência do meio de cultura nas características morfológicas das colônias de algumas bactérias capazes de degradarem a lactose e o glúten / Influence of the culture medium on the morphological characteristics of the colonies of some bacteria capable of degrading lactose and Gluten

Os microrganismos têm um metabolismo bastante diversificado e podem reagir de forma diferente quando colocados em condições diferentes de meios de cultura, temperatura, pH e pressão de oxigênio. Conhecer essas variações pode ser importante para entender como usam os nutrientes dos meios de cultura, principalmente quando se altera a fonte de carbono, de proteínas para carboidratos, e vice e versa. Esse trabalho teve como objetivo, avaliar o crescimento e as modificações das colônias de 20 bactérias capazes de degradar a lactose (carboidratos) e o glúten (proteínas) como forma de melhor entender seus metabolismos e potenciais biotecnológicos. Além disso, foi avaliado o Índice de Degradação do Glúten (IDG) de seis dessas bactérias. A morfologia das colônias das 20 bactérias capazes de degradar a lactose e o glúten nos dois meios de cultura usados pode ser usada para diferenciar uma das outras. Os diâmetros das colônias e do halo de degradação do glúten, bem como o Índice de Degradação do Glúten (IDG) também permitem diferenciar esse grupo de bactérias. Essas diferenças de características podem ser usadas para facilitar futuros estudos com essas bactérias. O meio cuja fonte de carbono é constituída de proteínas (glúten) foi o que mais favoreceu o crescimento das bactérias INPA BLG01, BLG22, BLG28, BLG52. 

Behavior of the thermal diffusivity of native and oxidized human low-density lipoprotein solutions studied by the Z-scan technique

Modifications in low-density lipoprotein (LDL) have emerged as a major pathogenic factor of atherosclerosis, which is the main cause of morbidity and mortality in the western world. Measurements of the heat diffusivity of human LDL solutions in their native and in vitro oxidized states are presented by using the Z-Scan (ZS) technique. Other complementary techniques were used to obtain the physical parameters necessary to interpret the optical results, e. g., pycnometry, refractometry, calorimetry, and spectrophotometry, and to understand the oxidation phase of LDL particles. To determine the sample's thermal diffusivity using the thermal lens model, an iterative one-parameter fitting method is proposed which takes into account several characteristic ZS time-dependent and the position-dependent transmittance measurements. Results show that the thermal diffusivity increases as a function of the LDL oxidation degree, which can be explained by the increase of the hydroperoxides production due to the oxidation process. The oxidation products go from one LDL to another, disseminating the oxidation process and caring the heat across the sample. This phenomenon leads to a quick thermal homogenization of the sample, avoiding the formation of the thermal lens in highly oxidized LDL solutions. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JBO.17.10.105003]National Counsel for Scientific and Technological Development (CNPq)National Counsel for Scientific and Technological Development (CNPq)Sao Paulo Research Foundation (FAPESP)Sao Paulo Research Foundation (FAPESP)National Institute of Science and Technology of Complex Fluid (INCTFCx)National Institute of Science and Technology of Complex Fluid (INCT-FCx)Redoxoma (INCT-Redoxoma)Redoxoma (INCTRedoxoma

Cytochrome c-promoted cardiolipin oxidation generates singlet molecular oxygen

The interaction of cytochrome c (cyt c) with cardiolipin (CL) induces protein conformational changes that favor peroxidase activity. This process has been correlated with CL oxidation and the induction of cell death. Here we report evidence demonstrating the generation of singlet molecular oxygen [O-2((1)Delta(g))] by a cyt c-CL complex in a model membrane containing CL. The formation of singlet oxygen was directly evidenced by luminescence measurements at 1270 nm and by chemical trapping experiments. Singlet oxygen generation required cyt c-CL binding and occurred at pH values higher than 6, consistent with lipid-protein interactions involving fully deprotonated CL species and positively charged residues in the protein. Moreover, singlet oxygen formation was specifically observed for tetralinoleoyl CL species and was not observed with monounsaturated and saturated CL species. Our results show that there are at least two mechanisms leading to singlet oxygen formation: one with fast kinetics involving the generation of singlet oxygen directly from CL hydroperoxide decomposition and the other involving CL oxidation. The contribution of the first mechanism was clearly evidenced by the detection of labeled singlet oxygen [O-18(2)((1)Delta(g))] from liposomes supplemented with 18-oxygen-labeled CL hydroperoxides. However quantitative analysis showed that singlet oxygen yield from CL hydroperoxides was minor (<5%) and that most of the singlet oxygen is formed from the second mechanism. Based on these data and previous findings we propose a mechanism of singlet oxygen generation through reactions involving peroxyl radicals (Russell mechanism) and excited triplet carbonyl intermediates (energy transfer mechanism).FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico (CNPq)CNPq (Conselho Nacional para o Desenvolvimento Cientifico e Tecnologico)CAPES/PROCAD-NF (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior/Programa Nacional de Cooperacao Academica Novas Fronteiras)CAPES/PROCADNF (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior/Programa Nacional de Cooperacao Academica Novas Fronteiras)INCT de Processos Redox em Biomedicina - RedoxomaINCT de Processos Redox em Biomedicina RedoxomaNAPRedoxomaNAP-RedoxomaL'OREAL-UNESCO for Women in ScienceLOREALUNESCO for Women in ScienceJohn Simon Guggenheim Memorial FoundationJohn Simon Memorial Guggenheim Foundatio

Oxidative modification of proteins: from damage to catalysis, signaling, and beyond

Significance: The systematic investigation of oxidative modification of proteins by reactive oxygen species started in 1980. Later, it was shown that reactive nitrogen species could also modify proteins. Some protein oxidative modifications promote loss of protein function, cleavage or aggregation, and some result in proteo-toxicity and cellular homeostasis disruption. Recent Advances: Previously, protein oxidation was associated exclusively to damage. However, not all oxidative modifications are necessarily associated with damage, as with Met and Cys protein residue oxidation. In these cases, redox state changes can alter protein structure, catalytic function, and signaling processes in response to metabolic and/or environmental alterations. This review aims to integrate the present knowledge on redox modifications of proteins with their fate and role in redox signaling and human pathological conditions. Critical Issues: It is hypothesized that protein oxidation participates in the development and progression of many pathological conditions. However, no quantitative data have been correlated with specific oxidized proteins or the progression or severity of pathological conditions. Hence, the comprehension of the mechanisms underlying these modifications, their importance in human pathologies, and the fate of the modified proteins is of clinical relevance. Future Directions: We discuss new tools to cope with protein oxidation and suggest new approaches for integrating knowledge about protein oxidation and redox processes with human pathophysiological conditions