Gelled Double-Layered Emulsions for Protection of Flaxseed Oil

Multilayer systems may present different functional properties according to the number of layers deposited, the type of biopolymers, the sequence of biopolymer layers, and the solution properties used during deposition. In this study, gelatin-stabilized emulsions were coated with alginate in order to produce double-layered emulsions. Concentrations of both primary emulsion and alginate in the outer layer were evaluated by a stability map. Results indicated the occurrence of depletion flocculation in emulsions with lower gelatin concentration due to excess of alginate. Stable emulsions were atomized in a calcium chloride solution for producing microgels, which resulted in semi-rounded monomodal particles. Emulsification process promoted a reduction in the content of the secondary oxidation products of flaxseed oil as compared to non-emulsified oil, while the gelation process was responsible for a considerable improvement on oxidative stability with significant reduction on both primary and secondary oxidation products during storage. These lipid-based microgels could be potentially used as delivery systems with improved oxidative stability.     

Degradation of Hydrocarbons by Members of the Genus Candida III. Oxidative Intermediates from 1-Hexadecene and 1-Heptadecene by Candida lipolytica

Candida lipolytica (Phaff) was grown in a mineral-salts medium amended with either 1-hexadecene or 1-heptadecene as substrate. Intermediates of the same chain length as the substrate were isolated and identified by various analytical procedures. The following intermediates of 16 and 17 carbon atoms were identified: omega-unsaturated acids, omega-unsaturated primary and secondary alcohols, 1,2-epoxides, 1,2-diols, and 2-hydroxy acids. Based on the chemical structure of these compounds, three oxidative mechanisms are proposed for the degradation of long-chain 1-alkenes by this yeast: (i) methyl-group oxidation, (ii) double-bond oxidation, and (iii) subterminal oxidation.     

Differential acquisition of antigenic peptides by Hsp70 and Hsc70 under oxidative conditions

Hsp70 and Hsc70 are two chaperones of high homology expressed under contrasting situations. Hsc70 is constitutively expressed and poorly stress-inducible, whereas Hsp70 is unabundant in normal physiological situations and strongly induced under oxidative stress. In the present study we show that the chaperoning activity of purified Hsp70 and Hsc70 is minimal under reducing conditions and increases in environments that mimic oxidative stress. Association with peptides is more pronounced for Hsp70 than for Hsc70 in every condition tested and is accompanied with a gradual change in secondary structure during oxidation. The binding of peptides to Hsp70 and Hsc70 under oxidative conditions is not reversible by treatment with a reducing agent, confirming that other chaperone-associated factors are required for substrate release. These findings support the idea that formation of HSP70-peptide complexes and possibly their immunogenicity is enhanced in conditions of stress.     

Interaction of seasonal and ovarian factors in the regulation of LH and FSH secretion in the mare.

A working hypothesis for the regulation of LH secretion in the mare is postulated which involves the following two components: (1) a primary central nervous system (CNS)-pituitary component which is responsible for a basal circannual LH rhythm, entrained to an environmental 'Zeitgeber' (most probably photoperiod) and independent of ovarian influences, and (2) a secondary ovarian (steroidal) component which modifies the primary rhythm during the ovulatory season. This hypothesis does not seem to apply in its entirety to FSH secretion; the CNS-pituitary component is demonstrable within the first year after ovariectomy in mares and then seems to disappear, and the ovarian component probably involves factors other than steroids on the basis of present evidence.     

Intraphagosomal Measurement of the Magnitude and Duration of the Oxidative Burst

Generation of an oxidative burst within the phagosomes of neutrophils, dendritic cells and macrophages is an essential component of the innate immune system. To examine the kinetics of the oxidative burst in the macrophage phagosome, we developed two new assays using beads coated with oxidation-sensitive fluorochromes. These assays permitted quantification and temporal resolution of the oxidative burst within the phagosome. The macrophage phagosomal oxidative burst is short lived, with oxidation of bead-associated substrates reaching maximal activity within 30 min following phagocytosis. Additionally, the extent and rate of macrophage phagosomal substrate oxidation were subject to immunomodulation by activation with lipopolysaccharide and/or interferon-γ.     

Study of somatotype in Italian children aged 6 to 10 years

The aim of the present research was to study the variations of somatotype, calculated by the Heath-Carter anthropometric technique, during growth in a sample of children (416 males and 402 females), aged 6 and 10 years, attending primary and secondary schools of L'Aquila and its province (Abruzzo, Italy). The sample was subdivided into “urban” and “non-urban” groups, on the basis of the residence of the children, to examine possible differences in growth related to the different environments. This study give an account of the somatotype components between urban and non urban childreen between the age 6 and 10 years. A tendency toward an increase of endomorphy (adipose component) with age was noticed in both sexes. In females, ectomorphy (component of physical linearity) tended to increase and mesomorphy (muscular-skeletal component) showed a slight decrease during growth, while males exhibited a discontinuous trend. The differences between urban and non-urban children were not significant, although generally higher values of endomorphy and mesomorphy were found in males and females of the urban sample. The differences between the sexes consisted of higher values of endomorphy and lower values of mesomorphy in females. Ectomorphy was similar in the two sexes.     

The Respiratory Chain of Plant Mitochondria: XVII. Flavoprotein-Cytochrome b(562) Interaction in Antimycin-treated Skunk Cabbage Mitochondria

During the transition from the aerobic steady state with succinate as substrate to anaerobiosis, in suspensions of skunk cabbage (Symplocarpus foetidus) mitochondria treated with antimycin A, cytochrome b(562) becomes reoxidized to the extent of about 20%, synchronously with the reduction of cytochrome c(549). This reoxidation occurs in both the absence and presence of m-chlorobenzhydroxamic acid, a specific inhibitor for the alternate terminal oxidase of plant mitochondria. A flavoprotein component, amounting to 13% to 15% of the total nonfluorescent mitochondrial flavoprotein, undergoes reduction synchronously with the oxidation of cytochrome b(562) during the aerobic to anaerobic transition with succinate as substrate in the presence of both antimycin A and m-chlorobenzhydroxamic acid. This flavoprotein component remains reduced in the presence of cyanide. The half-time for reduction of the flavoprotein component and cytochrome c(549) and for oxidation of cytochrome b(562) during the aerobic to anaerobic transition with succinate as substrate in the presence of both antimycin A and m-chlorobenzhydroxamic acid is 2 seconds. The half-times for oxidation of cytochrome c(549) and the flavoprotein component are 2.1 and 170 milliseconds, respectively, during the anaerobic to aerobic transition induced by addition of 14 mum O(2) to the mitochondrial suspensions. The half-time for reduction of cytochrome b(562) under these conditions is 150 milliseconds, synchronous with the flavoprotein component. The synchrony of the flavoprotein oxidation and of the cytochrome b(562) reduction at a rate much slower than that of cytochrome c(549) oxidation implies that, in antimycin-treated plant mitochondria, the state of the cytochrome b(562)/antimycin complex is regulated by the redox state of this flavoprotein component, rather than by cytochrome c(549). It is tentatively suggested that these two components are not part of the main sequence of the respiratory chain, but may be part of a multienzyme complex active in the hydroxylation reactions required for ubiquinone biosynthesis in the inner mitochondrial membrane.     

Fluorescence induction studies in isolated chloroplasts III. On the electron-transfer equilibria in the pool of electron acceptors of Photosystem II

The oxidation states of the primary and secondary electron acceptors of Photosystem II in isolated chloroplasts were measured simultaneously during their oxidation and reduction. The fluorescence yield and its variation were used as indicators for the oxidation states. An equilibrium treatment gives different contradicting results for different conditions: a low equilibrium constant (K ≈ 1) for the reaction between the (reduced) primary carrier to (oxidized) secondary carriers when the system is photoreduced, and a high equilibrium constant (K > 10, sometimes K > 100) when the system is oxidized in the dark. This discrepancy is discussed in terms of two alternatives: (a) influence of the light, by secondary interactions, on reaction parameters; (b) possibility of two photoreactions in Photosystem II.     

Secondary substrate utilization of methylene chloride by an isolated strain of Pseudomonas sp

Secondary substrate utilization of methylene chloride was analyzed by using Pseudomonas sp. strain LP. Both batch and continuously fed reactors demonstrated that this strain was capable of simultaneously consuming two substrates at different concentrations: the primary substrate at the higher concentration (milligrams per liter) and the secondary substrate at the lower concentration (micrograms per liter). The rate of methylene chloride utilization at trace concentrations was greater in the presence of the primary substrate, acetate, than without it. However, when the substrate roles were changed, the acetate secondary substrate utilization rate was less when methylene chloride was present. Thus, substrate interactions are important in the kinetics of secondary substrate utilization. Pseudomonas sp. strain LP showed a preference toward degrading methylene chloride over acetate, whether it was the primary or secondary substrate, providing it was below an inhibitory concentration of ca. 10 mg/liter.     

Inhibition of erythrocyte Ca2+-ATPase by activated oxygen through thiol- and lipid-dependent mechanisms

We have studied erythrocyte Ca2+-ATPase as a model target for elucidating effects of activated oxygen on the erythrocyte membrane. Either intracellular or extracellular generation of activated oxygen causes parallel decrements in Ca2+-ATPase activity and cytoplasmic GSH, oxidation of membrane protein thiols, and lipid peroxidation. Subsequent incubation with either dithiothreitol or glucose allows only partial recovery of Ca2+-ATPase, indicating both reversible and irreversible components which are modeled herein using diamide and t-butyl hydroperoxide. The reversible component reflects thiol oxidation, and its recovery depends upon GSH restoration. The irreversible component is largely due to lipid peroxidation, which appears to act through mechanisms involving neither malondialdehyde nor secondary thiol oxidation. However, some portion of the irreversible component could also reflect oxidation of thiols which are inaccessible for reduction by GSH, since we demonstrate existence of different classes of thiols relevant to Ca2+-ATPase activity. Activated oxygen has an exaggerated effect on Ca2+-ATPase of GSH-depleted cells. Sickle erythrocytes treated with dithiothreitol show a heterogeneous response of Ca2+-ATPase activity. These findings are potentially relevant to oxidant-induced hemolysis. They also may be pertinent to oxidative alteration of functional or structural membrane components in general, since many components share with Ca2+-ATPase both free thiols and close proximity to unsaturated lipid.     

Secondary substrate utilization of methylene chloride by an isolated strain of Pseudomonas sp.

Secondary substrate utilization of methylene chloride was analyzed by using Pseudomonas sp. strain LP. Both batch and continuously fed reactors demonstrated that this strain was capable of simultaneously consuming two substrates at different concentrations: the primary substrate at the higher concentration (milligrams per liter) and the secondary substrate at the lower concentration (micrograms per liter). The rate of methylene chloride utilization at trace concentrations was greater in the presence of the primary substrate, acetate, than without it. However, when the substrate roles were changed, the acetate secondary substrate utilization rate was less when methylene chloride was present. Thus, substrate interactions are important in the kinetics of secondary substrate utilization. Pseudomonas sp. strain LP showed a preference toward degrading methylene chloride over acetate, whether it was the primary or secondary substrate, providing it was below an inhibitory concentration of ca. 10 mg/liter.     

Cytochrome P-450 model reactions: efficient and highly selective oxidation of alcohols with tetrabutylammonium peroxymonosulfate catalyzed by Mn-porphyrins

A novel biomimetic method for rapid oxidation of a wide range of benzylic, allylic, aliphatic, primary and secondary alcohols to the related aldehydes and ketones using Bu(4)NHSO(5) catalyzed by Mn(TPP)OAc/pyridine system with high to excellent yields and excellent selectivity has been developed. The high turnover rates obtained in this catalytic system represent a high efficiency and also relative stability of Mn-porphyrin catalyst towards oxidative degradation. The presence of an electron-withdrawing group on the phenyl ring of both benzyl alcohol and porphyrin ligand increases the reactivity of substrate as well as catalytic activity of Mn-porphyrin catalyst in the oxidation reaction.     

Solid-state 13C nuclear magnetic resonance spectroscopy of simultaneously metabolized acetate and phenol in a soil Pseudomonas sp.

We investigated concentration-dependent primary and secondary substrate relationships in the simultaneous metabolism of the ubiquitous pollutant phenol and the naturally occurring substrate acetate by a Pseudomonas sp. soil isolate capable of utilizing either substance as a sole source of carbon and energy. In addition to conventional analytical techniques, solid-state 13C nuclear magnetic resonance spectroscopy was used to follow the cellular distribution of [1-13C]acetate in the presence of unlabeled phenol. With 5 mM acetate as the primary substrate, Pseudomonas sp. 9S8D2 removed 1 mM phenol (secondary substrate) at a rate of 2 nmol/mg of total cell protein. Although extensive acetate metabolism was indicated by a significant redistribution of the carboxyl label, this redistribution was not affected by the presence of phenol as a secondary substrate. When the primary and secondary substrate roles were reversed, however, the presence of 1 mM phenol altered the metabolism of 0.1 mM acetate, as evidenced by both the two- to fourfold increases in carboxyl label that appeared in terminal methyl and acyl chain methylene carbon resonances and the decrease in label that occurred in the carbohydrate spectral region. These results suggest that, when phenol is present as the primary substrate, acetate is preferentially shuttled into fatty acyl chain synthesis, whereas phenol carbon is funnelled into the tricarboxylic acid cycle. Thus, simultaneous use of a xenobiotic compound and a natural substrate apparently does occur, and the relative concentrations of the two substrates do influence the rate and manner in which the compounds are utilized.(ABSTRACT TRUNCATED AT 250 WORDS)     

Solid-state 13C nuclear magnetic resonance spectroscopy of simultaneously metabolized acetate and phenol in a soil Pseudomonas sp

We investigated concentration-dependent primary and secondary substrate relationships in the simultaneous metabolism of the ubiquitous pollutant phenol and the naturally occurring substrate acetate by a Pseudomonas sp. soil isolate capable of utilizing either substance as a sole source of carbon and energy. In addition to conventional analytical techniques, solid-state 13C nuclear magnetic resonance spectroscopy was used to follow the cellular distribution of [1-13C]acetate in the presence of unlabeled phenol. With 5 mM acetate as the primary substrate, Pseudomonas sp. 9S8D2 removed 1 mM phenol (secondary substrate) at a rate of 2 nmol/mg of total cell protein. Although extensive acetate metabolism was indicated by a significant redistribution of the carboxyl label, this redistribution was not affected by the presence of phenol as a secondary substrate. When the primary and secondary substrate roles were reversed, however, the presence of 1 mM phenol altered the metabolism of 0.1 mM acetate, as evidenced by both the two- to fourfold increases in carboxyl label that appeared in terminal methyl and acyl chain methylene carbon resonances and the decrease in label that occurred in the carbohydrate spectral region. These results suggest that, when phenol is present as the primary substrate, acetate is preferentially shuttled into fatty acyl chain synthesis, whereas phenol carbon is funnelled into the tricarboxylic acid cycle. Thus, simultaneous use of a xenobiotic compound and a natural substrate apparently does occur, and the relative concentrations of the two substrates do influence the rate and manner in which the compounds are utilized.(ABSTRACT TRUNCATED AT 250 WORDS)     

Astrocytic energetics during excitatory neurotransmission: What are contributions of glutamate oxidation and glycolysis?

Astrocytic energetics of excitatory neurotransmission is controversial due to discrepant findings in different experimental systems in vitro and in vivo. The energy requirements of glutamate uptake are believed by some researchers to be satisfied by glycolysis coupled with shuttling of lactate to neurons for oxidation. However, astrocytes increase glycogenolysis and oxidative metabolism during sensory stimulation in vivo, indicating that other sources of energy are used by astrocytes during brain activation. Furthermore, glutamate uptake into cultured astrocytes stimulates glutamate oxidation and oxygen consumption, and glutamate maintains respiration as well as glucose. The neurotransmitter pool of glutamate is associated with the faster component of total glutamate turnover in vivo, and use of neurotransmitter glutamate to fuel its own uptake by oxidation-competent perisynaptic processes has two advantages, substrate is supplied concomitant with demand, and glutamate spares glucose for use by neurons and astrocytes. Some, but not all, perisynaptic processes of astrocytes in adult rodent brain contain mitochondria, and oxidation of only a small fraction of the neurotransmitter glutamate taken up into these structures would be sufficient to supply the ATP required for sodium extrusion and conversion of glutamate to glutamine. Glycolysis would, however, be required in perisynaptic processes lacking oxidative capacity. Three lines of evidence indicate that critical cornerstones of the astrocyte-to-neuron lactate shuttle model are not established and normal brain does not need lactate as supplemental fuel: (i) rapid onset of hemodynamic responses to activation delivers oxygen and glucose in excess of demand, (ii) total glucose utilization greatly exceeds glucose oxidation in awake rodents during activation, indicating that the lactate generated is released, not locally oxidized, and (iii) glutamate-induced glycolysis is not a robust phenotype of all astrocyte cultures. Various metabolic pathways, including glutamate oxidation and glycolysis with lactate release, contribute to cellular energy demands of excitatory neurotransmission.     

Oxidative signaling pathway for externalization of plasma membrane phosphatidylserine during apoptosis

Active maintenance of membrane phospholipid asymmetry is universal in normal cell membranes and its disruption with subsequent externalization of phosphatidylserine is a hallmark of apoptosis. Externalized phosphatidylserine appears to serve as an important signal for targeting recognition and elimination of apoptotic cells by macrophages, however, the molecular mechanisms responsible for phosphatidylserine translocation during apoptosis remain unresolved. Studies have focused on the function of aminophospholipid translocase and phospholipid scramblase as mediators of this process. Here we present evidence that unique oxidative events, represented by selective oxidation of phosphatidylserine, occur during apoptosis that could promote phosphatidylserine externalization. We speculate that selective phosphatidylserine oxidation could affect phosphatidylserine recognition by aminophospholipid translocase and/or directly result in enzyme inhibition. The potential interactions between the anionic phospholipid phosphatidylserine and the redox-active cationic protein effector of apoptosis, cytochrome c, are presented as a potential mechanism to account for selective oxidation of phosphatidylserine during apoptosis. Thus, cytochrome c-mediated phosphatidylserine oxidation may represent an important component of the apoptotic pathway.     

桂北喀斯特峰丛洼地植物群落特征及其与土壤的耦合关系

基于喀斯特峰丛洼地草丛、灌丛、次生林、原生林4个生态系统24个样地(20 m × 20 m)的系统取样调查, 研究了喀斯特峰丛洼地不同生态系统群落的结构组成与生物多样性特征, 选取代表植物群落和土壤性质的35个指标, 对不同生态系统及整个喀斯特脆弱生态系统植物群落与土壤主要养分、土壤矿质养分和土壤微生物间的相互关系进行了主成分分析与典范相关分析。结果表明: 沿草丛、灌丛、次生林、原生林的顺向演替发展, 重要值(importance value, IV)>10.00的科、属、种及物种多样性最大值出现在次生林, 群落结构最佳值出现在顶级群落原生林; 喀斯特峰丛洼地景观异质性高, 各生态系统影响因子不同, 土壤微生物在喀斯特脆弱生态系统处于主导地位, 其次为灌丛; 不同集团因子的典范相关分析表明, 植物多样性指标与土壤氮素、Al₂O₃、Fe₂O₃、土壤微生物生物量碳(C_mic)、真菌和细菌关系密切。因此, 在喀斯特脆弱生态系统恢复与重建过程中, 应针对不同生态系统制定相应的培育管理措施。     

Routes of formation and toxic consequences of lipid oxidation products in foods.

Lipid oxidation in foods is initiated by free radical and/or singlet oxygen mechanisms which generate a series of autocatalytic free radical reactions. These autoxidation reactions lead to the breakdown of lipid and to the formation of a wide array of oxidation products. The nature and proportion of these products can vary widely between foods and depend on the composition of the food as well as numerous environmental factors. The toxicological significance of lipid oxidation in foods is complicated by interactions of secondary lipid oxidation products with other food components. These interactions could either form complexes that limit the bioavailability of lipid breakdown products or can lead to the formation of toxic products derived from non-lipid sources. A lack of gross pathological consequences has generally been observed in animals fed oxidized fats. On the other hand, secondary products of lipid autoxidation can be absorbed and may cause an increase in oxidative stress and deleterious changes in lipoprotein and platelet metabolism. The presence of reactive lipid oxidation products in foods needs more systematic research in terms of complexities of food component interactions and the metabolic processing of these compounds.     

Inhibition of palmityl carnitine oxidation in rat liver mitochondria by tert-butyl hydroperoxide

Mitochondria as an energy generating cell device are very sensitive to oxidative damage. Our previous findings obtained in hepatocytes demonstrated that Complex I of the respiratory chain is more sensitive to oxidative damage than other respiratory chain complexes. We present additional data on isolated mitochondria showing that palmityl carnitine oxidation is strongly depressed at a low (200 microM) tert-butyl hydroperoxide (tBHP) concentration, while oxidation of the flavoprotein-dependent substrate - succinate is not affected and neither is ATP synthesis inhibited by tBHP. In the presence of tBHP, the respiratory control index for palmityl carnitine oxidation is strongly depressed, but when succinate is oxidized the respiratory control index remains unaffected. Our findings thus indicate that flavoprotein-dependent substrates could be an important nutritional factor for the regeneration process in the necrotic liver damaged by oxidative stress.     

Bioconcentration mechanism of selenium by a coccolithophorid, Emiliania huxleyi

We investigated the uptake and bioconcentration of the essential element selenium by a coccolithophorid, Emiliania huxleyi, using [75Se]selenite. The time course of 75Se uptake showed a biphasic pattern, namely a primary phase and a subsequent secondary phase. The primary and secondary phases are due to a rapid selenite uptake process that attained a stationary level within 2 min and a slow Se-accumulation process that continued at a constant rate for 4 h or longer, respectively. Kinetic analysis revealed that the selenite uptake process consists of two components, one saturable and one linearly related to substrate concentration. The Km of the saturable component was 29.8 nM selenite; the uptake activity of this component was suppressed by inhibitors of ATP biogenesis, suggesting that selenite uptake is driven by a high-affinity, active transport system. During a 6-h incubation of cells with [75Se]selenite, 70% of the intracellular 75Se was incorporated into low-molecular-mass compounds (LMCs), and 17% was incorporated into proteins, but [75Se]selenite was barely detectable. A pulse-chase experiment demonstrated that the 75Se that had accumulated in LMCs was transferred into proteins. When the syntheses of amino acids and proteins were each separately inhibited, 75Se incorporation into LMCs and proteins was decreased. These results suggest that E. huxleyi rapidly absorbs selenite, filling a small intracellular pool. Then, Se-containing LMCs are immediately synthesized from the selenite, creating a pool of LMCs that are then metabolized to selenoproteins.