Lipid metabolism response to a single, prolonged bout of endurance exercise in healthy young men

To discover the alterations in lipid metabolism linked to postexercise hypotriglyceridemia, we measured lipid kinetics, lipoprotein subclass distribution and lipid transfer enzymes in seven healthy, lean, young men the day after 2 h of cycling and rest. Compared with rest, exercise increased fatty acid rate of appearance and whole body fatty acid oxidation by approximately 65 and 40%, respectively (P < 0.05); exercise had no effect on VLDL-triglyceride (TG) secretion rate, increased VLDL-TG plasma clearance rate by 40 +/- 8%, and reduced VLDL-TG mean residence time by approximately 40 min and VLDL-apolipoprotein B-100 (apoB-100) secretion rate by 24 +/- 8% (all P < 0.05). Exercise also reduced the number of VLDL but almost doubled the number of IDL particles in plasma (P < 0.05). Muscle lipoprotein lipase content was not different after exercise and rest, but plasma lipoprotein lipase concentration increased by approximately 20% after exercise (P < 0.05). Plasma hepatic lipase and lecithin:cholesterol acyltransferase concentrations were not affected by exercise, whereas cholesterol ester transfer protein concentration was approximately 10% lower after exercise than after rest (P = 0.052). We conclude that 1) greater fatty acid availability after exercise does not stimulate VLDL-TG secretion, probably because of the increase in fatty acid oxidation and possibly also fatty acid use for restoration of tissue TG stores; 2) reduced secretion of VLDL-apoB-100 lowers plasma VLDL particle concentration; and 3) increased VLDL-TG plasma clearance maintains low plasma TG concentration but is not accompanied by similar increases in subsequent steps of the delipidation cascade. Acutely, therefore, the cardioprotective lowering of plasma TG and VLDL concentrations by exercise is counteracted by a proatherogenic increase in IDL concentration.     

Dynamic responses of the glutathione system to acute oxidative stress in dystrophic mouse (mdx) muscles

The precise mechanisms underlying skeletal muscle damage in Duchenne muscular dystrophy (DMD) remain ill-defined. Functional ischemia during muscle activation, with subsequent reperfusion during rest, has been documented. Therefore, one possibility is the presence of increased oxidative stress. We applied a model of acute hindlimb ischemia/reperfusion (I/R) in mdx mice (genetic homolog of DMD) to evaluate dynamic in vivo responses of dystrophic muscles to this form of oxidative stress. Before the application of I/R, mdx muscles showed: 1) decreased levels of total glutathione (GSH) with an increased oxidized (GSSG)-to-reduced (GSH) glutathione ratio; 2) greater activity of the GSH-metabolizing enzymes glutathione peroxidase (GPx) and glutathione reductase; and 3) lower activity levels of NADP-linked isocitrate dehydrogenase (ICDH) and aconitase, two metabolic enzymes that are sensitive to inactivation by oxidative stress and also implicated in GSH regeneration. Interestingly, nondystrophic muscles subjected to I/R exhibited similar changes in total glutathione, GSSG/GSH, GPx, ICDH, and aconitase. In contrast, all of the above remained stable in mdx muscles subjected to I/R. Taken together, these results suggest that mdx muscles are chronically subjected to increased oxidative stress, leading to adaptive changes that attempt to protect (although only in part) the dystrophic muscles from acute I/R-induced oxidative stress. In addition, mdx muscles show significant impairment of the redox-sensitive metabolic enzymes ICDH and aconitase, which may further contribute to contractile dysfunction in dystrophic muscles.     

Running to stand still

For synapses to form and function, neurotransmitter receptors must be recruited to a location on the postsynaptic cell in direct apposition to presynaptic neurotransmitter release. However, once receptors are inserted into the postsynaptic membrane, they are not fixed in place but are continually exchanged between synaptic and extrasynaptic regions, and they cycle between the surface and intracellular compartments. This article highlights and compares the current knowledge about the dynamics of acetylcholine receptors at the vertebrate peripheral neuromuscular junction and AMPA, N-methyl-D-aspartate, and gamma-aminobutyric acid receptors in central synapses.     

The crystal structure of Aq_328 from the hyperthermophilic bacteria Aquifex aeolicus shows an ancestral histone fold

The structure of Aq_328, an uncharacterized protein from hyperthermophilic bacteria Aquifex aeolicus, has been determined to 1.9 A by using multi-wavelength anomalous diffraction (MAD) phasing. Although the amino acid sequence analysis shows that Aq_328 has no significant similarity to proteins with a known structure and function, the structure comparison by using the Dali server reveals that it: (1) assumes a histone-like fold, and (2) is similar to an ancestral nuclear histone protein (PDB code 1F1E) with z-score 8.1 and RMSD 3.6 A over 124 residues. A sedimentation equilibrium experiment indicates that Aq_328 is a monomer in solution, with an average sedimentation coefficient of 2.4 and an apparent molecular weight of about 20 kDa. The overall architecture of Aq_328 consists of two noncanonical histone domains in tandem repeat within a single chain, and is similar to eukaryotic heterodimer (H2A/H2B and H3/H4) and an archaeal histone heterodimer (HMfA/HMfB). The sequence comparisons between the two histone domains of Aq_328 and six eukaryotic/archaeal histones demonstrate that most of the conserved residues that underlie the Aq_328 architecture are used to build and stabilize the two cross-shaped antiparallel histone domains. The high percentage of salt bridges in the structure could be a factor in the protein's thermostability. The structural similarities to other histone-like proteins, molecular properties, and potential function of Aq_328 are discussed in this paper.     

One-step screen-printed electrode modified in its bulk with HRP based on direct electron transfer for hydrogen peroxide detection in flow injection mode

The preparation and performances of screen-printed carbon electrodes modified in their bulk with HRP (HRP-SPCE) is reported. The resulting modified HRP-SPCE was prepared in a one-step procedure, and then was optimised as an amperometric biosensor operating at [0-100] mV versus Ag/AgCl in flow injection mode for hydrogen peroxide. The amperometric response was due to direct electron transfer (DET) between HRP and SPCE surface. Factors such as chemical modification of the enzyme or the nature and rate of the binder were investigated regards to their influence on the sensitivity, linear range and operational stability. The best performing HRP-SPCE in terms of sensitivity and operational stability was obtained when graphite powder was modified with HRP previously oxidised by periodate ion (IO(4)(-)).     

New photoantimicrobial films composed of porphyrinated lipophilic cellulose esters

Porphyrinated cellulose laurate esters have been prepared in homogeneous DMA/LiCl medium by "one-pot, two-step" reactions starting from cellulose, protoporphyrin IX, and lauric acid and using a TsCl/Pyridine system. The plastic films obtained after casting were shown to display photobactericidal activity against Gram positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. This new photobactericidal polymer has potential for industrial, medical, or household applications.     

Differential Expression of Small Heat Shock Protein 27 (Hsp27) in Ataxia telangiectasia Brains

Ataxia telangiectasia (A-T) is a progressive neurodegenerative disorder caused by disruption of the gene, ataxia telangiectasia mutated (ATM). Present study was aimed at identifying proteins that are present in abnormal levels in A-T brain that may identify alternative targets for therapeutic interventions. Proteomic and Western blot analysis have shown massive expression of the small heat shock protein 27 (Hsp27) in frontal cortices of A-T brains compared to negligible levels in controls. The expression of other stress proteins, Hsp70, αB-crystallin, and prohibitin remained unchanged in the A-T and control brains. Significant decreases in reactive oxygen species, protein carbonyl groups and lipid peroxidation products were observed in the A-T brains. There is no evidence of caspase 3 activation or DAXX mediated apoptosis. We propose that neurons in the frontal lobe are protected by the expression of Hsp27, which scavenges the oxidative stress molecules formed consequent to the primary loss of ATM function.     

Anthropoid versus strepsirhine status of the African Eocene primates Algeripithecus and Azibius: craniodental evidence

Recent fossil discoveries have demonstrated that Africa and Asia were epicentres for the origin and/or early diversification of the major living primate lineages, including both anthropoids (monkeys, apes and humans) and crown strepsirhine primates (lemurs, lorises and galagos). Competing hypotheses favouring either an African or Asian origin for anthropoids rank among the most hotly contested issues in paleoprimatology. The Afrocentric model for anthropoid origins rests heavily on the >45 Myr old fossil Algeripithecus minutus from Algeria, which is widely acknowledged to be one of the oldest known anthropoids. However, the phylogenetic position of Algeripithecus with respect to other primates has been tenuous because of the highly fragmentary fossils that have documented this primate until now. Recently recovered and more nearly complete fossils of Algeripithecus and contemporaneous relatives reveal that they are not anthropoids. New data support the idea that Algeripithecus and its sister genus Azibius are the earliest offshoots of an Afro–Arabian strepsirhine clade that embraces extant toothcombed primates and their fossil relatives. Azibius exhibits anatomical evidence for nocturnality. Algeripithecus has a long, thin and forwardly inclined lower canine alveolus, a feature that is entirely compatible with the long and procumbent lower canine included in the toothcomb of crown strepsirhines. These results strengthen an ancient African origin for crown strepsirhines and, in turn, strongly challenge the role of Africa as the ancestral homeland for anthropoids.