The effect of acute resistance exercise on serum malondialdehyde in resistance-trained and untrained collegiate men

The purposes of this study were to determine whether acute resistance exercise increases serum malondialdehyde (MDA) levels postexercise, and if so, whether resistance exercise training status influences the magnitude of the exercise-induced lipid peroxidation response. Twelve recreationally resistance-trained (RT) and 12 untrained (UT) men who did not have resistance exercise experience in the past year participated in this study. All subjects completed an 8-exercise circuit resistance exercise protocol consisting of 3 sets of 10 repetitions at 10 repetitions maximum for each exercise. Blood samples were obtained pre-exercise, at 5 minutes postexercise, and at 6, 24, and 48 hours postexercise. At pre-exercise, MDA (nmol.ml(-1)) averaged 3.41 +/- 0.25 (RT) and 3.20 +/- 0.25 (UT) and did not differ (p > 0.05) either between groups or over time. Creatine kinase (IU.L(-1)) was significantly (p < 0.05) elevated 5 minutes postexercise (170.6 +/- 25.8), 6 hours postexercise (290.3 +/- 34.4), 24 hours postexercise (365.5 +/- 49.9), and 48 hours postexercise (247.5 +/- 38.5) as compared with pre-exercise (126.4 +/- 20.2) for both groups. There was no difference (p > 0.05) in CK activity between groups. This study indicated that moderate-intensity whole-body resistance exercise had no effect on serum MDA concentration in RT and UT subjects.     

Generation of cloned transgenic pigs rich in omega-3 fatty acids

Meat products are generally low in omega-3 (n-3) fatty acids, which are beneficial to human health. We describe the generation of cloned pigs that express a humanized Caenorhabditis elegans gene, fat-1, encoding an n-3 fatty acid desaturase. The hfat-1 transgenic pigs produce high levels of n-3 fatty acids from n-6 analogs, and their tissues have a significantly reduced ratio of n-6/n-3 fatty acids (P < 0.001).     

Deconstructing the molecular portrait of basal-like breast cancer

Gene-expression profiling has revealed several molecular subtypes of breast cancer, which differ in their pathobiology and clinical outcomes. Basal-like tumors are a newly recognized subtype of breast cancer, which express genes that are characteristic of basal epithelial cells, such as the basal cytokeratins, and are associated with poor relapse-free and overall survival. However, the genetic and epigenetic alterations that are responsible for the biologically aggressive phenotype of these estrogen receptor-negative and HER2/ErbB2-negative tumors are not well understood, thereby hindering efforts to develop targeted therapies. Here, we focus on new insights into the molecular pathogenesis of basal-like breast cancer and explore how these discoveries might impact the treatment of these poor-prognosis tumors.     

Developmental origin of shark electrosensory organs

Vertebrates have evolved electrosensory receptors that detect electrical stimuli on the surface of the skin and transmit them somatotopically to the brain. In chondrichthyans, the electrosensory system is composed of a cephalic network of ampullary organs, known as the ampullae of Lorenzini, that can detect extremely weak electric fields during hunting and navigation. Each ampullary organ consists of a gel-filled epidermal pit containing sensory hair cells, and synaptic connections with primary afferent neurons at the base of the pit that facilitate detection of voltage gradients over large regions of the body. The developmental origin of electroreceptors and the mechanisms that determine their spatial arrangement in the vertebrate head are not well understood. We have analyzed electroreceptor development in the lesser spotted catshark (Scyliorhinus canicula) and show that Sox8 and HNK1, two markers of the neural crest lineage, selectively mark sensory cells in ampullary organs. This represents the first evidence that the neural crest gives rise to electrosensory cells. We also show that pathfinding by cephalic mechanosensory and electrosensory axons follows the expression pattern of EphA4, a well-known guidance cue for axons and neural crest cells in osteichthyans. Expression of EphrinB2, which encodes a ligand for EphA4, marks the positions at which ampullary placodes are initiated in the epidermis, and EphA4 is expressed in surrounding mesenchyme. These results suggest that Eph-Ephrin signaling may establish an early molecular map for neural crest migration, axon guidance and placodal morphogenesis during development of the shark electrosensory system.     

Metabolic and behavioural adaptations during early development of the Antarctic silverfish, Pleuragramma antarcticum

The Antarctic silverfish Pleuragramma antarcticum is a keystone species in the Ross Sea ecosystem, providing one of the major links between lower and higher trophic levels. Despite the importance of this species, surprisingly little is known of its early development and behaviour. Here, we determine the metabolic capacity of Pleuragramma embryonated eggs and larvae and make comparisons with developing stages of another notothenioid, the naked dragonfish Gymnodraco acuticeps. We also show that although large numbers of embryonated eggs of Pleuragramma are found floating among the platelet ice of Terra Nova Bay, they are able to sink prior to hatching in late spring, likely reducing the risk of exposure to the potentially lethal, ice-laden surface environment. Applying Stoke’s law, we determine the change in density required for embryonated eggs to sink at the measured rate and then consider possible mechanisms by which this might occur. Significantly, newly hatched larvae are positively gravitactic and negatively phototactic, such that their swimming behaviour also directs them away from the risk of freezing in the icy surface waters. Measurement of the acute thermal tolerance shows that Pleuragramma larvae have, on average, a sustainable swimming performance breadth of about 17°C, which is significantly greater than that of other adult notothenioids. Although it lacks significant antifreeze capacity in its early developmental stages, Pleuragramma has other attributes that may ensure survival over a wider range of environmental temperatures than other more stenothermal Antarctic notothenioids. How it might adapt to prolonged environmental change arising from phenomena such as global warming, however, requires further investigation.     

Orthopedic gene therapy—lost in translation?

Orthopedic gene therapy has been the topic of considerable research for two decades. The preclinical data are impressive and many orthopedic conditions are well suited to genetic therapies. But there have been few clinical trials and no FDA-approved product exists. This paper examines why this is so. The reasons are multifactorial. Clinical translation is expensive and difficult to fund by traditional academic routes. Because gene therapy is viewed as unsafe and risky, it does not attract major funding from the pharmaceutical industry. Start-up companies are burdened by the complex intellectual property environment and difficulties in dealing with the technology transfer offices of major universities. Successful translation requires close interactions between scientists, clinicians and experts in regulatory and compliance issues. It is difficult to create such a favorable translational environment. Other promising fields of biological therapy have contemplated similar frustrations approximately 20 years after their founding, so there seem to be more general constraints on translation that are difficult to define. Gene therapy has noted some major clinical successes in recent years, and a sense of optimism is returning to the field. We hope that orthopedic applications will benefit collaterally from this upswing and move expeditiously into advanced clinical trials.     

Heat Shock Protein 90 Inhibitors Reduce Trafficking of ATP-gated P2X1 Receptors and Human Platelet Responsiveness

We have used selective inhibitors to determine whether the molecular chaperone heat shock protein 90 (HSP90) has an effect on both recombinant and native human P2X1 receptors. P2X1 receptor currents in HEK293 cells were reduced by ∼70–85% by the selective HSP90 inhibitor geldanamycin (2 μm, 20 min). This was associated with a speeding in the time course of desensitization as well as a reduction in cell surface expression. Imaging in real time of photoactivatable GFP-tagged P2X receptors showed that they are highly mobile. Geldanamycin almost abolished this movement for P2X1 receptors but had no effect on P2X2 receptor trafficking. P2X1/2 receptor chimeras showed that the intracellular N and C termini were involved in geldanamycin sensitivity. Geldanamycin also inhibited native P2X1 receptor-mediated responses. Platelet P2X1 receptors play an important role in hemostasis, contribute to amplification of signaling to a range of stimuli including collagen, and are novel targets for antithrombotic therapies. Platelet P2X1 receptor-, but not P2Y1 receptor-, mediated increases in intracellular calcium were reduced by 40–45% following HSP90 inhibition with geldanamycin or radicicol. Collagen stimulation leads to ATP release from platelets, and calcium increases to low doses of collagen were also reduced by ∼40% by the HSP90 inhibitors consistent with an effect on P2X1 receptors. These studies suggest that HSP90 inhibitors may be as effective as selective antagonists in regulating platelet P2X1 receptors, and their potential effects on hemostasis should be considered in clinical studies.     

Unique peptide substrate binding properties of 110-kDa heat-shock protein (Hsp110) determine its distinct chaperone activity

The molecular chaperone 70-kDa heat-shock proteins (Hsp70s) play essential roles in maintaining protein homeostasis. Hsp110, an Hsp70 homolog, is highly efficient in preventing protein aggregation but lacks the hallmark folding activity seen in Hsp70s. To understand the mechanistic differences between these two chaperones, we first characterized the distinct peptide substrate binding properties of Hsp110s. In contrast to Hsp70s, Hsp110s prefer aromatic residues in their substrates, and the substrate binding and release exhibit remarkably fast kinetics. Sequence and structure comparison revealed significant differences in the two peptide-binding loops: the length and properties are switched. When we swapped these two loops in an Hsp70, the peptide binding properties of this mutant Hsp70 were converted to Hsp110-like, and more impressively, it functionally behaved like an Hsp110. Thus, the peptide substrate binding properties implemented in the peptide-binding loops may determine the chaperone activity differences between Hsp70s and Hsp110s.