Metabolic characteristics and oxidative damage to skeletal muscle in broiler chickens exposed to chronic heat stress

Emerging evidence has shown that acute heat exposure affects metabolic characteristics and causes oxidative damage to skeletal muscle in birds. Little is known, however, about such phenomena under chronic heat stress conditions. To address this, we designed the present study to determine the influence of cyclic (32 to 24 to 32 °C: 32 °C for 8 h/d, 32–24–32HS ), and constant (32 and 34 °C, 32HS and 34HS, respectively) heat exposure on the metabolic and peroxide status in skeletal muscle of 4-wk-old male broiler chickens. Heat stress, particularly in the 32HS and 34HS groups, depressed feed intake and growth, while cyclic high temperature gave rise to a less severe stress response in performance terms. Malondialdehyde (MDA) levels in skeletal muscle were enhanced (P < 0.05) by constant heat treatment; the degree of enhancement was not as large as the changes observed in our previous ‘acute’ heat stress model. The 3HADH (3-hydroxyacyl CoA dehydrogenase related to fatty acid oxidation) and CS (citrate synthase) enzyme activities were lowered (P < 0.05) by both the cyclic and constant 34HS treatments, and constant 34HS group, respectively. These results suggest that chronic heat exposure decreases metabolic oxidation capacity in skeletal muscle of broiler chickens. On exposure to chronic heat stress, GPx activity remained relatively constant, though a temperature-dependent elevation in Cu/Zn-SOD activity was observed, implying that anti-oxidation ability was disturbed by the chronic stress condition. From these results it can be concluded that chronic heat stress did not induce oxidative damage to a major extent. This may probably be due to a decrease in metabolic oxidation capacity or due to a self-propagating scavenging system, though the system was not fully activated.     

Macrophage Dysfunction Impairs Resolution of Inflammation in the Wounds of Diabetic Mice

Background

Chronic inflammation is a characteristic feature of diabetic cutaneous wounds. We sought to delineate novel mechanisms involved in the impairment of resolution of inflammation in diabetic cutaneous wounds. At the wound-site, efficient dead cell clearance (efferocytosis) is a pre-requisite for the timely resolution of inflammation and successful healing.

Methodology/Principal Findings

Macrophages isolated from wounds of diabetic mice showed significant impairment in efferocytosis. Impaired efferocytosis was associated with significantly higher burden of apoptotic cells in wound tissue as well as higher expression of pro-inflammatory and lower expression of anti-inflammatory cytokines. Observations related to apoptotic cell load at the wound site in mice were validated in the wound tissue of diabetic and non-diabetic patients. Forced Fas ligand driven elevation of apoptotic cell burden at the wound site augmented pro-inflammatory and attenuated anti-inflammatory cytokine response. Furthermore, successful efferocytosis switched wound macrophages from pro-inflammatory to an anti-inflammatory mode.

Conclusions/Significance

Taken together, this study presents first evidence demonstrating that diabetic wounds suffer from dysfunctional macrophage efferocytosis resulting in increased apoptotic cell burden at the wound site. This burden, in turn, prolongs the inflammatory phase and complicates wound healing.     

The Parkinson's Disease Associated LRRK2 Exhibits Weaker In Vitro Phosphorylation of 4E-BP Compared to Autophosphorylation

Mutations in the gene encoding Leucine-rich repeat kinase 2 (LRRK2) are the most common cause of inherited Parkinson''s disease (PD). LRRK2 is a multi-domain protein kinase containing a central catalytic core and a number of protein-protein interaction domains. An important step forward in the understanding of both the biology and the pathology of LRRK2 would be achieved by identification of its authentic physiological substrates. In the present study we examined phosphorylation of 4E-BP (eukaryotic initiation factor 4E (eIF4E)-binding protein), a recently proposed substrate for LRRKs. We found that LRRK2 is capable of phosphorylating 4E-BP in vitro. The PD related LRRK2-G2019S mutant was ∼2 fold more active than wild type protein. However, LRRK2 autophosphorylation was stronger than 4E-BP phosphorylation under conditions of molar excess of 4E-BP to LRRK2. We also tested three other kinases (STK3, MAPK14/p38α and DAPK2) and found that MAPK14/p38α could efficiently phosphorylate 4E-BP at the same site as LRRK2 in vitro. Finally, we did not see changes in 4E-BP phosphorylation levels using inducible expression of LRRK2 in HEK cell lines. We also found that MAPK14/p38α phosphorylates 4E-BP in transient overexpression experiments whereas LRRK2 did not. We suggest that increased 4E-BP phosphorylation reported in some systems may be related to p38-mediated cell stress rather than direct LRRK2 activity. Overall, our results suggest that 4E-BP is a relatively poor direct substrate for LRRK2.     

Retracted: In Bangladesh,overweight individuals have fewer symptoms of depression than nonoverweight individuals

The aim of this study was to examine whether the association between overweight and depression usually found in western societies would also be found in locations where overweight is not stigmatized. A total of 1,271 individuals from rural Bangladesh were randomly selected; the response rate was 76%. Depressive symptoms were measured with the Montgomery‐Åsberg Depression Rating Scale (MADRS). The sum MADRS scores were 13.4 (s.d. = 5.8) and 18.5 (8.1) for overweight vs. nonoverweight (t = 6.6; P < 0.000) men, respectively, and 19.7 (7.8) and 23.2 (7.9) for overweight vs. nonoverweight women, respectively (t = 4.2; P < 0.000). Thus the MADRS score was lower in overweight individuals. After adjusting for sex and age, BMI significantly predicted the MADRS score (β = ?0.3; t = 10.2; P < 0.000). These findings suggest that overweight may be related to fewer depressive symptoms in non western cultures.     

Modeling oxidative stress in the central nervous system

Oxidative stress is associated with the onset and pathogenesis of several prominent central nervous system disorders. Consequently, there is a pressing need for experimental methods for studying neuronal responses to oxidative stress. A number of techniques for modeling oxidative stress have been developed, including the use of inhibitors of the mitochondrial respiratory chain, depletion of endogenous antioxidants, application of products of lipid peroxidation, use of heavy metals, and models of ischemic brain injury. These experimental approaches can be applied from cell culture to in vivo animal models. Their use has provided insight into the molecular underpinnings of oxidative stress responses in the nervous system, including cell recovery and cell death. Reactive oxygen species contribute to conformational change-induced activation of signaling pathways, inactivation of enzymes through modification of catalytic cysteine residues, and subcellular redistribution of signaling molecules. In this review, we will discuss several methods for inducing oxidative stress in the nervous system and explore newly emerging concepts in oxidative stress signaling.     

Proteomics in clinical trials and practice: present uses and future promise

The study of clinical proteomics is a promising new field that has the potential to have many applications, including the identification of biomarkers and monitoring of disease, especially in the field of oncology. Expression proteomics evaluates the cellular production of proteins encoded by a particular gene and exploits the differential expression and post-translational modifications of proteins between healthy and diseased states. These biomarkers may be applied towards early diagnosis, prognosis, and prediction of response to therapy. Functional proteomics seeks to decipher protein-protein interactions and biochemical pathways involved in disease biology and targeted by newer molecular therapeutics. Advanced spectrometry technologies and new protein array formats have improved these analyses and are now being applied prospectively in clinical trials. Further advancement of proteomics technology could usher in an era of personalized molecular medicine, where diseases are diagnosed at earlier stages and where therapies are more effective because they are tailored to the protein expression of a patient's malignancy.     

The fission yeast ptr1+ gene involved in nuclear mRNA export encodes a putative ubiquitin ligase

Fission yeast ptr1-1 is one of the mRNA transport mutants that accumulate poly(A)+ RNA in the nuclei at the nonpermissive temperature. We found that the ptr1+ gene encodes a homolog of Saccharomyces cerevisiae Tom1p, a hect type ubiquitin ligase. In ptr1-1, a conserved amino acid in the hect domain of Ptr1p is mutated. The ptr1+ gene is essential for growth and its mutation did not affect nuclear protein export. A ptr1-1 rae1-167 double mutant showed a synthetic effect on a growth defect, indicating that Ptr1p functionally interacts with an essential mRNA export factor Rae1p. We also isolated a multi-copy suppressor for ptr1-1 and found that it is the mpd2+ gene isolated as a multi-copy suppressor of cdc7-PD1.     

Chemopreventive action of Phyllanthus urinaria Linn on DMBA-induced skin carcinogenesis in mice

The inhibition of tumor incidence by hydro-alcoholic extract of the whole plant of P. urinaria was evaluated in 6-7 weeks old female albino mice on two-stage process of skin carcinogenesis induced by a single application of 7,12-dimethylbenz(a)anthracene (50 microg/50 microl of acetone), and 2 weeks later, promoted by repeated application of croton oil (1% in acetone/three times a week) till the end of the experiment (15 weeks). Topical application of the extract at a dose of 5 mg/kg body weight/day for 15 weeks at the peri-initiational stage (i.e., 7 days before and 7 days after DMBA application), promotional stage (i.e., from the time of croton oil application) and both peri and post-initiational stages (i.e., 7 days prior to DMBA application and continued till the end of the experiment) on the shaven backs of the mice recorded a significant reduction in tumor incidence to 50, 33.3 and 16.7% respectively in comparison to the control (i.e., the mice treated with DMBA and croton oil only) where tumor incidence was found to be 81.8%. The average number of papillomas per mouse was also significantly reduced. The results suggest a possible chemopreventive property of P. urinaria against DMBA-induced skin papillomagenesis in mice.     

The major shifts of human duplicated genes

Since many gene duplications in the human genome are ancient duplications going back to the origin of vertebrates, the question may be asked about the fate of such duplicated genes at the compositional genome transitions that occurred between cold- and warm-blooded vertebrates. Indeed, at that transition, about half of the (GC-poor) genes of cold-blooded vertebrates (the genes of the gene-dense "ancestral genome core") underwent a GC enrichment to become the genes of the "genome core" of warm-blooded vertebrates. Since the compositional distribution of the human duplicated genes investigated (1111 pairs) mimics the general distribution of human genes (about 50% GC(3)-poor and 50% GC(3)-rich genes, the border being at 60% GC(3)), we considered two possibilities, namely that the compositional transition affected either (i) about half of the copies on a random basis, or (ii) preferentially only one copy of the duplicated genes. The two possibilities could be distinguished if each copy is put into one of two subsets according to its GC(3) level. Indeed, in the first case, the two distributions would be similar, whereas in the second case, the two distributions would be different, one copy having maintained the ancestral GC-poor composition, and one copy having undergone the compositional change. Using this approach, we could show that, by far and large, one copy of the duplicated genes preferentially underwent the GC enrichment. This result implies that this copy, which had possibly acquired a different function and/or regulation, was preferentially translocated into the gene-dense compartment of the genome, the "ancestral genome core", namely the "gene space" which underwent the compositional transition at the emergence of warm-blooded vertebrates.