TNF-α is associated with loss of lean body mass only in already cachectic COPD patients

Background

Systemic inflammation may contribute to cachexia in patients with chronic obstructive pulmonary disease (COPD). In this longitudinal study we assessed the association between circulating C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 levels and subsequent loss of fat free mass and fat mass in more than 400 COPD patients over three years.

Methods

The patients, aged 40–76, GOLD stage II-IV, were enrolled in 2006/07, and followed annually. Fat free mass and fat mass indexes (FFMI & FMI) were calculated using bioelectrical impedance, and CRP, TNF-α, IL-1ß, and IL-6 were measured using enzyme immunoassays. Associations with mean change in FFMI and FMI of the four inflammatory plasma markers, sex, age, smoking, FEV₁, inhaled steroids, arterial hypoxemia, and Charlson comorbidity score were analyzed with linear mixed models.

Results

At baseline, only CRP was significantly (but weakly) associated with FFMI (r = 0.18, p < 0.01) and FMI (r = 0.27, p < 0.01). Univariately, higher age, lower FEV₁, and use of beta2-agonists were the only significant predictors of decline in FFMI, whereas smoking, hypoxemia, Charlson score, and use of inhaled steroids predicted increased loss in FMI. Multivariately, high levels of TNF-α (but not CRP, IL-1ß or IL-6) significantly predicted loss of FFMI, however only in patients with established cachexia at entry.

Conclusion

This study does not support the hypothesis that systemic inflammation is the cause of accelerated loss of fat free mass in COPD patients, but suggests a role for TNF-α in already cachectic COPD patients.     

Large, rapidly evolving intergenic spacers in the mitochondrial DNA of the salamander family Ambystomatidae (Amphibia: Caudata)

We report the presence, in the mitochondrial DNA (mtDNA) of all of the sexual species of the salamander family Ambystomatidae, of a shared 240- bp intergenic spacer between tRNAThr and tRNAPro. We place the intergenic spacer in context by presenting the sequence of 1,746 bp of mtDNA from Ambystoma tigrinum tigrinum, describe the nucleotide composition of the intergenic spacer in all of the species of Ambystomatidae, and compare it to other coding and noncoding regions of Ambystoma and several other vertebrate mtDNAs. The nucleotide substitution rate of the intergenic spacer is approximately three times faster than the substitution rate of the control region, as shown by comparisons among six Ambystoma macrodactylum sequences and eight members of the Ambystoma tigrinum complex. We also found additional inserts within the intergenic spacers of five species that varied from 87-444 bp in length. The presence of the intergenic spacer in all sexual species of Ambystomatidae suggests that it arose at least 20 MYA and has been a stable component of the ambystomatid mtDNA ever since. As such, it represents one of the few examples of a large and persistent intergenic spacer in the mtDNA of any vertebrate clade.      

Ontogenetic transition in leaf traits: a new cost associated with the increase in leaf longevity

Aims Recent work has identified a worldwide 'economics' spectrum of correlated leaf traits that mainly reflects the compromises between maximizing leaf longevity and short-term productivity. However, during the early stages of tree growth different species tend to exhibit a common strategy, because competition for soil water and nutrients forces the maximization of short-term productivity owing to the need for rapid growth during the most vulnerable part of the tree's life cycle. Accordingly, our aim here was to compare the variations that occur during ontogeny in the different leaf traits (morphology and leaf chemical composition) of several coexisting Mediterranean woody species differing in their leaf life spans and to test our hypothesis that tree species with a long leaf life span should exhibit larger shifts in leaf characteristics along ontogeny.Methods Six Mediterranean tree species differing in leaf life span, selected from three plots located in central-western Spain, were studied during three growth stages: seedlings, juveniles and mature trees. Leaf life span, leaf morphology (leaf area, dry weight, thickness and mass per unit area) and chemical composition (N and fibre concentrations) were measured in all six species. The magnitude of the ontogenetic changes in the different traits was estimated and related to the mean leaf longevity of the different species.Important findings Along ontogeny, strong changes were observed in all variables analysed. The early growth stages showed lower leaf thickness, leaf thickness and mass per unit area and N, cellulose and hemicellulose concentrations than mature trees, but a higher lignin content. However, these changes were especially marked in species with a longer leaf life span at maturity. Interspecific differences in leaf life span, leaf morphology and chemical composition were stronger at the mature stage than at the seedling stage. We conclude that greater plasticity and more intense strategy shifts along ontogeny are necessarily associated with long leaf life span. Our results thus provide a new aspect that should be incorporated into the analysis of the costs and benefits associated with the different strategies related to leaf persistence displayed by the different species. Accordingly, the intensity of the alterations in leaf traits among different growth stages should be added to the suite of traits that change along the leaf economics spectrum.     

Development of Bacteriocinogenic Strains of Saccharomyces cerevisiae Heterologously Expressing and Secreting the Leaderless Enterocin L50 Peptides L50A and L50B from Enterococcus faecium L50

A segregationally stable expression and secretion vector for Saccharomyces cerevisiae, named pYABD01, was constructed by cloning the yeast gene region encoding the mating pheromone α-factor 1 secretion signal (MFα1_s) into the S. cerevisiae high-copy-number expression vector pYES2. The structural genes of the two leaderless peptides of enterocin L50 (EntL50A and EntL50B) from Enterococcus faecium L50 were cloned, separately (entL50A or entL50B) and together (entL50AB), into pYABD01 under the control of the galactose-inducible promoter P_GAL1. The generation of recombinant S. cerevisiae strains heterologously expressing and secreting biologically active EntL50A and EntL50B demonstrates the suitability of the MFα1_s-containing vector pYABD01 to direct processing and secretion of these antimicrobial peptides through the S. cerevisiae Sec system.Lactic acid bacteria (LAB) are widely known for their ability to produce a variety of ribosomally synthesized proteins or peptides, referred to as bacteriocins, displaying antimicrobial activity against a broad range of gram-positive bacteria and, to a lesser extent, gram-negative bacteria, including spoilage and food-borne pathogenic microorganisms (11, 19, 33, 34, 36, 37). These antimicrobials may be classified into three main classes: (i) the lantibiotics, or posttranslationally modified peptides; (ii) the nonmodified, small, heat-stable peptides; and (iii) the large, heat-labile protein bacteriocins. Class II bacteriocins are further grouped into five subclasses: the subclass IIa (pediocin-like bacteriocins containing the N-terminal conserved motif YGNGVxC), the subclass IIb (two-peptide bacteriocins), the subclass IIc (leaderless bacteriocins), the subclass IId (circular bacteriocins), and the subclass IIe (other peptide bacteriocins) (17, 19, 21, 37). All lantibiotics and most class II bacteriocins are synthesized as biologically inactive precursors containing an N-terminal extension (the so-called double-glycine-type leader sequence or the Sec-dependent signal peptide), which is cleaved off concomitantly with externalization of biologically active bacteriocins by a dedicated ATP-binding cassette transporter and its accessory protein or by the Sec system and the signal peptidases, respectively (11, 17). Interestingly, only a few bacteriocins described to date are synthesized without an N-terminal extension, including enterocin L50 (L50A and L50B) (8), enterocin Q (EntQ) (10), enterocin EJ97 (41), and the bacteriocin LsbB (20).In recent years, there has been an increasing interest in the application of bacteriocinogenic microorganisms and/or their bacteriocins as biopreservatives to guarantee the safety and quality of foods and beverages, such as fermented vegetables and meats, dairy and fish products, and wine and beer (12, 15, 16, 39, 47). Three main strategies for the use of bacteriocins as food biopreservatives have been proposed: (i) addition of a purified/semipurified bacteriocin preparation as a food additive; (ii) use of a substrate previously fermented by a bacteriocin-producing strain as a food ingredient; and/or (iii) inoculation of a culture to produce the bacteriocin in situ in fermented foods (13, 15). The lantibiotic nisin A is the most widely characterized bacteriocin and the only one that has been legally approved in more than 48 countries as a food additive for use in certain types of cheeses (13, 16). Likewise, nisin A has been approved as a beer additive in Australia and New Zealand (16). However, the difficulties encountered in addressing the regulatory approval of new bacteriocins as food additives have spurred the development of the other bacteriocin-based food biopreservation strategies (13, 17).Beer is a beverage with a remarkable microbiological stability and is considered as a food substrate difficult to spoil. However, some LAB, such as Lactobacillus brevis, Lactobacillus lindneri, and Pediococcus damnosus, are able to spoil beer and are recognized as the most hazardous bacteria for breweries, being responsible for approximately 70% of microbial beer spoilage incidents (40, 47). The ever-growing consumer demand for less-processed and less chemically preserved foods and beverages is promoting the development of alternative biocontrol strategies, such as those based on the use of bacteriocins as biopreservatives (12, 15, 39, 47). However, beyond the strict requirements to fulfill legal regulations, the commercial application of bacteriocins as beer additives is hindered mainly by low bacteriocin production yields and increases in production costs (44). Considering that Saccharomyces cerevisiae is commonly used as starter culture for brewing (24, 28, 35), a novel beer biopreservation strategy based on the development of bactericidal S. cerevisiae brewing strains has been proposed to overcome the aforementioned challenges (44, 46, 47). In this respect, the heterologous production of LAB bacteriocins, namely, pediocin PA-1 (PedPA-1) from Pediococcus acidilactici PAC1.0 and plantaricin 423 from Lactobacillus plantarum 423, by laboratory strains of S. cerevisiae has been reported (44, 46).Enterocin L50 (EntL50) is a commonly found bacteriocin composed of two highly related leaderless antimicrobial peptides, enterocin L50A (EntL50A) and enterocin L50B (EntL50B), which possesses a broad antimicrobial spectrum against LAB, food-borne pathogenic bacteria, and human and animal clinical pathogens (8, 9, 10, 11). Previous work by our group showed that EntL50 (EntL50A and EntL50B) may be used as a beer biopreservative to inhibit the growth of beer spoilage bacteria (1). Therefore, genetically engineered strains of S. cerevisiae heterologously expressing and secreting EntL50A and EntL50B have been developed in this work. For this purpose, we constructed the segregationally stable expression and secretion vector pYABD01, which allowed the secretion of biologically active EntL50A and EntL50B directed by MFα1_s through the S. cerevisiae Sec system.     

Mobilization of Neural Stem Cells and Generation of New Neurons in 6-OHDA�Clesioned Rats by Intracerebroventricular Infusion of Liver Growth Factor

Neural stem cells with self-renewal and multilineage potential persist in the subventricular zone of the adult mammalian forebrain. These cells remain relatively quiescent but, under certain conditions, can be stimulated, giving rise to new neurons. Liver growth factor (LGF) is a mitogen for liver cells that shows biological activity in extrahepatic sites and is useful for neuroregenerative therapies. The aim of this study was to investigate the potential neurogenic activity of LGF in the 6-hydroxydopamine rat model of Parkinson''s disease. Proliferation was significantly increased in the subventricular zone and denervated striatum of rats receiving ICV LGF infusions, and 25% of the proliferating cells were doublecortin-positive neurons. Doublecortin-positive cells with the morphology of migrating neuroblasts were also observed in the dorsal and ventral regions of the striatum of LGF-infused animals. Moreover, some newly generated cells were neuronal nuclei-positive mature neurons. LGF also stimulated microglia and induced astrogliosis, both phenomena associated with generation and migration of new neurons in the adult brain. In summary, our study shows that LGF stimulates neurogenesis when applied intraventricularly in 6-hydroxydopamine–lesioned rats. Considering that this factor also promotes neuronal migration into damaged tissue, we propose LGF as a novel factor useful for neuronal replacement in neurodegenerative diseases. (J Histochem Cytochem 57:491–502, 2009)