Plasma N-glycome composition associates with chronic low back pain

Background

Low back pain (LBP) is the symptom of a group of syndromes with heterogeneous underlying mechanisms and molecular pathologies, making treatment selection and patient prognosis very challenging. Moreover, symptoms and prognosis of LBP are influenced by age, gender, occupation, habits, and psychological factors. LBP may be characterized by an underlying inflammatory process. Previous studies indicated a connection between inflammatory response and total plasma N-glycosylation. We wanted to identify potential changes in total plasma N-glycosylation pattern connected with chronic low back pain (CLBP), which could give an insight into the pathogenic mechanisms of the disease.

Influence of training on the response to exercise of adrenocorticotropin and growth hormone plasma concentrations in human swimmers

The aim of the present study was to evaluate the response of adrenocorticotropin ([ACTH]) and growth hormone ([GH]) concentrations to a typical aerobic swimming set during a training season. Nine top-level male endurance swimmers (age range 17–23 years) were tested during three training sessions occurring 6, 12 and 18 weeks after the beginning of the season. During each session, after a standard warm-up, the swimmers performed a training set of 15 × 200-m freestyle, with 20 s of rest between repetitions, at a predetermined individual speed. Blood samples were collected before warm-up and at the end of the training set. A few days before each session, the individual swimming velocity corresponding to the 4 mmol · l⁻¹ blood lactate concentration (v ₄) was assessed as a standard of aerobic performance. Aerobic training affected v ₄ levels, which were highest 18 weeks after the beginning of the season; at the same time, while [ACTH] response was attenuated, [GH] response was enhanced. These results could be considered as adaptations to the exercise intensity. In our training programme, these adaptations seemed to have occurred between the 12th and 18th weeks of the training season. Accepted: 21 April 1998     

Isozyme diversity, RFLP of the rDNA and phylogenetic affinities among cultivated Lima beans,Phaseolus lunatus (Fabaceae)

Genetic variation inPhaseolus lunatus (Lima bean) was investigated at isozyme and DNA levels. Sixty cultivated accessions, including representatives of the Mesoamerican and Andean gene pools and intermediate types, were analyzed for variability at 17 isozyme loci. Some accessions were also examined for restriction fragment length polymorphism (RFLP) at the rDNA level. These data were used to construct two dendrograms showing clear separation in two distinct groups corresponding to each of the gene pools and an intermediate one probably representing a transitional group.     

Complex II phosphorylation is triggered by unbalanced redox homeostasis in cells lacking complex III

A marked stimulation of complex II enzymatic activity was detected in cybrids bearing a homoplasmic MTCYB microdeletion causing disruption of both the activity and the assembly of complex III, but not in cybrids harbouring another MTCYB mutation affecting only the complex III activity. Moreover, complex II stimulation was associated with SDHA subunit tyrosine phosphorylation. Despite the lack of detectable hydrogen peroxide production, up-regulation of the levels of mitochondrial antioxidant defenses revealed a significant redox unbalance. This effect was also supported by the finding that treatment with N-acetylcysteine dampened the complex II stimulation, SDHA subunit tyrosine phosphorylation, and levels of antioxidant enzymes. In the absence of complex III, the cellular amount of succinate, but not fumarate, was markedly increased, indicating that enhanced activity of complex II is hampered due to the blockage of respiratory electron flow. Thus, we propose that complex II phosphorylation and stimulation of its activity represent a molecular mechanism triggered by perturbation of mitochondrial redox homeostasis due to severe dysfunction of respiratory complexes. Depending on the site and nature of the damage, complex II stimulation can either bypass the energetic deficit as an efficient compensatory mechanism, or be ineffectual, leaving cells to rely on glycolysis for survival.     

In the early phase of programmed cell death in Tobacco Bright Yellow 2 cells the mitochondrial adenine nucleotide translocator, adenylate kinase and nucleoside diphosphate kinase are impaired in a reactive oxygen species-dependent manner

To investigate whether and how mitochondria can change in plant programmed cell death (PCD), we used the non-photosynthetic Tobacco Bright Yellow 2 (TBY-2) cells. These can be synchronized to high levels, stand out in terms of growth rate and homogeneity and undergo PCD as a result of heat shock. Using these cells we investigated the activity of certain mitochondrial proteins that have a role in providing ATP and/or other nucleoside triphosphates (NTPs). We show that, already after 2 h from the heat shock, when cell viability remains unaffected, the rate of ADP/ATP exchange due to adenine nucleotide translocator (ANT) activity, and the rate of the reactions catalysed by adenylate kinase (ADK; EC 2.7.4.3) and nucleoside diphosphate kinase (NDPK; EC 2.7.4.6) are inhibited in a non-competitive-like manner. In all cases, externally added ascorbate partially prevented the inhibition. These effects occurred in spite of minor (for ANT) or no changes in the mitochondrial protein levels as immunologically investigated. Interestingly, a decrease of both the steady state level of the ascorbate pool and of the activity of l-galactono-gamma-lactone dehydrogenase (GLDH) (EC 1.3.2.3), the mitochondrial enzyme catalysing the last step of ascorbate biosynthesis, were also found.     

Isolation, Nucleotide Sequence, and Physiological Relevance of the Gene Encoding Triose Phosphate Isomerase from Kluyveromyces lactis

Lack of triose phosphate isomerase activity (TIM) is of special interest because this enzyme works at an important branch point of glycolytic flux. In this paper, we report the cloning and sequencing of the Kluyveromyces lactis gene encoding TIM. Unlike Saccharomyces cerevisiae ΔTPI1 mutants, the K. lactis mutant strain was found to be able to grow on glucose. Preliminary bioconversion experiments indicated that, like the S. cerevisiae TIM-deficient strain, the K. lactis TIM-deficient strain is able to produce glycerol with high yield.     

In vitro evidence for the participation of Drosophila melanogaster sperm β‐N‐acetylglucosaminidases in the interactions with glycans carrying terminal N‐acetylglucosamine residues on the egg's envelopes

Fertilization is a complex and multiphasic process, consisting of several steps, where egg‐coating envelope's glycoproteins and sperm surface receptors play a critical role. Sperm‐associated β‐N‐acetylglucosaminidases, also known as hexosaminidases, have been identified in a variety of organisms. Previously, two isoforms of hexosaminidases, named here DmHEXA and DmHEXB, were found as intrinsic proteins in the sperm plasma membrane of Drosophila melanogaster. In the present work, we carried out different approaches using solid‐phase assays in order to analyze the oligosaccharide recognition ability of D. melanogaster sperm hexosaminidases to interact with well‐defined carbohydrate chains that might functionally mimic egg glycoconjugates. Our results showed that Drosophila hexosaminidases prefer glycans carrying terminal β‐N‐acetylglucosamine, but not core β‐N‐acetylglucosamine residues. The capacity of sperm β‐N‐acetylhexosaminidases to bind micropylar chorion and vitelline envelope was examined in vitro assays. Binding was completely blocked when β‐N‐acetylhexosaminidases were preincubated with the glycoproteins ovalbumin and transferrin, and the monosaccharide β‐N‐acetylglucosamine. Overall, these data support the hypothesis of the potential role of these glycosidases in sperm–egg interactions in Drosophila.