Studies on glycopeptides derived from acidic glycoproteins of guinea-pig serum

1. Fraction I, a fraction containing acidic glycoproteins, isolated from guinea-pig serum, was digested with Pronase after removal of sialic acid and a major and a minor glycopeptide fraction were isolated by chromatography with Sephadex G-25 and G-50. 2. The major fraction was examined by various methods and shown to contain several glycopeptides. Estimates of molecular weight of the glycopeptide fractions were obtained. Although some variation appeared to occur, the glycopeptides were not grossly heterogeneous with respect to size. An average prosthetic group was estimated to contain about 15 sugar residues. 3. Aspartic acid was the principal amino acid present in the fractions and in all subfractions of the major fraction investigated. Where examined, ammonia was liberated on acid hydrolysis in approximately equimolar amounts to the aspartic acid present. The carbohydrate composition of the fractions was also determined. 4. The glycopeptides showed relatively little degradation in alkaline solution. 5. These results suggest that an N-acylglycosylamine bond involving aspartic acid forms the major type of linkage between carbohydrate and polypeptide. The isolation of a compound with the composition and chromatographic properties of 2-acetamido-1-(l-beta-aspartamido)-1,2-dideoxy-beta-d-glucose supports this view, and indicates that N-acetylglucosamine is the sugar involved in at least many linkages. 6. Fraction I contains some glycoproteins that are susceptible to Pronase and one or more others that resist digestion before the removal of sialic acid. A brief examination revealed some similarities between prosthetic groups derived from both kinds of glycoprotein.     

The effect of swimming activity on bone architecture in growing rats

The effect of non-habitual physical activity on bone architecture in the rat humeral shaft was examined. Two groups of rats were trained to swim for 1 h a day, for 20 weeks, at two training levels. The control group consisted of sedentary rats. Parameters of cross-sectional bone morphology (cross-section areas, principal area moments of inertia and their ratio) were used to evaluate the response of bone architecture to mechanical loading. The strength of bone was assessed by measuring the ultimate compressive force and stress. The cortical cross-section area and principal moments of inertia were found to be significantly higher in the swimming groups than in the controls. Examination of the ratio between the major and minor moments of inertia revealed a pronounced change in the shape of the bone cross-section which became more rounded following swimming training. The ultimate compressive force was significantly higher in the swimming rats while the changes in ultimate stress were not significant. Our results indicate a gain of bone strength due to increased periosteal apposition and modified bone tissue distribution. The marked changes in bone morphology are attributed to the different nature of the forces and moments exerted on the humerus during swimming compared to those prevailing during normal locomotion.     

The Power of the Web: A Systematic Review of Studies of the Influence of the Internet on Self-Harm and Suicide in Young People

Background

There is concern that the internet is playing an increasing role in self-harm and suicide. In this study we systematically review and analyse research literature to determine whether there is evidence that the internet influences the risk of self-harm or suicide in young people.

Methods

An electronic literature search was conducted using the PsycINFO, MEDLINE, EMBASE, Scopus, and CINAHL databases. Articles of interest were those that included empirical data on the internet, self-harm or suicide, and young people. The articles were initially screened based on titles and abstracts, then by review of the full publications, after which those included in the review were subjected to data extraction, thematic analysis and quality rating.

Results

Youth who self-harm or are suicidal often make use of the internet. It is most commonly used for constructive reasons such as seeking support and coping strategies, but may exert a negative influence, normalising self-harm and potentially discouraging disclosure or professional help-seeking. The internet has created channels of communication that can be misused to ‘cyber-bully’ peers; both cyber-bullying and general internet use have been found to correlate with increased risk of self-harm, suicidal ideation, and depression. Correlations have also been found between internet exposure and violent methods of self-harm.

Conclusions

Internet use may exert both positive and negative effects on young people at risk of self-harm or suicide. Careful high quality research is needed to better understand how internet media may exert negative influences and should also focus on how the internet might be utilised to intervene with vulnerable young people.     

Plant genome complexity may be a factor limiting in situ the transfer of transgenic plant genes to the phytopathogen Ralstonia solanacearum

The development of natural competence by bacteria in situ is considered one of the main factors limiting transformation-mediated gene exchanges in the environment. Ralstonia solanacearum is a plant pathogen that is also a naturally transformable bacterium that can develop the competence state during infection of its host. We have attempted to determine whether this bacterium could become the recipient of plant genes. We initially demonstrated that plant DNA was released close to the infecting bacteria. We constructed and tested various combinations of transgenic plants and recipient bacteria to show that the effectiveness of such transfers was directly related to the ratio of the complexity of the plant genome to the number of copies of the transgene.     

Markers of cartilage and bone matrix metabolism differ between the sera of macaque and squirrel monkeys

BACKGROUND: Nonhuman primates develop the characteristic lesions of osteoarthritis, making them attractive biomedical models for the study of environmental factors, such as diet, which may influence the progress of the condition. METHODS AND MATERIALS: We used ELISA assays of potential markers of osteoarthritis which were developed for use in humans to see if we could determined the presence of immunoreactivity in two nonhuman primate genera - Macaca (macaque monkeys) and Saimiri (squirrel monkeys). RESULTS: Inter-generic differences were significant for most markers. Three markers (bone alkaline phosphatase, hyaluronin and YKL-40) were outside the human range and two markers (laminin and C2C) did not yield useful results because they were off-scale high. CONCLUSION: Our results indicate that most of the ELISA assays designed for use with human serum can be used in nonhuman primates. The highly significant differences we observed between the sera of Macaca and Saimiri, suggest that further examination is warranted.     

Failure of catecholamines to shift T-cell cytokine responses toward a Th2 profile in patients with rheumatoid arthritis

To further understand the role of neuro-immunological interactions in the pathogenesis of rheumatoid arthritis (RA), we studied the influence of sympathetic neurotransmitters on cytokine production of T cells in patients with RA. T cells were isolated from peripheral blood of RA patients or healthy donors (HDs), and stimulated via CD3 and CD28. Co-incubation was carried out with epinephrine or norepinephrine in concentrations ranging from 10(-5) M to 10(-11) M. Interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, interleukin (IL)-4, and IL-10 were determined in the culture supernatant with enzyme-linked immunosorbent assay. In addition, IFN-gamma and IL-10 were evaluated with intracellular cytokine staining. Furthermore, basal and agonist-induced cAMP levels and catecholamine-induced apoptosis of T cells were measured. Catecholamines inhibited the synthesis of IFN-gamma, TNF-alpha, and IL-10 at a concentration of 10(-5) M. In addition, IFN-gamma release was suppressed by 10(-7) M epinephrine. Lower catecholamine concentrations exerted no significant effect. A reduced IL-4 production upon co-incubation with 10(-5) M epinephrine was observed in RA patients only. The inhibitory effect of catecholamines on IFN-gamma production was lower in RA patients as compared with HDs. In RA patients, a catecholamine-induced shift toward a Th2 (type 2) polarised cytokine profile was abrogated. Evaluation of intracellular cytokines revealed that CD8-positive T cells were accountable for the impaired catecholaminergic control of IFN-gamma production. The highly significant negative correlation between age and catecholamine effects in HDs was not found in RA patients. Basal and stimulated cAMP levels in T-cell subsets and catecholamine-induced apoptosis did not differ between RA patients and HDs. RA patients demonstrate an impaired inhibitory effect of catecholamines on IFN-gamma production together with a failure to induce a shift of T-cell cytokine responses toward a Th2-like profile. Such an unfavorable situation is a perpetuating factor for inflammation.