Immunologic and pharmacologic activity of atropine-protein conjugates

The immunological (production of specific antibodies to hapten) and pharmacological activity of bovine serum albumin conjugates with different chemical modifications of atropine was investigated. Mice and rabbits treated with atropine-protein conjugates (1-10 mg/kg) have produced a considerable number of specific serum antibodies to hapten during primary and secondary immune response. Mice treated with atropine-protein conjugates (25 and 50 mg/kg) have produced undetectable amounts of specific serum antibodies. The study of pharmacological activity in mice has revealed peripheral activity of atropine-protein conjugates. There was a correlation between the pharmacological activity of atropine-protein conjugates (25-50 mg/kg) and the activity of atropine (5 mg/kg), however the pharmacological effect of atropine-protein conjugates was somewhat longer. The results suggest that atropine-protein conjugates are both immunologically and pharmacologically active compounds.     

Heparan sulfate proteoglycan syndecan-3 is a novel receptor for GDNF, neurturin, and artemin

Glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) are potent survival factors for dopaminergic neurons and motoneurons with therapeutic potential for Parkinson's disease. Soluble GFLs bind to a ligand-specific glycosylphosphatidylinositol-anchored coreceptor (GDNF family receptor α) and signal through the receptor tyrosine kinase RET. In this paper, we show that all immobilized matrix-bound GFLs, except persephin, use a fundamentally different receptor. They interact with syndecan-3, a transmembrane heparan sulfate (HS) proteoglycan, by binding to its HS chains with high affinity. GFL-syndecan-3 interaction mediates both cell spreading and neurite outgrowth with the involvement of Src kinase activation. GDNF promotes migration of cortical neurons in a syndecan-3-dependent manner, and in agreement, mice lacking syndecan-3 or GDNF have a reduced number of cortical γ-aminobutyric acid-releasing neurons, suggesting a central role for the two molecules in cortical development. Collectively, syndecan-3 may directly transduce GFL signals or serve as a coreceptor, presenting GFLs to the signaling receptor RET.     

The geographical distribution of lymphatic filariasis infection in Malawi

Background

Papua New Guinea is the only endemic country in the Western Pacific Region that has not yet introduced a countrywide programme to eliminate lymphatic filariasis. However, on Misima Island in Milne Bay Province, government and private sectors have collaborated to implement a pilot elimination programme. Although interim evaluation indicated that the programme has been parasitologically successful, an appreciation that sustainable health gains depend on understanding and accommodating local beliefs prompted this qualitative study.

Methods

We investigated Misima community members knowledge and attitudes about lymphatic filariasis and the elimination programme. A combination of focus groups and key informant interviews were used to explore participants perceptions of health; knowledge of the aetiology and symptoms of filariasis, elephantiasis and hydrocele; attitudes towards the disease and mass drug distribution; and the social structure and decision-making protocols within the villages.

Results

Focus group discussions proved inferior to key informant interviews for gathering rich data. Study participants did not consider lymphatic filariasis ("pom") a major health problem but were generally positive about mass drug administration campaigns. A variety of conditions were frequently and incorrectly attributed to filariasis. Participants expressed the belief that individuals infected with filariasis always had visible manifestations of disease. A common misconception was that taking drugs during campaigns provided long-term immunity against disease. The role of mosquito vectors in transmission was not generally appreciated and certain clinical presentations, particularly hydrocele, were associated with supernatural forces. Multiple adverse events were associated with mass drug administration campaigns and most study participants mentioned community members who did not participate in campaigns.

Conclusion

Important issues requiring educational intervention and elimination activity modification in the Misima region were identified during this study. Research outcomes should assist Papua New Guinea in developing and implementing a national elimination strategy and inform discussions regarding the appropriateness of current elimination strategies.     

Seropositivity is associated with insulin resistance in patients with early inflammatory polyarthritis: results from the Norfolk Arthritis Register (NOAR): an observational study

Introduction  

Cardiovascular disease (CVD) is the leading cause of death in patients with inflammatory polyarthritis (IP), especially in seropositive disease. In established rheumatoid arthritis (RA), insulin resistance (IR) is increased and associated with CVD. We investigated factors associated with IR in an inception cohort of patients with early IP.     

Lack ofl-Iduronic Acid in Heparan Sulfate Affects Interaction with Growth Factors and Cell Signaling

HSEPI (glucuronyl C5-epimerase) catalyzes the conversion of d-glucuronic acid to l-iduronic acid in heparan sulfate (HS) biosynthesis. Disruption of the Hsepi gene in mice yielded a lethal phenotype with selective organ defects but had remarkably little effect on other organ systems. We have approached the underlying mechanisms by examining the course and effects of FGF2 signaling in a mouse embryonic fibroblast (MEF) cell line derived from the Hsepi^−/− mouse. The HS produced by these cells is devoid of l-iduronic acid residues but shows up-regulated N- and 6-O-sulfation compared with wild type (WT) MEF HS. In medium fortified with 10% fetal calf serum, the Hsepi^−/− MEFs proliferated and migrated similarly to WT cells. Under starvation conditions, both cell types showed attenuated proliferation and migration that could be restored by the addition of FGF2 to WT cells, whereas Hsepi^−/− cells were resistant. Moreover, ERK phosphorylation following FGF2 stimulation was delayed in Hsepi^−/− compared with WT cells. Assessment of HS-growth factor interaction by nitrocellulose filter trapping revealed a strikingly aberrant binding property of FGF2 and glia-derived neurotropic factor to Hsepi^−/− but not to WT HS. glia-derived neurotropic factor has a key role in kidney development, defective in Hsepi^−/− mice. By contrast, Hsepi^−/− and WT HS interacted similarly and in conventional mode with FGF10. These findings correlate defective function of growth factors with their mode of HS interaction and may help explain the partly modest organ phenotypes observed after genetic ablation of selected enzymes in HS biosynthesis.Signaling activities of numerous growth factors and morphogens during development involve cell surface receptor systems consisting of a tyrosine kinase-type receptor along with a heparan sulfate proteoglycan (HSPG)2 co-receptor (1, 2). The complex and heterogeneous HSPG macromolecules occur in the extracellular matrix and on the surfaces of virtually all animal cells (3). HS side chains of HSPGs show great structural variability; hence, they interact with a multitude of proteins and influence a variety of biological processes, including growth factor signaling (4).The structural diversity of HS is best envisaged through an account of its biosynthesis (Fig. 1). The process is initiated by glycosylation reactions that generate saccharide sequences composed of alternating GlcA and GlcNAc units covalently bound to a core protein (through a specific “linker” tetrasaccharide sequence). The resulting polymer of (GlcAβ1,4-GlcNAcα1,4-)_n disaccharide repeats is modified through a series of reactions, including N-deacetylation/N-sulfation of GlcNAc residues, C5-epimerization of GlcA to l-iduronic acid (IdoA) units, and O-sulfation at various positions of the hexuronic acid and glucosamine residues (4, 5). Modulation of these modification reactions, through as yet poorly understood mechanisms, yields HS chains of strictly regulated saccharide composition, varying with tissue source and age (6, 7). Interactions between protein ligands and HS involve selective ionic binding of peptide sequences containing basic amino acid residues to saccharide domains with clustered sulfate groups and IdoA residues. The latter components are considered to promote ligand apposition through their conformational flexibility (8).Open in a separate windowFIGURE 1.Schematic display of HS biosynthesis. A precursor structure composed of alternating GlcA and GlcNAc residues linked to a core protein is modified through the series of enzymatic reactions indicated and outlined under“Results.” The modifications yield domains of consecutive N-acetylated or N-sulfated disaccharide units, along with mixed sequences. Wild type HS contains both GlcA and IdoA residues, whereas Hsepi^−/− HS lacks IdoA units but shows increased N- and 6-O-sulfation. In particular, the mutant HS features extended sequences of -GlcA-GlcNS6S- disaccharide units.Targeted disruption of genes encoding HS biosynthesis enzymes demonstrated critical roles for HSPGs in developmental processes (9–11). The observed phenotypes vary dramatically in severity, from gastrulation failure to subtle disturbance of organ development. This variability may reflect redundancy due to the occurrence of isoforms for some of the enzymes. Alternatively, developmental events might be critically dependant on HS involvement but not on the fine structure of the polysaccharide chain, such that even structurally deranged HS would fulfill a functional role (12). The glucuronyl C5-epimerase (HSEPI) that catalyzes the conversion of GlcA to IdoA in HS biosynthesis is encoded by a single gene (13). Targeted disruption of this gene in mice resulted in an abnormal HS structure, completely lacking IdoA residues and with severely distorted sulfation pattern. The Hsepi-deficient mice die shortly after birth with multiple developmental defects, such as skeletal malformations and kidney agenesis. Intriguingly, however, other major organ systems, such as the brain and vascular system, known to depend on HS-supported signaling processes, developed seemingly normally (14).The present study was undertaken to obtain insight into the mechanisms behind the developmental defects in the Hsepi mutant mice, using a model system based on murine embryonic fibroblast (MEF) cell lines. The mutant MEF cells responded poorly to FGF2 in proliferation and migration experiments and showed defective FGF2-dependent intracellular signaling. Moreover, binding studies revealed an aberrant mode of interaction between mutant HS chains and certain growth factors, of potential relevance to growth factor signaling.     

The function of anabiosis autoinductors in microorganisms under blockade of metabolism

Alkyl-substituted hydroxybenzenes (AHBs), which are auto-inducers of microbial dormancy (d1 factors), were found to stabilize the structure of protein macromolecules and modify the catalytic activity of enzymes. In vitro experiments showed that C6-AHB at concentrations from 10(-4) to 10(-2) M, at which it occurs in the medium as a true solution and a micellar colloid, respectively, nonspecifically inhibited the activity of chymotrypsin, RNase, invertase, and glucose oxidase. C6-AHB-induced conformational alterations in protein macromolecules were due to the formation of complexes, as evidenced by differences in the fluorescence spectra of individual RNase and C6-AHB and their mixtures and in the surface tension isotherms of C6-AHB and trypsin solutions. Data on the involvement of dormancy auto-inducers in the post-translational modification of enzymes and their inhibition will provide further insight into the mechanisms of development and maintenance of dormant microbial forms.