Glycosylation of human trophoblast integrins is stage and cell-type specific

Cytotrophoblasts are the specialized epithelial cells of theplacenta. During the first trimester, a subpopulation of chorionicvillas cytotrophoblasts differentiates along an invasive pathwayand penetrates the maternal endo-metrium, decidua and spiralarterioles. Cytotrophoblast invasiveness declines rapidly duringthe second half of gestation. Isolated cytotrophoblasts of differentgestational ages retain this differential invasiveness in culture.To determine whether the properties of integrin receptors forextracellular matrix molecules differ between invasive and non-invasivecytotrophoblasts, detergent extracts of isolated cytotrophoblastsof different gestational ages, and of first-trimester villousfibroblasts, were immunoprecipitated with subunit-specific anti-     

Subjects with Knee Osteoarthritis Exhibit Widespread Hyperalgesia to Pressure and Cold

Hyperalgesia to mechanical and thermal stimuli are characteristics of a range of disorders such as tennis elbow, whiplash and fibromyalgia. This study evaluated the presence of local and widespread mechanical and thermal hyperalgesia in individuals with knee osteoarthritis, compared to healthy control subjects. Twenty-three subjects with knee osteoarthritis and 23 healthy controls, matched for age, gender and body mass index, were recruited for the study. Volunteers with any additional chronic pain conditions were excluded. Pain thresholds to pressure, cold and heat were tested at the knee, ipsilateral heel and ipsilateral elbow, in randomized order, using standardised methodology. Significant between-groups differences for pressure pain and cold pain thresholds were found with osteoarthritic subjects demonstrating significantly increased sensitivity to both pressure (p = .018) and cold (p = .003) stimuli, compared with controls. A similar pattern of results extended to the pain-free ipsilateral ankle and elbow indicating widespread pressure and cold hyperalgesia. No significant differences were found between groups for heat pain threshold, although correlations showed that subjects with greater sensitivity to pressure pain were also likely to be more sensitive to both cold pain and heat pain. This study found widespread elevated pain thresholds in subjects with painful knee osteoarthritis, suggesting that altered nociceptive system processing may play a role in ongoing arthritic pain for some patients.     

Modification of the ADP-ribosyltransferase and NAD glycohydrolase activities of a mammalian transferase (ADP-ribosyltransferase 5) by auto-ADP-ribosylation.

Mono-ADP-ribosylation, a post-translational modification in which the ADP-ribose moiety of NAD is transferred to an acceptor protein, is catalyzed by a family of amino acid-specific ADP-ribosyltransferases. ADP-ribosyltransferase 5 (ART5), a murine transferase originally isolated from Yac-1 lymphoma cells, differed in properties from previously identified eukaryotic transferases in that it exhibited significant NAD glycohydrolase (NADase) activity. To investigate the mechanism of regulation of transferase and NADase activities, ART5 was synthesized as a FLAG fusion protein in Escherichia coli. Agmatine was used as the ADP-ribose acceptor to quantify transferase activity. ART5 was found to be primarily an NADase at 10 microM NAD, whereas at higher NAD concentrations (1 mM), after some delay, transferase activity increased, whereas NADase activity fell. This change in catalytic activity was correlated with auto-ADP-ribosylation and occurred in a time- and NAD concentration-dependent manner. Based on the change in mobility of auto-ADP-ribosylated ART5 by SDS-polyacrylamide gel electrophoresis, the modification appeared to be stoichiometric and resulted in the addition of at least two ADP-ribose moieties. Auto-ADP-ribosylated ART5 isolated after incubation with NAD was primarily a transferase. These findings suggest that auto-ADP-ribosylation of ART5 was stoichiometric, resulted in at least two modifications and converted ART5 from an NADase to a transferase, and could be one mechanism for regulating enzyme activity.     

Retinal Changes Precede Visual Dysfunction in the Complement Factor H Knockout Mouse

We previously reported that aged mice lacking complement factor H (CFH) exhibit visual defects and structural changes in the retina. However, it is not known whether this phenotype is age-related or is the consequence of disturbed development. To address this question we investigated the effect of Cfh gene deletion on the retinal phenotype of young and mid-age mice. Cfh ^−/− mouse eyes exhibited thickening of the retina and reduced nuclear density, but relatively normal scotopic and photopic electroretinograms. At 12 months there was evidence of subtle astroglial activation in the Cfh ^−/− eyes, and significant elevation of the complement regulator, decay-accelerating factor (DAF) in Müller cells. In the retinal pigment epithelium (RPE) of young control and Cfh ^−/− animals mitochondria and melanosomes were oriented basally and apically respectively, whereas the apical positioning of melanosomes was significantly perturbed in the mid-age Cfh ^−/− RPE. We conclude that deletion of Cfh in the mouse leads to defects in the retina that precede any marked loss of visual function, but which become progressively more marked as the animals age. These observations are consistent with a lifelong role for CFH in retinal homeostasis.     

Molecular cloning and DNA sequence analysis of the human guanine nucleotide-binding protein Go alpha

The nucleotide sequence of human Go alpha was determined from a partial human brain cDNA clone and the sequence of the first two 5' coding exons of a human genomic Go alpha clone. Comparison of this sequence with bovine and rat Go alpha shows greater than 90% homology at the nucleotide and deduced amino acid level. There is 100% identity at the amino acid level for the cholera and pertussis toxin-catalyzed ADP ribosylation sites, the putative guanine nucleotide binding, and the GTP hydrolysis sites.