A monoclonal antibody to viral glycoprotein blocks virus-immune effector T cells operating at H-2Dd but not at H-2Kd1.

A particular monoclonal antibody that binds to the influenza virus HA molecule inhibits HA-specific thymus-derived lymphocytes mediating cytotoxicity in the context of H-2Dd but not of H-2Kd. Another monoclonal antibody blocks both sets of HA-specific effector T cells. This observation, together with related findings from other laboratories, is considered to support the idea that T cell recognition is directed against some association of viral and H-2 glycoproteins, as proposed in the original formulation of the "altered self" concept.     

Chondrocalcinosis is common in the absence of knee involvement

Introduction

We aimed to describe the distribution of radiographic chondrocalcinosis (CC) and to examine whether metacarpophalangeal joint (MCPJ) calcification and CC at other joints occurs in the absence of knee involvement.

Methods

This was a cross-sectional study embedded in the Genetics of Osteoarthritis and Lifestyle study (GOAL). All participants (n = 3,170) had radiographs of the knees, hands, and pelvis. These were scored for radiographic changes of osteoarthritis (OA), for CC at knees, hips, symphysis pubis, and wrists, and for MCPJ calcification. The prevalence of MCPJ calcification and CC overall, at each joint, and in the presence or absence of knee involvement, was calculated.

Results

The knee was the commonest site of CC, followed by wrists, hips, and symphysis pubis. CC was more likely to be bilateral at knees and wrists but unilateral at hips. MCPJ calcification was usually bilateral, and less common than CC at knees, hips, wrists, and symphysis pubis. Unlike that previously reported, CC commonly occurred without any knee involvement; 44.4% of wrist CC, 45.9% of hip CC, 45.5% of symphysis pubis CC, and 31.3% of MCPJ calcification occurred in patients without knee CC. Those with meniscal or hyaline articular cartilage CC had comparable ages (P = 0.21), and neither preferentially associated with fibrocartilage CC at distant joints.

Conclusions

CC visualized on a plain radiograph commonly occurs at other joints in the absence of radiographic knee CC. Therefore, knee radiographs alone are an insufficient screening test for CC. This has significant implications for clinical practice, for epidemiologic and genetic studies of CC, and for the definition of OA patients with coexistent crystal deposition.     

Multi-Functional Roles of Chitosan as a Potential Protective Agent against Obesity

Chitosan, a natural polysaccharide comprising copolymers of glucosamine and N-acetylglucosamine, has been shown to have anti-obesity properties. Two experiments (Exp. 1 and Exp. 2) were performed to determine the role of chitosan on dietary intake, body weight gain, and fat deposition in a pig model, as well as identifying potential mechanisms underlying the anti-obesity effect of chitosan. In Exp. 1, the nutrient digestibility experiment, 16 pigs (n = 4/treatment) were randomly allocated to one of four dietary treatments as follows: 1) basal diet; 2) basal diet plus 300 ppm chitosan; 3) basal diet plus 600 ppm chitosan; 4) basal diet plus 1200 ppm chitosan. The main observation was that crude fat digestibility was lower in the 1200 ppm chitosan group when compared with the control group (P<0.05). In Exp. 2, a total of 80 pigs (n = 20/treatment) were offered identical dietary treatments to that offered to animals in Exp. 1. Blood samples were collected on day 0, day 35 and at the end of the experiment (day 57). Animals offered diets containing 1200 ppm chitosan had a lower daily dietary intake (P<0.001) and body weight gain (P<0.001) from day 35 to 57 when compared with all the other treatment groups. Animals offered diets containing 1200 ppm chitosan had a significantly lower final body weight (P<0.01) when compared with all the other treatment groups. The decreased dietary intake observed in the 1200 ppm chitosan group was associated with increased serum leptin concentrations (P<0.001) and a decrease in serum C-reactive protein (CRP) concentrations (P<0.05). In conclusion, the results of this study highlight novel endocrine mechanisms involving the modulation of serum leptin and CRP concentrations by which chitosan exhibits anti-obesity properties in vivo.     

Importance of secondary structure for endothelin binding and functional activity.

ET-1[16-Phe] and ET-1[12-Pro] were prepared in order to investigate the importance of secondary structure of ET-1 for receptor binding and function. ET-1[16-Phe] displayed the greatest binding and contractile potency of the ET-analogs tested in rabbit pulmonary artery, rat aorta, and rat left atria. ET-1[12-Pro] also exhibited low nanomolar binding in these tissues but showed less contractile activity than ET-1[16-Phe] or ET-1. The results indicate that the helical region between residues Lys9 and Cys15 of ET-1 is not critical for receptor binding and functional activity. However, replacement of His16 with Phe altered the charge characteristics of the C-terminal region of ET-1 producing the most potent ET-1 analog yet reported.     

Neuronal process outgrowth of human sensory neurons on monolayers of cells transfected with cDNAs for five human N-CAM isoforms

Full length cDNAs for a variety of human N-CAM isoforms have been transfected into mouse L-cells and/or 3T3 cells. Three independent clones of each cell line that were shown to express human N-CAM were tested for their ability to support the morphological differentiation of sensory neurons. The cell surface expression of N-CAM isoforms, linked to the membrane directly by an integral transmembrane spanning domain or indirectly via covalent attachment to a glycosyl-phosphatidylinositol moiety, were consistently found to be associated with a significant increase in the morphological differentiation of both human and rat dorsal root ganglion neurons. Modification of the extracellular structure of both classes of N-CAM, consequent to the expression of a glycosylated 37-amino acid sequence normally found expressed exclusively in muscle N-CAM isoforms did not obviously affect the ability of transfected cells to support increased neuronal differentiation. 3T3 cells that were transfected with a full length cDNA encoding a secreted N-CAM isoform, and that have previously been shown to secrete N-CAM into the growth media rather than link it to the membrane did not significantly differ from control cells in their ability to support neuronal differentiation. These data provide direct evidence for both transmembrane and lipid-linked N-CAM isoforms being components of the regulatory machinery that determines neuronal morphology and process outgrowth.     

Abundance,Condition and Size of a Foundation Species Vary with Altered Soil Conditions,Remnant Type and Potential Competitors

Ecosystems - Native biodiversity often depends on remnant vegetation for survival in agricultural landscapes. However, the size and shape of remnant patches can affect their conservation values...     

Selective inhibition of fibroblast growth factor (FGF)-stimulated mitogenesis by a FGF receptor-1-derived phosphopeptide.

The activated fibroblast growth factor receptor (FGFR)-1 is phosphorylated on five tyrosine residues outside the catalytic site. Although one such residue, Tyr730, is flanked by potential binding sites for phosphotyrosine-interacting molecules, a physiological role for this region is still controversial. We report that a cell-permeant phosphopeptide mimic of this site, FGFR730(p)Y, inhibits FGF-mediated mitogenesis in cells with no effect on responses stimulated by other growth factors. A similar phosphopeptide corresponding to the phospholipase Cgamma binding site on the receptor had no effect on the mitogenic response. The FGFR730(p)Y peptide did not inhibit phosphorylation of p90/FRS2 or Erk, suggesting that it does not act by inhibiting the Erk-kinase cascade. However, the FGFR730(p)Y peptide bound Shc in a manner requiring both phosphorylated tyrosine and a putative PTB domain binding determinant. These data suggest that the peptide might inhibit mitogenesis by competing with the corresponding site on the FGFR for the ability to bind SHC.     

Iron incorporation and post-malaria anaemia

Background

Iron supplementation is employed to treat post-malarial anaemia in environments where iron deficiency is common. Malaria induces an intense inflammatory reaction that stalls reticulo-endothelial macrophagal iron recycling from haemolysed red blood cells and inhibits oral iron absorption, but the magnitude and duration of these effects are unclear.

Methodology/Principal Findings

We examined the red blood cell incorporation of oral administered stable isotopes of iron and compared incorporation between age matched 18 to 36 months old children with either anaemia post-malaria (n = 37) or presumed iron deficiency anaemia alone (n = 36). All children were supplemented for 30 days with 2 mg/kg elemental iron as liquid iron sulphate and administered ⁵⁷Fe and ⁵⁸Fe on days 1 and 15 of supplementation respectively. ⁵⁷Fe and⁵⁸Fe incorporation were significantly reduced (8% vs. 28%: p<0.001 and 14% vs. 26%: p = 0.045) in the malaria vs. non-malaria groups. There was a significantly greater haemoglobin response in the malaria group at both day 15 (p = 0.001) and 30 (p<0.000) with a regression analysis estimated greater change in haemoglobin of 7.2 g/l (s.e. 2.0) and 10.1 g/l (s.e. 2.5) respectively.

Conclusion/Significance

Post-malaria anaemia is associated with a better haemoglobin recovery despite a significant depressant effect on oral iron incorporation which may indicate that early erythropoetic iron need is met by iron recycling rather than oral iron. Supplemental iron administration is of questionable utility within 2 weeks of clinical malaria in children with mild or moderate anaemia.     

Site-specific PEGylation of engineered cysteine analogues of recombinant human granulocyte-macrophage colony-stimulating factor

Granulocyte macrophage colony-stimulating factor (GM-CSF) stimulates proliferation of hematopoietic cells of the macrophage and granulocyte lineages and is used clinically to treat neutropenia and other myeloid disorders. Because of its short circulating half-life, GM-CSF is administered to patients by daily injection. We describe here the engineering of highly potent, long-acting human GM-CSF proteins through site-specific modification of GM-CSF cysteine analogues with a cysteine-reactive poly(ethylene glycol) (PEG) reagent. Thirteen cysteine analogues of GM-CSF were constructed, primarily in nonhelical regions of the protein believed to lie away from the major receptor binding sites. The GM-CSF cysteine analogues were properly processed but insoluble following secretion into the Escherichia coli periplasm. The proteins were refolded and purified by column chromatography. Ten of the cysteine analogues could be modified with a 5-kDa maleimide PEG, and seven of the mono-PEGylated proteins were purified by ion-exchange column chromatography. Biological activities of the 13 cysteine analogues and 7 PEGylated cysteine analogues were comparable to that of wild-type GM-CSF in an in vitro cell proliferation assay using human TF-1 cells. One cysteine analogue was modified with larger 10-, 20-, and 40-kDa PEGs, with only minimal loss of in vitro bioactivity. Pharmacokinetic experiments in rats demonstrated that the PEGylated proteins had up to 47-fold longer circulating half-lives than wild-type GM-CSF. These data demonstrate the utility of site-specific PEGylation for creating highly potent, long-acting GM-CSF analogues and provide further evidence that the nonhelical regions of human GM-CSF examined are largely nonessential for biological activity of the protein.