Antibody response to B19 parvovirus VP1 and VP2 linear epitopes in patients with haemophilic arthritis

Parvovirus B19 infection occurs very frequently in patients with haemophilia on account of its transmission with plasma derivatives. In order to achieve a more defined serological pattern for the study of the role of B19 infection in haemophilic arthritis, 53 serum samples from 37 patients with haemophilic arthritis were investigated for the presence of IgG immune response against B19 VP2 and VP1 linear epitopes and VP2 conformational antigen compared to the serological reactivity against B19 NS1 and to the presence of B19 DNA in the synovial membranes. An IgG immune response against VP1 and VP2 linear epitopes was detected by immunoblot assay using recombinant proteins expressed in Escherichia coli. Specific IgG against VP2 and VP1 linear epitopes were present in 84.90 and 92.45% of haemophilic arthritis patients and in 28.0 and 64.0% of the controls (P<0.001) respectively. All 53 sera of the haemophiliacs (100%) and 66.0% of the controls (P<0.001) were IgG positive and IgM negative against VP2 structural epitopes. Specific IgG against VP2 linear epitopes, which are a serological marker of active or very recent B19 infection, proved to be significantly associated with the presence of anti-NS1 antibodies and with the presence of B19 DNA in synovial tissue in patients with haemophilic arthritis. In conclusion, in these patients the presence of B19 IgG anti-VP2 linear epitopes, in absence of IgM anti-VP2 structural antigens, can be a useful serological marker to diagnose active, recent or persistent B19 infection.

The draft genome of Ciona intestinalis: insights into chordate and vertebrate origins

The first chordates appear in the fossil record at the time of the Cambrian explosion, nearly 550 million years ago. The modern ascidian tadpole represents a plausible approximation to these ancestral chordates. To illuminate the origins of chordate and vertebrates, we generated a draft of the protein-coding portion of the genome of the most studied ascidian, Ciona intestinalis. The Ciona genome contains approximately 16,000 protein-coding genes, similar to the number in other invertebrates, but only half that found in vertebrates. Vertebrate gene families are typically found in simplified form in Ciona, suggesting that ascidians contain the basic ancestral complement of genes involved in cell signaling and development. The ascidian genome has also acquired a number of lineage-specific innovations, including a group of genes engaged in cellulose metabolism that are related to those in bacteria and fungi.

Evidence that suppression of insulin secretion by insulin itself is neurally mediated

We examined the mechanism by which an increase in blood insulin concentration inhibits insulin secretion by the pancreas. To this end, we determined plasma C-peptide concentrations during euglycemic-hyperinsulinemic (approximately 500 pmol/L) clamps in five patients with insulin-dependent diabetes mellitus (IDDM) after combined pancreas and kidney (P/K) transplantation, in five nondiabetic patients after kidney transplantation (K), and in six normal control subjects. Hyperinsulinemia decreased C-peptide concentrations in K patients (by 60%, P < .01) and controls (by 35%, P < .05), but not in P/K patients (653 +/- 115 v 702 +/- 197 pmol/L before and after 4 hours of hyperinsulinemia, respectively). The main difference between K patients and controls and P/K patients was that the pancreas in K patients and controls was innervated, whereas the transplanted pancreas of K/P patients was denervated. The data therefore suggested that the inhibition of pancreatic insulin secretion by hyperinsulinemia was neurally mediated.

Glucose metabolism and leg blood flow after pancreas/kidney transplantation

Patients with insulin-dependent diabetes mellitus (IDDM) who have undergone combined pancreas and kidney (P/K) transplantation, are hyperinsulinemic and have impaired insulin-stimulated whole body glucose uptake. We have investigated whether their reduced glucose uptake was due to insulin resistance at the tissue level or was caused by reduced muscle blood flow, previously reported to be present in patients with IDDM. Leg blood flow (LBF, determined with mercury strain-gauge plethysmography), glucose uptake (GRd, determined with 6,6 D2-glucose), and glucose oxidation (Gox, determined by indirect calorimetry) were obtained during euglycemic-hyperinsulinemic (approximately 500 pM) clamping in five P/K patients, five kidney transplant (K) patients, and six controls. Insulin-stimulated GRd was reduced in P/K patients compared to controls (23 +/- 4 vs. 44 +/- 6 mumol/kg/min, P < 0.05); Gox was comparable but glucose storage was reduced in P/K and K patients compared to controls (9 +/- 3 and 13 +/- 4 vs. 28 +/- 7 mumol/kg/min, P < 0.05). Basal LBF (3.9 +/- 0.3, 4.6 +/- 0.9, and 4.9 +/- 0.6 mL/dL leg tissue/min) and insulin-stimulated LBF (5.6 +/- 0.6, 6.1 +/- 1.1 and 6.1 +/- 0.9 mL/dL leg tissue/min) were similar in P/K, K patients, and controls. We concluded, that P/K patients had normal muscle blood flow but were insulin resistant at the tissue level, and that the insulin resistance was responsible, at least in part, for their hyperinsulinemia.

N-linked oligosaccharide changes with oncogenic transformation require sialylation of multiantennae

Glycopeptides derived from NIH 3T3 fibroblasts and these cells transformed by transfection with human DNA containing oncogene H-ras were analyzed by 500-MHz 1H-NMR spectroscopy and binding to immobilized lectins. The cells were metabolically labeled with D-[3H]glucosamine or L-[3H]fucose and the glycopeptides included in Bio-Gel P-10 (Mr 5000-3500) were separated into neutral and charged fractions on DEAE-cellulose. The major portion (80%) of these [3H]fucose glycopeptides from the non-transformed NIH 3T3 fibroblasts were neutral or contained one or two charged residues, whereas 90% of the glycopeptides from the transformed cells contained two or more charged residues. The structure of the predominant neutral glycopeptide from the non-transformed NIH 3T3 cells was determined by 1H-NMR spectroscopy to be tetraantennary containing terminal Gal alpha 1----3. (formula; see text) This structure was verified by binding to the immobilized alpha-Gal-specific lectin, Griffonia simplicifolia I and leukoagglutinating phytohemagglutinin from Phaseolus vulgaris (L-PHA), which binds certain tri- or tetraantennary glycopeptides. In contrast, the structure derived by NMR spectroscopy of one of the predominant charged glycopeptides from the transformed cells was triantennary containing terminal NeuNAc alpha 2----3 in addition to Gal alpha 1----3. (formula; see text) In attempting to verify this structure by lectin-binding properties it was found that removal of NeuNAc alpha 2----3 reduced the affinity to L-PHA - agarose. The other major glycopeptides of the transformed cells which were more charged also cotained NeuNAc alpha 2----3 but no NeuNAc alpha 2----6 or Gal alpha 1----3. A tentative structure was proposed for the major glycopeptide of the first charged class from NIH 3T3 cells on the basis of lectin-binding properties and the NMR spectrum which showed, in addition to NeuNAc alpha 2----3, the presence of NeuNAc alpha 2----6 and Gal alpha 1----3. On the basis of the NMR spectrum and other results, it is concluded that the presence of tetraantennary oligosaccharides are not sufficient for the transformed oligosaccharide phenotype. Rather, the tri- or tetraantennae must be sialylated in alpha 2----3 linkage, on more than one antennae, when properties of transformation are expressed in NIH 3T3 cells. Prior to transformation the tetraantennary oligosaccharides of these cells are terminated in alpha-Gal residues, whereas after transformation alpha-Gal residues appear to be replaced by NeuNAc alpha 2----3.(ABSTRACT TRUNCATED AT 400 WORDS)

NIH 3T3 cells transfected with human tumor DNA lose the transformed phenotype when treated with swainsonine

Phenotypic expression of transformation was inhibited by swainsonine at concentrations which affect the late stages of glycoprotein processing but not growth of cells. In the presence of swainsonine, NIH 3T3 fibroblasts transfected with human tumor DNA (al-l) no longer grew in soft agar or expressed complex type oligosaccharides characteristic of transformed cells. Thus, it appears that glycoproteins with fully processed oligosaccharides are necessary for the maintenance of the transformed phenotype in these cells.