Alterations of mRNA processing and stability as a pathogenic mechanism in von Willebrand factor quantitative deficiencies.

INTRODUCTION: von Willebrand disease (VWD) is an inherited bleeding disorder due to a deficiency or abnormality of von Willebrand factor (VWF), associated with heterogeneous phenotypes. While VWD mutations acting at the protein level have been deeply investigated, fewer data are available on genetic defects affecting VWF mRNA. AIM: The aim of this study was to characterize the molecular mechanism underlying VWD in three patients. METHODS: Mutational screening of the patients (P1-3) was accomplished by DNA sequencing of all VWF exons and splicing junctions. Platelet mRNA was analyzed by reverse-transcription (RT)-PCR and real-time RT-PCR. RESULTS: P1 is a compound heterozygote for a c.1534-3C>A transversion in intron 13 and for a nonsense mutation (p.Q77X) in exon 4. P2 is heterozygous for a splicing mutation in intron 9 (c.1109+2T>C). RT-PCR assays on the patient's platelet RNA revealed three mRNA populations: (i) wild type; (ii) lacking exon 9; and (iii) lacking exons 8 and 9. P3 showed a novel homozygous splicing mutation in intron 46 (c.7770+1G>T), producing three different mRNA species: (i) retaining the first 25 bp of intron 46; (ii) skipping exon 46; and (iii) skipping exon 46 while retaining 5 bp of intron 45. Whenever possible, the effect of mutations on the levels of VWF transcripts was analyzed, showing that mRNA variants containing a premature termination codon are downregulated, probably by the nonsense-mediated mRNA decay pathway. CONCLUSIONS: The identification of the genetic basis of VWD in three patients confirmed that mutations leading to null alleles in the VWF gene are associated with allele-specific mRNA degradation.

Effect of experimentally induced hypoglycemia and different insulin levels on feelings of hunger in type 1 diabetic patients.

INTRODUCTION: This study investigates the impacts of experimentally induced hypoglycemia and different insulin infusion rates on feelings of hunger. METHODS: Blood glucose and insulin levels were manipulated by hyperinsulinemic glucose clamp technique. Participants were 16 patients with type 1 diabetes (age 36.2+/-11.7 yrs, diabetes duration 9.0+/-6.3 yrs, HbA1c 8.2+/-2.0%). One group (n=8) received moderate, constant insulin infusion (0.8 microU/kg/min), whereas the insulin infusion was doubled in the other group (1.6 microU/kg/min). Blood glucose was lowered stepwise from euglycemia (5.6 mmol/l) to moderate hypoglycemia (2.5 mmol/l). RESULTS: As expected, there was a significant effect of hypoglycemia on feelings of hunger (F (3, 42)=41.7, p<0.01). But during high insulin infusion, feelings of hunger were significantly less intense than during moderate insulin infusion (F (1, 14)=7.2, p=0.02). CONCLUSION: Peripheral insulin levels seem to be associated with the intensity of feelings of hunger.

Fermi surface and quasiparticle excitations of overdoped Tl2Ba2CuO6 + delta.

The high-T(c) superconductor Tl(2)Ba(2)CuO(6 + delta) is studied by angle-resolved photoemission spectroscopy. For a very overdoped T(c) = 30 K sample, the Fermi surface consists of a single large hole pocket centered at (pi, pi) and is approaching a topological transition. Although a superconducting gap with d(x(2)-y(2)) symmetry is tentatively identified, the quasiparticle evolution with momentum and binding energy exhibits a marked departure from the behavior observed in under and optimally doped cuprates. The relevance of these findings to scattering, many-body, and quantum-critical phenomena is discussed.

Serum dependent expression of Enterococcus faecalis adhesins involved in the colonization of heart cells.

Our previous studies have shown that the adhesive ability of Enterococcus faecalis is dependent on the strain and is further modified by growth in serum. The data reported here demonstrate that E. faecalis adherence is mediated by carbohydrate residues present on the bacterial cell surface. Some of these (D-mannose and D-glucose) are expressed by strains isolated from both urinary tract infections (UTI) and endocarditis (EN) when the cells are grown in brain-heart infusion broth (BHIB), and mediate adherence to either urinary tract epithelial cells or the Girardi Heart (GH) cell line. Other residues are present only on EN strains (D-galactose and L-fucose) and mainly mediate adherence to GH cells. These ligands can also be expressed by UTI isolates after growth in serum. D-galactose-bearing adhesins also seem to be involved in internalization of serum grown UTI strains and BHIB or serum grown EN isolates into GH cells.

Role of neuraminidase-dependent adherence in Bacteroides fragilis attachment to human epithelial cells.

Of 50 B. fragilis strains isolated from clinical samples we have demonstrated that 24 (48%) possess an adhesin that mediates a neuraminidase-dependent attachment of B. fragilis to mammalian epithelial cells, but does not mediate any association with human polymorphonuclear leucocytes. This ligand interacts with a mammalian cell receptor that contains a galactoside residue, exposed after neuraminidase pretreatment. Our results suggest a possible role for cell associated neuraminidase in mediating a two step adherence mechanism.

[Recording of cell-mediated immunity in patients with gliomatous brain tumors]. / Zur Erfassung der zellvermittelten Immunität bei Patienten mit gliösen Hirntumoren.

The cell-mediated immunity state by detecting lymphokine in the macrophage electrophoresis mobility test (MEM-test) was supervised in 9 patients with gliomatous cerebral tumors and 12 normal subjects. A positive lymphokine proof was provable by application of 100 micrograms antigen in 8 of 9 patients of the tumor group, however, in the control group in 1 of 12 probands. The MEM-test is a practical improvement of the immunodiagnosis especially for tumors of the nervous system despite the high technical and temporal expense.