Human embryonic stem cells rapidly take up and then clear exogenous human and animal prions in vitro

Susceptibility to prion infection involves interplay between the prion strain and host genetics, but expression of the host-encoded cellular prion protein is a known prerequisite. Here we consider human embryonic stem cell (hESC) susceptibility by characterizing the genetics and expression of the normal cellular prion protein and by examining their response to acute prion exposure. Seven hESC lines were tested for their prion protein gene codon 129 genotype and this was found to broadly reflect that of the normal population. hESCs expressed prion protein mRNA, but only low levels of prion protein accumulated in self-renewing populations. Following undirected differentiation, up-regulation of prion protein expression occurred in each of the major embryonic lineages. Self-renewing populations of hESCs were challenged with infectious human and animal prions. The exposed cells rapidly and extensively took up this material, but when the infectious source was removed the level and extent of intracellular disease-associated prion protein fell rapidly. In the absence of a sufficiently sensitive test for prions to screen therapeutic cells, and given the continued use of poorly characterized human and animal bioproducts during hESC derivation and cultivation, the finding that hESCs rapidly take up and process abnormal prion protein is provocative and merits further investigation.     

Unapparent microsporidial infection among immunocompetent humans in the Czech Republic

In the present population-based study, we determined the prevalences of the most common human-pathogenic microsporidia, Encephalitozoon spp. and Enterocytozoon bieneusi, in asymptomatic healthy people living in the Czech Republic. A total of 382 males and females (ages, 1 to 84 years) living in the Czech Republic, of whom 265 were Czech nationals and 117 were foreign students, were included in a study testing for the presence of microsporidia by use of coprology and molecular methods. Single-species infections with Enterocytozoon bieneusi or an Encephalitozoon sp. were detected for 9 and 136 individuals, respectively. Moreover, coinfections were detected for 14 individuals. Four genotypes of 3 human-pathogenic Encephalitozoon spp. and 7 E. bieneusi genotypes, including 3 novel genotypes, were detected. Some of these were reported in humans for the first time. The highest prevalence was recorded for individuals older than 50 years and for loose, unformed stool samples. These findings clearly show that exposure to microsporidia is common among immunocompetent people and that microsporidiosis is not linked to any clinical manifestation in healthy populations.     

Fibronectin attenuates process outgrowth in oligodendrocytes by mislocalizing MMP-9 activity

The extension of multiple oligodendroglial branched processes towards axons is an important event during the early stages of myelination that likely requires remodeling of the extracellular matrix (ECM) microenvironment via matrix metalloproteinases (MMPs). Here we investigated whether fibronectin-mediated inhibition of myelin sheet formation in oligodendrocytes correlated with an altered MMP activity. Our data reveal that fibronectin enhanced, in a PKC-dependent manner, the net activity of MMP-9, but not its expression, in conditioned medium of oligodendrocytes. Residual cellular MMP-9 activity on fibronectin was confined to the cell body, whereas MMP-9 activity on laminin-2 was localized along extending processes of oligodendrocytes. The mislocalization of MMP-9 activity on fibronectin correlated with a perturbed outgrowth of oligodendroglial processes. In conclusion, our findings suggest that ECM molecules influence both the net activity of secreted MMP and the spatial distribution of cell-associated MMP activity, and thereby morphological oligodendrocyte differentiation.     

Vascular pathology in patients with idiopathic Parkinson's disease

To study the impact of brain vessel pathology on the clinical status of Parkinson's disease (PD), in 57 consecutive patients the clinical and neuropsychological data were compared with clinical MRI signs of vascular impairment and with the ultrasound brain vessel investigations. There was a significant correlation between clinical and cognitive status and intimomedial thickness, which is an indicator of large vessel impairment. Cognitive status was significantly related to the pulsatility index (an indicator of small vessel impairment). This study provides evidence that subclinical vascular pathology could influence the clinical status by contributing to motor and cognitive dysfunction in PD.     

Effect of an NK1/NK2 receptor antagonist on airway responses and inflammation to allergen in asthma

RATIONALE: The tachykinins substance P and neurokinin A (NKA) are implicated in the pathophysiology of asthma. Objective: We tested the safety, tolerability, and pharmacologic and biological efficacy of a tachykinin NK(1)/NK(2) receptor antagonist, AVE5883, in patients with asthma in two double-blind, placebo-controlled crossover studies. METHODS: The pharmacologic efficacy of a single inhaled dose (4.8 mg) of AVE5883 was tested against inhaled NKA in 20 patients with asthma. Subsequently, we studied the biological efficacy of the pharmacologically effective dose on inhaled allergen in a multiple-dose trial (4.8 mg three times per day, 9 d) in 12 patients with asthma with dual responses to inhaled house dust mite. On Day 8, an allergen challenge was conducted, and airway response was measured by FEV(1) until 9 hours postallergen. Exhaled NO, provocative concentration of methacholine bromide causing a 20% fall in FEV(1), and induced sputum were performed on Days 1, 7, and 9. RESULTS: AVE5883 had a bad taste, and transient bronchospasm occurred in some subjects. A single inhaled dose shifted the dose response to NKA by 1.2 doubling doses. Pretreatment with multiple doses of AVE5883 enhanced the allergen-induced early and late airway responses. There were no significant differences in the allergen-induced changes in exhaled NO, provocative concentration of methacholine bromide causing a 20% fall in FEV(1), and sputum cell differentials between placebo and AVE5883. CONCLUSIONS: Despite its demonstrated pharmacologic activity against inhaled NKA, multiple doses of AVE5883 increased the allergen-induced airway responses without affecting markers of airway hyperresponsiveness and airway inflammation. Our data question the prominent role of neurogenic inflammation in asthma and, consequently, the therapeutic potential of dual tachykinin antagonists.     

Novel mutations in the NF1 gene in Czech patients with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is one of the most common inherited human disorders, with an estimated incidence of 1 per 3500 births. In most cases, the disease is caused either by mutation in the NF1 gene, or by a particular or complete deletion of the NF1 gene. The NF1 gene exhibits one of the highest mutation rates of any human disorder. In this experimental study of the NF1 gene, we screened the mutational spectrum of 22 unrelated patients from the Czech Republic using the denaturing high-performance liquid chromatography (DHPLC) and multiplex ligation-dependent probe amplification (MLPA) methods. We found NF1 mutations in 17 patients: 15 causal mutations were detected with the use of the DHPLC method (15/20, 75%). With the MPLA method, we also confirmed and specified two large deletions that were previously genotyped by microsatellite markers. Twelve of the above-mentioned mutations were newly found: c.1_2delATinsCC, c.1185+1G>C, c.1757_1760delCTAG, c.1642-7A>G, c.2329 T>G, c.2816delA, c.3738_3741delGTTT, c.4733 C>T, c.5220delT, c.6473_6474insGAAG, ex14_49del, ex28_49del. We present this study as a first effectual step in the routine diagnosis of the NF1 in patients from the Czech Republic.     

Immune response of mice with alveolar echinococcosis to therapy with transfer factor, alone and in combination with albendazole

The effect of dialysable leucocyte extract (transfer factor TF) on immune response of mice infected with Echinococcus multilocularis and treated with albendazole (ABZ) was observed. TF administration increased the parasite-suppressed proliferative response of T and B lymphocytes of infected mice from weeks 8 to 12 or 14 post infection (p.i.), respectively, with the most stimulative effect after TF+ABZ therapy. The CD4 T cell presence in the spleen of infected mice with TF or TF+ABZ therapy was increased from weeks 6 to 12 or 14 p.i., respectively. The production of IFN-γ (Th1 cytokine) after TF or TF+ABZ therapy was significantly higher from weeks 6 to 12 p.i., and during this time, the significantly inhibited IL-5 synthesis (Th2 cytokine) was detected, particularly after TF+ABZ therapy. The superoxide anion (O₂⁻) production in peritoneal macrophages of infected mice treated with TF or TF+ABZ was stimulated from weeks 8 to 18 p.i. The immunomodulative effect of TF reduced the growth of larval cysts till week 14 p.i. with a comparable intensity to the anthelmintic drug ABZ. Combined therapy TF+ABZ resulted in the greatest parasite restriction and reduced the cyst development till the end of the experiment.     

507 A Novel Mechanism of Fas Signaling Suppression by PMLRARα in Acute Promyelocytic Leukemia

Presence of potential inhibitors of Fas could block Fas signaling and explain cancer cells resistance to apoptosis. In this study, we found that PMLRARα binds to Fas and blocks Fas-mediated apoptosis through recruiting c-FLIP in APL. Targeting tissue-specific inhibitors of Fas such as PMLRARα would improve cancer therapy.

Full Abstract

Fas plays a critical role in cell proliferation and in the selective killing of autoreactive lymphocytes and abnormal cells, including infected cells. To explain the common expression of Fas and the resistance to the Fas-induced apoptosis observed in some normal and cancer cells, we have screened cells for potential regulators of the Fas death receptor. By using mass spectrometry analysis of Fas-associated proteins, we identified peptides derived from promyelocytic leukemia (PML).PML enhances