Glucocorticoids reduce phobic fear in humans

Phobias are characterized by excessive fear, cued by the presence or anticipation of a fearful situation. Whereas it is well established that glucocorticoids are released in fearful situations, it is not known whether these hormones, in turn, modulate perceived fear. As extensive evidence indicates that elevated glucocorticoid levels impair the retrieval of emotionally arousing information, they might also inhibit retrieval of fear memory associated with phobia and, thereby, reduce phobic fear. Here, we investigated whether acutely administrated glucocorticoids reduced phobic fear in two double-blind, placebo-controlled studies in 40 subjects with social phobia and 20 subjects with spider phobia. In the social phobia study, cortisone (25 mg) administered orally 1 h before a socio-evaluative stressor significantly reduced self-reported fear during the anticipation, exposure, and recovery phase of the stressor. Moreover, the stress-induced release of cortisol in placebo-treated subjects correlated negatively with fear ratings, suggesting that endogenously released cortisol in the context of a phobic situation buffers fear symptoms. In the spider phobia study, repeated oral administration of cortisol (10 mg), but not placebo, 1 h before exposure to a spider photograph induced a progressive reduction of stimulus-induced fear. This effect was maintained when subjects were exposed to the stimulus again 2 days after the last cortisol administration, suggesting that cortisol may also have facilitated the extinction of phobic fear. Cortisol treatment did not reduce general, phobia-unrelated anxiety. In conclusion, the present findings in two distinct types of phobias indicate that glucocorticoid administration reduces phobic fear.

Synergistic inhibition in cell-cell fusion mediated by the matrix and nucleocapsid protein of canine distemper virus

Canine distemper virus (CDV) causes a chronic, demyelinating, progressive or relapsing neurological disease in dogs, because CDV persists in the CNS. Persistence of virulent CDV, such as the A75/17 strain has been reproduced in cell cultures where it is associated with a non-cytolytic infection with very limited cell-cell fusion. This is in sharp contrast to attenuated CDV infection in cell cultures, such as the Onderstepoort (OP) CDV strain, which produces extensive fusion activity and cytolysis. Fusion efficiency may be determined by the structure of the viral fusion protein per se but also by its interaction with other structural proteins of CDV. This was studied by combining genes derived from persistent and non-persistent CDV strains in transient transfection experiments. It was found that fusion efficiency was markedly attenuated by the structure of the fusion protein of the neurovirulent A75/17-CDV. Moreover, we showed that the interaction of the surface glycoproteins with the M protein of the persistent strain greatly influenced fusion activity. Site directed mutagenesis showed that the c-terminus of the M protein is of particular importance in this respect. Interestingly, although the nucleocapsid protein alone did not affect F/H-induced cell-cell fusion, maximal inhibition occurred when the latter was added to combined glycoproteins with matrix protein. Thus, the present study suggests that very limited fusogenicity in virulent CDV infection, which favours persistence by limiting cell destruction involves complex interactions between all viral structural proteins.

Signal peptide and helical bundle domains of virulent canine distemper virus fusion protein restrict fusogenicity

Persistence in canine distemper virus (CDV) infection is correlated with very limited cell-cell fusion and lack of cytolysis induced by the neurovirulent A75/17-CDV compared to that of the cytolytic Onderstepoort vaccine strain. We have previously shown that this difference was at least in part due to the amino acid sequence of the fusion (F) protein (P. Plattet, J. P. Rivals, B. Zuber, J. M. Brunner, A. Zurbriggen, and R. Wittek, Virology 337:312-326, 2005). Here, we investigated the molecular mechanisms of the neurovirulent CDV F protein underlying limited membrane fusion activity. By exchanging the signal peptide between both F CDV strains or replacing it with an exogenous signal peptide, we demonstrated that this domain controlled intracellular and consequently cell surface protein expression, thus indirectly modulating fusogenicity. In addition, by serially passaging a poorly fusogenic virus and selecting a syncytium-forming variant, we identified the mutation L372W as being responsible for this change of phenotype. Intriguingly, residue L372 potentially is located in the helical bundle domain of the F(1) subunit. We showed that this mutation drastically increased fusion activity of F proteins of both CDV strains in a signal peptide-independent manner. Due to its unique structure even among morbilliviruses, our findings with respect to the signal peptide are likely to be specifically relevant to CDV, whereas the results related to the helical bundle add new insights to our growing understanding of this class of F proteins. We conclude that different mechanisms involving multiple domains of the neurovirulent A75/17-CDV F protein act in concert to limit fusion activity, preventing lysis of infected cells, which ultimately may favor viral persistence.

Sendai virus RNA polymerase scanning for mRNA start sites at gene junctions

Mini-genomes expressing two reporter genes and a variable gene junction were used to study Sendai virus RNA polymerase (RdRp) scanning for the mRNA start signal of the downstream gene (gs2). We found that RdRp could scan the template efficiently as long as the initiating uridylate of gs2 (3' UCCCnnUUUC) was preceded by the conserved intergenic region (3' GAA) and the last 3 uridylates of the upstream gene end signal (ge1; 3' AUUCUUUUU). The end of the leader sequence (3' CUAAAA, which precedes gs1) could also be used for gene2 expression, but this sequence was considerably less efficient. Increasing the distance between ge1 and gs2 (up to 200 nt) led to the progressive loss of gene2 expression, in which half of gene2 expression was lost for each 70 nucleotides of intervening sequence. Beyond 200 nt, gene2 expression was lost more slowly. Our results suggest that there may be two populations of RdRp that scan at gene junctions, which can be distinguished by the efficiency with which they can scan the genome template for gs.

Treatment of newly diagnosed acute promyelocytic leukemia (APL): a comparison of French-Belgian-Swiss and PETHEMA results

All-trans retinoic acid (ATRA) plus anthracycline chemotherapy is the reference treatment of newly diagnosed acute promyelocytic leukemia (APL), whereas the role of cytosine arabinoside (AraC) remains disputed. We performed a joint analysis of patients younger than 65 years included in Programa para el Estudio de la Terapéutica en Hemopatía Maligna (PETHEMA) LPA 99 trial, where patients received no AraC in addition to ATRA, high cumulative dose idarubicin, and mitoxantrone, and APL 2000 trial, where patients received AraC in addition to ATRA and lower cumulative dose daunorubicin. In patients with white blood cell (WBC) count less than 10 x 10(9)/L, complete remission (CR) rates were similar, but 3-year cumulative incidence of relapse (CIR) was significantly lower in LPA 99 trial: 4.2% versus 14.3% (P = .03), although 3-year survival was similar in both trials. This suggested that AraC is not required in APL with WBC count less than 10 x 10(9)/L, at least in trials with high-dose anthracycline and maintenance treatment. In patients with WBC of 10 x 10(9)/L or more, however, the CR rate (95.1% vs 83.6% P = .018) and 3-year survival (91.5% vs 80.8%, P = .026) were significantly higher in APL 2000 trial, and there was a trend for lower 3-year CIR (9.9% vs 18.5%, P = .12), suggesting a beneficial role for AraC in those patients.

A case of necrotizing fasciitis with septic shock in a cat caused by Acinetobacter baumannii

A 4-year-old, neutered female, domestic shorthair cat admitted to the animal hospital for recurrent constipation presumed to be due to post-traumatic injuries, went into shock with signs including fever and ataxia followed by stupor. On the fifth day of hospitalization, the cat developed severe, diffuse oedema of the ventral abdomen with multifocal to coalescing erythematous areas and small vesicle formation. The results of bacteriological cultures of liver, spleen and kidney specimens led to the diagnosis of Acinetobacter baumannii sepsis. Histopathological findings of skin samples taken during necropsy showed an extensive epidermal and dermal necrosis with septic vasculitis and numerous intralesional gram-negative bacteria. Detection of the bla(OXA-51-like) gene specific for A. baumannii by PCR, performed retrospectively on samples of the deep layers of the skin, confirmed the presence of A. baumannii also in the cutaneous lesions. To our knowledge this is the first report of a necrotizing fasciitis with septic shock in a cat caused by A. baumannii.

Ezrin/moesin in motile Walker 256 carcinosarcoma cells: signal-dependent relocalization and role in migration

Rat Walker 256 carcinosarcoma cells spontaneously develop front-tail polarity and migrate in the absence of added stimuli. Constitutive activation of phosphatidylinositol-3 kinase (PI 3-kinase), Rac, Rho and Rho kinase are essential for these processes. Ezrin and moesin are putative targets of these signaling pathways leading to spontaneous migration. To test this hypothesis, we used specific siRNA probes that resulted in a downregulation of ezrin and moesin by about 70% and in a similar reduction in the fraction of migrating cells. Spontaneous polarization however was not affected, indicating a more subtle role of ezrin and moesin in migration. We provide furthermore evidence that endogenous ezrin and moesin colocalize with F-actin at the contracted tail of polarized cells, similar to ectopically expressed green fluorescent protein-tagged ezrin. Our results suggest that myosin light chain and ezrin are markers of front and tail, respectively, even in the absence of morphological polarization. We further show that endogenous ezrin and moesin are phosphorylated and that activities of PI-3 kinase, Rho and Rac, but not of Rho-kinase, are required for this C-terminal phosphorylation. Activation of protein kinase C in contrast suppressed phosphorylation of ezrin and moesin. Inhibition of ezrin phosphorylation prevented its membrane association.

Activation of non-ischemic, hypoxia-inducible signalling pathways up-regulate cytoprotective genes in the murine liver

BACKGROUND/AIMS: We investigated the molecular response of a non-ischemic hypoxic stress in the liver, in particular, to distinguish its hepatoprotective potential. METHODS: The livers of mice were subjected to non-ischemic hypoxia by clamping the hepatic-artery (HA) for 2h while maintaining portal circulation. Hypoxia was defined by a decrease in oxygen saturation, the activation of hypoxia-inducible factor (HIF)-1 and the mRNA up-regulation of responsive genes. To demonstrate that the molecular response to hypoxia may in part be hepatoprotective, pre-conditioned animals were injected with an antibody against Fas (Jo2) to induce acute liver failure. Hepatocyte apoptosis was monitored by caspase-3 activity, cleavage of lamin A and animal survival. RESULTS: Clamping the HA induced a hypoxic stress in the liver in the absence of severe metabolic distress or tissue damage. The hypoxic stimulus was sufficient to activate the HIF-1 signalling pathway and up-regulate hepatoprotective genes. Pre-conditioning the liver with hypoxia was able to delay the onset of Fas-mediated apoptosis and prolong animal survival. CONCLUSIONS: Our data reveal that hepatic cells can sense and respond to a decrease in tissue oxygenation, and furthermore, that activation of hypoxia-inducible signalling pathways function in part to promote liver cell survival.

Effects of non-ionic iodinated contrast media on patient heart rate and pressures during intra-cardiac or intra-arterial injection

PURPOSE: To compare the effects on heart rate (HR), on left ventricular (LV) or arterial pressures, and the general safety of a non-ionic low-osmolar contrast medium (CM) and a non-ionic iso-osmolar CM in patients undergoing cardiac angiography (CA) or peripheral intra-arterial digital subtraction angiography (IA-DSA). MATERIALS AND METHODS: Two double-blind, randomized studies were conducted in 216 patients who underwent CA (n=120) or peripheral IA-DSA (n=96). Patients referred for CA received a low-osmolar monomeric CM (iomeprol-350, n=60) or an iso-osmolar dimeric CM (iodixanol-320; n=60). HR and LV peak systolic and end-diastolic pressures were determined before and after the first injection during left and right coronary arteriography and left ventriculography. Monitoring for all types of adverse event (AE) was performed for 24 h following the procedure. t-tests were performed to compare CM for effects on HR. Patients referred for IA-DSA received iomeprol-300 (n=49) or iodixanol-320 (n=47). HR and arterial blood pressure (BP) were evaluated before and after the first 4 injections. Monitoring for AE was performed for 4 h following the procedure. Repeated-measures ANOVA was used to compare mean HR changes across the first 4 injections, whereas changes after the first injection were compared using t-tests. RESULTS: No significant differences were noted between iomeprol and iodixanol in terms of mean changes in HR during left coronary arteriography (p=0.8), right coronary arteriography (p=0.9), and left ventriculography (p=0.8). In patients undergoing IA-DSA, no differences between CM were noted for effects on mean HR after the first injection (p=0.6) or across the first 4 injections (p=0.2). No significant differences (p>0.05) were noted in terms of effects on arterial BP in either study or on LV pressures in patients undergoing CA. Non-serious AE considered possibly CM-related (primarily headache and events affecting the cardiovascular and digestive systems) were reported more frequently by patients undergoing CA and more frequently after iodixanol (14/60 [23.3%] and 2/47 [4.3%]; CA and IA-DSA, respectively) than iomeprol (10/60 [16.7%] and 1/49 [2%], respectively). CONCLUSIONS: Iomeprol and iodixanol are safe and have equally negligible effects on HR and LV pressures or arterial BP during and after selective intra-cardiac injection and peripheral IA-DSA. CLINICAL APPLICATION: Iomeprol and iodixanol are safe and equally well tolerated with regard to cardiac rhythm and clinical preference should be based on diagnostic image quality alone.

Perinatal adaptation in mammals: the impact of metabolic rate

Mammalian birth is accompanied by profound changes in metabolic rate that can be described in terms of body size relationship (Kleiber's rule). Whereas the fetus, probably as an adaptation to the low intrauterine pO2, exhibits an "inappropriately" low, adult-like specific metabolic rate, the term neonate undergoes a rapid metabolic increase up to the level to be expected from body size. A similar, albeit slowed, "switching-on" of metabolic size allometry is found in human preterm neonates whereas animals that are normally born in a very immature state are able to retard or even suppress the postnatal metabolic increase in favor of weight gain and O2 supply. Moreover, small immature mammalian neonates exhibit a temporary oxyconforming behavior which enhances their hypoxia tolerance, yet is lost to the extent by which the size-adjusted metabolic rate is "locked" by increasing mitochondrial density. Beyond the perinatal period, there are no other deviations from metabolic size allometry among mammals except in hibernation where the temporary "switching-off" of Kleiber's rule is accompanied by a deep reduction in tissue pO2. This gives support to the hypothesis that the postnatal metabolic increase represents an "escape from oxygen" similar to the evolutionary roots of mitochondrial respiration, and that the overall increase in specific metabolic rate with decreasing size might contribute to prevent tissues from O2 toxicity.

The metastatic T-cell hybridoma antigen/P-selectin glycoprotein ligand 1 is required for hematogenous metastasis of lymphomas

Using variants of the murine BW5147 lymphoma cell-line, we have previously identified 3 monoclonal antibodies (MAbs) that discriminate between metastatic and nonmetastatic BW5147-derived T-cell hybridomas and lymphomas, as well as BW5147-unrelated T-lymphomas. These MAbs were reported to recognize an identical membrane-associated sialoglycoprotein, termed "metastatic T-cell hybridoma antigen" (MTH-Ag). Here, we document that the expression pattern of the MTH-Ag on metastatic and nonmetastatic BW5147 variants correlates with that of the P-selectin glycoprotein ligand 1 (PSGL-1), a sialomucin involved in leukocyte recruitment to sites of inflammation. Moreover, the MAbs against the MTH-Ag recognize PSGL-1 when it is transfected in MTH-Ag-negative BW5147 variants, suggesting that the MTH-Ag is PSGL-1. Overexpression of MTH-Ag/PSGL-1 in MTH-Ag-negative BW5147 variants did not affect their in vivo malignancy. Yet, down-regulation of MTH-Ag/PSGL-1 expression on metastatic, MTH-Ag-positive BW5147 variants, using an RNA interference (RNAi) approach, resulted, in a dose-dependent manner, in a significant reduction of liver and spleen colonization and a delay in mortality of the recipient mice upon intravenous inoculation. Collectively, these results demonstrate that, although MTH-Ag/PSGL-1 overexpression alone may not be sufficient for successful dissemination and organ colonization, MTH-Ag/PSGL-1 plays a critical role in hematogenous metastasis of lymphoid cancer cells.

Benign paroxysmal positional vertigo in mountain bikers

We evaluated 4 men who had benign paroxysmal positional vertigo (BPPV) that occured several hours after intensive mountain biking but without head trauma. The positional maneuvers in the planes of the posterior and horizontal canals elicited BPPV, as well as transitory nystagmus. This was attributed to both the posterior and horizontal semicircular canals (SCCs) on the left side in 1 patient, in these 2 SCCs on the right side in another patient, and to the right posterior SCC in the other 2 patients. The symptoms disappeared after physiotherapeutic maneuvers in 2 patients and spontaneously in the other 2 patients. Cross-country or downhill mountain biking generates frequent vibratory impacts, which are only partially filtered through the suspension fork and the upper parts of the body. Biomechanically, during a moderate jump, before landing, the head is subjected to an acceleration close to negative 1 g, and during impact it is subjected to an upward acceleration of more than 2g. Repeated acceleration-deceleration events during intensive off-road biking might generate displacement and/or dislocation of otoconia from the otolithic organs, inducing the typical symptoms of BPPV. This new cause of posttraumatic BPPV should be considered as an injury of minor severity attributed to the practice of mountain biking.