Abnormal interactions of calsequestrin with the ryanodine receptor calcium release channel complex linked to exercise-induced sudden cardiac death

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a familial arrhythmogenic disorder associated with mutations in the cardiac ryanodine receptor (RyR2) and cardiac calsequestrin (CASQ2) genes. Previous in vitro studies suggested that RyR2 and CASQ2 interact as parts of a multimolecular Ca(2+)-signaling complex; however, direct evidence for such interactions and their potential significance to myocardial function remain to be determined. We identified a novel CASQ2 mutation in a young female with a structurally normal heart and unexplained syncopal episodes. This mutation results in the nonconservative substitution of glutamine for arginine at amino acid 33 of CASQ2 (R33Q). Adenoviral-mediated expression of CASQ2(R33Q) in adult rat myocytes led to an increase in excitation-contraction coupling gain and to more frequent occurrences of spontaneous propagating (Ca2+ waves) and local Ca2+ signals (sparks) with respect to control cells expressing wild-type CASQ2 (CASQ2WT). As revealed by a Ca2+ indicator entrapped inside the sarcoplasmic reticulum (SR) of permeabilized myocytes, the increased occurrence of spontaneous Ca2+ sparks and waves was associated with a dramatic decrease in intra-SR [Ca2+]. Recombinant CASQ2WT and CASQ2R33Q exhibited similar Ca(2+)-binding capacities in vitro; however, the mutant protein lacked the ability of its WT counterpart to inhibit RyR2 activity at low luminal [Ca2+] in planar lipid bilayers. We conclude that the R33Q mutation disrupts interactions of CASQ2 with the RyR2 channel complex and impairs regulation of RyR2 by luminal Ca2+. These results show that intracellular Ca2+ cycling in normal heart relies on an intricate interplay of CASQ2 with the proteins of the RyR2 channel complex and that disruption of these interactions can lead to cardiac arrhythmia.     

Role of corticotropin-releasing hormone as a thyrotropin-releasing factor in non-mammalian vertebrates

The finding that thyrotropin-releasing hormone does not always act as a thyrotropin (TSH)-releasing factor in non-mammalian vertebrates has led researchers to believe that another hypothalamic factor may exhibit this function. In representatives of all non-mammalian vertebrate classes, corticotropin-releasing hormone (CRH) appears to be a potent stimulator of hypophyseal TSH secretion, and might therefore function as a common regulator of both the thyroidal and adrenal/interrenal axes. CRH exerts its dual hypophysiotropic action through two different types of CRH receptors. Thyrotropes express type 2 CRH receptors, while CRH-induced corticotropin (ACTH) secretion is mediated by type 1 CRH receptors on the corticotropic pituitary cells. The stimulating effect of CRH on both TSH and ACTH release has profound consequences for the peripheral action of both hormonal axes. The simultaneous stimulation of the thyroidal and adrenal/interrenal axes by CRH, possibly fine-tuned by differential regulation of the expression of the different CRH receptor isoforms, provides a potential mechanism for developmental plasticity.     

General practitioners' fear-avoidance beliefs influence their management of patients with low back pain

The objectives of this cross-sectional study conducted in primary care practice in France were to describe general practitioners' (GPs) fear-avoidance beliefs about low back pain (LBP), investigate the impact of these beliefs on their following guidelines for bed rest, physical activities, and sick leave, and uncover factors associated with GPs' fear-avoidance beliefs. A total of 864 GPs completed a 5-part self-administered questionnaire. Parts 1, 2, and 3 concerned demographic, professional data, and personal history of back pain, respectively. Part 4 dealt with GPs' education about LBP and practice for LBP. Part 5 assessed GPs' fear-avoidance beliefs on the Fear-Avoidance Beliefs Questionnaire (FABQ). GPs' mean age was 48.2+/-7.0 years, 80% were male, 88% had been practicing for more than 10 years, and 52% reported a previous personal episode of acute LBP. Forty-six percent had participated in an educational session on LBP during the last 3 years. Mean scores for the FABQ Phys and Work were 9.6+/-4.8 and 17.5+/-6.7, respectively. Sixteen percent of participants had high rating on the FABQ Phys (FABQ Phys score>14). FABQ Phys score was associated with recommendation of bed rest or rest during sick leave (p<0.0001) for acute LBP and less advice to maintain maximum bearable physical activities (p<0.001) for chronic LBP. FABQ Work score was associated with prescribing sick leave during painful periods (p<0.005) for acute LBP and less advice to maintain maximum bearable physical activities (p<0.001) for chronic LBP. GPs' fear-avoidance beliefs about LBP negatively influence their following guidelines concerning physical and occupational activities for patients with LBP.     

Procalcitonin kinetics in the prognosis of severe community-acquired pneumonia

Objectives Procalcitonin (PCT) kinetics is a good prognosis marker in infectious diseases, but few studies of community-acquired pneumonia (CAP) have been performed in intensive care units (ICU). We analyzed the relationship between PCT kinetics and outcome in ICU patients with severe CAP. Design and setting Prospective observational study in a 16-bed university hospital ICU. Patients 100 critically ill patients with community-acquired pneumonia. Measurements and results Median PCT was 5.2 ng/ml on day 1 and 2.9 ng/ml on day 3. It increased from day 1 to day 3 in nonsurvivors but decreased in survivors. In multivariate analysis four variables were associated with death: invasive ventilation (odds ratio 10−), multilobar involvement (5.6−), LOD score (6.9−), and PCT increase from day 1 to day 3 (4.5−). In intubated patients with a PCT level below 0.95 ng/ml on day 3 the survival rate was 95%. Conclusion Increased PCT from day 1 to day 3 in severe CAP is a poor prognosis factor. A PCT level less than 0.95 ng/ml on day 3 in intubated patients is associated with a favorable outcome. Electronic supplementary material The electronic reference of this article is . The online full-text version of this article includes electronic supplementary material. This material is available to authorised users and can be accessed by means of the ESM button beneath the abstract or in the structured full-text article. To cite or link to this article you can use the above reference.     

Direct comparison of placebo effects on clinical and experimental pain

OBJECTIVES: Placebo effects have been suggested to be more potent on clinical than experimental pain. However, this proposition is based on the comparison of the magnitude of placebo analgesia between studies using different methodologies or between different groups of subjects within the same study. The authors sought to provide a more direct test of this hypothesis using a within-subject design and to investigate the potential mediating effect of expectancy. METHOD: Sixteen patients with low back pain rated the intensity and the unpleasantness of their clinical pain and underwent two cold pressor tests, both before and after a saline injection presented either as a potent painkiller (placebo treatment) in one session or as an inactive substance in a control session. RESULTS: The placebo treatment produced comparable increases in expected relief for clinical and experimental pain. However, ratings of pain intensity, pain unpleasantness, and perceived relief confirmed the larger placebo effect in low back pain than cold pressor pain. Retrospective ratings of perceived relief in low back pain generally showed the largest placebo effect compared with concurrent pain ratings. Furthermore, when the placebo session was performed after the control session, the placebo effect on low back pain was substantially reduced and observed only in perceived relief. Variations in expectation could not account for the large difference in placebo analgesia between clinical and experimental pain. CONCLUSIONS: The important reduction in placebo analgesia in low back pain after the single pre-exposure to the ineffective control treatment suggests the additional involvement of highly flexible mechanisms that may counteract the pro-analgesic effects of expectations.     

Progress report on the Bethesda System

The 2001 Bethesda System is a uniform system of terminology for reporting results of pap smears. It is acknowledged by most cytopathologists worldwide as a standard for cervical cytology reports. In France, several national surveys have confirmed its current utilization. However, more specific analysis have shown that the Bethesda System may be routinely modified by individual laboratories or even individual cytopathologist working within the same department. The aim of this progress report was to emphasize the importance of fully understanding the Bethesda System and applying it in a rigorous and standardized way.     

Cloning and characterization of the dromedary (Camelus dromedarius) neonatal Fc receptor (drFcRn)

The full length cDNA of the dromedary neonatal Fc receptor (drFcRn) chain was isolated and found that it is similar to the neonatal Fc receptor (FcRn) of other species with a high overall similarity to ruminant FcRn chains. The drFcRn/Fc contact residues are highly conserved and predicted to bind both conventional (IgG1) and heavy chain (IgG2a, IgG3) antibodies. Using immunohistochemistry, we detected its expression in the hepatocytes and in epithelial cells of portal bile ductuli and also in the mammary gland acini and ducti. Remarkably, Ser313, that was identified to be crucial for apical to basolateral transcytosis, is substituted in the drFcRn chain. The full length of the dog and orangutan FcRn chains was also identified from databases. Analyzing the phylogenetic relatedness of this gene we found that dromedary clustered together with artiodactyls, dog is located between artiodactyls and primates, where the orangutan was branched, reflecting the accepted evolutionary relationships.