Development of a new sensor based on micro-electro-mechanical systems for objective in vivo measurement of the cutaneous temperature: application to foundations

BACKGROUND/AIMS: The purpose of this work was to develop a new sensor for objective in vivo measurement of the cutaneous temperature based on micro-electro-mechanical systems (MEMS), and to compare these performances with those of a classical thermocouple. Research on this new sensor was carried out to allow the quantification of the thermal properties of the made-up skin. METHODS: Sixteen female subjects divided into two different age groups (18-35 and >50 years old) were recruited for this study. Several zones of the face and forearms were made up at random with foundations containing or not a thermoregulator raw material. The quantity of foundation applied on the skin was standardized and measurements were carried out first before make-up, and then 10 s and 5 min after make-up. The new sensor and the thermocouple were used successively on each zone. The cutaneous temperature was expressed in degrees celsius. RESULTS/CONCLUSION: The two systems are similar in terms of repeatability and reproducibility, with some differences in sensibility. The data measured by the MEMS sensor appear lower than those measured by the thermocouple. After make-up, the MEMS sensor detects a progressive increase of the temperature in time whereas the thermocouple detects a decrease. We found the same evolution on the face but in a more attenuated way. These results tend to show that the devices do not measure the same phenomenon. The thermocouple appears more sensitive to the thermal response of the made-up surface whereas the MEMS sensor appears more sensitive to the heat transfers in the interface between the skin and make-up.     

Regulation of calcium current by low-Km cyclic AMP phosphodiesterases in cardiac cells.

The voltage-gated Ca2+ current (ICa) in cardiac myocytes is regulated by cAMP-dependent phosphorylation. Although the regulation of ICa via mechanisms involving modulation of cAMP synthesis is well understood, the regulation of cAMP degradation has been less thoroughly investigated. The goal of the present study was to investigate the participation of different subclasses of cAMP phosphodiesterase (PDE) in regulating cAMP-dependent phosphorylation of Ca2+ channels in frog ventricular myocytes. Cardiomyocytes were isolated enzymatically and mechanically and were patch-clamped using the whole-cell configuration of the patch-clamp technique. The effects of various low-Km cAMP PDE inhibitors on ICa were examined. None of the inhibitors tested [milrinone, indolidan, 1-methyl 3-isobutyl xanthine (MIX), rolipram, or Ro 20-1724] were able to elevate ICa in the absence of elevated cAMP, although they all increased ICa in the presence of submaximal levels of cAMP. This result suggests that these compounds do not act directly on Ca2+ channels but rather modulate cAMP degradation. Half-maximal effects were observed with 1.4 microM milrinone and 3.4 microM MIX. Milrinone was effective when applied from either the extracellular or intracellular surface, whereas MIX was effective only when applied from the extracellular solution. In the presence of internal cGMP, which stimulates the cGMP-stimulated PDE, the low-Km cAMP PDE inhibitors had no effect on ICa, whereas high concentrations of MIX, which inhibit the cGMP-stimulated PDE, increased ICa. This would support the hypothesis that cGMP-stimulated PDE either has a much stronger capacity to hydrolyze cAMP or is more efficiently coupled to Ca2+ channels than the low-Km cAMP PDEs.     

Quantification and pharmacological characterization of dialysate levels of noradrenaline in the striatum of freely-moving rats: release from adrenergic terminals and modulation by α2-autoreceptors

Information concerning striatal levels of noradrenaline (NA) remains inconsistent. Here we have addressed this issue using a sensitive method of HPLC coupled to amperometric detection. The NA reuptake-inhibitor, reboxetine, selectively elevated levels of NA versus dopamine (DA), and NA levels were also selectively elevated by the α₂-adrenoceptor (AR) antagonist, atipamezole. The actions of atipamezole were mimicked by the preferential α_2A-AR antagonist, BRL44408, while JO-1 and prazosin, preferential antagonists at α_2C-ARs, caused less marked elevations in NA levels. In contrast to antagonists, the α₂-AR agonist, S18616, decreased NA levels and likewise suppressed those of DA. Unilateral lesions of the substantia nigra with 6-hydroxydopamine depleted DA levels without affecting those of NA. Further, the D₃/D₂ receptor agonist, quinelorane, decreased levels of DA without modifying those of NA. However, the D₃/D₂ receptor antagonists, haloperidol and raclopride, and the DA reuptake-inhibitor, GBR12935, elevated levels of both DA and NA. Levels of 5-HT (but not of NA or DA) were increased only by the 5-HT reuptake-inhibitor, citalopram. They were decreased by S18616 and prazosin, reflecting the inhibitory and excitatory influence of α₂- and α₁-ARs, respectively, upon serotonergic pathways. In conclusion, NA in the striatum is derived from adrenergic terminals. Its release is subject to tonic, inhibitory control by α₂-ARs, possibly involving both α_2A- and α_2C-AR subtypes, though their respective contribution requires clarification. A role of dopaminergic terminals in the reuptake of NA likely explains the elevation in its levels elicited by DA reuptake-inhibitors and D₃/D₂ receptor antagonists.     

Alternative methods to analyse the impact of HIV mutations on virological response to antiviral therapy

Background  

Principal component analysis (PCA) and partial least square (PLS) regression may be useful to summarize the HIV genotypic information. Without pre-selection each mutation presented in at least one patient is considered with a different weight. We compared these two strategies with the construction of a usual genotypic score.     

Quantification of plasma and intracellular levels of the HIV protease inhibitor ritonavir by competitive ELISA

The HIV protease inhibitor ritonavir (Norvir; ABT-578), currently used in combination with nucleoside analogs and other protease inhibitors in anti-HIV therapy, has previously been quantified by an HPLC procedure. Here, we report the first convenient one-step competitive ELISA for measuring plasma and intracellular ritonavir in HIV patients. Anti-ritonavir antibody was raised in rabbits using ritonavir-KLH conjugate as immunogen, and the enzymatic tracer was prepared by coupling the drug to acetylcholine esterase. Samples for analysis were first extracted with methanol. Bound/free separation was achieved in a microtiter plate previously coated with anti rabbit IgG monoclonal antibody. Fifty percent inhibition was observed at 1 ng/ml ritonavir and the method accurately and specifically detected as little as 3-4 ng/ml of plasma ritonavir as well as intracellular drug in the peripheral blood mononuclear cells of patients undergoing ritonavir therapy. Within-run and day to day coefficients of variation were below 10% and the drugs currently used in HIV therapy did not interfere with the test. The ELISA was applied to the measurement of plasma ritonavir and to the determination of the extracellular/intracellular drug level ratios in HIV patients receiving long-term multidrug therapy.     

Widespread lipoplex-mediated gene transfer to vascular endothelial cells and hemangioblasts in the vertebrate embryo.

We report here a method that allows fast, efficient, and low-cost screening for gene function in the vascular system of the vertebrate embryo. Through intracardiac delivery of nucleic acids optimally compacted by a specific cationic lipid, we are able to induce in vivo endothelial cell-specific gain-of-function during development of the vascular network in the chick embryo. When the nucleic acids are delivered during the period of intraembryonic hematopoiesis, aortic hemangioblasts, the forerunners of the hematopoietic stem cells known to derive from the aortic endothelium, are also labeled. Similarly, we show that siRNA could be used to induce loss-of-function in vascular endothelial cells. This gene transfer technique was also applied to the mouse embryo with a high efficiency. The present method allows large-scale analysis and may represent a new and versatile tool for functional genomics.     

Anti-SSA/Ro52 autoantibodies blocking the cardiac 5-HT4 serotoninergic receptor could explain neonatal lupus congenital heart block

The 52-kDa SSA/Ro (Ro52) ribonucleoprotein is an antigenic target strongly associated with the autoimmune response in mothers whose children develop neonatal lupus and congenital heart block. When sera from patients with systemic lupus erythematosus were used as autoimmune controls in an enzyme immunoassay to screen for antibodies against the human serotoninergic 5-HT4-receptor, a high correlation was found between the presence of anti-Ro52 protein antibodies in such sera and antibodies reacting with a synthetic peptide, corresponding to the second extracellular loop of the human 5-HT4 receptor (amino acid residues 165-185). Homology scanning between the 5-HT4 peptide and the sequence of the Ro52 protein indicated two potential common epitopes located between residues 365 and 396 of the Ro52 protein. Cross-reactivity was found between the peptide derived from the 5-HT4 receptor, and a peptide corresponding to residues 365-382 of the Ro52 protein. Autoantibodies, affinity-purified on the 5-HT4 receptor peptide, specifically recognized both the Ro52 protein and the 5-HT4 receptor protein in immunoblots. The affinity-purified antibodies antagonized the serotonin-induced L-type Ca channel activation on human atrial cells. This effect could explain the electrophysiological abnormalities in neonatal lupus.     

Induction of neonatal lupus in pups of mice immunized with synthetic peptides derived from amino acid sequences of the serotoninergic 5-HT4 receptor

We have previously suggested that the recognition of a cross-reactive epitope on the 5-HT4 receptor and the 52-kDa SSA/Ro protein by serotonin-antagonizing autoantibodies could explain the electrophysiological symptoms of congenital heart block in neonatal lupus. To confirm this hypothesis, we immunized female mice with four synthetic peptides corresponding to the recognized epitopes. All mice developed anti-peptide antibodies, which cross-reacted with the Ro52 and 5-HT4 receptor peptides and recognized both cognate proteins. Peptide-immune mice were mated. The pups from mice immunized with the Ro52 peptides had no symptoms of neonatal lupus apart from bradycardia. However, pups from mice immunized with the 5-HT4 receptor peptides and bradycardia, atrioventricular block of type I or II, longer QT intervals, skin rashes and neuromotor problems. The 5-HT4 receptor was detectable in the different fetal tissues affected (heart, skin and brain) by immunohistochemistry. Hearts from diseased pups were less developed and showed disorganized myocardial hyperplasia, compared to the normal littermates. These results demonstrate that the serotoninergic 5-HT4 receptor is the antigenic target of physiopathological autoantibodies in neonatal lupus.     

Estimation of dynamical model parameters taking into account undetectable marker values

Background  

Mathematical models are widely used for studying the dynamic of infectious agents such as hepatitis C virus (HCV). Most often, model parameters are estimated using standard least-square procedures for each individual. Hierarchical models have been proposed in such applications. However, another issue is the left-censoring (undetectable values) of plasma viral load due to the lack of sensitivity of assays used for quantification. A method is proposed to take into account left-censored values for estimating parameters of non linear mixed models and its impact is demonstrated through a simulation study and an actual clinical trial of anti-HCV drugs.     

Recurrent cardiac intimal sarcoma misdiagnosed as a myxoma or malignant transformation of a cardiac myxoma?

Cardiac intimal sarcoma is extremely rare and aggressive primary malignant cardiac tumors. Here, we reported the case of a young man initially operated for a tumor of the left atrium, causing a dynamic obstruction of the mitral valve and (mis‐)diagnosed as a myxoma at the histopathological analysis. Patient presented a local recurrence at 3 months and was reoperated. Pathology revealed this time the presence of an intimal sarcoma. Patient received adjuvant chemotherapy. Despite a good local control, the 1‐year follow‐up positron emission tomography scan revealed the presence of a metastasis in the left adrenal gland that was surgically resected. This article aims to highlight the risk of misdiagnosis in case of cardiac tumors, the hypothetical concept of malignant transformation of a cardiac myxoma, the aggressive course of the extremely rare cardiac intimal sarcoma, and the therapeutic modalities available to treat this pathology.