Cardiac Muscarinic Receptor Overexpression in Sudden Infant Death Syndrome

BACKGROUND: Sudden infant death syndrome (SIDS) remains the leading cause of death among infants less than 1 year of age. Disturbed expression of some neurotransmitters and their receptors has been shown in the central nervous system of SIDS victims but no biological abnormality of the peripheral vago-cardiac system has been demonstrated to date. The present study aimed to seek vago-cardiac abnormalities in SIDS victims. The cardiac level of expression of muscarinic receptors, as well as acetylcholinesterase enzyme activity were investigated. METHODOLOGY/PRINCIPAL FINDINGS: Left ventricular samples and blood samples were obtained from autopsies of SIDS and children deceased from non cardiac causes. Binding experiments performed with [(3)H]NMS, a selective muscarinic ligand, in cardiac membrane preparations showed that the density of cardiac muscarinic receptors was increased as shown by a more than doubled B(max) value in SIDS (n = 9 SIDS versus 8 controls). On average, the erythrocyte acetylcholinesterase enzyme activity was also significantly increased (n = 9 SIDS versus 11 controls). CONCLUSIONS: In the present study, it has been shown for the first time that cardiac muscarinic receptor overexpression is associated with SIDS. The increase of acetylcholinesterase enzyme activity appears as a possible regulatory mechanism

Guía de contenidos y trabajos prácticos. Prostodoncia II "B"

El propósito de esta guía es contribuir en una serie de aspectos fundamentales al trabajo clínico de la rehabilitación del paciente desdentado total, mediante la confección de prótesis dentales totales, proporcionando las bases para el entrenamiento del alumno en el pregrado.Fil: Pescio, Jorge. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Isla, Carolina. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Vera, Mónica. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Montañez, David. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Livolsi, Eduardo. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Bracamonte, Eva. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Peralta, Carlos. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: De la Vega, Diego. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: D´Angelo, Adriana. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Otras Ciencias de la Salu

Constitutive Overexpression of Muscarinic Receptors Leads to Vagal Hyperreactivity

BACKGROUND: Alterations in muscarinic receptor expression and acetylcholinesterase (AchE) activity have been observed in tissues from Sudden Infant Death Syndrome (SIDS). Vagal overactivity has been proposed as a possible cause of SIDS as well as of vasovagal syncopes. The aim of the present study was to seek whether muscarinic receptor overexpression may be the underlying mechanism of vagal hyperreactivity. Rabbits with marked vagal pauses following injection of phenylephrine were selected and crossed to obtain a vagal hyperreactive strain. The density of cardiac muscarinic receptors and acetylcholinesterase (AchE) gene expression were assessed. Blood markers of the observed cardiac abnormalities were also sought. METHODOLOGY/PRINCIPAL FINDINGS: Cardiac muscarinic M(2) and M(3) receptors were overexpressed in hyperreactive rabbits compared to control animals (2.3-fold and 2.5-fold, respectively) and the severity of the phenylephrine-induced bradycardia was correlated with their densities. A similar overexpression of M(2) receptors was observed in peripheral mononuclear white blood cells, suggesting that cardiac M(2) receptor expression can be inferred with high confidence from measurements in blood cells. Sequencing of the coding fragment of the M(2) receptor gene revealed a single nucleotide mutation in 83% of hyperreactive animals, possibly contributing for the transcript overexpression. Significant increases in AchE expression and activity were also assessed (AchE mRNA amplification ratio of 3.6 versus normal rabbits). This phenomenon might represent a compensatory consequence of muscarinic receptors overexpression. Alterations in M(2) receptor and AchE expression occurred between the 5th and the 7th week of age, a critical period also characterized by a higher mortality rate of hyperreactive rabbits (52% in H rabbits versus 13% in normal rabbits) and preceeded the appearance of functional disorders. CONCLUSIONS/SIGNIFICANCE: The results suggest that cardiac muscarinic receptor overexpression plays a critical role in the development of vagal hyperreactivity, whereas AchE hyperactivity appears as a compensatory consequence of it. Since similar vagal disorders were observed recently by us in SIDS, muscarinic receptor overexpression could become a marker of risk of vasovagal syncopes and SIDS

Mode de découverte d'une myotonie de steiner chez un garçon de 13 ans.

STRASBOURG-Medecine (674822101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Improving Walking Energy Efficiency in Transtibial Amputees Through the Integration of a Low-Power Actuator in an ESAR Foot

Reducing energy consumption during walking is a critical goal for transtibial amputees. The study presents the evaluation of a semi-active prosthesis with five transtibial amputees. The prosthesis has a low-power actuator integrated in parallel into an energy-storing-and-releasing foot. The actuator is controlled to compress the foot during the stance phase, supplementing the natural compression due to the user’s dynamic interaction with the ground, particularly during the ankle dorsiflexion phase, and to release the energy stored in the foot during the push-off phase, to enhance propulsion. The control strategy is adaptive to the user’s gait patterns and speed. The clinical protocol to evaluate the system included treadmill and overground walking tasks. The results showed that walking with the semi-active prosthesis reduced the Physiological Cost Index of transtibial amputees by up to 16% compared to walking using the subjects’ proprietary prosthesis. No significant alterations were observed in the spatiotemporal gait parameters of the participants, indicating the module’s compatibility with users’ natural walking patterns. These findings highlight the potential of the mechatronic actuator in effectively reducing energy expenditure during walking for transtibial amputees. The proposed prosthesis may bring a positive impact on the quality of life, mobility, and functional performance of individuals with transtibial amputation

AchE enzyme activity in erythrocytes from control and SIDS children.

<p>AchE enzyme activity was assayed colorimetrically in erythrocyte hemolysates. Each symbol represents one individual value; hatched bar represents the highest control value. *: <i>P</i> = 0.0128 <i>versus</i> control.</p

Total muscarinic receptors in hearts from control and SIDS children.

<p>Total muscarinic receptor densities (B_max; fmol mg⁻¹ protein) were obtained from Scatchard analysis of the saturation data using [³H]NMS as radioligand. Binding conditions were as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0009464#s2" target="_blank">Material and Methods</a>. Each symbol represents one individual value; hatched bar represents the highest control value. *: <i>P</i> = 0.0137 <i>versus</i> control.</p