Samy Talha

Can the Six-Minute Walk Test Predict Peak Oxygen Uptake in Men With Heart Transplant?

OBJECTIVE To determine whether the six-minute walk test (6MWT) might predict peak oxygen consumption (VO2peak) after heart transplantation. DESIGN Case-control prospective study. SETTING Public hospital. PARTICIPANTS Patients with heart transplant (n=22) and age-matched sedentary male subjects (n=13). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Exercise performance using a maximal exercise test, distance walked using the 6MWT, heart rate, and VO2peak. RESULTS Compared with controls, exercise performance was decreased in patients with heart transplant with less distance ambulated (516+/-13m vs 592+/-13m; P<.001) and a decrease in mean VO2peak (23.3+/-1.3 vs 29.6+/-1mL x min(-1) x kg(-1); P<.001). Patients with heart transplant showed an increased resting heart rate, a response delayed both at the onset of exercise and during recovery. However, the patients heart rate at the end of the 6MWT was similar to that obtained at the ventilatory threshold. The formula did not predict measured VO2, with a weak correlation observed between the six-minute walk distance and both VO2peak (r=.53; P<.01) and ventilatory threshold (r=.53; P<.01) after heart transplantation. Interestingly, when body weight was considered, correlations coefficient increased to .74 and .77, respectively (P<.001). CONCLUSIONS In heart transplant recipients, the 6MWT is a safe, practical, and submaximal functional test. The distance-weight product can be used as an alternative method for assessing the functional capacity after heart transplantation but cannot totally replace maximal VO2 determination.

Does circulating BNP normalize after heart transplantation in patients with normal hemodynamic and right and left heart functions

Abstract:  Background:  Increased brain natriuretic peptide (BNP) in cardiovascular disease is thought to be a compensatory protective mechanism allowing to delay the occurrence of terminal heart failure. Heart transplantation should normalize the neuroendocrine balance but BNP remains elevated in stable heart‐transplant recipients (Htx). Such increase has been related to persistent endothelial and cardiac dysfunctions. The purpose of this study was to determine whether selected Htx, presenting with normal hemodynamic and cardiac systolic and diastolic functions on both side of the heart, show a normalization of their BNP plasma values.

Muscles susceptibility to ischemia-reperfusion injuries depends on fiber type specific antioxidant level

Muscle injury resulting from ischemia-reperfusion largely aggravates patient prognosis but whether and how muscle phenotype modulates ischemia-reperfusion-induced mitochondrial dysfunction remains to be investigated. We challenged the hypothesis that glycolytic muscles are more prone to ischemia-reperfusion-induced injury than oxidative skeletal muscles. We therefore determined simultaneously the effect of 3 h of ischemia induced by aortic clamping followed by 2 h of reperfusion (IR, n = 11) on both gastrocnemius and soleus muscles, as compared to control animals (C, n = 11). Further, we investigated whether tempol, an antioxidant mimicking superoxide dismutase, might compensate a reduced defense system, likely characterizing glycolytic muscles (IR-Tempol, n = 7). In the glycolytic gastrocnemius muscle, as compared to control, ischemia-reperfusion significantly decreased mitochondrial respiration (−30.28 ± 6.16%, p = 0.003), increased reactive oxygen species production (+79.15 ± 28.72%, p = 0.04), and decreased reduced glutathione (−28.19 ± 6.80%, p = 0.011). Less deleterious effects were observed in the oxidative soleus muscle (−6.44 ± 6.30%, +4.32 ± 16.84%, and −8.07 ± 10.84%, respectively), characterized by enhanced antioxidant defenses (0.63 ± 0.05 in gastrocnemius vs. 1.24 ± 0.08 μmol L−1 g−1 in soleus). Further, when previously treated with tempol, glycolytic muscle was largely protected against the deleterious effects of ischemia-reperfusion. Thus, oxidative skeletal muscles are more protected than glycolytic ones against ischemia-reperfusion, thanks to their antioxidant pool. Such pivotal data support that susceptibility to ischemia-reperfusion-induced injury differs between organs, depending on their metabolic phenotypes. This suggests a need to adapt therapeutic strategies to the specific antioxidant power of the target organ to be protected.

Effects of cyclic nucleotide phosphodiesterases (PDEs) on mitochondrial skeletal muscle functions

Mitochondria play a critical role in skeletal muscle metabolism and function, notably at the level of tissue respiration, which conduct muscle strength as well as muscle survival. Pathological conditions induce mitochondria dysfunctions notably characterized by free oxygen radical production disturbing intracellular signaling. In that way, the second messengers, cyclic AMP and cyclic GMP, control intracellular signaling at the physiological and transcription levels by governing phosphorylation cascades. Both nucleotides are specifically and selectively hydrolyzed in their respective 5′-nucleotide by cyclic nucleotide phosphodiesterases (PDEs), which constitute a multi-genic family differently tissue distributed and subcellularly compartmentalized. These PDEs are presently recognized as therapeutic targets for cardiovascular, pulmonary, and neurologic diseases. However, very few data concerning cyclic nucleotides and PDEs in skeletal muscle, specifically in mitochondria, are reported in the literature. The knowledge of PDE implication in mitochondrial signaling would be helpful for resolving critical mitochondrial dysfunctions in skeletal muscle.

Lack of endothelial dysfunction in patients under tacrolimus after orthotopic liver transplantation

Abstract:  Background:  Endothelial dysfunction is a significant cause of vascular and end‐organ damage after solid organ transplantation. The aim of this study was to compare endothelial function in healthy controls and in patients who received tacrolimus for immunosuppression after orthotopic liver transplantation (OLT).

Endocrine heart after lung transplantation: increased brain natriuretic peptide is related to right ventricular function

Brain natriuretic peptide (BNP) increases in proportion to the extent of right ventricular dysfunction in pulmonary hypertension and after heart transplantation. No data are available after lung transplantation. Clinical, biological, respiratory, echocardiographic characteristics and circulating BNP and its second messenger cyclic guanosine monophosphate (cGMP) were determined in thirty matched subjects (10 lung‐, 10 heart‐transplant recipients (Ltx, Htx) and 10 healthy controls). Eventual correlations between these parameters were investigated. Heart rate and pulmonary arterial blood pressure were slightly increased after transplantation. Creatinine clearance was decreased. Mean of forced expiratory volume in 1 s was 76.6 ± 5.3% and vital capacity was 85.3 ± 6.4% of the predicted values in Ltx. BNP was similarly increased in Ltx and Htx, as compared with control values (54.1 ± 14.2 and 45.6 ± 9.2 vs. 6.2 ± 1.8 pg/ml, respectively). Significant relationships were observed between plasma BNP and cGMP values (r = 0.62; P < 0.05 and r = 0.75; P < 0.01, in Ltx and Htx) and between BNP and right ventricular fractional shortening and tricuspid E/Ea ratio in Ltx (r = −0.75 and r = 0.93; P < 0.01, respectively). BNP is increased after lung transplantation, like after heart transplantation. The relationships observed suggest that the cardiac hormone might counterbalance possible deleterious effects of lung‐transplantation on right functioning of patient’s heart.

Télémédecine dans le domaine de l’insuffisance cardiaque.: État des lieux et focus sur le projet de télémédecine 2.0 E-care. Perspectives dans le domaine de la diabétologie

Resume Contexte Nous realisons ici une revue de la litterature centree sur les projets de telemedecine developpes dans le domaine de l’insuffisance cardiaque. Nous detaillerons tout particulierement le projet de telesurveillance appele E-care, dedie a la detection precoce des situations a risque de decompensation cardiaque. Les perspectives du developpement du systeme E-care dans le domaine de la diabetologie seront egalement abordees. Resultats De nombreux projets de telemedecine, s’appuyant sur les objets connectes ou sur les technologies des sciences de l’information et de la communication ont vu le jour, ces cinq dernieres annees, ou sont en cours de developpement dans le domaine de l’insuffisance cardiaque. C’est le cas du projet de telesurveillance E-care qui s’inscrit parfaitement dans le cadre des projets de telemedecine 2.0. Leur apport potentiel en termes de mortalite ou de morbidite, en nombre d’hospitalisations evitees, est actuellement en cours d’etude ou de documentation. Leur impact en termes d’economie de sante est egalement en cours de validation, en sachant que les projets de telemedecine les plus anciens avaient deja valide des benefices medicoeconomiques apportes par les solutions de telemedecine.

Telemedicine to Monitor Elderly Patients with Chronic Diseases, with a Special Focus on Patients with Chronic Heart Failure

Chronic diseases are one of the most difficult challenges to the beginning of the twentieth century. Monitoring patients with chronic diseases, especially in chronic heart failure or diabetes mellitus, using telemedicine systems is a potential means for optimizing the management of these patients, even in elderly patients. The e-care project is developing an “intelligent” communicative platform enabling the home monitoring of patients with heart failure, using non-invasive sensors, with additional contextual information and patients’ profile. As a result, this platform will assist health care professionals by providing an automated processing of these sensors’ transmitted data in order to detect and report signs of cardiac decompensation early or wrong adherence to therapy.

Ontology-Based Information Gathering System for Patients with Chronic Diseases: Lifestyle Questionnaire Design

The aim of this paper is to describe an original approach which consists of designing an Information Gathering System (IGS). This system gathers the most relevant information related to the patient. Our IGS is based on using questionnaire ontology and adaptive engine which collects relevant information by prompting the whole significant questions in connection with the patient’ s medical background. The formerly collected answers are also taken into consideration in the questions selection process. Our approach improves the classical approach by customizing the interview to each patient. This ensures the selection of all of the most relevant questions. The proposed IGS is integrated within E-care monitoring platform for gathering lifestyle-related patient data.

Hybrid reasoning-based medical platform to assist clinicians in their clinical reasoning process

Clinical decision support systems (CDSSs) have been hailed for their potential to reduce medical errors and improve the quality and safety of health care. CDSSs aim to assist clinicians in their decision making and take over some routines including diagnostic support. This paper presents a design of a generic medical platform to assist clinicians in their clinical reasoning process. Our platform aims to guide clinicians in the process of gathering relevant information and to help them in their decision making. It exploits two sources of knowledge namely: theoretical knowledge (clinical rules) and practical knowledge (clinical experiences) by relying on Rule-Based Reasoning and Case-Based Reasoning, respectively. moreover, we utilize the semantic web and ontologies for knowledge modeling in order to reuse and to share knowledge.