Hôpital Montfort's Postnatal Care-at-Home Program: An Innovative Model for Early Postnatal Care.

The Montfort Postnatal Care-at-Home (MPCH) Program is an innovative, integrated physician, nurse and midwifery model of care that offers an early hospital discharge option to families. The MPCH Program provides care and support to families throughout their transition from hospital to home. The program has the potential to improve families' experiences and maternal-newborn health outcomes, and provides a safety net to families 24/7 during the first seven days postpartum at home. This model transforms how postnatal care is delivered, and has the potential to improve the flow of the birthing unit and the unit capacity and reduce acute care hospital costs.

Involvement of Autonomic Nervous System in New-Onset Atrial Fibrillation during Acute Myocardial Infarction.

Background: Atrial fibrillation (AF) is common after acute myocardial infarction (AMI) and associated with in-hospital and long-term mortality. However, the pathophysiology of AF in AMI is poorly understood. Heart rate variability (HRV), measured by Holter-ECG, reflects cardiovascular response to the autonomic nervous system and altered (reduced or enhanced) HRV may have a major role in the onset of AF in AMI patients. Objective: We investigated the relationship between autonomic dysregulation and new-onset AF during AMI. Methods: As part of the RICO survey, all consecutive patients hospitalized for AMI at Dijon (France) university hospital between June 2001 and November 2014 were analyzed by Holter-ECG <24 h following admission. HRV was measured using temporal and spectral analysis. Results: Among the 2040 included patients, 168 (8.2%) developed AF during AMI. Compared to the sinus-rhythm (SR) group, AF patients were older, had more frequent hypertension and lower left ventricular ejection fraction LVEF. On the Holter parameters, AF patients had higher pNN50 values (11% vs. 4%, p < 0.001) and median LH/HF ratio, a reflection of sympathovagal balance, was significantly lower in the AF group (0.88 vs 2.75 p < 0.001). The optimal LF/HF cut-off for AF prediction was 1.735. In multivariate analyses, low LF/HF <1.735 (OR(95%CI) = 3.377 (2.047-5.572))was strongly associated with AF, ahead of age (OR(95%CI) = 1.04(1.01-1.06)), mean sinus-rhythm rate (OR(95%CI) = 1.03(1.02-1.05)) and log NT-proBNP (OR(95%CI) = 1.38(1.01-1.90). Conclusion: Our study strongly suggests that new-onset AF in AMI mainly occurs in a dysregulated autonomic nervous system, as suggested by low LF/HF, and higher PNN50 and RMSSD values.

Impact of asymmetric dimethylarginine on mortality after acute myocardial infarction.

OBJECTIVE: Asymmetrical dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthases. From a prospective cohort of patients with acute myocardial infarction (MI), we aimed to analyze the predictive value of circulating ADMA concentrations on prognosis. METHODS AND RESULTS: Blood samples from 249 consecutive patients hospitalized for acute MI <24 hours were taken on admission. Serum levels of ADMA and its stereoisomer, symmetrical dimethylarginine (SDMA), were determined using high-performance liquid chromatography. The independent predictors of ADMA were glomerular filtration rate, female sex, and SDMA (R(2)=0. 25). Baseline ADMA levels were higher in patients who had died than in patients who were alive at 1 year follow-up (1.23 [0.98 to 1.56] versus 0.95 [0.77 to 1.20] micromol/L, P<0.001). By Cox multivariate analysis, the higher tertile of ADMA (median [interquartile range]: 1.45 [1.24 to 1.70] micromol/L) was a predictor for mortality (Hazard Ratio [95% CI], 4.83 [1.59 to 14.71]), when compared to lower tertiles, even when adjusted for potential confounders, such as acute therapy, biological, and clinical factors. CONCLUSIONS: Our study suggests that the baseline ADMA level has a strong prognostic value for mortality after MI, beyond traditional risk factors and biomarkers.

After four hours of cold ischemia and cardioplegic protocol, the heart can still be rescued with postconditioning.

BACKGROUND: There is evidence that ischemia lasting more than 4 hours affects cardiac allograft survival. Ischemia and reperfusion are associated with additional deleterious effects. Protective effects of preconditioning are already being used but protocols based on postconditioning have not been evaluated. We tested the impact of postconditioning on hearts maintained in the cold for a long period of total global ischemia and we compared the results with those obtained with pyruvate, a cardioprotective molecule. METHODS: Isolated working rat hearts were subjected to a global total ischemia (4 h/4 degrees C), followed by 45 min of reperfusion. Postconditioning consisted of brief total global ischemia applied three times during the onset of reperfusion (ischemia: 30 sec, reperfusion: 30 sec). Superoxide anion production and collagen content were evaluated on cryosections. RESULTS: Our results showed that postconditioning led to improvements in cardiac functions that were comparable to those conferred by pyruvate. Postconditioning reduced myocardial damage, gave better functional recovery, and better preserved the collagen content. It reduced the duration of arrhythmias at the onset of reperfusion. In the postconditioning group, this improvement was associated with a reduction in superoxide production. CONCLUSIONS: In conclusion, our study showed that postconditioning induced good cardioprotective effects in a long cold (4 hr/4 degrees C) ischemia protocol and led to lower O2 production in part mediated by the reduction in NAPDH oxidase activity. It is interesting to note that, in our experimental conditions, the beneficial effects of postconditioning were comparable to those produced by pyruvate.

Asymmetric dimethylarginine (ADMA) and hyperhomocysteinemia in patients with acute myocardial infarction.

OBJECTIVES: We sought to investigate the association between increased levels of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, and total plasma homocysteinemia (tHcy) in patients with acute myocardial infarction (AMI). DESIGN AND METHODS: In 138 patients hospitalized for AMI <24 h on admission, serum levels of ADMA, its symmetric stereoisomer (SDMA) and tHcy were measured. RESULTS: ADMA was positively associated with SDMA (p<0.001) and tHcy (p=0.03) but not with estimated glomerular filtration rates (eGFR, p=0.96), while tHcy strongly correlated with eGFR (p=0.002) and SDMA (p<0.001). By multiple linear regression, SDMA but not ADMA was independently associated with tHcy (p=0.005). CONCLUSION: Our findings suggest that, in AMI patients, hyperhomocysteinemia is indirectly related to ADMA levels via renal function. Moreover, ADMA level was independent of traditional cardiovascular risk factors in AMI patients. Interestingly, our findings suggest that SDMA could be a good risk indicator for cardiovascular disease in AMI patients.

A peroxynitrite decomposition catalyst: FeTPPS confers cardioprotection during reperfusion after cardioplegic arrest in a working isolated rat heart model.

Heart transplant is considered to be an extremely severe ischemia-reperfusion sequence. Post-ischemic dysfunction triggers multiple processes especially oxidative stress, but the mechanisms remain unclear. Free radical interactions lead to peroxynitrite generation, which seems to be involved in early post-transplant heart failure. The aim of this study was to evaluate the potential impact of a peroxynitrite decomposition catalyst: FeTPPS (5,10,15,20-tetrakis-[4-sulfonatophenyl]-porphyrinato-fer[III]) and pyruvate on myocardial functional recovery after cardioplegic arrest using an experimental protocol in rat hearts. Isolated working rat hearts were subjected to ischemia (4 h at 4 degrees C in cardioplegic solutions), followed by 45 min of reperfusion. Four groups were constituted: control, pyruvate: (2 mm) added to cardioplegic and Ringer-lactate solutions, FeTPPS: (10 microm) perfused during the reperfusion, and a combination of both treatments. Lactate dehydrogenase (LDH) activity was assessed during the reperfusion to evaluate the level of cardiac injury. Oxidative stress was evaluated on heart slices using a fluorescent probe: dihydroethidium, and the collagen content was assessed using picro-Sirius coloration. Global post-ischemic recovery in the control group was about 35% of pre-ischemic values. Results showed that addition of pyruvate led to an increase in myocardial function and to a decrease in LDH activity released during the reperfusion. FeTPPS protected against injury after cardioplegic arrest during reperfusion. No additive effect of the two treatments (pyruvate + FeTPPS) was observed. The collagen content was better preserved in the FeTPPS group than in the control and pyruvate groups. In conclusion, this study shows that peroxynitrite plays an important role in the functional and cellular alterations associated with cardiac ischemia-reperfusion sequences and confirms that pyruvate helped to preserve myocardial function. The use of the peroxynitrite decomposition catalyst (FeTPPS) may help to improve myocardial preservation during a prolonged ischemia sequence.

Dissociation between vascular oxidative stress and cardiovascular function in Wistar Kyoto and spontaneously hypertensive rats.

It has not been completely demonstrated if hypertension may, in part, develop as a result of increased oxidative stress (OS), inflammation and little is known about the short-term effects of antioxidant therapy. This study was designed to appreciate the effect of 7 days vitamin C-enriched diet (5 g/kg/day) on hemodynamic function and vascular OS in normotensive Wistar Kyoto rats and hypertensive rats (SHR). Aorta NAD(P)H oxidase activity was determinate and free radicals evaluated by electron spin resonance with a spin probe CP-H. Matrix metalloproteinase-1 (MMP-1) and monocyte chemoattractant protein-1 (MCP-1) expression were measured. The treatment with vitamin C did not change arterial pressure in SHR but prevented the increase in OS levels in SHR aortas. MMP-1 and MCP-1 expressions were more intense in the media of SHR aortas than in those of WKY rats but these expressions were not modified by vitamin C-pretreatment. Vitamin C-pretreatment was not able to protect heart against in vitro ischemia-reperfusion dysfunctions. These data may suggest that treatment with high doses of vitamin C in SHR can limit over-production of reactive oxygen species; however this effect was not accompanied with changes in arterial pressure and protection against I-R dysfunctions. Dissociation between vascular oxidative stress and cardiovascular function may be evoked.

Smokeless tobacco, sport and the heart.

Smokeless tobacco (snuff) is a finely ground or shredded tobacco that is sniffed through the nose or placed between the cheek and gum. Chewing tobacco is used by putting a wad of tobacco inside the cheek. Smokeless tobacco is widely used by young athletes to enhance performance because nicotine improves some aspects of physiology. However, smokeless tobacco has harmful health effects, including cardiovascular disorders, linked to nicotine physiological effects, mainly through catecholamine release. Nicotine decreases heart rate variability and the ventricular fibrillation threshold, and promotes the occurrence of various arrhythmias; it also impairs endothelial-dependent vasodilation and could therefore promote premature atherogenesis. At rest, heart rate, blood pressure, inotropism, cardiac output and myocardial oxygen consumption are increased by nicotine, leading to an imbalance between myocardial oxygen demand and supply. The same occurs at submaximal levels of exercise. These increases are accompanied by a rise in systemic resistances. At maximal exercise, heart rate, cardiac output and maximal oxygen uptake (V˙O2max) are unaffected by nicotine. Because endothelial dysfunction is promoted by nicotine, paradoxical coronary vasoconstriction may occur during exercise and recovery. Nicotine induces a decrease in muscular strength and impairs anaerobic performance. However, nicotine is used in sports as it diminishes anxiety, enhances concentration and agility, improves aerobic performance and favours weight control. Importantly, smokeless tobacco, similar to cigarette smoking, leads to nicotine dependence through dopaminergic pathways. Smokeless tobacco has harmful cardiovascular effects and is addictive: it fulfils all the criteria for inclusion in the World Anti-Doping Agency prohibited list as a doping product. Smokeless tobacco use in sporting activities must be discouraged.

Effect of two new PBN-derived phosphorylated nitrones against postischaemic ventricular dysrhythmias.

Spin traps might exert antioxidant cardioprotective effects during myocardial ischaemia-reperfusion where free radicals are thought to be responsible for the occurrence of reperfusion injury. The aim of our study was to investigate the effects of two new alpha-phenyl N-tert-butylnitrone (PBN)-derived beta-phosphorylated nitrones: 2-N-oxy-N-[benzylidène amino] diéthyl propyl-2-phosphate (PPN) and 1-diethoxyphosphoryl-1-methyl-N-[(1-oxido-pyridin-1-ium-4-yl) methylidene] ethylamine N-oxide (4-PyOPN) compared with PBN on (1) the evolution of cardiovascular parameters and (2) the postischaemic recovery. Anaesthetized rats were injected with 120 micro mol/kg of the nitrones or 14 micro mol/kg of amiodarone, used as a reference antidysrhythmic drug. Ischaemia was induced in vivo through ligation of the left anterior descending coronary artery for 5 min followed by 15 min of reperfusion after release. Cardiovascular parameters and occurrence of ventricular premature beats (VPB), ventricular tachycardia (VT) and fibrillation (VF) were recorded throughout the experiment. Under nonischaemic conditions, none of the three spin traps was shown to modify cardiovascular parameters during the 25-min measurement period. Solvent-treated (NaCl 0.9%) animals challenged with ischaemia-reperfusion exhibited 39 +/- 10 VPB, 156 +/- 39 s of VT and 60% mortality caused by sustained VF. Nitrones improved slightly postischaemic recovery, reducing the occurrence of VF and mortality to 33% whereas amiodarone injection totally suppressed rhythm disturbances and mortality. Our study has shown only limited antidysrhythmic cardioprotective effects of PBN-derived beta-phosphorylated nitrones during reperfusion after a regional myocardial ischaemia but also minor antioxidant properties of these spin trapping agents.

Mitochondrial basis of the anti-arrhythmic action of lidocaine and modulation by the n-6 to n-3 PUFA ratio of cardiac phospholipids.

The aim of this study was to evaluate the involvement of mitochondria in the mechanism of the anti-arrhythmic lidocaine. Rats were fed with a diet containing either n-6 polyunsaturated fatty acids (PUFAs, SSO group) or an equimolecular mixture of n-3 and n-6 PUFAs (FO group) for 8 weeks. The hearts were perfused according to the working mode using a medium with or without lidocaine 5 µm. They were then subjected to local ischemia (20 min) and reperfusion (30 min). Dietary n-3 PUFAs triggered the expected decrease in the n-6/n-3 PUFA ratio of cardiac phospholipids. Reperfusing the ischemic area favored the incidence of severe arrhythmias. Lidocaine treatment abolished almost completely reperfusion arrhythmias in the FO group, but did not display anti-arrhythmic properties in the SSO group. As it was indicated by measurements of the mitochondrial function, lidocaine seemed to favor mitochondrial calcium retention in the FO group, which might prevent cytosolic calcium spikes and reperfusion arrhythmias. In the SSO group, the resistance to lidocaine was associated with an aggravation of cellular damages. The mitochondrial calcium retention capacities were saturated, and lidocaine was unable to increase them, making the drug inefficient in preventing reperfusion arrhythmias.

High N-terminal pro-B-type natriuretic peptide levels are associated with reduced heart rate variability in acute myocardial infarction.

AIM: We investigated the relationships between the autonomic nervous system, as assessed by heart rate variability (HRV) and levels of N-terminal Pro-B-type Natriuretic Peptide (Nt-proBNP) in patients with acute myocardial infarction (MI). METHODS AND RESULTS: The mean of standard deviation of RR intervals (SDNN), the percentage of RR intervals with >50 ms variation (pNN50), square root of mean squared differences of successive RR intervals (rMSSD), and frequency domain parameters (total power (TP), high frequency and low frequency power ratio (LF/HF)) were assessed by 24 h Holter ECG monitoring. 1018 consecutive patients admitted <24 h for an acute MI were included. Plasma Nt-proBNP (Elecsys, Roche) was measured from blood samples taken on admission. The median (IQR) Nt-proBNP level was 681(159-2432) pmol/L. Patients with the highest quartile of Nt-proBNP were older, with higher rate of risk factors and lower ejection fraction. The highest Nt-proBNP quartile group had the lowest SDNN, LF/HF and total power but similar pNN50 and rMSSD levels. Nt-proBNP levels correlated negatively with SDNN (r = -0.19, p<0.001), LF/HF (r = -0.37, p<0.001), and LF (r = -0.29, p<0.001) but not HF (r = -0.043, p = 0.172). Multiple regression analysis showed that plasma propeptide levels remained predictive of LF/HF (B(SE) = -0.065(0.015), p<0.001)), even after adjustment for confounders. CONCLUSIONS: In conclusion, our population-based study highlights the importance of Nt-proBNP levels to predict decreased HRV after acute MI.

Docosahexaenoic acid, but not eicosapentaenoic acid, lowers ambulatory blood pressure and shortens interval QT in spontaneously hypertensive rats in vivo.

This study was designed to evaluate the effects of individual dietary long-chain n-3 polyunsaturated fatty acids (LCPUFA) on hypertension and cardiac consecutive disorders in spontaneously hypertensive rats (SHR) as compared to Wistar-Kyoto rats (WKY). Rats were fed for 2 months an eicosapentaenoic (EPA)- or docosahexaenoic acid (DHA)-rich diet (240 mg/day) or an n-3 PUFA-free diet. Male SHR (n=6), implanted with cardiovascular telemetry devices, were housed in individual cages for continuous measurements of cardiovascular parameters (blood pressure (BP) and heart rate (HR)) during either activity or rest periods, ECG were recorded during the quiet period. The n-6 PUFA upstream of arachidonic acid was affected in SHR tissues. The cardiac phospholipid fatty acid profile was significantly affected by dietary DHA supply, and EPA in a very lower extent, since DHA only was incorporated in the membranes instead of n-6 PUFAs. Endothelium n-6 PUFA content increased in all SHR groups. Compared to WKY, linoleic acid content decreased in both studied tissues. Cardiac noradrenalin decreased while the adrenal catecholamine stores decreased in SHR as compared to WKY. Both n-3 PUFA supply induced a decrease of adrenal catecholamine stores. Nevertheless after 6 weeks, DHA but not EPA induced a lowering-blood pressure effect and shortened the QT interval in SHR, most probably through its tissue enrichment and a specific effect on adrenergic function. Dietary DHA supply retards blood pressure development and has cardioprotective effect. These findings, showing the cardioprotective effects of DHA in living animals, were obtained in SHR, but may relate to essential hypertension in humans.

Assessment of cardiac autonomic nervous activity in frail elderly people with postural abnormalities and in control subjects.

Heart rate variability (HRV), which is considered to reflect the activity of the autonomic nervous system (ANS), has been shown to decline with age. The aim of the present study was to explore cardiac ANS in older patients showing frontal-subcortical dysfunction with "Psychomotor Disadaptation Syndrome" (PDS), through the 24-h HRV. We enrolled 14 patients with PDS (mean age: 84.5+/-6.9 years), they were compared to 13 frail control subjects (mean age: 80.6+/-6.7 years). Cardiac ANS activity was assessed by 24-h ECG recordings from three leads with a Holter digital monitor. The decrease in cardiac ANS activity observed in PDS subjects was greater than the alteration found in normally aging subjects. The abnormalities of ANS that aggravate the effects of aging can be seen as a type of physical deconditioning. Such patients could benefit from particular attention in physical training.

Long-term effect of dietary {alpha}-linolenic acid or decosahexaenoic acid on incorporation of decosahexaenoic acid in membranes and its influence on rat heart in vivo.

The present study was designed to evaluate whether long-term intake of dietary alpha-linolenic acid (ALA), supplied as whole grain-extruded linseed, can increase endogenous production of n-3 long-chain polyunsaturated fatty acids (FAs) in healthy adult rats and influence the heart rate (HR) and adrenergic response in the same way as docosahexaenoic acid (DHA)-rich diets. DHA enrichment was evaluated using FA analysis of tissue phospholipids after 8, 16, 24, and 32 wk of feeding in male Wistar rats randomly assigned to three dietary groups (n = 8 in each group): a reference fat diet (RFD), an ALA-rich (ALA) diet, and a DHA-rich (DHA) diet. At 1 wk before the animals were killed, under anesthesia, HR was measured from ECG recordings during an adrenergic stimulation challenge (n = 8). There was a significant increase of DHA in the cardiac membrane in the ALA group compared with the RFD group. DHA content in the cardiac membrane was approximately 10% in the ALA group vs. 20% in the DHA group and 4% in the RFD group. The cardiac FA profile was established after 2 mo and remained essentially unchanged thereafter. Regardless of the diet, DHA in the heart decreased with age. Nevertheless, DHA content in the heart remained at >15% in the DHA group and remained greater in older rats fed the ALA diet than in younger RFD-fed rats. Basal HR decreased in the ALA group (395 +/- 24.9 beats/min) to a level between that of the DHA and RFD groups (375 +/- 26.4 and 407 +/- 36.7 beats/min, respectively). Both n-3 dietary intakes contribute to enhancement of the chronotropic response to adrenergic agonist stimulation. Regulation of HR by neurohumoral mediators may be controlled by lower content of DHA, e.g., by a dietary supply of extruded linseed (ALA).

Acute administration of epirubicin induces myocardial depression in isolated rat heart and production of radical species evaluated by electron spin resonance spectroscopy.

The aim of our study was to evaluate the acute effect of epirubicin (EPI), an anthracycline anticancer drug, on the evolution of cardiac functional parameters and production of reactive oxygen/nitrogen species (RONS). Isolated perfused rat hearts were subjected to 70 minutes of EPI (10.3 microM) infusion and to 5 minutes of isoproterenol (ISO, 0.1 microM) at the end of the protocol. Coronary flow (CF), left ventricular developed pressure (LVDP), and lactate dehydrogenase (LDH) release in the coronary effluents were evaluated throughout the protocol. RONS were detected in the coronary effluents by electron spin resonance spectroscopy with a spin probe, 1-hydroxy-3-carboxy-pyrrolidine (CP-H, 0.1 mM). EPI induced a reduction in CF and in LVDP (P < 0.001). ISO infusion enhanced CF and RPP in the control group; in the EPI group, these increases were significantly impaired. Release of LDH was significantly increased during EPI infusion (P < 0.001). RONS was 2.5 times greater in the EPI group than in the control group (P < 0.05). In conclusion, a significant deterioration in cardiac function was observed after EPI perfusion and was associated with cellular injury and the generation of myocardial RONS. Further investigations are now needed to determine whether new cardioprotective agents targeting oxidative stress may reduce the incidence of anthracycline-induced cardiotoxicity.

Adverse effects of free fatty acid associated with increased oxidative stress in postischemic isolated rat hearts.

The mechanisms of the adverse effects of free fatty acids on the ischemic-reperfused myocardium are not fully understood. Long-chain fatty acids, including palmitate, uncouple oxidative phosphorylation and should therefore promote the formation of oxygen-derived free radicals, with consequent adverse effects. Conversely, the antianginal agent trimetazidine (TMZ), known to inhibit cardiac fatty acid oxidation, could hypothetically lessen the formation of reactive oxygen species (ROS) and thus improve reperfusion mechanical function. Isolated perfused rat hearts underwent 30 min of total global ischemia followed by 30 min of reperfusion. Hearts were perfused with glucose 5.5 mmol/l or palmitate 1.5 mmol/l with or without TMZ (100 micromol/l). Ascorbyl free radical (AFR) release during perfusion periods was measured by electron spin resonance as a marker of oxidative stress. Post-ischemic recovery in the palmitate group of heart was lower than in the glucose group with a marked rise in diastolic tension and reduction in left ventricular developed pressure (Glucose: 85 +/- 11 mmHg; Palmitate: 10 +/- 6 mmHg; p < 0.001). TMZ decreased diastolic tension in both glucose- and in palmitate-perfused hearts. Release of AFR within the first minute of reperfusion was greater in palmitate-perfused hearts and in hearts perfused with either substrate, this marker of oxidative stress was decreased by TMZ (expressed in arbitrary units/ml; respectively: 8.49 +/- 1.24 vs. 1.06 +/- 0.70 p < 0.05; 12.47 +/- 2.49 vs. 3.37 +/- 1.29 p < 0.05). Palmitate increased the formation of ROS and reperfusion contracture. TMZ, a potential inhibitor of palmitate-induced mitochondrial uncoupling, decreased the formation of free radicals and improved postischemic mechanical dysfunction. The novel conclusion is that adverse effects of fatty acids on ischemic-reperfusion injury may be mediated, at least in part, by oxygen-derived free radicals.

Substrate dependence of the postischemic cardiomyocyte recovery: dissociation between functional, metabolic and injury markers.

Defining the substrate that influences the most favourably the myocardial post-ischemic recovery is subject of debates, due to dissociation between functional and biochemical benefits. Hence, we studied the effects of either glucose or different fatty acids on the functional and metabolic recovery of post-ischemic cardiomyocytes in a substrate-free hypoxia model of simulated ischemia-reperfusion. Rat cardiomyocytes were submitted to a 2.5 h simulated ischemia followed by a 2 h reoxygenation without substrate (control), or with either glucose, octanoic acid, oleic acid, or elaidic acid. During simulated ischemia, electromechanical function gradually disappeared while the cellular viability and mitochondrial function declined. During control simulated reperfusion, cardiomyocytes recovered near normal function but a significant reduction in the action potential amplitude and rate persisted. The addition of glucose or oleic acid during simulated reperfusion promoted a faster, better and sustain functional recovery. Amongst the fatty acids, the functional recovery was slower with elaidic and octanoic acids as compared with oleic acid. The mitochondrial function was better improved during simulated reperfusion with glucose than with the tested fatty acids, among which elaidic acid was the less unfavourable. Paradoxically, the addition of whichever substrate during simulated reperfusion tended to worsen the cellular viability. Thus, cardiomyocytes recovery strongly relies on the characteristics of the substrate supplied at the onset of simulated reperfusion: glucidic or lipidic nature, chain-length, insaturation degree. Moreover, these data suggest that defining the appropriateness of a given substrate for the post-ischemic cardiomyocyte recovery is closely related to the functional and the biological endpoints in consideration.

Influence of ischemia on heart-rate variability in chronic hemodialysis patients.

BACKGROUND: Sudden cardiac death occurring in patients with end-stage renal disease (ESRD) may be related to poor autonomic function with a significant decreased heart-rate variability (HRV). In addition, coronary artery disease has a high prevalence in this population and accounts for 50% of deaths. In the present study, relationships between HRV and myocardial ischemic abnormalities revealed by myocardial scintigraphy (MS) were evaluated in 32 chronic hemodialysis patients. METHODS: We prospectively studied 32 chronic hemodialysis patients. Each underwent MS and 24 h electrocardiography at baseline for analysis of time and frequency domain the day of dialysis. Three periods were analyzed: during dialysis session, the morning after (nondialytic period), and in a 24 h period. Patients were included in group 1 (seven women, 11 men; mean age: 62+/-19 years) when MS revealed no ischemia, whereas patients were included in group 2 (seven women, seven men; mean age: 63.1+/-20 years) when MS revealed ischemic lesions. RESULTS: A student+/-test revealed that during the nondialytic period, two important markers of HRV, percentage of delta RR>50 ms (pNN50) (4.5+/-4.04 in group 1 versus 1.7+/-1.4 in group 2), and root mean square of delta RR (rMSSD) (27.7+/-13.4 versus 19.7+/-6.8) were significantly reduced in group 2 compared with values in group 1. No significant difference appears between the two groups for standard deviation of normal to normal intervals (SDNN), mean heart rate, and spectral analysis. CONCLUSION: Patients with ESRD and myocardial ischemia revealed by MS have reduced parasympathetic activity during the nondialytic period. Correlations between parameters of HRV and ischemic lesions revealed by MS have been shown for the first time.

Ability of thermophilic lactic acid bacteria to produce aroma compounds from amino acids.

Although a large number of key odorants of Swiss-type cheese result from amino acid catabolism, the amino acid catabolic pathways in the bacteria present in these cheeses are not well known. In this study, we compared the in vitro abilities of Lactobacillus delbrueckii subsp. lactis, Lactobacillus helveticus, and Streptococcus thermophilus to produce aroma compounds from three amino acids, leucine, phenylalanine, and methionine, under mid-pH conditions of cheese ripening (pH 5.5), and we investigated the catabolic pathways used by these bacteria. In the three lactic acid bacterial species, amino acid catabolism was initiated by a transamination step, which requires the presence of an alpha-keto acid such as alpha-ketoglutarate (alpha-KG) as the amino group acceptor, and produced alpha-keto acids. Only S. thermophilus exhibited glutamate dehydrogenase activity, which produces alpha-KG from glutamate, and consequently only S. thermophilus was capable of catabolizing amino acids in the reaction medium without alpha-KG addition. In the presence of alpha-KG, lactobacilli produced much more varied aroma compounds such as acids, aldehydes, and alcohols than S. thermophilus, which mainly produced alpha-keto acids and a small amount of hydroxy acids and acids. L. helveticus mainly produced acids from phenylalanine and leucine, while L. delbrueckii subsp. lactis produced larger amounts of alcohols and/or aldehydes. Formation of aldehydes, alcohols, and acids from alpha-keto acids by L. delbrueckii subsp. lactis mainly results from the action of an alpha-keto acid decarboxylase, which produces aldehydes that are then oxidized or reduced to acids or alcohols. In contrast, the enzyme involved in the alpha-keto acid conversion to acids in L. helveticus and S. thermophilus is an alpha-keto acid dehydrogenase that produces acyl coenzymes A.

Dietary n-3 PUFAs affect the blood pressure rise and cardiac impairments in a hyperinsulinemia rat model in vivo.

The cardiovascular consequences of eicosapentaenoic acid (EPA)- and docosahexaenoic acid (DHA)-specific intake were evaluated in vivo in a hyperinsulinemia (HI) model induced by dietary fructose intake. Wistar rats were fed a diet containing (or not for control) either EPA or DHA. The rise in blood pressure (BP), heart rate, and ECG were continuously monitored using an intra-abdominal telemetry system. The myocardial phospholipid fatty acid profile was significantly affected by DHA intake but less by EPA intake. The data indicated a reduced rise in BP in both DHA and EPA HI groups compared with controls. This result was confirmed by tail-cuff measurement after 5 wk [133.3 +/- 1.67 and 142.5 +/- 1.12 mmHg in n-3 polyunsaturated fatty acid (PUFA) and control groups, respectively], whereas n-3 PUFA did not affect BP in non-HI rats (116.3 +/- 3.33 mmHg). The heart rate was lower in the HI DHA group than in the other two dietary HI groups. Moreover, DHA induced a significantly shorter QT interval. It is concluded that the cardioactive component of fish oils is DHA through a mechanism that may involve the cardiac adrenergic system.