Palmira Bernocchi

New insights on myocardial pyridine nucleotides and thiol redox state in ischemia and reperfusion damage

OBJECTIVE to investigate the changes of pyridine nucleotides and thiol redox state in cardiac tissue following ischemia and reperfusion. NADH/NAD and NADPH/NADP redox couples were specifically studied and the influence of NADPH availability on cellular thiol redox was also investigated. METHODS isolated rabbit hearts were Langendorff perfused and subjected to a protocol of ischemia and reperfusion. An improved technique for extraction and selective quantitation of pyridine nucleotides was applied. RESULTS ischemia and reperfusion induced an increase in diastolic pressure, limited recovery in developed pressure and loss of creatine phosphokinase. Creatine phosphate and ATP were decreased by ischemia and only partially recovered during reperfusion. NADH was increased (from 0. 36+/-0.04 to 1.96+/-0.15 micromol/g dry wt. in ischemia, P<0.001), whereas NADPH decreased during ischemia (from 0.78+/-0.04 to 0. 50+/-0.06 micromol/g dry wt., P<0.01) and reperfusion (0.45+/-0.03 micromol/g dry wt.). Furthermore, we observed: (a) release of reduced (GSH) and oxidised glutathione (GSSG) during reperfusion; (b) decreased content of reduced sulfhydryl groups during ischemia and reperfusion (GSH: from 10.02+/-0.76 to 7.11+/-0.81 nmol/mg protein, P<0.05, and to 5.48+/-0.57 nmol/mg protein; protein-SH: from 280.42+/-12.16 to 135.11+/-17.00 nmol/mg protein, P<0.001, and to 190.21+/-11.98 nmol/mg protein); (c) increased content in GSSG during reperfusion (from 0.17+/-0.02 to 0.36+/-0.02 nmol/mg protein, P<0.001); (d) increased content in mixed disulphides during ischemia (from 6.14+/-0.13 to 8.31+/-0.44 nmol/mg protein, P<0.01) and reperfusion (to 9.87+/-0.82 nmol/mg protein, P<0.01). CONCLUSIONS under severe low-flow ischemia, myocardial NADPH levels can decrease despite the accumulation of NADH. The reduced myocardial capacity to maintain NADPH/NADP redox potential can result in thiol redox state changes. These abnormalities may have important consequences on cellular function and viability.

Skeletal muscle myosin heavy chain expression in rats with monocrotaline-induced cardiac hypertrophy and failure. Relation to blood flow and degree of muscle atrophy

BACKGROUND In congestive heart failure (CHF) the skeletal muscle of the lower limbs develops a myopathy characterised by atrophy and shift from the slow to the fast type fibres. The mechanisms responsible for these changes are not clear yet. OBJECTIVES We investigated the influence of blood flow and degree of muscle atrophy on the myosin heavy chains (MHC) composition of the soleus and extensor digitorum longus (EDL) of rats with right ventricle hypertrophy and failure. METHODS CHF was induced in 16 rats by injecting 30 mg/kg monocrotaline. Eight animals had the same dose of monocrotaline but resulting in compensated right ventricle hypertrophy. Two age- and diet-matched groups of control animals (nine and five respectively) were also studied. The relative percentage of MHC1 (slow isoform), MHC2a (fast oxidative) and MHC2b (fast glycolytic) was determined by densitometric scan after electrophoretic separation. The relative weights of soleus and EDL (muscle weight/body weight) were taken as an index of muscle atrophy. Skeletal muscle blood flow was measured by injecting fluorescent micropheres. RESULTS CHF and Control (Con) rats showed similar degree of atrophy both in soleus (0.40 +/- 0.06 vs. 0.44 +/- 0.06 p = NS), and EDL (0.47 +/- 0.04 vs. 0.45 +/- 0.02, p = 0.09). In CHF rats these two muscles showed a statistically significant MHCs redistribution toward the fast type isozymes. In fact in EDL of CHF rats MHC2a was 30.5 +/- 6.1% vs. 35.8 +/- 8.6% of the Con (p < 0.05). MHC2b was however higher (68.5 +/- 6.6% vs. 61.0 +/- 9.6%, p = 0.017). In the soleus of CHF rats MHC1 was decreased (87.6 +/- 3.4% vs. 91.9 +/- 5.2%, p = 0.02), while MHC2a was increased (12.04 +/- 3.5% vs. 7.9 +/- 5.2%; p = 0.028). Similar changes were not found in the muscles of the compensated hypertrophy animals. No correlation was found between MHC pattern and the relative muscle weight in the CHF animals. Soleus blood flow in CHF rats was significantly lower than that of Con (0.11 +/- 0.03 ml/min/g vs. 0.22 +/- 0.03 p < 0.05), while no differences were found in EDL (0.06 +/- 0.02 ml/min/g vs. 0.08 +/- 0.02, p = NS). CONCLUSIONS In rats with CHF a skeletal muscle myopathy characterised by a shift of the MHCs toward the fast type isoforms occurs. The magnitude of the shift correlates neither with the degree of atrophy, nor with the skeletal muscle blood flow, suggesting that these two factors do not play a pivotal role in the pathogenesis of the myopathy.

Reduction of oxidative stress by carvedilol: role in maintenance of ischaemic myocardium viability

OBJECTIVES To differentiate the impact of the beta-blocking and the anti-oxidant activity of carvedilol in maintaining myocardium viability. METHODS Isolated rabbit hearts, subjected to aerobic perfusion, or low-flow ischaemia followed by reperfusion, were treated with two doses of carvedilol, one dose (2.0 microM) with marked negative inotropic effect due to beta-blockage and the other (0.1 microM) with no beta-blockage nor negative inotropism. Carvedilol was compared with two doses of propranolol, 1.0 - without - and 5.0 microM - with negative inotropic effect. Anti-oxidant activity was measured as the capacity to counteract the occurrence of oxidative stress and myocardium viability as recovery of left ventricular function on reperfusion, membrane damage and energetic status. RESULTS Carvedilol counteracted the ischemia and reperfusion induced oxidative stress: myocardial content of reduced glutathione, protein and non-protein sulfhydryl groups after ischaemia and particularly after reperfusion, was higher in hearts treated with carvedilol, while the myocardial content of oxidised glutathione was significantly reduced (0.30+/-0.03 and 0.21+/-0.02 vs. 0.39+/-0.03 nmol/mg prot, both P<0.01, in 0.1 and 2.0 microM). At the same time, carvedilol improved myocardium viability independently from its beta-blocking effect. On the contrary, propranolol maintained viability only at the higher dose, although to a lesser extent than carvedilol. This suggests that the effects of propranolol are dependent on energy saving due to negative inotropism. The extra-protection observed with carvedilol at both doses is likely due to its anti-oxidant effect. CONCLUSIONS Our data show that the anti-oxidant activity of carvedilol is relevant for the maintenance of myocardium viability.

Tele-assistance in patients with amyotrophic lateral sclerosis: long term activity and costs.

Purpose: To describe i) nurse’s utilisation and associated costs during 4-year tele-assistance in amyotrophic lateral sclerosis (ALS) ii) optimal time for initiating tele-assistance. Method: 73 ALS patients after hospital discharge were followed up on voice by phone calls conducted by a nurse through a clinical card which was tested for feasibility, efficacy and utility. Number of patients simultaneously assisted/month, calls/patient, fixed and variable costs were calculated. Results: Time between disease’s diagnosis and the beginning of tele-assistance was 720 ± 971 days. ALS patients’ percentage managed by nurses through tele-assistance increased over time by 628%. Tele-assistance integrated care (TAIC) followed up patients with a total of 5073 telephone calls. Steady state activity was reached at the 3rd year employing 5 ± 3 calls/pt/month (time/call 64 ± 44 min). Implementing the card was feasible, useful and effective by operator. Survival from diagnosis of ALS was 1224 ± 1150 days. Survival was related to tracheotomy. Conclusion: TAIC is a feasible tool to manage up to 25 ALS patients/month/nurse and costs about €105.00 per patient per month. Tele-assistance is proposed at 2/3 of time course of the disease. Implications for Rehabilitation People with ALS have a complex time course of their disease necessitating important clinical decisions. Individually structured holistic and rehabilitative programmes are required. Tele-assistance has been demonstrated to be useful to follow-up providing autonomy of care, psychosocial monitoring, interventions and a source of information. Tele-assistance integrated care is a feasible tool to manage up to 25 ALS patients/month/nurse. Tele-assistance costs about €105.00 per patient per month. Tele-assistance is proposed at 2/3 of time course of the disease.

Role of bradykinin and eNOS in the anti‐ischaemic effect of trandolapril

Angiotensin converting enzyme (ACE) inhibitors are under study in ischaemic heart diseases, their mechanism of action being still unknown. The anti‐ischaemic effect of trandolapril and the possible involvement of a bradykinin‐modulation on endothelial constitutive nitric oxide synthase (eNOS) in exerting this effect, were investigated. Three doses of trandolapril, chronically administered in vivo, were studied in isolated perfused rat hearts subjected to global ischaemia followed by reperfusion. Trandolapril has an anti‐ischaemic effect. The dose of 0.3 mg kg−1 exerted the best effect reducing diastolic pressure increase during ischaemia (from 33.0±4.5 to 14.0±5.2 mmHg; P<0.05 vs control) and reperfusion (from 86.1±9.4 to 22.2±4.1 mmHg; P<0.01 vs control), improving functional recovery, counteracting creatine phosphokinase release and ameliorating energy metabolism after reperfusion. Trandolapril down‐regulated the baseline developed pressure. Trandolapril increased myocardial bradykinin content (from 31.8±6.1 to 54.8±7.5 fmol/gww; P<0.05, at baseline) and eNOS expression and activity in aortic endothelium (both P<0.01 vs control) and in cardiac myocytes (from 11.3±1.5 to 17.0±2.0 mUOD μg protein−1 and from 0.62±0.05 to 0.80±0.06 pmol mg prot−1 min−1; both P<0.05 vs control). HOE 140 (a bradykinin B2 receptor antagonist) and NOS inhibitors counteracted the above‐reported effects. There was a negative correlation between myocytes eNOS up‐regulation and myocardial contraction down‐regulation. Our findings suggest that the down‐regulation exerted by trandolapril on baseline cardiac contractility, through a bradykinin‐mediated increase in NO production, plays a crucial role in the anti‐ischaemic effect of trandolapril by reducing energy breakdown during ischaemia.

The blood perfused isolated heart: characterization of the model

Abstract We have characterized the aerobic blood-perfused isolated heart model evaluating the hemodynamics and metabolism of both the blood donor animal and the isolated organ.Anaesthesia of the blood donor with sodium pentobarbital (30 mg/kg) increases arterial concentration of non esterified fatty acids (NEFA) from 80 ± 6 to 452 ± 70 μM; p < 0.01. Injection of 1.000 U/kg heparin causes a second significant increase from 452 ± 70 to 1012 ± 104 μM; p < 0.01. Insertion of the perfusion circuit, without the isolated heart, causes a reduction in blood pressure of the blood donor and a significant increase in norepinephrine from 277 ± 44 to 634 ± 130 pg/ml; p < 0.05.Two hours of aerobic perfusion of the isolated heart inserted in the perfusion circuit, decreases arterial pressure of the blood donor with a concomitant increase of plasma norepinephrine from 475 ± 150 to 841 ± 159 pg/ml; p k< 0.05. Developed pressure, oxygen consumption, glucose and NEFA uptake of the isolated heart remain constant during two hours of aerobic perfusion, NEFA being the preferred substrate. Tissue content of high energy phosphates at the end of the perfusion is high and similar to that observed “in vivo”. Despite this, there is a release of lactate and CPK from the isolated heart.We conclude that: 1) the model allows accurate measurement of hemodynamics and metabolism of both the isolated heart and the blood donor animal; 2) the perfusion procedure modifies the substrates concentration of the blood donor animal which, in turn, results in the preferential NEFA utilization of the isolated heart. These changes do not affect the functional parameters of the perfused heart.

Changes in oxidative stress and cellular redox potential during myocardial storage for transplantation: Experimental studies

BACKGROUND Cardioplegic solutions assure only a sub-optimal myocardial protection during prolonged storage for transplantation. The ultimate cause of myocardial damage during storage is unknown, but oxygen free radicals might be involved. We evaluated the occurrence of oxidative stress and changes in cellular redox potential after different periods of hypothermic storage. METHODS Langendorff-perfused rabbit hearts were subjected to a protocol mimicking each stage of a cardiac transplantation procedure: explantation, storage and reperfusion. Three periods of storage were considered: Group A = 5 hours, Group B = 15 hours, and Group C = 24 hours. Oxidative stress was determined in terms of myocardial content and release of reduced (GSH) and oxidized (GSSG) glutathione, and cellular redox potential as oxidized and reduced pyridine nucleotides ratio (NAD/NADH). Data on mechanical function, cellular integrity and myocardial energetic status were collected. RESULTS At the end of reperfusion, despite the different timings of storage, recovery of left ventricular developed pressure (46.1+/-7.0, 54.7+/-6.7, and 45.7+/-7.4% of the baseline pre-ischaemic value), energy charge (0.81+/-0.02, 0.81+/-0.02, and 0.77+/-0.01) and NAD/NADH ratio (8.87+/-1.08, 9.39+/-1.72, and 10.26+/-1.98) were similar in all groups (A, B and C). On the contrary, the rise in left ventricular resting pressure (LVRP) and GSH/GSSG ratio were significantly different between Group C, and Groups A and B (p<0.0001, analyzed by Generalized Estimating Equations model for repeated measures, and p<0.05, respectively). CONCLUSIONS The pathophysiology of myocardial damage during hypothermic storage cannot be considered as a normothermic ischaemic injury and parameters other than energetic metabolism, such as thiolic redox state, are more predictive of functional recovery upon reperfusion.

Skeletal muscle abnormalities in rats with experimentally induced heart hypertrophy and failure

Abstract.Background: In congestive heart failure (CHF), function and metabolism of skeletal muscles are abnormal. Aim: To evaluate whether the reduced oxidative capacity of skeletal muscles in CHF is due to impaired O2 utilisation. Methods: CHF was induced in rats by injecting 50 mg/Kg monocrotaline. Several animals received the same dose of monocrotaline but only compensated right ventricular hypertrophy and no sign of congestion resulted. Two age- and diet-matched groups of control animals were also studied. In soleus and extensor digitorum longus (EDL) muscles, we studied skeletal muscle blood flow, oxidative capacity and respiratory function of skinned muscle fibres. Results: In CHF, we observed a decrease of muscle blood flow (statistically significant in the soleus, p < 0.05 vs. controls). In compensated rats, a similar trend in blood flow was observed. In both soleus and EDL, a significant reduction of high energy phosphate and a shift of the redox potential towards accumulation of reducing equivalents were observed. The reduction of energy charge was not correlated to the decrease of blood flow. In skinned myofibres, the ratio of O2 utilised in the presence and in absence of ADP (an index of phoshorilating efficiency) was reduced from 8.9 ± 1.9 to 2.7 ± 0.2 (p < 0.001) and from 5.7 ± 1.0 to 2.0 ± 0.3 (p < 0.01) in soleus and EDL, respectively. Activity of the different complexes of respiratory chain was investigated by means of specific inhibitors, showing major abnormalities at the level of complex I. In fact, inhibition of VO2 by rotenone was decreased from 83.5 ± 3.2 to 36.4 ± 9.6 % (p < 0.005) and from 81.8 ± 6.1 to 38.2 ± 7.4 % (p < 0.005) in soleus and EDL, respectively. Conclusions: In rats with CHF, abnormalities of oxidative phosphorylation of muscles occur and complex I of the respiratory chain seem to be primarily affected. The metabolic alterations of skeletal muscles in CHF may be explained, at least in part, by an impaired O2 utilisation.

Feasibility and efficacy of a robotic device for hand rehabilitation in hemiplegic stroke patients: A randomized pilot controlled study

Objective: The purpose of the study was to evaluate the feasibility and efficacy of robot-assisted hand rehabilitation in improving arm function abilities in sub-acute hemiplegic patients. Design: Randomized controlled pilot study. Setting: Inpatient rehabilitation centers. Participants: Thirty hemiplegic stroke patients (Ashworth spasticity index <3) were recruited and randomly divided into a Treatment group (TG) and Control group (CG). Interventions: Patients in the TG received intensive hand training with Gloreha, a hand rehabilitation glove that provides computer-controlled, repetitive, passive mobilization of the fingers, with multisensory feedback. Patients in the CG received the same amount of time in terms of conventional hand rehabilitation. Main outcome measures: Hand motor function (Motricity Index, MI), fine manual dexterity (Nine Hole Peg Test, NHPT) and strength (Grip and Pinch test) were measured at baseline and after rehabilitation, and the differences, (Δ) mean(standard deviation), compared between groups. Results Twenty-seven patients concluded the program: 14 in the TG and 13 in the CG. None of the patients refused the device and only one adverse event of rheumatoid arthritis reactivation was reported. Baseline data did not differ significantly between the two groups. In TG, ΔMI 23(16.4), ΔNHPT 0.16(0.16), ΔGRIP 0.27(0.23) and ΔPINCH 0.07(0.07) were significantly greater than in CG, ΔMI 5.2(9.2), ΔNHPT 0.02(0.07), ΔGRIP 0.03(0.06) and ΔPINCH 0.02(0.03)] (p=0.002, p=0.009, p=0.003 and p=0.038, respectively). Conclusions: Gloreha Professional is feasible and effective in recovering fine manual dexterity and strength and reducing arm disability in sub-acute hemiplegic patients.

In vitro administration of ergothioneine failed to protect isolated ischaemic and reperfused rabbit heart

Ergothioneine, a natural thiol-containing molecule, has recently been proposed to protect the heart against damage caused by ischaemia and reperfusion. We investigated the possibility that ergothioneine can have a role in maintaining the myocardial thiol/disulfide balance and consequently also a protective effect against ischaemic and reperfusion injury. We used isolated Langendorff-perfused rabbit hearts subjected to 45 min global and total ischaemia followed by 30 min reperfusion at baseline coronary flow (22 ml/min). Ergothioneine was delivered at 10(-5) M and 10(-4) M 60 min before ischaemia and during reperfusion. Myocardial damage was determined in terms of mechanical function, creatine kinase (CK) and lactate release, energy phosphate stores and the occurrence of oxidative stress. In our experimental conditions the treatment was unable to prevent myocardial damage. Ergothioneine, independently from the dosage used, failed to: (i) increase recovery of developed pressure upon reperfusion (14.4 +/- 2.3 mmHg in control hearts vs. 10.3 +/- 2.9 and 12.5 +/- 2.3 mmHg in 10(-5) M and 10(-4) M ergothioneine treated hearts, respectively); (ii) decrease the rise in diastolic pressure (44.3 +/- 4.4 mmHg in control hearts vs. 49.8 +/- 5.8 and 48.0 +/- 7.7 mmHg in treated hearts); (iii) decrease the release of CK and lactate; (iv) increase the levels of adenosine triphosphate (ATP) and creatine phosphate (CP) in tissue upon reperfusion; (v) maintain ratio between oxidized and reduced forms of adenine nucleotide coenzyme, as index of aerobic metabolism; (vi) prevent the decline of reduced glutathione (GSH), or the accumulation of oxidized glutathione (GSSG) as an index of oxidative stress.