Author Correction: Impact of sacubitril/valsartan on implantable defibrillator eligibility in heart failure: a real-world experience.

Correction to: European Review for Medical and Pharmacological Sciences 2021; 25 (18): 5690-5700-DOI: 10.26355/eurrev_202109_26788-PMID: 34604961, published online on 30 September 2021. After publication, the authors applied to change the first two lines of Table II as the second column results were erroneously shifted in the first column. In this way, the results were quite difficult to understand. There are amendments to this paper. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/26788.

Impact of sacubitril/valsartan on implantable defibrillator eligibility in heart failure: a real-world experience.

OBJECTIVE: Current guidelines recommend an implantable cardiac defibrillator (ICD) in patients with symptomatic heart failure and reduced ejection fraction (HFrEF; left ventricular ejection fraction [LVEF] ≤35%) despite ≥3 months of optimal medical therapy. Recent observations demonstrated that sacubitril/valsartan induces beneficial reverse cardiac remodeling in eligible HFrEF patients. Given the pivotal role of LVEF in the selection of ICD candidates, we sought to assess the impact of sacubitril/valsartan on ICD eligibility and its predictors in HFrEF patients. PATIENTS AND METHODS: We retrospectively evaluated 48 chronic HFrEF patients receiving sacubitril/valsartan and previously implanted with an ICD in primary prevention. We assumed that ICD was no longer necessary if LVEF improved >35% (or >30% if asymptomatics) at follow-up. RESULTS: Over a median follow-up of 11 months, sacubitril/valsartan induced a significant drop in LV end-systolic volume (-16.7 ml/m2, p=0.023) and diameter (-6.8 mm, p=0.022), resulting in a significant increase in LVEF (+3.9%, p<0.001). As a consequence, 40% of previously implanted patients resulted no more eligible for ICD at follow-up. NYHA class improved in 50% of the population. A dose-dependent effect was noted, with higher doses associated to more reverse remodeling. Among patients deemed no more eligible for ICD, lower NYHA class (odds ratio (OR) 3.73 [95% CI 1.05; 13.24], p=0.041), better LVEF (OR 1.23 [95% CI 1.01; 1.48], p=0.032) and the treatment with the intermediate or high dose of sacubitril/valsartan (OR 5.60 [1.15; 27.1], p=0.032) were the most important predictors of status change. CONCLUSIONS: In symptomatic HFrEF patients, sacubitril/valsartan induced beneficial cardiac reverse remodeling and improved NYHA class. These effects resulted in a significant reduction of patients deemed eligible for ICD in primary prevention.

Echocardiographic long-term follow-up of adult survivors of pediatric cancer treated with Dexrazoxane-Anthracyclines association.

AIMS: Cardiovascular disease is a well-recognized cause of increased late morbidity and mortality among survivors of childhood cancer treated with anthracyclines. Co-administration of Dexrazoxane has been shown to significantly reduce short-term and mid-term cardiotoxicity. Aim of this study was to assess cardiac function in long-term (>10 years) survivors of childhood tumors treated with dexrazoxane/anthracycline association. METHODS AND RESULTS: Twenty cancer survivors previously treated with co-administration of anthracyclines-dexrazoxane for childhood renal tumors or sarcoma and a control group of 20 healthy subjects were enrolled in the study. Echocardiographic measurements included 3D left ventricular (LV) ejection fraction (LVEF) and LV and right ventricular (RV) global longitudinal strain (GLS). Among cancer survivors group the median age at diagnosis was 5 years (1-17) and they were evaluated at median follow-up time of 21.5 years (10-26). No evidence of cardiac toxicity, as defined by current guidelines, was reported in all survivors. No significant differences in standard and deformation imaging parameters were observed between survivors and controls (3D LVEF 58 ±â€¯3% vs 60 ±â€¯5% p = NS; LV GLS -21 ±â€¯1% vs -21 ±â€¯2% p = NS; RV GLS -23 ±â€¯2% vs -23 ±â€¯5% p = NS). No second tumor was registered in dexrazoxane-treated survivors. CONCLUSIONS: Our findings may support the role of dexrazoxane as a useful strategy for cardio-protection in children undergoing anthracycline based treatment. However, large randomized trials are needed to confirm the cardio-protective role of dexrazoxane in pediatric setting at long-term follow-up.

A mitochondrial perspective on cell death.

The role of mitochondria as crucial participants in cell death programs is well established, yet the mechanisms responsible for the release of mitochondrial activators and the role of BCL2 family proteins in this process remain controversial. Here, we point out the limitations of current approaches used to monitor the physiological responses of mitochondria during cell death, the implications arising from modern views of mitochondrial structure, and briefly assess two proposed mechanisms for the release of mitochondrial proteins during apoptosis.

p66SHC promotes T cell apoptosis by inducing mitochondrial dysfunction and impaired Ca2+ homeostasis.

p66Shc, a redox enzyme that enhances reactive oxygen species (ROS) production by mitochondria, promotes T cell apoptosis. We have addressed the mechanisms regulating p66Shc-dependent apoptosis in T cells exposed to supraphysiological increases in [Ca2+]c. p66Shc expression resulted in profound mitochondrial dysfunction in response to the Ca2+ ionophore A23187, as revealed by dissipation of mitochondrial transmembrane potential, cytochrome c release and decreased ATP levels. p66Shc expression also caused a dramatic alteration in the cells' Ca2+-handling ability, which resulted in Ca2+ overload after A23187 treatment. The impairment in Ca2+ homeostasis was ROS dependent and caused by defective Ca2+ extrusion due at least in part to decreased plasma membrane ATPase (PMCA) expression. Both effects of p66Shc required Ca2+-dependent serine-36 phosphorylation. The mitochondrial effects of p66Shc were potentiated by but not strictly dependent on the rise in [Ca2+]c. Thus, Ca2+-dependent p66Shc phosphorylation causes both mitochondrial dysfunction and impaired Ca2+ homeostasis, which synergize in promoting T cell apoptosis.

Enhancement of anxiety, facilitation of avoidance behavior, and occurrence of adult-onset obesity in mice lacking mitochondrial cyclophilin D.

In this report, we have assessed the behavioral responses of mice missing the Ppif gene (CyPD-KO), encoding mitochondrial cyclophilin D (CyPD). Mitochondrial CyPD is a key modulator of the mitochondrial permeability transition which is involved in the regulation of calcium- and oxidative damage-induced cell death. Behavioral screening of CyPD-KO mice (ranging between 4 and 15 months of age) was accomplished using a battery of behavioral paradigms which included testing of motor functions, exploratory activity, and anxiety/emotionality, as well as learning and memory skills. We found that, compared with wild-type mice, CyPD-KO mice were (i) more anxious and less explorative in open field and elevated plus maze and (ii) performed better in learning and memory of avoidance tasks, such as active and passive avoidance. However, the absence of CyPD did not alter the nociceptive threshold for thermal stimuli. Finally, deletion of CyPD caused also an abnormal accumulation of white adipose tissue resulting in adult-onset obesity, which was not dependent on increased food and/or water intake. Taken together, our results suggest a new fundamental role of mitochondrial CyPD in basal brain functions and body weight homeostasis.

A patch-clamp study of Bacillus subtilis.

In patch-clamp experiments on giant protoplasts of the Gram-positive bacterium Bacillus subtilis, membrane stretch resulted in an initial transient collapse of the membrane resistance, after which stretch-activated, voltage modulated, high-conductance channels could be observed. The channel open probability increased exponentially with applied suction and positive voltage, as a result of variations of both the mean open and the mean closed times. The substate structure and other characteristics of the electrical activity suggested the presence of a family of pores exhibiting cooperative behavior. A role in osmotic protection is suggested. In the intact bacteria, the pores may be part of an unidentified envelope apparatus, having other functions as well.

ATP synthase-mediated proton fluxes and phosphorylation in rat liver mitochondria: dependence on delta mu H.

The dependence of the proton flux through the ATP synthases of rat liver mitochondria on a driving force composed mainly of a potassium diffusion potential was determined and compared with the relationship between rate of phosphorylation and delta mu H given by titrations with the respiratory inhibitor malonate. The two functions are in good agreement in the lower part of the delta mu H range covered. However, the maximal proton fluxes through the ATP synthases are much lower than needed to account for the rate of State 3 phosphorylation sustained by the same mitochondria oxidizing succinate. Possible reasons for this behavior are discussed.

Analysis of mechanisms of free-energy coupling and uncoupling by inhibitor titrations: theory, computer modeling and experiments.

The rates of ATP synthesis and of ATP-driven NAD reduction have been measured in bovine heart submitochondrial particles as a function of the fraction of inhibited redox pumps (in titrations with either antimycin or rotenone) and of the fraction of inhibited ATPases (in titrations with DCCD). The flux control coefficients of the redox and ATPase proton pumps on the rates of ATP synthesis and of ATP-driven NAD reduction have been derived and found to be equal to 1 for both pumps; i.e., both pumps appear to be 'completely rate limiting'. A theoretical analysis of the inhibitor titration approach based on kinetic models of chemiosmotic coupling and on the theory of metabolic control is presented. This analysis (i) shows that the results of the single inhibitor titrations are incompatible with a delocalized chemiosmotic mechanism of energy coupling if the proton conductance of the membrane is sufficiently low with respect to the conductances of the pumps; and (ii) suggests an experimental approach based on the determination of the P/O and the respiratory control ratios at different degrees of inhibition of the proton pumps to establish the origin of the 'loose coupling' of submitochondrial particle preparations. Three independent types of observation show that the 'loose coupling' of the particle preparation is not mainly due to an increased membrane proton conductance. The same and other independent observations are consistent with the view that the loose coupling of submitochondrial particle preparation is due mainly to inhomogeneity, i.e. to the presence of a subpopulation of highly leaky non-phosphorylating vesicles respiring at maximal rate. The results as a whole together with the simulations and analysis presented lead to the conclusion that the mechanism of free-energy coupling in submitochondrial particles is not completely delocalized.

Nigericin-induced transient changes in rat-liver mitochondria.

Addition of nigericin to mitochondria oxidizing succinate in a choline- and Tris-supplemented, low-KCl medium leads to a transient matrix acidification, followed by a return of pHin to values very close to pHout. The initial inhibition of stimulated respiration is gradually relieved as pHin returns to higher values. Matrix realkalinization depends on the operation of the H+ pumps and on the electrogenic influx of cations and efflux of anions. The process leads to replacement of much of the matrix K+ by other cations. Throughout the acidification/realkalinization cycle delta mu H variations, if any, are small, even though there are profound changes in the relative contributions of its two components, delta psi and delta pH.

Regulation of the permeability transition pore, a voltage-dependent mitochondrial channel inhibited by cyclosporin A.

Mitochondria from a variety of sources possess a regulated inner membrane channel, the permeability transition pore (MTP), which is responsible for the 'permeability transition', a sudden permeability increase to solutes with molecular masses < or = 1500 Da, most easily observed after Ca2+ accumulation. The MTP is a voltage-dependent channel blocked by cyclosporin A with Ki in the nanomolar range. The MTP open probability is regulated by both the membrane potential and matrix pH. The probability of pore opening increases as the membrane is depolarized, while it decreases as matrix pH is decreased below 7.3 through reversible protonation of histidine residues. Many physiological and pathological effectors, including Ca2+ and ADP, modulate MTP operation directly through changes of the gating potential rather than indirectly through changes of the membrane potential (Petronilli, V., Cola, C., Massari, S., Colonna, R. and Bernardi, P. (1993) J. Biol. Chem. 268, 21939-21945). Here we present recent work from our laboratory indicating that (i) the voltage sensor comprises at least two vicinal thiols whose oxidation-reduction state affects the MTP gating potential; as the couple becomes more oxidized the gating potential increases; conversely, as it becomes more reduced the gating potential decreases; (ii) that MTP opening is fully reversible, as mitochondria maintain volume homeostasis through several cycles of pore opening/closure; and (iii) that the mechanism of MTP inhibition by cyclosporin A presumably involves a mitochondrial cyclophilin but does not utilize a calcineurin-dependent pathway.

The role of mitochondria in the salvage and the injury of the ischemic myocardium.

The relationships between mitochondrial derangements and cell necrosis are exemplified by the changes in the function and metabolism of mitochondria that occur in the ischemic heart. From a mitochondrial point of view, the evolution of ischemic damage can be divided into three phases. The first is associated with the onset of ischemia, and changes mitochondria from ATP producers into powerful ATP utilizers. During this phase, the inverse operation of F0F1 ATPase maintains the mitochondrial membrane potential by using the ATP made available by glycolysis. The second phase can be identified from the functional and structural alterations of mitochondria caused by prolongation of ischemia, such as decreased utilization of NAD-linked substrates, release of cytochrome c and involvement of mitochondrial channels. These events indicate that the relationship between ischemic damage and mitochondria is not limited to the failure in ATP production. Finally, the third phase links mitochondria to the destiny of the myocytes upon post-ischemic reperfusion. Indeed, depending on the duration and the severity of ischemia, not only is mitochondrial function necessary for cell recovery, but it can also exacerbate cell injury.

Flow-force relationships during energy transfer between mitochondrial proton pumps.

The effect of inhibitors of proton pumps, of uncouplers and of permeant ions on the relationship between input force, delta mu H+, and output flows of the ATPase, redox and transhydrogenase H(+)-pumps in submitochondrial particles was investigated. It is concluded that: (1) The decrease of output flow of the transhydrogenase proton pump, defined as the rate of reduction of NADP+ by NADH, is linearily correlated with the decrease of input force, delta mu H+, in an extended range of delta mu H+, independently of whether the H(+)-generating pump is the ATPase or a redox pump, or whether delta mu H+ is depressed by inhibitors of the H(+)-generating pump such as oligomycin or malonate, or by uncouplers. (2) The output flows of the ATPase and of the site I redox H(+)-pumps exhibit a steep dependence on delta mu H+. The flow-force relationships differ depending on whether the depression of delta mu H+ is induced by inhibitors of the H(+)-generating pump, by uncouplers or by lipophilic anions. (3) With the ATPase as H(+)-consuming pump, at equivalent delta mu H+ values, the output flow is more markedly inhibited by malonate than by uncouplers; the latter, however, are more inhibitory than lipophilic anions such as ClO4-. With redox site I as proton-consuming pump, at equivalent delta mu H+ values, the output flow is more markedly inhibited by oligomycin than by uncouplers; again, uncouplers are more inhibitory than ClO4-. (4) The results provide further support for a delocalized interaction of transhydrogenase with other H(+)-pumps.

Apoptosis to necrosis switching downstream of apoptosome formation requires inhibition of both glycolysis and oxidative phosphorylation in a BCL-X(L)- and PKB/AKT-independent fashion.

Human T-lymphoma Jurkat cells treated with several intrinsic death stimuli readily undergo a stepwise apoptotic program. Treatment with 1,9-dideoxyforskolin (ddFSK), an inactive analogue of the adenylate cyclase activator forskolin, induces necrotic cell death and switches to necrosis the response to the apoptosis inducers in Jurkat and in other cell models. Yet, in the presence of ddFSK, mitochondrial changes are enhanced and apoptosome formation takes place. We show that ddFSK does not inhibit the catabolic steps of apoptosis, but rather elicits a profound ATP depletion that in turn tunes the mode of cell demise towards necrosis. Treatment with ddFSK impairs both glycolysis and oxidative phosphorylation in a Bcl-X(L)- and PKB/Akt-independent fashion, and inhibition of both processes is needed to affect apoptosis progression. Apoptosis is not blocked per se by ATP depletion, as engagement of the Fas receptor directly activates caspases, thus bypassing ddFSK inhibition.

Ion-conducting channels in a gram-positive bacterium.

The patch-clamp technique was used to obtain information on the existence and properties of ion channels in giant protoplasts obtained from the Gram-positive bacterium Streptococcus faecalis. The membrane proved to contain a pore with numerous conductance states, ranging from 10 pS to several nanosiemens. Application of a slight pressure differential across the membrane resulted in the activation of the channel. The pressure sensitivity points to a relationship between this channel and one recently discovered in E. coli spheroplasts [(1987) Proc. Natl. Acad. Sci. USA 84, 2297-2301] suggesting that pores of this type might be widespread among prokaryotes.

Multiple relationships between rate of oxidative phosphorylation and delta microH in rat liver mitochondria.

The relationship between rate of ATP synthesis and transmembrane electrochemical proton gradient has been determined in rat liver mitochondria oxidizing succinate, using the respiratory inhibitor malonate or the uncoupler FCCP to decrease delta microH progressively. As previously reported [(1982) Eur. J. Biochem. 126, 443-451] two different relationships are obtained depending on the method used. Evidence is presented that this result is not due to underestimation of the delta microH maintained by fast-respiring mitochondria, as recently suggested [(1985) FEBS Lett. 181, 323-327].

The inner mitochondrial membrane contains ion-conducting channels similar to those found in bacteria.

Patch-clamp experiments were performed on rat liver mitochondria inner membranes. Application of voltage gradients of either polarity revealed the presence of several different conductances, ranging up to 1.3 nS in symmetrical 150 mM KCl. Evidence is presented that at least those higher than 0.3 nS are substates of the highest conductance channel. Increasing matrix-side-positive (unphysiological) transmembrane voltage gradients favored the switch of the 1.3 nS channel to operation in lower conductance states. The size of these conductances, the presence of substates and the channel behavior are strongly reminiscent on one hand of the observations on the membrane of protoplasts from the gram-positive bacterium Streptococcus faecalis, [Zoratti, M. and Petronilli, V. (1988) FEBS Lett. 240, 105-109], and on the other of some properties of previously described channels of mitochondrial origin.

Inhibition of the mitochondrial cyclosporin A-sensitive permeability transition pore by the arginine reagent phenylglyoxal.

The mitochondrial permeability transition pore, a cyclosporin A-sensitive channel, is controlled by the transmembrane electric potential difference across the inner membrane. Here, we show that treatment of rat liver mitochondria with the arginine reagent phenylglyoxal inhibits the permeability transition pore triggered by depolarization with uncoupler after Ca2+ accumulation. Phenylglyoxal does not change the extent of mitochondrial Ca2+ uptake or the extent of membrane depolarization, indicating that covalent modification of arginine (and possibly lysine) residues directly affects the open probability of the pore. We propose that arginine residues play a role in the physiological control of the permeability transition pore by the mitochondrial transmembrane potential.

Selective inhibition of the mitochondrial permeability transition pore at the oxidation-reduction sensitive dithiol by monobromobimane.

In this paper we introduce monobromobimane, a thiol reagent, as a selective blocker of the recently identified dithiol whose oxidation-reduction status modifies voltage sensing by the mitochondrial permeability transition pore, a cyclosporin A-sensitive channel. Monobromobimane does not inhibit the phosphate carrier, nor does it interfere with Ca2+ transport, energy coupling or ATP production and transport. We show that monobromobimane selectively prevents the shift in pore gating potential caused by some dithiol oxidants or crosslinkers but not by increasing [Ca2+], allowing a clear distinction of the pore agonists which act at this site.

On the effects of paraquat on isolated mitochondria. Evidence that paraquat causes opening of the cyclosporin A-sensitive permeability transition pore synergistically with nitric oxide.

This paper reports an investigation on the effects of the bipyridylium herbicide, paraquat, on rat liver mitochondria in vitro. We show that paraquat induces a Ca(2+)-dependent permeability increase of the inner mitochondrial membrane leading to membrane depolarization, uncoupling and matrix swelling. The permeability increase is not observed in the absence of Ca2+ accumulation, and is not due to a direct effect of paraquat on the membrane energy level, as assessed by measurements of membrane potential, respiration and mitochondrial permeability to solutes at high concentrations of paraquat in the presence of excess ethylene-bis(oxoethylenenitrilo)tetraacetic acid (EGTA), a Ca2+ chelator. The Ca(2+)-dependent permeability increase is due to inappropriate opening of the endogenous permeability transition pore (MTP), a regulated, voltage-dependent channel of the inner mitochondrial membrane. The pore is primarily affected by paraquat through a shift of the gating potential to more negative values, allowing pore opening at physiological membrane potential. This effect apparently involves oxidation of a critical dithiol in the pore voltage sensor, while other regulatory aspects of the MTP (matrix pH and Ca2+) are unaffected by paraquat, which is not transported inside the mitochondrial matrix. The effects of paraquat on MTP opening depend on inhibition of electron transfer at Site I by rotenone, or by respiratory chain inhibition by nitric oxide, one of the proposed endogenous mediators of paraquat toxicity to the lung (Berisha, H.I., Hedayatollah, P., Absood, A., and Said, S.I. (1994) Proc. Natl. Acad. Sci. USA 91, 7445-7449). Taken together, these data provide an additional biochemical mechanism by which paraquat may affect cell function, and support the idea that mitochondrial damage is an important determinant in paraquat toxicity (Hirai, K.-I., Ikeda, K., and Wang, G.-Y. (1992) Toxicology 72, 1-16).