Zaburzenia erekcji w cukrzycy

Erectile dysfunction (ED) is one of the most prevalent chronic complications of diabetes, the one which is also severely impairing patients’ quality of life. However, it is also often undiagnosed and remains untreated. Erectile dysfunction in diabetes may result from vascular, neurological (autonomic neuropathy), hormonal (hypogonadism) and local lesions. Old age, sedentary lifestyle, obesity, dyslipidemia, hypertension, certain medications, smoking, alcohol abuse and depression are all important risk factors for ED development. International Index of Erectile Function-5 (IIEF-5) questionnaire is a useful self-administered tool for ED diagnosis. Management of ED includes improving blood glucose, blood pressure and lipids control as well as weight reduction, smoking cessation and decrease in alcohol intake. Psychological counselling should be offered to all patients. Phosphodiesterase inhibitors type 5 are drugs of choice, with sildenafil having been available for over 15 years. In majority (up to 70%) of patients these agents are effective in respect to improving erection quality. Other therapeutic options are prostaglandin E analog (alprostadil) injections or testosterone gel. In those patient in whom pharmacotherapy fails, medical devices or prosthesis can be used.Zaburzenia erekcji to jedno z najczęściej występujących i z najbardziej niekorzystnie wpływających na jakość życia chorych przewlekłych powikłań cukrzycy. Jest ono jednak nadal rzadko rozpoznawane i leczone. Zaburzenia prowadzące do zaburzeń wzwodu u chorych na cukrzycę mają złożony charakter, wyróżnia się czynniki naczyniowe, neurologiczne (neuropatia autonomiczna), hormonalne (hipogonadyzm) i miejscowe. Do czynników ryzyka wystąpienia zaburzeń erekcji zalicza się zaawansowany wiek, siedzący tryb życia, otyłość, zaburzenia lipidowe, nadciśnienie tętnicze, stosowanie określonych grup leków, palenie tytoniu, nadmierne spożywanie alkoholu, zaburzenia depresyjne. Standardowym narzędziem pomocnym w wykrywaniu zaburzeń wzwodu jest 5-punktowy skrócony kwestionariusz oceny zdrowia seksualnego mężczyzny International Index of Erectile Function-5 (IIEF-5). Zaleca się, aby u wszystkich pacjentów dążyć do optymalizacji kontroli glikemii, ciśnienia tętniczego, gospodarki lipidowej, u osób z nadwagą do redukcji masy ciała, u palaczy do porzucenia nałogu, a u osób nadużywających alkoholu do znacznego ograniczenia jego spożycia. U każdego chorego warto również rozważyć doradztwo psychologiczne. Lekami z wyboru w leczeniu zaburzeń erekcji są inhibitory fosfodiesterazy typu 5 (PDE5), jako pierwszy preparat tej grupy został wprowadzonym ponad 15 lat temu sildenafil; 60–70% pacjentów z cukrzycą leczonych tymi lekami zgłasza znaczącą poprawę w zakresie możliwości współżycia płciowego. Innymi możliwościami terapeutycznymi są stosowanie analogu prostaglandyny E1 (PGE1) alprostadylu podawanego w drodze iniekcji do ciała jamistego prącia oraz stosowanie preparatów testosteronu (najskuteczniejsze w postaci żelu). U osób, u których farmakoterapia nie jest skuteczna, istnieje możliwość stosowania próżniociągu lub leczenia zabiegowego (protezy)

In silico mapping of essential residues in the catalytic domain of PDE5 responsible for stabilization of its commercial inhibitors

Phosphodiesterase type 5 (PDE5) is an important enzyme associated with the hydrolysis of cyclic guanosine monophosphate (cGMP) to guanosine monophosphate (GMP). Due to the relevant role of second messenger cGMP as a mediator in many physiological processes, efforts have been converged to find a safe pharmacological approach, seeking a specific, selective and potent inhibitor of the PDE5 enzyme. There are five commercial drugs with potential for clinical use: tadalafil, sildenafil, avanafil, udenafil and vardenafil. Here, we applied molecular modeling to obtain different profiles of protein-ligand interactions by adopting distinct PDE5 structures, specifically PDBid:1XOZ and two extracted from molecular dynamics (MD) simulations. The results generated by molecular docking showed several possibilities for inhibitor interactions with the catalytic pocket. Tadalafil, sildenafil and vardenafil were clearly stabilized by Gln817 via a well-oriented hydrogen bond. Another set of different interactions, such as polar, hydrophobic, pi-stacking, metal-ligand and electrostatic, were responsible for accommodating avanafil and udenafil. All of the ligands are discussed in detail with consideration of the distinct protein structures, and a profile of the probability of residue-ligand contact is suggested, with the most frequently observed being: Tyr612, His613, Ser661, Thr723, Asp724, Asp764, Leu765, Val782 and Phe786. The molecular interactions displayed herein confirm findings achieved by previous authors and also present new contacts. In addition, the discussion can help researchers obtain a molecular basis for planning new selective PDE5 inhibitors, as well as explain an inhibitor's experimental assays by considering the specific interactions occurring at the catalytic site874CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP470374/2013-62010/16947-9; 2013/05475-7; 2013/08293-7; 2013/22360-9; 2017/26687-3; 2017/02201-

PHOSPHODIESTERASE-5 INHIBITION: A NOVEL STRATEGY TO IMPROVE STEM CELL THERAPY IN THE HEART

Several studies have shown cellular replacement therapy as a treatment strategy of myocardial infarction but results have been limited. Therefore, enhancing the therapeutic potential of stem cells injected into ischemic microenvironments by novel preconditioning (PC) techniques is critical for improving cellular therapy. Recent studies have shown that inhibition of phosphodiesterase-5 (PDE-5) is a powerful strategy to precondition the heart and cardiomyocytes against ischemia/reperfusion injury. We therefore tested the hypothesis that inhibition of PDE-5 with sildenafil (Viagra®) or selective knockdown with a silencing vector in adipose derived stem cells (ASCs) would improve their survival after ischemia/reoxygenation in vitro and enhance cardiac function following myocardial implantation in vivo. ASCs were treated with sildenafil or infected with PDE-5 silencing vector shRNA (shRNAPDE-5). The cells were subjected to simulated ischemia (SI) and reoxygenation (RO). Both sildenafil and shRNAPDE-5 significantly reduced cell injury, as shown by improved viability, decreased lactate dehydrogenase, and apoptosis. The preconditioned ASCs also demonstrated an increase in the release of growth factors including VEGF, b-FGF, and IGF. The protective effect against SI/RO injury was abolished by inhibition of protein kinase G (PKG) using both a pharmacological inhibitor and selective knockdown with shRNAPKG1α suggesting a PKG-mediated mechanism. To show the effect of preconditioned ASCs in vivo, adult male CD-1 mice underwent myocardial infarction (MI) by occlusion of the left descending coronary artery, followed by direct injection of PBS (control), non-preconditioned ASCs, or preconditioned ASCs (4x105) ASCs into the left ventricle (LV). Preconditioned ASC-treated hearts showed consistently superior cardiac function by all measures as compared with PBS and non-preconditioned ASCs after 4 weeks of treatment. Post-mortem histological analysis demonstrated that preconditioned ASC-treated mice had significantly reduced fibrosis, increased vascular density and reduced resident myocyte apoptosis as compared to mice receiving non-preconditioned ASCs or PBS. VEGF, b-FGF, and Ang-1 were also significantly elevated 4 weeks after cell therapy with preconditioned ASCs. Our data suggests that genetic or pharmacological inhibition of PDE-5 is a powerful new approach to improve stem cell therapy following myocardial infarction

Targeting the nitric oxide signalling pathway to modulate platelet function

Nitric oxide (NO) negatively regulates platelets and impaired NO signalling can lead to arterial thrombosis. The source of platelet-derived NO is unclear with recent proposals of NO synthase (NOS) independent NO sources, such as S-nitrosothiols (RSNOs) and inorganic nitrate/nitrite. Sildenafil citrate, a phosphodiesterase 5 (PDE5) inhibitor, enhances NO/cGMP signals in cells expressing PDE5 such as platelets. The aims of this study were to investigate the antiplatelet properties of sildenafil, its mechanism of action and to determine the upstream sources of NO affecting platelet function. The functional effect of sildenafil was determined using a range of in vitro and in vivo platelet assays. The mechanism of action of sildenafil and upstream sources of NO/cGMP signals were assessed pharmacologically using established methods of in vitro and in vivo platelet aggregation. Bioconversion of nitrate to nitrite was determined using gas-phase chemiluminescence. The functional significance of NO/cGMP signalling events in platelets were investigated in vivo in W.T and eNOS-/- (a model of vascular dysfunction) mice. Sildenafil exerted an antiplatelet effect by enhancing transient NO/cGMP signals generated by platelets independent of NOS activity in vitro. Inhibition of proposed mechanisms of NO release from RSNOs did not modify the inhibitory effect of sildenafil suggesting that RSNOs did not mediate platelet NO/cGMP signals. Nitrite was able to drive inhibitory cGMP signalling events in platelets in vitro. Furthermore, nitrate inhibited platelet function in eNOS-/- mice in vivo following enhanced bioconversion to nitrite, potentially as a compensatory mechanism due to impaired NO signalling. In conclusion, inorganic nitrate/nitrite may critically regulate platelets following bioconversion to NO and dietary sources of nitrate/nitrite may generate compensatory NO during vascular disease. Furthermore, sildenafil may be beneficial in reducing the risk of platelet-driven cardiovascular disease by enhancing NO/cGMP signalling derived from both enzymic and inorganic sources and restoring impaired NO signalling during endothelial dysfunction.Open Acces

Inhibition of phosphodiesterase type 5 in cardiovascular disease

Nitric oxide is released from the endothelium and causes relaxation of vascular smooth muscle by stimulating guanylate cyclase to produce guanosine 3’,5’-cyclic monophosphate (cGMP) which, in turn, is degraded by phosphodiesterase type 5 (PDE5). Inhibition of PDE5, with drugs like sildenafil citrate, promotes NOstimulated relaxation of vascular smooth muscle. The overall aim of the work contained within this thesis was to further characterise the systemic vascular effects of PDE5 inhibition. Four clinical studies were performed. The aims of the first study were to investigate in healthy men the effect of smoking on endothelium-dependent vasomotor function measured as the change in peripheral arterial wave reflection with inhaled salbutamol, and the effect of acute sildenafil 100 mg on this response. Smokers (n=12) exhibited a reduced response to inhaled salbutamol compared to non-smokers (n=11) [mean(standard deviation) area under the curve of the change in central augmentation index following salbutamol 400 μg: -29(143) AU in smokers vs -159(124) AU in non-smokers, P=0.03]. In the smokers, there was a trend to an improvement in the response to salbutamol following sildenafil [-96(266) AU vs -29(143) AU with matched placebo; P=0.2]. The co-administration of glyceryl trinitrate (GTN) and sildenafil is absolutely contraindicated because of the potential for profound hypotension. The aim of the second study was to characterise the time course of this interaction. Twenty men with stable angina, maintained on their usual medicines, were administered sublingual GTN 400 μg 1, 4, 6 and 8 hours after sildenafil 100 mg or matched placebo. Compared to the combination of GTN and placebo, the combination of GTN and sildenafil resulted in greater mean maximum reductions from baseline in sitting systolic blood pressure (BP) at 1, 4 and 8 hours, and in sitting diastolic BP at all time points (all P<0.05). Compared to placebo, sildenafil alone reduced systolic BP at 1, 4, 6 and 8 hours (P<0.01 at 1 hour and P<0.05 at 4, 6, and 8 hours) and diastolic BP at 4, 6, and 8 hours (all P<0.01). Analysis of the change in BP from the measures taken before each GTN challenge suggested that the interaction on BP might be synergistic at 1 hour after sildenafil, but no more than additive at 6 and 8 hours after sildenafil. Symptoms consistent with hypotension occurred following GTN in 6 subjects at 1 hour and 3 subjects at 4 hours after sildenafil, but in no subjects at 6 and 8 hours after sildenafil or at any time after placebo. In the third study, 25 otherwise untreated hypertensives were given sildenafil 50 mg or matched placebo three times daily for 16 days and the effects on ambulatory BP, clinic BP, arterial wave reflection, carotid-femoral pulse wave velocity and brachial artery flow-mediated dilatation were measured. Three subjects were withdrawn because of side effects and the data from the remaining 22 subjects were analysed. Sildenafil reduced ambulatory BP [change from baseline in average daytime BP: systolic -8(9) mmHg vs 2(9) mmHg with placebo, P<0.01; diastolic -6(5) mmHg vs 0(6) mmHg, P<0.01] and clinic BP [change from baseline to 1 hour after drug administration on day 16: systolic -5(11) mmHg vs 4(10) mmHg, P<0.01; diastolic -5(5) mmHg vs 2(7) mmHg, P<0.01]. Sildenafil, but not placebo, reduced arterial wave reflection [central augmentation index from 32(9)% at baseline to 30(10)% at 1 hour after administration on day 16, P<0.05; radial augmentation index from 88(13)% to 84(13)%, P<0.01], but the change in arterial wave reflection was not statistically significant compared to the change with placebo. Sildenafil did not affect pulse wave velocity or flow-mediated dilatation. The fourth study investigated the potential of combined PDE5 inhibition and organic nitrate for the management of treatment-resistant hypertension (TRH). In 6 patients with TRH, maintained on their usual antihypertensives sildenafil 50 mg alone, isosorbide mononitrate (ISMN) 10 mg alone and co-administered sildenafil and ISMN all acutely reduced systolic BP and diastolic BP compared to placebo (quantified as the area under the curve of the change from baseline to 4 hours after drug administration; all P≤0.01). The combination produced a greater reduction in systolic BP than did either sildenafil alone (P=0.03) or ISMN alone (P=0.01) and a greater reduction in diastolic BP than did sildenafil alone (P=0.02). Compared to placebo, from 1 to 3 hours after drug administration BP was on average 13/10 mmHg lower with sildenafil alone, 18/14 mmHg lower with ISMN alone and 26/18 mmHg lower with the combination. The following conclusions were made. (1) Smokers exhibit impaired vascular responsiveness to inhaled salbutamol, indicating systemic endothelial dysfunction, which may be improved by sildenafil. (2) In men with stable angina there is an interaction on BP reduction between sildenafil 100 mg and sublingual GTN 400 μg for at least 8 hours after sildenafil administration, but this interaction is no more than additive from 6 hours after sildenafil administration. (3) Regular sildenafil monotherapy reduces BP in hypertension. (4) In patients with TRH maintained on their usual antihypertensives sildenafil alone and ISMN alone both acutely reduce BP and there is additional BP reduction when these drugs are given in combination

EPR Effect-Based Tumor Targeted Nanomedicine

I am honored to undertake the work for Guest Editor for this Special Issue of EPR Effect-Based Tumor Targeted Nanomedicine for the Journal of Personalized Medicine. It has already been 35 years since we published the concept of the EPR effect for the first time. The discovery of the new concept of EPR effect gave an impetus effect of growth momentum in nanomedicine, and numerous works are focused on tumor delivery, although the initial idea was based on vascular permeability in infection-induced inflamed tissue, where we discovered bradykinin in the key mediator of vascular permeability.I know, however, there are pros and cons to EPR effect. Cons stem either from a poor understanding of EPR effect, or somehow a biased view of the EPR effect, or from the tumor models being used, particularly in the clinical settings where vascular blood flow is so frequently obstructed. I hope scientists in the clinic, or basic researchers working on the tumor drug delivery, will join the forum of this Special Issue and express their data and opinions.The scope of this issue includes an in-depth understanding of the EPR effect, and issues associated with tumor microenvironment and also further exploitation of EPR effect in human cancer. In addition, new strategies for enhancement of the EPR effect using nanomedicine will be welcome, which is as important as the EPR effect itself. These papers cover not only cancer therapy, but also imaging techniques using nanofluorescent agents, including photodynamic therapy for inflammation, and boron neutron capture therapy