Angiotensin converting enzyme (ACE) catalyzes the conversion of angiotensin I (Ang I) to angiotensin II (AngII). ACE also cleaves the terminal dipeptide of vasodilating hormone bradykinin (a nonapeptide) to its inactive form. Therefore, inhibition of ACE is one of the treatments of hypertension. A number of ACE inhibitory antihypertensive drugs are known. ‘Oxidative stress’ is another disease state caused by an imbalance in the production of oxidants and antioxidants in the body. A number of studies suggest that hypertension and oxidative stress are interdependent. Therefore, ACE inhibitors having antioxidant property are considered beneficial for the treatment of hypertension. Generally, selenium compounds exhibit better antioxidant behavior than their sulfur analogues. Therefore, we have synthesized a number of selenium analogues of captopril, an ACE inhibitor used as antihypertensive drug. Similar to captopril, the selenium analogues of captopril exhibited excellent ACE inhibition property. It was observed that these compounds are very good scavengers of peroxynitrite (PN), a strong oxidizing as well as nitrating agent found in vivo. The orientation of the chiral centers in these compounds was found to be very important for their ACE inhibition behavior. A number of selenocysteine- and cysteine-containing dipeptides and tripeptides were synthesized as inhibitors of ACE. It was observed that the ACE inhibition properties of these compounds depend on various factors such as orientation of the amino functionality, substitution at the C-terminal of the inhibitor, ring size of the proline moiety or the availability of the terminal acid group in carboxylate form etc. A structure-function correlation was drawn for the ACE inhibition properties of the peptide-based selenium-or sulfur-containing compounds. These studies reveal that the antioxidant properties do not depend on the side-chain functional groups, but they depend on the availability of selenium or sulfur centers. Selenium-based compounds were found to be better antioxidants than those containing sulfur moieties. In conclusion, the present study reveals that the replacement of sulfur atom in captopril and its analogues by selenium enhances the antioxidant activity. The reaction products of lactoperoxidase (LPO)-catalyzed iodination of Ang II were separated and characterized. It was observed that LPO-catalyzed iodination of Ang II takes place preferentially at the tyrosine residue. LPO-catalyzed iodination of Ang II is inhibited by commonly used antithyroid drugs such as MMI, MTU, PTU and also by antihypertensive drug captopril. It was also observed that the monoiodo Ang I is a better substrate for ACE compared to the natural substrate Ang I. The site of nitration of Ang II by PN was also determined by MS-MS analyses. This study reveals that the nitration takes place at the tyrosine residue.

Obesity is strongly associated with hypertension and cardiovascular diseases. An activated renin-angiotensin system (RAS) has long been suggested as a critical contributor to elevated blood pressure with obesity. Angiotensin II (AngII), the main effector of an activated RAS, can be catabolized by angiotensin-converting enzyme 2 (ACE2) to form angiotensin-(1-7) (Ang-(1-7)), which, acting through the mas receptor (MasR), has been shown to oppose the effects of an activated RAS. Therefore, further understanding of the mechanisms of this counter-regulatory arm, called the ACE2/Ang-(1-7)/MasR axis, may lead to new therapies for obesity-induced hypertension. Previously, we demonstrated that differences in the regulation of ACE2 in a tissue-specific manner contribute to sexual dimorphism of diet-induced obesity-hypertension in mice. Whereas male mice fed a high fat (HF) diet developed hypertension, HF-fed female mice were protected from obesity-hypertension, and this was associated with increased activity of ACE2 in adipose tissue of females. Both upregulation of adipose ACE2 and protection against obesity-hypertension were lost when females were ovariectomized (OVX). We hypothesized that estrogen-mediated increases in adipose ACE2 reduce the AngII/Ang-(1-7) peptide balance and protect females from obesity-hypertension. To test this hypothesis, we first determined if estrogen restores protection of Ovx female mice from obesity-hypertension, and therapeutically protects male mice from obesity-hypertension. We demonstrated that estrogen administration to Ovx HF-fed females activates adipose ACE2, reduces plasma Ang II concentrations, and decreases blood pressure in wildtype, but not of ACE2-deficient obese females. In contrast, estrogen administration to HF-fed male mice had no on the development of obesity-hypertension, regardless of genotype. These results demonstrate that estrogen protects female mice from obesity-hypertension through an ACE2-dependent mechanism. Next we defined the role of MasR deficiency on the development of obesity-hypertension in male and female mice. In HF-fed MasR-deficient female mice, diastolic blood pressure (DBP) was significantly elevated compared to LF-fed controls, suggesting that protection from obesity-hypertension was abolished by MasR deficiency. In contrast, HF-fed male mice with MasR deficiency exhibited reduced blood pressure compared to wildtype controls which was associated with reduced cardiac function. Overall, these studies indicate that the ACE2/Ang-(1-7)/MasR axis plays an important role in sexual dimorphism of obesity-hypertension, and in the regulation of cardiac function. Moreover, these studies suggest that the effects of this counter-regulatory arm of the RAS may be sex-specific.

Os inibidores da enzima conversora da angiotensina são uma classe de medicamentos freqüentemente prescrita pelos médicos e importante para o tratamento da Hipertensão Arterial Sistêmica (HAS) e da Insuficiência Cardíaca Congestiva (ICC). Os dois primeiros protótipos desta classe, o captopril e o maleato de enalapril, constam na Relação Nacional de Medicamentos Essenciais (RENAME) devido à importância terapêutica, eficácia clínica e segurança comprovada, além de seu custo-efetividade. Para cumprir o objetivo de estudar a utilização desta classe terapêutica foi realizado um levantamento no banco de dados da Secretaria Municipal de Saúde de Ribeirão Preto (SMS-RP) do estado de São Paulo (SP) para identificar os usuários do Sistema Único de Saúde (SUS) que receberam a dispensação de captopril e maleato de enalapril pelas farmácias das Unidades Básicas de Saúde (UBS) e Distritais de Saúde (UBDS) no período compreendido entre 01/03/2006 e 28/02/2007. Identificou-se que 9.560 pacientes utilizaram os inibidores da ECA, sendo que destes, 46,57% utilizaram captopril, 45,74% enalapril e 7,69% os dois fármacos simultaneamente ou não. A idade média dos usuários foi de 61 anos e houve um aumento progressivo da utilização desses agentes com o incremento da faixa etária e houve predominância para o gênero feminino. A aderência ao tratamento dos usuários das unidades de saúde do Distrito Oeste de Ribeirão Preto foi estimada em 80,6%. Enquanto que a dispensação única dos inibidores da ECA foi encontrada para 8,6% dos indivíduos, com idade média de 53,5 anos e as doses médias prescritas de captopril e de enalapril foram de 63,8 mg e 19,8 mg/dia respectivamente. Por outro lado, as doses médias prescritas e mantidas de captopril foram de 69,9 mg/dia e de enalapril foram de 21,35 mg/dia. Aproximadamente 0,3% dos pacientes utilizaram captopril em doses médias prescritas e mantidas iguais ou superiores a 150 mg e 0,65% dos pacientes receberam doses de enalapril acima de 40 mg, porém não foram encontradas doses subterapêuticas prescritas para esses medicamentos. Além disso, 20,21% dos pacientes analisados neste estudo tiveram seus esquemas terapêuticos alterados, sendo que a maioria teve apenas uma alteração. Um total de 92,69% dos usuários utilizou mais de um medicamento além dos inibidores da ECA e o incremento desse valor foi diretamente proporcional a faixa etária. O número de pacientes com risco de apresentar interação medicamentosa foi de 3.974 (41,57%), sendo que a maioria dos pacientes utilizou apenas um medicamento com essa possibilidade. / The angiotensin-converting enzyme inhibitors is a class of drugs often prescribed by pharmacian and important for the treatment of systemic arterial hypertension (SAH) and the Congestive Heart Failure (CHF). The first two prototypes of this class, enalapril maleate and captopril, are in the National Essential Drugs (RENAME) because of their therapeutic importance, clinical efficacy and safety established, and its cost-effectiveness. The aim of this study was reached through a survey database of the Municipal Health Secretary of Ribeirão Preto (SMS-RP) of São Paulo (SP) state to identify the users of the Unified Health System (SUS) that received dispensation of captopril and enalapril maleate by the basics health units (UBS) and districts health units (UBDS) for the period between 01/03/2006 and 28/02/2007. It was identified that 9,560 patients used ACE inhibitors, of which, 46.57% used captopril, 45.74% enalapril and 7.69% these two drugs simultaneously or not. The average age of users was 61 years and there was a progressive increase in the use of these agents with increasing age. The treatment adherence was estimated at 80.6% in users of health care units in the Western District of Ribeirão Preto. A single dispensing of ACE inhibitors was found for 8.6% of individuals with a mean age of 53,5 years and mean dose of 63.8 mg and the average prescribed doses of captopril were 69.9 and 19.8 mg/day respectively. Furthermore, the mean doses prescribed and maintained for captopril was 69.9 mg/day and enalapril were 21.35 mg/day. Around 0.3% of patients used average prescribed and maintained captopril doses equal or greater than 150 mg and 0.65% of patients received enalapril doses above 40 mg, but there were no prescribed subtherapeutic doses of these drugs. Moreover, 20.21% of patients analyzed in this study had their treatment regimens modified, and the majority had only one change. A total of 92.69% of users used more than one drug than the ACE inhibitors and the increase of this value was directly proportional to age. The number of patients with potential risk of a potential drug interaction was 3,974 (41.57%), and the most patients used only one drug with possibility.

A MMP-2 é uma protease que está envolvida em muitos eventos fisiológicos e patológicos e que compartilha similaridades estruturais com a enzima conversora de angiotensina (ECA), de modo que os inibidores da ECA passaram a ser estudados com relação ao efeito inibitório também sobre a MMP-2. No entanto, este potencial inibitório não foi ainda testado na MMP-2 altamente purificada. Este estudo teve como objetivo investigar o potencial inibitório do captopril sobre a atividade da MMP- 2. Primeiramente, supôs-se que a dissolução do captopril poderia induzir a mudanças no pH de soluções tampão. Em segundo lugar, avaliou-se o efeito direto do captopril sobre a MMP-2 presente no plasma humano e a MMP-2 recombinante humana (rhMMP-2) produzida e purificada de E. coli. As análises de atividade in vitro incluíram zimogramas com gelatina e ensaios fluorimétricos com DQ gelatin. A solubilização do captopril reduziu significativamente o pH da solução tampão 50 mM (p<0,01) mas não alterou o pH da solução tampão 200 mM (p>0,05). Resultados de zimografia do plasma e da rhMMP-2 mostraram inibição da atividade gelatinolítica com significância estatística somente em concentrações iguais ou maiores que 4 e 1 mM de captopril, respectivamente (p<0,05). A presença de captopril nos ensaios de fluorimetria resultaram na inibição significante da atividade de rhMMP-2 somente em concentrações iguais ou maiores que 2 mM (p<0,01), enquanto a rhMMP-2 ativada com APMA apresentou inibição significativa diante de 0,5 mM de captopril (p<0,01). As concentrações de captopril efetivas em inibir a MMP-2 in vitro foram muito superiores àquelas referentes à concentração plasmática máxima encontrada no plasma humano após a administração de uma dose de 50 mg de captopril. Em conjunto nossos resultados sugerem que o captopril não parece promover inibição significativa da MMP-2 nas concentrações relatadas in vivo. Além disso, o pH das soluções tamponantes é um aspecto que requer mais atenção durante ensaios de inibição de protease in vitro. / MMP-2 is involved in many physiological and pathological processes. This protease shares structural similarities with the angiotensin-converting enzyme (ACE), and ACE inhibitors have been described to inhibit MMP-2. However, this inhibitory potential has not been tested using a highly purified MM-2 so far. This study aimed at investigating the inhibitory potential of captopril on MMP-2 activity. First it was tested whether the dissolution of captopril would induce changes in the pH of the solutions. Secondly, the direct inhibitory effect of captopril on plasma MMP-2 and on a recombinant human MMP-2 (rhMMP-2) produced and purified from E. coli was tested. The in vitro activity assays included gelatin zymography and a fluorimetric assay with DQ gelatin. Captopril solubilization significantly decreased the pH of the 50 mM Tris buffer solution (p<0.01) but did not decreased the pH of the 200 mM Tris Buffer solution (p>0.05). Zymography results of plasma and rhMMP-2 showed that inhibition of the activity only reached statistical significance >= 4 and 1 mM of captopril, respectively (p<0,05). The presence of captopril in the fluorimetric assay resulted in a significant inhibition of the rhMMP-2 activity only at concentrations >= 2 mM (p<0.01), whereas APMA-activated rhMMP-2 was inhibited by 0.5 mM of captopril (p<0.01). The captopril concentrations found to inhibit MMP-2 are several times of magnitude higher than the maximum plasma concentration after a dose of 50 mg of captopril. In conclusion, captopril does not seem to cause significant inhibition of MMP-2 in the concentrations found in vivo, and more attention has to be given to the pH of the solutions when testing protease inhibition in vitro.

A doença periodontal (DP) compreende um grupo de lesões que afetam os tecidos periodontais de proteção (gengivite) e suporte (periodondite), envolvendo a participação de células residentes, células estruturais e mediadores inflamatórios. Pesquisas recentes mostram a existência de um Sistema Renina Angiotensina (SRA) local no tecido gengival de ratos e sugeriram que o SRA está envolvido na iniciação da progressão da DP induzida experimentalmente em ratos. Portanto, o objetivo deste trabalho foi avaliar se o enalapril, inibidor da enzima conversora de angiotensina (ECA), reduz a perda óssea e a expressão de componentes do SRA no tecido gengival. Para tanto foi utilizado o modelo de indução da DP por colocação de ligadura ao redor do primeiro molar inferior de ratos e tratamento destes animais com enalapril (20 mg/kg/dia, gavage), sendo utilizado micro CT para análise do volume ósseo. Os grupos experimentais foram os seguintes (n = 5): Grupo 1 - pré-tratamento com enalapril por 14 dias, indução da DP e pós-tratamento por 14 dias; Grupo 2 pré-tratamento com enalapril por 14 dias, indução da DP e pós-tratamento por 7 dias; Grupo 3 - pré-tratamento com enalapril por 7 dias, indução da DP e pós-tratamento por 14 dias; Grupo 4 - pré-tratamento com enalapril por 7 dias, indução da DP e pós-tratamento por 7 dias. Para fins de comparação, em todos os grupos, além do tratamento com enalapril, outros animais receberam água (n = 5) e em outros (n = 5) foi realizada cirurgia fictícia para indução da DP (sham). Foram realizadas análises de perda óssea alveolar e reação em cadeia da polimerase quantitativa (qPCR) dos seguintes componentes do SRA como Angiotensinogênio (AGT), ECA, ECA-2 e dos receptores AT1a, AT1b, AT2 e Mas). Os dados foram devidamente analisados por meio de gráficos, sendo utilizado o teste t para comparação dos animais tratados com enalapril ou água com os respectivos sham, adotando-se o nível de significância de 5%. Os resultados demonstraram que apenas no grupo com o menor tempo de pré-tratamento com o enalapril (Grupo 3) não houve bloqueio da perda óssea, porém nos demais grupos houve diminuição de forma estatisticamente significativa deste parâmetro (Grupos 1, 2 e 3). Em relação à análise molecular, de todos os alvos testados, apenas a expressão do AGT e receptor Mas foi alterada, com aumento estatisticamente significativo da expressão do RNAm para esta enzima identificado no grupo 4. Em conclusão, o pré-tratamento com enalapril, inibidor da ECA, pode prevenir a perda óssea alveolar no modelo de DP induzida experimentalmente em ratos. / Periodontal disease (PD) comprises a group of injuries affecting the periodontal tissue protection (gingivitis) and support (periodondite), involving the participation of resident cells, structural cells and inflammatory mediators. Recent research has shown the existence of a Renin Angiotensin System (RAS) site in the gingival tissue of rats and suggested that the SRA is involved in the onset of progression of PD experimentally induced in rats. Therefore, the aim of this study was to evaluate whether enalapril, angiotensin converting enzyme (ACE), bone loss and reduces the expression of RAS components in the gingival tissue. For this model was used for induction of PD placement of ligature around the mandibular first molar of rats and treatment of these animals with enalapril (20 mg / kg / day gavage) being used for micro-CT analysis of bone volume. The experimental groups were as follows (n = 5 each): Group 1 - the pre-enalapril treatment for 14 days, and DP induction of post-treatment for 14 days, Group 2 - the pre-enalapril treatment for 14 days, induction of DP and after treatment for 7 days and Group 3 - pre-enalapril treatment for 7 days, induction of PD-and post-treatment for 14 days, and Group 4 - the pre-enalapril treatment for 7 days, induction of post-treatment DP, and for 7 days. For comparison, all groups, and treatment with enalapril other animals received water (n = 5) and other (n = 5), sham surgery was performed to induce PD (sham). Analyses of alveolar bone loss and polymerase chain reaction quantitative (qPCR) of the following RAS components (angiotensinogen, ACE, ACE-2 receptor and AT1a, AT1b, AT2 and Mas). The data were properly analyzed by means of graphs, by using the t test for comparison of animals treated with enalapril or water with their sham, adopting a significance level of 5%. The results showed that only in the group with the shortest pre-treatment with enalapril (Group 3) showed no blocking of bone loss, but the other groups was statistically significant decrease in this parameter (Groups 1, 2 and 3). Regarding the molecular analysis of all targets tested, only the expression of angiotensinogen and Mas receptor was altered, with a statistically significant increase in the expression of mRNA for this enzyme identified in group 4. In conclusion, pre-treatment with enalapril ACE inhibitor can prevent bone loss in PD model experimentally induced in rats.

A MMP-2 é uma protease que está envolvida em muitos eventos fisiológicos e patológicos e que compartilha similaridades estruturais com a enzima conversora de angiotensina (ECA), de modo que os inibidores da ECA passaram a ser estudados com relação ao efeito inibitório também sobre a MMP-2. No entanto, este potencial inibitório não foi ainda testado na MMP-2 altamente purificada. Este estudo teve como objetivo investigar o potencial inibitório do captopril sobre a atividade da MMP- 2. Primeiramente, supôs-se que a dissolução do captopril poderia induzir a mudanças no pH de soluções tampão. Em segundo lugar, avaliou-se o efeito direto do captopril sobre a MMP-2 presente no plasma humano e a MMP-2 recombinante humana (rhMMP-2) produzida e purificada de E. coli. As análises de atividade in vitro incluíram zimogramas com gelatina e ensaios fluorimétricos com DQ gelatin. A solubilização do captopril reduziu significativamente o pH da solução tampão 50 mM (p<0,01) mas não alterou o pH da solução tampão 200 mM (p>0,05). Resultados de zimografia do plasma e da rhMMP-2 mostraram inibição da atividade gelatinolítica com significância estatística somente em concentrações iguais ou maiores que 4 e 1 mM de captopril, respectivamente (p<0,05). A presença de captopril nos ensaios de fluorimetria resultaram na inibição significante da atividade de rhMMP-2 somente em concentrações iguais ou maiores que 2 mM (p<0,01), enquanto a rhMMP-2 ativada com APMA apresentou inibição significativa diante de 0,5 mM de captopril (p<0,01). As concentrações de captopril efetivas em inibir a MMP-2 in vitro foram muito superiores àquelas referentes à concentração plasmática máxima encontrada no plasma humano após a administração de uma dose de 50 mg de captopril. Em conjunto nossos resultados sugerem que o captopril não parece promover inibição significativa da MMP-2 nas concentrações relatadas in vivo. Além disso, o pH das soluções tamponantes é um aspecto que requer mais atenção durante ensaios de inibição de protease in vitro. / MMP-2 is involved in many physiological and pathological processes. This protease shares structural similarities with the angiotensin-converting enzyme (ACE), and ACE inhibitors have been described to inhibit MMP-2. However, this inhibitory potential has not been tested using a highly purified MM-2 so far. This study aimed at investigating the inhibitory potential of captopril on MMP-2 activity. First it was tested whether the dissolution of captopril would induce changes in the pH of the solutions. Secondly, the direct inhibitory effect of captopril on plasma MMP-2 and on a recombinant human MMP-2 (rhMMP-2) produced and purified from E. coli was tested. The in vitro activity assays included gelatin zymography and a fluorimetric assay with DQ gelatin. Captopril solubilization significantly decreased the pH of the 50 mM Tris buffer solution (p<0.01) but did not decreased the pH of the 200 mM Tris Buffer solution (p>0.05). Zymography results of plasma and rhMMP-2 showed that inhibition of the activity only reached statistical significance >= 4 and 1 mM of captopril, respectively (p<0,05). The presence of captopril in the fluorimetric assay resulted in a significant inhibition of the rhMMP-2 activity only at concentrations >= 2 mM (p<0.01), whereas APMA-activated rhMMP-2 was inhibited by 0.5 mM of captopril (p<0.01). The captopril concentrations found to inhibit MMP-2 are several times of magnitude higher than the maximum plasma concentration after a dose of 50 mg of captopril. In conclusion, captopril does not seem to cause significant inhibition of MMP-2 in the concentrations found in vivo, and more attention has to be given to the pH of the solutions when testing protease inhibition in vitro.

No description available.

Diet-induced obesity promotes type 2 diabetes (T2D). Drugs that inhibit the renin-angiotensin system (RAS) have been demonstrated in clinical trials to decrease the onset of T2D. Previously, we demonstrated that mice made obese from chronic consumption of a high-fat (HF) diet have marked elevations in systemic concentrations of angiotensin II (AngII). Pancreatic islets have been reported to possess components of the renin-angiotensin system (RAS), including angiotensin type 1a receptors (AT1aR), the primary receptor for AngII, and angiotensin converting-enzyme 2 (ACE2), which negatively regulates the RAS by catabolizing AngII to angiotensin-(1-7) (Ang-(1-7)). These two opposing proteins have been implicated in the regulation of β-cell function. We hypothesized that the RAS contributes to the decline of β-cell function during the development of T2D with obesity. To test this hypothesis we first examined the effects of whole-body deficiency of ACE2 in mice on β-cell function in vivo and in vitro during the development of T2D. Whole-body deficiency of ACE2 resulted in impaired β-cell adaptation to insulin resistance with HF-feeding and a reduction of in vivo glucose-stimulated insulin secretion (GSIS) associated with reduced β- cell mass and proliferation. These results demonstrate that ACE2 plays a role in the adaptive response to hyperinsulinemia with obesity. In islets from HF-fed mice, AngII inhibited GSIS. In mice with pancreatic-specific deletion of AT1aR, AngII-induced inhibition of GSIS in vitro from islets of HF-fed mice was abolished. However, there was no effect of pancreatic AT1aR-deficiency on glucose homeostasis in vivo in HF-fed mice exhibiting pronounced hyperinsulinemia. Notably, pancreatic weight, insulin content and basal and glucose-stimulated insulin secretion from islets were decreased in mice with pancreatic AT1aR deficiency. These results suggest that AT1aR may contribute to pancreatic cell development, and also contribute to AngII-induced reductions in GSIS from islets of HF-fed mice. Overall, these studies suggest a role for the RAS in the regulation of β-cell function in T2D.

No description available.

Το γονίδιο του ανθρώπινου μετατρεπτικού ενζύμου της αγγειοτενσίνης ACE περιέχει έναν πολυμορφισμό δύο αλληλομόρφων που αποτελείται είτε από την παρουσία (I) είτε από την απουσία (D) ενός τμήματος 287 ζευγών βάσεων (bp). Πρόσφατες μελέτες έχουν προτείνει ότι το αλληλόμορφο Ι, μπορεί να σχετίζεται με απόδοση σχετιζόμενη με τη μυϊκή αντοχή. Αντιθέτως, το αλληλόμορφο D γονίδιο έχει συσχετισθεί με απόδοση σχετιζόμενη με τη μυϊκή ισχύ. Επιπλέον, έχει καταδειχθεί ότι η δραστικότητα του κυκλοφορούντος ACE (cACE) συσχετίζεται ευθέως με τη μυική ισχύ σε υγιείς ενήλικες. Η φυσιολογία και η βιοχημεία των αναπνευστικών μυών είναι παρόμοια με αυτή των σκελετικών μυών. Επομένως, η λειτουργικότητα των αναπνευστικών μυών και ιδίως του διαφράγματος, του πλέον σημαντικού αναπνευστικού μυ, μπορεί να επηρεάζεται αναλόγως. Η κόπωση των αναπνευστικών μυών μπορεί να οδηγεί σε αδυναμία διατήρησης του απαραίτητου κυψελιδικού αερισμού. Διάφορες μέθοδοι έχουν χρησιμοποιηθεί για να αξιολογηθούν οι ιδιότητες αντοχής των αναπνευστικών μυών. Ο διαφραγματικός δείκτης πίεσης-χρόνου (PTIdi) και ο μη επεμβατικός δείκτης πίεσης-χρόνου των αναπνευστικών μυών (PTImus), είναι δύο μέθοδοι εκτίμησης της αντοχής του διαφράγματος και των αναπνευστικών μυών, αντίστοιχα. Έχουν χρησιμοποιηθεί σε ενήλικες και παιδιά και έχουν τεκμηριωθεί σε νεογνά. Η διαφραγματική ισχύς και η ισχύς των αναπνευστικών μυών στα νεογνά μπορεί να αξιολογηθούν ειδικά με τη μέτρηση της μέγιστης δια-διαφραγματικής πίεσης (Pdimax) και της μεγίστης εισπνευστικής πίεσης αεραγωγών (Pimax), αντίστοιχα. Σκοπός. Να εξετασθεί η πιθανή συσχέτιση του πολυμορφισμού I/D του ACE και του κυκλοφορούντος ACE με την λειτουργικότητα του διαφράγματος και των αναπνευστικών μυών σε νεογνά. Δευτερεύων σκοπός ήταν ο προσδιορισμός της κατανομής του πολυμορφισμού I/D του ACE στον συγκεκριμένο πληθυσμό και η συσχέτισή του με την δραστικότητα του cACE. Υλικό και Μέθοδοι. Μελετήθηκαν νεογνά που είχαν εισαχθεί στην Μονάδα Εντατικής Νοσηλείας Νεογνών- Παιδιατρική κλινική του Πανεπιστημίου Πατρών. Τα Ι και D αλληλόμορφα του γονιδίου του ACE προσδιορίστηκαν με αλυσιδωτή αντίδραση πολυμεράσης (PCR amplification) σε DNA το οποίο εξήχθη από 0,5 mL ολικού αίματος. Η δραστηριότητα του ACE ορού αξιολογήθηκε με τη χρησιμοποίηση μιας UV κινητικής μεθόδου. Η αντοχή του διαφράγματος και των αναπνευστικών μυών εκτιμήθηκαν με μέτρηση του διαφραγματικού δείκτη πίεση-χρόνου (PTIdi) και του δείκτη πίεσης-χρόνου των αναπνευστικών μυών (PTImus), αντίστοιχα. Η διαφραγματική ισχύς και η ισχύς των αναπνευστικών μυών στα νεογνά αξιολογήθηκαν με μέτρηση της μέγιστης δια-διαφραγματικής πίεσης (Pdimax) και της μεγίστης εισπνευστικής πίεσης αεραγωγών (Pimax), αντίστοιχα. Αποτελέσματα. Συνολικά εξετάστηκαν 171 νεογνά. Στην πρώτη μελέτη της διατριβής μελετήθηκαν 148 νεογνά, στην δεύτερη μελέτη 132 και στην τρίτη μελέτη 110 νεογνά. Η κατανομή του πολυμορφισμού του ACE στο συγκεκριμένο πληθυσμό βρέθηκε κοντά σε προηγούμενα αναφερόμενα στοιχεία. Τα νεογνά με Ι/Ι γονότυπο είχαν χαμηλότερο PTIdi και PTImus από τα νεογνά με γονοτύπους είτε D/D ή I/D. Η ανάλυση των επιμέρους στοιχείων των PTIdi και PTImus έδειξε ότι μόνο οι λόγοι Pdimean (μέση διαδιαφραγματική πίεση) προς Pdimax και Pimean (μέση πίεση αεραγωγών) προς Pimax, αντίστοιχα, ήταν χαμηλότεροι σε νεογνά με γονότυπο I/I έναντι των νεογνών με γονοτύπους είτε D/D είτε I/D. Οι Pdimax και Pimax δεν ήταν στατιστικά διαφορετικές ανάμεσα στις τρείς ομάδες. Ανάλυση βηματικής παλινδρόμησης κατέδειξε σημαντική συσχέτιση των γονότυπων του ACE με τις τιμές του PTIdi και του PTImus, ανεξαρτήτως παραγόντων που θα μπορούσαν να επηρεάσουν την λειτουργικότητα του διαφράγματος και των αναπνευστικών μυών. Νεογνά με το D/D γονότυπο είχαν αυξημένη δραστικότητα ACE ορού σε σχέση με νεογνά με I/I ή I/D γονοτύπους. Η δραστικότητα του cACE σχετιζόταν σημαντικά ευθέως με τη Pimax και αντιστρόφως με το PTImus. Συμπεράσματα. Στις μελέτες αυτής της διατριβής ανεδείχθη συσχέτιση ανάμεσα στους γονοτύπους του ACE και την αντοχή του διαφράγματος και γενικότερα των αναπνευστικών μυών όπως αξιολογείται με τη μέτρηση των PTIdi και PTImus, αντίστοιχα, σε νεογνά. Δεν ανεδείχθη συσχέτιση ανάμεσα στους γονοτύπους του ACE και την ισχύ του διαφράγματος και γενικότερα των αναπνευστικών μυών όπως αξιολογείται με τη μέτρηση των Pdimax και Pimax, αντίστοιχα, σε αυτό τον πληθυσμό. Εντούτοις, κατεδείχθη μια θετική συσχέτιση μεταξύ της δραστικότητας του ACE ορού και της ισχύος των αναπνευστικών μυών, όπως αυτή αξιολογείται από μετρήσεις της Pimax , και μια αρνητική συσχέτιση ανάμεσα στη δραστικότητα του ACE ορού και του PTImus. Επιπλέον, δείχθηκε μια συσχέτιση του αλληλόμορφου D γονιδίου του γονοτύπου ACE με την αυξημένη δραστικότητα του cACE στα νεογνά. / The human ACE (angiotensin converting enzyme) gene contains a polymorphism consisting of either the presence (insertion, I) or absence (deletion, D) of a 287 base pair (bp) fragment. Recent studies have suggested that the I-allele may be associated with endurance performance. Conversely, D-allele has been associated with power-oriented performance. Moreover, it has been suggested that circulating ACE (cACE) activity is correlated with muscle strength in healthy adults. The physiological and biochemical properties of the respiratory and skeletal muscles are quite similar. Therefore, respiratory muscle and specific diaphragmatic function, may be similarly influenced. Fatigue of respiratory muscles may result in inability to maintain adequate alveolar ventilation. Several methods have been used to assess the endurance properties of respiratory muscles. Diaphragmatic pressure-time index (PTIdi) and the non-invasive pressure-time index of respiratory muscles (PTImus), are two methods of assessment of diaphragmatic and respiratory muscle endurance, respectively. They have been validated in both adults and infants. Diaphragmatic and respiratory muscle strength in infants can be assessed specifically, by measurement of maximum transdiaphragmatic pressure (Pdimax) and maximum inspiratory pressure (Pimax), respectively. Aims. To examine the possible association of the I/D genotypes of ACE and cACE, with diaphragmatic and respiratory muscle performance, in infants. Secondary aims were to identify the distribution of the I/D genotypes of ACE in the specific population and its association with cACE activity. Material and methods. Infants cared for at the Neonatal Intensive Care Unit- Paediatric Department of the University General Hospital of Patras, Greece, were eligible for the study. ACE genotyping was performed by polymerase chain reaction amplification on DNA, extracted from 0,5 ml of whole blood. Serum ACE activity was assayed by using a UV-kinetic method. The endurance of the diaphragm and the respiratory muscles was assessed by measurement of diaphragmatic pressure-time index (PTIdi) and pressure-time index of the respiratory muscles (PTImus), respectively. Diaphragmatic and respiratory muscle strength was assessed by measurement of maximum transdiaphragmatic (Pdimax) and maximum inspiratory (Pimax) pressures, respectively. Results. One hundred seventy one infants were recruited. One hundred fourty eight infants were included in the first study, one hundred thirty two in the second study and one hundred ten in the third study of this thesis. The distribution of the I/D genotypes of ACE in the specific population was close to previous reported data. Infants with I/I ACE genotype had lower PTIdi and PTImus than infants with either D/D or I/D genotypes. Analysis of the components of the PTIdi and PTImus has shown that the ratios of Pdimean to Pdimax and Pimean to Pimax , only, were lower in infants with the I/I genotype, compared to infants with either the D/D or I/D genotypes. Neither Pdimax, nor Pimax were statistically different between the three groups. A stepwise regression analysis revealed that ACE genotypes were significantly related to the PTIdi and PTImus measurements, independent of other factors that may affect diaphragmatic and respiratory muscle function. Infants with D/D genotype had significantly higher serum ACE activity than infants with I/I or I/D genotypes. Circulating ACE activity was significantly related to Pimax and inversely related to PTImus. Conclusions. In the studies of this thesis, an association between ACE genotypes and the endurance of the diaphragm and the respiratory muscles, assessed by measurement of PTIdi and PTImus, respectively, was demonstrated, in infants. No such association was demonstrated between ACE genotypes and strength of the diaphragm and the respiratory muscles, assessed by measurement of Pdimax and Pimax, respectively, in the specific population. However, a positive correlation between serum ACE activity and respiratory muscle strength, assessed by measurement of Pimax and and a negative correlation between serum ACE activity and PTImus, was shown. Moreover, an association of D-allele of ACE genotype with increased circulating ACE activity in infants, was demonstrated.