RESUMEN
PURPOSE OF REVIEW: Hypertension affects approximately 10% of pregnancies and may persist in the postpartum period. Furthermore, de novo hypertension may present after delivery, but its exact prevalence is not verified. Both types of hypertension expose the mother to eventually severe complications like eclampsia, stroke, pulmonary edema, and HELLP (hemolysis, elevated liver enzymes, low platelet) syndrome. RECENT FINDINGS: Until today, there are limited data regarding the risk factors, pathogenesis, and pathophysiology of postpartum hypertensive disorders. However, there is certain evidence that preeclampsia may in large part be responsible. Women who experienced preeclampsia during pregnancy, although considered cured after delivery and elimination of the placenta, continue to present endothelial and renal dysfunction in the postpartum period. The brain and kidneys are particularly sensitive to this pathological vascular condition, and severe complications may result from their involvement. Large randomized trials are needed to give us the evidence that will allow a timely diagnosis and treatment. Until then, medical providers should increase their knowledge regarding hypertension after delivery because many times there is an underestimation of the complications that can ensue after a misdiagnosed or undertreated postpartum hypertension.
Asunto(s)
Eclampsia , Síndrome HELLP , Hipertensión , Preeclampsia , Femenino , Humanos , Hipertensión/tratamiento farmacológico , Periodo Posparto , EmbarazoRESUMEN
Heart rate is an important factor in coronary artery disease and its manifestations, and as such has been considered as a possible target for therapy. Although in epidemiological, and in less degree, in clinical studies derived indications of a possible pathogenetic role of heart rate in major cardiac diseases, clinical trials did not provided any strong evidence. However, even as a simple risk marker, remains important in the treatment of coronary artery disease and heart failure. Beta-blockers are the drugs most frequently used for heart rate control. However, recent studies constantly find insufficient effectiveness of beta-blockers in heart rate control and go further to question their efficacy on outcomes, making clear the need for an additional therapy. Ivabradine, a pure heart rate inhibitor, added to classic beta-blocker treatment represent the new therapeutic option in stable coronary disease and heart failure.
Asunto(s)
Antagonistas Adrenérgicos beta/uso terapéutico , Fármacos Cardiovasculares/uso terapéutico , Enfermedad de la Arteria Coronaria/tratamiento farmacológico , Ivabradina/uso terapéutico , Metoprolol/uso terapéutico , Animales , Combinación de Medicamentos , Frecuencia Cardíaca/efectos de los fármacos , HumanosRESUMEN
Preeclampsia (PE) is one of the leading causes of maternal and fetal morbidity and mortality, with incidence rates ranging between 2 and 5 % in the Western World. The exact causes of the disease remain largely unknown, because of the complex pathophysiologic mechanisms involved in the process. Genetic, environmental, and epigenetic parameters have been implicated by various authors as culprits for the pathogenesis of PE. Recent reports in the literature highlight the paternal role. Still, the exact extent and mechanism remain elusive. In this systematic review, we attempt to present data regarding the paternal role in a concise and comprehensive manner.
Asunto(s)
Preeclampsia , Femenino , Humanos , Padres , Guías de Práctica Clínica como Asunto , Preeclampsia/fisiopatología , EmbarazoRESUMEN
Inevitably, a small proportion of patients with systematic hypertension will develop hypertensive crisis at some point. Hypertensive crises can be divided into hypertensive emergency or hypertensive urgency according to the presence or lack of acute target organ damage. In this review, we discuss cardiovascular hypertensive emergencies, including acute coronary syndrome, aortic dissection, congestive heart failure, and sympathomimetic hypertensive crises, including those caused by cocaine use. Each presents in a unique fashion, although some hypertensive emergency patients report nonspecific symptoms. Treatment includes several effective and rapid-acting medications to safely reduce the blood pressure, protect remaining end-organ function, relieve symptoms, minimize the risk of complications, and thereby improve patient outcomes.
Asunto(s)
Antihipertensivos/uso terapéutico , Enfermedades Cardiovasculares/tratamiento farmacológico , Hipertensión/tratamiento farmacológico , Determinación de la Presión Sanguínea , Servicios Médicos de Urgencia , HumanosRESUMEN
Hypertensive complications in pregnancy are the leading cause of maternal morbidity, at least in the developed countries. In recent years, infertility issues are managed with ever growing therapeutic options namely assisted reproductive technologies (ART), which improve the ratio of successful induction of pregnancy. It is still debated whether various ART modalities are associated with adverse pregnancy outcomes, including hypertensive complications, particularly with higher incidence of preeclampsia. The main source of controversy stems from the diversity of effect modifiers modulating the association between ART-oriented pregnancy and hypertensive disorders. Indeed, women undergoing an ART procedure are affected by diverse causes of infertility, are frequently characterized by different genetic patterns with respect to their artificially conceived embryo and experienced multiple gestations. In order to investigate whether ART modalities are associated with increased incidence of hypertensive complications in pregnancy, we reviewed all published studies carried out before the end of 2010 and identified in the PubMed database. Among the 47 studies finally selected and by acknowledging the potential of shortcomings related to the different study design and populations, the overall evidence suggests that ART-oriented pregnancies-especially the in-vitro fertilization techniques-are accompanied by increased risk for gestational hypertension and preeclampsia as compared with non-ART pregnancies, even after adjustment for confounders. Multiple gestations, advanced age and underlying polycystic ovary syndrome resulted in constant confounders of the questioned association. Reducing multiple gestations by implementing single embryo techniques might be the therapeutic limiting step to lower the rate of hypertensive complications in assisted pregnancies.
Asunto(s)
Presión Sanguínea , Hipertensión Inducida en el Embarazo/etiología , Técnicas Reproductivas Asistidas/efectos adversos , Factores de Confusión Epidemiológicos , Femenino , Humanos , Hipertensión Inducida en el Embarazo/mortalidad , Hipertensión Inducida en el Embarazo/fisiopatología , Hipertensión Inducida en el Embarazo/prevención & control , Edad Materna , Síndrome del Ovario Poliquístico/complicaciones , Embarazo , Embarazo Múltiple , Técnicas Reproductivas Asistidas/mortalidad , Medición de Riesgo , Factores de RiesgoAsunto(s)
Amlodipino/uso terapéutico , Antihipertensivos/uso terapéutico , Hidroclorotiazida/uso terapéutico , Hipertensión/tratamiento farmacológico , Hipertensión/epidemiología , Imidazoles/uso terapéutico , Síndrome Metabólico/epidemiología , Tetrazoles/uso terapéutico , Amlodipino/farmacología , Antihipertensivos/farmacología , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Índice de Masa Corporal , Comorbilidad , Quimioterapia Combinada , Determinación de Punto Final , Humanos , Hidroclorotiazida/farmacología , Hipertensión/fisiopatología , Imidazoles/farmacología , Estilo de Vida , Síndrome Metabólico/fisiopatología , Tetrazoles/farmacología , Resultado del TratamientoRESUMEN
OBJECTIVE. Recent evidence demonstrates that masked hypertension (MH) is a significant predictor of cardiovascular disease. The aim of our study was to examine the impact of MH on haemostasis parameters and to compare the findings to those of healthy normotensives matched for age, sex, body mass index and the rest of risk factors. DESIGN AND METHOD. 130 (60 male, 70 female) healthy subjects mean age 45 ± 12 years who had clinic blood pressure < 140/90 mmHg were studied. The whole study population underwent 24-h ambulatory blood pressure monitoring (ABPM). According to the ABPM recordings, 24 individuals (eight males, 16 females) had MH (daytime systolic blood pressure ≥ 135 mmHg or daytime diastolic blood pressure ≥ 85 mmHg - group A) and the remaining 106 subjects (52 males, 54 females) had normal ABPM recordings - group B. Fibrinogen, thrombomodulin ™, the antigens of plasminogen activator inhibitor 1 (PAI-1Ag) and tissue plasminogen activator (tPA-Ag) were determined in the two groups. Results. The PAI-1 Ag, tPA-Ag, fibrinogen and TM levels were significantly higher in the masked hypertensive group than to normotensive control group. CONCLUSIONS. Our findings suggest that subjects with MH have significantly higher fibrinogen, TM, PAI-1Ag and tPA-Ag plasma levels compared with normotensives. This observation may have prognostic significance for future cardiovascular events in subjects with MH and needs further investigation.
Asunto(s)
Hipertensión/fisiopatología , Antígenos/sangre , Presión Sanguínea/fisiología , Enfermedades Cardiovasculares/sangre , Enfermedades Cardiovasculares/etiología , Estudios de Cohortes , Femenino , Fibrinógeno/metabolismo , Hemostasis , Humanos , Hipertensión/sangre , Hipertensión/complicaciones , Masculino , Persona de Mediana Edad , Inhibidor 1 de Activador Plasminogénico/inmunología , Trombomodulina/metabolismo , Activador de Tejido Plasminógeno/inmunologíaRESUMEN
We investigated whether the resistin (Res) and adiponectin (Adp) levels are associated with different clinical blood pressure (BP) phenotypes. Among 465 consecutive never-treated white subjects, we excluded those with diabetes mellitus; impaired glucose metabolism; history of any cardiovascular disease or other concurrent medical condition; secondary hypertension; ongoing vasoactive treatment. Three separate clinic BP measurements and ambulatory BP monitoring were implemented to divide 328 subjects (aged 48±6 years; 172 males) into hypertensives (n=105), masked hypertensives (n=41), white-coat hypertensives (n=52) and normotensives (n=130). Participants underwent echocardiography and oral glucose tolerance testing, whereas, from fasting venous blood samples metabolic profile, plasma Res and Adp levels were assessed. Hypertensives and masked hypertensives showed higher log(10)(Res) and lower log(10)(Adp) levels compared with normotensives, whereas white-coat hypertensives had similar levels of these adipokines compared with normotensives. Common correlates for both of the adipokines were 24-h systolic BP, standing/sitting difference of both diastolic BP and heart rate, and waist circumference. Hypertensive and masked hypertensive compared with normotensive phenotype were independently associated with log(10)(Res) with odds ratios of 1.24 (1.08-1.44), and 1.16 (1.09-1.34) and log(10)(Adp) with 0.74 (0.65-0.87), and 0.81 (0.67-0.95), respectively. Increased Res and decreased Adp plasma levels are associated with out-of-clinic hypertension, whereas they did not determine white-coat hypertension.
Asunto(s)
Adiponectina/sangre , Presión Sanguínea/fisiología , Hipertensión/sangre , Fenotipo , Resistina/sangre , Adulto , Enfermedades Cardiovasculares/epidemiología , Estudios Transversales , Femenino , Humanos , Hipertensión/complicaciones , Hipertensión/fisiopatología , Modelos Logísticos , Masculino , Persona de Mediana Edad , Visita a Consultorio Médico , Factores de RiesgoRESUMEN
INTRODUCTION: The aim of our study was to investigate whether collagen degradation is altered in participants with masked hypertension and whether this alteration could be related to disturbances in the matrix metalloproteinases plasma concentration and to compare the findings with those participants with normal blood pressure levels matched for age, sex, and body mass index. METHODS: Twenty-four (11 men, 13 women) participants with masked hypertension [mean age 46 +/- 7 years and body mass index 25.9 +/- 2.1 kg/m(2) (group A)] and 106 healthy normotensives (49 men, 57 women) with normal blood pressure [mean age 44 +/- 6 years and body mass index 25.5 +/- 2.4 kg/m(2) (group B)]. RESULTS: The plasma levels of matrix metalloproteinase-9 were significantly higher, while the levels of tissue inhibitors of metalloproteinases-1 and -4 were significantly lower in group A compared with group B (matrix metalloproteinase-9: 569 +/- 135 vs. 282 +/- 117 ng/mL, TIMP-1: 169 +/- 42 vs. 230 +/- 37 ng/mL, P < .01, and TIMP-4: 2.1 +/- 1.3 vs. 4.2 +/- 1.98 ng/mL, P < .04, respectively). CONCLUSIONS: Patients with masked hypertension had significantly increased matrix metalloproteinase-9 plasma levels and significantly decreased plasma levels of tissue inhibitors of metalloproteinases-1 and -4 compared with participants with normal blood pressure. These findings need further investigation.
Asunto(s)
Presión Sanguínea/fisiología , Hipertensión/enzimología , Metaloproteasas/sangre , Adulto , Biomarcadores/sangre , Monitoreo Ambulatorio de la Presión Arterial , Índice de Masa Corporal , Progresión de la Enfermedad , Ensayo de Inmunoadsorción Enzimática , Femenino , Estudios de Seguimiento , Humanos , Hipertensión/fisiopatología , Masculino , Persona de Mediana Edad , Índice de Severidad de la EnfermedadRESUMEN
UNLABELLED: Recent evidence demonstrate that masked hypertension (MH) is a significant predictor of cardiovascular disease, while, elevated levels of circulating antibodies against endothelial cell surface antigens (antiendothelial cell antibodies - AECA) seem to play an important role at the early stages of atherosclerosis process and of borderline hypertension as well. Aim of this study was to investigate the presence of AECA in patients (pts) with MH and to compare the AECA title among pts with MH and healthy normotensives (HN), matched for age, sex and body mass index. METHODS: One hundred-thirty (60 M, 70 F) healthy subjects mean age 45+/-12 yrs who had clinic blood pressure <140/90 mm Hg were studied. The whole study population underwent 24 hour ambulatory blood pressure monitoring (ABPM). According to the ABPM recordings, 24 individuals (8 M, 16 F) had MH (daytime systolic blood pressure >/=135 mm Hg or daytime diastolic blood pressure >/=85 mm Hg - group A) and the remainder 106 subjects (52 M, 54 F) had normal ABPM recordings, group B. IgG and IgM AECA levels were determined by ELISA method. AECA levels were expressed as mean value+/-SD. None of the study population had a history of connective tissue disease or any metabolic disorder. RESULTS: Significantly increased titles of AECA class IgG were found in 8/24 pts of group A (30%) vs. 5/106 (4.6%) of group B (p<0,001). Significantly increased titles of AECA class IgM were also found in 6/24 pts of group A (25%) vs. 3/80 (3.8%) of group B (p<0,001). CONCLUSIONS: Our results suggest that patients with MH have significantly higher AECA levels of both classes (IgG, IgM) compared to healthy normotensives. These findings may indicate a possible explanation of the increased cardiovascular risk in MH. The possibility that high AECA levels may be a driving mechanism for the development of MH needs further investigation.
Asunto(s)
Aterosclerosis/inmunología , Autoanticuerpos/sangre , Células Endoteliales/inmunología , Hipertensión/inmunología , Adulto , Aterosclerosis/epidemiología , Presión Sanguínea , Femenino , Humanos , Hipertensión/epidemiología , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Masculino , Persona de Mediana Edad , Factores de Riesgo , Estudios SeroepidemiológicosRESUMEN
Matrix metalloproteinases (MMP) degrade myocardial fibrillar collagen in acute myocardial infarction (MI) patients. Their activity is tightly controlled in normal myocardium by a family of closely related tissue inhibitors known as TIMP. An imbalance in their activity might contribute to post-MI remodeling. Plasma levels of MMP-1, TIMP-1 and MMP-1/TIMP-1 complex were measured, using relevant ELISA kits, in 24 (22 males-2 females), acute MI patients with a mean age 59 +/- 14 years. Blood samples were taken on admission (0 h), and 3 h, 6 h, 9 h, 18 h, 24 h, 36 h, 48 h, 3rd, 4th, 5th, 7th, 15th, 30th days after MI. All patients underwent coronary arteriography with ventriculography for estimation of left ventricular ejection fraction (LVEF) and extent of coronary artery diseases, and echocardiographic study for measuring end-diastolic diameter (EDD). Ten patients with an LVEF < 45%, an EDD > 47.5 mm, and heart failure symptoms were included in group A and compared against 12 patients with an LVEF > 45% an EDD < 47.5 mm in group B. Mean plasma concentrations of MMP-1 were higher by 21% in group A (1.3 +/- 0.2 ng/mL) compared to group B (1 +/- 0.1 ng/mL) over the total study period. TIMP-1 plasma concentrations showed very little difference between the 2 groups, (704 +/- 213 ng/mL versus 691 +/- 165 ng/mL, (6%)). Finally, plasma concentrations of MMP-1/TIMP-1 complex were lower by -36% in group A with a mean value of 2.7 +/- 0.6 ng/mL versus 3.7 +/- 0.5 ng/mL in group B. Mean values for the differences were significant at time points 0, 6, 18, 24 and 48 hours for MMP-1 (p < 0.036), and on 48 h and the 4th day for MMP-1/TIMP-1 complex (p < 0.031). Moreover, a good correlation was found between plasma concentrations of creatine kinase (CK) and MMP-1 at 18 h (r = 0.422, p = 0.041) and on the 4th day (r = 0.67, p = 0.046), and TIMP-1 on the 4th day (r = 0.67, p = 0.047). Additionally, mean values for LVEF were 35.8 +/- 8.8% in group A versus 51.2 +/- 1.8% (p = 0.00014) in group B. Also, the EDD in-group A was 52.1 +/- 6.9 mm versus 42.9 +/- 3.2 mm in group B (p = 0.00013). In acute MI patients, increased MMP-1, with no change in TIMP-1, is associated with left ventricular dysfunction and dilatation, suggesting that increased collagenolytic activity contributes to loss of LV function.
Asunto(s)
Metaloproteinasas de la Matriz/sangre , Infarto del Miocardio/enzimología , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/fisiopatología , Función Ventricular IzquierdaRESUMEN
Essential hypertension is often accompanied by abnormalities of the coagulation/fibrinolytic system predisposing to a procoagulant state. The aim of the present study was to examine the comparative efficacy of the angiotensin II type 1 receptor antagonists eprosartan and losartan on plasma levels of hemostatic/fibrinolytic and endothelial function markers in a cohort of previously untreated hypertensive patients. A total of 86 patients whose hypertension was controlled by monotherapy with eprosartan 600 mg (45 patients) or losartan 100 mg (41 patients) were studied. The plasma levels of plasminogen activator inhibitor-1 (PAI-1) antigen, tissue plasminogen activator inhibitor (tPA) antigen, thrombomodulin (TM), tissue factor pathway inhibitor (TFPI) antigen, and fibrinogen were determined before and after 6 months of therapy. Age, sex distribution, body mass index, lipid profile, systolic and diastolic blood pressure levels, and baseline values of the measured markers were similar in both groups. After 6 months of therapy, systolic blood pressure was significantly lower in patients treated with eprosartan, while no differences were observed with respect to diastolic blood pressure. Treatment with both drugs was associated with a significant decrease in PAI-1 antigen, TM, fibrinogen plasma levels and an increase in tPA antigen. The favorable modification of all the above parameters was significantly greater in the eprosartan than in the losartan group, while TFPI plasma levels were decreased to a similar extent with both drugs. In conclusion, the results of our study indicate that 6-month monotherapy with a new angiotensin II type 1 receptor blocker, eprosartan, is associated with a more favorable modification of hemostatic/fibrinolytic status than with losartan.
Asunto(s)
Acrilatos/uso terapéutico , Fibrinólisis/efectos de los fármacos , Hemostasis/efectos de los fármacos , Hipertensión/tratamiento farmacológico , Imidazoles/uso terapéutico , Losartán/uso terapéutico , Tiofenos/uso terapéutico , Acrilatos/farmacología , Anciano , Bloqueadores del Receptor Tipo 1 de Angiotensina II , Esquema de Medicación , Femenino , Fibrinógeno/química , Fibrinógeno/efectos de los fármacos , Fibrinólisis/fisiología , Estudios de Seguimiento , Hemostasis/fisiología , Humanos , Hipertensión/fisiopatología , Imidazoles/farmacología , Lipoproteínas/sangre , Losartán/farmacología , Masculino , Persona de Mediana Edad , Inhibidor 1 de Activador Plasminogénico/sangre , Receptor de Angiotensina Tipo 1/uso terapéutico , Tiofenos/farmacología , Trombomodulina/sangre , Trombomodulina/efectos de los fármacos , Factores de Tiempo , Activador de Tejido Plasminógeno/antagonistas & inhibidores , Activador de Tejido Plasminógeno/sangre , Activador de Tejido Plasminógeno/efectos de los fármacosRESUMEN
Matrix metalloproteinases and their tissue inhibitors are key enzymes degrading myocardial collagen in acute myocardial infarction (AMI). The aim of the present study was to determine whether angiotensin-converting enzyme inhibitors (ACEI) influence collagenase-1 (MMP-1) and their tissue inhibitor (TIMP-1) activity in AMI patients. Plasma levels of MMP-1, TIMP-1 and MMP-1/TIMP-1 complex were measured in 24 patients (aged 58.4 +/- 13.9 years) with AMI. Thirteen patients received perindopril 4 mg/day (group A) and 11 did not (group B). Plasma samples collected on admission and at 0, 3, 6, 9, 12, 18, 24, 36 and 48 hours and on days 3, 4, 5, 7, 15 and 30 thereafter were analyzed by relevant ELISA kits. Ejection fraction (EF) was assessed by ventriculography and end-diastolic diameter (EDD) echo-study on days 6 and 30. Values of collagenolytic enzymes of group A compared with those in group B were on average lower by 34%, 18.3% and 40%, respectively. The difference in values between groups at 0 h, 3 h and 9 h was significant (p < 0.048). ANOVA repeated measurement analysis showed significance within subjects for MMP-1 alone (p < 0.043) and for MMP-1 and ACEI (p < 0.046), while for TIMP-1 and MMP-1/TIMP-1 complex significance was only p < 0.0009. Regarding EDD changes, patients in group A showed minimal or no changes (51.23 +/- 1.8 mm to 51.6 +/- 2.13 mm), their EF was 38.8% and infarct size was medium to large. In contrast, group B showed a trend to increase EDD (41 +/- 0.78 mm to 42.33 +/- 0.59 mm), their EF was 50.5% and infarct size was small to medium. In conclusion, early initiation of ACEI treatment reduces collagenolytic activity. This effect may be considered an alternative mechanism for beneficial effects on postinfarction remodeling.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Metaloproteinasa 1 de la Matriz/sangre , Infarto del Miocardio/tratamiento farmacológico , Inhibidores de Proteasas/sangre , Inhibidor Tisular de Metaloproteinasa-1/sangre , Adulto , Anciano , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/sangre , Infarto del Miocardio/patologíaRESUMEN
AIM: Since conventional risk factors predict less than one half of future cardiovascular events, other factors that contribute to atherogenesis need to be evaluated. The aim of this study was to investigate whether clotting factors are associated with carotid artery disease. Furthermore, we tried to determine whether clotting factors could be used to predict the risk of cerebrovascular events in patients with internal carotid artery stenosis. METHODS: Twenty-six patients with high-grade (>70%) internal carotid artery stenosis and 43 age-matched controls were evaluated for atherogenic risk factors and hemostatic function. Laboratory tests included plasma assays of fibrinogen, tissue plasminogen activator (TPA), D-dimer, plasminogen activator inhibitor 1 (PAI-1), plasminogen and factor VII:c. Nineteen (72%) patients had history of stroke or transient ischemic attack, while the remaining 7 (28%) were asymptomatic. Statistical analysis was performed using multiple linear regression analysis. RESULTS: Carotid artery stenosis was associated with high levels of TPA (p<0.001), D-dimer (p=0.019) and PAI-1 (p<0.001). No statistically significant correlation was found between the presence of carotid artery disease and the levels of fibrinogen (p=0.28), plasminogen (p=0.96) or factor VII:c (p=0.19). As regards the clinical manifestations, none of the studied clotting factors was correlated with the history of cerebrovascular events in the patients with carotid stenosis. CONCLUSION: The results of this study show that the hemostatic system may play a role in the development of carotid artery atherosclerotic disease, while it does not seem to affect the development of symptoms in patients with carotid stenosis.
Asunto(s)
Enfermedades de las Arterias Carótidas/sangre , Enfermedades de las Arterias Carótidas/fisiopatología , Hemostasis , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis de RegresiónRESUMEN
The catalytic schemes of a variety of haem enzymes, including the P450 mono-oxygenases, consist of a number of common reactive haem-oxygen adducts. The characterization of these intermediates by optical and EPR spectroscopies has reinforced the similarity of these intermediate states in a number of haem enzyme systems. Furthermore, the reactivity of these states in P450 and horseradish peroxidase, in which multiple potent oxidants are formed, provides a paradigm for many other haem enzymes.
Asunto(s)
Hemo/metabolismo , Oxígeno/metabolismo , Catálisis , Cinética , Mutagénesis Sitio-Dirigida , Proteínas Recombinantes/metabolismo , Esteroide 21-Hidroxilasa/metabolismoRESUMEN
We have employed gamma-irradiation at cryogenic temperatures (77 K and also approximately 6 K) of the ternary complexes of camphor, dioxygen, and ferro-cytochrome P450cam to inject the "second" electron of the catalytic process. We have used EPR and ENDOR spectroscopies to characterize the primary product of reduction as well as subsequent states created by annealing reduced oxyP450, both the WT enzyme and the D251N and T252A mutants, at progressively higher temperatures. (i) The primary product upon reduction of oxyP450 4 is the end-on, "H-bonded peroxo" intermediate 5A. (ii) This converts even at cryogenic temperatures to the hydroperoxo-ferriheme species, 5B, in a step that is sensitive to these mutations. Yields of 5B are as high as 40%. (iii) In WT and D251N P450s, brief annealing in a narrow temperature range around 200 K causes 5B to convert to a product state, 7A, in which the product 5-exo-hydroxycamphor is coordinated to the ferriheme in a nonequilibrium configuration. Chemical and EPR quantitations indicate the reaction pathway involving 5B yields 5-exo-hydroxycamphor quantitatively. Analogous (but less extensive) results are seen for the alternate substrate, adamantane. (iv) Although the T252A mutation does not interfere with the formation of 5B, the cryoreduced oxyT252A does not yield product, which suggests that 5B is a key intermediate at or near the branch-point that leads either to product formation or to nonproductive "uncoupling" and H(2)O(2) production. The D251N mutation appears to perturb multiple stages in the catalytic cycle. (v) There is no spectroscopic evidence for the buildup of a high-valence oxyferryl/porphyrin pi-cation radical intermediate, 6. However, ENDOR spectroscopy of 7A in H(2)O and D(2)O buffers shows that 7A contains hydroxycamphor, rather than water, bound to Fe(3+), and that the proton removed from the C(5) carbon of substrate during hydroxylation is trapped as the hydroxyl proton. This demonstrates that hydroxylation of substrates by P450cam in fact occurs by the formation and reaction of 6. (vi) Annealing at > or = 220 K converts the initial product state 7A to the equilibrium product state 7, with the transition occurring via a second nonequilibrium product state, 7B, in the D251N mutant; in states 7B and 7 the hydroxycamphor hydroxyl proton no longer is trapped. (vii) The present results are discussed in the context of other efforts to detect intermediates in the P450 catalytic cycle.
Asunto(s)
Alcanfor 5-Monooxigenasa/metabolismo , Alcanfor/metabolismo , Catálisis , Espectroscopía de Resonancia por Spin del Electrón , Congelación , HidroxilaciónRESUMEN
OBJECTIVE: The aim of this study was to evaluate the significance of the development of a restrictive response to an acute saline load, defined as an increase in the ratio of peak early to peak late diastolic transmitral flow velocity (E/A ratio) associated with a decrease in the deceleration time, in patients with mild to moderate untreated hypertension. BACKGROUND: Recognised abnormal patterns of transmitral diastolic flow include, from 'best' to 'worst': prolonged relaxation, pseudonormalisation, and restrictive physiology. The common denominator of these transitions is the constellation of an increase in the E/A ratio associated with a decrease in deceleration time. PATIENTS AND METHODS: Sixteen normal control subjects (6 males, 10 females, age 51.6 +/- 6.9 years) and 24 patients with mild to moderate untreated hypertension (12 males, 12 females, age 46.8 +/- 7.5 years) underwent supine blood pressure measurement with sphygmomanometry, biochemical studies, and transthoracic M-mode, 2D, and Doppler echocardiography before and after an acute saline load (7 mL kg(-1), maximum 500 mL, NaCl 0.9% within 15 min IV). RESULTS: The baseline E/A ratio was lower (0.90 +/- 0.14 vs. 1.04 +/- 0.18; P < 0.01) and the deceleration time was longer (158.8 +/- 19.4 vs. 135 +/- 8.9 ms; P < 0.01) in patients with hypertension compared with normotensive controls. However, no patient with hypertension exhibited a transmitral flow velocity pattern compatible with typical prolonged relaxation. A restrictive response to the acute saline load was observed in 12 (50%) of the hypertensive and none of the control subjects. Hypertensive patients with a restrictive response to the acute saline load had a lower baseline E velocity (54.8 +/- 8.7 cm s(-1) vs. 66 +/- 6.4 cm s(-1); P = 0.003), a lower baseline E/A ratio (0.83 +/- 0.13 vs. 0.97 +/- 0.12; P = 0.015), and a longer deceleration time (167.5 +/- 15.4 ms vs. 150 +/- 19.5; P = 0.03) than hypertensive patients without such a response. CONCLUSION: A restrictive response to an acute saline load is indicative of a limited diastolic reserve in patients with mild to moderate untreated hypertension. Further studies are required in order to evaluate the significance of such a response with regards to risk stratification and efficacy of medical treatment in this patient population.
Asunto(s)
Hipertensión/fisiopatología , Cloruro de Sodio , Función Ventricular Izquierda/fisiología , Adulto , Velocidad del Flujo Sanguíneo , Presión Sanguínea , Diástole/fisiología , Femenino , Pruebas de Función Cardíaca , Humanos , Masculino , Persona de Mediana Edad , Válvula Mitral/fisiopatología , Cloruro de Sodio/administración & dosificaciónRESUMEN
Unstable reaction intermediates of the cytochrome P450 catalytic cycle have been prepared at cryogenic temperatures using radiolytic one-electron reduction of the oxy-P450 CYP101 complex. Since a rate-limiting step in the catalytic cycle of the enzyme is the reduction of the ferrous oxygenated heme protein, subsequent reaction intermediates do not normally accumulate. Using (60)Co gamma-irradiation, the primary reduced oxy-P450 species at 77 K has been identified as a superoxo- or hydroperoxo-Fe(3+)-heme complex (Davydov, R., Macdonald, I. D. G., Makris, T. M., Sligar, S. G., and Hoffman, B. M. (1999) J. Am. Chem. Soc. 121, 10654-10655). The electronic absorption spectroscopy is an essential tool to characterize cytochrome P450 intermediates and complements paramagnetic methods, which are blind to important diamagnetic or antiferromagnetically coupled states. We report a method of trapping unstable states of redox enzymes using phosphorus-32 as an internal source of electrons. We determine the UV-visible optical spectra of the reduced oxygenated state of CYP101 and show that the primary intermediate, a hydroperoxo-P450, is stable below 180 K and converts smoothly to the product complex at approximately 195 K. In the course of the thermal annealing, no spectral changes indicating the presence of oxoferryl species (the so-called compound I type spectrum) was observed.
Asunto(s)
Sistema Enzimático del Citocromo P-450/química , Espectroscopía de Resonancia por Spin del Electrón , Oxidación-Reducción , Radioisótopos de Fósforo , RadioquímicaRESUMEN
BACKGROUND: Angiotensin-converting enzyme (ACE) gene polymorphism has been associated with an increased incidence of myocardial infarction. Recent studies have investigated a potential influence of ACE gene polymorphism on fibrinolysis or endothelial function. It has been previously established that essential hypertension is accompanied by endothelial dysfunction and fibrinolytic balance disorders. The aim of our study was to study the relation between ACE gene polymorphism and fibrinolytic/hemostatic factors as well as endothelial cell damage markers in patients with hypertension. METHODS: The following parameters were evaluated in 104 patients with previously untreated hypertension: plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) antigen, fibrinogen, D-dimer, and von Willebrand factor (vWF). The genotype of the ACE gene was also determined (by the polymerase chain reaction method), and patients were characterized according to the observed alleles as deletion/deletion (DD), insertion/insertion (II), or insertion/deletion (ID). RESULTS: Those with DD genotype (n = 42) had significantly higher plasma levels of PAI-1 antigen (P =. 012), tPA antigen (P =.0001), fibrinogen (P =.0002), D-dimer (P =. 0001) and vWF (P =.0004) compared with ID (n = 30) or II (n = 32) genotypes. The ACE gene genotypes appeared to be significant predictors for plasma PAI-1 antigen, tPA antigen, fibrinogen, D -dimer, and vWF even after adjustment for age, sex, body mass index, triglyceride and cholesterol levels, and blood pressure. CONCLUSIONS: Our findings suggest that the ACE/DD genotype is associated with hemostasis balance disturbances reflecting hypercoagulability and endothelial damage in patients with untreated hypertension.