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1.
Lancet ; 385(9984): 2264-2271, 2015 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-25748612

RESUMO

BACKGROUND: Genetic variants have been associated with the risk of coronary heart disease. In this study, we tested whether or not a composite of these variants could ascertain the risk of both incident and recurrent coronary heart disease events and identify those individuals who derive greater clinical benefit from statin therapy. METHODS: A community-based cohort study (the Malmo Diet and Cancer Study) and four randomised controlled trials of both primary prevention (JUPITER and ASCOT) and secondary prevention (CARE and PROVE IT-TIMI 22) with statin therapy, comprising a total of 48,421 individuals and 3477 events, were included in these analyses. We studied the association of a genetic risk score based on 27 genetic variants with incident or recurrent coronary heart disease, adjusting for traditional clinical risk factors. We then investigated the relative and absolute risk reductions in coronary heart disease events with statin therapy stratified by genetic risk. We combined data from the different studies using a meta-analysis. FINDINGS: When individuals were divided into low (quintile 1), intermediate (quintiles 2-4), and high (quintile 5) genetic risk categories, a significant gradient in risk for incident or recurrent coronary heart disease was shown. Compared with the low genetic risk category, the multivariable-adjusted hazard ratio for coronary heart disease for the intermediate genetic risk category was 1·34 (95% CI 1·22-1·47, p<0·0001) and that for the high genetic risk category was 1·72 (1·55-1·92, p<0·0001). In terms of the benefit of statin therapy in the four randomised trials, we noted a significant gradient (p=0·0277) of increasing relative risk reductions across the low (13%), intermediate (29%), and high (48%) genetic risk categories. Similarly, we noted greater absolute risk reductions in those individuals in higher genetic risk categories (p=0·0101), resulting in a roughly threefold decrease in the number needed to treat to prevent one coronary heart disease event in the primary prevention trials. Specifically, in the primary prevention trials, the number needed to treat to prevent one such event in 10 years was 66 in people at low genetic risk, 42 in those at intermediate genetic risk, and 25 in those at high genetic risk in JUPITER, and 57, 47, and 20, respectively, in ASCOT. INTERPRETATION: A genetic risk score identified individuals at increased risk for both incident and recurrent coronary heart disease events. People with the highest burden of genetic risk derived the largest relative and absolute clinical benefit from statin therapy. FUNDING: National Institutes of Health.


Assuntos
Doença das Coronárias/tratamento farmacológico , Doença das Coronárias/genética , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Humanos , Números Necessários para Tratar , Prevenção Primária , Recidiva , Medição de Risco , Prevenção Secundária , Resultado do Tratamento
2.
Diabet Med ; 28(8): 941-7, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21749444

RESUMO

AIMS: To evaluate, in hypertensive patients, whether the metabolic syndrome is a better predictor of new-onset diabetes compared with impaired fasting glucose, obesity or its other individual components alone, or collectively. METHODS: Cox models were developed to assess the risk of new-onset diabetes associated with the metabolic syndrome after adjusting for a priori confounders (age, sex, ethnicity and concomitant use of non-cardiovascular medications), its individual components and other determinants of new-onset diabetes. Area under receiver operator curves using the metabolic syndrome or models of impaired fasting glucose were compared, and the ability of these models to correctly identify those who (after 5-years of follow-up) would or would not develop diabetes was assessed. RESULTS: The metabolic syndrome adjusted for a priori confounders and its individual components, and further adjusted for other determinants, was associated with significantly increased risk of new-onset diabetes [1.19 (1.00-1.40), P = 0.05 and 1.22 (1.03-1.44), P = 0.02, respectively]. The discriminative ability of the metabolic syndrome model [area under receiver operating curve: 0.764 (0.750-0.778)] was significantly better than the model of impaired fasting glucose [0.742 (0.727-0.757)] (P < 0.001). The metabolic syndrome correctly allocates the risk of new-onset diabetes in a significantly higher proportion of patients (62.3%) than impaired fasting glucose status (37.7%) (P < 0.001). The presence of both the metabolic syndrome and impaired fasting glucose were associated with an approximately 9-fold (7.47-10.45) increased risk of new-onset diabetes. Among normoglycaemic patients, the metabolic syndrome was also associated with significantly increased risk of new-onset diabetes, after adjusting for BMI and a priori confounders [1.66 (1.29-2.13)]. CONCLUSIONS: Both impaired fasting glucose and the metabolic syndrome predict the risk of new-onset diabetes; however, the metabolic syndrome is a better predictor than impaired fasting glucose in assigning the risk of new-onset diabetes in hypertensive patients, and among those with normoglycaemia.


Assuntos
Glicemia , Diabetes Mellitus Tipo 2/metabolismo , Jejum , Hipertensão/metabolismo , Síndrome Metabólica/metabolismo , Obesidade/metabolismo , Diabetes Mellitus Tipo 2/etiologia , Jejum/fisiologia , Feminino , Humanos , Hipertensão/complicações , Masculino , Síndrome Metabólica/complicações , Pessoa de Meia-Idade , Obesidade/complicações , Valor Preditivo dos Testes , Modelos de Riscos Proporcionais , Fatores de Risco
3.
Int J Clin Pract ; 64(9): 1228-34, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20500533

RESUMO

BACKGROUND: Adherence to lipid-lowering therapy in clinical practice is less than ideal. Analysis of registry data has indicated that this is associated with poor outcomes. The objective of the present analysis was to assess the impact of high adherence to drug (defined as > 80% of days covered), compared with low adherence to drug (< 50% of days covered) in terms of risk of events and long-term economic consequences. DESIGN: Open-label follow up of a randomised placebo-controlled trial in hypertensive patients. METHODS: Cox proportional hazards and Poisson regression models were used to assess the hazard ratio of patients with high adherence compared with low adherence while controlling for cardiovascular risk. A Markov model was used to predict the long-term costs and health outcomes associated with poor adherence during the follow-up period. RESULTS: Both statistical models indicated that high adherence is associated with improved prognosis [Cox model: 0.75; 95% confidence interval (CI): 0.56-0.98, Poisson model hazard ratio: 0.73; 95% CI: 0.58-0.98]. Discounted at 3.5% per year, the Markov model predicts that as a consequence of higher adherence during the follow-up period, costs would be higher (1689 pounds per patient compared with 1323 pounds per patient) because of higher drug costs, but the projected survival and quality-adjusted survival (QALY) would also be longer (10.83 compared with 10.81 life years and 8.13 compared with 8.11 QALYs). CONCLUSION: Given the higher risk of cardiovascular events associated with low adherence shown here, measures to improve adherence are an important part of the prevention of cardiovascular disease.


Assuntos
Anticolesterolemiantes/uso terapêutico , Anti-Hipertensivos/uso terapêutico , Ácidos Heptanoicos/uso terapêutico , Hipertensão/tratamento farmacológico , Pirróis/uso terapêutico , Adulto , Idoso , Anticolesterolemiantes/economia , Anti-Hipertensivos/economia , Atorvastatina , Doenças Cardiovasculares/etiologia , Doença das Coronárias/prevenção & controle , Análise Custo-Benefício , Feminino , Seguimentos , Ácidos Heptanoicos/economia , Humanos , Hiperlipidemias/tratamento farmacológico , Hiperlipidemias/economia , Hipertensão/economia , Masculino , Cadeias de Markov , Adesão à Medicação , Pessoa de Meia-Idade , Pirróis/economia , Anos de Vida Ajustados por Qualidade de Vida , Fatores de Risco
4.
J Clin Invest ; 69(4): 779-84, 1982 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-6281311

RESUMO

Cardiovascular responses to intravenous administration of norepinephrine and the properties of alpha receptors on platelets were compared in normal human subjects and subjects with multiple system atrophy (MSA) and sympathetic degeneration. All the subjects with MSA had low plasma norepinephrine concentrations (in the supine position) (0.42 +/- 0.09 nM, normal 3.47 +/- 0.58 nM), which did not increase on tilt. The pressor sensitivity of subjects with MSA to norepinephrine infusion was increased 10- to 20-fold, demonstrating denervation supersensitivity to adrenergic agonists. Analysis of alpha receptors was by binding of [3H]dihydroergocryptine to platelets. Results are shown as mean +/- standard error of the mean. In the MSA subjects, the number of alpha receptors (1,712 +/- 699 fmol/10(8) platelets) was about sevenfold greater than in normal subjects (224 +/- 21 fmol/10(8) platelets), and the affinity, as measured by the equilibrium dissociation constant (Kd), was similar in both groups (MSA subjects, 9.6 +/- 4.3 nM; normal subjects, 4 +/- 0.5 nM). These observations suggest that an increase in alphaadrenergic receptor numbers may account for the denervation supersensitivity to infused norepinephrine in patients with sympathetic degeneration. All the subjects with MSA had low levels of the endogenous adrenergic transmitter norepinephrine: the simultaneous increase in alpha adrenergic receptors supports the theory of agonist regulation of receptor numbers.


Assuntos
Doenças do Sistema Nervoso Autônomo/fisiopatologia , Plaquetas/fisiologia , Receptores Adrenérgicos alfa/fisiologia , Receptores Adrenérgicos/fisiologia , Síndrome de Shy-Drager/fisiopatologia , Adulto , Idoso , Pressão Sanguínea , Feminino , Humanos , Infusões Parenterais , Masculino , Pessoa de Meia-Idade , Norepinefrina/sangue , Norepinefrina/metabolismo , Norepinefrina/farmacologia , Postura , Receptores Adrenérgicos alfa/metabolismo , Síndrome de Shy-Drager/sangue
5.
Biochim Biophys Acta ; 1035(3): 378-80, 1990 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-2207132

RESUMO

Until recently, direct measurement of intracellular free magnesium has been complex and difficult. However, fluorescent probes are now available, based on the same principle as well-established probes for free calcium. Using one such probe, mag-fura-2, we have estimated basal intracellular magnesium concentrations in the A7r5 rat vascular smooth muscle cell line. This level was unaffected by numerous pharmacological manipulations, including agonist stimulation and depolarisation. The possible implications of these findings are discussed.


Assuntos
Músculo Liso Vascular/metabolismo , Animais , Cálcio/metabolismo , Cálcio/farmacologia , Linhagem Celular , Fura-2 , Cinética , Magnésio/farmacologia , Músculo Liso Vascular/efeitos dos fármacos , Ratos
6.
Cardiovasc Res ; 29(1): 50-6, 1995 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7895239

RESUMO

OBJECTIVE: The aim was to investigate the involvement of polyamines in the development of cardiovascular hypertrophy in a rat angiotensin II infusion model of hypertension. METHODS: Rats were chronically infused with a low dose of angiotensin II (83 ng.min-1.rat-1) or vehicle by osmotic minipumps. The polyamine content of the cardiovascular organs and liver was measured by HPLC, and the blood pressure of conscious rats was determined by a tail cuff method. The mesenteric arterial beds were perfusion fixed in situ and medial and luminal cross sectional areas were determined by computer assisted planimetry. Cardiac hypertrophy was assessed by determination of ventricular:body weight ratios. RESULTS: Angiotensin II infusion caused an increased concentration of polyamines in the ventricles and aorta within hours of beginning the infusion, and within days in the mesenteric arteries. Polyamine content of the liver was unaffected. Hypertrophy of the myocardium and mesenteric arteries in association with the increased blood pressure was evident. CONCLUSIONS: A low dose of angiotensin II stimulates an early biochemical marker of growth, the polyamines, in cardiovascular tissues but not in the liver. The increase in tissue polyamines is associated with cardiovascular hypertrophy and the development of hypertension.


Assuntos
Angiotensina II/farmacologia , Cardiomegalia/metabolismo , Hipertensão/metabolismo , Poliaminas/metabolismo , Animais , Aorta/química , Modelos Animais de Doenças , Ventrículos do Coração/química , Fígado/química , Masculino , Artérias Mesentéricas/metabolismo , Miocárdio/química , Miocárdio/metabolismo , Putrescina/análise , Ratos , Ratos Endogâmicos WKY , Espermidina/análise , Espermina/análise
7.
Cardiovasc Res ; 12(3): 144-7, 1978 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-647718

RESUMO

Plasma noradrenaline concentration was determined by a radioenzymatic method in 10 normal individuals who were subjected to a stepwise tilt through 45 degrees. A gradual increase in noradrenaline was observed with maximal values occurring in most subjects following the full 45 degrees of tilt. Maximal levels were sustained for up to 30 min. In two subjects who fainted, the syncopal episode followed an initial sympathetic postural response as shown by a rise in plasma noradrenaline. For the remaining subjects a significant correlation was found between changes in plasma noradrenaline and mean arterial pressure.


Assuntos
Norepinefrina/sangue , Postura , Adulto , Pressão Sanguínea , Feminino , Humanos , Masculino , Pulso Arterial , Sistema Nervoso Simpático/fisiologia
8.
Cardiovasc Res ; 28(5): 615-20, 1994 May.
Artigo em Inglês | MEDLINE | ID: mdl-8025905

RESUMO

OBJECTIVE: The aim was to assess the growth inhibitory effect of fibrates on human vascular smooth muscle cells. Restenosis is the most important factor limiting the long term success of invasive vascular interventions and there is as yet no effective preventive treatment. Platelet derived growth factor (PDGF) is considered to be an important growth promoting agent for vascular smooth muscle cells (VSMC) and fenofibric acid (a hypolipidaemic drug) has been reported to be a PDGF antagonist. METHODS: The effect of the fibrate drugs fenofibrate, clofibrate, bezafibrate, and gemfibrozil were examined on the proliferation of cultured human vascular smooth muscle cells derived from saphenous vein (n = 20) and graft stenoses (n = 7). RESULTS: Fenofibrate (100 microM) produced potent inhibition (48%) of VSMC proliferation at a concentration equivalent to that of its circulating metabolite fenofibric acid, but none of the other drugs produced any significant effect on growth. VSMC derived from graft stenoses were equally sensitive to inhibition as saphenous vein derived controls, in contrast to our previous work which reported that graft stenosis derived VSMC were resistant to growth inhibition by the physiological inhibitor heparin. The antiproliferative effect of fenofibrate was independent of inhibition of cellular cholesterol synthesis or toxicity. Fenofibrate inhibited VSMC growth induced by 15% fetal calf serum, PDGF, and basic fibroblast growth factor to a similar degree, indicating that it is not a specific PDGF antagonist. CONCLUSIONS: Fenofibrate is not a specific PDGF antagonist. Fenofibric acid, one of the principal metabolites of fenofibrate, did not produce any inhibition of growth, suggesting that oral administration of fenofibrate would not be efficacious. Fenofibrate is the first potent inhibitor to be described for VSMC derived from human myo-intimal hyperplastic lesions.


Assuntos
Fenofibrato/farmacologia , Músculo Liso/efeitos dos fármacos , Bezafibrato/farmacologia , Divisão Celular/efeitos dos fármacos , Células Cultivadas , Clofibrato/farmacologia , Fenofibrato/análogos & derivados , Genfibrozila/farmacologia , Oclusão de Enxerto Vascular/patologia , Humanos , Músculo Liso/citologia , Fator de Crescimento Derivado de Plaquetas/antagonistas & inibidores , Veia Safena/citologia
9.
Cardiovasc Res ; 22(3): 159-62, 1988 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2901912

RESUMO

Bromoacetylalprenololmenthane (BAAM), an alkylating irreversible beta adrenoceptor antagonist, was used to study in vivo beta adrenoceptor synthesis in adult rat left ventricle under normoxic and hypoxic conditions. In normoxic conditions cardiac beta adrenoceptor density decreased by 50% 15 h after treatment and recovered to control values after about 250 h. A similar decrease in receptor density and pattern of recovery was found in environmental hypoxia. Neither hypoxia nor treatment with BAAM had a significant effect on the dissociation constant of the radioligand. These results show that cardiac beta adrenoceptor synthesis occurs rather slowly and suggest that alteration of the rate of receptor synthesis in hypoxic states is not a major determinant of reported changes in density.


Assuntos
Hipóxia/metabolismo , Miocárdio/metabolismo , Receptores Adrenérgicos beta/biossíntese , Antagonistas Adrenérgicos beta/farmacologia , Alprenolol/análogos & derivados , Alprenolol/farmacologia , Animais , Masculino , Ratos , Ratos Endogâmicos , Receptores Adrenérgicos beta/efeitos dos fármacos
10.
Cardiovasc Res ; 30(1): 147-52, 1995 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7553717

RESUMO

OBJECTIVE: An increased carotid intima-media thickness (IMT) has been found to be associated with a number of cardiovascular risk factors such as age, hypertension, cigarette smoking, hypercholesterolaemia and left ventricular hypertrophy. Our objective was to assess whether carotid intima-media thickness in hypertensive patients could be reduced by antihypertensive therapy. METHODS: 13 hypertensive patients, 10 previously untreated, were examined using carotid ultrasonography and echocardiography at baseline and then at 8 weeks and 39 weeks after commencement of antihypertensive therapy with ramipril and the second-line addition of felodipine. RESULTS: By the end of the study significant regression of IMT (0.1(0.05-0.16) mm, F-value 10.2, P < 0.01) and left ventricular mass index had occurred (25(10.7-39.3) g/m2, F-value 9.7, P < 0.01). The reduction in IMT was significantly related to the reduction in mean arterial pressure, r = 0.55, P = 0.05). CONCLUSION: Antihypertensive therapy with ramipril and felodipine causes regression of IMT in hypertensive patients, probably chiefly through blood pressure reduction. Large prospective studies are required to assess whether a reduction in IMT results in a reduction in morbidity and mortality.


Assuntos
Artérias Carótidas , Hipertensão/patologia , Ramipril/uso terapêutico , Túnica Íntima/patologia , Adulto , Idoso , Artérias Carótidas/diagnóstico por imagem , Quimioterapia Combinada , Felodipino/uso terapêutico , Feminino , Humanos , Hipertensão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Túnica Íntima/efeitos dos fármacos , Ultrassonografia
11.
Hypertension ; 8(8): 641-9, 1986 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-3733213

RESUMO

To determine whether venous plasma norepinephrine concentrations consistently reflect changes in sympathetic nervous activity, the influence of mental arithmetic, static handgrip, and submaximal bicycle exercise on intra-arterial blood pressure, heart rate, and plasma norepinephrine was studied in 51 subjects with untreated essential hypertension (mean age, 46 years; range, 16-69 years). At rest, plasma norepinephrine was unrelated to age or blood pressure. Mental arithmetic increased mean arterial pressure from 108 +/- 18 to 127 +/- 18 mm Hg (mean +/- S.D.; p less than 0.001) and heart rate from 69 +/- 7 to 93 +/- 13 beats/min (p less than 0.001) but not plasma norepinephrine (547 +/- 297 to 518 +/- 250 pg/ml). Isometric exercise raised mean arterial pressure from 115 +/- 18 to 148 +/- 21 mm Hg (p less than 0.001) and heart rate from 76 +/- 9 to 95 +/- 13 beats/min (p less than 0.001) but not plasma norepinephrine (683 +/- 253 to 741 +/- 253 pg/ml). Bicycle exercise increased mean arterial pressure from 114 +/- 20 to 146 +/- 26 mm Hg (p less than 0.001), heart rate from 77 +/- 9 to 128 +/- 19 beats/min (p less than 0.001), and plasma norepinephrine from 645 +/- 228 to 1151 +/- 462 pg/ml (p less than 0.001). Both the maximum mean arterial pressure and the peak heart rate attained during bicycle exercise were related to the exercise plasma norepinephrine level (r = 0.33, p less than 0.02 and r = 0.28, p less than 0.03, respectively). Increases in plasma norepinephrine with exercise were not greater in older or more hypertensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Hipertensão/sangue , Norepinefrina/sangue , Sistema Nervoso Simpático/fisiopatologia , Adulto , Idoso , Feminino , Frequência Cardíaca , Humanos , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Esforço Físico
12.
Hypertension ; 6(6 Pt 1): 810-3, 1984.
Artigo em Inglês | MEDLINE | ID: mdl-6335133

RESUMO

Blood pressure (BP) and associated factors were determined in 1737 men in a remote Kenyan agricultural community. Systolic BP showed no significant rise with age until after 54 years; diastolic BP showed a small rise with age. Both systolic and diastolic BP correlated with weight independent of age. Systolic and diastolic BP correlated positively with casual urinary sodium/potassium and negatively with potassium/creatinine ratios. Both systolic and diastolic BP correlated significantly with the number of years of education, as did urinary sodium/potassium and sodium/creatinine ratios. Potassium/creatinine ratios were negatively correlated with the number of years of education. Blood pressure and urinary sodium/creatinine ratios were significantly lower in subsistence farmers compared with those in other occupations, and potassium/creatinine ratios were significantly higher. Two pilot studies of Luo tribesmen showed a strong correlation between casual urinary electrolyte ratios and those derived from 24-hour urine samples and a greater variance of sodium excretion between these people than that found within individuals. These results suggest that a relationship between BP and casual urine electrolyte estimations may be identifiable in communities where there is less day-to-day dietary variation. They also suggest that some of the changes in BP associated with urbanization could be mediated by changes in dietary electrolytes.


Assuntos
Pressão Sanguínea , População Rural , Adolescente , Adulto , Idoso , Envelhecimento , Agricultura , Peso Corporal , Creatinina/urina , Estudos Transversais , Dieta , Escolaridade , Humanos , Quênia , Masculino , Pessoa de Meia-Idade , Ocupações , Projetos Piloto , Potássio/administração & dosagem , Potássio/urina , Sódio/administração & dosagem , Sódio/urina , Urbanização
13.
Hypertension ; 28(5): 791-6, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8901825

RESUMO

The interlead variation in QT length on a standard electrocardiograph reflects regional repolarization differences in the heart. To investigate the association between this interlead variation (QT dispersion) and left ventricular hypertrophy, we subjected 100 untreated subjects to 12-lead electrocardiography and echocardiography. Additionally, 24 previously untreated subjects underwent a 6-month treatment study with ramipril and felodipine. In the cross-sectional part of the study, QT dispersion corrected for heart rate (QTc dispersion) was significantly correlated with left ventricular mass index (r = .30, P < .01), systolic pressure (r = .30, P < .01), the ratio of peak flow velocity of the early filling wave to peak flow velocity of the atrial wave (E/A ratio) (r = -.22, P = .02), isovolumic relaxation time (r = .31, P < .01), and age (r = .21, P < .04). In the treatment part of the study, lead-adjusted QTc dispersion decreased from 24 to 19 milliseconds after treatment, and after a subsequent 2 weeks of drug washout remained at 19 milliseconds (P < .01). The changes in left ventricular mass index at these stages were 144, 121, and 124 g/m2 (P < .01). Systolic pressure decreased from 175 to 144 mm Hg and increased again to 164 mm Hg after drug washout (P < .01). The E/A ratio (0.97, 1.02, and 1.02; P = 69) and isovolumic relaxation time (111, 112, and 112; P = .97) remained unchanged through the three assessment points. In conclusion, QT dispersion is increased in association with an increased left ventricular mass index in hypertensive individuals. Antihypertensive therapy with ramipril and felodipine reduced both parameters. If an increased QT dispersion is a predictor of sudden death in this group of individuals, then the importance of its reduction is evident.


Assuntos
Anti-Hipertensivos/uso terapêutico , Eletrocardiografia/efeitos dos fármacos , Felodipino/uso terapêutico , Hipertensão/tratamento farmacológico , Hipertrofia Ventricular Esquerda/fisiopatologia , Ramipril/uso terapêutico , Adulto , Ecocardiografia , Feminino , Hemodinâmica , Humanos , Masculino
14.
Hypertension ; 11(3): 273-81, 1988 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2895071

RESUMO

We examined the influence of baroreceptor reflex sensitivity (the increase in pulse interval in response to a phenylephrine-induced increase in blood pressure), age, blood pressure, and beta-adrenergic receptor blockade on the variability of blood pressure and heart rate in essential hypertension. Fifty-six subjects were studied before treatment; intra-arterial blood pressure was recorded outside the hospital for 24 hours. Variability was defined (from all beats occurring while subjects were awake) as the standard deviation about the average waking value for mean arterial pressure (MAP) or pulse interval. The correlation (r) between baroreceptor reflex sensitivity and blood pressure variability was -0.47 (p less than 0.0002). Baroreceptor reflex sensitivity was the only independent determinant of blood pressure variability on multiple regression analysis. Thirty subjects were restudied after 5 months of beta-adrenergic receptor blockade. Ambulatory blood pressure was lower during treatment, whereas pulse interval, its variability, and baroreceptor reflex sensitivity were higher. Blood pressure variability was unchanged. The variability of MAP was inversely correlated with baroreceptor reflex sensitivity before (r = -0.42, p less than 0.02) and during (r = -0.45, p less than 0.02) treatment, but it was unrelated to the average ambulatory MAP or to the variability of pulse interval either before or during beta-blockade. Sixteen subjects whose average waking ambulatory blood pressure was 140/90 mm Hg or less were not treated. This group of borderline hypertensive subjects had less variable MAP than did the remaining 40 subjects (12.4 +/- 2.3 [SD] vs 14.5 +/- 2.5 mm Hg; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Pressão Sanguínea , Frequência Cardíaca , Hipertensão/fisiopatologia , Pressorreceptores/fisiologia , Antagonistas Adrenérgicos beta/uso terapêutico , Fatores Etários , Determinação da Pressão Arterial , Feminino , Humanos , Hipertensão/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Norepinefrina/sangue , Pulso Arterial , Receptores Adrenérgicos beta/efeitos dos fármacos , Reflexo/fisiologia , Fatores de Tempo
15.
Hypertension ; 31(5): 1190-4, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9576134

RESUMO

Black hypertensive persons have been observed to have a greater degree of left ventricular hypertrophy than white hypertensives. However, previous studies have matched groups for blood pressure (BP) measured in the clinic, and it has been demonstrated that black hypertensives have an attenuated nocturnal BP dip. Clinic BPs may thus underestimate mean 24-hour BP in this group. To investigate whether the differences in left ventricular hypertrophy can be accounted for by the greater mean 24-hour BP in black hypertensives, 92 previously untreated hypertensives were studied with 24-hour ambulatory BP monitoring and echocardiography. The 46 black hypertensives (24 men and 22 women) were matched with the 46 white hypertensives for age, gender, and mean 24-hour BP. Despite similar mean 24-hour BPs (blacks, 142/93 mm Hg; whites, 145/92 mm Hg; P=.53/.66), the black group had a smaller mean nocturnal dip than the white group (blacks, 8/8 mm Hg; whites, 16/13 mm Hg; P<.01). In addition, mean left ventricular mass index (LVMI) was greater (blacks, 130 g/m2; whites, 107 g/m2; P<.001). Mean 24-hour systolic BP was significantly related to LVMI in both groups (blacks, r=.45, P<.01; whites, r=.56, P<.01). However, systolic BP dip correlated inversely with LVMI only in the black group (blacks, r=-.30, P<.04; whites, r=.05, P=.76). In a multiple regression model, LVMI was independently related to both mean daytime BP and mean nocturnal BP dip in black subjects but only to mean daytime BP in white subjects. In conclusion, the increased left ventricular hypertrophy observed in black hypertensives compared with white hypertensives is not accounted for by differences in mean 24-hour BP. However, LVMI in black hypertensives appears to be more dependent on nocturnal BP than that in white hypertensives; this, coupled with the attenuated BP dip in black hypertensives, suggests that the BP profile rather than 24-hour BP may be important in determining the differences in left ventricular hypertrophy.


Assuntos
População Negra , Pressão Sanguínea , Hipertensão/etnologia , Hipertensão/fisiopatologia , Hipertrofia Ventricular Esquerda/etnologia , População Branca , Adulto , Monitorização Ambulatorial da Pressão Arterial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
16.
J Clin Endocrinol Metab ; 57(5): 911-4, 1983 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-6311864

RESUMO

Plasma norepinephrine concentrations in a group of malnourished patients with anorexia nervosa were significantly (P less than 0.002) lower than those in an age- and sex-matched group of normal subjects. Platelet total alpha-adrenoceptor densities of these patients significantly (P less than 0.002) exceeded those of the controls. The increased total alpha-adrenoceptor density was due to an increase in the alpha 2-adrenoceptor receptor subtype, which mediates epinephrine-induced platelet aggregation. Accordingly, the aggregation response of the patients' platelets was significantly (P less than 0.002) enhanced after epinephrine challenge. We suggest that the starvation-induced fall in plasma norepinephrine levels is associated with the up-regulation of platelet alpha-adrenoceptors. This, in turn, accounts for exaggerated epinephrine-induced platelet aggregation in anorexic patients.


Assuntos
Anorexia Nervosa/sangue , Agregação Plaquetária , Receptores Adrenérgicos alfa/metabolismo , Adolescente , Adulto , Plaquetas/metabolismo , Di-Hidroergotoxina/metabolismo , Epinefrina/farmacologia , Ácidos Graxos não Esterificados/sangue , Feminino , Humanos , Norepinefrina/sangue , Agregação Plaquetária/efeitos dos fármacos , Ioimbina/metabolismo
17.
FEBS Lett ; 199(1): 125-9, 1986 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-3007215

RESUMO

A method is described for preparing human lung parenchymal membranes essentially free of carbon contamination. Using this technique, a high-affinity 125I-VIP-binding site has been characterised. The receptor density is approx. 200 fmol/mg protein, and the Kd of 125I-VIP by saturation binding is 200 pM. The dissociation kinetics are complex and cannot be described by first-order kinetics. Several VIP-related peptides displace 125I-VIP from this binding site with a rank order of potency: VIP greater than rat GRF greater than PHM greater than PHI greater than human GRF greater than secretin greater than glucagon. Displacement curves of these peptides exhibited slope factors significantly less than unity with the exception of human GRF.


Assuntos
Pulmão/análise , Receptores de Superfície Celular/isolamento & purificação , Animais , Sítios de Ligação , Membrana Celular/análise , Glucagon/metabolismo , Hormônio Liberador de Hormônio do Crescimento/metabolismo , Humanos , Cinética , Peptídeo PHI , Peptídeos/metabolismo , Precursores de Proteínas/metabolismo , Ratos , Receptores de Superfície Celular/metabolismo , Receptores de Peptídeo Intestinal Vasoativo , Secretina/metabolismo , Peptídeo Intestinal Vasoativo/metabolismo
18.
FEBS Lett ; 199(2): 198-202, 1986 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-3009219

RESUMO

Localisation and pharmacological properties of the VIP receptor in human lung sections are described. The receptor density determined by saturation analysis using 125I-VIP is approx. 100 fmol/mg protein, with a Kd of approx. 600 pM. Inhibition of 125I-VIP binding with VIP and related peptides gives a rank order of potency: VIP greater than peptide histidine methionine greater than secretin. Light microscope autoradiography reveals specific VIP binding sites, with a high density over the pulmonary artery smooth muscle and the alveolar walls and with a lower density over the bronchial epithelium.


Assuntos
Pulmão/metabolismo , Receptores de Superfície Celular/metabolismo , Peptídeo Intestinal Vasoativo/metabolismo , Autorradiografia , Ligação Competitiva , Humanos , Radioisótopos do Iodo , Cinética , Receptores de Peptídeo Intestinal Vasoativo
19.
FEBS Lett ; 238(2): 357-60, 1988 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-2844604

RESUMO

Low-density lipoproteins activate isolated human platelets. The mechanism of this activation is unknown, but may involve increased phosphoinositide turnover. We have examined the effect of low-density lipoproteins on intracellular calcium concentrations in platelets loaded with the photoprotein aequorin. The lipoproteins induced concentration-dependent increases in intracellular calcium, associated with shape change and aggregation. These responses could be partially inhibited by the removal of extracellular calcium and by pre-incubation with acetylsalicylic acid. They were also antagonised by agents which increase cellular concentrations of cyclic adenosine and guanosine monophosphates. It is not clear whether the platelet-lipoprotein interaction involves a 'classical' lipoprotein receptor.


Assuntos
Equorina , Plaquetas/metabolismo , Cálcio/sangue , Lipoproteínas LDL/farmacologia , Proteínas Luminescentes , Tetra-Hidroisoquinolinas , Aspirina/farmacologia , Plaquetas/efeitos dos fármacos , GMP Cíclico/análogos & derivados , GMP Cíclico/farmacologia , Humanos , Isoquinolinas/farmacologia , Luminescência , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária
20.
Am J Clin Nutr ; 59(1): 66-9, 1994 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8279405

RESUMO

Water-soluble fiber has been reported to reduce serum cholesterol and consequently, oat bran, which has a high soluble-fiber content, has been recommended as part of a lipid-lowering diet. However, a recent small study of 20 volunteers with low mean serum cholesterol concentrations (4.8 mmol/L) demonstrated no lipid-lowering effect of oat bran. The present study investigated 64 volunteers with cholesterol concentrations much more typical of the UK population (6 mmol/L). Subjects were randomly allocated to receive either a normal-sized helping of an oat-based cereal or a cereal containing no oats for 4 wk and then crossed over to the alternative regimen for a further 4 wk. Small (2.23% and 4.55%) but significant (P < 0.04 and P < 0.05) reductions in total and low-density-lipoprotein cholesterol, respectively, were observed in association with the consumption of oat-based cereal. These data support the view that consumption of oat-based cereals may well contribute usefully to a lipid-lowering diet.


Assuntos
Grão Comestível , Lipídeos/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Ingestão de Alimentos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reino Unido
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