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2.
J Clin Endocrinol Metab ; 86(10): 4711-6, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11600530

RESUMO

We report 98 children who have reached final adult height in a long-term trial of LHRH agonist treatment. These children were 5.3 +/- 2.1 yr old at the start of treatment and were treated with either deslorelin (4 microg/kg.d sc) or histrelin (4-10 microg/kg.d) for an average of 6.1 +/- 2.5 yr. Final height averaged 159.8 +/- 7.6 cm in the 80 girls, which was significantly greater than pretreatment predicted height (149.3 +/- 9.6 cm) but still significantly less than midparental height (MPH) (163.7 +/- 5.6). Final height averaged 171.1 +/- 8.7 cm in the 18 boys, which was significantly greater than pretreatment predicted height (156.1 +/- 14.2 cm) but still significantly less than MPH (178.3 +/- 5.2 cm). However, the average adult height of the 54 children who had less than a 2-yr delay in the onset of treatment was not significantly different from their MPH, and 21 children exceeded MPH. Final height SD score correlated positively with duration of treatment (P < 0.01), midparental height (P < 0.001), predicted height at the start of treatment (P < 0.001), and growth velocity during the last year of treatment (P < 0.001) and correlated inversely with delay in the onset of treatment (P < 0.001), age at the start of treatment (P < 0.001), bone age at the start of treatment (P < 0.001), bone age at the end of treatment (P < 0.001), breast stage at the start of treatment (P = 0.02), and bone age minus chronological age at the start of treatment (P = 0.001). We conclude that LHRH agonist treatment improves the final height for children with rapidly progressing precocious puberty treated before the age of 8 yr for girls or 9 yr for boys. Less delay in the onset of treatment, longer duration of treatment, and lower chronological and bone age at the onset of treatment all lead to greater final height. All children with onset of pubertal symptoms before age 8 in girls and age 9 in boys should be evaluated for possible treatment. Treatment is appropriate in children with rapidly progressing puberty, accelerated bone maturation, and compromise of adult height prediction, regardless of bone age or chronological age at time of evaluation. However, once treatment is considered appropriate, it should be initiated quickly, because longer delays lead to shorter final height. In addition, the longer the treatment is continued, the greater is the final height outcome.


Assuntos
Estatura/efeitos dos fármacos , Hormônio Liberador de Gonadotropina/uso terapêutico , Fatores Etários , Criança , Pré-Escolar , Feminino , Hormônio Liberador de Gonadotropina/análogos & derivados , Humanos , Lactente , Masculino , Puberdade Precoce/tratamento farmacológico , Pamoato de Triptorrelina/análogos & derivados
3.
J Hum Hypertens ; 15(10): 677-80, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11607796

RESUMO

Increased QT dispersion has been associated with ventricular arrhythmia and sudden death in a variety of cardiac disorders. Left ventricular hypertrophy (LVH) has also been associated with increased incidence of sudden cardiac death in patients with essential hypertension. Furthermore, patients with essential hypertension, particularly those with LVH, are more likely to develop ventricular arrhythmias than are the normal population. The relationship between LVH, QT dispersion, complex ventricular arrhythmia and sudden cardiac death in previously untreated patients over long-term follow-up in hypertension has not been reported before and is the purpose of this study. Fifty-nine adult subjects with essential hypertension, who had never been previously on antihypertensive treatment were followed up for a total of 119.2 +/- 26.2 months. QTc (corrected QT), blood pressure, electrocardiograms, and 24-h Holter ECG recordings were performed in all patients at the time of entry to the study. Ventricular arrhythmias were classified using a modified Lown's scoring system. During the follow-up period death occurred in 12 cases (20%) of which only six (10%) deaths were sudden. The findings of this study indicate that LVH and complex ventricular arrhythmias (Lown's score > or =3) are the only significant predictors of sudden death. Although patients who died suddenly had higher systolic and diastolic blood pressures and greater QTc dispersion compared to surviving patients, this difference was statistically not significant. Similarly, when those who died suddenly were compared to those non-cardiac deaths, LVH and complex ventricular arrhythmias were the only significant predictors of sudden death. In spite of increased QTc dispersion in hypertensive patients, this finding was not associated with increased risk of sudden death and only LVH and high grade ventricular arrhythmias identified hypertensive patients at risk of sudden cardiac death over a 10-year follow-up period.


Assuntos
Arritmias Cardíacas/complicações , Morte Súbita Cardíaca/etiologia , Hipertensão/complicações , Hipertrofia Ventricular Esquerda/complicações , Idoso , Arritmias Cardíacas/fisiopatologia , Pressão Sanguínea/fisiologia , Eletrocardiografia Ambulatorial , Feminino , Seguimentos , Humanos , Hipertensão/fisiopatologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Risco , Fatores de Tempo
4.
J Clin Endocrinol Metab ; 85(11): 4036-8, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11095429

RESUMO

Hypothalamic hamartoma is an important cause of precocious puberty in boys. Although the GnRH analogs are known to be effective therapy, there are few studies of the recovery of the pituitary-gonadal axis following long-term treatment. To this end, we studied 11 boys with HH after 8.8+/-3.2 yr (range, 4.0-12.6) of treatment with the GnRH agonist D-Trp6,Pro9,NEt-LHRH. The patients' levels of LH and FSH, testosterone, testis volume, and body mass index were compared with those of six normal boys in pubertal stage IV-V. We found that the patients' mean +/- SD peak GnRH-stimulated LH and FSH had returned to the normal range by 1 yr after stopping therapy. Whereas testosterone returned to normal levels by 1 yr, the patients' testis volume remained smaller than normal until 2 yr after therapy. Ultrasonography revealed diffuse, punctate, echogenic foci in the testicular parenchyma of two patients; these were first observed during GnRH agonist therapy and persisted unchanged after discontinuation of treatment. Neither of these two patients reported pain or testicular discomfort, no mass or irregularity was detected by manual examination in either patient at any time, and levels of beta-hCG and alpha1-fetoprotein were normal. By 4 yr after therapy, all patients had pubertal stage V pubic hair; their body mass index was not different from that of the normal boys at any time point. The dimensions of the patients' hamartomas did not change during or after therapy, and no patient reported new neurological symptoms or signs suggestive of an enlarging lesion at any time during or after discontinuation of treatment. Two families did report episodes of emotional lability and truancy as the patients reentered puberty after discontinuation of treatment.


Assuntos
Hormônio Liberador de Gonadotropina/análogos & derivados , Hormônio Liberador de Gonadotropina/uso terapêutico , Hamartoma/fisiopatologia , Doenças Hipotalâmicas/fisiopatologia , Puberdade Precoce/fisiopatologia , Índice de Massa Corporal , Criança , Pré-Escolar , Hormônio Foliculoestimulante/sangue , Seguimentos , Hamartoma/diagnóstico , Hamartoma/tratamento farmacológico , Humanos , Doenças Hipotalâmicas/diagnóstico , Doenças Hipotalâmicas/tratamento farmacológico , Hormônio Luteinizante/sangue , Masculino , Puberdade/fisiologia , Puberdade Precoce/etiologia , Valores de Referência , Testículo/anatomia & histologia , Testículo/crescimento & desenvolvimento , Testosterona/sangue
5.
J Hypertens ; 18(9): 1297-306, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10994761

RESUMO

BACKGROUND: Left ventricular hypertrophy (LVH) is present in young spontaneously hypertensive rats (SHR) compared with normotensive Wistar-Kyoto (WKY) rats and treatment of SHR with captopril leads to regression of LVH. Hypertrophy produces changes in gene expression for myofibrillar proteins with increased ratios of skeletal to cardiac actin and beta to alpha-myosin heavy chain (MHC). OBJECTIVES: The objective of this study was to follow changes in transcript prevalence for these four proteins during ageing and with captopril treatment in SHR and WKY rats. METHODS: Untreated SHR and WKY rats were studied at 100, 156, 350 and 450 days. Groups at 100 and 350 days were divided into a treatment group (given captopril) and untreated controls. Transcripts were measured using in situ hybridization. RESULTS: Both cardiac and skeletal actin were increased in untreated SHR compared to WKY rats (P<0.01 and P<0.05, respectively). alpha-MHC was increased (P<0.01) whilst beta-MHC was normal in 100-day-old SHR (an age when LVH was present) compared with WKY rats. With ageing, alpha-MHC declined and beta-MHC increased giving the increased ratio of beta to alpha-MHC transcripts reported by other investigators. Treatment of SHR led to a significant decline in skeletal actin transcripts (P< 0.01) and reversed the rise in beta-MHC expression that occurred with ageing (P< 0.01). CONCLUSIONS: LVH in SHR is associated with increased skeletal and cardiac actin transcripts. Despite unequivocal LVH in SHR at 100 days of age, alpha rather than beta-MHC transcripts were increased. Only with ageing did the classically reported increased ratio of beta to alpha-MHC transcripts become apparent Captopril treatment reduced skeletal actin transcripts and reversed the increase in beta-MHC that occurred with ageing.


Assuntos
Actinas/genética , Envelhecimento/fisiologia , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Captopril/farmacologia , Hipertrofia Ventricular Esquerda/tratamento farmacológico , Cadeias Pesadas de Miosina/genética , Actinas/química , Animais , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/fisiologia , Hipertrofia Ventricular Esquerda/patologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Hibridização In Situ , Isomerismo , Masculino , Músculo Esquelético/química , Músculo Esquelético/fisiologia , Miocárdio/química , Miocárdio/metabolismo , Miocárdio/patologia , Cadeias Pesadas de Miosina/química , RNA Mensageiro/análise , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY
7.
J Cardiovasc Risk ; 7(3): 187-90, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11006887

RESUMO

The precise role that abnormal wall stress may play in the pathophysiology of hypertensive heart disease is not known. Hypertension is almost unique in that it ultimately affects all parts of the law of Laplace equation, i.e. intraventricular pressure changes and with the advent of left ventricular hypertrophy both internal radius and wall thickness alter. If heart failure supervenes the components of the equation change once more. This article will discuss the implications of abnormal wall stress at these various stages in hypertensive heart disease.


Assuntos
Hipertensão/fisiopatologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Contração Miocárdica/fisiologia , Anti-Hipertensivos/uso terapêutico , Arritmias Cardíacas/etiologia , Função do Átrio Esquerdo/fisiologia , Cardiomiopatia Dilatada/etiologia , Cardiomiopatia Dilatada/patologia , Cardiomiopatia Dilatada/fisiopatologia , Morte Súbita Cardíaca/etiologia , Insuficiência Cardíaca/etiologia , Ventrículos do Coração/patologia , Ventrículos do Coração/fisiopatologia , Humanos , Hipertensão/complicações , Hipertensão/tratamento farmacológico , Hipertrofia Ventricular Esquerda/etiologia , Hipertrofia Ventricular Esquerda/patologia , Miocárdio/patologia , Fatores de Risco
9.
J Clin Endocrinol Metab ; 85(3): 1114-20, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10720048

RESUMO

Treatment outcome in congenital adrenal hyperplasia is often sub-optimal due to hyperandrogenism, treatment-induced hypercortisolism, or both. We previously reported better control of linear growth, weight gain, and bone maturation in a short term cross-over study of a new four-drug treatment regimen containing an antiandrogen (flutamide), an inhibitor of androgen to estrogen conversion (testolactone), reduced hydrocortisone dose, and fludrocortisone, compared to the effects of a control regimen of hydrocortisone and fludrocortisone. Twenty-eight children have completed 2 yr of follow-up in a subsequent long term randomized parallel study comparing these two treatment regimens. During 2 yr of therapy, compared to children receiving hydrocortisone, and fludrocortisone treatment, children receiving flutamide, testolactone, reduced hydrocortisone dose (average of 8.7 +/- 0.6 mg/m2 x day), and fludrocortisone had significantly (P < or = 0.05) higher plasma 17-hydroxyprogesterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and testosterone levels. Despite elevated androgen levels, children receiving the new treatment regimen had normal linear growth rate (at 2 yr, 0.1 +/- 0.5 SD units), and bone maturation (at 2 yr, 0.7 +/- 0.3 yr bone age/yr chronological age). No significant adverse effects were observed after 2 yr. We conclude that the regimen of flutamide, testolactone, reduced hydrocortisone dose, and fludrocortisone provides effective control of congenital adrenal hyperplasia with reduced risk of glucocorticoid excess. A long term study of this new regimen is ongoing.


Assuntos
Hiperplasia Suprarrenal Congênita/tratamento farmacológico , Antagonistas de Androgênios/uso terapêutico , Anti-Inflamatórios/uso terapêutico , Antineoplásicos Hormonais/uso terapêutico , Desenvolvimento Ósseo/efeitos dos fármacos , Desenvolvimento Ósseo/fisiologia , Flutamida/uso terapêutico , Crescimento/fisiologia , Hidrocortisona/uso terapêutico , Testolactona/uso terapêutico , Hiperplasia Suprarrenal Congênita/complicações , Hiperplasia Suprarrenal Congênita/patologia , Antagonistas de Androgênios/administração & dosagem , Antagonistas de Androgênios/efeitos adversos , Androgênios/sangue , Anti-Inflamatórios/administração & dosagem , Anti-Inflamatórios/efeitos adversos , Antineoplásicos Hormonais/administração & dosagem , Antineoplásicos Hormonais/efeitos adversos , Criança , Pré-Escolar , Feminino , Flutamida/administração & dosagem , Flutamida/efeitos adversos , Seguimentos , Hormônios/sangue , Humanos , Hidrocortisona/administração & dosagem , Hidrocortisona/efeitos adversos , Masculino , Testolactona/administração & dosagem , Testolactona/efeitos adversos , Aumento de Peso/efeitos dos fármacos
10.
AJR Am J Roentgenol ; 172(5): 1235-8, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10227495

RESUMO

OBJECTIVE: The purpose of this study was to describe the serial sonographic findings and clinical and laboratory data obtained during follow-up of patients with congenital adrenal hyperplasia in whom testicular adrenal rest tissue develops. MATERIALS AND METHODS: We retrospectively reviewed testicular sonography and laboratory data for 12 patients with congenital adrenal hyperplasia who also had intratesticular masses consistent with adrenal rest tissue. The studies were done during follow-up that ranged from 7 months to 10 years. RESULTS: During follow-up of 11 of the 12 patients after the initial sonographic diagnosis, the testicular adrenal rest tissue either remained stable in size (n = 1), grew larger or smaller (n = 9), disappeared (n = 4), or reappeared after disappearing (n = 3). In one patient, the testicular adrenal rest tissue grew very rapidly in a 1-month interval. Discordant changes in the testicular adrenal rest tissue were noted in 10 patients with bilateral masses. We found no relationship between the change in size of the masses and clinical control (based on 17-hydroxyprogesterone level) at the time of sonography. CONCLUSION: In patients with congenital adrenal hyperplasia who have testicular masses detected sonographically, testicular adrenal rest tissue is the most likely diagnosis. Testicular adrenal rest tissue may remain stable in size, grow larger or smaller, or disappear during sonographic follow-up. The change in size may be marked, may occur very rapidly, and, in our study cohort, was not related to short-term clinical control based on 17-hydroxyprogesterone level at the time of sonography.


Assuntos
Hiperplasia Suprarrenal Congênita/complicações , Tumor de Resto Suprarrenal/diagnóstico por imagem , Neoplasias Testiculares/diagnóstico por imagem , Hiperplasia Suprarrenal Congênita/diagnóstico por imagem , Tumor de Resto Suprarrenal/complicações , Criança , Humanos , Masculino , Estudos Retrospectivos , Neoplasias Testiculares/complicações , Testículo/diagnóstico por imagem , Ultrassonografia
11.
J Hum Hypertens ; 13(3): 185-90, 1999 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10204815

RESUMO

The objective of this analysis was to determine whether changes in baroreflex sensitivity (BRS) within 35 hypertensive patients (25 M, 10 F, mean age 47 years) treated with beta-blockade as monotherapy relate to reductions in ambulatory blood pressure (BP) or its variability. BP was recorded intra-arterially directly from the brachial artery before and during submaximal exercise. BRS was determined by the phenylephrine injection technique. MAP and its variability were determined for the awake period of 24-h BP monitoring. Subjects were randomised to one of atenolol, metoprolol, pindolol, or propranolol, and restudied after a mean of 5 months. Beta-blockade increased BRS in 24 patients and decreased BRS in 11. BRS increased from 6.53+/-4.94 to 9.40+/-8.62 ms/mm Hg (mean +/- s.d.) (P<0.01). Waking ambulatory MAP decreased from 125.8+/-15.8 to 106.4+/-16.2 mm Hg (P<0.0001), but its variability did not change. Higher BRS after chronic beta-blockade was associated with a decrease in waking ambulatory MAP (r = -0.55, P<0.001), but not with its variability (r = -0.08). Beta-blockade attenuated the pressor response to exercise, but there was a positive relationship between the effect of beta-blockade on BRS, and on the rise in systolic BP during bicycling (r = 0.63; P<0.001). Any dampening effect of beta-blockade on BP variability at rest in hypertensive patients with the greatest increase in BRS may be offset by increased pressor responses to physical activity such as exercise. Consequently, BP variability is unaffected, even though reductions in ambulatory BP during chronic beta-blockade are inversely related to changes in BRS. BP responses to beta-blockade may be a function of the action of this class of drugs on BRS. However, there is considerable variation, between subjects, in their effect on BRS. This may have implications for other conditions, such as dilated cardiomyopathy, or following myocardial infarction, in which improvement in BRS is one mechanism by which beta-adrenoceptor blockade could improve survival.


Assuntos
Antagonistas Adrenérgicos beta/uso terapêutico , Barorreflexo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Hipertensão/tratamento farmacológico , Adolescente , Agonistas alfa-Adrenérgicos , Adulto , Idoso , Atenolol/uso terapêutico , Exercício Físico/fisiologia , Teste de Esforço , Feminino , Seguimentos , Frequência Cardíaca/efeitos dos fármacos , Humanos , Hipertensão/fisiopatologia , Masculino , Metoprolol/uso terapêutico , Pessoa de Meia-Idade , Pindolol/uso terapêutico , Prognóstico , Propranolol/uso terapêutico
12.
J Clin Endocrinol Metab ; 84(1): 44-9, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9920060

RESUMO

Although the GnRH agonist analogs have become an established treatment for precocious puberty, there have been few long term studies of reproductive function and general health after discontinuation of therapy. To this end, we compared peak LH and FSH after 100 microg sc GnRH, estradiol, mean ovarian volume (MOV), age of onset and frequency of menses, body mass (BMI), and incidence of neurological and psychiatric problems in 2 groups of girls: those with precocious puberty due to hypothalamic hamartoma (HH; n 18) and those with idiopathic precocious puberty (IPP; n = 32) who had been treated with deslorelin (4-8 microg/kg x day, s.c.) or histrelin (10 microg/kg x day, s.c.) for 3.1-10.3 yr and were observed at 1, 2, 3, and 4-5 yr after discontinuation of treatment. The endocrine findings were also compared to those in 14 normal perimenarcheal girls. There were no differences between the HH and IPP groups in age or bone age at the start of treatment, at the end of treatment, or during GnRH analog therapy. We found that whereas the peak LH level was higher in HH than in IPP girls before (165.5 +/- 129 vs. 97.5 +/- 55.7; P < 0.02) and at the end (6.8 +/- 6.0 vs. 3.9 +/- 1.8 mIU/mL; P < 0.05) of therapy, this difference did not persist at any of the posttherapy time points. LH, FSH, and estradiol rose into the pubertal range by 1 yr posttherapy in both HH and IPP. However, the mean posttherapy peak LH levels in both HH and IPP groups tended to be lower than normal, whereas the peak FSH levels were not different from normal, so that the overall posttherapy LH/FSH ratio was decreased compared to that in the normal girls (HH, 2.7 +/- 0.3; IPP, 2.6 +/- 0.1; normal, 5.2 +/- 4.8; P < 0.05). The MOV was larger in HH than IPP at the end of treatment (3.7 +/- 3.5 vs. 2.0 +/- 1.2 mL; P < 0.05) and tended to increase in both groups over time to become larger than that in normal girls by 4-5 yr posttherapy (HH, 14.9 +/- 12.9; IPP, 7.6 +/- 2.2; normal, 5.4 +/- 2.5 mL; P < 0.05). Whereas the onset of spontaneous menses varied widely in both groups, once menses had started, the HH group had a higher incidence of oligomenorrhea. Pelvic ultrasonography revealed more than 10-mm hypoechoic regions in 4 HH patients, 15 IPP patients, and 3 normal girls, all of whom were reporting regular menses. Live births of normal infants were reported by 2 HH and 2 IPP patients, and elective terminations of pregnancy were reported by 1 HH and 2 IPP patients. BMI was greater than normal in HH and IPP both before treatment and at all posttherapy time points and tended to be higher in the HH patients. Marked obesity (BMI, +2 to +5.2 SD score) was observed in 5 HH and 6 IPP patients, 1 of whom had a BMI of +2.5 SD score and developed acanthosis nigricans, insulin resistance, and hyperglycemia. Seizure disorders developed during GnRH analog therapy in 5 HH and 1 IPP patient, and 2 additional HH girls developed severe depression and emotional lability posttherapy. Although the mean anterior-posterior dimension of the hamartoma was larger in the HH patients with seizure than in those who were seizure free (1.7 +/- 1.2 vs. 0.9 +/- 0.4 cm; P < 0.05), no change in hamartoma size was observed either during or after therapy, and no patient has reported the onset of a seizure disorder posttherapy. Other than a tendency toward a larger MOV, a higher incidence of oligomenorrhea, obesity, and frequency of neurological disorders, recovery of the reproductive axis after GnRH analog therapy was not markedly different in HH compared to IPP. Continued follow-up of these patients may determine whether the decreased LH responses and increased BMI in both groups compared to those in normal girls remain clinically significant problems.


Assuntos
Hormônio Liberador de Gonadotropina/análogos & derivados , Hamartoma/tratamento farmacológico , Doenças Hipotalâmicas/tratamento farmacológico , Puberdade Precoce/tratamento farmacológico , Reprodução/efeitos dos fármacos , Adolescente , Criança , Pré-Escolar , Estradiol/sangue , Feminino , Hormônio Foliculoestimulante/sangue , Seguimentos , Hormônio Liberador de Gonadotropina/uso terapêutico , Hamartoma/fisiopatologia , Humanos , Doenças Hipotalâmicas/fisiopatologia , Hormônio Luteinizante/sangue , Gravidez , Puberdade Precoce/fisiopatologia , Pamoato de Triptorrelina/análogos & derivados
13.
Clin Sci (Lond) ; 95(4): 453-8, 1998 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9748421

RESUMO

1. This study examined the effect of an acute injection of contrast medium on generation of arrhythmias in diseased hearts in man.2. Subjects were 100 patients in sinus rhythm undergoing cardiac catheterization in whom good quality echocardiograms could be obtained. The subjects comprised 78 males and 22 females aged 37-83 years.3. Arrhythmia induced by left ventricular angiography ranged from nil to brief bursts of ventricular tachycardia. There was a strongly positive relationship between left ventricular internal dimension in diastole (LVIDd) and induced arrhythmia. Out of 26 patients, 25 developed arrhythmia when LVIDd>=5 cm (96%), but only 24 out of 74 patients developed arrhythmia when LVIDd<5 cm (32%) (P<0.001). In non-dilated hearts where K+<4.0 mmol/l, arrhythmia developed in 100% (10 out of 10) of those with left ventricular hypertrophy (LVH), but in only 40% (8 out of 20) without LVH (P<0. 005). Where K+>=4.0 mmol/l, no arrhythmia occurred in patients with LVH but was present in 52% (31 out of 60) of patients without LVH (P<0.005). There were no relationships with age, end-diastolic pressure, blood pressure, ischaemic heart disease or sex of patient. 4. These data support the view that acute injection of contrast medium in humans induces arrhythmias dependent upon the underlying state of the heart, with potentially complex interplay between left ventricular dimension, hypertrophy and potassium status, supporting similar observations in experimental animals.


Assuntos
Arritmias Cardíacas/etiologia , Cateterismo Cardíaco/efeitos adversos , Meios de Contraste/efeitos adversos , Hipertrofia Ventricular Esquerda/complicações , Iopamidol/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Arritmias Cardíacas/sangue , Doenças Cardiovasculares/diagnóstico por imagem , Distribuição de Qui-Quadrado , Ecocardiografia , Eletrocardiografia , Feminino , Humanos , Hipertrofia Ventricular Esquerda/sangue , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Potássio/sangue , Radiografia , Estatísticas não Paramétricas
14.
Cardiovasc Res ; 34(3): 493-503, 1997 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9231032

RESUMO

OBJECTIVE: To assess whether streptomycin, an inhibitor of mechano-sensitive cation channels, has an effect on arrhythmias-induced by an increase of ventricular wall stress in the rat heart. METHODS: The isolated working rat heart preparation was used. Arrhythmias were induced by increasing the afterload (i.e., aortic pressure) against which the left ventricle (LV) pumped for 20 s. This led to an increase of LV pressure, stretch of the LV and an increase in LV wall stress. The number of ventricular premature beats induced by each afterload step was compared in the absence and presence of streptomycin, a compound known to block mechano-sensitive cation channels in the heart. RESULTS: Perfusion with 200 microM streptomycin caused a significant reduction in wall-stress-induced arrhythmias. The effect of streptomycin on arrhythmias reached steady-state within 10 min of application. In the presence of streptomycin, arrhythmias elicited by a 40 mmHg afterload increase were reduced to 38% of control. Arrhythmias induced by an 80 mmHg afterload increase were reduced to 61% of control. Complex arrhythmias (ventricular tachycardia) induced by an afterload increase were also reduced in the presence of 200 microM streptomycin. There was no change in inotropic state with streptomycin, as assessed either by cardiac output or by maximum developed LV pressure. Streptomycin 50 microM (a typical therapeutic plasma concentration in patients) had no effect on wall-stress-induced arrhythmias. CONCLUSIONS: The results were inconsistent with streptomycin acting by modulating inositol phosphate production, or altering the level of intracellular calcium or inotropic state. The anti-arrhythmic effect of streptomycin appears more consistent with inhibition of mechano-sensitive cation channels, suggesting that these ion channels might be involved in causing wall-stress-induced arrhythmias.


Assuntos
Arritmias Cardíacas/tratamento farmacológico , Canais Iônicos/efeitos dos fármacos , Estreptomicina/farmacologia , Estreptomicina/uso terapêutico , Estresse Mecânico , Animais , Ventrículos do Coração , Perfusão , Ratos , Ratos Wistar
15.
J Hypertens ; 15(6): 659-66, 1997 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9218186

RESUMO

OBJECTIVES: (1) To study the effect of low external K and combined low K plus low Mg on the action potential of hypertrophied left ventricular myocytes isolated from the spontaneously hypertensive rat (SHR) and cells from normotensive control rats (NCR). (2) To identify differences in the response of SHR and NCR ventricular myocytes to low K and low K plus low Mg that could contribute to the increased number of arrhythmias observed in hypertrophied hearts. METHODS: Cells were superfused with Tyrode's solution containing 6 mmol/l K and stimulated at 1 Hz. Action potentials were recorded using the patch clamp technique. The effect of low K (2.4 mmol/l) and combined low K plus low Mg (2.4 mmol/l K and nominally zero Mg) on the characteristics of the action potential was measured in nine SHR, eight Wistar-Kyoto rat and 5 Wistar rat cells. RESULTS: With 6 mmol/l K, the action potential was prolonged significantly in SHR cells at 50, 70, 90 and 95% repolarizations. Both low K and low K plus low Mg shortened the action potential significantly only at 70% repolarization in NCR cells. In contrast, both low K and low K plus Mg led to marked action potential shortening at 70 and 90% repolarizations in SHR cells (P < 0.01) and also at 50 and 95% repolarizations (P < 0.05). Combined low K plus low Mg produced no additional effect on the action potential shape either in SHR or in NCR cells compared with that produced by low K alone. Although in SHR cells low K and combined low K plus low Mg produced a greater shortening of the action potential, which extended across a longer period of repolarization, a significant prolongation of the action potential still remained with low K at 50 and 95% repolarizations in SHR cells compared with that in NCR cells. CONCLUSIONS: Low K shortened the action potential both in NCR and in SHR cells but had a much greater effect on the action potential shape in SHR cells. Low K attenuated the difference in action potential shape between SHR and NCR by reducing the longer plateau observed in SHR cells. Combined low K plus low Mg exerted an effect on the action potential shape similar to that of low K alone in all cells. This increased shortening of the action potential produced by low K in SHR cells might be relevant to the increased incidence of arrhythmias associated with left ventricular hypertrophy, perhaps by shortening the wavelength of excitation and encouraging re-entrant arrhythmias, or by increasing the heterogeneity of repolarization within the ventricle.


Assuntos
Coração/efeitos dos fármacos , Coração/fisiopatologia , Hipertensão/fisiopatologia , Potássio/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Arritmias Cardíacas/fisiopatologia , Cardiomegalia/fisiopatologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/patologia , Ventrículos do Coração/fisiopatologia , Humanos , Hipertensão/patologia , Técnicas In Vitro , Magnésio/farmacologia , Masculino , Miocárdio/patologia , Perfusão , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Ratos Wistar
16.
J Cardiovasc Electrophysiol ; 8(6): 700-21, 1997 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9209972

RESUMO

A number of clinical cardiac disorders may be associated with a rise of the intracellular Na concentration (Na(i)) in heart muscle. A clear example is digitalis toxicity, in which excessive inhibition of the Na/K pump causes the Na(i) concentration to become raised above the normal level. Especially in digitalis toxicity, but also in many other situations, the rise of Na(i) may be an important (or contributory) cause of increased cardiac arrhythmias. In this review, we consider the mechanisms by which a raised Na(i) may cause cardiac arrhythmias. First, we describe the factors that regulate Na(i), and we demonstrate that the equilibrium level of Na(i) is determined by a balance between Na entry into the cell, and Na extrusion from the cell. A number of mechanisms are responsible for Na entry into the cell, whereas the Na/K pump appears to be the main mechanism for Na extrusion. We then consider the processes by which an increased level of Nai might contribute to cardiac arrhythmias. A rise of Na(i) is well known to result in an increase of intracellular Ca, via the important and influential Na/Ca exchange mechanism in the cell membrane of cardiac muscle cells. A rise of intracellular Ca modulates the activity of a number of sarcolemmal ion channels and affects release of intracellular Ca from the sarcoplasmic reticulum, all of which might be involved in causing arrhythmia. It is possible that the increase in contractile force that results from the rise of intracellular Ca may initiate or exacerbate arrhythmia, since this will increase wall stress and energy demands in the ventricle, and an increase in wall stress may be arrhythmogenic. In addition, the rise of Na(i) is anticipated to modulate directly a number of ion channels and to affect the regulation of intracellular pH, which also may be involved in causing arrhythmia. We also present experiments in this review, carried out on the working rat heart preparation, which suggest that a rise of Na(i) causes an increase of wall stress-induced arrhythmia in this model. In addition, we have investigated the effect on wall stress-induced arrhythmia of maneuvers that might be anticipated to change intracellular Ca, and this has allowed identification of some of the factors involved in causing arrhythmia in the working rat heart.


Assuntos
Arritmias Cardíacas/metabolismo , Sódio/metabolismo , Potenciais de Ação/fisiologia , Animais , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/fisiopatologia , Transporte Biológico , Cálcio/metabolismo , Proteínas de Transporte/metabolismo , Junções Comunicantes/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Contração Miocárdica/fisiologia , Miocárdio/metabolismo , Trocador de Sódio e Cálcio , ATPase Trocadora de Sódio-Potássio/metabolismo
17.
Cardiovasc Res ; 33(3): 561-72, 1997 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9093526

RESUMO

OBJECTIVES: (1) To determine whether regression of left ventricular hypertrophy (LVH) leads to a reduction in wall stress induced arrhythmia. (2) To determine the relationship between the time course of LVH regression and changes in arrhythmias in the spontaneously hypertensive rat heart. METHODS: 67 male spontaneously hypertensive rats (SHR) and 67 normotensive Wistar Kyoto rats (WKY) rats were studied at 100 days of age. 39 of each were treated with the ACE inhibitor captopril 2 mg/ml in drinking water, and the remaining 28 were controls. At 0, 2, 4, 8 and 16 weeks hearts were removed and perfused in the working heart mode. Control afterload was 80 mm Hg and perfusate K+ was 2.4 mM. Step increases in afterload (20, 40 and 80 mm Hg rises; 20 s duration; 2 min between each) were applied in random order to increase ventricular wall stress and induce arrhythmias. RESULTS: Total number of ventricular premature beats (VPBs) elicited by each afterload step were counted. The ratio of left ventricular weight to body weight in the SHR (an index of LVH) showed a rapid and marked decline with captopril treatment (2.65 +/- s.e.m. 0.07 mg/g after 2 weeks treatment compared to 3.38 +/- 0.08 before treatment; P < 0.01), indicating that captopril produced rapid regression of LVH. In contrast, the number of wall stress-induced arrhythmias in SHR did not show a significant decline over the 16 week treatment period. However, when the effect of regression of LVH on wall thickness was taken into account, and compensation was made for differences in wall stress applied, there did appear to be a slow reduction in arrhythmias in SHR. This decline in VPBs was significant after 16 weeks treatment for 40 and 80 mm Hg rises in afterload (P < 0.05). CONCLUSIONS: Treatment with captopril produced a rapid regression of LVH in the SHR. In contrast, arrhythmias declined more slowly over the 16 week period. There did not appear to be a direct relationship between the degree of regression of LVH and wall stress-induced arrhythmias in this model.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Arritmias Cardíacas/etiologia , Captopril/uso terapêutico , Hipertrofia Ventricular Esquerda/tratamento farmacológico , Animais , Arritmias Cardíacas/tratamento farmacológico , Arritmias Cardíacas/fisiopatologia , Coração/fisiopatologia , Hipertrofia Ventricular Esquerda/complicações , Hipertrofia Ventricular Esquerda/fisiopatologia , Masculino , Perfusão , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Fatores de Tempo
19.
Cancer Invest ; 15(3): 224-6, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9171856

RESUMO

The association between progressive systemic sclerosis (PSS; scleroderma) and malignancy has been a controversial issue in the literature. The present report describes a rare case of concurrent malignant melanoma and PSS. A literature review suggests a possible connection between these two conditions.


Assuntos
Melanoma/complicações , Escleroderma Sistêmico/complicações , Neoplasias Cutâneas/complicações , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Evolução Fatal , Feminino , Humanos , Metástase Linfática , Melanoma/tratamento farmacológico , Melanoma/patologia , Pessoa de Meia-Idade , Escleroderma Sistêmico/patologia , Neoplasias Cutâneas/tratamento farmacológico , Neoplasias Cutâneas/patologia
20.
J Clin Endocrinol Metab ; 81(10): 3535-9, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8855797

RESUMO

Treatment outcome in congenital adrenal hyperplasia is often suboptimal due to hyperandrogenism, treatment-induced hypercortisolism, or both. As a new approach, we hypothesized that the effects of androgen could be blocked by an antiandrogen (flutamide) and an inhibitor androgen to estrogen conversion (testolactone), thus allowing the hydrocortisone dose to be reduced. We conducted a short term pilot study in 12 children with congenital adrenal hyperplasia in a randomised cross-over open design to determine whether flutamide, testolactone, reduced hydrocortisone dose, and fludrocortisone are more effective than hydrocortisone and fludrocortisone treatment in normalizing linear growth, weight gain, and bone maturation. Each regimen was administered for 6 months, with a 3-month washout period, consisting of hydrocortisone and fludrocortisone treatment, between regimens. Compared to hydrocortisone and fludrocortisone treatment, the regimen of flutamide, testolactone, reduced hydrocortisone dose (from 12.9 to 7.9 mg/m2 day), and fludrocortisone produced an increase in plasma 17-hydroxyprogesterone levels (P < 0.05) and a decline in urinary cortisol (P < 0.01), linear growth rate (-0.9 +/- 0.5 vs. 1.4 +/- 0.6 SD U; P = 0.003), weight velocity (-0.80 +/- 4.0 vs 0.6 +/- 0.4 SD U; P = 0.01), and bone maturation (0.6 +/- 0.6 vs. 1.4 +/- 0.9 yr bone age/yr chronological age; P = 0.02). Although no important adverse effects were observed, the known potential for flutamide-induced hepatotoxicity made frequent monitoring essential. We conclude that the regimen of flutamide, testolactone, reduced hydrocortisone does, and fludrocortisone improve the short term control of growth and bone maturation in children with congenital adrenal hyperplasia. Long term studies are required to determine whether this approach can improve these children's growth and development.


Assuntos
Hiperplasia Suprarrenal Congênita/tratamento farmacológico , Flutamida/uso terapêutico , Hidrocortisona/administração & dosagem , Testolactona/uso terapêutico , 17-alfa-Hidroxiprogesterona/sangue , Hiperplasia Suprarrenal Congênita/fisiopatologia , Hormônio Adrenocorticotrópico/sangue , Desenvolvimento Ósseo , Criança , Pré-Escolar , Desidroepiandrosterona/sangue , Feminino , Flutamida/administração & dosagem , Flutamida/efeitos adversos , Humanos , Hidrocortisona/efeitos adversos , Hidrocortisona/uso terapêutico , Hidrocortisona/urina , Lactente , Masculino , Estações do Ano , Testolactona/administração & dosagem , Testolactona/efeitos adversos , Aumento de Peso
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