二甲双胍在多囊卵巢综合征的作用

生殖及代谢异常是多囊卵巢综合征(PCOS)的特征性表现。已证实高胰岛素血症及胰岛素抵抗,导致血中雄激素水平过高,是PCOS的重要发病机制。二甲双胍(metformin)称为胰岛素增敏剂,用于治疗PCOS后,可减轻高雄激素血症,使月经周期规律,改善卵巢对诱导排卵的反应,提高妊娠率,降低早孕流产率,且能减低发展为II型糖尿病及心血管疾病的危险性。本文就国外近年有关metformin运用于PCOS的进展作一综述。     

Enhanced dispersion of atrial refractoriness as an electrophysiological substrate for vulnerability to atrial fibrillation in patients with paroxysmal atrial fibrillation.

Atrial electrical remodeling plays a part in recurrence of atrial fibrillation (AF). It has been related to an increase in heterogeneity of atrial refractoriness that facilitates the occurrence of multiple reentry wavelets and vulnerability to AF. AIM: To examine the relationship between dispersion of atrial refractoriness (Disp_A) and vulnerability to AF induction (A_Vuln) in patients with clinical paroxysmal AF (PAF). METHODS: Thirty-six patients (22 male; age 55+/-13 years) with > or =1 year of history of PAF (no underlying structural heart disease--n=20, systemic hypertension--n=14, mitral valve prolapse--n=1, surgically corrected pulmonary stenosis--n=1), underwent electrophysiological study (EPS) while off medication. The atrial effective refractory period (AERP) was assessed at five different sites--high (HRA) and low (LRA) lateral right atrium, high interatrial septum (IAS), proximal (pCS) and distal (dCS) coronary sinus--during a cycle length of 600 ms. AERP was taken as the longest S1-S2 interval that failed to initiate a propagation response. Disp_A was calculated as the difference between the longest and shortest AERP. A_Vuln was defined as the ability to induce AF with 1-2 extrastimuli or with incremental atrial pacing (600-300 ms) from the HRA or dCS. The EPS included analysis of focal electrical activity based on the presence of supraventricular ectopic beats (spontaneous or with provocative maneuvers). The patients were divided into group A--AF inducible (n=25) and group B--AF not inducible (n=11). Disp_A was analyzed to determine any association with A_Vuln. Disp_A and A_Vuln were also examined in those patients with documented repetitive focal activity. Logistic regression was used to determine any association of the following variables with A_Vuln: age, systemic hypertension, left ventricular hypertrophy, left atrial size, left ventricular function, duration of PAF, documented atrial flutter/tachycardia and Disp_A. RESULTS: There were no significant differences between the groups with regard to clinical characteristics and echocardiographic data. AF was inducible in 71% of the patients and noninducible in 29%. Group A had greater Disp_A compared to group B (105+/-78 ms vs. 49+/-20 ms; p=0.01). Disp_A was >40 ms in 50% of the patients without A_Vuln and in 91% of those with A_Vuln (p=0.05). Focal activity was demonstrated in 14 cases (39%), 57% of them with A_Vuln. Disp_A was 56+/-23 ms in this group and 92+/-78 ms in the others (p=0.07). Using logistic regression, the only predictor of A_Vuln was Disp_A (p=0.05). CONCLUSION: In patients with paroxysmal AF, Disp_A is a major determinant of A_Vuln. Nevertheless, the degree of nonuniformity of AERP appears to be less important as an electrophysiological substrate for AF due to focal activation.     

Modulation of arterial stiffness with intensive competitive training.

BACKGROUND: Aerobic exercise training has been associated with beneficial effects on the cardiovascular system, improving arterial compliance, possibly related to a positive impact on the endothelium. The effects of competitive aerobic exercise are not so well documented. This prompted us to evaluate the possible modulation of arterial properties in a group of athletes and their response to the aging process. METHODS: 423 healthy males were enrolled in a cross-sectional study, 212 of whom were competitive athletes and 211 were controls. All underwent carotid-femoral pulse wave velocity (PWV) evaluation, and casual blood pressure and other relevant anthropometric data were evaluated. RESULTS: To control the effects of age, each group was divided into two subgroups with an age cut-point of 20 years. PWV was 6.3 +/- 0.9 m/s (athletes) vs. 7.0 +/- 1.0 m/s (controls) for ages <20 years, and 7.6 +/- 1.2 m/s (athletes) vs. 8.1 +/- 0.9 m/s (controls) for ages >20 years, with statistically significant differences in both comparisons. A linear regression model with logarithmic tendency analysis with age as the independent determinant of PWV revealed a different progression of age-related deterioration of aortic compliance between the two groups (athletes and controls). CONCLUSIONS: Our data documented better compliance indices in competition athletes compared with controls, which may reflect optimization of endothelial function. This improvement was age-dependent, being less pronounced as the athletes grow older, which could be due partially to sustained stretching effects on the arterial walls in long-term competitors.     

Estimation of salt intake by urinary sodium excretion in a Portuguese adult population and its relationship to arterial stiffness.

BACKGROUND: Portugal has one of the highest mortality rates from stroke, a high prevalence of hypertension and probably a high salt intake level. AIM: To evaluate Portuguese salt intake levels and their relationship to blood pressure and arterial stiffness in a sample of four different adult populations living in northern Portugal. METHODS: A cross-sectional study evaluating 24-hour urinary excretion of sodium (24 h UNa+), potassium and creatinine, blood pressure (BP), and pulse wave velocity (PWV) as an index of aortic stiffness in adult populations of sustained hypertensives (HT), relatives of patients with previous stroke (Fam), university students (US) and factory workers (FW), in the context of their usual dietary habits. RESULTS: We evaluated a total of 426 subjects, mean age 50 +/- 22 years, 56% female, BMI 27.9+/-5.1, BP 159/92 mmHg, PWV 10.4+/-2.2 m/s, who showed mean 24h UNa+ of 202 +/- 64 mmol/d, corresponding to a daily salt intake of 12.3 g (ranging from 5.2 to 24.8). The four groups were: HT: n = 245, 49 +/- 18 years, 92% of those selected, 69% treated, BP 163/94 mmHg, PWV 11.9 m/s, 24 h UNa+ 212 mmol/d, i.e. 12.4 g/d of salt); Fam: n = 38, 64 +/- 20 years, 57 % of those selected, BP 144/88 mmHg, PWV 10.5 m/s, 24 h UNa+ 194 mmol/d, i.e. 11.1 g/d of salt; US: n = 82, 22 +/- 3 years, 57% of those selected, BP 124/77 mmHg, PWV 8.7 m/s, 24h UNa+ 199 mmol/d, i.e. 11.3 g/d of salt; FW: n = 61, 39 9 years, 47% of those selected, BP 129/79 mmHg, PWV 9.5 m/s, 24 h UNa+ 221 mmol/d, i.e. 12.9 g/d of salt. The ratio of urinary sodium/potassium excretion (1.9 (0.4) was significantly higher in HT than the other three groups. In the 426 subjects, 24h UNa+ correlated significantly (p < 0.01) with systolic BP (r = 0.209) and with PWV (r=0.256) after adjustment for age and BP. Multivariate analysis showed that BP, age and 24h UNa+ correlated independently with PWV taken as a dependent variable. CONCLUSIONS: Four different Portuguese populations showed similarly high mean daily salt intake levels, almost double those recommended by the WHO. Overall, high urinary sodium excretion correlated consistently with high BP levels and appeared to be an independent determining factor of arterial stiffness. These findings suggest that Portugal in general has a high salt intake diet, and urgent measures are required to restrict salt consumption in order to prevent and treat hypertensive disease and to reduce overall cardiovascular risk and events.     

Rupture of a submitral ventricular aneurysm into the left atrium diagnosed by transesophageal echocardiography.

Submitral ventricular aneurysm is a thoroughly studied pathology but is not well known due to its rarity. Clinically, it is manifested by symptoms and signs of heart failure, mitral regurgitation and/or ventricular arrhythmias, and may be associated with thromboembolic phenomena and myocardial ischemia due to compression of the coronary arteries by the aneurysm. A rare complication of this type of aneurysm is rupture into the left atrium. Transthoracic echocardiography plays an important role in the definitive diagnosis of this pathology, although the role of transesophageal echocardiography in the evaluation of these patients is less known. We report a case of a submitral ventricular aneurysm complicated by rupture into the left atrium, which was diagnosed by transesophageal echocardiography.     

Dose response and toxicity of doxorubicin microspheres in a rat tumor model.

The therapeutic response and toxic effects of chemotherapy using several doses of doxorubicin in conventional solution form or bound to an ion-exchange resin were compared in a rat tumor model, to assess the relationship of drug dose to therapeutic efficacy and associated toxicity. Single bolus injections of 3.0, 4.5, 6.0, 7.5 and 9.0 mg/kg were administered via the abdominal aorta to rats bearing hindlimb tumors. Tumor size was measured serially and the growth rates of treated groups were compared with a control growth curve. In addition, the effect of empty microspheres on tumor growth rate was assessed. The levels of circulating white blood cells were measured and compared to control levels to provide an indication of the severity of bone marrow toxicity experienced by each form of treatment. Finally, any difference in the distribution of doxorubicin to tumor, hindlimb and cardiac tissue following administration of doxorubicin as free drug or on microspheres was ascertained. Empty ion-exchange resin exerted a small although significant detrimental effect on tumor growth which may be explained by the embolization of microspheres in the precapillary blood vessels of the tumor resulting in a transient delay in tumor growth rate. The lowest dose of doxorubicin produced a significantly better therapeutic response when administered in the free drug form, but higher doses elicited an equivalent delay in tumor growth for both drug microsphere and free drug groups in a dose-dependent manner, with the maximum anti-tumor response occurring at the highest dose. Treatment with free doxorubicin at high doses resulted in significant reductions of circulating white blood cells suggesting the occurrence of bone marrow toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ictal chronology and interictal spikes predict perfusion patterns in temporal lobe epilepsy: a multivariate study.

Typical (TPP) and atypical (APP) perfusion patterns (PP) may be seen in ictal SPECT of patients with temporal lobe epilepsy (TLE). APP may pose problem in the lateralization of the epileptogenic zone (EZ). We aimed to investigate predictive variables for the occurrence of TPP and APP. Fifty-one TLE patients were submitted to successful anterior-mesial temporal lobectomy. Univariate (UVA) and multivariate (MVA) analysis were performed upon clinical data, distribution of interictal spikes, and ictal chronology of seizures. From MVA, a final predictive model (FPM) was determined to better predict TPP and APP. Forty patients showed TPP (78.5%) and 11 patients APP (21.5%). Accuracy of ictal SPECT was higher in the unilateral (UIS) than in the bilateral (BIS) interictal spikes group (P = 0.05). FPM showed that patients exhibiting BIS, with shorter proportion of the electrographic seizure occurring after completion of tracer injection, and longer clinical than EEG seizure duration had more APP (P = 0.003). Generalized tonic-clonic seizures did not result in more APP. We concluded that analysis of ictal SPECT in TLE requires the knowledge of TPP and APP, the distribution of interictal spikes on temporal lobes and the ictal chronology of seizures. BIS showed that beyond a more complex epileptogenicity and seizure propagation, they may also lead to APP.