Aircraft noise and incidence of hypertension--gender specific effects

Recent studies show associations between aircraft noise and cardiovascular outcomes such as hypertension. However, these studies were mostly cross-sectional and there are uncertainties regarding potential gender differences as well as sensitive subgroups. In this study, we investigated the cumulative incidence of hypertension in relation to aircraft noise exposure among Swedish men and women living in Stockholm County. A total of 4721 subjects, aged 35–56 at baseline, were followed for 8–10 years. The population was selected according to family history of diabetes, which was present for half of the subjects. The exposure assessment was performed by geographical information systems and based on residential history during the period of follow-up. Blood pressure was measured at baseline and at the end of follow-up. Additional information regarding diagnosis and treatment of hypertension as well as various lifestyle factors was provided by questionnaires. In the overall population, no increased risk for hypertension was found among subjects exposed to aircraft noise ≥50 dB(A) L_den; relative risk (RR) 1.02 (95% CI 0.90–1.15). When restricting the cohort to those not using tobacco at the blood pressure measurements, a significant risk increase per 5 dB(A) of aircraft noise exposure was found in men; RR 1.21 (1.05–1.39), but not in women; RR 0.97 (0.83–1.13). In both sexes combined, an increased risk of hypertension related to aircraft noise exposure was indicated primarily among those reporting annoyance to aircraft noise; RR 1.42 (1.11–1.82). No consistent effect modification was detected for any of the cardiovascular risk factors under investigation although a family history of diabetes appeared to modify the risk in women. In conclusion, the results suggest an increased risk of hypertension following long-term aircraft noise exposure in men, and that subjects annoyed by aircraft noise may be particularly sensitive to noise related hypertension.     

血浆内皮素对慢性病黄疸发生的影响

血浆内皮素（ＥＴ）是血管内皮细胞分泌的,由２１个氨基酸组成的具有强烈缩血管作用的活性肽,其与心血管系统在生理和病理方面的关系已受到广泛关注。近年来有研究表明,肝脏可能与ＥＴ的产生和清除有着较密切的关系。用ＥＴ灌注鼠肝可导致肝内胆汁的淤滞［１］,由此推测黄疸的发生可能与ＥＴ的增多有某种联系。材料与方法一、病例选择根据１９９０年全国病毒性肝炎会议修订的诊断标准,选择我院门诊及病房接治的慢性肝病患者５１例,女２４例,年龄为２９～７６岁,平均５５．３岁。其中肝硬化３１例,伴黄疸者１５例（ＴＢ＞２．０ｍｇ…     

Pharmacokinetics and distribution of flucloxacillin in pacemaker patients

Summary The pharmacokinetics of flucloxacillin in plasma and tissue fluid after i.v. infusion of 1 g was analyzed according to an open two-compartment model in 19 patients with bradyarrhythmias (mean age 70.8 years) admitted for implantation or replacement of a permanent pacemaker system. After the first infusion of flucloxacillin (5 min), the distribution phase was rapid (t_1/2=0.13 h). The plasma half-life of elimination (t_1/2) was 1.51 h, which is almost twice as long as reported in healthy volunteers. Total plasma clearance (93.1 ml/min) was also lower than is usually found in healthy individuals, due to low renal clearance of flucloxacillin (60.2 ml/min). The total apparent volume of distribution during the -phase (Vd_area) was 0.172 l/kg and distribution in the central compartment (V_c) 0.064 l/kg. In each patient plasma protein binding and drug distribution to plasma water, proteins and blood cells in whole blood were determined. Binding in plasma to proteins was 91.0% and distribution to blood cells in whole blood 13.8%. The mean distribution volume of free flucloxacillin during the -phase (V_{d free}) was 2.18 l/kg, which exceeds total body water, suggesting possible intracellular distribution and substantial tissue binding. Plasma concentrations of flucloxacillin after the fourth dose (1 g t.i.d.) were very similar to those obtained after the first infusion and those predicted from the single dose kinetics. The concentration of flucloxacillin in fluid from the pacemaker pockets in 5 patients averaged 12.1 µg/ml and 9.5 µg/ml at 1 and 5 h, respectively, which was more than ten times the MIC-values for Staphylococcus aureus and S. epidermidis. The average concentration ratio (tissue fluid/plasma) was 0.57. Thus the pharmacokinetics of flucloxacillin in these elderly patients exhibited marked differences from what has been found in healthy volunteers. Despite the high degree of plasma protein binding, flucloxacillin appears to distribute rapidly and efficiently to extravascular compartments, such as a pacemaker pocket.