Role of the Vascular Wall in Sodium Homeostasis and Salt Sensitivity

Excessive sodium intake is associated with both hypertension and an increased risk of cardiovascular events, presumably because of an increase in extracellular volume. The extent to which sodium intake affects extracellular volume and BP varies considerably among individuals, discriminating subjects who are salt-sensitive from those who are salt-resistant. Recent experiments have shown that, other than regulation by the kidney, sodium homeostasis is also regulated by negatively charged glycosaminoglycans in the skin interstitium, where sodium is bound to glycosaminoglycans without commensurate effects on extracellular volume. The endothelial surface layer is a dynamic layer on the luminal side of the endothelium that is in continuous exchange with flowing blood. Because negatively charged glycosaminoglycans are abundantly present in this layer, it may act as an intravascular buffer compartment that allows sodium to be transiently stored. This review focuses on the putative role of the endothelial surface layer as a contributor to salt sensitivity, the consequences of a perturbed endothelial surface layer on sodium homeostasis, and the endothelial surface layer as a possible target for the treatment of hypertension and an expanded extracellular volume.     

Risk factors for infection after liver transplantation

Infection is a common cause of morbidity and mortality after liver transplantation. Risk factors relate to transplantation factors, donor and recipient factors. Transplant factors include ischaemia-reperfusion damage, amount of intra-operative blood transfusion, level and type of immunosuppression, rejection, and complications, prolonged intensive care stay with dialysis or ventilation, type of biliary drainage, repeat operations, re-transplantation, antibiotics, antiviral regimen, and environment. Donor risk factors include infection, prolonged intensive care stay, quality of the donor liver (e.g. steatosis), and viral status. For the recipient the most important are MELD score >30, malnutrition, renal failure, acute liver failure, presence of infection or colonisation, and immune status for viruses like cytomegalovirus. In recent years it has become clear that genetic polymorphisms in innate immunity, especially the lectin pathway of complement activation and in Toll-like receptors importantly contribute to the infection risk after liver transplantation. Therefore, the risk for infections after liver transplantation is a multifactorial problem and all factors need attention to reduce this risk.     

The renin-angiotensin system in malignant hypertension revisited: plasma renin activity, microangiopathic hemolysis, and renal failure in malignant hypertension

BACKGROUND: Malignant hypertension is a renin-dependent form of hypertension. However, the variations in renin-angiotensin system (RAS) activation in malignant hypertension are not completely understood. A proposed mechanism for ongoing RAS activation is the presence of microangiopathic hemolysis resulting in renovascular ischemia. METHODS: We prospectively examined the association between plasma renin activity (PRA), microangiopathic hemolysis, and renal dysfunction in 30 consecutive patients with malignant hypertension (n=18) and severe hypertension (n=12). The PRA and aldosterone were measured in the supine position and before initiating therapy. RESULTS: The PRA was 8.8 ng angiotensin I (AI)/mL/h (interquartile range [IQR] 4.8-20) in malignant hypertensive patients and 2.8 ng AI/mL/h (IQR 0.6-6.3) in patients with severe hypertension (P<.01). Aldosterone was 1.30+/-1.02 nmol/L in patients with malignant hypertension compared with 0.44+/-0.37 nmol/L in those with severe hypertension (P<.01). In malignant hypertension, PRA highly correlated with lactic dehydrogenase (LDH) (r=0.76, P<.001), meaning that 58% of the variations in PRA could be explained by LDH. The PRA positively correlated with serum creatinine values at presentation (r=0.50, P=.007), but adjustment for LDH abolished the effect of PRA on creatinine (P=.24). CONCLUSIONS: The PRA and aldosterone were markedly elevated in patients with malignant hypertension but not in severely hypertensive patients despite small differences in blood pressure (BP). The strong logarithmic correlation between PRA, microangiopathic markers, and renal dysfunction suggests a renin-mediated acceleration of vascular damage and renal dysfunction in patients with malignant hypertension.     

Persistent trigeminal artery associated with trigeminal neuralgia: hypothesis of neurovascular compression

Introduction The aim of this study was to determine the prevalence of persistent trigeminal artery (PTA) associated with trigeminal neuralgia (TN). Methods From January 1998 to January 2004, 288 MRI scans of patients examined for trigeminal deficits were retrospectively evaluated. MRI was performed at 1.5 T. Scan protocols included cerebral TSE T2-weighted imaging, contrast enhanced SE T1-weighted imaging and thin-section 3D T2-weighted imaging of the temporal bones, 3D TOF pre- and postcontrast MR angiography. TN was defined as episodes of intense stabbing, electric shock-like pain in areas of the face supplied by the trigeminal branches. Neurovascular compression (NVC) was assumed to be present if the patient showed clinical features of TN, if there was contact between an artery and the trigeminal nerve on the affected side, and if other pathology had been excluded. The prevalence and confidence intervals were calculated (95% CI of the prevalence was based on the exact binomial distribution). Results Of 288 patients, 136 matched the criteria for TN. In this series a PTA was detected in three patients, which in all patients was on the same side as the TN. The prevalence of a PTA in patients presenting with TN was 2.2% (CI 0.005–0.06). Conclusion Previous studies have shown PTA as an incidental finding in 0.1–0.6% of cerebral angiograms. The prevalence of a PTA in patients with TN was 2.2%. With respect to the clinical significance, a PTA has to be considered in TN and the diagnosis of a PTA can easily be made using MR imaging/angiography.     

高血压患者常规行眼底镜检查的价值：系统性综述

目的 评价高血压患者常规眼底检查的价值。 设计 系统性综述。 入选患者 ≥19岁的高血压视网膜病变患者。 数据来源 从1990起的Medline、Embase和Cochrane图书馆的数据库。 综述方法 纳入的研究包括：评估了高血压视网膜病变性失明与心血管危险因素之间联系的研究。研究必须由2名或2名以上观察者得出一致评价结果，用K统计分析表示。对于高血压患者，研究高血压视网膜病变与高血压脏器损害之间的联系。对于非选择的血压正常者和无糖尿病高血压患者，评价高血压视网膜病变与心血管危险因素之间的联系。 结果 由于观察者之间的巨大差异限制了对视网膜微血管变化的评价。高血压视网膜病变与血压水平之间的阳性及阴性预测值均较低（分别为47％～72％和32％-67％）。除了视网膜病变与脑卒中之间有联系外，视网膜微血管变化与心血管危险因素之问无明显联系。但在血压正常的视网膜病变患者中同样发现脑卒中增加。这些研究没有对高血压脏器损害的其他预测因子进行调整。 结论 研究表明，高血压患者常规进行眼底检查有额外价值的观点尚缺乏证据。     

A framework for the comparison of mobile patient monitoring systems

A mobile patient monitoring system makes use of mobile computing and wireless communication technologies for continuous or periodic measurement and analysis of biosignals of a mobile patient. In a number of trials these systems have demonstrated their user-friendliness, convenience and effectiveness for both patients and healthcare professionals. In this paper we propose a generic architecture, associated terminology and a classificatory framework for comparing mobile patient monitoring systems. We then apply this comparison framework to classify six mobile patient monitoring systems selected according to the following criteria: use of diverse mobile communication techniques, evidence of practical trials and availability of sufficient published scientific information. We also show how to use this framework to determine feature sets of prospective real-time mobile patient monitoring systems using the example of epilepsy monitoring. This paper is aimed at both healthcare professionals and computer professionals. For healthcare professionals, this paper provides a general understanding of technical aspects of the mobile patient monitoring systems and highlights a number of issues implied by the use of these systems. The proposed framework for comparing mobile patient monitoring systems can be used by healthcare professionals to determine feature sets of prospective mobile patient monitoring systems to address particular healthcare related needs. Computer professionals are expected to benefit by gaining an understanding of the latest developments in the important emerging application area of mobile patient monitoring systems.     

Ethnic disparities in the incidence, presentation and complications of malignant hypertension

BACKGROUND: The incidence of malignant hypertension has declined after the introduction of antihypertensive agents. However, previous reports have suggested that malignant hypertension may be relatively common in multi-ethnic populations. The aim of this study was to compare ethnic disparities in the incidence, clinical characteristics and complications of malignant hypertension. METHODS: A retrospective cohort study on malignant hypertension in a multi-ethnic population in Amsterdam, the Netherlands, between August 1993 and August 2005. RESULTS: A total of 122 patients with malignant hypertension were included, mean age 44 years (+/- 12), 66% were men and 47% were black. The incidence rate remained approximately 2.6 (+/- 0.9) per 100,000 per year and was higher among blacks. Black individuals had higher systolic blood pressure (234 +/- 23 versus 225 +/- 22, P = 0.03) and more renal dysfunction compared with white individuals (39% with serum creatinine > 300 micromol/l versus 22%, P = 0.04). Hypertension was previously diagnosed in 58% of all patients, 37% received medication, and 23% stopped their drugs before admission. Health insurance was absent in 25% of black and 2% of white patients (P < 0.01). Secondary causes were identified in 40% of white and 10% of black subjects (P < 0.01). After a mean follow-up of 4.0 +/- 3.2 years 10% had died and 19% needed renal replacement therapy. Renal failure was more frequent in black than in white individuals (hazard ratio 2.8; 95% confidence interval 1.1-7.2), but mainly because of higher serum creatinine levels at presentation. CONCLUSION: The incidence of malignant hypertension and related renal complications is higher in black compared with white individuals. These differences may be explained by ethnic disparities in blood pressure control, drug adherence and insurance status.