Reconstruction for Renal Artery Aneurysm and its Effect on Hypertension

AbstractObjectives: many renal artery aneurysms (RAA) are diagnosed incidentally in the course of investigations for hypertension and their management is controversial. Aim: to review the results of renal artery reconstruction for RAA. Methods: between January 1978 and December 1998 111 RAR were performed in 81 kidneys in 71 patients. Results: fifty-nine patients were hypertensive, three had a creatinine >2.0 mg/dl and one was on dialysis. The principal underlying pathology was fibromuscular dysplasia (39) and atherosclerosis (17). The mean RAA diameter was 2.2 (range 1–15) cm overall and 3.5 (range 2–10) cm in four patients who presented with rupture. Fifty-one patients had renal artery stenosis. Autogenous material was used in 105 RAR. There was no 30-day mortality and the morbidity rate was 16%. The 5-year cumulative patency rate was 69%. Hypertension was cured in 25% and improved in 39%.Conclusions: RAR tested for RAA treats hypertension and reduces the risk of rupture and distal embolisation

The influence of anesthetics, neurotransmitters and antibiotics on the relaxation processes in lipid membranes

In the proximity of melting transitions of artificial and biological membranes fluctuations in enthalpy, area, volume and concentration are enhanced. This results in domain formation, changes of the elastic constants, changes in permeability and slowing down of relaxation processes. In this study we used pressure perturbation calorimetry to investigate the relaxation time scale after a jump into the melting transition regime of artificial lipid membranes. This time corresponds to the characteristic rate of domain growth. The studies were performed on single-component large unilamellar and multilamellar vesicle systems with and without the addition of small molecules such as general anesthetics, neurotransmitters and antibiotics. These drugs interact with membranes and affect melting points and profiles. In all systems we found that heat capacity and relaxation times are related to each other in a simple manner. The maximum relaxation time depends on the cooperativity of the heat capacity profile and decreases with a broadening of the transition. For this reason the influence of a drug on the time scale of domain formation processes can be understood on the basis of their influence on the heat capacity profile. This allows estimations of the time scale of domain formation processes in biological membranes.Comment: 12 pages, 6 figure

Phase transitions in biological membranes

Native membranes of biological cells display melting transitions of their lipids at a temperature of 10-20 degrees below body temperature. Such transitions can be observed in various bacterial cells, in nerves, in cancer cells, but also in lung surfactant. It seems as if the presence of transitions slightly below physiological temperature is a generic property of most cells. They are important because they influence many physical properties of the membranes. At the transition temperature, membranes display a larger permeability that is accompanied by ion-channel-like phenomena even in the complete absence of proteins. Membranes are softer, which implies that phenomena such as endocytosis and exocytosis are facilitated. Mechanical signal propagation phenomena related to nerve pulses are strongly enhanced. The position of transitions can be affected by changes in temperature, pressure, pH and salt concentration or by the presence of anesthetics. Thus, even at physiological temperature, these transitions are of relevance. There position and thereby the physical properties of the membrane can be controlled by changes in the intensive thermodynamic variables. Here, we review some of the experimental findings and the thermodynamics that describes the control of the membrane function.Comment: 23 pages, 15 figure