Effect of different lipid apheresis methods on plasma polyunsaturated fatty acids.

Lipoprotein apheresis has been shown to improve the cardiovascular outcome in patients with atherosclerotic disease and therapy-refractory hypercholesterolemia or elevated lipoprotein (a) (Lp(a)). An elevated intake of omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has also been associated with a reduced cardiovascular risk. However, until now only little is known about the effect of apheresis treatment on the levels of omega-6 and omega-3 polyunsaturated fatty acids (n-6 PUFA and n-3 PUFA) in patients. Using gas chromatography (GC) the present study analyzed the content of n-6 and n-3 PUFA as well as saturated fatty acids and monounsaturated fatty acids in the plasma of 20 patients with hyperlipidemia undergoing regular lipoprotein apheresis procedures in direct pre- and post-therapy measurements. Lipoprotein apheresis uniformly reduced the concentrations of arachidonic acid (AA), EPA and DHA fatty acids analyzed in the plasma. However, the three different apheresis methods analyzed (heparin precipitation, membrane filtration and direct absorption) had different effects on the fatty acid profile in the plasma. We found that heparin precipitation and direct absorption apheresis procedures led to a significant decrease of plasma n-3 and n-6 PUFA by 40-50%. In contrast, patients undergoing membrane filtration apheresis, levels pre- and post-apheresis did not change significantly, with AA and EPA being only reduced by approximately 10% while levels of DHA were maintained pre- and post-apheresis. In contrast, total triglyceride levels were lowered most potently by membrane filtration apheresis. In summary, heparin precipitation and direct absorption apheresis approaches significantly lowered polyunsaturated fatty acids in plasma, while membrane filtration did not. This might have implications for cardiovascular and inflammatory risk/benefit profiles associated with n-6 and n-3 PUFA levels in the body.

A lipidomic analysis approach in patients undergoing lipoprotein apheresis.

Lipoprotein apheresis such as heparin-induced extracorporal LowDensityLipoprotein (LDL) Cholesterol precipitation (HELP) reduces apolipoprotein B-containing lipoproteins, most importantly low-density-lipoprotein (LDL), and lipoprotein (a) [Lp(a)]. It is used in patients with atherosclerotic disease and therapy-refractory hypercholesterolemia or progressive atherosclerotic disease in patients with elevated Lp(a). While lipid-lowering effects of lipoprotein apheresis are well-established, there are only sparse data regarding the effect of apheresis on individual omega-6 and omega-3 polyunsaturated fatty acids (n-6 PUFA and n-3 PUFA), such as arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which could increase (AA) or decrease (EPA and DHA) cardiovascular risk. Here we analyzed different omega-6 and omega-3 fatty acids in the blood of patients undergoing a single HELP apheresis procedure using gas chromatography (GC). Furthermore, we assessed the effect of HELP treatment on formation of lipid metabolites and mediators arising from these polyunsaturated fatty acids in the plasma by LC/ESI-MS/MS. Lipoprotein apheresis reduced the concentrations of fatty acids analyzed in the plasma by 40-50%. This was similar for AA, EPA and DHA. The reduction in fatty acid plasma levels was similar to the reduction of total triglycerides. However there was a trend towards an increase of PUFA metabolites associated with platelet activation, such as 12-hydroxyeicosatetraenoic acid (12-HETE) and 14-hydroxydocosahexaenoic acid (14-HDHA). These data indicate that HELP apheresis could interfere with achieving higher levels of n-3 PUFA in the plasma. Lipid apheresis treatment might also increase the formation of potentially pro- as well as anti-inflammatory lipid mediators derived from AA or EPA and DHA.

Internet paradox. A social technology that reduces social involvement and psychological well-being?

The Internet could change the lives of average citizens as much as did the telephone in the early part of the 20th century and television in the 1950s and 1960s. Researchers and social critics are debating whether the Internet is improving or harming participation in community life and social relationships. This research examined the social and psychological impact of the Internet on 169 people in 73 households during their first 1 to 2 years on-line. We used longitudinal data to examine the effects of the Internet on social involvement and psychological well-being. In this sample, the Internet was used extensively for communication. Nonetheless, greater use of the Internet was associated with declines in participants' communication with family members in the household, declines in the size of their social circle, and increases in their depression and loneliness. These findings have implications for research, for public policy and for the design of technology.

A prisoner's dilemma experiment on cooperation with people and human-like computers.

The authors investigated basic properties of social exchange and interaction with technology in an experiment on cooperation with a human-like computer partner or a real human partner. Talking with a computer partner may trigger social identity feelings or commitment norms. Participants played a prisoner's dilemma game with a confederate or a computer partner. Discussion, inducements to make promises, and partner cooperation varied across trials. On Trial 1, after discussion, most participants proposed cooperation. They kept their promises as much with a text-only computer as with a person, but less with a more human-like computer. Cooperation dropped sharply when any partner avoided discussion. The strong impact of discussion fits a social contract explanation of cooperation following discussion. Participants broke their promises to a computer more than to a person, however, indicating that people make heterogeneous commitments.