Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

[Q]: Abstract: Following nephrectomy and acute potassium loading, animals previously maintained on a high potassium diet have a smaller increment in plasma potassium than do animals on a control diet. The mechanism of this "extrarenal potassium adaptation" is not known. To explore the role of potassium depletion in this process, we studied rats adapted to either a high potassium (HK) or control (C) diet. When dietary potassium was withdrawn, urinary potassium losses in HK rats greatly exceeded those in C rats for at least two days, leading to greater potassium depletion in HK than C animals. A smaller increment in plasma potassium in HK compared to C rats was seen only after prolonged fasting preceded nephrectomy and acute potassium loading. Correction of potassium depletion incurred during fasting abolished extrarenal potassium adaptation. We conclude: after withdrawal of dietary potassium, urinary potassium losses are much greater in HK than in C rats; if the duration of dietary potassium deprivation is sufficient, these urinary potassium losses will cause potassium-adapted animals to paradoxically become more potassium depleted than controls; and this paradoxical potassium depletion may be responsible for extrarenal potassium adaptation.
[A]: Adaptation, Physiological

[Q]: Abstract: Human IgG4 antibodies directed against phospholipase A, the P1 antigen from Dermatophagoides pteronyssinus extracts, and cat albumin were found unable to cross-link antigen. Previously, it was demonstrated that IgG4 antibodies, in contrast to IgG1 antibodies, did not cross-link Sepharose-bound antigen and antigen added in solution. To eliminate the possibility that this phenomenon was caused by preferential binding of both IgG4 Fab fragments to the solid-phase-bound antigen, cross-linking of antigen was studied in a fluid-phase system. In this test, incapability of IgG4 antibodies to bridge two antigens was also found. As a result of such a phenomenon, it is expected that immune complexes formed by IgG4 antibodies will be considerably smaller than complexes formed by IgG1. This was confirmed by analysis of the molecular size profiles of IgG1- and IgG4-containing immune complexes in sucrose-density gradients. Moreover, IgG1 was able to precipitate antigen in a radioimmunoprecipitation test, whereas precipitation was not demonstrable by the same amount of IgG4 antibodies. Even 3% polyethylene glycol 8,000 did not precipitate the small IgG4-containing immune complexes efficiently. The antibodies studied were of a high-affinity type, and there was no significant difference in association constants between IgG1 and IgG4 antibodies. Therefore, we were not able to confirm observations reported in the literature that the IgG4 subclass is associated with a low-affinity antibody response; probably, the affinity of the IgG4 antibodies was underestimated by other investigators because of the polyethylene glycol precipitation technique used to separate antibody-bound and free antigen. Our findings stress the point that IgG4 antibodies take a special place in the immune response upon chronic exposure to antigen.
[A]: Albumins

[Q]: Abstract: This paper reports the Authors' 8 year experience in the clinical use of charcoal hemoperfusion as a means to reduce the weekly time of treatment in chronic uremic patients. Two different programmes were applied. Programme A (34 patients) which involved substituting the 3 procedures per week of standard dialysis (4 hours duration each) by 2 procedures of combined hemodialysis and hemoperfusion, again of 4 hours duration each. Programme B (18 patients) which involved substituting the 3 procedures per week of 4 hours duration by 3 procedures of 3 hours each, 2 of combined hemodialysis and hemoperfusion, 1 of conventional dialysis. The net weekly reduction was 33% for Programme A and 25% for Programme B. The efficacy of the two Programmes was evaluated by clinical, hematochemical, nutritional and instrumental parameters.
[A]:
Adult