instruction:
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.
question:
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.
answer:
Albumins

question:
Abstract: Fistula or deep sinus formation as a complication of xanthogranulomatous pyelonephritis (XPN) has not been described previously in the British literature. We present the clinicopathological features of one case of a nephrodiaphragmatic sinus complicating XPN, and three cases of nephrocolic fistula, including the first recorded case of fistula in childhood XPN. The detailed clinical, radiological and pathological features of XPN and its complications are reviewed. Total nephrectomy, together with primary excision of sinuses or fistulae, is the treatment of choice.
answer:
Adult

question:
Abstract: Male Sprague-Dawley rats were maintained on high protein (60%), normal protein (20%), low protein (5%), or no protein (0%) diets for two or four weeks prior to 45 minutes of renal ischemia induced by renal pedicle clamping. Most (93%) of the rats on the high protein diet died within three days following renal ischemia. In addition, 69% of the rats on normal protein diets also died, most before the fourth day following ischemic insult. In contrast, 88% of the rats on the low protein diet lived, although some exhibited elevated serum creatinine levels for up to one to two weeks following ischemia. Finally, all of the rats on no protein diets lived, and most (75%) exhibited normal serum creatinine levels by the fourth day following ischemia. Shifting the diets of high protein and normal protein adapted rats to no protein diets immediately following ischemia did not improve postischemic survival. Also, changing the diets of no protein adapted rats to high protein diets immediately following ischemia did not significantly affect postischemic recovery. When rats were maintained on no protein diets for shorter periods of time prior to ischemia, it was found that approximately a week on this diet is necessary to provide maximum protection from postischemic acute renal failure. These findings demonstrate a dramatic effect of dietary protein prior to ischemic induced acute renal failure, and suggests that preoperative dietary protein intake should be an important consideration in those situations which are predisposed to postoperative acute renal failure.
answer:
Animal