Increased urine interleukin-1 levels in aging

Our laboratory previously noted an increase in thymocyte mitogenic activity in the urine of many elderly patients. The present study was performed to verify this finding and to determine if this activity was actually due to an increase in interleukin-1 (IL-1). IL-1 levels were measured in the urine of 33 healthy, ambulatory, elderly subjects (ages 83-95 years), using both a murine thymocyte bioassay, measuring activation by the incorporation of tritiated thymidine and an MTT dye reduction assay. There was a significant increase in urine IL-1 in 85% of elderly individuals. In the MTT dye reduction assay, mean elderly urine IL-1 levels were 0.88 U/ml, in comparison with a young control group (ages 23-37 years) in which urine IL-1 levels were very low (mean IL-1 < or = 0.05 U/ml). Urine levels of IL-1 beta were also measured by using a sensitive immunoassay (ELISA) and were found to be significantly increased in the elderly (mean = 57.4 pg/ml), compared to the young (mean = 2.5 pg/ml). In contrast, IL-2 levels in urine were very low, with no difference between the young and the elderly. Mean urine protein and creatinine levels did not differ significantly between young and old, and did not account for the increase in urine IL-1 levels. Although its immunologic significance is not yet understood, this striking increase in IL-1 is an unusual and interesting finding that merits further investigation.

Effects of low copper intake on dimethylhydrazine-induced colon cancer in rats

Rats fed low copper show a high incidence of dimethylhydrazine (DMH)-induced colon tumors compared with rats fed very high Cu. The difference could be due to Cu deficiency in the low group or to Cu toxicity in the high group. In the present study, rats fed low Cu (0.2 ppm) showed greater DMH-stimulated colon tumorigenesis than rats fed adequate Cu (8 ppm). Differences were seen in the number of rats developing tumors (5 of 11 vs 1 of 10), total tumors (7 vs 2), and average tumor mass (1.02 g vs 0.29 g). Low Cu intake did not cause any general DMH toxicity as assessed by body weight gain. To prevent Cu deficiency-induced mortality, low Cu feeding was begun in postweanling rats (weight, about 80 g) housed in groups of five to six, rather than individually. This limited the effects of low Cu feeding to only a moderate Cu deficiency based on several parameters, including three Cu antioxidant enzyme activities. Group-housed rats fed marginal Cu levels (2.5 ppm) showed normal Cu status, and DMH produced only one tumor in 10 rats. In conclusion, high DMH-induced colon tumorigenesis can be found in rats with low activities of Cu antioxidant enzymes.

Electrocardiographic activity and cardiac function in copper-restricted rats

The temporal sequence of events leading to cardiac dysfunction during copper restriction in the Long-Evans rat was studied over a 6-week period. Weanling rats were fed either copper-adequate (6 mg Cu/kg diet, n = 25) or copper-restricted (less than 1 mg Cu/kg diet, n = 25) diets for varying periods of time for up to 6 weeks. Beginning at 2 weeks after weaning and weekly thereafter, five rats from each diet were evaluated for cardiac function, and sacrificed, and indicators of copper deficiency were determined on several tissues. Electrocardiograms began showing indications of cardiac disease at Week 3 in the copper-restricted rats, at which time cardiac hypertrophy and other signs of copper deficiency were apparent. Greater QT intervals and QRS amplitudes were observed in copper-restricted rats at various weeks. Peak + and - dP/dt maxs did not differ by diet copper treatment for any of the time intervals studied, nor was any notable difference in developed left ventricular pressure apparent. Hematocrit and liver copper levels were decreased in copper-restricted rat hearts at all weeks. These results suggest that the onset of cardiac dysfunction in copper deficiency is rapid, with both dysfunction and hypertrophy apparent within 3 weeks after copper restriction and when liver copper levels have declined.

Copper deficiency in a genetically hypertensive cardiomyopathic rat: electrocardiogram, functional and ultrastructural aspects

The effect of copper deficiency on cardiac function and structure was studied in a strain of rats (SHHS/Mcc-cp) known to develop cardiac failure as adults. Restriction of dietary copper (less than or equal to 1 mg/kg vs. 6 mg/kg in adequate diets) at weaning in both sexes for a 6-wk period produced cardiac hypertrophy. Male rats developed more severe copper-deficiency symptoms than their female counterparts. In both sexes of copper-deficient rats, there was an increase in cardiac length, width, free ventricular wall thickness and septum thickness. Electrocardiographic tracings revealed greater QRS height among male copper-deficient rats. Heart rate also was substantially reduced in this group. The increased volume of myocardium occupied by mitochondria in the copper-deficient male rats might result in increased electrical resistance that would increase the QRS height; hypertrophy or anemia also could be contributory. Some male copper-deficient rats had prolongation of the QRS in a bundle branch block pattern. Maximal rates of rise and fall for left ventricular pressure were reduced in male copper-deficient rats. The gross histology indicated that this type of heart failure was more concentric than eccentric. The copper-deficient male rat may serve as a useful model for studying the concentric cardiac hypertrophy that occurs in humans.

Characterization of a human interleukin 1 inhibitor

Human urine contains a specific inhibitor of interleukin 1 (IL 1) that is found in increased amounts during fever. This inhibitor was purified by using a sequence of ammonium sulfate fractionation, DEAE cellulose ion-exchange chromatography, molecular sieve chromatography on Sephacryl S-200, affinity chromatography on concanavalin A (Con A) Sepharose, and polyacrylamide gel electrophoresis. Two peaks of IL 1 inhibitory material were eluted from the polyacrylamide gels. One peak contained three proteins of 29, 32, and 67 kd, respectively, which could be visualized by silver staining. The second peak contained only a small amount of the 67 kd protein. A partially purified inhibitor fraction was found to cross-react with antisera directed against two low m.w. urine trypsin inhibitors that are cleavage products of the serum inter-alpha-trypsin inhibitor. Although these findings suggest that the urine IL 1 inhibitor may be related to the inter-alpha-trypsin inhibitor, a more exact identification will require either a homogeneous inhibitor preparation or a monospecific antiserum.

Characterization of a human interleukin 1 inhibitor

Human urine contains a specific inhibitor of interleukin 1 (IL 1) that is found in increased amounts during fever. This inhibitor was purified by using a sequence of ammonium sulfate fractionation, DEAE cellulose ion-exchange chromatography, molecular sieve chromatography on Sephacryl S-200, affinity chromatography on concanavalin A (Con A) Sepharose, and polyacrylamide gel electrophoresis. Two peaks of IL 1 inhibitory material were eluted from the polyacrylamide gels. One peak contained three proteins of 29, 32, and 67 kd, respectively, which could be visualized by silver staining. The second peak contained only a small amount of the 67 kd protein. A partially purified inhibitor fraction was found to cross-react with antisera directed against two low m.w. urine trypsin inhibitors that are cleavage products of the serum inter-alpha-trypsin inhibitor. Although these findings suggest that the urine IL 1 inhibitor may be related to the inter-alpha-trypsin inhibitor, a more exact identification will require either a homogeneous inhibitor preparation or a monospecific antiserum.

Identification of a specific interleukin 1 inhibitor in the urine of febrile patients

The urine of febrile patients has been found to contain high concentrations of an inhibitor of interleukin 1 (IL-1)-induced thymocyte proliferation. The inhibitor is specific for IL-1 and does not block the effects of interleukin 2 (IL-2) or phytohemagglutin (PHA) on thymocytes, and it is not nonspecifically toxic for these cells. IL-1 inhibitor can be found in the urine of normal individuals and afebrile patients, but is present in increased concentrations in the urine of patients with fever of diverse etiologies. Preliminary physicochemical characterization indicates that the inhibitor is a 20-40-kdalton protein.