Acquired free protein S deficiency in children with steroid resistant nephrosis

Plasma and urine concentrations of protein S were measured in five children with steroid-resistant nephrotic syndrome. It was found that plasma free protein S was reduced in three out of the five patients studied. Thus, acquired free protein S deficiency does occur in children with nephrotic syndrome and is one of many factors which may place them at risk for a thromboembolic event.

Tissue differences in antioxidant enzyme gene expression in response to endotoxin

The effect of endotoxin on antioxidant gene expression and antioxidant enzyme activity in homogenates of the heart, liver, and kidney from Sprague-Dawley rats was compared by quantitation of m-RNA and enzyme activities. Alterations in the message level for Cu-Zn superoxide dismutase (SOD), Mn SOD, and catalase varied with the tissue type, length of exposure to endotoxin, and dose of endotoxin. In general, endotoxin treatment reduced Cu-Zn SOD expression in the heart and liver, but had no noticeable effect in the kidney. Mn SOD message levels were increased in the heart and kidney but decreased in the liver. Catalase expression was reduced in the kidney and increased marginally in the heart and liver. With regard to enzyme activity, endotoxin treatment reduced Cu-Zn SOD activity in the heart, liver, and kidney. Mn SOD activity showed little change in the heart, but increased in the liver and, to a lesser extent, in the kidney. Catalase activity showed little change in the heart and kidney but was decreased at 12 h in the liver. The differing responses of tissues to the oxidant stress of endotoxin exposure should be considered when evaluating the effect of endotoxin on antioxidant enzymes.

Effect of rifampin on Staphylococcus aureus colonization in children on chronic peritoneal dialysis

The efficacy of rifampin in eliminating Staphylococcus aureus colonization was evaluated in a pediatric peritoneal dialysis population. Six children with documented nasal colonization were treated for 7 days with rifampin and cloxacillin. Although antimicrobial therapy eliminated nasal carriage in all patients, recolonization occurred in 66%. Exit site colonization proved difficult to eradicate with negative cultures documented in only 3 of 5 children after rifampin/cloxacillin therapy. Although S. aureus carriage is a risk factor for S. aureus infections, efforts to eradicate carriage with rifampin are hindered by rapid recolonization.

Impairment of peroxisomal beta-oxidation system by endotoxin treatment

It is now clear that peroxisomes play a crucial role in many cellular processes, including the beta-oxidation of very long chain fatty acids. Recently, mammalian peroxisomes have been shown to contain the antioxidant enzymes, superoxide dismutase and glutathione peroxidase, in addition to catalase. The presence of these enzymes in peroxisomes suggests that peroxisomes undergo oxidative stress in normal and disease states. As an indicator of the potential impact of an oxidative stress on peroxisomal functions, we evaluated the effect of endotoxin exposure on the beta-oxidation enzyme system in rat liver. Peroxisomes were isolated from liver homogenates by differential and density gradient centrifugations. Endotoxin treatment decreased the beta-oxidation of lignoceric acid to 56% of control values (p < 0.01). The specific activity of the rate limiting enzyme in the system, acyl-CoA oxidase, was decreased to 73% of control values (p < 0.05). Immunoblot analysis revealed a 25% decrease in the 21KD subunit of the acyl-CoA oxidase protein. In contrast, the protein levels of the other enzymes in the pathway, trifunctional protein and 3-ketoacyl-CoA thiolase, were increased by 10 and 15%, respectively. These findings suggest that impairment of beta-oxidation of lignoceric acid by endotoxin treatment is due primarily to a reduction in the activity and protein level of the key enzyme, acyl-CoA oxidase. Oxidative stresses such as endotoxin exposure may have deleterious effects on important peroxisomal functions, such as beta-oxidation of very long chain fatty acids.

Tumor necrosis factor alpha modulates parathyroid hormone action in UMR-106-01 osteoblastic cells

Tumor necrosis factor (TNF-alpha) has been shown to play an important role in local control of bone remodeling. The interaction of TNF-alpha and PTH was evaluated in UMR-106-01 cells, a phenotypic osteoblastic osteosarcoma cell line. We examined the influence of TNF-alpha on the two signal transduction systems triggered by PTH in UMR-106-01 cells, adenylate cyclase and free cytosolic calcium ([Ca2+]i). cAMP generation was inhibited in TNF-alpha-pretreated cells by 69, 61, 34, and 21% at PTH concentrations of 0.1, 1, 10, and 100 nM, respectively. Inhibition was seen at TNF-alpha doses of 100-1500 units/ml after a minimum incubation time of 12 h. TNF-alpha inhibition of the PTH-stimulated increase in [Ca2+]i was even more pronounced: treated cells showed no change in baseline [Ca2+]i after stimulation with 40 nM PTH. Treatment with TNF-alpha was also found to inhibit both arms of the PTH response in the nontransformed osteoblastic cell line, MC3T3-E1. TNF-alpha treatment did not alter cAMP generation in response to PGE2. TNF-alpha inhibition of the PTH-stimulated cAMP response was reversed completely by addition of cholera toxin (5 micrograms/ml) and partially by forskolin (10 microM) but not pertussis toxin (100 and 500 ng/ml). Scatchard analysis using PTHrP revealed that TNF-alpha treatment reduced the number of receptors but had no effect on KD. These findings suggest that TNF-alpha inhibits the osteoblastic response to PTH at least in part because of a reduction in receptor number. Further investigation is indicated to provide insight into the interaction of calciotropic hormones and cytokines in vivo.

Peroxisomal participation in the cellular response to the oxidative stress of endotoxin

Exposure to a sublethal dose of endotoxin offers protection against subsequent oxidative stresses. The cellular mechanisms involved in generating this effect are not well understood. We evaluated the effect of endotoxin on antioxidant enzymes in liver peroxisomes. Peroxisomes have recently been shown to contain superoxide dismutase (SOD) and glutathione peroxidase (GPX) in addition to catalase. Peroxisomes were isolated from liver homogenates by differential and density gradient centrifugations. Endotoxin treatment increased the specific activity of SOD and GPX in peroxisomes to 208% and 175% of control activity, respectively. These findings correlated with increases in peroxisomal SOD and GPX proteins observed by immunoblot. Although the quantity of catalase protein was increased when assessed by immunoblot analysis, the specific activity of catalase was decreased to 68% of control activity. Activation of catalase with ethanol only restored catalase activity to control levels suggesting that catalase had undergone irreversible inactivation. The observed increase in GPX activity may represent a compensatory mechanism triggered by accumulating H2O2. The data presented here suggest for the first time that mammalian peroxisomal antioxidant enzymes are altered during the oxidative injury of endotoxin treatment.

Acute peritoneal dialysis utilizing a non-luminal channeled catheter in infants

Acute peritoneal dialysis in unstable infants is at times plagued by early catheter malfunction secondary to omental plugging in both rigid acute catheters and conventional Tenckhoff catheters. This problem is inherent to the design of catheters using sideports for outflow and is enhanced by the tenacity of the omentum in this population in walling off foreign bodies. We have modified and utilized a non-luminal, channeled surgical drain for acute peritoneal dialysis in infants to avoid this problem. Five infants ranging in age from 2 days to 7 months were dialyzed acutely in a Pediatric Intensive Care Unit setting for periods ranging from 5 to 34 days utilizing this modified catheter. The infants ranged in weights from 1.96 to 8 Kg. Catheters were placed by a surgeon and peritoneal dialysis was initiated using a Y-setup. In none of the patients was there loss of catheter function secondary to omental plugging. Three patients subsequently died of their underlying illness and two recovered renal function. Two acute catheters were subsequently changed to conventional Tenckhoff catheters when it became apparent that dialysis would need to be performed for a prolonged time. The acute catheter which was used has a four channel cloverleaf appearance when cut in cross section with no central lumen. There is a transition to a luminal catheter outside the peritoneal cavity. The advantage of the cloverleaf configuration is the ability to exchange fluid along its entire intraperitoneal length, thereby excluding a defined area of catheter sideports where omentum can occlude the system causing a ball valve phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)

Vesicoureteral reflux and urinary tract infections in renal transplant recipients

Fifty-six children who received kidney transplants were evaluated for postoperative vesicoureteral reflux and frequency of urinary tract infection. Two methods of ureteral implantation were compared: a nonantireflux extravesicular ureteroneocystostomy and an antireflux intravesicular ureteroneocystostomy. Reflux was found in 79% of children who had the nonantireflux procedure vs 19% of children who had the antireflux procedure. This disparity was present regardless of sex and age. Infections occurred at a rate of one per 11 patient-months after the nonantireflux procedure vs one per 40 patient-months after the antireflux procedure. Regardless of surgical technique, the incidence of infection was higher in children with reflux. The potentially harmful effect of infection with reflux warrants concern. Because of the need to maximize allograft function for a longer time period, an antireflux procedure is recommended in all pediatric kidney transplants.