The kidney is probably the major site of production of the plasma enzyme glutathione peroxidase (GSHPx-P). For this study, GSHPx-P activity was determined in 40 healthy people, in 34 patients with differing degrees of renal impairment, and in hemodialysis patients from whom blood samples were withdrawn either before or after each session (18 patients) or throughout the dialysis session (27 patients). Hemodialysis patients were treated by means of different techniques (bicarbonate hemodialysis, hemodiafiltration, and acetate free biofiltration), and different membranes (cuprophane, polyacrylonitrite, and polymethylmethacrylate). The following results were obtained: 1) GSHPx-P activity was significantly decreased in renal impairment patients; 2) GSHPx-P activity negatively correlated with serum creatinine values in renal impairment patients (r = -0.55; p < 0.001); and 3) the enzyme activity slightly increased after the session in hemodialysis patients. The following conclusions can be drawn: GSHPx-P activity could be new index of renal function, because it was decreased in patients with renal failure; the decrease in GSHPx-P activity paralleled the severity of renal impairment, and was maximal in hemodialysis patients; GSHPx-P activity was slightly raised at the end of the hemodialysis session, concomitant with other enzyme activities (aspartate transaminase, alanine transaminase, and alkaline phosphatase) and total protein concentration. This seems to be attributable to the process of water loss rather than other hypothetical mechanisms, such as A) enzyme activation by either peroxide generation during blood-membrane contact, or by the removal of a hypothetical inhibitor; and B) de novo synthesis in the residual renal mass or in other sites of production.

Body Water↗

PubMedDate not supplied

Effect of aging on the body composition of dialyzed subjects. Comparison with normal subjects.

A bioimpedance analyzer (BIA-CHIP; Akern RJL System) was applied to 366 normal subjects (171 men and 195 women). Each gender group was divided into eight groups, according to age: 20-29 years; 30-39 years; 40-49 years; 50-59 years; 60-69 years; 70-79 years; 80-89 years; and 90-95 years. The same was done with 44 hemodialysis patients (22 men, 22 women), each being evaluated 15 times over a period of 5 years: these were divided into seven groups (seven, because no patient was older than 89) using the same criteria. For each subject, 23 parameters were determined: 5 directly measured (height, weight, resistance, reactance, phase angle) and the others (fat and lean mass, body water, body cell mass, extra and intracellular water, etc.) from appropriate equations. Twenty-four thousand data points were collected and served to form a data bank. Men and women on hemodialysis showed different effects of aging: women normalized their BC at an age > 70 years, whereas men continued to have a muscle mass lower than that of normal subjects until the age of 80. A computerized program (Nutritio) permits fast and reliable evaluation of the nutritional status of hemodialysis patients, each subject being compared with both the similarly aged population (dialyzed or not) or with his or her own data, obtained over time.

Adult↗

PubMedDate not supplied

Free radicals and oxidative stress challenge dialysis patients: effects of two different membranes.

Patients with end-stage renal disease (ESRD) who undergo hemodialysis manifest pronounced oxidative stress (OS), for the antioxidant system is inadequate to correct the imbalance between generation and scavenging of reactive oxygen species (ROS). To clarify the role of two different membranes on the OS, we measured plasma lipid peroxidation (LPO) and erythrocyte concentration of several antioxidant enzymes on 20 controls and 6 patients on bicarbonate dialysis (BHD). At 7 days intervals, 2 BHD sessions were done on the same 6 hemodialysis patients: the two BHD sessions were similar, except for the membrane used (cuprophan, first study; regenerated cellulose = Bioflux, second study, 7 days later). Before, during, and after each session (0', 30', 60', 120', end, 30' after BHD end), several blood samples were drawn. Lipid peroxidation and erythrocyte glutathione (GSH), superoxide dismutase (SOD), and catalase were spectrophotometrically determined (Bioxytech, France), but for erythrocyte glutathione peroxidase (Gpx) and G-6-PD, Gunzler's and Beutler's methods were used, respectively. Both membranes induce a significant decrease in LPO (p < 0.01) and an increase in erythrocyte SOD (p < 0.05). Bioflux shows some peculiar effects: a significant increase in erythrocyte GSH (p < 0.05) and erythrocyte catalase (p < 0.01) with a gradual increase of erythrocyte SOD and catalase/SOD ratio. Cuprophan, on the contrary, causes a sudden increase in erythrocyte SOD, while erythrocyte catalase decreases. These data support the view that Bioflux induces an OS lower than cuprophan because with the former, increased H2O2 production leads (thanks to catalase and GPx action) to water generation. With cuprophan, instead the reduced SOD/catalase ratio causes a greater H2O2 generation and a lower conversion to water.

Adult↗