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D G Oreopoulos

Publications and source records attributed to D G Oreopoulos.

At least 91 records · Page 5Linked to original sources
PubMed1996

Effect of vitamin E on peroxidation and permeability of the peritoneum.

Because of the evidence that peritoneal macrophages are activated during peritoneal dialysis, we hypothesised that the injury of the peritoneum is, at least in part, dependent on the intraperitoneal generation of free radicals. The aim of the study was to evaluate the effect of vitamin E on the peroxidation and permeability of the peritoneum during chronic peritoneal dialysis in rats. Supplementation of the intraperitoneally infused saline with vitamin E decreased the peroxidation of peritoneum estimated as the malondialdehyde (MDA) level in rats' omentum. However the permeability of the peritoneum to glucose and protein in vitamin E treated rats was increased. In in vitro study we have found that vitamin E is cytotoxic to human mesothelial cells (HMC) as measured by inhibition of their proliferation and this effect was irreversible. We conclude that vitamin E, despite its antioxidant effect, causes the changes of the peritoneum permeability which could decrease the effectiveness of peritoneal dialysis.

Animals↗
PubMed1995

Changes in biocompatibility of dialysis fluid during its dwell in the peritoneal cavity.

OBJECTIVE: To evaluate the changes in biocompatibility of peritoneal dialysis solutions during intraperitoneal dwell. DESIGN: We studied the effect of the drained dialysates at time 0 and after 30, 60, 120, 240, and 360 minutes of intraperitoneal dwell on the growth of peritoneal mesothelial cells and fibroblasts and the synthesis of proteins by these cells. On one day the patients were dialyzed with glucose-based Dianeal and on alternate days with an amino acid-containing solution based on Travasol. PATIENTS: Dialysates were collected from 4 patients during continuous ambulatory peritoneal dialysis (CAPD) training. RESULTS: Unused dialysis solutions containing glucose or amino acids inhibit growth of mesothelial cells and fibroblasts. Dialysates obtained after 30 or 60 minutes of intraperitoneal dwell support the growth of these cells in a way similar to 10% fetal calf serum, but dialysates drained after a longer dwell of 120-360 minutes had a stronger effect on growth of these cells than did serum. All glucose-based dialysates stimulate the synthesis of collagen in mesothelial cells, whereas they reduce the synthesis of non-collagen proteins. All glucose-based dialysates reduce the synthesis of collagen and non-collagen proteins in fibroblasts compared with the production of these proteins in the presence of serum. CONCLUSION: Changes in the properties of the dialysis solutions during their intraperitoneal dwells do not seem to increase their biocompatibility. Indeed, excessive mitogenic effect and the stimulation of collagen synthesis of the dialysates may induce pathological changes in the peritoneum.

Biocompatible Materials↗
PubMed1995

Functional properties of mesothelial cells after prolonged exposure to dialysate effluent.

The authors tested in vitro the effect of glucose-based and amino acid-based dialysate effluent on the function of human peritoneal mesothelial cells. After 9 days of exposure to the tested effluents with medium (1:1 v/v) or to a medium supplemented with 10% fetal calf serum (FCS) (control), several functional properties of the cells were studied. The synthesis of DNA measured by incorporation of 3H-methyl-thymidine was higher in mesothelial-cell monolayers exposed to the dialysates than in the controls. Synthesis of hyaluronic acid was similar in all three groups, but after stimulation with Il-1 the cells exposed to the dialysates produced more hyaluronic acid. Synthesis of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) was higher in the control cells. However, after stimulation with IL-1, the cells exposed to the dialysate showed greater synthesis of PAI-1 than of t-PA. Also, procoagulant activity of the control cells was higher than that of the cells exposed to the dialysates. We have concluded that the functional properties of the mesothelial cells may be altered in vitro during prolonged exposure to the dialysate, something that may also occur in vivo.

Amino Acids↗
PubMed1995

Hypotension in CAPD: role of volume and sodium depletion.

The prevalence of hypotension in continuous ambulatory peritoneal dialysis (CAPD) patients varies between 10% and 16%. The main causes of hypotension in these patients include hypovolemia, antihypertensive medications, myocardial failure, and a variety of poorly understood causes, viz, severe autonomic neuropathy, amyloidosis, malignancies, adrenal insufficiency, removal of vasopressor substances by dialysis and steroid withdrawal. In addition, there are a large number of patients with hypotension due to unknown causes. Between 1989 and 1994 we had 65 of 525 CAPD patients suffering from persistent hypotension. Sixteen (25%) patients were hypovolemic, 14 improved after increasing the target weight, but 2 did not because of concurrent administration of coronary vasodilators. The various steps in the treatment of this group include fluid repletion after discontinuing anti-hypertensive medications and excluding myocardial failure, oral sodium supplementation and possibly increasing the dialysate sodium. Preventive measures include frequent assessment of the hydration status. Judicious use of diuretics is also important. Bioelectrical impedance and inferior vena caval ultrasound are two promising tools to assess the fluid status and supplement careful clinical examination.

Blood Volume↗
PubMed1995

Discrepancy between weekly KT/V and weekly creatinine clearance in patients on CAPD.

Currently, weekly KT/V and weekly creatinine clearance (WCC) are used to quantitate continuous ambulatory peritoneal dialysis (CAPD), the minimum recommended requirements being 1.7/week and 50 L/week, respectively. There is no substantial evidence that one index is better than the other, and there is no clear recommendation what one should do if there is a discrepancy between these two values. We performed a cross sectional analysis of 68 patients in whom we measured weekly KT/V, WCC, residual clearances, and a 4-hr peritoneal equilibration test (PET). The correlation between KT/V and WCC in the whole group was highly significant (p < 0.0001); when patients were divided in the four PET groups, there was a significant correlation (p < 0.05) in the low-average (n = 22) and high-average (n = 21) PET groups, but the correlation was not significant in the high (n = 13) and low (n = 12) PET groups. Fourteen of 68 patients (20%) showed a discrepancy between KT/V and WCC: 7 patients had a KT/V < 1.7 and WCC > or = 50 (group 1), and 7 patients had a KT/V > or = 1.7 and WCC < 50 (group 2). Those in group 1 with a WCC > 50 had a higher residual renal function (0.82 vs 0.11 mL/min, p < 0.05) than those in group 2 and therefore had a higher tubular secretion of creatinine and reabsorption of urea. Those in group 2 with a KT/V > 1.7 had lower creatinine equilibration than those in group 1 (D/Pcr 0.56 vs 0.75, p < 0.05) and therefore a better removal of urea than creatinine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effect of phosphatidylcholine on lymphatic drainage and fluid loss from the peritoneal cavity of sheep.

The purpose of this investigation was to test the hypothesis that phosphatidylcholine enhances net ultrafiltration by decreasing lymphatic drainage of the peritoneal cavity. Twelve sheep were used in this study. Six animals received 50 ml/kg intraperitoneal infusions of Dianeal 4.25% (490 mOsm/liter) and six received similar volumes of premixed phosphatidylcholine-Dianeal (510 mOsm/liter). Labeled albumin (25 microCi 125I-human serum albumin) was added to the dialysate as a lymph flow marker. Lymph drainage of the peritoneal cavity was estimated from the appearance of the intraperitoneally administered tracer in the blood. Net ultrafiltration was significantly enhanced by phosphatidylcholine at each hour up to 6 hours post-infusion, and over this period reached 30.3 +/- 3.8 ml/kg in the phosphatidylcholine animals compared to 12.2 +/- 2.1 ml/kg in the control group. Phosphatidylcholine treatment decreased the volume removed by lymphatics; by six hours 5.5 +/- 1.1 ml/kg in the animals receiving phosphatidylcholine, and 10.3 +/- 1.0 ml/kg in the control group was drained as lymph. Fluid loss (estimated from the tracer disappearance from the peritoneal cavity) was slightly less in the phosphatidylcholine-treated animals, averaging 15.8 +/- 1.6 in this group versus 16.8 +/- 1.7 ml/kg in the control sheep. However, these differences were not significant. Phosphatidylcholine significantly increased transcapillary ultrafiltration (estimate of volume movement into peritoneal cavity without fluid loss) from 27.6 +/- 1.5 ml/kg in the controls to 43.8 +/- 3.4 ml/kg in the animals receiving phosphatidylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Glycosaminoglycan chondroitin sulphate prevents loss of ultrafiltration during peritoneal dialysis in rats.

We evaluated the effect of 6 days of intraperitoneal saline infusion on peritoneal peroxidation and permeability in rats. Peroxidation of the peritoneum as measured by malondialdehyde concentration in the omentum was increased and there was a concomitant augmented membrane permeability to glucose and resulted in a loss of ultrafiltration. In vitro experiments with mesothelial cells showed that glycosaminoglycan chondroitin sulphate appears to act as a scavenger of free radicals and so protects the mesothelial cells against injury. Thus, in rats, supplementation of the infused saline with chondroitin sulphate reduces peroxidation of the peritoneum and prevents loss of ultrafiltration during peritoneal dialysis. These results suggest that chondroitin sulphate may be effective in preventing the deterioration of peritoneal permeability during chronic peritoneal dialysis. This beneficial effect probably derives from the scavenging of free radicals by chondroitin sulphate.

Animals↗
PubMed1994

Anabolic steroids in the treatment of malnourished CAPD patients: a retrospective study.

OBJECTIVE: To assess the effect of anabolic steroids on malnutrition of continuous ambulatory peritoneal dialysis (CAPD) patients. DESIGN: Retrospective analysis of medical records, charts, and computer-generated laboratory and medication data. SETTING: Peritoneal Dialysis Unit of The Toronto Hospital. PATIENTS: Thirteen patients with moderate to severe malnutrition who had received nandrolone decanoate (ND) intramuscularly (IM) for at least three months. Nine of these patients (group A), with a mean age of 59.4 years, received only ND (100-200 mg IM monthly). Group B consisted of 4 patients (mean age 74.0 years) who, in addition to ND, received intraperitoneal (IP) amino acids. RESULTS: In group A, serum albumin, while declining before ND treatment (34.4 +/- 3.2 to 31.5 +/- 3.35, x +/- SEM, g/L at -2 and 0 months), showed a progressive and significant (p < 0.001) increase during treatment, sustained up to the third month (36.57 +/- 1.51). In group B, serum albumin did not increase significantly (30.25 +/- 2.62, 30.75 +/- 1.9, and 31.5 +/- 4.8, mean +/- SEM, g/L at -2, 0, and +3 months, respectively. In group A, serum creatinine was increased significantly (p < 0.01) from 0 to +3 months (731 +/- 185 to 938 +/- 92.5 mmol/L). Blood urea, bicarbonate, and total protein levels did not change significantly. In group B, serum creatinine fluctuated considerably with an insignificant trend to rise. Blood urea showed a steady trend to increase without reaching statistical significance. In relation to time 0, bicarbonate levels (28.7 +/- 3.3) were decreased significantly (p < 0.05) (27 +/- 0.8, 24.6 +/- 1.5, and 25 +/- 1 mEq/L, at +1, +2, and +3 months, respectively). CONCLUSIONS: Nandrolone decanoate alone, in relatively low doses, exerted a definite anabolic effect in 9 malnourished CAPD patients. The lack of a similar effect in 4 patients, who in addition to ND received amino acids IP, could be explained by the low dose of ND, the concurrent acidosis, the severity of malnutrition, and the older age of this group.

Adult↗