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Biomedical subjects

D Oreopoulos

Publications and source records attributed to D Oreopoulos.

At least 37 records · Page 2Linked to original sources
PubMed1994

51Cr-RBCs and 125I-albumin as markers to estimate lymph drainage of the peritoneal cavity in sheep.

The purpose of this study was to compare the use of 125I-labeled human serum albumin (125I-HSA) and autologous 51Cr-labeled red blood cells (51Cr-RBCs) as lymph flow markers to estimate lymph drainage of the peritoneal cavity in conscious sheep. In one group, we assessed lymph drainage from the appearance of intraperitoneally administered tracer in the bloodstream. To determine distribution of drainage into discrete lymph compartments, in a second group of studies, lymph was collected from the caudal mediastinal lymph node and the thoracic duct, both of which are involved in lymphatic drainage of the ovine peritoneal cavity. Ringer lactate solution (50 ml/kg) containing 8-10 microCi each of 125I-HSA and 51Cr-RBCs was infused into the peritoneal cavity. Lymph drainage was calculated by dividing the change in mass of tracer in the blood or lymph compartments by the average intraperitoneal tracer concentration. In noncannulated animals, lymph drainage averaged over 6 h was higher with 125I-HSA as tracer (1.35 +/- 0.12 vs. 0.62 +/- 0.19 ml.h-1.kg-1 with 51Cr-RBCs). A similar pattern was noted in terms of drainage into the caudal lymphatic (0.89 +/- 0.23 and 0.52 +/- 0.19 ml.h-1.kg-1 with 125I-HSA and 51Cr-RBCs, respectively) and thoracic duct (0.16 +/- 0.06 and 0.05 +/- 0.02 ml.h-1.kg-1 with 125I-HSA and 51Cr-RBCs, respectively). Analysis of 125I-HSA and 51Cr-RBC concentrations in lymph and intraperitoneal fluid suggested sieving of RBCs at the diaphragmatic stomata or lymph nodes. Using 125I-HSA as tracer and combining data from noncannulated and cannulated sheep, we estimated peritoneal lymph drainage to be 1.35 ml.h-1.kg-1, with 66% of this flow drained by the caudal vessel, 22% by the parasternal pathway (right lymph duct), and 12% by the thoracic duct.

Animals↗
PubMed1994

Lymph flow and lymphatic drainage of inflammatory cells from the peritoneal cavity in a casein-peritonitis model in sheep.

The purpose of this study was to characterize the cellular responses in the peritoneal cavity and draining lymph in a sterile peritonitis model in conscious sheep. Lymph was collected from lymphatics that drained the peritoneal space (caudal mediastinal and thoracic ducts) as well as from lymph vessels that drained peripheral tissues (prescapular). Casein was used as the inflammatory agent. Dialysis solution (Dianeal 4.25%) containing 1g% casein and 25 microCi 125I-human serum albumin was infused into the peritoneal cavity in 50 ml/kg volumes. Peritoneal volumes increased from a mean infused volume of 1572 +/- 51 ml to a maximum of 2119 +/- 77 ml at 3 hours. Over 6 hours, the number of macrophages and lymphocytes in the peritoneal cavity remained relatively constant but the number of neutrophils increased from 9.9 +/- 4.2 x 10(7) to 9.2 +/- 1.9 x 10(9) total cells. Caudal lymph which drains directly from the peritoneal cavity through diaphragmatic stomata, demonstrated a 5 fold increase in flow rate over 6 hours following the Dianeal-casein infusion. Thoracic duct and prescapular flows declined approximately 70% and 50% respectively in the same time period. the concentration of lymphocytes and the lymphocyte outputs (product of volume and concentration) declined in all lymph compartments. No elevations in neutrophil numbers in the thoracic and prescapular lymph compartments were observed but neutrophil output in the caudal lymph increased steadily from 3.1 +/- 1.5 x 10(6) to 4.6 +/- 1.3 x 10(7)/hr at the 6 hour mark. We conclude that the major route of removal of inflammatory cells and fluid from the peritoneal cavity is through diaphragmatic lymphatics.

Animals↗
PubMed1994

In vitro culture of human peritoneal mesothelium for investigation of mesothelial dysfunction during peritoneal dialysis.

There is a growing need for more biocompatible peritoneal dialysis fluid formulations. Using a method of in vitro cell culture we have examined the effect of osmotic agents, antiseptics and drug additives on various functions of human peritoneal mesothelial cells (HPMC). We have demonstrated that glucose and amino acids reduce the HPMC proliferation rate in a dose-dependent manner. 3H-methyl-thymidine incorporation into HPMC exposed to either 1.1% amino acid mixture or 2.0% glucose was decreased to (mean +/- SD) 32.5 +/- 6.1% and 16.8 +/- 1.2% of the control level respectively. Cultured HPMC have been shown to produce a fibrinolytic activity which may be estimated by the rate of plasma clot lysis. This activity may be diminished following the pre-incubation with 2.0% glucose and 1.1% amino acid mixture. We have found that povidone-iodine exerts a dose-dependent cytotoxic effect towards HPMC as measured by the increased 86Rb or 3H-inulin release from radiolabelled cells. We have also demonstrated that insulin enhances the 86Rb uptake and stimulates the Na, K-ATPase activity in HPMC but on the other hand is capable of reducing the phospholipids secretion from HPMC. Glucose, hydrocortisone or verapamil have also been shown to inhibit the release of mesothelial phospholipids. These data indicate that the mesothelial cell culture provides a convenient model for testing the biocompatibility of peritoneal dialysis solutions and assessing the dysfunction of mesothelial cells during peritoneal dialysis.

Cell Division↗
PubMed1993

Lymphatic drainage of hypertonic solution from peritoneal cavity of anesthetized and conscious sheep.

Lymphatic drainage of the peritoneal cavity may reduce ultrafiltration in continuous ambulatory peritoneal dialysis. We assessed lymphatic drainage of the peritoneal cavity in sheep under dialysis conditions by cannulation of the relevant lymphatic vessels and compared lymphatic drainage in anesthetized and conscious animals. Lymph was collected from the caudal mediastinal lymph node and the thoracic duct, both of which are involved in the lymphatic drainage of the ovine peritoneal cavity. Volumes of a hypertonic dialysis solution (50 ml/kg 4.25% Dianeal) containing 25 microCi 125I-human serum albumin were instilled into the peritoneal cavity, and lymph flows and the appearance of labeled protein in the lymphatic and vascular compartments were monitored for 6 h. Intraperitoneal pressures increased 4-5 cmH2O above resting levels after infusion of dialysate. On the basis of the appearance of tracer in the lymph, drainage of peritoneal fluid into the caudal lymphatic was calculated to be 3.09 +/- 0.69 and 14.14 +/- 2.86 ml/h in anesthetized and conscious sheep, respectively. Drainage of peritoneal fluid into the thoracic duct preparations was calculated to be 1.32 +/- 0.33 and 14.69 +/- 5.73 ml/h in anesthetized and conscious sheep, respectively. Significant radioactivity was found in the bloodstream, and at least a portion of this was likely contributed by the right lymph duct, which was not cannulated in our experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1993

Quantitation of lymphatic drainage of the peritoneal cavity in sheep: comparison of direct cannulation techniques with indirect methods to estimate lymph flow.

OBJECTIVE: It has been suggested that lymphatics may contribute to ultrafiltration failure in patients on continuous ambulatory peritoneal dialysis (CAPD) by absorbing dialysate and ultrafiltrate from the peritoneal cavity. In most studies lymphatic drainage has been estimated from the disappearance of an instilled tracer from the peritoneal cavity or estimated from the appearance of an intraperitoneally administered tracer in the bloodstream. However, in sheep it is possible to cannulate several of the relevant lymphatics that drain the peritoneal cavity and assess lymph drainage parameters directly. The purpose of this study was to estimate lymph drainage from the peritoneal cavity in sheep using the disappearance of tracer from the cavity and the appearance of intraperitoneally instilled tracer in the bloodstream and to compare these results with those obtained from our previous studies using cannulation techniques. DESIGN: Experiments were performed in anesthetized and nonanesthetized animals. Volumes of 50 mL/kg of Dianeal 4.25% containing 25 microCi of 125I-albumin were infused into the peritoneal cavity. RESULTS: In anesthetized sheep the calculated peritoneal lymph drainage from monitoring the disappearance of tracer from the peritoneal cavity over 6 hours was 1.873 +/- 0.364 mL/kg/hour. Monitoring the appearance of tracer in the blood gave significantly lower peritoneal lymph flow rates of 1.094 +/- 0.241 mL/kg/hour. Directly measured lymph flow rates from our earlier publication were lower still and ranged from 0.156 +/- 0.028-0.265 +/- 0.049 mL/hour/kg, depending on how we estimated the right lymph duct contribution to peritoneal drainage, since we could not cannulate this vessel. We repeated these experiments in conscious sheep. The value for lymph flow estimated from the disappearance of tracer from the peritoneal cavity was 2.398 +/- 0.617 mL/hour/kg and from the appearance of tracer in the blood, 1.424 +/- 0.113 mL/hour/kg. The lymph flow rates monitored from indwelling lymphatic catheters ranged from 1.021 +/- 0.186-1.523 +/- 0.213 mL/hour/kg (again, depending on our estimates for the right lymph duct). CONCLUSIONS: Lymph flow rates measured from indwelling lymphatic catheters provided the most conservative values for lymphatic drainage of the peritoneal cavity under dialysis conditions. Estimates of lymphatic drainage based on the appearance of tracer in the blood gave values that were on average higher. The method using the disappearance of tracer from the cavity to estimate lymph flows overestimated peritoneal lymph drainage. Fluid was lost from the peritoneal cavity, and the estimated proportion of liquid lost through lymphatic drainage depended on the technique used to measure lymph flow rates.

Absorption↗
PubMed1992

Effects of amino acid dialysate on appetite in CAPD patients.

The use of amino acid (AA) dialysate in CAPD patients may have theoretical disadvantages, since protein ingestion is known to suppress food intake in humans disproportionately to its energy value. Therefore we measured subjective appetite and food intake of CAPD patients in a cross-over study of 16 subjects (age 22-75 years, BMI 19-31, > 3 months on CAPD, non-diabetic and not protein malnourished). They received, in random order, either 4 weeks of dextrose only (their usual treatment), or one AA (1%) exchange replacing the first dextrose exchange each day. Subjective measurements of food intake (3 day food record) and quantitative measurements of lunch time food intake were obtained during a morning dextrose exchange after 28 days of each regimen. Except for a reduction in feelings of fullness during the AA treatment, there were no effects on feelings of hunger/satiety, food appeal, lunch-time food intake, or on 3-day food intake. We conclude that the use of a daily AA (1%) dialysate for 4 weeks does not affect subjective appetite or food intake of CAPD patients. There may even be a beneficial effect as the feeling of fullness decreased with the AA treatment.

Adult↗
PubMed1991

Lymphatic removal of dialysate from the peritoneal cavity of anesthetized sheep.

Several investigators have suggested that the lymphatic circulation reduces ultrafiltration in continuous ambulatory peritoneal dialysis (CAPD). The purpose of this study was to assess lymphatic drainage of the peritoneal cavity directly in anesthetized sheep under dialysis conditions. Lymph was collected from the caudal mediastinal lymph node and the thoracic duct, both of which are involved in the lymphatic drainage of the ovine peritoneal cavity, and from the prescapular lymph node, which is not involved in peritoneal lymphatic drainage. Fifty ml/kg volumes of a mildly hypertonic dialysis solution (Dianeal 1.5%) containing 25 microCi 125I-human serum albumin were instilled into the peritoneal cavity, and lymph flows and the appearance of labeled protein in the lymphatic and vascular compartments were monitored for six hours. Following the instillation of dialysis fluid there was a tendency for lymph flow rates from the thoracic duct to increase but these changes were not significant. However, flow rates from the caudal lymphatic demonstrated significant increases, especially in the final three hours of the monitoring period. Only about 8% of the radiolabeled albumin was removed from the peritoneal cavity over six hours (that is, 92% was left in the peritoneal space). Of the albumin removed, approximately 17% of this was drained by abdominal visceral lymphatics into the thoracic duct. About 25% passed through the diaphragm into the caudal mediastinal lymph node and into efferent lymph. Since the efferent lymphatic duct of the caudal mediastinal node empties directly into the thoracic duct, about 42% of all protein removed from the peritoneal cavity of the sheep was ultimately transported to the thoracic duct.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Lymphatic drainage of the peritoneal cavity in sheep.

Lymphatic drainage of the peritoneal cavity has been investigated in anesthetized sheep. Studies involving intraperitoneal administration of a complex of Evans blue dye and bovine serum albumin demonstrated the existence of three anatomically distinct pathways. In the first pathway, dye is removed from the peritoneal cavity by diaphragmatic lymphatics that pass into caudal sternal lymph nodes. Efferent lymphatics from these nodes transport the material to cranial sternal lymph nodes. Efferent cranial sternal lymphatics then convey the material either directly or indirectly, via tracheal lymphatic trunks, to the right lymph duct. In the second pathway, the complex is transported from the peritoneal cavity by diaphragmatic lymphatics that pass into the caudal mediastinal lymph node. Efferent lymphatic ducts from this node transport the material to the thoracic duct. The third pathway appears to involve transport of the dye across the mesothelial lining of the abdominal viscera and removal from the interstitium by afferent visceral lymphatics. Material taken up in this manner is ultimately transported to the thoracic duct by efferent visceral lymphatics. Experiments involving measurements of lymphatic absorption of 125I-labeled human serum albumin from the peritoneal cavity indicated that, over the 6-h period studied, 4.55 +/- 1.20 and 1.43 +/- 0.56% of the injected tracer could be recovered in thoracic duct lymph and caudal mediastinal efferent lymph, respectively, and the sum of these values represented 26% of the recovered radioactivity. On the other hand, 16.95 +/- 6.93% of the injected radioactivity could be found in the blood over the same period.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Immunoreactive parathyroid hormone and in vitro inhibition of erythropoiesis by uremic serum in patients on continuous ambulatory peritoneal dialysis.

Inhibition of erythropoiesis in vitro by uremic serum is well established. The role of parathyroid hormone (PTH) as inhibitor of erythropoiesis is uncertain. To further elucidate this effect we correlated the in vitro growth of red cell progenitors (BFU-E) in the presence of uremic serum from 26 patients on continuous ambulatory peritoneal dialysis with levels of immunoreactive PTH in the serum. The patients had a mean hemoglobin level of 100 +/- 20.1 g/l. The BFU-E growth was 98.8 +/- 28.3% of control. No correlation between BFU-E growth and hemoglobin was found. A significant negative correlation between levels of immunoreactive PTH and BFU-E growth was found (p = 0.05). These results support the notion that PTH or PTH fragment(s) might be responsible for the in vitro inhibition of erythropoiesis by uremic serum in patients on continuous ambulatory peritoneal dialysis.

Erythropoiesis↗
PubMed1982

Continuous ambulatory peritoneal dialysis in diabetics with end-stage renal disease.

Twenty diabetics with end-stage renal disease who had never previously received dialysis treatment were treated with continuous ambulatory peritoneal dialysis for periods of two to 36 months (average, 14.5). Intraperitoneal administration of insulin achieved good control of blood sugar. Even though creatinine clearance decreased significantly (P = 0.001), control of blood urea nitrogen and serum creatinine was adequate. Hemoglobin and serum albumin levels increased significantly (P = 0.005 and 0.04, respectively). Similarly, there was a significant increase in serum triglycerides and alkaline phosphatase (P = 0.02 and 0.05). Blood pressure became normal without medications in all but one of the patients. Retinopathy, neuropathy, and osteodystrophy remained unchanged. Peritonitis developed once in every 20.6 patient-months--a rate similar to that observed in nondiabetics. The calculated survival rate was 93 per cent at one year; the calculated rate of continuation on ambulatory peritoneal dialysis was 87 per cent. We conclude that continuous ambulatory dialysis with intraperitoneal administration of insulin is a good alternative treatment for diabetics with end-stage renal disease.

Adult↗
PubMed1978

Measurement of free and free-plus-peptide hydroxyproline fractions in plasma.

Plasma hydroxyproline fractions--free-plus-peptide and free--were determined by a method involving centrifugal ultrafiltration and the procedure of Kivirikko et al. [Anal. Biochem. 19, 249 (1967)]. Within- and between-day precision (CV) for the combined fractions was 4--5% and 2.8--6%, respectively. Mean analytical recoveries of free hydroxyproline were 95.2% (87--109%) in the normal range, and 97% (91--108%) in the above-normal range. Normal ranges for plasma hydroxyproline fractions, based on data for 11 men and 19 women, were free-plus-peptide, 7.5--25.3; free, 4.9--22.7; and peptide (calculated), 0.1--5.1 mumol of hydroxyproline per litre, respectively. These ranges showed no sex-related differences and were gaussian in distribution. A factor was derived to transform data on concentrations in ultrafiltrate into plasma concentrations.

Humans↗
PubMed1977

Partial body calcium measurements on patients with renal failure.

The bone calcium status of 39 patients with chronic renal failure on hemodialysis has been measured by in vivo neutron activation analysis (IVNAA) and reported in terms of a calcium bone index (CaBl) which relates the calcium in a patient to that in a normal person of the same height. In 20 of the 39 cases sequential measurements were made over periods of up to 40 mo. The results are compared with data obtained by radiology and by histological examination of bone biopsies. CaBl values varied from below normal to, in one case, above the range of normal. Many of the higher values were associated with demonstrable osteosclerosis. As found in previous work here with IVNAA, significantly low values of CaBl were associated with vertebral deformities; however, some patients with deformity had normal CaBl values, indicating that these had both local mineral loss (resulting in fracture) and osteosclerosis. Taken all together, the data suggest that more than half the patients have osteosclerosis. Sequential data showed no uniform response to treatment.

Adult↗
PubMed1977

A controlled trial of nondrolone decanoate in the treatment of uremic anemia.

Thirty-seven male dialysis patients, from three university hospital centers known to have adequate iron B12, and folate stores, were entered into a controlled trial to study the effects of nandrolone decanoate (200 mg i.m. weekly) on their anemia. An initial six-month stabilization period was followed by a randomized 12-month study, with crossover between treatment and control groups occurring at six months. Patients received parenteral iron therapy plus oral folate throughout the trial. All serious illnesses or major blood losses excluded the patients from analysis. The 24 patients with remnant kidneys showed an increase in hemoglobin and hematocrit of 24% by the end of six months of treatment (P less than 0.005), with a corresponding decrement during the six months of control, but the five anephric patients showed no statistically significant change compared to those patients whose kidneys were in place during the study. Complications of treatment were minimal, with injection site hematoma the only significant local effect and a rise in triglyceride the only significant systemic disturbance. Despite the improvement in anemia, the disadvantages, including the high cost of treatment, the apparent plateauing of benefits by five months, the minimal subjective improvement in life style, the risk of i.m. injection, plus the long term effects of increased lipids, should limit this therapy to patients with remnant kidneys who have severe symptomatic anemia or frequent transfusion requirements.

Adult↗
PubMed1977

Measurement of serum and plasma ionic calcium with the "Space-Stat 20 Ionized Calcium Analyzer".

Ca2+ was measured in sera and plasma from 36 normal subjects (18 men 23-57 years old, and 18 women 20-52 years old) with the Space-Stat 20 Ionized Calcium Analyzer. Within-day and between-day precision (CV) for commercial serum-based specimens varied from 0.64-0.96% and 1.1-3.8%, respectively, depending on their mean concentrations. Plasma and serum showed within-day CV's of 1.05 and 0.79%, respectively. The linear regression of serum Ca2+ (y) on plasma Ca2+ (x) was y = 0.63x + 0.45 mmol/litre with a highly significant (P less than 0.001) coefficient of correlation (r) of 0.69. An approximate 5% increase in the mean Ca2+ concentration in serum over that found in plasma is probably due to heparin complexing. No significant sex-related difference was observed for either serum or plasma. The mean Ca2+ concentration of 29 refrigerated specimens tended to decrease in seven days (by 2.3%, not statistically significant). The normal Ca2+ range in serum and plasma (n = 35) was 1.08-1.18 and 1.02-1.14 mmol/litre, respectively.

Adult↗