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Biomedical subjects

S Ringoir

Publications and source records attributed to S Ringoir.

At least 37 records · Page 2Linked to original sources
PubMed1995

Evaluation of renal function before and after intravenous injection of non-cholangiographic water soluble contrast media in rats.

In the present study, normal laboratory rats (n = 22), were injected intravenously with water soluble contrast media (CM) or saline. Renal function was monitored before and followed after challenge. Seven animals were injected with saline, the others with 3 different types of contrast media. The absolute urinary creatinine output decreased significantly in the saline group, from 0.0247 mumol/min 100 g BW (IR: 0.0052) to 0.0167 mumol/min 100 g BW (IR: 0.0019) (p < 0.01), while in the CM groups only a significant decrease was seen after ioxaglate injection, from 0.0250 mumol/min 100 g BW (IR: 0.0014) to 0.0174 mumol/min 100 g BW (IR: 0.0027) (p < 0.01). ANOVA between the groups showed no difference. The median values for serum creatinine after injection of the test products did not differ from the control values. It seems therefore that the challenge of a normal laboratory rat with CM is not a suitable model for the detection of subtile nephrotoxic properties of CM.

Animals↗
PubMed1994

Influence of erythropoietin on dialyzer reuse, heparin need, and urea kinetics in maintenance hemodialysis patients.

The administration of erythropoietin (EPO) in maintenance hemodialysis may affect urea kinetic parameters by altering dialyzer function during first use and reuse, and dietary protein intake as a consequence of increased appetite. In the present study, the effect of EPO treatment on urea kinetic parameters in case of reuse (n = 14) and first use (n = 10) of dialyzers was assessed in 24 clinically stable hemodialysis patients who were evaluated before and during EPO treatment. In addition, the heparin need and the number of uses before discarding the dialyzer were registered. No significant differences between urea kinetic parameters before compared with during EPO treatment were noted in the overall population or in the subgroups treated with reused or first-use dialyzers. However, in 13 patients with a low baseline protein catabolic rate (pcr(wt)) (pcr(wt) < 1.0 g/kg/24 hr before EPO treatment), pcr(wt) increased from 0.81 +/- 0.04 to 0.93 +/- 0.06 (+ 15%, P < 0.01). The heparin dosage increased from 6,693 +/- 419 IU/session to 7,659 +/- 566 IU/session and from 5,538 +/- 594 IU/session to 6,918 +/- 649 IU/session (P < 0.05) in the subgroups treated with reused or first-use dialyzers, respectively. Nevertheless, when dialyzer reprocessing was performed, the number of achieved uses before discarding the dialyzers was reduced after the introduction of EPO (5.4 +/- 0.4 v 3.4 +/- 0.4, P < 0.01). In conclusion, during EPO treatment urea kinetic parameters were not affected in case of dialyzer first use or in case of reuse. In patients with low pretreatment values, pcr(wt) increased, possibly indicating improved protein intake in malnourished patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Recombinant hirudin: a specific thrombin inhibiting anticoagulant for hemodialysis.

The first experience with hirudin as an alternative anticoagulant for heparin in hemodialysis is reported. Recombinant hirudin (HBW 023) was administered in 20 patients as a bolus before dialysis with low flux polysulfone dialyzers (PS400), the dosage being adapted stepwise from patient to patient by 0.02 mg/kg to the occurrence of clotting or bleeding. Four different administration schedules were studied. The first three schedules (0.02 mg/kg, N = 1; 0.04 mg/kg, N = 1; 0.06 mg/kg, N = 4) were discontinued because of clotting. The 0.08 mg/kg schedule was maintained without clotting event in 14 patients. Bleeding was not observed. Plasma hirudin averaged 503.9 +/- 214.0 and 527.7 +/- 217.1 ng/ml after two and four hours of dialysis, and decreased during an interdialytic interval of 44 hours to 223.2 +/- 86.2 ng/ml. Modified antithrombin III (P < 0.05) and activated partial thromboplastin times were lower (P < 0.01) under hirudin compared to heparin; these coagulation parameters were closer to normal during hirudin treatment. The patients developing clotting could be distinguished from those without clotting by the registration of the activated clotting times (9.2 +/- 3.0 vs. 18.7 +/- 3.2 min after 2 hr, P < 0.01; 8.1 +/- 3.0 vs. 16.2 +/- 3.8 min after 4 hr of dialysis, P < 0.05); cut-off value below which clotting is to be expected was 12 min). It is concluded that administration of hirudin as a bolus before the start of dialysis, at a dosage of 0.08 mg/kg, is not complicated by clotting or by bleeding. Coagulation tendency can optimally be monitored by the registration of the activated clotting time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Factors and complications affecting catheter and technique survival with permanent single-lumen dialysis catheters.

This long-term study on the outcome of permanent silicone single-lumen dialysis catheters consisted of 43 surgically inserted catheters in 33 patients. All catheters were attached to a pressure-pressure single-cannula dialysis system. Technique and catheter survival were 80 and 59% at 1 year, and 63 and 50% at the 3rd year respectively. These parameters were not different in older patients (> or = 70 years, n = 12). Factors corresponding to a less successful outcome were placement in the left jugular vein (3-month actuarial survival of 44%) and absence of distal side holes (1-year actuarial survival of 44%). Insertion in both subclavian veins was not different to the classical right jugular vein. Infectious complications (incidence of 0.72 per 1000 catheter days) often caused simultaneous catheter and technique failure (14 versus 15%), whereas inadequate flow (incidence of 2 per 1000 catheter days) caused catheter rather than technique failure (30 versus 12%). The incidence of both complications declined significantly with time after insertion during the follow-up period. The first 3 months after insertion were more predisposed to the occurrence of inadequate flow than catheter-related infections. The general performance of these permanent single-lumen catheter devices justifies their long-term application in haemodialysis, even as a first choice of vascular access, especially in the elderly. Insertion in the left jugular vein and use of catheters without side holes should be avoided, providing a better catheter survival.

Adult↗
PubMed1994

Vascular access for hemodialysis.

Indwelling central venous catheters were consecutively used as access for acute and chronic hemodialysis, emergency treatment of pulmonary fluid overload, intoxication and electrolyte disturbances, plasmapheresis, and semiacute continuous dialysis strategies, such as continuous arteriovenous hemofiltration (CAVH). Modification in catheter structure also made it possible to use this access for long-term treatment (e.g., surgically insertable catheters [Hickman], soft large-bore catheters for blind insertion). We discuss the remaining open questions in this field: Which is the insertion site of preference (i.e., subclavian, femoral, or deep jugular)? Should we prefer stiff or soft catheters? Should soft catheters be positioned surgically or is blind insertion by nonsurgeons as adequate? Is it necessary to couple catheter insertion to adjuvant techniques, such as echographic guidance, to reduce complications? Is the currently used polymer structure of the catheters acceptable? Should catheter dialysis be used with single or double vascular access?

Catheterization, Central Venous↗
PubMed1994

Subclavian vein hemodialysis catheters: advantages and disadvantages.

The pros and cons of subclavian vein hemodialysis catheters are reviewed. The subclavian vein catheter offers rapid and adequate vascular access. Other advantages are preservation of patient mobility and the ease with which the dressing can be secured. In contrast, subclavian vein stenosis has recently been identified as an important long-term complication of subclavian vein catheters that seriously compromises the creation and long-term viability of later ipsilateral arteriovenous fistulas. For this reason, we recommend restricting use of the subclavian hemodialysis catheter for acute situations and preferential use of internal jugular catheters for more chronic approaches because they better preserve venous integrity.

Catheterization, Central Venous↗
PubMed1994

Uraemic toxic retention solutes depress polymorphonuclear response to phagocytosis.

Previous studies from our laboratory have demonstrated that the activity of the hexose monophosphate shunt (HMS) pathway in phagocytosis-related respiratory burst is disturbed in end-stage renal disease. To determine whether uraemic solute retention is responsible for this defect the HMS-path was evaluated by measurements of glucose-1-C14 utilization and determination of 14CO2 production in polymorphonuclear cells (PMNLs), suspended in normal plasma or uraemic biological fluids. Normal PMNLs, while suspended in normal or uraemic plasma, were stimulated with either latex, zymosan or Staph. aureus; CO2 generation (measured as DPM/10(3) PMNL, normal versus uraemic plasma) was depressed in uraemic plasma in response to latex (from 43 +/- 5 to 20 +/- 3), zymosan (from 72 +/- 8 to 47 +/- 4) (P < 0.01), and Staph aureus (from 73 +/- 17 to 47 +/- 8 DPM/10(3) PMNL) (P < 0.05). The degree of inhibition was similar for each stimulus. To characterize the substances responsible for this defect we fractionated uraemic plasma ultrafiltrate by polarity-based semipreparative C18 reversed phase HPLC and found a decreased response to Staph. aureus in the presence of fraction 2 (from 102 +/- 13 to 23 +/- 10 DPM/10(3) PMNL, P < 0.05), and in fractions 8 and 11 (lowest value in fraction 8, 54 +/- 14 DPM/10(3) PMNL, P < 0.05 versus control). The pattern of HPLC elution on a gradient from 100% formiate (pH 4.0) to 100% methanol indicates that there are at least two chemically distinguishable groups of compounds, one hydrophilic (in fraction 2), and one lipophilic (in fractions 8 and 11). We conclude that uraemic biological fluids contain factors that inhibit HMS activity related to phagocytosis, and that at least two groups of components with different characteristics are involved.

Adult↗
PubMed1993

Factors influencing drug protein binding in patients with end stage renal failure.

Investigations were undertaken to evaluate which uraemic solutes decrease drug protein binding. This was done by performing HPLC-fractionation of uraemic biological fluids and studying the effect of addition of a lyophilisate of each fraction to normal plasma containing standard quantities of radiolabelled drugs. From a first study, based only on fractionation of uraemic ultrafiltrate with an HPLC-gradient mainly aimed at elution of hydrophilic compounds, hippuric acid appeared to be a major protein binding inhibitor for theophylline and phenytoin. The problem with this approach was that it did not include the compounds with the most substantial protein binding. Therefore, studies were planned to fractionate deproteinized uraemic sera, but first it was necessary to define which deproteinisation methods gave the highest yields of protein bound ligand. Heat denaturation was found to be one of the most effective deproteinisation methods. When a lyophilisate of uraemic serum, deproteinised by this method, was added to normal plasma, a higher capacity to displace theophylline from protein binding sites was found compared to the effect of an identical volume of an ultrafiltrate of the same samples. Fractionation of the deproteinised sample by HPLC revealed a larger number of fractions able to inhibit drug protein binding.

Humans↗
PubMed1993

Single-dose pharmacokinetics of cefpirome in patients receiving hemodialysis and in patients treated by continuous ambulatory peritoneal dialysis.

Cefpirome is eliminated primarily by renal excretion, compelling dosage reduction in kidney failure. We studied the elimination kinetics after intravenous administration of 1 gm cefpirome in patients undergoing hemodialysis (n = 9) and after intravenous (n = 6) or intraperitoneal administration (n = 6) of 1 gm cefpirome in subjects treated by continuous ambulatory peritoneal dialysis (CAPD). Four hours of hemodialysis removed 48% +/- 9% of the drug present in the body at the start of hemodialysis. Consequently, a supplementary dose equal to 50% of the daily dose recommended in end stage renal disease (ESRD) should be administered after each hemodialysis treatment. In patients receiving CAPD, therapeutic levels in both serum and dialysate were reached after intravenous and intraperitoneal administration. The bioavailability after intraperitoneal administration was 84%. After systemic administration, the elimination of cefpirome in the dialysate was negligible. Consequently, systemic dosage of cefpirome in patients receiving CAPD and in patients with ESRD should be identical.

Adult↗
PubMed1993

Contributing factors to the inhibition of phagocytosis in hemodialyzed patients.

Although polymorphonuclear (PMNL) glucose consumption as an index of metabolic response to phagocytosis in the production of free radical species is depressed in hemodialyzed patients, substantial interindividual differences are registered. Studies evaluating to what variables these differences are related are, however, lacking. In the present study, the relation of several factors to PMNL functional capacity in the breakdown of glucose to CO2 by the hexose monophosphate shunt (HMS) is considered in an individual and multifactorial regression analysis. Starting from a database, collected in 126 stabilized hemodialysis patients, PMNL HMS-response to standard quantities of latex and zymosan was correlated to 14 numerical parameters: time since the start of dialysis, hematocrit, serum creatinine, phosphorus, ferritin, albumin, parathormone, albumin before and after administration of desferrioxamine, residual creatinine clearance, PCR, TACurea, Kt/V and age. In addition, the non-numeric parameters of sex, biocompatibility of dialyzers, and primary diagnosis were also considered. A significant correlation was found for time on dialysis (P < 0.001), hematocrit (P < 0.001), ferritin (P < 0.05), PTH (P < 0.001) and aluminum (P < 0.05). The highest correlation coefficients were found for time on dialysis (latex: N = 126, r = 0.50, P < 0.001; zymosan: N = 126, r = 0.58, P < 0.001). Multivariate correlation analysis of one clinical parameter together with time on dialysis to PMNL response showed that the correlation was strongly weakened or disappeared for ferritin, aluminum and PTH, but not for hematocrit. Our data indicate that time since the start of dialysis is an important, but not unique factor, influencing polymorphonuclear functional capacity in a hemodialysis population.

Bacterial Infections↗
PubMed1993

Depressed phagocytosis in hemodialyzed patients: in vivo and in vitro mechanisms.

Infection is a frequent complication and the major cause of death among end-stage renal patients. Polymorphonuclear phagocytes (PMNL) are important in host defense mainly because of bacterial destruction by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-related free radical production following phagocytosis. In this study, hexose monophosphate pathway glycolytic activity, delivering energy to NADPH oxidase, is evaluated in vivo and in vitro, in healthy controls and in dialyzed renal failure patients. Our results show a marked parallel and correlated inhibition in the response to three stimuli for phagocytic activity (Staphylococcus aureus, formyl-methionine-leucine-phenylalanine, phorbol myristic acid) in predialysis samples. These data point to a main suppression of metabolic pathways, possibly beyond protein kinase C. This response is further suppressed at the 15th minute of cuprophane dialysis, for all stimuli studied (-40 to -94%; p < 0.001) except PMA. PMNL response remains intact during dialysis with non-complement-activating dialyzers. In vitro experiments confirm decreased PMNL glycolytic activity after the suspension of cuprophane fragments in normal whole blood. We conclude that polymorphonuclear cell energy delivery to NADPH oxidase is impaired in patients with end-stage renal failure. The impaired response against various stimuli is different in predialysis blood samples compared to samples collected during cuprophane dialysis, and may be related to two different conditions. These events probably contribute to the acquired immune suppression of uremia and the high incidence of infection among dialysis patients.

Cellulose↗
PubMed1993

Infectious morbidity and defects of phagocytic function in end-stage renal disease: a review.

Infectious diseases remain among the most morbid events and are an important cause of death in ESRD. These events are related to an acquired immunodeficiency that progresses during the development of uremic retention, as part of the broader spectrum, displayed by the "uremic syndrome". A central role in the hose defense against bacterial infection is played by the phagocytic polymorphonuclear white blood cells, which are characterized by the capacity to ingest bacteria (phagocytosis), which is followed by the destruction of those bacteria (killing capacity). This article reviews the mechanisms of development and the potential causes that have been held responsible for this aspect of the defective immune function. The observed changes are attributed to alterations in receptor expression, although more convincing evidence points in the direction of metabolic functional disturbances, especially in the NAD(P)H-oxidase-dependent production of oxygen free radicals. The most important causative factors are: uremic toxicity, iron overload, renal anemia, dialyzer bioincompatibility, and the type of renal replacement therapy. It is concluded that the phagocytic defect in ESRD is multifactorial and that each factor should be managed by specific therapeutic approaches.

Humans↗