Search PubMed⌕ Search

Biomedical subjects

N Lameire

Publications and source records attributed to N Lameire.

At least 19 recordsLinked to original sources
PubMed2002

The 13C-octanoic acid breath test: validation of a new noninvasive method of measuring gastric emptying in rats.

Currently available rat models for measuring gastric emptying are hampered by the necessity to kill the animals at the end of each experiment, which makes repetitive testing impossible. We have developed and validated a noninvasive test model, adapted from the 13C-octanoic breath test in humans, for repetitive measurements of gastric emptying in rats. Male Wistar rats were trained on a fixed protocol to eat a piece of pancake doped with 1 microg 13C-octanoic acid after 12 h fasting, and to stay thereafter in cylindrical glass cages. Breath tests were performed by a fully automated system of computer-guided switching valves, which collected consecutive breath samples. All breath samples were analysed by gas chromatography and isotope mass spectrometry. The area under the curve (AUC) from the cumulative 13CO2 excretion from 0 to 6 h was determined by the trapezium method to calculate the gastric half-emptying times (t(1/2)). Inter-day variability was determined. The effect of subcutaneous or intraperitoneal injection of saline was studied. The test was further validated for pharmacological interventions by oral administration of cisapride and parenteral administration of atropine, to induce, respectively. acceleration and delay of gastric emptying. Mean gastric emptying times +/- SD of 24 rats were 119.3 +/- 28.2 min, 138.7 +/- 26.0 min, and 124.5 +/- 30.9 min on three different test days. The mean coefficient of variation of three repeated measurements in the same 24 rats was 17.5%. No significant differences were observed after subcutaneous or intraperitoneal injection of saline. In a second test series of eight rats, cisapride significantly accelerated gastric emptying (mean t(1/2) 112.7 +/- 33.1 min, P < 0.05), while atropine caused a significant delay (mean t(1/2) 205.9 +/- 24.9 min, P < 0.05) when compared to control test results (mean t(1/2) 140.7 +/- 16.7 min) in the same rats. We validated the 13C-octanoic breath test to study gastric emptying in rats. This test method obviates the necessity to kill laboratory animals and allows repetitive measurements of gastric emptying to study its physiology or pathophysiology as well as the effect of pharmacological agents.

Animals↗
PubMed2002

Alternative timeframes for hemodialysis.

Routinely, maintenance hemodialysis is applied according to an alternate day time schedule with dialysis sessions lasting 3 to 5 h. In analogy with continuous ambulatory peritoneal dialysis, a more gradual and more consistent removal pattern could be achieved by modifying this timeframe, e.g., by applying daily hemodialysis and/or by prolonging hemodialysis sessions to 8 h or more. Recently, a number of dialysis units implemented such alternative timeframes. Both the clinical and metabolic status showed dramatic improvements with beneficial effects on blood pressure, anemia, and potassium and phosphate levels. These changes occurred despite decreases in the dosage of the drugs administered to cope with these problems. However, controlled studies comparing morbidity and mortality of these alternative timeframes to the more traditional approaches are lacking at this moment.

Humans↗
PubMed2002

Gastric emptying of solids in cirrhotic and peritoneal dialysis patients: influence of peritoneal volume load.

INTRODUCTION: A delay in gastric emptying rate has been reported in peritoneal dialysis patients, often normalizing after evacuation of the dialysate. To evaluate the effect of the intraperitoneal volume, we compared this finding with a cirrhotic model in which gastric emptying was studied before and after a large-volume paracentesis. METHODS AND DESIGN: We used the 13C-octanoic acid breath test to measure gastric half-emptying time (T1/2) for solids in patients with alcoholic cirrhosis, non-diabetic peritoneal dialysis patients, and a control population (asymptomatic volunteers). Cirrhotic patients underwent the test on two consecutive mornings before and after an evacuating paracentesis. Peritoneal dialysis patients were studied twice on consecutive days: once with the dialysate present intra-abdominally ("full"), and once with an emptied abdomen ("empty"). Biochemical analysis was carried out on blood samples before the first test. All cirrhotics underwent a 13C-aminopyrine breath test to assess residual liver function. RESULTS: Gastric emptying in cirrhotics showed no difference before or after paracentesis (median T1/2 108.0 min v. 117.9 min), but it was delayed significantly versus normal in both tests. There was no correlation with biochemical parameters, Child-Pugh score, or 13C-aminopyrine breath test results. Gastric half-emptying times of "full" peritoneal dialysis patients (median T1/2 103.1 min) were significantly higher than those of "empty" peritoneal dialysis patients (median T1/2 68.9 min) and asymptomatic volunteers (median T1/2 60.1 min). "Empty" peritoneal dialysis patients showed no gastroparesis. CONCLUSION: In alcoholic cirrhotic patients with ascites, gastric emptying of solids is delayed, independently of the volume of ascites. In peritoneal dialysis patients, gastric emptying was delayed when "full" and normalized after drainage of the dialysate.

Adult↗
PubMed2002

Dyspepsia and gastroparesis in chronic renal failure: the role of Helicobacter pylori.

AIMS: Many patients with chronic renal failure have dyspeptic symptoms. In the present study, we assessed the Helicobacter pylori (Hp) status, dyspeptic symptoms and gastric emptying rates in uremic patients. The present study was undertaken to compare chronic renal failure patients not under dialysis therapy (predialysis), hemodialysis (HD) patients and peritoneal dialysis (PD) patients for these variables and to search for a possible causative role of Hp. METHODS: We used a standardized questionnaire to assess dyspeptic symptoms. Gastric emptying rates were determined by the 13C-octanoic acid breath test. HD patients were examined outside a dialysis session, PD patients were examined with a "full" abdomen. Specific Helicobacter pylori IgG was measured by a second-generation enzyme-linked immunosorbent assay. RESULTS: Sixty-six HD patients. 58 predialytic patients and 28 PD patients were included. Prevalences of Hp infection were highest in HD patients (46.2%) and predialysis patients (42.3%) compared to PD patients (28.6%) (p < 0.02). On the contrary, the prevalence of dysmotility-like dyspepsia was higher in PD patients (67.9%) when compared to HD patients (33.3%) (p < 0.01) and predialytic patients (53.6%) (difference not significant). Neither dyspepsia nor delayed gastric emptying were related to the presence of Helicobacter pylori IgG antibodies. CONCLUSION: A positive Helicobacter status based on serology was not related to the presence of dyspepsia or gastroparesis in uremic patients, whether on dialysis therapy or not. Dyspeptic complaints as well as gastroparesis are most prevalent in patients on peritoneal dialysis. The physiopathological mechanisms and clinical impact of these findings merit further investigation.

Adult↗
PubMed2002

The ionized fraction of serum total magnesium in hemodialysis patients: is it really lower than in healthy subjects?

AIM OF THE STUDY: Based on data in the literature, it remains unclear whether the ionized fraction of serum total magnesium (Mg) is lower in chronic hemodialysis (HD) patients compared to healthy subjects. PATIENTS AND METHODS: The ionized fraction of serum total Mg was investigated in 49 HD patients, pre- and post-dialysis, and compared to 30 healthy controls. The quality of the analytical performance of the Mg measurements has been emphasized by applying a reference method and/or rigorous internal quality control (IQC). In addition, the ionized fraction of serum total calcium (Ca) was measured in both populations, because the results for Mg should be related to those of Ca. RESULTS: In HD patients, the ionized fraction of serum total Mg was on average 65% (pre-dialysis 64.2% and post-dialysis 66.2%). In healthy controls, the ionized fraction was 64.9%. When the analytical variability was taken into account, no significant differences (p > 0.05) were observed between pre- and post-dialysis samples and controls. For Ca, an ionized fraction of 55.3% was found in HD patients, which was not significantly different from the fraction obtained in the control group (55.7%). CONCLUSION: The present study demonstrates that, compared to healthy controls, the ionized fraction of serum total Mg is not different in hemodialysis patients.

Aged↗
PubMed2001

Kinetics of the protein-bound, lipophilic, uremic toxin p-cresol in healthy rats.

P-Cresol, a partially lipophilic and protein-bound compound is related to several biochemical alterations in uremia. Because p-cresol kinetics have never been studied, we investigated its kinetic behavior in rats. Results were compared with those obtained with creatinine, a water soluble, non-protein-bound uremic retention solute, which is currently used as a marker of uremic retention. Healthy rats were divided into 3 groups with comparable body weight: (1) a control group (n=6); (2) a group (n=7) which received an intravenous bolus of 3 mg p-cresol; and (3) a group (n=5) which received an intravenous bolus of 18 mg creatinine. Blood samples were collected at 0, 5, 30, 60, 120, 180 and 240 minutes after administration for the determination of p-cresol and creatinine. Urine was collected at 1-hour intervals. p-Cresol concentrations were assessed by HPLC. Pharmacokinetic parameters of p-cresol and creatinine were calculated from the serum concentration-time curves using non-compartmental analysis. Each compound showed a concentration at time point 5 min (p-cresol: 6.7 +/- 1.4 mg/L and creatinine: 141 +/- 12 mg/L) which was comparable with values observed in uremic patients; these concentrations decreased gradually towards min 240 (p-cresol: 0.6 +/- 0.3 mg/L and creatinine: 4 +/- 2 mg/L, p<0.05 vs. 5 min in both cases). No p-cresol was found in the serum of control rats and these rats showed no changes in serum concentration of creatinine. Urinary excretions were strikingly different (p-cresol: 23 +/- 10% and creatinine: 95 +/- 25% of the administered dose, p<0.05). The half-life of p-cresol was twice as long as that of creatinine (1.5 +/- 0.8 vs. 0.8 +/- 0.1 h, p<0.05). Total clearance (CLt) was much higher for p-cresol than for creatinine (23.2 +/- 4.5 vs. 8.1 +/- 0.4 mL/min/kg, p<0.01); renal clearance (CLr), however, was substantially lower for p-cresol (4.8 +/- 2.0 vs. 8.2 +/- 1.9 mL/min/kg, p<0.05). Whereas CLt and CLr were similar for creatinine, CLt of p-cresol largely exceeded its CLr (p<0.05). The volume of distribution (Vd) was also much larger for p-cresol than for creatinine (2.9 +/- 1.4 vs. 0.6 +/- 0.1 L/kg, p<0.01). After injection of p-cresol, an additional chromatographic peak appeared in serum and in urine samples. Although at min 240 serum concentration of p-cresol had decreased to 10% of the peak value, only 23% of the administered amount was excreted in the urine and the CLr was +/- 50% lower compared to that of creatinine. Non-renal clearance and Vd of p-cresol were, however, substantially larger. These data may be of value to explain the different behavior of p-cresol in renal failure and dialysis, compared to creatinine.

Animals↗
PubMed2001

Non-ideal behaviour of free vanadate on a Superose 12 size-exclusion column. Application to in vivo 48V-labelled rat spleen homogenate.

Seven chromatographic columns were evaluated for the recovery of 48V-radiolabelled vanadate. Further, the behaviour of vanadate (H2VO4-) was studied on a size-exclusion column Superose 12 as a function of (a) buffer salt molarity, (b) different buffer salts, (c) different buffers and (d) organic solvents added to the buffer. As opposed to the unsatisfactory recovery of V-compounds on other columns, we recovered the vanadium quantitatively. We observed that in most cases vanadate eluted after the total volume of the Superose 12 column. This indicates a non-ideal behaviour of vanadate. However, through this non-ideal behaviour it was possible to separate low-molecular-mass bound (Mr<5000) and unbound vanadium which would not be possible under normal behaviour. A possible explanation for this non-ideal behaviour of vanadium is put forward. The method has been successfully applied for the fractionation of different vanadium species in rat spleen homogenate.

Animals↗
PubMed2001

Life-threatening hyperkalemia during combined therapy with angiotensin-converting enzyme inhibitors and spironolactone: an analysis of 25 cases.

PURPOSE: The beneficial effects of spironolactone are additive to those of ACE inhibitors among patients with heart failure and/or hypertension; however, it is essential to identify patients prone to develop serious hyperkalemia during combined treatment and to evaluate the associated morbidity and mortality. SUBJECTS AND METHODS: We studied 25 patients treated with ACE inhibitors and spironolactone who were admitted to the emergency room with a serum potassium level > 6 mmol/L. Patients were followed up for at least one month after admission. RESULTS: The mean age of the patients (11 males, 14 females) was 74 +/- 13 years. Five patients were diabetics. On admission, the serum potassium was 7.7 +/- 0.7 mmol/L and the serum creatinine was 3.8 +/- 1.8 mg/dL; these values were significantly higher than the most recent follow-up laboratory measurements (4.6 +/- 0.5 mmol/L and 1.9 +/- 1.2 mg/dL, respectively) obtained at 13 +/- 5 weeks before admission. The arterial pH on admission was 7.3 +/- 0.1 and the plasma bicarbonate was 18 +/- 5 mmol/L. The main causes for acute renal failure were dehydration (n = 12) and worsening heart failure (n = 9). The mean daily dose of spironolactone was 57 +/- 32 mg and 12 patients were concomitantly treated with other drugs that may cause hyperkalemia. Two patients died, and 2 patients were resuscitated but survived. Hemodialysis was necessary in 17 patients; 12 patients were admitted to the intensive care unit. The mean duration of hospitalization was 12 +/- 6 days. Two patients needed to be started on maintenance hemodialysis therapy. CONCLUSION: A combination of ACE inhibitors and spironolactone should be considered with caution and monitored closely in patients with renal insufficiency, diabetes, older age, worsening heart failure, a risk for dehydration, and in combination with other medications that may cause hyperkalemia. A daily spironolactone dose of 25 mg should not be exceeded.

Aged↗
PubMed2001

In vivo distribution and speciation of [114mIn]InCl3 in the Wistar rat.

Five Wistar rats were given an intraperitoneal injection of [114mIn]InCl3 during four consecutive days. One hour after the last injection the rats were sacrificed. The in vivo distribution of 114mIn was studied in the blood and in different organs. Differential centrifugation was used to study the distribution in liver, kidney and spleen homogenate. Rat serum, packed cell lysate, urine and the cytosol of liver, kidney and spleen homogenate were examined by size exclusion fast protein liquid chromatography. The results showed that serum accounts for 90% of the indium activity in whole blood. Indium is preferentially accumulated within the liver, spleen and kidney, the highest amount of 114mIn being localised in the cytosolic fraction followed by the mitochondria. Size exclusion experiments showed that, in rat serum, indium is exclusively bound to transferrin. These results differed from earlier in vitro incubation experiments of human serum with 114mIn. It was not possible, from the experiments described herein, to conclude unequivocally whether indium is bound to haemoglobin of packed cell lysate or to another high molecular mass compound. Indium is associated with the high molecular mass fraction in liver, kidney and spleen cytosol; only in kidney are small amounts of 114mIn found in the low molecular mass fraction. The in vivo inhibitory effect of indium on the delta-aminolaevulinic acid dehydratase (ALAD) enzymatic activity in red blood cells and kidney tissue, well documented by other researchers, could not be attributed to direct binding of indium with this enzyme.

Animals↗
PubMed2001

Inhibition of nitric oxide synthase reverses changes in peritoneal permeability in a rat model of acute peritonitis.

BACKGROUND: Acute peritonitis is the most frequent complication of peritoneal dialysis (PD), and nitric oxide (NO) is thought to play a role in the structural and permeability changes observed in this condition. We have used a combination of expression, enzymatic and pharmacological studies to substantiate the potential role(s) played by NO during peritonitis. METHODS: The peritoneal equilibration test was performed in control rats and rats with acute peritonitis (originating from skin flora), using standard dialysate supplemented or not with the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). In parallel, peritoneal NOS enzymatic activities were measured and expression studies for NOS isoforms and S-nitrosocysteine reactivity performed in the peritoneum. RESULTS: In comparison with controls, rats with acute peritonitis were characterized by inflammatory changes, increased S-nitrosocysteine immunoreactivity, and increased NOS activities in the peritoneum, due to the up-regulation of endothelial and inducible NOS. In parallel, rats with acute peritonitis showed increased permeability for small solutes; decreased sodium sieving; loss of ultrafiltration (UF); and increased protein loss in the dialysate. Addition of L-NAME to the dialysate did not induce permeability changes in control rats, but significantly improved UF and reversed permeability modifications in rats with peritonitis. The effect of L-NAME was reflected by a mild but consistent increase in blood pressure during PD exchange. CONCLUSIONS: Our results demonstrate that local generation of NO, secondary to up-regulation of NOS isoforms, plays an important role in the regulation of peritoneal permeability during acute peritonitis in rats. By itself, NOS inhibition improves UF and reverses permeability changes, which might offer new therapeutic perspectives in acute peritonitis.

Acute Disease↗
PubMed2001

Intervention of the Renal Disaster Relief Task Force in the 1999 Marmara, Turkey earthquake.

BACKGROUND: Major earthquakes are followed by a substantial number of crush syndromes and pigment-induced acute renal failures (ARFs). The natural evolution of this problem rapidly leads to death. Today's possibilities of dialysis therapy enable saving numerous lives that otherwise would be lost. Currently, the primary problem is organizational, if huge catastrophes occur and complex therapeutic options need to be offered to a large number of victims. METHODS: Following the 1988 Spitak earthquake in Armenia, the International Society of Nephrology (ISN) established the Renal Disaster Relief Task Force (RDRTF) in order to anticipate organizational problems related to renal care in the aftermath of large natural and human-made catastrophes. The proposed concept was one of a dialysis advance team, which would assess the needs and possibilities of dialysis treatment, to be followed by supportive manpower and supplies. This article describes the organizational aspects of a rescue action that was undertaken following the Marmara earthquake, which occurred on August 17th, 1999, in northwestern Turkey. In conjunction with Médecins Sans Frontières, a team landed at Istanbul Airport less than 22 hours after the disaster, and logistic and material support as well as manpower were provided over a period of approximately one month. Specific attention was paid to the choice of the renal replacement therapy, the transport of victims and materials, the implementation of preventive rehydration, and the problem of chronic renal failure patients dialyzed in the damaged area. CONCLUSIONS: We demonstrate how previously anticipated international support may offer moral, financial, as well as logistical help to local nephrological communities confronted with serious disasters.

Acute Kidney Injury↗
PubMed2001

The Marmara earthquake: epidemiological analysis of the victims with nephrological problems.

BACKGROUND: Crush syndrome resulting from earthquakes is a major cause of morbidity and mortality, as seen during the catastrophic Marmara earthquake that struck Northwestern Turkey in August 1999. This report analyzes the epidemiological characteristics of the crush syndrome victims of this disaster. METHODS: In order to analyze the nephrological problems caused by this earthquake, questionnaires were prepared within the first week of the disaster and sent to 35 reference hospitals that treated the victims. Data obtained by these questionnaires are the subject of this report. RESULTS: Of the 5302 hospitalized patients in reference hospitals, 639 (12.0%) suffered from nephrological problems, and 477 (9.0%) needed dialysis support. Considering the patients with renal problems, there was not any significant difference in gender; however, the incidence of children younger than 10 years and the older population (older than 60 years of age) was significantly lower as compared with the resident population of the affected area (P < 0.001). Nonsurvivors were older (34.5 +/- 16.1 years) than survivors (31.2 +/- 14.4 years, P = 0.048), while no deaths were recorded under the age of 10. Most patients (70.1%) were admitted within the first three days after the earthquake, and the mortality rate among these victims was higher (17.7%) as compared with victims admitted thereafter (10.0%, P = 0.016). The average time period under the rubble was 11.7 +/- 14.3 hours, which was not significantly different between survivors and nonsurvivors, while the victims who required dialysis support spent shorter durations under the rubble, as compared with the ones who were not dialyzed at all (10.3 +/- 9.5 vs. 15.9 +/- 23.1 hours, P < 0.001). CONCLUSION: Victims of catastrophic earthquakes are characterized by a high incidence of renal problems and the need for dialysis support. The incidence of nephrological problems is lower in children, while the period of time under the rubble is not a prognostic indicator of survival.

Adolescent↗
PubMed2001

Protein-bound uremic solutes: the forgotten toxins.

The present concept of dialysis focuses mainly on the removal of small water-soluble compounds, and also, the currently applied kinetic parameters of dialysis adequacy are based on the behavior of water-soluble compounds. Nevertheless, many of the currently known biological effects in uremia are attributable to compounds with different physicochemical characteristics, and among these, protein-bound solutes play an important role. In this article, we review the characteristics and consequences of changes in protein binding in uremia, as well as the toxicity of the protein-bound uremic solutes 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), indoxyl sulfate, hippuric acid, homocysteine, and p-cresol. Starting from the example of p-cresol, we then summarize the impact of protein-binding on dialytic removal, whereby it is concluded that this removal is largely hampered by this protein-binding compared with that of classic markers such as urea and creatinine. Alternative removal strategies, such as strategies to modify intestinal generation or absorption, are considered.

Animals↗
PubMed2001

Uremic toxins and peritoneal dialysis.

Uremic toxicity is related in part to the accumulation of toxic substances, the nature of which has only partly been characterized. Because of the use of a highly permeable membrane and better preservation of the residual renal function, it could be anticipated that some of these uremic toxins are more efficiently cleared across the peritoneal membrane, and that the plasma and tissue levels of these compounds are lower than in hemodialysis patients. This article analyzes the generation and removal of several uremic toxins in peritoneal dialysis patients. The following uremic toxins are discussed: beta2-microglobulin, advanced glycation end products, advanced oxidation protein products, granulocyte inhibitory proteins, p-Cresol, and hyperhomocysteinemia. Some recent studies are reviewed suggesting that uremic toxins are involved in the progression of renal failure and are at least partially removed by peritoneal dialysis. We conclude that, although the plasma levels of some of these compounds are lower in peritoneal dialysis versus hemodialysis patients, it does not mean that the peritoneal dialysis patient is "better" protected against the numerous disturbances caused by these toxins.

Animals↗
PubMed2001

The anti-proliferative effect of calcitriol on HL-60 cells is neutralized by uraemic biological fluids.

BACKGROUND: It has been demonstrated that uraemic serum/ultrafiltrate inhibits cell-mediated immune response in vitro, and that it suppresses calcitriol synthesis and its biological actions. METHODS: In the present in vitro study, the effect of calcitriol, uraemic ultrafiltrate (UUF) and a combination of both on the human promyelocytic leukaemia cell line, HL-60, was studied by evaluating bromodeoxyuridine (BrdU) incorporation into the DNA, luminol-amplified chemiluminescence (CL) production, expression of CD14, and levels of vitamin D receptor mRNA (VDR mRNA) and CD14 mRNA. RESULTS: The ability of calcitriol to block cell proliferation (37.4+/-5.4 to 30.5+/-5.6% cells incorporating BrdU, P:<0.01) was neutralized when UUF was applied together with calcitriol (53.4+/-21.3% cells incorporating BrdU, P:<0.01 vs calcitriol alone). Similarly to what was observed for BrdU incorporation, the CL production of HL-60 cells was enhanced in the presence of calcitriol (20126+/-10154 to 61528+/-24021 cpm, P:<0.01), and was suppressed again in the presence of calcitriol and UUF (20916+/-12075 cpm, P:<0.01 vs calcitriol alone); finally UUF also inhibited the calcitriol-induced CD14 expression (71.1+/-11.2 to 54.9+/-17.7% CD14 positive cells, P:<0.05). On the other hand, the calcitriol-induced CD14 mRNA levels were not significantly different in the presence of calcitriol and UUF compared to calcitriol alone. This points to an inhibition by UUF at a post-transcriptional level. Similar data were found for VDR mRNA levels. UUF was fractionated by HPLC in four fractions, hydrophilic uraemic solutes being eluted first (F1) and hydrophobic solutes being eluted last (F4); fractions 1, 2 and 3 simultaneously affected both BrdU incorporation and CL production in a significant way. CONCLUSIONS: It is concluded that UUF contains factors that impair calcitriol-activated function of HL-60 cells. Hence, the differentiation and immune response of these promyelocytic leukaemia cells, as induced by the supplementation of calcitriol, is neutralized in the presence of uraemic biological fluids. This may be of relevance for the propensity to infection and malignancy of the uraemic patient.

Biological Factors↗