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Biomedical subjects

Joris R Delanghe

Publications and source records attributed to Joris R Delanghe.

At least 37 records · Page 2Linked to original sources
PubMed2004

Automated flow cytometry analysis of peritoneal dialysis fluid.

BACKGROUND: Recently, the Sysmex UF-100 flow cytometer has been developed to automate urinalysis. We have evaluated this instrument to explore the possibilities of flow cytometry in the analysis of peritoneal dialysis fluid (PD) and have compared the obtained data with those of counting chamber techniques, biochemical analysis and bacterial culture. METHODS: UF-100 data were correlated with microscopy and biochemical data in 135 PD samples. Microbiological analysis was performed in 63 suspected cases of peritonitis. RESULTS: Good agreement (P < 0.001) was obtained between UF-100 and microscopy data for leukocytes (r = 0.825). UF-100 bacterial count correlated (P < 0.001) with UF-100 leukocyte count (r = 0.549). UF-100 bacterial counts were unreliable in samples where interference by blood platelets was observed. Another major problem was the UF-100 'bacterial' background signal in sterile PD samples. Yeast cells were detected by the flow cytometer in spiked samples. CONCLUSIONS: Flow cytometry of PD with the UF-100 offers a rapid and reliable leukocyte count. Sensitivity of the 'bacterial' channel count in predicting positive culture exceeds the sensitivity of conventional Gram stain. Furthermore, additional semi-quantitative information is provided regarding the presence of yeasts.

Adolescent↗
PubMed2004

Creatine supplementation does not decrease total plasma homocysteine in chronic hemodialysis patients.

BACKGROUND: Hyperhomocysteinemia is present in the majority of chronic hemodialysis patients. Treatment with folic acid, vitamin B12, and vitamin B6 cannot fully normalize plasma homocysteine concentrations (tHcy). Previously we have demonstrated the tHcy-lowering effect of creatine supplementation in an animal model of uremia (Kidney Int 64:1331-1337, 2003). The present study investigates the effects of creatine supplementation on tHcy in a vitamin-repleted chronic hemodialysis population. METHODS: Forty-five hemodialysis patients receiving folic acid and vitamin B6 and B12 were included. Patients were treated with creatine (2 g/day) or placebo during 2 treatment periods of 4 weeks, separated by a washout of 4 weeks. Plasma tHcy, creatine, Kt/V(urea), folic acid, vitamin B12, and routine biochemistry were determined, as well as the prognostic inflammatory and nutritional index. RESULTS: All patients had elevated tHcy concentrations (21.2 +/- 5.6 micromol/L). Creatine treatment resulted in increased plasma and red blood cell creatine levels, documenting uptake of creatine. Creatine did not affect tHcy concentrations. There was no relationship between plasma creatine concentrations and tHcy concentrations. No changes in body weight, routine biochemistry, nutritional status, folic acid, or vitamin B12 were observed during the study. CONCLUSION: Creatine supplementation at a rate of 2 g/day does not further decrease tHcy concentrations in chronic dialysis patients already treated with high dose folic acid, vitamin B6, and B12 supplementation.

Aged↗
PubMed2004

Effect of dietary creatine on skeletal muscle myosin heavy chain isoform expression in an animal model of uremia.

BACKGROUND: Chronic renal failure is accompanied with muscle dysfunction and myopathy, characterized by muscle weakness and increased fatigue. Myosin heavy chain (MHC) is the principal structural protein that controls the intrinsic contractile properties of striated muscle. Creatine is widely used as an ergogenic nutritional supplement in sportsmen. This study investigates the effect of creatine supplementation on MHC expression in the setting of uremic myopathy. METHODS: Male Wistar rats were either sham operated or subtotally nephrectomized and received a control diet or creatine (2% w/w)-supplemented diet. After 4 weeks of treatment, serum creatinine, creatine, urea and creatinine clearances were determined. MHC isoforms were determined electrophoretically in the extensor digitorum longus and soleus muscles. RESULTS: Creatinine clearances were lower in nephrectomized animals, but similar in creatine-supplemented and control diet animals. Nephrectomized animals had significantly higher MHC IIb and lower MHC IIx isoform expression in the extensor digitorum longus muscle compared to sham-operated animals. In the soleus muscle, MHC IIb expression was increased in nephrectomized animals. Creatine supplementation reversed the MHC transitions observed in uremia in the soleus muscle, but not in the extensor digitorum longus muscle. CONCLUSION: We observed altered expression of MHC isoforms in uremia. In uremic animals, fast MHC IIb isoforms were increased, whereas MHC I and IIx isoforms predominate in control animals. Dietary creatine supplementation reversed the altered MHC expression during uremia in slow-twitch, but not in fast-twitch muscles.

Administration, Oral↗
PubMed2004

Prohepcidin accumulates in renal insufficiency.

BACKGROUND: The understanding of iron metabolism has increased substantially during the last decade. Several new transporters and iron regulating molecules have been described. Hepcidin, a small hepatic peptide has recently been proposed as a central mediator of dietary iron absorption. We have investigated the relationship between prohepcidin, the prohormone of hepcidin, and renal function and iron status. METHODS: Forty six patients, referred for 51Cr-EDTA clearance were included in this study. Renal function was assessed by determination of serum creatinine, creatinine clearance, serum cystatin C and serum beta-trace protein. Iron status was evaluated by determination of serum iron, transferrin, transferrin saturation and serum ferritin. All determinations were performed using commercial reagents (Roche Diagnostics, Dade Behring). Serum prohepcidin was determined using an ELISA kit. RESULTS: Serum prohepcidin was found to correlate with 51Cr-EDTA clearance (r = -0.44; p = 0.005), creatinine clearance, serum creatinine, beta-trace protein and cystatin C. No significant relationship was observed between serum prohepcidin concentrations and red cell count, hemoglobin concentration or hematocrit. No significant correlation was found in this population between prohepcidin concentrations and iron status. CONCLUSION: Increased serum prohepcidin concentrations were observed with declining kidney function. We observed no relationship between red cell indices or iron status and serum prohepcidin concentrations.

Aged↗
PubMed2003

Creatine supplementation decreases homocysteine in an animal model of uremia.

BACKGROUND: Hyperhomocysteinemia is prevalent in more than 85% of patients with end-stage renal disease (ESRD) and is thought to contribute to the excess cardiovascular mortality and morbidity. Creatine is synthesized by methylation of guanidinoacetate with formation of S-adenosylhomocysteine and subsequently, homocysteine (Hcy). Creatine supplementation down-regulates its endogenous synthesis and, thus, may reduce Hcy production. The present study investigates the effect of creatine supplementation on Hcy concentrations in an animal model of uremia. METHODS: Male Wistar rats were either sham-operated and received a control diet (N = 8) or a 2% creatine-supplemented diet (N = 8), or underwent subtotal nephrectomy and received a control diet (N = 10) or a 2%-supplemented creatine diet (N = 10). After 2 weeks of treatment, total plasma Hcy, creatine, creatinine, folate, and vitamin B12 were determined, as well as hepatic folate and vitamin B12 concentrations. RESULTS: Plasma creatinine concentrations were higher in nephrectomized animals, but similar in creatine-supplemented and control diet-fed animals. Plasma Hcy was higher in nephrectomized animals but lower in creatine-supplemented nephrectomized animals compared to nephrectomized control diet-fed animals (12.1 +/- 2.4 micromol/L vs. 15.4 +/- 1.7 micromol/L; P < 0.01). Total plasma Hcy inversely correlated with plasma creatine concentrations (r =-0.39; P = 0.02). Plasma folate was higher in supplemented animals and hepatic tetrahydrofolate (THF) was higher in nephrectomized supplemented animals. Plasma vitamin B12 was similar in all groups, whereas hepatic vitamin B12 was higher in nephrectomized animals. CONCLUSION: Creatine supplementation can effectively lower plasma Hcy concentrations in an animal model of uremia and should be further investigated as a potential treatment for hyperhomocysteinemia in patients with ESRD.

Animals↗
PubMed2003

Studies on dialysate mixing in the Genius single-pass batch system for hemodialysis therapy.

BACKGROUND: The Genius single-pass batch system for hemodialysis contains a closed reservoir and dialysate circuit of 75 L dialysate. The unused dialysate is withdrawn at the top of the reservoir and the spent fluid is reintroduced into the container at the bottom. Although it has been claimed that both fractions remain unmixed during the dialysis session, no direct proof of this assumption has yet been provided. In the present study, we investigated whether contamination of the unused dialysate with uremic solutes occurred and at which time point it began. Two different dialysate temperatures were compared. METHODS: Ten chronic hemodialysis patients were dialyzed twice with the Genius system, with dialysate prepared at 37 degrees C and 38.5 degrees C, respectively. The sessions lasted 270 minutes with blood/dialysate flow set at 300 mL/min. Dialysate was sampled at 5, 60, 180, 210, 225, 230, 235, 240, 255, and 270 minutes both from the inlet and outlet dialysate line and blood was sampled from the arterial line predialysis, after 4 hours, and postdialysis. All samples were tested for osmolality, urea, creatinine, p-cresol, hippuric acid, and indoxyl sulfate. RESULTS: Uremic solutes appeared in the inlet dialysate line between 3 hours 50 minutes and 4 hours 10 minutes after the start of dialysis, corresponding to 68.6 and 74.7 L spent dialysate, respectively (37 degrees C vs. 38.5 degrees C; P = NS). No difference in the amount of removed solutes and in the serum levels was observed between 37 degrees C and 38.5 degrees C. A Kt/V of 1.17 +/- 0.20 and 1.18 +/- 0.26, respectively, was reached with the 37 degrees C and 38.5 degrees C dialysate temperature (P = NS). CONCLUSION: Contamination with uremic solutes occurred at the dialysate inlet only near the end of the session when small quantities of fresh dialysate were left in the container. Differences in dialysate temperature did not result in a different separation between used and unused dialysate, or in differences in removal of toxins or Kt/V.

Aged↗
PubMed2003

Creatine supplementation does not affect kidney function in an animal model with pre-existing renal failure.

BACKGROUND: Creatine is widely used as an ergogenic substance among athletes. Safety of prolonged creatine intake has been questioned, based upon case reports and animal data. We investigated the effect of prolonged creatine ingestion on renal function in animals with normal kidney function or pre-existing kidney failure, respectively. METHODS: Male Wistar rats were randomly allocated to four experimental groups: (i) sham-operated, control diet; (ii) sham-operated, creatine-supplemented diet (2% w/w (0.9+/-0.2 g creatine/kg body weight/day)); (iii) two-thirds nephrectomized, control diet; and (iv) two-thirds nephrectomized, creatine supplemented diet. Glomerular filtration rate was determined using inulin and creatinine clearance, together with albumin excretion, urea clearance, muscle and serum creatine and serum cystatin C concentrations. RESULTS: In contrast to previous reports, no detrimental effects of creatine supplementation on the renal function indices were observed in two-thirds nephrectomized or sham-operated animals. No differences were observed in inulin (0.28+/-0.08 vs 0.25+/-0.08 ml/min/100 g; P=NS) or creatinine clearance rates. Serum cystatin C concentration, urinary protein excretion, and albumin and urea clearance were comparable between creatine-supplemented and control-diet fed animals in both sham-operated and two-thirds nephrectomized animals. Serum creatine and intramuscular total creatine concentrations were higher in creatine-supplemented groups (P<0.05). CONCLUSIONS: Creatine supplementation at a dosage of 2% w/w for 4 weeks does not impair kidney function in animals with pre-existing renal failure or in control animals.

Albuminuria↗
PubMed2003

The analysis of carbohydrate-deficient transferrin, marker of chronic alcoholism, using capillary electrophoresis.

Carbohydrate-deficient transferrin (CDT) is currently considered to be the best available marker for the diagnosis of chronic alcoholism. A large variety of methods have been developed, demonstrating the need for standardisation. Commercially available anion-exchange chromatographic-based assays are easy to use and require no specialised, expensive instruments. However, these methods cannot identify genetic transferrin variants or the carbohydrate-deficient glycoprotein syndrome. In 1989, a capillary isoelectric focusing method was developed for quantitative measurement of CDT. Despite the optimal resolution, this method is not easily applied in a clinical routine environment due to the complexity of analysis. Capillary electrophoresis in a polymer network using coated capillaries allowed full resolution of the sialoforms of human transferrin. The drawbacks due to an expensive and time-consuming sample preparation were eliminated when a method in neat serum was developed. Capillary zone electrophoresis allowed full resolution of the transferrin isoforms with a high analytical performance in a short analysis time thanks to a strong electroosmotic flow. Genetic transferrin variants were easily detected, avoiding false-positive results. Also, using capillary zone electrophoresis, it was shown that CDT is a suitable marker of chronic alcohol abuse detection in transferrin CD (common/cathodal) variants.

Alcoholism↗
PubMed2002

Flow cytometry as a new method to quantify the cellular content of human saliva and its relation to gingivitis.

BACKGROUND: Determining the cellular content of saliva by means of conventional microscopy chamber counting is a very time-consuming and operator-sensitive procedure. This study concentrated on the use of flow cytometry to examine the cellular content of saliva. Erythrocytes, leukocytes, epithelial cells and bacteria were quantified and the results were compared with caries experience and the presence of gingivitis. METHODS: 258 uncentrifuged vortexed paraffin-stimulated saliva samples (112 males and 146 females) were analyzed with the UF-100 flow cytometer. Salivary reference values were established for erythrocyte, leukocyte, epithelial cell and bacterial count. Caries experience (DMF) and the presence of gingivitis were recorded. RESULTS: Caries experience or caries risk could not be assessed with flow cytometry. However, salivary flow cytometry may be useful in determining an individual's risk for gingivitis: a significant increase in salivary leukocytes was observed in individuals with gingivitis. At a cut-off level of 10(3) leukocytes micro l(-1) saliva, a sensitivity of 76% and a specificity of 45% was obtained. Other analytes were not significantly different between individuals with and without gingivitis. CONCLUSION: Flow cytometry of paraffin-stimulated human saliva seems a promising diagnostic or predictive tool and further investigations of diseases of the oro-pharyngeal loge, such as tonsillitis and periodontitis, should be carried out in the future.

Adult↗
PubMed2002

Discriminative value of serum amyloid A and other acute-phase proteins for coronary heart disease.

We studied the value of serum amyloid A (SAA), a first-class acute-phase protein, as a marker for coronary heart disease (CHD) in a middle-aged male population. In a working population of 16307 men (age, 35-59 years), 446 cases had a history of CHD or prominent Q:QS waves on electrocardiogram. For each case, two matched controls were investigated. SAA, measured by immunonephelometry, was correlated with other acute-phase proteins, cardiovascular risk factors, and infectious serology markers. SAA concentrations were significantly higher in the cases than in controls (P<0.05) and correlated with serum C-reactive protein (CRP) (r=0.61), plasma fibrinogen (r=0.39), serum haptoglobin (r=0.26), and body mass index (r=0.13) (P<0.001). Serum CRP is a better marker for CHD than SAA, which showed discriminative power only in a univariate model comparing highest versus lowest tertile (odds ratio, 1.39; 95% confidence interval, 1.03-1.87). Neither SAA nor other acute-phase proteins correlated with Chlamydia pneumoniae immunoglobulin (Ig)G, Helicobacter pylori IgG and IgA, and cytomegalovirus IgG. In conclusion, although SAA has a discriminative value for CHD, serum CRP is to be preferred as a first-class acute-phase reactant for detection of the disease.

Acute-Phase Proteins↗
PubMed2002

Serum cystatin C concentration compared with other markers of glomerular filtration rate in the old old.

OBJECTIVES: To assess serum cystatin C, compared with other markers of renal function, as a marker of renal function in the old old (aged 85 and older). DESIGN: A cross-sectional analysis of data obtained in medically stable people aged 70 and older in a geriatric ward at a university hospital. SETTING: University hospital in Belgium. PARTICIPANTS: Forty-eight patients (17 men, 31 women) mean age +/- standard deviation 84.4 +/- 6.3 without acute illness or overt malignancy 7 days after admission were included. Twenty-five patients were aged 85 and older. MEASUREMENTS: Blood samples and 24-hour urine collections were obtained from each patient to determine serum creatinine, serum cystatin C levels, serum albumin, and creatinine clearance. Glomerular filtration rate (GFR) was estimated using the Cockcroft-Gault formula and the Modification of Diet in Renal Study Group (MDRD) formula. On the same day, clearance of 51chromium ethylenediamine tetraacetic acid was performed in all patients as the criterion standard of GFR. RESULTS: Serum creatinine (r=0.68), serum cystatin C (r=0.62), urinary creatinine clearance (r=0.57), the Cockcroft-Gault formula (r=0.82), and the MDRD-formula (r=0.65) correlated significantly with GFR (P <.0001). Regression analysis showed that serum cystatin C and serum creatinine were comparable markers of renal function (Y=0.442 +/- 0.007 x GFR and Y=0.494 +/- 0.01 x GFR respectively). Receiver operating characteristic analysis showed a similar area under the curve for serum cystatin C and serum creatinine (P=.5) in detecting renal impairment (GFR <80 mL/min). The Cockcroft-Gault formula provides a good estimation of GFR when the GFR is less than 60 mL/min (Y=1.11 +/- 1.04 x GFR). When the GFR is greater than 60 mL/min, the Cockcroft-Gault formula underestimates GFR (Y=11.01 +/- 0.66 x GFR). In patients aged 85 and older, a slight decrease in GFR (51.8 +/- 21.3 mL/min vs 65.2 +/- 34.3 mL/min in patients aged 70-84; P=.10) is observed. This is reflected by a nonsignificant increase in serum cystatin C (P=.06), whereas serum creatinine is identical in both groups (P=.88). CONCLUSION: Serum cystatin C, serum creatinine, the Cockcroft-Gault formula, the MDRD formula, and urinary creatinine clearance are comparable markers of renal function in the overall older population. The Cockcroft-Gault formula underestimates renal function in older people with GFR greater than 60 mL/min. In our study, serum cystatin C was not superior to serum creatinine in the detection of renal impairment.

Aged↗
PubMed2002

Effect of transferrin polymorphism on the metabolism of vitamin C in Zimbabwean adults.

BACKGROUND: Transferrin is the major iron binding protein in human plasma. In black persons, the transferrin CD phenotype has been associated with alterations in certain markers of iron status. OBJECTIVE: We studied vitamin C status in a Zimbabwean population according to transferrin phenotype because vitamin C metabolism is influenced by iron-driven oxidative stress. DESIGN: The study population consisted of 150 black African adults, 90 of whom were at risk of iron overload on the basis of high dietary iron content in the form of traditional beer. Transferrin phenotypes, indirect measures of iron status, and leukocyte ascorbic acid concentrations were determined. The in vitro rate of L-ascorbic acid depletion in sera from different transferrin phenotypes was investigated. RESULTS: The transferrin phenotype frequencies of transferrin CC and CD were 0.893 and 0.107, respectively. The iron status of transferrin CC and CD subjects was similar. After adjustment for traditional beer consumption, baseline leukocyte vitamin C concentrations were significantly higher in 16 transferrin CD subjects ( +/- SE: 2.10 +/- 0.34 and 2.61 +/- 0.28 fmol/leukocyte in men and women, respectively) than in 134 transferrin CC subjects ( +/- SE: 1.65 +/- 0.11 and 1.99 +/- 0.11 fmol/leukocyte in men and women, respectively; P = 0.024). Oral administration of ascorbic acid (2.0 g every 24 h for 48 h) led to slower rises in leukocyte vitamin C concentrations in subjects with the transferrin CD phenotype than in subjects with the transferrin CC phenotype (P = 0.028). After in vitro supplementation of serum with 570 micromol vitamin C/L, the rate of L-ascorbic acid depletion was significantly lower in subjects of a transferrin CD phenotype than in subjects with the transferrin CC phenotype. CONCLUSION: Transferrin polymorphism may affect vitamin C status in blacks.

Administration, Oral↗
PubMed2002

Haptoglobin polymorphism and body iron stores.

In humans the iron status is influenced by environmental and genetic factors. Among them, the genetic polymorphism of the hemoglobin (Hb)-binding plasma protein haptoglobin (Hp) has been shown to affect iron turnover. The best known biological function of Hp is capture of free Hb in plasma to allow hepatic recycling of heme iron and to prevent kidney damage during hemolysis. In healthy males, but not in females, the Hp 2-2 phenotype is associated with higher serum iron, higher transferrin saturation, and higher ferritin than Hp 1-1 and 2-1. Moreover, serum ferritin correlates with monocyte L-ferritin content, which is also highest in Hp 2-2 subjects due to endocytosis of multimeric Hb-Hp 2-2 complexes by the recently identified Hb scavenger receptor CD163 in macrophages. This iron delocalization pathway, occurring selectively in Hp 2-2 subjects, has important biological and clinical consequences. The Hp polymorphism is related to the prevalence and the outcome of various pathological conditions with altered iron metabolism such as hemochromatosis, infections, and atherosclerotic vascular disease.

Antigens, CD↗