Search PubMed⌕ Search

Biomedical subjects

A Meulemans

Publications and source records attributed to A Meulemans.

At least 19 recordsLinked to original sources
PubMed2003

Modulation of NA-synthase activity in rat cortex using NA measurement with ultramicro carbon electrode following topical applications of pharmacological agents.

The aim of the study was to document NA, the active product of brain NA-synthase known as NO-synthase in rat cortex. NA measurements in brain extracellular fluid were performed using an ultramicro carbon electrode (0.5-2 microm) with differential pulse voltammetry. The ultramicro carbon electrode was inserted at a fixed depth (125 microm) into the frontal cortex. A constant level of neuronal NA (0.66 mM) was found in rat cortex during a few hours in the basal state. Topical applications of competitive inhibitors of brain NO-synthase (L-NNA, L-NMA, D-arginine, 1 mg ml(-1)) and a NO-donor (SNAP, 1 mg ml(-1)) resulted in a complete disappearance of NA. Simultaneous in vivo measurements of L-NNA, an electroactive inhibitor (-1.2 V vs. Ag/AgCl), and NA (-1.66 V vs. Ag/AgCl) allowed the following of the diffusion of this neuronal specific inhibitor and the simultaneous inhibition of NA synthesis. Topical addition of acetylcholine (10 microM) produced a NA increase, while bradykinin, adenosine, and hydrogen peroxide (10 microM each) resulted in the disappearance of NA. Topical addition of radical oxygen species (ROS) scavengers (oxy-hemoglobin, methylen blue, ascorbic acid and cystein, l mg ml(-1)) had no influence on NA concentrations which remained at a constant level in brain cortex. These preliminary results indicated that NA is continuously produced at a high level by neurons. Acetylcholine and vasodilatators modulated neuronal NA synthesis after topical application, but ROS had no effect.

Animals↗
PubMed2003

The effect of mechanical cleaning and thermal disinfection on light intensity provided by fibrelight Macintosh laryngoscopes.

The increased use of thermal decontamination procedures for fibrelight laryngoscope blades, to comply with international guidelines, will have considerable economical effects. We evaluated the effect of mechanical cleaning plus thermal disinfection at 90 degrees C, with or without subsequent steam sterilisation at 134 degrees C, on light intensity provided by fibrelight laryngoscopes. After mounting the blades in a special frame with a built-in light source, light intensity was measured using radiometer/photometer. In total, 14 blades provided by 11 companies were tested. The majority of fibrelight laryngoscope blades were fairly resistant to the damaging effects of machine washing plus disinfection at 90 degrees C (mean [range] reduction in light intensity 34.6%[2.1-78.3%]). However, when exposed to an additional sterilisation procedure at 134 degrees C, the majority of blades were unable to withstand the combined treatment for 300 cycles (mean [range] reduction in light intensity 86.5%[32.0-98.7%]). This study stresses the need for fibrelight laryngoscope blades which are more resistant to thermal decontamination procedures than those available at present.

Disinfection↗
PubMed2002

Survey of non-invasive ventilation for acute exacerbation of chronic obstructive pulmonary disease patients in emergency departments in Belgium.

A study was undertaken to assess the availability and use of non-invasive ventilation (NIV) for the treatment of acute exacerbation of chronic obstructive pulmonary disease (COPD) in emergency departments in Belgium. A questionnaire was sent to the head physicians of 145 emergency departments (EDs) found in the list of the Belgian College of Emergency Physicians (BeCEP). Ninety eight questionnaires were analysed (representing 68% of the questionnaires sent). NIV was used in 49% of the EDs. In the hospitals where NIV was not used, the most important reasons given were no available equipment in 71%, lack of experience with this form of treatment in 32.7%, and more time consuming for physicians and nursing staff in 22.8%. Only 3.8% of the physicians doubted the benefit of NIV treatment. In the hospitals where NIV was used, the patient was watched during the first hour by one nurse only in 19.6%, by one physician in 8.6% and by a nurse and a physician in 54.5%. NIV was used for more than 4 h in 33% of EDs. Pressure-controlled ventilation (with home respirators) was used more often than volume-controlled ventilation.

Attitude of Health Personnel↗
PubMed2002

Role of nitric oxide in the gastric accommodation reflex and in meal induced satiety in humans.

AIMS: In humans, impaired gastric accommodation is associated with early satiety and weight loss. In animals, accommodation involves activation of gastric nitrergic neurones. Our aim was to study involvement of nitric oxide in gastric accommodation and in meal induced satiety in humans. METHODS: The effect of N(G)-monomethyl-L-arginine (L-NMMA) 4 mg/kg/h and 8 mg/kg/h on gastric compliance, on sensitivity to distension, and on gastric accommodation was studied with a barostat in double blind, randomised, placebo controlled studies. The effect of L-NMMA 8 mg/kg/h on meal induced satiety was studied using a drinking test. RESULTS: L-NMMA had no significant effect on fasting compliance and sensitivity. Ingestion of a meal induced a relaxation of 274 (15) ml which was significantly smaller after L-NMMA 4 mg/kg/h (132 (45) ml; p=0.03) or L-NMMA 8 mg/kg/h (82 (72) ml; p=0.03). L-NMMA 8 mg/kg/h significantly decreased the amount of food ingested at maximum satiety from 1058 (67) to 892 (73) kcal (p<0.01). CONCLUSION: In humans, fasting gastric tone and sensitivity to distension are not influenced by nitric oxide synthase inhibition, but the gastric accommodation reflex involves activation of nitrergic neurones. Inhibition of nitric oxide synthase impairs accommodation and enhances meal induced satiety.

Adaptation, Physiological↗
PubMed2000

Electrochemical detection of nitroso-arginine as an intermediate between N-hydroxy-arginine and citrulline. An in vitro versus in vivo study using microcarbon electrodes in neuronal nitric oxide synthase and mice brain.

The aim of the study was to describe in vivo and in vitro the transformation of N-hydroxy-arginine (NHA) into nitrite and citrulline. The products of NHA oxidation were studied by electrochemical methods. Cyclic voltammetry of NHA on microcarbon electrode showed an oxidation in two steps with one electron and one proton exchanged at each step. The first step gave a radical species NHA(.) with a half-life shorter than 1 micros and the second step gave nitroso-arginine (NA) with a half-life of about 1 s (1.5 s). Coulometric oxidation of NHA gave citrulline and nitrite. Differential pulse voltammetry (DPV) in vivo and in vitro gave a peak in reduction at -1.66 V vs Ag/AgCl for NA. After reductive adsorption of NA on the microelectrode surface in mice brain it gave the two peaks of NHA in oxidation plus another peak identified as nitrite. DPV in native and recombinant rat brain nitric oxide (NO)-synthase gave NA signal permitting K(m) and V(max) determination. All these results showed that NA was synthetized by NO-synthases before the final products, citrulline and nitrite.

Animals↗
PubMed2000

A paradoxical increase in resting energy expenditure in malnourished patients near death: the king penguin syndrome.

BACKGROUND: The metabolic expression of extreme starvation on the verge of death is unknown in humans. OBJECTIVE: The objective was to compare the resting energy expenditure (REE) of 5 extremely malnourished dying patients [body mass index (in kg/m(2)): 9.77 +/- 0.1] with that of 16 less-malnourished anorexia nervosa (AN) patients. DESIGN: REE was measured by indirect calorimetry and body composition was measured by anthropometry and dual-frequency bioelectrical impedance analysis. Fasting serum insulin, thyroid hormone, and catecholamine concentrations were also determined. RESULTS: At the start of refeeding, REE was high in each of the 5 extremely malnourished dying patients, whereas it was low in the 16 AN patients (mean +/- SD: 5174 +/- 391 kJ/d compared with 3844 +/- 619 kJ/d; P < 0.05). The high REE value in the 5 extremely malnourished dying patients was associated with almost no fat mass (FM), high urinary nitrogen loss (16.4 +/- 2.9 g/d), low serum fatty acid concentrations (0.36 +/- 0.23 mmol/L), and low or normal serum insulin, thyroid hormone, and catecholamine concentrations. During the first 2-4 wk of refeeding, REE and nitrogen loss decreased, whereas fatty acid concentrations increased in each of the 4 surviving patients; REE and urinary nitrogen output increased in the 16 AN patients. CONCLUSION: In malnourished persons near death, there is an increase in REE and in protein catabolism. The reason for this increase is unknown but could relate to consumption of the last mobilizable muscle mass and to diseased cellular membranes.

Adult↗
PubMed1999

Multicenter trial of the quantitative BTA TRAK assay in the detection of bladder cancer.

BACKGROUND: Human complement factor H-related protein (hCFHrp) is produced by several bladder cancer cell lines and may be useful as a cancer marker. The aim of this study was to compare urinary hCFHrp and cytology for the detection of bladder cancer found by cystoscopy in patients with suggestive signs, symptoms, or preliminary test results. METHODS: The BTA TRAK assay, a quantitative enzyme immunoassay for the bladder tumor-associated antigen in urine, was compared with exfoliative cytology in 220 patients (155 men, 65 women; mean age, 64.2 years) presenting with signs, symptoms, or preliminary diagnostic results suggestive of this disease. Cystoscopy was the standard of detection. RESULTS: In the 100 patients found to have bladder cancer, the overall sensitivities of the BTA TRAK assay (at a previously determined decision threshold of 14 kilounits/L) and cytology were 66% (66 of 100) and 33% (33 of 100), respectively (P <0.001). The BTA TRAK assay proved to be statistically more sensitive than cytology for tumor grades I and II and for stage Ta and T1 tumors. In contrast, the overall specificity of the BTA TRAK assay in the 120 patients without cystoscopically confirmed bladder cancer was 69% (83 of 120) and that of cytology was 99% (119 of 120; P <0.001). The specificity of the BTA TRAK assay was higher in patients without benign or malignant genitourinary disease other than bladder cancer (76%; n = 89) than in patients with these conditions. When the BTA TRAK assay and cytology were used together such that a positive result in either test was scored as positive and the results compared with those of the BTA TRAK assay alone, increases in overall sensitivity and equivalent specificity were observed. CONCLUSION: Because of its relatively high sensitivity, the BTA TRAK assay could complement cytology as an adjunct to cystoscopy in the diagnosis and follow-up of most patients with bladder cancer.

Adult↗
PubMed1998

Effect of psyllium on gastric emptying, hunger feeling and food intake in normal volunteers: a double blind study.

OBJECTIVE: To assess whether psyllium, a soluble dietary fibre, could, at an acceptable dose (7.4 g), delay gastric emptying of a low-calorie meal, and reduce hunger feeling and energy intake, without requiring intimate mixing with the meal. DESIGN: A double blind randomized cross over study with 14 normal volunteers, to evaluate the effect of this dose of psyllium on postprandial serum glucose, triglycerides and insulin levels, and on gastric fullness, hunger feeling and food intake. METHODS: Gastric emptying was measured using a standard double-radiolabeled 450 kcal meal and feelings by visual analogic scales. The postprandial serum glucose, triglycerides and insulin levels were also determined. RESULTS: No delay in the gastric emptying of the solid and liquid phases of the meal was observed with psyllium. After the meal, hunger feelings and energy intake were significantly lower during the psyllium session than during the placebo session (13% and 17% lower respectively; P < 0.05). Postprandial increase in serum glucose, triglycerides and insulin levels was less with psyllium than with placebo (P < 0.05). CONCLUSIONS: Psyllium reduces hunger feelings and energy intake in normal volunteers at reasonable dose and without requiring mixing with the meal. It does not act by slowing down the gastric emptying of hydrosoluble nutrients, but by increase in the time allowed for intestinal absorption, as suggested by the flattening of the postprandial serum glucose, insulin and triglycerides curves.

Adolescent↗
PubMed1998

Quantitative autoradiography using a radioimager based on a multiwire proportional chamber.

Determination of the biodistribution of radiopharmaceuticals is an important issue for the evaluation of their performance in diagnosis and therapy. In this study, we evaluated a digital radioimager (RI) based on a multiwire proportional chamber for quantitative autoradiography (AR). The RI allows direct detection of electronic emissions of gamma emitters. Its qualitative and quantitative performances were tested on 99mTc and (111)In labelled sections and compared with conventional film AR. Linearity of count rate versus activity was verified over a 104 range of activity. As compared with film AR, a substantial improvement of the detection limit was obtained even for acquisition periods up to 20 times less than film exposure times. We provided the basis for quantitative analysis with tissue equivalent paste standards: the 99mTc and (111)In RI counting efficiencies were respectively 1.19% and 2.35%. We illustrated the respective values of RI and film AR in two rat studies: 99mTc-DMSA in kidney and dual-isotope 99mTc-MIBI and (111)In-antimyosin in heart. Calculated activity concentrations on sections of rat organs confirmed good correlation to gamma counting (deviation less than 12%). We suggest RI as a convenient technique for fast localization of single or dual-isotope tracers and determination of activity distribution.

Animals↗
PubMed1998

Clearance of free and total serum PSA after prostatic surgery.

INTRODUCTION: Although the biology and sites of secretion of PSA are well known, its pharmacokinetics are still unclear. This study analyzes the differences between the clearance of total and free serum PSA following open surgery for BPH and radical prostatectomy. METHODS: Free and total PSA were measured in 27 patients submitted to radical prostatectomy for clinically localized prostate cancer (group I) and in 27 patients submitted to open surgery for BPH (group II). In both groups, the clearance of free and total PSA was studied. RESULTS: Group I-the mean half-life was 1.416 +/- 0.723 days for free PSA and 2.43 +/- 0.688 days for total PSA. After prostate removal, free PSA showed a marked increase. Group II-the mean half-life of free PSA was 2.157 +/- 1.792 days and 3.391 +/- 2.337 days for total PSA. CONCLUSIONS: The increase in free PSA shortly after manipulative procedures of the prostate was higher than the increase in total PSA. Serum clearance of free PSA after eradicative prostatic surgery was related to the indication and type of procedure used.

Aged↗
PubMed1996

Determination of N-nitroso-L-arginine in rat brain extracts by capillary electrophoresis using photodiode-array detection.

N-Nitroso-L-arginine was described as one of the products of L-arginine metabolism in biological media. A simple and rapid method to determine its concentration in rat brain was developed. Capillary electrophoresis with a photodiode-array detector was used at 254 nm, permitting the quantification of N-nitroso-L-arginine. The detection limit in biological solution was 1 microgram/ml.

Animals↗
PubMed1995

[Prostate specific antigen. Clinical applications of ultrasensitive assay].

Recent progress in the techniques used to assay prostate specific antigen (PSA) have made this diagnostic tool even more useful in the management of patients with cancer of the prostate. However, although "ultrasensitive" methods can now detect minute levels, there still is no widely accepted definition of the detection threshold making it difficult to compare results reported with the different techniques. Ultrasensitive assay is particularly interesting in patients who have had radical prostatectomy, offering complementary information to the pathology examination of the surgical specimen. Used as a tool for following disease course after surgery, ultrasensitive PSA is currently the most sensitive measure of disease recurrence. Ultrasensitive assay can also give an evaluation of the effect of post-surgery complementary radiotherapy. Inversely, it adds no further information compared with regular assay before surgery. Thus, ultrasensitive assay is not indicated for differential diagnosis or screening programmes but is a valuable tool for evaluating the effectiveness of curative surgery or exclusive curative radiotherapy.

Humans↗
PubMed1995

Clearance of serum PSA after open surgery for benign prostatic hypertrophy, radical cystectomy, and radical prostatectomy.

OBJECTIVE: To study the clearance of serum prostate-specific antigen (PSA) after several types of prostatic tissue ablation. METHODS: Serum PSA levels were measured (YANG Proscheck ultrasensitive assay) just before surgery, immediately after specimen removal, then twice weekly for 5 weeks or until it was undetectable (< 0.05 ng/ml) in patients undergoing radical cystoprostatectomy for bladder cancer (n = 10), or radical prostatectomy for T1 T2 prostate cancer (n = 18) and daily for 6 days after open surgery for benign prostatic hypertrophy (BPH) (n = 10). RESULTS: Open enucleation for BPH: the immediately postoperative PSA level was 6 times its preoperative value. It decreased following a monoexponential curve with a very short half-life of 0.55 +/- 0.39 days, range (0.14-1.3), reaching a value lower than the preoperative level in all cases, except one by day 3. After radical cystoprostatectomy: the decrease of serum PSA is monoexponential with a half life of 1.92 +/- 1.2 days (0.57-4.24) reaching undetectable level (< 0.05 ng/ml) in all patients by day 21. After radical prostatectomy: 11/18 patients (61%) showed a one-component exponential decrease in PSA with a half-life of 2.5 +/- 1.33 days (range 0.97-4.6 days), and 7/18 showed a two-component exponential decrease with a first half-life of 0.94 +/- 0.8 days and a second of 7.62 +/- 6.35 days); 100% of the patients reached undetectable serum PSA by day 28 in the first group compared to 14.2% of the patients with a two component exponential decrease (P < 0.01). There was no difference between these groups as far as preoperative PSA levels and specimen pathology were concerned. CONCLUSION: Serum clearance of PSA after extirpative prostatic surgery is closely related to the type and indication of procedure used. Radical cystoprostatectomy is probably the best model in which to study the pharmacokinetics of PSA.

Cystectomy↗
PubMed1995

A nitric oxide synthase activity is involved in the modulation of acetylcholine release in Aplysia ganglion neurons: a histological, voltammetric and electrophysiological study.

The role of nitric oxide or related molecules as neuromodulators was investigated in the buccal and the abdominal ganglia of the mollusc Aplysia californica. In a first step we showed that reduced nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry and specific nitric oxide synthase immunohistochemistry labelled the same neurons and fibres in both ganglia, pointing to the presence of a neuronal nitric oxide synthase. In a second step, we performed voltammetric detection of nitric oxide-related molecules using a microcarbon electrode in a reduction mode. A peak identified as N-nitroso-L-arginine was detected at -1.66 V in both ganglia. The identification of this compound as a product of endogenous nitric oxide synthase activity was reinforced by the fact that its peak amplitude was decreased in the presence of NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthase, and increased with its substrate, L-arginine. An additional proof of a nitric oxide synthase activity was the detection of nitrites and nitrates in high concentrations (millimolar range) by capillary electrophoresis. We also showed that these nitric oxide-related molecules modulated acetylcholine release at two identified synapses in these ganglia. L-Arginine decreased acetylcholine release at the inhibitory synapse (buccal ganglion), whereas it increased acetylcholine release at the excitatory synapse (abdominal ganglion). The nitric oxide synthase inhibitors, N omega-nitro-L-arginine and NG-monomethyl-L-arginine, had opposite effects. Moreover, the exogenous nitric oxide donor, 3-morpholinosydnonimine hydrochloride mimicked the effects of L-arginine on both inhibitory and excitatory cholinergic synapses. The identification of two cholinergic synapses where nitric oxide affects acetylcholine release in opposite ways provides a useful tool to study the cellular mechanisms through which nitric oxide-related molecules modulate transmitter release.

Acetylcholine↗
PubMed1995

Effect of radiation therapy after radical prostatectomy on serum prostate-specific antigen measured by an ultrasensitive assay.

OBJECTIVES: To study prospectively the impact of adjuvant radiation therapy on the serum level of prostate-specific antigen (PSA), as measured by an ultrasensitive Yang Proscheck assay in patients with detectable serum PSA and a negative metastatic survey after radical prostatectomy for T1 or T2 prostate cancer. METHODS: Seventeen patients had a detectable serum PSA (2.40 +/- 2.1 ng/mL; range, 0.5 to 10) by the Yang polyclonal assay 2 to 71 months after radical prostatectomy for P2N0 (2 patients) or P3N0 (15 patients) prostate cancer. Metastatic workup (bone and computed tomography scan) was negative; 9 of 17 patients had a local recurrence documented by a positive biopsy of the vesicourethral anastomosis. All patients were treated by external radiotherapy, receiving 65 Gy on the prostate fossa over 5 weeks for an assumed low volume residual disease. Patients were followed up by determination of serum PSA every 3 months, using the Yang ultrasensitive assay for a mean duration of 14.4 months. RESULTS: In 17.6% of the patients (3 of 17) PSA became undetectable (less than 0.05 ng/mL) after radiotherapy. Radiotherapy had no impact on PSA in 35.3% (6 of 17). PSA decreased after radiation therapy within 6 months in 47.1% (8 of 17) and for up to 12 months in 2 patients, with a nadir of 0.28 ng/mL. All patients in this group experienced a secondary rise in PSA a mean of 10.6 months (range, 6 to 18 months) after radiotherapy. CONCLUSIONS: External radiotherapy has a limited impact on residual disease after radical prostatectomy, as assessed by its impact on PSA.

Follow-Up Studies↗
PubMed1995

Intralipid-induced gastric relaxation is mediated via NO.

UNLABELLED: In vitro, nitric oxide (NO) has been shown to be the neurotransmitter responsible for gastric relaxation. In vivo gastric relaxations can be controlled via reflex pathways originating in the duodenum. The aim of this study was to determine whether NO was involved in gastric relaxation in vivo in conscious dogs induced by intraduodenal administration of intralipid. Gastric tone was monitored with a flaccid bag introduced into the stomach via a gastric cannula and connected to a barostat. Intralipid administration into the duodenum caused a gastric relaxation (420 +/- 11 ml, n = 6) sensitive to inhibition by nitro-L-arginine (L-NNA) (5 mg kg-1 i.v.). This inhibitory effect of L-NNA was reversed by L-arginine (100 mg kg-1 i.v.). IN CONCLUSION: intraduodenal administration of intralipid induces a gastric relaxation via a NO-dependent mechanism.

Animals↗