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H Neels

Publications and source records attributed to H Neels.

71 records · Page 4Linked to original sources
PubMed1994

Evaluation of the REMEDi drug profiling system.

One hundred and sixteen samples for toxicological analysis (78 urines and 38 stomach contents) were analysed both with the Bio-Rad REMEDi Drug Profiling System and with a set of immunoassays and standard chromatographic procedures (HPLC, GC/NPD and GC/MS). As a screening method, REMEDi performed only moderately well, compared with immunoassays. Amphetamines and tricyclic antidepressants were detected by REMEDi in 80% and 68%, respectively, of the positive immunoassay results. Positive immunoassay screening tests were more often confirmed by the conventional chromatographic methods (80%) than by REMEDi (35%). The highest confirmation score for REMEDi was observed in the amphetamine group (9 of 12), while low scores were obtained for barbiturates (1 of 7) and benzodiazepines (13 of 75). However, in these samples REMEDi detected 53 additional compounds, which were neither reactive in the immunoassay screening tests, nor detected by the standard chromatographic procedures. These results clearly demonstrate that REMEDi can be a useful complementary technique in the clinical toxicology laboratory, since it expands the range of drugs covered by the immunoassays and provides a rapid, preliminary report in emergency situations.

Chromatography, High Pressure Liquid↗
PubMed1992

Spuriously low concentrations of serum iron measured with generation 14 Kodak Ektachem slides: prevalence, possible causes, and partial improvement with generation 16 slides.

For sera with iron (Fe) concentrations < 4 mumol/L, Kodak Ektachem slides Generation (GEN) 14 (without ascorbic acid) yielded systematically lower results for Fe than did liquid Ferrozine-based reagents from Baker containing ascorbic acid (10 g/L, final concentration) and adapted to Cobas-Bio. During an 8-month comparison period, outliers (defined as [Fe]Cobas - [Fe]Kodak > 4 mumol/L) were seen in 21 of the 8731 sera (0.24%) tested, corresponding to < 5% of the sera with [Fe]Kodak < 4 mumol/L. In vitro addition of ascorbic acid and (or) Fe identified at least two types of outliers: type 1 (approximately 70%), characterized by [Fe]Kodak > 0.4 mumol/L, by (supra)normal Fe recovery in Kodak slides in the presence or absence of ascorbic acid (10 g/L), and by between-method differences in serum Fe (Cobas - Kodak) that were significantly correlated with serum Zn content (P < 0.0004); and type 2 (approximately 30%), tentatively ascribed to contamination by EDTA, with serum Fe by Kodak < 0.4 mumol/L and Fe recovery near 0%, both of which could be significantly and dose-dependently increased by addition of ascorbic acid (5-20 g/L). For both types of outliers, flameless atomic absorption spectrometry (AAS) yielded results that were significantly higher than concentrations by Kodak with GEN 14. Use of GEN 16 slides (containing ascorbic acid) improved concordance of Kodak results with Cobas, and hence with flameless AAS, for both types of outliers; abolished Zn dependency of results; and increased Fe results in sera with type 2 outliers, although these remained substantially lower than by Cobas. However, like other ascorbic acid-containing reagents, GEN 16 slides were more sensitive to interference by dextran-bound Fe, as assessed during in vitro addition experiments and comparisons involving samples from Fe-dextran-treated patients. GEN 16 slides are hence expected to more frequently overestimate the physiologically available protein-bound Fe in hemodialysis patients. In hospital laboratories, this new interference will probably arise more frequently than the spuriously low results with GEN 14, hence warranting further efforts in optimizing Fe slides.

Ascorbic Acid↗
PubMed1991

Priming solutions for cardiopulmonary bypass: comparison of three colloids.

The present study was designed to compare the differences in the clinical effects of three colloidal solutions, albumin, urea-linked gelatin, and succinyl-linked gelatin, when used as priming fluids for cardiopulmonary bypass (CPB) under alpha-stat conditions. A consecutive series of 105 patients scheduled for cardiac surgery were randomized into three identically managed groups, except for the CPB prime. Variables relating to acid-base status, oncotic activity, metabolism, coagulation, and postoperative evaluation were measured. Marked differences in acid-base status, colloid osmotic pressure, additional prime requirements, blood lactate, urine output, and the need for buffer solutions occurred among groups, with the succinyl-linked gelatin group having better results than the other groups. Changes in hemodynamics, oxygen consumption, and blood-glucose levels during CPB did not vary among groups. There were also no important intergroup differences in hematologic and clotting variables or postoperative parameters such as blood loss or use of blood products. Electrolyte changes were similar except for a significant increase in ionized calcium that occurred in the urea-linked gelatin group after bypass. The results indicate that succinyl-linked gelatin is an adequate and safe alternative to human albumin for use as a colloid during CPB under alpha-stat conditions.

Acid-Base Equilibrium↗
PubMed1988

Prognostic value of gastric intramural pH in surgical intensive care patients.

Gastric intramural pH (pHi), which has been shown to reflect the adequacy of oxygenation in peripheral tissue beds, was measured in acutely ill surgical patients in order to evaluate its value as a prognostic factor and its relation to the sepsis score. Fifty-nine surgical patients were studied on ICU admission. The stomach wall pH was calculated from the PCO2 in gastric juice and arterial bicarbonate concentration using the Henderson-Hasselbalch equation. A fall in tissue pH less than 7.32 was taken as an indication of inadequate tissue oxygenation. Patients with sepsis scores greater than 10 were considered septic. Hospital and short-term (within 72 h of admission) mortality rates were determined. A significantly higher short-term mortality rate was observed in patients having a pHi less than 7.32 (37% vs. 0%, p less than .005). Most (90%) of the septic patients had a pHi less than 7.32. The short-term mortality rate was the highest (50%) in the septic group. In this group also, a linear correlation was found between pHi and the sepsis score (r = -.43, p less than .01). Gastric pHi, however, offered no prediction for the long-term outcome.

Adult↗
PubMed1986

Kininase II of human seminal fluid: kinetics and inhibition.

The activity of kininase II in crude human sperm was measured continuously by measuring the hydrolysis of a blocked tripeptide 3-(2-furylacryloyl)-L- phenylalanyl-glycyl-glycine (1 mmol/l). Mean seminal plasma activity was 335 +/- 61 U/g protein; the Km was 0.7 mmol/l; pH optimum was 8.8 in a 50 mmol/l HEPES buffer and the chloride optimum was 300 mmol/l. This male genital tract enzyme is inhibited by several kininase II inhibitors. Captopril (SQ 14225) showed IC50 = 1.6 X 10(-8) mol/l, with a competitive pattern (Ki = 7.3 X 10(-9)). 3-(Mercaptomethyl)-oxo-piperidineacetic acid showed the same kind of inhibition with an IC50 = 1.8 X 10(-6) mol/l (Ki = 6.8 X 10(-7) mol/l). Enalapril diacid was the most potent inhibitor and had an IC50 of 4.1 X 10(-9) mol/l and showed a mixed competitive and non-competitive inhibition (Ki = 10(-9) mol/Ki' = 9.5 X 10(-10) mol/l). These in vitro inhibition data suggest that, in vivo, such drugs may effect the function of kininase II in the male reproductive system. The observed 50% inhibition constants are comparable to those observed in lung enzyme suggesting similar kinetic properties.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1985

Tripeptidyl carboxypeptidase activity of angiotensin-converting enzyme in human tissues of the urogenital tract.

The tripeptidyl carboxypeptidase activity of angiotensin-converting enzyme (EC 3.4.15.1) has been determined in several human tissues of the urogenital tract. Benzoyl-glycyl-L-seryl-L-prolyl-L-phenylalanine was used as substrate. The cleaved benzoyl-glycine was measured by means of high-performance liquid chromatography. Results obtained showed a high enzymatic activity for seminal plasma, vesicula seminalis and benign prostatic hyperplasia. Normal prostate and in particular prostatic adenocarcinoma have low enzymatic activity. The activity of the enzyme is sensitive to inhibition by the angiotensin-converting enzyme inhibitor captopril.

Adenocarcinoma↗
PubMedDate not supplied

Inflammatory markers in younger vs elderly normal volunteers and in patients with Alzheimer's disease.

BACKGROUND: Recently it has been reported that activation of the inflammatory response system (IRS) may play a role in the aging process and in the pathogenesis of the degenerative changes associated with Alzheimer's disease (SDAT). The aims of the present study were to examine the peripheral IRS in normal aging and in SDAT patients. METHODS: Serum zinc (Zn), total serum protein (TSP), albumin (Alb), SP electrophoresis, and serum interleukin-6 (IL-6) and the stimulated production of tumor necrosis factor-alpha (TNFalpha) were determined in younger versus elderly healthy subjects and in SDAT patients vs. age-matched, healthy volunteers. RESULTS: Serum Zn and Alb were significantly lower in elderly than in younger healthy volunteers and were significantly and inversely correlated with age. The production of TNFalpha was significantly higher in elderly than in younger healthy volunteers and was significantly and positively correlated with age. In SDAT patients, no significant changes in serum Zn or TNFalpha production could be found. Serum Alb was significantly lower and serum IL-6 and the alpha1 and alpha2 globulin fractions significantly higher in SDAT patients than in controls. CONCLUSIONS: Activation of the IRS appears to accompany the normal aging process, i.e. lower serum Zn and Alb and increased TNFalpha production, as well as SDAT, i.e. lower serum Alb and increased serum IL-6 and alpha1 and alpha2 globulin fractions. The findings suggest that not all indicators of IRS activation in SDAT are related to those of the normal ageing process.

Adult↗