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Biomedical subjects

A Meulemans

Publications and source records attributed to A Meulemans.

At least 55 records · Page 3Linked to original sources
PubMed1990

Gastrointestinal decontamination for acute poisoning.

Acute poisoning remains a common cause of morbidity and even mortality in children and adults. The goal of gastrointestinal decontamination is to eliminate or to reduce the potentially life-threatening effects of the ingested poison. Methods of gastrointestinal detoxication in case of acute poisoning, such as induced emesis, gastric lavage, administration of activated charcoal and intestinal cleansing are discussed. As far as induced emesis is still concerned, only the administration of Ipecac-syrup can be retained. The controversy between emesis and gastric lavage still remains. For those toxins well adsorbed by activated charcoal, the administration of activated charcoal, followed or not by gastric lavage, is the treatment of choice. Single doses of activated charcoal can be insufficient. In certain kinds of poisoning, repeated doses of activated charcoal are advisable because of the interruption of the entero-hepatic and entero-enteric circulation. The benefit and the indications for intestinal cleansing in case of acute poisoning seem to be very limited.

Cathartics↗
PubMed1989

Measurement and clinical and pharmacokinetic implications of diffusion coefficients of antibiotics in tissues.

A method for determining diffusion coefficients of four antibiotics in extracellular tissue space according to Fick's law is described. This new method was applied to rat brain tissue and to agar. After diffusion of the antibiotic in one axis, the gradient concentration was determined with microvoltammetric electrodes. These microelectrodes (1 micron at the extreme tip) measured the free diffusible form of electroactive antibiotics in the extracellular brain space. Metronidazole, chloramphenicol succinate, cefsulodin, and piperacillin gave diffusion coefficients ranging from 0.1 x 10(-6) to 0.2 x 10(-6) cm2 . s-1 in tissue; chloramphenicol base, which is positively charged, gave a coefficient of 0.04 x 10(-6) cm2 . s-1. The coefficient ranged from 0.6 x 10(-6) to 1.2 x 10(-6) cm2 . s-1 in agar. These coefficients were used to simulate antibiotic concentrations in infectious sites and between capillaries by using a simple model of plane diffusion.

Animals↗
PubMed1989

Pharmacokinetics of cefsulodin in rat cerebrospinal fluid during experimental Pseudomonas aeruginosa meningitis.

Experimental meningitis was induced in rats with Pseudomonas aeruginosa. Bacteria were inoculated in the second ventricle. Twenty hours later cefsulodin penetration was studied in CSF by on-line cannula system which permitted sampling of CSF in the third ventricle. Comparison with healthy animals indicated breakdown of the blood-CSF barrier and high concentrations of cefsulodin were found in CSF.

Animals↗
PubMed1989

Permeability of two nitrosoureas, carmustine and fotemustine in rat cortex.

Carmustine and fotemustine were perfused using a bolus retrograde infusion into the right external carotid artery of rats. The right jugular vein gave blood samples. Using a previously described method, nitrosoureas were continuously measured in rat brain by voltammetry and in blood samples by high-performance liquid chromatography for 15 min. Cerebrovascular permeability coefficients calculated in the first 2 min were 0.9.10(-4) cm.s-1 for carmustine and 0.5.10(-4) cm.s-1 for fotemustine. These high brain permeability coefficients were compared to literature values for carmustine and other nitrosoureas determined with a radioactive procedure.

Animals↗
PubMed1988

Determination of antibiotic lipophilicity with a micromethod: application to brain permeability in man and rats.

Lipophilicity of the injectable form of some antibiotics was measured with a micromethod. The antibiotic was dissolved in a small volume (1 ml) of phosphate buffer at a physiological pH (pH = 7.4) and was extracted by a small volume of octanol (1 ml). HPLC determinations of the antibiotic were performed in the two phases. log P ranged from +1.3 for chloramphenicol to -4.3 for ceftriaxone. A linear relationship was established for a few antibiotics between the log P values found in our experiments and the log permeability calculated from data in the literature for human and rat brain. This linear relationship enabled the brain concentrations of antibiotics to be predicted in man and rats.

Animals↗
PubMed1987

Changes in serotonin concentration in a living neurone: a study by on-line intracellular voltammetry.

Intraneuronal concentration of serotonin (5-HT) and its changes were measured in live serotonergic metacerebral cells of Aplysia for several hours following neuronal stimulation, after intracellular injection of 5-HT or extracellular application of L-tryptophan, reserpine, or p-chlorophenylalanine. This was achieved by an on-line intracellular differential pulse voltammetric method using a new, needle-tipped and glass-insulated, platinum microelectrode sensitive to 5-HT.

Aplysia↗
PubMed1987

Respiratory valve for oxygen uptake measurements during swimming.

A detailed description of a respiratory valve to measure oxygen uptake while swimming is given. The effect on body drag of the addition of this equipment was measured in four subjects swimming over a range of speeds (0.9-1.9 m s-1). The respiratory valve has a low airflow resistance (29 Pa at an airflow of 8 l X s-1) and a small deadspace (30 ml). Total body drag when swimming while wearing the respiratory equipment did not differ significantly from that when swimming without the equipment. It is concluded that this respiratory valve is ideal for making valid and reliable measurements of oxygen uptake during swimming.

Evaluation Studies as Topic↗
PubMed1987

Effects of prenatal and postnatal exposure to gentamicin on renal differentiation in the rat.

Pregnant rats were injected daily, from the 10th day of gestation to term, with 75 mg/kg of gentamicin. They gave birth about 15 h later than control pregnant rats injected with saline to pups with various degrees of growth retardation. In pups born of gentamicin-treated mothers, the number of nephrons present at birth, as well as the final number of nephrons, were reduced by at least 20%. Observation of the kidneys by light microscopy showed focal tubular lesions on the mature nephrons. The intrarenal concentration of gentamicin was higher in the severely growth retarded pups than in the others. In another series of experiments, rats were given 75 mg/kg of gentamicin daily from days 1 to 13 after birth. Although under these conditions the concentration of gentamicin reached in the postnatal kidney was higher than that reached after exposure in utero, no reduction of the final number of nephrons was observed. It is concluded that administration of gentamicin to pregnant rats caused focal tubular lesions in the developing kidney and a reduced rate of early nephrogenesis. The latter was probably due to growth retardation, though a more direct effect of gentamicin on early nephrogenesis may also have been involved.

Animals↗
PubMed1987

Effect of fetal exposure to gentamicin on kidneys of young guinea pigs.

Clearance experiments were performed with young pups born of guinea pigs given a daily injection of 4 mg of gentamicin per kg (body weight) from days 48 to 54 of gestation (term, 68 days). For 3-day-old animals, the glomerular filtration rate was similar to that measured in control guinea pigs of the same age whose mothers were given saline during the same period of gestation. The same applied to fractional excretion of water, urea, total solutes, Na, K, Ca, and Mg but not to fractional phosphate excretion, which increased significantly in the gentamicin group when compared with the controls (mean +/- standard error, 21.7 +/- 4.9 versus 7.3 +/- 1.8%; P less than 0.05; n = 6 for both). The glomerular volume of the juxtamedullary nephrons diminished by about 40%, and their proximal tubule length decreased by about 20%. The glomerular volume of the superficial nephrons also diminished, by about 30%, but their proximal tubule length did not change. The gentamicin concentration was higher in the renal cortex than in the medulla (13.1 +/- 2.6 versus 5.7 +/- 2.2 micrograms/g [dry wt]; P less than 0.01; n = 6 for each). It decreased significantly from days 3 to 20 in both tissues. No functional impairment of the kidney was found in 10-day-old animals, and normal or even supranormal morphometry of the nephrons was observed in the 20-day-old animals. It is concluded that fetal exposure to gentamicin impairs proximal tubular function in the developing animal and might also adversely affect glomerular and tubular growth. However, both the functional and morphometric impairments of nephrons are transitory.

Animals↗
PubMed1987

[Diffusion of fluoroquinolones in the aqueous humor and crystalline lens].

In 53 patients undergoing cataract extraction, the authors measured pefloxacin and ofloxacin penetration in aqueous humour and lens. Cataract removal was performed at varying times after either the end of one-hour infusion of pefloxacin, ofloxacin per os in one time, or pefloxacin per os during 3 days. In the two first schemes, acme concentrations in aqueous humour are 1.45 mg/l for pefloxacin, 1.14 mg/l for ofloxacin. These concentrations reach the MIC90 of most bacteria usually involved in endophthalmia. The steady state concentrations of pefloxacin are between 6 and 7 mg/l during the first 12 h: they reach the MIC of 80% of Streptococci. There is no evidence of accumulation of pefloxacin in lens; lenticular concentrations of ofloxacin are very low and rapidly decrease.

Administration, Oral↗
PubMed1986

Measurement of active drag during crawl arm stroke swimming.

In order to measure active drag during front crawl swimming a system has been designed, built and tested. A tube (23 m long) with grips is fixed under the water surface and the swimmer crawls on this. At one end of the tube, a force transducer is attached to the wall of the swimming pool. It measures the momentary effective propulsive forces of the hands. During the measurements the subjects' legs are fixed together and supported by a buoy. After filtering and digitizing the electrical force signal, the mean propulsive force over one lane at constant speeds (ranging from about 1 to 2 m s-1) was calculated. The regression equation of the force on the speed turned out to be almost quadratic. At a mean speed of 1.55 m s-1 the mean force was 66.3 N. The accuracy of this force measured on one subject at different days was 4.1 N. The observed force, which is equal to the mean drag force, fits remarkably well with passive drag force values as well as with values calculated for propulsive forces during actual swimming reported in the literature. The use of the system does not interfere to any large extent with normal front crawl swimming; this conclusion is based on results of observations of film by skilled swim coaches. It was concluded that the system provides a good method of studying active drag and its relation to anthropometric variables and swimming technique.

Biomechanical Phenomena↗
PubMed1986

Kinetics and bactericidal effect of gentamicin and latamoxef (moxalactam) in experimental Escherichia coli endocarditis.

The pharmacokinetics of gentamicin and latamoxef (moxalactam) were examined in serum, normal heart valves, sterile cardiac vegetations and vegetations infected with Escherichia coli. Penetration of antibiotics into heart valves and vegetations was rapid; the maximum concentration was achieved in both sites at the end of a 20 min iv infusion. However, both antibiotics penetrated better into vegetations than into normal heart valves. In rabbits with left-sided endocarditis, similar antibiotic levels were found in infected vegetations after one or 22 im injections. After 11 im injections (one every 8 h) of latamoxef (15 mg/kg) the bacterial titre (cfu/g) was significantly reduced, but not nil, despite concentrations about 40 times the MBC for this antibiotic in the vegetations. Afer 22 im injections, vegetations in rabbits receiving latamoxef were sterile and were significantly reduced in those receiving gentamicin (1.5 mg/kg/im), concentrations of which in the vegetations were inferior to the MBC. Our results suggest that the in-vivo antibacterial effect depends on local antibiotic levels, kinetics of killing and duration of contact between antibiotic and bacteria.

Animals↗
PubMed1986

Penetration of aztreonam into cerebrospinal fluid of patients with bacterial meningitis.

The penetration of aztreonam into the cerebrospinal fluid was determined in 16 patients with bacterial meningitis undergoing treatment with other antibiotics. Three aztreonam doses of 30 mg/kg were infused intravenously over 30 to 45 min at 8-h intervals, first between days 2 and 4 and again between days 11 and 20 after onset of the disease. Concentrations of aztreonam in serum and cerebrospinal fluid samples obtained at 60, 90, 120, and 240 min after the third aztreonam dose were measured by high-pressure liquid chromatography. The concentrations of aztreonam in cerebrospinal fluid ranged from 3.5 to 62 micrograms/ml, depending on the sampling time and the time elapsed since the onset of the disease. These concentrations were equal to or higher than the MICs for most of the gram-negative bacilli (including Pseudomonas aeruginosa).

Adult↗
PubMed1986

Continuous sampling for determination of pharmacokinetics in rat cerebrospinal fluid.

A method for determining drug concentration relationships between plasma and cerebrospinal fluid (CSF) in rats is described. Continuous CSF samples were collected directly from the third anterior ventricle with an indwelling cannula inserted through the bregma point, and drug concentrations were determined by high-pressure liquid chromatography and radioimmunoassay micromethods. Three antibiotics with different abilities to cross the blood-CSF barrier (chloramphenicol, piperacillin, and gentamicin) were tested. This method was found to be reproducible for each drug even if the antibiotic levels were low and the sample volumes very small. Peak CSF concentrations occurred between 0.75 and 1.25 h after injection for all three antibiotics. Percent penetration values at 1 h were 50, 1.2, and 5.4% for chloramphenicol, piperacillin, and gentamicin, respectively.

Animals↗
PubMed1986

Cefsulodin penetration into rat brain: extracellular versus total concentration.

Disposition of cefsulodin (125 mg X kg-1) was studied in rat frontal cortex after intravenous injection of a bolus by two methods. In vivo voltametry and high performance liquid chromatography of cefsulodin in brain extracts gave different concentration values. The ratio of concentrations determined by the two methods was similar to the ratio of the extravascular volume to total volume. Thus, these findings evidenced the distribution of cefsulodin in the extravascular fluid of the rat frontal cortex.

Animals↗