Showing papers by "Ghent University published in 1985"

Fat Tissue: A Steroid Reservoir and Site of Steroid Metabolism

Abstract: Sex steroid concentrations and 17 beta-hydroxy-steroid dehydrogenase and aromatase activities were determined in fat tissue removed at surgery or, in order to allow comparisons in different sites, postmortem. Except for dehydroepiandrosterone (DHEA) sulfate (DHEAS), there existed a positive tissue/plasma gradient for all steroids studied (testosterone, androstenedione, DHEA, androstenediol, estrone, and estradiol), suggesting androgen uptake and estrogen synthesis in situ. Androgen concentrations did not vary according to site of origin of fat tissue, except that the DHEAS concentration was significantly lower in abdominal sc and omental fat than in breast, pericardial, or sc pubic fat. Tissue androgen concentrations were positively correlated with their plasma concentrations, but tissue and plasma estrogen concentrations were not correlated. All tissue steroid concentrations, with the exception of estradiol in men, decreased with age. Aromatase activity [androstenedione----estrone; mean maximum velocity, 7.4 +/- 3.7 (+/- SD) fmol estrone/mg protein . h] did not vary between sexes or with site of origin of fat tissue. 17 beta-Hydroxysteroid dehydrogenase activity (estradiol----estrone, mean maximum velocity 9.8 +/- 5.4 pmol/mg protein . h) was higher in fat from women than in that from men, higher in premenopausal than in postmenopausal women, and higher in omental than in sc fat. Its activity was noncompetitively inhibited in vitro by DHEA and DHEAS in near-physiological concentrations, and the enzyme activity was inversely correlated (P less than 0.001) with the tissue DHEA and DHEAS concentrations. We conclude that fat tissue is an important steroid hormone reservoir, that it is the site of active aromatase and 17 beta-hydroxysteroid dehydrogenase, and that tissue DHEA(S) may have a modulating effect on tissue estrogen production.

Protein-blotting on Polybrene-coated glass-fiber sheets. A basis for acid hydrolysis and gas-phase sequencing of picomole quantities of protein previously separated on sodium dodecyl sulfate/polyacrylamide gel.

Abstract: A procedure has been developed which allows the immobilization on glass-fiber sheets coated with the polyquaternary amine, Polybrene, of proteins and protein fragments previously separated on sodium-dodecylsulfate-containing polyacrylamide gels. The transfer is carried out essentially as has been used for protein blotting on nitrocellulose membranes [Towbin, H., Staehelin, T. and Gordon, J. (1979) Proc. Natl Acad. Sci. USA 76, 4350–4354], but is now used to determine the amino acid composition and partial sequence of the immobilized proteins. Protein transfer could be carried out after staining the proteins in the gels with Coomassie blue, by which immobilized proteins are visible as blue spots, or without previous staining, after which transferred proteins are detected as fluorescent spots following reaction with fluorescamine. The later procedure was found to be more efficient and yielded binding capacities of ± 20 μ/cm2. Fluorescamine detection was of equal or higher sensitivity than the classical Coomassie staining of proteins in the gel. Immobilized proteins could be hydrolyzed when still present on the glass fiber and reliable amino acid compositions were obtained for various reference proteins immobilized in less than 100 pmol quantities. In addition, and more importantly, glass-fiber-bound proteins could be subjected to the Edman degradation procedure by simply cutting out the area of the sheet carrying the immobilized protein and mounting the disc in the reaction chamber of the gas-phase sequenator. Results of this immobilization-sequencing technique are shown for immobilized myoglobin (1 nmol) and two proteolytic fragments of actin (± 80 pmol each) previously separated on a sodium-dodecylsulfate-containing gel.

Homogeneous interferon-inducing 22K factor is related to endogenous pyrogen and interleukin-1

Abstract: In vitro stimulation of mononuclear cells from human peripheral blood with mitogens causes the release of factors (monokines and lymphokines) which possess distinct biological activities. One such factor, termed 22K, can induce production of human beta-interferon (HuIFN-beta) in cultured human fibroblasts, thereby rendering these cells resistant to virus infection. Here we report the complete purification and partial sequencing (39 N-terminal amino acids) of this factor, whose relative molecular mass was estimated by SDS-polyacrylamide gel electrophoresis to be 17,000 (17K). In addition to an antiviral effect, the pure protein exhibits several other biological activities. Most significantly, intravenous (i.v.) injection of the factor in rabbits caused fever and granulopenia at doses of 0.1-1 microgram per kg, effects which we attribute to a monokine called endogenous pyrogen (EP). In vitro, the protein was scored as positive in a LAF (lymphocyte-activating factor) assay at 0.1-1 ng ml-1. LAF and EP are considered to be members of one family of monokines, called interleukin-1 (IL-1). For this reason, and also because the amino-acid sequence of the 22K factor is at least partially homologous to a complementary DNA-derived IL-1 sequence, we postulate that the 22K factor also belongs to the IL-1 family.

Trace elements in human body fluids and tissues.

Abstract: Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.

Identification of coagulase‐negative staphylococci from farm animals

Abstract: The species identify of 661 strains of coagulase-negative staphylococci isolated from the skin and nares of cattle, pigs, poultry, goats and sheep was determined. They belonged either to the novobiocin-sensitive species Staphylococcus hyicus, Staph. simulans, Staph. epidermidis, Staph. haemolyticus and Staph. warneri or to the novobiocin-resistant species Staph. sciuri, Staph. lentus, Staph. xylosus, Staph. cohnii, Staph. saprophyticus and Staph. gallinarum; twenty-one strains remained unidentified. The staphylococcal flora of the farm animals studied differed markedly from that associated with man; several species which do not occur in man were isolated and novobiocin-resistant strains, which occur infrequently in man, were present in large numbers in animals. Two simplified schemes for the identification of staphylococci from farm animals and man are presented.

Liquid medium additions to established tissue cultures to improve elongation and rooting in vivo

Abstract: In order to save manual labour in plant tissue propagation, we tried adding liquid media to established, exhausted cultures, instead of transplanting the tissues to a fresh medium This has been investigated for the elongation and for root induction stages with Cordyline, Philodendron, Magnolia and Spathiphyllum The salt concentration and the application time are important factors, determining the success of this method Charcoal added to the liquid stage IIIa medium eliminated the residual effects of BA applied during stage II

Capillary GC of triglycerides in fats and oils using a high temperature phenylmethylsilicone stationary phase, part I

Abstract: The analysis of triglycerides on FSOT columns coated with a phenylmethylsilicone gum opens up new perspectives in fat and oil characterization. On phenylmethylsilicone, besides a “carbon number” or CN separation, the triglycerides are also separated according to the different combinations of saturated and unsaturated fatty acids in the triglycerides.

Effect of speed of injection on induction of anaesthesia using propofol

Abstract: Sixty unpremedicated patients (30 male) were randomly allocated to three groups. They received an induction dose of propofol 2 mg kg-1 over 5, 20 or 60 s to a forearm vein. Anaesthesia was maintained with conventional inhalation anaesthetic agents. Anaesthesia was induced satisfactorily in all 20 of the patients in the 5-s group, in 19 of the patients in the 20-s group and in 18 of the patients in the 60s group. The rate of injection had a significant influence on induction time. Mean induction time increased from 21.5 to 34.7 and 50.5s, when injection time was increased from 5- to 20 to 60s, respectively. Similar induction times were found in male and female patients. There was no significant difference between the groups, in depth of anaesthesia obtained — as assessed by the eyelash reflex. Mean arterial pressure decreased to the same extent in all three groups. Two minutes after induction, mean systolic arterial pressure was reduced by 15.1, 13.5 and 19.3 mm Hg in the 5-, 20- and 60-s groups, respectively, and mean diastolic arterial pressure by 10.3, 13.2 and 13.7 mm Hg. Heart rate changes were insignificant. Apnoea of more than 10 s duration was seen frequently in all three groups, but the results suggest that the incidence was not influenced by the rate of injection. Three patients experienced mild pain at the time of injection. No major adverse reactions occurred during or after anaesthesia.

Plasma oxytocin in human pregnancy and parturition

Abstract: Oxytocin concentrations were determined in serial peripheral plasma samples collected from clinically normal women during pregnancy and labor. Measurable concentrations of this hormone were detected in all maternal plasma samples during pregnancy, but there were wide differences in values between patients. Serial samples from individual patients revealed a pattern of gradual rise of oxytocin levels with advancing gestation and the increase in concentration was statistically significant. There were no significant differences in oxytocin levels at any stage of labor, with or without epidural analgesia. Oxytocin levels at the onset of the second stage did not differ statistically from those at crowning. Comparison of cross-sectional data showed no significant difference between the mean oxytocin concentration in early labor and in late pregnancy. Oxytocin surges occurred, but not in a regular pattern. Plasma oxytocin concentration did not increase after pelvic examination, sweeping of the membranes, low amniotomy or after cervical vibration. After spontaneous vaginal delivery, umbilical arterial plasma levels of oxytocin were consistently higher than plasma concentrations from the umbilical vein. The fetal arterio-venous difference was less pronounced at elective cesarean section. At spontaneous vaginal delivery, with and without epidural anesthesia, plasma levels from the umbilical artery were significantly higher than the maternal levels. After vaginal delivery, oxytocin levels in cord plasma were significantly higher than at elective abdominal delivery. Some methodological aspects with regard to blood sampling and to plasma oxytocin radioimmunoassay procedures are discussed. From the results presented it is concluded that the human fetus can be an important source of oxytocin and that neurohumoral birth reflexes described in animals do not occur systematically in man.

Field singularities at metal-dielectric wedges

Abstract: The wedges discussed are the dielectric wedge, the metallic 90\deg corner on a dielectric plane, and the adjacent 90\deg metallic and dielectric corners. The field components perpendicular to the edge may become infinite according to a law ( 1/r^{n} ). Numerical data are given for n , and plots of lines of force of \bar{e} (or \bar{h} ) are shown.

Heavy metal contamination near major highways, industrial and urban areas in Belgian grassland

Abstract: An investigation was made of the Zn, Cu, Mn, and Pb contents in samples of soil and grass collected along highways and in fields adjoining industrial zones in Belgium. Soil contamination by Zn and Pb was quite pronounced along highways and in some cases contamination by Mn was also observed. Contamination by these heavy metals decreased rapidly with increasing distance from the highway. High values of metal accumulation in plants located near highways were observed. The accumulation of Pb was particularly pronounced. Contamination by Cu, Zn, Pb and possibly Mn in soils of some urban gardens was also recorded.

Selectivity and selectivity tuning in capillary gas chromatography

Abstract: The selection of stationary phases in capillary gas chromatography is discussed. Methyl silicone, phenyl methyl silicone, trifluoropropylmethyl silicone, biscyanopropyl silicone, and high molecular weight (HMW) polyethylene glycol are considered to be the basic phases. Selectivities and polarities between these phases are obtained by selectivity tuning. Selectivity tuning can be performed in three different ways, namely by synthesizing a tuned stationary phase, by mixing the basic phases, or by coupling capillary columns of different selectivities. In coupling capillary columns the variables are column length, β-value, temperature, and/or pressure.

Epidural sufentanil for postoperative pain relief

Abstract: An open pilot study was undertaken to evaluate the analgesic properties of epidurally administered sufentanil in the early postoperative period. After orthopaedic surgery of the lower extremity, four different groups of five adult patients each received either 15 micrograms (group 1), 30 micrograms (group 2), 50 micrograms (group 3) or 75 micrograms (group 4) sufentanil via an epidural catheter previously used for the surgical procedure. Results were satisfactory in groups 3 and 4 with very good relief of pain and a mean duration of action of 372 and 307 minutes respectively. Dosage above 50 micrograms did not seem to improve the quality or duration of pain relief, although the onset of action was faster with 75 micrograms. Sedation was always present in patients with effective analgesia. In the present study respiratory depression was not evident, but three patients complained of itching and two of urinary retention.

The pharmacokinetics of ciprofloxacin in patients with impaired renal function

Abstract: Pharmacokinetics of ciprofloxacin after single oral administration of 250 mg were studied in patients with and without renal failure. Ciprofloxacin concentrations were measured by HPLC. The elimination half-life was 8.7 +/- 0.9 h (mean +/- S.E.M.) in six renal failure patients not on haemodialysis, as compared to 4.4 +/- 0.2 h in six patients with normal renal function. The urinary recovery of unchanged ciprofloxacin was 5.3 +/- 1.7% of dose over 24 h in the renal failure patients, as compared to 37.0 +/- 3.7% in the patients with normal renal function. In haemodialysis patients, the half-life was 5.8 +/- 0.9 h on an interdialysis day, and 3.2 +/- 0.4 h during haemodialysis.

Optimal variable weighting for hierarchical clustering: An alternating least-squares algorithm

Abstract: This paper presents the development of a new methodology which simultaneously estimates in a least-squares fashion both an ultrametric tree and respective variable weightings for profile data that have been converted into (weighted) Euclidean distances. We first review the relevant classification literature on this topic. The new methodology is presented including the alternating least-squares algorithm used to estimate the parameters. The method is applied to a synthetic data set with known structure as a test of its operation. An application of this new methodology to ethnic group rating data is also discussed. Finally, extensions of the procedure to model additive, multiple, and three-way trees are mentioned.

Comparison of propofol and thiopentone for induction of anaesthesia in premedicated patients.

Abstract: Summary Thirty premedicated ASA I or II patients scheduled for minor gynaecological surgery, were randomly allocated to receive either 15 mg/kg or 2 mg/kg propofol of the new emulsion formulation, or 4 mg/kg thiopentone, given over 20 seconds Anaesthesia was successfully induced in all 30 patients The mean (SEM) induction times were for propofol 15 mg/kg 333(32) second7, for 2 mg/kg 305(27) seconds and for thiopentone 346(27) seconds The incidence of apnoeu greater than 10 seconds, was respectively 60, 80 and 80%, and the mean duration of apnoea 308(53) 371(50) and 237(50) seconds The mean systolic blood pressure decreased after propofol 15 mg/kg by 160 mmHg, after 2 mg/kg by 186 mmHg, and increased after thiopentone by 1 mmHg, 2 minutes after injection Heart rate increased significantly 2 minutes after thiopentone by an average of 151 beats/minute, but not after propogol Pain was not reported during or after the injection No major adverse reactions occurred at induction or during maintenance of anaesthesia with an inhalation agent One patient who received 2 mg/kg propofol and isoflurane vomited for 24 hours The recovery of anaesthesia after propofol induction, was quicker than after thiopentone

Influence of Age on Steroid Concentrations in Skin and Striated Muscle in Women and in Cardiac Muscle and Lung Tissue in Men

Abstract: In order to investigate whether androgen concentrations vary as a function of age in all tissues and organs and whether the sexual differences in plasma androgen levels are reflected in tissue concentrations, testosterone (T), 5 alpha-androstane-17 beta-ol, 3-one (DHT), 5 alpha-androstane-3 alpha,17 beta-diol (Adiol), and 4-androstene-3,17-dione (Adion) concentrations were measured postmortem in lung tissue and myocardium of men aged 16-87 yr. The results were compared to values obtained previously in other tissues. Similar measurements were made in various tissues (labia majora, clitoris, pubic skin, thigh skin, striated muscle) from women aged 16-87 yr. In cardiac tissue of men, T was quantitatively the most important androgen and concentrations of DHT and Adiol were low, reflecting low 5 alpha-reductase activity; in lung tissue, T and Adion were found in similar concentrations, with lower levels of 5 alpha-reduced metabolites. In both cardiac and lung tissue, androgen concentrations decreased significantly with age. In women, androgen concentrations were highest in specific androgen target tissues (labia majora, clitoris) and lowest in thigh skin and striated muscle. The ratios of the 5 alpha-saturated metabolites (DHT plus Adiol) to T or to T + Adion, respectively, parallel total androgen concentrations, whereas the Adiol to DHT ratio, a parameter of 3 alpha-reductase activity, was highest in striated muscle and thigh skin and lowest in androgen target tissues (labia majora and clitoris). In women tissue concentrations of all androgens decreased significantly with age in nearly all tissues studied. As expected tissue androgen concentrations were lower in women than in men, but in androgen target tissues such as the clitoris or labia majora, concentrations were little lower than in scrotal skin. We conclude that in both men and women androgen target tissues contain high androgen concentrations and high 5 alpha-reductase activity; moreover androgen concentrations in target tissues are similar in both sexes. In both sexes tissue androgen concentrations decreased with age in most tissues, but in target tissues the decrease was more pronounced in women than in men.

Stabilization of a class of distributional convolution equations

Abstract: This paper discusses the stabilization of a class of linear infinite-dimensional systems, described by distributional convolution equations with bounded support. In particular this includes time-delay systems containing several time-varying delays in the state and the input. The system is stabilized using a linear time-invariant memoryless feedback law, and closed-loop stability is proved by means of a classical quadratic Liapunov functional. Sufficient conditions for stabilizability and design algorithms for a stabilizing feedback amplifier matrix are derived.