A quantitative approach to ecotone creation for nature reserve design.
Conference (1999)Detailed reference viewed: 4 (0 ULg)
A quantitative approach to ecotone creation for nature reserve design.
Bogaert, Jan ; ; et al
in The European dimension in ecology, perspectives and challenges for the 21th century (1999)Detailed reference viewed: 6 (1 ULg)
A quantitative approach to land transformation processes: the case of habitat fragmentation.
Scientific conference (1999)Detailed reference viewed: 6 (1 ULg)
Quantitative approach to the conservation of a tropical seabird population in the western Indian Ocean
; ; Doucet, Jean-Louis et al
The roseate tern (Sterna dougalli) is an oceanic seabird species showing mainly a tropical distribution, with a relatively fragile status worldwide. It was still recently considered as a "near-threatened ... [more ▼]
The roseate tern (Sterna dougalli) is an oceanic seabird species showing mainly a tropical distribution, with a relatively fragile status worldwide. It was still recently considered as a "near-threatened" (IUCN red list) due to the strong decline in population trends over the last decades. For instance, the annual breeding population found on Aride Island, western Indian Ocean, has fluctuated between a high of 4,000 in the 1970's to a low of 60-1200 pairs from 2000 onwards. As a result, an intensive monitoring program was conducted on Aride between 1998 and 2006 in order to understand how environmental factors may affects this breeding population. This included the estimation of annual productivity (no of chicks fledged per pair), demographic parameters such as survival rate and recruitment (age-specific breeding probabilities), and their affecting co-factors (e.g. food availability, tick parasitism,...). We suggest that these three parameters (productivity, survival, recruitment) constitute the necessary basis to model the life-cycle of this population, and, ultimately, to provide local managers with conservations measures. [less ▲]Detailed reference viewed: 8 (2 ULg)
Quantitative approaches based on Surface-Enhanced Raman Scattering (SERS) and Surface-Enhanced Raman Chemical Imaging (SER-CI)
De Bleye, Charlotte ; Sacre, Pierre-Yves ; Dumont, Elodie et al
Conference (2014, January 20)
Surface-enhanced Raman scattering (SERS), discovered in 1978, is a recent technique enabling to circumvent the main limitations of classical Raman spectroscopy by dramatically exalting the Raman ... [more ▼]
Surface-enhanced Raman scattering (SERS), discovered in 1978, is a recent technique enabling to circumvent the main limitations of classical Raman spectroscopy by dramatically exalting the Raman scattering of the target molecules which are adsorbed or very closed to metallic surfaces while reducing the fluorescence impact on spectra . This technique combines the sensitivity of the fluorescence keeping the structural information of molecules obtained from the SERS spectrum . This last point allows to implement multiplex analyses. Moreover, it is possible to perform Surface-enhanced Raman chemical imaging (SER-CI) analyses which enable to acquire a visual representation of samples combining spectral and spatial measurements. Therefore SERS could become an attractive technique in numerous fields such as pharmaceutical and biomedical research. In this context, the feasibility of developing quantitative approaches using SERS and SER-CI on a pharmaceutical model was studied. The aim was to develop methods allowing the quantification of 4-aminophenol (4-AP) in a pharmaceutical formulation based on paracetamol. 4-AP is the main impurity of paracetamol and is actively research because of its toxicity. This pharmaceutical model was first investigated using SERS and a quantitative method enabling to quantify 4-AP from 3 to15 µg/mL was developed and validated using the standard addition method as a calibration method . From these results, the possibility of developing a quantitative approach using SER-CI was investigated. Tablets based on paracetamol comprising different concentrations of 4-AP were prepared. Different ways to cover the sample surface by the SERS substrate were tested and a homogeneity study was performed to improve the repeatability of SER-CI analyses. Different spectral intensity normalizations were also tested in order to optimize the SER-CI method. Finally, a quantitative approach using SER-CI was developed allowing the quantification of 4-AP from 0.025% to 0.2% (w/w) in paracetamol tablets . This first quantitative approach could pave the way to quantitative analysis of small molecules using SER-CI in complex matrices. References  P.L. Stiles, J.A. Dieringer, N.C. Shah, R.P. Van Duyne, Annu. Rev. Anal. Chem. 1 (2008) 601-626.  R.F. Aroca, R.A. Alvarez-Puebla, N. Pieczonka, S. Sanchez-Cortez, J.V. Garcia-Ramos, Adv. Colloid Interface Sci. 116 (2005) 45-61.  C. De Bleye, E. Dumont, E. Rozet, P.-Y. Sacré, P.-F. Chavez, L. Netchacovitch, G. Piel, Ph. Hubert, E. Ziemons, Talanta 116 (2013) 899-905.  C. De Bleye, P.-Y. Sacré, E. Dumont, L. Netchacovitch, P.-F. Chavez, G. Piel, P. Lebrun, Ph. Hubert, E. Ziemons, J. Pharm. Biomed. Anal. (in Press) [less ▲]Detailed reference viewed: 105 (3 ULg)
Quantitative aspect of serum myoglobin changes in acute myocardial infarction
Chapelle, Jean-Paul ; Albert, Adelin ; et al
in European Heart Journal (1981), 2(A), 213Detailed reference viewed: 10 (1 ULg)
Quantitative aspects of serum myoglobin changes in acute myocardial infarction
Chapelle, Jean-Paul ; Albert, Adelin ; et al
Poster (1981, September)Detailed reference viewed: 3 (0 ULg)
Quantitative aspects of the spatial distribution and morphological characteristics of the sea bass (Dicentrarchus labrax L.; Teleostei, Serranidae) trunk lateral line neuromasts.
Faucher, Karine ; ;
in Brain, Behavior & Evolution (2005), 65(4), 231-43
The results presented herein report quantitative data relative to the distribution and morphological characteristics of both types of neuromasts encountered on the trunk lateral line of the sea bass ... [more ▼]
The results presented herein report quantitative data relative to the distribution and morphological characteristics of both types of neuromasts encountered on the trunk lateral line of the sea bass (Dicentrarchus labrax, L.). These data were obtained from scanning electron micrographs. They indicate that, as expected, each modified scale of the sea bass possessed a single canal neuromast with long axis oriented parallel to the fish's long axis. In contrast to several fish species, two thirds of superficial neuromasts observed herein were oriented perpendicular to the fish's long axis. However, whatever the main orientation of superficial neuromasts, two thirds of their hair bundles were oriented parallel to the long axis of the animal with approximately half of them in the direction of the head. Similar ratios were observed for canal neuromasts whatever the area of the maculae: central or peripheral. For both types of neuromasts it was not possible to clearly distinguish a paired organization of hair bundles with opposing polarities. Superficial neuromasts on each trunk canal scale were located on either the dorsal or ventral side of the canal and appeared to be distributed along the trunk lateral line with a higher probability to be encountered closer to the operculum. The frequency of presence and the average number of superficial neuromasts per scale increased with fish size. We observed a size gradient for canal neuromasts between the operculum and caudal peduncle. This gradation was correlated with a reduction of the width of the central area of the canal segment. Canal neuromasts were always localized in the larger portions of the canal segments. Taken together, these results point out some specific features associated with the sea bass trunk lateral line. With the previous report, they establish the first full description of the trunk lateral line of sea bass and will be useful for upcoming experiments regarding the function of the two types of neuromasts. [less ▲]Detailed reference viewed: 24 (2 ULg)
Quantitative assessment by western-blot of proteins expressed by different cell types involved in inhibition and promotion of regeneration in the lesioned spinal cord.
; Martin, Didier ; Leprince, Pierre et al
Conference (1995, September 21)Detailed reference viewed: 5 (0 ULg)
Quantitative Assessment of Aerial Ammonia Toxicity to the Nasal Mucosa by Use of the Nasal Lavage Method in Pigs
; Gustin, Pascal ; et al
in American Journal of Veterinary Research (1994), 55(9), 1335-1340
Effects of atmospheric ammonia (NH3) on the nasal mucosa and somatic growth were investigated in pigs exposed to 4 NH3 concentrations (0; 25; 50; and 100 ppm) for 6 days in a specifically designed air ... [more ▼]
Effects of atmospheric ammonia (NH3) on the nasal mucosa and somatic growth were investigated in pigs exposed to 4 NH3 concentrations (0; 25; 50; and 100 ppm) for 6 days in a specifically designed air-pollutant exposure chamber. Nasal lavage (NAL) was applied to quantify the ammonia-induced inflammatory response by measuring the number of neutrophils and the albumin (porcine serum albumin) concentration in the NAL liquid. In control pigs, these variables remained unchanged throughout the exposure period. In all other groups, an important ammonia concentration-related increase was recorded. The equation of the linear regression line established between the mean values of the number of neutrophils (x 10(3)) per milliliter of NAL liquid (y) recorded at the end of the exposure period and the ammonia concentrations (ppm) was: y = 69.7 + 3.3 [NH3] (r = 0.979; P < 0.020). The increase in the neutrophil count was significant (P < 0.05) at concentrations as low as 25 ppm. For albumin concentration nanograms per milliliter, the corresponding equation was: y = 574 + 14.3 [NH3] (r = 0.953; P < 0.045). However, the first significant change (P < 0.05) in this variable was only obtained for the higher concentration (100 ppm). In exposed pigs, a concentration-related depression of somatic growth was observed. The equation of the regression line plotted relating the individual values of the changes in body weight gain recorded over the exposure period expressed as percentage of the initial body weight (y) and the ammonia concentration was: y = 3.507-0.203 [NH3] + 0.001 [NH3]2 (r = 0.55; P < 0.010).(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]Detailed reference viewed: 22 (0 ULg)
Quantitative assessment of erythropoiesis and functional classification of anemia based on measurements of serum transferrin receptor and erythropoietin.
Beguin, Yves ; ; et al
in Blood (1993), 81(4), 1067-76
We evaluated the quantitative value of a simple model of erythropoiesis, based on the basic assumptions that the red blood cell (RBC) mass determines erythropoietin (Epo) production, which in turn ... [more ▼]
We evaluated the quantitative value of a simple model of erythropoiesis, based on the basic assumptions that the red blood cell (RBC) mass determines erythropoietin (Epo) production, which in turn stimulates erythropoietic activity. The RBC mass was quantitated by direct isotopic measurement (RCM), Epo production by serum Epo levels, and erythropoiesis by the ferrokinetic measurement of the erythron transferrin uptake (ETU), the serum transferrin receptor (TfR) level, and the reticulocyte (retic) index, and was completed by an evaluation of overall marrow erythron cellularity. We studied a total of 195 subjects, including 31 normal individuals, 38 patients with polycythemia, and 126 patients with various forms of anemia. Instead of only quantitating Epo and erythropoiesis in absolute terms, we also evaluated them in relation to the degree of anemia or polycythemia, and expressed the results as a ratio of observed values to values predicted from the regression equations between hematocrit (Hct) on the one hand, and Epo, TfR, and ETU on the other, obtained in a carefully selected subpopulation. The slope of the regression of TfR (as well as ETU) versus Hct was very similar to the slope of the regression of Epo versus Hct. Average EPO and TfR (as well as ETU) values predicted from the regression equations were quite comparable to observed values in most groups of subjects, with exceptions predictable from knowledge of the pathophysiology of these hematologic disorders. We identified four major patterns of erythropoiesis, ie, normal, hyperdestruction (with variants of hemolysis or ineffective erythropoiesis), intrinsic marrow hypoproliferation, and defective Epo production. Dissecting out groups of patients showed much greater heterogeneity than when patients were analyzed by group. This was particularly true in the case of a hypoproliferative component being combined with hyperdestruction, giving what we called a "mixed disorder of erythropoiesis." We conclude that the pathophysiology of anemia can be assessed by a simple measurement of Hct, retic index, Epo, and TfR levels, with Epo and TfR being more informative when expressed in relation to the degree of anemia. The model is particularly useful for detecting the presence of multiple mechanisms of anemia in the same patient. However, it has limitations inherent to the relative invalidity of TfR in iron deficiency, the imprecision of a retic count, and the difficulty in distinguishing hemolysis from ineffective erythropoiesis in some patients and in recognizing a component of hyperdestruction in hypoproliferative anemia. [less ▲]Detailed reference viewed: 33 (1 ULg)
Quantitative assessment of erythropoiesis in haemodialysis patients demonstrates gradual expansion of erythroblasts during constant treatment with recombinant human erythropoietin.
Beguin, Yves ; ; R'Zik, Samir et al
in British Journal of Haematology (1995), 89(1), 17-23
Recombinant human erythropoietin (rHuEpo) has been shown to be effective in correcting the anaemia of chronic renal failure. It has been reported that reticulocytes as well as erythroid progenitors ... [more ▼]
Recombinant human erythropoietin (rHuEpo) has been shown to be effective in correcting the anaemia of chronic renal failure. It has been reported that reticulocytes as well as erythroid progenitors increase within 1-2 weeks, with no further elevation beyond this time interval. However, the erythroblast pool is quantitatively the most important compartment of erythropoiesis, and the rate, extent and duration of the expansion of erythropoietic activity in response to rHuEpo is not known. Treatment with rHuEpo was given to 64 patients i.v. thrice weekly after haemodialysis. The effect of rHuEpo was obvious from the early elevation of reticulocyte counts, but much of this increase was due to a rapid output of shift reticulocytes which levelled off after a few weeks. Serum transferrin receptor (TfR), a quantitative measure of erythropoiesis, increased progressively over 6 weeks to reach a plateau phase at about twice baseline values. The Hct increased progressively and continued to rise steadily after the TfR plateau was reached. The speed and extent of the expansion of erythropoietic activity correlated with the later haematological response to rHuEpo. When rHuEpo was discontinued, erythropoietic activity returned progressively to baseline values, to rise again gradually when treatment was resumed. Part of the Hct increase was also due to haemoconcentration. The results indicate that changes in the various erythroid compartments vary considerably in intensity and speed, and that the erythroblast compartment in particular is slow to respond to modifications in the erythropoietin stimulus. [less ▲]Detailed reference viewed: 30 (2 ULg)
Quantitative assessment of global and regional left ventricular function with low-contrast dose digital subtraction ventriculography.
; ; Legrand, Victor et al
in Chest (1985), 87(5), 598-602
Few studies have compared the use of low-contrast dose digital subtraction ventriculography with conventional ventriculography for quantitative assessment of both global and regional left ventricular ... [more ▼]
Few studies have compared the use of low-contrast dose digital subtraction ventriculography with conventional ventriculography for quantitative assessment of both global and regional left ventricular function. Accordingly, 34 patients underwent conventional ventriculography using 36 ml of ionic contrast material and digital ventriculography (mask-mode) using 10 ml of contrast diluted in 10 ml of saline and injected over two seconds. Data from two patients were excluded because of ectopy during cineventriculography and from one because of ectopy during both studies. End-diastolic and end-systolic volumes were calculated from both studies by an area-length method and used to calculate ejection fractions. Regional wall motion was quantitated by the centerline method. Results of linear regression analysis demonstrated high correlations for all parameters (end-diastolic volume, r = 0.85; end-systolic volume, r = 0.93; ejection fraction, r = 0.92; quantitative regional wall motion, r = 0.90). Thus, low-contrast dose digital subtraction ventriculography provides an accurate assessment of both global and regional ventricular function and minimizes the required dose and inherent risks of contrast media. [less ▲]Detailed reference viewed: 5 (0 ULg)
Quantitative assessment of myocardial contractile reserve during exercise in patients with mitral valve prolapse
Lancellotti, Patrizio ; ; et al
in Circulation (2006, October 31), 114(18, Suppl. S), 707-708Detailed reference viewed: 6 (0 ULg)
A quantitative assessment of the 1998 carbon monoxide emission anomaly in the Northern Hemisphere based on total column and surface concentration measurements
; ; et al
in Journal of Geophysical Research. Atmospheres (2004), 109(D15),
Carbon monoxide abundances in the atmosphere have been measured between January 1996 and December 2001 in the high Northern Hemisphere (HNH) (30degrees-90degreesN) using two different approaches: total ... [more ▼]
Carbon monoxide abundances in the atmosphere have been measured between January 1996 and December 2001 in the high Northern Hemisphere (HNH) (30degrees-90degreesN) using two different approaches: total column amounts of CO retrieved from infrared solar spectra and CO mixing ratios measured in situ at ground-based stations. The data were averaged, and anomalies of the CO HNH burden ( deviations of the total tropospheric mass between 30degreesN and 90degreesN from the mean seasonal profile, determined as the 5 year average) were analyzed. The anomalies obtained from in situ and total column data agree well and both show two maxima, by far the largest in October 1998 and a lower one in August 1996. A noticeable decrease of the positive 1998 summer anomaly with increasing height was found. A box model was applied, and anomalies in source rates were obtained under the assumption of insignificant interannual sink variations. In August 1998 the HNH emission anomaly was estimated to be 38 Tg month(-1). The annual 1998 emission positive anomaly was 96 Tg yr(-1). Nearly all excess CO may be attributed to the emissions from boreal forest fires. According to available inventories, biomass burning emits around 52 Tg yr(-1) during the "normal'' years; therefore total biomass emissions in 1998 were as large as 148 Tg yr(-1). In August 1998, CO contribution from the biomass burning was twice as large as that from fossil fuel combustion. The results were compared to available emission inventories. [less ▲]Detailed reference viewed: 18 (6 ULg)
Quantitative Assessment of the Specific Cd4+ T Lymphocyte Proliferative Response in Bovine Herpesvirus 1 Immune Cattle
; ; et al
in Veterinary Immunology and Immunopathology (1994), 42(3-4), 275-86
We quantified the CD4+ T cell proliferation specific for bovine herpesvirus 1 (BHV-1) in peripheral blood mononuclear cells from cattle. The stimulation index as detected in proliferative assays performed ... [more ▼]
We quantified the CD4+ T cell proliferation specific for bovine herpesvirus 1 (BHV-1) in peripheral blood mononuclear cells from cattle. The stimulation index as detected in proliferative assays performed in the presence of BHV-1 antigen is highly variable in immune cattle. By using proliferative assays performed after negative selection we showed that, as expected, CD4+ T cells were the limiting cell type for antigen-induced proliferation. Neither B, gamma delta T nor CD8+ cells seemed to be involved. The limiting dilution method was established to obtain quantitative estimations, namely frequencies of specific T cells. When limiting dilution cultures were supplemented with interleukin-2 (IL-2), an IL-2 induced unspecific cell proliferation masked the specific T cell proliferation. Natural killer cells were not the major cell type involved, but CD4+ lymphocytes themselves seemed to respond to IL-2 irrespective of the presence of antigen. When cultures were performed without addition of IL-2, the frequency of BHV-1 specific proliferative T cells could be obtained by the difference between the frequency of proliferating cells calculated in the presence and absence of antigen. The method provides a sensitive and quantitative means to measure the T cell immune response to BHV-1 vaccine candidates. [less ▲]Detailed reference viewed: 13 (1 ULg)
Quantitative bacterial cultures and cytological examination of bronchoalveolar lavage specimens in the diagnosis of lower respiratory tract disease in dogs: a retrospective study of 48 cases.
Peeters, Dominique ; ; et al
in Journal of Veterinary Internal Medicine (2000), 14(5), 534-541
Cytology and quantitative bacterial cultures of lower respiratory tract secretions are widely used in human medicine to differentiate airway infection from simple bacterial colonization. A retrospective ... [more ▼]
Cytology and quantitative bacterial cultures of lower respiratory tract secretions are widely used in human medicine to differentiate airway infection from simple bacterial colonization. A retrospective study was conducted to determine the usefulness of quantitative aerobic cultures and Gram stain intracellular bacteria counts from bronchoalveolar lavage (BAL) specimens in dogs in diagnosing lower respiratory tract infection (LRTI) and to determine whether chronic bronchitis is associated with marked bacterial growth in dogs. The threshold determined to define clinically relevant bacterial growth was 1.7 x 10(3) colony-forming units per milliliter of BAL fluid. We used this threshold and found that diagnostic sensitivity and specificity were 86% and 100%, respectively. With a threshold for infection of >2 intracellular bacteria observed in any of 50 fields, microscopic examination of Gram stain BAL preparations had a sensitivity of 71% and a specificity of 97% in establishing LRTI. There was a high correlation between bacterial morphology on BAL Gram stain and bacterial cultures. Combining the results of intracellular bacteria counts from the BAL Gram stain with those from the quantitative cultures, the sensitivity in diagnosing LRTI was 87% and the specificity was 97%. BAL quantitative cultures as well as quantitating intracellular bacteria on Gram stain BAL cytology were revealed to be useful in identifying LRTI in dogs. Chronic bronchitis does not appear to be associated with marked bacterial growth in dogs. [less ▲]Detailed reference viewed: 27 (1 ULg)
Quantitative bacterial cultures and microscopic examination of bronchoalveolar lavage specimens in the diagnosis of lower respiratory disease in dogs and cats.
Peeters, Dominique ; ; et al
in Proceedings of the 8th Annual Congress of the ESVIM (1998)Detailed reference viewed: 5 (0 ULg)
Quantitative Buffy Coat Analysis Related to Adrenocortical Function in Horses During a Three-Day Event Competition
Linden, Annick ; Art, Tatiana ; Amory, Hélène et al
in Zentralblatt für Veterinarmedizin. Reihe A (1991), 38(5), 376-82
This study was carried out to investigate stress induced in a cross-country by measuring plasma cortisol and to compare the changes in cortisol level with the leucocytic changes measured with the ... [more ▼]
This study was carried out to investigate stress induced in a cross-country by measuring plasma cortisol and to compare the changes in cortisol level with the leucocytic changes measured with the quantitative buffy coat (QBC) analysis, which is a new method applicable in field conditions for the evaluation of haematological parameters in horses. Seven healthy horses competing in a national three-day event were investigated. Venous blood was sampled under resting condition, 2 min and 180 min after the completion of the cross-country and analysed for haematological parameters, plasma cortisol, protein and lactate levels. Immediately after the event, there was a significant increase in all values except in the granulocytes (Gr) to lymphocytes-monocytes (LM) ratio. 180 min after the event, all the parameters returned to their resting levels while white blood cells (WBC), Gr and Gr/LM ratio were significantly higher with respect to their resting values. A high correlation (r = 0.82) was found between the relative increase in plasma cortisol levels 2 min after exercise and the relative increase in Gr/LM 180 min after exercise. Therefore it was concluded that the Gr/LM ratio measured 180 min after exercise with the QBC analysis is a reliable index to estimate the plasma cortisol levels measured 2 min after exercise. This new technique could consequently be used in order to evaluate, in field conditions, the exercise-induced stress. [less ▲]Detailed reference viewed: 56 (3 ULg)
Quantitative capabilities of current commercial SPECT-CT systems
Bernard, Claire ; Nguyen, Daniel ; Seret, Alain
Poster (2011, October 27)
Aim: To assess the quantitative capabilities of commercial SPECT-CT systems with their full 3D iterative reconstruction which includes resolution recovery, attenuation and scatter corrections. Materials ... [more ▼]
Aim: To assess the quantitative capabilities of commercial SPECT-CT systems with their full 3D iterative reconstruction which includes resolution recovery, attenuation and scatter corrections. Materials and methods: A NEMA NU2-1994 attenuation and scatter correction accuracy phantom, a cylindrical phantom with uniform part, cold and hot rods (diameter 4-25 mm), three uniform cylindrical phantoms of different sizes were scanned on a Siemens Symbia T6, a Philips BrightView XCT and a GE Infinia Hawkeye 4. For each phantom, activity concentration was obtained from the technetium-99m activity measured with an activimeter and its water volume. Emission projections were collected for 128 angles over 360 in 128*128 matrix (pixel size of 2.7 mm) using the 140 keV system usual energy window, and standard CT attenuation protocol was executed. Full 3D iterative reconstructions (Siemens Flash3D, Philips Astonish, GE Evolution) were performed. Residual fraction (RF) in the cold inserts of the NEMA phantom, contrast recovery coefficient (CRC) in the cold and hot rods were computed from the images. Regions of interest (ROI) of different sizes (60-100% of the phantom physical size) were drawn on the three uniform phantoms to obtain a calibration factor (CF). Results: RF dropped below 4% and CRC almost stabilized after 18 iterations. Hot rod CRC were above 90% for the rods with a diameter larger than 16 mm rising above 100% in some cases. Accurate quantification was shown feasible to within 5% or even less on some systems. CF was found to depend on both the phantom and the ROI sizes used for its determination, with variation of a few percents to more than 10%. The best phantom/ROI combination was also dependent on the system. Conclusion: With a careful design of the calibration procedure, quantification with these SPECT-CT systems and 3D iterative reconstruction seems to be feasible. However partial volume effect will remain a concern when object size drops below 2 cm. [less ▲]Detailed reference viewed: 48 (14 ULg)